Sample records for tantalum 174

  1. The tantalum-cased tantalum capacitor

    NASA Technical Reports Server (NTRS)

    Moynihan, J. D.

    1977-01-01

    Tantalum-cased tantalum capacitors were tested with regard to temperature stability, capacitance ratio, surge current capabilities, shock, vibration, and thermal shock. They were found to be superior to the conventional wet slug tantalum capacitor cased in silver, since they are more resistant to sulfuric acid. The tantalum-cased tantalum capacitors are widely accepted for use in critical electronic equipment because of their excellent performance and reliability.

  2. Packed bed carburization of tantalum and tantalum alloy

    DOEpatents

    Lopez, Peter C.; Rodriguez, Patrick J.; Pereyra, Ramiro A.

    1999-01-01

    Packed bed carburization of a tantalum or tantalum alloy object. A method for producing corrosion-resistant tantalum or tantalum alloy objects is described. The method includes the steps of placing the object in contact with a carburizing pack, heating the packed object in vacuum furnace to a temperature whereby carbon from the pack diffuses into the object forming grains with tantalum carbide along the grain boundaries, and etching the surface of the carburized object. This latter step removes tantalum carbides from the surface of the carburized tantalum object while leaving the tantalum carbide along the grain boundaries.

  3. Packed bed carburization of tantalum and tantalum alloy

    DOEpatents

    Lopez, P.C.; Rodriguez, P.J.; Pereyra, R.A.

    1999-06-29

    Packed bed carburization of a tantalum or tantalum alloy object is disclosed. A method for producing corrosion-resistant tantalum or tantalum alloy objects is described. The method includes the steps of placing the object in contact with a carburizing pack, heating the packed object in vacuum furnace to a temperature whereby carbon from the pack diffuses into the object forming grains with tantalum carbide along the grain boundaries, and etching the surface of the carburized object. This latter step removes tantalum carbides from the surface of the carburized tantalum object while leaving the tantalum carbide along the grain boundaries. 4 figs.

  4. METHOD OF FORMING TANTALUM SILICIDE ON TANTALUM SURFACES

    DOEpatents

    Bowman, M.G.; Krikorian, N.H.

    1961-10-01

    A method is described for forming a non-corrosive silicide coating on tantalum. The coating is made through the heating of trirhenium silicides in contact with the tantalum object to approximately 1400 deg C at which temperature trirhenium silicide decomposes into rhenium and gaseous silicons. The silicon vapor reacts with the tantalum surface to form a tantalum silicide layer approximately 10 microns thick. (AEC)

  5. Tungsten-reinforced tantalum

    NASA Technical Reports Server (NTRS)

    Bacigalupi, R. J.; Breitwieser, R.

    1972-01-01

    Method is described for producing tungsten-reinforced tantalum, a material possessing the high temperature strength of tungsten and room temperature ductility and weldability of tantalum. This material is produced by bonding together and overlaying structure of tungsten wires with chemical vapor deposited tantalum.

  6. Copper-tantalum alloy

    DOEpatents

    Schmidt, Frederick A.; Verhoeven, John D.; Gibson, Edwin D.

    1986-07-15

    A tantalum-copper alloy can be made by preparing a consumable electrode consisting of an elongated copper billet containing at least two spaced apart tantalum rods extending longitudinally the length of the billet. The electrode is placed in a dc arc furnace and melted under conditions which co-melt the copper and tantalum to form the alloy.

  7. All-tantalum electrolytic capacitor

    NASA Technical Reports Server (NTRS)

    Green, G. E., Jr.

    1977-01-01

    Device uses single-compression tantalum-to-tantalum seal. Single-compression seal allows better utilization of volume within device. As result of all-tantalum case and lengthened cathode, electrical parameters, particularly equivalent series resistance and capacitance stability, improved over silver-cased capacitor.

  8. Niobium and tantalum

    USGS Publications Warehouse

    Schulz, Klaus J.; Piatak, Nadine M.; Papp, John F.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Niobium and tantalum are transition metals that are almost always found together in nature because they have very similar physical and chemical properties. Their properties of hardness, conductivity, and resistance to corrosion largely determine their primary uses today. The leading use of niobium (about 75 percent) is in the production of high-strength steel alloys used in pipelines, transportation infrastructure, and structural applications. Electronic capacitors are the leading use of tantalum for high-end applications, including cell phones, computer hard drives, and such implantable medical devices as pacemakers. Niobium and tantalum are considered critical and strategic metals based on the potential risks to their supply (because current production is restricted to only a few countries) and the significant effects that a restriction in supply would have on the defense, energy, high-tech industrial, and medical sectors.The average abundance of niobium and tantalum in bulk continental crust is relatively low—8.0 parts per million (ppm) niobium and 0.7 ppm tantalum. Their chemical characteristics, such as small ionic size and high electronic field strength, significantly reduce the potential for these elements to substitute for more common elements in rock-forming minerals and make niobium and tantalum essentially immobile in most aqueous solutions. Niobium and tantalum do not occur naturally as pure metals but are concentrated in a variety of relatively rare oxide and hydroxide minerals, as well as in a few rare silicate minerals. Niobium is primarily derived from the complex oxide minerals of the pyrochlore group ((Na,Ca,Ce)2(Nb,Ti,Ta)2(O,OH,F)7), which are found in some alkaline granite-syenite complexes (that is, igneous rocks containing sodium- or potassium-rich minerals and little or no quartz) and carbonatites (that is, igneous rocks that are more than 50 percent composed of primary carbonate minerals, by volume). Tantalum is derived mostly from the

  9. Electrodeposition of Tantalum and Tantalum-Chromium Alloys

    DTIC Science & Technology

    1980-05-01

    Electrochem Soc, 112, 840 (1965). 7Ibid, 113,60 (1966). 8Ibid, 113.66 (1966). J. Wurm, "European Conference on the Development of Molten Salts Applica...Chem. 35, 161-3 (1887). 16. J. Wurm, "European Conference on the Development of Molten Salts Applica- tions," Extended Abstracts and Proceedings, pp...Metals Tantalum Tantalum-Chromium Alloys Chromium Coating Fused Salt Electrolyte Electrodeposition FLINAK 20. ABSTRACT (Continue on reverse

  10. Metastable tantalum oxide formation during the devitrification of amorphous tantalum thin films

    DOE PAGES

    Donaldson, Olivia K.; Hattar, Khalid; Trelewicz, Jason R.

    2016-07-04

    Microstructural evolution during the devitrification of amorphous tantalum thin films synthesized via pulsed laser deposition was investigated using in situ transmission electron microscopy (TEM) combined with ex situ isothermal annealing, bright-field imaging, and electron-diffraction analysis. The phases formed during crystallization and their stability were characterized as a function of the chamber pressure during deposition, devitrification temperature, and annealing time. A range of metastable nanocrystalline tantalum oxides were identified following devitrification including multiple orthorhombic oxide phases, which often were present with, or evolved to, the tetragonal TaO 2 phase. While the appearance of these phases indicated the films were evolving tomore » the stable form of tantalum oxide—monoclinic tantalum pentoxide—it was likely not achieved for the conditions considered due to an insufficient amount of oxygen present in the films following deposition. Nevertheless, the collective in situ and ex situ TEM analysis applied to thin film samples enabled the isolation of a number of metastable tantalum oxides. As a result, new insights were gained into the transformation sequence and stability of these nanocrystalline phases, which presents opportunities for the development of advanced tantalum oxide-based dielectric materials for novel memristor designs.« less

  11. An experimental study of the solubility and speciation of tantalum in fluoride-bearing aqueous solutions at elevated temperature

    DOE PAGES

    Timofeev, Alexander; Migdisov, Art. A.; Williams-Jones, A. E.

    2016-10-27

    Here, the solubility of Ta 2O 5 (solid) and the speciation of tantalum in HF-bearing aqueous solutions have been determined at temperatures of 100-250 °C and vapour-saturated water pressure. Tantalum is transported as the species Ta(OH) 5 0 at low HF concentration and pH ~1-3. At higher HF concentration, tantalum mobility is controlled by the species TaF 3(OH) 3- and TaF 5; the presence of TaF 5 0 is only evident at ≤150 °C. Equilibrium constants range from -17.4 ± 0.45 to -16.4 ± 0.12 for the formation of Ta(OH) 5 from crystalline Ta 2O 5 and from -8.24 ±more » 0.64 to -8.55 ± 0.68 for the formation of TaF 3(OH) 3- at 100 and 250 °C, respectively. For TaF 5 0, they were determined to be 0.13 at 100 °C and -0.35 at 150 °C.« less

  12. Tantalum recycling in the United States in 1998

    USGS Publications Warehouse

    Cunningham, Larry D.

    2001-01-01

    This report describes the flow of tantalum in the United States in 1998 with emphasis on the extent to which tantalum was recycled/reused. Tantalum was mostly recycled from new scrap that was generated during the manufacture of tantalum-related electronic components and new and old scrap products of tantalum-containing cemented carbides and superalloys. In 1998, about 210 metric tons of tantalum was recycled/reused, with about 43% derived from old scrap. The tantalum recycling rate was calculated to be 21%, and tantalum scrap recycling efficiency, 35%.

  13. Semimicrodetermination of tantalum with selenous acid

    USGS Publications Warehouse

    Grimaldi, F.S.; Schnepfe, M.M.

    1958-01-01

    Tantalum is separated and determined gravimetrically by precipitation with selenous acid from a highly acidic solution containing oxalic and tartaric acids. The method is selective for the determination of up to 30 mg. of tantalum pentoxide, and tolerates relatively large amounts of scandium, yttrium, cerium, titanium, zirconium, thorium, vanadium, niobium, molybdenum, tungsten, uranium, iron, aluminum, gallium, tin, lead, antimony, and bismuth. The separation of tantalum from niobium and titanium is not strictly quantitative, and correction is made colorimetrically for the small amounts of niobium and titanium co-precipitating with the tantalum. The method was applied to the determination of tantalum in tantaloniobate ores.

  14. Method of making tantalum capacitors

    DOEpatents

    McMillan, April D.; Clausing, Robert E.; Vierow, William F.

    1998-01-01

    A method for manufacturing tantalum capacitors includes preparing a tantalum compact by cold pressing tantalum powder, placing the compact, along with loose refractory metal powder, in a microwave-transparent casket to form an assembly, and heating the assembly for a time sufficient to effect at least partial sintering of the compact and the product made by the method.

  15. Process for manufacturing tantalum capacitors

    DOEpatents

    Lauf, Robert J.; Holcombe, Cressie E.; Dykes, Norman L.

    1993-01-01

    A process for manufacturing tantalum capacitors in which microwave energy is used to sinter a tantalum powder compact in order to achieve higher surface area and improved dielectric strength. The process comprises cold pressing tantalum powder with organic binders and lubricants to form a porous compact. After removal of the organics, the tantalum compact is heated to 1300.degree. to 2000.degree. C. by applying microwave radiation. Said compact is then anodized to form a dielectric oxide layer and infiltrated with a conductive material such as MnO.sub.2. Wire leads are then attached to form a capacitor to said capacitor is hermetically packaged to form the finished product.

  16. Process for manufacturing tantalum capacitors

    DOEpatents

    Lauf, R.J.; Holcombe, C.E.; Dykes, N.L.

    1993-02-02

    A process for manufacturing tantalum capacitors in which microwave energy is used to sinter a tantalum powder compact in order to achieve higher surface area and improved dielectric strength. The process comprises cold pressing tantalum powder with organic binders and lubricants to form a porous compact. After removal of the organics, the tantalum compact is heated to 1,300 to 2,000 C by applying microwave radiation. Said compact is then anodized to form a dielectric oxide layer and infiltrated with a conductive material such as MnO[sub 2]. Wire leads are then attached to form a capacitor to said capacitor is hermetically packaged to form the finished product.

  17. Additively manufactured porous tantalum implants.

    PubMed

    Wauthle, Ruben; van der Stok, Johan; Amin Yavari, Saber; Van Humbeeck, Jan; Kruth, Jean-Pierre; Zadpoor, Amir Abbas; Weinans, Harrie; Mulier, Michiel; Schrooten, Jan

    2015-03-01

    The medical device industry's interest in open porous, metallic biomaterials has increased in response to additive manufacturing techniques enabling the production of complex shapes that cannot be produced with conventional techniques. Tantalum is an important metal for medical devices because of its good biocompatibility. In this study selective laser melting technology was used for the first time to manufacture highly porous pure tantalum implants with fully interconnected open pores. The architecture of the porous structure in combination with the material properties of tantalum result in mechanical properties close to those of human bone and allow for bone ingrowth. The bone regeneration performance of the porous tantalum was evaluated in vivo using an orthotopic load-bearing bone defect model in the rat femur. After 12 weeks, substantial bone ingrowth, good quality of the regenerated bone and a strong, functional implant-bone interface connection were observed. Compared to identical porous Ti-6Al-4V structures, laser-melted tantalum shows excellent osteoconductive properties, has a higher normalized fatigue strength and allows for more plastic deformation due to its high ductility. It is therefore concluded that this is a first step towards a new generation of open porous tantalum implants manufactured using selective laser melting. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  18. Radiopharmaceutical composition containing tantalum-178 and process therefor

    DOEpatents

    Neirinckx, Rudi D.; Holman, B. Leonard; Davis, Michael A.; Harris, Gale I.

    1989-05-16

    A physiologically acceptable solution of tantalum-178 having an activity of 0.1 to 200 millicuries per milliliter of tantalum-178 solution is provided. The solution is obtained from tungsten-178 bound to a column of an anion exchange resin which forms tantalum-178 in situ by eluting the column with a hydrochloric acid solution containing hydrogen peroxide to form an acidic solution of tantalum-178. The acidic solution of tantalum-178 then is neutralized.

  19. Mineral resource of the month: tantalum

    USGS Publications Warehouse

    ,

    2011-01-01

    The article offers information on a rare transition metal called tantalum. It says that the blue-gray mineral resource was discovered in 1801 or 1802 and was used for capacitors in 1940. It adds that the tantalite ore and other minerals in the ore should be separated in order to generate concentrates of tantalum. The use of tantalum are also cited.

  20. Performance comparison: Aluminum electrolytic and solid tantalum capacitor

    NASA Technical Reports Server (NTRS)

    Hawthornthwaite, B. G.; Piper, J.; Holland, H. W.

    1981-01-01

    Several key electrical and environmental parameters of latest technology aluminum electrolytic and solid tantalum capacitors were evaluated in terms of price fluctuations of tantalum metal. Performance differences between solid tantalums and aluminum electrolytics are examined.

  1. High strength forgeable tantalum base alloy

    NASA Technical Reports Server (NTRS)

    Buckman, R. W., Jr.

    1975-01-01

    Increasing tungsten content of tantalum base alloy to 12-15% level will improve high temperature creep properties of existing tantalum base alloys while retaining their excellent fabrication and welding characteristics.

  2. Tantalum-based semiconductors for solar water splitting.

    PubMed

    Zhang, Peng; Zhang, Jijie; Gong, Jinlong

    2014-07-07

    Solar energy utilization is one of the most promising solutions for the energy crises. Among all the possible means to make use of solar energy, solar water splitting is remarkable since it can accomplish the conversion of solar energy into chemical energy. The produced hydrogen is clean and sustainable which could be used in various areas. For the past decades, numerous efforts have been put into this research area with many important achievements. Improving the overall efficiency and stability of semiconductor photocatalysts are the research focuses for the solar water splitting. Tantalum-based semiconductors, including tantalum oxide, tantalate and tantalum (oxy)nitride, are among the most important photocatalysts. Tantalum oxide has the band gap energy that is suitable for the overall solar water splitting. The more negative conduction band minimum of tantalum oxide provides photogenerated electrons with higher potential for the hydrogen generation reaction. Tantalates, with tunable compositions, show high activities owning to their layered perovskite structure. (Oxy)nitrides, especially TaON and Ta3N5, have small band gaps to respond to visible-light, whereas they can still realize overall solar water splitting with the proper positions of conduction band minimum and valence band maximum. This review describes recent progress regarding the improvement of photocatalytic activities of tantalum-based semiconductors. Basic concepts and principles of solar water splitting will be discussed in the introduction section, followed by the three main categories regarding to the different types of tantalum-based semiconductors. In each category, synthetic methodologies, influencing factors on the photocatalytic activities, strategies to enhance the efficiencies of photocatalysts and morphology control of tantalum-based materials will be discussed in detail. Future directions to further explore the research area of tantalum-based semiconductors for solar water splitting

  3. Tantalum-copper alloy and method for making

    DOEpatents

    Schmidt, Frederick A.; Verhoeven, John D.; Gibson, Edwin D.

    1984-11-06

    A tantalum-copper alloy can be made by preparing a consumable electrode consisting of an elongated copper billet containing at least two spaced apart tantalum rods extending longitudinally the length of the billet. The electrode is placed in a dc arc furnace and melted under conditions which co-melt the copper and tantalum to form the alloy.

  4. Tantalum-copper alloy and method for making

    DOEpatents

    Schmidt, F.A.; Verhoeven, J.D.; Gibson, E.D.

    1983-06-01

    A tantalum-copper alloy can be made by preparing a consumable electrode consisting of an elongated copper billet containing at least two spaced apart tantalum rods extending longitudinally the length of the billet. The electrode is placed in a dc arc furnace and melted under conditions which co-melt the copper and tantalum to form the alloy.

  5. Purification of tantalum by plasma arc melting

    DOEpatents

    Dunn, Paul S.; Korzekwa, Deniece R.

    1999-01-01

    Purification of tantalum by plasma arc melting. The level of oxygen and carbon impurities in tantalum was reduced by plasma arc melting the tantalum using a flowing plasma gas generated from a gas mixture of helium and hydrogen. The flowing plasma gases of the present invention were found to be superior to other known flowing plasma gases used for this purpose.

  6. Ultraviolet spectrophotometric determination of tantalum with pyrogallol

    USGS Publications Warehouse

    Dinnin, J.I.

    1953-01-01

    In a search for a more rapid method for the determination of tantalum in rocks and minerals, an intensive study was made of the tantalum-pyrogallol reaction recommended by Platanov and Krivoshlikov, and a better modified spectrophotometric procedure is given. The improved method consists in measuring the absorbancy of the tantalum-pyrogallol complex at 325 m?? in 4N hydrochloric acid and a fixed concentration (0.0175M) of ammonium oxalate. Beer's law is followed for the concentration range up to 40 ?? per ml. Sensitivity in terms of molar absorbancy index is 4775. Most interferences are additive in character and readily correctable. Separations or major corrections are required in the presence of significant amounts of molybdenum, tungsten, antimony, and uranium. The method has been successfully applied to three ores previously analyzed by gravimetric techniques. The method affords greater speed, sensitivity, and reproducibility in the determination of tantalum in rocks and minerals. A more reliable technique for preparing standard solutions of tantalum has been developed.

  7. Study of constitution diagram aluminum-tantalum

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

    Glazov, V.M.; Mal'tsev, M.V.; Chistyakov, Y.D.

    1988-10-20

    Alloys of aluminum with tantalum were for the first time obtained by aluminothermic method in 1868 by Moriniak. Later these alloys were studied in the works of Schirmeister (1915) and Brouwer (1938), moreover Brouwer established that tantalum with aluminum forms the chemical compound TaA1, which has tetragonal crystal lattice with parameters a=5.422 angstroms and c=8.536 angstroms (1). However despite the fact that alloys of aluminum with tantalum long ago are obtained already, constitution diagram of this system is not studied until recently. In connection with the application of tantalum as the modifying additive in aluminum alloys an emergency in themore » construction of this diagram, without the knowledge by which it is not possible to give the correct explanation of the mechanism of the very process of the modification of primary grain. For this purpose was undertaken this work. Russian translations.« less

  8. Niobium and tantalum: indispensable twins

    USGS Publications Warehouse

    Schulz, Klaus; Papp, John

    2014-01-01

    Niobium and tantalum are transition metals almost always paired together in nature. These “twins” are difficult to separate because of their shared physical and chemical properties. In 1801, English chemist Charles Hatchett uncovered an unknown element in a mineral sample of columbite; John Winthrop found the sample in a Massachusetts mine and sent it to the British Museum in London in 1734. The name columbium, which Hatchet named the new element, came from the poetic name for North America—Columbia—and was used interchangeably for niobium until 1949, when the name niobium became official. Swedish scientist Anders Ekberg discovered tantalum in 1802, but it was confused with niobium, because of their twinned properties, until 1864, when it was recognized as a separate element. Niobium is a lustrous, gray, ductile metal with a high melting point, relatively low density, and superconductor properties. Tantalum is a dark blue-gray, dense, ductile, very hard, and easily fabricated metal. It is highly conductive to heat and electricity and renowned for its resistance to acidic corrosion. These special properties determine their primary uses and make niobium and tantalum indispensable.

  9. Structure refinement for tantalum nitrides nanocrystals with various morphologies

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

    Liu, Lianyun; School of Science, Beijing Jiaotong University, 3 Shang Yuan Cun, Haidian District, Beijing 100044; Huang, Kai

    2012-07-15

    Graphical abstract: Tantalum nitrides nanocrystals with various phases and morphologies for the first time have been synthesized through homogenous sodium reduction under low temperature with the subsequent annealing process under high vacuum. Highlights: ► The spherical TaN, cuboidal TaN{sub 0.83} and TaN{sub 0.5} nanocrystals have been synthesized through homogenous sodium reduction under low temperature with the subsequent annealing process under high vacuum. ► The crystal structures of different tantalum nitrides were determined by Rietveld refinement on the X-ray diffraction data and the examinations of electron microcopies. ► The specific surface area of the tantalum nitrides powders was around 10 m{supmore » 2} g{sup −1}. ► Tantalum nitrides powders could be suitable for capacitor with high specific capacitance. -- Abstract: Tantalum nitrides (TaN{sub x}) nanocrystals with different phase and morphology have been synthesized through homogenous sodium reduction under low temperature with the subsequent annealing process under high vacuum. The crystal structures of tantalum nitrides were determined by Rietveld refinement based on the X-ray diffraction data. The morphologies of various tantalum nitrides nanocrystals in high quality were analyzed through the electron microcopies examinations. The spherical TaN nanoparticles, cuboidal TaN{sub 0.83} and TaN{sub 0.5} nanocrystals have been selectively prepared at different annealing temperatures. In addition, the specific surface areas of the tantalum nitrides nanocrystals measured by BET method were around 9.87–11.64 m{sup 2} g{sup −1}, indicating that such nano-sized tantalum nitrides could be suitable for capacitor with high specific capacitance.« less

  10. Scintillation Breakdowns in Chip Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2008-01-01

    Scintillations in solid tantalum capacitors are momentarily local breakdowns terminated by a self-healing or conversion to a high-resistive state of the manganese oxide cathode. This conversion effectively caps the defective area of the tantalum pentoxide dielectric and prevents short-circuit failures. Typically, this type of breakdown has no immediate catastrophic consequences and is often considered as nuisance rather than a failure. Scintillation breakdowns likely do not affect failures of parts under surge current conditions, and so-called "proofing" of tantalum chip capacitors, which is a controllable exposure of the part after soldering to voltages slightly higher than the operating voltage to verify that possible scintillations are self-healed, has been shown to improve the quality of the parts. However, no in-depth studies of the effect of scintillations on reliability of tantalum capacitors have been performed so far. KEMET is using scintillation breakdown testing as a tool for assessing process improvements and to compare quality of different manufacturing lots. Nevertheless, the relationship between failures and scintillation breakdowns is not clear, and this test is not considered as suitable for lot acceptance testing. In this work, scintillation breakdowns in different military-graded and commercial tantalum capacitors were characterized and related to the rated voltages and to life test failures. A model for assessment of times to failure, based on distributions of breakdown voltages, and accelerating factors of life testing are discussed.

  11. 21 CFR 886.3100 - Ophthalmic tantalum clip.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... blood vessels in the eye. (b) Classification. Class II (special controls). The device is exempt from the...) MEDICAL DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3100 Ophthalmic tantalum clip. (a) Identification. An ophthalmic tantalum clip is a malleable metallic device intended to be implanted permanently...

  12. Efficacy of Tantalum Tungsten Alloys for Diffusion Barrier Applications

    NASA Astrophysics Data System (ADS)

    Smathers, D. B.; Aimone, P. R.

    2017-12-01

    Traditionally either Niobium, Tantalum or a combination of both have been used as diffusion barriers in Nb3Sn Multi-filament wire. Vanadium has also been used successfully but the ultimate RRR of the copper is limited unless an external shell of Niobium is included. Niobium is preferred over Tantalum when alternating current losses are not an issue as the Niobium will react to form Nb3Sn. Pure Tantalum tends to deform irregularly requiring extra starting thickness to ensure good barrier qualities. Our evaluations showed Tantalum lightly alloyed with 3 wt% Tungsten is compatible with the wire drawing process while deforming as well as or better than pure Niobium. Ta3wt%W has been processed as a single barrier and as a distributed barrier to fine dimensions. In addition, the higher modulus and strength of the Tantalum Tungsten alloy improves the overall tensile properties of the wire.

  13. Hafnium radioisotope recovery from irradiated tantalum

    DOEpatents

    Taylor, Wayne A.; Jamriska, David J.

    2001-01-01

    Hafnium is recovered from irradiated tantalum by: (a) contacting the irradiated tantalum with at least one acid to obtain a solution of dissolved tantalum; (b) combining an aqueous solution of a calcium compound with the solution of dissolved tantalum to obtain a third combined solution; (c) precipitating hafnium, lanthanide, and insoluble calcium complexes from the third combined solution to obtain a first precipitate; (d) contacting the first precipitate of hafnium, lanthanide and calcium complexes with at least one fluoride ion complexing agent to form a fourth solution; (e) selectively adsorbing lanthanides and calcium from the fourth solution by cationic exchange; (f) separating fluoride ion complexing agent product from hafnium in the fourth solution by adding an aqueous solution of ferric chloride to obtain a second precipitate containing the hafnium and iron; (g) dissolving the second precipitate containing the hafnium and iron in acid to obtain an acid solution of hafnium and iron; (h) selectively adsorbing the iron from the acid solution of hafnium and iron by anionic exchange; (i) drying the ion exchanged hafnium solution to obtain hafnium isotopes. Additionally, if needed to remove residue remaining after the product is dried, dissolution in acid followed by cation exchange, then anion exchange, is performed.

  14. Intense photoluminescence from amorphous tantalum oxide films

    NASA Astrophysics Data System (ADS)

    Zhu, Minmin; Zhang, Zhengjun; Miao, Wei

    2006-07-01

    Tantalum oxide films were deposited on silicon substrates at a temperature of ˜450°C by heating a pure tantalum foil in a rough vacuum. The films were amorphous in structure and consisted of fully oxidized Ta2O5 and (TaOx, x <2.5) suboxides. This feature resulted in strong visible light emission from the films further oxidized in the air at temperatures of 200-300°C. The mechanism for this photoluminescence behavior of the amorphous tantalum oxide films was also investigated and discussed. This study suggests that wide-band-gap materials could act as effective visible light emitters and provides a simple route to synthesize such materials.

  15. Electronic structure and charge transport in nonstoichiometric tantalum oxide

    NASA Astrophysics Data System (ADS)

    Perevalov, T. V.; Gritsenko, V. A.; Gismatulin, A. A.; Voronkovskii, V. A.; Gerasimova, A. K.; Aliev, V. Sh; Prosvirin, I. A.

    2018-06-01

    The atomic and electronic structure of nonstoichiometric oxygen-deficient tantalum oxide TaO x<2.5 grown by ion beam sputtering deposition was studied. The TaO x film content was analyzed by x-ray photoelectron spectroscopy and by quantum-chemistry simulation. TaO x is composed of Ta2O5, metallic tantalum clusters and tantalum suboxides. A method for evaluating the stoichiometry parameter of TaO x from the comparison of experimental and theoretical photoelectron valence band spectra is proposed. The charge transport properties of TaO x were experimentally studied and the transport mechanism was quantitatively analyzed with four theoretical dielectric conductivity models. It was found that the charge transport in almost stoichiometric and nonstoichiometric tantalum oxide can be consistently described by the phonon-assisted tunneling between traps.

  16. High Temperature Evaluation of Tantalum Capacitors - Test 1

    DOE Data Explorer

    Cieslewski, Grzegorz

    2014-09-28

    Tantalum capacitors can provide much higher capacitance at high-temperatures than the ceramic capacitors. This study evaluates selected tantalum capacitors at high temperatures to determine their suitability for you in geothermal field. This data set contains results of the first test where three different types of capacitors were evaluated at 260C.

  17. 2017 NEPP Tasks Update for Ceramic and Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander A.

    2017-01-01

    This presentation gives an overview of current NEPP tasks on ceramic and tantalum capacitors and plans for the future. It includes tasks on leakage currents, gas generation and case deformation in wet tantalum capacitors; ESR degradation and acceleration factors in MnO2 and polymer cathode capacitors. Preliminary results on the effect of moisture on degradation of reverse currents in MnO2 tantalum capacitors are discussed. Latest results on mechanical characteristics of MLCCs and modeling of degradation of leakage currents in BME capacitors with defects are also presented.

  18. METHOD OF PROTECTING TANTALUM CRUCIBLES AGAINST REACTION WITH MOLTEN URANIUM

    DOEpatents

    Feder, H.M.; Chellew, N.R.

    1960-08-16

    Tantalum crucibles against reaction with molten uranium by contacting the surfaces to be protected with metallic boron (as powder, vapor, or suspension in a liquid-volatilenonreacting medium, such as acetone and petroleum oil) at about 1800 deg C in vacuum, discontinuing contact with the boron, and heating the crucibles to a temperature of between 1800 aad 2000 deg C, whereby the tantalum boride formed in the first heating step is converted to tantalum monoboride.

  19. Fabrication of a Tantalum-Based Josephson Junction for an X-Ray Detector

    NASA Astrophysics Data System (ADS)

    Morohashi, Shin'ichi; Gotoh, Kohtaroh; Yokoyama, Naoki

    2000-06-01

    We have fabricated a tantalum-based Josephson junction for an X-ray detector. The tantalum layer was selected for the junction electrode because of its long quasiparticle lifetime, large X-ray absorption efficiency and stability against thermal cycling. We have developed a buffer layer to fabricate the tantalum layer with a body-centered cubic structure. Based on careful consideration of their superconductivity, we have selected a niobium thin layer as the buffer layer for fabricating the tantalum base electrode, and a tungsten thin layer for the tantalum counter electrode. Fabricated Nb/AlOx-Al/Ta/Nb and Nb/Ta/W/AlOx-Al/Ta/Nb Josephson junctions exhibited current-voltage characteristics with a low subgap leakage current.

  20. Extreme Response in Tension and Compression of Tantalum

    NASA Astrophysics Data System (ADS)

    Remington, Tane Perry

    This research on a model bcc metal, tantalum, has three components: the study of tensile failure; defects generated under a nanoindenter; and dislocation velocities in an extreme regime generated by pulsed lasers. The processes of dynamic failure by spalling were established in nano, poly, and mono crystalline tantalum in recovery experiments following laser compression and release. The process of spall was characterized by different techniques: optical microscopy, scanning electron microscopy, microcomputerized tomography and electron backscatter diffraction. Additionally, the pull back signal was measured by VISAR and the pressure decay was compared with HYADES simulations. There are clear differences in the microscopic fracture mechanisms, dictated by the grain sizes. In the nano and poly crystals, spalling occurred by ductile fracture favoring grain boundaries. In the monocrystals, grain boundaries are absent, and the process was of ductile failure by void initiation, growth and coalescence. The spall strength of single crystalline tantalum was higher than the poly and nano crystals. It was experimentally confirmed that spall strength in tantalum increases with strain rate. In order to generate dislocations close to the surface, single crystalline tantalum with orientations (100), (110) and (111) was nanoindented with a Berkovich tip. Atomic force microscopy showed pile-ups of dislocations around the perimeter of the nanoindentations. Sections of nanoindentations were focused ion beam cut into transmission electron microscope foils. The mechanisms of deformation under a nanoindentation in tantalum were identified and quantified. Molecular dynamics simulations were conducted and the simulated plastic deformation proceeds by the formation of nanotwins, which rapidly evolve into shear dislocation loops. Dislocation densities under the indenter were estimated experimentally (~1.2 x 1015 m-2), by MD (~7 x1015 m-2) and through an analytical calculation (2.6--19 x10

  1. Fabrication of a tantalum-clad tungsten target for LANSCE

    NASA Astrophysics Data System (ADS)

    Nelson, A. T.; O'Toole, J. A.; Valicenti, R. A.; Maloy, S. A.

    2012-12-01

    Development of a solid state bonding technique suitable to clad tungsten targets with tantalum was completed to improve operation of the Los Alamos Neutron Science Centers spallation target. Significant deterioration of conventional bare tungsten targets has historically resulted in transfer of tungsten into the cooling system through corrosion resulting in increased radioactivity outside the target and reduction of delivered neutron flux. The fabrication method chosen to join the tantalum cladding to the tungsten was hot isostatic pressing (HIP) given the geometry constraints of a cylindrical assembly and previous success demonstrated at KENS. Nominal HIP parameters of 1500 °C, 200 MPa, and 3 h were selected based upon previous work. Development of the process included significant surface engineering controls and characterization given tantalums propensity for oxide and carbide formation at high temperatures. In addition to rigorous acid cleaning implemented at each step of the fabrication process, a three layer tantalum foil gettering system was devised such that any free oxygen and carbon impurities contained in the argon gas within the HIP vessel was mitigated to the extent possible before coming into contact with the tantalum cladding. The result of the numerous controls and refined techniques was negligible coarsening of the native Ta2O5 surface oxide, no measureable oxygen diffusion into the tantalum bulk, and no detectable carburization despite use of argon containing up to 5 ppm oxygen and up to 40 ppm total CO, CO2, or organic contaminants. Post bond characterization of the interface revealed continuous bonding with a few microns of species interdiffusion.

  2. ON THE GEOCHEMISTRY OF NIOBIUM AND TANTALUM IN CLAYS (in Russian)

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

    Pachadzhanov, D.N.

