WorldWideScience

Sample records for tantalum 188

  1. Vapor deposition of tantalum and tantalum compounds

    International Nuclear Information System (INIS)

    Trkula, M.

    1996-01-01

    Tantalum, and many of its compounds, can be deposited as coatings with techniques ranging from pure, thermal chemical vapor deposition to pure physical vapor deposition. This review concentrates on chemical vapor deposition techniques. The paper takes a historical approach. The authors review classical, metal halide-based techniques and current techniques for tantalum chemical vapor deposition. The advantages and limitations of the techniques will be compared. The need for new lower temperature processes and hence new precursor chemicals will be examined and explained. In the last section, they add some speculation as to possible new, low-temperature precursors for tantalum chemical vapor deposition

  2. Niobium and tantalum

    Science.gov (United States)

    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

  3. Tantalum markers in radiography

    International Nuclear Information System (INIS)

    Aronson, A.S.; Jonsson, N.; Alberius, P.

    1985-01-01

    The biocompatibility of two types of radiopaque tantalum markers was evaluated histologically. Reactions to pin markers (99.9% purity) and spherical markers (95.2% purity) were investigated after 3-6 weeks in rabbits and 5-48 weeks in children with abnormal growth. Both marker types were firmly attached to bone trabeculae; this was most pronounced in rabbit bone, and no adverse macroscopic reactions were observed. Microscopically, no reactions or only slight fibrosis of bone tissue were detected, while soft tissues only demonstrated a minor inflammatory reaction. Nevertheless, the need for careful preparation and execution of marker implantations is stressed, and particularly avoidance iof the use of emery in sharpening of cannulae. The bioinertness of tantalum was reconfirmed as was its suitability for use as skeletal and soft tissue radiographic markers. (orig.)

  4. Chromatographic 188W →188Re generator

    International Nuclear Information System (INIS)

    Khujaev, S.

    2005-01-01

    Full text: The main purpose of the generator - reception of daughter radioisotope Rhenium-188 from it by periodic elution for a long period of time (more than half-year). It is generally known that Rhenium-188, in the form of its complex connections, is applied in nuclear medicine in treatment and removal of painful syndromes. The generator possesses convenient nuclear-physical characteristics of a daughter radioisotope Rhenium-188. It is a source of (Irradiation with energy 2.12 MeV (98 %) with small contribution soft γ-radiation with energy 0.155 MeV (15 %). The Period of half-life destruction of radioisotope is 17 hours. The 188 W parent radioisotope for the generator is formed by irradiation of 186 W neutrons based on the following reaction: 186 W (n,γ) 187 W (n,γ) 188 W (69 days) → 188 Re (17 hours) + β The following were used as targets for irradiation: 1) Metal Tungsten (powder) of natural structure; 2) Metal Tungsten (plate) of natural structure; 3) Metal Tungsten (wire) of natural structure, d = 12 mm; 4) Metal Tungsten (powder) with enrichment on isotope 186 W - 99.79 %. The irradiated material was exposed to chemical processing with reception of radioactive solution of tungsten-188, from which sorption Tungsten was carried out onto sorbent as poly-wolframate-ions. It is established that Tungsten sorption depends on many factors as there are various chemical forms of Tungsten (VI) in water solutions, ratio of which depends on pH of the solution, concentration of Tungsten in the solution and presence of foreign ions. Tungsten sorption was carried out in static and in dynamic regimes. At dynamic regime the sorbent was placed directly in the generating column. The generator consisted of chromatographic columns with sorbent and radioisotope 188 W, eluting system and radiation protection. Rhenium-188 was taken from the generator as perrhenate sodium by elution of 0.9 % solution of chloride sodium in 10 ml. Technical characteristics of the generator

  5. Niobium and tantalum

    International Nuclear Information System (INIS)

    Polupanova, L.I.; Volkova, G.A.

    1983-01-01

    General mineralogical-geochemical and analytical characteristics of niobium and tantalum are presented. Potentialities of any analytical methods for determining these elements in various geologic samples are estimated. The following specific techniques are described: neutron + activation determination of Ta, fluorescence X-radiometric determination of Nb and Ta, fluorescence X-ray spectral determination of Nb and Ta, spectrographic determination of Nb and Ta, gravimetric determination of Nb and Ta, their extraction-photometric determination with various reagents (crystal violet, rhodamine 6 Y, butylrhodamine B)

  6. Hydride Olefin complexes of tantalum and niobium

    NARCIS (Netherlands)

    Klazinga, Aan Hendrik

    1979-01-01

    This thesis describes investigations on low-valent tantalum and niobium hydride and alkyl complexes, particularly the dicyclopentadienyl tantalum hydride olefin complexes Cp2Ta(H)L (L=olefin). ... Zie: Summary

  7. 188W/188Re Generator System and Its Therapeutic Applications

    Directory of Open Access Journals (Sweden)

    A. Boschi

    2014-01-01

    Full Text Available The 188Re radioisotope represents a useful radioisotope for the preparation of radiopharmaceuticals for therapeutic applications, particularly because of its favorable nuclear properties. The nuclide decay pattern is through the emission of a principle beta particle having 2.12 MeV maximum energy, which is enough to penetrate and destroy abnormal tissues, and principle gamma rays (Eγ=155 keV, which can efficiently be used for imaging and calculations of radiation dose. 188Re may be conveniently produced by 188W/188Re generator systems. The challenges related to the double neutron capture reaction route to provide only modest yield of the parent 188W radionuclide indeed have been one of the major issues about the use of 188Re in nuclear medicine. Since the specific activity of 188W used in the generator is relatively low (<185 GBq/g, the eluted Re188O4- can have a low radioactive concentration, often ineffective for radiopharmaceutical preparation. However, several efficient postelution concentration techniques have been developed, which yield clinically useful Re188O4- solutions. This review summarizes the technologies developed for the preparation of 188W/188Re generators, postelution concentration of the 188Re perrhenate eluate, and a brief discussion of new chemical strategies available for the very high yield preparation of 188Re radiopharmaceuticals.

  8. Additively manufactured porous tantalum implants

    NARCIS (Netherlands)

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

    2015-01-01

    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

  9. Rhenium-188: Availability from the W-188/Re-188 Generator and Status of Current Applications

    International Nuclear Information System (INIS)

    Pillai, M.R.A.; Dash, A.; Knapp, Russ F. Jr.

    2012-01-01

    Rhenium-188 is one of the most readily available generator derived and useful radionuclides for therapy emitting β-particles (2.12 MeV, 71.1% and 1.965 MeV, 25.6%) and imageable gammas (155 KeV, 15.1%). The 188W/188Re generator is an ideal source for the long term (4-6 months) continuous availability of no carrier added (nca) 188Re suitable for the preparation of radiopharmaceuticals for radionuclide therapy. The challenges associated with the double neutron capture route of production of the parent 188W radionuclide have been a major impediment in the progress of application of 188Re. Tungsten-188 of adequate specific activity can be prepared only in 2-3 of the high flux reactors operating in the World. Several useful technologies have been developed for the preparation of clinical grade 188W/188Re generator. Since the specific activity of 188W used in the generator is relatively low (<5 Ci/g), the eluted 188ReO4- can have low radioactive concentration often insufficient for radiopharmaceutical preparation. However, several efficient post elution concentration techniques have been developed that yield clinically useful 188ReO4-. Rhenium-188 has been used for the preparation of therapeutic radiopharmaceuticals for the management of diseases such as bone metastasis, rheumatoid arthritis and primary cancers. Several early phase clinical studies using radiopharmaceuticals based on 188Re-labeled phosphonates, antibodies, peptides, lipiodol and particulates have been reported. This article reviews the availability, and use of188Re including a discussion of why broader use of 188Re has not progressed as ecpected as a popular radionuclide for therapy.

  10. In-house Preparation of 188W/188Re Generators

    International Nuclear Information System (INIS)

    Sriwiang, Wiranee; Minsakorn, Napharat; Wardwilai, Charudej; Yindirum, Chareon; Sangsuriyan, Jatupol

    2007-08-01

    Full text: Low activity 188W/188Re generators were developed for the purpose of routinely supplying rhenium-188 for laboratory experiments and research works. Chromatography technology was applied in the construction of the generators. The chromatography columns containing 1.74 g alumina (Al2O3) were housed in plastic (PE) shielding inside the 30mm thick lead shield. Three generators were loaded with three different 188W activities; 25mCi (RG1), 25 mCi (RG2) and 50 mCi (RG3). Generator performances were determined in terms of elution yields, radiochemical purity, Al-breakthrough, 188W-breakthrough, and radionuclidic purity of the eluted products. These generators can be used for more than 6 months with average elution yields greater than 90 %. Radiochemical purity of 188ReO4- was high (> 99.7 % by ITLC), low level of 188W -breakthrough and low contamination of 192Ir and 191Os. There were only less than 1 ppm of 186W carrier and less than 3 ppm of Al-breakthrough. Key words: 188W/188Re, Generator, 188Re, Radionuclide

  11. Electrorecovery of tantalum in molten fluorides

    International Nuclear Information System (INIS)

    Espinola, A.; Dutra, A.J.B.; Silva, F.T. da

    1988-01-01

    Considering the privileged situation of Brazil as a productor of tantaliferous minerals, the authors have in view the development of a technology for production of metallic tantalum via molten salts electrolysis; this has the advantage of improving the aggregate value of exportation products, additionally to tantalum oxide and tantalum concentrates. Having in view the preliminary determintion of better conditions of temperature, electrolyte composition and current density for this process, electrolysis were conducted with a solvent composed of an eutetic mixture of lithium, sodium and potassium fluoride for dipotassium fluotantalate and occasionally for tantalum oxide. Current efficiencies as high as 83% were obtained in favoured conditions. (author) [pt

  12. Producing tantalum or columbium powder

    International Nuclear Information System (INIS)

    Rerat, C.F.

    1979-01-01

    A process is described for the production of tantalum or columbium powder with a high yield within a desired range of particle sizes. A molten salt bath of a double salt comprising either an alkali metal tantalum fluoride or an alkali metal columbium fluoride and a relatively large amount of alkali metal halide diluent salt to act as a heat sink is initially maintained at a temperature a little above the liquidus temperature of the salt mixture. A liquid alkali metal at a comparatively low temperature is added to the continuously stirred bath at a high mass flow rate, and reduces the double salt, producing tantalum or columbium. The reaction is exothermic and causes the temperature to rise rapidly to a desired final reaction temperature within the range 760 to 1000 0 . The liquid alkali metal is thereafter fed at a high mass flow rate to complete the reaction quickly at the final reaction temperature. Forced cooling at a heat extraction rate not less than 42 kilojoules/min./kg. of double salt is used during at least a portion of the reaction cycle at a rate sufficient to maintain the final reaction temperature within a desired range. (author)

  13. Preparation of potassium tantalum fluoride from tantalum hydroxide

    International Nuclear Information System (INIS)

    Silva, F.T. da; Espinola, A.; Dutra, A.J.B.

