TEM investigation of ductile iron alloyed with vanadium.

PubMed

Dymek, S; Blicharski, M; Morgiel, J; Fraś, E

2010-03-01

This article presents results of the processing and microstructure evolution of ductile cast iron, modified by an addition of vanadium. The ductile iron was austenitized closed to the solidus (1095 degrees C) for 100 h, cooled down to 640 degrees C and held on at this temperature for 16 h. The heat treatment led to the dissolution of primary vanadium-rich carbides and their subsequent re-precipitation in a more dispersed form. The result of mechanical tests indicated that addition of vanadium and an appropriate heat treatment makes age hardening of ductile iron feasible. The precipitation processes as well as the effect of Si content on the alloy microstructure were examined by scanning and transmission electron microscopy. It was shown that adjacent to uniformly spread out vanadium-rich carbides with an average size of 50 nm, a dispersoid composed of extremely small approximately 1 nm precipitates was also revealed.

Innovative coating of nanostructured vanadium carbide on the F/M cladding tube inner surface for mitigating the fuel cladding chemical interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yong; Phillpot, Simon

300oC and 500 oC, respectively. The coating layer contains both carbon and vanadium elements as quantified by WED, and the phases mainly consist of a mixture of V2C and VC, which was confirmed using X-ray diffraction patterns. In addition, the ratio between V and C varies with processing temperature, and it was observed that a higher temperature promotes the carbon adsorption and increases thickness of the coating. With optimized deposition conditions, we can apply the coating technique toward the actual T91 cladding materials, and provide the possibilities for the real application in sodium-cooled fast reactors (SFRs). Diffusion couple experiments were performed at both 550 oC and 690 oC, which corresponds to normal and aggressive operating temperatures, respectively. The results show that vanadium carbide coating with wider thickness (8 µm) and lower carbon concentration (27 at.%) reduced the width of the inter diffusion region, indicating that vanadium carbide coating can mitigate FCCI effectively. In specific, inter-diffusion between Fe and Ce was prohibited over most area, but Ce diffusion occurred toward the coating and the Fe substrate through thinner coating layer, which needs further optimization in terms of uniform coating thickness. Overall, it is concluded that this coating process can be successfully applied onto the inner surface of HT9 cladding tubes and the FCCI can be effectively mitigated if not totally eliminated.« less

Interaction of oxygen with ZrC(001) and VC(001): Photoemission and first-principles studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez, J.A.; Liu, P.; Gomes, J.

2005-08-15

High-resolution photoemission and first-principles density-functional calculations were used to study the interaction of oxygen with ZrC(001) and VC(001) surfaces. Atomic oxygen is present on the carbide substrates after small doses of O{sub 2} at room temperature. At 500 K, the oxidation of the surfaces is fast and clear features for ZrO{sub x} or VO{sub x} are seen in the O(1s), Zr(3d), and V(2p{sub 3/2}) core levels spectra, with an increase in the metal/carbon ratio of the samples. A big positive shift (1.3-1.6 eV) was detected for the C 1s core level in O/ZrC(001), indicating the existence of strong O{r_reversible}C ormore » C{r_reversible}C interactions. A phenomenon corroborated by the results of first-principles calculations, which show a CZrZr hollow as the most stable site for the adsorption of O. Furthermore, the calculations also show that a C{r_reversible}O exchange is exothermic on ZrC(001), and the displaced C atoms bond to CZrZr sites. In the O/ZrC(001) interface, the surface C atoms play a major role in determining the behavior of the system. In contrast, the adsorption of oxygen induces very minor changes in the C(1s) spectrum of VC(001). The O{r_reversible}V interactions are stronger than the O{r_reversible}Zr interactions, and O{r_reversible}C interactions do not play a dominant role in the O/VC(001) interface. In this system, C{r_reversible}O exchange is endothermic. VC(001) has a larger density of metal d states near the Fermi level than ZrC(001), but the rate of oxidation of VC(001) is slower. Therefore the O/ZrC(001) and O/VC(001) systems illustrate two different types of pathways for the oxidation of carbide surfaces.« less

Effect of molybdenum, vanadium, boron on mechanical properties of high chromium white cast iron in as-cast condition

NASA Astrophysics Data System (ADS)

Nurjaman, F.; Sumardi, S.; Shofi, A.; Aryati, M.; Suharno, B.

2016-02-01

In this experiment, the effect of the addition carbide forming elements on high chromium white cast iron, such as molybdenum, vanadium and boron on its mechanical properties and microstructure was investigated. The high chromium white cast iron was produced by casting process and formed in 50 mm size of grinding balls with several compositions. Characterization of these grinding balls was conducted by using some testing methods, such as: chemical and microstructure analysis, hardness, and impact test. From the results, the addition of molybdenum, vanadium, and boron on high chromium white cast iron provided a significant improvement on its hardness, but reduced its toughness. Molybdenum induced fully austenitic matrix and Mo2C formation among eutectic M7C3 carbide. Vanadium was dissolved in the matrix and carbide. While boron was played a role to form fine eutectic carbide. Grinding balls with 1.89 C-13.1 Cr-1.32 Mo-1.36 V-0.00051 B in as-cast condition had the highest hardness, which was caused by finer structure of eutectic carbide, needle like structure (upper bainite) matrix, and martensite on its carbide boundary.

Theoretical insights into the uranyl adsorption behavior on vanadium carbide MXene

NASA Astrophysics Data System (ADS)

Zhang, Yu-Juan; Zhou, Zhang-Jian; Lan, Jian-Hui; Ge, Chang-Chun; Chai, Zhi-Fang; Zhang, Peihong; Shi, Wei-Qun

2017-12-01

Remediation of the contamination by long-lived actinide wastes is extremely important but also challenging. Adsorption based techniques have attracted much research attention for their potential as low-cost and effective methods to reduce the radioactive waste from solution. In this work, we have investigated the adsorption behavior of uranyl species [with the general form UO2(L1)x(L2)y(L3)z, where L1, L2 and L3 stand for ligands H2O, OH and CO3, respectively] on hydroxylated vanadium carbide V2C(OH)2 MXene nanosheets using density functional theory based simulation methods We find that all studied uranyl species can stably bond to hydroxylated MXene with binding energies ranging from -3.3 to -4.6 eV, suggesting that MXenes could be effective adsorbers for uranyl ions. The strong adsorption is achieved by forming two Usbnd O bonds with the hydroxylated Mxene. In addition, the axial oxygen atoms from the uranyl ions form hydrogen bonds with the hydroxylated V2C, further strengthening the adsorption. We have also investigated the effects of F termination on the uranyl adsorption properties of V2C nanosheets. Usbnd F bonds are in general weaker than Usbnd O bonds on the adsorption site, suggesting that F terminated Mexne is less favorable for uranyl adsorption applications.

Carbon Textile Decorated with Pseudocapacitive VC/Vx Oy for High-Performance Flexible Supercapacitors.

PubMed

Van Lam, Do; Shim, Hyung Cheoul; Kim, Jae-Hyun; Lee, Hak-Joo; Lee, Seung-Mo

2017-11-01

It is demonstrated that, via V 2 O 5 coating by low temperature atomic layer deposition and subsequent pyrolysis, ubiquitous cotton textile can readily turn into high-surface-area carbon textile fully decorated with pseudocapacitive V x O y /VC widely usable as electrodes of high-performance supercapacitor. It is found that carbothermic reduction of V 2 O 5 (C + V 2 O 5 → C' + VC + CO/CO 2 (g)) leads to chemical/mechanical activation of carbon textile, thereby producing high-surface-area conductive carbon textile. In addition, sequential phase transformation and carbide formation (V 2 O 5 → V x O y → VC) occurred by carbothermic reduction trigger decoration of the carbon textile with redox-active V x O y /VC. Thanks to the synergistic effect of electrical double layer and pseudocapacitance, the supercapacitors made of the hybrid carbon textile exhibit far better energy density (over 30-fold increase) with excellent cycling stability than the carbon textile simply undergone pyrolysis. The method can open up a promising and facile way to synthesize hybrid electrode materials for electrochemical energy storages possessing advantages of both electrical double layer and pseudocapacitive material. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Fe-V Cofactor of Vanadium Nitrogenase Contains an Interstitial Carbon Atom.

PubMed

Rees, Julian A; Bjornsson, Ragnar; Schlesier, Julia; Sippel, Daniel; Einsle, Oliver; DeBeer, Serena

2015-11-02

The first direct evidence is provided for the presence of an interstitial carbide in the Fe-V cofactor of Azotobacter vinelandii vanadium nitrogenase. As for our identification of the central carbide in the Fe-Mo cofactor, we employed Fe Kβ valence-to-core X-ray emission spectroscopy and density functional theory calculations, and herein report the highly similar spectra of both variants of the cofactor-containing protein. The identification of an analogous carbide, and thus an atomically homologous active site in vanadium nitrogenase, highlights the importance and influence of both the interstitial carbide and the identity of the heteroatom on the electronic structure and catalytic activity of the enzyme. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

VC-dimension of univariate decision trees.

PubMed

Yildiz, Olcay Taner

2015-02-01

In this paper, we give and prove the lower bounds of the Vapnik-Chervonenkis (VC)-dimension of the univariate decision tree hypothesis class. The VC-dimension of the univariate decision tree depends on the VC-dimension values of its subtrees and the number of inputs. Via a search algorithm that calculates the VC-dimension of univariate decision trees exhaustively, we show that our VC-dimension bounds are tight for simple trees. To verify that the VC-dimension bounds are useful, we also use them to get VC-generalization bounds for complexity control using structural risk minimization in decision trees, i.e., pruning. Our simulation results show that structural risk minimization pruning using the VC-dimension bounds finds trees that are more accurate as those pruned using cross validation.

Surface segregation on Fe3%Si0.04%VC(100) single crystal surfaces

NASA Astrophysics Data System (ADS)

Uebing, C.; Viefhaus, H.

1990-10-01

Surface segregation phenomena on (100) oriented single crystal surfaces of the ferritic Fe-3%Si-0.04%V-C alloy were investigated by AES and LEED. At temperatures below 635 °C vanadium and carbon cosegregation is observed after prolonged heating. At thermodynamic equilibrium the substrate surface is saturated with the binary surface compound VC. The two-dimensional VC is epitaxially arranged on the substrate surface as indicated by LEED investigations. Its structure corresponds to the (100) plane of the three-dimensional VC with rocksalt structure. Sharp above 635 °C the surface compound VC is dissolved into the bulk. At higher temperatures the substrate surface is covered with segregated silicon forming a c(2 × 2) structure. This surface phase transition is reversible. Because of the low concentration and slow diffusion of vanadium, non-equilibrium surface states are formed as intermediates upon segregation of silicon and carbon. Below 500 °C a disordered graphite layer with a characteristical asymmetrical C Auger peak is observed on the substrate surface. Above 500 °C carbon segregation leads to the formation of an ordered c(2 × 2) structure with a symmetrical C Auger peak being characteristic for carbidic or atomically adsorbed species. At increasing temperatures silicon segregation takes place leading to a c(2 × 2) structure. Between silicon and carbon site competition is effective.

Doping of vanadium to nanocrystalline diamond films by hot filament chemical vapor deposition

PubMed Central

2012-01-01

Doping an impure element with a larger atomic volume into crystalline structure of buck crystals is normally blocked because the rigid crystalline structure could not tolerate a larger distortion. However, this difficulty may be weakened for nanocrystalline structures. Diamonds, as well as many semiconductors, have a difficulty in effective doping. Theoretical calculations carried out by DFT indicate that vanadium (V) is a dopant element for the n-type diamond semiconductor, and their several donor state levels are distributed between the conduction band and middle bandgap position in the V-doped band structure of diamond. Experimental investigation of doping vanadium into nanocrystalline diamond films (NDFs) was first attempted by hot filament chemical vapor deposition technique. Acetone/H2 gas mixtures and vanadium oxytripropoxide (VO(OCH2CH2CH3)3) solutions of acetone with V and C elemental ratios of 1:5,000, 1:2,000, and 1:1,000 were used as carbon and vanadium sources, respectively. The resistivity of the V-doped NDFs decreased two orders with the increasing V/C ratios. PMID:22873631

The effect of nitrogen on precipitation and transformation kinetics in vanadium steels

NASA Astrophysics Data System (ADS)

Balliger, N. K.; Honeycombe, R. W. K.

1980-03-01

The isothermal decomposition of austenite has been studied in a series of vanadium steels containing varying amounts of carbon and nitrogen, (in approximately stoichio-metric proportions), in the temperature range 700 to 850°C. In the basic alloy, Fe-0.27V-0.05C (composition in wt pct), below 810°C the austenite to polygonal ferrite trans-formation is accompanied by interphase precipitation of vanadium carbide, the finer dis-persions being associated with the lower transformation temperatures. However, below 760°C there is an additional precipitation reaction where dislocation precipitation of vanadium carbide predominates; this is shown to occur in association with Widmanstätten ferrite. Above 810° C, a proeutectoid ferrite reaction results, the ferrite being void of precipitates; evidence is provided to show that partitioning of vanadium from ferrite to austenite occurs during the transformation. In the two steels containing nitrogen, namely Fe-0.26V-0.022N-0.020C and Fe-0.29V-0.032 N the basic interphase precipitation re-action is unchanged, but the resultant precipitate dispersions are finer at a given trans-formation temperature. The temperature range over which interphase precipitation oc-curs is expanded by the presence of nitrogen, since the Widmanstätten start tempera-ture is depressed and the proeutectoid ferrite reaction is inhibited. Precipitation in austenite prior to transformation and twin formation during transformation are both en-couraged by the presence of nitrogen.

BRIC-100VC Biological Research in Canisters (BRIC)-100VC

NASA Technical Reports Server (NTRS)

Richards, Stephanie E.; Levine, Howard G. (Compiler); Romero, Vergel

2016-01-01

The Biological Research in Canisters (BRIC) is an anodized-aluminum cylinder used to provide passive stowage for investigations of the effects of space flight on small specimens. The BRIC 100 mm petri dish vacuum containment unit (BRIC-100VC) has supported Dugesia japonica (flatworm) within spring under normal atmospheric conditions for 29 days in space and Hemerocallis lilioasphodelus L. (daylily) somatic embryo development within a 5% CO2 gaseous environment for 4.5 months in space. BRIC-100VC is a completely sealed, anodized-aluminum cylinder (Fig. 1) providing containment and structural support of the experimental specimens. The top and bottom lids of the canister include rapid disconnect valves for filling the canister with selected gases. These specialized valves allow for specific atmospheric containment within the canister, providing a gaseous environment defined by the investigator. Additionally, the top lid has been designed with a toggle latch and O-ring assembly allowing for prompt sealing and removal of the lid. The outside dimensions of the BRIC-100VC canisters are 16.0 cm (height) x 11.4 cm (outside diameter). The lower portion of the canister has been equipped with sufficient storage space for passive temperature and relative humidity data loggers. The BRIC- 100VC canister has been optimized to accommodate standard 100 mm laboratory petri dishes or 50 mL conical tubes. Depending on storage orientation, up to 6 or 9 canisters have been flown within an International Space Station (ISS) stowage locker.

Crystallographic characterizations of eutectic and secondary carbides in a Fe-12Cr-2.5Mo-1.5W-3V-1.25C alloy

NASA Astrophysics Data System (ADS)

Guo, Jing; Liu, Ligang; Feng, Yunli; Liu, Sha; Ren, Xuejun; Yang, Qingxiang

2017-03-01

In this work, the morphology and structures of the eutectic and secondary carbides in a new high chromium Fe-12Cr-2.5Mo-1.5W-3V-1.25C designed for cold-rolling work roll were systematically studied. The precipitated carbides inside the grains and along the grain boundaries were investigated with optical microscope, scanning electron microscopy with energy dispersive spectroscopy, transmission electron microscopy and X-Ray diffraction. Selected area diffraction patterns have been successfully used to identify the crystal formation and lattice constants of the carbides with different alloying elements. The results show that the eutectic carbides precipitated contain MC and M2C distributed along the grain boundaries with dendrite feature. The composition and crystal structure analysis shows that the eutectic MC carbides contain VC and WC with a cubic and hexagonal crystal lattice structures respectively, while the eutectic M2C carbides predominantly contain V2C and Mo2C with orthorhombic and hexagonal crystal lattices respectively. The secondary carbides contain MC, M2C, M7C3 formed along the grain boundaries and their sizes are much larger than the eutectic carbides ones. The secondary M23C6 is much small (0.3-0.5μm) and is distributed dispersively inside the grain. Similar to the eutectic carbides, the secondary carbides also contain VC, WC, V2C, and Mo2C. M7C3 is hexagonal (Fe,Cr)7C3, while M23C6 is indexed to be in a cubic crystal form.

Synthesis of nanostructured vanadium powder by high-energy ball milling: X-ray diffraction and high-resolution electron microscopy characterization

NASA Astrophysics Data System (ADS)

Krishnan, Vinoadh Kumar; Sinnaeruvadi, Kumaran

2016-10-01

Vanadium metal powders, ball milled with different surfactants viz., stearic acid, KCl and NaCl, have been studied by X-ray diffraction and transmission electron microscopy. The surfactants alter the microstructural and morphological characteristics of the powders. Ball milling with stearic acid results in solid-state amorphization, while powders milled with KCl yield vanadium-tungsten carbide nanocomposite mixtures. NaCl proved to be an excellent surfactant for obtaining nanostructured fusion-grade vanadium powders. In order to understand the reaction mechanism behind any interstitial addition in the ball-milled powders, CHNOS analysis was performed.

First-principles investigations of iron-based alloys and their properties

NASA Astrophysics Data System (ADS)

Limmer, Krista Renee

Fundamental understanding of the complex interactions governing structure-property relationships in iron-based alloys is necessary to advance ferrous metallurgy. Two key components of alloy design are carbide formation and stabilization and controlling the active deformation mechanism. Following a first-principles methodology, understanding on the electronic level of these components has been gained for predictive modeling of alloys. Transition metal carbides have long played an important role in alloy design, though the complexity of their interactions with the ferrous matrix is not well understood. Bulk, surface, and interface properties of vanadium carbide, VCx, were calculated to provide insight for the carbide formation and stability. Carbon vacancy defects are shown to stabilize the bulk carbide due to increased V-V bonding in addition to localized increased V-C bond strength. The VCx (100) surface energy is minimized when carbon vacancies are at least two layers from the surface. Further, the Fe/VC interface is stabilized through maintaining stoichiometry at the Fe/VC interface. Intrinsic and unstable stacking fault energy, gammaisf and gamma usf respectively, were explicitly calculated in nonmagnetic fcc Fe-X systems for X = Al, Si, P, S, and the 3d and 4d transition elements. A parabolic relationship is observed in gamma isf across the transition metals with minimums observed for Mn and Tc in the 3d and 4d periods, respectively. Mn is the only alloying addition that was shown to decrease gamma isf in fcc Fe at the given concentration. The effect of alloying on gammausf also has a parabolic relationship, with all additions decreasing gammaisf yielding maximums for Fe and Rh.

Reduction and Smelting of Vanadium Titanomagnetite Metallized Pellets

NASA Astrophysics Data System (ADS)

Wang, Shuai; Chen, Mao; Guo, Yufeng; Jiang, Tao; Zhao, Baojun

2018-04-01

Reduction and smelting of the vanadium titanomagnetite metallized pellets have been experimentally investigated in this study. By using the high-temperature smelting, rapid quenching, and electron probe x-ray microanalysis (EPMA) technique, the effects of basicity, reaction time, and graphite reductant amount were investigated. The vanadium contents in iron alloys increase with increasing basicity, reaction time, and graphite amount, whereas the FeO and V2O3 concentrations in the liquid phase decrease with the increase of graphite amount and reaction time. Increasing the reaction time and reductant content promotes the reduction of titanium oxide, whereas the reduction of titanium oxides can be suppressed with increasing the slag basicity. Titanium carbide (TiC) was not observed in all the quenched samples under the present conditions. The experimental results and the FactSage calculations are also compared in the present study.

Effect of Feeding and Withdrawal of Vanadium and Vitamin C on Egg Quality and Vanadium Residual Over Time in Laying Hens.

PubMed

Wang, J P; He, K R; Ding, X M; Bai, S P; Zeng, Q F; Zhang, K Y

2017-06-01

This experiment examined the egg quality of hens fed vanadium (V) and vitamin C (VC) during storage, as well as the V and VC withdrawal on egg quality and V residual in egg. A total of 360 laying hens (31 weeks old) were randomly allotted into a 3 × 2 factorial arrangement treatments (6 replicates and 10 chicks per replicate) with three levels of dietary V (0, 5, and 10 mg/kg) and two levels of VC (0 and 100 mg/kg) for 19 weeks (feeding V and VC 12 weeks, recovery 7 weeks). The V residual in eggs at 4, 8, and 12th weeks were increased (linear effect, P ≤ 0.01) as V levels increased and was not detected in albumen at 7th week after V withdrawal. Followed by 12-week feeding period, albumen height and Haugh unit of eggs during 2-week storage were decreased (linear and quadratic effect, P < 0.01) by dietary V supplementation. Lightness value was increased (linear effect, P < 0.01), whereas redness and yellowness value of the eggshell were lowered (linear effect, P < 0.01) in V-containing diet. During 7-week withdrawal period, eggs from groups pre-feeding 5 and 10 mg/kg V had lower (linear effect, P < 0.01) overall albumen height and Haugh unit. The reducing effect on albumen height and HU continued to be observed until the seventh week, whereas the bleaching effect on eggshell color disappeared after 1-week withdrawal. The results indicated that feeding 5 or 10 mg/kg V increases egg V residual and reduces egg albumen quality and bleached the shell color, and the impaired albumen quality induced by 10 mg/kg of V lasted at least 6 weeks after changing to no V supplementation diet. The addition of VC did not show to affect egg quality during storage or recovery phase.

Effect of electroslag remelting on carbides in 8Cr13MoV martensitic stainless steel

NASA Astrophysics Data System (ADS)

Zhu, Qin-tian; Li, Jing; Shi, Cheng-bin; Yu, Wen-tao

2015-11-01

The effect of electroslag remelting (ESR) on carbides in 8Cr13MoV martensitic stainless steel was experimentally studied. Phases precipitated from liquid steel during solidification were calculated using the Thermo-Calc software. The carbon segregation was analyzed by original position analysis (OPA), and the carbides were analyzed by optical microscopy (OM), scanning electron microscopy (SEM), energy- dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The results indicated that more uniform carbon distribution and less segregation were obtained in the case of samples subjected to the ESR process. After ESR, the amount of netty carbides decreased significantly, and the chromium and vanadium contents in the grain-boundary carbides was reduced. The total area and average size of carbides were obviously smaller after the ESR process. In the sample subjected to ESR, the morphology of carbides changed from lamellar and angular to globular or lump, whereas the types of carbides did not change; both M23C6 and M7C3 were present before and after the ESR process.

Correlation between molten vanadium salts and the structural degradation of HK-type steel superheater tubes

NASA Astrophysics Data System (ADS)

de Carvalho Nunes, Frederico; de Almeida, Luiz Henrique; Ribeiro, André Freitas

2006-12-01

HK steels are among the most used heat-resistant cast stainless steels, being corrosion-resistant and showing good mechanical properties at high service temperatures. These steels are widely used in reformer furnaces and as superheater tubes. During service, combustion gases leaving the burners come in contact with these tubes, resulting in corrosive attack and a large weight loss occurs due to the presence of vanadium, which forms low melting point salts, removing the protective oxide layer. In this work the external surface of a tube with dramatic wall thickness reduction was analyzed using light microscopy, scanning electron microscopy, and transmission electron microscopy. The identification of the phases was achieved by energy dispersive spectroscopy (EDS) analyses. The results showed oxides arising from the external surface. In this oxidized region vanadium compounds inside chromium carbide particles were also observed, due to inward vanadium diffusion during corrosion attack. A chemical reaction was proposed to explain the presence of vanadium in the metal microstructure.

Role of precursor crystal structure on electrochemical performance of carbide-derived carbon electrodes

NASA Astrophysics Data System (ADS)

Palazzo, Benjamin; Norris, Zach; Taylor, Greg; Yu, Lei; Lofland, Samuel; Hettinger, Jeffrey

2015-03-01

Binary carbides with hexagonal and cubic crystal structures have been synthesized by reactive magnetron sputtering of vanadium and other transition metals in acetylene or methane gas mixed with argon. The binary carbides are converted to carbide-derived carbon (CDC) films using chlorine gas in a post-deposition process in an external vacuum reaction furnace. Residual chlorine has been removed using an annealing step in a hydrogen atmosphere. The CDC materials have been characterized by x-ray diffraction, x-ray fluorescence, and scanning electron microscopy. The performance of the CDC materials in electrochemical device applications has been measured with the hexagonal phase precursor demonstrating a significantly higher specific capacitance in comparison to that of the cubic phase. We report these results and pore-size distributions of these and similar materials.

Evaluation of silicon carbide fiber/titanium composites

NASA Technical Reports Server (NTRS)

Jech, R. W.; Signorelli, R. A.

1979-01-01

Izod impact, tensile, and modulus of elasticity were determined for silicon carbide fiber/titanium composites to evaluate their potential usefulness as substitutes for titanium alloys or stainless steel in stiffness critical applications for aircraft turbine engines. Variations in processing conditions and matrix ductility were examined to produce composites having good impact strength in both the as-fabricated condition and after air exposure at elevated temperature. The impact strengths of composites containing 36 volume percent silicon carbide (SiC) fiber in an unalloyed (A-40) titanium matrix were found to be equal to unreinforced titanium-6 aluminum-4 vanadium alloy; the tensile strengths of the composites were marginally better than the unreinforced unalloyed (A-70) matrix at elevated temperature, though not at room temperature. At room temperature the modulus of elasticity of the composites was 48 percent higher than titanium or its alloys and 40 percent higher than that of stainless steel.

Large-scale delamination of multi-layers transition metal carbides and carbonitrides “MXenes”

DOE PAGES

Naguib, Michael; Unocic, Raymond R.; Armstrong, Beth L.; ...

2015-04-17

Herein we report on a general approach to delaminate multi-layered MXenes using an organic base to induce swelling that in turn weakens the bonds between the MX layers. Simple agitation or mild sonication of the swollen MXene in water resulted in the large-scale delamination of the MXene layers. The delamination method is demonstrated for vanadium carbide, and titanium carbonitrides MXenes.

Vanadium

USGS Publications Warehouse

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

Vanadium and columbium additions in pressure vessel steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, P.; Somers, B.R.; Pense, A.W.

1994-09-01

A statistically designed series of vanadium and columbium microalloyed C-Mn HSLA steels was used for an investigation of heat-affected zone (HAZ) toughness in post weld heat treated (PWHT) multi-pass welds. The vanadium additions were in the range 0.005 to 0.097 Wt.% and the columbium additions were in the range 0.004 to 0.06 Wt.% GMAW processes with welding heat inputs of 3kJ/mm and 5kJ/mm and post-weld heat treatments at 620 C for 2 10 hours were employed. A degradation of the HAZ toughness with additions of microalloy elements V and Cb in the as-welded and PWHT conditions was revealed. The 50more » Joule (37 ft-lb) transition temperature (TT50J) for HAZs in all weld conditions correlated with maximum HAZ hardness. Increases in HAZ hardness and TT50J caused by PWHT were observed. Hence PWHT in some situations may not beneficial for V/Cb microalloyed HLSA steels. The randomly distributed precipitation of V and Cb carbides (V, Cb)C, including dislocation precipitation and matrix precipitation with particle sizes of 5--15 nm, is the predominant alloy carbide precipitate morphology in these steels. The crack initiation sites in Charpy specimens of HAZs tested at the approximate transition temperature are shifted from the highest stress triaxiality, mid-specimen location to an off center higher hardness location. This is found to be characteristic of fracture in the multipass HAZ of the microalloyed steel.« less

Transcript Profile of Flowering Regulatory Genes in VcFT-Overexpressing Blueberry Plants

PubMed Central

Walworth, Aaron E.; Chai, Benli; Song, Guo-qing

2016-01-01

In order to identify genetic components in flowering pathways of highbush blueberry (Vaccinium corymbosum L.), a transcriptome reference composed of 254,396 transcripts and 179,853 gene contigs was developed by assembly of 72.7 million reads using Trinity. Using this transcriptome reference and a query of flowering pathway genes of herbaceous plants, we identified potential flowering pathway genes/transcripts of blueberry. Transcriptome analysis of flowering pathway genes was then conducted on leaf tissue samples of transgenic blueberry cv. Aurora (‘VcFT-Aurora’), which overexpresses a blueberry FLOWERING LOCUS T-like gene (VcFT). Sixty-one blueberry transcripts of 40 genes showed high similarities to 33 known flowering-related genes of herbaceous plants, of which 17 down-regulated and 16 up-regulated genes were identified in ‘VcFT-Aurora’. All down-regulated genes encoded transcription factors/enzymes upstream in the signaling pathway containing VcFT. A blueberry CONSTANS-LIKE 5-like (VcCOL5) gene was down-regulated and associated with five other differentially expressed (DE) genes in the photoperiod-mediated flowering pathway. Three down-regulated genes, i.e., a MADS-AFFECTING FLOWERING 2-like gene (VcMAF2), a MADS-AFFECTING FLOWERING 5-like gene (VcMAF5), and a VERNALIZATION1-like gene (VcVRN1), may function as integrators in place of FLOWERING LOCUS C (FLC) in the vernalization pathway. Because no CONSTAN1-like or FLOWERING LOCUS C-like genes were found in blueberry, VcCOL5 and VcMAF2/VcMAF5 or VRN1 might be the major integrator(s) in the photoperiod- and vernalization-mediated flowering pathway, respectively. The major down-stream genes of VcFT, i.e., SUPPRESSOR of Overexpression of Constans 1-like (VcSOC1), LEAFY-like (VcLFY), APETALA1-like (VcAP1), CAULIFLOWER 1-like (VcCAL1), and FRUITFULL-like (VcFUL) genes were present and showed high similarity to their orthologues in herbaceous plants. Moreover, overexpression of VcFT promoted expression of all

Transcript Profile of Flowering Regulatory Genes in VcFT-Overexpressing Blueberry Plants.

PubMed

Walworth, Aaron E; Chai, Benli; Song, Guo-Qing

2016-01-01

In order to identify genetic components in flowering pathways of highbush blueberry (Vaccinium corymbosum L.), a transcriptome reference composed of 254,396 transcripts and 179,853 gene contigs was developed by assembly of 72.7 million reads using Trinity. Using this transcriptome reference and a query of flowering pathway genes of herbaceous plants, we identified potential flowering pathway genes/transcripts of blueberry. Transcriptome analysis of flowering pathway genes was then conducted on leaf tissue samples of transgenic blueberry cv. Aurora ('VcFT-Aurora'), which overexpresses a blueberry FLOWERING LOCUS T-like gene (VcFT). Sixty-one blueberry transcripts of 40 genes showed high similarities to 33 known flowering-related genes of herbaceous plants, of which 17 down-regulated and 16 up-regulated genes were identified in 'VcFT-Aurora'. All down-regulated genes encoded transcription factors/enzymes upstream in the signaling pathway containing VcFT. A blueberry CONSTANS-LIKE 5-like (VcCOL5) gene was down-regulated and associated with five other differentially expressed (DE) genes in the photoperiod-mediated flowering pathway. Three down-regulated genes, i.e., a MADS-AFFECTING FLOWERING 2-like gene (VcMAF2), a MADS-AFFECTING FLOWERING 5-like gene (VcMAF5), and a VERNALIZATION1-like gene (VcVRN1), may function as integrators in place of FLOWERING LOCUS C (FLC) in the vernalization pathway. Because no CONSTAN1-like or FLOWERING LOCUS C-like genes were found in blueberry, VcCOL5 and VcMAF2/VcMAF5 or VRN1 might be the major integrator(s) in the photoperiod- and vernalization-mediated flowering pathway, respectively. The major down-stream genes of VcFT, i.e., SUPPRESSOR of Overexpression of Constans 1-like (VcSOC1), LEAFY-like (VcLFY), APETALA1-like (VcAP1), CAULIFLOWER 1-like (VcCAL1), and FRUITFULL-like (VcFUL) genes were present and showed high similarity to their orthologues in herbaceous plants. Moreover, overexpression of VcFT promoted expression of all of these

Insights on the SO2 Poisoning of Pt3Co/VC and Pt/VC Fuel Cell Catalysts

DTIC Science & Technology

2010-01-01

catalyst is performed at the cathode of proton exchange membrane fuel cells ( PEMFCs ) in order to link previously reported results at the elec- trode...stripping voltammetry and underpotential deposition (upd) of copper adatoms. Then the performance of PEMFC cathodes employing 30wt.% Pt3Co/VC and 50wt.% Pt/VC...proton exchange membrane fuel cells( PEMFCs )in order to link previously reported results at the elec- trode/solution interface to the FC environment. First

Probing Nuclear Spin Effects on Electronic Spin Coherence via EPR Measurements of Vanadium(IV) Complexes.

PubMed

Graham, Michael J; Krzyaniak, Matthew D; Wasielewski, Michael R; Freedman, Danna E

2017-07-17

Quantum information processing (QIP) has the potential to transform numerous fields from cryptography, to finance, to the simulation of quantum systems. A promising implementation of QIP employs unpaired electronic spins as qubits, the fundamental units of information. Though molecular electronic spins offer many advantages, including chemical tunability and facile addressability, the development of design principles for the synthesis of complexes that exhibit long qubit superposition lifetimes (also known as coherence times, or T 2 ) remains a challenge. As nuclear spins in the local qubit environment are a primary cause of shortened superposition lifetimes, we recently conducted a study which employed a modular spin-free ligand scaffold to place a spin-laden propyl moiety at a series of fixed distances from an S = 1 / 2 vanadium(IV) ion in a series of vanadyl complexes. We found that, within a radius of 4.0(4)-6.6(6) Å from the metal center, nuclei did not contribute to decoherence. To assess the generality of this important design principle and test its efficacy in a different coordination geometry, we synthesized and investigated three vanadium tris(dithiolene) complexes with the same ligand set employed in our previous study: K 2 [V(C 5 H 6 S 4 ) 3 ] (1), K 2 [V(C 7 H 6 S 6 ) 3 ] (2), and K 2 [V(C 9 H 6 S 8 ) 3 ] (3). We specifically interrogated solutions of these complexes in DMF-d 7 /toluene-d 8 with pulsed electron paramagnetic resonance spectroscopy and electron nuclear double resonance spectroscopy and found that the distance dependence present in the previously synthesized vanadyl complexes holds true in this series. We further examined the coherence properties of the series in a different solvent, MeCN-d 3 /toluene-d 8 , and found that an additional property, the charge density of the complex, also affects decoherence across the series. These results highlight a previously unknown design principle for augmenting T 2 and open new pathways for the

In vivo and in vitro phenotypic differences between Great Lakes VHSV genotype IVb isolates with sequence types vcG001 and vcG002

PubMed Central

Imanse, Sierra M.; Cornwell, Emily R.; Getchell, Rodman G.; Kurath, Gael; Bowser, Paul R.

2014-01-01

Viral hemorrhagic septicemia virus (VHSV) is an aquatic rhabdovirus first recognized in farmed rainbow trout in Denmark. In the past decade, a new genotype of this virus, IVb was discovered in the Laurentian Great Lakes basin and has caused several massive die-offs in some of the 28 species of susceptible North American freshwater fishes. Since its colonization of the Great Lakes, several closely related sequence types within genotype IVb have been reported, the two most common of which are vcG001 and vcG002. These sequence types have different spatial distributions in the Great Lakes. The aim of this study was to determine whether the genotypic differences between representative vcG001 (isolate MI03) and vcG002 (isolate 2010-030 #91) isolates correspond to phenotypic differences in terms of virulence using both an in vitro and in vivo approach. In vitro infection of epithelioma papulosum cyprini (EPC), bluegill fry (BF-2), and Chinook salmon embryo (CHSE) cells demonstrated some differences in onset and rate of growth in EPC and BF-2 cells, without any difference in the quantity of RNA produced. In vivo infection of round gobies (Neogobius melanostomus) via immersion exposure to different concentrations of vcG001 or vcG002 caused a significantly greater mortality in round gobies exposed to 102 plaque forming units ml−1 of vcG001. These experiments suggest that there are phenotypic differences between Great Lakes isolates of VHSV genotype IVb. PMID:25722533

In vivo and in vitro phenotypic differences between Great Lakes VHSV genotype IVb isolates with sequence types vcG001 and vcG002

USGS Publications Warehouse

Imanse, Sierra M.; Cornwell, Emily R.; Getchell, Rodman G.; Kurath, Gael; Bowser, Paul R.

2014-01-01

Viral hemorrhagic septicemia virus (VHSV) is an aquatic rhabdovirus first recognized in farmed rainbow trout in Denmark. In the past decade, a new genotype of this virus, IVb was discovered in the Laurentian Great Lakes basin and has caused several massive die-offs in some of the 28 species of susceptible North American freshwater fishes. Since its colonization of the Great Lakes, several closely related sequence types within genotype IVb have been reported, the two most common of which are vcG001 and vcG002. These sequence types have different spatial distributions in the Great Lakes. The aim of this study was to determine whether the genotypic differences between representative vcG001 (isolate MI03) and vcG002 (isolate 2010-030 #91) isolates correspond to phenotypic differences in terms of virulence using both in vitro and in vivo approaches. In vitro infection of epithelioma papulosum cyprini (EPC), bluegill fry (BF-2), and Chinook salmon embryo (CHSE) cells demonstrated some differences in onset and rate of growth in EPC and BF-2 cells, without any difference in the quantity of RNA produced. In vivo infection of round gobies (Neogobius melanostomus) via immersion exposure to different concentrations of vcG001 or vcG002 caused a significantly greater mortality in round gobies exposed to 102 plaque forming units ml− 1 of vcG001. These experiments suggest that there are phenotypic differences between Great Lakes isolates of VHSV genotype IVb.

THE COLORIMETRIC DETERMINATION OF VANADIUM IN NIOBIUM-VANADIUM ALLOYS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Articolo, O.J.

1959-06-26

A procedure is described for the analysis of vanadium in niobium-- vanadium alloys in the range >0.1% vanadium with an accuracy of better than 3%. The method was applied to the analysis of niobium alloys in which the nominal per cent vanadium varied between 0.3 to 4.6%. The sample is dissolved in a mixture of nitric and hydrofluoric acid and then evaporated to fumes with sulfuric acid. The niobium is hydrolyzed with sulfurous acid and separated from the vanadium by filtration. Hydrogen peroxide is added to the filtrate to form a reddish brown complex with the vanadium. The optical densitymore » of the resulting solution is obtained at 450 m mu on a model B Beckman spectrophotometer. (auth)« less

Effect of dietary vanadium and vitamin C on egg quality and antioxidant status in laying hens.

PubMed

Wang, J P; He, K R; Ding, X M; Luo, Y H; Bai, S P; Zeng, Q F; Su, Z W; Xuan, Y; Zhang, K Y

2016-06-01

This study assessed the effect of dietary vanadium (V) and vitamin C (VC) on production performance, egg quality and antioxidant status in laying hens. A total of 360 laying hens (31-week-old) were randomly allotted into a 3 × 3 factorial arrangement treatments (four replicates and 10 chicks per replicate) with three levels of dietary V (0, 5 and 10 mg/kg) and three levels of vitamin C (0, 50 and 100 mg/kg) for 12 weeks. The effect of V and VC did not alter egg production, egg weight, average daily feed intake and feed conversion ratio during 1-12 week. Albumen height and Haugh unit value were linearly decreased (p < 0.001) by addition of V, whereas the effect of 100 mg/kg VC was observed to counteract (p < 0.05) this effect in V-containing treatments during 1-12 week. Hens fed V-containing diet laid lighter (linear effect, p < 0.05) coloured eggs (higher lightness value, lower redness and yellowness value), and the VC exerted no influence on it during 1-12 week. The serum superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities, ability to inhibit hydroxyl radical, were significantly decreased, and the malondialdehyde (MDA) and V contents were increased (p < 0.05) by effect of V during 4, 8 and 12 week. The effect of VC alone and the interactive effect between VC and V were shown to increase serum (p < 0.05) SOD activity in 4 week and decrease MAD levels in 12 week. The result indicate that V decreased the egg quality and caused the oxidative stress at level of 5 mg/kg and 10 mg/kg, and the addition of 100 mg/kg vitamin C can alleviate its egg quality reduction effect and can mitigate the oxidative stress to some extent. Journal of Animal Physiology and Animal Nutrition © 2015 Blackwell Verlag GmbH.

Lateral power MOSFETs in silicon carbide

NASA Astrophysics Data System (ADS)

Spitz, Jan

2001-07-01

Because of its large bandgap, its high critical electric field, and its high quality native SiO2, silicon carbide is considered to be the material of choice for power switching electronics in the future. Until 1997 the maximum thickness of commercially available epilayers serving as the drift region for power devices has been limited to 10--15 mum, limiting the maximum blocking voltage to 1500 V for vertical power devices in silicon carbide. In this study, we present the first lateral power devices on a semi-insulating vanadium doped substrate of silicon carbide. The first generation of lateral DMOSFETs in 4H-SiC yielded a blocking voltage of 2.6 kV---more than twice what was previously reported for any SiC MOSFETs---but suffered from low MOS channel mobility caused by the high anneal temperatures (≥1600°C) required to activate the p-type ion-implant. Combining the high blocking-voltage of the vanadium-doped substrate with the higher MOS mobility previously achieved by an epitaxially-grown accumulation channel leads us to the LACCUFET device: No p-type implant is necessary. This device shows a blocking voltage of 2.7 kV unmatched by any SiC transistor until February 2000 combined with a much lower specific on-resistance of 3.6 O•cm2. The ability to combine long-channel test MOSFETs with high channel mobility of 27 cm2/(volt·sec) in 4H-SiC with power devices of 13 cm2/(volt·sec) on the same chip has been demonstrated. The Figure of Merit Vblock 2/Ron,sp for this new NON-RESURF LDMOSFET in 4H-SiC is close to the theoretical limit for vertical power devices made of silicon. The specific on-resistance can be reduced by factor 2.5 by forward-biasing the p-base to source junction by 2 to 3 volts. Basic operation in Static Induction Injection Accumulation FET (SIAFET) mode has been demonstrated. Lateral (Non-Punch-Through) Insulated Gate Bipolar Transistors (LIGBT) have been presented for the first time showing similar on-resistance and blocking voltages but

VcBBX, VcMYB21, and VcR2R3MYB Transcription Factors Are Involved in UV-B-Induced Anthocyanin Biosynthesis in the Peel of Harvested Blueberry Fruit.

PubMed

Nguyen, Chau T T; Lim, Sooyeon; Lee, Jeong Gu; Lee, Eun Jin

2017-03-15

This study was carried out to better understand the mechanism responsible for increasing the anthocyanins in blueberries after UV-B radiation at 6.0 kJ m -2 for 20 min. UV-B induced upregulation of genes involved in anthocyanin biosynthesis in blueberry fruit compared to a nontreated control. Phenylalanine ammonia lyase, chalcone synthase, and flavanone 3'-hydroxylase, which are enzymes that function upstream of anthocyanin biosynthesis, were significantly expressed by UV-B. Expression levels of VcBBX, VcMYB21, and VcR2R3MYB transcription factors (TFs) were upregulated by UV-B in the same manner as the anthocyanin biosynthesis genes. The significant increase in the expression of TFs occurred immediately after UV-B treatment and was then maximized within 3 h. In accordance with these changes, individual anthocyanin contents in the fruits treated with UV-B significantly increased within 6 h and were 2-3-fold higher than the control. Our results indicated that UV-B radiation stimulates an increase in anthocyanin biosynthesis, which could be upregulated by the TFs studied.

Selected data fron continental scientific drilling core holes VC-1 and VC-2a, Valles Caldera, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Musgrave, J.A.; Goff, F.; Shevenell, L.

1989-02-01

This report presents geochemical and isotopic data on rocks and water and wellbore geophysical data from the Continental Scientific Drilling Program core holes VC-1 and VC-2a, Valles Caldera, New Mexico. These core holes were drilled as a portion of a broader program that seeks to answer fundamental questions about magma, water/rock interactions, ore deposits, and volcanology. The data in this report will assist the interpretation of the hydrothermal system in the Jemez Mountains and will stimulate further research in magmatic processes, hydrothermal alteration, ore deposits, hydrology, structural geology, and hydrothermal solution chemistry. 37 refs., 36 figs., 28 tabs.

2D molybdenum and vanadium nitrides synthesized by ammoniation of 2D transition metal carbides (MXenes)

DOE PAGES

Urbankowski, Patrick; Anasori, Babak; Hantanasirisakul, Kanit; ...

2017-11-08

MXenes are a rapidly growing class of 2D transition metal carbides and nitrides, finding applications in fields ranging from energy storage to electromagnetic interference shielding and transparent conductive coatings. However, while more than 20 carbide MXenes have already been synthesized, Ti 4N 3 and Ti 2N are the only nitride MXenes reported so far. Here by ammoniation of Mo 2CT x and V 2CT x MXenes at 600 °C, we report on their transformation to 2D metal nitrides. Carbon atoms in the precursor MXenes are replaced with N atoms, resulting from the decomposition of ammonia molecules. The crystal structures ofmore » the resulting Mo 2N and V 2N were determined with transmission electron microscopy and X-ray pair distribution function analysis. Our results indicate that Mo 2N retains the MXene structure and V 2C transforms to a mixed layered structure of trigonal V 2N and cubic VN. Temperature-dependent resistivity measurements of the nitrides reveal that they exhibit metallic conductivity, as opposed to semiconductor-like behavior of their parent carbides. As important, room-temperature electrical conductivity values of Mo2N and V2N are three and one order of magnitude larger than those of the Mo 2CT x and V 2CT x precursors, respectively. In conclusion, this study shows how gas treatment synthesis such as ammoniation can transform carbide MXenes into 2D nitrides with higher electrical conductivities and metallic behavior, opening a new avenue in 2D materials synthesis.« less

Process optimization for diffusion bonding of tungsten with EUROFER97 using a vanadium interlayer

NASA Astrophysics Data System (ADS)

Basuki, Widodo Widjaja; Aktaa, Jarir

2015-04-01

Solid-state diffusion bonding is a selected joining technology to bond divertor components consisting of tungsten and EUROFER97 for application in fusion power plants. Due to the large mismatch in their coefficient of thermal expansions, which leads to serious thermally induced residual stresses after bonding, a thin vanadium plate is introduced as an interlayer. However, the diffusion of carbon originated from EUROFER97 in the vanadium interlayer during the bonding process can form a vanadium carbide layer, which has detrimental influences on the mechanical properties of the joint. For optimal bonding results, the thickness of this layer and the residual stresses has to be decreased sufficiently without a significant reduction of material transport especially at the vanadium/tungsten interface, which can be achieved by varying the diffusion bonding temperature and duration. The investigation results show that at a sufficiently low bonding temperature of 700 °C and a bonding duration of 4 h, the joint reaches a reasonable high ductility and toughness especially at elevated test temperature of 550 °C with elongation to fracture of 20% and mean absorbed Charpy impact energy of 2 J (using miniaturized Charpy impact specimens). The strength of the bonded materials is about 332 MPa at RT and 291 MPa at 550 °C. Furthermore, a low bonding temperature of 700 °C can also help to avoid the grain coarsening and the alteration of the grain structure especially of the EUROFER97 close to the bond interface.

Vanadium Electrolyte Studies for the Vanadium Redox Battery-A Review.

PubMed

Skyllas-Kazacos, Maria; Cao, Liuyue; Kazacos, Michael; Kausar, Nadeem; Mousa, Asem

2016-07-07

The electrolyte is one of the most important components of the vanadium redox flow battery and its properties will affect cell performance and behavior in addition to the overall battery cost. Vanadium exists in several oxidation states with significantly different half-cell potentials that can produce practical cell voltages. It is thus possible to use the same element in both half-cells and thereby eliminate problems of cross-contamination inherent in all other flow battery chemistries. Electrolyte properties vary with supporting electrolyte composition, state-of-charge, and temperature and this will impact on the characteristics, behavior, and performance of the vanadium battery in practical applications. This Review provides a broad overview of the physical properties and characteristics of the vanadium battery electrolyte under different conditions, together with a description of some of the processing methods that have been developed to produce vanadium electrolytes for vanadium redox flow battery applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Vanadium Respiration by Geobacter metallireducens: Novel Strategy for In Situ Removal of Vanadium from Groundwater

PubMed Central

Ortiz-Bernad, Irene; Anderson, Robert T.; Vrionis, Helen A.; Lovley, Derek R.

2004-01-01

Vanadium can be an important contaminant in groundwaters impacted by mining activities. In order to determine if microorganisms of the Geobacteraceae, the predominant dissimilatory metal reducers in many subsurface environments, were capable of reducing vanadium(V), Geobacter metallireducens was inoculated into a medium in which acetate was the electron donor and vanadium(V) was the sole electron acceptor. Reduction of vanadium(V) resulted in the production of vanadium(IV), which subsequently precipitated. Reduction of vanadium(V) was associated with cell growth with a generation time of 15 h. No vanadium(V) was reduced and no precipitate was formed in heat-killed or abiotic controls. Acetate was the most effective of all the electron donors evaluated. When acetate was injected into the subsurface to enhance the growth and activity of Geobacteraceae in an aquifer contaminated with uranium and vanadium, vanadium was removed from the groundwater even more effectively than uranium. These studies demonstrate that G. metallireducens can grow via vanadium(V) respiration and that stimulating the activity of Geobacteraceae, and hence vanadium(V) reduction, can be an effective strategy for in situ immobilization of vanadium in contaminated subsurface environments. PMID:15128571

Self-Supported Biocarbon-Fiber Electrode Decorated with Molybdenum Carbide Nanoparticles for Highly Active Hydrogen-Evolution Reaction.

PubMed

Xiao, Jian; Zhang, Yan; Zhang, Zheye; Lv, Qiying; Jing, Feng; Chi, Kai; Wang, Shuai

2017-07-12

Devising and facilely synthesizing an efficient noble metal-free electrocatalyst for the acceleration of the sluggish kinetics in the hydrogen-evolution reaction (HER) is still a big challenge for electrolytic water splitting. Herein, we present a simple one-step approach for constructing self-supported biocarbon-fiber cloth decorated with molybdenum carbide nanoparticles (BCF/Mo 2 C) electrodes by a direct annealing treatment of the Mo oxyanions loaded cotton T-shirt. The Mo 2 C nanoparticles not only serve as the catalytic active sites toward the HER but also enhance the hydrophilicity and conductivity of resultant electrodes. As an integrated three-dimensional HER cathode catalyst, the BCF/Mo 2 C exhibits outstanding electrocatalytic performance with extremely low overpotentials of 88 and 115 mV to drive a current density of 20 mA cm -2 in alkaline and acidic media, respectively. In addition, it can continuously work for 50 h with little decrease in the cathodic current density in both alkaline and acidic solutions. Even better, self-supported tungsten carbide and vanadium carbide based electrodes also can be prepared by a similar synthesis process. This work will illuminate an entirely new avenue for the preparation of various self-supported three-dimensional electrodes made of transition-metal carbides for various applications.

Effect of contaminant concentration on aerobic microbial mineralization of DCE and VC in stream-bed sediments

USGS Publications Warehouse

Bradley, P.M.; Chapelle, F.H.

1998-01-01

Discharge of DCE and VC to an aerobic surface water system simultaneously represents a significant environmental concern and, potentially, a non-engineered opportunity for efficient contaminant bioremediation. The potential for bioremediation, however, depends on the ability of the stream-bed microbial community to efficiently and completely degrade DCE and VC over a range of contaminant concentrations. The purposes of the studies reported here were to assess the potential for aerobic DCE and VC mineralization by stream-bed microorganisms and to evaluate the effects of DCE and VC concentrations on the apparent rates of aerobic mineralization. Bed-sediment microorganisms indigenous to a creek, where DCE-contaminated groundwater continuously discharges, demonstrated rapid mineralization of DCE and VC under aerobic conditions. Over 8 days, the recovery of [1,2-14C]DCE radioactivity as 14CO2 ranged from 17% to 100%, and the recovery of [1,2- 14C]VC radioactivity as 14CO2 ranged from 45% to 100%. Rates of DCE and VC mineralization increased significantly with increasing contaminant concentration, and the response of apparent mineralization rates to changes in DCE and VC concentrations was adequately described by Michaelis-Menten kinetics.Discharge of DCE and VC to an aerobic surface water system simultaneously represents a significant environmental concern and, potentially, a non-engineered opportunity for efficient contaminant bioremediation. The potential for bioremediation, however, depends on the ability of the stream-bed microbial community to efficiently and completely degrade DCE and VC over a range of contaminant concentrations. The purposes of the studies reported here were to assess the potential for aerobic DCE and VC mineralization by stream-bed microorganisms and to evaluate the effects of DCE and VC concentrations on the apparent rates of aerobic mineralization. Bed-sediment microorganisms indigenous to a creek, where DCE-contaminated groundwater

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

PubMed

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 <1% of the total vanadium readily mobilised. Column experiments revealed that only <0.1% of 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.

75 FR 70690 - Visteon Corporation Springfield Plant Formerly Known as VC Regional Assembly & Manufacturing, LLC...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-18

... Springfield Plant Formerly Known as VC Regional Assembly & Manufacturing, LLC Including On-Site Leased Workers... formerly known as VC Regional Assembly & Manufacturing, LLC. Workers separated from employment at the... name VC Regional Assembly & Manufacturing, LLC. Accordingly, the Department is amending this...

[Accidents of the everyday life (AcVC) in children in Dakar: about 201 cases].

PubMed

Mohamed, Azhar Salim; Sagna, Aloïse; Fall, Mbaye; Ndoye, Ndeye Aby; Mbaye, Papa Alassane; Fall, Aimé Lakh; Diaby, Alou; Ndour, Oumar; Ngom, Gabriel

2017-01-01

Accidents of everyday life (AcVC) are common in children and can led to disabling injuries and death. This study aimed to analyze the epidemiological aspects of AcVC and the related injury mechanisms in Dakar. We conducted a descriptive, cross-sectional study conducted from 1 January 2013 to 30 June 2013. All the children victims of domestic accidents, sport and leisure accidents or school accidents were included. We studied some general parameters and some parameters related to each type of AcVC. Two hundred and one children were included, accounting for 27% of emergency consultations. There were 148 boys and 53 girls. Children less than 5 years of age were most affected (37.8%). Football and wrestling game were the main causes of AcVC. AcVC occur mainly at home (58.2%) and in the areas of sport and recreation (31.8%). The fractures predominated in the different types of AcVC: 54.9% of domestic accidents, 68.8% of sport and recreation accidents and 40% of school accidents. From an epidemiological perspective, our results are superimposable to literature. Fractures predominated contrary to literature where bruises were preponderant. Wrestling game is the main cause of these fractures, after football. The acquisition of knowledge about the epidemiological aspects of AcVC and the related injury mechanisms will allow for prevention campaigns in Dakar.