    1963-10-01

    With the aid of the spectral method with a preliminary enrichment in tannin, the niobium and tantalum content was determined in some humid and arid clays of the Russian platform. The investigated samples were composed of 354 specimens. The average content of niobium in humid clays is 0.0020%, of tantalum 0.00024% (the Nb/Ta ratio is 8.4) and in arid clays is respectively the content of niobium 0.00133% and the content of tantalum 0.00009% (the Nb/Ta ratio is 14.8). The average value of the content of niobium content for all studied clays is 0.00183% and of the tantalum content 0.00020%, themore » Nb/Ta ratio being 9.1. In clays an interconnection of niobium with tantalum, as well as with aluminium, titanium, zirconium, and hafnium was observed. However, on the background of this connection some separation of the named elements is noted. A tendency for the Nb/Ta ratio shift from the region of matter removal towards the center of the marine basin was observed. The study of niobium and tantalum distribution over different clay fractions showed that one part of elements is connected with zircon and titanium minerals in aleuosand fraction (0.1-- 0.01 mm). Another, approximately similar part is contained in the proper clay fraction (<0. 01 mm), the tantalum somewhat more concentrating in the aleurosand fraction and niobium in the clay fraction. (P.C.H.)« less

  3. Multi-scale Modeling of Plasticity in Tantalum.

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

    Lim, Hojun; Battaile, Corbett Chandler.; Carroll, Jay

    In this report, we present a multi-scale computational model to simulate plastic deformation of tantalum and validating experiments. In atomistic/ dislocation level, dislocation kink- pair theory is used to formulate temperature and strain rate dependent constitutive equations. The kink-pair theory is calibrated to available data from single crystal experiments to produce accurate and convenient constitutive laws. The model is then implemented into a BCC crystal plasticity finite element method (CP-FEM) model to predict temperature and strain rate dependent yield stresses of single and polycrystalline tantalum and compared with existing experimental data from the literature. Furthermore, classical continuum constitutive models describingmore » temperature and strain rate dependent flow behaviors are fit to the yield stresses obtained from the CP-FEM polycrystal predictions. The model is then used to conduct hydro- dynamic simulations of Taylor cylinder impact test and compared with experiments. In order to validate the proposed tantalum CP-FEM model with experiments, we introduce a method for quantitative comparison of CP-FEM models with various experimental techniques. To mitigate the effects of unknown subsurface microstructure, tantalum tensile specimens with a pseudo-two-dimensional grain structure and grain sizes on the order of millimeters are used. A technique combining an electron back scatter diffraction (EBSD) and high resolution digital image correlation (HR-DIC) is used to measure the texture and sub-grain strain fields upon uniaxial tensile loading at various applied strains. Deformed specimens are also analyzed with optical profilometry measurements to obtain out-of- plane strain fields. These high resolution measurements are directly compared with large-scale CP-FEM predictions. This computational method directly links fundamental dislocation physics to plastic deformations in the grain-scale and to the engineering-scale applications. Furthermore

  4. Development and Applications of Porous Tantalum Trabecular Metal Enhanced Titanium Dental Implants

    PubMed Central

    Bencharit, Sompop; Byrd, Warren C.; Altarawneh, Sandra; Hosseini, Bashir; Leong, Austin; Reside, Glenn; Morelli, Thiago; Offenbacher, Steven

    2013-01-01

    Statement of Problem Porous tantalum trabecular metal has recently been incorporated in titanium dental implants as a new form of implant surface enhancement. However, there is little information on the applications of this material in implant dentistry. Methods We, therefore review the current literature on the basic science and clinical uses of this material. Results Porous tantalum metal is used to improve the contact between osseous structure and dental implants; and therefore presumably facilitate osseointegration. Success of porous tantalum metal in orthopedic implants led to the incorporation of porous tantalum metal in the design of root-from endosseous titanium implants. The porous tantalum three-dimensional enhancement of titanium dental implant surface allows for combining bone ongrowth together with bone ingrowth, or osseoincorporation. While little is known about the biological aspect of the porous tantalum in the oral cavity, there seems to be several possible advantages of this implant design. This article reviews the biological aspects of porous tantalum enhanced titanium dental implants, in particular the effects of anatomical consideration and oral environment to implant designs. Conclusions We propose here possible clinical situations and applications for this type of dental implant. Advantages and disadvantages of the implants as well as needed future clinical studies are discussed. PMID:23527899

  5. World War II, tantalum, and the evolution of modern cranioplasty technique.

    PubMed

    Flanigan, Patrick; Kshettry, Varun R; Benzel, Edward C

    2014-04-01

    Cranioplasty is a unique procedure with a rich history. Since ancient times, a diverse array of materials from coconut shells to gold plates has been used for the repair of cranial defects. More recently, World War II greatly increased the demand for cranioplasty procedures and renewed interest in the search for a suitable synthetic material for cranioprostheses. Experimental evidence revealed that tantalum was biologically inert to acid and oxidative stresses. In fact, the observation that tantalum did not absorb acid resulted in the metal being named after Tantalus, the Greek mythological figure who was condemned to a pool of water in the Underworld that would recede when he tried to take a drink. In clinical use, malleability facilitated a single-stage cosmetic repair of cranial defects. Tantalum became the preferred cranioplasty material for more than 1000 procedures performed during World War II. In fact, its use was rapidly adopted in the civilian population. During World War II and the heyday of tantalum cranioplasty, there was a rapid evolution in prosthesis implantation and fixation techniques significantly shaping how cranioplasties are performed today. Several years after the war, acrylic emerged as the cranioplasty material of choice. It had several clear advantages over its metallic counterparts. Titanium, which was less radiopaque and had a more optimal thermal conductivity profile (less thermally conductive), eventually supplanted tantalum as the most common metallic cranioplasty material. While tantalum cranioplasty was popular for only a decade, it represented a significant breakthrough in synthetic cranioplasty. The experiences of wartime neurosurgeons with tantalum cranioplasty played a pivotal role in the evolution of modern cranioplasty techniques and ultimately led to a heightened understanding of the necessary attributes of an ideal synthetic cranioplasty material. Indeed, the history of tantalum cranioplasty serves as a model for innovative

  6. 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.

  7. International strategic minerals inventory summary report; niobium (columbium) and tantalum

    USGS Publications Warehouse

    Crockett, R.N.; Sutphin, D.M.

    1993-01-01

    Major world resources of niobium and tantalum are described in this summary report of information in the International Strategic Minerals Inventory (ISMI). ISMI is a cooperative data-collection effort of earth-science and mineral-resource agencies in Australia, Canada, the Federal Republic of Germany, the Republic of South Africa, the United Kingdom, and the United States of America. Part I of this report presents an overview of the resources and potential supply of niobium and tantalum based on inventory information; Part II contains tables of both geologic and mineral-resource information and includes production data collected by ISMI participants. Niobium is used principally as an alloying element in special steels and superalloys, and tantalum is used mainly in electronics. Minerals in the columbite-tantalite series are principal ore minerals of niobium and tantalum. Pyrochlore is a principal source of niobium. These minerals are found in carbonatite, certain rocks in alkaline igneous complexes, pegmatite, and placer deposits. ISMI estimates show that there are over 7 million metric tons of niobium and almost 0.5 million metric tons of tantalum in known deposits, outside of China and the former Soviet Union, for which reliable estimates have been made. Brazilian deposits, followed by Canadian deposits, contain by far the largest source of niobium. Tantalum production is spread widely among several countries, and Brazil and Canada are the most significant of these producers. Brazil's position is further strengthened by potential byproduct columbite from tin mining. Present economically exploitable resources of niobium appear to be sufficient for the near future, but Brazil will continue to be the predominant world supplier of ferrocolumbium. Tantalum, a byproduct of tin production, has been captive to the fluctuations of that market, but resources in pegmatite in Canada and Australia make it likely that future increases in the present modest demand will be met.

  8. Thermochemistry of tantalum-wall cooling system with lithium and sodium working fluids

    NASA Technical Reports Server (NTRS)

    Tower, L. K.

    1972-01-01

    Plots are presented which show the distribution of oxygen between liquid lithium and tantalum or niobium, and between liquid sodium and tantalum at elevated temperatures. Additional plots showing the composition of the gas phase above the solutions of oxygen and alkali metal are presented. The use of the plots is illustrated by an example tantalum heat pipe filled with lithium.

  9. Tantalum coatings for inertial confinement fusion dry wall designs

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

    Taylor, L.H.; Green, L.

    1996-12-31

    The coating on a dry first wall inertial confinement fusion reactor must survive the target explosion and be ductile, inexpensive, and compatible with the materials in the target, i.e. have a high atomic number Z. Calculations indicate that tantalum is the best choice for the coating material. As a test of this design 1 mm tantalum coatings were plasma sprayed onto ferrite steel tubes. They were then subjected to 100 heating-cooling cycles which simulated the stressful thermal cycling which would be encountered during five years of plant startups and shutdowns. The coatings were undamaged and continued to bond well tomore » the steel. Furthermore, chemical reactions should not degrade tantalum coatings.« less

  10. Constitutive behavior of tantalum and tantalum-tungsten alloys

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

    Chen, S.R.; Gray, G.T. III

    1996-10-01

    The effects of strain rate, temperature, and tungsten alloying on the yield stress and the strain-hardening behavior of tantalum were investigated. The yield and flow stresses of unalloyed Ta and tantalum-tungsten alloys were found to exhibit very high rate sensitivities, while the hardening rates in Ta and Ta-W alloys were found to be insensitive to strain rate and temperature at lower temperatures or at higher strain rates. This behavior is consistent with the observation that overcoming the intrinsic Peierls stress is shown to be the rate-controlling mechanism in these materials at low temperatures. The dependence of yield stress on temperaturemore » and strain rate was found to decrease, while the strain-hardening rate increased with tungsten alloying content. The mechanical threshold stress (MTS) model was adopted to model the stress-strain behavior of unalloyed Ta and the Ta-W alloys. Parameters for the constitutive relations for Ta and the Ta-W alloys were derived for the MTS model, the Johnson-Cook (JC), and the Zerilli-Armstrong (ZA) models. The results of this study substantiate the applicability of these models for describing the high strain-rate deformation of Ta and Ta-W alloys. The JC and ZA models, however, due to their use of a power strain-hardening law, were found to yield constitutive relations for Ta and Ta-W alloys that are strongly dependent on the range of strains for which the models were optimized.« less

  11. Mineral-deposit model for lithium-cesium-tantalum pegmatites

    USGS Publications Warehouse

    Bradley, Dwight C.; McCauley, Andrew D.; Stillings, Lisa L.

    2017-06-20

    Lithium-cesium-tantalum (LCT) pegmatites comprise a compositionally defined subset of granitic pegmatites. The major minerals are quartz, potassium feldspar, albite, and muscovite; typical accessory minerals include biotite, garnet, tourmaline, and apatite. The principal lithium ore minerals are spodumene, petalite, and lepidolite; cesium mostly comes from pollucite; and tantalum mostly comes from columbite-tantalite. Tin ore as cassiterite and beryllium ore as beryl also occur in LCT pegmatites, as do a number of gemstones and high-value museum specimens of rare minerals. Individual crystals in LCT pegmatites can be enormous: the largest spodumene was 14 meters long, the largest beryl was 18 meters long, and the largest potassium feldspar was 49 meters long.Lithium-cesium-tantalum pegmatites account for about one-fourth of the world’s lithium production, most of the tantalum production, and all of the cesium production. Giant deposits include Tanco in Canada, Greenbushes in Australia, and Bikita in Zimbabwe. The largest lithium pegmatite in the United States, at King’s Mountain, North Carolina, is no longer being mined although large reserves of lithium remain. Depending on size and attitude of the pegmatite, a variety of mining techniques are used, including artisanal surface mining, open-pit surface mining, small underground workings, and large underground operations using room-and-pillar design. In favorable circumstances, what would otherwise be gangue minerals (quartz, potassium feldspar, albite, and muscovite) can be mined along with lithium and (or) tantalum as coproducts.Most LCT pegmatites are hosted in metamorphosed supracrustal rocks in the upper greenschist to lower amphibolite facies. Lithium-cesium-tantalum pegmatite intrusions generally are emplaced late during orogeny, with emplacement being controlled by pre-existing structures. Typically, they crop out near evolved, peraluminous granites and leucogranites from which they are inferred to be

  12. 40 CFR 421.110 - Applicability: Description of the primary columbium-tantalum subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS MANUFACTURING POINT SOURCE... the production of columbium or tantalum by primary columbium-tantalum facilities. [49 FR 8817, Mar. 8...

  13. Reliability Effects of Surge Current Testing of Solid Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2007-01-01

    Solid tantalum capacitors are widely used in space applications to filter low-frequency ripple currents in power supply circuits and stabilize DC voltages in the system. Tantalum capacitors manufactured per military specifications (MIL-PRF-55365) are established reliability components and have less than 0.001% of failures per 1000 hours (the failure rate is less than 10 FIT) for grades D or S, thus positioning these parts among electronic components with the highest reliability characteristics. Still, failures of tantalum capacitors do happen and when it occurs it might have catastrophic consequences for the system. This is due to a short-circuit failure mode, which might be damaging to a power supply, and also to the capability of tantalum capacitors with manganese cathodes to self-ignite when a failure occurs in low-impedance applications. During such a failure, a substantial amount of energy is released by exothermic reaction of the tantalum pellet with oxygen generated by the overheated manganese oxide cathode, resulting not only in destruction of the part, but also in damage of the board and surrounding components. A specific feature of tantalum capacitors, compared to ceramic parts, is a relatively large value of capacitance, which in contemporary low-size chip capacitors reaches dozens and hundreds of microfarads. This might result in so-called surge current or turn-on failures in the parts when the board is first powered up. Such a failure, which is considered as the most prevalent type of failures in tantalum capacitors [I], is due to fast changes of the voltage in the circuit, dV/dt, producing high surge current spikes, I(sub sp) = Cx(dV/dt), when current in the circuit is unrestricted. These spikes can reach hundreds of amperes and cause catastrophic failures in the system. The mechanism of surge current failures has not been understood completely yet, and different hypotheses were discussed in relevant literature. These include a sustained scintillation

  14. Topical Report Tantalum – 2.5% Tungsten Machinability Testing

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

    L. J. Lazarus

    2009-09-02

    Protection Association (NFPA). NFPA 484, Standard for Combustible Metals, Chapter 9 Tantalum and Annex E, supplemental Information on Tantalum require cutting oil be used when machining tantalum because it burns at such a high temperature that it breaks down the water in a water-based metalworking fluid (MWF). The NFPA guide devotes approximately 20 pages to this material. The Kansas City Plant (KCP) uses Fuchs Lubricants Ecocut Base 44 LVC as a MWF. This is a highly chlorinated oil with a high flash point (above 200° F). The chlorine is very helpful in preventing BUE (Built Up Edge) that occurs frequentlymore » with this very gummy material. The Ecocut is really a MWF additive that Fuchs uses to add chlorinated fats to other non-chlorinated MWF.« less

  15. Advanced Wet Tantalum Capacitors: Design, Specifications and Performance

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2016-01-01

    Insertion of new types of commercial, high volumetric efficiency wet tantalum capacitors in space systems requires reassessment of the existing quality assurance approaches that have been developed for capacitors manufactured to MIL-PRF-39006 requirements. The specifics of wet electrolytic capacitors is that leakage currents flowing through electrolyte can cause gas generation resulting in building up of internal gas pressure and rupture of the case. The risk associated with excessive leakage currents and increased pressure is greater for high value advanced wet tantalum capacitors, but it has not been properly evaluated yet. This presentation gives a review of specifics of the design, performance, and potential reliability risks associated with advanced wet tantalum capacitors. Problems related to setting adequate requirements for DPA, leakage currents, hermeticity, stability at low and high temperatures, ripple currents for parts operating in vacuum, and random vibration testing are discussed. Recommendations for screening and qualification to reduce risks of failures have been suggested.

  16. Advanced Wet Tantalum Capacitors: Design, Specifications and Performance

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2017-01-01

    Insertion of new types of commercial, high volumetric efficiency wet tantalum capacitors in space systems requires reassessment of the existing quality assurance approaches that have been developed for capacitors manufactured to MIL-PRF-39006 requirements. The specifics of wet electrolytic capacitors is that leakage currents flowing through electrolyte can cause gas generation resulting in building up of internal gas pressure and rupture of the case. The risk associated with excessive leakage currents and increased pressure is greater for high value advanced wet tantalum capacitors, but it has not been properly evaluated yet. This presentation gives a review of specifics of the design, performance, and potential reliability risks associated with advanced wet tantalum capacitors. Problems related to setting adequate requirements for DPA, leakage currents, hermeticity, stability at low and high temperatures, ripple currents for parts operating in vacuum, and random vibration testing are discussed. Recommendations for screening and qualification to reduce risks of failures have been suggested.

  17. Tribological performance of polycrystalline tantalum-carbide-incorporated diamond films on silicon substrates

    NASA Astrophysics Data System (ADS)

    Ullah, Mahtab; Rana, Anwar Manzoor; Ahmed, E.; Malik, Abdul Sattar; Shah, Z. A.; Ahmad, Naseeb; Mehtab, Ujala; Raza, Rizwan

    2018-05-01

    Polycrystalline tantalum-carbide-incorporated diamond coatings have been made on unpolished side of Si (100) wafer by hot filament chemical vapor deposition process. Morphology of the coatings has been found to vary from (111) triangular-facetted to predominantly (111) square-faceted by increasing the concentration of tantalum carbide. The results have been compared to those of a diamond reference coating with no tantalum content. An increase in roughness has been observed with the increase of tantalum carbide (TaC) due to change in morphology of the diamond films. It is noticed that roughness of the coatings increases as grains become more square-faceted. It is found that diamond coatings involving tantalum carbide are not as resistant as diamond films with no TaC content and the coefficient of friction for such coatings with microcrystalline grains can be manipulated to 0·33 under high vacuum of 10-7 Torr. Such a low friction coefficient value enhances tribological behavior of unpolished Si substrates and can possibly be used in sliding applications.

  18. Anomalous softening of yield strength in tantalum at high pressures

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

    Jing, Qiumin, E-mail: j-qm@163.com; Wu, Qiang; Xu, Ji-an

    2015-02-07

    The pressure dependence of the yield strength of tantalum was investigated experimentally up to 101 GPa at room temperature using a diamond anvil cell. A yield strength softening is observed between 52 and 84 GPa, whereas a normal trend is observed below 52 GPa and above 84 GPa. The onset pressure of the softening is in agreement with previous results obtained by the pressure gradient method and shock wave experiments. This unusual strength softening in tantalum is not related with structural transformation, preferred orientation, or material damage. Our measurements indicate that microscopic deviatoric strain is the major reason for the observed strength softening inmore » tantalum.« less

  19. Investigating the oxidation mechanism of tantalum nanoparticles at high heating rates

    NASA Astrophysics Data System (ADS)

    DeLisio, Jeffery B.; Wang, Xizheng; Wu, Tao; Egan, Garth C.; Jacob, Rohit J.; Zachariah, Michael R.

    2017-12-01

    Reduced diffusion length scales and increased specific surface areas of nanosized metal fuels have recently demonstrated increased reaction rates for these systems, increasing their relevance in a wide variety of applications. The most commonly employed metal fuel, aluminum, tends to oxidize rapidly near its melting point (660 °C) in addition to undergoing a phase change of the nascent oxide shell. To further expand on the understanding of nanosized metal fuel oxidation, tantalum nanoparticles were studied due to their high melting point (3017 °C) in comparison to aluminum. Both traditional slow heating rate and in-situ high heating rate techniques were used to probe the oxidation of tantalum nanoparticles in oxygen containing environments in addition to nanothermite mixtures. When oxidized by gas phase oxygen, the oxide shell of the tantalum nanoparticles rapidly crystallized creating cracks that may attribute to enhanced oxygen diffusion into the particle. In the case of tantalum based nanothermites, oxide shell crystallization was shown to induce reactive sintering with the metal oxide resulting in a narrow range of ignition temperatures independent of the metal oxide used. The oxidation mechanism was modeled using the Deal-Grove model to extract rate parameters, and theoretical burn times for tantalum based nanocomposites were calculated.

  20. High efficiency tantalum-based ceramic composite structures

    NASA Technical Reports Server (NTRS)

    Stewart, David A. (Inventor); Leiser, Daniel B. (Inventor); DiFiore, Robert R. (Inventor); Katvala, Victor W. (Inventor)

    2010-01-01

    Tantalum-based ceramics are suitable for use in thermal protection systems. These composite structures have high efficiency surfaces (low catalytic efficiency and high emittance), thereby reducing heat flux to a spacecraft during planetary re-entry. These ceramics contain tantalum disilicide, molybdenum disilicide and borosilicate glass. The components are milled, along with a processing aid, then applied to a surface of a porous substrate, such as a fibrous silica or carbon substrate. Following application, the coating is then sintered on the substrate. The composite structure is substantially impervious to hot gas penetration and capable of surviving high heat fluxes at temperatures approaching 3000.degree. F. and above.

  1. A niobium oxide-tantalum oxide selector-memristor self-aligned nanostack

    NASA Astrophysics Data System (ADS)

    Diaz Leon, Juan J.; Norris, Kate J.; Yang, J. Joshua; Sevic, John F.; Kobayashi, Nobuhiko P.

    2017-03-01

    The integration of nonlinear current-voltage selectors and bi-stable memristors is a paramount step for reliable operation of crossbar arrays. In this paper, the self-aligned assembly of a single nanometer-scale device that contains both a selector and a memristor is presented. The two components (i.e., selector and memristor) are vertically assembled via a self-aligned fabrication process combined with electroforming. In designing the device, niobium oxide and tantalum oxide are chosen as materials for selector and memristor, respectively. The formation of niobium oxide is visualized by exploiting the self-limiting reaction between niobium and tantalum oxide; crystalline niobium (di)oxide forms at the interface between metallic niobium and tantalum oxide via electrothermal heating, resulting in a niobium oxide selector self-aligned to a tantalum oxide memristor. A steady-state finite element analysis is used to assess the electrothermal heating expected to occur in the device. Current-voltage measurements and structural/chemical analyses conducted for the virgin device, the electroforming process, and the functional selector-memristor device are presented. The demonstration of a self-aligned, monolithically integrated selector-memristor device would pave a practical pathway to various circuits based on memristors attainable at manufacturing scales.

  2. Analysis of Weibull Grading Test for Solid Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2010-01-01

    Weibull grading test is a powerful technique that allows selection and reliability rating of solid tantalum capacitors for military and space applications. However, inaccuracies in the existing method and non-adequate acceleration factors can result in significant, up to three orders of magnitude, errors in the calculated failure rate of capacitors. This paper analyzes deficiencies of the existing technique and recommends more accurate method of calculations. A physical model presenting failures of tantalum capacitors as time-dependent-dielectric-breakdown is used to determine voltage and temperature acceleration factors and select adequate Weibull grading test conditions. This, model is verified by highly accelerated life testing (HALT) at different temperature and voltage conditions for three types of solid chip tantalum capacitors. It is shown that parameters of the model and acceleration factors can be calculated using a general log-linear relationship for the characteristic life with two stress levels.

  3. 49 CFR 17.4 - [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false [Reserved] 17.4 Section 17.4 Transportation Office of the Secretary of Transportation INTERGOVERNMENTAL REVIEW OF DEPARTMENT OF TRANSPORTATION PROGRAMS AND ACTIVITIES § 17.4 [Reserved] ...

  4. The Tri-lab Tantalum Strength Consortium

    NASA Astrophysics Data System (ADS)

    Flicker, Dawn G.; Arsenlis, Thomas A.; Austin, Ryan; Barton, Nathan R.; Benage, John F.; Bronkhorst, Curt A.; Brown, Justin L.; Brown, Staci L.; Buttler, William T.; Shen, Shuh-Rong; Dattelbaum, Dana M.; Fensin, Sayu J.; Gray, George T., III; Lane, J. Matthew D.; Lim, Hojun; Luscher, D. J.; Mattsson, Thomas R.; McNabb, Dennis P.; Remington, Bruce A.; Park, Hye-Sook; Prisbrey, Shon T.; Prime, Michael B.; Scharff, Robert J.; Schraad, Mark W.; Sun, Amy C.

    2017-06-01

    A Tri-lab consortium of experimentalists and theorists at SNL, LLNL, and LANL is joining forces to better understand tantalum strength across an unprecedented range of loading conditions. The team is collecting and comparing tantalum strength data from Hopkinson bar, Taylor cylinder, guns, Z, Omega and the NIF. These experiments, all using Ta from a single lot, span pressures from tenths to hundreds of GPa and strain rates from 103 to 107. New experiments are underway to provide more overlap between the platforms. The experiments are being simulated with a variety of models in order to determine which processes are important under which conditions. The presentation will show results to date. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000.

  5. Observation of oxide particles below the apparent oxygen solubility limit in tantalum

    NASA Technical Reports Server (NTRS)

    Stecura, S.

    1973-01-01

    The apparent solubility of oxygen in polycrystalline tantalum as determined by the X-ray diffraction lattice parameter technique is about 1.63 atomic percent at 820 C. However, oxide particles were identified in samples containing as low as 0.5 atomic percent of oxygen. These oxide particles were present at the grain boundaries and within the grains. The number of oxide particles increased with increasing oxygen concentration in tantalum. The presence of oxide particles suggests that the true solubility of oxygen in the polycrystalline tantalum metal is probably significantly lower than that reported in the literature.

  6. Simultaneous determination of tantalum and hafnium in silicates by neutron activation analysis

    USGS Publications Warehouse

    Greenland, L.P.

    1968-01-01

    A neutron activation procedure suitable for the routine determination of tantalum and hafnium in silicates is described. The irradiated sample is fused with sodium peroxide and leached, and the insoluble hydroxides are dissolved in dilute hydrofluoric acid-hydrochloric acid. After LaF3 and AgCl scavenges, tantalum and hafnium are separated by anion exchange. Tantalum is obtained radiochemically pure; 233Pa and 95Zr contaminants in the hafnium fraction are resolved by ??-ray spectrometry. The chemical yield of the procedure is detemined after counting by re-irradiation. Values for the 8 U.S. Geological Survey standard rocks are reported. ?? 1968.

  7. Synthesis of Coral-Like Tantalum Oxide Films via Anodization in Mixed Organic-Inorganic Electrolytes

    PubMed Central

    Yu, Hongbin; Zhu, Suiyi; Yang, Xia; Wang, Xinhong; Sun, Hongwei; Huo, Mingxin

    2013-01-01

    We report a simple method to fabricate nano-porous tantalum oxide films via anodization with Ta foils as the anode at room temperature. A mixture of ethylene glycol, phosphoric acid, NH4F and H2O was used as the electrolyte where the nano-porous tantalum oxide could be synthesized by anodizing a tantalum foil for 1 h at 20 V in a two–electrode configuration. The as-prepared porous film exhibited a continuous, uniform and coral-like morphology. The diameters of pores ranged from 30 nm to 50 nm. The pores interlaced each other and the depth was about 150 nm. After calcination, the as-synthesized amorphous tantalum oxide could be crystallized to the orthorhombic crystal system. As observed in photocatalytic experiments, the coral-like tantalum oxide exhibited a higher photocatalytic activity for the degradation of phenol than that with a compact surface morphology, and the elimination rate of phenol increased by 66.7%. PMID:23799106

  8. Biological Response of Human Bone Marrow-Derived Mesenchymal Stem Cells to Commercial Tantalum Coatings with Microscale and Nanoscale Surface Topographies

    NASA Astrophysics Data System (ADS)

    Skoog, Shelby A.; Kumar, Girish; Goering, Peter L.; Williams, Brian; Stiglich, Jack; Narayan, Roger J.

    2016-06-01

    Tantalum is a promising orthopaedic implant coating material due to its robust mechanical properties, corrosion resistance, and excellent biocompatibility. Previous studies have demonstrated improved biocompatibility and tissue integration of surface-treated tantalum coatings compared to untreated tantalum. Surface modification of tantalum coatings with biologically inspired microscale and nanoscale features may be used to evoke optimal tissue responses. The goal of this study was to evaluate commercial tantalum coatings with nanoscale, sub-microscale, and microscale surface topographies for orthopaedic and dental applications using human bone marrow-derived mesenchymal stem cells (hBMSCs). Tantalum coatings with different microscale and nanoscale surface topographies were fabricated using a diffusion process or chemical vapor deposition. Biological evaluation of the tantalum coatings using hBMSCs showed that tantalum coatings promote cellular adhesion and growth. Furthermore, hBMSC adhesion to the tantalum coatings was dependent on surface feature characteristics, with enhanced cell adhesion on sub-micrometer- and micrometer-sized surface topographies compared to hybrid nano-/microstructures. Nanostructured and microstructured tantalum coatings should be further evaluated to optimize the surface coating features to promote osteogenesis and enhance osseointegration of tantalum-based orthopaedic implants.

  9. Effect of Post-HALT Annealing on Leakage Currents in Solid Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2010-01-01

    Degradation of leakage currents is often observed during life testing of tantalum capacitors and is sometimes attributed to the field-induced crystallization in amorphous anodic tantalum pentoxide dielectrics. However, degradation of leakage currents and the possibility of annealing of degraded capacitors have not been investigated yet. In this work the effect of annealing after highly accelerated life testing (HALT) on leakage currents in various types of solid tantalum capacitors was analyzed. Variations of leakage currents with time during annealing at temperatures from 125 oC to 180 oC, thermally stimulated depolarization (TSD) currents, and I-V characteristics were measured to understand the conduction mechanism and the reason for current degradation. Annealing resulted in a gradual decrease of leakage currents and restored their initial values. Repeat HALT after annealing resulted in reproducible degradation of leakage currents. The observed results are explained based on ionic charge instability (drift/diffusion of oxygen vacancies) in the tantalum pentoxide dielectrics using a modified Schottky conduction mechanism.

  10. The Evaluation of Hydroxyapatite (HA) Coated and Uncoated Porous Tantalum for Biomedical Material Applications

    NASA Astrophysics Data System (ADS)

    Safuan, Nadia; Sukmana, Irza; Kadir, Mohammed Rafiq Abdul; Noviana, Deni

    2014-04-01

    Porous tantalum has been used as an orthopedic implant for bone defects as it has a good corrosion resistance and fatigue behaviour properties. However, there are some reports on the rejection of porous Ta after the implantation. Those clinical cases refer to the less bioactivity of metallic-based materials. This study aims to evaluate hydroxyapatite coated and uncoated porous Tantalum in order to improve the biocompatibility of porous tantalum implant and osseointegration. Porous tantalum was used as metallic-base substrate and hydroxyapatite coating has been done using plasma-spraying technique. Scanning Electron Microscopy (SEM) and Field Emission Scanning Electron Microscopy (FESEM) techniques were utilizes to investigate the coating characteristics while Confocal Raman Microscopy to investigate the interface and image. The effect of coating to the corrosion behaviour was assessed by employing potentiodynamic polarization tests in simulated body fluid at 37±1 °C. Based on SEM and FESEM results, the morphologies as well the weight element consists in the uncoated and hydroxyapatite coated porous tantalum were revealed. The results indicated that the decrease in corrosion current density for HA coated porous Ta compared to the uncoated porous Ta. This study concluded that by coating porous tantalum with HA supports to decrease the corrosion rate of pure porous.

  11. NIOBIUM-TANTALUM SEPARATION

    DOEpatents

    Wilhelm, H.A.; Foos, R.A.

    1959-01-27

    The usual method for the separation of tantalum and niobium consists of a selective solvent extraction from an aqueous hydrofluoric acid solution of the metals. A difficulty encountered in this process is the fact that the corrosion problems associated with hydrofluoric acid are serious. It has been found that the corrosion caused by the hydrofluoric acid may be substantially reduced by adding to the acidic solution an amine, such as phenyl diethanolamine or aniline, and adjusting pH value to between 4 and 6.

  12. 46 CFR 174.325 - Equalization.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Equalization. 174.325 Section 174.325 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments Calculations § 174.325 Equalization...

  13. 46 CFR 174.325 - Equalization.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Equalization. 174.325 Section 174.325 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments Calculations § 174.325 Equalization...

  14. 37 CFR 1.174 - [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2014-07-01 2014-07-01 false [Reserved] 1.174 Section 1.174 Patents, Trademarks, and Copyrights UNITED STATES PATENT AND TRADEMARK OFFICE, DEPARTMENT OF COMMERCE GENERAL RULES OF PRACTICE IN PATENT CASES National Processing Provisions Reissues § 1.174...

  15. Tantalum modified ferritic iron base alloys

    NASA Technical Reports Server (NTRS)

    Oldrieve, R. E.; Blankenship, C. P. (Inventor)

    1977-01-01

    Strong ferritic alloys of the Fe-CR-Al type containing 0.4% to 2% tantalum were developed. These alloys have improved fabricability without sacrificing high temperature strength and oxidation resistance in the 800 C (1475 F) to 1040 C (1900 F) range.

  16. 19 CFR 174.32 - Publication.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 2 2012-04-01 2012-04-01 false Publication. 174.32 Section 174.32 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY (CONTINUED) PROTESTS Review and Disposition of Protests § 174.32 Publication. Within 90 calendar days after...

  17. 19 CFR 174.32 - Publication.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 2 2014-04-01 2014-04-01 false Publication. 174.32 Section 174.32 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY (CONTINUED) PROTESTS Review and Disposition of Protests § 174.32 Publication. Within 90 calendar days after...

  18. 19 CFR 174.32 - Publication.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 2 2013-04-01 2013-04-01 false Publication. 174.32 Section 174.32 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY (CONTINUED) PROTESTS Review and Disposition of Protests § 174.32 Publication. Within 90 calendar days after...

  19. 19 CFR 174.32 - Publication.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 2 2011-04-01 2011-04-01 false Publication. 174.32 Section 174.32 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY (CONTINUED) PROTESTS Review and Disposition of Protests § 174.32 Publication. Within 90 calendar days after...

  20. 19 CFR 174.32 - Publication.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Publication. 174.32 Section 174.32 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY (CONTINUED) PROTESTS Review and Disposition of Protests § 174.32 Publication. Within 120 days after issuing a...

  1. Effect of Compressive Stresses on Leakage Currents in Microchip Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2012-01-01

    Microchip tantalum capacitors are manufactured using new technologies that allow for production of small size capacitors (down to EIA case size 0402) with volumetric efficiency much greater than for regular chip capacitors. Due to a small size of the parts and leadless design they might be more sensitive to mechanical stresses that develop after soldering onto printed wiring boards (PWB) compared to standard chip capacitors. In this work, the effect of compressive stresses on leakage currents in capacitors has been investigated in the range of stresses up to 200 MPa. Significant, up to three orders of magnitude, variations of currents were observed after the stress exceeds a certain critical level that varied from 10 MPa to 180 MPa for capacitors used in this study. A stress-induced generation of electron traps in tantalum pentoxide dielectric is suggested to explain reversible variations of leakage currents in tantalum capacitors. Thermo-mechanical characteristics of microchip capacitors have been studied to estimate the level of stresses caused by assembly onto PWB and assess the risk of stress-related degradation and failures. Keywords: tantalum capacitors, leakage current, soldering, reliability, mechanical stress.

  2. The preparation of tantalum powder using a MR-EMR combination process

    NASA Astrophysics Data System (ADS)

    Yoon, Jae Sik; Kim, Byung Il

    2007-04-01

    In the conventional metallothermic reduction (MR) process used to obtain tantalum powder in batch-type operation, it is difficult to control the morphology and location of the tantalum deposits. In contrast, an electronically mediated reaction (EMR) process is capable of overcoming this difficulty. It has the advantage of being a continuous process, but has the disadvantage of a poor reduction yield. A process known as the MR-EMR combination process is able to overcome the shortcomings of the MR and EMR processes. In this study, an MR-EMR combination process is applied to the production of tantalum powder via sodium reduction of K2TaF7. In the MR-EMR combination process, the total charge passed through an external circuit and the average particle size (FSSS) increase as the reduction temperature increases. In addition, the proportion of fine particles (-325 mesh) decreases as the reduction temperature increasess. The tantalum yield improved from 65 to 74% as the reduction temperature increased. Taking into account the charge, impurities, morphology, particle size and yield, a reduction temperature of 1123 K was found to be optimum for the MR-EMR combination process.

  3. 7 CFR 993.174 - Records.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Records. 993.174 Section 993.174 Agriculture... Administrative Rules and Regulations Reports and Books and Other Records § 993.174 Records. Each handler shall maintain such records as are necessary to furnish the reports required to be submitted to the Committee by...

  4. 7 CFR 993.174 - Records.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Records. 993.174 Section 993.174 Agriculture... Administrative Rules and Regulations Reports and Books and Other Records § 993.174 Records. Each handler shall maintain such records as are necessary to furnish the reports required to be submitted to the Committee by...

  5. 7 CFR 993.174 - Records.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Records. 993.174 Section 993.174 Agriculture... Administrative Rules and Regulations Reports and Books and Other Records § 993.174 Records. Each handler shall maintain such records as are necessary to furnish the reports required to be submitted to the Committee by...

  6. Reliability of High-Voltage Tantalum Capacitors. Parts 3 and 4)

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2010-01-01

    Weibull grading test is a powerful technique that allows selection and reliability rating of solid tantalum capacitors for military and space applications. However, inaccuracies in the existing method and non-adequate acceleration factors can result in significant, up to three orders of magnitude, errors in the calculated failure rate of capacitors. This paper analyzes deficiencies of the existing technique and recommends more accurate method of calculations. A physical model presenting failures of tantalum capacitors as time-dependent-dielectric-breakdown is used to determine voltage and temperature acceleration factors and select adequate Weibull grading test conditions. This model is verified by highly accelerated life testing (HALT) at different temperature and voltage conditions for three types of solid chip tantalum capacitors. It is shown that parameters of the model and acceleration factors can be calculated using a general log-linear relationship for the characteristic life with two stress levels.

  7. 12 CFR 174.4 - Control.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 1 2013-01-01 2013-01-01 false Control. 174.4 Section 174.4 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY ACQUISITION OF CONTROL OF FEDERAL SAVINGS ASSOCIATIONS § 174.4 Control. (a) Conclusive control. (1) An acquiror shall be deemed to have acquired control of a...

  8. 12 CFR 174.4 - Control.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 1 2012-01-01 2012-01-01 false Control. 174.4 Section 174.4 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY ACQUISITION OF CONTROL OF FEDERAL SAVINGS ASSOCIATIONS § 174.4 Control. (a) Conclusive control. (1) An acquiror shall be deemed to have acquired control of a...

  9. 12 CFR 174.4 - Control.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 1 2014-01-01 2014-01-01 false Control. 174.4 Section 174.4 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY ACQUISITION OF CONTROL OF FEDERAL SAVINGS ASSOCIATIONS § 174.4 Control. (a) Conclusive control. (1) An acquiror shall be deemed to have acquired control of a...

  10. Surface nanotexturing of tantalum by laser ablation in water

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

    Barmina, E V; Simakin, Aleksandr V; Shafeev, Georgii A

    2009-01-31

    Surface nanotexturing of tantalum by ablation with short laser pulses in water has been studied experimentally using three ablation sources: a neodymium laser with a pulse duration of 350 ps, an excimer laser (248 nm) with a pulse duration of 5 ps and a Ti:sapphire laser with a pulse duration of 180 fs. The morphology of the nanotextured surfaces has been examined using a nanoprofilometer and field emission scanning electron microscope. The results demonstrate that the average size of the hillocks produced on the target surface depends on the laser energy density and is {approx}200 nm at an energy densitymore » approaching the laser-melting threshold of tantalum and a pulse duration of 350 ps. Their surface density reaches 10{sup 6} cm{sup -2}. At a pulse duration of 5 ps, the average hillock size is 60-70 nm. Nanotexturing is accompanied by changes in the absorption spectrum of the tantalum surface in the UV and visible spectral regions. The possible mechanisms of surface nanotexturing and potential applications of this effect are discussed. (nanostructures)« less

  11. Semimicrodetermination of combined tantalum and niobium with selenous acid

    USGS Publications Warehouse

    Grimaldi, F.S.; Schnepfe, M.