    1987-01-01

    Potassium tantalum fluoride (K 2 TaF 7 ) is an intermediary product in the processing of tantaliferous materials; it is the basic raw material for both reduction processes in use presently: reduction by metallic sodium and electrolysis in molten halides. It is normally obtained from a fluorotantalic acid solution to which potassium ions are added the precipitation of white acicular crystals of K 2 TaF 7 . The conditions for precipitation and recrystallization were studied, and crystal characterization were done by scanning electron microscopy, X-ray diffraction and thermogravimetric and thermodifferential analyses. (Author) [pt

  14. 188W→188Re generator for biomedical applications

    International Nuclear Information System (INIS)

    Kamioki, Hiroshi; Mirzadeh, S.; Lambrecht, R.M.; Knapp, R. Jr.; Dadachova, K.

    1994-01-01

    An alumina-based 188 W → 188 Re generator was evaluated for 188 Re yield and elution profile and 188 W breakthrough using various reagents for a three-month period. To address the problem of low specific volume, the generator was eluted with reagents which could be easily destroyed by gentle evaporation from acidic solutions (e.g. NH 4 Cl and NH 4 NO 3 ). We also evaluated a proposed ''alumina/anion-exchange'' tandem generator for the preparation of highly purified 188 Re as perrhenic acid. In parallel studies, the adsorption dynamics of tungsten on alumina showed a sharp rise in the tungsten breakthrough at W/Al 2 O 3 ratio of ∼ 120 mg/g corresponding to a distribution constant of ∼ 8400 from nitrate solution at 0.05 M ionic strength. In adsorption on anion exchange resins, carrier-free 188 Re exhibited a behavior very similar to that of macroscopic quantities of Re. These studies further demonstrated the long and useful shelf-life of 188 W → 188 Re generator. (orig.)

  15. Niobium Nb and tantalum Ta

    International Nuclear Information System (INIS)

    Busev, A.I.; Tiptsova, V.G.; Ivanov, V.M.

    1978-01-01

    The basic methods for determining niobium and tantalum in various objects are described. Nb and Ta are separated with the aid of N-benzoyl-N-phenylhydroxylamine by precipitating Nb(5) from a tartaric acid solution with subsequent precipitation of Ta from the filtrate. The gravimetric determination of Nb and Ta in steels is based on their quantitative separation from a diluted solution by way of hydrolysis with subsequent after-precipitation with phenylarsonic acid (in the absence of W). The gravimetric determination of Nb in the presence of W is carried out with the aid of Cupferron. To determine Nb in its carbide, Nb(5) reduced to Nb(3) is titrated with a solution of K 2 Cr 2 O 7 in the presence of phenyl-anthranilic acid. The photometric determination of Nb in tungsten-containing steels and in ores containing Ti, W, Mo and Cr is based on the rhodanide method. Nb is determined in alloys with Zr and Ti photometrically with the aid of 4-(2-pyridylazo)-resorcin and in alloyed steels with the aid of benzhydroxamic acid. The latter complex is extracted with chloroform. This method is used to determine Nb in rocks. The photometric determination of Ta in TiCl 4 is carried out with the aid of pyrogallol, in commercial niobium with the aid of methyl violet, and in steel with the aid of 4-(-pyridylazo)-resorcin. Also described is the polarographic determination of Nb in tantalum pentoxide

  16. Studies of HEDP labelled with 188Re from different generators of 188W /188Re

    International Nuclear Information System (INIS)

    Marczewski, Barbara Szot

    2006-01-01

    The widespread interest in 188 Re for therapeutic applications, is due to its attractive 16,9 hours half-life, emission of a β - particle with maximum energy of 2.12 MeV and gamma-ray of 155 keV suitable for imaging. This work presents the radiolabelling of HEDP (etidronate) with 188 Re eluted from alumina-based 188 W/ 188 Re generators and tungstate-based 188 W/ 188 Re gel generators. Dependence of the yield of the 18 '8Re-HEDP on the concentration of the reduction agent, p H, reaction time, temperature and addition of carrier Re 2 O 7 were evaluated. The radiolabelling of 188 Re-HEDP procedure using the optimum conditions resulted a yield >= 98% for liquid and lyophilized kits. This basic formulation contains: 30 mg de HEDP, 7 mg de SnCl 2 , 3 mg de ascorbic acid and addition of 20 mug of Re 2 O 7 . The reactions were carried out with heating in boiling water for 30 minutes followed by 60 minutes of incubation. Another important aspect of this work was the radiochemical quality control comparing the results of PC, TLC and ion chromatography, along with the experiments with HPLC. The biological distribution proved the adequate bone uptake and in vivo stability of 188 Re-HEDP complexes. (author)

  17. Preparation of potassium-reduced tantalum powders

    International Nuclear Information System (INIS)

    Kolosov, V.N.; Miroshnichenko, M.N.; Orlov, V.M.; Prokhorova, T.Yu.

    2005-01-01

    Characteristics of tantalum powders prepared by reduction of molten potassium heptafluorotantalate with liquid potassium are studied in a temperature range of 750 - 850 deg C using potassium chloride as a flux at a ratio of K 2 TaF 7 : KCl = 1, 2, and 3. The use of potassium as a reducing agent facilitates washing of tantalum powders for impurity salt removal, reduces sodium content and leakage currents in the anodes. As compared to sodium process, the potassium reduction results in a high yield of sponge material, a decrease in the specific surface area and yield of tantalum powder suitable for manufacture of capacitor anodes [ru

  18. Preparation of tantalum targets of known thicknesses

    International Nuclear Information System (INIS)

    Alexander, J.R.; Wirth, H.L.

    1985-01-01

    A series of carbon-backed tantalum targets were produced in a heavy ion sputtering system with a Penning ion source. The target thicknesses were then measured using the alpha-ray energy loss method. The resulting tabulated measurements were reproducible and make possible the production of carbon-backed tantalum targets with pre-determined thicknesses ranging from 20 μg/cm 2 to 1 mg/cm 2 . (orig.)

  19. Extraction of Tantalum from locally sourced Tantalite using ...

    African Journals Online (AJOL)

    acer

    Extraction of Tantalum from locally sourced Tantalite using ... ABSTRACT: The ability of polyethylene glycol solution to extract tantalum from locally .... metal ion in question by the particular extractant. ... Loparite, a rare-earth ore (Ce, Na,.

  20. Modeling the mechanical behavior of tantalum

    International Nuclear Information System (INIS)

    Lee, B.J.; Ahzi, S.

    1997-01-01

    A crystal plasticity model is proposed to simulate the large plastic deformation and texture evolution in tantalum over a wide range of strain rates. In the model, a modification of the viscoplastic power law for slip and a Taylor interaction law for polycrystals are employed, which account for the effects of strain hardening, strain-rate hardening, and thermal softening. A series of uniaxial compression tests in tantalum at strain rates ranging from 10 -3 to 10 4 s -1 were conducted and used to verify the model's simulated stress-strain response. Initial and evolved deformation textures were also measured for comparison with predicted textures from the model. Applications of this crystal plasticity model are made to examine the effect of different initial crystallographic textures in tantalum subjected to uniaxial compression deformation or biaxial tensile deformation

  1. Tantalum high-temperature oxidation kinetics

    International Nuclear Information System (INIS)

    Grigor'ev, Yu.M.; Sarkisyan, A.A.; Merzhanov, A.G.

    1981-01-01

    Kinetics of heat release and scale growth during tantalum oxidation within 650-1300 deg C temperature range in oxygen-containing media is investigated. Kinetic equations and temperature and pressure dependences of constants are ound Applicability of the kinetic Lorie mechanism for the description of the tantalum oxidation kinetics applicably to rapid-passing processes is shown. It is stated that the process rate (reaction ability) is determined by adsorption desorption factors on the external surface of the ''protective'' oxide for the ''linear'' oxidation stage [ru

  2. The filamentary nebulae S 188

    International Nuclear Information System (INIS)

    Rosado, M.; Kwitter, K.B.

    1982-01-01

    The crescent shaped nebula S 188 is identified as a planetary nebula (PN) of Peimbert's Type I on the basis of its observed nebula spectrum. New FP interferometric work allows to determine the systemic motion of this nebula. The derived kinematical distance exceeds Cudworth's distance estimate supporting the idea that Peimbert's Type I PNs have larger ejected masses than typical PNs. A discussion about the origin of its non-spherical shape is also given. (author)

  3. New Sesame equation of state for tantalum

    International Nuclear Information System (INIS)

    Greeff, C. W.; Johnson, J. D.

    2000-01-01

    A new Sesame equation of state (EOS) table has been created for tantalum. This EOS incorporates new high pressure Hugoniot data and diamond anvil cell compression data. The new EOS gives better agreement with this data as well as with sound speeds and Hugoniot curves of porous samples

  4. Bone remodeling around cementless tantalum cups

    NARCIS (Netherlands)

    Grillo, J. -C.; Flecher, X.; Bouvenot, J.; Argenson, J. -N.

    2008-01-01

    Purpose of the study.-Most studies have reported a significant decrease in periacetabular bone stock one year after implantation of a cementless cup. The purpose of this work was to study the bone-implant interface of the tantalum cup using plain X-rays and dual-energy X-ray absorptiometry (DEXA).

  5. Review of tantalum and niobium alloy production

    International Nuclear Information System (INIS)

    Buckman, R.W. Jr.

    1984-01-01

    This paper concentrates on the current state of niobium- and tantalum-base alloy production. The materials requirements, alloy compositions of interest, and production status are discussed. Finally, a list of developments needed to support the SP-100 program will be identified. A bibliography is included

  6. Obtainment of tantalum oxide from national ores

    International Nuclear Information System (INIS)

    Pinatti, D.G.; Ribeiro, S.; Martins, A.H.

    1988-01-01

    The experimental results of tantalum oxides (Ta 2 O 5 ) obtainment from Brazilian ores of tantalite and columbite are described. This study is a part of the technologic and scientific research design of refractory metals (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W) and correlate ceramics. (C.G.C.) [pt

  7. Intercalated compounds of niobium and tantalum dicalcogenides

    International Nuclear Information System (INIS)

    Wypych, F.

    1988-01-01

    The synthesis of niobium and tantalum lamellar compounds and its intercalated derivatives is described. The intercalated compounds with lithium, with alkaline metal and with metals of the first-row transition are studied, characterized by X-ray diffraction. (C.G.C.) [pt

  8. 46 CFR 188.10-51 - Ocean.

    Science.gov (United States)

    2010-10-01

    ... Terms Used in This Subchapter § 188.10-51 Ocean. Under this designation shall be included all vessels navigating the waters of any ocean, or the Gulf of Mexico more than 20 nautical miles offshore. ... 46 Shipping 7 2010-10-01 2010-10-01 false Ocean. 188.10-51 Section 188.10-51 Shipping COAST GUARD...

  9. 46 CFR 188.10-37 - Label.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Label. 188.10-37 Section 188.10-37 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS GENERAL PROVISIONS Definition of Terms Used in This Subchapter § 188.10-37 Label. This term means the label required by 49 CFR part 172...

  10. 12 CFR 18.8 - Delivery.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Delivery. 18.8 Section 18.8 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY DISCLOSURE OF FINANCIAL AND OTHER INFORMATION BY NATIONAL BANKS § 18.8 Delivery. Each national bank shall, after receiving a request for an annual...

  11. Case history of tantalum-weld cracking

    International Nuclear Information System (INIS)

    Knorovsky, G.A.