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

PubMed

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.

Thirty years through vanadium chemistry.

PubMed

Costa Pessoa, J

2015-06-01

The relevance of vanadium in biological systems is known for many years and vanadium-based catalysts have important industrial applications, however, till the beginning of the 80s research on vanadium chemistry and biochemistry did not receive much attention from the scientific community. The understanding of the broad bioinorganic implications resulting from the similarities between phosphate and vanadate(V) and the discovery of vanadium dependent enzymes gave rise to an enormous increase in interest in the chemistry and biological relevance of vanadium. Thereupon the last 30years corresponded to a period of enormous research effort in these fields, as well as in medicinal applications of vanadium and in the development of catalysts for use in fine-chemical synthesis, some of these inspired by enzymatic active sites. Since the 80s my group in collaboration with others made contributions, described throughout this text, namely in the understanding of the speciation of vanadium compounds in aqueous solution and in biological fluids, and to the transport of vanadium compounds in blood plasma and their uptake by cells. Several new types of vanadium compounds were also synthesized and characterized, with applications either as prospective therapeutic drugs or as homogeneous or heterogenized catalysts for the production of fine chemicals. The developments made are described also considering the international context of the evolution of the knowledge in the chemistry and bioinorganic chemistry of vanadium compounds during the last 30years. This article was compiled based on the Vanadis Award presentation at the 9th International Vanadium Symposium. Copyright © 2015 Elsevier Inc. All rights reserved.

Crystal Structure of VC0702 at 2.0 angstrom: A Conserved Hypothetical Protein from Vibrio Cholerae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ni, Shuisong; Forouhar, Farhad; Bussiere, Dirksen E.

2006-06-01

VC0702, a conserved hypothetical protein of unknown function from Vibrio cholerae, resides in a putative three-gene operon containing the MbaA gene, which is involved in regulating formation of the extracellular matrix of biofilms in Vibrio cholerae. The VC0702 crystal structure has been determined at 2.0? and refined to Rwork=22.8% and Rfree=26.3%. VC0702 crystallized in an orthorhombic crystal lattice in the C2221 space group with dimensions of a=66.61 ?, b=88.118 ?, and c=118.35 ? with a homodimer in the asymmetric unit. VC0702 belongs to the Pfam DUF84 and COG1986 family of proteins. Sequence conservation within the DUF84 and COG1986 families wasmore » used to identify a conserved patch of surface residues that define a cleft and potential substrate-binding site in VC0702. The three-dimensional structure of VC0702 is similar to that of Mj0226 from Methanococcus janeshii, which has been identified as a novel NTPase. The NTP-binding site in Mj0226 is similarly located in comparison to the conserved patch of surface residues in VC0702. Furthermore, the NTP binds to MJ0226 in a cleft and deep cavity, features that are present in the VC0702 structure as well, suggesting that VC0702 may have a biochemical function involving NTP binding that is associated with a cellular function of regulating biofilm formation in Vibrio cholerae.« less

Origin of VC-only plumes from naturally enhanced dechlorination in a peat-rich hydrogeologic setting

NASA Astrophysics Data System (ADS)

Filippini, Maria; Amorosi, Alessandro; Campo, Bruno; Herrero-Martìn, Sara; Nijenhuis, Ivonne; Parker, Beth L.; Gargini, Alessandro

2016-09-01

The occurrence of vinyl chloride (VC) is often a main concern at sites contaminated with chlorinated solvents due to its high degree of toxicity and carcinogenicity. VC occurrence in aquifers is most often related to the degradation of higher chlorinated ethenes or ethanes and it is generally detected in plumes along with parent contaminants. However, specific combination of stratigraphic, hydrogeologic and geochemical conditions can enhance the degradation of parents and lead to the formation of plumes almost entirely composed of VC (i.e. VC-only plumes). This paper investigates the causes of VC-only plumes in the aquifers below the city of Ferrara (northern Italy) by combining multiple lines of evidence. The City of Ferrara is located on an alluvial lowland, built by the River Po, and is made up of alternating unconsolidated sandy aquifer and silt-clay aquitard deposits of fluvial origin. This region has been strongly impacted by prior industrial activities, with the occurrence of chlorinated compounds at several sites. VC-only plumes with uncertain source location were found at two contaminated sites. The source zone of a third plume composed of chloroethenes from PCE to VC was investigated for high resolution depositional facies architecture and contaminant distribution (contaminant concentration and Compound Specific Isotope Analysis - CSIA). The investigation suggested that degradation of PCE and TCE takes place during contaminant migration through peat-rich (swamp) layers related to the Holocene transgression, which locally act as a ;reactor; for stimulating degradation with the accumulation of VC in the strongly reducing environment of the peat. Regional-scale stratigraphic architecture showed the ubiquitous occurrence of swamp layers at distinct stratigraphic levels in the investigated system and their apparent linkage to the in situ creation of the VC-only plumes.

Pharmacokinetics of vanadium in humans after intravenous administration of a vanadium containing albumin solution

PubMed Central

Heinemann, Günter; Fichtl, Burckhard; Vogt, Wolfgang

2003-01-01

Aims Vanadium is currently undergoing clinical trials as an oral drug in patients with noninsulin-dependent diabetes mellitus. Furthermore, vanadium occurs in elevated concentrations in the blood of patients receiving intravenous albumin solutions containing large amounts of the metal ion as an impurity. The present study was performed to examine the pharmacokinetics of vanadium in humans following a single intravenous (i.v.) dose of a commercial albumin solution containing a high amount of vanadium. Methods The study was conducted in five healthy volunteer subjects who received intravenously 90 ml of a commercial 20% albumin infusion solution containing 47.6 µg vanadium as an impurity. Vanadium concentrations in serum and urine were determined by electrothermal atomic absorption spectrometry. Results Vanadium serum concentrations after i.v. administration were measured for 31 days. The data could be fitted by a triexponential function corresponding formally to a three-compartment model. There was an initial rapid decrease in serum concentrations with half-lives of 1.2 and 26 h. This was followed by a long-terminal half-life time of 10 days. The terminal phase accounted for about 80% of the total area under the serum concentration-time curve (AUC). The mean apparent volume of distribution of the central compartment was found to be 10 l. The volume of distribution at steady state was 54 l, and total clearance was 0.15 l h−1. Vanadium was mainly excreted by the kidneys. About 52% of the dose was recovered in the urine after 12 days. Conclusions This study provides data on vanadium pharmacokinetics in healthy humans. PMID:12630973

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

PubMed

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 cellmore » 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.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ebbinghaus, Bartley 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 cellmore » 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 2, ThO 2, YDT(0.85ThO 2-0.15YO 1.5), and LDT(0.85ThO 2- 0.15LaO 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.« less

VANADIUM ALLOYS

DOEpatents

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.

A method for recovery of iron, titanium, and vanadium from vanadium-bearing titanomagnetite

NASA Astrophysics Data System (ADS)

Zhang, Yi-min; Wang, Li-na; Chen, De-sheng; Wang, Wei-jing; Liu, Ya-hui; Zhao, Hong-xin; Qi, Tao

2018-02-01

An innovative method for recovering valuable elements from vanadium-bearing titanomagnetite is proposed. This method involves two procedures: low-temperature roasting of vanadium-bearing titanomagnetite and water leaching of roasting slag. During the roasting process, the reduction of iron oxides to metallic iron, the sodium oxidation of vanadium oxides to water-soluble sodium vanadate, and the smelting separation of metallic iron and slag were accomplished simultaneously. Optimal roasting conditions for iron/slag separation were achieved with a mixture thickness of 42.5 mm, a roasting temperature of 1200°C, a residence time of 2 h, a molar ratio of C/O of 1.7, and a sodium carbonate addition of 70wt%, as well as with the use of anthracite as a reductant. Under the optimal conditions, 93.67% iron from the raw ore was recovered in the form of iron nugget with 95.44% iron grade. After a water leaching process, 85.61% of the vanadium from the roasting slag was leached, confirming the sodium oxidation of most of the vanadium oxides to water-soluble sodium vanadate during the roasting process. The total recoveries of iron, vanadium, and titanium were 93.67%, 72.68%, and 99.72%, respectively.

[Oxidative Stress Level of Vanadium-exposed Workers].

PubMed

Wei, Teng-da; Li, Shun-pin; Liu, Yun-xing; Tan, Chun-ping; Li, Juan; Zhang, Zu-hui; Lan, Ya-jia; Zhang, Qin

2015-11-01

To determine the oxidative stress level in peripheral blood of vanadium-exposed workers, as an indication of population health effect of vanadium on human neurobehavioral system. 86 vanadium-exposed workers and 65 non-exposed workers were recruited by cluster sampling. A questionnaire was administered to collect demographic and occupational exposure information. Serum activity of superoxide dismutase (SOD), inducible nitric oxide synthase (iNOS) and malonaldehyde (MDA) contents were detected by kit assay. The differences in oxidative stress level between vanadium-exposed and non-exposed workers were compared. Vanadium-exposed workers had higher levels of MDA contents than the controls. The total superoxide dismutase(T-SOD) activity in vanadium-exposed workers was significantly lower than that in the controls, which was associated with lowered levels of manganese superoxide dismutase (Mn-SOD) activity. No changes in serum levels of cupro-zinc superoxide dismutase (CuZn-SOD) was found in vanadium-exposed workers. No difference in iNOS activity was found between vanadium-exposed workers and controls. Vanadium exposure increases free radical production in serum and reduces antioxidant capacity. But the relationship between vanadium exposure and iNOS damage remains uncertain.

Genetic characterization of ØVC8 lytic phage for Vibrio cholerae O1.

PubMed

Solís-Sánchez, Alejandro; Hernández-Chiñas, Ulises; Navarro-Ocaña, Armando; De la Mora, Javier; Xicohtencatl-Cortes, Juan; Eslava-Campos, Carlos

2016-03-22

Epidemics and pandemics of cholera, a diarrheal disease, are attributed to Vibrio cholera serogroups O1 and O139. In recent years, specific lytic phages of V. cholera have been proposed to be important factors in the cyclic occurrence of cholera in endemic areas. However, the role and potential participation of lytic phages during long interepidemic periods of cholera in non-endemic regions have not yet been described. The purpose of this study was to isolate and characterize specific lytic phages of V. cholera O1 strains. Sixteen phages were isolated from wastewater samples collected at the Endhó Dam in Hidalgo State, Mexico, concentrated with PEG/NaCl, and purified by density gradient. The lytic activity of the purified phages was tested using different V. cholerae O1 and O139 strains. Phage morphology was visualized by transmission electron microscopy (TEM), and phage genome sequencing was performed using the Genome Analyzer IIx System. Genome assembly and bioinformatics analysis were performed using a set of high-throughput programs. Phage structural proteins were analyzed by mass spectrometry. Sixteen phages with lytic and lysogenic activity were isolated; only phage ØVC8 showed specific lytic activity against V. cholerae O1 strains. TEM images of ØVC8 revealed a phage with a short tail and an isometric head. The ØVC8 genome comprises linear double-stranded DNA of 39,422 bp with 50.8 % G + C. Of the 48 annotated ORFs, 16 exhibit homology with sequences of known function and several conserved domains. Bioinformatics analysis showed multiple conserved domains, including an Ig domain, suggesting that ØVC8 might adhere to different mucus substrates such as the human intestinal epithelium. The results suggest that ØVC8 genome utilize the "single-stranded cohesive ends" packaging strategy of the lambda-like group. The two structural proteins sequenced and analyzed are proteins of known function. ØVC8 is a lytic phage with specific activity against V. cholerae

Vanadium distribution in rats and DNA cleavage by vanadyl complex: implication for vanadium toxicity and biological effects.

PubMed Central

Sakurai, H

1994-01-01

Vanadium ion is toxic to animals. However, vanadium is also an agent used for chemoprotection against cancers in animals. To understand both the toxic and beneficial effects we studied vanadium distribution in rats. Accumulation of vanadium in the liver nuclei of rats given low doses of compounds in the +4 or +5 oxidation state was greater than in the liver nuclei of rats given high doses of vanadium compounds or the vanadate (+5 oxidation state) compound. Vanadium was incorporated exclusively in the vanadyl (+4 oxidation state) form. We also investigated the reactions of vanadyl ion and found that incubation of DNA with vanadyl ion and hydrogen peroxide (H2O2) led to intense DNA cleavage. ESR spin trapping demonstrated that hydroxyl radicals are generated during the reactions of vanadyl ion and H2O2. Thus, we propose that the mechanism for vanadium-dependent toxicity and antineoplastic action is due to DNA cleavage by hydroxyl radicals generated in living systems. PMID:7843133

Effects of vanadium and processing parameters on the structures and properties of a direct-quenched low-carbon Mo-B steel

NASA Astrophysics Data System (ADS)

Taylor, K. A.; Hansen, S. S.

1991-10-01

The structures and mechanical properties of a series of thermomechanically processed, direct-quenched martensitic 0.1C-1.4Mn-0.5Mo-B steels containing from 0 to 0.24 wt pct va have been investigated and compared to those obtained after a conventional austenitizing-and-quenching treatment. For all processing conditions, vanadium additions to the base composition are found to increase hardenability (ideal critical parameter, D,); the largest effects (up to a 90 pct increase in D I) are noted when samples are hot-rolled prior to direct quenching. Vanadium additions are also observed to provide significant strengthening in the quenched-and-tempered condition as the result of the precipitation of fine V-Mo carbides. The strengthening increment due to these precipitates is approximately 100 MPa/0.1 wt pct V over the range of vanadium additions examined. At the same time, however, these precipitates reduce notch toughness; on the average, the 20 J transition temperature increases by about 4 °C for each 10 MPa increment in yield strength. For the conditions examined, the best balance of strength and toughness is obtained in direct-quenched samples which are control-rolled (i.e., rolling is completed below the austenite recrystallization temperature) prior to quenching.

[VC and DCE in groundwater and drainage channel water].

PubMed

Ackermann, A

2004-12-01

In an area used merely for gardening in a downland moor, which is partly transformed to an industrial estate, accidentally a contamination of a drainage channel with VOC's - predominantly chloroethylene (vinyl chloride [VC]) and 1.2-cis-dichloroethylene (DCE) - was found. The ascending ground water leaks into the drainage channels. The dissolved harmful substances (water solubility of VC is 1.6 g/l) can reach the radix range of plants and fruit bosks and can theoretically be incorporated with the water influx. Additionally the water from the drainage channels can be used to water the crops. Six gardens and a housing were involved. In the groundwater of the mainly concerned region max. 5,000 microg/l VOC's (quite predominantly VC and DCE) was measured from 147 samples. In the drainage channel water max. 2,500 microg/l was measured from 52 samples (limit value according to the drinking water ordinance is 10 microg/l). In the sediment of the channel with approximately 60,000 microg/kg VOC was found in dry matter (6 samples). We describe, how the consumer protection dept. dealt with this unexpected situation and what measures were taken. The impact on human health by the contaminated ground and channel water or by means of contaminated plants are determined for tree fruits, potatoes, bulbs and carrots. The soil air was contaminated, but in buildings no harmful compounds were detectioned.

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

NASA Astrophysics Data System (ADS)

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.

The material performance of HSS (high speed steel) tools and its relation with chemical composition and carbide distribution

NASA Astrophysics Data System (ADS)

Darmawan, B.; Kusman, M.; Hamdani, R. A.

2016-04-01

The study aims to compare the performance of two types of material HSS (High Speed Steel) are widely used. It also will be the chemical composition and distribution of carbide particles therein. Two types of HSS are available in the market: HSS from Germany (Bohler) and HSS from China. This research employed the pure experimental design. It consists of two stages. The first, aims to test/operate lathe machines to determine the lifetime and performance of tools based on specified wear criteria. The second, characterization of microstructure using SEM-EDS was conducted. Firstly, grinding of toolss was done so that the toolss could be used for cutting metal in the turning process. Grinding processes of the two types of toolss were done at the same geometry, that is side rake angle (12°-18°), angle of keenness (60°-68°), and side relief angle (10°-12°). Likewise, machining parameters were set in the same machining conditions. Based on the results of the tests, it is found that to reach 0.2 mm wear point, toolss made of HSS from Germany needed 24 minutes, while toolss made of HSS from China needed 8 minutes. Next, microstructure tests using SEM/EDS were done. The results of the SEM tests indicate that the carbide particles of HSS from Germany were more evenly distributed than the carbide particles of HSS from China. Carbide compounds identified in HSS from China were Cr23C6 and Fe4Mo2C. Oxide impurity of Al2O3 was also found in the material. On the other hand, in HSS from Germany, no impurity and other carbide compounds were identified, except Cr23C6 and Fe4Mo2C, also Fe4W2C, and VC or V4C3.

Effects of dietary vanadium in mallard ducks

USGS Publications Warehouse

White, D.H.; Dieter, M.P.

1978-01-01

Adult mallard ducks fed 0, 1, 10, or 100 ppm vanadyl sulfate in the diet were sacrificed after 12 wk on treatment; tissues were analyzed for vanadium. No birds died during the study and body weights did not change. Vanadium accumulated to higher concentrations in the bone and liver than in other tissues. Concentrations in bones of hens were five times those in bones of drakes, suggesting an interaction between vanadium and calcium mobilization in laying hens. Vanadium concentrations in most tissues were significantly correlated and increased with treatment level. Lipid metabolism was altered in laying hens fed 100 ppm vanadium. Very little vanadium accumulated in the eggs of laying hens.

Release kinetics of vanadium from vanadium (III, IV and V) oxides: Effect of pH, temperature and oxide dose.

PubMed

Hu, Xingyun; Yue, Yuyan; Peng, Xianjia

2018-05-01

Batch experiments were performed to derive the rate laws for the proton-promoted dissolution of the main vanadium (III, IV and V) oxides at pH 3.1-10.0. The release rates of vanadium are closely related to the aqueous pH, and several obvious differences were observed in the release behavior of vanadium from the dissolution of V 2 O 5 and vanadium(III, IV) oxides. In the first 2hr, the release rates of vanadium from V 2 O 3 were r=1.14·([H + ]) 0.269 at pH 3.0-6.0 and r=0.016·([H + ]) -0.048 at pH 6.0-10.0; the release rates from VO 2 were r=0.362·([H + ]) 0.129 at pH 3.0-6.0 and r=0.017·([H + ]) -0.097 at pH 6.0-10.0; and the release rates from V 2 O 5 were r=0.131·([H + ]) -0.104 at pH 3.1-10.0. The release rates of vanadium from the three oxides increased with increasing temperature, and the effect of temperature was different at pH 3.8, pH 6.0 and pH 7.7. The activation energies of vanadium (III, IV and V) oxides (33.4-87.5kJ/mol) were determined at pH 3.8, pH6.0 and pH 7.7, showing that the release of vanadium from dissolution of vanadium oxides follows a surface-controlled reaction mechanism. The release rates of vanadium increased with increasing vanadium oxides dose, albeit not proportionally. This study, as part of a broader study of the release behavior of vanadium, can help to elucidate the pollution problem of vanadium and to clarify the fate of vanadium in the environment. Copyright © 2017. Published by Elsevier B.V.

SUPERCONDUCTING VANADIUM BASE ALLOY

DOEpatents

Cleary, H.J.

1958-10-21

A new vanadium-base alloy which possesses remarkable superconducting properties is presented. The alloy consists of approximately one atomic percent of palladium, the balance being vanadium. The alloy is stated to be useful in a cryotron in digital computer circuits.

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

PubMed

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.

Influence of vanadium on serum lipid and lipoprotein profiles: a population-based study among vanadium exposed workers

PubMed Central

2014-01-01

Background Some experimental animal studies reported that vanadium had beneficial effects on blood total cholesterol (TC) and triglyceride (TG). However, the relationship between vanadium exposure and lipid, lipoprotein profiles in human subjects remains uncertain. This study aimed to compare the serum lipid and lipoprotein profiles of occupational vanadium exposed and non-exposed workers, and to provide human evidence on serum lipid, lipoprotein profiles and atherogenic indexes changes in relation to vanadium exposure. Methods This cross-sectional study recruited 533 vanadium exposed workers and 241 non-exposed workers from a Steel and Iron Group in Sichuan, China. Demographic characteristics and occupational information were collected through questionnaires. Serum lipid and lipoprotein levels were measured for all participants. The ratios of total cholesterol to high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) to HDL-C and apoB to apoA-I were used as atherogenic indexes. A general linear model was applied to compare outcomes of the two groups while controlling possible confounders and multivariate logistic regression was performed to evaluate the relationship between low HDL-C level, abnormal atherogenic index and vanadium exposure. Results Higher levels of HDL-C and apoA-I could be observed in the vanadium exposed group compared with the control group (P < 0.05). Furthermore, atherogenic indexes (TC/HDL-C, LDL-C/HDL-C, and apoB/apoA-I ratios) were found statistically lower in the vanadium exposed workers (P < 0.05). Changes in HDL-C, TC/HDL-C, and LDL-C/HDL-C were more pronounced in male workers than that in female workers. In male workers, after adjusting for potential confounding variables as age, habits of smoking and drinking, occupational vanadium exposure was still associated with lower HDL-C (OR 0.41; 95% CI, 0.27-0.62) and abnormal atherogenic index (OR 0.38; 95% CI, 0.20-0.70). Conclusion Occupational

Efficient Separation and Extraction of Vanadium and Chromium in High Chromium Vanadium Slag by Selective Two-Stage Roasting-Leaching

NASA Astrophysics Data System (ADS)

Wen, Jing; Jiang, Tao; Xu, Yingzhe; Liu, Jiayi; Xue, Xiangxin

2018-06-01

Vanadium and chromium are important rare metals, leading to a focus on high chromium vanadium slag (HCVS) as a potential raw material to extract vanadium and chromium in China. In this work, a novel method based on selective two-stage roasting-leaching was proposed to separate and extract vanadium and chromium efficiently in HCVS. XRD, FT-IR, and SEM were utilized to analyze the phase evolutions and microstructure during the whole process. Calcification roasting, which can calcify vanadium selectively using thermodynamics, was carried out in the first roasting stage to transfer vanadium into acid-soluble vanadate and leave chromium in the leaching residue as (Fe0.6Cr0.4)2O3 after H2SO4 leaching. When HCVS and CaO were mixed in the molar ratio CaO/V2O3 (n(CaO)/n(V2O3)) of 0.5 to 1.25, around 90 pct vanadium and less than 1 pct chromium were extracted in the first leaching liquid, thus achieving the separation of vanadium and chromium. In the second roasting stage, sodium salt, which combines with chromium easily, was added to the first leaching residue to extract chromium and 95.16 pct chromium was extracted under the optimal conditions. The total vanadium and chromium leaching rates were above 95 pct, achieving the efficient separation and extraction of vanadium and chromium. The established method provides a new technique to separate vanadium and chromium during roasting rather than in the liquid form, which is useful for the comprehensive application of HCVS.

Efficient Separation and Extraction of Vanadium and Chromium in High Chromium Vanadium Slag by Selective Two-Stage Roasting-Leaching

NASA Astrophysics Data System (ADS)

Wen, Jing; Jiang, Tao; Xu, Yingzhe; Liu, Jiayi; Xue, Xiangxin

2018-04-01

Vanadium and chromium are important rare metals, leading to a focus on high chromium vanadium slag (HCVS) as a potential raw material to extract vanadium and chromium in China. In this work, a novel method based on selective two-stage roasting-leaching was proposed to separate and extract vanadium and chromium efficiently in HCVS. XRD, FT-IR, and SEM were utilized to analyze the phase evolutions and microstructure during the whole process. Calcification roasting, which can calcify vanadium selectively using thermodynamics, was carried out in the first roasting stage to transfer vanadium into acid-soluble vanadate and leave chromium in the leaching residue as (Fe0.6Cr0.4)2O3 after H2SO4 leaching. When HCVS and CaO were mixed in the molar ratio CaO/V2O3 (n(CaO)/n(V2O3)) of 0.5 to 1.25, around 90 pct vanadium and less than 1 pct chromium were extracted in the first leaching liquid, thus achieving the separation of vanadium and chromium. In the second roasting stage, sodium salt, which combines with chromium easily, was added to the first leaching residue to extract chromium and 95.16 pct chromium was extracted under the optimal conditions. The total vanadium and chromium leaching rates were above 95 pct, achieving the efficient separation and extraction of vanadium and chromium. The established method provides a new technique to separate vanadium and chromium during roasting rather than in the liquid form, which is useful for the comprehensive application of HCVS.

Commercialization of the Chevron FCC vanadium trap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kennedy, J.V.; Kuehler, C.W.; Krishna, A.S.

1995-09-01

Vanadium, present to varying degrees in FCC feed, deposits on the catalyst virtually quantitatively in the cracking process. In resid operations, vanadium levels on catalyst can reach 10,000 ppm at typical catalyst make-up rates. Once on the catalyst, vanadium destroys the zeolite and restricts access to active sites. This reduces catalyst activity. A vanadium trap is a material that when introduced into the catalyst inventory selectively reacts with migrating vanadium, thus protecting the zeolite and other active components of the catalyst. The trap may be incorporated into the catalyst, or introduced as a separate particle. Only a limited amount ofmore » trap can be incorporated into the catalyst without limiting the amount of zeolite that can be included. Gulf began development of a vanadium trap during the early 1980`s. The work produced a variety of promising materials whose use as vanadium traps was subsequently patented. The work ultimately led to a formulation with a phase very active for trapping vanadium while still quite sulfur tolerant. Based on these results, an extensive pilot plant evaluation was undertaken by Chevron after the Chevron-Gulf merger to better simulate commercial operation. The paper describes pilot plant tests as well as 3 commercial tests of this vanadium trap.« less

Controlled coordination in vanadium(V) dimethylhydrazido compounds.

PubMed

Sakuramoto, Takashi; Moriuchi, Toshiyuki; Hirao, Toshikazu

2016-11-01

The vanadium(V) dimethylhydrazido compounds were structurally characterized to elucidate the effect of the alkoxide ligands in the coordination environment of vanadium(V) hydrazido center. The single-crystal X-ray structure determination of the vanadium(V) dimethylhydrazido compound with isopropoxide ligands revealed a dimeric structure with the V(1)-N(1) distance of 1.680(5)Å, in which each vanadium atom is coordinated in a distorted trigonal-bipyramidal geometry (τ 5 =0.81) with the hydrazido and bridging isopropoxide ligands in the apical positions. On the contrary, nearly tetrahedral arrangement around the vanadium metal center (τ 4 =0.06) with the V(1)-N(1) distance of 1.660(2)Å was observed in the vanadium(V) dimethylhydrazido compound with tert-butoxide ligands. The introduction of the 2,2',2″-nitrilotriethoxide ligand led to a pseudo-trigonal-bipyramidal geometry (τ 5 =0.92) at the vanadium center with the V(1)-N(1) distance of 1.691(5)Å, wherein vanadium atom is pulled out of the plane formed by the nitrilotriethoxide oxygen atoms in the direction of the hydrazido nitrogen. The coordination from the apical ligand in the vanadium(V) dimethylhydrazido compound was found to result in the longer V(1)-N(1) distance. Copyright © 2016 Elsevier Inc. All rights reserved.

Homology of vanadium oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vasyutinskii, N.A.

1987-05-01

The authors examine the homology of vanadium oxide and note that data on the existence of phases and homogeneity limits in the V-O system are very contradictory. A graphical illustration shows the homologous series of vanadium oxides. The predominant part of the discrete formations in the system V-O is characterized by integral stoichiometry and forms six homologous series. It is found that homologous series of vanadium oxides are not only a basis for systematization of such oxides, but also may serve as a means for predicting the composition of new phases, limits of homogeneity, their structure, and properties.

Vanadium-Binding Ability of Nucleoside Diphosphate Kinase from the Vanadium-Rich Fan Worm, Pseudopotamilla occelata.

PubMed

Yamaguchi, Nobuo; Yoshinaga, Masafumi; Kamino, Kei; Ueki, Tatsuya

2016-06-01

Polychaete fan worms and ascidians accumulate high levels of vanadium ions. Several vanadiumbinding proteins, known as vanabins, have been found in ascidians. However, no vanadium-binding factors have been isolated from the fan worm. In the present study, we sought to identify vanadiumbinding proteins in the branchial crown of the fan worm using immobilized metal ion affinity chromatography. A nucleoside diphosphate kinase (NDK) homolog was isolated and determined to be a vanadium-binding protein. Kinase activity of the NDK homologue, PoNDK, was suppressed by the addition of V(IV), but was unaffected by V(V). The effect of V(IV) on PoNDK precedes its activation by Mg(II). This is the first report to describe the relationship between NDK and V(IV). PoNDK is located in the epidermis of the branchial crown, and its distribution is very similar to that of vanadium. These results suggest that PoNDK is associated with vanadium accumulation and metabolism in P. occelata.

Vanadium recycling in the United States in 2004

USGS Publications Warehouse

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).

Isolation and Structural Characterization of Two Very Large, and Largely Empty, Endohedral Fullerenes: Tm@C3v-C94 and Ca@C3v-C94

PubMed Central

Che, Yuliang; Yang, Hua; Wang, Zhimin; Jin, Hongxiao; Lu, Chunxin; Zuo, Tianming; Beavers, Christine M.

2009-01-01

The structures of two newly synthesized endohedral fullerenes - Tm@C3v-C94 and Ca@C3v-C94 - have been determined by single crystal X-ray diffraction on samples co-crystallized with NiII(octaethylporphyrin). Both compounds exhibit the same cage geometry and conform to the isolated pentagon rule (IPR). The metal ions within these rather large cages are localized near one end and along the C3 axis. While the calcium ion is situated over a C-C bond at a 6:6 ring junction, the thulium ion is positioned above a six-membered ring of the fullerene. PMID:19507844

Comparison of Ultrasound-Assisted and Regular Leaching of Vanadium and Chromium from Roasted High Chromium Vanadium Slag

NASA Astrophysics Data System (ADS)

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.

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

PubMed

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.

Perineuronal nets labeled by monoclonal antibody VC1.1 ensheath interneurons expressing parvalbumin and calbindin in the rat amygdala

PubMed Central

McDonald, Alexander J.; Hamilton, Patricia G.; Barnstable, Colin J.

2018-01-01

Perineuronal nets (PNNs) are specialized condensations of extracellular matrix that ensheath particular neuronal subpopulations in the brain and spinal cord. PNNs regulate synaptic plasticity, including the encoding of fear memories by the amygdala. The present immunohistochemical investigation studied PNN structure and distribution, as well as the neurochemistry of their ensheathed neurons, in the rat amygdala using monoclonal antibody VC1.1, which recognizes a glucuronic acid 3-sulfate glycan associated with PNNs in the cerebral cortex. VC1.1+ PNNs surrounded the cell bodies and dendrites of a subset of nonpyramidal neurons in cortex-like portions of the amygdala (basolateral amygdalar complex, cortical nuclei, nucleus of the lateral olfactory tract, and amygdalohippocampal region). There was also significant neuropilar VC1.1 immunoreactivity whose density varied in different amygdalar nuclei. Cell counts in the basolateral nucleus revealed that virtually all neurons ensheathed by VC1.1+ PNNs were parvalbumin-positive (PV+) interneurons, and these VC1.1+/PV+ cells constituted 60% of all PV+ interneurons, including all of the larger PV+ neurons. Approximately 70% of VC1.1+ neurons were calbindin-positive (CB+), and these VC1.1+/CB+ cells constituted about 40% of all CB+ neurons. Colocalization of VC1.1 with Vicia villosa agglutinin (VVA) binding, which stains terminal N-acetylgalactosamines, revealed that VC1.1+ PNNs were largely a subset of VVA+ PNNs. This investigation provides baseline data regarding PNNs in the rat which should be useful for future studies of their function in this species. PMID:29094304

Myosin Vc Interacts with Rab32 and Rab38 Proteins and Works in the Biogenesis and Secretion of Melanosomes*

PubMed Central

Bultema, Jarred J.; Boyle, Judith A.; Malenke, Parker B.; Martin, Faye E.; Dell'Angelica, Esteban C.; Cheney, Richard E.; Di Pietro, Santiago M.

2014-01-01

Class V myosins are actin-based motors with conserved functions in vesicle and organelle trafficking. Herein we report the discovery of a function for Myosin Vc in melanosome biogenesis as an effector of melanosome-associated Rab GTPases. We isolated Myosin Vc in a yeast two-hybrid screening for proteins that interact with Rab38, a Rab protein involved in the biogenesis of melanosomes and other lysosome-related organelles. Rab38 and its close homolog Rab32 bind to Myosin Vc but not to Myosin Va or Myosin Vb. Binding depends on residues in the switch II region of Rab32 and Rab38 and regions of the Myosin Vc coiled-coil tail domain. Myosin Vc also interacts with Rab7a and Rab8a but not with Rab11, Rab17, and Rab27. Although Myosin Vc is not particularly abundant on pigmented melanosomes, its knockdown in MNT-1 melanocytes caused defects in the trafficking of integral membrane proteins to melanosomes with substantially increased surface expression of Tyrp1, nearly complete loss of Tyrp2, and significant Vamp7 mislocalization. Knockdown of Myosin Vc in MNT-1 cells more than doubled the abundance of pigmented melanosomes but did not change the number of unpigmented melanosomes. Together the data demonstrate a novel role for Myosin Vc in melanosome biogenesis and secretion. PMID:25324551

Bioleaching of vanadium from barren stone coal and its effect on the transition of vanadium speciation and mineral phase

NASA Astrophysics Data System (ADS)

Wang, Xin; Lin, Hai; Dong, Ying-bo; Li, Gan-yu

2018-03-01

This study determined the optimal conditions required to obtain maximum vanadium extraction and examined the transition of mineral phases and vanadium speciation during the bioleaching process. Parameters including the initial pH value, initial Fe2+ concentration, solid load, and inoculum quantity were examined. The results revealed that 48.92wt% of the vanadium was extracted through bioleaching under optimal conditions. Comparatively, the chemical leaching yield (H2SO4, pH 2.0) showed a slower and milder increase in vanadium yield. The vanadium bioleaching yield was 35.11wt% greater than the chemical leaching yield. The Community Bureau of Reference (BCR) sequential extraction results revealed that 88.62wt% of vanadium existed in the residual fraction. The bacteria substantially changed the distribution of the vanadium speciation during the leaching process, and the residual fraction decreased to 48.44wt%. The X-ray diffraction (XRD) and Fourier transform infrared (FTIR) results provided evidence that the crystal lattice structure of muscovite was destroyed by the bacteria.

Memory Deficit Recovery after Chronic Vanadium Exposure in Mice.

PubMed

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.

Methods for making lithium vanadium oxide electrode materials

DOEpatents

Schutts, Scott M.; Kinney, Robert J.

2000-01-01

A method of making vanadium oxide formulations is presented. In one method of preparing lithium vanadium oxide for use as an electrode material, the method involves: admixing a particulate form of a lithium compound and a particulate form of a vanadium compound; jet milling the particulate admixture of the lithium and vanadium compounds; and heating the jet milled particulate admixture at a temperature below the melting temperature of the admixture to form lithium vanadium oxide.

Long-term immunogenicity of an initial booster dose of an inactivated, Vero cell culture-derived Japanese encephalitis vaccine (JE-VC) and the safety and immunogenicity of a second JE-VC booster dose in children previously vaccinated with an inactivated, mouse brain-derived Japanese encephalitis vaccine.

PubMed

Yun, Ki Wook; Lee, Hoan Jong; Park, Ji Young; Cho, Hye-Kyung; Kim, Yae-Jean; Kim, Kyung-Hyo; Kim, Nam Hee; Hong, Young Jin; Kim, Dong Ho; Kim, Hwang Min; Cha, Sung-Ho

2018-03-07

This study was performed with the aim of determining the long-term immunogenicity of an inactivated, Vero cell culture-derived Japanese encephalitis (JE) vaccine (JE-VC) and an inactivated, mouse brain-derived JE vaccine (JE-MB) after the 1st booster dose at 2 years of age, as well as the safety and immunogenicity of the 2nd booster dose of JE-VC at 6 years of age, in children primed and given a 1st booster dose of either JE-VC or JE-MB. In this multicenter, open-label clinical trial, the study population consisted of healthy Korean children (aged 6 years) who participated in the previous JE vaccine trial. All subjects were subcutaneously vaccinated once for the booster immunization with Boryung Cell Culture Japanese Encephalitis Vaccine® (JE-VC). Approximately 4 years after the 1st booster dose of JE-VC, the seroprotection rate (SPR) and geometric mean titer (GMT) of the neutralizing antibody were 100% and 1113.8, respectively. In children primed and given a 1st booster dose of JE-MB, the SPR and GMT were 88.5% and 56.3, respectively. After the 2nd booster dose of JE-VC, all participants primed and given a 1st booster dose of either JE-MB or JE-VC were seroprotective against JE virus. The GMT of the neutralizing antibody was higher in children primed and given a 1st booster dose of JE-VC (8144.1) than in those primed and given a 1st booster dose of JE-MB (942.5) after the vaccination (p < 0.001). In addition, the 2nd booster dose of JE-VC showed a good safety profile with no serious vaccine-related adverse events. The 1st booster dose of JE-VC and JE-MB showed long-term immunogenicity of at least 4 years, and the 2nd booster dose of JE-VC showed a good safety and immunogenicity profile in children primed and given a 1st booster dose of either JE-VC or JE-MB. ClinicalTtrials.gov Identifier: NCT02532569. Copyright © 2018 Elsevier Ltd. All rights reserved.

Vanadium pentoxide nanoparticles mimic vanadium haloperoxidases and thwart biofilm formation

NASA Astrophysics Data System (ADS)

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.

Optimizing the dual elemental thermal reactive deposition time in carbide layer formation on SUJ2 tool steel

NASA Astrophysics Data System (ADS)

Mochtar, Myrna Ariati; Putra, Wahyuaji Narottama; Mahardika, Bayu

2018-05-01

This paper presents developments contributing to the improvement of thermo-reactive deposition (TRD) process in producing hard carbide layers, on automotive components application. The problem in using FeV powder as a coating material that has been applied in the industries is it is high cost. In this study, FeCr powder coating material was mixed into FeV powder with a ratio of 35:65 weight percent. The SUJ2 steel pins components are processed at 980° C, with varying TRD time was 4,6,8 and 10 hours. Scanning Electron microscope (SEM), Electron Probe Micro Analyzer (EPMA) and X-ray diffraction (XRD) were applied to analyze the coating layers. The thickness of the carbide layer formed will increase with the longer processing time, which thickness at 4-10 hours is increase from 22.7 to 29.7 micron. The gained thickness tends to be homogeneous. Increasing the TRD process holding time results in a higher hardness of the carbide layerwith hardness at 4, 6, 8 and 10 hours is 2049, 2184, 2175 and 2343 HV. The wear rate at TRD holding time of 4-10 hours with the Ogoshi method was reduced from 5.1 × 10-4 mm3/m to 2.5 × 10-4 mm3/m. Optical microscope observations shows that substrate phases consisting of pearlite and cementite and grains that tend to enlarge with the addition of time. Carbide compounds that are formed are vanadium carbide (V8C7, V6C5, V2C) and chromium carbide (Cr3C2, Cr23C7, Cr3C7). While EDS-Linescan results show complex phase (Fe, V, Cr) xC formed. The research shows that addition of FeCr into FeV powder in TRD process in 980°C with optimum time of 10 hours processing meet the mechanical properties requirement of automotive components.

Myosin vc interacts with Rab32 and Rab38 proteins and works in the biogenesis and secretion of melanosomes.

PubMed

Bultema, Jarred J; Boyle, Judith A; Malenke, Parker B; Martin, Faye E; Dell'Angelica, Esteban C; Cheney, Richard E; Di Pietro, Santiago M

2014-11-28

Class V myosins are actin-based motors with conserved functions in vesicle and organelle trafficking. Herein we report the discovery of a function for Myosin Vc in melanosome biogenesis as an effector of melanosome-associated Rab GTPases. We isolated Myosin Vc in a yeast two-hybrid screening for proteins that interact with Rab38, a Rab protein involved in the biogenesis of melanosomes and other lysosome-related organelles. Rab38 and its close homolog Rab32 bind to Myosin Vc but not to Myosin Va or Myosin Vb. Binding depends on residues in the switch II region of Rab32 and Rab38 and regions of the Myosin Vc coiled-coil tail domain. Myosin Vc also interacts with Rab7a and Rab8a but not with Rab11, Rab17, and Rab27. Although Myosin Vc is not particularly abundant on pigmented melanosomes, its knockdown in MNT-1 melanocytes caused defects in the trafficking of integral membrane proteins to melanosomes with substantially increased surface expression of Tyrp1, nearly complete loss of Tyrp2, and significant Vamp7 mislocalization. Knockdown of Myosin Vc in MNT-1 cells more than doubled the abundance of pigmented melanosomes but did not change the number of unpigmented melanosomes. Together the data demonstrate a novel role for Myosin Vc in melanosome biogenesis and secretion. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Memory Deficit Recovery after Chronic Vanadium Exposure in Mice

PubMed Central

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. PMID:26962395

The bacterial dicarboxylate transporter, VcINDY, uses a two-domain elevator-type mechanism

PubMed Central

Mulligan, Christopher; Fenollar-Ferrer, Cristina; Fitzgerald, Gabriel A.; Vergara-Jaque, Ariela; Kaufmann, Desirée; Li, Yan; Forrest, Lucy R.; Mindell, Joseph A.

2016-01-01

Secondary transporters use alternating access mechanisms to couple uphill substrate movement to downhill ion flux. Most known transporters utilize a “rocking bundle” motion, where the protein moves around an immobile substrate binding site. However, the glutamate transporter homolog, GltPh, translocates its substrate binding site vertically across the membrane, an “elevator” mechanism. Here, we used the “repeat swap” approach to computationally predict the outward-facing state of the Na+/succinate transporter VcINDY, from Vibrio cholerae. Our model predicts a substantial “elevator”-like movement of vcINDY’s substrate binding site, with a vertical translation of ~15 Å and a rotation of ~43°; multiple disulfide crosslinks which completely inhibit transport provide experimental confirmation and demonstrate that such movement is essential. In contrast, crosslinks across the VcINDY dimer interface preserve transport, revealing an absence of large scale coupling between protomers. PMID:26828963

Tool wear mechanisms in turning titanium-aluminum-vanadium using tungsten carbide and polycrystalline diamond inserts

NASA Astrophysics Data System (ADS)

Schrock, David James

The objective of this work is to identify some of the tool wear mechanisms at the material level for the machining of titanium and to provide some understanding of these mechanisms for use in physics based tool wear models. Turning experiments were conducted at cutting speeds of 61m/min, 91m/min, and 122m/min on Ti-6Al-4V, an alloy of titanium, using two different grades of tungsten carbide cutting inserts and one grade of polycrystalline diamond inserts. Three-dimensional wear data and two-dimensional wear profiles of the rake face were generated using Confocal Laser Scanning Microscopy to quantify the tool wear mechanisms. Additionally, the microstructure of the deformed work material (chip) and un-deformed parent material (work piece) were studied using Orientation Imaging Microscopy (OIM). Observations from tool wear studies on the PCD inserts revealed the presence of two fundamentally different wear mechanisms operating at the different cutting speeds. Microstructural analyses of the chip and the work material showed phase dependent tool wear mechanisms for machining titanium. There is a high likelihood of phase change occurring in the work material during machining, with a transformation from the alpha phase to the beta phase. The observed dramatic increase in wear is attributed to a combination of increased diffusivity in the beta phase of the titanium alloy in conjunction with a higher degree of recrystallization of the prior beta phase upon cooling. Results of other observations such as the influence of carbide grain size on tool wear are also discussed.

Improved toughness of silicon carbide

NASA Technical Reports Server (NTRS)

Palm, J. A.

1976-01-01

Impact energy absorbing layers (EALs) comprised of partially densified silicon carbide were formed in situ on fully sinterable silicon carbide substrates. After final sintering, duplex silicon carbide structures resulted which were comprised of a fully sintered, high density silicon carbide substrate or core, overlayed with an EAL of partially sintered silicon carbide integrally bonded to its core member. Thermal cycling tests proved such structures to be moderately resistant to oxidation and highly resistant to thermal shock stresses. The strength of the developed structures in some cases exceeded but essentially it remained the same as the fully sintered silicon carbide without the EAL. Ballistic impact tests indicated that substantial improvements in the toughness of sintered silicon carbide were achieved by the use of the partially densified silicon carbide EALs.

Vanadium in landscape components of western Transbaikalia

NASA Astrophysics Data System (ADS)

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.

The role of vanadium in biology.

PubMed

Rehder, Dieter

2015-05-01

Vanadium is special in at least two respects: on the one hand, the tetrahedral anion vanadate(v) is similar to the phosphate anion; vanadate can thus interact with various physiological substrates that are otherwise functionalized by phosphate. On the other hand, the transition metal vanadium can easily expand its sphere beyond tetrahedral coordination, and switch between the oxidation states +v, +iv and +iii in a physiological environment. The similarity between vanadate and phosphate may account for the antidiabetic potential of vanadium compounds with carrier ligands such as maltolate and picolinate, and also for vanadium's mediation in cardiovascular and neuronal defects. Other potential medicinal applications of more complex vanadium coordination compounds, for example in the treatment of parasitic tropical diseases, may also be rooted in the specific properties of the ligand sphere. The ease of the change in the oxidation state of vanadium is employed by prokarya (bacteria and cyanobacteria) as well as by eukarya (algae and fungi) in respiratory and enzymatic functions. Macroalgae (seaweeds), fungi, lichens and Streptomyces bacteria have available haloperoxidases, and hence enzymes that enable the 2-electron oxidation of halide X(-) with peroxide, catalyzed by a Lewis-acidic V(V) center. The X(+) species thus formed can be employed to oxidatively halogenate organic substrates, a fact with implications also for the chemical processes in the atmosphere. Vanadium-dependent nitrogenases in bacteria (Azotobacter) and cyanobacteria (Anabaena) convert N2 + H(+) to NH4(+) + H2, but are also receptive for alternative substrates such as CO and C2H2. Among the enigmas to be solved with respect to the utilization of vanadium in nature is the accumulation of V(III) by some sea squirts and fan worms, as well as the purport of the nonoxido V(IV) compound amavadin in the fly agaric.

The role of phosphate additive in stabilization of sulphuric-acid-based vanadium(V) electrolyte for all-vanadium redox-flow batteries

NASA Astrophysics Data System (ADS)

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.

Diffusion mechanism in molten salt baths during the production of carbide coatings via thermal reactive diffusion

NASA Astrophysics Data System (ADS)

Ghadi, Aliakbar; Saghafian, Hassan; Soltanieh, Mansour; Yang, Zhi-gang

2017-12-01

The diffusion mechanism of carbide-forming elements from a molten salt bath to a substrate surface was studied in this research, with particular focus on the processes occurring in the molten bath at the time of coating. Metal, oxide, and metal-oxide baths were investigated, and the coating process was performed on H13 steel substrates. Scanning electron microscopy and electron-probe microanalysis were used to study the coated samples and the quenched salt bath. The thickness of the carbide coating layer was 6.5 ± 0.5, 5.2 ± 0.5, or 5.7 ± 0.5 μm depending on whether it was deposited in a metal, oxide, or metal-oxide bath, respectively. The phase distribution of vanadium-rich regions was 63%, 57%, and 74% of the total coating deposited in metal, oxide, and metal-oxide baths, respectively. The results obtained using the metal bath indicated that undissolved suspended metal particles deposited onto the substrate surface. Then, carbon subsequently diffused to the substrate surface and reacted with the metal particles to form the carbides. In the oxide bath, oxide powders dissolved in the bath with or without binding to the oxidative structure (Na2O) of borax; they were then reduced by aluminum and converted into metal particles. We concluded that, in the metal and oxide baths, the deposition of metal particles onto the sample surface is an important step in the formation of the coating.

Mineral resource of the month: vanadium

USGS Publications Warehouse

Magyar, Michael J.

2007-01-01

Vanadium, the name of which comes from Vanadis, a goddess in Scandinavian mythology, is one of the most important ferrous metals. Vanadium has many uses, but the metal’s metallurgical applications, such as an alloying element in iron and steel, account for more than 85 percent of U.S. consumption. The dominant nonmetallurgical use of the metal is as a catalyst for the production of maleic anhydride and sulfuric acid, ceramics, vanadium chemicals and electronics.

Kinetics of DCE and VC mineralization under methanogenic and Fe(III)- reducing conditions

USGS Publications Warehouse

Bradley, P.M.; Chapelle, F.H.

1997-01-01

The kinetics of anaerobic mineralization of DCE and VC under mathanogenic and Fe(III)-reducing conditions as a function of dissolved contaminant concentration were evaluated. Microorganisms indigenous to creek bed sediments, where groundwater contaminated with chlorinated ethenes continuously discharges, demonstrated significant mineralization of DCE and VC under methanogenic and Fe(III)- reducing conditions. Over 37 days, the recovery of [1,214C]VC radioactivity as 14CO2 ranged from 5% to 44% and from 8% to 100% under methanogenic and Fe(III)-reducing conditions, respectively. The recovery of [1,2-14C]DCE radioactivity as 14CO2 ranged from 4% to 14% and did not vary significantly between methanogenic and Fe(III)reducing conditions. VC mineralization was described by Michaelis- Menten kinetics. Under methanogenic conditions, V(max) was 0.19 ?? 0.01 ??mol L-1 d-1 and the half-saturation constant, k(m), was 7.6 ?? 1.7 ??M. Under Fe(III)-reducing conditions, V(max) was 0.76 ?? 0.07 ??mol L-1 d-1 and k(m) was 1.3 ?? 0.5 ??M. In contrast, DCE mineralization could be described by first-order kinetics. The first-order degradation rate constant for DCE mineralization was 0.6 ?? 0.2% d-1 under methanogenic and Fe(III)-reducing conditions. The results indicate that the kinetics of chlorinated ethane mineralization can vary significantly with the specific contaminant and the predominant redox conditions under which mineralization occurs.

A combined theoretical-experimental study of interactions between vanadium ions and Nafion membrane in all-vanadium redox flow batteries

NASA Astrophysics Data System (ADS)

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.

Process for microwave sintering boron carbide

DOEpatents

Holcombe, C.E.; Morrow, M.S.

1993-10-12

A method of microwave sintering boron carbide comprises leaching boron carbide powder with an aqueous solution of nitric acid to form a leached boron carbide powder. The leached boron carbide powder is coated with a glassy carbon precursor to form a coated boron carbide powder. The coated boron carbide powder is consolidated in an enclosure of boron nitride particles coated with a layer of glassy carbon within a container for microwave heating to form an enclosed coated boron carbide powder. The enclosed coated boron carbide powder is sintered within the container for microwave heating with microwave energy.

Process for microwave sintering boron carbide

DOEpatents

Holcombe, Cressie E.; Morrow, Marvin S.

1993-01-01

A method of microwave sintering boron carbide comprises leaching boron carbide powder with an aqueous solution of nitric acid to form a leached boron carbide powder. The leached boron carbide powder is coated with a glassy carbon precursor to form a coated boron carbide powder. The coated boron carbide powder is consolidated in an enclosure of boron nitride particles coated with a layer of glassy carbon within a container for microwave heating to form an enclosed coated boron carbide powder. The enclosed coated boron carbide powder is sintered within the container for microwave heating with microwave energy.

Effective Recovery of Vanadium from Oil Refinery Waste into Vanadium-Based Metal-Organic Frameworks.

PubMed

Zhan, Guowu; Ng, Wei Cheng; Lin, Wenlin Yvonne; Koh, Shin Nuo; Wang, Chi-Hwa

2018-03-06

Carbon black waste, an oil refinery waste, contains a high concentration of vanadium(V) leftover from the processing of crude oil. For the sake of environmental sustainability, it is therefore of interest to recover the vanadium as useful products instead of disposing of it. In this work, V was recovered in the form of vanadium-based metal-organic frameworks (V-MOFs) via a novel pathway by using the leaching solution of carbon black waste instead of commercially available vanadium chemicals. Two different types of V-MOFs with high levels of crystallinity and phase purity were fabricated in very high yields (>98%) based on a coordination modulation method. The V-MOFs exhibited well-defined and controlled shapes such as nanofibers (length: > 10 μm) and nanorods (length: ∼270 nm). Furthermore, the V-MOFs showed high catalytic activities for the oxidation of benzyl alcohol to benzaldehyde, indicating the strong potential of the waste-derived V-MOFs in catalysis applications. Overall, our work offers a green synthesis pathway for the preparation of V-MOFs by using heavy metals of industrial waste as the metal source.

Effect of substrate temperature on thermochromic vanadium dioxide thin films sputtered from vanadium target

NASA Astrophysics Data System (ADS)

Madiba, I. G.; Kotsedi, L.; Ngom, B. D.; Khanyile, B. S.; Maaza, M.

2018-05-01

Vanadium dioxide films have been known as the most promising thermochromic thin films for smart windows which self-control the solar radiation and heat transfer for energy saving, comfort in houses and automotives. Such an attractive technological application is due to the fact that vanadium dioxide crystals exhibit a fast semiconductor-to-metal phase transition at a transition temperature Tc of about 68 °C, together with sharp optical changes from high transmitive to high reflective coatings in the IR spectral region. The phase transition has been associated with the nature of the microstructure, stoichiometry and stresses related to the oxide. This study reports on the effect of the crystallographic quality controlled by the substrate temperature on the thermochromic properties of vanadium dioxide thin films synthesized by reactive radio frequency inverted cylindrical magnetron sputtering from vanadium target. The reports results are based on X-ray diffraction, Atomic force microscopy, and UV-Visible spectrophotometer. The average crystalline grain size of VO2 increases with the substrate temperature, inducing stress related phenomena within the films.

Microbial vanadium (V) reduction in groundwater with different soils from vanadium ore mining areas.