    1959-01-01

    Tantalum and niobium are separated and determined gravimetrically by precipitation with selenous acid from highly acidic solutions in the absence of complexing agents. Hydrogen peroxide is used in the preparation of the solution and later catalytically destroyed during digestion of the precipitate. From 0.2 to 30 mg., separately or in mixtures, of niobium or tantalum pentoxide can be separated from mixtures containing 100 mg. each of the oxides of scandium, yttrium, cerium, vanadium, molybdenum, iron, aluminum, tin, lead, and bismuth with a single precipitation; and from 30 mg. of titanium dioxide, and 50 mg. each of the oxides of antimony and thorium, when present separately, with three precipitations. At least 50 mg. of uranium(VI) oxide can be separated with a single precipitation when present alone; otherwise, three precipitations may be needed. Zirconium does not interfere when the tantalum and niobium contents of the sample are small, but in general, zirconium as well as tungsten interfere. The method is applied to the determination of the earth acids in tantaloniobate ores.

  12. Tantalum protective coatings for fusion reactor applications

    NASA Astrophysics Data System (ADS)

    Brossa, Francesco; Piatti, Giovanni; Bardy, Michel

    Tantalum has a very low sputtering yield, high melting point, low vapour pressure and good mechanical properties at low and high temperatures, so it is a very interesting candidate for the first wall and blanket structural components. Tantalum coatings overcome the problems of fabrication and joining bulk Ta, thus reducing also dead weight and cost. Ta coatings were produced by chemical vapour deposition and plasma spraying on four conventional structural materials: Al, Cu, AISI 316 L and Inconel 600. The conditions which improve adherence have been studied. The composition of the films was determined by chemical means and by X-ray analysis. Metallographie examination was employed to define the morphological structure of the deposits. The adherence of the coatings was determined by subjecting the samples to bend tests and to thermal shocks.

  13. Effects of severe stressing on tantalum capacitors

    NASA Technical Reports Server (NTRS)

    Shakar, J. F.; Fairfield, E. H.

    1981-01-01

    The ultimate capabilities of an all tantalum capacitor were determined and evaluated. The evaluation included: 175 C life; 100 cycle thermal shock; 70 g random vibration; 3000 g shock; and 90 C ase ripple current.

  14. Micro/Nano Structural Tantalum Coating for Enhanced Osteogenic Differentiation of Human Bone Marrow Stem Cells

    PubMed Central

    Ding, Ding; Xie, Youtao; Li, Kai; Huang, Liping; Zheng, Xuebin

    2018-01-01

    Recently, tantalum has been attracting much attention for its anticorrosion resistance and biocompatibility, and it has been widely used in surface modification for implant applications. To improve its osteogenic differentiation of human bone marrow stem cells (hBMSCs), a micro/nano structure has been fabricated on the tantalum coating surface through the combination of anodic oxidation and plasma spraying method. The morphology, composition, and microstructure of the modified coating were comprehensively studied by employing scanning electron microscopy (SEM), X-ray diffraction (XRD) as well as transmission electron microscopy (TEM). The effects of hierarchical structures as well as micro-porous structure of tantalum coating on the behavior for human bone marrow stem cells (hBMSCs) were evaluated and compared at both cellular and molecular levels in vitro. The experimental results show that a hierarchical micro/nano structure with Ta2O5 nanotubes spread onto a micro-scale tantalum coating has been fabricated successfully, which is confirmed to promote cell adhesion and spreading. Besides, the hierarchical micro/nano tantalum coating can provide 1.5~2.1 times improvement in gene expression, compared with the micro-porous tantalum coating. It demonstrates that it can effectively enhance the proliferation and differentiation of hBMSCs in vitro. PMID:29614022

  15. Micro/Nano Structural Tantalum Coating for Enhanced Osteogenic Differentiation of Human Bone Marrow Stem Cells.

    PubMed

    Ding, Ding; Xie, Youtao; Li, Kai; Huang, Liping; Zheng, Xuebin

    2018-04-03

    Recently, tantalum has been attracting much attention for its anticorrosion resistance and biocompatibility, and it has been widely used in surface modification for implant applications. To improve its osteogenic differentiation of human bone marrow stem cells (hBMSCs), a micro/nano structure has been fabricated on the tantalum coating surface through the combination of anodic oxidation and plasma spraying method. The morphology, composition, and microstructure of the modified coating were comprehensively studied by employing scanning electron microscopy (SEM), X-ray diffraction (XRD) as well as transmission electron microscopy (TEM). The effects of hierarchical structures as well as micro-porous structure of tantalum coating on the behavior for human bone marrow stem cells (hBMSCs) were evaluated and compared at both cellular and molecular levels in vitro. The experimental results show that a hierarchical micro/nano structure with Ta₂O₅ nanotubes spread onto a micro-scale tantalum coating has been fabricated successfully, which is confirmed to promote cell adhesion and spreading. Besides, the hierarchical micro/nano tantalum coating can provide 1.5~2.1 times improvement in gene expression, compared with the micro-porous tantalum coating. It demonstrates that it can effectively enhance the proliferation and differentiation of hBMSCs in vitro.

  16. Random Vibration Testing of Advanced Wet Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2015-01-01

    Advanced wet tantalum capacitors allow for improved performance of power supply systems along with substantial reduction of size and weight of the systems that is especially beneficial for space electronics. Due to launch-related stresses, acceptance testing of all space systems includes random vibration test (RVT). However, many types of advanced wet tantalum capacitors cannot pass consistently RVT at conditions specified in MIL-PRF-39006, which impedes their use in space projects. This requires a closer look at the existing requirements, modes and mechanisms of failures, specifics of test conditions, and acceptance criteria. In this work, different lots of advanced wet tantalum capacitors from four manufacturers have been tested at step stress random vibration conditions while their currents were monitored before, during, and after the testing. It has been shown that the robustness of the parts and their reliability are mostly due to effective self-healing processes and limited current spiking or minor scintillations caused by RVT do not increase the risk of failures during operation. A simple model for scintillations events has been used to simulate current spiking during RVT and optimize test conditions. The significance of scintillations and possible effects of gas generation have been discussed and test acceptance criteria for limited current spiking have been suggested.

  17. Effects of substrate temperature on properties of pulsed dc reactively sputtered tantalum oxide films

    NASA Astrophysics Data System (ADS)

    Jain, Pushkar; Juneja, Jasbir S.; Bhagwat, Vinay; Rymaszewski, Eugene J.; Lu, Toh-Ming; Cale, Timothy S.

    2005-05-01

    The effects of substrate heating on the stoichiometry and the electrical properties of pulsed dc reactively sputtered tantalum oxide films over a range of film thickness (0.14 to 5.4 μm) are discussed. The film stoichiometry, and hence the electrical properties, of tantalum oxide films; e.g., breakdown field, leakage current density, dielectric constant, and dielectric loss are compared for two different cases: (a) when no intentional substrate/film cooling is provided, and (b) when the substrate is water cooled during deposition. All other operating conditions are the same, and the film thickness is directly related to deposition time. The tantalum oxide films deposited on the water-cooled substrates are stoichiometric, and exhibit excellent electrical properties over the entire range of film thickness. ``Noncooled'' tantalum oxide films are stoichiometric up to ~1 μm film thickness, beyond that the deposited oxide is increasingly nonstoichiometric. The presence of partially oxidized Ta in thicker (>~1 μm) noncooled tantalum oxide films causes a lower breakdown field, higher leakage current density, higher apparent dielectric constant, and dielectric loss. The growth of nonstoichiometric tantalum oxide in thicker noncooled films is attributed to decreased surface oxygen concentration due to oxygen recombination and desorption at higher film temperatures (>~100 °C). The quantitative results presented reflect experience with a specific piece of equipment; however, the procedures presented can be used to characterize deposition processes in which film stoichiometry can change.

  18. Guidelines for the selection and application of tantalum electrolytic capacitors in highly reliable equipment

    NASA Technical Reports Server (NTRS)

    Holladay, A. M.

    1978-01-01

    Guidelines are given for the selection and application of three types of tantalum electrolytic capacitors in current use in the design of electrical and electronic circuits for space flight missions. In addition, the guidelines supplement requirements of existing military specifications used in the procurement of capacitors. A need exists for these guidelines to assist designers in preventing some of the recurring, serious problems experienced with tantalum electrolytic capacitors in the recent past. The three types of capacitors covered by these guidelines are; solid, wet foil, and tantalum cased wet slug.

  19. Electronic transitions of tantalum monofluoride

    NASA Astrophysics Data System (ADS)

    Ng, K. F.; Zou, Wenli; Liu, Wenjian; Cheung, A. S.-C.

    2017-03-01

    The electronic transition spectrum of the tantalum monofluoride (TaF) molecule in the spectral region between 448 and 560 nm has been studied using the technique of laser-ablation/reaction free jet expansion and laser induced fluorescence spectroscopy. The TaF molecule was produced by reacting laser-ablated tantalum atoms with sulfur hexafluoride gas seeded in argon. Twenty-two vibrational bands with resolved rotational structure have been recorded and analyzed, which were organized into seven electronic transitions. The X3Σ-(0+) state has been identified to be the ground state and the determined equilibrium bond length, re, and vibrational frequency, ωe, are 1.8184 Å and 700.1 cm-1, respectively. The low-lying Λ-S states and Ω sub-states of TaF were also theoretically studied at the MRCISD+Q level of theory with spin-orbit coupling. The Ω = 0+ and 2 sub-states from the -3Σ and 3Φ state have been found to be the ground and the first excited states, respectively, which agrees well with our experimental determinations. This work represents the first experimental investigation of the molecular structure of the TaF molecule.

  20. Performance and Reliability of Solid Tantalum Capacitors at Cryogenic Conditions

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2006-01-01

    Performance of different types of solid tantalum capacitors was evaluated at room and low temperatures, down to 15 K. The effect of temperature on frequency dependencies of capacitance, effective series resistances (ESR), leakage currents, and breakdown voltages has been investigated and analyzed. To assess thermo-mechanical robustness of the parts, several groups of loose capacitors and those soldered on FR4 boards were subjected to multiple (up to 500) temperature cycles between room temperature and 77 K. Experiments and mathematical modeling have shown that degradation in tantalum capacitors at low temperatures is mostly due to increasing resistance of the manganese cathode layer, resulting in substantial decrease of the roll-off frequency. Absorption currents follow a power law, I approximately t(sup -m), with the exponent m varying from 0.8 to 1.1. These currents do not change significantly at cryogenic conditions and the value of the exponent remains the same down to 15 K. Variations of leakage currents with voltage can be described by Pool-Frenkel and Schottky mechanisms of conductivity, with the Schottky mechanism prevailing at cryogenic conditions. Breakdown voltages of tantalum capacitors increase and the probability of scintillations decreases at cryogenic temperatures. However, breakdown voltages measured during surge current testing decrease at liquid nitrogen (LN) compared to room-temperature conditions. Results of temperature cycling suggest that tantalum capacitors are capable of withstanding multiple exposures to cryogenic conditions, but the probability of failures varies for different part types.

  1. Tantalum-based thin film coatings for wear resistant arthroprostheses.

    PubMed

    Balagna, C; Faga, M G; Spriano, S

    2011-10-01

    Cobalt-chromium-molybdenum alloys with high carbon content (HC-CoCrMo) are widely used as materials for arthroprosthesis, in particular in metal-on-metal (MoM) hip joints. In spite of their good wear and corrosion resistance, production of metallic wear particles and metal ion release will occur on a large time-scale. An enhancement of the metal ion level in the patient's blood and urine is often reported in clinical data. Hypersensitivity, inflammatory response and cell necrosis can occur as consequence. So implants on young patients and women on childbearing age are not so widespread. The aim of this research is the realization of a thin film coating in order to improve the biocompatibility of Co-based alloys and to reduce debris production, ion release and citotoxicity. The innovative process consists of a thermal treatment in molten salts, in order to obtain a tantalum enriched thin film coating. Tantalum is chosen because it is considered a biocompatible metal with high corrosion resistance and low ion release. Three HC-CoCrMo alloys, produced by different manufacturing processes, are tested as substrates. The coating is a thin film of TaC or it can be composed by a multilayer of two tantalum carbides and metallic tantalum, depending on the temperature of the treatment and on the carbon content of the substrate. The thin films as well the substrates are characterized from the structural, chemical and morphological point of view. Moreover mechanical behaviour of treated and untreated materials is analyzed by means of nanohardness, scratch and ball-on-disc wear tests. The coating increases the mechanical and tribological properties of HC-CoCrMo.

  2. A preliminary deposit model for lithium-cesium-tantalum (LCT) pegmatites

    USGS Publications Warehouse

    Bradley, Dwight; McCauley, Andrew

    2013-01-01

    This report is part of an effort by the U.S. Geological Survey to update existing mineral deposit models and to develop new ones. We emphasize practical aspects of pegmatite geology that might directly or indirectly help in exploration for lithium-cesium-tantalum (LCT) pegmatites, or for assessing regions for pegmatite-related mineral resource potential. These deposits are an important link in the world’s supply chain of rare and strategic elements, accounting for about one-third of world lithium production, most of the tantalum, and all of the cesium.

  3. 46 CFR 174.300 - Specific applicability.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Specific applicability. 174.300 Section 174.300 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments § 174.300 Specific...

  4. 49 CFR 174.57 - Cleaning cars.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Cleaning cars. 174.57 Section 174.57... and Loading Requirements § 174.57 Cleaning cars. All hazardous material which has leaked from a package in any rail car or on other railroad property must be carefully removed. ...

  5. 49 CFR 174.57 - Cleaning cars.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Cleaning cars. 174.57 Section 174.57... and Loading Requirements § 174.57 Cleaning cars. All hazardous material which has leaked from a package in any rail car or on other railroad property must be carefully removed. ...

  6. 49 CFR 174.57 - Cleaning cars.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Cleaning cars. 174.57 Section 174.57... and Loading Requirements § 174.57 Cleaning cars. All hazardous material which has leaked from a package in any rail car or on other railroad property must be carefully removed. ...

  7. 49 CFR 174.57 - Cleaning cars.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Cleaning cars. 174.57 Section 174.57... and Loading Requirements § 174.57 Cleaning cars. All hazardous material which has leaked from a package in any rail car or on other railroad property must be carefully removed. ...

  8. 49 CFR 174.57 - Cleaning cars.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Cleaning cars. 174.57 Section 174.57... and Loading Requirements § 174.57 Cleaning cars. All hazardous material which has leaked from a package in any rail car or on other railroad property must be carefully removed. ...

  9. 13 CFR 120.174 - Earthquake hazards.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Earthquake hazards. 120.174 Section 120.174 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION BUSINESS LOANS Policies Applying to All Business Loans Requirements Imposed Under Other Laws and Orders § 120.174 Earthquake...

  10. Deformation of Cases in High Capacitance Value Wet Tantalum Capacitors under Environmental Stresses

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2016-01-01

    Internal gas pressure in hermetic wet tantalum capacitors is created by air, electrolyte vapor, and gas generated by electrochemical reactions at the electrodes. This pressure increases substantially with temperature and time of operation due to excessive leakage currents. Deformation of the case occurs when the internal pressure exceeds pressure of the environments and can raise significantly when a part operates in space. Contrary to the cylinder case wet tantalum capacitors that have external sealing by welding and internal sealing provided by the Teflon bushing and crimping of the case, no reliable internal sealing exists in the button case capacitors. Single seal design capacitors are used for high capacitance value wet tantalum capacitors manufactured per DLA L&M drawings #04003, 04005, and 10011, and require additional analysis to assure their reliable application in space systems. In this work, leakage currents and case deformation of button case capacitors were measured during different environmental test conditions. Recommendations for derating, screening and qualification testing are given. This work is a continuation of a series of NEPP reports related to quality and reliability of wet tantalum capacitors.

  11. 46 CFR 174.320 - Damage survival.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Damage survival. 174.320 Section 174.320 Shipping COAST... SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments Calculations § 174.320 Damage survival. A hopper dredge survives assumed damage if it meets the following conditions: (a) The maximum...

  12. 46 CFR 174.320 - Damage survival.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Damage survival. 174.320 Section 174.320 Shipping COAST... SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments Calculations § 174.320 Damage survival. A hopper dredge survives assumed damage if it meets the following conditions: (a) The maximum...

  13. 46 CFR 174.320 - Damage survival.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Damage survival. 174.320 Section 174.320 Shipping COAST... SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments Calculations § 174.320 Damage survival. A hopper dredge survives assumed damage if it meets the following conditions: (a) The maximum...

  14. Superconducting characteristics in purified tantalum-foils

    NASA Astrophysics Data System (ADS)

    Hu, Qinghua; Wang, Zhihe

    2018-07-01

    We have conducted extensive investigations on the electrical transport and magnetization on a purified tantalum foil with extremely sharp resistive transition (transition width ΔTc < 0.02 K) at 0 T and residual resistivity ratio ρ290K/ρ5K= 16.75. Many effects, such as anisotropic field-induced resistive broadening and second peak of the magnetization-hysteresis loop, are observed in the sample. The maximum upper critical field determined by criteria of R/Rn = 0.9 is about 1.08 T rather weak compared to that in cuprate and/or iron-based superconductors. Although the value of upper critical field Hc2(0) and the field dependence of effective pinning energy U show that the flux pinning potential is weaker, the critical current density Jc(2 K, 0 T) = 1.145 × 105 A/cm2 and the effect of second peak indicate that there should be higher collective vortex pinning potential in the tantalum foil. The carriers are dominated by holes with the density n = 6.6 × 1022/cm3.

  15. Catalytic Hydroamination of Alkynes and Norbornene with Neutral and Cationic Tantalum Imido Complexes

    PubMed Central

    Anderson, Laura L.; Arnold, John; Bergman, Robert G.

    2005-01-01

    Several tantalum imido complexes have been synthesized and shown to efficiently catalyze the hydroamination of internal and terminal alkynes. An unusual hydroamination/hydroarylation reaction of norbornene catalyzed by a highly electrophilic cationic tantalum imido complex is also reported. Factors affecting catalyst activity and selectivity are discussed along with mechanistic insights gained from stoichiometric reactions. PMID:15255680

  16. Characterization of Tantalum Polymer Capacitors

    NASA Technical Reports Server (NTRS)

    Spence, Penelope

    2012-01-01

    Overview Reviewed data Caution must be taken when accelerating test conditions Data not useful to establish an acceleration model Introduction of new failure mechanism skewing results Evidence of Anti-Wear-Out De-doping of polymer Decreased capacitance Increased ESR Not dielectric breakdown Needs further investigation Further investigation into tantalum polymer capacitor technology Promising acceleration model for Manufacturer A Possibility for use in high-reliability space applications with suitable voltage derating.

  17. Physically-based strength model of tantalum incorporating effects of temperature, strain rate and pressure

    DOE PAGES

    Lim, Hojun; Battaile, Corbett C.; Brown, Justin L.; ...

    2016-06-14

    In this work, we develop a tantalum strength model that incorporates e ects of temperature, strain rate and pressure. Dislocation kink-pair theory is used to incorporate temperature and strain rate e ects while the pressure dependent yield is obtained through the pressure dependent shear modulus. Material constants used in the model are parameterized from tantalum single crystal tests and polycrystalline ramp compression experiments. It is shown that the proposed strength model agrees well with the temperature and strain rate dependent yield obtained from polycrystalline tantalum experiments. Furthermore, the model accurately reproduces the pressure dependent yield stresses up to 250 GPa.more » The proposed strength model is then used to conduct simulations of a Taylor cylinder impact test and validated with experiments. This approach provides a physically-based multi-scale strength model that is able to predict the plastic deformation of polycrystalline tantalum through a wide range of temperature, strain and pressure regimes.« less

  18. Vacuum pyrolysis characteristics and parameter optimization of recycling organic materials from waste tantalum capacitors.

    PubMed

    Chen, Zhenyang; Niu, Bo; Zhang, Lingen; Xu, Zhenming

    2018-01-15

    Recycling rare metal tantalum from waste tantalum capacitors (WTCs) is significant to alleviate the shortage of tantalum resource. However, environmental problems will be caused if the organic materials from WTCs are improperly disposed. This study presented a promising vacuum pyrolysis technology to recycle the organic materials from WTCs. The organics removal rate could reach 94.32wt% according to TG results. The optimal parameters were determined as 425°C, 50Pa and 30min on the basis of response surface methodology (RSM). The oil yield and residual rate was 18.09wt% and 74.94wt%, respectively. All pyrolysis products can be recycled through a reasonable route. Besides, to deeply understand the pyrolysis process, the pyrolysis mechanism was also proposed based on the product and free radical theory. This paper provides an efficient process for recycling the organic material from WTCs, which can facilitate the following tantalum recovery. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. 49 CFR 174.615 - Cleaning cars.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Cleaning cars. 174.615 Section 174.615... Requirements for Division 6.1 (Poisonous) Materials § 174.615 Cleaning cars. (a) [Reserved] (b) After Division 6.1 (poisonous) materials are unloaded from a rail car, that car must be thoroughly cleaned unless...

  20. 49 CFR 174.615 - Cleaning cars.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Cleaning cars. 174.615 Section 174.615... Requirements for Division 6.1 (Poisonous) Materials § 174.615 Cleaning cars. (a) [Reserved] (b) After Division 6.1 (poisonous) materials are unloaded from a rail car, that car must be thoroughly cleaned unless...

  1. 49 CFR 174.615 - Cleaning cars.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Cleaning cars. 174.615 Section 174.615... Requirements for Division 6.1 (Poisonous) Materials § 174.615 Cleaning cars. (a) [Reserved] (b) After Division 6.1 (poisonous) materials are unloaded from a rail car, that car must be thoroughly cleaned unless...

  2. 49 CFR 174.615 - Cleaning cars.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Cleaning cars. 174.615 Section 174.615... Requirements for Division 6.1 (Poisonous) Materials § 174.615 Cleaning cars. (a) [Reserved] (b) After Division 6.1 (poisonous) materials are unloaded from a rail car, that car must be thoroughly cleaned unless...

  3. 49 CFR 174.615 - Cleaning cars.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Cleaning cars. 174.615 Section 174.615... Requirements for Division 6.1 (Poisonous) Materials § 174.615 Cleaning cars. (a) [Reserved] (b) After Division 6.1 (poisonous) materials are unloaded from a rail car, that car must be thoroughly cleaned unless...

  4. 49 CFR 174.24 - Shipping papers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Shipping papers. 174.24 Section 174.24... Requirements § 174.24 Shipping papers. (a) A person may not accept a hazardous material for transportation or transport a hazardous material by rail unless that person receives a shipping paper prepared in accordance...

  5. 49 CFR 174.24 - Shipping papers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Shipping papers. 174.24 Section 174.24... Requirements § 174.24 Shipping papers. (a) A person may not accept a hazardous material for transportation or transport a hazardous material by rail unless that person receives a shipping paper prepared in accordance...

  6. Corrosion resistance of porous binary tantalum and titanium carbides of various composition

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

    Artyunina, N.P.; Komratov, G.N.; Bolonova, E.A.

    1993-12-20

    Resistance of porous binary tantalum and titanium carbides in solutions of mineral acids and their mixtures, of several organic acids, and of ammonium and potassium hydroxide was studied. It has been shown that as the content of tantalum in a material increases its resistance in solutions of oxidizing acids is improved, but it is reduced in solutions of sulfuric and hydrofluoric acids and also in solutions of potassium hydroxide.

  7. 46 CFR 174.090 - Permeability of spaces.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Permeability of spaces. 174.090 Section 174.090 Shipping... Permeability of spaces. When doing the calculations required in § 174.065— (a) The permeability of a floodable space, other than a machinery space, must be as listed in Table 174.090; and (b) Calculations in which a...

  8. 46 CFR 174.090 - Permeability of spaces.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Permeability of spaces. 174.090 Section 174.090 Shipping... Permeability of spaces. When doing the calculations required in § 174.065— (a) The permeability of a floodable space, other than a machinery space, must be as listed in Table 174.090; and (b) Calculations in which a...

  9. 46 CFR 174.090 - Permeability of spaces.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Permeability of spaces. 174.090 Section 174.090 Shipping... Permeability of spaces. When doing the calculations required in § 174.065— (a) The permeability of a floodable space, other than a machinery space, must be as listed in Table 174.090; and (b) Calculations in which a...

  10. 46 CFR 174.090 - Permeability of spaces.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Permeability of spaces. 174.090 Section 174.090 Shipping... Permeability of spaces. When doing the calculations required in § 174.065— (a) The permeability of a floodable space, other than a machinery space, must be as listed in Table 174.090; and (b) Calculations in which a...

  11. 46 CFR 174.090 - Permeability of spaces.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Permeability of spaces. 174.090 Section 174.090 Shipping... Permeability of spaces. When doing the calculations required in § 174.065— (a) The permeability of a floodable space, other than a machinery space, must be as listed in Table 174.090; and (b) Calculations in which a...

  12. [Short-term curative effects of Tantalum rod treatment in early avascular necrosis].

    PubMed

    Ye, Fu-Sheng; Ni, Zhe-Ji; Chu, Xiao-Bing; He, Bang-Jian; Li, Ju; Tong, Pei-Jian

    2013-08-01

    To explore the recent clinical curative effect of Tantalum rod in treating the early avascular necrosis. From January 2008 to November 2008, the 25 patients (39 hips) with early avascular necrosis accepted tantalum rod placement and included 9 males (11 hips) and 16 females (28 hips) with an average age of 37 years old ranging from 18 to 74 years old. Four patients (6 hips) caused by Alcoholic, 6 patients (8 hips) by hormone, 2 cases (2 hips) by traumatic, 13 cases (23 hips) by idiopathic. Steinberg preoperative stage involved 7 hips in period I, 24 hips in period II, 8 hips in period III. Curative effect analysis included preoperative and postoperative Harris score, radiographic changes and hip replacement for follow-up to accept the end of the femoral head survival rate. All patients were followed up for 6 to 47 months (averaged 37.4 months). All 12 hips imaging appeard progress,including tantalum rod exit in 1 hip, hip hemiarthroplasty collapse in 3 hips, the area increased to avascular necrosis in 8 hips. Six hips accepted total hip replacement, including imaging progress in 5 hips (41.7%, 5/12), no imaging progress in 1 hip (3.7%,1/27). All hips' Kaplan-Meier survival curves showed 6-month survival rate was (97.4 +/- 2.5)% after tantalum stick insertion, 1-year survival rate was (94.7 +/- 3.6), and 2-year survival rate was (88.6 +/- 5.4)%, 3-year survival rate was (72.5 +/- 11.2). It is effective for treatment of avascular necrosis of femoral head in Steinberg I and II by Tantalum rod, and it can effectively relieve femoral head replacement time.

  13. Addition of oxygen to and distribution of oxides in tantalum alloy T-111 at low concentrations

    NASA Technical Reports Server (NTRS)

    Stecura, S.

    1975-01-01

    Oxygen was added at 820 and 990 C at an oxygen pressure of about .0003 torr. The technique permitted predetermined and reproducible oxygen doping of the tantalum alloy (T-111). Based on the temperature dependency of the doping reaction, it was concluded that the initial rates of oxygen pickup are probably controlled by solution of oxygen into the T-111 lattice. Although hafnium oxides are more stable than those of tantalum or tungsten, analyses of extracted residues indicate that the tantalum and tungsten oxides predominate in the as-doped specimens, presumably because of the higher concentrations of tantalum and tungsten in the alloy. However, high-temperature annealing promotes gettering of dissolved oxygen and oxygen from other oxides to form hafnium oxides. Small amounts of tantalum and tungsten oxides were still present after high temperature annealing. Tungsten oxide (WO3) volatilizes slightly from the surface of T-111 at 990 C but not at 820 C. The vaporization of WO3 has no apparent effect on the doping reaction.

  14. 49 CFR 174.110 - Car magazine.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Car magazine. 174.110 Section 174.110...) Materials § 174.110 Car magazine. When specially authorized by the carrier, Division 1.1 or 1.2 (explosive) materials in quantity not exceeding 68 kg (150 pounds) may be carried in construction or repair cars if the...

  15. 49 CFR 174.110 - Car magazine.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Car magazine. 174.110 Section 174.110...) Materials § 174.110 Car magazine. When specially authorized by the carrier, Division 1.1 or 1.2 (explosive) materials in quantity not exceeding 68 kg (150 pounds) may be carried in construction or repair cars if the...

  16. 49 CFR 174.110 - Car magazine.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Car magazine. 174.110 Section 174.110...) Materials § 174.110 Car magazine. When specially authorized by the carrier, Division 1.1 or 1.2 (explosive) materials in quantity not exceeding 68 kg (150 pounds) may be carried in construction or repair cars if the...

  17. 49 CFR 174.110 - Car magazine.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Car magazine. 174.110 Section 174.110...) Materials § 174.110 Car magazine. When specially authorized by the carrier, Division 1.1 or 1.2 (explosive) materials in quantity not exceeding 68 kg (150 pounds) may be carried in construction or repair cars if the...

  18. 49 CFR 174.110 - Car magazine.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Car magazine. 174.110 Section 174.110...) Materials § 174.110 Car magazine. When specially authorized by the carrier, Division 1.1 or 1.2 (explosive) materials in quantity not exceeding 68 kg (150 pounds) may be carried in construction or repair cars if the...

  19. The effects of argon ion bombardment on the corrosion resistance of tantalum

    NASA Astrophysics Data System (ADS)

    Ramezani, A. H.; Sari, A. H.; Shokouhy, A.

    2017-02-01

    Application of ion beam has been widely used as a surface modification method to improve surface properties. This paper investigates the effect of argon ion implantation on surface structure as well as resistance against tantalum corrosion. In this experiment, argon ions with energy of 30 keV and in doses of 1 × 1017-10 × 1017 ions/cm2 were used. The surface bombardment with inert gases mainly produces modified topography and morphology of the surface. Atomic Force Microscopy was also used to patterned the roughness variations prior to and after the implantation phase. Additionally, the corrosion investigation apparatus wear was applied to compare resistance against tantalum corrosion both before and after ion implantation. The results show that argon ion implantation has a substantial impact on increasing resistance against tantalum corrosion. After the corrosion test, scanning electron microscopy (SEM) analyzed the samples' surface morphologies. In addition, the elemental composition is characterized by energy-dispersive X-ray (EDX) analysis. The purpose of this paper was to obtain the perfect condition for the formation of tantalum corrosion resistance. In order to evaluate the effect of the ion implantation on the corrosion behavior, potentiodynamic tests were performed. The results show that the corrosion resistance of the samples strongly depends on the implantation doses.

  20. An exploration in mineral supply chain mapping using tantalum as an example

    USGS Publications Warehouse

    Soto-Viruet, Yadira; Menzie, W. David; Papp, John F.; Yager, Thomas R.

    2013-01-01

    This report uses the supply chain of tantalum (Ta) to investigate the complexity of mineral and metal supply chains in general and show how they can be mapped. A supply chain is made up of all the manufacturers, suppliers, information networks, and so forth, that provide the materials and parts that go into making up a final product. The mineral portion of the supply chain begins with mineral material in the ground (the ore deposit); extends through a series of processes that include mining, beneficiation, processing (smelting and refining), semimanufacture, and manufacture; and continues through transformation of the mineral ore into concentrates, refined mineral commodities, intermediate forms (such as metals and alloys), component parts, and, finally, complex products. This study analyses the supply chain of tantalum beginning with minerals in the ground to many of the final goods that contain tantalum.

  1. STUDIES ON ANALYTICAL METHODS FOR TRACE ELEMENTS IN METALS BY USING RADIOACTIVE ISOTOPE. III. DETERMINATION OF TANTALUM BY MEANS OF ISOTOPE DILUTION METHOD

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

    Amano, H.

    1959-10-01

    The determination of tantalum by the isotope dilution method in the presence of niobium was investigated by the use of the radioisotope Ta/sup 185/. Tantalum was separated from niobium as tantalum-tannin precipitate under the optimum conditions of a pH of 1.9 to 2.5 and a tantalum/niobium ratio of up to 1/ 50. If niobium was present in amounts 100 times or more that of tantalum, reprecipitation was needed. The reciprocal of the specific activity of tanthlum pentoxide precipitate was in a linear relation to the change in the amount of tantalum added. The recommended method gave an accurate result inmore » the determination of tantalum in steal. (auth)« less

  2. Thermocouples of tantalum and rhenium alloys for more stable vacuum-high temperature performance

    NASA Technical Reports Server (NTRS)

    Morris, J. F. (Inventor)

    1977-01-01

    Thermocouples of the present invention provide stability and performance reliability in systems involving high temperatures and vacuums by employing a bimetallic thermocouple sensor wherein each metal of the sensor is selected from a group of metals comprising tantalum and rhenium and alloys containing only those two metals. The tantalum, rhenium thermocouple sensor alloys provide bare metal thermocouple sensors having advantageous vapor pressure compatibilities and performance characteristics. The compatibility and physical characteristics of the thermocouple sensor alloys of the present invention result in improved emf, temperature properties and thermocouple hot junction performance. The thermocouples formed of the tantalum, rhenium alloys exhibit reliability and performance stability in systems involving high temperatures and vacuums and are adaptable to space propulsion and power systems and nuclear environments.

  3. 46 CFR 160.174-11 - Performance.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 6 2014-10-01 2014-10-01 false Performance. 160.174-11 Section 160.174-11 Shipping...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Thermal Protective Aids § 160.174-11 Performance. (a) Thermal... between −30 °C (−22 °F) and +65 C (149 °F). (d) In water performance. The thermal protective aid must be...

  4. 46 CFR 160.174-11 - Performance.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Performance. 160.174-11 Section 160.174-11 Shipping...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Thermal Protective Aids § 160.174-11 Performance. (a) Thermal... between −30 °C (−22 °F) and +65 C (149 °F). (d) In water performance. The thermal protective aid must be...

  5. 46 CFR 160.174-11 - Performance.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 6 2013-10-01 2013-10-01 false Performance. 160.174-11 Section 160.174-11 Shipping...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Thermal Protective Aids § 160.174-11 Performance. (a) Thermal... between −30 °C (−22 °F) and +65 C (149 °F). (d) In water performance. The thermal protective aid must be...

  6. 46 CFR 160.174-11 - Performance.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 6 2012-10-01 2012-10-01 false Performance. 160.174-11 Section 160.174-11 Shipping...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Thermal Protective Aids § 160.174-11 Performance. (a) Thermal... between −30 °C (−22 °F) and +65 C (149 °F). (d) In water performance. The thermal protective aid must be...

  7. Tantalum capacitor behavior under fast transient overvoltages. [circuit protection against lightning

    NASA Technical Reports Server (NTRS)

    Zill, J. A.; Castle, K. D.

    1974-01-01

    Tantalum capacitors were tested to determine failure time when subjected to short-duration, high-voltage surges caused by lightning strikes. Lightning is of concern to NASA because of possible damage to critical spacecraft circuits. The test was designed to determine the minimum time for tantalum capacitor failure and the amount of overvoltage a capacitor could survive, without permanent damage, in 100 microseconds. All tested exhibited good recovery from the transient one-shot pulses with no failure at any voltage, forward or reverse, in less than 25 microseconds.

  8. SU-E-J-201: Position Verification in Breast Cancer Radiotherapy Using Tantalum Clips in the Lumpectomy Cavity

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

    Santvoort, J van; Van der Drift, M; Kuipers, J

    2014-06-01

    Purpose: To find out whether tantalum surgical clips can be used for online position verification in treatment of the lumpectomy cavity (LC) in breast cancer patients. Tantalum is a high density metal that could be visible on Electronic Portal Images (EPIs) and be an affordable alternative to gold markers. Clips are considered more representative for the LC position than nearby bony structures. Methods: In twelve patients the surgeon had placed 2 to 5 tantalum clips in the LC. The AP and lateral fields used for portal imaging, were adapted. In doing so, both bony structures and tantalum clips were visiblemore » on EPIs. The following analyses were performed:1. Image degradation, with respect to delineating the CTV, of the axial CT slices by artefacts because of the tantalum clips was evaluated by a radiation oncologist;2. The visibility of the tantalum clips on the EPIs was evaluated by four radiation therapists (RTTs);3. Bony anatomy and tantalum clip matches were performed on the same images independently by two observers. Results: 1. Delineation of the CTV by the radiation oncologist was not hampered by CT image artefacts because of the clips.2. The mean score for visibility of the clips on the EPIs, analysed by the four RTTs, was 5.6 on a scale of 10 (range 3.9 – 8.0).3. In total 12 patients with 16 fractions each were analysed. The differences between clip match and bone match are significant with a mean vector length of 5.2 mm (SD 1.9 mm) for the difference. Conclusion: Results of matches on tantalum clips as compared to matches on bony structures differ substantially. Therefore clip matches can result in smaller CTV to PTV margins than bone matches. Visibility of the clips on EPIs is sufficient, so they can be an alternative to gold markers.« less

  9. The application of porous tantalum cylinder to the repair of comminuted bone defects: a study of rabbit firearm injuries

    PubMed Central

    Ren, Bo; Zhai, Zhenbo; Guo, Kai; Liu, Yanpu; Hou, Weihuan; Zhu, Qingsheng; Zhu, Jinyu

    2015-01-01

    The aim of this study is to investigate the effect of porous tantalum material in repair tibial defects caused by firearm injuries in a rabbit model. A multifunctional biological impact machine was used to establish a rabbit tibial defect model of firearm injury. Porous tantalum rods were processed into a hollow cylinder. Kirschner wires were used for intramedullary fixation. We compared the differences of the bone ingrowth of the porous tantalum material by gross observations, X-rays and histological evaluations. The radiographic observations revealed that fibrous tissue covered the material surface after 4 weeks, and periosteal reactions and new bone callus extending materials appeared after 8 weeks. After 16 weeks, the calluses of the firearm injury group were completely wrapped around a porous tantalum material. The group with the highest Lane-Sandhu X-rays cores was the firearm injury and tantalum implant group, and the blank control group exhibited the lowest scores. The histological evaluations revealed that the presence of new bone around the biomaterial had grown into the porous tantalum. By the 16th week, the areas of bone tissue of the firearm injury group was significant higher than that of non-firearm injury group (P<0.05). The comminuted fractures treated with tantalum cylinders exhibited greater bone ingrowth in the firearm injury group. In conditions of firearm injuries, the porous tantalum biomaterial exhibited bone ingrowth that was beneficial to the treatment of bone defects. PMID:26131078

  10. 40 CFR 415.174 - [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 29 2014-07-01 2012-07-01 true [Reserved] 415.174 Section 415.174 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS INORGANIC CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Sodium Dichromate and Sodium Sulfate Production...