    1982-01-01

    Tantalum welding is normally a routine operation. Of course, the routine involves careful cleaning beforehand, and welding in an atmosphere which excludes reactive gases (O 2 , N 2 , H 2 ). Recently a weld cracking problem was encountered at SNLA despite the fact that normal precautions had been taken. This account reviews what happened, the analytical procedures followed to determine the unusual source of the problem, and the remedy which solved the problem

  12. Origins of Beta Tantalum in Sputtered Coatings

    National Research Council Canada - National Science Library

    Mulligan, C

    2001-01-01

    .... Some of the most recent work has attempted to relate the energetics (i.e., atom/ion energy) of the plasma to the alpha right arrow beta transition. It has been shown that the energetics of the plasma can relate to the most crucial sputtering parameters. The most significant feature of the use of plasma energy to explain the alpha right arrow beta transition is that it relates the formation of beta-tantalum to a quantifiable measure.

  13. Spark plasma sintering of tantalum carbide

    International Nuclear Information System (INIS)

    Khaleghi, Evan; Lin, Yen-Shan; Meyers, Marc A.; Olevsky, Eugene A.

    2010-01-01

    A tantalum carbide powder was consolidated by spark plasma sintering. The specimens were processed under various temperature and pressure conditions and characterized in terms of relative density, grain size, rupture strength and hardness. The results are compared to hot pressing conducted under similar settings. It is shown that high densification is accompanied by substantial grain growth. Carbon nanotubes were added to mitigate grain growth; however, while increasing specimens' rupture strength and final density, they had little effect on grain growth.

  14. Electrodepositions on Tantalum in Alkali Halide Melts

    DEFF Research Database (Denmark)

    Barner, Jens H. Von; Jensen, Annemette Hindhede; Christensen, Erik

    2013-01-01

    Surface layers of tantalum metal were electrodeposited on steel from K2TaF7-LiF-NaF-KF melts. With careful control of the oxide contents dense and adherent deposits could be obtained by pulse plating. In NaCl-KCl-NaF-Na2CO3 and NaCl-KCl-Na2CO3 melts carbonate ions seems to be reduced to carbon in...

  15. Electrodepositions on Tantalum in alkali halide melts

    DEFF Research Database (Denmark)

    Barner, Jens H. Von; Jensen, Annemette Hindhede; Christensen, Erik

    2012-01-01

    Surface layers of tantalum metal were electrodeposited on steel from K 2TaF7-LiF-NaF-KF melts. With careful control of the oxide contents dense and adherent deposits could be obtained by pulse plating. In NaCl-KCl-NaF-Na2CO3 and NaCl-KCl-Na2CO 3 melts carbonate ions seems to be reduced to carbon ...

  16. Formation of nickel-tantalum compounds in tantalum fluoride halide melts

    International Nuclear Information System (INIS)

    Matychenko, Eh.S.; Zalkind, O.A.; Kuznetsov, B.Ya.; Orlov, V.M.; Sukhorzhevskaya, S.L.

    2001-01-01

    Interaction of nickel with NaCl-K 2 TaF 7 melt (14 mol.%) at 750 deg C was studied, the composition of intermetallic compounds formed in Ni-Ta system being analyzed, using the methods of chemical and X-ray phase analyses, IR spectroscopy. It was ascertained that composition of intermetallic compounds (Ni 3 Ta, Ni 2 Ta) depends on K 2 TaF 7 concentration in the melt, metallic tantalum additions, nickel substrate thickness and experiment duration. The mechanism of currentless deposition of tantalum on nickel was considered and the assumption was made that disproportionation reaction lies in the basis of the process [ru

  17. A review on the current status and production technology for 188W-188Re generator system

    International Nuclear Information System (INIS)

    Kuznetsov, R. A.; Han, H. S.; Cho, W. K.; Park, U. J.; Kim, Y. M.

    1998-11-01

    The current status of 188 W- 188 Re generator production technology were reviewed in PART 1. Main interests were given to the aspects of 188 W reactor production, irradiated targets reprocessing and generator loading technologies, such as alumina type and gel type generators. In order to develop the more convenient and advanced 188 W- 188 Re generator, further studies must be carried out to get the precise evaluation of production and burn-up cross section of 188 W, the more easily realizable generator loading procedure, and also to optimize the column and generator design to compensate the deterioration of generator performance because of parent radionuclide decay. By irradiation of 186 W enriched sample, 188 W- 188 Re generator production experiments were performed to evaluate the possibility of 188 W- 188 Re generator production using HANARO, and PART 2 describes about the experiments. The experimental results shows the possibility of practical 188 W- 188 Re generator production using of low-specific activity 188 W produced in HANARO. (author). 79 refs., 4 tabs., 26 figs

  18. Advances in the chemical vapor deposition (CVD) of Tantalum

    DEFF Research Database (Denmark)

    Mugabi, James Atwoki; Eriksen, Søren; Christensen, Erik

    2014-01-01

    The chemical stability of tantalum in hot acidic media has made it a key material in the protection of industrial equipment from corrosion under such conditions. The Chemical Vapor Deposition of tantalum to achieve such thin corrosion resistant coatings is one of the most widely mentioned examples...

  19. Tantalum: A strategic metal; Tantalo: Un metal estrategico

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Lopez, G.; Lopez-Lopez, J.; Garcia-Yagues, M. R.

    2009-07-01

    In nature, the main source of tantalum is an isomorphous series of minerals containing oxides of tantalum, niobium, iron and manganese, which are collectively known as columbine-tantalite (coltan). Upgraded Ta{sub 2}O{sub 5}-containing tin slags are also used as a secondary source of tantalum. Coltan, either naturally occurring or synthetically produced as concentrates from tin slags, are digested with hydrofluoric and sulphuric acid at an elevated temperature. the aqueous solution of ta-Nb in hydrofluoric acid is extracted in several continuously operating mixer-settler systems or extraction columns with an organic solvent like methyl isobutyl ketone. The organic phase is then scrubbed with 6-15 N H{sub 2}SO{sub 4} to separate the niobium from the tantalum by selective stripping. The tantalum salt is extracted from the organic phase with water or diluted aqueous ammonium fluoride solution, the demands of the solid tantalum capacitor industry for high quality, high surface area tantalum powders have driven improvements in the sodium reduction of K{sub 2}TaF{sub 7}. The much-improved chemistry reflects the many modifications to the process put in place after 1990 and the subsequent improvements in the electrical quality as measured by the performance of tantalum capacitors. (Author) 5 refs.

  20. Human bone ingrowth into a porous tantalum acetabular cup

    Directory of Open Access Journals (Sweden)

    Gregory N. Haidemenopoulos

    2017-11-01

    Full Text Available Porous Tantalum is increasingly used as a structural scaffold in orthopaedic applications. Information on the mechanisms of human bone ingrowth into trabecular metal implants is rather limited. In this work we have studied, qualitatively, human bone ingrowth into a retrieved porous tantalum monoblock acetabular cup using optical microscopy, scanning electron microscopy and energy dispersive X-ray analysis. According to the results and taking into account the short operational life (4 years of the implant, bone ingrowth on the acetabular cup took place in the first two-rows of porous tantalum cells to an estimated depth of 1.5 to 2 mm. The bone material, grown inside the first raw of cells, had almost identical composition with the attached bone on the cup surface, as verified by the same Ca:P ratio. Bone ingrowth has been a gradual process starting with Ca deposition on the tantalum struts, followed by bone formation into the tantalum cells, with gradual densification of the bone tissue into hydroxyapatite. A critical step in this process has been the attachment of bone material to the tantalum struts following the topology of the porous tantalum scaffold. These results provide insight to the human bone ingrowth process into porous tantalum implants.

  1. 21 CFR 886.3100 - Ophthalmic tantalum clip.

    Science.gov (United States)

    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...

  2. Standard specification for tantalum and tantalum alloy plate, sheet, and strip. ASTM standard

    International Nuclear Information System (INIS)

    1998-09-01

    This specification is under the jurisdiction of ASTM Committee B-10 on Reactive and Refractory Metals and Alloys and is the direct responsibility of Subcommittee B10.03 on Niobium and Tantalum. Current edition approved May 10, 1998 and published September 1998. Originally published as B 708-82. Last previous edition was B 708-92

  3. Efficacy of Tantalum Tungsten Alloys for Diffusion Barrier Applications

    Science.gov (United States)

    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.

  4. Uptake and retention of insufflated tantalum by lymph nodes

    International Nuclear Information System (INIS)

    Kilpper, R.W.; Bianco, A.; Gibb, F.R.; Landman, S.; Morrow, P.E.

    1976-01-01

    A nonsacrifice, radiographic technique is presented for evaluating the lymph node uptake of radiographically dense materials from the lungs of beagle dogs into which the material was insufflated. With tantalum as the contrast agent, lymph nodes sometimes become visible within 2 days after exposure when the insufflation resulted in radiographic ''alveolarization'' of some of the tantalum. Localization of the material within the nodes was observed in subsequent radiographs as well as persistent retention after as much as 1 year. Through the use of preinsufflation control films and tantalum foils of varying thickness, densitometric methods for determining the amount of tantalum within the lymph nodes are being investigated. Tantalum-182 is being used to follow the lung retention of the material as well as to verify estimates of burdens in harvested nodes. Preliminary lymphokinetic data are presented from experiments utilizing powders of 1 and 5 μm (mean) particle sizes

  5. Fabrication of a tantalum-clad tungsten target for KENS

    International Nuclear Information System (INIS)

    Kawai, Masayoshi; Kikuchi, Kenji; Kurishita, Hiroaki; Li, J.-F.; Furusaka, Michihiro

    2001-01-01

    Since the cold neutron source intensity of KENS (the spallation neutron source at High Energy Accelerator Research Organization) was decreased into about a third of the designed value because a cadmium liner at the cold neutron source deformed and obstructed the neutron beam line, the target-moderator-and-reflector assembly (TMRA) has been replaced by a new one aimed at improving the neutron performance and recovering the cold neutron source. The tantalum target has also been replaced by a tantalum-clad tungsten one. In order to bond the tantalum-clad with the tungsten block, a hot isostatic press (HIP) process was applied and optimized. It was found that gaseous interstitial impurity elements severely attacked tantalum and embrittled, and that the getter materials such as zirconium and tantalum were effective to reduce the embrittlement

  6. Process for the production of a tantalum and niobium bearing concentrate from a tantalum and niobium bearing ferro-alloy

    International Nuclear Information System (INIS)

    Deweck, J.; Van, H.

    1980-01-01

    In a process for the production of a tantalum and niobium bearing concentrate from a tantalum and niobium bearing ferro-alloy containing tantalum and niobium as carbide, by treating the ferro-alloy in molten state with a controlled amount of an oxidizing agent in order to slag at least most of the tantalum and at least part of the niobium and by separting the so obtained slag phase from the metal phase, the improvement which comprises using air, oxygen enriched air or oxygen as oxidizing agent and adjusting the iron content to the ferro-alloy by adding at least 70% by weight of iron prior to the step of forming the slag so that at least most of the tantalum carbide is dissolved in the molten ferro-alloy

  7. Fracture of an uncemented tantalum patellar component

    Directory of Open Access Journals (Sweden)

    Nathan L. Grimm, MD

    2016-06-01

    Full Text Available A 62-year-old man presented with the acute, atraumatic onset of pain 3 years after uncemented right total knee arthroplasty. He complained of new mechanical locking with the knee held in extension on examination and unable to flex the knee. On the plain radiographs, the patellar component peg was fractured and the plate was dislocated. The knee was immobilized, and revision to a cemented 3-peg component was performed. Fracture of a single-peg, tantalum-backed uncemented patellar component has not been described. Clinical suspicion for this should be given in the setting of acute locking. We recommend revision with a cemented polyethylene component.