PubMed

Hao, Liting; Zhang, Baogang; Feng, Chuanping; Zhang, Zhenya; Lei, Zhongfang; Shimizu, Kazuya; Cao, Xuelong; Liu, Hui; Liu, Huipeng

2018-07-01

This work investigated the potential of vanadium (V) (V(V)) bioreduction by using soils sampled from four main kinds of vanadium ore mining areas, i.e. vanadium titanomagnetite, stone coal, petroleum associated minerals and uvanite as inocula. During a typical operation cycle of 60 h, the soils from vanadium titanomagnetite area and petroleum associated minerals area exhibited higher V(V) removal efficiencies, about 92.0 ± 2.0% and 91.0 ± 1.9% in comparison to 87.1 ± 1.9% and 69.0 ± 1.1% for the soils from uvanite and stone coal areas, respectively. Results from high-throughput 16 S rRNA gene pyrosequencing analysis reflect the accumulation of Bryobacter and Acidobacteriaceae with capabilities of V(V) reduction, accompanied with other functional species. This study is helpful to search new functional species for V(V) reduction and to develop in situ bioremediations of V(V) polluted groundwater. Copyright © 2018 Elsevier Ltd. All rights reserved.

Method for preparing high purity vanadium

DOEpatents

Schmidt, Frederick; Carlson, O. Norman

1986-09-09

A method for preparing high purity vanadium having a low silicon content has been developed. Vanadium pentoxide is reduced with a stoichiometric, or slightly deficient amount of aluminum to produce a vanadium-aluminum alloy containing an excess of oxygen. Silicon is removed by electron-beam melting the alloy under oxidizing conditions to promote the formation of SiO which is volatile at elevated temperatures. Excess oxygen is removed by heating the alloy in the presence of calcium metal to form calcium oxide.

Method for preparing high purity vanadium

DOEpatents

Schmidt, F.; Carlson, O.N.

1984-05-16

A method for preparing high purity vanadium having a low silicon content has been developed. Vanadium pentoxide is reduced with a stoichiometric, or slightly deficient amount of aluminum to produce a vanadium-aluminum alloy containing an excess of oxygen. Silicon is removed by electron-beam melting the alloy under oxidizing conditions to promote the formation of SiO which is volatile at elevated temperatures. Excess oxygen is removed by heating the alloy in the presence of calcium metal to form calcium oxide.

Vanadium K-edge XAS studies on the native and peroxo-forms of vanadium chloroperoxidase from Curvularia inaequalis.

PubMed

Renirie, Rokus; Charnock, John M; Garner, C David; Wever, Ron

2010-06-01

Vanadium K-edge X-ray Absorption Spectra have been recorded for the native and peroxo-forms of vanadium chloroperoxidase from Curvularia inaequalis at pH 6.0. The Extended X-ray Absorption Fine Structure (EXAFS) regions provide a refinement of previously reported crystallographic data; one short V=O bond (1.54A) is present in both forms. For the native enzyme, the vanadium is coordinated to two other oxygen atoms at 1.69A, another oxygen atom at 1.93A and the nitrogen of an imidazole group at 2.02A. In the peroxo-form, the vanadium is coordinated to two other oxygen atoms at 1.67A, another oxygen atom at 1.88A and the nitrogen of an imidazole group at 1.93A. When combined with the available crystallographic and kinetic data, a likely interpretation of the EXAFS distances is a side-on bound peroxide involving V-O bonds of 1.67 and 1.88A; thus, the latter oxygen would be 'activated' for transfer. The shorter V-N bond observed in the peroxo-form is in line with the previously reported stronger binding of the cofactor in this form of the enzyme. Reduction of the enzyme with dithionite has a clear influence on the spectrum, showing a change from vanadium(V) to vanadium(IV).

Improved toughness of silicon carbide

NASA Technical Reports Server (NTRS)

Palm, J. A.

1975-01-01

Several techniques were employed to apply or otherwise form porous layers of various materials on the surface of hot-pressed silicon carbide ceramic. From mechanical properties measurements and studies, it was concluded that although porous layers could be applied to the silicon carbide ceramic, sufficient damage was done to the silicon carbide surface by the processing required so as to drastically reduce its mechanical strength. It was further concluded that there was little promise of success in forming an effective energy absorbing layer on the surface of already densified silicon carbide ceramic that would have the mechanical strength of the untreated or unsurfaced material. Using a process for the pressureless sintering of silicon carbide powders it was discovered that porous layers of silicon carbide could be formed on a dense, strong silicon carbide substrate in a single consolidation process.

Roasting and leaching behaviors of vanadium and chromium in calcification roasting-acid leaching of high-chromium vanadium slag

NASA Astrophysics Data System (ADS)

Wen, Jing; Jiang, Tao; Zhou, Mi; Gao, Hui-yang; Liu, Jia-yi; Xue, Xiang-xin

2018-05-01

Calcification roasting-acid leaching of high-chromium vanadium slag (HCVS) was conducted to elucidate the roasting and leaching behaviors of vanadium and chromium. The effects of the purity of CaO, molar ratio between CaO and V2O5 ( n(CaO)/ n(V2O5)), roasting temperature, holding time, and the heating rate used in the oxidation-calcification processes were investigated. The roasting process and mechanism were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetry-differential scanning calorimetry (TG-DSC). The results show that most of vanadium reacted with CaO to generate calcium vanadates and transferred into the leaching liquid, whereas almost all of the chromium remained in the leaching residue in the form of (Fe0.6Cr0.4)2O3. Variation trends of the vanadium and chromium leaching ratios were always opposite because of the competitive reactions of oxidation and calcification between vanadium and chromium with CaO. Moreover, CaO was more likely to combine with vanadium, as further confirmed by thermodynamic analysis. When the HCVS with CaO added in an n(CaO)/ n(V2O5) ratio of 0.5 was roasted in an air atmosphere at a heating rate of 10°C/min from room temperature to 950°C and maintained at this temperature for 60 min, the leaching ratios of vanadium and chromium reached 91.14% and 0.49%, respectively; thus, efficient extraction of vanadium from HCVS was achieved and the leaching residue could be used as a new raw material for the extraction of chromium. Furthermore, the oxidation and calcification reactions of the spinel phases occurred at 592 and 630°C for n(CaO)/ n(V2O5) ratios of 0.5 and 5, respectively.

Microwave sintering of boron carbide

DOEpatents

Blake, R.D.; Katz, J.D.; Petrovic, J.J.; Sheinberg, H.

1988-06-10

A method for forming boron carbide into a particular shape and densifying the green boron carbide shape. Boron carbide in powder form is pressed into a green shape and then sintered, using a microwave oven, to obtain a dense boron carbide body. Densities of greater than 95% of theoretical density have been obtained. 1 tab.

Exploring electrolyte preference of vanadium nitride supercapacitor electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Bo; Chen, Zhaohui; Lu, Gang

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 canmore » shed light on other transition metal nitride-based electrochemical energy storage systems.« less

A well-defined terminal vanadium(III) oxo complex.

PubMed

King, Amanda E; Nippe, Michael; Atanasov, Mihail; Chantarojsiri, Teera; Wray, Curtis A; Bill, Eckhard; Neese, Frank; Long, Jeffrey R; Chang, Christopher J

2014-11-03

The ubiquity of vanadium oxo complexes in the V+ and IV+ oxidation states has contributed to a comprehensive understanding of their electronic structure and reactivity. However, despite being predicted to be stable by ligand-field theory, the isolation and characterization of a well-defined terminal mononuclear vanadium(III) oxo complex has remained elusive. We present the synthesis and characterization of a unique terminal mononuclear vanadium(III) oxo species supported by the pentadentate polypyridyl ligand 2,6-bis[1,1-bis(2-pyridyl)ethyl]pyridine (PY5Me2). Exposure of [V(II)(NCCH3)(PY5Me2)](2+) (1) to either dioxygen or selected O-atom-transfer reagents yields [V(IV)(O)(PY5Me2)](2+) (2). The metal-centered one-electron reduction of this vanadium(IV) oxo complex furnishes a stable, diamagnetic [V(III)(O)(PY5Me2)](+) (3) species. The vanadium(III) oxo species is unreactive toward H- and O-atom transfer but readily reacts with protons to form a putative vanadium hydroxo complex. Computational results predict that further one-electron reduction of the vanadium(III) oxo species will result in ligand-based reduction, even though pyridine is generally considered to be a poor π-accepting ligand. These results have implications for future efforts toward low-valent vanadyl chemistry, particularly with regard to the isolation and study of formal vanadium(II) oxo species.

Enrichment, Distribution of Vanadium-Containing Protein in Vanadium-Enriched Sea Cucumber Apostichopus japonicus and the Ameliorative Effect on Insulin Resistance.

PubMed

Liu, Yanjun; Zhou, Qingxin; Zhao, Yanlei; Wang, Yiming; Wang, Yuming; Wang, Jingfeng; Xu, Jie; Xue, Changhu

2016-05-01

Sea cucumbers are a potential source of natural organic vanadium that may improve insulin resistance. In this work, vanadium was accumulated rapidly in blood, body wall, and intestine by sea cucumber Apostichopus japonicus. Furthermore, water-soluble vanadium-containing proteins, the main form of the organic vanadium, were tentatively accumulated and isolated by a bioaccumulation experiment. It was also designed to evaluate the beneficial effect of vanadium-containing proteins (VCPs) from sea cucumber rich in vanadium on the development of hyperglycemia and insulin resistance in C57BL/6J mice fed with a high-fat high-sucrose diet (HFSD). HFSD mice treated with VCPs significantly decreased fasting blood glucose, serum insulin, and HOMA-IR values as compared to HFSD mice, respectively. Serum adiponectin, resistin, TNF-α, and leptin levels in insulin-resistant mice were dramatically reduced by a VCP supplement. These results show an ameliorative effect on insulin resistance by treatment with VCPs. Such compound seems to be a valuable therapy to achieve and/or maintain glycemic control and therapeutic agents in the treatment arsenal for insulin resistance and type 2 diabetes.

Assessment of Dephosphorization During Vanadium Extraction Process in Converter

NASA Astrophysics Data System (ADS)

Chen, Lian; Diao, Jiang; Wang, Guang; Xie, Bing

2018-06-01

Dephosphorization during the vanadium extraction process in the converter was studied. The effects of the slag basicity and FeO content on the dephosphorization and the mineral phases in the phosphorus-containing vanadium slag are discussed. The results show that removal of phosphorus from the hot metal during the vanadium extraction process can be achieved by adding lime into the vanadium extraction converter. The highest dephosphorization rate was obtained at slag basicity of 1.93. The phosphorus distribution ratio increased with increasing FeO content up to 16-18% but decreased thereafter. Vanadium was present in the slag only as spinels rather than calcium vanadate. Phosphorus was still present in the form of calcium phosphate eutectic in calcium silicate. The present work proves that the vanadium extraction and dephosphorization processes are nonconflicting reactions.

Vanadium hydride deuterium-tritium generator

DOEpatents

Christensen, Leslie D.

1982-01-01

A pressure controlled vanadium hydride gas generator to provide deuterium-tritium gas in a series of pressure increments. A high pressure chamber filled with vanadium-deuterium-tritium hydride is surrounded by a heater which controls the hydride temperature. The heater is actuated by a power controller which responds to the difference signal between the actual pressure signal and a programmed pressure signal.

Photocatalytic Activity of Vanadium-Substituted ETS-10

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nash,M.; Rykov, S.; Lobo, R.

2007-01-01

Various amounts of vanadium have been isomorphously substituted for titanium in ETS-10, creating samples with V/(V+Ti) ratios of 0.13, 0.33, 0.43, and 1.00 and characterized experimentally using Raman, near-edge X-ray absorption fine structure (NEXAFS), X-ray powder diffraction, N{sub 2} adsorption, scanning electron microscopy (SEM), UV/vis spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Raman spectra reveal a disordered chain structure that contains different V-O bonds along with the presence of a V-O-Ti peak. The UV/vis spectra of the vanadium samples have three new absorption features in the visible region at 450, 594, and 850 nm, suggesting both V{sup 4+}more » and V{sup 5+} are present in the samples. NEXAFS results confirm the presence of both V{sup 5+} and V{sup 4+} in the vanadium samples, with a fraction of V{sup 4+} within the range of 0.2-0.4. The addition of vanadium lowers the band gap energy of ETS-10 from 4.32 eV to a minimum of 3.58 eV for the 0.43ETVS-10 sample. Studies of the photocatalytic polymerization of ethylene show that the 594 nm transition has no photocatalytic activity. The visible transition around 450 nm in the vanadium-incorporated samples is photocatalytically active, and the lower-concentration vanadium samples have higher photocatalytic activity than that of ETS-10 and AM-6, the all-vanadium analogue of ETS-10.« less

VANADIUM CHEMISTRY ESSENTIALS FOR TREATMENT STUDIES

EPA Science Inventory

The importance of vanadium occurrence and treatment in drinking water has been elevated by its inclusion in the Contaminant Candidate List. Though it is still too early to know the nature of new regulatory requirements for vanadium, if indeed it becomes regulated, a substantial u...

Porous silicon carbide (SIC) semiconductor device

NASA Technical Reports Server (NTRS)

Shor, Joseph S. (Inventor); Kurtz, Anthony D. (Inventor)

1996-01-01

Porous silicon carbide is fabricated according to techniques which result in a significant portion of nanocrystallites within the material in a sub 10 nanometer regime. There is described techniques for passivating porous silicon carbide which result in the fabrication of optoelectronic devices which exhibit brighter blue luminescence and exhibit improved qualities. Based on certain of the techniques described porous silicon carbide is used as a sacrificial layer for the patterning of silicon carbide. Porous silicon carbide is then removed from the bulk substrate by oxidation and other methods. The techniques described employ a two-step process which is used to pattern bulk silicon carbide where selected areas of the wafer are then made porous and then the porous layer is subsequently removed. The process to form porous silicon carbide exhibits dopant selectivity and a two-step etching procedure is implemented for silicon carbide multilayers.

Differential Cav2.1 and Cav2.3 channel inhibition by baclofen and α-conotoxin Vc1.1 via GABAB receptor activation

PubMed Central

McArthur, Jeffrey R.; Cuny, Hartmut; Clark, Richard J.; Adams, David J.

2014-01-01

Neuronal Cav2.1 (P/Q-type), Cav2.2 (N-type), and Cav2.3 (R-type) calcium channels contribute to synaptic transmission and are modulated through G protein–coupled receptor pathways. The analgesic α-conotoxin Vc1.1 acts through γ-aminobutyric acid type B (GABAB) receptors (GABABRs) to inhibit Cav2.2 channels. We investigated GABABR-mediated modulation by Vc1.1, a cyclized form of Vc1.1 (c-Vc1.1), and the GABABR agonist baclofen of human Cav2.1 or Cav2.3 channels heterologously expressed in human embryonic kidney cells. 50 µM baclofen inhibited Cav2.1 and Cav2.3 channel Ba2+ currents by ∼40%, whereas c-Vc1.1 did not affect Cav2.1 but potently inhibited Cav2.3, with a half-maximal inhibitory concentration of ∼300 pM. Depolarizing paired pulses revealed that ∼75% of the baclofen inhibition of Cav2.1 was voltage dependent and could be relieved by strong depolarization. In contrast, baclofen or Vc1.1 inhibition of Cav2.3 channels was solely mediated through voltage-independent pathways that could be disrupted by pertussis toxin, guanosine 5′-[β-thio]diphosphate trilithium salt, or the GABABR antagonist CGP55845. Overexpression of the kinase c-Src significantly increased inhibition of Cav2.3 by c-Vc1.1. Conversely, coexpression of a catalytically inactive double mutant form of c-Src or pretreatment with a phosphorylated pp60c-Src peptide abolished the effect of c-Vc1.1. Site-directed mutational analyses of Cav2.3 demonstrated that tyrosines 1761 and 1765 within exon 37 are critical for inhibition of Cav2.3 by c-Vc1.1 and are involved in baclofen inhibition of these channels. Remarkably, point mutations introducing specific c-Src phosphorylation sites into human Cav2.1 channels conferred c-Vc1.1 sensitivity. Our findings show that Vc1.1 inhibition of Cav2.3, which defines Cav2.3 channels as potential targets for analgesic α-conotoxins, is caused by specific c-Src phosphorylation sites in the C terminus. PMID:24688019

Reference binding energies of transition metal carbides by core-level x-ray photoelectron spectroscopy free from Ar+ etching artefacts

NASA Astrophysics Data System (ADS)

Greczynski, G.; Primetzhofer, D.; Hultman, L.

2018-04-01

We report x-ray photoelectron spectroscopy (XPS) core level binding energies (BE's) for the widely-applicable groups IVb-VIb transition metal carbides (TMCs) TiC, VC, CrC, ZrC, NbC, MoC, HfC, TaC, and WC. Thin film samples are grown in the same deposition system, by dc magnetron co-sputtering from graphite and respective elemental metal targets in Ar atmosphere. To remove surface contaminations resulting from exposure to air during sample transfer from the growth chamber into the XPS system, layers are either (i) Ar+ ion-etched or (ii) UHV-annealed in situ prior to XPS analyses. High resolution XPS spectra reveal that even gentle etching affects the shape of core level signals, as well as BE values, which are systematically offset by 0.2-0.5 eV towards lower BE. These destructive effects of Ar+ ion etch become more pronounced with increasing the metal atom mass due to an increasing carbon-to-metal sputter yield ratio. Systematic analysis reveals that for each row in the periodic table (3d, 4d, and 5d) C 1s BE increases from left to right indicative of a decreased charge transfer from TM to C atoms, hence bond weakening. Moreover, C 1s BE decreases linearly with increasing carbide/metal melting point ratio. Spectra reported here, acquired from a consistent set of samples in the same instrument, should serve as a reference for true deconvolution of complex XPS cases, including multinary carbides, nitrides, and carbonitrides.

Selected fretting-wear-resistant coatings for titanium - 6-percent-aluminum - 4-percent-vanadium alloy

NASA Technical Reports Server (NTRS)

Bill, R. C.

1976-01-01

A titanium - 6-percent-aluminum - 4-percent-vanadium alloy (Ti-6Al-4V) was subjected to fretting-wear exposures against uncoated Ti-6Al-4V as a baseline and against various coatings and surface treatments applied to Ti-6Al-4V. The coatings evaluated included plasma-sprayed tungsten carbide with 12 percent cobalt, aluminum oxide with 13 percent titanium oxide, chromium oxide, and aluminum bronze with 10 percent aromatic polyester; polymer-bonded polyimide, polyimide with graphite fluoride, polyimide with molybdenum disulfide (MoS2), and methyl phenyl silicone bonded MoS2, preoxidation surface treatment, a nitride surface treatment, and a sputtered MoS2 coating. Results of wear measurements on both the coated and uncoated surfaces after 300,000 fretting cycles indicated that the polyimide coating was the most wear resistant and caused the least wear to the uncoated mating surface.

Aqueous vanadium ion dynamics relevant to bioinorganic chemistry: A review.

PubMed

Kustin, Kenneth

2015-06-01

Aqueous solutions of the four highest vanadium oxidation states exhibit four diverse colors, which only hint at the diverse reactions that these ions can undergo. Cationic vanadium ions form complexes with ligands; anionic vanadium ions form complexes with ligands and self-react to form isopolyanions. All vanadium species undergo oxidation-reduction reactions. With a few exceptions, elucidation of the dynamics of these reactions awaited the development of fast reaction techniques before the kinetics of elementary ligation, condensation, reduction, and oxidation of the aqueous vanadium ions could be investigated. As the biological roles played by endogenous and therapeutic vanadium expand, it is appropriate to bring the results of the diverse kinetics studies under one umbrella. To achieve this goal this review presents a systematic examination of elementary aqueous vanadium ion dynamics. Copyright © 2014 Elsevier Inc. All rights reserved.

Vanadium hydride deuterium-tritium generator

DOEpatents

Christensen, L.D.

1980-03-13

A pressure controlled vanadium hydride gas generator was designed to provide deuterium-tritium gas in a series of pressure increments. A high pressure chamber filled with vanadium-deuterium-tritium hydride is surrounded by a heater which controls the hydride temperature. The heater is actuated by a power controller which responds to the difference signal between the actual pressure signal and a programmed pressure signal.

Structural and silver/vanadium ratio effects on silver vanadium phosphorous oxide solution formation kinetics: impact on battery electrochemistry.

PubMed

Bock, David C; Takeuchi, Kenneth J; Marschilok, Amy C; Takeuchi, Esther S

2015-01-21

The detailed understanding of non-faradaic parasitic reactions which diminish battery calendar life is essential to the development of effective batteries for use in long life applications. The dissolution of cathode materials including manganese, cobalt and vanadium oxides in battery systems has been identified as a battery failure mechanism, yet detailed dissolution studies including kinetic analysis are absent from the literature. The results presented here provide a framework for the quantitative and kinetic analyses of the dissolution of cathode materials which will aid the broader community in more fully understanding this battery failure mechanism. In this study, the dissolution of silver vanadium oxide, representing the primary battery powering implantable cardioverter defibrillators (ICD), is compared with the dissolution of silver vanadium phosphorous oxide (Ag(w)VxPyOz) materials which were targeted as alternatives to minimize solubility. This study contains the first kinetic analyses of silver and vanadium solution formation from Ag0.48VOPO4·1.9H2O and Ag2VP2O8, in a non-aqueous battery electrolyte. The kinetic results are compared with those of Ag2VO2PO4 and Ag2V4O11 to probe the relationships among crystal structure, stoichiometry, and solubility. For vanadium, significant dissolution was observed for Ag2V4O11 as well as for the phosphate oxide Ag0.49VOPO4·1.9H2O, which may involve structural water or the existence of multiple vanadium oxidation states. Notably, the materials from the SVPO family with the lowest vanadium solubility are Ag2VO2PO4 and Ag2VP2O8. The low concentrations and solution rates coupled with their electrochemical performance make these materials interesting alternatives to Ag2V4O11 for the ICD application.

Vanadium-pumped titanium x-ray laser

DOEpatents

Nilsen, J.

1992-05-26

A resonantly photo-pumped x-ray laser is formed of a vanadium and titanium foil combination that is driven by two beams of intense line focused optical laser radiation. Ground state neon-like titanium ions are resonantly photo-pumped by line emission from fluorine-like vanadium ions. 4 figs.

Mineralogy and geochemistry of vanadium in the Colorado Plateau

USGS Publications Warehouse

Weeks, A.D.

1961-01-01

The chief domestic source of vanadium is uraniferous sandstone in the Colorado Plateau. Vanadium is 3-, 4-, or 5-valent in nature and, as oxides or combined with other elements, it forms more than 40 minerals in the Plateau ores. These ores have been studied with regard to the relative amounts of vanadium silicates and oxide-vanadates, uranium-vanadium ratios, the progressive oxidation of black low-valent ores to high-valent carnotite-type ores, and theories of origin. ?? 1961.

Vanadium bioavailability and toxicity to soil microorganisms and plants.

PubMed

Larsson, Maja A; Baken, Stijn; Gustafsson, Jon Petter; Hadialhejazi, Golshid; Smolders, Erik

2013-10-01

Vanadium, V, is a redox-sensitive metal that in solution, under aerobic conditions, prevails as the oxyanion vanadate(V). There is little known regarding vanadium toxicity to soil biota, and the present study was set up to determine the toxicity of added vanadate to soil organisms and to investigate the relationship between toxicity and vanadium sorption in soils. Five soils with contrasting properties were spiked with 7 different doses (3.2-3200 mg V kg(-1)) of dissolved vanadate, and toxicity was measured with 2 microbial and 3 plant assays. The median effective concentration (EC50) thresholds of the microbial assays ranged from 28 mg added V kg(-1) to 690 mg added V kg(-1), and the EC50s in the plant assays ranged from 18 mg added V kg(-1) to 510 mg added V kg(-1). The lower thresholds were in the concentration range of the background vanadium in the untreated control soils (15-58 mg V kg(-1)). The vanadium toxicity to plants decreased with a stronger soil vanadium sorption strength. The EC50 values for plants expressed on a soil solution basis ranged from 0.8 mg V L(-1) to 15 mg V L(-1) and were less variable among soils than corresponding values based on total vanadium in soil. It is concluded that sorption decreases the toxicity of added vanadate and that soil solution vanadium is a more robust measure to determine critical vanadium concentrations across soils. © 2013 SETAC.

Long coherence times in nuclear spin-free vanadyl qubits [Long coherence times in surface-compatible nuclear spin-free vanadium qubits

DOE PAGES

Yu, Chung -Jui; Graham, Michael J.; Zadrozny, Joseph M.; ...

2016-10-31

Quantum information processing (QIP) offers the potential to create new frontiers in fields ranging from quantum biology to cryptography. Two key figures of merit for electronic spin qubits, the smallest units of QIP, are the coherence time ( T2), the lifetime of the qubit, and the spin–lattice relaxation time ( T1), the thermally defined upper limit of T2. To achieve QIP, processable qubits with long coherence times are required. Recent studies on (Ph4P-d20)2[V(C8S8)3], a vanadium-based qubit, demonstrate that millisecond T2 times are achievable in transition metal complexes with nuclear spinfree environments. Applying these principles to vanadyl complexes offers a routemore » to combine the previously established surface compatibility of the flatter vanadyl structures with a long T2. Toward those ends, we investigated a series of four qubits, (Ph 4P) 2[VO(C 8S 8) 2] (1), (Ph 4P) 2[VO(β-C 3S 5) 2] (2), (Ph 4P) 2[VO(α-C 3S 5) 2] (3), and (Ph 4P) 2[VO(C 3S 4O) 2] (4), by pulsed electron paramagnetic resonance (EPR) spectroscopy and compared the performance of these species with our recently reported set of vanadium tris(dithiolene) complexes. Crucially we demonstrate that solutions of 1–4 in SO 2, a uniquely polar nuclear spinfree solvent, reveal T2 values of up to 152(6) μs, comparable to the best molecular qubit candidates. Upon transitioning to vanadyl species from the tris(dithiolene) analogues, we observe a remarkable order of magnitude increase in 12, attributed to stronger solute–solvent interactions with the polar vanadium-oxo moiety. Simultaneously, we detect a small decrease in T2 for the vanadyl analogues relative to the tris(dithiolene) complexes. We attribute this decrease to the absence of one nuclear spinfree ligand, which served to shield the vanadium centers against solvent nuclear spins. Lastly, our results highlight new design principles for long T1 and T2 times by demonstrating the efficacy of ligand-based tuning of solute�

Effect of vanadium compounds on acid phosphatase activity.

PubMed

Vescina, C M; Sálice, V C; Cortizo, A M; Etcheverry, S B

1996-01-01

The direct effect of different vanadium compounds on acid phosphatase (ACP) activity was investigated. Vanadate and vanadyl but not pervanadate inhibited the wheat germ ACP activity. These vanadium derivatives did not alter the fibroblast Swiss 3T3 soluble fraction ACP activity. Using inhibitors of tyrosine phosphatases (PTPases), the wheat germ ACP was partially characterized as a PTPase. This study suggests that the inhibitory ability of different vanadium derivatives to modulate ACP activity seems to depend on the geometry around the vanadium atom more than on the oxidation state. Our results indicate a correlation between the PTPase activity and the sensitivity to vanadate and vanadyl cation.

77 FR 51825 - Ferrovanadium and Nitrided Vanadium From Russia

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-27

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

Chloride supporting electrolytes for all-vanadium redox flow batteries.

PubMed

Kim, Soowhan; Vijayakumar, M; Wang, Wei; Zhang, Jianlu; Chen, Baowei; Nie, Zimin; Chen, Feng; Hu, Jianzhi; Li, Liyu; Yang, Zhenguo

2011-10-28

This paper examines vanadium chloride solutions as electrolytes for an all-vanadium redox flow battery. The chloride solutions were capable of dissolving more than 2.3 M vanadium at varied valence states and remained stable at 0-50 °C. The improved stability appeared due to the formation of a vanadium dinuclear [V(2)O(3)·4H(2)O](4+) or a dinuclear-chloro complex [V(2)O(3)Cl·3H(2)O](3+) in the solutions over a wide temperature range. The all-vanadium redox flow batteries with the chloride electrolytes demonstrated excellent reversibility and fairly high efficiencies. Only negligible, if any, gas evolution was observed. The improved energy capacity and good performance, along with the ease in heat management, would lead to substantial reduction in capital cost and life-cycle cost, making the vanadium chloride redox flow battery a promising candidate for stationary applications. This journal is © the Owner Societies 2011

Recycling of Ammonia Wastewater During Vanadium Extraction from Shale

NASA Astrophysics Data System (ADS)

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

2018-03-01

In the vanadium metallurgical industry, massive amounts of ammonia hydroxide or ammonia salt are added during the precipitation process to obtain V2O5; therefore, wastewater containing a high level of NH4 + is generated, which poses a serious threat to environmental and hydrologic safety. In this article, a novel process was developed to recycle ammonia wastewater based on a combination of ammonia wastewater leaching and crystallization during vanadium extraction from shale. The effects of the NH4 + concentration, temperature, time and liquid-to-solid ratio on the leaching efficiencies of vanadium, aluminum and potassium were investigated, and the results showed that 93.2% of vanadium, 86.3% of aluminum and 96.8% of potassium can be leached from sulfation-roasted shale. Subsequently, 80.6% of NH4 + was separated from the leaching solution via cooling crystallization. Vanadium was recovered via a combined method of solvent extraction, precipitation and calcination. Therefore, ammonia wastewater was successfully recycled during vanadium extraction from shale.

Vanadium pentoxide

Integrated Risk Information System (IRIS)

Vanadium pentoxide ; CASRN 1314 - 62 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogen

Adsorption and diffusion of Au atoms on the (001) surface of Ti, Zr, Hf, V, Nb, Ta, and Mo carbides.

PubMed

Florez, Elizabeth; Viñes, Francesc; Rodriguez, Jose A; Illas, Francesc

2009-06-28

The adsorption of atomic Au on the (001) surface of TiC, ZrC, HfC, VC, NbC, TaC, and delta-MoC and the mechanism of diffusion of this adatom through the surface have been studied in terms of a periodic density functional theory based approach. In all the cases, the Au adsorption energies are in the range of 1.90-2.35 eV. The moderately large adsorption energies allow the Au diffusion before desorption could take place. For TiC(001), ZrC(001), and HfC(001), atomic Au is adsorbed directly on top of C atoms and diffusion takes place along the diagonal of the squares formed by M-C-M-C atoms with the transition state located above the hollow sites. For the rest of transition metal carbides the situation is less simple with the appearance of more than one stable adsorption site, as for NbC and TaC, of a small energy barrier for diffusion around the most stable adsorption site and of a more complex diffusion pathway. The small energy barrier for diffusion around the most stable site will result in a highly mobile Au species which could be observed in scanning tunnel microscope experiments. After depositing Au on metal-carbide surfaces, there is a noticeable charge transfer from the substrate to the adsorbed Au atom. The electronic perturbations on Au increase when going from TiC to ZrC or TaC. Our results indicate that metal carbides should be better supports for the chemical activation of Au than metal oxides.

Boron-carbide-aluminum and boron-carbide-reactive metal cermets

DOEpatents

Halverson, Danny C.; Pyzik, Aleksander J.; Aksay, Ilhan A.

1986-01-01

Hard, tough, lightweight boron-carbide-reactive metal composites, particularly boron-carbide-aluminum composites, are produced. These composites have compositions with a plurality of phases. A method is provided, including the steps of wetting and reacting the starting materials, by which the microstructures in the resulting composites can be controllably selected. Starting compositions, reaction temperatures, reaction times, and reaction atmospheres are parameters for controlling the process and resulting compositions. The ceramic phases are homogeneously distributed in the metal phases and adhesive forces at ceramic-metal interfaces are maximized. An initial consolidation step is used to achieve fully dense composites. Microstructures of boron-carbide-aluminum cermets have been produced with modulus of rupture exceeding 110 ksi and fracture toughness exceeding 12 ksi.sqroot.in. These composites and methods can be used to form a variety of structural elements.

Anion-conductive membranes with ultralow vanadium permeability and excellent performance in vanadium flow batteries.

PubMed

Mai, Zhensheng; Zhang, Huamin; Zhang, Hongzhang; Xu, Wanxing; Wei, Wenping; Na, Hui; Li, Xianfeng

2013-02-01

Anion exchange membranes prepared from quaternized poly(tetramethyl diphenyl ether sulfone) (QAPES) were first investigated in the context of vanadium flow battery (VFB) applications. The membranes showed an impressive suppression effect on vanadium ions. The recorded vanadium permeability was 0.02×10(-7)-0.09×10(-7) cm(2) min(-1), which was two orders of magnitude lower than that of Nafion 115. The self-discharge duration of a VFB single cell with a QAPES membrane is four times longer than that of Nafion 115. The morphological difference in hydrophilic domains between QAPES and Nafion was confirmed by TEM. After soaking the membranes in VO(2)(+) solution, adsorbed vanadium ions can barely be found in QAPES, whereas the hydrophilic domains of Nafion were stained. In the ex situ chemical stability test, QAPES showed a high tolerance to VO(2)(+) and remained intact after immersion in VO(2)(+) solution for over 250 h. The performance of a VFB single cell assembled with QAPES membranes is equal to or even better than that of Nafion 115 and remains stable in a long-term cycle test. These results indicate that QAPES membranes can be an ideal option in the fabrication of high-performance VFBs with low electric capacity loss. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparative erythropoietic effects of three vanadium compounds.

PubMed

Hogan, G R

2000-07-10

The biotoxic effects of vanadium are variable depending upon a number of factors including the oxidation state of the test compound. This study reports the effects of three vanadium compounds on peripheral erythrocytes. On day 0 female ICR mice received a single injection of vanadium chloride (V-III), vanadyl sulfate (V-IV), or sodium orthovandate (V-V). At scheduled intervals post-injection, the number of circulating erythrocytes [red blood cells per millimeter cubed (RBC/mm3)], reticulocyte percentages, and radioiron uptake percentages were determined and compared to mice receiving saline only. Data show that all three test substances promoted a significant lowering of RBC/mm3 beginning on day 1 for V-IV and V-V and on day 2 for V-III through day 4. The reticulocyte percentages increase followed the same time course as that of the peripheral RBC decrease. Peak reticulocytosis was noted on days 2 and 4 for all three vanadium-treated groups; for V-IV and V-V the increase continued to day 6. Radioiron data showed an erythropoietic stimulation by a significant increase in uptake percentages on days 4-6 after vanadium injections compared to saline-treated controls.

Vanadium exposure-induced striatal learning and memory alterations in rats.

PubMed

Sun, Liping; Wang, Keyue; Li, Yan; Fan, Qiyuan; Zheng, Wei; Li, Hong

2017-09-01

Occupational and environmental exposure to vanadium has been associated with toxicities in reproductive, respiratory, and cardiovascular systems. The knowledge on whether and how vanadium exposure caused neurobehavioral changes remains incomplete. This study was designed to investigate the changes in learning and memory following drinking water exposure to vanadium, and to conduct the preliminary study on underlying mechanisms. Male Sprague-Dawley rats were exposed to vanadium dissolved in drinking water at the concentration of 0.0, 0.5, 1.0 and 2.0g/L, as the control, low-, medium-, and high- dose groups, respectively, for 12 weeks. The results by the Morris water maze test showed that the time for the testing animal to find the platform in the high exposed group was increased by 82.9% and 49.7%, as compared to animals in control and low-dose groups (p<0.05). There were significantly fewer rats in the medium- and high- dose groups than in the control group who were capable of crossing the platform (p<0.05). Quantitation of vanadium by atomic absorption spectrophotometry revealed a significant dose-dependent accumulation of vanadium in striatum (r=0.931, p<0.01). Histopathological examination further demonstrated a degenerative damage in vanadium-exposed striatum. Interestingly, with the increase of the dose of vanadium, the contents of neurotransmitter ACh, 5-HT and GABA in the striatum increased; however, the levels of Syn1 was significantly reduced in the exposed groups compared with controls (p<0.05). These data suggest that vanadium exposure apparently reduces the animals' learning ability. This could be due partly to vanadium's accumulation in striatum and the ensuing toxicity to striatal structure and synaptic plasticity. Further research is warranted for mechanistic understanding of vanadium-induced neurotoxicity. Copyright © 2017 Elsevier B.V. All rights reserved.

Geochemical controls on vanadium accumulation in fossil fuels

USGS Publications Warehouse

Breit, G.N.; Wanty, R.B.

1989-01-01

High vanadium contents in petroleum and other fossil fuels have been attributed to organic-matter type, organisms, volcanic emanations, diffusion of sea water, and epigenetic enrichment. However, these factors are inadequate to account for the high abundance of vanadium in some fossil fuels and the paucity in others. By examining vanadium deposits in sedimentary rocks with sparse organic matter, constraints are placed on processes controlling vanadium accumulation in organic-rich sediments. Vanadium, as vanadate (V(V)), entered some depositional basins in oxidizing waters from dry, subaerial environments. Upon contact with organic matter in anoxic waters, V(V) is reduced to vanadyl (V(IV)), which can be removed from the water column by adsorption. H2S reduces V(IV) to V(III), which hydrolyzes and precipitates. The lack of V(III) in petroleum suggests that reduction of V(IV) to V(III) is inhibited by organic complexes. In the absence of strong complexing agents, V(III) forms and is incorporated in clay minerals.

Geochemical controls of vanadium accumulation in fossil fuels

USGS Publications Warehouse

Breit, G.N.; Wanty, R.B.

1989-01-01

High vanadium contents in petroleum and other fossil fuels have been attributed to organic-matter type, organisms, volcanic emanations, diffusion of sea water, and epigenetic enrichment. However, these factors are inadequate to account for the high abundance of vanadium in some fossil fuels and the paucity in others. By examining vanadium deposits in sedimentary rocks with sparse organic matter, constraints are placed on processes controlling vanadium accumulation in organic-rich sediments. Vanadium, as vanadate (V(V)), entered some depositional basins in oxidizing waters from dry, subaerial environments. Upon contact with organic matter in anoxic waters, V(V) is reduced to vanadyl (V(IV)), which can be removed from the water column by adsorption. H2S reduces V(IV) to V(III), which hydrolyzes and precipitates. The lack of V(III) in petroleum suggests that reduction of V(IV) to V(III) is inhibited by organic complexes. In the absence of strong complexing agents, V(III) forms and is incorporated in clay minerals.

Exploring Online Learning at Primary Schools: Students' Perspectives on Cyber Home Learning System through Video Conferencing (CHLS-VC)

ERIC Educational Resources Information Center

Lee, June; Yoon, Seo Young; Lee, Chung Hyun

2013-01-01

The purposes of the study are to investigate CHLS (Cyber Home Learning System) in online video conferencing environment in primary school level and to explore the students' responses on CHLS-VC (Cyber Home Learning System through Video Conferencing) in order to explore the possibility of using CHLS-VC as a supportive online learning system. The…

IRIS Toxicological Review of Vanadium Pentoxide ...

EPA Pesticide Factsheets

On September 30, 2011, the draft Toxicological Review of Vanadium Pentoxide and the charge to external peer reviewers were released for external peer review and public comment. The Toxicological Review and charge were reviewed internally by EPA and by other federal agencies and White House Offices before public release. In the new IRIS process (May 2009), introduced by the EPA Administrator, all written comments on IRIS assessments submitted by other federal agencies and White House Offices will be made publicly available. Accordingly, interagency comments and the interagency science consultation draft of the IRIS Toxicological Review of Vanadium Pentoxide and the charge to external peer reviewers are posted on this site. EPA is reassessing its IRIS toxicological review of vanadium pentoxide (CASRN 1314-62-1). This vanadium pentoxide reassessment consists of an oral reference dose (RfD), an inhalation reference concentration (RfC), an inhalation unit risk (IUR) and a cancer weight of evidence descriptor. This is the first assessment developing an RfC or IUR for this compound. This assessment is intended to provide human health data to support agency regulatory decisions.

Enhanced electrocatalytic activity and stability of Pd 3V/C nanoparticles with a trace amount of Pt decoration for the oxygen reduction reaction

DOE PAGES

Liu, Sufen; Han, Lili; Zhu, Jing; ...

2015-09-14

In this study, carbon supported Pd 3V bimetallic alloy nanoparticles (Pd 3V/C) have been successfully synthesized via a simple impregnation–reduction method, followed by high temperature treatment under a H 2 atmosphere. Electrochemical tests reveal that the half-wave potential of Pd 3V/C-500 shifts positively 40 mV compared with Pd/C. However, the catalytic activity of Pd 3V/C-500 suffers from serious degradation after 1k cycles. By a spontaneous displacement reaction or co-reduction method, a trace amount of Pt was decorated on the surface or inside of the Pd 3V/C nanoparticles. The catalytic activity and stability of the Pd 3V@Pt/C and Pt-Pd 3V/C catalystsmore » for the oxygen reduction reaction (ORR) are enhanced significantly, and are comparable to commercial Pt/C. In addition, the Pt mass activity of Pd 3V@Pt/C and Pt-Pd 3V/C improves by factors of 10.9 and 6.5 at 0.80 V relative to Pt/C. Moreover, Pt-decorated Pd 3V/C nanoparticles show almost no obvious morphology change after durability tests, because the Pt-rich shell plays an important role in preventing degradation.« less

Plasma enhanced chemical vapor deposition (PECVD) method of forming vanadium oxide films and vanadium oxide thin-films prepared thereby

DOEpatents

Zhang, Ji-Guang; Tracy, C. Edwin; Benson, David K.; Turner, John A.; Liu, Ping

2000-01-01

A method is disclosed of forming a vanadium oxide film on a substrate utilizing plasma enhanced chemical vapor deposition. The method includes positioning a substrate within a plasma reaction chamber and then forming a precursor gas comprised of a vanadium-containing chloride gas in an inert carrier gas. This precursor gas is then mixed with selected amounts of hydrogen and oxygen and directed into the reaction chamber. The amounts of precursor gas, oxygen and hydrogen are selected to optimize the final properties of the vanadium oxide film An rf plasma is generated within the reaction chamber to chemically react the precursor gas with the hydrogen and the oxygen to cause deposition of a vanadium oxide film on the substrate while the chamber deposition pressure is maintained at about one torr or less. Finally, the byproduct gases are removed from the plasma reaction chamber.

The Vaccinium corymbosum FLOWERING LOCUS T-like gene (VcFT): a flowering activator reverses photoperiodic and chilling requirements in blueberry.

PubMed

Song, Guo-qing; Walworth, Aaron; Zhao, Dongyan; Jiang, Ning; Hancock, James F

2013-11-01

The blueberry FLOWERING LOCUS T ( FT )-like gene ( VcFT ) cloned from the cDNA of a tetraploid, northern highbush blueberry ( Vaccinium corymbosum L.) is able to reverse the photoperiodic and chilling requirements and drive early and continuous flowering. Blueberry is a woody perennial bush with a longer juvenile period than annual crops, requiring vernalization to flower normally. Few studies have been reported on the molecular mechanism of flowering in blueberry or other woody plants. Because FLOWERING LOCUS T (FT) from Arabidopsis thaliana plays a multifaceted role in generating mobile molecular signals to regulate plant flowering time, isolation and functional analysis of the blueberry (Vaccinium corymbosum L.) FT-like gene (VcFT) will facilitate the elucidation of molecular mechanisms of flowering in woody plants. Based on EST sequences, a 525-bpVcFT was identified and cloned from the cDNA of a tetraploid, northern highbush blueberry cultivar, Bluecrop. Ectopic expression of 35S:VcFT in tobacco induced flowering an average of 28 days earlier than wild-type plants. Expression of the 35S:VcFT in the blueberry cultivar Aurora resulted in an extremely early flowering phenotype, which flowered not only during in vitro culture, a growth stage when nontransgenic shoots had not yet flowered, but also in 6-10-week old, soil-grown transgenic plants, in contrast to the fact that at least 1 year and 800 chilling hours are required for the appearance of the first flower of both nontransgenic 'Aurora' and transgenic controls with the gusA. These results demonstrate that the VcFT is a functional floral activator and overexpression of the VcFT is able to reverse the photoperiodic and chilling requirements and drive early and continuous flowering.

Vanadium-pumped titanium x-ray laser

DOEpatents

Nilsen, Joseph

1992-01-01

A resonantly photo-pumped x-ray laser (10) is formed of a vanadium (12) and titanium (14) foil combination (16) that is driven by two beams (18, 20) of intense line focused (22, 24) optical laser radiation. Ground state neon-like titanium ions (34) are resonantly photo-pumped by line emission from fluorine-like vanadium ions (32).

Kinetic model of whole-body vanadium metabolism: studies in sheep

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patterson, B.W.; Hansard, S.L. II; Ammerman, C.B.

1986-08-01

A compartmental model for vanadium metabolism in sheep has been proposed. The model is consistent with data obtained from sheep fed a control diet (2.6 ppm vanadium) containing 0 or 200 ppm supplemental vanadium. Sheep were administered UYV dioxovanadium either orally or intravenously. Blood feces, and urine radioactivity were monitored for 6 days postdosing. Several new insights regarding vanadium metabolism are suggested and tested against the data using the model. Some of these include 1) significant absorption of UYV occurs from the upper gastrointestinal tract; 2) an in vivo process is necessary in order for UYV dioxovanadium to be convertedmore » into a more biologically reactive species; 3) at steady state the upper and lower gastrointestinal tracts contain at least 10- and 100-fold more mass of vanadium, respectively, than does blood. No statistically significant differences in transport rate constants were found between animals receiving 0 and 200 ppm supplemental dietary vanadium. The availability of a model will enable the refinement of future studies regarding vanadium metabolism in the ruminant.« less

Anisotropic Tribological Properties of Silicon Carbide

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Buckley, D. H.

1980-01-01

The anisotropic friction, deformation and fracture behavior of single crystal silicon carbide surfaces were investigated in two categories. The categories were called adhesive and abrasive wear processes, respectively. In the adhesive wear process, the adhesion, friction and wear of silicon carbide were markedly dependent on crystallographic orientation. The force to reestablish the shearing fracture of adhesive bond at the interface between silicon carbide and metal was the lowest in the preferred orientation of silicon carbide slip system. The fracturing of silicon carbide occurred near the adhesive bond to metal and it was due to primary cleavages of both prismatic (10(-1)0) and basal (0001) planes.

Vanadium exposure-induced striatal learning and memory alterations in rats

PubMed Central

Sun, Liping; Wang, Keyue; Li, Yan; Fan, Qiyuan; Zheng, Wei; Li, Hong

2017-01-01

Occupational and environmental exposure to vanadium has been associated with toxicities in reproductive, respiratory, and cardiovascular systems. The knowledge on whether and how vanadium exposure caused neurobehavioral changes remains incomplete. This study was designed to investigate the changes in learning and memory following drinking water exposure to vanadium, and to conduct the preliminary study on underlying mechanisms. Male Sprague-Dawley rats were exposed to vanadium dissolved in drinking water at the concentration of 0.0, 0.5, 1.0 and 2.0 g/L, as the control, low-, medium-, and high- dose groups, respectively, for 12 weeks. The results by the Morris water maze test showed that the time for the testing animal to find the platform in the high exposed group was increased by 82.9% and 49.7%, as compared to animals in control and low-dose groups (p <0.05). There were significantly fewer rats in the medium- and high- dose groups than in the control group who were capable of crossing the platform (p <0.05). Quantitation of vanadium by atomic absorption spectrophotometry revealed a significant dose-dependent accumulation of vanadium in striatum (r = 0.931, p <0.01). Histopathological examination further demonstrated a degenerative damage in vanadium-exposed striatum. Interestingly, with the increase of the dose of vanadium, the contents of neurotransmitter ACh, 5-HT and GABA in the striatum increased; however, the levels of Syn1 was significantly reduced in the exposed groups compared with controls (p <0.05). These data suggest that vanadium exposure apparently reduces the animals’ learning ability. This could be due partly to vanadium’s accumulation in striatum and the ensuing toxicity to striatal structure and synaptic plasticity. Further research is warranted for mechanistic understanding of vanadium-induced neurotoxicity. PMID:28625925

Catalytic determination of vanadium in water

USGS Publications Warehouse

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.

DNA damage induction in human cells exposed to vanadium oxides in vitro.

PubMed

Rodríguez-Mercado, Juan J; Mateos-Nava, Rodrigo A; Altamirano-Lozano, Mario A

2011-12-01

Vanadium and vanadium salts cause genotoxicity and elicit variable biological effects depending on several factors. In the present study, we analyzed and compared the DNA damage and repair processes induced by vanadium in three oxidation states. We used human blood leukocytes in vitro and in a single cell gel electrophoresis assay at two pH values. We observed that vanadium(III) trioxide and vanadium(V) pentoxide produced DNA single-strand breaks at all of the concentrations (1, 2, 4, or 8 μg/ml) and treatment times (2, 4, or 6 h) tested. Vanadium(IV) tetraoxide treatment significantly increased DNA damage at all concentrations for 4 or 6 h of treatment but not for 2 h of treatment. The DNA repair kinetics indicated that most of the cells exposed to vanadium III and V for 4 h recovered within the repair incubation time of 90 min; however, those exposed to vanadium(IV) repaired their DNA within 120 min. The data at pH 9 indicated that vanadium(IV) tetraoxide induced DNA double-strand breaks. Our results show that the genotoxic effect of vanadium can be produced by any of its three oxidation states. However, vanadium(IV) induces double-strand breaks, and it is known that these lesions are linked with forming structural chromosomal aberrations. Copyright © 2011 Elsevier Ltd. All rights reserved.

Electronic structure of lead telluride-based alloys, doped with vanadium

NASA Astrophysics Data System (ADS)

Skipetrov, E. P.; Golovanov, A. N.; Slynko, E. I.; Slynko, V. E.

2013-01-01

The crystal structure, composition, galvanomagnetic properties in low magnetic fields (4.2 K ≤ T ≤ 300 K, B ≤ 0.07 T), and the Shubnikov-de Haas effect (T = 4.2 K, B ≤ 7 T) are studied in Pb1-x-ySnxVyTe (x = 0, 0.05-0.18) alloys synthesized by the Bridgman technique with variable vanadium impurity concentrations. It is shown that increasing the vanadium content leads to the formation of regions enriched in vanadium and of microscopic inclusions of compounds with compositions close to V3Te4. In Pb1-yVyTe stabilization of the Fermi level by a deep vanadium level, an insulator-metal transition, and a rise in the free electron concentration are observed as the vanadium content is increased. The variation in the free charge carrier concentration with increasing vanadium concentration in Pb1-yVyTe and Pb1-x-ySnxVyTe (x = 0.05-0.18) alloys is compared. Possible models for rearrangement of the electronic structure in Pb1-x-ySnxVyTe alloys with vanadium doping are discussed.

Essentiality and toxicity of vanadium supplements in health and pathology.

PubMed

Gruzewska, K; Michno, A; Pawelczyk, T; Bielarczyk, H

2014-10-01

The biological properties of vanadium complexes have become an object of interest due to their therapeutic potential in several diseases. However, the mechanisms of action of vanadium salts are still poorly understood. Vanadium complexes are cofactors for several enzymes and also exhibit insulin-mimetic properties. Thus, they are involved in the regulation of glucose metabolism, including in patients with diabetes. In addition, vanadium salts may also normalize blood pressure and play a key role in the metabolism of the thyroid and of iron as well as in the regulation of total cholesterol, cholesterol HDL and triglyceride (TG) levels in blood. Moreover, in cases of hypoxia, vanadium compounds may improve cardiomyocytes function. They may also exhibit both carcinogenic and anti-cancer properties. These include dose- and exposure-time-dependent induction and inhibition of the proliferation and survival of cancer cells. On the other hand, the balance between vanadium's therapeutic properties and its side effects has not yet been determined. Therefore, any studies on the potential use of vanadium compounds as supplements to support the treatment of a number of diseases must be strictly monitored for adverse effects.

Molecular geometry of vanadium dichloride and vanadium trichloride: a gas-phase electron diffraction and computational study.

PubMed

Varga, Zoltán; Vest, Brian; Schwerdtfeger, Peter; Hargittai, Magdolna

2010-03-15

The molecular geometries of VCl2 and VCl3 have been determined by computations and gas-phase electron diffraction (ED). The ED study is a reinvestigation of the previously published analysis for VCl2. The structure of the vanadium dichloride dimer has also been calculated. According to our joint ED and computational study, the evaporation of a solid sample of VCl2 resulted in about 66% vanadium trichloride and 34% vanadium dichloride in the vapor. Vanadium dichloride is unambiguously linear in its 4Sigma(g)+ ground electronic state. For VCl3, all computations yielded a Jahn-Teller-distorted ground-state structure of C(2v) symmetry. However, it lies merely less than 3 kJ/mol lower than the 3E'' state (D(3h) symmetry). Due to the dynamic nature of the Jahn-Teller effect in this case, rigorous distinction cannot be made between the planar models of either D(3h) symmetry or C(2v) symmetry for the equilibrium structure of VCl3. Furthermore, the presence of several low-lying excited electronic states of VCl3 is expected in the high-temperature vapor. To our knowledge, this is the first experimental and computational study of the VCl3 molecule.

Microstructure and properties of Fe-based composite coating by laser cladding Fe-Ti-V-Cr-C-CeO2 powder

NASA Astrophysics Data System (ADS)

Zhang, Hui; Zou, Yong; Zou, Zengda; Wu, Dongting

2015-01-01

In situ TiC-VC reinforced Fe-based cladding layer was obtained on low carbon steel surface by laser cladding with Fe-Ti-V-Cr-C-CeO2 alloy powder. The microstructure, phases and properties of the cladding layer were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), transmission electron microscopy (TEM), potentio-dynamic polarization and electro-chemical impedance spectroscopy (EIS). Results showed Fe-Ti-V-Cr-C-CeO2 alloy powder formed a good cladding layer without defects such as cracks and pores. The phases of the cladding layer were α-Fe, γ-Fe, TiC, VC and TiVC2. The microstructures of the cladding layer matrix were lath martensite and retained austenite. The carbides were polygonal blocks with a size of 0.5-2 μm and distributed uniformly in the cladding layer. High resolution transmission electron microscopy showed the carbide was a complex matter composed of nano TiC, VC and TiVC2. The cladding layer with a hardness of 1030 HV0.2 possessed good wear and corrosion resistance, which was about 16.85 and 9.06 times than that of the substrate respectively.

Effect of hydrogen on fatigue crack propagation in vanadium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chung, D.W.; Stoloff, N.S.