  11. 7 CFR 993.174 - Records.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Records. 993.174 Section 993.174 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE DRIED PRUNES PRODUCED IN CALIFORNIA...

  12. Transition of dislocation glide to shear transformation in shocked tantalum

    DOE PAGES

    Hsiung, Luke L.; Campbell, Geoffrey H.

    2017-02-28

    A TEM study of pure tantalum and tantalum-tungsten alloys explosively shocked at a peak pressure of 30 GPa (strain rate: ~1 x 10 4 sec -1) is presented. While no ω (hexagonal) phase was found in shock-recovered pure Ta and Ta-5W that contain mainly a low-energy cellular dislocation structure, shock-induced ω phase was found to form in Ta-10W that contains evenly distributed dislocations with a stored dislocation density higher than 1 x 10 12 cm -2. The TEM results clearly reveal that shock-induced α (bcc) → ω (hexagonal) shear transformation occurs when dynamic recovery reactions which lead the formation low-energymore » cellular dislocation structure become largely suppressed in Ta-10W shocked under dynamic (i.e., high strain-rate and high-pressure) conditions. A novel dislocation-based mechanism is proposed to rationalize the transition of dislocation glide to twinning and/or shear transformation in shock-deformed tantalum. Lastly, twinning and/or shear transformation take place as an alternative deformation mechanism to accommodate high-strain-rate straining when the shear stress required for dislocation multiplication exceeds the threshold shear stresses for twinning and/or shear transformation.« less

  13. High-acoustic-impedance tantalum oxide layers for insulating acoustic reflectors.

    PubMed

    Capilla, Jose; Olivares, Jimena; Clement, Marta; Sangrador, Jesús; Iborra, Enrique; Devos, Arnaud

    2012-03-01

    This work describes the assessment of the acoustic properties of sputtered tantalum oxide films intended for use as high-impedance films of acoustic reflectors for solidly mounted resonators operating in the gigahertz frequency range. The films are grown by sputtering a metallic tantalum target under different oxygen and argon gas mixtures, total pressures, pulsed dc powers, and substrate biases. The structural properties of the films are assessed through infrared absorption spectroscopy and X-ray diffraction measurements. Their acoustic impedance is assessed by deriving the mass density from X-ray reflectometry measurements and the acoustic velocity from picosecond acoustic spectroscopy and the analysis of the frequency response of the test resonators.

  14. 33 CFR 174.103 - Administration.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Administration. 174.103 Section 174.103 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED....103 Administration. The State casualty reporting system must be administered by a State agency that...

  15. 33 CFR 174.103 - Administration.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Administration. 174.103 Section 174.103 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED....103 Administration. The State casualty reporting system must be administered by a State agency that...

  16. 33 CFR 174.103 - Administration.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Administration. 174.103 Section 174.103 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED....103 Administration. The State casualty reporting system must be administered by a State agency that...

  17. 33 CFR 174.103 - Administration.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Administration. 174.103 Section 174.103 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED....103 Administration. The State casualty reporting system must be administered by a State agency that...

  18. 33 CFR 174.103 - Administration.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Administration. 174.103 Section 174.103 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED....103 Administration. The State casualty reporting system must be administered by a State agency that...

  19. 50 CFR 217.174 - Mitigation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 10 2012-10-01 2012-10-01 false Mitigation. 217.174 Section 217.174 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS REGULATIONS GOVERNING THE TAKE OF MARINE MAMMALS INCIDENTAL TO...

  20. 50 CFR 217.174 - Mitigation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 10 2014-10-01 2014-10-01 false Mitigation. 217.174 Section 217.174 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS REGULATIONS GOVERNING THE TAKE OF MARINE MAMMALS INCIDENTAL TO...

  1. 50 CFR 217.174 - Mitigation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false Mitigation. 217.174 Section 217.174 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS REGULATIONS GOVERNING THE TAKE OF MARINE MAMMALS INCIDENTAL TO...

  2. 50 CFR 217.174 - Mitigation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 10 2013-10-01 2013-10-01 false Mitigation. 217.174 Section 217.174 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS REGULATIONS GOVERNING THE TAKE OF MARINE MAMMALS INCIDENTAL TO...

  3. Effect of Reverse Bias Stress on Leakage Currents and Breakdown Voltages of Solid Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander A.

    2011-01-01

    The majority of solid tantalum capacitors are produced by high-temperature sintering of a fine tantalum powder around a tantalum wire followed by electrolytic anodization that forms a thin amorphous Ta2O5 dielectric layer and pyrolysis of manganese nitrite on the oxide to create a conductive manganese dioxide electrode. A contact to tantalum wire is used as anode terminal and to the manganese layer as a cathode terminal of the device. This process results in formation of an asymmetric Ta -- Ta2O5 -- MnO2 capacitor that has different characteristics at forward (positive bias applied to tantalum) and reverse (positive bias applied to manganese cathode) voltages. Reverse bias currents might be several orders of magnitude larger than forward leakage currents so I-V characteristics of tantalum capacitors resemble characteristics of semiconductor rectifiers. Asymmetric I-V characteristics of Ta -- anodic Ta2O5 systems have been observed at different top electrode materials including metals, electrolytes, conductive polymers, and manganese oxide thus indicating that this phenomenon is likely related to the specifics of the Ta -- Ta2O5 interface. There have been multiple attempts to explain rectifying characteristics of capacitors employing anodic tantalum pentoxide dielectrics. A brief review of works related to reverse bias (RB) behavior of tantalum capacitors shows that the mechanism of conduction in Ta -- Ta2O5 systems is still not clear and more testing and analysis is necessary to understand the processes involved. If tantalum capacitors behave just as rectifiers, then the assessment of the safe reverse bias operating conditions would be a relatively simple task. Unfortunately, these parts can degrade with time under reverse bias significantly, and this further complicates analysis of the I-V characteristics and establishing safe operating areas of the parts. On other hand, time dependence of reverse currents might provide additional information for investigation of

  4. Clustering of transmutation elements tantalum, rhenium and osmium in tungsten in a fusion environment

    NASA Astrophysics Data System (ADS)

    You, Yu-Wei; Kong, Xiang-Shan; Wu, Xuebang; Liu, C. S.; Fang, Q. F.; Chen, J. L.; Luo, G.-N.

    2017-08-01

    The formation of transmutation solute-rich precipitates has been reported to seriously degrade the mechanical properties of tungsten in a fusion environment. However, the underlying mechanisms controlling the formation of the precipitates are still unknown. In this study, first-principles calculations are therefore performed to systemically determine the stable structures and binding energies of solute clusters in tungsten consisting of tantalum, rhenium and osmium atoms as well as irradiation-induced vacancies. These clusters are known to act as precursors for the formation of precipitates. We find that osmium can easily segregate to form clusters even in defect-free tungsten alloys, whereas extremely high tantalum and rhenium concentrations are required for the formation of clusters. Vacancies greatly facilitate the clustering of rhenium and osmium, while tantalum is an exception. The binding energies of vacancy-osmium clusters are found to be much higher than those of vacancy-tantalum and vacancy-rhenium clusters. Osmium is observed to strongly promote the formation of vacancy-rhenium clusters, while tantalum can suppress the formation of vacancy-rhenium and vacancy-osmium clusters. The local strain and electronic structure are analyzed to reveal the underlying mechanisms governing the cluster formation. Employing the law of mass action, we predict the evolution of the relative concentration of vacancy-rhenium clusters. This work presents a microscopic picture describing the nucleation and growth of solute clusters in tungsten alloys in a fusion reactor environment, and thereby explains recent experimental phenomena.

  5. Deposition and characterization of magnetron sputtered bcc tantalum

    NASA Astrophysics Data System (ADS)

    Patel, Anamika

    The goal of this thesis was to provide scientific and technical research results for developing and characterizing tantalum (Ta) coatings on steel substrates deposited by DC magnetron sputtering. Deposition of tantalum on steel is of special interest for the protection it offers to surfaces, e.g. the surfaces of gun barrels against the erosive wear of hot propellant gases and the mechanical damage caused by the motion of launching projectiles. Electro-plated chromium is presently most commonly used for this purpose; however, it is considered to be carcinogenic in its hexavalent form. Tantalum is being investigated as non-toxic alternative to chromium and also because of its superior protective properties in these extreme environments. DC magnetron sputtering was chosen for this investigation of tantalum coatings on steel substrates because it is a versatile industrial proven process for deposition of metals. Sputter deposited Ta films can have two crystallographic structures: (1) body center cubic (bcc) phase, characterized by high toughness and high ductility and (2) a tetragonal beta phase characterized by brittleness and a tendency to fail under stress. It was found in this work that the bcc Ta coatings on steel can be obtained reliably by either of two methods: (1) depositing Ta on a submicron, stoichiometric TaN seed layer reactively sputtered on unheated steel and (2) depositing Ta directly on steel heated above a critical temperature. For argon sputtering gas this critical temperature was found to be 400°C at a pressure of 5 mtorr. With the heavier krypton gas, this critical temperature is reduced to 350°C. X-ray diffraction (XRD) was used to investigate the structure of tantalum and nitride films, and the composition of the nitride films was measured by nuclear reaction analyses (NRA), which were used to study in detail the enhancement of the bcc phase of Ta on steel. The scratch adhesion tests performed with a diamond hemispherical tip of radius 200 mum

  6. Mineral resource of the month: tantalum

    USGS Publications Warehouse

    Cunningham, Larry D.

    2004-01-01

    Tantalum is a metal that is critical to the United States because of its defense-related applications in aircraft, missiles and radio communications. It is ductile, easily fabricated, highly resistant to corrosion by acids, a good conductor of heat and electricity, and has a high melting point. Tantalum’s first commercial usage was as filament material in incandescent electric lamps in the early 1900s.

  7. Tantalum coating of porous carbon scaffold supplemented with autologous bone marrow stromal stem cells for bone regeneration in vitro and in vivo.

    PubMed

    Wei, Xiaowei; Zhao, Dewei; Wang, Benjie; Wang, Wei; Kang, Kai; Xie, Hui; Liu, Baoyi; Zhang, Xiuzhi; Zhang, Jinsong; Yang, Zhenming

    2016-03-01

    Porous tantalum metal with low elastic modulus is similar to cancellous bone. Reticulated vitreous carbon (RVC) can provide three-dimensional pore structure and serves as the ideal scaffold of tantalum coating. In this study, the biocompatibility of domestic porous tantalum was first successfully tested with bone marrow stromal stem cells (BMSCs) in vitro and for bone tissue repair in vivo. We evaluated cytotoxicity of RVC scaffold and tantalum coating using BMSCs. The morphology, adhesion, and proliferation of BMSCs were observed via laser scanning confocal microscope and scanning electron microscopy. In addition, porous tantalum rods with or without autologous BMSCs were implanted on hind legs in dogs, respectively. The osteogenic potential was observed by hard tissue slice examination. At three weeks and six weeks following implantation, new osteoblasts and new bone were observed at the tantalum-host bone interface and pores. At 12 weeks postporous tantalum with autologous BMSCs implantation, regenerated trabecular equivalent to mature bone was found in the pore of tantalum rods. Our results suggested that domestic porous tantalum had excellent biocompatibility and could promote new bone formation in vivo. Meanwhile, the osteogenesis of porous tantalum associated with autologous BMSCs was more excellent than only tantalum implantation. Future clinical studies are warranted to verify the clinical efficacy of combined implantation of this domestic porous tantalum associated with autologous BMSCs implantation and compare their efficacy with conventional autologous bone grafting carrying blood vessel in patients needing bone repairing. © 2016 by the Society for Experimental Biology and Medicine.

  8. 46 CFR 174.045 - Intact stability requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Intact stability requirements. 174.045 Section 174.045 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling Units § 174.045...

  9. 46 CFR 174.050 - Stability on bottom.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Stability on bottom. 174.050 Section 174.050 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling Units § 174.050...

  10. 46 CFR 174.045 - Intact stability requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Intact stability requirements. 174.045 Section 174.045 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling Units § 174.045...

  11. 46 CFR 174.065 - Damage stability requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Damage stability requirements. 174.065 Section 174.065 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling Units § 174.065...

  12. 46 CFR 174.065 - Damage stability requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Damage stability requirements. 174.065 Section 174.065 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling Units § 174.065...

  13. 46 CFR 174.050 - Stability on bottom.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Stability on bottom. 174.050 Section 174.050 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling Units § 174.050...

  14. 7 CFR 1726.151-1726.174 - [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 11 2010-01-01 2010-01-01 false [Reserved] 1726.151-1726.174 Section 1726.151-1726.174 Agriculture Regulations of the Department of Agriculture (Continued) RURAL UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE ELECTRIC SYSTEM CONSTRUCTION POLICIES AND PROCEDURES Buildings §§ 1726.151-1726.174...

  15. 49 CFR 174.67 - Tank car unloading.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Tank car unloading. 174.67 Section 174.67... and Loading Requirements § 174.67 Tank car unloading. For transloading operations, the following rules... least one wheel to prevent movement in any direction. If multiple tank cars are coupled together...

  16. 49 CFR 174.67 - Tank car unloading.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Tank car unloading. 174.67 Section 174.67... and Loading Requirements § 174.67 Tank car unloading. For transloading operations, the following rules... least one wheel to prevent movement in any direction. If multiple tank cars are coupled together...

  17. 49 CFR 174.67 - Tank car unloading.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Tank car unloading. 174.67 Section 174.67... and Loading Requirements § 174.67 Tank car unloading. For transloading operations, the following rules... least one wheel to prevent movement in any direction. If multiple tank cars are coupled together...

  18. 49 CFR 174.67 - Tank car unloading.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Tank car unloading. 174.67 Section 174.67... and Loading Requirements § 174.67 Tank car unloading. For transloading operations, the following rules... least one wheel to prevent movement in any direction. If multiple tank cars are coupled together...

  19. 46 CFR 160.174-25 - Production testing.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 6 2010-10-01 2010-10-01 false Production testing. 160.174-25 Section 160.174-25...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Thermal Protective Aids § 160.174-25 Production testing. (a) Thermal protective aid production testing is conducted under the procedures in this section and subpart...

  20. 46 CFR 160.174-13 - Storage case.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 6 2014-10-01 2014-10-01 false Storage case. 160.174-13 Section 160.174-13 Shipping...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Thermal Protective Aids § 160.174-13 Storage case. Each thermal protective aid must be provided with a ziplock bag or equivalent storage case. ...

  1. 46 CFR 160.174-13 - Storage case.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Storage case. 160.174-13 Section 160.174-13 Shipping...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Thermal Protective Aids § 160.174-13 Storage case. Each thermal protective aid must be provided with a ziplock bag or equivalent storage case. ...

  2. 46 CFR 160.174-13 - Storage case.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 6 2012-10-01 2012-10-01 false Storage case. 160.174-13 Section 160.174-13 Shipping...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Thermal Protective Aids § 160.174-13 Storage case. Each thermal protective aid must be provided with a ziplock bag or equivalent storage case. ...

  3. 46 CFR 160.174-13 - Storage case.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 6 2010-10-01 2010-10-01 false Storage case. 160.174-13 Section 160.174-13 Shipping...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Thermal Protective Aids § 160.174-13 Storage case. Each thermal protective aid must be provided with a ziplock bag or equivalent storage case. ...

  4. 46 CFR 160.174-13 - Storage case.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 6 2013-10-01 2013-10-01 false Storage case. 160.174-13 Section 160.174-13 Shipping...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Thermal Protective Aids § 160.174-13 Storage case. Each thermal protective aid must be provided with a ziplock bag or equivalent storage case. ...

  5. 37 CFR 1.74 - Reference to drawings.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2014-07-01 2014-07-01 false Reference to drawings. 1.74 Section 1.74 Patents, Trademarks, and Copyrights UNITED STATES PATENT AND TRADEMARK OFFICE, DEPARTMENT OF COMMERCE GENERAL RULES OF PRACTICE IN PATENT CASES National Processing Provisions Specification § 1.74...

  6. 37 CFR 1.74 - Reference to drawings.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2011-07-01 2011-07-01 false Reference to drawings. 1.74 Section 1.74 Patents, Trademarks, and Copyrights UNITED STATES PATENT AND TRADEMARK OFFICE, DEPARTMENT OF COMMERCE GENERAL RULES OF PRACTICE IN PATENT CASES National Processing Provisions Specification § 1.74...

  7. 46 CFR 160.174-5 - Independent laboratory.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 6 2011-10-01 2011-10-01 false Independent laboratory. 160.174-5 Section 160.174-5...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Thermal Protective Aids § 160.174-5 Independent laboratory. (a... laboratory accepted by the Coast Guard under subpart 159.010 of this chapter. (b) [Reserved] ...

  8. 46 CFR 160.174-5 - Independent laboratory.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 6 2010-10-01 2010-10-01 false Independent laboratory. 160.174-5 Section 160.174-5...: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Thermal Protective Aids § 160.174-5 Independent laboratory. (a... laboratory accepted by the Coast Guard under subpart 159.010 of this chapter. (b) [Reserved] ...

  9. Tantalum coating of porous carbon scaffold supplemented with autologous bone marrow stromal stem cells for bone regeneration in vitro and in vivo

    PubMed Central

    Wei, Xiaowei; Wang, Benjie; Wang, Wei; Kang, Kai; Xie, Hui; Liu, Baoyi; Zhang, Xiuzhi; Zhang, Jinsong; Yang, Zhenming

    2016-01-01

    Porous tantalum metal with low elastic modulus is similar to cancellous bone. Reticulated vitreous carbon (RVC) can provide three-dimensional pore structure and serves as the ideal scaffold of tantalum coating. In this study, the biocompatibility of domestic porous tantalum was first successfully tested with bone marrow stromal stem cells (BMSCs) in vitro and for bone tissue repair in vivo. We evaluated cytotoxicity of RVC scaffold and tantalum coating using BMSCs. The morphology, adhesion, and proliferation of BMSCs were observed via laser scanning confocal microscope and scanning electron microscopy. In addition, porous tantalum rods with or without autologous BMSCs were implanted on hind legs in dogs, respectively. The osteogenic potential was observed by hard tissue slice examination. At three weeks and six weeks following implantation, new osteoblasts and new bone were observed at the tantalum–host bone interface and pores. At 12 weeks postporous tantalum with autologous BMSCs implantation, regenerated trabecular equivalent to mature bone was found in the pore of tantalum rods. Our results suggested that domestic porous tantalum had excellent biocompatibility and could promote new bone formation in vivo. Meanwhile, the osteogenesis of porous tantalum associated with autologous BMSCs was more excellent than only tantalum implantation. Future clinical studies are warranted to verify the clinical efficacy of combined implantation of this domestic porous tantalum associated with autologous BMSCs implantation and compare their efficacy with conventional autologous bone grafting carrying blood vessel in patients needing bone repairing. PMID:26843518

  10. 10 CFR 72.174 - Quality assurance records.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 2 2010-01-01 2010-01-01 false Quality assurance records. 72.174 Section 72.174 Energy... NUCLEAR FUEL, HIGH-LEVEL RADIOACTIVE WASTE, AND REACTOR-RELATED GREATER THAN CLASS C WASTE Quality Assurance § 72.174 Quality assurance records. The licensee, applicant for a license, certificate holder, and...

  11. 10 CFR 72.174 - Quality assurance records.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 2 2011-01-01 2011-01-01 false Quality assurance records. 72.174 Section 72.174 Energy... NUCLEAR FUEL, HIGH-LEVEL RADIOACTIVE WASTE, AND REACTOR-RELATED GREATER THAN CLASS C WASTE Quality Assurance § 72.174 Quality assurance records. The licensee, applicant for a license, certificate holder, and...

  12. 10 CFR 72.174 - Quality assurance records.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 2 2012-01-01 2012-01-01 false Quality assurance records. 72.174 Section 72.174 Energy... NUCLEAR FUEL, HIGH-LEVEL RADIOACTIVE WASTE, AND REACTOR-RELATED GREATER THAN CLASS C WASTE Quality Assurance § 72.174 Quality assurance records. The licensee, applicant for a license, certificate holder, and...

  13. 10 CFR 72.174 - Quality assurance records.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 2 2014-01-01 2014-01-01 false Quality assurance records. 72.174 Section 72.174 Energy... NUCLEAR FUEL, HIGH-LEVEL RADIOACTIVE WASTE, AND REACTOR-RELATED GREATER THAN CLASS C WASTE Quality Assurance § 72.174 Quality assurance records. The licensee, applicant for a license, certificate holder, and...

  14. Antimicrobial activity of tantalum oxide coatings decorated with Ag nanoparticles

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

    Cao, Huiliang, E-mail: hlc@mail.sic.ac.cn; Meng, Fanhao; Liu, Xuanyong, E-mail: xyliu@mail.sic.ac.cn

    Silver plasma immersion ion implantation was used to decorate silver nanoparticles (Ag NPs) on tantalum oxide (TO) coatings. The coatings acted against bacterial cells (Staphylococcus epidermidis) in the dark by disrupting their integrity. The action was independent of silver release and likely driven by the electron storage capability of the Schottky barriers established at the interfaces between Ag NPs and the TO support. Moreover, no apparent side effect on the adhesion and differentiation of rat bone mesenchymal stem cells was detected when using Ag NPs-modified TO coatings. These results demonstrate that decoration of tantalum oxide using Ag NPs could bemore » a promising procedure for improving the antibacterial properties for orthopedic and dental implants.« less

  15. 27 CFR 26.174 - Records.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Records. 26.174 Section 26... Eligible Articles From Puerto Rico § 26.174 Records. (a) General. Every person intending to file claim for drawback on eligible articles brought into the United States from Puerto Rico shall keep permanent records...

  16. Application of pyrolysis to recycling organics from waste tantalum capacitors.

    PubMed

    Niu, Bo; Chen, Zhenyang; Xu, Zhenming

    2017-08-05

    Tantalum capacitors (TCs) are widely used in electronic appliances. The rapid replacement of electronic products results in generating large amounts of waste TCs (WTCs). WTCs, rich in valuable tantalum, are considered as high quality tantalum resources for recycling. However, environmental pollution will be caused if the organics of WTCs were not properly disposed. Therefore, effectively recycling the organics of WTCs is significant for recovering the valuable parts. This study proposed an argon (Ar) pyrolysis process to recycle the organics from WTCs. The organic decomposition kinetic was first analyzed by thermogravimetry. The results showed that the organics were decomposed in two major steps and the average activation energy was calculated to 234kJ/mol. Then, the suitable pyrolysis parameters were determined as 550°C, 30min and 100ml/min. The organics were effectively decomposed and converted to oils (mainly contained phenol homologs and benzene homologs) and gases (some hydrocarbon). These pyrolysis products could be reutilized as energy sources. Moreover, based on the products and bond energy theory, the pyrolysis mechanisms of the organics were also discussed. Finally, a reasonable technological process for products utilization was presented. This study contributes to the efficient recycling the organics before valuable material recovery from WTCs. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Achieving surface chemical and morphologic alterations on tantalum by plasma electrolytic oxidation.

    PubMed

    Goularte, Marcelo Augusto Pinto Cardoso; Barbosa, Gustavo Frainer; da Cruz, Nilson Cristino; Hirakata, Luciana Mayumi

    2016-12-01

    Search for materials that may either replace titanium dental implants or constitute an alternative as a new dental implant material has been widely studied. As well, the search for optimum biocompatible metal surfaces remains crucial. So, the aim of this work is to develop an oxidized surface layer on tantalum using plasma electrolytic oxidation (PEO) similar to those existing on oral implants been marketed today. Cleaned tantalum samples were divided into group 1 (control) and groups 2, 3, and 4 (treated by PEO for 1, 3, and 5 min, respectively). An electrolytic solution diluted in 1-L deionized water was used for the anodizing process. Then, samples were washed with anhydrous ethyl alcohol and dried in the open air. For complete anodic treatment disposal, the samples were immersed in acetone altogether, taken to the ultrasonic tank for 10 min, washed again in distilled water, and finally air-dried. For the scanning electron microscopy (SEM) analysis, all samples were previously coated with gold; the salt deposition analysis was conducted with an energy-dispersive X-ray spectroscopy (EDS) system integrated with the SEM unit. SEM images confirmed the changes on tantalum strips surface according to different exposure times while EDS analysis confirmed increased salt deposition as exposure time to the anodizing process also increased. PEO was able to produce both surface alteration and salt deposition on tantalum strips similar to those existing on oral implants been marketed today.

  18. 27 CFR 25.174 - Bond not sufficient.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bond not sufficient. 25.174 Section 25.174 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS BEER Tax on Beer Prepayment of Tax § 25.174 Bond not sufficient. When the...

  19. 27 CFR 25.174 - Bond not sufficient.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Bond not sufficient. 25.174 Section 25.174 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL BEER Tax on Beer Prepayment of Tax § 25.174 Bond not sufficient. When the...

  20. 27 CFR 25.174 - Bond not sufficient.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Bond not sufficient. 25.174 Section 25.174 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL BEER Tax on Beer Prepayment of Tax § 25.174 Bond not sufficient. When the...

  1. 27 CFR 25.174 - Bond not sufficient.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Bond not sufficient. 25.174 Section 25.174 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS BEER Tax on Beer Prepayment of Tax § 25.174 Bond not sufficient. When the...

  2. 27 CFR 25.174 - Bond not sufficient.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Bond not sufficient. 25.174 Section 25.174 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS BEER Tax on Beer Prepayment of Tax § 25.174 Bond not sufficient. When the...

  3. X-ray analyses of thermally grown and reactively sputtered tantalum oxide films on NiTi alloy

    NASA Astrophysics Data System (ADS)

    McNamara, Karrina; Tofail, Syed A. M.; Conroy, Derek; Butler, James; Gandhi, Abbasi A.; Redington, Wynette

    2012-08-01

    Sputter deposition of tantalum (Ta) on the surface of NiTi alloy is expected to improve the alloy's corrosion resistance and biocompatibility. Tantalum is a well-known biomaterial which is not affected by body fluids and is not irritating to human tissue. Here we compare the oxidation chemistry crystal structure evolution of tantalum oxide films grown on NiTi by reactive O2 sputtering and by thermal oxidation of sputter deposited Ta films. The effect of sputtering parameters and post-sputtering treatments on the morphology, oxidation state and crystal structure of the tantalum oxide layer have been investigated by field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The study has found that it may be better to avoid oxidation at and above 600 °C. The study establishes that reactive sputtering in presence of low oxygen mixture yields thicker film with better control of the film quality except that the surface oxidation state of Ta is slightly lower.

  4. Synthesis and characterization of polystyrene embolization particles doped with tantalum oxide nanoparticles for X-ray contrast.

    PubMed

    Morrison, Rachel; Thompson, James; Bird, Luke; Hill, Mark A; Townley, Helen

    2015-08-01

    Radiopaque and fluorescent embolic particles have been synthesized and characterised to match the size of vasculature found in tumours to ensure effective occlusion of the vessels. A literature search showed that the majority of vessels surrounding a tumour were less than 50 µm and therefore polydispersed polystyrene particles with a peak size of 50 µm have been synthesised. The embolic particles contain 5-8 nm amorphous tantalum oxide nanoparticles which provide X-ray contrast. Embolic particles containing up to 9.4 wt% tantalum oxide were prepared and showed significant contrast compared to the undoped polystyrene particles. The X-ray contrast of the embolic particles was shown to be linear (R(2) = 0.9) with respect to the concentration of incorporated tantalum nanoparticles. A model was developed which showed that seventy-five 50 µm embolic particles containing 10% tantalum oxide could provide the same contrast as 5 cm of bone. Therefore, the synthesized particles would provide sufficient X-ray contrast to enable visualisation within a tumour.

  5. Effect of the oxygen content in a salt solution on the characteristics of sodium-reduced tantalum powders

    NASA Astrophysics Data System (ADS)

    Kolosov, V. N.; Orlov, V. M.; Miroshnichenko, M. N.; Prokhorova, T. Yu.; Masloboeva, S. M.; Belyaevskii, A. T.

    2009-02-01

    The characteristics of the tantalum powders produced by sodium thermal reduction from salt melts based on K2TaF7 and NaCl with various amounts of added oxycompounds K3TaOF6 and K2Ta2O3F6 are studied. At a molar ratio of oxygen to tantalum of 1.25 in the initial melt, capacitor tantalum powders with a specific surface area more than 3 m2/g are produced. The specific capacitance of the anodes made from these powders reaches 58 mC/g.

  6. 46 CFR 174.330 - Jettisoning of spoil.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments Calculations § 174.330 Jettisoning of spoil. (a) When doing the calculations required by § 174.310 for a hopper dredge with bottom... calculations required by § 174.310 for a hopper dredge with a split hull, it may be assumed that the spoil is...

  7. 46 CFR 174.330 - Jettisoning of spoil.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments Calculations § 174.330 Jettisoning of spoil. (a) When doing the calculations required by § 174.310 for a hopper dredge with bottom... calculations required by § 174.310 for a hopper dredge with a split hull, it may be assumed that the spoil is...

  8. Crystalline phase-stability of tantalum pentoxide

    NASA Astrophysics Data System (ADS)

    Walton, Santiago; Padilha, Antonio; Dalpian, Gustavo; Guillén, Jorge; Dalpian's Research Group Collaboration; Grupo de Estado Solido Collaboration; Gritad Collaboration

    2013-03-01

    Memristive devices are attractive candidates to provide a paradigm change in memory devices fabrication. These new devices would be faster, denser and less power consuming than those available today. However, the mechanism of memristance is not yet well understood. It is believed that a voltage/current-driven phase transition occurs in the material, which leads to significant changes in the device's conductivity. In the particular case of tantalum-oxide-based devices the relevant crystalline phases are still a matter of debate. Some of these phases are not even completely known and there is no agreement about which model best explains the crystallographic results. In this work we have performed ab-initio DFT based calculations to study the structural properties of different phases (and models) of Ta2O5 - the structure which is believed to exist inside Tantalum Oxide based devices. The equations of state for this material were constructed through first principles total energy calculations and we have also calculated the phonon frequencies at Γ. These results show that the most stable phase of this oxide (B-Ta2O5) is in fact composed of octahedral, instead of pentagonal (as L-Ta2O5) or hexagonal (as δ-Ta2O5) bipyramids. Fapesp, CNPq, Capes,CODI-UdeA

  9. Evaluation of the 3D Finite Element Method Using a Tantalum Rod for Osteonecrosis of the Femoral Head

    PubMed Central

    Shi, Jingsheng; Chen, Jie; Wu, Jianguo; Chen, Feiyan; Huang, Gangyong; Wang, Zhan; Zhao, Guanglei; Wei, Yibing; Wang, Siqun

    2014-01-01

    Background The aim of this study was to contrast the collapse values of the postoperative weight-bearing areas of different tantalum rod implant positions, fibula implantation, and core decompression model and to investigate the advantages and disadvantages of tantalum rod implantation in different ranges of osteonecrosis in comparison with other methods. Material/Methods The 3D finite element method was used to establish the 3D finite element model of normal upper femur, 3D finite element model after tantalum rod implantation into different positions of the upper femur in different osteonecrosis ranges, and other 3D finite element models for simulating fibula implant and core decompression. Results The collapse values in the weight-bearing area of the femoral head of the tantalum rod implant model inside the osteonecrosis area, implant model in the middle of the osteonecrosis area, fibula implant model, and shortening implant model exhibited no statistically significant differences (p>0.05) when the osteonecrosis range was small (60°). The stress values on the artificial bone surface for the tantalum rod implant model inside the osteonecrosis area and the shortening implant model exhibited statistical significance (p<0.01). Conclusions Tantalum rod implantation into the osteonecrosis area can reduce the collapse values in the weight-bearing area when osteonecrosis of the femoral head (ONFH) was in a certain range, thereby obtaining better clinical effects. When ONFH was in a large range (120°), the tantalum rod implantation inside the osteonecrosis area, shortening implant or fibula implant can reduce the collapse values of the femoral head, as assessed by other methods. PMID:25479830

  10. The effect of tantalum and carbon on the structure/properties of a single crystal nickel-base superalloy. M.S. Thesis. Final Report

    NASA Technical Reports Server (NTRS)

    Nguyen, H. C.

    1984-01-01

    The microstructure, phase chemistry, and creep and hot tensile properties were studied as a function of tantalum and carbon levels in Mar-M247 type single crystal alloys. Microstructural studies showed that several types of carbides (MC, M23C6 and M5C) are present in the normal carbon (0.10 wt % C) alloys after heat treatment. In general, the composition of the MC carbides changes from titanium rich to tantalum rich as the tantalum level in the alloy increases. Small M23C6 carbides are present in all alloys. Tungsten rich M6C carbides are also observed in the alloy containing no tantalum. No carbides are present in the low carbon (0.01 wt % C) alloy series. The morphology of gamma prime is observed to be sensitive to heat treatment and tantalum level in the alloy. Cuboidal gamma prime is present in all the as cast structures. After heat treatment, the gamma prime precipitates tend to have a more spheroidal like morphology, and this tendency increases as the tantalum level decreases. On prolonged aging, the gamma prime reverts back to a cuboidal morphology or under stress at high temperatures, forms a rafted structure. The weight fraction and lattice parameter of the spheroidal gamma prime increases with increasing tantalum content. Changes in the phase chemistry of the gamma prime matrix and gamma prime have also been analyzed using phase extraction techniques. The partitioning ratio decreases for tungsten and aluminum and increases for tantalum as the tantalum content increases for both alloy series; no significant changes occur in the partitioning ratios of the other alloying elements. A reduction in secondary creep rate and an increase in rupture time result from increasing the tantalum content and decreasing the carbon level.

  11. Conflict minerals from the Democratic Republic of the Congo: global tantalum processing plants, a critical part of the tantalum supply chain

    USGS Publications Warehouse

    Papp, John F.

    2014-01-01

    Post-beneficiation processing plants (generally called smelters and refineries) for 3TG mineral ores and concentrates were identified by company and industry association representatives as being the link in the 3TG mineral supply chain through which these minerals can be traced to their source of origin (mine). The determination of the source of origin is critical to the development of a complete and transparent conflict-free mineral supply chain. Tungsten processing plants were the subject of the first fact sheet in this series published by USGS NMIC in August 2014. Background information about historical conditions and multinational stakeholders’ voluntary due diligence guidance for minerals from conflict-affected and high-risk areas is presented in the tungsten fact sheet. This fact sheet, the second in a series about 3TG minerals, focuses on the tantalum supply chain by listing selected processors that produced tantalum materials commercially worldwide during 2013–14. It does not provide any information regarding the sources of material processed in these facilities.

  12. A novel tantalum-based sol-gel packed microextraction syringe for highly specific enrichment of phosphopeptides in MALDI-MS applications.