  8. Plasma-sprayed tantalum/alumina cermets

    International Nuclear Information System (INIS)

    Kramer, C.M.

    1977-12-01

    Cermets of tantalum and alumina were fabricated by plasma spraying, with the amount of alumina varied from 0 to 65 percent (by volume). Each of four compositions was then measured for tensile strength, elastic modulus, and coefficient of thermal expansion. In general, strength and strain to failure decreased with increasing alumina content: 62 MPa for 100 percent Ta to 19 MPa for 35 v percent Ta. A maximum of 0.1 percent strain was observed for the sprayed 100 percent Ta specimens. The coefficient of thermal expansion measured for the pure Ta was 6.2 (10 -6 )/K

  9. Stability of rhenium-188 labeled antibody

    International Nuclear Information System (INIS)

    Lim, B. K.; Jung, J. M.; Jung, J. K.; Lee, D. S.; Lee, M. C.

    1999-01-01

    For clinical application of beta-emitter labeled antibody, high specific activity is important. Carrier-free Re-188 from W-188/Re-188 generator is an ideal radionuclide for this purpose. However, low stability of Re-188 labeled antibody, especially in high specific activity, due to radiolytic decomposition by high energy (2.1 MeV) beta ray was problem. We studied the stability of Re-188 labeled antibody, and stabilizing effect of several nontoxic radical-quenching agents. Pre-reduced monoclonal antibody (CEA79.4) was labeled with Re-188 by incubating with generator-eluted Re-188-perrhenate in the presence of stannous tartrate for 2 hr at room temperature. Radiochemical purity of each preparation was determined by chromatography (ITLC-SG/acetone, ITLC-SG/Umezawa, Whatman No.1/saline). Human serum albumin was added to the labeled antibodies(2%). Stability of Re-188-CEA79.4 was investigated in the presence of vitamin C, ethanol, or Tween 80 as radical-quenching agents. Specific activities of 4.29∼5.11 MBq/μg were obtained. Labeling efficiencies were 88±4%(n=12). Very low stability after removal of stannous tartrate from the preparation was observed. If stored after purging with N 2 , all the preparations were stable for 10 hr. However, if contacted with air, stability decreased. Perrhenate and Re-188-tartrate was major impurity in declined preparation (12∼47 and 9∼38% each, after 10 hr). Colloid-formation was not a significant problem in all cases. Addition of vitamin C stabilized the labeled antibodies either under N 2 or under air by reducing the formation of perrhenate. High specific activity Re-188 labeled antibody is unstable, especially, in the presence of oxygen. Addition of vitamin C increased the stability

  10. Shock compression and quasielastic release in tantalum

    International Nuclear Information System (INIS)

    Johnson, J.N.; Hixson, R.S.; Tonks, D.L.; Gray, G.T. III

    1994-01-01

    Previous studies of quasielastic release in shock-loaded FCC metals have shown a strong influence of the defect state on the leading edge, or first observable arrival, of the release wave. This is due to the large density of pinned dislocation segments behind the shock front, their relatively large pinning separation, and a very short response time as determined by the drag coefficient in the shock-compressed state. This effect is entirely equivalent to problems associated with elastic moduli determination using ultrasonic methods. This is particularly true for FCC metals, which have an especially low Peierls stress, or inherent lattice resistance, that has little influence in pinning dislocation segments and inhibiting anelastic deformation. BCC metals, on the other hand, have a large Peierls stress that essentially holds dislocation segments in place at low net applied shear stresses and thus allows fully elastic deformation to occur in the complete absence of anelastic behavior. Shock-compression and release experiments have been performed on tantalum (BCC), with the observation that the leading release disturbance is indeed elastic. This conclusion is established by examination of experimental VISAR records taken at the tantalum/sapphire (window) interface in a symmetric-impact experiment which subjects the sample to a peak longitudinal stress of approximately 7.3 GPa, in comparison with characteristic code calculations. copyright 1994 American Institute of Physics

  11. Twinning anisotropy of tantalum during nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Goel, Saurav, E-mail: S.GOEL@qub.ac.uk [School of Mechanical and Aerospace Engineering, Queen' s University, Belfast, BT9 5AH (United Kingdom); Beake, Ben [Micro Materials Limited, Willow House, Yale Business Village, Ellice Way, Wrexham LL13 7YL (United Kingdom); Dalton Research Institute, Manchester Metropolitan University, Manchester, M15GD (United Kingdom); Chan, Chi-Wai [School of Mechanical and Aerospace Engineering, Queen' s University, Belfast, BT9 5AH (United Kingdom); Haque Faisal, Nadimul [School of Engineering, Robert Gordon University, Garthdee Road, Aberdeen AB10 7GJ (United Kingdom); Dunne, Nicholas [School of Mechanical and Aerospace Engineering, Queen' s University, Belfast, BT9 5AH (United Kingdom)

    2015-03-11

    Unlike other BCC metals, the plastic deformation of nanocrystalline Tantalum (Ta) during compression is regulated by deformation twinning. Whether or not this twinning exhibits anisotropy was investigated through simulation of displacement-controlled nanoindentation test using molecular dynamics (MD) simulation. MD data was found to correlate well with the experimental data in terms of surface topography and hardness measurements. The mechanism of the transport of material was identified due to the formation and motion of prismatic dislocations loops (edge dislocations) belonging to the 1/2〈111〉 type and 〈100〉 type Burgers vector family. Further analysis of crystal defects using a fully automated dislocation extraction algorithm (DXA) illuminated formation and migration of twin boundaries on the (110) and (111) orientation but not on the (010) orientation and most importantly after retraction all the dislocations disappeared on the (110) orientation suggesting twinning to dominate dislocation nucleation in driving plasticity in tantalum. A significant finding was that the maximum shear stress (critical Tresca stress) in the deformation zone exceeded the theoretical shear strength of Ta (Shear modulus/2π~10.03 GPa) on the (010) orientation but was lower than it on the (110) and the (111) orientations. In light of this, the conventional lore of assuming the maximum shear stress being 0.465 times the mean contact pressure was found to break down at atomic scale.

  12. Evaluation of Polymer Hermetically Sealed Tantalum Capacitors

    Science.gov (United States)

    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.

  13. Tantalum-based semiconductors for solar water splitting.

    Science.gov (United States)

    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

  14. Work hardening and plastic equation of state of tantalum

    International Nuclear Information System (INIS)

    Gypen, L.A.; Aernoudt, E.; Deruyttere, A.

    1983-01-01

    The influence of cold deformation on the thermal and athermal components of the flow stress of tantalum was investigated. Up to high deformation levels the strain hardening is due only to the development of internal stress fields; the effective stress remains almost constant. The athermal strain hardening of tantalum is parabolic at low deformation levels (epsilon < 0.5) and linear at high deformation levels, as for other bcc metals. Hart's plastic equation of state is shown to be valid for tantalum at room temperature in the whole deformation range investigated (from epsilon = 0.005 to epsilon = 2.8). (author)

  15. The Chemical Vapour Deposition of Tantalum - in long narrow channels

    DEFF Research Database (Denmark)

    Mugabi, James Atwoki

    protective layers of tantalum because of the process’ ability to coat complex geometries and its relative ease to control. This work focuses on studying the CVD of tantalum in long narrow channels with the view that the knowledge gained during the project can be used to optimise the commercial coating...... and that there is a major change in morphology between 850 – 900 °C. The effects of system pressure and precursor partial pressure are also studied, and were found to have relevance to the tantalum distribution along the substrates but little effect on the structural morphology of the deposited layer. In the implemented...

  16. Hydroxyapatite based 99Mo-99mTc and 188W-188Re generator systems

    International Nuclear Information System (INIS)

    Monroy-Guzman, F.; Badillo-Almaraz, V.E.; Flores de la Torre, J.A.; Cosgrove, J.; Knapp, F.F. Jr.

    2007-01-01

    This paper describes studies evaluating the use of hydroxyapatite as the adsorbent material for both 90M o- 90m Tc and 89W - 188 Re generator systems. Hydroxyapatite is an insoluble solid with anion exchange properties. A study of the sorption behaviour of 90M o, 90m Tc, 188 W and 188 Re on hydroxyapatite in NaCl medium was evaluated by batch experiments. The results demonstrated that while 90M o, 90m Tc and 188 Re are not adsorbed by the hydroxyapatite in NaCl solutions (Kd 89W is strongly adsorbed (Kd >500). On the basis of these measurements, hydroxyapatite 89W - 188 Re generator systems were then constructed and eluted in NaCl solutions. The hydroxyapatite based 89W - 188 Re generator performances are presented. (author)

  17. Electronic structure and charge transport in nonstoichiometric tantalum oxide

    Science.gov (United States)

    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.

  18. Force-dominated non-equilibrium oxidation kinetics of tantalum

    International Nuclear Information System (INIS)

    Kar, Prasenjit; Wang, Ke; Liang, Hong

    2008-01-01

    Using a combined electrochemical and mechanical manipulation technique, we compared the equilibrium and non-equilibrium oxidation processes and states of tantalum. Experimentally, a setup was developed with an electrochemical system attached to a sliding mechanical configuration capable of friction force measurement. The surface chemistry of a sliding surface, i.e., tantalum, was modified through the electrolyte. The mechanically applied force was fixed and the dynamics of the surface was monitored in situ through a force sensor. The formation of non-equilibrium oxidation states of tantalum was found in oxidation limiting environment of acetic acid. An oxidative environment of deionized water saturated with KCl was used as comparison. We proposed a modified Arrhenius-Eyring equation in which the mechanical factor was considered. We found that the mechanical energy induced the non-stable-state reactions leading to metastable oxidation states of tantalum. This equation can be used to predict mechanochemical reactions that are important in many industrial applications

  19. Titrimetric determination of tungsten in its alloys with tantalum

    International Nuclear Information System (INIS)

    Elinson, S.V.; Nezhnova, T.I.