The influence of hydrogen on fatigue crack propagation in unalloyed vanadium and several hydrogen-charged vanadium alloys has been investigated. The Paris--Erdogan equation, da/dN = C(..delta..K)/sup m/, was approximately obeyed for all alloys. Crack growth rates were lowest in vanadium and dilute vanadium-hydrogen alloys, and were not very sensitive to volume fraction of hydrides in more concentrated alloys. The crack growth exponent, m, is inversely proportional to the cyclic strain hardening rate, n', and the rate constant C is inversely proportional to the square of the ultimate tensile stress, sigma/sub UTS/: metallographic examination showed hydride reorientation and growth in the originallymore » hydrided alloys. No stress-induced hydrides were observed in V-H solid-solution alloys. Fractures in hydrided materials exhibited cleavage-like features, while striations were noted in unalloyed vanadium and dilute solid-solution alloys.« less

Effect of hydrogen on fatigue crack propagation in vanadium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chung, D.W.; Stoloff, N.S.

The influence of hydrogen on fatigue crack propagation in unalloyed vanadium and several hydrogen-charged vanadium alloys has been investigated. The Paris--Erdogan equation, da/dN = C(..delta..K)/sup m/, was approximately obeyed for all alloys. Crack growth rates were lowest in vanadium and dilute vanadium--hydrogen alloys, and were not very sensitive to volume fraction of hydrides in more concentrated alloys. The crack growth exponent, m, is inversely proportional to the cyclic strain hardening rate, n', and the rate constant C is inversely proportional to the square of the ultimate tensile stress, sigma/sub UTS/: metallographic examination showed hydride reorientation and growth in the originallymore » hydrided alloys. No stress-induced hydrides were observed in V--H solid-solution alloys. Fractures in hydrided materials exhibited cleavage-like features, while striations were noted in unalloyed vanadium and dilute solid-solution alloys.« less

Spectrophotometric determination of vanadium in rutile and in mafic igneous rocks

USGS Publications Warehouse

Marinenko, John; Mei, Leung

1974-01-01

Minor and major levels of vanadium in rutile are separated from titanium and iron by sample fusion with sodium carbonate followed by water leach and filtration. The filtrate is then acidified with hydrochloric acid. Silicates are decomposed with a mixture of hydrofluoric and hydrochloric acids, and iron is separated by extraction of its chloride with diethyl ether. Sample vanadium in hydrochloric acid is then quantitatively reduced to vanadium(IV) with sulfurous acid. The remaining sulfur dioxide is expelled by heating. Vanadium (IV) then is reacted with excess of iron(III) at reduced acidity (pH 5) in the presence of 1,10-phenanthroline to yield the orange-red iron(II) 1,10-phenanthroline complex. Iron(II) generated by vanadium(IV) is a measure of total vanadium in the sample. The proposed method is free from elemental interferences because the color development cannot take place without the two redox reactions described above, and these are, under the outlined experimental conditions, quantitative only for vanadium.

Geochemistry of vanadium in an epigenetic, sandstone-hosted vanadium- uranium deposit, Henry Basin, Utah

USGS Publications Warehouse

Wanty, R.B.; Goldhaber, M.B.; Northrop, H.R.

1990-01-01

The epigenetic Tony M vanadium-uranium orebody in south-central Utah is hosted in fluvial sandstones of the Morrison Formation (Upper Jurassic). Measurements of the relative amounts of V+3 and V +4 in ore minerals show that V+3 is more abundant. Thermodynamic calculations show that vanadium was more likely transported to the site of mineralization as V+4. The ore formed as V+4 was reduced by hydrogen sulfide, followed by hydrolysis and precipitation of V+3 in oxide minerals or chlorite. Uranium was transported as uranyl ion (U+6), or some complex thereof, and reduced by hydrogen sulfide, forming coffinite. Detrital organic matter in the rocks served as the carbon source for sulfate-reducing bacteria. Vanadium most likely was derived from the dissolution of iron-titanium oxides. Uranium probably was derived from the overlying Brushy Basin Member of the Morrison Formation. Previous studies have shown that the ore formed at the density-stratified interface between a basinal brine and dilute meteoric water. The mineralization processes described above occurred within the mixing zone between these two fluids. -from Authors

NREL, American Vanadium Demonstrate First-of-Its-Kind Battery Management

Science.gov Websites

System | Energy Systems Integration Facility | NREL American Vanadium NREL, American Vanadium Demonstrate First-of-Its-Kind Battery Management System NREL researchers are collaborating with American Vanadium, an integrated energy storage company, to evaluate and demonstrate the first North American

Silicon carbide ceramic production

NASA Technical Reports Server (NTRS)

Suzuki, K.; Shinohara, N.

1984-01-01

A method to produce sintered silicon carbide ceramics in which powdery carbonaceous components with a dispersant are mixed with silicon carbide powder, shaped as required with or without drying, and fired in nonoxidation atmosphere is described. Carbon black is used as the carbonaceous component.

Recent progress on gas tungsten arc welding of vanadium alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

King, J.F.; Grossbeck, M.L.; Goodwin, G.M.

1997-04-01

This is a progress report on a continuing research project to acquire a fundamental understanding of the metallurgical processes in the welding of vanadium alloys. It also has the goal of developing techniques for welding structural vanadium alloys. The alloy V-4Cr-4Ti is used as a representative alloy of the group; it is also the prime candidate vanadium alloy for the U.S. Fusion Program at the present time. However, other alloys of this class were used in the research as necessary. The present work focuses on recent findings of hydrogen embrittlement found in vanadium alloy welds. It was concluded that themore » atmosphere in the inert gas glove box was insufficient for welding 6mm thick vanadium alloy plates.« less

Methods of producing continuous boron carbide fibers

DOEpatents

Garnier, John E.; Griffith, George W.

2015-12-01

Methods of producing continuous boron carbide fibers. The method comprises reacting a continuous carbon fiber material and a boron oxide gas within a temperature range of from approximately 1400.degree. C. to approximately 2200.degree. C. Continuous boron carbide fibers, continuous fibers comprising boron carbide, and articles including at least a boron carbide coating are also disclosed.

Methods for producing silicon carbide fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garnier, John E.; Griffith, George W.

Methods of producing silicon carbide fibers. The method comprises reacting a continuous carbon fiber material and a silicon-containing gas in a reaction chamber at a temperature ranging from approximately 1500.degree. C. to approximately 2000.degree. C. A partial pressure of oxygen in the reaction chamber is maintained at less than approximately 1.01.times.10.sup.2 Pascal to produce continuous alpha silicon carbide fibers. Continuous alpha silicon carbide fibers and articles formed from the continuous alpha silicon carbide fibers are also disclosed.

Modified lithium vanadium oxide electrode materials products and methods

DOEpatents

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.

Processing development of 4 tantalum carbide-hafnium carbide and related carbides and borides for extreme environments

NASA Astrophysics Data System (ADS)

Gaballa, Osama Gaballa Bahig

Carbides, nitrides, and borides ceramics are of interest for many applications because of their high melting temperatures and good mechanical properties. Wear-resistant coatings are among the most important applications for these materials. Materials with high wear resistance and high melting temperatures have the potential to produce coatings that resist degradation when subjected to high temperatures and high contact stresses. Among the carbides, Al4SiC4 is a low density (3.03 g/cm3), high melting temperature (>2000°C) compound, characterized by superior oxidation resistance, and high compressive strength. These desirable properties motivated this investigation to (1) obtain high-density Al4SiC4 at lower sintering temperatures by hot pressing, and (2) to enhance its mechanical properties by adding WC and TiC to the Al4SiC4. Also among the carbides, tantalum carbide and hafnium carbide have outstanding hardness; high melting points (3880°C and 3890°C respectively); good resistance to chemical attack, thermal shock, and oxidation; and excellent electronic conductivity. Tantalum hafnium carbide (Ta4HfC 5) is a 4-to-1 ratio of TaC to HfC with an extremely high melting point of 4215 K (3942°C), which is the highest melting point of all currently known compounds. Due to the properties of these carbides, they are considered candidates for extremely high-temperature applications such as rocket nozzles and scramjet components, where the operating temperatures can exceed 3000°C. Sintering bulk components comprised of these carbides is difficult, since sintering typically occurs above 50% of the melting point. Thus, Ta4 HfC5 is difficult to sinter in conventional furnaces or hot presses; furnaces designed for very high temperatures are expensive to purchase and operate. Our research attempted to sinter Ta4HfC5 in a hot press at relatively low temperature by reducing powder particle size and optimizing the powder-handling atmosphere, milling conditions, sintering

Combining Theory and Experiment for Multitechnique Characterization of Activated CO 2 on Transition Metal Carbide (001) Surfaces

DOE PAGES

Kunkel, Christian; Viñes, Francesc; Ramírez, Pedro J.; ...

2018-01-15

Early transition metal carbides (TMC; TM = Ti, Zr, Hf, V, Nb, Ta, Mo) with face-centered cubic crystallographic structure have emerged as promising materials for CO 2 capture and activation. Density functional theory (DFT) calculations using the Perdew–Burke–Ernzerhof exchange–correlation functional evidence charge transfer from the TMC surface to CO 2 on the two possible adsorption sites, namely, MMC and TopC, and the electronic structure and binding strength differences are discussed. Further, the suitability of multiple experimental techniques with respect to (1) adsorbed CO2 recognition and (2) MMC/TopC adsorption distinction is assessed from extensive DFT simulations. Results show that ultraviolet photoemissionmore » spectroscopies (UPS), work function changes, core level X-ray photoemission spectroscopy (XPS), and changes in linear optical properties could well allow for adsorbed CO2 detection. Only infrared (IR) spectra and scanning tunnelling microscopy (STM) seem to additionally allow for MMC/TopC adsorption site distinction. These findings are confirmed with experimental XPS measurements, demonstrating CO 2 binding on single crystal (001) surfaces of TiC, ZrC, and VC. The experiments also help resolving ambiguities for VC, where CO 2 activation was unexpected due to low adsorption energy, but could be related to kinetic trapping involving a desorption barrier. With a wealth of data reported and direct experimental evidence provided, this study aims to motivate further basic surface science experiments on an interesting case of CO 2 activating materials, allowing also for a benchmark of employed theoretical models.« less

Combining Theory and Experiment for Multitechnique Characterization of Activated CO 2 on Transition Metal Carbide (001) Surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kunkel, Christian; Viñes, Francesc; Ramírez, Pedro J.

Early transition metal carbides (TMC; TM = Ti, Zr, Hf, V, Nb, Ta, Mo) with face-centered cubic crystallographic structure have emerged as promising materials for CO 2 capture and activation. Density functional theory (DFT) calculations using the Perdew–Burke–Ernzerhof exchange–correlation functional evidence charge transfer from the TMC surface to CO 2 on the two possible adsorption sites, namely, MMC and TopC, and the electronic structure and binding strength differences are discussed. Further, the suitability of multiple experimental techniques with respect to (1) adsorbed CO2 recognition and (2) MMC/TopC adsorption distinction is assessed from extensive DFT simulations. Results show that ultraviolet photoemissionmore » spectroscopies (UPS), work function changes, core level X-ray photoemission spectroscopy (XPS), and changes in linear optical properties could well allow for adsorbed CO2 detection. Only infrared (IR) spectra and scanning tunnelling microscopy (STM) seem to additionally allow for MMC/TopC adsorption site distinction. These findings are confirmed with experimental XPS measurements, demonstrating CO 2 binding on single crystal (001) surfaces of TiC, ZrC, and VC. The experiments also help resolving ambiguities for VC, where CO 2 activation was unexpected due to low adsorption energy, but could be related to kinetic trapping involving a desorption barrier. With a wealth of data reported and direct experimental evidence provided, this study aims to motivate further basic surface science experiments on an interesting case of CO 2 activating materials, allowing also for a benchmark of employed theoretical models.« less

Exposure of Daphnia magna to trichloroethylene (TCE) and vinyl chloride (VC): evaluation of gene transcription, cellular activity, and life-history parameters.

PubMed

Houde, Magali; Douville, Mélanie; Gagnon, Pierre; Sproull, Jim; Cloutier, François

2015-06-01

Trichloroethylene (TCE) is a ubiquitous contaminant classified as a human carcinogen. Vinyl chloride (VC) is primarily used to manufacture polyvinyl chloride and can also be a degradation product of TCE. Very few data exist on the toxicity of TCE and VC in aquatic organisms particularly at environmentally relevant concentrations. The aim of this study was to evaluate the sub-lethal effects (10 day exposure; 0.1; 1; 10 µg/L) of TCE and VC in Daphnia magna at the gene, cellular, and life-history levels. Results indicated impacts of VC on the regulation of genes related to glutathione-S-transferase (GST), juvenile hormone esterase (JHE), and the vitelline outer layer membrane protein (VMO1). On the cellular level, exposure to 0.1, 1, and 10 µg/L of VC significantly increased the activity of JHE in D. magna and TCE increased the activity of chitinase (at 1 and 10 µg/L). Results for life-history parameters indicated a possible tendency of TCE to affect the number of molts at the individual level in D. magna (p=0.051). Measurement of VG-like proteins using the alkali-labile phosphates (ALP) assay did not show differences between TCE treated organisms and controls. However, semi-quantitative measurement using gradient gel electrophoresis (213-218 kDa) indicated significant decrease in VG-like protein levels following exposure to TCE at all three concentrations. Overall, results indicate effects of TCE and VC on genes and proteins related to metabolism, reproduction, and growth in D. magna. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

Conductive heat flux in VC-1 and the thermal regime of Valles caldera, Jemez Mountains, New Mexico ( USA).

USGS Publications Warehouse

Sass, J.H.; Morgan, P.

1988-01-01

Over 5% of heat in the western USA is lost through Quaternary silicic volcanic centers, including the Valles caldera in N central New Mexico. These centers are the sites of major hydrothermal activity and upper crustal metamorphism, metasomatism, and mineralization, producing associated geothermal resources. Presents new heat flow data from Valles caldera core hole 1 (VC-1), drilled in the SW margin of the Valles caldera. Thermal conductivities were measured on 55 segments of core from VC-1, waxed and wrapped to preserve fluids. These values were combined with temperature gradient data to calculate heat flow. Above 335 m, which is probably unsaturated, heat flow is 247 + or - 16 mW m-2. Inteprets the shallow thermal gradient data and the thermal regime at VC-1 to indicate a long-lived hydrothermal (and magmatic) system in the southwestern Valles caldera that has been maintained through the generation of shallow magma bodies during the long postcollapse history of the caldera. High heat flow at the VC-1 site is interpreted to result from hot water circulating below the base of the core hole, and we attribute the lower heat flow in the unsaturated zone is attributed to hydrologic recharge. -from Authors

Optimizing the Calculation of DM,CO and VC via the Single Breath Single Oxygen Tension DLCO/NO Method

PubMed Central

Coffman, Kirsten E.; Taylor, Bryan J.; Carlson, Alex R.; Wentz, Robert J.; Johnson, Bruce D.

2015-01-01

Alveolar-capillary membrane conductance (DM,CO) and pulmonary-capillary blood volume (VC) are calculated via lung diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO) using the single breath, single oxygen tension (single-FiO2) method. However, two calculation parameters, the reaction rate of carbon monoxide with blood (θCO) and the DM,NO/DM,CO ratio (α-ratio), are controversial. This study systematically determined optimal θCO and α-ratio values to be used in the single-FiO2 method that yielded the most similar DM,CO and VC values compared to the ‘gold-standard’ multiple-FiO2 method. Eleven healthy subjects performed single breath DLCO/DLNO maneuvers at rest and during exercise. DM,CO and VC were calculated via the single-FiO2 and multiple-FiO2 methods by implementing seven θCO equations and a range of previously reported α-ratios. The RP θCO equation (Reeves and Park, Respiration physiology 88:1–21, 1992.) and an α-ratio of 4.0–4.4 yielded DM,CO and VC values that were most similar between methods. The RP θCO equation and an experimental α-ratio should be used in future studies. PMID:26521031

Neural networks with local receptive fields and superlinear VC dimension.

PubMed

Schmitt, Michael

2002-04-01

Local receptive field neurons comprise such well-known and widely used unit types as radial basis function (RBF) neurons and neurons with center-surround receptive field. We study the Vapnik-Chervonenkis (VC) dimension of feedforward neural networks with one hidden layer of these units. For several variants of local receptive field neurons, we show that the VC dimension of these networks is superlinear. In particular, we establish the bound Omega(W log k) for any reasonably sized network with W parameters and k hidden nodes. This bound is shown to hold for discrete center-surround receptive field neurons, which are physiologically relevant models of cells in the mammalian visual system, for neurons computing a difference of gaussians, which are popular in computational vision, and for standard RBF neurons, a major alternative to sigmoidal neurons in artificial neural networks. The result for RBF neural networks is of particular interest since it answers a question that has been open for several years. The results also give rise to lower bounds for networks with fixed input dimension. Regarding constants, all bounds are larger than those known thus far for similar architectures with sigmoidal neurons. The superlinear lower bounds contrast with linear upper bounds for single local receptive field neurons also derived here.

Carbide coated fibers in graphite-aluminum composites

NASA Technical Reports Server (NTRS)

Imprescia, R. J.; Levinson, L. S.; Reiswig, R. D.; Wallace, T. C.; Williams, J. M.

1975-01-01

The study of protective-coupling layers of refractory metal carbides on the graphite fibers prior to their incorporation into composites is presented. Such layers should be directly wettable by liquid aluminum and should act as diffusion barriers to prevent the formation of aluminum carbide. Chemical vapor deposition was used to uniformly deposit thin, smooth, continuous coats of ZrC on the carbon fibers of tows derived from both rayon and polyacrylonitrile. A wet chemical coating of the fibers, followed by high-temperature treatment, was used, and showed promise as an alternative coating method. Experiments were performed to demonstrate the ability of aluminum alloys to wet carbide surfaces. Titanium carbide, zirconium carbide and carbide-coated graphite surfaces were successfully wetted. Results indicate that initial attempts to wet surfaces of ZrC-coated carbon fibers appear successful.

Molecular characterisation of a calmodulin gene, VcCaM1, that is differentially expressed under aluminium stress in highbush blueberry.

PubMed

Inostroza-Blancheteau, C; Aquea, F; Loyola, R; Slovin, J; Josway, S; Rengel, Z; Reyes-Díaz, M; Alberdi, M; Arce-Johnson, P

2013-11-01

Calmodulin (CaM), a small acidic protein, is one of the best characterised Ca(2+) sensors in eukaryotes. This Ca(2+) -regulated protein plays a critical role in decoding and transducing environmental stress signals by activating specific targets. Many environmental stresses elicit changes in intracellular Ca(2+) activity that could initiate adaptive responses under adverse conditions. We report the first molecular cloning and characterisation of a calmodulin gene, VcCaM1 (Vaccinium corymbosum Calmodulin 1), in the woody shrub, highbush blueberry. VcCaM1 was first identified as VCAL19, a gene induced by aluminium stress in V. corymbosum L. A full-length cDNA of VcCaM1 containing a 766-bp open reading frame (ORF) encoding 149 amino acids was cloned from root RNA. The sequence encodes four Ca(2+) -binding motifs (EF-hands) and shows high similarity (99%) with the isoform CaM 201 of Daucus carota. Expression analyses showed that following Al treatment, VcCaM1 message level decreased in roots of Brigitta, an Al-resistant cultivar, and after 48 h, was lower than in Bluegold, an Al-sensitive cultivar. VcCAM1 message also decreased in leaves of both cultivars within 2 h of treatment. Message levels in leaves then increased by 24 h to control levels in Brigitta, but not in Bluegold, but then decreased again by 48 h. In conclusion, VcCaM1 does not appear to be directly involved in Al resistance, but may be involved in improved plant performance under Al toxicity conditions through regulation of Ca(2+) homeostasis and antioxidant systems in leaves. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

Method of fabricating porous silicon carbide (SiC)

NASA Technical Reports Server (NTRS)

Shor, Joseph S. (Inventor); Kurtz, Anthony D. (Inventor)

1995-01-01

Porous silicon carbide is fabricated according to techniques which result in a significant portion of nanocrystallites within the material in a sub 10 nanometer regime. There is described techniques for passivating porous silicon carbide which result in the fabrication of optoelectronic devices which exhibit brighter blue luminescence and exhibit improved qualities. Based on certain of the techniques described porous silicon carbide is used as a sacrificial layer for the patterning of silicon carbide. Porous silicon carbide is then removed from the bulk substrate by oxidation and other methods. The techniques described employ a two-step process which is used to pattern bulk silicon carbide where selected areas of the wafer are then made porous and then the porous layer is subsequently removed. The process to form porous silicon carbide exhibits dopant selectivity and a two-step etching procedure is implemented for silicon carbide multilayers.

40 CFR 440.80 - Applicability; description of the vanadium ore subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... vanadium ore subcategory. 440.80 Section 440.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORE MINING AND DRESSING POINT SOURCE CATEGORY Vanadium Ore Subcategory (Mined Alone and Not as a Byproduct) § 440.80 Applicability; description of the vanadium ore...

40 CFR 440.80 - Applicability; description of the vanadium ore subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... vanadium ore subcategory. 440.80 Section 440.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORE MINING AND DRESSING POINT SOURCE CATEGORY Vanadium Ore Subcategory (Mined Alone and Not as a Byproduct) § 440.80 Applicability; description of the vanadium ore...

Positron lifetime in vanadium oxide bronzes

NASA Astrophysics Data System (ADS)

Dryzek, J.; Dryzek, E.

2003-09-01

The positron lifetime (PL) and Doppler broadening (DB) of annihilation line measurements have been performed in vanadium oxide bronzes MxV2O5. The dependence of these annihilation characteristics on the kind and concentration of the metal M donor has been observed. In the PL spectrum only one lifetime component has been detected in all studied bronzes. The results indicate the positron localization in the structural tunnels present in the crystalline lattice of the vanadium oxide bronzes. (

Intelligent MONitoring System for antiviral pharmacotherapy in patients with chronic hepatitis C (SiMON-VC).

PubMed

Margusino-Framiñán, Luis; Cid-Silva, Purificación; Mena-de-Cea, Álvaro; Sanclaudio-Luhía, Ana Isabel; Castro-Castro, José Antonio; Vázquez-González, Guillermo; Martín-Herranz, Isabel

2017-01-01

Two out of six strategic axes of pharmaceutical care in our hospital are quality and safety of care, and the incorporation of information technologies. Based on this, an information system was developed in the outpatient setting for pharmaceutical care of patients with chronic hepatitis C, SiMON-VC, which would improve the quality and safety of their pharmacotherapy. The objective of this paper is to describe requirements, structure and features of Si- MON-VC. Requirements demanded were that the information system would enter automatically all critical data from electronic clinical records at each of the visits to the Outpatient Pharmacy Unit, allowing the generation of events and alerts, documenting the pharmaceutical care provided, and allowing the use of data for research purposes. In order to meet these requirements, 5 sections were structured for each patient in SiMON-VC: Main Record, Events, Notes, Monitoring Graphs and Tables, and Follow-up. Each section presents a number of tabs with those coded data needed to monitor patients in the outpatient unit. The system automatically generates alerts for assisted prescription validation, efficacy and safety of using antivirals for the treatment of this disease. It features a completely versatile Indicator Control Panel, where temporary monitoring standards and alerts can be set. It allows the generation of reports, and their export to the electronic clinical record. It also allows data to be exported to the usual operating systems, through Big Data and Business Intelligence. Summing up, we can state that SiMON-VC improves the quality of pharmaceutical care provided in the outpatient pharmacy unit to patients with chronic hepatitis C, increasing the safety of antiviral therapy. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Quantitation and detection of vanadium in biologic and pollution materials

NASA Technical Reports Server (NTRS)

Gordon, W. A.

1974-01-01

A review is presented of special considerations and methodology for determining vanadium in biological and air pollution materials. In addition to descriptions of specific analysis procedures, general sections are included on quantitation of analysis procedures, sample preparation, blanks, and methods of detection of vanadium. Most of the information presented is applicable to the determination of other trace elements in addition to vanadium.

Silicon carbide thyristor

NASA Technical Reports Server (NTRS)

Edmond, John A. (Inventor); Palmour, John W. (Inventor)

1996-01-01

The SiC thyristor has a substrate, an anode, a drift region, a gate, and a cathode. The substrate, the anode, the drift region, the gate, and the cathode are each preferably formed of silicon carbide. The substrate is formed of silicon carbide having one conductivity type and the anode or the cathode, depending on the embodiment, is formed adjacent the substrate and has the same conductivity type as the substrate. A drift region of silicon carbide is formed adjacent the anode or cathode and has an opposite conductivity type as the anode or cathode. A gate is formed adjacent the drift region or the cathode, also depending on the embodiment, and has an opposite conductivity type as the drift region or the cathode. An anode or cathode, again depending on the embodiment, is formed adjacent the gate or drift region and has an opposite conductivity type than the gate.

Low-temperature direct synthesis of mesoporous vanadium nitrides for electrochemical capacitors

NASA Astrophysics Data System (ADS)

Lee, Hae-Min; Jeong, Gyoung Hwa; Kim, Sang-Wook; Kim, Chang-Koo

2017-04-01

Mesoporous vanadium nitrides are directly synthesized by a one-step chemical precipitation method at a low temperature (70 °C). Structural and morphological analyses reveal that vanadium nitride consist of long and slender nanowhiskers, and mesopores with diameters of 2-5 nm. Compositional analysis confirms the presence of vanadium in the VN structure, along with oxidized vanadium. The cyclic voltammetry and charge-discharge tests indicate that the obtained material stores charges via a combination of electric double-layer capacitance and pseudocapacitance mechanisms. The vanadium nitride electrode exhibits a specific capacitance of 598 F/g at a current density of 4 A/g. After 5000 charge-discharge cycles, the electrode has an equivalent series resistance of 1.42 Ω and retains 83% of its initial specific capacitance. This direct low-temperature synthesis of mesoporous vanadium nitrides is a simple and promising method to achieve high specific capacitance and low equivalent series resistance for electrochemical capacitor applications.

Nanostructured Electrocatalysts for All-Vanadium Redox Flow Batteries.

PubMed

Park, Minjoon; Ryu, Jaechan; Cho, Jaephil

2015-10-01

Vanadium redox reactions have been considered as a key factor affecting the energy efficiency of the all-vanadium redox flow batteries (VRFBs). This redox reaction determines the reaction kinetics of whole cells. However, poor kinetic reversibility and catalytic activity towards the V(2+)/V(3+) and VO(2+)/VO2(+) redox couples on the commonly used carbon substrate limit broader applications of VRFBs. Consequently, modified carbon substrates have been extensively investigated to improve vanadium redox reactions. In this Focus Review, recent progress on metal- and carbon-based nanomaterials as an electrocatalyst for VRFBs is discussed in detail, without the intention to provide a comprehensive review on the whole components of the system. Instead, the focus is mainly placed on the redox chemistry of vanadium ions at a surface of various metals, different dimensional carbons, nitrogen-doped carbon nanostructures, and metal-carbon composites. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Kinetics and Equilibrium Study of Vanadium Dissolution from Vanadium Oxides and Phosphates in Battery Electrolytes: Possible Impacts on ICD Battery Performance.

PubMed

Bock, David C; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S

2013-06-01

Silver vanadium oxide (Ag 2 V 4 O 11 , SVO) has enjoyed widespread commercial success over the past 30 years as a cathode material for implantable cardiac defibrillator (ICD) batteries. Recently, silver vanadium phosphorous oxide (Ag 2 VO 2 PO 4 , SVPO) has been studied as possibly combining the desirable thermal stability aspects of LiFePO 4 with the electrical conductivity of SVO. Further, due to the noted insoluble nature of most phosphate salts, a lower material solubility of SVPO relative to SVO is anticipated. Thus, the first vanadium dissolution studies of SVPO in battery electrolyte solutions are described herein. The equilibrium solubility of SVPO was ~5 times less than SVO, with a rate constant of dissolution ~3.5 times less than that of SVO. The vanadium dissolution in SVO and SVPO can be adequately described with a diffusion layer model, as supported by the Noyes-Whitney equation. Cells prepared with vanadium-treated anodes displayed higher AC impedance and DC resistance relative to control anodes. These data support the premise that SVPO cells are likely to exhibit reduced cathode solubility and thus less affected by increased cell resistance due to cathode solubility compared to SVO based cells.

Tackling capacity fading in vanadium flow batteries with amphoteric membranes

NASA Astrophysics Data System (ADS)

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.

Method for preparing boron-carbide articles

DOEpatents

Benton, S.T.; Masters, D.R.

1975-10-21

The invention is directed to the preparation of boron carbide articles of various configurations. A stoichiometric mixture of particulate boron and carbon is confined in a suitable mold, heated to a temperature in the range of about 1250 to 1500$sup 0$C for effecting a solid state diffusion reaction between the boron and carbon for forming the boron carbide (B$sub 4$C), and thereafter the resulting boron-carbide particles are hot-pressed at a temperature in the range of about 1800 to 2200$sup 0$C and a pressure in the range of about 1000 to 4000 psi for densifying and sintering the boron carbide into the desired article.

Terrier Black Brant VC design characteristics and program status. [rocket development

NASA Technical Reports Server (NTRS)

Payne, B. R.; Mayo, E. E.

1979-01-01

In the present paper, the design analysis of the Terrier-Black Brant VC, representing the latest addition to the Black Brant rocket family, is discussed, including the aerodynamic, structural, thermal, and operational aspects. An appreciable increase in apogee, as compared to the BBVC and Nike/BBVC, is achieved without any modifications to the well-proven BBV motor or degradation of the thermal or dynamic flight environment.

Optimizing the calculation of DM,CO and VC via the single breath single oxygen tension DLCO/NO method.

PubMed

Coffman, Kirsten E; Taylor, Bryan J; Carlson, Alex R; Wentz, Robert J; Johnson, Bruce D

2016-01-15

Alveolar-capillary membrane conductance (D(M,CO)) and pulmonary-capillary blood volume (V(C)) are calculated via lung diffusing capacity for carbon monoxide (DL(CO)) and nitric oxide (DL(NO)) using the single breath, single oxygen tension (single-FiO2) method. However, two calculation parameters, the reaction rate of carbon monoxide with blood (θ(CO)) and the D(M,NO)/D(M,CO) ratio (α-ratio), are controversial. This study systematically determined optimal θ(CO) and α-ratio values to be used in the single-FiO2 method that yielded the most similar D(M,CO) and V(C) values compared to the 'gold-standard' multiple-FiO2 method. Eleven healthy subjects performed single breath DL(CO)/DL(NO) maneuvers at rest and during exercise. D(M,CO) and V(C) were calculated via the single-FiO2 and multiple-FiO2 methods by implementing seven θ(CO) equations and a range of previously reported α-ratios. The RP θ(CO) equation (Reeves, R.B., Park, H.K., 1992. Respiration Physiology 88 1-21) and an α-ratio of 4.0-4.4 yielded DM,CO and VC values that were most similar between methods. The RP θ(CO) equation and an experimental α-ratio should be used in future studies. Copyright © 2015 Elsevier B.V. All rights reserved.

Vanadium-uranium extraction from Wyoming vanadiferoud silicates. Report of investigations/1983

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayashi, M.; Nichols, I.L.; Huiatt, J.L.

1983-11-01

The Bureau of Mines conducted laboratory studies on low-grade vanadiferous silicates from the Pumpkin Buttes and Nine Mile Lake deposits of Wyoming to examine techniques for extracting vanadium and uranium. Recovery from low-grade sources such as these could contribute to future vanadium production and reduce reliance on vanadium imports.

Particle Characteristics and Densification of W6Mo5Cr4V2Co5Nb Overspray Powder

NASA Astrophysics Data System (ADS)

Pi, Ziqiang; Lu, Xin; Yang, Fei; Liu, Bowen; Jia, Chengchang; Qu, Xuanhui; Zheng, Wei; Wu, Lizhi; Shao, Qingli

2018-05-01

W6Mo5Cr4V2Co5Nb (825 K) alloy was prepared by a two-step sintering process from overspray 825 K alloy powder. The overspray powder characteristics and the microstructure and mechanical properties of the as-sintered 825 K alloy were investigated. Results showed that two types of carbides formed a network structure in the overspray powder, which had spherical or quasispherical shape: one was MC carbide that was rich in vanadium (V), and the other was M2C carbide enriched with vanadium (V) and tungsten (W). The sintered 825 K alloy contained M6C and MC carbides, of which M6C was rich in tungsten (W) and molybdenum (Mo), and both of these two carbides were uniformly distributed in the alloy matrix. The alloy had relative density of 98.43%, hardness of HRC 51.8, and superior bending strength of 2042 MPa. These mechanical properties can meet the requirements of most engineering applications.

Effectively suppressing vanadium permeation in vanadium redox flow battery application with modified Nafion membrane with nacre-like nanoarchitectures

NASA Astrophysics Data System (ADS)

Zhang, Lesi; Ling, Ling; Xiao, Min; Han, Dongmei; Wang, Shuanjin; Meng, Yuezhong

2017-06-01

A novel self-assembled composite membrane, Nafion-[PDDA/ZrP]n with nacre-like nanostructures was successfully fabricated by a layer-by-layer (LbL) method and used as proton exchange membrane for vanadium redox flow battery applications. Poly(diallyldimethylammonium chloride) (PDDA) with positive charges and zirconium phosphate (ZrP) nanosheets with negative charges can form ultra-thin nacre-like nanostructure on the surface of Nafion membrane via the ionic crosslinking of tightly folded macromolecules. The lamellar structure of ZrP nanosheets and Donnan exclusion effect of PDDA can greatly decrease the vanadium ion permeability and improve the selectivity of proton conductivity. The fabricated Nafion-[PDDA/ZrP]4 membrane shows two orders of magnitude lower vanadium ion permeability (1.05 × 10-6 cm2 min-1) and 12 times higher ion selectivity than those of pristine Nafion membrane at room temperature. Consequently, the performance of vanadium redox flow batteries (VRFBs) assembled with Nafion-[PDDA/ZrP]3 membrane achieved a highly coulombic efficiency (CE) and energy efficiency (EE) together with a very slow self-discharge rate. When comparing with pristine Nafion VRFB, the CE and EE values of Nafion-[PDDA/ZrP]3 VRFB are 10% and 7% higher at 30 mA cm-2, respectively.

Nuclear reactor fuel element with vanadium getter on cladding

DOEpatents

Johnson, Carl E.; Carroll, Kenneth G.

1977-01-01

A nuclear reactor fuel element is described which has an outer cladding, a central core of fissionable or mixed fissionable and fertile fuel material and a layer of vanadium as an oxygen getter on the inner surface of the cladding. The vanadium reacts with oxygen released by the fissionable material during irradiation of the core to prevent the oxygen from reacting with and corroding the cladding. Also described is a method for coating the inner surface of small diameter tubes of cladding with a layer of vanadium.

Vanadium diffusion coating on HT-9 cladding for mitigating the fuel cladding chemical interactions

NASA Astrophysics Data System (ADS)

Lo, Wei-Yang; Yang, Yong

2014-08-01

Fuel cladding chemical interaction (FCCI) has been identified as one of the crucial issues for developing Ferritic/Martensitic (F/M) stainless steel claddings for metallic fuels in a fast reactor. The anticipated elevated temperature and high neutron flux can significantly aggravate the FCCI, in terms of formation of inter-diffusion and lower melting point eutectic phases. To mitigate the FCCI, vanadium carbide coating as a diffusion barrier was deposited on the HT-9 substrate using a pack cementation diffusion coating (PCDC) method, and the processing temperature was optimized down to 730 °C. A solid metallurgical bonding between the coating layer and substrate was achieved, and the coating is free from through depth cracks. The microstructural characterizations using SEM and TEM show a nanostructured grain structure. EDS/WDS and XRD analysis confirm the phase of coating layer as V2C. Diffusion couple tests at 660 °C for 100 h demonstrate that V2C layer with a thickness of less than 5 μm can effectively eliminate the inter-diffusion between the lanthanide cerium and HT-9 steel.

Vanadium Recovery from Oil Fly Ash by Carbon Removal and Roast-Leach Process

NASA Astrophysics Data System (ADS)

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.

Vanadium Extraction from Shale via Sulfuric Acid Baking and Leaching

NASA Astrophysics Data System (ADS)

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.

New Icosahedral Boron Carbide Semiconductors

NASA Astrophysics Data System (ADS)

Echeverria Mora, Elena Maria

Novel semiconductor boron carbide films and boron carbide films doped with aromatic compounds have been investigated and characterized. Most of these semiconductors were formed by plasma enhanced chemical vapor deposition. The aromatic compound additives used, in this thesis, were pyridine (Py), aniline, and diaminobenzene (DAB). As one of the key parameters for semiconducting device functionality is the metal contact and, therefore, the chemical interactions or band bending that may occur at the metal/semiconductor interface, X-ray photoemission spectroscopy has been used to investigate the interaction of gold (Au) with these novel boron carbide-based semiconductors. Both n- and p-type films have been tested and pure boron carbide devices are compared to those containing aromatic compounds. The results show that boron carbide seems to behave differently from other semiconductors, opening a way for new analysis and approaches in device's functionality. By studying the electrical and optical properties of these films, it has been found that samples containing the aromatic compound exhibit an improvement in the electron-hole separation and charge extraction, as well as a decrease in the band gap. The hole carrier lifetimes for each sample were extracted from the capacitance-voltage, C(V), and current-voltage, I(V), curves. Additionally, devices, with boron carbide with the addition of pyridine, exhibited better collection of neutron capture generated pulses at ZERO applied bias, compared to the pure boron carbide samples. This is consistent with the longer carrier lifetimes estimated for these films. The I-V curves, as a function of external magnetic field, of the pure boron carbide films and films containing DAB demonstrate that significant room temperature negative magneto-resistance (> 100% for pure samples, and > 50% for samples containing DAB) is possible in the resulting dielectric thin films. Inclusion of DAB is not essential for significant negative magneto

Tempering characteristics of a vanadium containing dual phase steel

NASA Astrophysics Data System (ADS)

Rashid, M. S.; Rao, B. V. N.

1982-10-01

Dual phase steels are characterized by a microstructure consisting of ferrite, martensite, retained austenite, and/or lower bainite. This microstructure can be altered by tempering with accompanying changes in mechanical properties. This paper examines such changes produced in a vanadium bearing dual phase steel upon tempering below 500 °C. The steel mechanical properties were minimally affected on tempering below 200 °C; however, a simultaneous reduction in uniform elongation and tensile strength occurred upon tempering above 400 °C. The large amount of retained austenite (≅10 vol pct) observed in the as-received steel was found to be essentially stable to tempering below 300 °C. On tempering above 400 °C, most of the retained austenite decomposed to either upper bainite (at 400 °C) or a mixture of upper bainite and ferrite-carbide aggregate formed by an interphase precipitation mechanism (at 500 °C). In addition, tempering at 400 °C led to fine precipitation in the retained ferrite. The observed mechanical properties were correlated with these microstructural changes. It was concluded that the observed decrease in uniform elongation upon tempering above 400 °C is primarily the consequence of the decomposition of retained austenite and the resulting loss of transformation induced plasticity (TRIP) as a contributing mechanism to the strain hardening of the steel.

Formation of dysprosium carbide on the graphite (0001) surface

DOE PAGES

Lii-Rosales, Ann; Zhou, Yinghui; Wallingford, Mark; ...

2017-07-12

When using scanning tunneling microscopy, we characterize a surface carbide that forms such that Dy is deposited on the basal plane of graphite. In order to form carbide islands on terraces, Dy is first deposited at 650–800 K, which forms large metallic islands. Upon annealing at 1000 K, these clusters convert to carbide. Deposition directly at 1000 K is ineffective because nucleation on terraces is inhibited. Reaction is signaled by the fact that each carbide cluster is partially or totally surrounded by an etch pit. The etch pit is one carbon layer deep for most carbide clusters. Carbide clusters aremore » also identifiable by striations on their surfaces. Based on mass balance, and assuming that only the surface layer of carbon is involved in the reaction, the carbide has stoichiometry D y 2 C . This is Dy-rich compared with the most common bulk carbide Dy C 2 , which may reflect limited surface carbon transport to the carbide.« less

Iron diminishes the in vitro biological effect of vanadium.

EPA Science Inventory

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...

Amphoteric Ion-Exchange Membranes with Significantly Improved Vanadium Barrier Properties for All-Vanadium Redox Flow Batteries.

PubMed

Nibel, Olga; Rojek, Tomasz; Schmidt, Thomas J; Gubler, Lorenz

2017-07-10

All-vanadium redox flow batteries (VRBs) have attracted considerable interest as promising energy-storage devices that can allow the efficient utilization of renewable energy sources. The membrane, which separates the porous electrodes in a redox flow cell, is one of the key components in VRBs. High rates of crossover of vanadium ions and water through the membrane impair the efficiency and capacity of a VRB. Thus, membranes with low permeation rate of vanadium species and water are required, also characterized by low resistance and stability in the VRB environment. Here, we present a new design concept for amphoteric ion-exchange membranes, based on radiation-induced grafting of vinylpyridine into an ethylene tetrafluoroethylene base film and a two-step functionalization to introduce cationic and anionic exchange sites, respectively. During long-term cycling, redox flow cells containing these membranes showed higher efficiency, less pronounced electrolyte imbalance, and significantly reduced capacity decay compared to the cells with the benchmark material Nafion 117. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Silicon carbide fibers and articles including same

DOEpatents

Garnier, John E; Griffith, George W

2015-01-27

Methods of producing silicon carbide fibers. The method comprises reacting a continuous carbon fiber material and a silicon-containing gas in a reaction chamber at a temperature ranging from approximately 1500.degree. C. to approximately 2000.degree. C. A partial pressure of oxygen in the reaction chamber is maintained at less than approximately 1.01.times.10.sup.2 Pascal to produce continuous alpha silicon carbide fibers. Continuous alpha silicon carbide fibers and articles formed from the continuous alpha silicon carbide fibers are also disclosed.

Compatibility of buffered uranium carbides with tungsten.

NASA Technical Reports Server (NTRS)

Phillips, W. M.

1971-01-01

Results of compatibility tests between tungsten and hyperstoichiometric uranium carbide alloys run at 1800 C for 1000 and 2500 hours. These tests compared tungsten-buffered uranium carbide with tungsten-buffered uranium-zirconium carbide. The zirconium carbide addition appeared to widen the homogeneity range of the uranium carbide, making additional carbon available for reaction. Reaction layers could be formed by either of two diffusion paths, one producing UWC2, while the second resulted in the formation of W2C. UWC2 acts as a diffusion barrier for carbon and slows the growth of the reaction layer with time, while carbon diffusion is relatively rapid in W2C, allowing equilibrium to be reached in less than 2500 hours at a temperature of 1800 C.

Catalytic destruction of PCDD/Fs over vanadium oxide-based catalysts.

PubMed

Yu, Ming-Feng; Lin, Xiao-Qing; Li, Xiao-Dong; Yan, Mi; Prabowo, Bayu; Li, Wen-Wei; Chen, Tong; Yan, Jian-Hua

2016-08-01

Vanadium oxide-based catalysts were developed for the destruction of vapour phase PCDD/Fs (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans). A vapour phase PCDD/Fs generating system was designed to supply stable PCDD/Fs steam with initial concentration of 3.2 ng I-TEQ Nm(-3). Two kinds of titania (nano-TiO2 and conventional TiO2) and alumina were used as catalyst supports. For vanadium-based catalysts supported on nano-TiO2, catalyst activity is enhanced with operating temperature increasing from 160 to 300 °C and then reduces with temperature rising further to 350 °C. It is mainly due to the fact that high volatility of organic compounds at 350 °C suppresses adsorption of PCDD/Fs on catalysts surface and then further inhibits the reaction between catalyst and PCDD/Fs. The optimum loading of vanadium on nano-TiO2 support is 5 wt.% where vanadium oxide presents highly dispersed amorphous state according to the Raman spectra and XRD patterns. Excessive vanadium will block the pore space and form microcrystalline V2O5 on the support surface. At the vanadium loading of 5 wt.%, nano-TiO2-supported catalyst performs best on PCDD/Fs destruction compared to Al2O3 and conventional TiO2. Chemical states of vanadium in the fresh, used and reoxidized VOx(5 %)/TiO2 catalysts at different operating temperature are also analysed by XPS.

Vanadium accumulation in carbonaceous rocks: A review of geochemical controls during deposition and diagenesis

USGS Publications Warehouse

Breit, G.N.; Wanty, R.B.

1991-01-01

Published data relevant to the geochemistry of vanadium were used to evaluate processes and conditions that control vanadium accumulation in carbonaceous rocks. Reduction, adsorption, and complexation of dissolved vanadium favor addition of vanadium to sediments rich in organic carbon. Dissolved vanadate (V(V)) species predominate in oxic seawater and are reduced to vanadyl ion (V(IV)) by organic compounds or H2S. Vanadyl ion readily adsorbs to particle surfaces and is added to the sediment as the particles settle. The large vanadium concentrations of rocks deposited in marine as compared to lacustrine environments are the result of the relatively large amount of vanadium provided by circulating ocean water compared to terrestrial runoff. Vanadium-rich carbonaceous rocks typically have high contents of organically bound sulfur and are stratigraphically associated with phosphate-rich units. A correspondence between vanadium content and organically bound sulfur is consistent with high activities of H2S during sediment deposition. Excess H2S exited the sediment into bottom waters and favored reduction of dissolved V(V) to V(IV) or possibly V(III). The stratigraphic association of vanadiferous and phosphatic rocks reflects temporal and spatial shifts in bottom water chemistry from suboxic (phosphate concentrated) to more reducing (euxinic?) conditions that favor vanadium accumulation. During diagenesis some vanadium-organic complexes migrate with petroleum out of carbonaceous rocks, but significant amounts of vanadium are retained in refractory organic matter or clay minerals. As carbon in the rock evolves toward graphite during metamorphism, vanadium is incorporated into silicate minerals. ?? 1991.

Thymic cytoarchitecture changes in mice exposed to vanadium.

PubMed

Ustarroz-Cano, Martha; Garcia-Pelaez, Isabel; Cervantes-Yepez, Silvana; Lopez-Valdez, Nelly; Fortoul, Teresa I

2017-12-01

The thymus is a vital immune system organ wherein selection of T-lymphocytes occurs in a process regulated by dendritic and epithelial thymic cells. Previously, we have reported that in a mouse model of vanadium inhalation, a decrease in CD11c dendritic cells was observed. In the present study, we report on a thymic cortex-medulla distribution distortion in these hosts due to apparent effects of the inhaled vanadium on cytokeratin-5 (K5 + ) epithelial cells in the same mouse model - after 1, 2, and 4 weeks of exposure - by immunohistochemistry. These cells - together with dendritic cells - eliminate autoreactive T-cell clones and regulate the production of regulatory T-cells in situ. Because both cell types are involved in the negative selection of autoreactive clones, a potential for an increase in development of autoimmune conditions could be a possible consequence among individuals who might be exposed often to vanadium in air pollution, including dwellers of highly polluted cities with elevated levels of particulate matter onto which vanadium is often adsorbed.

The structural studies of vanadium substituted lithium-bismuth-boro-tellurite glass

NASA Astrophysics Data System (ADS)

Madhu, A.; Eraiah, B.

2018-05-01

The structural studies of vanadium substituted lithium-bismuth-boro-tellurite glass is successfully prepared and certain analysis like XRD,FTIR,DTA/TGA with density, molar volume are done. The amorphous phase has been identified based on X-ray diffraction analysis. The vanadium oxide plays the role as a glass-modifier and influences on BO3 ↔ BO4 conversion. The observed nonlinear variation in Tg with vanadium oxide increase, it reflects structural changes. The nonlinear variation of density and molar volume can be attributed to vanadium oxide incorporation have increased the number of Non-bridging oxygen (NBO'S).

Geochemistry of vanadium (V) in Chinese coals.

PubMed

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.

METHOD OF JOINING CARBIDES TO BASE METALS

DOEpatents

Krikorian, N.H.; Farr, J.D.; Witteman, W.G.

1962-02-13

A method is described for joining a refractory metal carbide such as UC or ZrC to a refractory metal base such as Ta or Nb. The method comprises carburizing the surface of the metal base and then sintering the base and carbide at temperatures of about 2000 deg C in a non-oxidizing atmosphere, the base and carbide being held in contact during the sintering step. To reduce the sintering temperature and time, a sintering aid such as iron, nickel, or cobait is added to the carbide, not to exceed 5 wt%. (AEC)

Consolidation and fabrication techniques for vanadium-20 w/o titanium /TV-20/

NASA Technical Reports Server (NTRS)

Burt, W. R.; Karasek, F. J.; Kramer, W. C.; Mayfield, R. M.; Mc Gowan, R. D.

1968-01-01

Tests of the mechanical properties, fuel compatibility, sodium corrosion and irradiation behavior were made for vanadium and vanadium alloy. Improved methods for consolidation and fabrication of bar, rod, sheet, and high-quality, small diameter, thin-wall tubing of vanadium-20 without titanium are reported.

WE-G-BRD-06: Volumetric Cine MRI (VC-MRI) Estimated Based On Prior Knowledge for On-Board Target Localization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harris, W; Yin, F; Cai, J

Purpose: To develop a technique to generate on-board VC-MRI using patient prior 4D-MRI, motion modeling and on-board 2D-cine MRI for real-time 3D target verification of liver and lung radiotherapy. Methods: The end-expiration phase images of a 4D-MRI acquired during patient simulation are used as patient prior images. Principal component analysis (PCA) is used to extract 3 major respiratory deformation patterns from the Deformation Field Maps (DFMs) generated between end-expiration phase and all other phases. On-board 2D-cine MRI images are acquired in the axial view. The on-board VC-MRI at any instant is considered as a deformation of the prior MRI atmore » the end-expiration phase. The DFM is represented as a linear combination of the 3 major deformation patterns. The coefficients of the deformation patterns are solved by matching the corresponding 2D slice of the estimated VC-MRI with the acquired single 2D-cine MRI. The method was evaluated using both XCAT (a computerized patient model) simulation of lung cancer patients and MRI data from a real liver cancer patient. The 3D-MRI at every phase except end-expiration phase was used to simulate the ground-truth on-board VC-MRI at different instances, and the center-tumor slice was selected to simulate the on-board 2D-cine images. Results: Image subtraction of ground truth with estimated on-board VC-MRI shows fewer differences than image subtraction of ground truth with prior image. Excellent agreement between profiles was achieved. The normalized cross correlation coefficients between the estimated and ground-truth in the axial, coronal and sagittal views for each time step were >= 0.982, 0.905, 0.961 for XCAT data and >= 0.998, 0.911, 0.9541 for patient data. For XCAT data, the maximum-Volume-Percent-Difference between ground-truth and estimated tumor volumes was 1.6% and the maximum-Center-of-Mass-Shift was 0.9 mm. Conclusion: Preliminary studies demonstrated the feasibility to estimate real-time VC-MRI for on

CATALYTIC PROMOTION OF THE ADSORPTION OF VANADIUM ON AN ANIONIC EXCHANGE RESIN

DOEpatents

Bailes, R.H.; Ellis, D.A.

1958-08-26

An improvement in the process for the recovery of vanadium from acidic phosphatic solutions is presented. In this process the vanadium is first oxidized to the pentavaleat state, and is then separated by contacting such solutions with an anion exchange resin whereby adsorption of the complexed pentavalent vanadium is effected. The improvement lies in the fact that adsorp tion of the vanadium complex by the anion exchange resin is promoted and improved by providing fiuoride ions in solution to be contacted.

[Effect of vanadium exposure on neurobehavioral function in workers].

PubMed

Zhu, C W; Liu, Y X; Huang, C J; Gao, W; Hu, G L; Li, J; Zhang, Q; Lan, Y J

2016-02-20

To establish the comprehensive indicators for neurobehavioral function test, and to investigate the possible adverse effect of long-time vanadium exposure on neurobehavioral function and its features in workers. From July to November, 2012, The Neurobehavioral Core Test Battery(NCTB) recommended by WHO was used to conduct tests for 128 workers in vanadium exposure group and 128 workers in control group. The t-test and analysis of covariance were used to compare the differences in each indicator in NCTB between different populations, and the principal component analysis was used to establish the comprehensive neurobehavioral index(NBI) and investigate the effect of vanadium on workers' neurobehavioral function. The vanadium exposure group had significantly lower visual retention score(6.9±1.9), digit span(order) score(8.9±2.9), lifting and turning dexterity(the non-handed hand) score (14.1±3.6), pursuit aiming test(the number of correct dots) score(65.7±24.8), and digit symbol score (31.1±15.0) than the control group (8.2±1.3, 9.4±2.7, 15.5±3.0, 76.5±23.8, and 33.7±9.5)(all P<0.05). The vanadium exposure group also had a significantly lower NBI than the control group(-0.167±0.602 vs 0.168±0.564, P<0.05). Long-term vanadium exposure can influence the workers' neurobehavioral function, with the manifestations of decreased hearing and visual memory, movement velocity, accuracy, and coordination.

Theoretical analysis and experiments for the carburization of vanadium-bearing hot metal

NASA Astrophysics Data System (ADS)

Ma, Deng; Wu, Wei; Dai, Shifan; Liu, Zhibin

2018-01-01

In this study, the feasibility of the carburization of vanadium-bearing hot metal was first investigated by thermodynamic analysis. Next, three carburizers, namely a low-nitrogen carburizer, anthracite, and coke, were used for carburization of 500 g of vanadium-bearing hot metal at 1450 °C, 1500 °C, and 1550 °C, respectively. The carbon increments for the low-nitrogen carburizer, anthracite and coke followed decreasing order in the temperature range from 1450 °C to 1550 °C. Anthracite was the most cost-effective carburizer. Hence, anthracite is used in pilot-scale experiments of the vanadium-bearing hot metal (100 kg and 200 kg). Finally, vanadium extraction experiments of the vanadium-bearing hot metal were carried out in a top-bottom-combined blowing induction furnace. It is proved that the average superheat degree of semi-steel increases from 100 °C to 198 °C by the carburization of vanadium-containing hot metal. Foundation Item: Item Sponsored by National Science Foundation of China (51674092)

Silicon carbide reinforced silicon carbide composite

NASA Technical Reports Server (NTRS)

Lau, Sai-Kwing (Inventor); Calandra, Salvatore J. (Inventor); Ohnsorg, Roger W. (Inventor)

2001-01-01

This invention relates to a process comprising the steps of: a) providing a fiber preform comprising a non-oxide ceramic fiber with at least one coating, the coating comprising a coating element selected from the group consisting of carbon, nitrogen, aluminum and titanium, and the fiber having a degradation temperature of between 1400.degree. C. and 1450.degree. C., b) impregnating the preform with a slurry comprising silicon carbide particles and between 0.1 wt % and 3 wt % added carbon c) providing a cover mix comprising: i) an alloy comprising a metallic infiltrant and the coating element, and ii) a resin, d) placing the cover mix on at least a portion of the surface of the porous silicon carbide body, e) heating the cover mix to a temperature between 1410.degree. C. and 1450.degree. C. to melt the alloy, and f) infiltrating the fiber preform with the melted alloy for a time period of between 15 minutes and 240 minutes, to produce a ceramic fiber reinforced ceramic composite.