    PubMed

    Çelikbıçak, Ömür; Atakay, Mehmet; Güler, Ülkü; Salih, Bekir

    2013-08-07

    A new tantalum-based sol-gel material was synthesized using a unique sol-gel synthesis pathway by PEG incorporation into the sol-gel structure without performing a calcination step. This improved its chemical and physical properties for the high capacity and selective enrichment of phosphopeptides from protein digests in complex biological media. The specificity of the tantalum-based sol-gel material for phosphopeptides was evaluated and compared with tantalum(V) oxide (Ta2O5) in different phosphopeptide enrichment applications. The tantalum-based sol-gel and tantalum(V) oxide were characterized in detail using FT-IR spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM), and also using a surface area and pore size analyzer. In the characterization studies, the surface morphology, pore volume, crystallinity of the materials and PEG incorporation into the sol-gel structure to produce a more hydrophilic material were successfully demonstrated. The X-ray diffractograms of the two different materials were compared and it was noted that the broad signals of the tantalum-based sol-gel clearly represented the amorphous structure of the sol-gel material, which was more likely to create enough surface area and to provide more accessible tantalum atoms for phosphopeptides to be easily adsorbed when compared with the neat and more crystalline structure of Ta2O5. Therefore, the phosphopeptide enrichment performance of the tantalum-based sol-gels was found to be remarkably higher than the more crystalline Ta2O5 in our studies. Phosphopeptides at femtomole levels could be selectively enriched using the tantalum-based sol-gel and detected with a higher signal-to-noise ratio by matrix-assisted laser desorption/ionization-mass spectrometer (MALDI-MS). Moreover, phosphopeptides in a tryptic digest of non-fat bovine milk as a complex real-world biological sample were retained with higher yield using a tantalum-based sol-gel. Additionally, the sol-gel material

  13. Effect of Temperature Cycling and Exposure to Extreme Temperatures on Reliability of Solid Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2007-01-01

    In this work, results of multiple temperature cycling (TC) (up to 1,000 cycles) of different types of solid tantalum capacitors are analyzed and reported. Deformation of chip tantalum during temperature variations simulating reflow soldering conditions was measured to evaluate the possibility of the pop-corning effect in the parts. To simulate the effect of short-time exposures to solder reflow temperatures on the reliability of tantalum capacitors, several part types were subjected to multiple cycles (up to 100) between room temperature and 240 C with periodical measurements of electrical characteristics of the parts. Mechanisms of degradation caused by temperature cycling and exposure to high temperatures, and the requirements of MIL-PRF-55365 for assessment of the resistance of the parts to soldering heat are discussed.

  14. CONTRIBUTION TO THE GEOCHEMISTRY OF TANTALUM AND NIOBIUM IN THE HYDROTHERMAL-PNEUMATHOLYTIC PROCESS (in Russian)

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

    Beus, A.A.; Sitnin, A.A.

    1961-01-01

    S>Data obtained as a result of geochemical investigations show that tantalum and niobium are typical elements of high-temperature postmagmatic processes (early albitization, greysening) connected with granites. The separation of tantalum and niobium in the hydrothermal-pneumatholytic process (greysening stage), which leads to the concentration of tantalum in albitized and greysenized granites (40 to 100 times compared to the average content in granites) is connected with the different mobility and stability of their acido- complex compounds (in particular fluor- and oxyfluorcomplexes), the existence of which in greysening solutions is suggested. A natural analogy in the behavior of both elements in the processesmore » of postmagmatic metasomatose in granites and granitic pegmatites is suggested. (tr-auth)« less

  15. Early/Late Heterobimetallic Tantalum/Rhodium Species Assembled Through a Novel Bifunctional NHC-OH Ligand.

    PubMed

    Srivastava, Ravi; Moneuse, Raphaël; Petit, Julien; Pavard, Paul-Alexis; Dardun, Vincent; Rivat, Madleen; Schiltz, Pauline; Solari, Marius; Jeanneau, Erwann; Veyre, Laurent; Thieuleux, Chloé; Quadrelli, Elsje Alessandra; Camp, Clément

    2018-03-20

    The straightforward synthesis of a new unsymmetrical hydroxy-tethered N-heterocyclic carbene (NHC) ligand, HL, is presented. The free ligand exhibits an unusual OH-carbene hydrogen-bonding interaction. This OH-carbene motif was used to yield 1) the first tantalum complex displaying both a Fischer- and Schrock-type carbene ligand and 2) a unique NHC-based early/late heterobimetallic complex. More specifically, the protonolysis chemistry between the ligand's hydroxy group and imido-alkyl or alkylidene-alkyl tantalum precursor complexes yielded the rare monometallic tantalum-NHC complexes [Ta(XtBu)(L)(CH 2 tBu) 2 ] (X=N, CH), in which the alkoxy-carbene ligand acts as a chelate. In contrast, HL only binds to rhodium through the NHC unit in [Rh(HL)(cod)Cl] (cod=cycloocta-1,5-diene), the hydroxy pendant arm remaining unbound. This bifunctional ligand scaffold successfully promoted the assembly of rhodium/tantalum heterobimetallic complexes upon either 1) the insertion of [Rh(cod)Cl] 2 into the Ta-NHC bond in [Ta(NtBu)(L)(CH 2 tBu) 2 ] or 2) protonolysis between the free hydroxy group in [Rh(HL)(cod)Cl] and one alkyl group in [Ta(NtBu)(CH 2 tBu) 3 ]. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Hot pressing of nanocrystalline tantalum using high frequency induction heating and pulse plasma sintering

    NASA Astrophysics Data System (ADS)

    Jakubowicz, J.; Adamek, G.; Sopata, M.; Koper, J. K.; Siwak, P.

    2017-12-01

    The paper presents the results of nanocrystalline powder tantalum consolidation using hot pressing. The authors used two different heating techniques during hot pressing: high-frequency induction heating (HFIH) and pulse plasma sintering (PPS). A comparison of the structure, microstructure, mechanical properties and corrosion resistance of the bulk nanocrystalline tantalum obtained in both techniques was performed. The nanocrystalline powder was made to start from the microcrystalline one using the high-energy ball milling process. The nanocrystalline powder was hot-pressed at 1000 °C, whereas, for comparison, the microcrystalline powder was hot pressed up to 1500 °C for proper consolidation. The authors found that during hot pressing, the powder partially reacts with the graphite die covered by boron nitride, which facilitated punches and powder displacement in the die during densification. Tantalum carbide and boride in the nanocrystalline material was found, which can improve the mechanical properties. The hardness of the HFIH and PPS nanocrystalline tantalum was as high as 625 and 615 HV, respectively. The microstructure was more uniform in the PPS nanomaterial. The corrosion resistance in both cases deteriorated, in comparison to the microcrystalline material, while the PPS material corrosion resistance was slightly better than that of the HFIH one.

  17. Comparison of the effect of NaOH and TE buffer on 25 to 100 eV electron induced damage to ΦX174 dsDNA

    NASA Astrophysics Data System (ADS)

    Kumar, S. V. K.; Murali, Megha; Kushwaha, Preksha

    2015-09-01

    In this article we report the usage of (1) ΦX174 dsDNA as a model for electron - DNA interaction studies, (2) semiconductor grade 100 silicon wafer, gold on chrome on glass, and tantalum foil substrates, drying process and effect of temperature, on the DNA film formation and its stability, (3) stability of DNA films formed from DNA suspended in nano pure water and with additives like NaOH and TE buffer, and (4) effect of 0.001 mM NaOH and TE buffer (at pH 7.5) additives on DNA damage induced by 25 to 100 eV electrons. The results show that when tantalum foils are used as a substrate, it results in films, which have DNA distributed fairly uniformly and is also stable against strand breaks affected due to the stress of the drying. Electron irradiation of DNA suspended in TE buffer result in the formation of only relaxed form. When the DNA is suspended in 0.001 mM NaOH and irradiated similarly, linear form and cross links are also formed, in addition to relaxed form. This could be likely due to the secondary electrons interacting with Na+ ions that are bound to the DNA causing a second strand break in the opposite strand. Contribution to the Topical Issue "COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy", edited by Andrey Solov'yov, Nigel Mason, Gustavo García, Eugene Surdutovich.

  18. The effect of tantalum on the structure/properties of two polycrystalline nickel-base superalloys: B-1900 + Hf MAR-M247. M.S. Thesis, Final Report

    NASA Technical Reports Server (NTRS)

    Janowski, G. M.

    1985-01-01

    The microstructure, phase compositions, and phase fractions were studied in conventionally cast B-1900 + Hf and both conventionally cast and directionally solidified MAR-M247 as a function of tantalum concentration. The hot tensile and creep rupture properties of the solutionized and aged MAR-M247-type alloys were also determined as a function of tantalum level. The effects of tantalum on the microstructure and phase compositions of B-1900 + Hf and MAR-M247 (conventionally cast and directionally solidified) were found to be very similar. The addition of tantalum to the as cast and heat treated alloys was shown to cause the partial replacement of the Hf in the MC carbides by Ta, although the degree of replacement was decreased by the solutionizing and aging heat treatment. The gamma prime and minor phase fractions (primarily MC type carbides) both increased approximately linearly with tantalum concentration. The gamma prime phase compositions were relatively insensitive to tantalum variations with the exception of the tantalum and/or hafnium levels. Bulk tantalum additions increased the tantalum, chromium, and cobalt levels of the gamma phase in both alloy series. The increase in the concentrations of the latter two elements in the gamma phase was a result of the decrease in the gamma phase fraction with increasing bulk tantalum concentration and constant gamma/gamma prime partitioning ratio. Tantalum additions increased the yield stress and ultimate tensile strength of the directionally solidified MAR-M247 type alloys and had no significant effect on ductility.

  19. Primary human osteoblasts grow into porous tantalum and maintain an osteoblastic phenotype.

    PubMed

    Welldon, Katie J; Atkins, Gerald J; Howie, Donald W; Findlay, David M

    2008-03-01

    Porous tantalum (Ta) has found application in orthopedics, although the interaction of human osteoblasts (HOB) with this material has not been reported. The aim of this study was to investigate the interaction of primary HOB with porous tantalum, using 5-mm thick discs of porous tantalum. Comparison was made with discs of solid tantalum and tissue culture plastic. Confocal microscopy was used to investigate the attachment and growth of cells on porous Ta, and showed that HOB attached successfully to the metal "trabeculae," underwent extensive cell division, and penetrated into the Ta pores. The maturation of HOB on porous Ta was determined in terms of cell expression of the osteoblast phenotypic markers, STRO-1, and alkaline phosphatase. Despite some donor-dependent variation in STRO-1/AlkPhos expression, growth of cells grown on porous Ta either promoted, or did not impede, the maturation of HOB. In addition, the expression of key osteoblastic genes was investigated after 14 days of culture. The relative levels of mRNA encoding osteocalcin, osteopontin and receptor activator of NFkappaB ligand (RANKL) was not different between porous or solid Ta or plastic, although these genes were expressed differently by cells of different donors. However, bone sialoprotein and type I collagen mRNA species showed a decreased expression on porous Ta compared with expression on plastic. No substrate-dependent differences were seen in the extent of in vitro mineralization by HOB. These results indicate that porous Ta is a good substrate for the attachment, growth, and differentiated function of HOB. (c) 2007 Wiley Periodicals, Inc.

  20. Leakage Currents and Gas Generation in Advanced Wet Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2015-01-01

    Currently, military grade, established reliability wet tantalum capacitors are among the most reliable parts used for space applications. This has been achieved over the years by extensive testing and improvements in design and materials. However, a rapid insertion of new types of advanced, high volumetric efficiency capacitors in space systems without proper testing and analysis of degradation mechanisms might increase risks of failures. The specifics of leakage currents in wet electrolytic capacitors is that the conduction process is associated with electrolysis of electrolyte and gas generation resulting in building up of internal gas pressure in the parts. The risk associated with excessive leakage currents and increased pressure is greater for high value advanced wet tantalum capacitors, but it has not been properly evaluated yet. In this work, in Part I, leakages currents in various types of tantalum capacitors have been analyzed in a wide range of voltages, temperatures, and time under bias. Gas generation and the level of internal pressure have been calculated in Part II for different case sizes and different hermeticity leak rates to assess maximal allowable leakage currents. Effects related to electrolyte penetration to the glass seal area have been studied and the possibility of failures analyzed in Part III. Recommendations for screening and qualification to reduce risks of failures have been suggested.

  1. 49 CFR 173.174 - Refrigerating machines.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... of a flammable liquid for its operation in a strong, tight receptacle is excepted from labeling... 49 Transportation 2 2014-10-01 2014-10-01 false Refrigerating machines. 173.174 Section 173.174 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY...

  2. 49 CFR 173.174 - Refrigerating machines.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... of a flammable liquid for its operation in a strong, tight receptacle is excepted from labeling... 49 Transportation 2 2010-10-01 2010-10-01 false Refrigerating machines. 173.174 Section 173.174 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY...

  3. 49 CFR 173.174 - Refrigerating machines.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... of a flammable liquid for its operation in a strong, tight receptacle is excepted from labeling... 49 Transportation 2 2011-10-01 2011-10-01 false Refrigerating machines. 173.174 Section 173.174 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY...

  4. 49 CFR 173.174 - Refrigerating machines.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... of a flammable liquid for its operation in a strong, tight receptacle is excepted from labeling... 49 Transportation 2 2013-10-01 2013-10-01 false Refrigerating machines. 173.174 Section 173.174 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY...

  5. 49 CFR 173.174 - Refrigerating machines.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... of a flammable liquid for its operation in a strong, tight receptacle is excepted from labeling... 49 Transportation 2 2012-10-01 2012-10-01 false Refrigerating machines. 173.174 Section 173.174 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY...

  6. 20 CFR 655.174 - Public disclosure.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 3 2013-04-01 2013-04-01 false Public disclosure. 655.174 Section 655.174 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR TEMPORARY EMPLOYMENT OF... temporary agricultural labor certifications. The database will include such information as the number of...

  7. 20 CFR 655.174 - Public disclosure.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 3 2014-04-01 2014-04-01 false Public disclosure. 655.174 Section 655.174 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR TEMPORARY EMPLOYMENT OF... temporary agricultural labor certifications. The database will include such information as the number of...

  8. 20 CFR 655.174 - Public disclosure.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 3 2011-04-01 2011-04-01 false Public disclosure. 655.174 Section 655.174 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR TEMPORARY EMPLOYMENT OF... temporary agricultural labor certifications. The database will include such information as the number of...

  9. 20 CFR 655.174 - Public disclosure.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Public disclosure. 655.174 Section 655.174 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR TEMPORARY EMPLOYMENT OF... temporary agricultural labor certifications. The database will include such information as the number of...

  10. 20 CFR 655.174 - Public disclosure.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 3 2012-04-01 2012-04-01 false Public disclosure. 655.174 Section 655.174 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR TEMPORARY EMPLOYMENT OF... temporary agricultural labor certifications. The database will include such information as the number of...

  11. 49 CFR 174.14 - Movements to be expedited.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Movements to be expedited. 174.14 Section 174.14 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY... Requirements § 174.14 Movements to be expedited. (a) A carrier must forward each shipment of hazardous...

  12. 13 CFR 120.174 - Earthquake hazards.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 13 Business Credit and Assistance 1 2013-01-01 2013-01-01 false Earthquake hazards. 120.174... Applying to All Business Loans Requirements Imposed Under Other Laws and Orders § 120.174 Earthquake..., the construction must conform with the “National Earthquake Hazards Reduction Program (“NEHRP...

  13. 13 CFR 120.174 - Earthquake hazards.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 13 Business Credit and Assistance 1 2014-01-01 2014-01-01 false Earthquake hazards. 120.174... Applying to All Business Loans Requirements Imposed Under Other Laws and Orders § 120.174 Earthquake..., the construction must conform with the “National Earthquake Hazards Reduction Program (“NEHRP...

  14. 13 CFR 120.174 - Earthquake hazards.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 13 Business Credit and Assistance 1 2012-01-01 2012-01-01 false Earthquake hazards. 120.174... Applying to All Business Loans Requirements Imposed Under Other Laws and Orders § 120.174 Earthquake..., the construction must conform with the “National Earthquake Hazards Reduction Program (“NEHRP...

  15. 13 CFR 120.174 - Earthquake hazards.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 13 Business Credit and Assistance 1 2011-01-01 2011-01-01 false Earthquake hazards. 120.174... Applying to All Business Loans Requirements Imposed Under Other Laws and Orders § 120.174 Earthquake..., the construction must conform with the “National Earthquake Hazards Reduction Program (“NEHRP...

  16. Effect of Mechanical Stresses on Characteristics of Chip Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander A.

    2007-01-01

    The effect of compressive mechanical stresses on chip solid tantalum capacitors is investigated by monitoring characteristics of different part types under axial and hydrostatic stresses. Depending on part types, an exponential increase of leakage currents was observed when stresses exceeded 10 MPa to 40 MPa. For the first time, reversible variations of leakage currents (up to two orders of magnitude) with stress have been demonstrated. Mechanical stresses did not cause significant changes of AC characteristics of the capacitors, whereas breakdown voltages measured during the surge current testing decreased substantially indicating an increased probability of failures of stressed capacitors in low impedance applications. Variations of leakage currents are explained by a combination of two mechanisms: stress-induced scintillations and stress-induced generation of electron traps in the tantalum pentoxide dielectric.

  17. Heat of combustion of tantalum-tungsten oxide thermite composites

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

    Cervantes, Octavio G.; Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616; Kuntz, Joshua D.

    2010-12-15

    The heat of combustion of two distinctly synthesized stoichiometric tantalum-tungsten oxide energetic composites was investigated by bomb calorimetry. One composite was synthesized using a sol-gel (SG) derived method in which micrometric-scale tantalum is immobilized in a tungsten oxide three-dimensional nanostructured network structure. The second energetic composite was made from the mixing of micrometric-scale tantalum and commercially available (CA) nanometric tungsten oxide powders. The energetic composites were consolidated using the spark plasma sintering (SPS) technique under a 300 MPa pressure and at temperatures of 25, 400, and 500 C. For samples consolidated at 25 C, the density of the CA compositemore » is 61.65 {+-} 1.07% in comparison to 56.41 {+-} 1.19% for the SG derived composite. In contrast, the resulting densities of the SG composite are higher than the CA composite for samples consolidated at 400 and 500 C. The theoretical maximum density for the SG composite consolidated to 400 and 500 C are 81.30 {+-} 0.58% and 84.42 {+-} 0.62%, respectively. The theoretical maximum density of the CA composite consolidated to 400 and 500 C are 74.54 {+-} 0.80% and 77.90 {+-} 0.79%, respectively. X-ray diffraction analyses showed an increase of pre-reaction of the constituents with an increase in the consolidation temperature. The increase in pre-reaction results in lower stored energy content for samples consolidated to 400 and 500 C in comparison to samples consolidated at 25 C. (author)« less

  18. 49 CFR 174.20 - Local or carrier restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Local or carrier restrictions. 174.20 Section 174... General Requirements § 174.20 Local or carrier restrictions. (a) When local conditions make the acceptance, transportation, or delivery of hazardous materials unusually hazardous, local restrictions may be imposed by the...

  19. 49 CFR 174.20 - Local or carrier restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Local or carrier restrictions. 174.20 Section 174... General Requirements § 174.20 Local or carrier restrictions. (a) When local conditions make the acceptance, transportation, or delivery of hazardous materials unusually hazardous, local restrictions may be imposed by the...

  20. Use of a Tantalum Liner to Reduce Bore Erosion and Increase Muzzle Velocity in Two-Stage Light Gas Guns

    NASA Technical Reports Server (NTRS)

    Bogdanoff, David W.

    2015-01-01

    Muzzle velocities and gun erosion predicted by earlier numerical simulations of two stage light gas guns with steel gun tubes were in good agreement with experimental values. In a subsequent study, simulations of high performance shots were repeated with rhenium (Re) gun tubes. Large increases in muzzle velocity (2 - 4 km/sec) were predicted for Re tubes. In addition, the hydrogen-produced gun tube erosion was, in general, predicted to be zero with Re tubes. Tantalum (Ta) has some mechanical properties superior to those of Re. Tantalum has a lower modulus of elasticity than Re for better force transmission from the refractory metal liner to an underlying thick wall steel tube. Tantalum also has greater ductility than Re for better survivability during severe stress/strain cycles. Also, tantalum has been used as a coating or liner in military powder guns with encouraging results. Tantalum has, however, somewhat inferior thermal properties to those of rhenium, with a lower melting point and lower density and thermal conductivity. The present study was undertaken to see to what degree the muzzle velocity gains of rhenium gun tubes (over steel tubes) could be achieved with tantalum gun tubes. Nine high performance shots were modeled with a new version of our CFD gun code for steel, rhenium and tantalum gun tubes. For all except the highest velocity shot, the results with Ta tubes were nearly identical with those for Re tubes. Even for the highest velocity shot, the muzzle velocity gain over a steel tube using Ta was 82% of the gain obtained using Re. Thus, the somewhat inferior thermal properties of Ta (when compared to those of Re) translate into only very slightly poorer overall muzzle velocity performance. When this fact is combined with the superior mechanical properties of Ta and the encouraging performance of Ta liners/coatings in military powder guns, tantalum is to be preferred over Re as a liner/coating material for two stage light gas guns to increase muzzle

  1. Evaluation of Ferrite Chip Beads as Surge Current Limiters in Circuits with Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2014-01-01

    Limiting resistors are currently required to be connected in series with tantalum capacitors to reduce the risk of surge current failures. However, application of limiting resistors decreases substantially the efficiency of the power supply systems. An ideal surge current limiting device should have a negligible resistance for DC currents and high resistance at frequencies corresponding to transients in tantalum capacitors. This work evaluates the possibility of using chip ferrite beads (FB) as such devices. Twelve types of small size FBs from three manufacturers were used to evaluate their robustness under soldering stresses and at high surge current spikes associated with transients in tantalum capacitors. Results show that FBs are capable to withstand current pulses that are substantially greater than the specified current limits. However, due to a sharp decrease of impedance with current, FBs do not reduce surge currents to the required level that can be achieved with regular resistors.

  2. Tantalum-containing catalyst useful for producing alcohols from synthesis gas

    DOEpatents

    Kinkade, Nancy E.

    1991-01-01

    A catalyst useful for selectively converting a mixture of carbon monoxide and hydrogen to a mixture of lower alkanols consisting essentially of a mixture of molybdenum sulfide, an alkali metal compound and a tantalum compound.

  3. Tantalum-containing catalyst useful for producing alcohols from synthesis gas

    DOEpatents

    Kinkade, Nancy E.

    1992-01-01

    A catalyst useful for selectively converting a mixture of carbon monoxide and hydrogen to a mixture of lower alkanols consisting essentially of a mixture of molybdenum sulfide, an alkali metal compound and a tantalum compound.

  4. 19 CFR 174.11 - Matters subject to protest.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Matters subject to protest. 174.11 Section 174.11 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY (CONTINUED) PROTESTS Protests § 174.11 Matters subject to protest. The following decisions of the...

  5. 19 CFR 174.11 - Matters subject to protest.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 2 2013-04-01 2013-04-01 false Matters subject to protest. 174.11 Section 174.11... TREASURY (CONTINUED) PROTESTS Protests § 174.11 Matters subject to protest. The following decisions of CBP... administrative decisions involving the following subject matters are subject to protest: (1) The appraised value...

  6. 19 CFR 174.11 - Matters subject to protest.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 2 2014-04-01 2014-04-01 false Matters subject to protest. 174.11 Section 174.11... TREASURY (CONTINUED) PROTESTS Protests § 174.11 Matters subject to protest. The following decisions of CBP... administrative decisions involving the following subject matters are subject to protest: (1) The appraised value...

  7. 19 CFR 174.11 - Matters subject to protest.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 2 2011-04-01 2011-04-01 false Matters subject to protest. 174.11 Section 174.11... TREASURY (CONTINUED) PROTESTS Protests § 174.11 Matters subject to protest. The following decisions of CBP... administrative decisions involving the following subject matters are subject to protest: (1) The appraised value...

  8. 19 CFR 174.11 - Matters subject to protest.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 2 2012-04-01 2012-04-01 false Matters subject to protest. 174.11 Section 174.11... TREASURY (CONTINUED) PROTESTS Protests § 174.11 Matters subject to protest. The following decisions of CBP... administrative decisions involving the following subject matters are subject to protest: (1) The appraised value...

  9. 22 CFR 17.4 - Equity and good conscience.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Equity and good conscience. 17.4 Section 17.4... PENSION SYSTEM (FSPS) § 17.4 Equity and good conscience. (a) Defined. Recovery is against equity and good... a valuable right or changed positions for the worse; or (3) Recovery could be unconscionable under...

  10. 34 CFR 668.174 - Past performance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 34 Education 3 2011-07-01 2011-07-01 false Past performance. 668.174 Section 668.174 Education... performance. (a) Past performance of an institution. An institution is not financially responsible if the... pursuant to subpart G or H of this part. (b) Past performance of persons affiliated with an institution. (1...

  11. 34 CFR 668.174 - Past performance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 34 Education 3 2013-07-01 2013-07-01 false Past performance. 668.174 Section 668.174 Education... performance. (a) Past performance of an institution. An institution is not financially responsible if the... pursuant to subpart G or H of this part. (b) Past performance of persons affiliated with an institution. (1...

  12. 34 CFR 668.174 - Past performance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 3 2010-07-01 2010-07-01 false Past performance. 668.174 Section 668.174 Education... performance. (a) Past performance of an institution. An institution is not financially responsible if the... pursuant to subpart G or H of this part. (b) Past performance of persons affiliated with an institution. (1...

  13. 34 CFR 668.174 - Past performance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 34 Education 3 2012-07-01 2012-07-01 false Past performance. 668.174 Section 668.174 Education... performance. (a) Past performance of an institution. An institution is not financially responsible if the... pursuant to subpart G or H of this part. (b) Past performance of persons affiliated with an institution. (1...

  14. 34 CFR 668.174 - Past performance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 34 Education 3 2014-07-01 2014-07-01 false Past performance. 668.174 Section 668.174 Education... performance. (a) Past performance of an institution. An institution is not financially responsible if the... pursuant to subpart G or H of this part. (b) Past performance of persons affiliated with an institution. (1...

  15. Inferring Strength of Tantalum from Hydrodynamic Instability Recovery Experiments

    NASA Astrophysics Data System (ADS)

    Sternberger, Z.; Maddox, B.; Opachich, Y.; Wehrenberg, C.; Kraus, R.; Remington, B.; Randall, G.; Farrell, M.; Ravichandran, G.

    2018-05-01

    Hydrodynamic instability experiments allow access to material properties at extreme conditions, where strain rates exceed 105 s-1 and pressures reach 100 GPa. Current hydrodynamic instability experimental methods require in-flight radiography to image the instability growth at high pressure and high strain rate, limiting the facilities where these experiments can be performed. An alternate approach, recovering the sample after loading, allows measurement of the instability growth with profilometry. Tantalum samples were manufactured with different 2D and 3D initial perturbation patterns and dynamically compressed by a blast wave generated by laser ablation. The samples were recovered from peak pressures between 30 and 120 GPa and strain rates on the order of 107 s-1, providing a record of the growth of the perturbations due to hydrodynamic instability. These records are useful validation points for hydrocode simulations using models of material strength at high strain rate. Recovered tantalum samples were analyzed, providing an estimate of the strength of the material at high pressure and strain rate.

  16. 19 CFR 174.23 - Further review of protests.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Further review of protests. 174.23 Section 174.23... TREASURY (CONTINUED) PROTESTS Review and Disposition of Protests § 174.23 Further review of protests. A protesting party may seek further review of a protest in lieu of review by the port director by filing, on...

  17. Upgrading tantalum and niobium oxides content in Bangka tin slag with double leaching

    NASA Astrophysics Data System (ADS)

    Soedarsono, J. W.; Permana, S.; Hutauruk, J. K.; Adhyputra, R.; Rustandi, A.; Maksum, A.; Widana, K. S.; Trinopiawan, K.; Anggraini, M.

    2018-03-01

    Tantalum has become one of the 14 types of critical materials where the level of its availability is assumed as the midterm critical metal. Benefits of the element tantalum in the electronics field increased the deficit balance of supply / demand, as more variations of electronic products developed. The tantalum experts calculated the level of availability until 2020. Base on the previous studies, tin slag is a secondary source of tantalum and niobium. This study uses tin slag from Bangka, Indonesia, abbreviated, Bangka Tin Slag (BTS). BTS was roasted, water quenched and sieved, abbreviated BTS-RQS.BTS was roasted, water quenched and sieved, abbreviated BTS-RQS.BTS-RQS was roasted at a temperature 700□C given sample code BTS-R700QS, while roasted at 800°C given sample code BTS-R800QS.A variable leaching experiment on BTS-R700QS was solvent concentration variable and on BTS-R800QS was time variable. The entire residue was characterized by X-Ray Fluorescence (XRF), and the optimum results are on the BTS-R800QS leaching into 5 M NaOH for 20 min followed by 5M HCl for 50 min, with content of Ta2O5 and Nb2O51.56% and 1.11%, respectively. The result of XRF measurement showed was the increasing of TNO content due to the increasing solvent concentration and time of acid leaching. The discussion of thermodynamics this study used was HSC Chemistry 6 as a supporting data.

  18. 46 CFR 174.065 - Damage stability requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... lowest edge of any opening through which additional flooding could occur if the unit were subjected simultaneously to— (1) Damage causing flooding described in §§ 174.075 through 174.085; and (2) A wind heeling...

  19. 46 CFR 174.065 - Damage stability requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... lowest edge of any opening through which additional flooding could occur if the unit were subjected simultaneously to— (1) Damage causing flooding described in §§ 174.075 through 174.085; and (2) A wind heeling...

  20. 46 CFR 174.065 - Damage stability requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... lowest edge of any opening through which additional flooding could occur if the unit were subjected simultaneously to— (1) Damage causing flooding described in §§ 174.075 through 174.085; and (2) A wind heeling...

  1. 17-4 PH and 15-5 PH

    NASA Technical Reports Server (NTRS)

    Johnson, Howard T.

    1995-01-01

    17-4 PH and 15-5 PH are extremely useful and versatile precipitation-hardening stainless steels. Armco 17-4 PH is well suited for the magnetic particle inspection requirements of Aerospace Material Specification. Armco 15-5 PH and 17-4 PH are produced in billet, plate, bar, and wire. Also, 15-5 PH is able to meet the stringent mechanical properties required in the aerospace and nuclear industries. Both products are easy to heat treat and machine, making them very useful in many applications.

  2. Evaluation of Polymer Hermetically Sealed Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander A.

    2014-01-01

    Polymer cathode tantalum capacitors have lower ESR (equivalent series resistance) compared to other types of tantalum capacitors and for this reason have gained popularity in the electronics design community. Their use allows improved performance of power supply systems along with substantial reduction of size and weight of the components used. However, these parts have poor thermal stability and can degrade in humid environments. Polymer hermetically sealed (PHS) capacitors avoid problems related to environmental degradation of molded case parts and can potentially replace current wet and solid hermetically sealed capacitors. In this work, PHS capacitors manufactured per DLA LAM DWG#13030 are evaluated for space applications. Several lots of capacitors manufactured over period from 2010 to 2014 were tested for the consistency of performance, electrical and thermal characteristics, highly accelerated life testing, and robustness under reverse bias and random vibration conditions. Special attention was given to analysis of leakage currents and the effect of long-term high temperature storage on capacitors in as is condition and after hermeticity loss. The results show that PHS capacitors might be especially effective for low-temperature applications or for system requiring a cold start-up. Additional screening and qualification testing have been recommended to assure the necessary quality of capacitors for space projects.

  3. 40 CFR 141.174 - Filtration sampling requirements.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ....174 Section 141.174 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration and Disinfection... water system subject to the requirements of this subpart that provides conventional filtration treatment...

  4. 40 CFR 141.174 - Filtration sampling requirements.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ....174 Section 141.174 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration and Disinfection... water system subject to the requirements of this subpart that provides conventional filtration treatment...

  5. 40 CFR 141.174 - Filtration sampling requirements.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ....174 Section 141.174 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration and Disinfection... water system subject to the requirements of this subpart that provides conventional filtration treatment...

  6. Tantalum-containing catalyst useful for producing alcohols from synthesis gas

    DOEpatents

    Kinkade, N.E.

    1992-04-07

    A catalyst is described which is useful for selectively converting a mixture of carbon monoxide and hydrogen to a mixture of lower alkanols. The catalyst consists essentially of a mixture of molybdenum sulfide, an alkali metal compound and a tantalum compound.

  7. Frequency spectrum of tantalum at temperatures of 293-2300 K

    NASA Astrophysics Data System (ADS)

    Semenov, V. A.; Kozlov, Zh. A.; Krachun, L.; Mateescu, G.; Morozov, V. M.; Oprea, A. I.; Oprea, K.; Puchkov, A. V.

    2010-05-01

    The temperature dependence of the frequency spectrum of tantalum in the temperature range from room temperature to 2300 K has been studied for the first time using inelastic slow-neutron scattering. The inelastic slow-neutron scattering spectra have been measured at different temperatures on a DIN-2PI time-of-flight spectrometer installed at the IBR-2 nuclear reactor (Joint Institute for Nuclear Research, Dubna, Russia) with the use of a TS3000K high-temperature thermostat. From the measured spectra, the frequency spectra of the tantalum crystal lattice have been determined at temperatures of 293, 1584, and 2300 K by the iteration method. As the temperature increases, the frequency spectrum, on the whole, is softened and the specific features manifested themselves at room temperature are smoothed. The variations observed have been explained by the increase in the role of the effects of vibration anharmonism at high temperatures.

  8. Atomization from a tantalum surface in graphite furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Gregoire, D. C.; Chakrabarti, C. L.

    The mechanism of atom formation of U, V, Mo, Ni, Mn, Cu and Mg atomized from pyrolytic graphite and tantalum metal surfaces has been studied. The mechanism of atom formation for U from a graphite tube atomizer is reported for the first time. The peak absorbance for U and Cu is increased by factors of 59.7 and 2.0, respectively, whereas that of V, Mo and Ni is reduced by several orders of magnitude when they are atomized from a tantalum metal surface. The peak absorbance of Mn and Mg is not appreciably affected by the material of the atomization surface. Interaction of Mn and Mg with the graphite surface and formation of their refractory carbides was found to be negligible. Uranium forms a refractory carbide when heated from a graphite surface.

  9. 46 CFR 174.225 - Hull penetrations and shell connections.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Hull penetrations and shell connections. 174.225 Section 174.225 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY... § 174.225 Hull penetrations and shell connections. Each overboard discharge and shell connection except...

  10. 7 CFR 1.74 - Basis for special working relationships.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 1 2013-01-01 2013-01-01 false Basis for special working relationships. 1.74 Section 1.74 Agriculture Office of the Secretary of Agriculture ADMINISTRATIVE REGULATIONS Cooperative Production of Television Films § 1.74 Basis for special working relationships. The Department and its...

  11. 46 CFR 174.225 - Hull penetrations and shell connections.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Hull penetrations and shell connections. 174.225 Section 174.225 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY... § 174.225 Hull penetrations and shell connections. Each overboard discharge and shell connection except...

  12. 47 CFR 17.4 - Antenna structure registration.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Antenna structure registration. 17.4 Section 17... ANTENNA STRUCTURES General Information § 17.4 Antenna structure registration. (a) Effective July 1, 1996, the owner of any proposed or existing antenna structure that requires notice of proposed construction...

  13. 47 CFR 17.4 - Antenna structure registration.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Antenna structure registration. 17.4 Section 17... ANTENNA STRUCTURES General Information § 17.4 Antenna structure registration. (a) Effective July 1, 1996, the owner of any proposed or existing antenna structure that requires notice of proposed construction...

  14. 50 CFR 17.4 - Pre-Act wildlife.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 2 2010-10-01 2010-10-01 false Pre-Act wildlife. 17.4 Section 17.4 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR (CONTINUED) TAKING, POSSESSION, TRANSPORTATION, SALE, PURCHASE, BARTER, EXPORTATION, AND IMPORTATION OF WILDLIFE AND...

  15. 50 CFR 17.4 - Pre-Act wildlife.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 2 2011-10-01 2011-10-01 false Pre-Act wildlife. 17.4 Section 17.4 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR (CONTINUED) TAKING, POSSESSION, TRANSPORTATION, SALE, PURCHASE, BARTER, EXPORTATION, AND IMPORTATION OF WILDLIFE AND...

  16. 50 CFR 17.4 - Pre-Act wildlife.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 2 2013-10-01 2013-10-01 false Pre-Act wildlife. 17.4 Section 17.4 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR (CONTINUED) TAKING, POSSESSION, TRANSPORTATION, SALE, PURCHASE, BARTER, EXPORTATION, AND IMPORTATION OF WILDLIFE AND...

  17. 50 CFR 17.4 - Pre-Act wildlife.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 2 2012-10-01 2012-10-01 false Pre-Act wildlife. 17.4 Section 17.4 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR (CONTINUED) TAKING, POSSESSION, TRANSPORTATION, SALE, PURCHASE, BARTER, EXPORTATION, AND IMPORTATION OF WILDLIFE AND...

  18. 50 CFR 17.4 - Pre-Act wildlife.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 2 2014-10-01 2014-10-01 false Pre-Act wildlife. 17.4 Section 17.4 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR (CONTINUED) TAKING, POSSESSION, TRANSPORTATION, SALE, PURCHASE, BARTER, EXPORTATION, AND IMPORTATION OF WILDLIFE AND...

  19. 2014 NEPP Tasks Update for Ceramic and Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander A.