    1982-01-01

    Titrimetric method of tungsten determination in tantalum base alloys has been developed. The method permits to determine 5-10% tungsten in the alloys with relative standard deviation of 0.013. The conditions are created by application of precipitation from homogeieous solutions or by the method of appearing reagents at pH values, which condition gradual hydrolytic precipitation of tantalum, and sodium tungstate remains in the solution and is not sorbed on tantalum hydroxide. After separation of tantalum oxide tungsten is precipitated in the form of lead tungstate by the excess of ti trated solution of lead salt during boiling and then at the background of lead tungstate precipitate without its separation lead excess is titrated by EDTA in the presence of mixed indicator-4-(2-pyridylazo)resocinol and xylenole orange in acetate buffer solution

  20. PREPARATION OF TANTALUM CARBIDE FROM AN ORGANOMETALLIC PRECURSOR

    Directory of Open Access Journals (Sweden)

    C. P. SOUZA

    1999-03-01

    Full Text Available In this work we have synthesized an organometallic oxalic precursor from tantalum oxide. This oxide was solubilized by heating with potassium hydrogen sulfate. In order to precipitate Ta2O5.nH2O, the fused mass obtained was dissolved in a sulfuric acid solution and neutralized with ammonia. The hydrated tantalum oxide precipitated was dissolved in an equimolar solution of oxalic acid/ammonium oxalate. The synthesis and the characterization of the tantalum oxalic precursor are described. Pyrolysis of the complex in a mixture of hydrogen and methane at atmospheric pressure was studied. The gas-solid reaction made it possible to obtain tantalum carbide, TaC, in the powder form at 1000oC. The natural sintering of TaC powder in an inert atmosphere at 1400°C during 10 hours, under inert atmosphere made it possible to densify the carbide to 96% of the theoretical value.

  1. Radiographic examination of tracheal strictures by means of powdered tantalum

    International Nuclear Information System (INIS)

    Scheel, W.; Dippmann, A.

    1979-01-01

    This report deals with the diagnostic value of a tracheobronchography with powdered tantalum in 5 patients who suffer from a severe stricture of the trachea. The own experiences with this method are described. (orig.) [de

  2. Valence electronic structure of tantalum carbide and nitride

    Institute of Scientific and Technical Information of China (English)

    FAN; ChangZeng

    2007-01-01

    The valence electronic structures of tantalum carbide (TaC) and tantalum nitride (TaN) are studied by using the empirical electronic theory (EET). The results reveal that the bonds of these compounds have covalent, metallic and ionic characters. For a quantitative analysis of the relative strength of these components, their ionicities have been calculated by implanting the results of EET to the PVL model. It has been found that the ionicity of tantalum carbide is smaller than that of tantalum nitride. The EET results also reveal that the covalent electronic number of the strongest bond in the former is larger than that of the latter. All these suggest that the covalent bond of TaC is stronger than that of TaN, which coincides to that deduced from the first-principles method.……

  3. Valence electronic structure of tantalum carbide and nitride

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ The valence electronic structures of tantalum carbide (TaC) and tantalum nitride (TaN) are studied by using the empirical electronic theory (EET). The results reveal that the bonds of these compounds have covalent, metallic and ionic characters. For a quantitative analysis of the relative strength of these components, their ionicities have been calculated by implanting the results of EET to the PVL model. It has been found that the ionicity of tantalum carbide is smaller than that of tantalum nitride. The EET results also reveal that the covalent electronic number of the strongest bond in the former is larger than that of the latter. All these suggest that the covalent bond of TaC is stronger than that of TaN, which coincides to that deduced from the first-principles method.

  4. Fast-neutrons incident on rotors: Tantalum

    International Nuclear Information System (INIS)

    Smith, Alan B.

    2005-01-01

    Mono-energetic neutrons are elastically and inelastically scattered from elemental tantalum at incident energies of ∼0.3-10.0 MeV. These experimental results are augmented with neutron total-cross-section and additional neutron-scattering data from the literature to form a composite experimental database. The latter is interpreted in the context of optical-statistical and coupled-channels models, including consideration of collective rotations, dispersion effects and other physical properties. The results are compared with those of similar processes in this region of collective nuclei. A regional model is proposed for the interpretation and prediction of such interactions. The model and the experimental results are compared with corresponding values given in ENDF/B-VI

  5. The global tantalum industry and Sons of Gwalia Ltd

    International Nuclear Information System (INIS)

    Paull, D.

    2002-01-01

    Sons of Gwalia Ltd., in Perth Australia is a long-term supplier of tantalum (Ta), a valuable rare metal with adequate supply. Tantalum is soft and ductile with high melting and boiling points and a low co-efficient of thermal expansion. It has excellent capacity to store and release electrical charge and offers exceptional resistance to corrosion. Its' main use is in consumer electronics such as mobile phones, laptop computers, DVD players, personal video recorders and MP-3 players. For automotive electronics, tantalum is used for air-bags, audio systems, navigation systems, anti-lock break systems and under the hood vehicle management systems. The super alloy is also in demand by the aerospace industry and for turbine blades for power stations. The total demand of Tantalum in 2000 was 5 million lbs. Demand growth has increased steadily since 1993 with perhaps a slight increase in the past 5 years. Resources are estimated at a 125 year supply based on year 2000 production rates. 41 per cent of the world supply of tantalum is obtained from Australia, 13 per cent from Africa, 16 per cent from America, 22 per cent from Asia. The Greenbushes mine in Australia is the world's largest tantalum mine with 80 million lbs Ta, followed by Australia's Wodgina Mine with 50 million lbs Ta. Both mines are expected to be operational for the next 25 years. 12 figs

  6. Absolute counting of 188Re radiopharmaceuticals

    International Nuclear Information System (INIS)

    Ravindra, Anuradha; Kulkarni, D.B.; Joseph, Leena; Kulkarni, M.S.

    2018-01-01

    Rhenium-188 is radiopharmaceutical that belongs to the group of strong beta-weak gamma emitters. It emits high energy beta particles, (E β m ax = 2.12MeV) and weak gamma rays (E γ = 155 keV) hence makes it suitable for wide variety of therapeutic as well as diagnostic applications. Therapeutic applications include therapy of tumors, radionuclide synovectomy, bone pain palliation, intra vascular radiation therapy etc. 188 Re-labeled medicines have been employed increasingly in the therapy of tumors and vascular restenosis. To ensure that patient receives the appropriate radiation dose during the treatment, both the activity standardization and the determination of sensitivity coefficient of the secondary standard for 188 Re have become important tasks. This paper presents the methods and results obtained for the following measurements a) Standardisation of the 188 Re by using the 4π proportional counter (4πPC)-gamma extrapolation method b) Determination of sensitivity coefficient (pA/MBq) of the secondary standard ionization chamber type Centronic IG12, 20A for 188 Re

  7. Lithium in old open clusters - NGC 188

    International Nuclear Information System (INIS)

    Hobbs, L.M.; Pilachowski, C.

    1988-01-01

    Echelle spectra which include the Li I line at 6707 A are reported for seven main-sequence stars and one subgiant in NGC 188. The Li I line is detected in five of the six dwarfs which are highly probable cluster members. The derived atmospheric Li/H ratios exceed the solar value by factors ranging approximately from 10 to 40, although these apparently closely solarlike stars are about twice as old as the sun. The variation of the lithium abundance with stellar mass along the main sequences of the Pleiades, the Hyades, NGC 752, and NGC 188 are compared. The resulting evolutionary pattern indicates that the lithium fraction in the Galactic gas has shown no appreciable change from Li/H of roughly 10 to the -9th since the birth of NGC 188 about 10 Gyr ago, except that the abundance could have been higher by an uncertain but possibly appreciable factor at the beginning of that epoch. 51 references

  8. Development of a technology for the preparation of 188W-188Re generators

    International Nuclear Information System (INIS)

    Oliveira, Alexandre de

    2004-01-01

    A big interest has recently arisen concerning the use of Rhenium-188 (188Re) for various medical applications. Tumor therapy with antibodies labeled with 188Re is the main application, but it is being studied its application in carcinomas of medullar thyroid, bone pain palliation and radionuclide synovectomy, among others. Rhenium-188 decays 79% to the ground state of stable 188Os (Eβ1max - 2,11 MeV) and 20% to the first excited state (Eβ2max = 1,97 MeV). The deexcitation of this state gives a 155 keV gamma ray (15r%) which can be detected by imaging. Another great advantage is the viability of carrier-free 188Re from the decay of 188W (t 1/2 = 69.4 days) in a generator system. The objective of this work is the development of the technology for the preparation of 188W- 188Re generators. To accomplish this, the steps of the work are: preparation of the targets of W; irradiation of W targets in order to measure the activation and radionuclidic impurities; development of 188W-188Re generators; development of a method for the quality control of 188Re: chemical, radiochemical and radionuclidic purities. The study of alumina-based generators was performed with the irradiation of targets of natural metallic W and W03 and showed that this kind of generator will only be viable with the importation of 188W, due to the low neutron flux of the Reactor IEA-R1 Reactor for the commercial routine production of this radioisotope, but the technology of production and quality control were successful. The gel type chromatographic generators of WZr were produced with natural WO3 targets and showed that, if enriched targets are to be used and with the power upgrade of the IEA-R1 Reactor, they can be produced by the Radiopharmacy Center at IPEN-SP. The quality control methodology were determined and the results were inside the limits given by the Pharmacopoeia. (author)

  9. Concentration of 188Re-Perrhenate for Therapeutic Radiopharmaceuticals

    International Nuclear Information System (INIS)

    Bokhari, T.H.; Hina, S.; Ahmad, M.; Iqbal, M.

    2013-01-01

    Summary: Rhenium-188 (T1/2=16.9h) has great potential for a variety of therapeutic applications, including radionuclide synovectomy, oncology and bone pain palliation. The radioactive concentration of 188Re is dependent upon the specific activity of 188W, which dictates the bed size of the alumina/gel column. Due to the high content of inactive tungsten in neutron irradiated WO3, large columns containing aluminum oxide or gel are needed to prepare to double neutron capture based 188W/188Re generators that results in large elution volumes containing relatively high188W contents and low concentrations of /sup 188/ ReO/sub 4/ This decrease in specific volume of 188ReO/sub 4/ places a limitation because a high radioactive concentration of 188ReO4 - is always needed for filling angioplasty balloons or other therapeutic radiopharmaceuticals like188Re -EHDP 188Re -EDTMP, 188Re - MAG3 and 188Re -DTPA. We report post elution concentration of 188ReO4 - using in- house prepared lead cation exchange and alumina columns. Using these columns high bolus volume (10 mL saline) of 188ReO4 - can conveniently be concentrated in 1 mL of physiological saline for therapeutic use. (author)

  10. Tantalum oxide thin films as protective coatings for sensors

    DEFF Research Database (Denmark)

    Christensen, Carsten; Reus, Roger De; Bouwstra, Siebe

    1999-01-01

    Reactively sputtered tantalum oxide thin films have been investigated as protective coatings for aggressive media exposed sensors. Tantalum oxide is shown to be chemically very robust. The etch rate in aqueous potassium hydroxide with pH 11 at 140°C is lower than 0.008 Å h-l. Etching in liquids...... with pH values in the range from pH 2 to 11 have generally given etch rates below 0.04 Å h-l. On the other hand patterning is possible in hydrofluoric acid. Further, the passivation behaviour of amorphous tantalum oxide and polycrystalline Ta2O5 is different in buffered hydrofluoric acid. By ex situ...... annealing O2 in the residual thin-film stress can be altered from compressive to tensile and annealing at 450°C for 30 minutes gives a stress-free film. The step coverage of the sputter deposited amorphous tantalum oxide is reasonable, but metallization lines are hard to cover. Sputtered tantalum oxide...