Imaging of Vanadium in Microfossils: A New Potential Biosignature

NASA Astrophysics Data System (ADS)

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.

Accelerating volumetric cine MRI (VC-MRI) using undersampling for real-time 3D target localization/tracking in radiation therapy: a feasibility study

NASA Astrophysics Data System (ADS)

Harris, Wendy; Yin, Fang-Fang; Wang, Chunhao; Zhang, You; Cai, Jing; Ren, Lei

2018-01-01

Purpose. To accelerate volumetric cine MRI (VC-MRI) using undersampled 2D-cine MRI to provide real-time 3D guidance for gating/target tracking in radiotherapy. Methods. 4D-MRI is acquired during patient simulation. One phase of the prior 4D-MRI is selected as the prior images, designated as MRIprior. The on-board VC-MRI at each time-step is considered a deformation of the MRIprior. The deformation field map is represented as a linear combination of the motion components extracted by principal component analysis from the prior 4D-MRI. The weighting coefficients of the motion components are solved by matching the corresponding 2D-slice of the VC-MRI with the on-board undersampled 2D-cine MRI acquired. Undersampled Cartesian and radial k-space acquisition strategies were investigated. The effects of k-space sampling percentage (SP) and distribution, tumor sizes and noise on the VC-MRI estimation were studied. The VC-MRI estimation was evaluated using XCAT simulation of lung cancer patients and data from liver cancer patients. Volume percent difference (VPD) and Center of Mass Shift (COMS) of the tumor volumes and tumor tracking errors were calculated. Results. For XCAT, VPD/COMS were 11.93  ±  2.37%/0.90  ±  0.27 mm and 11.53  ±  1.47%/0.85  ±  0.20 mm among all scenarios with Cartesian sampling (SP  =  10%) and radial sampling (21 spokes, SP  =  5.2%), respectively. When tumor size decreased, higher sampling rate achieved more accurate VC-MRI than lower sampling rate. VC-MRI was robust against noise levels up to SNR  =  20. For patient data, the tumor tracking errors in superior-inferior, anterior-posterior and lateral (LAT) directions were 0.46  ±  0.20 mm, 0.56  ±  0.17 mm and 0.23  ±  0.16 mm, respectively, for Cartesian-based sampling with SP  =  20% and 0.60  ±  0.19 mm, 0.56  ±  0.22 mm and 0.42  ±  0.15 mm, respectively, for

Vanadium proton exchange membrane water electrolyser

NASA Astrophysics Data System (ADS)

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.

A nested case-control study of prenatal vanadium exposure and low birthweight.

PubMed

Jiang, Minmin; Li, Yuanyuan; Zhang, Bin; Zhou, Aifen; Zheng, Tongzhang; Qian, Zhengmin; Du, Xiaofu; Zhou, Yanqiu; Pan, Xinyun; Hu, Jie; Wu, Chuansha; Peng, Yang; Liu, Wenyu; Zhang, Chuncao; Xia, Wei; Xu, Shunqing

2016-09-01

Is prenatal vanadium exposure associated with adverse birth outcomes? The odds of low birthweight (LBW) are increased 2.23-fold in mothers with a urinary vanadium of ≥2.91 μg/g creatinine compared with that in mothers with a urinary vanadium of ≤1.42 μg/g creatinine. Human exposure to vanadium occurs through intake of food, water and polluted air. Vanadium has been suggested to have fetotoxicity and developmental toxicity in animal studies, and epidemiological studies have reported an association between a decrease in birthweight and vanadium exposure estimated from particulate matter. A nested case-control study involving 816 study participants (204 LBW cases and 612 matched controls) was conducted with data from the prospective Healthy Baby Cohort between 2012 and 2014 in the province of Hubei, China. Vanadium concentrations in 816 maternal urine samples collected before delivery [the median gestational age was 39 weeks (range 27-42 weeks)] were measured by inductively coupled plasma mass spectrometry. Information on the infants' birth outcomes was obtained from medical records. Conditional logistic regression was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs). The median urinary vanadium concentration of the cases was much higher than that of the controls (3.04 μg/g creatinine versus 1.93 μg/g creatinine). The results revealed a significant positive trend between the odds of LBW and level of maternal urinary vanadium [relative to the lowest tertile; adjusted OR = 1.69 (95% CI: 0.92, 3.10) for the medium tertile; adjusted OR = 2.23 (95% CI: 1.23, 4.05) for the highest tertile; P-trend = 0.02]. Additionally, the association was not modified by maternal age (P for heterogeneity = 0.70) or infant gender (P for heterogeneity = 0.21). The maternal urine sample was collected before labor, and the maternal urinary vanadium levels measured at one point in time may not accurately reflect the vanadium burden during the entire pregnancy

Surface and Bulk Carbide Transformations in High-Speed Steel

PubMed Central

Godec, M.; Večko Pirtovšek, T.; Šetina Batič, B.; McGuiness, P.; Burja, J.; Podgornik, B.

2015-01-01

We have studied the transformation of carbides in AISI M42 high-speed steels in the temperature window used for forging. The annealing was found to result in the partial transformation of the large, metastable M2C carbides into small, more stable grains of M6C, with an associated change in the crystal orientation. In addition, MC carbides form during the transformation of M2C to M6C. From the high-speed-steel production point of view, it is beneficial to have large, metastable carbides in the cast structure, which later during annealing, before the forging, transform into a structure of polycrystalline carbides. Such carbides can be easily decomposed into several small carbides, which are then randomly distributed in the microstructure. The results also show an interesting difference in the carbide-transformation reactions on the surface versus the bulk of the alloy, which has implications for in-situ studies of bulk phenomena that are based on surface observations. PMID:26537780

Plasma assisted synthesis of vanadium pentoxide nanoplates

NASA Astrophysics Data System (ADS)

Singh, Megha; Sharma, Rabindar Kumar; Kumar, Prabhat; Reddy, G. B.

2015-08-01

In this work, we report the growth of α-V2O5 (orthorhombic) nanoplates on glass substrate using plasma assisted sublimation process (PASP) and Nickel as catalyst. 100 nm thick film of Ni is deposited over glass substrate by thermal evaporation process. Vanadium oxide nanoplates have been deposited treating vanadium metal foil under high vacuum conditions with oxygen plasma. Vanadium foil is kept at fixed temperature growth of nanoplates of V2O5 to take place. Samples grown have been studied using XPS, XRD and HRTEM to confirm the growth of α-phase of V2O5, which revealed pure single crystal of α- V2O5 in orthorhombic crystallographic plane. Surface morphological studies using SEM and TEM show nanostructured thin film in form of plates. Uniform, vertically aligned randomly oriented nanoplates of V2O5 have been deposited.

Integration and High-Temperature Characterization of Ferroelectric Vanadium-Doped Bismuth Titanate Thin Films on Silicon Carbide

NASA Astrophysics Data System (ADS)

Ekström, Mattias; Khartsev, Sergiy; Östling, Mikael; Zetterling, Carl-Mikael

2017-07-01

4H-SiC electronics can operate at high temperature (HT), e.g., 300°C to 500°C, for extended times. Systems using sensors and amplifiers that operate at HT would benefit from microcontrollers which can also operate at HT. Microcontrollers require nonvolatile memory (NVM) for computer programs. In this work, we demonstrate the possibility of integrating ferroelectric vanadium-doped bismuth titanate (BiTV) thin films on 4H-SiC for HT memory applications, with BiTV ferroelectric capacitors providing memory functionality. Film deposition was achieved by laser ablation on Pt (111)/TiO2/4H-SiC substrates, with magnetron-sputtered Pt used as bottom electrode and thermally evaporated Au as upper contacts. Film characterization by x-ray diffraction analysis revealed predominately (117) orientation. P- E hysteresis loops measured at room temperature showed maximum 2 P r of 48 μC/cm2, large enough for wide read margins. P- E loops were measurable up to 450°C, with losses limiting measurements above 450°C. The phase-transition temperature was determined to be about 660°C from the discontinuity in dielectric permittivity, close to what is achieved for ceramics. These BiTV ferroelectric capacitors demonstrate potential for use in HT NVM applications for SiC digital electronics.

Vanadium Nitrogenase Reduces CO*

PubMed Central

Lee, Chi Chung; Hu, Yilin; Ribbe, Markus W.

2011-01-01

Vanadium nitrogenase not only reduces dinitrogen to ammonia but also reduces carbon monoxide to ethylene, ethane, and propane. The parallelism between the two reactions suggests a potential link in mechanism and evolution between the carbon and nitrogen cycles on Earth. PMID:20689010

Vanadium Exposure-Induced Neurobehavioral Alterations among Chinese Workers

PubMed Central

Li, Hong; Zhou, Dinglun; Zhang, Qin; Feng, Chengyong; Zheng, Wei; He, Keping; Lan, Yajia

2014-01-01

Vanadium-containing products are manufactured and widely used in the modern industry. Yet the neurobehavioral toxicity due to occupational exposure to vanadium remained elusive. This cross-sectional study was designed to examine the neurotoxic effects of occupational vanadium exposure. A total of 463 vanadium-exposed workers (exposed group) and 251 non-exposed workers (control group) were recruited from a Steel and Iron Group in Sichuan, China. A WHO-recommended neurobehavioral core test battery (NCTB) and event-related auditory evoked potentials test (P300) were used to assess the neurobehavioral functions of all study subjects. A general linear model was used to compare outcome scores between the two groups while controlling for possible confounders. The exposed group showed a statistically significant neurobehavioral alteration more than the control group in the NCTB tests. The exposed workers also exhibited an increased anger-hostility, depression-dejection and fatigue-inertia on the profile of mood states (p<0.05). Performances in the Simple Reaction Time, Digit Span, Benton Visual Retention and Pursuit Aiming were also poorer among exposed workers as compared to unexposed control workers(p<0.05). Some of these poor performances in tests were also significantly related to workers’ exposure duration. P300 latencies were longer in the exposed group than in the control (p<0.05). Longer mean reaction times and more counting errors were also found in the exposed workers (p<0.05). Given the findings of our study and the limitations of neurobehavioral workplace testing, we found evidence of altered neurobehavioral outcomes by occupational exposure to vanadium. PMID:23500660

Silicon Carbide Integrated Circuit Chip

NASA Image and Video Library

2015-02-17

A multilevel interconnect silicon carbide integrated circuit chip with co-fired ceramic package and circuit board recently developed at the NASA GRC Smart Sensors and Electronics Systems Branch for high temperature applications. High temperature silicon carbide electronics and compatible packaging technologies are elements of instrumentation for aerospace engine control and long term inner-solar planet explorations.

A Disposable Alkaline Phosphatase-Based Biosensor for Vanadium Chronoamperometric Determination

PubMed Central

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

Imaging of Vanadium in Microfossils: A New Potential Biosignature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marshall, Craig P.; Marshall, Alison Olcott; Aitken, Jade B.

Being able to distinguish unambiguously 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 non-biological 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; either 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 biologicalmore » 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 diagensis 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. Here, 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 biogenecity of putative microfossil-like structures.« less

Imaging of Vanadium in Microfossils: A New Potential Biosignature

DOE PAGES

Marshall, Craig P.; Marshall, Alison Olcott; Aitken, Jade B.; ...

2017-11-01

Being able to distinguish unambiguously 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 non-biological 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; either 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 biologicalmore » 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 diagensis 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. Here, 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 biogenecity of putative microfossil-like structures.« less

40 CFR 440.30 - Applicability; description of the uranium, radium and vanadium ores subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... vanadium ores are produced; and (b) mills using the acid leach, alkaline leach, or combined acid and alkaline leach process for the extraction of uranium, radium and vanadium. Only vanadium byproduct...

40 CFR 440.30 - Applicability; description of the uranium, radium and vanadium ores subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... vanadium ores are produced; and (b) mills using the acid leach, alkaline leach, or combined acid and alkaline leach process for the extraction of uranium, radium and vanadium. Only vanadium byproduct...

40 CFR 440.30 - Applicability; description of the uranium, radium and vanadium ores subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... vanadium ores are produced; and (b) mills using the acid leach, alkaline leach, or combined acid and alkaline leach process for the extraction of uranium, radium and vanadium. Only vanadium byproduct...

Silicon carbide semiconductor technology for high temperature and radiation environments

NASA Technical Reports Server (NTRS)

Matus, Lawrence G.

1993-01-01

Viewgraphs on silicon carbide semiconductor technology and its potential for enabling electronic devices to function in high temperature and high radiation environments are presented. Topics covered include silicon carbide; sublimation growth of 6H-SiC boules; SiC chemical vapor deposition reaction system; 6H silicon carbide p-n junction diode; silicon carbide MOSFET; and silicon carbide JFET radiation response.

Cobalt Doping of Semiconducting Boron Carbide Using Cobaltocene

DTIC Science & Technology

2007-03-01

COBALT DOPING OF SEMICONDUCTING BORON CARBIDE USING COBALTOCENE THESIS Lonnie Carlson, Major...DOPING OF SEMICONDUCTING BORON CARBIDE USING COBALTOCENE THESIS Presented to the Faculty Department of Engineering Physics Graduate School...DISTRIBUTION UNLIMITED AFIT/GNE/ENP/07-01 COBALT DOPING OF SEMICONDUCTING BORON CARBIDE USING COBALTOCENE Lonnie

Silicon carbide sintered body manufactured from silicon carbide powder containing boron, silicon and carbonaceous additive

NASA Technical Reports Server (NTRS)

Tanaka, Hidehiko

1987-01-01

A silicon carbide powder of a 5-micron grain size is mixed with 0.15 to 0.60 wt% mixture of a boron compound, i.e., boric acid, boron carbide (B4C), silicon boride (SiB4 or SiB6), aluminum boride, etc., and an aluminum compound, i.e., aluminum, aluminum oxide, aluminum hydroxide, aluminum carbide, etc., or aluminum boride (AlB2) alone, in such a proportion that the boron/aluminum atomic ratio in the sintered body becomes 0.05 to 0.25 wt% and 0.05 to 0.40 wt%, respectively, together with a carbonaceous additive to supply enough carbon to convert oxygen accompanying raw materials and additives into carbon monoxide.

Properties of vanadium-loaded iron sorbent after alkali regeneration.

PubMed

Khalid, Muhammad Kamran; Leiviskä, Tiina; Tanskanen, Juha

2017-11-01

The aim of this research was to investigate the regeneration and reuse of a commercial granular iron sorbent (mainly goethite) when used in vanadium removal. A regeneration rate of 3 M NaOH was the highest (85%) achieved, followed by 2 M NaOH (79%) and 1 M NaOH (68%). The breakthrough curves show that the regenerated material can be reused. The BET (Brunauer-Emmett-Teller) surface area increased by 35-38% and the total pore volume increased by 123-130% as a consequence of NaOH treatment. The results indicated that sodium hydroxide could be used for the regeneration of iron sorbent although the regeneration was incomplete. This may be explained by the fact that vanadium diffusion into pores is a significant sorption mechanism in addition to complex formation with surface functional groups. As a consequence, vanadium desorbability from pores is not as effective as the regeneration of surface sites. X-ray photoelectron spectroscopy analyses confirmed a very low vanadium content on the surface of the NaOH-treated iron sorbent.

Breaking the icosahedra in boron carbide

PubMed Central

Xie, Kelvin Y.; An, Qi; Sato, Takanori; Breen, Andrew J.; Ringer, Simon P.; Goddard, William A.; Cairney, Julie M.; Hemker, Kevin J.

2016-01-01

Findings of laser-assisted atom probe tomography experiments on boron carbide elucidate an approach for characterizing the atomic structure and interatomic bonding of molecules associated with extraordinary structural stability. The discovery of crystallographic planes in these boron carbide datasets substantiates that crystallinity is maintained to the point of field evaporation, and characterization of individual ionization events gives unexpected evidence of the destruction of individual icosahedra. Statistical analyses of the ions created during the field evaporation process have been used to deduce relative atomic bond strengths and show that the icosahedra in boron carbide are not as stable as anticipated. Combined with quantum mechanics simulations, this result provides insight into the structural instability and amorphization of boron carbide. The temporal, spatial, and compositional information provided by atom probe tomography makes it a unique platform for elucidating the relative stability and interactions of primary building blocks in hierarchically crystalline materials. PMID:27790982

Direct Electrochemical Preparation of Cobalt, Tungsten, and Tungsten Carbide from Cemented Carbide Scrap

NASA Astrophysics Data System (ADS)

Xiao, Xiangjun; Xi, Xiaoli; Nie, Zuoren; Zhang, Liwen; Ma, Liwen

2017-02-01

A novel process of preparing cobalt, tungsten, and tungsten carbide powders from cemented carbide scrap by molten salt electrolysis has been investigated in this paper. In this experiment, WC-6Co and NaCl-KCl salt were used as sacrificial anode and electrolyte, respectively. The dissolution potential of cobalt and WC was determined by linear sweep voltammetry to be 0 and 0.6 V ( vs Ag/AgCl), respectively. Furthermore, the electrochemical behavior of cobalt and tungsten ions was investigated by a variety of electrochemical techniques. Results of cyclic voltammetry (CV) and square-wave voltammetry show that the cobalt and tungsten ions existed as Co2+ and W2+ on melts, respectively. The effect of applied voltage, electrolysis current, and electrolysis times on the composition of the product was studied. Results showed that pure cobalt powder can be obtained when the electrolysis potential is lower than 0.6 V or during low current and short times. Double-cathode and two-stage electrolysis was utilized for the preparation of cobalt, tungsten carbide, and tungsten powders. Additionally, X-ray diffraction results confirm that the product collected at cathodes 1 and 2 is pure Co and WC, respectively. Pure tungsten powder was obtained after electrolysis of the second part. Scanning electron microscope results show that the diameters of tungsten, tungsten carbide, and cobalt powder are smaller than 100, 200, and 200 nm, respectively.

Vanadium removal from LD converter slag using bacteria and fungi.

PubMed

Mirazimi, S M J; Abbasalipour, Z; Rashchi, F

2015-04-15

Removal of vanadium from Linz-Donawits (LD) converter slag was investigated by means of three different species of microbial systems: Acidithiobacillus thiooxidans (autotrophic bacteria), Pseudomonas putida (heterotrophic bacteria) and Aspergillus niger (fungi). The bioleaching process was carried out in both one-step and two-step process and the leaching efficiencies in both cases were compared. Formation of inorganic and organic acids during the leaching process caused mobilization of vanadium. In order to reduce toxic effects of the metal species on the above mentioned microorganisms, a prolonged adaptation process was performed. Both bacteria, A. thiooxidans and P. putida were able to remove more than 90% of vanadium at slag concentrations of 1-5 g L(-1) after 15 days. Also, the maximum achievable vanadium removal in the fungal system was approximately 92% at a slag concentration of 1 g L(-1) after 22 days. Copyright © 2015 Elsevier Ltd. All rights reserved.

A capture method based on the VC1 domain reveals new binding properties of the human receptor for advanced glycation end products (RAGE).

PubMed

Degani, Genny; Altomare, Alessandra A; Colzani, Mara; Martino, Caterina; Mazzolari, Angelica; Fritz, Guenter; Vistoli, Giulio; Popolo, Laura; Aldini, Giancarlo

2017-04-01

The Advanced Glycation and Lipoxidation End products (AGEs and ALEs) are a heterogeneous class of compounds derived from the non-enzymatic glycation or protein adduction by lipoxidation break-down products. The receptor for AGEs (RAGE) is involved in the progression of chronic diseases based on persistent inflammatory state and oxidative stress. RAGE is a pattern recognition receptor (PRR) and the inhibition of the interaction with its ligands or of the ligand accumulation have a potential therapeutic effect. The N-terminal domain of RAGE, the V domain, is the major site of AGEs binding and is stabilized by the adjacent C1 domain. In this study, we set up an affinity assay relying on the extremely specific biological interaction AGEs ligands have for the VC1 domain. A glycosylated form of VC1, produced in the yeast Pichia pastoris, was attached to magnetic beads and used as insoluble affinity matrix (VC1-resin). The VC1 interaction assay was employed to isolate specific VC1 binding partners from in vitro generated AGE-albumins and modifications were identified/localized by mass spectrometry analysis. Interestingly, this method also led to the isolation of ALEs produced by malondialdehyde treatment of albumins. Computational studies provided a rational-based interpretation of the contacts established by specific modified residues and amino acids of the V domain. The validation of VC1-resin in capturing AGE-albumins from complex biological mixtures such as plasma and milk, may lead to the identification of new RAGE ligands potentially involved in pro-inflammatory and pro-fibrotic responses, independently of their structures or physical properties, and without the use of any covalent derivatization process. In addition, the method can be applied to the identification of antagonists of RAGE-ligand interaction. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

LIQUID PHASE SINTERING OF METALLIC CARBIDES

DOEpatents

Hammond, J.; Sease, J.D.

1964-01-21

An improved method is given for fabricating uranium carbide composites, The method comprises forming a homogeneous mixture of powdered uranium carbide, a uranium intermetallic compound which wets and forms a eutectic with said carbide and has a non-uranium component which has a relatively high vapor pressure at a temperature in the range 1200 to 1500 deg C, and an organic binder, pressing said mixture to a composite of desired green strength, and then vacuum sintering said composite at the eutectic forming temperature for a period sufficient to remove at least a portion of the non-uranium containing component of said eutectic. (AEC)

Electrocatalysis using transition metal carbide and oxide nanocrystals

NASA Astrophysics Data System (ADS)

Regmi, Yagya N.

Carbides are one of the several families of transition metal compounds that are considered economic alternatives to catalysts based on noble metals and their compounds. Phase pure transition metal carbides of group 4-6 metals, in the first three periods, were synthesized using a common eutectic salt flux synthesis method, and their electrocatalytic activities compared under uniform electrochemical conditions. Mo2C showed highest hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) activities among the nine metal carbides investigated, but all other metal carbides also showed substantial activities. All the metal carbides showed remarkable enhancement in catalytic activities as supports, when compared to traditional graphitic carbon as platinum support. Mo2C, the most active transition metal carbide electrocatalyst, was prepared using four different synthesis routes, and the synthesis route dependent activities compared. Bifunctional Mo 2C that is HER as well as oxygen evolution reaction (OER) active, was achieved when the carbide was templated on a multiwalled carbon nanotube using carbothermic reduction method. Bimetallic carbides of Fe, Co, and Ni with Mo or W were prepared using a common carbothermic reduction method. Two different stoichiometries of bimetallic carbides were obtained for each system within a 60 °C temperature window. While the bimetallic carbides showed relatively lower electrocatalytic activities towards HER and ORR in comparison to Mo2C and WC, they revealed remarkably higher OER activities than IrO2 and RuO2, the state-of-the-art OER catalysts. Bimetallic oxides of Fe, Co, and Ni with Mo and W were also prepared using a hydrothermal synthesis method and they also revealed OER activities that are much higher than RuO2 and IrO2. Additionally, the OER activities were dependent on the degree and nature of hydration in the bimetallic oxide crystal lattice, with the completely hydrated, as synthesized, cobalt molybdate and nickel

Vanadium doped tin dioxide as a novel sulfur dioxide sensor.

PubMed

Das, S; Chakraborty, S; Parkash, O; Kumar, D; Bandyopadhyay, S; Samudrala, S K; Sen, A; Maiti, H S

2008-04-15

Considering the short-term exposure limit of SO2 to be 5 ppm, we first time report that semiconductor sensors based on vanadium doped SnO2 can be used for SO2 leak detection because of their good sensitivity towards SO2 at concentrations down to 5 ppm. Such sensors are quite selective in presence of other gases like carbon monoxide, methane and butane. The high sensitivity of vanadium doped tin dioxide towards SO2 may be understood by considering the oxidation of sulfur dioxide to sulfur trioxide on SnO2 surface through redox cycles of vanadium-sulfur-oxygen adsorbed species.

Boron-carbide-aluminum and boron-carbide-reactive metal cermets. [B/sub 4/C-Al

DOEpatents

Halverson, D.C.; Pyzik, A.J.; Aksay, I.A.

1985-05-06

Hard, tough, lighweight boron-carbide-reactive metal composites, particularly boron-carbide-aluminum composites, are produced. These composites have compositions with a plurality of phases. A method is provided, including the steps of wetting and reacting the starting materials, by which the microstructures in the resulting composites can be controllably selected. Starting compositions, reaction temperatures, reaction times, and reaction atmospheres are parameters for controlling the process and resulting compositions. The ceramic phases are homogeneously distributed in the metal phases and adhesive forces at ceramic-metal interfaces are maximized. An initial consolidated step is used to achieve fully dense composites. Microstructures of boron-carbide-aluminum cermets have been produced with modules of rupture exceeding 110 ksi and fracture toughness exceeding 12 ksi..sqrt..in. These composites and methods can be used to form a variety of structural elements.

Deposition method for producing silicon carbide high-temperature semiconductors

DOEpatents

Hsu, George C.; Rohatgi, Naresh K.

1987-01-01

An improved deposition method for producing silicon carbide high-temperature semiconductor material comprising placing a semiconductor substrate composed of silicon carbide in a fluidized bed silicon carbide deposition reactor, fluidizing the bed particles by hydrogen gas in a mildly bubbling mode through a gas distributor and heating the substrate at temperatures around 1200.degree.-1500.degree. C. thereby depositing a layer of silicon carbide on the semiconductor substrate.

Carbide fuels for nuclear thermal propulsion

NASA Astrophysics Data System (ADS)

Matthews, R. B.; Blair, H. T.; Chidester, K. M.; Davidson, K. V.; Stark, W. E.; Storms, E. K.

1991-09-01

A renewed interest in manned exploration of space has revitalized interest in the potential for advancing nuclear rocket technology developed during the 1960's. Carbide fuel performance, melting point, stability, fabricability and compatibility are key technology issues for advanced Nuclear Thermal Propulsion reactors. The Rover fuels development ended with proven carbide fuel forms with demonstrated operating temperatures up to 2700 K for over 100 minutes. The next generation of nuclear rockets will start where the Rover technology ended, but with a more rigorous set of operating requirements including operating lifetime to 10 hours, operating temperatures greater that 3000 K, low fission product release, and compatibility. A brief overview of Rover/NERVA carbide fuel development is presented. A new fuel form with the highest potential combination of operating temperature and lifetime is proposed that consists of a coated uranium carbide fuel sphere with built-in porosity to contain fission products. The particles are dispersed in a fiber reinforced ZrC matrix to increase thermal shock resistance.

Quantitative LIBS analysis of vanadium in samples of hexagonal mesoporous silica catalysts.

PubMed

Pouzar, Miloslav; Kratochvíl, Tomás; Capek, Libor; Smoláková, Lucie; Cernohorský, Tomás; Krejcová, Anna; Hromádko, Ludek

2011-02-15

The method for the analysis of vanadium in hexagonal mesoporous silica (V-HMS) catalysts using Laser Induced Breakdown Spectrometry (LIBS) was suggested. Commercially available LIBS spectrometer was calibrated with the aid of authentic V-HMS samples previously analyzed by ICP OES after microwave digestion. Deposition of the sample on the surface of adhesive tape was adopted as a sample preparation method. Strong matrix effect connected with the catalyst preparation technique (1st vanadium added in the process of HMS synthesis, 2nd already synthesised silica matrix was impregnated by vanadium) was observed. The concentration range of V in the set of nine calibration standards was 1.3-4.5% (w/w). Limit of detection was 0.13% (w/w) and it was calculated as a triple standard deviation from five replicated determinations of vanadium in the real sample with a very low vanadium concentration. Comparable results of LIBS and ED XRF were obtained if the same set of standards was used for calibration of both methods and vanadium was measured in the same type of real samples. LIBS calibration constructed using V-HMS-impregnated samples failed for measuring of V-HMS-synthesized samples. LIBS measurements seem to be strongly influenced with different chemical forms of vanadium in impregnated and synthesised samples. The combination of LIBS and ED XRF is able to provide new information about measured samples (in our case for example about procedure of catalyst preparation). Copyright © 2010 Elsevier B.V. All rights reserved.

Abrasive slurry composition for machining boron carbide

DOEpatents

Duran, E.L.

1984-11-29

An abrasive slurry particularly suited for use in drilling or machining boron carbide consists essentially of a suspension of boron carbide and/or silicon carbide grit in a carrier solution consisting essentially of a dilute solution of alkylaryl polyether alcohol in octyl alcohol. The alkylaryl polyether alcohol functions as a wetting agent which improves the capacity of the octyl alcohol for carrying the grit in suspension, yet without substantially increasing the viscosity of the carrier solution.

Abrasive slurry composition for machining boron carbide

DOEpatents

Duran, Edward L.

1985-01-01

An abrasive slurry particularly suited for use in drilling or machining boron carbide consists essentially of a suspension of boron carbide and/or silicon carbide grit in a carrier solution consisting essentially of a dilute solution of alkylaryl polyether alcohol in octyl alcohol. The alkylaryl polyether alcohol functions as a wetting agent which improves the capacity of the octyl alcohol for carrying the grit in suspension, yet without substantially increasing the viscosity of the carrier solution.

Effect of diet composition on vanadium toxicity for the chick

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berg, L.R.

1966-01-01

Studies to determine the effect of diet composition on the toxicity of 20 ppm added vanadium for the young chick have shown: growth depression of 25-30% with a corn-soybean meal ration but only 3-7% with a corn-herring fish meal diet. Growth depression of 35-40% with a semi-purified sucrose-soybean meal diet and approximately 50% with a diet of sucrose and herring fish meal. Adding graded levels of corn to the sucrose-fish meal ration and fish meal to the corn-soybean meal ration reduced vanadium toxicity. The corn fractions, ash, oil, starch, zein and gluten did not reduce vanadium toxicity. Removing the addedmore » magnesium (300 ppm) and potassium (2000 ppm) from the sucrose-fish meal ration did not affect growth rate or mortality. However removal of these materials from the basal ration increased growth depression due to added vanadium from 43-56% and increased mortality from 10-80%. 4 references, 9 tables.« less

Tungsten carbide encapsulated in nitrogen-doped carbon with iron/cobalt carbides electrocatalyst for oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Zhang, Jie; Chen, Jinwei; Jiang, Yiwu; Zhou, Feilong; Wang, Gang; Wang, Ruilin

2016-12-01

This work presents a type of hybrid catalyst prepared through an environmental and simple method, combining a pyrolysis of transition metal precursors, a nitrogen-containing material, and a tungsten source to achieve a one-pot synthesis of N-doping carbon, tungsten carbides, and iron/cobalt carbides (Fe/Co/WC@NC). The obtained Fe/Co/WC@NC consists of uniform Fe3C and Co3C nanoparticles encapsulated in graphitized carbon with surface nitrogen doping, closely wrapped around a plate-like tungsten carbide (WC) that functions as an efficient oxygen reduction reaction (ORR) catalyst. The introduction of WC is found to promote the ORR activity of Fe/Co-based carbide electrocatalysts, which is attributed to the synergistic catalysts of WC, Fe3C, and Co3C. Results suggest that the composite exhibits comparable electrocatalytic activity, higher durability, and ability for methanol tolerance compared with commercial Pt/C for ORR in alkaline electrolyte. These advantages make Fe/Co/WC@NC a promising ORR electrocatalyst and a cost-effective alternative to Pt/C for practical application as fuel cell.

Rate Dependency of Silver Vanadium Phosphorous Oxide Reduction

NASA Astrophysics Data System (ADS)

Cheng, Po-Jen

2011-12-01

The silver vanadium phosphorus oxide (Ag2VO2PO 4) is a high-capacity and good-compatibility material for the cathode in the battery. Due to their innovative properties, they are used as cathode in lithium batteries. Therefore, when the lithium batteries begin to discharge, the anodes of the cell perform an electrochemical oxidation and release electrons. In the mean time, the cathodes in the cells perform the electrochemical reduction and catch the electrons. For reduction of Ag2VO2PO 4, two silver ions (Ag+) catch two electrons to form silver particles, and the vanadium ions (V5+) catch two electrons to form V3+. It means that four electrons will be released by lithium anode. We call this four electrons discharge as 100% discharge. In my most of the projects, the Ag2VO2PO4 material is tested by differential scanning calorimetry (DSC) to check purity. My study is based on the discharge of batteries, and I focus on the morphology and the intensity of silver particles on the cathode after discharge. Depending on different adjustment of factors, such as discharge time, discharge rate, storage time, storage temperature, I try to investigate the silver intensity, conductivity as a function of DOD (Depth of Discharge). The silver particles could be examined by optical microscope, and scanning electron microscope (SEM). Moreover, I do some x-ray diffraction analysis to quantify the silver particles after discharge. Also, I perform magnetic susceptibility measurement to check the mechanism of the reduction of vanadium ions. Under the research on silver ions and vanadium ions, I will know a big frame of reduction process on silver vanadium phosphorous oxide and the time effect on this cathode material.

40 CFR 440.30 - Applicability; description of the uranium, radium and vanadium ores subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 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 uranium, radium and vanadium ores subcategory. The provisions of this subpart C are applicable to...

Three-dimensional studies of intergranular carbides in austenitic stainless steel.

PubMed

Ochi, Minoru; Kawano, Rika; Maeda, Takuya; Sato, Yukio; Teranishi, Ryo; Hara, Toru; Kikuchi, Masao; Kaneko, Kenji

2017-04-01

A large number of morphological studies of intergranular carbides in steels have always been carried out in two dimensions without considering their dispersion manners. In this article, focused ion beam serial-sectioning tomography was carried out to study the correlation among the grain boundary characteristics, the morphologies and the dispersions of intergranular carbides in 347 austenitic stainless steel. More than hundred intergranular carbides were characterized in three dimensions and finally classified into three different types, two types of carbides probably semi-coherent to one of the neighboring grains with plate-type morphology, and one type of carbides incoherent to both grains with rod-type morphology. In addition, the rod-type carbide was found as the largest number of carbides among three types. Since large numbers of defects, such as misfit dislocations, may be present at the grain boundaries, which can be ideal nucleation sites for intergranular rod-type carbide precipitation. © The Author 2016. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved.For permissions, please e-mail: journals.permissions@oup.com.

Hydrogen Production by Steam Reforming of Natural Gas Over Vanadium-Nickel-Alumina Catalysts.

PubMed

Yoo, Jaekyeong; Park, Seungwon; Song, Ji Hwan; Song, In Kyu

2018-09-01

A series of vanadium-nickel-alumina (xVNA) catalysts were prepared by a single-step sol-gel method with a variation of vanadium content (x, wt%) for use in the hydrogen production by steam reforming of natural gas. The effect of vanadium content on the physicochemical properties and catalytic activities of xVNA catalysts in the steam reforming of natural gas was investigated. It was found that natural gas conversion and hydrogen yield showed volcano-shaped trends with respect to vanadium content. It was also revealed that natural gas conversion and hydrogen yield increased with decreasing nickel crystallite size.

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

PubMed

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.

Synthesis, Characterization, Antioxidant Status, and Toxicity Study of Vanadium-Rutin Complex in Balb/c Mice.

PubMed

Roy, Souvik; Majumdar, Sumana; Singh, Amit Kumar; Ghosh, Balaram; Ghosh, Nilanjan; Manna, Subhadip; Chakraborty, Tania; Mallick, Sougato

2015-08-01

A new trend was developed for the formation of a complex between vanadium and flavonoid derivatives in order to increase the intestinal absorption and to reduce the toxicity of vanadium compounds. The vanadium-rutin complex was characterized by several spectroscopic techniques like ultraviolet (UV)-visible, Fourier transform infrared (FTIR), NMR, mass spectrometry, and microscopic evaluation by scanning electron microscopy. The mononuclear complex was formed by the interaction between vanadium and rutin with 1:2 metal to ligand stoichiometry. Antioxidant activity of the complex was evaluated by 1,1-diphenyl-2 picrylhydrazyl, ferric-reducing power, and 2,2'-azin-obis 3-ethylbenzothiazoline-6-sulphonic acid methods. It was shown that radical scavenging activity and ferric-reducing potential of free rutin was lower as compared with vanadium-rutin complex. The study was also investigated for oral acute toxicity and 28 days repeated oral subacute toxicity study of vanadium-rutin complex in balb/c mice. The vanadium-rutin complex showed mortality at a dose of 120 mg/kg in the balb/c mice. In 28 days repeated oral toxicity study, vanadium-rutin complex was administered to both sex of balb/c mice at dose levels of 90, 45, and 20 ppm, respectively. In addition, subacute toxicity study of vanadium-rutin complex (at 90 ppm dose level) showed increase levels of white blood cell (WBC), total bilirubin, alanine aminotransferase (ALT), alkaline phosphatase (ALP), aspartate aminotransferase (AST), creatinine, and blood urea nitrogen and decrease level of total protein (TP) as compared with control group. Histopathological study of vanadium-rutin showed structural alteration in the liver, kidney, and stomach at 90 ppm dose level. No observed toxic level of vanadium-rutin complex at 20 ppm dose level could be good for further study.

Density Determination and Metallographic Surface Preparation of Electron Beam Melted Ti6Al4V

DTIC Science & Technology

2015-06-02

Electron Microscopy SiC Silicon Carbide Ti6Al4V Titanium-6Aluminum-4Vanadium WRNMMC Walter Reed National Military Medical Center Wd Dry...polishing with silicon carbide ( SiC ) papers and colloidal silica suspension to produce samples with varying surface topographies. Surfaces were...manufacturing process. For titanium alloys, the grinding media typically used is silicon carbide ( SiC ) paper. Table 1 lists grades of SiC papers that are

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

NASA Astrophysics Data System (ADS)

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.

Development, qualification, validation and application of the Ames test using a VITROCELL® VC10® smoke exposure system.

PubMed

Fowler, Kathy; Fields, Wanda; Hargreaves, Victoria; Reeve, Lesley; Bombick, Betsy

2018-01-01

The Ames test has established use in the assessment of potential mutagenicity of tobacco products but has generally been performed using partitioned exposures (e.g. total particulate matter [TPM], gas vapor phase [GVP]) rather than whole smoke (WS). The VITROCELL ® VC10 ® smoke exposure system offers multiple platforms for air liquid interface (ALI), or air agar interface (AAI) in the case of the Ames test exposure to mimic in vivo -like conditions for assessing the toxicological impact of fresh WS in in vitro assays. The goals of this study were to 1) qualify the VITROCELL ® VC10 ® to demonstrate functionality of the system, 2) develop and validate the Ames test following WS exposure with the VITROCELL ® VC10 ® and 3) assess the ability of the Ames test to differentiate between a reference combustible product (3R4F Kentucky reference cigarette) and a primarily tobacco heating product (Eclipse). Based on critical function assessments, the VITROCELL ® VC10 ® was demonstrated to be fit for the purpose of consistent generation of WS. Assay validation was conducted for 5 bacterial strains (TA97, TA98, TA100, TA1535 and TA102) and reproducible exposure-related changes in revertants were observed for TA98 and TA100 in the presence of rat liver S-9 following exposure to 3R4F WS. In the comparative studies, exposure-related changes in in vitro mutagenicity following exposure of TA98 and TA100 in the presence of S9 to both 3R4F and Eclipse WS were observed, with the response for Eclipse being significantly less than that for 3R4F (p < 0.001) which is consistent with the fewer chemical constituents liberated by primarily-heating the product.

Silicon Carbide Capacitive High Temperature MEMS Strain Transducer

DTIC Science & Technology

2012-03-22

SILICON CARBIDE CAPACITIVE HIGH TEMPURATURE MEMS STRAIN TRANSDUCER THESIS Richard P. Weisenberger, DR01, USAF AFIT/GE/ENG...declared a work of the U.S. Government and is not subject to copyright protection in the United States AFIT/GE/ENG/12-43 SILICON CARBIDE CAPACITIVE...STATEMENT A. APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED AFIT/GE/ENG/12-43 SILICON CARBIDE CAPACITIVE IDGH TEMPURATURE MEMS STRAIN TRANSDUCER

Characterization of boron carbide with an electron microprobe

NASA Technical Reports Server (NTRS)

Matteudi, G.; Ruste, J.

1983-01-01

Within the framework of a study of heterogeneous materials (Matteudi et al., 1971: Matteudi and Verchery, 1972) thin deposits of boron carbide were characterized. Experiments using an electronic probe microanalyzer to analyze solid boron carbide or boron carbide in the form of thick deposits are described. Quantitative results on boron and carbon are very close to those obtained when applying the Monte Carlo-type correction calculations.

Preparation and electrocatalytic activity of tungsten carbide and titania nanocomposite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Sujuan; Shi, Binbin; Yao, Guoxing

2011-10-15

Graphical abstract: The electrocatalytic activity of tungsten carbide and titania nanocomposite is related to the structure, crystal phase and chemical components of the nanocomposite, and is also affected by the property of electrolyte. A synergistic effect exists between tungsten carbide and titania of the composite. Highlights: {yields} Electrocatalytic activity of tungsten carbide and titania nanocomposite with core-shell structure. {yields} Activity is related to the structure, crystal phase and chemical component of the nanocomposite. {yields} The property of electrolyte affects the electrocatalytic activity. {yields} A synergistic effect exists between tungsten carbide and titania of the composite. -- Abstract: Tungsten carbide andmore » titania nanocomposite was prepared by combining a reduced-carbonized approach with a mechanochemical approach. The samples were characterized by X-ray diffraction, transmission electron microscope under scanning mode and X-ray energy dispersion spectrum. The results show that the crystal phases of the samples are composed of anatase, rutile, nonstoichiometry titanium oxide, monotungsten carbide, bitungsten carbide and nonstoichiometry tungsten carbide, and they can be controlled by adjusting the parameters of the reduced-carbonized approach; tungsten carbide particles decorate on the surface of titania support, the diameter of tungsten carbide particle is smaller than 20 nm and that of titania is around 100 nm; the chemical components of the samples are Ti, O, W and C. The electrocatalytic activity of the samples was measured by a cyclic voltammetry with three electrodes. The results indicate that the electrocatalytic activities of the samples are related to their crystal phases and the property of electrolyte in aqueous solution. A synergistic effect between titania and tungsten carbide is reported for the first time.« less

Boron carbide nanowires: Synthesis and characterization

NASA Astrophysics Data System (ADS)

Guan, Zhe

Bulk boron carbide has been widely used in ballistic armored vest and the property characterization has been heavily focused on mechanical properties. Even though boron carbides have also been projected as a promising class of high temperature thermoelectric materials for energy harvesting, the research has been limited in this field. Since the thermal conductivity of bulk boron carbide is still relatively high, there is a great opportunity to take advantage of the nano effect to further reduce it for better thermoelectric performance. This dissertation work aims to explore whether improved thermoelectric performance can be found in boron carbide nanowires compared with their bulk counterparts. This dissertation work consists of four main parts. (1) Synthesis of boron carbide nanowires. Boron carbide nanowires were synthesized by co-pyrolysis of diborane and methane at low temperatures (with 879 °C as the lowest) in a home-built low pressure chemical vapor deposition (LPCVD) system. The CVD-based method is energy efficient and cost effective. The as-synthesized nanowires were characterized by electron microscopy extensively. The transmission electron microscopy (TEM) results show the nanowires are single crystalline with planar defects. Depending on the geometrical relationship between the preferred growth direction of the nanowire and the orientation of the defects, the as-synthesized nanowires could be further divided into two categories: transverse fault (TF) nanowires grow normal to the defect plane, while axial fault (AF) ones grow within the defect plane. (2) Understanding the growth mechanism of as-synthesized boron carbide nanowires. The growth mechanism can be generally considered as the famous vapor-liquid-solid (VLS) mechanism. TF and AF nanowires were found to be guided by Ni-B catalysts of two phases. A TF nanowire is lead by a hexagonal phase catalyst, which was proved to be in a liquid state during reaction. While an AF nanowires is catalyzed by a

Amphiphilic block copolymer membrane for vanadium redox flow battery

NASA Astrophysics Data System (ADS)

Wang, Fei; Sylvia, James M.; Jacob, Monsy M.; Peramunage, Dharmasena

2013-11-01

An amphiphilic block copolymer comprised of hydrophobic polyaryletherketone (PAEK) and hydrophilic sulfonated polyaryletherketone (SPAEK) blocks has been synthesized and characterized. A membrane prepared from the block copolymer is used as the separator in a single cell vanadium redox flow battery (VRB). The proton conductivity, mechanical property, VO2+ permeability and single VRB cell performance of this block copolymer membrane are investigated and compared to Nafion™ 117. The block copolymer membrane showed significantly improved vanadium ion selectivity, higher mechanical strength and lower conductivity than Nafion™ 117. The VRB containing the block copolymer membrane exhibits higher coulombic efficiency and similar energy efficiency compared to a VRB using Nafion™ 117. The better vanadium ion selectivity of the block copolymer membrane has led to a much smaller capacity loss during 50 charge-discharge cycles for the VRB.

Insulating phases of vanadium dioxide are Mott-Hubbard insulators

DOE PAGES

Huffman, T. J.; Hendriks, C.; Walter, E. J.; ...

2017-02-15

Here, we present comprehensive broadband optical spectroscopy data on two insulating phases of vanadium dioxide (VO 2): monoclinic M 2 and triclinic. The main result of our work is that the energy gap and the electronic structure are essentially unaltered by the first-order structural phase transition between the M 2 and triclinic phases. Moreover, the optical interband features in the M 2 and triclinic phases are remarkably similar to those observed in the well-studied monoclinic M 1 insulating phase of VO 2. As the energy gap is insensitive to the different lattice structures of the three insulating phases, we rulemore » out vanadium-vanadium pairing (the Peierls component) as the dominant contributor to the opening of the gap. Rather, the energy gap arises primarily from intra-atomic Coulomb correlations.« less

The Influence of Vanadium on Ferrite and Bainite Formation in a Medium Carbon Steel

NASA Astrophysics Data System (ADS)

Sourmail, T.; Garcia-Mateo, C.; Caballero, F. G.; Cazottes, S.; Epicier, T.; Danoix, F.; Milbourn, D.

2017-09-01

The influence of vanadium additions on transformation kinetics has been investigated in a medium carbon forging steel. Using dilatometry to track transformation during continuous cooling or isothermal transformation, the impact of vanadium on both ferrite-pearlite and bainite has been quantified. Transmission electron microscopy and atom probe tomography have been used to establish whether vanadium was present in solid solution, or as clusters and precipitates. The results show that vanadium in solid solution has a pronounced retarding influence on ferrite-pearlite formation and that, unlike in the case of niobium, this effect can be exploited even during relatively slow cooling. The influence on bainite transformation was found to depend on temperature; an explanation in terms of the effect of vanadium on heterogeneous nucleation is tentatively proposed.

Tungsten carbide: Crystals by the ton

NASA Astrophysics Data System (ADS)

Smith, E. N.

1988-06-01

A comparison is made of the conventional process of making tungsten carbide by carburizing tungsten powder and the Macro Process wherein the tungsten carbide is formed directly from the ore concentrate by an exothermic reaction of ingredients causing a simultaneous reduction and carburization. Tons of tungsten monocarbide crystals are formed in a very rapid reaction. The process is unique in that it is self regulating and produces a tungsten carbide compound with the correct stoichiometry. The high purity with respect to oxygen and nitrogen is achieved because the reactions occur beneath the molten metal. The morphology and hardness of these crystals has been studied by various investigators and reported in the listed references.

Fabrication of thorium bearing carbide fuels

DOEpatents

Gutierrez, Rueben L.; Herbst, Richard J.; Johnson, Karl W. R.

1981-01-01

Thorium-uranium carbide and thorium-plutonium carbide fuel pellets have been fabricated by the carbothermic reduction process. Temperatures of 1750.degree. C. and 2000.degree. C. were used during the reduction cycle. Sintering temperatures of 1800.degree. C. and 2000.degree. C. were used to prepare fuel pellet densities of 87% and >94% of theoretical, respectively. The process allows the fabrication of kilogram quantities of fuel with good reproducibility of chemicals and phase composition. Methods employing liquid techniques that form carbide microspheres or alloying-techniques which form alloys of thorium-uranium or thorium-plutonium suffer from limitation on the quantities processed of because of criticality concerns and lack of precise control of process conditions, respectively.

Manufacture of silicon carbide using solar energy

DOEpatents

Glatzmaier, Gregory C.

1992-01-01

A method is described for producing silicon carbide particles using solar energy. The method is efficient and avoids the need for use of electrical energy to heat the reactants. Finely divided silica and carbon are admixed and placed in a solar-heated reaction chamber for a time sufficient to cause a reaction between the ingredients to form silicon carbide of very small particle size. No grinding of silicon carbide is required to obtain small particles. The method may be carried out as a batch process or as a continuous process.

Effects of vanadium ion implantation on microstructure, mechanical and tribological properties of TiN coatings

NASA Astrophysics Data System (ADS)

Deng, Bin; Tao, Ye; Guo, Deliang

2012-09-01

TiN coatings were deposited on the substrates of cemented carbide (WC-TiC-Co) by Magnetic Filter Arc Ion Plating (MFAIP) and then implanted with vanadium through Metal Vacuum Vapor Arc (MEVVA) ion source with the doses of 1 × 1017 and 5 × 1017 ions/cm2 at 40 kV. The microstructures and chemical compositions of the V-implanted TiN coatings were investigated using Glancing Incidence X-ray Diffraction (GIXRD) and X-ray Photoelectron Spectroscopy (XPS), together with the mechanical and tribological properties of coatings were characterized using nano-indentation and ball-on-disk tribometer. It was found that the diffraction peaks of the V-implanted TiN coatings at the doses of 5 × 1017 ions/cm2 shifted to higher angles and became broader. The hardness and elastic modulus of TiN coatings increased after V ion implantation. The wear mechanism for both un-implanted and V-implanted TiN coatings against GCr15 steel ball was adhesive wear, and the V-implanted TiN coatings had a lower friction coefficient as well as a better wear resistance

Mechanical Testing of Silicon Carbide on MISSE-7

DTIC Science & Technology

2012-07-15

JS) ii Abstract Silicon carbide ( SiC ) mechanical test specimens were included on the second Optical and Reflector Materials Experiment (ORMatE II...2. Vendor 2 EFS Weibull Results (normalized to Extra Disks Weibull parameters) 12 1. Introduction Silicon carbide ( SiC ) mechanical test...AEROSPACE REPORT NO ATR-2012(8921)-5 Mechanical Testing of Silicon Carbide on MISSE-7 Jul> 15. 2012 David B. Witkin Space Materials Laboratory

Titanium Carbide Bipolar Plate for Electrochemical Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaConti, Anthony B.; Griffith, Arthur E.; Cropley, Cecelia C.

Titanium carbide comprises a corrosion resistant, electrically conductive, non-porous bipolar plate for use in an electrochemical device. The process involves blending titanium carbide powder with a suitable binder material, and molding the mixture, at an elevated temperature and pressure.

Tribological properties of sintered polycrystalline and single crystal silicon carbide

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Buckley, D. H.; Srinivasan, M.

1982-01-01

Tribological studies and X-ray photoelectron spectroscopy analyses were conducted with sintered polycrystalline and single crystal silicon carbide surfaces in sliding contact with iron at various temperatures to 1500 C in a vacuum of 30 nPa. The results indicate that there is a significant temperature influence on both the friction properties and the surface chemistry of silicon carbide. The main contaminants on the as received sintered polycrystalline silicon carbide surfaces are adsorbed carbon, oxygen, graphite, and silicon dioxide. The surface revealed a low coefficient of friction. This is due to the presence of the graphite on the surface. At temperatures of 400 to 600 C graphite and copious amount of silicon dioxide were observed on the polycrystalline silicon carbide surface in addition to silicon carbide. At 800 C, the amount of the silicon dioxide decreased rapidly and the silicon carbide type silicon and carbon peaks were at a maximum intensity in the XPS spectra. The coefficients of friction were high in the temperature range 400 to 800 C. Small amounts of carbon and oxygen contaminants were observed on the as received single crystal silicon carbide surface below 250 C. Silicon carbide type silicon and carbon peaks were seen on the silicon carbide in addition to very small amount of graphite and silicon dioxide at temperatures of 450 to 800 C.

A comparative assessment of the acute inhalation toxicity of vanadium compounds.

PubMed

Rajendran, N; Seagrave, J C; Plunkett, L M; MacGregor, J A

2016-11-01

Vanadium compounds have become important in industrial processes, resulting in workplace exposure potential and are present in ambient air as a result of fossil fuel combustion. A series of acute nose-only inhalation toxicity studies was conducted in both rats and mice in order to obtain comparative data on the acute toxicity potential of compounds used commercially. V 2 O 3 , V 2 O 4 , and V 2 O 5 , which have different oxidation states (+3, +4, +5, respectively), were delivered as micronized powders; the highly water-soluble and hygroscopic VOSO 4 (+4) could not be micronized and was instead delivered as a liquid aerosol from an aqueous solution. V 2 O 5 was the most acutely toxic micronized powder in both species. Despite its lower overall percentage vanadium content, a liquid aerosol of VOSO 4 was more toxic than the V 2 O 5 particles in mice, but not in rats. These data suggest that an interaction of characteristics, i.e., bioavailability, solubility and oxidation state, as well as species sensitivity, likely affect the toxicity potential of vanadium compounds. Based on clinical observations and gross necropsy findings, the lung appeared to be the target organ for all compounds. The level of hazard posed will depend on the specific chemical form of the vanadium. Future work to define the inhalation toxicity potential of vanadium compounds of various oxidation states after repeated exposures will be important in understanding how the physico-chemical and biological characteristics of specific vanadium compounds interact to affect toxicity potential and the potential risks posed to human health.