    2014-01-01

    Presentation describes recent development in research on MnO2, wet, and polymer tantalum capacitors. Low-voltage failures in multilayer ceramic capacitors and techniques to reveal precious metal electrode (PME) and base metal electrode (BME) capacitors with cracks are discussed. A voltage breakdown technique is suggested to select high quality low-voltage BME ceramic capacitors.

  20. Alkyl group effects on CO insertion into coordinatively unsaturated early-transition-metal alkyls. Preparations and the first structural characterizations of tantalum enolate-O and tantalum. eta. sup 2 -acyl complexes

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

    Meyer, T.Y.; Garner, L.R.; Baenziger, N.C.

    1990-10-03

    Low-pressure carbonylation of the mono(peralkylcyclopentadienyl)tantalum(V) alkyls ({eta}-C{sub 5}Me{sub 4}R)TaR{prime}Cl{sub 3} (R = Me, Et; R{prime} = CH{sub 2}C{sub 6}H{sub 4}-p-Me, CH{sub 2}CMe{sub 3}) yields either the O-bound enolate or the {eta}{sup 2}-acyl as shown by ir/NMR spectroscopy and x-ray diffractometry. The p-tolyl enolate ({eta}-C{sub 5}Me{sub 5})Ta(OCH{double bond}CHC{sub 6}H{sub 4}-p-Me)Cl{sub 3}, derived directly from carbonylation of the tantalum 4-methylbenzyl precursor, is shown to possess a cis configuration in solution and in the solid state. Key structural features from a single-crystal x-ray diffraction study of the tetrahydrofuran-ligated enolate complex are reported. The mechanism of formation of the enolate from carbonylation of themore » 4-methylbenzyl complex is discussed. The previously reported acyl ({eta}-C{sub 5}Me{sub 4}R)Ta(C(O)CH{sub 2}CMe{sub 3})Cl{sub 3} has been reexamined and found to possess a symmetric, strongly distorted {eta}{sup 2}-acyl coordination by solution {sup 1}H NMR spectroscopy and solid-state x-ray diffractometry. The molecular structures of ({eta}-C{sub 5}Me{sub 5})Ta(OCH{double bond}CHC{sub 6}H{sub 4}-p-Me)Cl{sub 3} and ({eta}-C{sub 5}Me{sub 5})Ta(C(O)CH{sub 2}CMe{sub 3})Cl{sub 3}, which are reported here, are the first structural determinations of a tantalum enolate and of a tantalum {eta}{sup 2}-acyl. 41 refs., 2 figs., 8 tabs.« less

  1. 46 CFR 174.085 - Flooding on column stabilized units.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Flooding on column stabilized units. 174.085 Section 174... Units § 174.085 Flooding on column stabilized units. (a) Watertight compartments that are outboard of... of the unit, must be assumed to be subject to flooding as follows: (1) When a column is subdivided...

  2. 46 CFR 174.085 - Flooding on column stabilized units.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Flooding on column stabilized units. 174.085 Section 174... Units § 174.085 Flooding on column stabilized units. (a) Watertight compartments that are outboard of... of the unit, must be assumed to be subject to flooding as follows: (1) When a column is subdivided...

  3. 19 CFR 174.21 - Time for review of protests.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Time for review of protests. 174.21 Section 174.21... TREASURY (CONTINUED) PROTESTS Review and Disposition of Protests § 174.21 Time for review of protests. (a.... Any protest filed pursuant to this paragraph shall clearly so state on its face. Any protest filed...

  4. Study of surge current effects on solid tantalum capacitors

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Results are presented of a 2,000 hour cycled life test program conducted to determine the effect of short term surge current screening on approximately 47 micron f/volt solid tantalum capacitors. The format provides average values and standard deviations of the parameters, capacitance, dissipation factor, and equivalent series resistance at 120 Hz, 1KHz, abd 40 KHz.

  5. 46 CFR 174.075 - Compartments assumed flooded: general.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Units § 174.075 Compartments assumed flooded: general. The individual flooding of each of the... § 174.065 (a). Simultaneous flooding of more than one compartment must be assumed only when indicated in...

  6. 46 CFR 174.075 - Compartments assumed flooded: general.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Units § 174.075 Compartments assumed flooded: general. The individual flooding of each of the... § 174.065 (a). Simultaneous flooding of more than one compartment must be assumed only when indicated in...

  7. 46 CFR 174.075 - Compartments assumed flooded: general.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Units § 174.075 Compartments assumed flooded: general. The individual flooding of each of the... § 174.065 (a). Simultaneous flooding of more than one compartment must be assumed only when indicated in...

  8. Diffusion-Cooled Tantalum Hot-Electron Bolometer Mixers

    NASA Technical Reports Server (NTRS)

    Skalare, Anders; McGrath, William; Bumble, Bruce; LeDuc, Henry

    2004-01-01

    A batch of experimental diffusion-cooled hot-electron bolometers (HEBs), suitable for use as mixers having input frequencies in the terahertz range and output frequencies up to about a gigahertz, exploit the superconducting/normal-conducting transition in a thin strip of tantalum. The design and operation of these HEB mixers are based on mostly the same principles as those of a prior HEB mixer that exploited the superconducting/normal- conducting transition in a thin strip of niobium and that was described elsewhere.

  9. Electron-ion temperature equilibration in warm dense tantalum

    DOE PAGES

    Doppner, T; LePape, S.; Ma, T.; ...

    2014-11-05

    We present measurements of electron-ion temperature equilibration in proton-heated tantalum, under warm dense matter conditions. Our results agree with theoretical predictions for metals calculated using input data from ab initio simulations. Furthermore, the fast relaxation observed in the experiment contrasts with much longer equilibration times found in proton heated carbon, indicating that the energy flow pathways in warm dense matter are far from being fully understood.

  10. Response and representation of ductile damage under varying shock loading conditions in tantalum

    DOE PAGES

    Bronkhorst, C. A.; Gray, III, G. T.; Addessio, F. L.; ...

    2016-02-25

    The response of polycrystalline metals, which possess adequate mechanisms for plastic deformation under extreme loading conditions, is often accompanied by the formation of pores within the structure of the material. This large deformation process is broadly identified as progressive with nucleation, growth, coalescence, and failure the physical path taken over very short periods of time. These are well known to be complex processes strongly influenced by microstructure, loading path, and the loading profile, which remains a significant challenge to represent and predict numerically. In the current study, the influence of loading path on the damage evolution in high-purity tantalum ismore » presented. Tantalum samples were shock loaded to three different peak shock stresses using both symmetric impact, and two different composite flyer plate configurations such that upon unloading the three samples displayed nearly identical “pull-back” signals as measured via rear-surface velocimetry. While the “pull-back” signals observed were found to be similar in magnitude, the sample loaded to the highest peak stress nucleated a connected field of ductile fracture which resulted in complete separation, while the two lower peak stresses resulted in incipient damage. The damage evolution in the “soft” recovered tantalum samples was quantified using optical metallography, electron-back-scatter diffraction, and tomography. These experiments are examined numerically through the use of a model for shock-induced porosity evolution during damage. The model is shown to describe the response of the tantalum reasonably well under strongly loaded conditions but less well in the nucleation dominated regime. As a result, numerical results are also presented as a function of computational mesh density and discussed in the context of improved representation of the influence of material structure upon macro-scale models of ductile damage.« less

  11. The structure, bond strength and apatite-inducing ability of micro-arc oxidized tantalum and their response to annealing

    NASA Astrophysics Data System (ADS)

    Wang, Cuicui; Wang, Feng; Han, Yong

    2016-01-01

    In this study, the tantalum oxide coatings were formed on pure tantalum (Ta) by micro-arc oxidation (MAO) in electrolytic solutions of calcium acetate and β-glycerophosphate disodium, and the effect of the applied voltage on the microstructure and bond strength of the MAO coatings was systematically investigated. The effect of annealing treatment on the microstructure, bond strength and apatite-inducing ability of the MAO coatings formed at 350 and 450 V was also studied. The study revealed that during the preparation of tantalum oxide coatings on Ta substrate by MAO, the applied voltage considerably affected the phase components, morphologies and bond strength of the coatings, but had little effect on surface chemical species. After annealing treatment, newly formed CaTa4O11 phase mainly contributed to the much more stronger apatite-inducing ability of the annealed tantalum oxide coatings than those that were not annealed. The better apatite-inducing ability of the MAO coatings formed at 450 V compared to those formed at 350 V was attributed to the less amorphous phase and more crystalline phase as well as more Ca and P contained in the MAO coatings with increasing the applied voltage.

  12. Design, Development, manufacture and qualification of wet-slug all-tantalum capacitors

    NASA Technical Reports Server (NTRS)

    Maher, R. H.

    1977-01-01

    Specifications and qualification tests data are presented for over eleven hundred T3 case all-tantalum capacitors encompassing four ratings. The finalized product has all the advantages of the silver cased wet and is capable of withstanding some reverse potential ac ripple current.

  13. Physics of Shock Compression and Release: NEMD Simulations of Tantalum and Silicon

    NASA Astrophysics Data System (ADS)

    Hahn, Eric; Meyers, Marc; Zhao, Shiteng; Remington, Bruce; Bringa, Eduardo; Germann, Tim; Ravelo, Ramon; Hammerberg, James

    2015-06-01

    Shock compression and release allow us to evaluate physical deformation and damage mechanisms occurring in extreme environments. SPaSM and LAMMPS molecular dynamics codes were employed to simulate single and polycrystalline tantalum and silicon at strain rates above 108 s-1. Visualization and analysis was accomplished using OVITO, Crystal Analysis Tool, and a redesigned orientation imaging function implemented into SPaSM. A comparison between interatomic potentials for both Si and Ta (as pertaining to shock conditions) is conducted and the influence on phase transformation and plastic relaxation is discussed. Partial dislocations, shear induced disordering, and metastable phase changes are observed in compressed silicon. For tantalum, the role of grain boundary and twin intersections are evaluated for their role in ductile spallation. Finally, the temperature dependent response of both Ta and Si is investigated.

  14. Intraoperative Localization of Tantalum Markers for Proton Beam Radiation of Choroidal Melanoma by an Opto-Electronic Navigation System: A Novel Technique

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

    Amstutz, Christoph A., E-mail: christoph.amstutz@usz.ch; Bechrakis, Nikolaos E.; Foerster, Michael H.

    2012-03-15

    Purpose: External beam proton radiation therapy has been used since 1975 to treat choroidal melanoma. For tumor location determination during proton radiation treatment, surgical tantalum clips are registered with image data. This report introduces the intraoperative application of an opto-electronic navigation system to determine with high precision the position of the tantalum markers and their spatial relationship to the tumor and anatomical landmarks. The application of the technique in the first 4 patients is described. Methods and Materials: A navigated reference base was attached noninvasively to the eye, and a navigated pointer device was used to record the spatial positionmore » of the tantalum markers, the tumor, and anatomical landmarks. Measurement accuracy was assessed on ex vivo porcine eye specimen by repetitive recording of the tantalum marker positions. The method was applied intraoperatively on 4 patients undergoing routine tantalum clip surgery. The spatial position information delivered by the navigation system was compared to the geometric data generated by the EYEPLAN software. Results: In the ex vivo experiments, the maximum repetition error was 0.34 mm. For the intraoperative application, the root mean square error of paired-points matching of the marker positions from the navigation system and from the EYEPLAN software was 0.701-1.25 mm. Conclusions: Navigation systems are a feasible tool for accurate localization of tantalum markers and anatomic landmarks. They can provide additional geometric information, and therefore have the potential to increase the reliability and accuracy of external beam proton radiation therapy for choroidal melanoma.« less

  15. 1 CFR 17.4 - Procedure and timing for emergency publication.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 1 General Provisions 1 2010-01-01 2010-01-01 false Procedure and timing for emergency publication. 17.4 Section 17.4 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER PREPARATION... Schedule § 17.4 Procedure and timing for emergency publication. (a) Each agency requesting publication on...

  16. Novel hierarchical tantalum oxide-PDMS hybrid coating for medical implants: One pot synthesis, characterization and modulation of fibroblast proliferation.

    PubMed

    Tran, Phong A; Fox, Kate; Tran, Nhiem

    2017-01-01

    Surface properties such as morphology, roughness and charge density have a strong influence on the interaction of biomaterials and cells. Hierarchical materials with a combination of micron/submicron and nanoscale features for coating of medical implants could therefore have significant potential to modulate cellular responses and eventually improve the performance of the implants. In this study, we report a simple, one pot wet chemistry preparation of a hybrid coating system with hierarchical surface structures consisting of polydimethylsiloxane (PDMS) and tantalum oxide. Medical grade, amine functional PDMS was mixed with tantalum ethoxide which subsequently formed Ta 2 O 5 in situ through hydrolysis and condensation during coating process. The coatings were characterized by SEM, EDS, XPS, confocal scanning microscopy, contact angle measurement and in vitro cell culture. Varying PDMS and tantalum ethoxide ratios resulted in coatings of different surface textures ranging from smooth to submicro- and nano-structured. Strikingly, hierarchical surfaces containing both microscale (1-1.5μm) and nanoscale (86-163nm) particles were found on coatings synthesized with 20% and 40% (v/v) tantalum ethoxide. The coatings were similar in term of hydrophobicity but showed different surface roughness and chemical composition. Importantly, higher cell proliferation was observed on hybrid surface with hierarchical structures compared to pure PDMS or pure tantalum oxide. The coating process is simple, versatile, carried out under ambient condition and requires no special equipment. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. 46 CFR 174.075 - Compartments assumed flooded: general.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Compartments assumed flooded: general. 174.075 Section 174.075 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling...

  18. 46 CFR 174.070 - General damage stability assumptions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false General damage stability assumptions. 174.070 Section 174.070 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling...

  19. 46 CFR 174.070 - General damage stability assumptions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false General damage stability assumptions. 174.070 Section 174.070 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling...

  20. 46 CFR 174.075 - Compartments assumed flooded: general.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Compartments assumed flooded: general. 174.075 Section 174.075 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling...

  1. 40 CFR 60.174 - Standard for visible emissions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standard for visible emissions. 60.174 Section 60.174 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Standards of Performance for Primary Zinc...

  2. Effect of oxygen deficiency on electronic properties and local structure of amorphous tantalum oxide thin films

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

    Denny, Yus Rama; Firmansyah, Teguh; Oh, Suhk Kun

    2016-10-15

    Highlights: • The effect of oxygen flow rate on electronic properties and local structure of tantalum oxide thin films was studied. • The oxygen deficiency induced the nonstoichiometric state a-TaOx. • A small peak at 1.97 eV above the valence band side appeared on nonstoichiometric Ta{sub 2}O{sub 5} thin films. • The oxygen flow rate can change the local electronic structure of tantalum oxide thin films. - Abstract: The dependence of electronic properties and local structure of tantalum oxide thin film on oxygen deficiency have been investigated by means of X-ray photoelectron spectroscopy (XPS), Reflection Electron Energy Loss Spectroscopy (REELS),more » and X-ray absorption spectroscopy (XAS). The XPS results showed that the oxygen flow rate change results in the appearance of features in the Ta 4f at the binding energies of 23.2 eV, 24.4 eV, 25.8, and 27.3 eV whose peaks are attributed to Ta{sup 1+}, Ta{sup 2+}, Ta{sup 3+}/Ta{sup 4+}, and Ta{sup 5+}, respectively. The presence of nonstoichiometric state from tantalum oxide (TaOx) thin films could be generated by the oxygen vacancies. In addition, XAS spectra manifested both the increase of coordination number of the first Ta-O shell and a considerable reduction of the Ta-O bond distance with the decrease of oxygen deficiency.« less

  3. 33 CFR 174.121 - Forwarding of casualty or accident reports.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... accident reports. 174.121 Section 174.121 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... § 174.121 Forwarding of casualty or accident reports. Within 30 days of the receipt of a casualty or accident report, each State that has an approved numbering system must forward a copy of that report to the...

  4. 33 CFR 174.121 - Forwarding of casualty or accident reports.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... accident reports. 174.121 Section 174.121 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... § 174.121 Forwarding of casualty or accident reports. Within 30 days of the receipt of a casualty or accident report, each State that has an approved numbering system must forward a copy of that report to the...

  5. 46 CFR 154.174 - Transverse contiguous hull structure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Transverse contiguous hull structure. 154.174 Section... Equipment Hull Structure § 154.174 Transverse contiguous hull structure. (a) The transverse contiguous hull...) The transverse contiguous hull structure of a vessel having cargo containment systems with secondary...

  6. Effect of Surge Current Testing on Reliability of Solid Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2008-01-01

    Tantalum capacitors manufactured per military specifications are established reliability components and have less than 0.001% of failures per 1000 hours for grades D or S, thus positioning these parts among electronic components with the highest reliability characteristics. Still, failures of tantalum capacitors do happen and when it occurs it might have catastrophic consequences for the system. To reduce this risk, further development of a screening and qualification system with special attention to the possible deficiencies in the existing procedures is necessary. The purpose of this work is evaluation of the effect of surge current stress testing on reliability of the parts at both steady-state and multiple surge current stress conditions. In order to reveal possible degradation and precipitate more failures, various part types were tested and stressed in the range of voltage and temperature conditions exceeding the specified limits. A model to estimate the probability of post-surge current testing-screening failures and measures to improve the effectiveness of the screening process has been suggested.

  7. 33 CFR 174.29 - Temporary certificate of number.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Temporary certificate of number. 174.29 Section 174.29 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY....29 Temporary certificate of number. A State may issue a temporary certificate of number that is...

  8. 33 CFR 174.29 - Temporary certificate of number.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Temporary certificate of number. 174.29 Section 174.29 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY....29 Temporary certificate of number. A State may issue a temporary certificate of number that is...

  9. 46 CFR 154.174 - Transverse contiguous hull structure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Transverse contiguous hull structure. 154.174 Section... Equipment Hull Structure § 154.174 Transverse contiguous hull structure. (a) The transverse contiguous hull structure of a vessel having cargo containment systems without secondary barriers must meet the standards of...

  10. 46 CFR 154.174 - Transverse contiguous hull structure.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Transverse contiguous hull structure. 154.174 Section... Equipment Hull Structure § 154.174 Transverse contiguous hull structure. (a) The transverse contiguous hull structure of a vessel having cargo containment systems without secondary barriers must meet the standards of...

  11. 46 CFR 154.174 - Transverse contiguous hull structure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Transverse contiguous hull structure. 154.174 Section... Equipment Hull Structure § 154.174 Transverse contiguous hull structure. (a) The transverse contiguous hull structure of a vessel having cargo containment systems without secondary barriers must meet the standards of...

  12. 46 CFR 154.174 - Transverse contiguous hull structure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Transverse contiguous hull structure. 154.174 Section... Equipment Hull Structure § 154.174 Transverse contiguous hull structure. (a) The transverse contiguous hull structure of a vessel having cargo containment systems without secondary barriers must meet the standards of...

  13. 40 CFR 17.4 - Applicability to EPA proceedings.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 1 2013-07-01 2013-07-01 false Applicability to EPA proceedings. 17.4... ACCESS TO JUSTICE ACT IN EPA ADMINISTRATIVE PROCEEDINGS General Provisions § 17.4 Applicability to EPA proceedings. The Act applies to an adversary adjudication pending before EPA at any time between October 1...

  14. 40 CFR 17.4 - Applicability to EPA proceedings.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 1 2012-07-01 2012-07-01 false Applicability to EPA proceedings. 17.4... ACCESS TO JUSTICE ACT IN EPA ADMINISTRATIVE PROCEEDINGS General Provisions § 17.4 Applicability to EPA proceedings. The Act applies to an adversary adjudication pending before EPA at any time between October 1...

  15. 40 CFR 17.4 - Applicability to EPA proceedings.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 1 2014-07-01 2014-07-01 false Applicability to EPA proceedings. 17.4... ACCESS TO JUSTICE ACT IN EPA ADMINISTRATIVE PROCEEDINGS General Provisions § 17.4 Applicability to EPA proceedings. The Act applies to an adversary adjudication pending before EPA at any time between October 1...

  16. 40 CFR 17.4 - Applicability to EPA proceedings.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 1 2011-07-01 2011-07-01 false Applicability to EPA proceedings. 17.4... ACCESS TO JUSTICE ACT IN EPA ADMINISTRATIVE PROCEEDINGS General Provisions § 17.4 Applicability to EPA proceedings. The Act applies to an adversary adjudication pending before EPA at any time between October 1...

  17. 40 CFR 17.4 - Applicability to EPA proceedings.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Applicability to EPA proceedings. 17.4... ACCESS TO JUSTICE ACT IN EPA ADMINISTRATIVE PROCEEDINGS General Provisions § 17.4 Applicability to EPA proceedings. The Act applies to an adversary adjudication pending before EPA at any time between October 1...

  18. 46 CFR 174.215 - Drainage of weather deck.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Drainage of weather deck. 174.215 Section 174.215 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES... weather deck. The weather deck must have open rails to allow rapid clearing of water, or must have freeing...

  19. 46 CFR 174.215 - Drainage of weather deck.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Drainage of weather deck. 174.215 Section 174.215 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES... weather deck. The weather deck must have open rails to allow rapid clearing of water, or must have freeing...

  20. 46 CFR 174.215 - Drainage of weather deck.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Drainage of weather deck. 174.215 Section 174.215 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES... weather deck. The weather deck must have open rails to allow rapid clearing of water, or must have freeing...

  1. 46 CFR 174.215 - Drainage of weather deck.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Drainage of weather deck. 174.215 Section 174.215 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES... weather deck. The weather deck must have open rails to allow rapid clearing of water, or must have freeing...

  2. 46 CFR 174.215 - Drainage of weather deck.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Drainage of weather deck. 174.215 Section 174.215 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES... weather deck. The weather deck must have open rails to allow rapid clearing of water, or must have freeing...

  3. Effect of silicon, tantalum, and tungsten doping and polarization on bioactivity of hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Dhal, Jharana

    Hydroxyapatite (HAp) ceramics has important applications as bone graft because of the structural and compositional similarities with bone tissue. However, inferior osteogenic capacity to bone and poor mechanical properties have been identified to be major disadvantages of synthetic HAp compared to the living bone tissue. The objective of the current study is to evaluate the effect of doping with higher valent cations (Tungsten, tantalum, and silicon) and polarization or combination of both on change in property of doped HAp and subsequent impact its bioactivity. In vitro study with human osteoblast cells was used to investigate the influences of doping and polarization on bone cell-materials interactions. The bioactivity of doped HAp was compared with pure HAp. Effect of doping and polarization on the change in HAp was investigated by monitoring change in mineral phases, stored charge, and activation energy of HAp. Activation energy of depolarization was used to explain the possible mechanism of polarization in doped samples. Bioactivity of HAp increased when doped with tantalum and tungsten. Polarization further increased the bioactivity of tungsten- and tantalum-doped samples. Increase in bioactivity on polarized and doped samples was attributed to increase in surface energy and increase in surface wettability. Whereas, an increase in bioactivity on doped unpolarized surface was attributed to change in microstructure. Polarized charge calculated from TSDC indicates that polarized charge decreases on tantalum- and tungsten-doped HAp. The decrease in polarized charge was attributed to the presence of significant amount of different phases that may hinder the ionic motion in doped samples. However, for silicon-doped HAp, TSDC study showed no difference in the mechanism of polarization between doped and undoped samples. Increase in silicon doping decreased the grain size though mechanism is not affected by grain size. Total stored charge decreased with increase in

  4. 46 CFR 174.315 - Extent and character of damage.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments Calculations § 174.315 Extent and character of damage. (a) The calculations required by § 174.310 must show that the dredge can...

  5. 46 CFR 174.315 - Extent and character of damage.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments Calculations § 174.315 Extent and character of damage. (a) The calculations required by § 174.310 must show that the dredge can...

  6. Ion beam and dual ion beam sputter deposition of tantalum oxide films

    NASA Astrophysics Data System (ADS)

    Cevro, Mirza; Carter, George

    1994-11-01

    Ion beam sputter deposition (IBS) and dual ion beam sputter deposition (DIBS) of tantalum oxide films was investigated at room temperature and compared with similar films prepared by e-gun deposition. Optical properties ie refractive index and extinction coefficient of IBS films were determined in the 250 - 1100 nm range by transmission spectrophotometry and at (lambda) equals 632.8 nm by ellipsometry. They were found to be mainly sensitive to the partial pressure of oxygen used as a reactive gas in the deposition process. The maximum value of the refractive index of IBS deposited tantalum oxide films was n equals 2.15 at (lambda) equals 550 nm and the extinction coefficient of order k equals 2 X 10-4. Films deposited by e-gun deposition had refractive index n equals 2.06 at (lambda) equals 550 nm. Films deposited using DIBS ie deposition assisted by low energy Ar and O2 ions (Ea equals 0 - 300 eV) and low current density (Ji equals 0 - 40 (mu) A/cm2) showed no improvement in the optical properties of the films. Preferential sputtering occurred at Ea(Ar) equals 300 eV and Ji equals 20 (mu) A/cm2 and slightly oxygen deficient films were formed. Different bonding states in the tantalum-oxide films were determined by x-ray spectroscopy while composition of the film and contaminants were determined by Rutherford scattering spectroscopy. Tantalum oxide films formed by IBS contained relatively high Ar content (approximately equals 2.5%) originating from the reflected argon neutrals from the sputtering target while assisted deposition slightly increased the Ar content. Stress in the IBS deposited films was measured by the bending technique. IBS deposited films showed compressive stress with a typical value of s equals 3.2 X 109 dyn/cm2. Films deposited by concurrent ion bombardment showed an increase in the stress as a function of applied current density. The maximum was s approximately equals 5.6 X 109 dyn/cm2 for Ea equals 300 eV and Ji equals 35 (mu) A/cm2. All

  7. Ion-beam and dual-ion-beam sputter deposition of tantalum oxide films

    NASA Astrophysics Data System (ADS)

    Cevro, Mirza; Carter, George

    1995-02-01

    Ion-beam sputter deposition (IBS) and dual-ion-beam sputter deposition (DIBS) of tantalum oxide films was investigated at room temperature and compared with similar films prepared by e-gun deposition. The optical properties, i.e., refractive index and extinction coefficient, of IBS films were determined in the 250- to 1100-nm range by transmission spectrophotometry and at (lambda) equals 632.8 nm by ellipsometry. They were found to be mainly sensitive to the partial pressure of oxygen used as a reactive gas in the deposition process. The maximum value of the refractive index of IBS deposited tantalum oxide films was n equals 2.15 at (lambda) equals 550 nm and the extinction coefficient of order k equals 2 X 10-4. Films deposited by e-gun deposition had refractive index n 2.06 at (lambda) equals 550 nm. Films deposited using DIBS, i.e., deposition assisted by low energy Ar and O2 ions (Ea equals 0 to 300 eV) and low current density (Ji equals 0 to 40 (mu) A/cm2), showed no improvement in the optical properties of the films. Preferential sputtering occurred at Ea(Ar) equals 300 eV and Ji equals 20 (mu) A/cm2 and slightly oxygen deficient films were formed. Different bonding states in the tantalum-oxide films were determined by x-ray spectroscopy, whereas composition of the film and contaminants were determined by Rutherford backscattering spectroscopy (RBS). Tantalum oxide films formed by IBS contained relatively high Ar content (approximately equals 2.5%) originating from the reflected argon neutrals from the sputtering target whereas assisted deposition slightly increased the Ar content. Stress in the IBS-deposited films was measured by the bending technique. IBS-deposited films showed compressive stress with a typical value of s equals 3.2 X 109 dyn/cm2. Films deposited by concurrent ion bombardment showed an increase in the stress as a function of applied current density. The maximum was s approximately equals 5.6 X 109 dyn/cm2 for Ea equals 300 eV and Ji equals

  8. 19 CFR 174.24 - Criteria for further review.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... upon by the Commissioner of Customs or his designee or by the Customs courts; (c) Involves matters... 19 Customs Duties 2 2011-04-01 2011-04-01 false Criteria for further review. 174.24 Section 174.24 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE...

  9. 19 CFR 174.24 - Criteria for further review.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... upon by the Commissioner of Customs or his designee or by the Customs courts; (c) Involves matters... 19 Customs Duties 2 2014-04-01 2014-04-01 false Criteria for further review. 174.24 Section 174.24 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE...

  10. 19 CFR 174.24 - Criteria for further review.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... upon by the Commissioner of Customs or his designee or by the Customs courts; (c) Involves matters... 19 Customs Duties 2 2013-04-01 2013-04-01 false Criteria for further review. 174.24 Section 174.24 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE...

  11. 19 CFR 174.24 - Criteria for further review.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... upon by the Commissioner of Customs or his designee or by the Customs courts; (c) Involves matters... 19 Customs Duties 2 2010-04-01 2010-04-01 false Criteria for further review. 174.24 Section 174.24 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE...

  12. 19 CFR 174.24 - Criteria for further review.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... upon by the Commissioner of Customs or his designee or by the Customs courts; (c) Involves matters... 19 Customs Duties 2 2012-04-01 2012-04-01 false Criteria for further review. 174.24 Section 174.24 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE...

  13. Evaluation of wet tantalum capacitors after exposure to extended periods of ripple current, volume 1

    NASA Technical Reports Server (NTRS)

    Watson, G. W.; Lasharr, J. C.; Shumaker, M. J.

    1974-01-01

    The application of tantalum capacitors in the Viking Lander includes both dc voltage and ripple current electrical stress, high temperature during nonoperating times (sterilization), and high vibration and shock loads. The capacitors must survive these severe environments without any degradation if reliable performance is to be achieved. A test program was established to evaluate both wet-slug tantalum and wet-foil capacitors under conditions accurately duplicating actual Viking applications. Test results of the electrical performance characteristics during extended periods of ripple current, the characteristics of the internal silver migration as a function for extended periods of ripple current, and the existence of any memory characteristics are presented.

  14. Evaluation of wet tantalum capacitors after exposure to extended periods of ripple current, volume 2

    NASA Technical Reports Server (NTRS)

    Ward, C. M.

    1975-01-01

    The application of tantalum capacitors in the Viking Lander includes dc voltage and ripple current electrical stress, high temperature during nonoperating times (sterilization), and high vibration and shock loads. The capacitors must survive these severe environments without any degradation if reliable performance is to be achieved. A test program was established to evaluate both wet-slug tantalum and wet-foil capacitors under conditions accurately duplicating actual Viking applications. Test results of the electrical performance characteristics during extended periods of ripple current, the characteristics of the internal silver migration as a function of extended periods of ripple current, and the existence of any memory characteristics are presented.

  15. Niobium (columbium) and tantalum resources of Brazil

    USGS Publications Warehouse

    White, Max Gregg

    1975-01-01

    Most of the niobium resources of Brazil occur as pyrochlore in carbonatites within syenitic intrusives of Late Cretaceous to early Tertiary age in western Minas Gerais and southeastern Goils. Minor amounts of it are produced together with tantalum from columbite-tantalite concentrates from pegmatites and placers adjacent to them, in the Sao Joao del Rei district in south-central Minas Gerais. All the niobium and tantalum produced in Brazil is exported. The only pyrochlore mined is from the Barreiro carbonatite deposit near Araxa in Minas Gerais where concentrates and ferroniobium are produced. Exploration work for pyrochlore and other mineral resources are being undertaken on other carbonatites, particularly at Catalao I in southeast Goias and at Tapira and Serra Negra in western Minas Gerais. Annual production and export from the Barreiro deposit are about 8,000 metric tons of pyrochlore concentrate containing about 60 percent Nb205 and about 2,700 metric tons of ferroniobium with 63 percent Nb2O5. The annual production capacity of the Barreiro plant is 18,000 tons of concentrate and 4,000 tons of ferroniobium. Ore reserves of the Barreiro deposit in all categories are 380 million tons with percent Nb2O5. Annual production of tantalite-columbite from the Sao Joao del Rei district, most of which is exported to the United States, is about 290 tons, of which about 79 percent is tantalite and about percent is columbite. Reserves of tantalite-columbite in the Sao Joao del Rei district are about 43,000 tons of proved and 73,000 tons of probable ore.

  16. 21 CFR 174.5 - General provisions applicable to indirect food additives.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... additives. 174.5 Section 174.5 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: GENERAL § 174.5 General provisions applicable to indirect food additives. (a) Regulations prescribing conditions under...

  17. 21 CFR 174.5 - General provisions applicable to indirect food additives.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... additives. 174.5 Section 174.5 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) INDIRECT FOOD ADDITIVES: GENERAL § 174.5 General provisions applicable to indirect food additives. (a) Regulations prescribing conditions under which food additive substances may be...

  18. 21 CFR 174.5 - General provisions applicable to indirect food additives.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... additives. 174.5 Section 174.5 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: GENERAL § 174.5 General provisions applicable to indirect food additives. (a) Regulations prescribing conditions under...

  19. 21 CFR 174.5 - General provisions applicable to indirect food additives.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... additives. 174.5 Section 174.5 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: GENERAL § 174.5 General provisions applicable to indirect food additives. (a) Regulations prescribing conditions under...

  20. 21 CFR 174.5 - General provisions applicable to indirect food additives.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... additives. 174.5 Section 174.5 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: GENERAL § 174.5 General provisions applicable to indirect food additives. (a) Regulations prescribing conditions under...

  1. Development of high temperature materials for solid propellant rocket nozzle applications. [tantalum carbides-tungsten fiber composites

    NASA Technical Reports Server (NTRS)

    Manning, C. R., Jr.; Honeycutt, L., III

    1974-01-01

    Evaluation of tantalum carbide-tungsten fiber composites has been completed as far as weight percent carbon additions and weight percent additions of tungsten fiber. Extensive studies were undertaken concerning Young's Modulus and fracture strength of this material. Also, in-depth analysis of the embrittling effects of the extra carbon additions on the tungsten fibers has been completed. The complete fabrication procedure for the tantalum carbide-tungsten fiber composites with extra carbon additions is given. Microprobe and metallographic studies showed the effect of extra carbon on the tungsten fibers, and evaluation of the thermal shock parameter fracture strength/Young's Modulus is included.

  2. 46 CFR 174.195 - Bulkheads in machinery spaces.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Bulkheads in machinery spaces. 174.195 Section 174.195... in machinery spaces. (a) The bulkhead in each machinery space of each OSV must be watertight to the bulkhead deck. (b) Each penetration of, and each opening in, a bulkhead in a machinery space must— (1) Be...

  3. 46 CFR 174.195 - Bulkheads in machinery spaces.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Bulkheads in machinery spaces. 174.195 Section 174.195... in machinery spaces. (a) The bulkhead in each machinery space of each OSV must be watertight to the bulkhead deck. (b) Each penetration of, and each opening in, a bulkhead in a machinery space must— (1) Be...

  4. 46 CFR 174.195 - Bulkheads in machinery spaces.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Bulkheads in machinery spaces. 174.195 Section 174.195... in machinery spaces. (a) The bulkhead in each machinery space of each OSV must be watertight to the bulkhead deck. (b) Each penetration of, and each opening in, a bulkhead in a machinery space must— (1) Be...

  5. 46 CFR 174.195 - Bulkheads in machinery spaces.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Bulkheads in machinery spaces. 174.195 Section 174.195... in machinery spaces. (a) The bulkhead in each machinery space of each OSV must be watertight to the bulkhead deck. (b) Each penetration of, and each opening in, a bulkhead in a machinery space must— (1) Be...

  6. 46 CFR 174.195 - Bulkheads in machinery spaces.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Bulkheads in machinery spaces. 174.195 Section 174.195... in machinery spaces. (a) The bulkhead in each machinery space of each OSV must be watertight to the bulkhead deck. (b) Each penetration of, and each opening in, a bulkhead in a machinery space must— (1) Be...

  7. Use of steel and tantalum apparatus for molten Cd-Mg-Zn alloys

    NASA Technical Reports Server (NTRS)

    Bennett, G. A.; Burris, L., Jr.; Kyle, M. L.; Nelson, P. A.

    1966-01-01

    Steel and tantalum apparatus contains various ternary alloys of cadmium, zinc, and magnesium used in pyrochemical processes for the recovery of uranium-base reactor fuels. These materials exhibit good corrosion resistance at the high temperatures necessary for fuel separation in liquid metal-molten salt solvents.

  8. Direct electroplating of copper on tantalum from ionic liquids in high vacuum: origin of the tantalum oxide layer.

    PubMed

    Schaltin, Stijn; D'Urzo, Lucia; Zhao, Qiang; Vantomme, André; Plank, Harald; Kothleitner, Gerald; Gspan, Christian; Binnemans, Koen; Fransaer, Jan

    2012-10-21

    In this paper, it is shown that high vacuum conditions are not sufficient to completely remove water and oxygen from the ionic liquid 1-ethyl-3-methylimidazolium chloride. Complete removal of water demands heating above 150 °C under reduced pressure, as proven by Nuclear Reaction Analysis (NRA). Dissolved oxygen gas can only be removed by the use of an oxygen scavenger such as hydroquinone, despite the fact that calculations show that oxygen should be removed completely by the applied vacuum conditions. After applying a strict drying procedure and scavenging of molecular oxygen, it was possible to deposit copper directly on tantalum without the presence of an intervening oxide layer.