  11. Tantalum oxide thin films as protective coatings for sensors

    DEFF Research Database (Denmark)

    Christensen, Carsten; Reus, Roger De; Bouwstra, Siebe

    1999-01-01

    Reactively sputtered tantalum oxide thin-films have been investigated as protective coating for aggressive media exposed sensors. Tantalum oxide is shown to be chemically very robust. The etch rate in aqueous potassium hydroxide with pH 11 at 140°C is lower than 0.008 Å/h. Etching in liquids with p......H values in the range from pH 2-11 have generally given etch rates below 0.04 Å/h. On the other hand patterning is possible in hydrofluoric acid. Further, the passivation behaviour of amorphous tantalum oxide and polycrystalline Ta2O5 is different in buffered hydrofluoric acid. By ex-situ annealing in O2...... the residual thin-film stress can be altered from compressive to tensile and annealing at 450°C for 30 minutes gives a stress-free film. The step coverage of the sputter deposited amorphous tantalum oxide is reasonable, but metallisation lines are hard to cover. Sputtered tantalum oxide exhibits high...

  12. Tantalum strength model incorporating temperature, strain rate and pressure

    Science.gov (United States)

    Lim, Hojun; Battaile, Corbett; Brown, Justin; Lane, Matt

    Tantalum is a body-centered-cubic (BCC) refractory metal that is widely used in many applications in high temperature, strain rate and pressure environments. In this work, we propose a physically-based strength model for tantalum that incorporates effects of temperature, strain rate and pressure. A constitutive model for single crystal tantalum is developed based on dislocation kink-pair theory, and calibrated to measurements on single crystal specimens. The model is then used to predict deformations of single- and polycrystalline tantalum. In addition, the proposed strength model is implemented into Sandia's ALEGRA solid dynamics code to predict plastic deformations of tantalum in engineering-scale applications at extreme conditions, e.g. Taylor impact tests and Z machine's high pressure ramp compression tests, and the results are compared with available experimental data. Sandia National Laboratories is a multi program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  13. Development of technology of high-purity compounds of tantalum and niobium with octanol use

    International Nuclear Information System (INIS)

    Majorov, V.G.; Nikolaev, A.I.; Kopkov, V.K.; Baklanova, I.V.; Safonova, L.A.

    2001-01-01

    Effect of composition of solutions and extractant expenditure on tantalum and niobium distribution during extraction by octanol and purification of tantalum and niobium extracts from impurities was studied. Scheme was developed according to which samples of high-pure tantalum and niobium pentaoxides were prepared [ru

  14. Corrosion resistance of tantalum base alloys

    International Nuclear Information System (INIS)

    Gypen, L.A.; Brabers, M.; Deruyttre, A.

    1984-01-01

    The corrosion behaviour of substitutional Ta-Mo, Ta-W, Ta-Nb, Ta-Hf, Ta-Zr, Ta-Re, Ta-Ni, Ta-V, Ta-W-Mo, Ta-W-Nb, Ta-W-Hf and Ta-W-Re alloys has been investigated in various corrosive media, i.e. (1) concentrated sulfuric acid at 250 0 C and 200 0 C, (2) boiling hydrochloric acid of azeotropic composition, (3) concentrated hydrochloric acid at 150 0 C under pressure, (4) HF-Containing solutions and (5) 0.5% H 2 SO 4 at room temperature (anodisation). In highly corrosive media such as concentrated H 2 SO 4 at 250 0 C and concentrated HCl at 150 0 C tantalum is hydrogen embrittled, probably by stress induced precipitation of β-hydride. Both corrosion rate and hydrogen embrittlement in concentrated H 2 SO 4 at 250 0 C are strongly influenced by alloying elements. Small alloying additions of either Mo or Re decrease the corrosion rate and the hydrogen embrittlement, while Hf has the opposite effect. Hydrogen embrittlement in concentrated H 2 SO 4 at 250 0 C is completely eliminated by alloying Ta with 1 to 3 at % Mo (0.5 to 1.5 wt % Mo). These results can be explained in terms of oxygen deficiency of the Ta 2 O 5 film and the electronic structure of these alloys. (orig.) [de

  15. Thermomechanical characterization of pure polycrystalline tantalum

    International Nuclear Information System (INIS)

    Rittel, D.; Bhattacharyya, A.; Poon, B.; Zhao, J.; Ravichandran, G.

    2007-01-01

    The thermomechanical behavior of pure polycrystalline tantalum has been characterized over a wide range of strain rates, using the recently developed shear compression specimen [D. Rittel, S. Lee, G. Ravichandran, Experimental Mechanics 42 (2002) 58-64]. Dynamic experiments were carried out using a split Hopkinson pressure bar, and the specimen's temperature was monitored throughout the tests using an infrared radiometer. The results of the mechanical tests confirm previous results on pure Ta. Specifically, in addition to its significant strain rate sensitivity, it was observed that pure Ta exhibits very little strain hardening at high strain rates. The measured temperature rise in the specimen's gauge was compared to theoretical predictions which assume a total conversion of the mechanical energy into heat (β = 1) [G.I. Taylor, H. Quinney, Proceedings of the Royal Society of London, vol. A, 1934, pp. 307-326], and an excellent agreement was obtained. This result confirms the previous result of Kapoor and Nemat-Nasser [R. Kapoor, S. Nemat-Nasser, Mech. Mater. 27 (1998) 1-12], while a different experimental approach was adopted here. The assumption that β = 1 is found to be justified in this specific case by the lack of dynamic strain hardening of pure Ta. However, this assumption should be limited to non-hardening materials, to reflect the fact that strain hardening implies that part of the mechanical energy is stored into the material's microstructure

  16. Tantalum powder consolidation, modeling and properties

    International Nuclear Information System (INIS)

    Bingert, S.R.; Vargas, V.D.; Sheinberg, H.C.

    1996-01-01

    A systematic approach was taken to investigate the consolidation of tantalum powders. The effects of sinter time, temperature and ramp rate; hot isostatic pressing (HIP) temperature and time; and powder oxygen content on consolidation density, kinetics, microstructure, crystallographic texture, and mechanical properties have been evaluated. In general, higher temperatures and longer hold times resulted in higher density compacts with larger grain sizes for both sintering and HIP'ing. HIP'ed compacts were consistently higher in density than sintered products. The higher oxygen content powders resulted in finer grained, higher density HIP'ed products than the low oxygen powders. Texture analysis showed that the isostatically processed powder products demonstrated a near random texture. This resulted in isotropic properties in the final product. Mechanical testing results showed that the HIP'ed powder products had consistently higher flow stresses than conventionally produced plates, and the sintered compacts were comparable to the plate material. A micromechanics model (Ashby HIP model) has been employed to predict the mechanisms active in the consolidation processes of cold isostatic pressing (CIP), HIP and sintering. This model also predicts the density of the end product and whether grain growth should be expected under the applied processing conditions

  17. Carbochlorination kinetics of tantalum and niobium pentoxides

    International Nuclear Information System (INIS)

    Allain, E.; Gaballah, I.; Garcia, F.; Ferreira, S.; Ayala, J. N.; Hernandez, A.

    1999-01-01

    The carbochlorination kinetics of pure Nb 2 O 5 and Ta 2 O 5 by gas mixture (CL 2 +CO+N 2 ) between 380 and 1,000 degree centigree is studied. A calculation of the standard free energy of the carbochlorination reactions is made. A diagram of the phases stability is drawn. The influence of the gas flow, temperature and the partial pressure of Cl 2 and Co at temperatures below 650 degree centigree on the reaction rate is studied. The apparent activation energy is approximately 75 and 110 kJ/mol for Nb 2 O 5 and Ta 2 O 5 , respectively. At temperatures above 650 degree centigree the Arrhenius diagram presents and anomaly which may be attributed to the decomposition of the COCL 2 formed in situ. The apparent reaction order of the carbochlorination of these oxides against Cl 2 +CO is approximately 2. The carbochlorination rates of these oxides are much greater than those of chlorination by Cl 2 +N 2 . The carbochlorination kinetics of tin furnace slag leaching concentrates containing tantalum and niobium compounds are also studied and compared with the carbochlorination kinetics of the pure oxides. (Author) 14 refs

  18. Dynamic material properties of refractory metals: tantalum and tantalum/tungsten alloys

    International Nuclear Information System (INIS)

    Furnish, M.D.; Lassila, D.H.; Chhabildas, L.C.; Steinberg, D.J.

    1996-01-01

    We have made a careful set of impact wave-profile measurements (16 profiles) on tantalum and tantalum-tungsten alloys at relatively low stresses (to 15 GPa). Alloys used were Ta 96.5 W 3.5 and Ta 86.5 W 13.5 (wt%) with oxygen contents of 30 endash 70 ppm. Information available from these experiments includes Hugoniot, elastic limits, loading rates, spall strength, unloading paths, reshock structure and specimen thickness effects. Hugoniot and spall properties are illustrated, and are consistent with expectations from earlier work. Modeling the tests with the Steinberg-Guinan-Lund rate-dependent material model provides for an excellent match of the shape of the plastic loading wave. The release wave is not well modeled due to the absence of the dynamic Bauschinger effect. There is also a discrepancy between experiments and calculations regarding the relative timing of the elastic and plastic waves that may be due to texture effects. copyright 1996 American Institute of Physics

  19. Material removal mechanisms in electrochemical-mechanical polishing of tantalum

    International Nuclear Information System (INIS)

    Gao, F.; Liang, H.

    2009-01-01

    Material removal mechanisms in tantalum chemical-mechanical polishing (CMP) and electrochemical-mechanical polishing (ECMP) were investigated using the single frequency electrochemical impedance spectroscopy (EIS). Through measuring the impedance of the tantalum surface, the single frequency EIS scan made it possible to observe the CMP and ECMP processes in situ. The impedance results presented competing mechanisms of removal and formation of a surface oxide layer of tantalum. Analysis indicated that the thickness of the oxide layer formed during polishing was related to the mechanical power correlated to the friction force and the rotating speed. Furthermore, the rate of growth and removal of the oxide film was a function of the mechanical power. This understanding is beneficial for optimization of CMP and ECMP processes.

  20. An investigation of tantalum and niobium contents by nuclear technique

    International Nuclear Information System (INIS)

    Patmasiriwat, N.

    1981-01-01

    The objective of this experimental study was to find suitable nuclear techniques to determine the quantities of niobium and tantalum in columbite. The study has been performed by using radioisotope X-ray fluorescent technique (X RF) and neutron activation analysis (NAA). The results showed a good agreement between these two techniques. Nevertheless, with NAA, if there is uranium in the sample, the spectrum of niobium will be interfered. So practically, on the basis of accuracy and speed of determination, X-ray fluorescence is more suitable than NAA to determine the quantity of niobium while tantalum is preferable to use NAA. The detection limit of niobium and tantalum using the above techniques are 0.661% and 0.1 mg respectively

  1. Behaviour of tantalum- and ceramics implants in the organism

    International Nuclear Information System (INIS)

    Reich, M.

    1987-01-01

    Studies of human and animal tissues after the use of orthopaedic implants were carried out by means of instrumental neutron activation analysis (INAA), as well as studies on the corrosion behaviour of tantalum by means of tracer techniques. After the use of an Al 2 O 3 -ceramic-metal compound prosthesis of the hip joint samples from the joint capsule and the Fascia Lata of 9 patients were studied. The measured Al amounts in the capsule tissues were greater than the normal values by up to 3 orders of magnitude. The corrosion experiment with tantalum was carried out in Ringer's solution as a model of body fluids. Local and systemic changes because of tantalum implants in animal experiments showed massive local stress of the contact tissue as a result of corrosion. Along with this, increased values of Ta were found in the spleen and the liver. (orig./RB) [de

  2. Photo field emission spectroscopy of the tantalum band structure

    International Nuclear Information System (INIS)

    Kleint, Ch.; Radon, T.