Tribology of carbide derived carbon films synthesized on tungsten carbide

NASA Astrophysics Data System (ADS)

Tlustochowicz, Marcin

Tribologically advantageous films of carbide derived carbon (CDC) have been successfully synthesized on binderless tungsten carbide manufactured using the plasma pressure compaction (P2CRTM) technology. In order to produce the CDC films, tungsten carbide samples were reacted with chlorine containing gas mixtures at temperatures ranging from 800°C to 1000°C in a sealed tube furnace. Some of the treated samples were later dechlorinated by an 800°C hydrogenation treatment. Detailed mechanical and structural characterizations of the CDC films and sliding contact surfaces were done using a series of analytical techniques and their results were correlated with the friction and wear behavior of the CDC films in various tribosystems, including CDC-steel, CDC-WC, CDC-Si3N4 and CDC-CDC. Optimum synthesis and treatment conditions were determined for use in two specific environments: moderately humid air and dry nitrogen. It was found that CDC films first synthesized at 1000°C and then hydrogen post-treated at 800°C performed best in air with friction coefficient values as low as 0.11. However, for dry nitrogen applications, no dechlorination was necessary and both hydrogenated and as-synthesized CDC films exhibited friction coefficients of approximately 0.03. A model of tribological behavior of CDC has been proposed that takes into consideration the tribo-oxidation of counterface material, the capillary forces from adsorbed water vapor, the carbon-based tribofilm formation, and the lubrication effect of both chlorine and hydrogen.

Process for making silicon carbide reinforced silicon carbide composite

NASA Technical Reports Server (NTRS)

Lau, Sai-Kwing (Inventor); Calandra, Salavatore J. (Inventor); Ohnsorg, Roger W. (Inventor)

1998-01-01

A process comprising the steps of: a) providing a fiber preform comprising a non-oxide ceramic fiber with at least one coating, the coating comprising a coating element selected from the group consisting of carbon, nitrogen, aluminum and titanium, and the fiber having a degradation temperature of between 1400.degree. C. and 1450.degree. C., b) impregnating the preform with a slurry comprising silicon carbide particles and between 0.1 wt % and 3 wt % added carbon c) providing a cover mix comprising: i) an alloy comprising a metallic infiltrant and the coating element, and ii) a resin, d) placing the cover mix on at least a portion of the surface of the porous silicon carbide body, e) heating the cover mix to a temperature between 1410.degree. C. and 1450.degree. C. to melt the alloy, and f) infiltrating the fiber preform with the melted alloy for a time period of between 15 minutes and 240 minutes, to produce a ceramic fiber reinforced ceramic composite.

40 CFR 440.80 - Applicability; description of the vanadium ore subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... vanadium ore subcategory. 440.80 Section 440.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) ORE MINING AND DRESSING POINT SOURCE CATEGORY Vanadium Ore Subcategory (Mined Alone and Not as a Byproduct) § 440.80 Applicability; description of the...

40 CFR 440.80 - Applicability; description of the vanadium ore subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... vanadium ore subcategory. 440.80 Section 440.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) ORE MINING AND DRESSING POINT SOURCE CATEGORY Vanadium Ore Subcategory (Mined Alone and Not as a Byproduct) § 440.80 Applicability; description of the...

40 CFR 440.80 - Applicability; description of the vanadium ore subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... vanadium ore subcategory. 440.80 Section 440.80 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS (CONTINUED) ORE MINING AND DRESSING POINT SOURCE CATEGORY Vanadium Ore Subcategory (Mined Alone and Not as a Byproduct) § 440.80 Applicability; description of the...

Spectrophotometric determination of vanadium and its application to gas-turbine fuel-oils.

PubMed

Banerjee, S; Sinha, B P; Dutta, R K

1975-08-01

A very sensitive spectrophotometric method for the determination of vanadium in furnace oils is described. The intense indigo-blue colour developed by the reaction of vanadium with tannin and thioglycollic acid is measured at a wavelength of 600 nm at pH 4 and obeys Beer's law between 0.5 and 5 ppm vanadium. The method is applicable to gas-turbine fuel-oil and special navy fuel-oils. The common mineral constituents usually present in such oils do not interfere.

[Interaction Between Occupational Vanadium Exposure and hsp70-hom on Neurobehavioral Function].

PubMed

Zhang, Qin; Liu, Yun-xing; Cui, Li; Li, Shun-pin; Gao, Wei; Hu, Gao-lin; Zhang, Zu-hui; Lan, Ya-jia

2016-01-01

In determine the effect of heat shock protein 70-hom gene (hsp70-hom) polymorphism on the neurobehavioral function of workers exposed to vanadium. Workers from the vanadium products and chemical industry were recruited by cluster sampling. Demographic data and exposure information were collected using a questionnaire. Neurobehavioral function was assessed by Neurobehavioral Core Test Battery. The hsp70-hom genotype was detected by restricted fragment length polymorphism-polymerase chain reaction (RFLP-PCR). A neurobehavioral index (NBI) was formulated through principal component analysis. Workers with a T/C genotype had worse performance in average reaction time, visual retention, digital span (backward), Santa Ana aiming (non-habitual hand), pursuit aiming (right points, total points), digit symbol and NBI score than others (P < 0.05). The relative risk of abnormal NBI score of the workers with a T/C genotype was 1.748 fold of those with a T/T genotype. The relative risk of abnormal.NBI score of the workers exposed to vanadium was 3.048 fold of controls (P < 0.05). But after adjustment with age and education, only vanadium exposure appeared with a significant effect on NBI score. When gene polymorphism and vanadium exposure coexisted, the effect of vanadium on neurobehavioral function was attenuated, but the influence of T/C genotype increased Codds ratio (OR = 4.577, P < 0.05). After adjustment with age and education, the OR of T/C genotype further increased to 7.777 (P < 0.05). Vanadium exposure and T/C genotype had.a bio-interaction effect on NBI score Crelative excess risk due to interaction (RERI) = 4.12, attributable proportion (AP) = 0.7, synergy index (S) = 6.45]. After adjustment with age and education, the RERI became 2.49 and the AP became 0.75, but no coefficient of interaction was produced. Priorities of occupational protection should be given to vanadium-exposed workers with a hsp70-hom T/C genotype and low education level.

Titanium carbide bipolar plate for electrochemical devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaConti, Anthony B.; Griffith, Arthur E.; Cropley, Cecelia C.

A corrosion resistant, electrically conductive, non-porous bipolar plate is made from titanium carbide for use in an eletrochemical device. The process involves blending titanium carbide powder with a suitable binder material, and molding the mixture, at an elevated temperature and pressure.

Natural precursor based hydrothermal synthesis of sodium carbide for reactor applications

NASA Astrophysics Data System (ADS)

Swapna, M. S.; Saritha Devi, H. V.; Sebastian, Riya; Ambadas, G.; Sankararaman, S.

2017-12-01

Carbides are a class of materials with high mechanical strength and refractory nature which finds a wide range of applications in industries and nuclear reactors. The existing synthesis methods of all types of carbides have problems in terms of use of toxic chemical precursors, high-cost, etc. Sodium carbide (Na2C2) which is an alkali metal carbide is the least explored one and also that there is no report of low-cost and low-temperature synthesis of sodium carbide using the eco-friendly, easily available natural precursors. In the present work, we report a simple low-cost, non-toxic hydrothermal synthesis of refractory sodium carbide using the natural precursor—Pandanus. The formation of sodium carbide along with boron carbide is evidenced by the structural and morphological characterizations. The sample thus synthesized is subjected to field emission scanning electron microscopy (FESEM), x-ray powder diffraction (XRD), ultraviolet (UV)—visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), Raman, and photoluminescent (PL) spectroscopic techniques.

The presence of vanadium in groundwater of southeastern extreme the pampean region Argentina Relationship with other chemical elements.

PubMed

Fiorentino, Carmen E; Paoloni, Juan D; Sequeira, Mario E; Arosteguy, Pedro

2007-08-15

Changes in the quality of groundwater resources are related to the presence and concentration of contaminants, especially trace elements such as arsenic, boron, fluoride and vanadium. Vanadium is a rare element naturally abundant, generally found in combination with other elements. Vanadium pentoxide is known to have aneugenic effects. Thus, a study was carried out to assess the presence of vanadium in the groundwater of the southeastern pampean region of Argentina, which constitutes the main water supply for the local population. Statistical and correlational analyses were applied to identify possible interrelationships between vanadium and another chemical elements. Vanadium was found in all groundwater samples. The minimum and maximum vanadium concentrations found were 0.05 mg/l and 2.47 mg/l, respectively. Vanadium is significantly correlated with other trace elements such as arsenic, fluoride and boron. The interrelationship between vanadium and the presence of volcanic glass in sediments is not significant as expected.

The Design and Realization of Radio Telescope Control Software in Windows XP System with VC++

NASA Astrophysics Data System (ADS)

Zhao, Rong-Bing; Aili, Yu; Zhang, Jin; Yu, Yun

2007-03-01

The main function of the radio telescope control software is to drive the radio telescope to track the target accurately. The design of radio telescope control software is based on Windows XP system with VC++. The functions of the software, communication mode and the user interface is introduced in this article.

Investigation on the fates of vanadium and nickel during co-gasification of petroleum coke with biomass.

PubMed

Li, Jiazhou; Wang, Xiaoyu; Wang, Bing; Zhao, Jiantao; Fang, Yitian

2018-06-01

This study investigates the volatilization behaviors and mineral transformation of vanadium and nickel during co-gasification of petroleum coke with biomass. Moreover, the evolution of occurrence modes of vanadium and nickel was also determined by the method of sequential chemical extraction. The results show that the volatilities of vanadium and nickel in petroleum coke have a certain level of growth with an increase in the temperature. With the addition of biomass, their volatilities both show an obvious decrease. Organic matter and stable forms are the dominant chemical forms of vanadium and nickel. After gasification, organic-bound vanadium and nickel decompose completely and convert into other chemical forms. The crystalline phases of vanadium trioxide, coulsonite, nickel sulfide, and elemental nickel are clearly present in petroleum coke and biomass gasification ashes. When the addition of biomass reaches 60 wt%, the diffraction peaks of orthovanadate are found while that of vanadium trioxide disappear. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hydrophilic Channel Alignment of Perfluoronated Sulfonic-Acid Ionomers for Vanadium Redox Flow Batteries.

PubMed

So, Soonyong; Cha, Min Suc; Jo, Sang-Woo; Kim, Tae-Ho; Lee, Jang Yong; Hong, Young Taik

2018-06-13

It is known that uniaxially drawn perfluoronated sulfonic-acid ionomers (PFSAs) show diffusion anisotropy because of the aligned water channels along the deformation direction. We apply the uniaxially stretched membranes to vanadium redox flow batteries (VRFBs) to suppress the permeation of active species, vanadium ions through the transverse directions. The aligned water channels render much lower vanadium permeability, resulting in higher Coulombic efficiency (>98%) and longer self-discharge time (>250 h). Similar to vanadium ions, proton conduction through the membranes also decreases as the stretching ratio increases, but the thinned membranes show the enhanced voltage and energy efficiencies over the range of current density, 50-100 mA/cm 2 . Hydrophilic channel alignment of PFSAs is also beneficial for long-term cycling of VRFBs in terms of capacity retention and cell performances. This simple pretreatment of membranes offers an effective and facile way to overcome high vanadium permeability of PFSAs for VRFBs.

Cellular uptake of titanium and vanadium from addition of salts or fretting corrosion in vitro

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maurer, A.M.; Merritt, K.; Brown, S.A.

1994-02-01

The use of titanium and titanium-6% aluminum-4% vanadium alloy for dental and orthopedic implants has increased in the last decade. The implants are presumed to be compatible because oseointegration, bony apposition, and cell attachment are known. However, the cellular association of titanium and vanadium have remained unknown. This study examined the uptake of salts or fretting corrosion products. Titanium was not observed to be toxic to the cells. Vanadium was toxic at levels greater than 10[mu]g/mL. The percentage of cellular association of titanium was shown to be about 10 times that of vanadium. The percentage of cellular association of eithermore » element was greater from fretting corrosion than from the addition of salts. The presence of vanadium did not affect the cellular uptake of titanium. The presence of titanium decreased the cell association of vanadium.« less

New Polymeric Precursors of Silicon Carbide

NASA Technical Reports Server (NTRS)

Litt, M.; Kumar, K.

1987-01-01

Silicon carbide made by pyrolizing polymers. Method conceived for preparation of poly(decamethylcyclohexasilanes) as precursors for preparation of silicon carbide at high yield. Technical potential of polysilanes as precursors of SiC ceramics being explored. Potential limited by intractability of some polysilanes; formation of small, cyclic polycarbosilane fragments during pyrolysis; and overall low char yield and large shrinkage in conversion to ceramics.

Silicon nitride/silicon carbide composite powders

DOEpatents

Dunmead, Stephen D.; Weimer, Alan W.; Carroll, Daniel F.; Eisman, Glenn A.; Cochran, Gene A.; Susnitzky, David W.; Beaman, Donald R.; Nilsen, Kevin J.

1996-06-11

Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

Protective effects of Sesamum indicum extract against oxidative stress induced by vanadium on isolated rat hepatocytes.

PubMed

Hosseini, Mir-Jamal; Shahraki, Jafar; Tafreshian, Saman; Salimi, Ahmad; Kamalinejad, Mohammad; Pourahmad, Jalal

2016-08-01

Vanadium toxicity is a challenging problem to human and animal health with no entirely understanding cytotoxic mechanisms. Previous studies in vanadium toxicity showed involvement of oxidative stress in isolated liver hepatocytes and mitochondria via increasing of ROS formation, release of cytochrome c and ATP depletion after incubation with different concentrations (25-200 µM). Therefore, we aimed to investigate the protective effects of Sesamum indicum seed extract (100-300 μg/mL) against oxidative stress induced by vanadium on isolated rat hepatocytes. Our results showed that quite similar to Alpha-tocopherol (100 µM), different concentrations of extract (100-300 μg/mL) protected the isolated hepatocyte against all oxidative stress/cytotoxicity markers induced by vanadium in including cell lysis, ROS generation, mitochondrial membrane potential decrease and lysosomal membrane damage. Besides, vanadium induced mitochondrial/lysosomal toxic interaction and vanadium reductive activation mediated by glutathione in vanadium toxicity was significantly (P < 0.05) ameliorated by Sesamum indicum extracts. These findings suggested a hepato-protective role for extracts against liver injury resulted from vanadium toxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 979-985, 2016. © 2015 Wiley Periodicals, Inc.

Joining of porous silicon carbide bodies

DOEpatents

Bates, Carl H.; Couhig, John T.; Pelletier, Paul J.

1990-05-01

A method of joining two porous bodies of silicon carbide is disclosed. It entails utilizing an aqueous slip of a similar silicon carbide as was used to form the porous bodies, including the sintering aids, and a binder to initially join the porous bodies together. Then the composite structure is subjected to cold isostatic pressing to form a joint having good handling strength. Then the composite structure is subjected to pressureless sintering to form the final strong bond. Optionally, after the sintering the structure is subjected to hot isostatic pressing to further improve the joint and densify the structure. The result is a composite structure in which the joint is almost indistinguishable from the silicon carbide pieces which it joins.

Plasma Enabled Fabrication of Silicon Carbide Nanostructures

NASA Astrophysics Data System (ADS)

Fang, Jinghua; Levchenko, Igor; Aramesh, Morteza; Rider, Amanda E.; Prawer, Steven; Ostrikov, Kostya (Ken)

Silicon carbide is one of the promising materials for the fabrication of various one- and two-dimensional nanostructures. In this chapter, we discuss experimental and theoretical studies of the plasma-enabled fabrication of silicon carbide quantum dots, nanowires, and nanorods. The discussed fabrication methods include plasma-assisted growth with and without anodic aluminium oxide membranes and with or without silane as a source of silicon. In the silane-free experiments, quartz was used as a source of silicon to synthesize the silicon carbide nanostructures in an environmentally friendly process. The mechanism of the formation of nanowires and nanorods is also discussed.

Creep behavior of uranium carbide-based alloys

NASA Technical Reports Server (NTRS)

Seltzer, M. S.; Wright, T. R.; Moak, D. P.

1975-01-01

The present work gives the results of experiments on the influence of zirconium carbide and tungsten on the creep properties of uranium carbide. The creep behavior of high-density UC samples follows the classical time-dependence pattern of (1) an instantaneous deformation, (2) a primary creep region, and (3) a period of steady-state creep. Creep rates for unalloyed UC-1.01 and UC-1.05 are several orders of magnitude greater than those measured for carbide alloys containing a Zr-C and/or W dispersoid. The difference in creep strength between alloyed and unalloyed materials varies with temperature and applied stress.

76 FR 78888 - Final Results of Expedited Sunset Review: Ferrovanadium and Nitrided Vanadium From Russia

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-20

... Sunset Review: Ferrovanadium and Nitrided Vanadium From Russia AGENCY: Import Administration... and nitrided vanadium from the Russian Federation (Russia), pursuant to section 751(c) of the Tariff... vanadium from Russia, pursuant to section 751(c) of the Act. See Initiation of Five-Year (``Sunset...

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

PubMed

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.

The determination of vanadium in brines by atomic absorption spectroscopy

USGS Publications Warehouse

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.

77 FR 54897 - Ferrovanadium and Nitrided Vanadium from the Russian Federation: Revocation of Antidumping Duty...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-06

... nitrided vanadium from the Russian Federation (Russia) would not be likely to lead to continuation or... the antidumping duty order on ferrovanadium and nitrided vanadium from Russia. \\1\\ See Ferrovanadium and Nitrided Vanadium From Russia, 77 FR 51825 (August 27, 2012) (ITC Final). DATES: Effective Date...

Growth control of the oxidation state in vanadium oxide thin films

DOE PAGES

Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; ...

2014-12-05

Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research, but also technological applications that utilize the subtle change in the physical properties originating from the metalinsulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase puremore » epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V₂⁺²O₃, V⁺⁴O₂, and V₂⁺⁵O₅. A well pronounced MIT was only observed in VO₂ films grown in a very narrow range of oxygen partial pressure P(O₂). The films grown either in lower (< 10 mTorr) or higher P(O₂) (> 25 mTorr) result in V₂O₃ and V₂O₅ phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO₂ thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an 3 improved MIT behavior.« less

Growth control of the oxidation state in vanadium oxide thin films

NASA Astrophysics Data System (ADS)

Lee, Shinbuhm; Meyer, Tricia L.; Park, Sungkyun; Egami, Takeshi; Lee, Ho Nyung

2014-12-01

Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research but also technological applications that utilize the subtle change in the physical properties originating from the metal-insulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase pure epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V2 + 3 O 3 , V + 4 O 2 , and V2 + 5 O 5 . A well pronounced MIT was only observed in VO2 films grown in a very narrow range of oxygen partial pressure P(O2). The films grown either in lower (<10 mTorr) or higher P(O2) (>25 mTorr) result in V2O3 and V2O5 phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO2 thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an improved MIT behavior.

Electroextraction of boron from boron carbide scrap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jain, Ashish; Anthonysamy, S., E-mail: sas@igcar.gov.in; Ghosh, C.

2013-10-15

Studies were carried out to extract elemental boron from boron carbide scrap. The physicochemical nature of boron obtained through this process was examined by characterizing its chemical purity, specific surface area, size distribution of particles and X-ray crystallite size. The microstructural characteristics of the extracted boron powder were analyzed by using scanning electron microscopy and transmission electron microscopy. Raman spectroscopic examination of boron powder was also carried out to determine its crystalline form. Oxygen and carbon were found to be the major impurities in boron. Boron powder of purity ∼ 92 wt. % could be produced by the electroextraction processmore » developed in this study. Optimized method could be used for the recovery of enriched boron ({sup 10}B > 20 at. %) from boron carbide scrap generated during the production of boron carbide. - Highlights: • Recovery of {sup 10}B from nuclear grade boron carbide scrap • Development of process flow sheet • Physicochemical characterization of electroextracted boron • Microscopic examination of electroextracted boron.« less

Magneto-Resistance in thin film boron carbides

NASA Astrophysics Data System (ADS)

Echeverria, Elena; Luo, Guangfu; Liu, J.; Mei, Wai-Ning; Pasquale, F. L.; Colon Santanta, J.; Dowben, P. A.; Zhang, Le; Kelber, J. A.

2013-03-01

Chromium doped semiconducting boron carbide devices were fabricated based on a carborane icosahedra (B10C2H12) precursor via plasma enhanced chemical vapor deposition, and the transition metal atoms found to dope pairwise on adjacent icosahedra site locations. Models spin-polarized electronic structure calculations of the doped semiconducting boron carbides indicate that some transition metal (such as Cr) doped semiconducting boron carbides may act as excellent spin filters when used as the dielectric barrier in a magnetic tunnel junction structure. In the case of chromium doping, there may be considerable enhancements in the magneto-resistance of the heterostructure. To this end, current to voltage curves and magneto-transport measurements were performed in various semiconducting boron carbide both in and out plane. The I-V curves as a function of external magnetic field exhibit strong magnetoresistive effects which are enhanced at liquid Nitrogen temperatures. The mechanism for these effects will be discussed in the context of theoretical calculations.

Salt flux synthesis of single and bimetallic carbide nanowires

NASA Astrophysics Data System (ADS)

Leonard, Brian M.; Waetzig, Gregory R.; Clouser, Dale A.; Schmuecker, Samantha M.; Harris, Daniel P.; Stacy, John M.; Duffee, Kyle D.; Wan, Cheng

2016-07-01

Metal carbide compounds have a broad range of interesting properties and are some of the hardest and highest melting point compounds known. However, their high melting points force very high reaction temperatures and thus limit the formation of high surface area nanomaterials. To avoid the extreme synthesis temperatures commonly associated with these materials, a new salt flux technique has been employed to reduce reaction temperatures and form these materials in the nanometer regime. Additionally, the use of multiwall carbon nanotubes as a reactant further reduces the diffusion distance and provides a template for the final carbide materials. The metal carbide compounds produced through this low temperature salt flux technique maintain the nanowire morphology of the carbon nanotubes but increase in size to ˜15-20 nm diameter due to the incorporation of metal in the carbon lattice. These nano-carbides not only have nanowire like shape but also have much higher surface areas than traditionally prepared metal carbides. Finally, bimetallic carbides with composition control can be produced with this method by simply using two metal precursors in the reaction. This method provides the ability to produce nano sized metal carbide materials with size, morphology, and composition control and will allow for these compounds to be synthesized and studied in a whole new size and temperature regime.

Why Antidiabetic Vanadium Complexes are Not in the Pipeline of "Big Pharma" Drug Research? A Critical Review.

PubMed

Scior, Thomas; Guevara-Garcia, Jose Antonio; Do, Quoc-Tuan; Bernard, Philippe; Laufer, Stefan

2016-01-01

Public academic research sites, private institutions as well as small companies have made substantial contributions to the ongoing development of antidiabetic vanadium compounds. But why is this endeavor not echoed by the globally operating pharmaceutical companies, also known as "Big Pharma"? Intriguingly, today's clinical practice is in great need to improve or replace insulin treatment against Diabetes Mellitus (DM). Insulin is the mainstay therapeutically and economically. So, why do those companies develop potential antidiabetic drug candidates without vanadium (vanadium- free)? We gathered information about physicochemical and pharmacological properties of known vanadium-containing antidiabetic compounds from the specialized literature, and converted the data into explanations (arguments, the "pros and cons") about the underpinnings of antidiabetic vanadium. Some discoveries were embedded in chronological order while seminal reviews of the last decade about the Medicinal chemistry of vanadium and its history were also listed for further understanding. In particular, the concepts of so-called "noncomplexed or free" vanadium species (i.e. inorganic oxido-coordinated species) and "biogenic speciation" of antidiabetic vanadium complexes were found critical and subsequently documented in more details to answer the question.

Physiological and anthocyanin biosynthesis genes response induced by vanadium stress in mustard genotypes with distinct photosynthetic activity.

PubMed

Imtiaz, Muhammad; Mushtaq, Muhammad Adnan; Nawaz, Muhammad Amjad; Ashraf, Muhammad; Rizwan, Muhammad Shahid; Mehmood, Sajid; Aziz, Omar; Rizwan, Muhammad; Virk, Muhammad Safiullah; Shakeel, Qaiser; Ijaz, Raina; Androutsopoulos, Vasilis P; Tsatsakis, Aristides M; Coleman, Michael D

2018-06-13

The present study aimed to elucidate the photosynthetic performance, antioxidant enzyme activities, anthocyanin contents, anthocyanin biosynthetic gene expression, and vanadium uptake in mustard genotypes (purple and green) that differ in photosynthetic capacity under vanadium stress. The results indicated that vanadium significantly reduced photosynthetic activity in both genotypes. The activities of the antioxidant enzymes were increased significantly in response to vanadium in both genotypes, although the purple exhibited higher. The anthocyanin contents were also reduced under vanadium stress. The anthocyanin biosynthetic genes were highly expressed in the purple genotype, notably the genes TT8, F3H, and MYBL2 under vanadium stress. The results indicate that induction of TT8, F3H, and MYBL2 genes was associated with upregulation of the biosynthetic genes required for higher anthocyanin biosynthesis in purple compared with the green mustard. The roots accumulated higher vanadium than shoots in both mustard genotypes. The results indicate that the purple mustard had higher vanadium tolerance. Copyright © 2018 Elsevier B.V. All rights reserved.

Vanadium based materials as electrode materials for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Yan, Yan; Li, Bing; Guo, Wei; Pang, Huan; Xue, Huaiguo

2016-10-01

As a kind of supercapacitors, pseudocapacitors have attracted wide attention in recent years. The capacitance of the electrochemical capacitors based on pseudocapacitance arises mainly from redox reactions between electrolytes and active materials. These materials usually have several oxidation states for oxidation and reduction. Many research teams have focused on the development of an alternative material for electrochemical capacitors. Many transition metal oxides have been shown to be suitable as electrode materials of electrochemical capacitors. Among them, vanadium based materials are being developed for this purpose. Vanadium based materials are known as one of the best active materials for high power/energy density electrochemical capacitors due to its outstanding specific capacitance and long cycle life, high conductivity and good electrochemical reversibility. There are different kinds of synthetic methods such as sol-gel hydrothermal/solvothermal method, template method, electrospinning method, atomic layer deposition, and electrodeposition method that have been successfully applied to prepare vanadium based electrode materials. In our review, we give an overall summary and evaluation of the recent progress in the research of vanadium based materials for electrochemical capacitors that include synthesis methods, the electrochemical performances of the electrode materials and the devices.

Novel hybrid materials based on the vanadium oxide nanobelts

NASA Astrophysics Data System (ADS)

Zabrodina, G. S.; Makarov, S. G.; Kremlev, K. V.; Yunin, P. A.; Gusev, S. A.; Kaverin, B. S.; Kaverina, L. B.; Ketkov, S. Yu.

2016-04-01

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 V2O5·nH2O gel with surfactants (TBAB, CTAB) used as structure-directing agents, where CTAB - cetyltrimethylammonium bromide, TBAB - tetrabutylammonium bromide. Hybrid materials were prepared decoration of (CTA)0.33V2O5 flexible nanobelts with cationic zinc phthalocyanine by the ion-exchange route. Investigations of the thermal stability, morphologies and structures of the (CTA)0.33V2O5, (TBA)0.16V2O5 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.

A silicon carbide array for electrocorticography and peripheral nerve recording.

PubMed

Diaz-Botia, C A; Luna, L E; Neely, R M; Chamanzar, M; Carraro, C; Carmena, J M; Sabes, P N; Maboudian, R; Maharbiz, M M

2017-10-01

Current neural probes have a limited device lifetime of a few years. Their common failure mode is the degradation of insulating films and/or the delamination of the conductor-insulator interfaces. We sought to develop a technology that does not suffer from such limitations and would be suitable for chronic applications with very long device lifetimes. We developed a fabrication method that integrates polycrystalline conductive silicon carbide with insulating silicon carbide. The technology employs amorphous silicon carbide as the insulator and conductive silicon carbide at the recording sites, resulting in a seamless transition between doped and amorphous regions of the same material, eliminating heterogeneous interfaces prone to delamination. Silicon carbide has outstanding chemical stability, is biocompatible, is an excellent molecular barrier and is compatible with standard microfabrication processes. We have fabricated silicon carbide electrode arrays using our novel fabrication method. We conducted in vivo experiments in which electrocorticography recordings from the primary visual cortex of a rat were obtained and were of similar quality to those of polymer based electrocorticography arrays. The silicon carbide electrode arrays were also used as a cuff electrode wrapped around the sciatic nerve of a rat to record the nerve response to electrical stimulation. Finally, we demonstrated the outstanding long term stability of our insulating silicon carbide films through accelerated aging tests. Clinical translation in neural engineering has been slowed in part due to the poor long term performance of current probes. Silicon carbide devices are a promising technology that may accelerate this transition by enabling truly chronic applications.

A silicon carbide array for electrocorticography and peripheral nerve recording

NASA Astrophysics Data System (ADS)

Diaz-Botia, C. A.; Luna, L. E.; Neely, R. M.; Chamanzar, M.; Carraro, C.; Carmena, J. M.; Sabes, P. N.; Maboudian, R.; Maharbiz, M. M.

2017-10-01

Objective. Current neural probes have a limited device lifetime of a few years. Their common failure mode is the degradation of insulating films and/or the delamination of the conductor-insulator interfaces. We sought to develop a technology that does not suffer from such limitations and would be suitable for chronic applications with very long device lifetimes. Approach. We developed a fabrication method that integrates polycrystalline conductive silicon carbide with insulating silicon carbide. The technology employs amorphous silicon carbide as the insulator and conductive silicon carbide at the recording sites, resulting in a seamless transition between doped and amorphous regions of the same material, eliminating heterogeneous interfaces prone to delamination. Silicon carbide has outstanding chemical stability, is biocompatible, is an excellent molecular barrier and is compatible with standard microfabrication processes. Main results. We have fabricated silicon carbide electrode arrays using our novel fabrication method. We conducted in vivo experiments in which electrocorticography recordings from the primary visual cortex of a rat were obtained and were of similar quality to those of polymer based electrocorticography arrays. The silicon carbide electrode arrays were also used as a cuff electrode wrapped around the sciatic nerve of a rat to record the nerve response to electrical stimulation. Finally, we demonstrated the outstanding long term stability of our insulating silicon carbide films through accelerated aging tests. Significance. Clinical translation in neural engineering has been slowed in part due to the poor long term performance of current probes. Silicon carbide devices are a promising technology that may accelerate this transition by enabling truly chronic applications.

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

PubMed Central

Folarin, Oluwabusayo R.; Snyder, Amanda M.; Peters, Douglas G.; Olopade, Funmilayo; Connor, James R.; Olopade, James O.

2017-01-01

Vanadium is a potentially toxic environmental pollutant and induces oxidative damage in biological systems including the central nervous system (CNS). Its deposition in brain tissue may be involved in the pathogenesis of certain neurological disorders which after prolonged exposure can culminate into more severe pathology. Most studies on vanadium neurotoxicity have been done after acute exposure but in reality some populations are exposed for a lifetime. This work was designed to ascertain neurodegenerative consequences of chronic vanadium administration and to investigate the progressive changes in the brain after withdrawal from vanadium treatment. A total of 85 male BALB/c mice were used for the experiment and divided into three major groups of vanadium treated (intraperitoneally (i.p.) injected with 3 mg/kg body weight of sodium metavanadate and sacrificed every 3 months till 18 months); matched controls; and animals that were exposed to vanadium for 3 months and thereafter the metal was withdrawn. Brain tissues were obtained after animal sacrifice. Sagittal cut sections of paraffin embedded tissue (5 μm) were analyzed by the Laser ablation-inductively coupled plasma-mass spectrometry (LA–ICP–MS) to show the absorption and distribution of vanadium metal. Also, Haematoxylin and Eosin (H&E) staining of brain sections, and immunohistochemistry for Microglia (Iba-1), Astrocytes (GFAP), Neurons (Neu-N) and Neu-N + 4′,6-diamidine-2′-pheynylindole dihydrochloride (Dapi) Immunofluorescent labeling were observed for morphological and morphometric parameters. The LA–ICP–MS results showed progressive increase in vanadium uptake with time in different brain regions with prediction for regions like the olfactory bulb, brain stem and cerebellum. The withdrawal brains still show presence of vanadium metal in the brain slightly more than the controls. There were morphological alterations (of the layering profile, nuclear shrinkage) in the prefrontal cortex

Chemical state of fission products in irradiated uranium carbide fuel

NASA Astrophysics Data System (ADS)

Arai, Yasuo; Iwai, Takashi; Ohmichi, Toshihiko

1987-12-01

The chemical state of fission products in irradiated uranium carbide fuel has been estimated by equilibrium calculation using the SOLGASMIX-PV program. Solid state fission products are distributed to the fuel matrix, ternary compounds, carbides of fission products and intermetallic compounds among the condensed phases appearing in the irradiated uranium carbide fuel. The chemical forms are influenced by burnup as well as stoichiometry of the fuel. The results of the present study almost agree with the experimental ones reported for burnup simulated carbides.

Ab initio Investigation of Helium in Vanadium Oxide Nanoclusters

NASA Astrophysics Data System (ADS)

Danielson, Thomas; Tea, Eric; Hin, Celine

Nanostructured ferritic alloys (NFAs) are strong candidate materials for the next generation of fission reactors and future fusion reactors. They are characterized by a large number density of oxide nanoclusters dispersed throughout a BCC iron matrix, where current oxide nanoclusters are primarily comprised of Y-Ti-O compounds. The oxide nanoclusters provide the alloy with high resistance to neutron irradiation, high yield strength and high creep strength at the elevated temperatures of a reactor environment. In addition, the oxide nanoclusters serve as trapping sites for transmutation product helium providing substantially increased resistance to catastrophic cracking and embrittlement. Although the mechanical properties and radiation resistance of the existing NFAs is promising, the problem of forming large scale reactor components continues to present a formidable challenge due to the high hardness and unpredictable fracture behavior of the alloys. An alternative alloy has been previously proposed and fabricated where vanadium is added in order to form vanadium oxide nanoclusters that serve as deflection sites for crack propagation. Although experiments have shown evidence that the fracture behavior of the alloys is improved, it is unknown whether or not the vanadium oxide nanoclusters are effective trapping sites for helium. We present results obtained using density functional theory investigating the thermodynamic stability of helium with the vanadium oxide matrix to make a comparison of trapping effectiveness to traditional Y-Ti-O compounds.

Modeling of ion transport through a porous separator in vanadium redox flow batteries

NASA Astrophysics Data System (ADS)

Zhou, X. L.; Zhao, T. S.; An, L.; Zeng, Y. K.; Wei, L.

2016-09-01

In this work, we develop a two-dimensional, transient model to investigate the mechanisms of ion-transport through a porous separator in VRFBs and their effects on battery performance. Commercial-available separators with pore sizes of around 45 nm are particularly investigated and effects of key separator design parameters and operation modes are explored. We reveal that: i) the transport mechanism of vanadium-ion crossover through available separators is predominated by convection; ii) reducing the pore size below 15 nm effectively minimizes the convection-driven vanadium-ion crossover, while further reduction in migration- and diffusion-driven vanadium-ion crossover can be achieved only when the pore size is reduced to the level close to the sizes of vanadium ions; and iii) operation modes that can affect the pressure at the separator/electrode interface, such as the electrolyte flow rate, exert a significant influence on the vanadium-ion crossover rate through the available separators, indicating that it is critically important to equalize the pressure on each half-cell of a power pack in practical applications.

Chemical-Vapor Deposition Of Silicon Carbide

NASA Technical Reports Server (NTRS)

Cagliostro, D. E.; Riccitiello, S. R.; Ren, J.; Zaghi, F.

1993-01-01

Report describes experiments in chemical-vapor deposition of silicon carbide by pyrolysis of dimethyldichlorosilane in hydrogen and argon carrier gases. Directed toward understanding chemical-kinetic and mass-transport phenomena affecting infiltration of reactants into, and deposition of SiC upon, fabrics. Part of continuing effort to develop method of efficient and more nearly uniform deposition of silicon carbide matrix throughout fabric piles to make improved fabric/SiC-matrix composite materials.

Amorphous Mixed-Valence Vanadium Oxide/Exfoliated Carbon Cloth Structure Shows a Record High Cycling Stability.

PubMed

Song, Yu; Liu, Tian-Yu; Yao, Bin; Kou, Tian-Yi; Feng, Dong-Yang; Liu, Xiao-Xia; Li, Yat

2017-04-01

Previous studies show that vanadium oxides suffer from severe capacity loss during cycling in the liquid electrolyte, which has hindered their applications in electrochemical energy storage. The electrochemical instability is mainly due to chemical dissolution and structural pulverization of vanadium oxides during charge/discharge cyclings. In this study the authors demonstrate that amorphous mixed-valence vanadium oxide deposited on exfoliated carbon cloth (CC) can address these two limitations simultaneously. The results suggest that tuning the V 4+ /V 5+ ratio of vanadium oxide can efficiently suppress the dissolution of the active materials. The oxygen-functionalized carbon shell on exfoliated CC can bind strongly with VO x via the formation of COV bonding, which retains the electrode integrity and suppresses the structural degradation of the oxide during charging/discharging. The uptake of structural water during charging and discharging processes also plays an important role in activating the electrode material. The amorphous mixed-valence vanadium oxide without any protective coating exhibits record-high cycling stability in the aqueous electrolyte with no capacitive decay in 100 000 cycles. This work provides new insights on stabilizing vanadium oxide, which is critical for the development of vanadium oxide based energy storage devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Complex formation of vanadium(V) with resorcylalhydrazides of carboxylic acids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dudarev, V.I.; Dolgorev, V.A.; Volkov, A.N.

1986-08-01

In this work, a previous investigation of hydrazine derivatives as analytical reagents for vanadium(V) was continued. The authors studied arylalhydrazones -- derivatives of resorcylalhydrazides of anisic (RHASA), anthranilic (RHANA), and benzoic (RHBA) acids. The reagents presented differ from those studied previously by the presence of a second hydroxy group in the para-position of the benzene ring -the resorcinol fragment -- and substituents in the benzoin fragment. Such changes made it possible to increase the solubility of the reagents in aqueous medium and to estimate the change in the main spectrophotometric parameters of the analytical reaction. A rapid method was developedmore » for the determination of vanadium in steels with the resorcylalhydrazide of anthranilic acid. The minimum determinable vanadium content is 0.18 micrograms/ml.« less

Vanadium K-edge X-ray absorption spectroscopy of bromoperoxidase from Ascophyllum nodosum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arber, J.M.; de Boer, E.; Garner, C.D.

Bromoperoxidase from Ascophyllum nodusum was the first vanadium-containing enzyme to be isolated. X-ray absorption spectra have now been collected in order to investigate the coordination of vanadium in the native, native plus bromide, native plus hydrogen peroxide, and dithionite-reduced forms of the enzyme. The edge and X-ray absorption near-edge structures show that, in the four samples studied, it is only on reduction of the native enzyme that the metal site is substantially altered. In addition, these data are consistent with the presence of vanadium(IV) in the reduced enzyme and vanadium(V) in the other samples. Extended X-ray absorption fine structure datamore » confirm that there are structural changes at the metal site on reduction of the native enzyme, notably a lengthening of the average inner-shell distance, and the presence of terminal oxygen together with histidine and oxygen-donating residues.« less

Investigation of crossover processes in a unitized bidirectional vanadium/air redox flow battery

NASA Astrophysics Data System (ADS)

grosse Austing, Jan; Nunes Kirchner, Carolina; Komsiyska, Lidiya; Wittstock, Gunther

2016-02-01

In this paper the losses in coulombic efficiency are investigated for a vanadium/air redox flow battery (VARFB) comprising a two-layered positive electrode. Ultraviolet/visible (UV/Vis) spectroscopy is used to monitor the concentrations cV2+ and cV3+ during operation. The most likely cause for the largest part of the coulombic losses is the permeation of oxygen from the positive to the negative electrode followed by an oxidation of V2+ to V3+. The total vanadium crossover is followed by inductively coupled plasma mass spectroscopy (ICP-MS) analysis of the positive electrolyte after one VARFB cycle. During one cycle 6% of the vanadium species initially present in the negative electrolyte are transferred to the positive electrolyte, which can account at most for 20% of the coulombic losses. The diffusion coefficients of V2+ and V3+ through Nafion® 117 are determined as DV2+ ,N 117 = 9.05 ·10-6 cm2 min-1 and DV3+ ,N 117 = 4.35 ·10-6 cm2 min-1 and are used to calculate vanadium crossover due to diffusion which allows differentiation between vanadium crossover due to diffusion and migration/electroosmotic convection. In order to optimize coulombic efficiency of VARFB, membranes need to be designed with reduced oxygen permeation and vanadium crossover.

Cytotoxic effect of vanadium and oil-fired fly ash on hamster tracheal epithelium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schiff, L.J.; Graham, J.A.

1984-08-01

Hamster tracheal organ cultures were used to study the in vitro effects of vanadium and oil-fired fly ash on mucociliary respiratory epithelium. Two vanadium compounds, VOSO/sub 4/ and V/sub 2/O/sub 5/, and fly ash from an oil-fueled power plant were dissolved or suspended in culture medium over a range of concentrations and epithelia were exposed for 1 hr/day, for 9 consecutive days. At intervals during this period, alterations in cilia-beating frequency, cytology, and histology were documented by light microscopy. Explants treated with VOSO/sub 4/ either decreased ciliary activity or produced ciliostasis depending upon the concentration and length of exposure. Earlymore » morphological alterations consisted of vacuolization of both nuclei and cytoplasm. After multiple exposures, cytology of VOSO/sub 4/-treated respiratory mucosa was markedly affected. Similar changes were observed in cultures exposed to V/sub 2/O/sub 5/; however, the cytotoxicity appeared earlier and was more pronounced. Fly ash-treated explants produced similar biological effects when compared to both vanadium compounds. Thus, the data indicate that the extent of vanadium toxicity depends, at least in part, on the vanadium content of the compound tested, and that exposure to this metal and vanadium-rich fly ash can inhibit normal mucociliary function, a vital clearance mechanism in the respiratory tract.« less

Diamond-silicon carbide composite

DOEpatents

Qian, Jiang; Zhao, Yusheng

2006-06-13

Fully dense, diamond-silicon carbide composites are prepared from ball-milled microcrystalline diamond/amorphous silicon powder mixture. The ball-milled powder is sintered (P=5–8 GPa, T=1400K–2300K) to form composites having high fracture toughness. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPa.dot.m^1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness. X-ray diffraction patterns and Raman spectra indicate that amorphous silicon is partially transformed into nanocrystalline silicon at 5 GPa/873K, and nanocrystalline silicon carbide forms at higher temperatures.

Growth control of the oxidation state in vanadium oxide thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Shinbuhm; Meyer, Tricia L.; Lee, Ho Nyung, E-mail: hnlee@ornl.gov

2014-12-01

Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research but also technological applications that utilize the subtle change in the physical properties originating from the metal-insulator transition (MIT) near room temperature. However, due to the multivalent nature of vanadium and the lack of a good understanding on growth control of the oxidation state, stabilization of phase pure vanadium oxides with a single oxidation state is extremely challenging. Here, we systematically varied the growth conditions to clearly map out the growth window for preparing phase puremore » epitaxial vanadium oxides by pulsed laser deposition for providing a guideline to grow high quality thin films with well-defined oxidation states of V{sub 2}{sup +3}O{sub 3}, V{sup +4}O{sub 2}, and V{sub 2}{sup +5}O{sub 5}. A well pronounced MIT was only observed in VO{sub 2} films grown in a very narrow range of oxygen partial pressure P(O{sub 2}). The films grown either in lower (<10 mTorr) or higher P(O{sub 2}) (>25 mTorr) result in V{sub 2}O{sub 3} and V{sub 2}O{sub 5} phases, respectively, thereby suppressing the MIT for both cases. We have also found that the resistivity ratio before and after the MIT of VO{sub 2} thin films can be further enhanced by one order of magnitude when the films are further oxidized by post-annealing at a well-controlled oxidizing ambient. This result indicates that stabilizing vanadium into a single valence state has to compromise with insufficient oxidation of an as grown thin film and, thereby, a subsequent oxidation is required for an improved MIT behavior.« less

Vanadium(IV)-stimulated hydrolysis of 2,3-diphosphoglycerate.

PubMed

Stankiewicz, P J

1989-05-01

Vanadium(IV) stimulates the hydrolysis of 2,3-diphosphoglycerate at 23 degrees C. The pH optimum is 5.0. Reactions were analyzed by enzymatic and phosphate release assays. The products of 2,3-diphosphoglycerate hydrolysis are inorganic phosphate and 3-phosphoglycerate. The reaction is inhibited by high concentrations of 2,3-diphosphoglycerate and an equation has been formulated that describes the kinetic constants for this reaction at pH 7. The possible relevance of the reaction to the therapeutic lowering by vanadium(IV) of red cell 2,3-diphosphoglycerate in sickle-cell disease is discussed.

Tunable carbon nanotube-tungsten carbide nanoparticles heterostructures by vapor deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xia, Min; Guo, Hongyan; Ge, Changchun

2014-05-14

A simple, versatile route for the synthesis of carbon nanotube (CNT)-tungsten carbide nanoparticles heterostructures was set up via vapor deposition process. For the first time, amorphous CNTs (α-CNTs) were used to immobilized tungsten carbide nanoparticles. By adjusting the synthesis and annealing temperature, α-CNTs/amorphous tungsten carbide, α-CNTs/W{sub 2}C, and CNTs/W{sub 2}C/WC heterostructures were prepared. This approach provides an efficient method to attach other metal carbides and other nanoparticles to carbon nanotubes with tunable properties.

Insulin and vanadium protect against osteoarthritis development secondary to diabetes mellitus in rats.

PubMed

El Karib, Abbas O; Al-Ani, Bahjat; Al-Hashem, Fahaid; Dallak, Mohammad; Bin-Jaliah, Ismaeel; El-Gamal, Basiouny; Bashir, Salah O; Eid, Refaat A; Haidara, Mohamed A

2016-07-01

Diabetic complications such as cardiovascular disease and osteoarthritis (OA) are among the common public health problems. The effect of insulin on OA secondary to diabetes has not been investigated before in animal models. Therefore, we sought to determine whether insulin and the insulin-mimicking agent, vanadium can protect from developing OA in diabetic rats. Type 1 diabetes mellitus (T1DM) was induced in Sprague-Dawley rats and treated with insulin and/or vanadium. Tissues harvested from the articular cartilage of the knee joint were examined by scanning electron microscopy, and blood samples were assayed for oxidative stress and inflammatory biomarkers. Eight weeks following the induction of diabetes, a profound damage to the knee joint compared to the control non-diabetic group was observed. Treatment of diabetic rats with insulin and/or vanadium differentially protected from diabetes-induced cartilage damage and deteriorated fibrils of collagen fibers. The relative biological potencies were insulin + vanadium > insulin > vanadium. Furthermore, there was about 2- to 5-fold increase in TNF-α (from 31.02 ± 1.92 to 60.5 ± 1.18 pg/ml, p < 0.0001) and IL-6 (from 64.67 ± 8.16 to 338.0 ± 38.9 pg/ml, p < 0.0001) cytokines and free radicals measured as TBARS (from 3.21 ± 0.37 to 11.48 ± 1.5 µM, p < 0.0001) in the diabetic group, which was significantly reduced with insulin and or vanadium. Meanwhile, SOD decreased (from 17.79 ± 8.9 to 8.250.29, p < 0.0001) and was increased with insulin and vanadium. The relative potencies of the treating agents on inflammatory and oxidative stress biomarkers were insulin + vanadium > insulin > vanadium. The present study demonstrates that co-administration of insulin and vanadium to T1DM rats protect against diabetes-induced OA possibly by lowering biomarkers of inflammation and oxidative stress.

Modified silicon carbide whiskers

DOEpatents

Tiegs, Terry N.; Lindemer, Terrence B.

1991-01-01

Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

Modified silicon carbide whiskers

DOEpatents

Tiegs, T.N.; Lindemer, T.B.

1991-05-21

Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

Researches on tungsten carbide

NASA Astrophysics Data System (ADS)

1994-11-01

This paper summarizes results of the researches on tungsten carbide (WC), carried out in the 5-year period starting 1989 by the Science and Technology Agency's National Institute for Researches in Inorganic Materials. The high-frequency heating, floating zone technique, generally suited for growth of large-size, single crystals of high melting materials, is inapplicable to the hexagonal WC system, which is decomposed. This problem has been solved by adding boron to the system, to allow it to exist with the W-C-B melt at an equilibrium. The computer-aided control techniques have enabled automatic growth of the single crystals of carbides and borides. The de Haas-Van Alphen effect of the single WC crystals has been observed, to establish the Fermi surface model. The single crystals of transition metal carbides, such as WC, have been coated with the monolayer of graphite at high repeatability, to create the surface layer materials. An attempt has been done to produce the halite type structure by substituting Ti as the atom in the outermost layer of TiC by W. The new method, based on the low-speed deuterium ion scattering, has been developed to analyze the surface bonding conditions, clarifying the conditions of alkalis adsorbed on and bonded to metallic surfaces, and their surface reactivities.

76 FR 69736 - Draft Toxicological Review of Vanadium Pentoxide: In Support of Summary Information on the...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-09

... Toxicological Review of Vanadium Pentoxide: In Support of Summary Information on the Integrated Risk Information..., ``Toxicological Review of Vanadium Pentoxide: In Support of Summary Information on the Integrated Risk Information... Vanadium Pentoxide: In Support of Summary Information on the Integrated Risk Information System (IRIS)'' is...

Extreme-Environment Silicon-Carbide (SiC) Wireless Sensor Suite

NASA Technical Reports Server (NTRS)

Yang, Jie

2015-01-01

Phase II objectives: Develop an integrated silicon-carbide wireless sensor suite capable of in situ measurements of critical characteristics of NTP engine; Compose silicon-carbide wireless sensor suite of: Extreme-environment sensors center, Dedicated high-temperature (450 deg C) silicon-carbide electronics that provide power and signal conditioning capabilities as well as radio frequency modulation and wireless data transmission capabilities center, An onboard energy harvesting system as a power source.

Development and Performance of Boron Carbide-Based Smoke Compositions

DTIC Science & Technology

2013-03-06

DOI: 10.1002/prep.201200166 Development and Performance of Boron Carbide -Based Smoke Compositions Anthony P. Shaw,*[a] Jay C. Poret,[a] Robert A...volatilized and recondense to give smoke. Boron carbide was recognized as a pyrotechnic fuel many years ago, but it has since been overlooked. A 1961...Abstract : Pyrotechnic smoke compositions for visual ob- scuration containing boron carbide , potassium nitrate, po- tassium chloride, and various lubricants

Selective etching of silicon carbide films

DOEpatents

Gao, Di; Howe, Roger T.; Maboudian, Roya

2006-12-19

A method of etching silicon carbide using a nonmetallic mask layer. The method includes providing a silicon carbide substrate; forming a non-metallic mask layer by applying a layer of material on the substrate; patterning the mask layer to expose underlying areas of the substrate; and etching the underlying areas of the substrate with a plasma at a first rate, while etching the mask layer at a rate lower than the first rate.

The Influence of Vanadium Microalloying on the Production of Thin Slab Casting and Direct Rolled Steel Strip

NASA Astrophysics Data System (ADS)

Li, Yu; Milbourn, David

Vanadium microalloying is highly effective in high strength strip steels produced by thin slab casting and direct rolled process. Because of the high solubility of V(C,N) in austenite, vanadium is likely to remain in solution during casting, equalisation and rolling. Vanadium microalloyed steels have better hot ductility and are less prone to transverse cracking than niobium containing steels. Despite a coarse as-cast austenite grain size before rolling, significant grain refinement can be achieved in vanadium microalloyed steels by repeated recrystallization during rolling, resulting in a fine uniform ferrite microstructure in final strip. Almost all vanadium present in microalloyed steels is available to precipitate in ferrite as very fine particles, contributing to precipitation strengthening. Vanadium microalloyed steels show less sensitivity to rolling process variables and exhibit excellent combination of strength and toughness.

Friction and wear behavior of single-crystal silicon carbide in contact with titanium

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Buckley, D. H.

1977-01-01

Sliding friction experiments were conducted with single crystal silicon carbide in sliding contact with titanium. Results indicate that the friction coefficient is greater in vacuum than in argon and that this is due to the greater adhesion or adhesive transfer in vacuum. Thin films of silicon carbide transferred to titanium also adhered to silicon carbide both in argon at atmospheric pressure and in high vacuum. Cohesive bonds fractured on both the silicon carbide and titanium surfaces. The wear debris of silicon carbide created by fracture plowed the silicon carbide surface in a plastic manner. The friction characteristics of titanium in contact with silicon carbide were sensitive to the surface roughness of silicon carbide, and the friction coefficients were higher for a rough surface of silicon carbide than for a smooth one. The difference in friction results was due to plastic deformation (plowing of titanium).

XPS, AES and friction studies of single-crystal silicon carbide

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Buckley, D. H.

1982-01-01

The surface chemistry and friction behavior of a single crystal silicon carbide surface parallel to the 0001 plane in sliding contact with iron at various temperatures to 1500 C in a vacuum of 3 x 10 nPa are investigated using X-ray photoelectron and Auger electron spectroscopy. Results show that graphite and carbide-type carbon are seen primarily on the silicon carbide surface in addition to silicon at temperatures to 800 C by both types of spectroscopy. The coefficients of friction for iron sliding against a silicon carbide surface parallel to the 0001 plane surface are found to be high at temperatures up to 800 C, with the silicon and carbide-type carbon at maximum intensity in the X-ray photoelectron spectroscopy at 800 C. The concentration of the graphite increases rapidly on the surface as the temperature is increased above 800 C, while the concentrations of the carbide-type carbon and silicon decrease rapidly and this presence of graphite is accompanied by a significant decrease in friction. Preheating the surfaces to 1500 C also gives dramatically lower coefficients of friction when reheating in the sliding temperature range of from room temperature to 1200 C, with this reduction in friction due to the graphite layer on the silicon carbide surface.

Process for preparing metal-carbide-containing microspheres from metal-loaded resin beads

DOEpatents

Beatty, Ronald L.

1976-01-01

An improved method for treating metal-loaded resin microspheres is described which comprises heating a metal-loaded resin charge in an inert atmosphere at a pre-carbide-forming temperature under such conditions as to produce a microsphere composition having sufficient carbon as to create a substantially continuous carbon matrix and a metal-carbide or an oxide-carbide mixture as a dispersed phase(s) during carbide-forming conditions, and then heating the thus treated charge to a carbide-forming temperature.

Tribological properties of silicon carbide in metal removal process

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Buckley, D. H.