  9. Degradation of Leakage Currents and Reliability Prediction for Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2016-01-01

    Two types of failures in solid tantalum capacitors, catastrophic and parametric, and their mechanisms are described. Analysis of voltage and temperature reliability acceleration factors reported in literature shows a wide spread of results and requires more investigation. In this work, leakage currents in two types of chip tantalum capacitors were monitored during highly accelerated life testing (HALT) at different temperatures and voltages. Distributions of degradation rates were approximated using a general log-linear Weibull model and yielded voltage acceleration constants B = 9.8 +/- 0.5 and 5.5. The activation energies were Ea = 1.65 eV and 1.42 eV. The model allows for conservative estimations of times to failure and was validated by long-term life test data. Parametric degradation and failures are reversible and can be annealed at high temperatures. The process is attributed to migration of charged oxygen vacancies that reduce the barrier height at the MnO2/Ta2O5 interface and increase injection of electrons from the MnO2 cathode. Analysis showed that the activation energy of the vacancies' migration is 1.1 eV.

  10. 46 CFR 174.305 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments § 174.305 Definitions. Hopper dredge has the same meaning as contained in § 44.310 of this chapter. Length has the same meaning as...

  11. 46 CFR 174.305 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments § 174.305 Definitions. Hopper dredge has the same meaning as contained in § 44.310 of this chapter. Length has the same meaning as...

  12. 5 CFR 1201.174 - Enforcing the Special Panel decision.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    .... 1201.174 Section 1201.174 Administrative Personnel MERIT SYSTEMS PROTECTION BOARD ORGANIZATION AND... Special Panel, will order the agency concerned to take any action appropriate to carry out the decision of... matter. These regulations are set out in subpart F of this part. ...

  13. 5 CFR 1201.174 - Enforcing the Special Panel decision.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    .... 1201.174 Section 1201.174 Administrative Personnel MERIT SYSTEMS PROTECTION BOARD ORGANIZATION AND... Special Panel, will order the agency concerned to take any action appropriate to carry out the decision of... matter. These regulations are set out in subpart F of this part. ...

  14. 5 CFR 1201.174 - Enforcing the Special Panel decision.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    .... 1201.174 Section 1201.174 Administrative Personnel MERIT SYSTEMS PROTECTION BOARD ORGANIZATION AND... Special Panel, will order the agency concerned to take any action appropriate to carry out the decision of... matter. These regulations are set out in subpart F of this part. ...

  15. 5 CFR 1201.174 - Enforcing the Special Panel decision.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    .... 1201.174 Section 1201.174 Administrative Personnel MERIT SYSTEMS PROTECTION BOARD ORGANIZATION AND... Special Panel, will order the agency concerned to take any action appropriate to carry out the decision of... matter. These regulations are set out in subpart F of this part. ...

  16. Experimental study on deep hole drilling of 17-4PH material

    NASA Astrophysics Data System (ADS)

    Uzhanfeng, LI; Uquantai, LI

    2018-02-01

    This paper uses 17-4PH material as the research object, according to the material characteristics of 17-4PH, designed and carried out deep hole drilling test. The purpose of the experiment is to study and discuss the three major problems of tool wear, chip shape and axial deviation of the hole in the process of deep hole drilling of 17-4PH materials. Through the deep hole drilling test of 17-4PH material, the variation of the chip shape and the deflection of the hole axis was obtained under different wear conditions.

  17. Synthesis, Consolidation and Characterization of Sol-gel Derived Tantalum-Tungsten Oxide Thermite Composites

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

    Cervantes, O

    2010-06-01

    Energetic composite powders consisting of sol-gel (SG) derived nanostructured tungsten oxide were produced with various amounts of micrometer-scale tantalum fuel metal. Such energetic composite powders were ignition-tested and results show that the powders are not sensitive to friction, spark and/or impact ignition. Initial consolidation experiments, using the High Pressure Spark Plasma Sintering (HPSPS) technique, on the SG derived nanostructured tungsten oxide produced samples with higher relative density than can be achieved with commercially available tungsten oxide. The SG derived nanostructured tungsten oxide with immobilized tantalum fuel metal (Ta - WO3) energetic composite was consolidated to a density of 9.17 g·cm-3more » or 93% relative density. In addition, those samples were consolidated without significant pre-reaction of the constituents, thus retaining their stored chemical energy.« less

  18. Effect of Preconditioning and Soldering on Failures of Chip Tantalum Capacitors

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander A.

    2014-01-01

    Soldering of molded case tantalum capacitors can result in damage to Ta205 dielectric and first turn-on failures due to thermo-mechanical stresses caused by CTE mismatch between materials used in the capacitors. It is also known that presence of moisture might cause damage to plastic cases due to the pop-corning effect. However, there are only scarce literature data on the effect of moisture content on the probability of post-soldering electrical failures. In this work, that is based on a case history, different groups of similar types of CWR tantalum capacitors from two lots were prepared for soldering by bake, moisture saturation, and longterm storage at room conditions. Results of the testing showed that both factors: initial quality of the lot, and preconditioning affect the probability of failures. Baking before soldering was shown to be effective to prevent failures even in lots susceptible to pop-corning damage. Mechanism of failures is discussed and recommendations for pre-soldering bake are suggested based on analysis of moisture characteristics of materials used in the capacitors' design.

  19. NEPP Evaluation of Automotive Grade Tantalum Chip Capacitors

    NASA Technical Reports Server (NTRS)

    Sampson, Mike; Brusse, Jay

    2018-01-01

    Automotive grade tantalum (Ta) chip capacitors are available at lower cost with smaller physical size and higher volumetric efficiency compared to military/space grade capacitors. Designers of high reliability aerospace and military systems would like to take advantage of these attributes while maintaining the high standards for long-term reliable operation they are accustomed to when selecting military-qualified established reliability tantalum chip capacitors (e.g., MIL-PRF-55365). The objective for this evaluation was to assess the long-term performance of off-the-shelf automotive grade Ta chip capacitors (i.e., manufacturer self-qualified per AEC Q-200). Two (2) lots of case size D manganese dioxide (MnO2) cathode Ta chip capacitors from 1 manufacturer were evaluated. The evaluation consisted of construction analysis, basic electrical parameter characterization, extended long-term (2000 hours) life testing and some accelerated stress testing. Tests and acceptance criteria were based upon manufacturer datasheets and the Automotive Electronics Council's AEC Q-200 qualification specification for passive electronic components. As-received a few capacitors were marginally above the specified tolerance for capacitance and ESR. X-ray inspection found that the anodes for some devices may not be properly aligned within the molded encapsulation leaving less than 1 mil thickness of the encapsulation. This evaluation found that the long-term life performance of automotive grade Ta chip capacitors is generally within specification limits suggesting these capacitors may be suitable for some space applications.

  20. Antibacterial properties and cytocompatibility of tantalum oxide coatings with different silver content

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

    Huang, Heng-Li; Chang, Yin-Yu, E-mail: yinyu@mail2000.com.tw; Chen, Hung-Jui

    Tantalum (Ta) oxides and their coatings have been proved to increase their applications in the biomedical fields by improving osseointegration and wear resistance. In this study, Ta oxide coatings containing different proportions of Ag are deposited on SS304 materials. A twin-gun magnetron sputtering system is used to deposit the tantalum oxide-Ag coating. In this study, Staphylococcus aureus, which exhibits physiological commensalism on the human skin, nares, and mucosal and oral areas, is chosen as the model for in vitro antibacterial analyses via a fluorescence staining method using Syto9. The cytocompatibility and adhesive morphology of human skin fibroblast cells (CCD-966SK) onmore » the coatings are also determined by using the microculture tetrazolium assay. This study shows that Ta{sub 2}O{sub 5} and Ta{sub 2}O{sub 5}-Ag coatings with 12.5 at. % of Ag exhibit improved antibacterial effects against S. aureus and have good skin fibroblast cell cellular biocompatibility.« less

  1. 46 CFR 174.085 - Flooding on column stabilized units.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Flooding on column stabilized units. 174.085 Section 174.085 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling...

  2. 46 CFR 174.085 - Flooding on column stabilized units.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Flooding on column stabilized units. 174.085 Section 174.085 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling...

  3. 21 CFR 14.174 - Advice and recommendations in writing.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... § 14.174 Advice and recommendations in writing. Advice and recommendations given by a committee on a... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Advice and recommendations in writing. 14.174... of the advice and recommendations of the committee. ...

  4. 21 CFR 14.174 - Advice and recommendations in writing.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... § 14.174 Advice and recommendations in writing. Advice and recommendations given by a committee on a... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Advice and recommendations in writing. 14.174... of the advice and recommendations of the committee. ...

  5. Analysis of shockless dynamic compression data on solids to multi-megabar pressures: Application to tantalum

    DOE PAGES

    Davis, Jean -Paul; Brown, Justin L.; Knudson, Marcus D.; ...

    2014-11-26

    In this research, magnetically-driven, planar shockless-compression experiments to multi-megabar pressures were performed on tantalum samples using a stripline target geometry. Free-surface velocity waveforms were measured in 15 cases; nine of these in a dual-sample configuration with two samples of different thicknesses on opposing electrodes, and six in a single-sample configuration with a bare electrode opposite the sample. Details are given on the application of inverse Lagrangian analysis (ILA) to these data, including potential sources of error. The most significant source of systematic error, particularly for single-sample experiments, was found to arise from the pulse-shape dependent free-surface reflected wave interactions withmore » the deviatoric-stress response of tantalum. This could cause local, possibly temporary, unloading of material from a ramp compressed state, and thus multi-value response in wave speed that invalidates the free-surface to in-material velocity mapping step of ILA. By averaging all 15 data sets, a final result for the principal quasi-isentrope of tantalum in stress-strain was obtained to a peak longitudinal stress of 330 GPa with conservative uncertainty bounds of ±4.5% in stress. The result agrees well with a tabular equation of state developed at Los Alamos National Laboratory.« less

  6. Internal fuse modules for solid tantalum capacitors

    NASA Technical Reports Server (NTRS)

    Dematos, H. V.

    1981-01-01

    Miniature fuse modules were designed for and incorporated into two styles of solid tantalum capacitors. One is an epoxy molded, radial leaded, high frequency decoupling capacitor; the other is an hermetically sealed device with axial lead wires. The fusible element for both devices consists of a fine bimetallic wire which reacts exothermically upon reaching a critical temperature and then disintegrates. The desirability of having fused devices is discussed and design constraints, in particular those which minimize inductance and series resistance while optimizing fuse actuation characteristics, are reviewed. Factors affecting the amount of energy required to actuate the fuse and reliability of acuation are identified.

  7. 48 CFR 217.174 - Multiyear contracts that employ economic order quantity procurement.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... employ economic order quantity procurement. 217.174 Section 217.174 Federal Acquisition Regulations... TYPES SPECIAL CONTRACTING METHODS Mulityear Contracting 217.174 Multiyear contracts that employ economic... defense committees at least 30 days before awarding— (1) A multiyear contract providing for economic order...

  8. 46 CFR 174.100 - Appliances for watertight and weathertight integrity.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... through 174.085; and (2) A wind heeling moment calculated in accordance with § 174.055 using a wind... met. In either case, control systems for watertight doors must have power supplies, power sources...

  9. 46 CFR 174.100 - Appliances for watertight and weathertight integrity.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... through 174.085; and (2) A wind heeling moment calculated in accordance with § 174.055 using a wind... met. In either case, control systems for watertight doors must have power supplies, power sources...

  10. Alkali oxide-tantalum, niobium and antimony oxide ionic conductors

    NASA Technical Reports Server (NTRS)

    Roth, R. S.; Brower, W. S.; Parker, H. S.; Minor, D. B.; Waring, J. L.

    1975-01-01

    The phase equilibrium relations of four systems were investigated in detail. These consisted of sodium and potassium antimonates with antimony oxide and tantalum and niobium oxide with rubidium oxide as far as the ratio 4Rb2O:llB2O5 (B=Nb, Ta). The ternary system NaSbO3-Sb2O4-NaF was investigated extensively to determine the actual composition of the body centered cubic sodium antimonate. Various other binary and ternary oxide systems involving alkali oxides were examined in lesser detail. The phases synthesized were screened by ion exchange methods to determine mobility of the mobility of the alkali ion within the niobium, tantalum or antimony oxide (fluoride) structural framework. Five structure types warranted further investigation; these structure types are (1) hexagonal tungsten bronze (HTB), (2) pyrochlore, (3) the hybrid HTB-pyrochlore hexagonal ordered phases, (4) body centered cubic antimonates and (5) 2K2O:3Nb2O5. Although all of these phases exhibit good ion exchange properties only the pyrochlore was prepared with Na(+) ions as an equilibrium phase and as a low porosity ceramic. Sb(+3) in the channel interferes with ionic conductivity in this case, although relatively good ionic conductivity was found for the metastable Na(+) ion exchanged analogs of RbTa2O5F and KTaWO6 pyrochlore phases.

  11. 48 CFR 217.174 - Multiyear contracts for electricity from renewable energy sources.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... electricity from renewable energy sources. 217.174 Section 217.174 Federal Acquisition Regulations System... SPECIAL CONTRACTING METHODS Mulityear Contracting 217.174 Multiyear contracts for electricity from... not to exceed 10 years for the purchase of electricity from sources of renewable energy, as that term...

  12. 48 CFR 217.174 - Multiyear contracts for electricity from renewable energy sources.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... electricity from renewable energy sources. 217.174 Section 217.174 Federal Acquisition Regulations System... SPECIAL CONTRACTING METHODS Mulityear Contracting 217.174 Multiyear contracts for electricity from... not to exceed 10 years for the purchase of electricity from sources of renewable energy, as that term...

  13. 48 CFR 217.174 - Multiyear contracts for electricity from renewable energy sources.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... electricity from renewable energy sources. 217.174 Section 217.174 Federal Acquisition Regulations System... SPECIAL CONTRACTING METHODS Mulityear Contracting 217.174 Multiyear contracts for electricity from... not to exceed 10 years for the purchase of electricity from sources of renewable energy, as that term...

  14. 48 CFR 217.174 - Multiyear contracts for electricity from renewable energy sources.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... electricity from renewable energy sources. 217.174 Section 217.174 Federal Acquisition Regulations System... SPECIAL CONTRACTING METHODS Mulityear Contracting 217.174 Multiyear contracts for electricity from... not to exceed 10 years for the purchase of electricity from sources of renewable energy, as that term...

  15. 7 CFR 1427.174 - Maturity of seed cotton loans.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 10 2011-01-01 2011-01-01 false Maturity of seed cotton loans. 1427.174 Section 1427..., DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS COTTON Recourse Seed Cotton Loans § 1427.174 Maturity of seed cotton loans. Seed cotton loans mature on demand by CCC but no later than May 31 following...

  16. 7 CFR 1427.174 - Maturity of seed cotton loans.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Maturity of seed cotton loans. 1427.174 Section 1427..., DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS COTTON Recourse Seed Cotton Loans § 1427.174 Maturity of seed cotton loans. Seed cotton loans mature on demand by CCC but no later than May 31 following...

  17. 7 CFR 1427.174 - Maturity of seed cotton loans.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 10 2014-01-01 2014-01-01 false Maturity of seed cotton loans. 1427.174 Section 1427..., DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS COTTON Recourse Seed Cotton Loans § 1427.174 Maturity of seed cotton loans. Seed cotton loans mature on demand by CCC but no later than May 31 following...

  18. 7 CFR 1427.174 - Maturity of seed cotton loans.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 10 2012-01-01 2012-01-01 false Maturity of seed cotton loans. 1427.174 Section 1427..., DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS COTTON Recourse Seed Cotton Loans § 1427.174 Maturity of seed cotton loans. Seed cotton loans mature on demand by CCC but no later than May 31 following...

  19. 7 CFR 1427.174 - Maturity of seed cotton loans.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 10 2013-01-01 2013-01-01 false Maturity of seed cotton loans. 1427.174 Section 1427..., DEPARTMENT OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS COTTON Recourse Seed Cotton Loans § 1427.174 Maturity of seed cotton loans. Seed cotton loans mature on demand by CCC but no later than May 31 following...

  20. The role of electronegativity on the extent of nitridation of group 5 metals as revealed by reactions of tantalum cluster cations with ammonia molecules.

    PubMed

    Arakawa, Masashi; Ando, Kota; Fujimoto, Shuhei; Mishra, Saurabh; Patwari, G Naresh; Terasaki, Akira

    2018-05-10

    Reactions of the free tantalum cation, Ta+, and tantalum cluster cations, Tan+ (n = 2-10), with ammonia are presented. The reaction of the monomer cation, Ta+, with two molecules of NH3 leads to the formation of TaN2H2+ along with release of two H2 molecules. The dehydrogenation occurs until the formal oxidation number of the tantalum atom reaches +5. On the other hand, all the tantalum cluster cations, Tan+, react with two molecules of NH3 and form TanN2+ with the release of three H2 molecules. Further exposure to ammonia showed that TanNmH+ and TanNm+ are produced through successive reactions; a pure nitride and three H2 molecules are formed for every other NH3 molecule. The nitridation occurred until the formal oxidation number of the tantalum atoms reaches +5 as in the case of TaN2H2+ in contrast to other group 5 elements, i.e., vanadium and niobium, which have been reported to produce nitrides with lower oxidation states. The present results on small gas-phase metal-nitride clusters show correlation with their bulk properties: tantalum is known to form bulk nitrides in the oxidation states of either +5 (Ta3N5) or +3 (TaN), whereas vanadium and niobium form nitrides in the oxidation state of +3 (VN and NbN). Along with DFT calculations, these findings reveal that nitridation is driven by the electron-donating ability of group 5 elements, i.e., electronegativity of the metal plays a key role in determining the composition of the metal nitrides.

  1. 46 CFR 170.174 - Specific applicability.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... REQUIREMENTS FOR ALL INSPECTED VESSELS Determination of Lightweight Displacement and Centers of Gravity § 170.174 Specific applicability. This subpart applies to each vessel for which the lightweight displacement...

  2. 46 CFR 170.174 - Specific applicability.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... REQUIREMENTS FOR ALL INSPECTED VESSELS Determination of Lightweight Displacement and Centers of Gravity § 170.174 Specific applicability. This subpart applies to each vessel for which the lightweight displacement...

  3. 46 CFR 170.174 - Specific applicability.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... REQUIREMENTS FOR ALL INSPECTED VESSELS Determination of Lightweight Displacement and Centers of Gravity § 170.174 Specific applicability. This subpart applies to each vessel for which the lightweight displacement...

  4. 46 CFR 170.174 - Specific applicability.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... REQUIREMENTS FOR ALL INSPECTED VESSELS Determination of Lightweight Displacement and Centers of Gravity § 170.174 Specific applicability. This subpart applies to each vessel for which the lightweight displacement...

  5. 46 CFR 170.174 - Specific applicability.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... REQUIREMENTS FOR ALL INSPECTED VESSELS Determination of Lightweight Displacement and Centers of Gravity § 170.174 Specific applicability. This subpart applies to each vessel for which the lightweight displacement...

  6. Tantalum-tungsten oxide thermite composites prepared by sol-gel synthesis and spark plasma sintering

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

    Kuntz, Joshua D.; Gash, Alexander E.; Cervantes, Octavio G.

    2010-08-15

    Energetic composite powders consisting of sol-gel derived nanostructured tungsten oxide were produced with various amounts of micrometer-scale tantalum fuel metal. Such energetic composite powders were ignition-tested and the results show that the powders are not sensitive to friction, spark and/or impact ignition. Initial consolidation experiments, using the High-Pressure Spark Plasma Sintering (HPSPS) technique, on the sol-gel derived nanostructured tungsten oxide produced samples with higher relative density than can be achieved with commercially available tungsten oxide. The sol-gel derived nanostructured tungsten oxide with immobilized tantalum fuel metal (Ta-WO{sub 3}) energetic composite was consolidated to a density of 9.17 g cm{sup -3}more » or 93% relative density. In addition, those samples were consolidated without significant pre-reaction of the constituents, thus retaining their stored chemical energy. (author)« less

  7. Tantalum-Tungsten Oxide Thermite Composite Prepared by Sol-Gel Synthesis and Spark Plasma Sintering

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

    Cervantes, O; Kuntz, J; Gash, A

    2009-02-13

    Energetic composite powders consisting of sol-gel derived nanostructured tungsten oxide were produced with various amounts of micrometer-scale tantalum fuel metal. Such energetic composite powders were ignition tested and results show that the powders are not sensitive to friction, spark and/or impact ignition. Initial consolidation experiments, using the High Pressure Spark Plasma Sintering (HPSPS) technique, on the sol-gel derived nanostructured tungsten oxide produced samples with higher relative density than can be achieved with commercially available tungsten oxide. The sol-gel derived nanostructured tungsten oxide with immobilized tantalum fuel metal (Ta - WO{sub 3}) energetic composite was consolidated to a density of 9.17more » g.cm{sup -3} or 93% relative density. In addition those parts were consolidated without significant pre-reaction of the constituents, thus the sample retained its stored chemical energy.« less

  8. FAST TRACK COMMUNICATION High rate straining of tantalum and copper

    NASA Astrophysics Data System (ADS)

    Armstrong, R. W.; Zerilli, F. J.

    2010-12-01

    High strain rate measurements reported recently for several tantalum and copper crystal/polycrystal materials are shown to follow dislocation mechanics-based constitutive relations, first at lower strain rates, for dislocation velocity control of the imposed plastic deformations and, then at higher rates, transitioning to nano-scale dislocation generation control by twinning or slip. For copper, there is the possibility of added-on slip dislocation displacements to be accounted for from the newly generated dislocations.

  9. 46 CFR 174.030 - Specific applicability.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling Units § 174.030 Specific applicability. Each mobile offshore drilling unit (MODU) inspected under Subchapter IA of this...

  10. 46 CFR 174.030 - Specific applicability.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling Units § 174.030 Specific applicability. Each mobile offshore drilling unit (MODU) inspected under Subchapter IA of this...

  11. 46 CFR 174.300 - Specific applicability.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments § 174.300 Specific applicability. This subpart applies to each self-propelled hopper dredge for which a working freeboard...

  12. 46 CFR 174.300 - Specific applicability.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments § 174.300 Specific applicability. This subpart applies to each self-propelled hopper dredge for which a working freeboard...

  13. Synthesis of Monodispersed Tantalum(V) oxide Nanospheres by an Ethylene Glycol Mediated Route

    EPA Science Inventory

    Tantalum(V) oxide (Ta2O5) nanospheres have been synthesized by a very simple ethylene glycol mediated route. The two-step process involves the formation of glycolate nanoparticles and their subsequent hydrolysis and calcination to generate the final Ta2O5 nanospheres. The synthes...

  14. Degradation of Leakage Currents in Solid Tantalum Capacitors Under Steady-State Bias Conditions

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander A.

    2010-01-01

    Degradation of leakage currents in various types of solid tantalum capacitors under steady-state bias conditions was investigated at temperatures from 105 oC to 170 oC and voltages up to two times the rated voltage. Variations of leakage currents with time under highly accelerated life testing (HALT) and annealing, thermally stimulated depolarization currents, and I-V characteristics were measured to understand the conduction mechanism and the reason for current degradation. During HALT the currents increase gradually up to three orders of magnitude in some cases, and then stabilize with time. This degradation is reversible and annealing can restore the initial levels of leakage currents. The results are attributed to migration of positively charged oxygen vacancies in tantalum pentoxide films that diminish the Schottky barrier at the MnO2/Ta2O5 interface and increase electron injection. A simple model allows for estimation of concentration and mobility of oxygen vacancies based on the level of current degradation.

  15. 32 CFR 174.18 - Historic preservation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... REVITALIZING BASE CLOSURE COMMUNITIES AND ADDRESSING IMPACTS OF REALIGNMENT Environmental Matters § 174.18... planning and zoning actions undertaken by units of State or local government; if so, working with such...

  16. 32 CFR 174.18 - Historic preservation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... REVITALIZING BASE CLOSURE COMMUNITIES AND ADDRESSING IMPACTS OF REALIGNMENT Environmental Matters § 174.18... planning and zoning actions undertaken by units of State or local government; if so, working with such...

  17. 46 CFR 174.340 - Collision bulkhead.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments Design § 174.340 Collision bulkhead. Each hopper dredge must have a collision bulkhead that is located not less than 5...

  18. 46 CFR 174.340 - Collision bulkhead.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments Design § 174.340 Collision bulkhead. Each hopper dredge must have a collision bulkhead that is located not less than 5...

  19. 29 CFR 1952.174 - Completion of developmental steps and certification.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... approved: Authority to grant or deny temporary variances rests with the Division of Industrial Safety, and... Board hears appeals from the Division of Industrial Safety's decisions on temporary variances. (b) In....174 Section 1952.174 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH...

  20. 29 CFR 1952.174 - Completion of developmental steps and certification.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... approved: Authority to grant or deny temporary variances rests with the Division of Industrial Safety, and... Board hears appeals from the Division of Industrial Safety's decisions on temporary variances. (b) In....174 Section 1952.174 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH...

  1. 29 CFR 1952.174 - Completion of developmental steps and certification.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... approved: Authority to grant or deny temporary variances rests with the Division of Industrial Safety, and... Board hears appeals from the Division of Industrial Safety's decisions on temporary variances. (b) In....174 Section 1952.174 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH...

  2. 29 CFR 1952.174 - Completion of developmental steps and certification.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... approved: Authority to grant or deny temporary variances rests with the Division of Industrial Safety, and... Board hears appeals from the Division of Industrial Safety's decisions on temporary variances. (b) In....174 Section 1952.174 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH...

  3. 46 CFR 174.035 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling Units § 174.035 Definitions. (a... IA of this chapter: (1) Column stabilized unit. (2) Mobile offshore drilling unit. (3) Self-elevating... loaded or arranged for drilling, field transit, or ocean transit. (4) Severe storm condition means a...

  4. 46 CFR 174.035 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling Units § 174.035 Definitions. (a... IA of this chapter: (1) Column stabilized unit. (2) Mobile offshore drilling unit. (3) Self-elevating... loaded or arranged for drilling, field transit, or ocean transit. (4) Severe storm condition means a...

  5. 46 CFR 174.360 - Calculations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Dry Cargo Ships § 174.360 Calculations. Each ship to... for that ship by the International Convention for the Safety of Life at Sea, 1974, as amended, chapter...

  6. 40 CFR 265.174 - Inspections.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Management of Containers § 265.174 Inspections. At least weekly, the owner or operator must inspect areas where containers are stored, except for Performance Track member facilities, that must conduct..., the Performance Track member facility must follow the procedures described in § 265.15(b)(5) of this...

  7. 40 CFR 265.174 - Inspections.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Management of Containers § 265.174 Inspections. At least weekly, the owner or operator must inspect areas where containers are stored, except for Performance Track member facilities, that must conduct..., the Performance Track member facility must follow the procedures described in § 265.15(b)(5) of this...

  8. 40 CFR 265.174 - Inspections.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Management of Containers § 265.174 Inspections. At least weekly, the owner or operator must inspect areas where containers are stored, except for Performance Track member facilities, that must conduct..., the Performance Track member facility must follow the procedures described in § 265.15(b)(5) of this...

  9. 40 CFR 265.174 - Inspections.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Management of Containers § 265.174 Inspections. At least weekly, the owner or operator must inspect areas where containers are stored, except for Performance Track member facilities, that must conduct..., the Performance Track member facility must follow the procedures described in § 265.15(b)(5) of this...

  10. 40 CFR 265.174 - Inspections.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Management of Containers § 265.174 Inspections. At least weekly, the owner or operator must inspect areas where containers are stored, except for Performance Track member facilities, that must conduct..., the Performance Track member facility must follow the procedures described in § 265.15(b)(5) of this...

  11. 46 CFR 174.055 - Calculation of wind heeling moment (Hm).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Calculation of wind heeling moment (Hm). 174.055 Section 174.055 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling...

  12. 49 CFR 174.715 - Cleanliness of transport vehicles after use.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Cleanliness of transport vehicles after use. 174... RAIL Detailed Requirements for Class 7 (Radioactive) Materials § 174.715 Cleanliness of transport vehicles after use. (a) Each transport vehicle used for transporting Class 7 (radioactive) materials as...

  13. 49 CFR 174.715 - Cleanliness of transport vehicles after use.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Cleanliness of transport vehicles after use. 174... RAIL Detailed Requirements for Class 7 (Radioactive) Materials § 174.715 Cleanliness of transport vehicles after use. (a) Each transport vehicle used for transporting Class 7 (radioactive) materials as...

  14. 49 CFR 174.715 - Cleanliness of transport vehicles after use.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Cleanliness of transport vehicles after use. 174.715 Section 174.715 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS REGULATIONS CARRIAGE BY RAIL Detailed Requirements for Class 7 ...

  15. 46 CFR 160.174-9 - Construction.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... Each thermal protective aid must be constructed primarily of a durable insulating or heat reflecting material that meets the thermal insulation requirements in § 160.174-11(a). Each aid must be designed to...

  16. 46 CFR 160.174-9 - Construction.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    .... Each thermal protective aid must be constructed primarily of a durable insulating or heat reflecting material that meets the thermal insulation requirements in § 160.174-11(a). Each aid must be designed to...

  17. 46 CFR 160.174-9 - Construction.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    .... Each thermal protective aid must be constructed primarily of a durable insulating or heat reflecting material that meets the thermal insulation requirements in § 160.174-11(a). Each aid must be designed to...

  18. 46 CFR 160.174-9 - Construction.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .... Each thermal protective aid must be constructed primarily of a durable insulating or heat reflecting material that meets the thermal insulation requirements in § 160.174-11(a). Each aid must be designed to...

  19. 46 CFR 160.174-9 - Construction.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    .... Each thermal protective aid must be constructed primarily of a durable insulating or heat reflecting material that meets the thermal insulation requirements in § 160.174-11(a). Each aid must be designed to...

  20. 46 CFR 174.355 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Dry Cargo Ships § 174.355 Definitions. New ship means a... absence of a contract, the construction work of which is begun on or after August 1, 1992; or (iii) Which...

  1. Dissolution kinetics of small amounts of oxygen in tantalum alloy T-111 and internal oxide displacement reactions during annealing

    NASA Technical Reports Server (NTRS)

    Stecura, S.

    1976-01-01

    Oxygen was added to T-111 (Ta-8W-2Hf, wt. %) at 820 and 990 C at an oxygen pressure of about 0.0003 torr. The technique employed permitted predetermined and reproducible doping of T-111 up to 3.0 at. % oxygen. Based on the temperature dependence of the doping reaction, it is concluded that the initial rates of oxygen pickup are probably controlled by solution of oxygen into the T-111 lattice. Although hafnium oxides are more stable than those of tantalum or tungsten, analyses of extracted residues indicate that the latter oxides predominate in the as-doped specimens, presumably because of the higher concentrations of tantalum and tungsten in the alloy. However, high-temperature annealing promotes gettering of dissolved oxygen and of other oxides to form hafnium oxides. Small amounts of tantalum and tungsten oxides were still present after high-temperature annealing. Tungsten oxide (WO3) volatilizes slightly from the surface of T-111 at 990 C. The vaporization of WO3 has no apparent affect on the doping reaction.

  2. Evaluation of tantalum 316 stainless steel transition joints

    NASA Technical Reports Server (NTRS)

    Stoner, D. R.

    1972-01-01

    Tubular transition joints providing a metallurgically bonded connection between tantalum and 316 stainless steel pipe sections were comparatively evaluated for durability under thermal cycling conditions approximating the operation of a SNAP-8 mercury boiler. Both coextruded and vacuum brazed transition joints of 50mm (2 inch) diameter were tested by thermal cycling 100 times between 730 C and 120 C(1350 F and 250 F) in a high vacuum environment. The twelve evaluated transition joints survived the full test sequence without developing leaks, although liquid penetrant bond line indications eventually developed in all specimens. The brazed transition joints exhibited the best dimensional stability and bond line durability.

  3. 40 CFR 264.174 - Inspections.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Containers § 264.174 Inspections. At least weekly, the owner or operator must inspect areas where containers are stored, except for Performance Track member facilities, that may conduct inspections at least once... Track member facility must follow the procedures identified in § 264.15(b)(5) of this part. The owner or...

  4. 40 CFR 264.174 - Inspections.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Containers § 264.174 Inspections. At least weekly, the owner or operator must inspect areas where containers are stored, except for Performance Track member facilities, that may conduct inspections at least once... Track member facility must follow the procedures identified in § 264.15(b)(5) of this part. The owner or...

  5. 40 CFR 264.174 - Inspections.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Containers § 264.174 Inspections. At least weekly, the owner or operator must inspect areas where containers are stored, except for Performance Track member facilities, that may conduct inspections at least once... Track member facility must follow the procedures identified in § 264.15(b)(5) of this part. The owner or...

  6. 40 CFR 264.174 - Inspections.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Containers § 264.174 Inspections. At least weekly, the owner or operator must inspect areas where containers are stored, except for Performance Track member facilities, that may conduct inspections at least once... Track member facility must follow the procedures identified in § 264.15(b)(5) of this part. The owner or...

  7. 40 CFR 264.174 - Inspections.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Containers § 264.174 Inspections. At least weekly, the owner or operator must inspect areas where containers are stored, except for Performance Track member facilities, that may conduct inspections at least once... Track member facility must follow the procedures identified in § 264.15(b)(5) of this part. The owner or...

  8. 50 CFR 300.174 - Logbook reports.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Pacific Albacore Tuna Fisheries § 300.174 Logbook reports. The owner of any U.S. vessel that fishes for albacore tuna in Canadian waters under the Treaty as amended in 2002 must maintain and submit to the...

  9. 50 CFR 300.174 - Logbook reports.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Pacific Albacore Tuna Fisheries § 300.174 Logbook reports. The owner of any U.S. vessel that fishes for albacore tuna in Canadian waters under the Treaty as amended in 2002 must maintain and submit to the...

  10. 50 CFR 300.174 - Logbook reports.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Pacific Albacore Tuna Fisheries § 300.174 Logbook reports. The owner of any U.S. vessel that fishes for albacore tuna in Canadian waters under the Treaty as amended in 2002 must maintain and submit to the...

  11. 50 CFR 300.174 - Logbook reports.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Pacific Albacore Tuna Fisheries § 300.174 Logbook reports. The owner of any U.S. vessel that fishes for albacore tuna in Canadian waters under the Treaty as amended in 2002 must maintain and submit to the...

  12. 50 CFR 300.174 - Logbook reports.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Pacific Albacore Tuna Fisheries § 300.174 Logbook reports. The owner of any U.S. vessel that fishes for albacore tuna in Canadian waters under the Treaty as amended in 2002 must maintain and submit to the...

  13. 29 CFR 4.174 - Meeting requirements for holiday fringe benefits.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... contract, all employees who work during the first week would be entitled to holiday pay for that day. For... 29 Labor 1 2010-07-01 2010-07-01 true Meeting requirements for holiday fringe benefits. 4.174 Section 4.174 Labor Office of the Secretary of Labor LABOR STANDARDS FOR FEDERAL SERVICE CONTRACTS...

  14. 49 CFR 174.59 - Marking and placarding of rail cars.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Marking and placarding of rail cars. 174.59... RAIL General Handling and Loading Requirements § 174.59 Marking and placarding of rail cars. No person may transport a rail car carrying hazardous materials unless it is marked and placarded as required by...

  15. 49 CFR 174.59 - Marking and placarding of rail cars.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Marking and placarding of rail cars. 174.59... RAIL General Handling and Loading Requirements § 174.59 Marking and placarding of rail cars. No person may transport a rail car carrying hazardous materials unless it is marked and placarded as required by...

  16. 49 CFR 174.59 - Marking and placarding of rail cars.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Marking and placarding of rail cars. 174.59... RAIL General Handling and Loading Requirements § 174.59 Marking and placarding of rail cars. No person may transport a rail car carrying hazardous materials unless it is marked and placarded as required by...

  17. 49 CFR 174.59 - Marking and placarding of rail cars.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Marking and placarding of rail cars. 174.59... RAIL General Handling and Loading Requirements § 174.59 Marking and placarding of rail cars. No person may transport a rail car carrying hazardous materials unless it is marked and placarded as required by...

  18. 49 CFR 174.59 - Marking and placarding of rail cars.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Marking and placarding of rail cars. 174.59... RAIL General Handling and Loading Requirements § 174.59 Marking and placarding of rail cars. No person may transport a rail car carrying hazardous materials unless it is marked and placarded as required by...

  19. Studying tantalum-based high-κ dielectrics in terms of capacitance measurements

    NASA Astrophysics Data System (ADS)

    Stojanovska-Georgievska, L.