    1978-01-01

    Photo field emission (PFE) currents of clean and barium covered tantalum tips have been measured with single lines of the mercury arc spectrum and phase-sensitive detection. Field strength and work function were determined from Fowler-Nordheim plots of the FE currents. Shoulders in the PFE current-voltage characteristics could be correlated to transitions in the band structure of tantalum according to a recently proposed two-step PFE model. A comparison with the relativistic calculations of Mattheiss and the nonrelativistic bands of Petroff and Viswanathan shows that Mattheiss' bands are more appropriate. Beside direct transitions several nondirect transitions from the different features composing the upper two density of states maxima below the Fermi edge of tantalum have been found. (Auth.)

  3. Change in lattice parameter of tantalum due to dissolved hydrogen

    Directory of Open Access Journals (Sweden)

    Gyanendra P. Tiwari

    2012-06-01

    Full Text Available The volume expansion of tantalum due to the dissolved hydrogen has been determined using Bragg equation. The hydrogen was dissolved in the pure tantalum metal at constant temperature (360 °C and constant pressure (132 mbar by varying the duration of hydrogen charging. The amount of dissolved hydrogen was within the solid solubility limit. The samples with different hydrogen concentration were analyzed by X-ray diffraction technique. Slight peak shifts as well as peak broadening were observed. The relative changes of lattice parameters plotted against the hydrogen concentration revealed that the lattice parameters varied linearly with the hydrogen concentration.

  4. Hydrogen adsorption on skeletal rhodium-tantalum electrodes-catalysts

    International Nuclear Information System (INIS)

    Tsinstevich, V.M.; Krejnina, N.M.

    1975-01-01

    Skeleton rhodium-tantalic catalyst electrodes with a tantalum mass percentage of 0 to 100 have been obtained by the methodology of Crupp and others. The hydrogen adsorption is studied through the method of removing the galvano-static and potentiodynamic curves of charging in sulfuric acid and potassium hydroxide. It has been discovered that the maximum adsorption ability relatively to the hydrogen can be observed in an alloy with a 5% tantalum contents. The energetic characteristics of the alloys are higher in alkali than in acid

  5. Electromigration of hydrogen and deuterium in vanadium, niobium, and tantalum

    International Nuclear Information System (INIS)

    Jensen, C.L.

    1977-10-01

    The electric mobility and effective valence of hydrogen and deuterium in vanadium, niobium, tantalum and three niobium-tantalum alloys were measured. A resistance technique was used to directly determine the electric mobility of hydrogen and deuterium at 30 0 C while a steady-state method was used to measure the effective valence. The use of mass spectrographic techniques on a single specimen which contained both hydrogen and deuterium greatly increased the precision with which the isotope effect in the effective valence could be measured

  6. Liquid kit for preparation of {sup 188}rhenium-etidronate

    Energy Technology Data Exchange (ETDEWEB)

    Marczewski, Barbara; Dias, Carla Roberta; Moraes, Vanessa; Osso Junior, Joao Alberto [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), SP (Brazil). Centro de Radiofarmacia]. E-mail: baszot@gmail.com

    2005-10-15

    The aim of this study was the preparation of a liquid kit for radiolabeling of {sup 188} Re-HEDP (hydroxyethylidene diphosphonate). {sup 188} Re was obtained from alumina based {sup 188} W/{sup 188} Re generators. This paper reports the efficacy of a cold kit stored for more than two weeks, determined by the dependence of the radiolabeling yields of {sup 188} Re-HEDP on the incubation time, reducing agent concentration, the effects of concentration of ligand, the p H of the reaction and the temperature. The cold kits showed a good stability when carrie-free rhenium-188 was added in the reaction mixture. (author)

  7. Liquid kit for preparation of 188rhenium-etidronate

    International Nuclear Information System (INIS)

    Marczewski, Barbara; Dias, Carla Roberta; Moraes, Vanessa; Osso Junior, Joao Alberto

    2005-01-01

    The aim of this study was the preparation of a liquid kit for radiolabeling of 188 Re-HEDP (hydroxyethylidene diphosphonate). 188 Re was obtained from alumina based 188 W/ 188 Re generators. This paper reports the efficacy of a cold kit stored for more than two weeks, determined by the dependence of the radiolabeling yields of 188 Re-HEDP on the incubation time, reducing agent concentration, the effects of concentration of ligand, the p H of the reaction and the temperature. The cold kits showed a good stability when carrie-free rhenium-188 was added in the reaction mixture. (author)

  8. Production of {sup 186}Re and {sup 188}Re, and synthesis of {sup 188}Re-DTPA

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Kazuyuki; Motoishi, Shoji; Kobayashi, Katsutoshi; Izumo, Mishiroku [Department of Radioisotopes, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan); Musdja, Muhammad Yanis

    1999-08-01

    Production of radioactive rhenium isotopes {sup 186}Re and {sup 188}Re, and synthesis of {sup 188}Re-DTPA have been studied. For {sup 186}Re, a production method by the {sup 185}Re(n, {gamma}) {sup 186}Re reaction in a reactor has been established. For {sup 188}Re, a production method by the double neuron capture reaction of {sup 186}W, which produces a {sup 188}W/{sup 188}Re generator, has been established. For synthesis of {sup 188}Re-DTPA, the optimum conditions, including pH, the amounts of regents and so on, have been determined. (author)

  9. 188Re(V) Nitrido Radiopharmaceuticals for Radionuclide Therapy.

    Science.gov (United States)

    Boschi, Alessandra; Martini, Petra; Uccelli, Licia

    2017-01-19

    The favorable nuclear properties of rhenium-188 for therapeutic application are described, together with new methods for the preparation of high yield and stable 188 Re radiopharmaceuticals characterized by the presence of the nitride rhenium core in their final chemical structure. 188 Re is readily available from an 188 W/ 188 Re generator system and a parallelism between the general synthetic procedures applied for the preparation of nitride technetium-99m and rhenium-188 theranostics radiopharmaceuticals is reported. Although some differences between the chemical characteristics of the two metallic nitrido fragments are highlighted, it is apparent that the same general procedures developed for the labelling of biologically active molecules with technetium-99m can be applied to rhenium-188 with minor modification. The availability of these chemical strategies, that allow the obtainment, in very high yield and in physiological condition, of 188 Re radiopharmaceuticals, gives a new attractive prospective to employ this radionuclide for therapeutic applications.

  10. 188Re(V) Nitrido Radiopharmaceuticals for Radionuclide Therapy

    Science.gov (United States)

    Boschi, Alessandra; Martini, Petra; Uccelli, Licia

    2017-01-01

    The favorable nuclear properties of rhenium-188 for therapeutic application are described, together with new methods for the preparation of high yield and stable 188Re radiopharmaceuticals characterized by the presence of the nitride rhenium core in their final chemical structure. 188Re is readily available from an 188W/188Re generator system and a parallelism between the general synthetic procedures applied for the preparation of nitride technetium-99m and rhenium-188 theranostics radiopharmaceuticals is reported. Although some differences between the chemical characteristics of the two metallic nitrido fragments are highlighted, it is apparent that the same general procedures developed for the labelling of biologically active molecules with technetium-99m can be applied to rhenium-188 with minor modification. The availability of these chemical strategies, that allow the obtainment, in very high yield and in physiological condition, of 188Re radiopharmaceuticals, gives a new attractive prospective to employ this radionuclide for therapeutic applications. PMID:28106830

  11. A review on the current status and production technology for {sup 188}W-{sup 188}Re generator system

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, R. A.; Han, H. S.; Cho, W. K.; Park, U. J.; Kim, Y. M

    1998-11-01

    The current status of {sup 188}W-{sup 188}Re generator production technology were reviewed in PART 1. Main interests were given to the aspects of {sup 188}W reactor production, irradiated targets reprocessing and generator loading technologies, such as alumina type and gel type generators. In order to develop the more convenient and advanced {sup 188}W-{sup 188}Re generator, further studies must be carried out to get the precise evaluation of production and burn-up cross section of {sup 188}W, the more easily realizable generator loading procedure, and also to optimize the column and generator design to compensate the deterioration of generator performance because of parent radionuclide decay. By irradiation of {sup 186}W enriched sample, {sup 188}W-{sup 188}Re generator production experiments were performed to evaluate the possibility of {sup 188}W-{sup 188}Re generator production using HANARO, and PART 2 describes about the experiments. The experimental results shows the possibility of practical {sup 188}W-{sup 188}Re generator production using of low-specific activity {sup 188}W produced in HANARO. (author). 79 refs., 4 tabs., 26 figs.

  12. 2014 NEPP Tasks Update for Ceramic and Tantalum Capacitors

    Science.gov (United States)

    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.

  13. Electron microprobe analysis of tantalum--nitride thin films

    International Nuclear Information System (INIS)

    Stoltz, D.L.; Starkey, J.P.

    1979-06-01

    Quantitative chemical analysis of 500- and 2000-angstrom tantalum--nitride films on glass substrates has been accomplished using an electron microprobe x-ray analyzer. In order to achieve this analysis, modifications to the microprobe were necessary. A description of the calibration procedure, the method of analysis, and the quantitative results are discussed

  14. Evaluation of residual stress in sputtered tantalum thin-film

    Energy Technology Data Exchange (ETDEWEB)

    Al-masha’al, Asa’ad, E-mail: asaad.al@ed.ac.uk; Bunting, Andrew; Cheung, Rebecca

    2016-05-15

    Highlights: • Tantalum thin-films have been deposited by DC magnetron sputtering system. • Thin-film stress is observed to be strongly influenced by sputtering pressure. • Transition towards the compressive stress is ascribed to the annealing at 300 °C. • Expose thin-film to air ambient or ion bombardment lead to a noticeable change in the residual stress. - Abstract: The influence of deposition conditions on the residual stress of sputtered tantalum thin-film has been evaluated in the present study. Films have been deposited by DC magnetron sputtering and curvature measurement method has been employed to calculate the residual stress of the films. Transitions of tantalum film stress from compressive to tensile state have been observed as the sputtering pressure increases. Also, the effect of annealing process at temperature range of 90–300 °C in oxygen ambient on the residual stress of the films has been studied. The results demonstrate that the residual stress of the films that have been deposited at lower sputtering pressure has become more compressive when annealed at 300 °C. Furthermore, the impact of exposure to atmospheric ambient on the tantalum film stress has been investigated by monitoring the variation of the residual stress of both annealed and unannealed films over time. The as-deposited films have been exposed to pure Argon energy bombardment and as result, a high compressive stress has been developed in the films.

  15. Laser welding of a beryllium/tantalum collimator

    International Nuclear Information System (INIS)

    Lingenfelter, A.C.; Anglin, C.D.