1980-01-01

Material properties are considered as they relate to adhesion, friction, and wear of single crystal silicon carbide in contact with metals and alloys that are likely to be involved in a metal removal process such as grinding. Metal removal from adhesion between sliding surfaces in contact and metal removal as a result of the silicon carbide sliding against a metal, indenting into it, and plowing a series of grooves or furrows are discussed. Fracture and deformation characteristics of the silicon carbide surface are also covered. The adhesion, friction, and metal transfer to silicon carbide is related to the relative chemical activity of the metals. The more active the metal, the higher the adhesion and friction, and the greater the metal transfer to silicon carbide. Atomic size and content of alloying elements play a dominant role in controlling adhesion, friction, and abrasive wear properties of alloys. The friction and abrasive wear (metal removal) decrease linearly as the shear strength of the bulk metal increases. They decrease as the solute to solvent atomic radius ratio increases or decreases linearly from unity, and with an increase of solute content. The surface fracture of silicon carbide is due to cleavages of 0001, 10(-1)0, and/or 11(-2)0 planes.

Fabrication of vanadium dioxide polycrystalline films with higher temperature coefficient of resistance

NASA Astrophysics Data System (ADS)

Li, Jinhua; Yuan, Ningyi; Jiang, Meiping; Kun, Li

2011-08-01

Vanadium Dioxide Polycrystalline Films with High Temperature Coefficient of Resistance(TCR) were fabricated by modified Ion Beam Enhanced Deposition(IBED) method. The TCR of the Un-doping VO2 was about -4%/K at room temperature after appropriate thermal annealing. The XRD results clearly showed that IBED polycrystalline VO2 films had a single [002] orientation of VO2(M). The TCR of 5at.%W and 7at.% Ta doped Vanadium Dioxide Polycrystalline Films were high up to -18%/K and -12%/K at room temperature, respectively. Using 7at.% Ta and 2at.% Ti co-doping, the TCR of the co-doped vanadium oxide film was -7%/K and without hysteresis during temperature increasing and decresing from 0-80°C. It should indicate that the W-doped vanadium dioxide films colud be used for high sensing IR detect and the Ta/Ti co-doped film without hysteresis is suitable for infrarid imaging application.

Spatial distribution of vanadium and microbial community responses in surface soil of Panzhihua mining and smelting area, China.

PubMed

Cao, Xuelong; Diao, Muhe; Zhang, Baogang; Liu, Hui; Wang, Song; Yang, Meng

2017-09-01

Spatial distribution of vanadium in surface soils from different processing stages of vanadium-bearing titanomagnetite in Panzhihua mining and smelting area (China) as well as responses of microbial communities including bacteria and fungi to vanadium were investigated by fieldwork and laboratory incubation experiment. The vanadium contents in this region ranged from 149.3 to 4793.6 mg kg -1 , exceeding the soil background value of vanadium in China (82 mg kg -1 ) largely. High-throughput DNA sequencing results showed bacterial communities from different manufacturing locations were quite diverse, but Bacteroidetes and Proteobacteria were abundant in all samples. The contents of organic matter, available P, available S and vanadium had great influences on the structures of bacterial communities in soils. Bacterial communities converged to similar structure after long-term (240 d) cultivation with vanadium containing medium, dominating by bacteria which can tolerate or reduce toxicities of heavy metals. Fungal diversities decreased after cultivation, but Ascomycota and Ciliophora were still the most abundant phyla as in the original soil samples. Results in this study emphasize the urgency of investigating vanadium contaminations in soils and provide valuable information on how vanadium contamination influences bacterial and fungal communities. Copyright © 2017 Elsevier Ltd. All rights reserved.

The toxicity of vanadium on gastrointestinal, urinary and reproductive system, and its influence on fertility and fetuses malformations.

PubMed

Wilk, Aleksandra; Szypulska-Koziarska, Dagmara; Wiszniewska, Barbara

2017-09-25

Vanadium is a transition metal that has a unique and beneficial effect on both humans and animals. For many years, studies have suggested that vanadium is an essential trace element. Its biological properties are of interest due to its therapeutic potential, including in the treatment of diabetes mellitus. Vanadium deficiencies can lead to a range of pathologies. However, excessive concentration of this metal can cause irreversible damage to various tissues and organs. Vanadium toxicity mainly manifests in gastrointestinal symptoms, including diarrhea, vomiting, and weight reduction. Vanadium also exhibits hepatotoxic and nephrotoxic properties, including glomerulonephritis and pyelonephritis. Vanadium compounds may also lead to partial degeneration of the seminiferous epithelium of the seminiferous tubules in the testes and can affect male fertility. This paper describes the harmful effects of vanadium on the morphology and physiology of both animal and human tissues, including the digestive system, the urinary tract, and the reproductive system. What is more, the following study includes data concerning the correlation between the above-mentioned metal and its influence on fertility and fetus malformations. 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.

Iron Carbides in Fischer–Tropsch Synthesis: Theoretical and Experimental Understanding in Epsilon-Iron Carbide Phase Assignment

DOE PAGES

Liu, Xing-Wu; Cao, Zhi; Zhao, Shu; ...

2017-09-11

As active phases in low-temperature Fischer–Tropsch synthesis for liquid fuel production, epsilon iron carbides are critically important industrial materials. However, the precise atomic structure of epsilon iron carbides remains unclear, leading to a half-century of debate on the phase assignment of the ε-Fe 2C and ε’-Fe 2.2C. Here, we resolve this decades-long question by a combining theoretical and experimental investigation to assign the phases unambiguously. First, we have investigated the equilibrium structures and thermal stabilities of ε-Fe xC, (x = 1, 2, 2.2, 3, 4, 6, 8) by first-principles calculations. We have also acquired X-ray diffraction patterns and Mössbauer spectramore » for these epsilon iron carbides, and compared them with the simulated results. These analyses indicate that the unit cell of ε-Fe 2C contains only one type of chemical environment for Fe atoms, while ε’-Fe 2.2C has six sets of chemically distinct Fe atoms.« less

Method for producing silicon nitride/silicon carbide composite

DOEpatents

Dunmead, Stephen D.; Weimer, Alan W.; Carroll, Daniel F.; Eisman, Glenn A.; Cochran, Gene A.; Susnitzky, David W.; Beaman, Donald R.; Nilsen, Kevin J.

1996-07-23

Silicon carbide/silicon nitride composites are prepared by carbothermal reduction of crystalline silica powder, carbon powder and optionally crsytalline silicon nitride powder. The crystalline silicon carbide portion of the composite has a mean number diameter less than about 700 nanometers and contains nitrogen.

Silicon Carbide Metallization

NASA Astrophysics Data System (ADS)

Lescoat, F.; Tanguy, F.; Durand, P.

2016-05-01

A study has been done to assess the feasibility of metallization of Silicon Carbide (SiC) in order to simplify design and mounting of one or more ground reference rail needed to provide an electrical reference for electronics mounted on an SiC structure.

Superconducting and Magnetic Properties of Vanadium/iron Superlattices.

NASA Astrophysics Data System (ADS)

Wong, Hong-Kuen

A novel ultrahigh vacuum evaporator was constructed for the preparation of superlattice samples. The thickness control was much better than an atomic plane. With this evaporator we prepared V/Fe superlattice samples on (0001) sapphire substrates with different thicknesses. All samples showed a good bcc(110) structure. Mossbauer experiments showed that the interface mixing extended a distance of about one atomic plane indicating an almost rectangular composition profile. Because of this we were able to prepare samples with layer thickness approaching one atomic plane. Even with ultrathin Fe layers, the samples are ferromagnetic, at least at lower temperatures. Superparamagnetism and spin glass states were not seen. In the absence of an external field, the magnetic moments lie close to the film plane. In addition to this shape anisotropy, there is some uniaxial anisotropy. No magnetic dead layers have been observed. The magnetic moments within the Fe layers vary little with the distance from the interfaces. At the interfaces the Fe moment is reduced and an antiparallel moment is induced on the vanadium atoms. It is observed that ultrathin Fe layers behave in a 2D fashion when isolated by sufficiently thick vanadium layers; however, on thinning the vanadium layers, a magnetic coupling between the Fe layers has been observed. We also studied the superconducting properties of V/Fe sandwiches and superlattices. In both cases, the Fe layer, a strong pair-breaker, suppresses the superconducting transition temperature consistent with the current knowledge of the magnetic proximity effect. For the sandwiches with thin (thick) vanadium layers, the temperature dependence of the upper critical fields is consistent with the simple theory for a 2D (3D) superconductor. For the superlattices, when the vanadium layer is on the order of the BCS coherence length and the Fe layer is only a few atomic planes thick, a 2D-3D crossover has been observed in the temperature dependence of the

Cottonseed meal, dehydrated grass and ascorbic acid as dietary factors preventing toxicity of vanadium for the chick

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berg, L.R.; Lawrence, W.W.

1971-01-01

Studies have been conducted which show that the replacement of 5% sucrose in a sucrose-fish meal diet for chicks with degossypolized cottonseed meal prevents the toxicity of 20 ppm added vanadium. The addition of 5% dehydrated grass to the same ration markedly reduced the toxicity symptoms. No such reduction in vanadium toxicity resulted when soybean meal, corn gluten meal, meat meal, fish meal, casein, isolated soybean protein, zein or wheat gluten were added to the ration. No evidence was found that the gossypol remaining in the cottonseed meal was the detoxifying agent. The addition of 0.25 to 0.50% ascorbic acidmore » to the sucrose-fish meal basal ration prevented the toxic symptoms resulting from the addition of 20 ppm vanadium derived from HN/sub 4/VO/sub 3/. The vanadium derived from VOSO/sub 4/ and VOCl/sub 2/ (vanadium valence 4) was as toxic as vanadium derived from HN/sub 4/VO/sub 3/ (V = valence 5). This leads one to question that the action of ascorbic acid in reducing vanadium toxicity is through its property of a reducing agent which might change the vanadium in VH/sub 4/VO/sub 3/ to a lower valence, presumably less toxic.« less

Fabrication of thorium bearing carbide fuels

DOEpatents

Gutierrez, R.L.; Herbst, R.J.; Johnson, K.W.R.

Thorium-uranium carbide and thorium-plutonium carbide fuel pellets have been fabricated by the carbothermic reduction process. Temperatures of 1750/sup 0/C and 2000/sup 0/C were used during the reduction cycle. Sintering temperatures of 1800/sup 0/C and 2000/sup 0/C were used to prepare fuel pellet densities of 87% and > 94% of theoretical, respectively. The process allows the fabrication of kilogram quantities of fuel with good reproductibility of chemical and phase composition.

Vanadium Microalloyed High Strength Martensitic Steel Sheet for Hot-Dip Coating

NASA Astrophysics Data System (ADS)

Hutchinson, Bevis; Komenda, Jacek; Martin, David

Cold rolled steels with various vanadium and nitrogen levels have been treated to simulate the application of galvanizing and galvannealing to hardened martensitic microstructures. Strength levels were raised 100-150MPa by alloying with vanadium, which mitigates the effect of tempering. This opens the way for new ultra-high strength steels with corrosion resistant coatings produced by hot dip galvanising.

Varying potential silicon carbide gas sensor

NASA Technical Reports Server (NTRS)

Shields, Virgil B. (Inventor); Ryan, Margaret A. (Inventor); Williams, Roger M. (Inventor)

1997-01-01

A hydrocarbon gas detection device operates by dissociating or electro-chemically oxidizing hydrocarbons adsorbed to a silicon carbide detection layer. Dissociation or oxidation are driven by a varying potential applied to the detection layer. Different hydrocarbon species undergo reaction at different applied potentials so that the device is able to discriminate among various hydrocarbon species. The device can operate at temperatures between 100.degree. C. and at least 650.degree. C., allowing hydrocarbon detection in hot exhaust gases. The dissociation reaction is detected either as a change in a capacitor or, preferably, as a change of current flow through an FET which incorporates the silicon carbide detection layers. The silicon carbide detection layer can be augmented with a pad of catalytic material which provides a signal without an applied potential. Comparisons between the catalytically produced signal and the varying potential produced signal may further help identify the hydrocarbon present.

Effect of Sulfuric and Triflic Acids on the Hydration of Vanadium Cations: An ab Initio Study.

PubMed

Sepehr, Fatemeh; Paddison, Stephen J

2015-06-04

Vanadium redox flow batteries (VRFBs) may be a promising solution for large-scale energy storage applications, but the crossover of any of the redox active species V(2+), V(3+), VO(2+), and VO2(+) through the ion exchange membrane will result in self-discharge of the battery. Hence, a molecular level understanding of the states of vanadium cations in the highly acidic environment of a VRFB is needed. We examine the effects of sulfuric and triflic (CF3SO3H) acids on the hydration of vanadium species as they mimic the electrolyte and functional group of perfluorosulfonic acid (PFSA) membranes. Hybrid density functional theory in conjunction with a continuum solvation model was utilized to obtain the local structures of the hydrated vanadium cations in proximity to H2SO4, CF3SO3H, and their conjugate anions. The results indicate that none of these species covalently bond to the vanadium cations. The hydration structure of V(3+) is more distorted than that of V(2+) in an acidic medium. The oxo-group of VO2(+) is protonated by either acid, in contrast to VO(2+) which is not protonated. The atomic partial charge of the four oxidation states of vanadium varies from +1.7 to +2.0. These results provide the local solvation structures of vanadium cations in the VRFBs environment that are directly related to the electrolytes stability and diffusion of vanadium ions into the membrane.

Chemical vapour deposition: Transition metal carbides go 2D

DOE PAGES

Gogotsi, Yury

2015-08-17

Here, the research community has been steadily expanding the family of few-atom-thick crystals beyond graphene, discovering new materials or producing known materials in a 2D state and demonstrating their unique properties 1, 2. Recently, nanometre-thin 2D transition metal carbides have also joined this family 3. Writing in Nature Materials, Chuan Xu and colleagues now report a significant advance in the field, showing the synthesis of large-area, high-quality, nanometre-thin crystals of molybdenum carbide that demonstrate low-temperature 2D superconductivity 4. Moreover, they also show that other ultrathin carbide crystals, such as tungsten and tantalum carbides, can be grown by chemical vapour depositionmore » with a high crystallinity and very low defect concentration.« less

Iron Carbides and Nitrides: Ancient Materials with Novel Prospects.

PubMed

Ye, Zhantong; Zhang, Peng; Lei, Xiang; Wang, Xiaobai; Zhao, Nan; Yang, Hua

2018-02-07

Iron carbides and nitrides have aroused great interest in researchers, due to their excellent magnetic properties, good machinability and the particular catalytic activity. Based on these advantages, iron carbides and nitrides can be applied in various areas such as magnetic materials, biomedical, photo- and electrocatalysis. In contrast to their simple elemental composition, the synthesis of iron carbides and nitrides still has great challenges, particularly at the nanoscale, but it is usually beneficial to improve performance in corresponding applications. In this review, we introduce the investigations about iron carbides and nitrides, concerning their structure, synthesis strategy and various applications from magnetism to the catalysis. Furthermore, the future prospects are also discussed briefly. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hugoniot equation of state and dynamic strength of boron carbide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grady, Dennis E.

Boron carbide ceramics have been particularly problematic in attempts to develop adequate constitutive model descriptions for purposes of analysis of dynamic response in the shock and impact environment. Dynamic strength properties of boron carbide ceramic differ uniquely from comparable ceramics. Furthermore, boron carbide is suspected, but not definitely shown, to undergoing polymorphic phase transformation under shock compression. In the present paper, shock-wave compression measurements conducted over the past 40 years are assessed for the purpose of achieving improved understanding of the dynamic equation of state and strength of boron carbide. In particular, attention is focused on the often ignored Losmore » Alamos National Laboratory (LANL) Hugoniot measurements performed on porous sintered boron carbide ceramic. The LANL data are shown to exhibit two compression anomalies on the shock Hugoniot within the range of 20–60 GPa that may relate to crystallographic structure transitions. More recent molecular dynamics simulations on the compressibility of the boron carbide crystal lattice reveal compression transitions that bear similarities to the LANL Hugoniot results. The same Hugoniot data are complemented with dynamic isentropic compression data for boron carbide extracted from Hugoniot measurements on boron carbide and copper granular mixtures. Other Hugoniot measurements, however, performed on near-full-density boron carbide ceramic differ markedly from the LANL Hugoniot data. These later data exhibit markedly less compressibility and tend not to show comparable anomalies in compressibility. Alternative Hugoniot anomalies, however, are exhibited by the near-full-density data. Experimental uncertainty, Hugoniot strength, and phase transformation physics are all possible explanations for the observed discrepancies. It is reasoned that experimental uncertainty and Hugoniot strength are not likely explanations for the observed differences. The notable

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

PubMed

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.

METHOD FOR COATING GRAPHITE WITH METALLIC CARBIDES

DOEpatents

Steinberg, M.A.

1960-03-22

A method for producing refractory coatings of metallic carbides on graphite was developed. In particular, the graphite piece to be coated is immersed in a molten solution of 4 to 5% by weight of zirconium, titanium, or niobium dissolved in tin. The solution is heated in an argon atmosphere to above 1400 deg C, whereby the refractory metal reacts with the surface of the graphite to form a layer of metalic carbide. The molten solution is cooled to 300 to 400 deg C, and the graphite piece is removed. Excess tin is wiped from the graphite, which is then heated in vacuum to above 2300 deg C. The tin vaporizes from the graphite surface, leaving the surface coated with a tenacious layer of refractory metallic carbide.

Intramuscular Immunization of Mice with the Live-Attenuated Herpes Simplex Virus 1 Vaccine Strain VC2 Expressing Equine Herpesvirus 1 (EHV-1) Glycoprotein D Generates Anti-EHV-1 Immune Responses in Mice.

PubMed

Liu, Shiliang A; Stanfield, Brent A; Chouljenko, Vladimir N; Naidu, Shan; Langohr, Ingeborg; Del Piero, Fabio; Ferracone, Jacqueline; Roy, Alma A; Kousoulas, Konstantin G

2017-06-15

Vaccination remains the best option to combat equine herpesvirus 1 (EHV-1) infection, and several different strategies of vaccination have been investigated and developed over the past few decades. Herein, we report that the live-attenuated herpes simplex virus 1 (HSV-1) VC2 vaccine strain, which has been shown to be unable to enter into neurons and establish latency in mice, can be utilized as a vector for the heterologous expression of EHV-1 glycoprotein D (gD) and that the intramuscular immunization of mice results in strong antiviral humoral and cellular immune responses. The VC2-EHV-1-gD recombinant virus was constructed by inserting an EHV-1 gD expression cassette under the control of the cytomegalovirus immediate early promoter into the VC2 vector in place of the HSV-1 thymidine kinase (UL23) gene. The vaccines were introduced into mice through intramuscular injection. Vaccination with both the VC2-EHV-1-gD vaccine and the commercially available vaccine Vetera EHV XP 1/4 (Vetera; Boehringer Ingelheim Vetmedica) resulted in the production of neutralizing antibodies, the levels of which were significantly higher in comparison to those in VC2- and mock-vaccinated animals ( P < 0.01 or P < 0.001). Analysis of EHV-1-reactive IgG subtypes demonstrated that vaccination with the VC2-EHV-1-gD vaccine stimulated robust IgG1 and IgG2a antibodies after three vaccinations ( P < 0.001). Interestingly, Vetera-vaccinated mice produced significantly higher levels of IgM than mice in the other groups before and after challenge ( P < 0.01 or P < 0.05). Vaccination with VC2-EHV-1-gD stimulated strong cellular immune responses, characterized by the upregulation of both interferon- and tumor necrosis factor-positive CD4 + T cells and CD8 + T cells. Overall, the data suggest that the HSV-1 VC2 vaccine strain may be used as a viral vector for the vaccination of horses as well as, potentially, for the vaccination of other economically important animals. IMPORTANCE A novel virus

Why Antidiabetic Vanadium Complexes are Not in the Pipeline of “Big Pharma” Drug Research? A Critical Review

PubMed Central

Scior, Thomas; Guevara-Garcia, Jose Antonio; Do, Quoc-Tuan; Bernard, Philippe; Laufer, Stefan

2016-01-01

Public academic research sites, private institutions as well as small companies have made substantial contributions to the ongoing development of antidiabetic vanadium compounds. But why is this endeavor not echoed by the globally operating pharmaceutical companies, also known as “Big Pharma”? Intriguingly, today’s clinical practice is in great need to improve or replace insulin treatment against Diabetes Mellitus (DM). Insulin is the mainstay therapeutically and economically. So, why do those companies develop potential antidiabetic drug candidates without vanadium (vanadium-free)? We gathered information about physicochemical and pharmacological properties of known vanadium-containing antidiabetic compounds from the specialized literature, and converted the data into explanations (arguments, the “pros and cons”) about the underpinnings of antidiabetic vanadium. Some discoveries were embedded in chronological order while seminal reviews of the last decade about the Medicinal chemistry of vanadium and its history were also listed for further understanding. In particular, the concepts of so-called “noncomplexed or free” vanadium species (i.e. inorganic oxido-coordinated species) and “biogenic speciation” of antidiabetic vanadium complexes were found critical and subsequently documented in more details to answer the question. PMID:26997154

Carbide factor predicts rolling-element bearing fatigue life

NASA Technical Reports Server (NTRS)

Chevalier, J. L.; Zaretsky, E. V.

1973-01-01

Analysis was made to determine correlation between number and size of carbide particles and rolling-element fatigue. Correlation was established, and carbide factor was derived that can be used to predict fatigue life more effectively than such variables as heat treatment, chemical composition, and hardening mechanism.

Structural water engaged disordered vanadium oxide nanosheets for high capacity aqueous potassium-ion storage.

PubMed

Charles, Daniel Scott; Feygenson, Mikhail; Page, Katharine; Neuefeind, Joerg; Xu, Wenqian; Teng, Xiaowei

2017-05-23

Aqueous electrochemical energy storage devices using potassium-ions as charge carriers are attractive due to their superior safety, lower cost and excellent transport properties compared to other alkali ions. However, the accommodation of potassium-ions with satisfactory capacity and cyclability is difficult because the large ionic radius of potassium-ions causes structural distortion and instabilities even in layered electrodes. Here we report that water induces structural rearrangements of the vanadium-oxygen octahedra and enhances stability of the highly disordered potassium-intercalated vanadium oxide nanosheets. The vanadium oxide nanosheets engaged by structural water achieves high capacity (183 mAh g -1 in half-cells at a scan rate of 5 mV s -1 , corresponding to 0.89 charge per vanadium) and excellent cyclability (62.5 mAh g -1 in full cells after 5,000 cycles at 10 C). The promotional effects of structural water on the disordered vanadium oxide nanosheets will contribute to the exploration of disordered structures from earth-abundant elements for electrochemical energy storage.

Structural water engaged disordered vanadium oxide nanosheets for high capacity aqueous potassium-ion storage

DOE PAGES

Charles, Daniel Scott; Feygenson, Mikhail; Page, Katharine; ...

2017-05-23

Aqueous electrochemical energy storage devices using potassium-ions as charge carriers are attractive due to their superior safety, lower cost and excellent transport properties compared to other alkali ions. However, the accommodation of potassium-ions with satisfactory capacity and cyclability is difficult because large ionic radius of potassium-ions causes structural distortion and instabilities even in layered electrodes. Here we report that water induces structural rearrangements of the vanadium-oxygen octahedra and enhances stability of the highly disordered potassium-intercalated vanadium oxide nanosheets. The vanadium oxide nanosheets engaged by structural water achieves high capacity (183 mAh g -1 in half-cells at a scan rate ofmore » 5 mV s -1, corresponding to 0.89 charge per vanadium) and excellent cyclability (62.5 mAh g -1 in full-cells after 5,000 cycles at 10 C). Finally, the promotional effects of structural water on the disordered vanadium oxide nanosheets will contribute to the exploration of disordered structures from earth-abundant elements for electrochemical energy storage.« less

Structural water engaged disordered vanadium oxide nanosheets for high capacity aqueous potassium-ion storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Charles, Daniel Scott; Feygenson, Mikhail; Page, Katharine

Aqueous electrochemical energy storage devices using potassium-ions as charge carriers are attractive due to their superior safety, lower cost and excellent transport properties compared to other alkali ions. However, the accommodation of potassium-ions with satisfactory capacity and cyclability is difficult because large ionic radius of potassium-ions causes structural distortion and instabilities even in layered electrodes. Here we report that water induces structural rearrangements of the vanadium-oxygen octahedra and enhances stability of the highly disordered potassium-intercalated vanadium oxide nanosheets. The vanadium oxide nanosheets engaged by structural water achieves high capacity (183 mAh g -1 in half-cells at a scan rate ofmore » 5 mV s -1, corresponding to 0.89 charge per vanadium) and excellent cyclability (62.5 mAh g -1 in full-cells after 5,000 cycles at 10 C). Finally, the promotional effects of structural water on the disordered vanadium oxide nanosheets will contribute to the exploration of disordered structures from earth-abundant elements for electrochemical energy storage.« less

Method for making hot-pressed fiber-reinforced carbide-graphite composite

DOEpatents

Riley, Robert E.; Wallace Sr., Terry C.

1979-01-01

A method for the chemical vapor deposition of a uniform coating of tantalum metal on fibers of a woven graphite cloth is described. Several layers of the coated cloth are hot pressed to produce a tantalum carbide-graphite composite having a uniformly dispersed, fine grained tantalum carbide in graphite with compositions in the range of 15 to 40 volume percent tantalum carbide.

Cathepsin B Cleavage of vcMMAE-Based Antibody-Drug Conjugate Is Not Drug Location or Monoclonal Antibody Carrier Specific.

PubMed

Gikanga, Benson; Adeniji, Nia S; Patapoff, Thomas W; Chih, Hung-Wei; Yi, Li

2016-04-20

Antibody-drug conjugates (ADCs) require thorough characterization and understanding of product quality attributes. The framework of many ADCs comprises one molecule of antibody that is usually conjugated with multiple drug molecules at various locations. It is unknown whether the drug release rate from the ADC is dependent on drug location, and/or local environment, dictated by the sequence and structure of the antibody carrier. This study addresses these issues with valine-citrulline-monomethylauristatin E (vc-MMAE)-based ADC molecules conjugated at reduced disulfide bonds, by evaluating the cathepsin B catalyzed drug release rate of ADC molecules with different drug distributions or antibody carriers. MMAE drug release rates at different locations on ADC I were compared to evaluate the impact of drug location. No difference in rates was observed for drug released from the V(H), V(L), or C(H)2 domains of ADC I. Furthermore, four vc-MMAE ADC molecules were chosen as substrates for cathepsin B for evaluation of Michaelis-Menten parameters. There was no significant difference in K(M) or k(cat) values, suggesting that different sequences of the antibody carrier do not result in different drug release rates. Comparison between ADCs and small molecules containing vc-MMAE moieties as substrates for cathepsin B suggests that the presence of IgG1 antibody carrier, regardless of its bulkiness, does not impact drug release rate. Finally, a molecular dynamics simulation on ADC II revealed that the val-cit moiety at each of the eight possible conjugation sites was, on average, solvent accessible over 50% of its maximum solvent accessible surface area (SASA) during a 500 ns trajectory. Combined, these results suggest that the cathepsin cleavage sites for conjugated drugs are exposed enough for the enzyme to access and that the drug release rate is rather independent of drug location or monoclonal antibody carrier. Therefore, the distribution of drug conjugation at different

Effect of vanadium on colonic aberrant crypt foci induced in rats by 1,2 Dimethyl hydrazine

PubMed Central

Kanna, P Suresh; Mahendrakumar, CB; Chakraborty, T; Hemalatha, P; Banerjee, Pratik; Chatterjee, M

2003-01-01

AIM: To investigate the chemo preventive effects of vanadium on rat colorectal carcinogenesis induced by 1,2-dimethylhydrazine (DMH). METHODS: Male Sprague-Dawley Rats were randomly divided into four groups. Rats in Group A received saline vehicle alone for 16 weeks. Rats in Group B were given DMH injection once a week intraperitoneally for 16 weeks; rats in Group C, with the same DMH treatment as in the Group B, but received 0.5-ppm vanadium in the form ammonium monovanadate ad libitum in drinking water. Rats in the Group D received vanadium alone as in the Group C without DMH injection. RESULTS: Aberrant crypt foci (ACF) were formed in animals in DMH-treated groups at the end of week 16. Compared to DMH group, vanadium treated group had less ACF (P < 0.001). At the end of week 32, all rats in DMH group developed large intestinal tumors. Rats treated with vanadium contained significantly few colonic adenomas and carcinomas (P < 0.05) compared to rats administered DMH only. In addition, a significant reduction (P < 0.05) in colon tumor burden (sum of tumor sizes per animal) was also evident in animals of Group C when compared to those in rats of carcinogen control Group B. The results also showed that vanadium significantly lowered PCNA index in ACF (P < 0.005). Furthermore, vanadium supplementation also elevated liver GST and Cyt P-450 activities (P < 0.001 and P < 0.02, respectively). CONCLUSION: Vanadium in the form of ammonium monovanadate supplemented in drinking water ad libitum has been found to be highly effective in reducing tumor incidence and preneoplastic foci on DMH-induced colorectal carcinogenesis. These findings suggest that vanadium administration can suppress colon carcinogenesis in rats. PMID:12717849

Flexural strength of proof-tested and neutron-irradiated silicon carbide

NASA Astrophysics Data System (ADS)

Price, R. J.; Hopkins, G. R.

1982-08-01

Proof testing before service is a valuable method for ensuring the reliability of ceramic structures. Silicon carbide has been proposed as a very low activation first-wall and blanket structural material for fusion devices, where it would experience a high flux of fast neutrons. Strips of three types of silicon carbide were loaded in four-point bending to a stress sufficient to break about a third of the specimens. Groups of 16 survivors were irradiated to 2 × 10 26n/ m2 ( E>0.05 MeV) at 740°C and bend tested to failure. The strength distribution of chemically vapor-deposited silicon carbide (Texas Instruments) was virtually unchanged by irradiation. The mean strength of sintered silicon carbide (Carborundum Alpha) was reduced 34% by irradiation, while the Weibull modulus and the truncated strength distribution characteristic of proof-tested material were retained. Irradiation reduced the mean strength of reaction-bonded silicon carbide (Norton NC-430) by 58%, and the spread in strength values was increased. We conclude that for the chemically vapor-deposited and the sintered silicon carbide the benefits of proof testing to eliminate low strength material are retained after high neutron exposures.

Vanadium Transitions in the Spectrum of Arcturus

NASA Astrophysics Data System (ADS)

Wood, M. P.; Sneden, C.; Lawler, J. E.; Den Hartog, E. A.; Cowan, J. J.; Nave, G.

2018-02-01

We derive a new abundance for vanadium in the bright, mildly metal-poor red giant Arcturus. This star has an excellent high-resolution spectral atlas and well-understood atmospheric parameters, and it displays a rich set of neutral vanadium lines that are available for abundance extraction. We employ a newly recorded set of laboratory FTS spectra to investigate any potential discrepancies in previously reported V I log(gf) values near 900 nm. These new spectra support our earlier laboratory transition data and the calibration method utilized in that study. We then perform a synthetic spectrum analysis of weak V I features in Arcturus, deriving log ε(V) = 3.54 ± 0.01 (σ = 0.04) from 55 lines. There are no significant abundance trends with wavelength, line strength, or lower excitation energy.

MC Carbide Characterization in High Refractory Content Powder-Processed Ni-Based Superalloys

NASA Astrophysics Data System (ADS)

Antonov, Stoichko; Chen, Wei; Huo, Jiajie; Feng, Qiang; Isheim, Dieter; Seidman, David N.; Sun, Eugene; Tin, Sammy

2018-04-01

Carbide precipitates in Ni-based superalloys are considered to be desirable phases that can contribute to improving high-temperature properties as well as aid in microstructural refinement of the material; however, they can also serve as crack initiation sites during fatigue. To date, most of the knowledge pertaining to carbide formation has originated from assessments of cast and wrought Ni-based superalloys. As powder-processed Ni-based superalloys are becoming increasingly widespread, understanding the different mechanisms by which they form becomes increasingly important. Detailed characterization of MC carbides present in two experimental high Nb-content powder-processed Ni-based superalloys revealed that Hf additions affect the resultant carbide morphologies. This morphology difference was attributed to a higher magnitude of elastic strain energy along the interface associated with Hf being soluble in the MC carbide lattice. The composition of the MC carbides was studied through atom probe tomography and consisted of a complex carbonitride core, which was rich in Nb and with slight Hf segregation, surrounded by an Nb carbide shell. The characterization results of the segregation behavior of Hf in the MC carbides and the subsequent influence on their morphology were compared to density functional theory calculations and found to be in good agreement, suggesting that computational modeling can successfully be used to tailor carbide features.

MC Carbide Characterization in High Refractory Content Powder-Processed Ni-Based Superalloys

NASA Astrophysics Data System (ADS)

Antonov, Stoichko; Chen, Wei; Huo, Jiajie; Feng, Qiang; Isheim, Dieter; Seidman, David N.; Sun, Eugene; Tin, Sammy

2018-06-01

Carbide precipitates in Ni-based superalloys are considered to be desirable phases that can contribute to improving high-temperature properties as well as aid in microstructural refinement of the material; however, they can also serve as crack initiation sites during fatigue. To date, most of the knowledge pertaining to carbide formation has originated from assessments of cast and wrought Ni-based superalloys. As powder-processed Ni-based superalloys are becoming increasingly widespread, understanding the different mechanisms by which they form becomes increasingly important. Detailed characterization of MC carbides present in two experimental high Nb-content powder-processed Ni-based superalloys revealed that Hf additions affect the resultant carbide morphologies. This morphology difference was attributed to a higher magnitude of elastic strain energy along the interface associated with Hf being soluble in the MC carbide lattice. The composition of the MC carbides was studied through atom probe tomography and consisted of a complex carbonitride core, which was rich in Nb and with slight Hf segregation, surrounded by an Nb carbide shell. The characterization results of the segregation behavior of Hf in the MC carbides and the subsequent influence on their morphology were compared to density functional theory calculations and found to be in good agreement, suggesting that computational modeling can successfully be used to tailor carbide features.

Versatile Boron Carbide-Based Visual Obscurant Compositions for Smoke Munitions

DTIC Science & Technology

2015-04-17

Versatile Boron Carbide-Based Visual Obscurant Compositions for Smoke Munitions Anthony P. Shaw,*,† Giancarlo Diviacchi,‡ Ernest L. Black,‡ Jared D...have been demonstrated to produce thick white smoke clouds upon combustion. These compositions use powdered boron carbide (B4C) as a pyrotechnic...ignition and are safe to handle. KEYWORDS: Smoke, Obscurants, Pyrotechnics, Boron carbide, Sustainable chemistry ■ INTRODUCTION Visible obscuration

Plasma metallurgical production of nanocrystalline borides and carbides

NASA Astrophysics Data System (ADS)

Galevsky, G. V.; Rudneva, V. V.; Cherepanov, A. N.; Galevsky, S. G.; Efimova, K. A.

2016-09-01

he experience in production and study of properties of nanocrystalline borides and chromium carbides, titanium, silicon was summarized. The design and features of the vertical three-jet once-through reactor with power 150 kW, used in the plasma metallurgical production, was described. The technological, thermotechnical and resource characteristics of the reactor were identified. The parameters of borides and carbides synthesis, their main characteristics in the nanodispersed state and equipment-technological scheme of production were provided. Evaluation of engineering-and-economical performance of the laboratory and industrial levels of borides and carbides production and the state corresponding to the segment of the world market was carried out.

On carbide dissolution in an as-cast ASTM F-75 alloy.

PubMed

Caudillo, M; Herrera-Trejo, M; Castro, M R; Ramírez, E; González, C R; Juárez, J I

2002-02-01

The solution treatment of an as-cast ASTM F-75 alloy was investigated. Microstructural evolution was followed during thermal processing, in particular with regard to the content and type of carbides formed. To evidence any probable carbide transformations occurring during the heating stage, as well as to clarify their effect on the carbide dissolution kinetics, three heating rates were studied. Image analysis and scanning electron microscopy techniques were used for microstructural characterization. For the identification of precipitates, these were electrolytically extracted from the matrix and then analyzed by X-ray diffraction. It was found that the precipitates in the as-cast alloy were constituted by both a M(23)C(6) carbide and a sigma intermetallic phase. The M(23)C(6) carbide was the only phase identified in solution-treated specimens, regardless of the heating rate employed, which indicated that this carbide dissolved directly into the matrix without being transformed first into an M(6)C carbide, as reported in the literature. It was found that the kinetics of dissolution for the M(23)C(6) carbide decreased progressively during the solution treatment, and that it was sensitive to the heating rate, decreasing whenever the latter was decreased. Because the M(23)C(6) carbide was not observed to suffer a phase transformation prior to its dissolution into the matrix, the effect of the heating rate was associated to the morphological change occurred as the specimens were heated. The occurrence of the observed phases was analyzed with the aid of phase diagrams computed for the system Co-Cr-Mo-C. Copyright 2001 John Wiley & Sons, Inc. J Biomed Mater Res 59: 378-385, 2002

Critical V2O5/TeO2 Ratio Inducing Abrupt Property Changes in Vanadium Tellurite Glasses.

PubMed

Kjeldsen, Jonas; Rodrigues, Ana C M; Mossin, Susanne; Yue, Yuanzheng

2014-12-26

Transition metal containing glasses have unique electrical properties and are therefore often used for electrochemical applications, such as in batteries. Among oxide glasses, vanadium tellurite glasses exhibit the highest electronic conductivity and thus the high potential for applications. In this work, we investigate how the dynamic and physical properties vary with composition in the vanadium tellurite system. The results show that there exists a critical V(2)O(5) concentration of 45 mol %, above which the local structure is subjected to a drastic change with increasing V(2)O(5), leading to abrupt changes in both hardness and liquid fragility. Electronic conductivity does not follow the expected correlation to the valence state of the vanadium as predicted by the Mott-Austin equation but shows a linear correlation to the mean distance between vanadium ions. These findings could contribute to designing optimum vanadium tellurite compositions for electrochemical devices. The work gives insight into the mechanism of electron conduction in the vanadium tellurite systems.

Improved capacitance characteristics of electrospun ACFs by pore size control and vanadium catalyst.

PubMed

Im, Ji Sun; Woo, Sang-Wook; Jung, Min-Jung; Lee, Young-Seak

2008-11-01

Nano-sized carbon fibers were prepared by using electrospinning, and their electrochemical properties were investigated as a possible electrode material for use as an electric double-layer capacitor (EDLC). To improve the electrode capacitance of EDLC, we implemented a three-step optimization. First, metal catalyst was introduced into the carbon fibers due to the excellent conductivity of metal. Vanadium pentoxide was used because it could be converted to vanadium for improved conductivity as the pore structure develops during the carbonization step. Vanadium catalyst was well dispersed in the carbon fibers, improving the capacitance of the electrode. Second, pore-size development was manipulated to obtain small mesopore sizes ranging from 2 to 5 nm. Through chemical activation, carbon fibers with controlled pore sizes were prepared with a high specific surface and pore volume, and their pore structure was investigated by using a BET apparatus. Finally, polyacrylonitrile was used as a carbon precursor to enrich for nitrogen content in the final product because nitrogen is known to improve electrode capacitance. Ultimately, the electrospun activated carbon fibers containing vanadium show improved functionality in charge/discharge, cyclic voltammetry, and specific capacitance compared with other samples because of an optimal combination of vanadium, nitrogen, and fixed pore structures.

Thermal conductivity behavior of boron carbides

NASA Technical Reports Server (NTRS)

Wood, C.; Zoltan, A.; Emin, D.; Gray, P. E.

1983-01-01

Knowledge of the thermal conductivity of boron carbides is necessary to evaluate its potential for high temperature thermoelectric energy conversion applications. The thermal diffusivity of hot pressed boron carbide B/sub 1-x/C/sub x/ samples as a function of composition, temperature and temperature cycling was measured. These data in concert with density and specific heat data yield the thermal conductivities of these materials. The results in terms of a structural model to explain the electrical transport data and novel mechanisms for thermal conduction are discussed.

Chemical and structural characterization of boron carbide powders and ceramics

NASA Astrophysics Data System (ADS)

Kuwelkar, Kanak Anant

Boron carbide is the material of choice for lightweight armor applications due to its extreme hardness, high Young's modulus and low specific weight. The homogeneity range in boron carbide extends from 9 to 20 at% carbon with the solubility limits not uniquely defined in literature. Over the homogeneity range, the exact lattice positions of boron and carbon atoms have not been unambiguously established, and this topic has been the consideration of significant debate over the last 60 years. The atomic configuration and positions of the boron and carbon atoms play a key role in the crystal structure of the boron carbide phases. Depending on the atomic structure, boron carbide exhibits different mechanical properties which may alter its ballistic performance under extreme dynamic conditions. This work focusses on refinement and development of analytical and chemical methods for an accurate determination of the boron carbide stoichiometry. These methods were then utilized to link structural changes of boron carbide across the solubility range to variations in mechanical properties. After an extensive assessment of the currently employed characterization techniques, it was discerned that the largest source of uncertainty in the determination of the boron carbide stoichiometry was found to arise from the method utilized to evaluate the free carbon concentration. To this end, a modified spiking technique was introduced for free carbon determination where curve fitting techniques were employed to model the asymmetry of the 002 free carbon diffraction peak based on the amorphous, disordered and graphitic nature of carbon. A relationship was then established between the relative intensities of the carbon and boron carbide peaks to the percentage of added carbon and the free-carbon content was obtained by extrapolation. Samples with varying chemistry and high purity were synthesized across the solubility range by hot pressing mixtures of amorphous boron and boron carbide

40 CFR 415.30 - Applicability; description of the calcium carbide production subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... calcium carbide production subcategory. 415.30 Section 415.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbide Production Subcategory § 415.30 Applicability; description of the calcium... the production of calcium carbide in uncovered furnaces. ...

40 CFR 415.30 - Applicability; description of the calcium carbide production subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... calcium carbide production subcategory. 415.30 Section 415.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbide Production Subcategory § 415.30 Applicability; description of the calcium... the production of calcium carbide in uncovered furnaces. ...

40 CFR 415.30 - Applicability; description of the calcium carbide production subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... calcium carbide production subcategory. 415.30 Section 415.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbide Production Subcategory § 415.30 Applicability; description of the calcium... the production of calcium carbide in uncovered furnaces. ...

40 CFR 415.30 - Applicability; description of the calcium carbide production subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... calcium carbide production subcategory. 415.30 Section 415.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbide Production Subcategory § 415.30 Applicability; description of the calcium... the production of calcium carbide in uncovered furnaces. ...

40 CFR 415.30 - Applicability; description of the calcium carbide production subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... calcium carbide production subcategory. 415.30 Section 415.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbide Production Subcategory § 415.30 Applicability; description of the calcium... the production of calcium carbide in uncovered furnaces. ...

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

PubMed

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.

Inverse association of plasma vanadium levels with newly diagnosed type 2 diabetes in a Chinese population.

PubMed

Wang, Xia; Sun, Taoping; Liu, Jun; Shan, Zhilei; Jin, Yilin; Chen, Sijing; Bao, Wei; Hu, Frank B; Liu, Liegang

2014-08-15

Vanadium compounds have been proposed to have beneficial effects on the pathogenesis and complications of type 2 diabetes. Our objective was to evaluate the association between plasma vanadium levels and type 2 diabetes. We performed a case-control study involving 1,598 Chinese subjects with or without newly diagnosed type 2 diabetes (December 2004-December 2007). Cases and controls were frequency-matched by age and sex. Plasma vanadium concentrations were measured and compared between groups. Analyses showed that plasma vanadium concentrations were significantly lower in cases with newly diagnosed type 2 diabetes than in controls (P = 0.001). Mean plasma vanadium levels in participants with and without diabetes were 1.0 μg/L and 1.2 μg/L, respectively. Participants in the highest quartile of plasma vanadium concentration had a notably lower risk of newly diagnosed type 2 diabetes (odds ratio = 0.26, 95% confidence interval: 0.19, 0.35; P < 0.001), compared with persons in the lowest quartile. The trend remained significant after adjustment for known risk factors and in further stratification analyses. Our results suggested that plasma vanadium concentrations were inversely associated with newly diagnosed type 2 diabetes in this Chinese population. © The Author 2014. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Feasibility study of fluxless brazing cemented carbides to steel

NASA Astrophysics Data System (ADS)

Tillmann, W.; Sievers, N.

2017-03-01

One of the most important brazing processes is the joints between cemented carbides and steel for the tool industry such as in rotary drill hammers or saw blades. Even though this technique has already been used for several decades, defects in the joint can still occur and lead to quality loss. Mostly, the joining process is facilitated by induction heating and the use of a flux to enhance the wetting of the filler alloy on the surface of the steel and cemented carbide in an ambient atmosphere. However, although the use of flux enables successful joining, it also generates voids within the joint, which reduces the strength of the connection while the chemicals within the flux are toxic and polluting. In this feasibility study, a fluxless brazing process is used to examine the joint between cemented carbides and steel for the first time. For this, ultrasound is applied during induction heating to enable the wetting between the liquid filler metal and the surfaces of the cemented carbide and steel. The ultrasound generates cavitations within the liquid filler metal, which remove the oxides from the surface. Several filler metals such as a silver based alloy Ag449, pure Zn, and an AlSi-alloy were used to reduce the brazing temperature and to lower the thermal residual stresses within the joint. As a result, every filler metal successfully wetted both materials and led to a dense connection. The ultrasound has to be applied carefully to prevent a damage of the cemented carbide. In this regard, it was observed that single grains of the cemented carbide broke out and remained in the joint. This positive result of brazing cemented carbides to steel without a flux but using ultrasound, allows future studies to focus on the shear strength of these joints as well as the behavior of the thermally induced residual stresses.

Processing and characterization of boron carbide-hafnium diboride ceramics

NASA Astrophysics Data System (ADS)

Brown-Shaklee, Harlan James

Hafnium diboride based ceramics are promising candidate materials for advanced aerospace and nuclear reactor components. The effectiveness of boron carbide and carbon as HfB2 sintering additives was systematically evaluated. In the first stage of the research, boron carbide and carbon additives were found to improve the densification behavior of milled HfB2 powder in part by removing oxides at the HfB2 surface during processing. Boron carbide additives reduced the hot pressing temperature of HfB2 by 150°C compared to carbon, which reduced the hot pressing temperature by ˜50°C. Reduction of oxide impurities alone could not explain the difference in sintering enhancement, however, and other mechanisms of enhancement were evaluated. Boron carbides throughout the homogeneity range were characterized to understand other mechanisms of sintering enhancement in HfB2. Heavily faulted carbon rich and boron rich boron carbides were synthesized for addition to HfB2. The greatest enhancement to densification was observed in samples containing boron- and carbon-rich compositions whereas B6.5 C provided the least enhancement to densification. It is proposed that carbon rich and boron rich boron carbides create boron and hafnium point defects in HfB2, respectively, which facilitate densification. Evaluation of the thermal conductivity (kth) between room temperature and 2000°C suggested that the stoichiometry of the boron carbide additives did not significantly affect kth of HfB2-BxC composites. The improved sinterability and the high kth (˜110 W/m-K at 300K and ˜90 W/m-K at 1000°C ) of HfB2-BxC ceramics make them excellent candidates for isotopically enriched reactor control materials.

Self-repairing vanadium-zirconium composite conversion coating for aluminum alloys

NASA Astrophysics Data System (ADS)

Zhong, Xin; Wu, Xiaosong; Jia, Yuyu; Liu, Yali

2013-09-01

In this paper, new self-repairing vanadium-zirconium composite conversion coating was prepared and investigated by Electrochemical impedance spectra (EIS), Scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. EIS results showed that V-Zr conversion coating with hydrogen peroxide modified (VZO) revealed an increasing corrosion resistance in corrosive media which meant a certain self-repairing effect. SEM comparison photos also disclosed that VZO treated with scratches was gradually ameliorated from the initial cracked configuration to fewer cracks and more fillers through an immersion of 3.5% NaCl solution. XPS results demonstrated that the content of vanadium on VZO increased and zirconium declined when immersed in the corrosive solution. This explained further that the self-repairing ability could be related to vanadium. From the above results, we inferred possible structures of VZO and proposed that self-repairing effect was achieved through a hydrolysis condensation polymerization process of vanadate in the localized corrosion area.

Bipolar resistive switching in room temperature grown disordered vanadium oxide thin-film devices

NASA Astrophysics Data System (ADS)

Wong, Franklin J.; Sriram, Tirunelveli S.; Smith, Brian R.; Ramanathan, Shriram

2013-09-01

We demonstrate bipolar switching with high OFF/ON resistance ratios (>104) in Pt/vanadium oxide/Cu structures deposited entirely at room temperature. The SET (RESET) process occurs when negative (positive) bias is applied to the top Cu electrode. The vanadium oxide (VOx) films are amorphous and close to the vanadium pentoxide stoichiometry. We also investigated Cu/VOx/W structures, reversing the position of the Cu electrode, and found the same polarity dependence with respect to the top and bottom electrodes, which suggests that the bipolar nature is linked to the VOx layer itself. Bipolar switching can be observed at 100 °C, indicating that it not due to a temperature-induced metal-insulator transition of a vanadium dioxide second phase. We discuss how ionic drift can lead to the bipolar electrical behavior of our junctions, similar to those observed in devices based on several other defective oxides. Such low-temperature processed oxide switches could be of relevance to back-end or package integration processing schemes.

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

NASA Astrophysics Data System (ADS)

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.

Detection of qnrVC6, within a new genetic context, in a NDM-1-producing Citrobacter freundii clinical isolate from Uruguay.

PubMed

Bado, Inés; Ezdra, Romina Papa; Cordeiro, Nicolás; Outeda, Matilde; Caiata, Leticia; García-Fulgueiras, Virginia; Seija, Verónica; Vignoli, Rafael

2018-03-08

The objective of the present study was to characterise the mechanisms underlying quinolone and oxyimino-cephalosporin resistance in a Citrobacter freundii clinical isolate obtained from the ICU in Uruguay's University Hospital. Citrobacter freundii strain CF638 was isolated from a urine culture. Identification and susceptibility testing were performed using the VITEK ® 2 system, and MIC determination and disc diffusion assay, respectively. Resistance genes and mobile genetic elements were identified, by PCR and sequencing. Plasmid transfer was assessed by conjugation; plasmid, size was estimated by treatment with S1 and PFGE. Plasmid incompatibility, group and toxin-antitoxin systems were sought by PCR. Strain CF638 showed a multi-drug resistant profile, including, resistance to carbapenemes and quinolones. Transconjugant TcCF638, harbouring a ∼200 kb IncA/C plasmid, also showed resistance to all β-lactams, (except for aztreonam), and diminished susceptibility to ciprofloxacin. PCR, assays were positive for bla NDM-1 and qnrVC in CF638 and TcCF638. Two different class 1 integrons were detected, In127 and In907. In127, featured the genetic array: aadA2-ltr2. Conversely, complex In907 featured, two variable regions (VR); VR-1 consisted of aadB-bla OXA-10 -aadA1cc, whereas, VR-2, featured a gene qnrVC6 108 bp downstream from the ISCR1 and 45 bp, upstream from the qacEΔ1. Expression of qnrVC6 would be on account of a, putative promoter region, detected using the Neural Network Promoter, Prediction program. To the best of our knowledge this constitutes the first report of a qnrVC gene within a complex class 1 integron, and the first report as well of the occurrence of such gene in an NDM-1-producing enterobacterial clinical isolate. Copyright © 2018. Published by Elsevier Ltd.

Effect of tea polyphenols on production performance, egg quality, and hepatic antioxidant status of laying hens in vanadium-containing diets.

PubMed

Yuan, Z H; Zhang, K Y; Ding, X M; Luo, Y H; Bai, S P; Zeng, Q F; Wang, J P

2016-07-01

This study was conducted to determine the effect of tea polyphenols (TP) on production performance, egg quality, and hepatic-antioxidant status of laying hens in vanadium-containing diets. A total of 300 Lohman laying hens (67 wk old) were used in a 1 plus 3 × 3 experiment design in which hens were given either a diet without vanadium and TP supplementation (control) or diets supplemented with 5, 10, or 15 mg V/kg and TP (0, 600, 1,000 mg/kg) diets for 8 wk, which included 2 phases: a 5-wk accumulation phase and a 3-wk depletion phase. During the accumulation phase, dietary vanadium addition decreased (linear, P < 0.01) albumen height and Haugh unit (HU), and TP supplementation mitigated (linear effect, P < 0.01) this reduction effect induced by vanadium. Eggshell thickness (linear, P < 0.01), redness (linear and quadratic, P < 0.05), and yellowness (linear and quadratic, P < 0.05) were decreased by vanadium and increased by the effect of TP when a vanadium-containing diet was fed. In the depletion phase, the bleaching effect on eggshells induced by vanadium disappeared one wk after vanadium withdrawal. Eggshell thickness, eggshell strength, albumen height, and HU were lower (P < 0.05) in the 15 mg/kg vanadium group compared with the control diet until 2 wk post vanadium challenge, but hens fed 15 mg/kg vanadium and 600 mg/kg TP showed no difference from the control diet only after 1 wk withdrawal. In the liver, the activity of glutathione S-transferases and glutathione peroxidase was increased (linear, P < 0.01) with the TP addition at 5 wk in the accumulation phase in the vanadium-containing diet; the malondialdehyde content increased (linear effect, P = 0.02) with the addition of vanadium. The results indicate that supplementation of 10 and 15 mg/kg vanadium resulted in reduced albumen quality, bleaching effect on eggshell color, and antioxidant stress in the liver. The effect of TP addition can prevent laying hens from the adverse effect of vanadium on egg

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

PubMed

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.

Effect of vanadium doping on structural and magnetic properties of defective nano-nickel ferrite

NASA Astrophysics Data System (ADS)

Heiba, Zein K.; Mohamed, Mohamed Bakr; Wahba, Adel Maher; Almalowi, M. I.

2018-04-01

Nano-nickel ferrites defected by vanadium doping (NiV x Fe2-1.67 x O4, 0 ≤ x ≤ 0.25) were prepared using a simple sol gel method. Rietveld analysis revealed a nonmonotonic change in lattice parameter, oxygen parameter and magnetization upon doping with vanadium. Cation distributions suggested from either Rietveld analysis or from experimental magnetic moments were in a good agreement. For low doping values ( x = 0.05), vanadium was residing mainly in octahedral sites, while for samples with vanadium content ( x ≥ 0.1) a significant part of vanadium ions resided at tetrahedral sites; a result which has been confirmed by the analysis of Fourier-transform infrared (FTIR) spectrums obtained for the samples. The transmission electron microscope (TEM) image showed fine spherical particles with size of ˜ 11 nm. All samples showed a superparamagnetic nature with a nonmonotonic change of either magnetization ( M S) or coercivity (H C) with the content of nonmagnetic V5+. The cation occupancies indicated presence of an enormous number of vacancies through doping with high valence cation V5+, making present samples potential electrodes for Li- or Na-ion batteries.