    2016-08-01

    The trend of rapid development of microelectronics towards nano-miniaturization dictates the inevitable introduction of dielectrics with high permittivity (high-κ dielectrics), as alternative material for replacing SiO2. Therefore, studying these materials in terms of their characteristics, especially in terms of reliability, is of great importance for proper design and manufacture of devices. In this paper, alteration of capacitance in different frequency regimes is used, in order to determine the overall behavior of the material. Samples investigated here are MOS structures containing nanoscale tantalum based dielectrics. Layers of pure Ta2O5, but also Hf and Ti doped tantalum pentoxide, i.e. Ta2O5:Hf and Ta2O5:Ti are studied here. All samples are considered as ultrathin oxide layers with thicknesses less than 15 nm, obtained by radio frequent sputtering on p-type silicon substrate. Measuring capacitive characteristics enables determination of several specific parameters of the structures. The obtained results for capacitance in accumulation, the thickness and time evolution of the interfacial SiO2 layer, values of flatband and threshold voltage, density of oxide charges, interfacial and border states, and reliability properties favor the possibilities for more intensive use of studied materials in new nanoelectronic technologies.

  20. 21 CFR 133.174 - Pasteurized process cheese food with fruits, vegetables, or meats.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ..., vegetables, or meats. 133.174 Section 133.174 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... Requirements for Specific Standardized Cheese and Related Products § 133.174 Pasteurized process cheese food... cheese food by § 133.173, except that: (1) Its milk fat content is not less than 22 percent. (2) It...

  1. 40 CFR 174.25 - Plant-incorporated protectant from sexually compatible plant.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Plant-incorporated protectant from sexually compatible plant. 174.25 Section 174.25 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS PROCEDURES AND REQUIREMENTS FOR PLANT-INCORPORATED PROTECTANTS Exemptions...

  2. 40 CFR 174.25 - Plant-incorporated protectant from sexually compatible plant.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Plant-incorporated protectant from sexually compatible plant. 174.25 Section 174.25 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS PROCEDURES AND REQUIREMENTS FOR PLANT-INCORPORATED PROTECTANTS Exemptions...

  3. 40 CFR 174.25 - Plant-incorporated protectant from sexually compatible plant.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Plant-incorporated protectant from sexually compatible plant. 174.25 Section 174.25 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS PROCEDURES AND REQUIREMENTS FOR PLANT-INCORPORATED PROTECTANTS Exemptions...

  4. 40 CFR 174.25 - Plant-incorporated protectant from sexually compatible plant.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Plant-incorporated protectant from sexually compatible plant. 174.25 Section 174.25 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS PROCEDURES AND REQUIREMENTS FOR PLANT-INCORPORATED PROTECTANTS Exemptions...

  5. 40 CFR 174.25 - Plant-incorporated protectant from sexually compatible plant.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Plant-incorporated protectant from sexually compatible plant. 174.25 Section 174.25 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS PROCEDURES AND REQUIREMENTS FOR PLANT-INCORPORATED PROTECTANTS Exemptions...

  6. Large area graphene ion sensitive field effect transistors with tantalum pentoxide sensing layers for pH measurement at the Nernstian limit

    NASA Astrophysics Data System (ADS)

    Fakih, Ibrahim; Sabri, Shadi; Mahvash, Farzaneh; Nannini, Matthieu; Siaj, Mohamed; Szkopek, Thomas

    2014-08-01

    We have fabricated and characterized large area graphene ion sensitive field effect transistors (ISFETs) with tantalum pentoxide sensing layers and demonstrated pH sensitivities approaching the Nernstian limit. Low temperature atomic layer deposition was used to deposit tantalum pentoxide atop large area graphene ISFETs. The charge neutrality point of graphene, inferred from quantum capacitance or channel conductance, was used to monitor surface potential in the presence of an electrolyte with varying pH. Bare graphene ISFETs exhibit negligible response, while graphene ISFETs with tantalum pentoxide sensing layers show increased sensitivity reaching up to 55 mV/pH over pH 3 through pH 8. Applying the Bergveld model, which accounts for site binding and a Guoy-Chapman-Stern picture of the surface-electrolyte interface, the increased pH sensitivity can be attributed to an increased buffer capacity reaching up to 1014 sites/cm2. ISFET response was found to be stable to better than 0.05 pH units over the course of two weeks.

  7. The plastic response of Tantalum in Quasi-Isentropic Compression Ramp and Release

    NASA Astrophysics Data System (ADS)

    Moore, Alexander; Brown, Justin; Lim, Hojun; Lane, J. Matthew D.

    2017-06-01

    The mechanical response of various forms of tantalum under extreme pressures and strain rates is studied using dynamic quasi-isentropic compression loading conditions in atomistic simulations. Ramp compression in bcc metals under these conditions tend to show a significant strengthening effect with increasing pressure; however, due to limitations of experimental methods in such regimes, the underlying physics for this phenomenon is not well understood. Molecular dynamics simulations provide important information about the plasticity mechanisms and can be used to investigate this strengthening. MD simulations are performed on nanocrystalline Ta and single crystal defective Ta with dislocations and point defects to uncover how the material responds and the underlying plasticity mechanisms. The different systems of solid Ta are seen to plastically deform through different mechanisms. Fundamental understanding of tantalum plasticity in these high pressure and strain rate regimes is needed to model and fully understand experimental results. Sandia National Labs is a multi program laboratory managed and operated by Sandia Corp., a wholly owned subsidiary of Lockheed Martin Corp., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  8. Effect of strain rate and dislocation density on the twinning behavior in Tantalum

    DOE PAGES

    Florando, Jeffrey N.; El-Dasher, Bassem S.; Chen, Changqiang; ...

    2016-04-28

    The conditions which affect twinning in tantalum have been investigated across a range of strain rates and initial dislocation densities. Tantalum samples were subjected to a range of strain rates, from 10 –4/s to 10 3/s under uniaxial stress conditions, and under laser-induced shock-loading conditions. In this study, twinning was observed at 77K at strain rates from 1/s to 103/s, and during laser-induced shock experiments. The effect of the initial dislocation density, which was imparted by deforming the material to different amounts of pre-strain, was also studied, and it was shown that twinning is suppressed after a given amount ofmore » pre-strain, even as the global stress continues to increase. These results indicate that the conditions for twinning cannot be represented solely by a critical global stress value, but are also dependent on the evolution of the dislocation density. Additionally, the analysis shows that if twinning is initiated, the nucleated twins may continue to grow as a function of strain, even as the dislocation density continues to increase.« less

  9. 46 CFR 160.174-15 - Instructions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... thermal protective aid and visible through a transparent storage case. The instructions must also be... COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Thermal Protective Aids § 160.174-15 Instructions. (a) Each...

  10. 46 CFR 174.055 - Calculation of wind heeling moment (Hm).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Calculation of wind heeling moment (Hm). 174.055 Section... Units § 174.055 Calculation of wind heeling moment (Hm). (a) The wind heeling moment (Hm) of a unit in a given normal operating condition or severe storm condition is the sum of the individual wind heeling...

  11. Direct observation of localized radial oxygen migration in functioning tantalum oxide memristors

    DOE PAGES

    Kumar, Suhas; Graves, Catherine E.; Strachan, John Paul; ...

    2016-02-02

    Oxygen migration in tantalum oxide, a promising next-generation storage material, is studied using in operando x-ray absorption spectromicroscopy and is used to microphysically describe accelerated evolution of conduction channel and device failure. Furthermore, the resulting ring-like patterns of oxygen concentration are modeled using thermophoretic forces and Fick diffusion, establishing the critical role of temperature-activated oxygen migration that has been under question lately.

  12. 46 CFR 160.174-23 - Marking.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... the Coast Guard approval number. (b) Each storage case must be marked with the words “Thermal... GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND APPROVAL LIFESAVING EQUIPMENT Thermal Protective Aids § 160.174-23 Marking. (a) Each thermal...

  13. Direction of Translation and Size of Bacteriophage φX174 Cistrons

    PubMed Central

    Benbow, Robert M.; Mayol, Robert F.; Picchi, Joanna C.; Sinsheimer, Robert L.

    1972-01-01

    Translation of the bacteriophage φX174 genome follows cistron order D-E-F-G-H-A-B-C. To establish this, the position of a nonsense mutation on the genetic map was compared with the physical size (molecular weight) of the appropriate protein fragment generated in nonpermissive cells. Distances on the φX174 genetic map and distances on a physical map constructed from the molecular weights of φX174 proteins and protein fragments are proportional over most of the genome with the exception of the high recombination region within cistron A. Images PMID:16789133

  14. 46 CFR 174.055 - Calculation of wind heeling moment (Hm).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... lateral resistance of the underwater hull to the center of wind pressure on “A”. (c) When calculating “A... 46 Shipping 7 2014-10-01 2014-10-01 false Calculation of wind heeling moment (Hm). 174.055 Section... Units § 174.055 Calculation of wind heeling moment (Hm). (a) The wind heeling moment (Hm) of a unit in a...

  15. 46 CFR 174.055 - Calculation of wind heeling moment (Hm).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... lateral resistance of the underwater hull to the center of wind pressure on “A”. (c) When calculating “A... 46 Shipping 7 2012-10-01 2012-10-01 false Calculation of wind heeling moment (Hm). 174.055 Section... Units § 174.055 Calculation of wind heeling moment (Hm). (a) The wind heeling moment (Hm) of a unit in a...

  16. 26 CFR 1.174-1 - Research and experimental expenditures; in general.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... (continued) § 1.174-1 Research and experimental expenditures; in general. Section 174 provides two methods for treating research or experimental expenditures paid or incurred by the taxpayer in connection with... 26 Internal Revenue 3 2010-04-01 2010-04-01 false Research and experimental expenditures; in...

  17. 26 CFR 1.174-2 - Definition of research and experimental expenditures.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 3 2013-04-01 2013-04-01 false Definition of research and experimental... Corporations (continued) § 1.174-2 Definition of research and experimental expenditures. (a) In general. (1) The term research or experimental expenditures, as used in section 174, means expenditures incurred in...

  18. 26 CFR 1.174-2 - Definition of research and experimental expenditures.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 3 2014-04-01 2014-04-01 false Definition of research and experimental... Corporations (continued) § 1.174-2 Definition of research and experimental expenditures. (a) In general. (1) The term research or experimental expenditures, as used in section 174, means expenditures incurred in...

  19. 26 CFR 1.174-2 - Definition of research and experimental expenditures.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 3 2010-04-01 2010-04-01 false Definition of research and experimental... (continued) § 1.174-2 Definition of research and experimental expenditures. (a) In general. (1) The term research or experimental expenditures, as used in section 174, means expenditures incurred in connection...

  20. 26 CFR 1.174-2 - Definition of research and experimental expenditures.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 3 2012-04-01 2012-04-01 false Definition of research and experimental... Corporations (continued) § 1.174-2 Definition of research and experimental expenditures. (a) In general. (1) The term research or experimental expenditures, as used in section 174, means expenditures incurred in...

  1. 26 CFR 1.174-2 - Definition of research and experimental expenditures.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 3 2011-04-01 2011-04-01 false Definition of research and experimental... Corporations (continued) § 1.174-2 Definition of research and experimental expenditures. (a) In general. (1) The term research or experimental expenditures, as used in section 174, means expenditures incurred in...

  2. 47 CFR 15.241 - Operation in the band 174-216 MHz.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Operation in the band 174-216 MHz. 15.241 Section 15.241 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Intentional Radiators Radiated Emission Limits, Additional Provisions § 15.241 Operation in the band 174-216...

  3. 46 CFR 174.040 - Stability requirements: general.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling Units § 174.040... draft for navigation, towing, or drilling afloat, or at a temporary draft when changing drafts. ...

  4. 46 CFR 174.040 - Stability requirements: general.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling Units § 174.040... draft for navigation, towing, or drilling afloat, or at a temporary draft when changing drafts. ...

  5. 25 CFR 224.174 - When does a voluntary rescission become effective?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 25 Indians 1 2011-04-01 2011-04-01 false When does a voluntary rescission become effective? 224.174 Section 224.174 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR ENERGY AND MINERALS TRIBAL ENERGY RESOURCE AGREEMENTS UNDER THE INDIAN TRIBAL ENERGY DEVELOPMENT AND SELF DETERMINATION ACT...

  6. 25 CFR 224.174 - When does a voluntary rescission become effective?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false When does a voluntary rescission become effective? 224.174 Section 224.174 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR ENERGY AND MINERALS TRIBAL ENERGY RESOURCE AGREEMENTS UNDER THE INDIAN TRIBAL ENERGY DEVELOPMENT AND SELF DETERMINATION ACT...

  7. 46 CFR 174.007 - Incorporation by reference.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... are: American Society for Testing and Materials (ASTM) 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959. ASTM F 1196-94, Standard Specification for Sliding Watertight Door Assemblies—174.100 ASTM F...

  8. PHYSICAL VAPOR DEPOSITION OF TANTALUM ON GUN BARREL STEEL (SYSTEMS ANLAYSIS BRANCH, SUSTAINABLE TECHNOLOGY DIVISION, NRMRL)

    EPA Science Inventory

    This project entails the development of an alternative technology for plating gun barrel steel to replace the process electroplating of chrome (Cr-electroplate) with physical vapor deposition of tantalum (Ta-PVD). Developed by Benet Laboratory at Watervliet Arsenal, this project'...

  9. A proposed CT contrast agent using carboxybetaine zwitterionic tantalum oxide nanoparticles: Imaging, biological, and physicochemical performance

    PubMed Central

    FitzGerald, Paul F.; Butts, Matthew D.; Roberts, Jeannette C.; Colborn, Robert E.; Torres, Andrew S.; Lee, Brian D.; Yeh, Benjamin M.; Bonitatibus, Peter J.

    2016-01-01

    Objectives To produce and evaluate a proposed computed tomography (CT) contrast agent based on carboxybetaine zwitterionic (CZ) coated soluble tantalum oxide nanoparticles (CZ-TaO NPs). We chose tantalum to provide superior imaging performance compared to current iodine-based clinical CT contrast agents. We developed the CZ coating to provide biological and physical performance similar to that of current iodinated contrast agents. The aim of this study was to evaluate the imaging, biological, and physicochemical performance of this proposed contrast agent compared to clinically-used iodinated agents. Materials and Methods We evaluated CT imaging performance of our CZ-TaO NPs compared to an iodinated agent in live rats, imaged centrally-located within a tissue-equivalent plastic phantom that simulated a large patient. To evaluate vascular contrast enhancement, we scanned the rats’ great vessels at high temporal resolution during and following contrast agent injection. We performed several in vivo CZ-TaO NP studies in healthy rats to evaluate tolerability. These studies included injecting the agent at the anticipated clinical dose (ACD) and at 3 times and 6 times the ACD, followed by longitudinal hematology to assess impact to blood cells and organ function (from 4 hours to 1 week). Kidney histological analysis was performed 48 hours after injection at 3 times the ACD. We measured the elimination half-life of CZ-TaO NPs from blood, and we monitored acute kidney injury biomarkers with a kidney injury assay using urine collected from 4 hours to 1 week. We measured tantalum retention in individual organs and in the whole carcass 48 hours after injection at ACD. CZ-TaO NPs were synthesized and analyzed in detail. We used multi-dimensional nuclear magnetic resonance (NMR) to determine surface functionality of the nanoparticles. We measured nanoparticle size and solution properties (osmolality and viscosity) of the agent over a range of tantalum concentrations, including

  10. Isolation of tungsten and tantalum isotopes without supports from. cap alpha. -particle-irradiated hafnium targets

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

    Gasita, S.M.; Iota, B.Z.; Malachkov, A.G.

    1985-11-01

    An extraction procedure has been developed for successive isolation of tungsten (/sup 178/W and /sup 181/W) and tantalum (/sup 179/Ta and /sup 182/Ta) isotopes without supports from ..cap alpha..particle-irradiated hafnium targets. The target, irradiated on a cyclotron, is dissolved in hydrofluoric acid. Tantalum isotopes are extracted with tributyl phosphate (TBP) from 1-5 M HF and are then reextracted with a 1:1 ammonia solution, and hydrofluoric acid is removed by heating. Tungsten isotopes are extracted with a chloroform solution or N-benzoyl-N-phenylhydroxylamine (BPHA) from 11-12 M H/sub 2/SO/sub 4/ or ..cap alpha..-benzoin oxime from 4.5-5.5 M H/sub 2/SO/sub 4/ and are thenmore » reextracted with a l:l ammonia solution. The yield of tungsten isotopes is not less than 95%, and the content of radioactive impurities of other isotopes is not more than 0.1%.« less

  11. 40 CFR 205.174 - Remedial orders.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... calibrated with the acoustic calibrator as often as is necessary throughout testing to maintain the accuracy... TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycle Exhaust Systems § 205.174 Remedial orders. The... Noise Emission Test Procedures Appendix I-1 to Subparts D and E—Test Procedure for Street and off-road...

  12. 46 CFR 174.335 - Watertight doors.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments Design § 174.335 Watertight doors. (a) Each hopper dredge must have sliding watertight doors (Class 3) approved under § 170.270 of this... to and including the maximum amount of assumed damage. (b) Each hopper dredge must have sliding...

  13. 46 CFR 174.335 - Watertight doors.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... SPECIFIC VESSEL TYPES Hopper Dredges With Working Freeboard Assignments Design § 174.335 Watertight doors. (a) Each hopper dredge must have sliding watertight doors (Class 3) approved under § 170.270 of this... to and including the maximum amount of assumed damage. (b) Each hopper dredge must have sliding...

  14. Large area graphene ion sensitive field effect transistors with tantalum pentoxide sensing layers for pH measurement at the Nernstian limit

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

    Fakih, Ibrahim, E-mail: ibrahim.fakih@mail.mcgill.ca; Sabri, Shadi; Szkopek, Thomas, E-mail: thomas.szkopek@mcgill.ca

    2014-08-25

    We have fabricated and characterized large area graphene ion sensitive field effect transistors (ISFETs) with tantalum pentoxide sensing layers and demonstrated pH sensitivities approaching the Nernstian limit. Low temperature atomic layer deposition was used to deposit tantalum pentoxide atop large area graphene ISFETs. The charge neutrality point of graphene, inferred from quantum capacitance or channel conductance, was used to monitor surface potential in the presence of an electrolyte with varying pH. Bare graphene ISFETs exhibit negligible response, while graphene ISFETs with tantalum pentoxide sensing layers show increased sensitivity reaching up to 55 mV/pH over pH 3 through pH 8. Applying themore » Bergveld model, which accounts for site binding and a Guoy-Chapman-Stern picture of the surface-electrolyte interface, the increased pH sensitivity can be attributed to an increased buffer capacity reaching up to 10{sup 14} sites/cm{sup 2}. ISFET response was found to be stable to better than 0.05 pH units over the course of two weeks.« less

  15. Verification of conventional equations of state for tantalum under quasi-isentropic compression

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

    Binqiang, Luo; Guiji, Wang; Jianjun, Mo

    2014-11-21

    Shock Hugoniot data have been widely used to calibrate analytic equations of state (EOSs) of condensed matter at high pressures. However, the suitability of particular analytic EOSs under off-Hugoniot states has not been sufficiently verified using experimental data. We have conducted quasi-isentropic compression experiments (ICEs) of tantalum using the compact pulsed power generator CQ-4, and explored the relation of longitudinal stress versus volume of tantalum under quasi-isentropic compression using backward integration and characteristic inverse methods. By subtracting the deviatoric stress and additional pressure caused by irreversible plastic dissipation, the isentropic pressure can be extracted from the longitudinal stress. Several theoreticalmore » isentropes are deduced from analytic EOSs and compared with ICE results to validate the suitability of these analytic EOSs in isentropic compression states. The comparisons show that the Gruneisen EOS with Gruneisen Gamma proportional to volume is accurate, regardless whether the Hugoniot or isentrope is used as the reference line. The Vinet EOS yields better accuracy in isentropic compression states. Theoretical isentropes derived from Tillotson, PUFF, and Birch-Murnaghan EOSs well agree with the experimental isentrope in the range of 0–100 GPa, but deviate gradually with pressure increasing further.« less

  16. 46 CFR 174.220 - Hatches and coamings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Offshore Supply Vessels § 174.220 Hatches and... securing-devices; and (2) Be attached to the hatch frame or coaming by hinges, captive chains, or other...

  17. 46 CFR 174.220 - Hatches and coamings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Offshore Supply Vessels § 174.220 Hatches and... securing-devices; and (2) Be attached to the hatch frame or coaming by hinges, captive chains, or other...

  18. 46 CFR 174.220 - Hatches and coamings.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Offshore Supply Vessels § 174.220 Hatches and... securing-devices; and (2) Be attached to the hatch frame or coaming by hinges, captive chains, or other...

  19. 46 CFR 174.220 - Hatches and coamings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Offshore Supply Vessels § 174.220 Hatches and... securing-devices; and (2) Be attached to the hatch frame or coaming by hinges, captive chains, or other...

  20. 46 CFR 174.220 - Hatches and coamings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Offshore Supply Vessels § 174.220 Hatches and... securing-devices; and (2) Be attached to the hatch frame or coaming by hinges, captive chains, or other...

  1. 21 CFR 174.6 - Threshold of regulation for substances used in food-contact articles.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Threshold of regulation for substances used in food-contact articles. 174.6 Section 174.6 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH... § 174.6 Threshold of regulation for substances used in food-contact articles. Substances used in food...

  2. M551 metals melting experiment. [space manufacturing of aluminum alloys, tantalum alloys, stainless steels

    NASA Technical Reports Server (NTRS)

    Li, C. H.; Busch, G.; Creter, C.

    1976-01-01

    The Metals Melting Skylab Experiment consisted of selectively melting, in sequence, three rotating discs made of aluminum alloy, stainless steel, and tantalum alloy. For comparison, three other discs of the same three materials were similarly melted or welded on the ground. The power source of the melting was an electron beam unit. Results are presented which support the concept that the major difference between ground base and Skylab samples (i.e., large elongated grains in ground base samples versus nearly equiaxed and equal sized grains in Skylab samples) can be explained on the basis of constitutional supercooling, and not on the basis of surface phenomena. Microstructural observations on the weld samples and present explanations for some of these observations are examined. In particular, ripples and their implications to weld solidification were studied. Evidence of pronounced copper segregation in the Skylab A1 weld samples, and the tantalum samples studied, indicates a weld microhardness (and hence strength) that is uniformly higher than the ground base results, which is in agreement with previous predictions. Photographs are shown of the microstructure of the various alloys.

  3. A fully decompressed synthetic bacteriophage øX174 genome assembled and archived in yeast.

    PubMed

    Jaschke, Paul R; Lieberman, Erica K; Rodriguez, Jon; Sierra, Adrian; Endy, Drew

    2012-12-20

    The 5386 nucleotide bacteriophage øX174 genome has a complicated architecture that encodes 11 gene products via overlapping protein coding sequences spanning multiple reading frames. We designed a 6302 nucleotide synthetic surrogate, øX174.1, that fully separates all primary phage protein coding sequences along with cognate translation control elements. To specify øX174.1f, a decompressed genome the same length as wild type, we truncated the gene F coding sequence. We synthesized DNA encoding fragments of øX174.1f and used a combination of in vitro- and yeast-based assembly to produce yeast vectors encoding natural or designer bacteriophage genomes. We isolated clonal preparations of yeast plasmid DNA and transfected E. coli C strains. We recovered viable øX174 particles containing the øX174.1f genome from E. coli C strains that independently express full-length gene F. We expect that yeast can serve as a genomic 'drydock' within which to maintain and manipulate clonal lineages of other obligate lytic phage. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. Effect of strain rate and dislocation density on the twinning behavior in tantalum

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

    Florando, Jeffrey N., E-mail: florando1@llnl.gov; Swift, Damian C.; Barton, Nathan R.

    2016-04-15

    The conditions which affect twinning in tantalum have been investigated across a range of strain rates and initial dislocation densities. Tantalum samples were subjected to a range of strain rates, from 10{sup −4}/s to 10{sup 3}/s under uniaxial stress conditions, and under laser-induced shock-loading conditions. In this study, twinning was observed at 77 K at strain rates from 1/s to 10{sup 3}/s, and during laser-induced shock experiments. The effect of the initial dislocation density, which was imparted by deforming the material to different amounts of pre-strain, was also studied, and it was shown that twinning is suppressed after a givenmore » amount of pre-strain, even as the global stress continues to increase. These results indicate that the conditions for twinning cannot be represented solely by a critical global stress value, but are also dependent on the evolution of the dislocation density. In addition, the analysis shows that if twinning is initiated, the nucleated twins may continue to grow as a function of strain, even as the dislocation density continues to increase.« less

  5. 21 CFR 174.6 - Threshold of regulation for substances used in food-contact articles.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Threshold of regulation for substances used in food-contact articles. 174.6 Section 174.6 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: GENERAL § 174.6 Threshold of regulation for...

  6. 21 CFR 174.6 - Threshold of regulation for substances used in food-contact articles.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Threshold of regulation for substances used in food-contact articles. 174.6 Section 174.6 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) INDIRECT FOOD ADDITIVES: GENERAL § 174.6 Threshold of regulation for substances used in food-contact articles....

  7. 21 CFR 174.6 - Threshold of regulation for substances used in food-contact articles.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Threshold of regulation for substances used in food-contact articles. 174.6 Section 174.6 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: GENERAL § 174.6 Threshold of regulation for...

  8. 21 CFR 174.6 - Threshold of regulation for substances used in food-contact articles.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Threshold of regulation for substances used in food-contact articles. 174.6 Section 174.6 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: GENERAL § 174.6 Threshold of regulation for...

  9. 49 CFR 174.83 - Switching placarded rail cars, transport vehicles, freight containers, and bulk packagings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., freight containers, and bulk packagings. 174.83 Section 174.83 Transportation Other Regulations Relating... Vehicles and Freight Containers § 174.83 Switching placarded rail cars, transport vehicles, freight containers, and bulk packagings. (a) In switching operations where the use of hand brakes is necessary— (1...

  10. 49 CFR 174.83 - Switching placarded rail cars, transport vehicles, freight containers, and bulk packagings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., freight containers, and bulk packagings. 174.83 Section 174.83 Transportation Other Regulations Relating... Vehicles and Freight Containers § 174.83 Switching placarded rail cars, transport vehicles, freight containers, and bulk packagings. (a) In switching operations where the use of hand brakes is necessary— (1...

  11. 49 CFR 174.83 - Switching placarded rail cars, transport vehicles, freight containers, and bulk packagings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., freight containers, and bulk packagings. 174.83 Section 174.83 Transportation Other Regulations Relating... Vehicles and Freight Containers § 174.83 Switching placarded rail cars, transport vehicles, freight containers, and bulk packagings. (a) In switching operations where the use of hand brakes is necessary— (1...

  12. 49 CFR 174.83 - Switching placarded rail cars, transport vehicles, freight containers, and bulk packagings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., freight containers, and bulk packagings. 174.83 Section 174.83 Transportation Other Regulations Relating... Vehicles and Freight Containers § 174.83 Switching placarded rail cars, transport vehicles, freight containers, and bulk packagings. (a) In switching operations where the use of hand brakes is necessary— (1...

  13. 49 CFR 174.83 - Switching placarded rail cars, transport vehicles, freight containers, and bulk packagings.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., freight containers, and bulk packagings. 174.83 Section 174.83 Transportation Other Regulations Relating... Vehicles and Freight Containers § 174.83 Switching placarded rail cars, transport vehicles, freight containers, and bulk packagings. (a) In switching operations where the use of hand brakes is necessary— (1...

  14. In vivo comparison of tantalum, tungsten, and bismuth enteric contrast agents to complement intravenous iodine for double-contrast dual-energy CT of the bowel

    PubMed Central

    Rathnayake, Samira; Mongan, John; Torres, Andrew S.; Colborn, Robert; Gao, Dong-Wei; Yeh, Benjamin M; Fu, Yanjun

    2016-01-01

    To assess the ability of dual-energy CT (DECT) to separate intravenous contrast of bowel wall from intraluminal contrast, we scanned 16 rabbits on a clinical DECT scanner: n=3 using only iodinated intravenous contrast; and n=13 double-contrast enhanced scans using iodinated intravenous contrast and experimental enteric non-iodinated contrast agents in the bowel lumen (5 bismuth-, 4 tungsten-, and 4 tantalum-based). Representative image pairs from conventional CT images and DECT iodine density maps of small bowel (116 pairs from 232 images) were viewed by four abdominal imaging attending radiologists to independently score each comparison pair on a visual analog scale (−100 to +100%) for: 1) preference in small bowel wall visualization; and 2) preference in completeness of intraluminal enteric contrast subtraction. Median small bowel wall visualization was scored 39 and 42 percentage points (95% CI: 30–44% and 36–45%, p<0.001 both) higher at double-contrast DECT than at conventional CT with enteric tungsten and tantalum contrast, respectively. Median small bowel wall visualization at double-contrast DECT was scored 29 and 35 percentage points (95% CI: 20–35% and 33–39%, p<0.001 both) higher with enteric tungsten and tantalum, respectively, than with bismuth contrast. Median completeness of intraluminal enteric contrast subtraction in double-contrast DECT iodine density maps was scored 28 and 29 percentage points (95% CI: 15–31% and 28–33%, p<0.001 both) higher with enteric tungsten and tantalum, respectively, than with bismuth contrast. Results suggest that in vivo double-contrast DECT with iodinated intravenous and either tantalum- or tungsten-based enteric contrast provide better visualization of small bowel than conventional CT. PMID:26892945

  15. Flash melting of tantalum in a diamond cell to 85 GPa

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

    Karandikar, Amol; Boehler, Reinhard

    2016-02-09

    Here, we demonstrate a new level of precision in measuring melting temperatures at high pressure using laser flash-heating followed by Scanning Electron Microscopy and Focused Ion Beam Milling. Furthermore, the new measurements on tantalum put unprecedented constraints on its highly debated melting slope, calling for a reevaluation of theoretical, shock compression and diamond cell approaches to determine melting at high pressure. X-ray analysis of the recovered samples confirmed the absence of chemical reactions, which likely played a significant role in previous experiments.

  16. Effects of the [OC6F5] moiety upon structural geometry: crystal structures of half-sandwich tantalum(V) aryloxide complexes from reaction of Cp*Ta(N(t)Bu)(CH2R)2 with pentafluorophenol.

    PubMed

    Cole, Jacqueline M; Chan, Michael C W; Gibson, Vernon C; Howard, Judith A K

    2011-10-01

    The synthesis, chemical and structural characterization of a series of pentamethylcyclopentadienyl (Cp*) tantalum imido complexes and aryloxide derivatives are presented. Specifically, the imido complexes Cp*Ta(N(t)Bu)(CH(2)R)(2), where R = Ph [dibenzyl(tert-butylamido) (η(5)-pentamethylcyclopentadienyl)tantalum(IV) (1)], Me(2)Ph [tert-butylamido)bis(2-methyl-2-phenylpropyl) (η(5)-pentamethylcyclopentadienyl)tantalum(IV) (2)], CMe(3) [(tert-butylamido)bis(2,2-dimethylpropyl) (η(5)-pentamethylcyclopentadienyl)tantalum(IV) (3)], are reported. The crystal structure of (3) reveals α-agostic interactions with the Ta atom. The resulting increase in the tantalum core coordination improves electronic stability. As such it does not react with pentafluorophenol, in contrast to the other two reported imido complexes [(1) and (2)]. Addition of C(6)F(5)OH to (1) yields a dimeric aryl-oxide derivative, [Cp*Ta(CH(2)Ph)(OC(6)H(5))(μ-O)](2) [di-μ-oxido-bis[benzyl(pentafluorophenolato) (η(5)-pentamethylcyclopentadienyl)tantalum(V)] (4)]. Its crystal structure reveals long Ta-O(C(6)H(5)) bonds but short oxo-bridging Ta-O bonds. This is explained by accounting for the fierce electronic competition for the vacant d(π) orbitals of the electrophilic Ta(V) centre. Steric congestion around each metal is alleviated by a large twist angle (77.1°) between the benzyl and pentafluorophenyl ligands and the ordering of each of these groups into stacked pairs. The imido complex (2) reacts with C(6)F(5)OH to produce a mixture of Cp*Ta(OC(6)F(5))(4) [tetrakis(pentafluorophenolato)(η(5)-pentamethylcyclopentadienyl)tantalum(V) (5)] and [Cp*Ta(OC(6)F(5))(2)(μ-O)](2) [di-μ-oxido-bis[bis(pentafluorophenolato)(η(5)-pentamethylcyclopentadienyl)tantalum(V)] (6)]. Steric congestion is offset in both cases by the twisting of its pentafluorophenyl ligands. Particularly strong electronic competition for the empty d(π) metal orbitals in (6) is reflected in its bond geometry, and owes itself to the

  17. Modified porous tantalum rod technique for the treatment of femoral head osteonecrosis

    PubMed Central

    Pakos, Emilios E; Megas, Panayiotis; Paschos, Nikolaos K; Syggelos, Spyridon A; Kouzelis, Antonios; Georgiadis, Georgios; Xenakis, Theodoros A

    2015-01-01

    AIM: To study a modified porous tantalum technique for the treatment of osteonecrosis of the femoral head. METHODS: The porous tantalum rod was combined with endoscopy, curettage, autologous bone grafting and use of bone marrow aspirates from iliac crest aspiration in 49 patients (58 hips) with a mean age of 38 years. The majority of the patients had idiopathic osteonecrosis, followed by corticosteroid-induced osteonecrosis. Thirty-eight hips were of Steinberg stage II disease and 20 hips were of stage III disease. Patients were followed for 5 years and were evaluated clinically with the Merle D’Aubigne and Postel score and radiologically. The primary outcome of the study was survival based on the conversion to total hip arthroplasty (THA). Secondary outcomes included deterioration of the osteonecrosis to a higher disease stage at 5 years compared to the preoperative period and identification of factors that were associated with survival. The Kaplan-Meier survival analysis was performed to evaluate the survivorship of the prosthesis, and the Fisher exact test was performed to test associations between various parameters with survival. RESULTS: No patient developed any serious intraoperative or postoperative complication including implant loosening or migration and donor site morbidity. During the 5-year follow up, 1 patient died, 7 patients had disease progression and 4 hips were converted to THA. The 5-year survival based on conversion to THA was 93.1% and the respective rate based on disease progression was 87.9%. Stage II disease was associated with statistically significant better survival rates compared to stage III disease (P = 0.04). The comparison between idiopathic and non-idiopathic osteonecrosis and between steroid-induced and non-steroid-induced osteonecrosis did not showed any statistically significant difference in survival rates. The clinical evaluation revealed statistically significantly improved Merle d’Aubigne scores at 12 mo postoperatively

  18. Modified porous tantalum rod technique for the treatment of femoral head osteonecrosis.

    PubMed

    Pakos, Emilios E; Megas, Panayiotis; Paschos, Nikolaos K; Syggelos, Spyridon A; Kouzelis, Antonios; Georgiadis, Georgios; Xenakis, Theodoros A

    2015-11-18

    To study a modified porous tantalum technique for the treatment of osteonecrosis of the femoral head. The porous tantalum rod was combined with endoscopy, curettage, autologous bone grafting and use of bone marrow aspirates from iliac crest aspiration in 49 patients (58 hips) with a mean age of 38 years. The majority of the patients had idiopathic osteonecrosis, followed by corticosteroid-induced osteonecrosis. Thirty-eight hips were of Steinberg stage II disease and 20 hips were of stage III disease. Patients were followed for 5 years and were evaluated clinically with the Merle D'Aubigne and Postel score and radiologically. The primary outcome of the study was survival based on the conversion to total hip arthroplasty (THA). Secondary outcomes included deterioration of the osteonecrosis to a higher disease stage at 5 years compared to the preoperative period and identification of factors that were associated with survival. The Kaplan-Meier survival analysis was performed to evaluate the survivorship of the prosthesis, and the Fisher exact test was performed to test associations between various parameters with survival. No patient developed any serious intraoperative or postoperative complication including implant loosening or migration and donor site morbidity. During the 5-year follow up, 1 patient died, 7 patients had disease progression and 4 hips were converted to THA. The 5-year survival based on conversion to THA was 93.1% and the respective rate based on disease progression was 87.9%. Stage II disease was associated with statistically significant better survival rates compared to stage III disease (P = 0.04). The comparison between idiopathic and non-idiopathic osteonecrosis and between steroid-induced and non-steroid-induced osteonecrosis did not showed any statistically significant difference in survival rates. The clinical evaluation revealed statistically significantly improved Merle d'Aubigne scores at 12 mo postoperatively compared to the

  19. 27 CFR 41.174 - Disposition of tobacco products and cigarette papers and tubes, and schedule.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... products and cigarette papers and tubes, and schedule. 41.174 Section 41.174 Alcohol, Tobacco Products and... IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Claims Tobacco Products and Cigarette Papers and Tubes Withdrawn from the Market § 41.174 Disposition of tobacco products and cigarette...

  20. 27 CFR 41.174 - Disposition of tobacco products and cigarette papers and tubes, and schedule.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... products and cigarette papers and tubes, and schedule. 41.174 Section 41.174 Alcohol, Tobacco Products and... IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Claims Tobacco Products and Cigarette Papers and Tubes Withdrawn from the Market § 41.174 Disposition of tobacco products and cigarette...