Vanadium(IV/V) complexes of Triapine and related thiosemicarbazones: Synthesis, solution equilibrium and bioactivity.

PubMed

Kowol, Christian R; Nagy, Nóra V; Jakusch, Tamás; Roller, Alexander; Heffeter, Petra; Keppler, Bernhard K; Enyedy, Éva A

2015-11-01

The stoichiometry and thermodynamic stability of vanadium(IV/V) complexes of Triapine and two related α(N)-heterocyclic thiosemicarbazones (TSCs) with potential antitumor activity have been determined by pH-potentiometry, EPR and (51)V NMR spectroscopy in 30% (w/w) dimethyl sulfoxide/water solvent mixtures. In all cases, mono-ligand complexes in different protonation states were identified. Dimethylation of the terminal amino group resulted in the formation of vanadium(IV/V) complexes with considerably higher stability. Three of the most stable complexes were also synthesized in solid state and comprehensively characterized. The biological evaluation of the synthesized vanadium complexes in comparison to the metal-free ligands in different human cancer cell lines revealed only minimal influence of the metal ion. Thus, in addition the coordination ability of salicylaldehyde thiosemicarbazone (STSC) to vanadium(IV/V) ions was investigated. The exchange of the pyridine nitrogen of the α(N)-heterocyclic TSCs to a phenolate oxygen in STSC significantly increased the stability of the complexes in solution. Finally, this also resulted in increased cytotoxicity activity of a vanadium(V) complex of STSC compared to the metal-free ligand. Copyright © 2015 Elsevier Inc. All rights reserved.

Removal of arsenic, vanadium, and/or nickel compounds from petroliferous liquids

DOEpatents

Fish, R.H.

1985-05-17

Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids (shale oil, SRC, etc.) by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20/sup 0/ to 100/sup 0/C with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

Removal of arsenic, vanadium, and/or nickel compounds from petroliferous liquids

DOEpatents

Fish, Richard H.

1986-01-01

Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20.degree. to 100.degree. C. with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

Real-time monitoring of capacity loss for vanadium redox flow battery

NASA Astrophysics Data System (ADS)

Wei, Zhongbao; Bhattarai, Arjun; Zou, Changfu; Meng, Shujuan; Lim, Tuti Mariana; Skyllas-Kazacos, Maria

2018-06-01

The long-term operation of the vanadium redox flow battery is accompanied by ion diffusion across the separator and side reactions, which can lead to electrolyte imbalance and capacity loss. The accurate online monitoring of capacity loss is therefore valuable for the reliable and efficient operation of vanadium redox flow battery system. In this paper, a model-based online monitoring method is proposed to detect capacity loss in the vanadium redox flow battery in real time. A first-order equivalent circuit model is built to capture the dynamics of the vanadium redox flow battery. The model parameters are online identified from the onboard measureable signals with the recursive least squares, in seeking to keep a high modeling accuracy and robustness under a wide range of working scenarios. Based on the online adapted model, an observer is designed with the extended Kalman Filter to keep tracking both the capacity and state of charge of the battery in real time. Experiments are conducted on a lab-scale battery system. Results suggest that the online adapted model is able to simulate the battery behavior with high accuracy. The capacity loss as well as the state of charge can be estimated accurately in a real-time manner.

Effect of Vanadyl Rosiglitazone, a New Insulin-Mimetic Vanadium Complexes, on Glucose Homeostasis of Diabetic Mice.

PubMed

Jiang, Pingzhe; Dong, Zhen; Ma, Baicheng; Ni, Zaizhong; Duan, Huikun; Li, Xiaodan; Wang, Bin; Ma, Xiaofeng; Wei, Qian; Ji, Xiangzhen; Li, Minggang

2016-11-01

Diabetes has been cited as the most challenging health problem in the twenty-first century. Accordingly, it is urgent to develop a new type of efficient and low-toxic antidiabetic medication. Since vanadium compounds have insulin-mimetic and potential hypoglycemic activities for type 1 and type 2 diabetes, a new trend has been developed using vanadium and organic ligands to form a new compound in order to increase the intestinal absorption and reduce the toxicity of vanadium compound. In the current investigation, a new organic vanadium compounds, vanadyl rosiglitazone, was synthesized and determined by infrared spectra. Vanadyl rosiglitazone and three other organic vanadium compounds were administered to the diabetic mice through oral administration for 5 weeks. The results of mouse model test indicated that vanadyl rosiglitazone could regulate the blood glucose level and relieve the symptoms of polydipsia, polyphagia, polyuria, and weight loss without side effects and was more effective than the other three organic vanadium compounds including vanadyl trehalose, vanadyl metformin, and vanadyl quercetin. The study indicated that vanadyl rosiglitazone presents insulin-mimetic activities, and it will be a good potential candidate for the development of a new type of oral drug for type 2 diabetes.

Effects of Vanadium-Containing Compounds on Membrane Lipids and on Microdomains Used in Receptor-Mediated Signaling

PubMed Central

Roess, Deborah A.; Smith, Steven M. L.; Winter, Peter; Zhou, Jun; Dou, Ping; Baruah, Bharat; Trujillo, Alejandro M.; Levinger, Nancy E.; Yang, Xioda; Barisas, B. George; Crans, Debbie C.

2011-01-01

There is increasing evidence for the involvement of plasma membrane microdomains in insulin receptor function. Moreover, disruption of these structures, which are typically enriched in sphingomyelin and cholesterol, results in insulin resistance. Treatment strategies for insulin resistance include the use of vanadium compounds which have been shown in animal models to enhance insulin responsiveness. One possible mechanism for insulin-enhancing effects might involve direct effects of vanadium compounds on membrane lipid organization. These changes in lipid organization promote the partitioning of insulin receptors and other receptors into membrane microdomains where receptors are optimally functional. To explore this possibility, we have used several strategies involving vanadium complexes such as [VO2dipic]− (pyridin-2,6-dicarboxylatodioxovanadium(V)), decavanadate (V10O286−, V10), BMOV (bis(maltolato)oxovanadium(IV)) and [VO(saltris)]2 (2-salicylideniminato-2-(hydroxymethyl)-1,3-dihydroxypropane-oxovanadium(V)). Our strategies include an evaluation of interactions between vanadium-containing compounds and model lipid systems, an evaluation of the effects of vanadium compounds on lipid fluidity in erythrocyte membranes, and studies of the effects of vanadium-containing compounds on signaling events initiated by receptors known to use membrane microdomains as signaling platforms. PMID:18729092

Molybdenum disilicide composites reinforced with zirconia and silicon carbide

DOEpatents

Petrovic, John J.

1995-01-01

Compositions consisting essentially of molybdenum disilicide, silicon carbide, and a zirconium oxide component. The silicon carbide used in the compositions is in whisker or powder form. The zirconium oxide component is pure zirconia or partially stabilized zirconia or fully stabilized zirconia.

Characterization of individual straight and kinked boron carbide nanowires

NASA Astrophysics Data System (ADS)

Cui, Zhiguang

Boron carbides represent a class of ceramic materials with p-type semiconductor natures, complex structures and a wide homogeneous range of carbon compositions. Bulk boron carbides have long been projected as promising high temperature thermoelectric materials, but with limited performance. Bringing the bulk boron carbides to low dimensions (e.g., nanowires) is believed to be an option to enhance their thermoelectric performance because of the quantum size effects. However, the fundamental studies on the microstructure-thermal property relation of boron carbide nanowires are elusive. In this dissertation work, systematic structural characterization and thermal conductivity measurement of individual straight and kinked boron carbide nanowires were carried out to establish the true structure-thermal transport relation. In addition, a preliminary Raman spectroscopy study on identifying the defects in individual boron carbide nanowires was conducted. After the synthesis of single crystalline boron carbide nanowires, straight nanowires accompanied by the kinked ones were observed. Detailed structures of straight boron carbide nanowires have been reported, but not the kinked ones. After carefully examining tens of kinked nanowires utilizing Transmission Electron Microscopy (TEM), it was found that they could be categorized into five cases depending on the stacking faults orientations in the two arms of the kink: TF-TF, AF-TF, AF-AF, TF-IF and AF-IF kinks, in which TF, AF and IF denotes transverse faults (preferred growth direction perpendicular to the stacking fault planes), axial faults (preferred growth direction in parallel with the stacking fault planes) and inclined faults (preferred growth direction neither perpendicular to nor in parallel with the stacking fault planes). Simple structure models describing the characteristics of TF-TF, AF-TF, AF-AF kinked nanowires are constructed in SolidWorks, which help to differentiate the kinked nanowires viewed from the zone

The oxidation of organic additives in the positive vanadium electrolyte and its effect on the performance of vanadium redox flow battery

NASA Astrophysics Data System (ADS)

Nguyen, Tam D.; Whitehead, Adam; Scherer, Günther G.; Wai, Nyunt; Oo, Moe O.; Bhattarai, Arjun; Chandra, Ghimire P.; Xu, Zhichuan J.

2016-12-01

Despite many desirable properties, the vanadium redox flow battery is limited, in the maximum operation temperature that can be continuously endured, before precipitation begins in the positive electrolyte. Many additives have been proposed to improve the thermal stability of the charged positive electrolyte. However, we have found that the apparent stability, revealed in laboratory testing, is often simply an artifact of the test method and arises from the oxidation of the additive, with corresponding partial reduction of V(V) to V(IV). This does not improve the stability of the electrolyte in an operating system. Here, we examined the oxidation of some typical organic additives with carboxyl, alcohol, and multi-functional groups, in sulfuric acid solutions containing V(V). The UV-vis measurements and titration results showed that many compounds reduced the state-of-charge (SOC) of vanadium electrolyte, for example, by 27.8, 88.5, and 81.9% with the addition of 1%wt of EDTA disodium salt, pyrogallol, and ascorbic acid, respectively. The cell cycling also indicated the effect of organic additives on the cell performance, with significant reduction in the usable charge capacity. In addition, a standard screening method for thermally stable additives was introduced, to quickly screen suitable additives for the positive vanadium electrolyte.

Atomic layer deposition of VO2 films with Tetrakis-dimethyl-amino vanadium (IV) as vanadium precursor

NASA Astrophysics Data System (ADS)

Lv, Xinrui; Cao, Yunzhen; Yan, Lu; Li, Ying; Song, Lixin

2017-02-01

VO2 thin films have been grown on Si(100) (VO2/Si) and fused silica substrates (VO2/SiO2) by atomic layer deposition (ALD) using tetrakis-dimethyl-amino vanadium (IV) (TDMAV) as a novel vanadium precursor and water as reactant gas. The quartz crystal microbalance (QCM) measurement was performed to study the ALD process of VO2 thin film deposition, and a constant growth rate of about 0.95 Å/cycle was obtained at the temperature range of 150-200 °C. XRD measurement was performed to study the influence of deposition temperature and post-annealing condition on the crystallization of VO2 films, which indicated that the films deposited between 150 and 200 °C showed well crystallinity after annealing at 475 °C for 100 min in Ar atmosphere. XPS measurement verified that the vanadium oxidation state was 4+ for both as-deposited film and post-annealed VO2/Si film. AFM was applied to study the surface morphology of VO2/Si films, which showed a dense polycrystalline film with roughness of about 1 nm. The resistance of VO2/Si films deposited between 150 °C and 200 °C as a function of temperature showed similar semiconductor-to-metal transition (SMT) characters with the transition temperature for heating branch (Tc,h) of about 72 °C, a hysteresis width of about 10 °C and the resistance change of two orders of magnitude. The increase of Tc,h compared with the bulk VO2 (68 °C) may be attributed to the tensile stress along the c-axis in the film. Transmittance measurement of VO2/SiO2 films showed typical thermochromic property with a NIR switching efficiency of above 50% at 2 μm across the transition.

Silicon carbide, an emerging high temperature semiconductor

NASA Technical Reports Server (NTRS)

Matus, Lawrence G.; Powell, J. Anthony

1991-01-01

In recent years, the aerospace propulsion and space power communities have expressed a growing need for electronic devices that are capable of sustained high temperature operation. Applications for high temperature electronic devices include development instrumentation within engines, engine control, and condition monitoring systems, and power conditioning and control systems for space platforms and satellites. Other earth-based applications include deep-well drilling instrumentation, nuclear reactor instrumentation and control, and automotive sensors. To meet the needs of these applications, the High Temperature Electronics Program at the Lewis Research Center is developing silicon carbide (SiC) as a high temperature semiconductor material. Research is focussed on developing the crystal growth, characterization, and device fabrication technologies necessary to produce a family of silicon carbide electronic devices and integrated sensors. The progress made in developing silicon carbide is presented, and the challenges that lie ahead are discussed.

Semiconducting boron carbide polymers devices for neutron detection

NASA Astrophysics Data System (ADS)

Echeverria, Elena; Pasquale, Frank L.; James, Robinson; Colón Santana, Juan A.; Adenwalla, Shireen; Kelber, Jeffry A.; Dowben, Peter A.

2014-03-01

Boron carbide materials, with aromatic compounds included, prove to be effective materials as solid state neutron detector detectors. The I-V characteristic curves for these heterojunction diodes with silicon show that these modified boron carbides, in the presence of these linking groups such as 1,4-diaminobenzene (DAB) and pyridine, are p-type. Cadmium was used as shield to discriminate between neutron-induced signals and thermal neutrons, and thermal neutron capture is evident, while gamma detection was not realized. Neutron detection signals for these heterojunction diode were observed, a measurable zero bias current noted, even without complete electron-hole collection. This again illustrates that boron carbide devices can be considered a neutron voltaic.

ON THE SEPARATION OF VANADIUM, MOLYBDENUM AND TUNGSTEN BY MEANS OF PAPER CHROMATOGRAPHY. PART I

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tzou, S.; Liang, S.

1959-02-01

Molybdenum, tangsten, and vanadium are separated by chromatography as per-acids, and then detected with tannin solution. Of the seven solvents tested, n-butanolhydrogen peroxide-nitric acid mixtures offer the best separations. With the addition of dioxane, the R/sub F/ values of these elements increase, while vanadium and tungsten spots overlap. The formation of per-acids avoids the retainment of tungsten on the original spot and the tailings of vanadium and molybdenum spots. (B.O.G.)

Molecular based magnets comprising vanadium tetracyanoethylene complexes for shielding electromagnetic fields

DOEpatents

Epstein, Arthur J.; Morin, Brian G.

1998-01-01

The invention presents a vanadium tetracyanoethylene solvent complex for electromagnetic field shielding, and a method for blocking low frequency and magnetic fields using these vanadium tetracyanoethylene compositions. The compositions of the invention can be produced at ambient temperature and are light weight, low density and flexible. The materials of the present invention are useful as magnetic shields to block low frequency fields and static fields, and for use in cores in transformers and motors.

Evaluation of titanium carbide metal matrix composites deposited via laser cladding

NASA Astrophysics Data System (ADS)

Cavanaugh, Daniel Thomas

Metal matrix composites have been widely studied in terms of abrasion resistance, but a particular material system may behave differently as particle size, morphology, composition, and distribution of the hardening phase varies. The purpose of this thesis was to understand the mechanical and microstructural effects of combining titanium carbide with 431 series stainless steel to create a unique composite via laser cladding, particularly regarding wear properties. The most predominant effect in increasing abrasion resistance, measured via ASTM G65, was confirmed to be volume fraction of titanium carbide addition. Macrohardness was directly proportional to the amount of carbide, though there was an overall reduction in individual particle microhardness after cladding. The reduction in particle hardness was obscured by the effect of volume fraction carbide and did not substantially contribute to the wear resistance changes. A model evaluating effective mean free path of the titanium carbide particles was created and correlated to the measured data. The model proved successful in linking theoretical mean free path to overall abrasion resistance. The effects of the titanium carbide particle distributions were limited, while differences in particle size were noticeable. The mean free path model did not correlate well with the particle size, but it was shown that the fine carbides were completely removed by the coarse abrasive particles in the ASTM G65 test. The particle morphology showed indications of influencing the wear mode, but no statistical reduction was observed in the volume loss figures. Future studies may more specifically focus on particle morphology or compositional effects of the carbide particles.

Size dependence of nanoscale wear of silicon carbide

Treesearch

Chaiyapat Tangpatjaroen; David Grierson; Steve Shannon; Joseph E. Jakes; Izabela Szlufarska

2017-01-01

Nanoscale, single-asperity wear of single-crystal silicon carbide (sc- SiC) and nanocrystalline silicon carbide (nc-SiC) is investigated using single-crystal diamond nanoindenter tips and nanocrystalline diamond atomic force microscopy (AFM) tips under dry conditions, and the wear behavior is compared to that of single-crystal silicon with both thin and thick native...

Molybdenum disilicide composites reinforced with zirconia and silicon carbide

DOEpatents

Petrovic, J.J.

1995-01-17

Compositions are disclosed consisting essentially of molybdenum disilicide, silicon carbide, and a zirconium oxide component. The silicon carbide used in the compositions is in whisker or powder form. The zirconium oxide component is pure zirconia or partially stabilized zirconia or fully stabilized zirconia.

Soil-adjusted sorption isotherms for arsenic(V) and vanadium(V)

NASA Astrophysics Data System (ADS)

Rückamp, Daniel; Utermann, Jens; Florian Stange, Claus

2017-04-01

The sorption characteristic of a soil is usually determined by fitting a sorption isotherm model to laboratory data. However, such sorption isotherms are only valid for the studied soil and cannot be transferred to other soils. For this reason, a soil-adjusted sorption isotherm can be calculated by using the data of several soils. Such soil-adjusted sorption isotherms exist for cationic heavy metals, but are lacking for heavy metal oxyanions. Hence, the aim of this study is to establish soil-adjusted sorption isotherms for the oxyanions arsenate (arsenic(V)) and vanadate (vanadium(V)). For the laboratory experiment, 119 soils (samples from top- and subsoils) typical for Germany were chosen. The batch experiments were conducted with six concentrations of arsenic(V) and vanadium(V), respectively. By using the laboratory data, sorption isotherms for each soil were derived. Then, the soil-adjusted sorption isotherms were calculated by non-linear regression of the sorption isotherms with additional soil parameters. The results indicated a correlation between the sorption strength and oxalate-extractable iron, organic carbon, clay, and electrical conductivity for both, arsenic and vanadium. However, organic carbon had a negative regression coefficient. As total organic carbon was correlated with dissolved organic carbon; we attribute this observation to an effect of higher amounts of dissolved organic substances. We conclude that these soil-adjusted sorption isotherms can be used to assess the potential of soils to adsorb arsenic(V) and vanadium(V) without performing time-consuming sorption experiments.

Dilatometry Analysis of Dissolution of Cr-Rich Carbides in Martensitic Stainless Steels

NASA Astrophysics Data System (ADS)

Huang, Qiuliang; Volkova, Olena; Biermann, Horst; Mola, Javad

2017-12-01

The dissolution of Cr-rich carbides formed in the martensitic constituent of a 13 pct Cr stainless steel was studied by dilatometry and correlative electron channeling contrast examinations. The dissolution of carbides subsequent to the martensite reversion to austenite was associated with a net volume expansion which in turn increased the dilatometry-based apparent coefficient of thermal expansion (CTEa) during continuous heating. The effects of carbides fraction and size on the CTEa variations during carbides dissolution are discussed.

Carbide-reinforced metal matrix composite by direct metal deposition

NASA Astrophysics Data System (ADS)

Novichenko, D.; Thivillon, L.; Bertrand, Ph.; Smurov, I.

Direct metal deposition (DMD) is an automated 3D laser cladding technology with co-axial powder injection for industrial applications. The actual objective is to demonstrate the possibility to produce metal matrix composite objects in a single-step process. Powders of Fe-based alloy (16NCD13) and titanium carbide (TiC) are premixed before cladding. Volume content of the carbide-reinforced phase is varied. Relationships between the main laser cladding parameters and the geometry of the built-up objects (single track, 2D coating) are discussed. On the base of parametric study, a laser cladding process map for the deposition of individual tracks was established. Microstructure and composition of the laser-fabricated metal matrix composite objects are examined. Two different types of structures: (a) with the presence of undissolved and (b) precipitated titanium carbides are observed. Mechanism of formation of diverse precipitated titanium carbides is studied.

REVIEWS OF TOPICAL PROBLEMS: Order-disorder transformations and phase equilibria in strongly nonstoichiometric compounds

NASA Astrophysics Data System (ADS)

Gusev, Aleksandr I.

2000-01-01

Data on order-disorder phase transformations in strongly nonstoichiometric carbides and nitrides MXy (X=C, N) of Group IV and V transition metals at temperatures below 1300-1400 K are reviewed. The order-parameter functional method as applied to atomic and vacancy ordering in strongly nonstoichiometric MXy compounds and to phase equilibrium calculations for M-X systems is discussed. Phase diagram calculations for the Ti-C, Zr-C, Hf-C, V-C, Nb-C, Ta-C, Ti-N, and Ti-B-C systems (with the inclusion of the ordering of nonstoichiometric carbides and nitrides) and those for pseudobinary carbide M(1)C-M(2)C systems are presented. Heat capacity, electrical resistivity and magnetic susceptibility changes at reversible order-disorder phase transformations in nonstoichiometric carbides are considered.

Development of refractory armored silicon carbide by infrared transient liquid phase processing

NASA Astrophysics Data System (ADS)

Hinoki, Tatsuya; Snead, Lance L.; Blue, Craig A.

2005-12-01

Tungsten (W) and molybdenum (Mo) were coated on silicon carbide (SiC) for use as a refractory armor using a high power plasma arc lamp at powers up to 23.5 MW/m 2 in an argon flow environment. Both tungsten powder and molybdenum powder melted and formed coating layers on silicon carbide within a few seconds. The effect of substrate pre-treatment (vapor deposition of titanium (Ti) and tungsten, and annealing) and sample heating conditions on microstructure of the coating and coating/substrate interface were investigated. The microstructure was observed by scanning electron microscopy (SEM) and optical microscopy (OM). The mechanical properties of the coated materials were evaluated by four-point flexural tests. A strong tungsten coating was successfully applied to the silicon carbide substrate. Tungsten vapor deposition and pre-heating at 5.2 MW/m 2 made for a refractory layer containing no cracks propagating into the silicon carbide substrate. The tungsten coating was formed without the thick reaction layer. For this study, small tungsten carbide grains were observed adjacent to the interface in all conditions. In addition, relatively large, widely scattered tungsten carbide grains and a eutectic structure of tungsten and silicon were observed through the thickness in the coatings formed at lower powers and longer heating times. The strength of the silicon carbide substrate was somewhat decreased as a result of the processing. Vapor deposition of tungsten prior to powder coating helped prevent this degradation. In contrast, molybdenum coating was more challenging than tungsten coating due to the larger coefficient of thermal expansion (CTE) mismatch as compared to tungsten and silicon carbide. From this work it is concluded that refractory armoring of silicon carbide by Infrared Transient Liquid Phase Processing is possible. The tungsten armored silicon carbide samples proved uniform, strong, and capable of withstanding thermal fatigue testing.

SOLID SOLUTION CARBIDES ARE THE KEY FUELS FOR FUTURE NUCLEAR THERMAL PROPULSION

NASA Technical Reports Server (NTRS)

Panda, Binayak; Hickman, Robert R.; Shah, Sandeep

2005-01-01

Nuclear thermal propulsion uses nuclear energy to directly heat a propellant (such as liquid hydrogen) to generate thrust for space transportation. In the 1960 s, the early Rover/Nuclear Engine for Rocket Propulsion Application (NERVA) program showed very encouraging test results for space nuclear propulsion but, in recent years, fuel research has been dismal. With NASA s renewed interest in long-term space exploration, fuel researchers are now revisiting the RoverMERVA findings, which indicated several problems with such fuels (such as erosion, chemical reaction of the fuel with propellant, fuel cracking, and cladding issues) that must be addressed. It is also well known that the higher the temperature reached by a propellant, the larger the thrust generated from the same weight of propellant. Better use of fuel and propellant requires development of fuels capable of reaching very high temperatures. Carbides have the highest melting points of any known material. Efforts are underway to develop carbide mixtures and solid solutions that contain uranium carbide, in order to achieve very high fuel temperatures. Binary solid solution carbides (U, Zr)C have proven to be very effective in this regard. Ternary carbides such as (U, Zr, X) carbides (where X represents Nb, Ta, W, and Hf) also hold great promise as fuel material, since the carbide mixtures in solid solution generate a very hard and tough compact material. This paper highlights past experience with early fuel materials and bi-carbides, technical problems associated with consolidation of the ingredients, and current techniques being developed to consolidate ternary carbides as fuel materials.

Removal of arsenic, vanadium and/or nickel compounds from spent catecholated polymer

DOEpatents

Fish, R.H.

1987-04-21

Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20 to 100 C with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

Electrical and Infrared Optical Properties of Vanadium Oxide Semiconducting Thin-Film Thermometers

NASA Astrophysics Data System (ADS)

Zia, Muhammad Fakhar; Abdel-Rahman, Mohamed; Alduraibi, Mohammad; Ilahi, Bouraoui; Awad, Ehab; Majzoub, Sohaib

2017-10-01

A synthesis method has been developed for preparation of vanadium oxide thermometer thin film for microbolometer application. The structure presented is a 95-nm thin film prepared by sputter-depositing nine alternating multilayer thin films of vanadium pentoxide (V2O5) with thickness of 15 nm and vanadium with thickness of 5 nm followed by postdeposition annealing at 300°C in nitrogen (N2) and oxygen (O2) atmospheres. The resulting vanadium oxide (V x O y ) thermometer thin films exhibited temperature coefficient of resistance (TCR) of -3.55%/°C with room-temperature resistivity of 2.68 Ω cm for structures annealed in N2 atmosphere, and TCR of -3.06%/°C with room-temperature resistivity of 0.84 Ω cm for structures annealed in O2 atmosphere. Furthermore, optical measurements of N2- and O2-annealed samples were performed by Fourier-transform infrared ellipsometry to determine their dispersion curves, refractive index ( n), and extinction coefficient ( k) at wavelength from 7000 nm to 14,000 nm. The results indicate the possibility of applying the developed materials in thermometers for microbolometers.

Vanadium release in whole blood, serum and urine of patients implanted with a titanium alloy hip prosthesis.

PubMed

Catalani, S; Stea, S; Beraudi, A; Gilberti, M E; Bordini, B; Toni, A; Apostoli, P

2013-08-01

Vanadium (V) is a minor constituent of the Titanium-Aluminum-Vanadium (TiAlV) alloy currently used in cementless hip prostheses. Present study aimed at verifying the correlation of vanadium levels among different matrices and assessing reference levels of the ion in a population of patients wearing a well-functioning hip prosthesis. Vanadium was measured using Inductive Coupled Plasma Mass Spectrometry (ICP-MS) in whole blood, serum and urine of 129 patients implanted with a TiAlV-alloy hip prosthesis. The values in the serum were above the upper limit of the reference values in 42% of patients (29% in urine and 13% in whole blood). A good correlation among matrices was observed (p < 0.001). The cohort of patients (N = 32) complaining of pain or in which a loosening or damage to the prosthesis was assessed showed a significantly higher excretion of vanadium in urine as compared with the remaining asymptomatic patients (p = 0.001). The 95th percentile distribution of vanadium in the cohort of patients with a well-functioning prosthesis was 0.3 μg/L in whole blood, 0.5 μg/L in serum and 2.8 μg/L in urine, higher that in the unexposed population, especially for urine. The presence of a prosthesis, even though well-functioning, may cause a possible release of vanadium into the blood and a significant urinary excretion. The reference values of vanadium of the asymptomatic patients with titanium alloy hip prostheses supplied information regarding the background exposure level of the ions and their lower and upper limits.

40 CFR 440.30 - Applicability; description of the uranium, radium and vanadium ores subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... uranium, radium and vanadium ores subcategory. 440.30 Section 440.30 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS ORE MINING AND DRESSING POINT SOURCE CATEGORY Uranium, Radium and Vanadium Ores Subcategory § 440.30 Applicability; description of the...

One-step hydrothermal synthesis of hexangular starfruit-like vanadium oxide for high power aqueous supercapacitors

NASA Astrophysics Data System (ADS)

Shao, Jie; Li, Xinyong; Qu, Qunting; Zheng, Honghe

2012-12-01

Homogenous hexangular starfruit-like vanadium oxide was prepared for the first time by a one-step hydrothermal method. The assembly process of hexangular starfruit-like structure was observed from TEM images. The electrochemical performance of starfruit-like vanadium oxide was examined by cyclic voltammetry and galvanostatic charge/discharge. The obtained starfruit-like vanadium oxide exhibits a high power capability (19 Wh kg-1 at the specific power of 3.4 kW kg-1) and good cycling stability for supercapacitors application.

Method of making silicon carbide-silicon composite having improved oxidation resistance

NASA Technical Reports Server (NTRS)

Wang, Hongyu (Inventor); Luthra, Krishan Lal (Inventor)

2002-01-01

A Silicon carbide-silicon matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is provided. A method is given for sealing matrix cracks in situ in melt infiltrated silicon carbide-silicon matrix composites. The composite cracks are sealed by the addition of various additives, such as boron compounds, into the melt infiltrated silicon carbide-silicon matrix.

Removal and recovery of vanadium from alkaline steel slag leachates with anion exchange resins.

PubMed

Gomes, Helena I; Jones, Ashley; Rogerson, Mike; Greenway, Gillian M; Lisbona, Diego Fernandez; Burke, Ian T; Mayes, William M

2017-02-01

Leachable vanadium (V) from steel production residues poses a potential environmental hazard due to its mobility and toxicity under the highly alkaline pH conditions that characterise these leachates. This work aims to test the efficiency of anion exchange resins for vanadium removal and recovery from steel slag leachates at a representative average pH of 11.5. Kinetic studies were performed to understand the vanadium sorption process. The sorption kinetics were consistent with a pseudo-first order kinetic model. The isotherm data cannot differentiate between the Langmuir and Freundlich models. The maximum adsorption capacity (Langmuir value q max ) was 27 mg V g -1 resin. In column anion exchange, breakthrough was only 14% of the influent concentration after passing 90 L of steel slag leachate with 2 mg L -1 V through the column. When eluting the column 57-72% of vanadium was recovered from the resin with 2 M NaOH. Trials on the reuse of the anion exchange resin showed it could be reused 20 times without loss of efficacy, and on average 69% of V was recovered during regeneration. The results document for the first time the use of anion exchange resins to remove vanadium from steel slag leachate. As an environmental contaminant, removal of V from leachates may be an obligation for long-term management requirements of steel slag repositories. Vanadium removal coupled with the recovery can potentially be used to offset long-term legacy treatment costs. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Molecular based magnets comprising vanadium tetracyanoethylene complexes for shielding electromagnetic fields

DOEpatents

Epstein, A.J.; Morin, B.G.

1998-10-13

The invention presents a vanadium tetracyanoethylene solvent complex for electromagnetic field shielding, and a method for blocking low frequency and magnetic fields using these vanadium tetracyanoethylene compositions. The compositions of the invention can be produced at ambient temperature and are light weight, low density and flexible. The materials of the present invention are useful as magnetic shields to block low frequency fields and static fields, and for use in cores in transformers and motors. 21 figs.

Silicon Carbide Etching Using Chlorine Trifluoride Gas

NASA Astrophysics Data System (ADS)

Habuka, Hitoshi; Oda, Satoko; Fukai, Yasushi; Fukae, Katsuya; Takeuchi, Takashi; Aihara, Masahiko

2005-03-01

The etch rate, chemical reactions and etched surface of β-silicon carbide are studied in detail using chlorine trifluoride gas. The etch rate is greater than 10 μm min-1 at 723 K with a flow rate of 0.1 \\ell min-1 at atmospheric pressure in a horizontal reactor. The maximum etch rate at a substrate temperature of 773 K is 40 μm min-1 with a flow rate of 0.25 \\ell min-1. The step-like pattern that initially exists on the β-silicon carbide surface tends to be smoothed; the root-mean-square surface roughness decreases from its initial value of 5 μm to 1 μm within 15 min; this minimum value is maintained for more than 15 min. Therefore, chlorine trifluoride gas is considered to have a large etch rate for β-silicon carbide associated with making a rough surface smooth.

Method of forming impermeable carbide coats on graphite

DOEpatents

Wohlberg, C.

1973-12-11

A method of forming an impermeable refractory metal carbide coating on graphite is described in which a metal containing oxidant and a carbide former are applied to the surface of the graphite, heated to a temperature of between 1200 and 1500 deg C in an inert gas, under a vacuum and continuing to heat to about 2300 deg C. (Official Gazette)

TUNGSTEN BRONZE RELATED NON-NOBLE ELECTROCATALYSTS.

DTIC Science & Technology

FUEL CELLS, *CATALYSTS), (*OXYGEN, *ELECTRODES), (* SILICIDES , ELECTRODES), (*CARBIDES, ELECTRODES), (*TUNGSTEN COMPOUNDS, *ELECTROCHEMISTRY...CATALYSTS, TITANIUM COMPOUNDS, ZIRCONIUM COMPOUNDS, VANADIUM COMPOUNDS, NIOBIUM COMPOUNDS, TUNGSTEN COMPOUNDS, TANTALUM COMPOUNDS, MOLYBDENUM COMPOUNDS, SULFURIC ACID, CRYSTAL GROWTH, SODIUM COMPOUNDS

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

NASA Astrophysics Data System (ADS)

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

Investigating the air oxidation of V(II) ions in a vanadium redox flow battery

NASA Astrophysics Data System (ADS)

Ngamsai, Kittima; Arpornwichanop, Amornchai

2015-11-01

The air oxidation of vanadium (V(II)) ions in a negative electrolyte reservoir is a major side reaction in a vanadium redox flow battery (VRB), which leads to electrolyte imbalance and self-discharge of the system during long-term operation. In this study, an 80% charged negative electrolyte solution is employed to investigate the mechanism and influential factors of the reaction in a negative-electrolyte reservoir. The results show that the air oxidation of V(II) ions occurs at the air-electrolyte solution interface area and leads to a concentration gradient of vanadium ions in the electrolyte solution and to the diffusion of V(II) and V(III) ions. The effect of the ratio of the electrolyte volume to the air-electrolyte solution interface area and the concentrations of vanadium and sulfuric acid in an electrolyte solution is investigated. A higher ratio of electrolyte volume to the air-electrolyte solution interface area results in a slower oxidation reaction rate. The high concentrations of vanadium and sulfuric acid solution also retard the air oxidation of V(II) ions. This information can be utilized to design an appropriate electrolyte reservoir for the VRB system and to prepare suitable ingredients for the electrolyte solution.

The development of silicon carbide-based power electronics devices

NASA Astrophysics Data System (ADS)

Hopkins, Richard H.; Perkins, John F.

1995-01-01

In 1989 Westinghouse created an internally funded initiative to develop silicon carbide materials and device technology for a variety of potential commercial and military applications. Westinghouse saw silicon carbide as having the potential for dual use. For space applications, size and weight reductions could be achieved, together with increased reliability. Terrestrially, uses in harsh-temperature environments would be enabled. Theoretically, the physical and electrical properties of silicon carbide were highly promising for high-power, high-temperature, radiation-hardened electronics. However, bulk material with the requisite electronic qualities was not available, and the methods needed to produce a silicon carbide wafer—to fabricate high-quality devices—and to transition these technologies into a commercial product were considered to be a high-risk investment. It was recognized that through a collaborative effort, the CCDS could provide scientific expertise in several areas, thus reducing this risk. These included modeling of structures, electrical contacts, dielectrics, and epitaxial growth. This collaboration has been very successful, with developed technologies being transferred to Westinghouse.

Concentration Dependence of VO2+ Crossover of Nafion for Vanadium Redox Flow Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lawton, Jamie; Jones, Amanda; Zawodzinski, Thomas A

2013-01-01

The VO2+ crossover, or permeability, through Nafion in a vanadium redox flow battery (VRFB) was monitored as a function of sulfuric acid concentration and VO2+ concentration. A vanadium rich solution was flowed on one side of the membrane through a flow field while symmetrically on the other side a blank or vanadium deficit solution was flowed. The blank solution was flowed through an electron paramagnetic resonance (EPR) cavity and the VO2+ concentration was determined from the intensity of the EPR signal. Concentration values were fit using a solution of Fick s law that allows for the effect of concentration changemore » on the vanadium rich side. The fits resulted in permeability values of VO2+ ions across the membrane. Viscosity measurements of many VO2+ and H2SO4 solutions were made at 30 60 C. These viscosity values were then used to determine the effect of the viscosity of the flowing solution on the permeability of the ion. 2013 The Electrochemical Society. [DOI: 10.1149/2.004306jes] All rights reserved.« less

Atomic resolution crystal structure of VcLMWPTP-1 from Vibrio cholerae O395: Insights into a novel mode of dimerization in the low molecular weight protein tyrosine phosphatase family

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nath, Seema; Banerjee, Ramanuj; Sen, Udayaditya, E-mail: udayaditya.sen@saha.ac.in

Highlights: • VcLMWPTP-1 forms dimer in solution. • The dimer is catalytically active unlike other reported dimeric LMWPTPs. • The formation of extended dimeric surface excludes the active site pocket. • The surface bears closer resemblance to eukaryotic LMWPTPs. - Abstract: Low molecular weight protein tyrosine phosphatase (LMWPTP) is a group of phosphotyrosine phosphatase ubiquitously found in a wide range of organisms ranging from bacteria to mammals. Dimerization in the LMWPTP family has been reported earlier which follows a common mechanism involving active site residues leading to an enzymatically inactive species. Here we report a novel form of dimerization inmore » a LMWPTP from Vibrio cholera 0395 (VcLMWPTP-1). Studies in solution reveal the existence of the dimer in solution while kinetic study depicts the active form of the enzyme. This indicates that the mode of dimerization in VcLMWPTP-1 is different from others where active site residues are not involved in the process. A high resolution (1.45 Å) crystal structure of VcLMWPTP-1 confirms a different mode of dimerization where the active site is catalytically accessible as evident by a tightly bound substrate mimicking ligand, MOPS at the active site pocket. Although being a member of a prokaryotic protein family, VcLMWPTP-1 structure resembles very closely to LMWPTP from a eukaryote, Entamoeba histolytica. It also delineates the diverse surface properties around the active site of the enzyme.« less

Carbide derived carbon from MAX-phases and their separation applications

NASA Astrophysics Data System (ADS)

Hoffman, Elizabeth N.

Improved sorbents with increased selectivity and permeability are needed to meet growing energy and environmental needs. New forms of carbon based sorbents have been discovered recently, including carbons produced by etching metals from metal carbides, known as carbide derived carbons (CDCs). A common method for the synthesis of CDC is by chlorination at elevated temperatures. The goal of this work is to synthesize CDC from ternary carbides and to explore the links between the initial carbide chemistry and structure with the resulting CDCs properties, including porosity. CDC was produced from MAX-phase carbides, in particular Ti3SiC 2, Ti3AlC2, Ti2AlC, and Ta2AlC. Additionally, CDC was produced from Ta-based binary carbides, TaC and Ta 2C, and one carbo-nitride Ti2AlC0.5N0.5. The CDC structure was characterized using XRD, Raman microspectroscopy, and HRTEM. Porosity characterization was performed using sorption analysis with both Ar and N2 as adsorbates. It was determined the microporosity of CDC is related to the density of the initial carbide. The layered structure of the MAX-phase carbides lent toward the formation of larger mesopores within the resulting CDCs, while the amount of mesopores was dependent on the chemistry of the carbide. Furthermore, CDC produced from carbides with extremely high theoretical porosity resulted in small specific surface areas due to a collapse of the carbon structure. To expand the potential applications for CDC beyond powder and bulk forms, CDC membranes were produced from a thin film of TiC deposited by magnetron sputtering onto porous ceramic substrates. The TiC thin film was subsequently chlorinated to produce a bilayer membrane with CDC as the active layer. Both gases and liquids are capable of passing the membrane. The membrane separates based on selective adsorption, rather than a size separation molecular sieving effect. Two applications for CDC produced from MAX-phases were investigated: protein adsorption and gas

Metal Insulator transition in Vanadium Dioxide

NASA Astrophysics Data System (ADS)

Jovaini, Azita; Fujita, Shigeji; Suzuki, Akira; Godoy, Salvador

2012-02-01

MAR12-2011-000262 Abstract Submitted for the MAR12 Meeting of The American Physical Society Sorting Category: 03.9 (T) On the metal-insulator-transition in vanadium dioxide AZITA JOVAINI, SHIGEJI FUJITA, University at Buffalo, SALVADOR GODOY, UNAM, AKIRA SUZUKI, Tokyo University of Science --- Vanadium dioxide (VO2) undergoes a metal-insulator transition (MIT) at 340 K with the structural change from tetragonal to monoclinic crystal. The conductivity _/ drops at MIT by four orders of magnitude. The low temperature monoclinic phase is known to have a lower ground-state energy. The existence of the k-vector k is prerequisite for the conduction since the k appears in the semiclassical equation of motion for the conduction electron (wave packet). The tetragonal (VO2)3 unit is periodic along the crystal's x-, y-, and z-axes, and hence there is a three-dimensional k-vector. There is a one-dimensional k for a monoclinic crystal. We believe this difference in the dimensionality of the k-vector is the cause of the conductivity drop. Prefer Oral Session X Prefer .

Self-assembly of Carbon Vacancies in Sub-stoichiometric ZrC1−x

PubMed Central

Zhang, Yanhui; Liu, Bin; Wang, Jingyang

2015-01-01

Sub-stoichiometric interstitial compounds, including binary transition metal carbides (MC1−x), maintain structural stability even if they accommodate abundant anion vacancies. This unique character endows them with variable-composition, diverse-configuration and controllable-performance through composition and structure design. Herein, the evolution of carbon vacancy (VC) configuration in sub-stoichiometric ZrC1−x is investigated by combining the cluster expansion method and first-principles calculations. We report the interesting self-assembly of VCs and the fingerprint VC configuration (VC triplet constructed by 3rd nearest neighboring vacancies) in all the low energy structures of ZrC1−x. When VC concentration is higher than the critical value of 0.5 (x > 0.5), the 2nd nearest neighboring VC configurations with strongly repulsive interaction inevitably appear, and meanwhile, the system energy (or formation enthalpy) of ZrC1−x increases sharply which suggests the material may lose phase stability. The present results clarify why ZrC1−x bears a huge amount of VCs, tends towards VC ordering, and retains stability up to a stoichiometry of x = 0.5. PMID:26667083

Graphene-modified nanostructured vanadium pentoxide hybrids with extraordinary electrochemical performance for Li-ion batteries

DOE PAGES

Liu, Qi; Li, Zhe-Fei; Liu, Yadong; ...

2015-01-20

The long-standing issues of low intrinsic electronic conductivity, slow lithium-ion diffusion and irreversible phase transitions on deep discharge prevent the high specific capacity/energy (443 mAh g -1 and 1,550 Wh kg -1) vanadium pentoxide from being used as the cathode material in practical battery applications. Here we develop a method to incorporate graphene sheets into vanadium pentoxide nanoribbons via the sol–gel process. The resulting graphene-modified nanostructured vanadium pentoxide hybrids contain only 2 wt. % graphene, yet exhibits extraordinary electrochemical performance: a specific capacity of 438 mAh g -1, approaching the theoretical value (443 mAh g -1), a long cyclability andmore » significantly enhanced rate capability. Such performance is the result of the combined effects of the graphene on structural stability, electronic conduction, vanadium redox reaction and lithium-ion diffusion supported by various experimental studies. Finally, this method provides a new avenue to create nanostructured metal oxide/graphene materials for advanced battery applications.« less

Imaging metal-like monoclinic phase stabilized by surface coordination effect in vanadium dioxide nanobeam

PubMed Central

Li, Zejun; Wu, Jiajing; Hu, Zhenpeng; Lin, Yue; Chen, Qi; Guo, Yuqiao; Liu, Yuhua; Zhao, Yingcheng; Peng, Jing; Chu, Wangsheng; Wu, Changzheng; Xie, Yi

2017-01-01

In correlated systems, intermediate states usually appear transiently across phase transitions even at the femtosecond scale. It therefore remains an open question how to determine these intermediate states—a critical issue for understanding the origin of their correlated behaviour. Here we report a surface coordination route to successfully stabilize and directly image an intermediate state in the metal-insulator transition of vanadium dioxide. As a prototype metal-insulator transition material, we capture an unusual metal-like monoclinic phase at room temperature that has long been predicted. Coordinate bonding of L-ascorbic acid molecules with vanadium dioxide nanobeams induces charge-carrier density reorganization and stabilizes metallic monoclinic vanadium dioxide, unravelling orbital-selective Mott correlation for gap opening of the vanadium dioxide metal–insulator transition. Our study contributes to completing phase-evolution pathways in the metal-insulator transition process, and we anticipate that coordination chemistry may be a powerful tool for engineering properties of low-dimensional correlated solids. PMID:28613281

Whatever happened to silicon carbide. [semiconductor devices

NASA Technical Reports Server (NTRS)

Campbell, R. B.

1981-01-01

The progress made in silicon carbide semiconductor devices in the 1955 to 1975 time frame is examined and reasons are given for the present lack of interest in the material. Its physical and chemical properties and methods of preparation are discussed. Fabrication techniques and the characteristics of silicon carbide devices are reviewed. It is concluded that a combination of economic factors and the lack of progress in fabrication techniques leaves no viable market for SiC devices in the near future.

Lactational Vitamin E Protects Against the Histotoxic Effects of Systemically Administered Vanadium in Neonatal Rats.

PubMed

Olaolorun, F A; Obasa, A A; Balogun, H A; Aina, O O; Olopade, J O

2014-12-29

The work investigated the protective role of lactational vitamin E administration on vanadium-induced histotoxicity. Three groups of Wistar rats, with each group comprising of two dams and their pups, were used in this study. Group I pups were administered intraperitoneal injection of sterile water at volumes corresponding to the dose rate of the vanadium (sodium metavanadate) treated group from postnatal day (PND) 1-14 while those in Group II were administered intraperitoneal injection of 3mg/kg vanadium from PND 1-14. Group III pups were administered intraperitoneal injection of 3mg/kg vanadium while the dam received oral vitamin E (500 mg) concurrently every 72 hours. The results showed that group II pups exhibited histopathological changes which included seminiferous tubule disruption of the testes characterised by vacuolar degeneration and coagulative necrosis of spermatogonia and Sertoli cells with reduction in mitosis, and areas of interstitial thickening with fibroblast proliferation. In addition, the lungs showed disruption of the bronchiolar wall and denudation of the bronchiolar respiratory epithelium while the liver showed hydropic degeneration and coagulative necrosis of the centrilobular hepatocytes. These histotoxic changes were ameliorated in the vanadium + vitamin E group. We conclude that lactational vitamin E protects against the histotoxic effects of vanadium and could be a consideration for supplementation in the occupationally and environmentally exposed neonates. However, caution should be taken in vitamin E supplementation because there is still equivocal evidence surrounding its benefits as a supplement at the moment.

Single-Event Effects in Silicon Carbide Power Devices

NASA Technical Reports Server (NTRS)

Lauenstein, Jean-Marie; Casey, Megan C.; LaBel, Kenneth A.; Ikpe, Stanley; Topper, Alyson D.; Wilcox, Edward P.; Kim, Hak; Phan, Anthony M.

2015-01-01

This report summarizes the NASA Electronic Parts and Packaging Program Silicon Carbide Power Device Subtask efforts in FY15. Benefits of SiC are described and example NASA Programs and Projects desiring this technology are given. The current status of the radiation tolerance of silicon carbide power devices is given and paths forward in the effort to develop heavy-ion single-event effect hardened devices indicated.

Process for preparing fine-grain metal carbide powder

DOEpatents

Kennedy, C.R.; Jeffers, F.P.

Fine-grain metal carbide powder suitable for use in the fabrication of heat resistant products is prepared by coating bituminous pitch on SiO/sub 2/ or Ta/sub 2/O/sub 5/ particles, heating the coated particles to convert the bituminous pitch to coke, and then heating the particles to a higher temperature to convert the particles to a carbide by reaction of said coke therewith.

Vanadium sorption by mineral soils: Development of a predictive model.

PubMed

Larsson, Maja A; Hadialhejazi, Golshid; Gustafsson, Jon Petter

2017-02-01

The toxicity of vanadium in soils depends on its sorption to soil components. Here we studied the vanadate(V) sorption properties of 26 mineral soils. The data were used to optimise parameters for a Freundlich equation with a pH term. Vanadium K-edge XANES spectroscopy for three selected soils confirmed that the added vanadate(V) had accumulated mostly as adsorbed vanadate(V) on Fe and Al hydrous oxides, with only minor contributions from organically complexed vanadium(IV). Data on pH-dependent V solubility for seven soils showed that on average 0.36 H + accompanied each V during adsorption and desorption. The resulting model provided reasonable fits to the V sorption data, with r 2  > 0.99 for 20 of 26 soils. The observed K dS value, i.e. the ratio of total to dissolved V, was strongly dependent on V addition and soil; it varied between 3 and 4 orders of magnitude. The model was used to calculate the Freundlich sorption strength (FSS), i.e. the amount of V sorbed at [V] = 2.5 mg L -1 , in the concentration range of observed plant toxicities. A close relationship between FSS and oxalate-extractable Fe and Al was found (r 2  = 0.85) when one acidic soil was removed from the regression. The FSS varied between 27 and 8718 mg V kg -1 , showing that the current environmental guidelines can be both under- and overprotective for vanadium. Copyright © 2016 Elsevier Ltd. All rights reserved.

Analysis of microalloy precipitate reversion in steels

NASA Technical Reports Server (NTRS)

Michal, G. M.; Locci, I. E.

1988-01-01

The influence of the ferrite to austenite allotropic transformation on the stability of MXn precipitates in an iron matrix is studied. In the MX phase, M is a group IVb or Vb transition metal, such as niobium, titanium, or vanadium. X is carbon or nitrogen and n is in the range of 0.75-1.0. The application of the present model to the case of vanadium carbide reversion in a microalloyed steel is discussed.

Thermal shock and erosion resistant tantalum carbide ceramic material

NASA Technical Reports Server (NTRS)

Honeycutt, L., III; Manning, C. R. (Inventor)

1978-01-01

Ceramic tantalum carbide artifacts with high thermal shock and mechanical erosion resistance are provided by incorporating tungsten-rhenium and carbon particles in a tantalum carbide matrix. The mix is sintered by hot pressing to form the ceramic article which has a high fracture strength relative to its elastic modulus and thus has an improved thermal shock and mechanical erosion resistance. The tantalum carbide is preferable less than minus 100 mesh, the carbon particles are preferable less than minus 100 mesh, and the tungsten-rhenium particles are preferable elongate, having a length to thickness ratio of at least 2/1. Tungsten-rhenium wire pieces are suitable as well as graphite particles.

64. INTERIOR VIEW OF THE CARBIDE COOLING SHED. VIEW IS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

64. INTERIOR VIEW OF THE CARBIDE COOLING SHED. VIEW IS SHOWING CALCIUM CARBIDE IN COOLING CARS ON THE FLOOR. DECEMBER 26, 1918. - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

Structural and thermal properties of vanadium tellurite glasses

NASA Astrophysics Data System (ADS)

Kaur, Rajinder; Kaur, Ramandeep; Khanna, Atul; González, Fernando

2018-04-01

V2O5-TeO2 glasses containing 10 to 50 mol% V2O5 were prepared by melt quenching and characterized by X-ray diffraction (XRD), density, Differential Scanning Calorimetry (DSC) and Raman studies.XRD confirmed the amorphous nature of vanadium tellurite samples. The density of the glasses decreases and the molar volume increases on increasing the concentration of V2O5. The thermal properties, such as glass transition temperature Tg, crystallization temperature Tc, and the melting temperature Tm were measured. Tg decreases from a value of 288°C to 232°C. The changes in Tg were correlated with the number of bonds per unit volume, and the average stretching force constant. Raman spectra were used to elucidate the short-range structure of vanadium tellurite glasses.

Carbide coated fibers in graphite-aluminum composites

NASA Technical Reports Server (NTRS)

Imprescia, R. J.; Levinson, L. S.; Reiswig, R. D.; Wallace, T. C.; Williams, J. M.

1975-01-01

The NASA-supported program at the Los Alamos Scientific Laboratory (LASL) to develop carbon fiber-aluminum matrix composites is described. Chemical vapor deposition (CVD) was used to uniformly deposit thin, smooth, continuous coats of TiC on the fibers of graphite tows. Wet chemical coating of fibers, followed by high-temperature treatment, was also used, but showed little promise as an alternative coating method. Strength measurements on CVD coated fiber tows showed that thin carbide coats can add to fiber strength. The ability of aluminum alloys to wet TiC was successfully demonstrated using TiC-coated graphite surfaces. Pressure-infiltration of TiC- and ZrC-coated fiber tows with aluminum alloys was only partially successful. Experiments were performed to evaluate the effectiveness of carbide coats on carbon as barriers to prevent reaction between alluminum alloys and carbon. Initial results indicate that composites of aluminum and carbide-coated graphite are stable for long periods of time at temperatures near the alloy solidus.

Sulfonated graphene oxide/nafion composite membrane for vanadium redox flow battery.

PubMed

Kim, Byung Guk; Han, Tae Hee; Cho, Chang Gi

2014-12-01

Nafion is the most frequently used as the membrane material due to its good proton conductivity, and excellent chemical and mechanical stabilities. But it is known to have poor barrier property due to its well-developed water channels. In order to overcome this drawback, graphene oxide (GO) derivatives were introduced for Nafion composite membranes. Sulfonated graphene oxide (sGO) was prepared from GO. Both sGO and GO were treated each with phenyl isocyanate and transformed into corresponding isGO and iGO in order to promote miscibility with Nafion. Then composite membranes were obtained, and the adaptability as a membrane for vanadium redox flow battery (VRFB) was investigated in terms of proton conductivity and vanadium permeability. Compared to a pristine Nafion, proton conductivities of both isGO/Nafion and iGO/Nafion membranes showed less temperature sensitivity. Both membranes also showed quite lower vanadium permeability at room temperature. Selectivity of the membrane was the highest for isGO/Nafion and the lowest for the pristine Nafion.