    1985-01-01

    This report describes the methods utilized in the fabrication of a collimator from 0.001 inch thick beryllium and tantalum foil. The laser welding process proved to be an acceptable method for joining the beryllium in a standing edge joint configuration

  16. 46 CFR 188.10-11 - Chemistry laboratory.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Chemistry laboratory. 188.10-11 Section 188.10-11 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS GENERAL PROVISIONS Definition of Terms Used in This Subchapter § 188.10-11 Chemistry laboratory. This term includes...

  17. 46 CFR 154.188 - Membrane tank: Inner hull steel.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Membrane tank: Inner hull steel. 154.188 Section 154.188... STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Hull Structure § 154.188 Membrane tank: Inner hull steel. For a vessel with membrane tanks, the inner hull...

  18. 46 CFR 188.10-59 - Recognized classification society.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Recognized classification society. 188.10-59 Section 188... VESSELS GENERAL PROVISIONS Definition of Terms Used in This Subchapter § 188.10-59 Recognized classification society. This term means the American Bureau of Shipping or other classification society...

  19. 46 CFR 188.10-3 - Approved container.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Approved container. 188.10-3 Section 188.10-3 Shipping... PROVISIONS Definition of Terms Used in This Subchapter § 188.10-3 Approved container. This term means a container which is properly labeled, marked and approved by DOT for the commodity which it contains. [CGFR...

  20. Affinity of hydroxyapatite by radionuclides parent/child in 188Re/188W generator for radiotherapy

    International Nuclear Information System (INIS)

    Carrera D, A. A.; Badillo A, V.; Badillo A, V. E.; Monroy G, F.

    2009-10-01

    To assess the feasibility of using apatites as matrices of 188 W/ 188 Re generator is essential to obtain the distribution coefficients as much of parent radionuclide as child radionuclide in apatite, that is to say to know their affinity for the solid. It was selected the mineral species more representative as adsorbent, the hydroxyapatite Ca 10 (PO 4 ) 6 (OH) 2 it is known for its great capacity of ions retention and by presenting a large affinity for anionic species in their surface. In this paper we use a synthetic hydroxyapatite marketed by Bio-Rad. This paper presents the preliminary results regarding the affinity of hydroxyapatite for the anionic species tungstates (WO 4 2- ) and perrhenates (ReO 4 - in EDTA, as background electrolyte expressed as distribution coefficients between two immiscible phases obtained with the help of radioactive tracers 187 W and 188 Re respectively. The retention measures of these ions, traces show that Bio-Gel hydroxyapatite presents moderate values of distribution coefficients for anionic species of W(Vi) in EDTA 0.01 mol/L that are in the range p H 5 to 6.5; the parent radionuclide of generator 188 Re/ 188 W is fixed but not enough to consider it a good absorbent. By contrast, the fixation of perrhenate ions is virtually wiped as may be easily removed from a hydroxyapatite column packed with a saline solution. The influence of this saline solution in the removal of perrhenate ions is null practically. (Author)

  1. Multi-scale Modeling of Plasticity in Tantalum.

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Hojun [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Battaile, Corbett Chandler. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Carroll, Jay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Buchheit, Thomas E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Boyce, Brad [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Weinberger, Christopher [Drexel Univ., Philadelphia, PA (United States)

    2015-12-01

    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 describing 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, direct

  2. Phenomenological effets of tantalum incorporation into diamond films: Experimental and first principle studies

    Energy Technology Data Exchange (ETDEWEB)

    Ullah, Mahtab, E-mail: mahtabullah@bzu.edu.pk [Department of Physics, Bahauddin Zakariya University Multan (Pakistan); Rana, Anwar Manzoor; Ahmad, E. [Department of Physics, Bahauddin Zakariya University Multan (Pakistan); Raza, Rizwan [Department of Physics, COMSATS Institute of Information Technology, Lahore-54000 (Pakistan); Hussain, Fayyaz [Department of Physics, Bahauddin Zakariya University Multan (Pakistan); Hussain, Akhtar; Iqbal, Muhammad [Theoretical Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan)

    2016-09-01

    Graphical abstract: - Highlights: • Fabrication of tantalum incorporated diamonds films using HFCVD technique. • Decrease in resistivity by increasing tantalum content in diamond thin films. • Electronic structure calculations of tantalum incorporated diamonds films through VASP code. • A rise of bond length and bond angles by addition of tantalum in the diamond lattice. • Confirmation of decrease of resistivity by adding tantalum due to creation of impurity states in the bandgap. - Abstract: Tantalum (Ta) incorporated diamond films are synthesized on silicon substrate by chemical vapor deposition under gas mixture of CH{sub 4} + H{sub 2}. Characterizations of the resulting films indicate that morphology and resistivity of as-grown diamond films are significantly influenced by the process parameters and the amount of tantalum incorporated in the diamond films. XRD plots reveal that diamond films are composed of TaC along with diamond for higher concentration of tantalum and Ta{sub 2}C phases for lower concentration of tantalum. EDS spectra confirms the existence of tantalum in the diamond films. Resistivity measurements illustrate a sudden fall of about two orders of magnitude by the addition of tantalum in the diamond films. Band structure of Ta-incorporated diamond has been investigated based on density functional theory (DFT) using VASP code. Band structure calculations lead to the semiconducting behavior of Ta-incorporated diamond films because of the creation of defects states inside the band gap extending towards conduction band minimum. Present DFT results support experimental trend of resistivity that with the incorporation of tantalum into diamond lattice causes a decrease in the resistivity of diamond films so that tantalum-incorporated diamond films behave like a good semiconductor.

  3. Issues associated with the use of the Tungsten-188/Rhenium188 generator and concentrator system and preparation of Re-188 HDD: A report

    International Nuclear Information System (INIS)

    Knapp, F.F.Jr.; Turner, J.H.; Jeong, J.-M.; Padhy, A.K.

    2004-01-01

    The ready availability of no-carrier-added Rhenium-188 from the Tungsten-188/Rhenium-188 generator represents an important source of a therapeutic radioisotope for a broad range of therapeutic applications in nuclear medicine, oncology, rheumatology and interventional cardiology. The International Atomic Energy Agency (IAEA) is coordinating a clinical trial involving the use of Rhenium188-Lipiodol for therapy of hepatocellular carcinoma. This report summarizes the experience of investigators at ten participating centres associated with the use and performance of the Tungsten-188/Rhenium-188 generators and the preparation and handling of the Re-188 HDD agent. This evaluation has demonstrated the cost effective provision of on-site therapeutic activities of Rhenium-188 and recommendations are made for further development of the next generator prototype in light of this international experience. The high bolus volumes (20-40 ml) of the ORNL generator requires post elution concentration of the Re-188 bolus by passage through the tandem silver cation/anion column system. The high back pressure often encountered during generator elution through the silver cation/anion concentrator system has been identified as a potential problem. The details of a method involving in house preparation of the silver cation columns were provided and implementation of this method for Re-188 bolus concentration is recommended. It is also recommended that ORNL investigators reassess the possibility of increasing Tungsten generator loading capacity and the use of higher specific activity Tungsten-188, with a view to reducing the generator bolus volume. The Re-188 HDD/Lipiodol conjugate?;ate is used in this IAEA trial for radioembolytic therapy of primary liver cancer, and methods for preparation of Re-188 HDD and its extraction into Lipiodol are discussed. Since Re-188 HDD binds to glass surfaces, the recovery yields are variable and can be as low as 40-45%. In an effort to maximize the

  4. Rhenium 188 labelling of peptide conjugates

    International Nuclear Information System (INIS)

    Melendez-Alafort, Laura

    2001-01-01

    Many human tumours express high levels, of somatostatin receptors. In order to make possible a radiotherapeutic treatment of this kind for tumour a series of somatostatin analogues that can tightly chelate beta emitting isotopes have been developed in recent years. The work carried out for this thesis has been aimed towards development of a new therapeutic radiopharmaceutical for treatment of somatostatin receptor positive tumours. The first chapters describe work with technetium-99m to establish the labelling and analytical conditions for a somatostatin analogue, [Tyr 3 ]-octreotide (TOC), as a precursor to undertaking labelling studies with the beta emitter rhenium-188. 6-Hydrazinopyridine-3-carboxylic acid (HYNIC) was conjugated to TOC and labelled with 99m using different coligands. Then the stability, receptor binding and biodistribution of each complex were assessed. 99m Tc-HYNIC-TOC using EDDA as coligand showed the best characteristics, and was superior for tumour imaging in humans than the commercially available 111 In-DTPA-octreotide. The conditions for labelling the HYNIC-TOC conjugate with 188 Re were then optimised using tricine as a co-ligand. A labelling yield of ∼80% was achieved. After purification however, the stability of the complex was low. The use of other coligand systems which had proved useful for 99m Tc labelling was explored, but yields were very poor. Other chelators such as diethylenetriamine pentaacetic acid (DTPA), dimercaptosuccinic acid (DMSA) and mercaptoacetyltriglycine (MAG 3 ) were studied as potential co-ligand agents to label the HYNIC-TOC conjugate with 188 Re but, again low yields of the labelled peptide complexes were achieved. A novel 188 Re-HYNIC complex was prepared in high yields using N-N-disubstituted dithiocarbamates as coligands. However to date, the specific activities achieved with this system are relatively low. The use of the [ 99m Tc(CO) 3 (H 2 O) 3 ] complex to label the HYNIC-TOC conjugate was investigated

  5. Monoclonal Antibodies Radiolabeling with Rhenium-188 for Radioimmunotherapy

    Science.gov (United States)

    Martini, Petra; Pasquali, Micol

    2017-01-01

    Rhenium-188, obtained from an alumina-based tungsten-188/rhenium-188 generator, is actually considered a useful candidate for labeling biomolecules such as antibodies, antibody fragments, peptides, and DNAs for radiotherapy. There is a widespread interest in the availability of labeling procedures that allow obtaining 188Re-labeled radiopharmaceuticals for various therapeutic applications, in particular for the rhenium attachment to tumor-specific monoclonal antibodies (Mo)Abs for immunotherapy. Different approaches have been developed in order to obtain 188Re-radioimmunoconjugates in high radiochemical purity starting from the generator eluted [188Re]ReO4−. The aim of this paper is to provide a short overview on 188Re-labeled (Mo)Abs, focusing in particular on the radiolabeling methods, quality control of radioimmunoconjugates, and their in vitro stability for radioimmunotherapy (RIT), with particular reference to the most important contributions published in literature in this topic. PMID:28951872

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

    Science.gov (United States)

    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

  7. Carbochlorination kinetics of tantalum and niobium pentoxides

    Directory of Open Access Journals (Sweden)

    Allain, E.

    1999-08-01

    Full Text Available The carbochlorination kinetics of pure Nb2O5 and Ta2O5 by gas mixture (C12 + CO + N2 between 380 and 1,000 °C is studied. A calculation of the standard free energy of the carbochlorination reactions is made. A diagram of the phases stability is drawn. The influence of the gas flow, temperature and the pardal pressure of Cl2 and CO at temperatures below 650 °C on the reaction rate is studied. The apparent activation energy is approximately 75 and 110 kJ/mol for Nb2Os and Ta2O5, respectively. At temperatures above 650°C the Arrhenius diagram presents an anomaly which may be attributed to the decomposition of the COCl2 formed in situ. The apparent reaction order of the carbochlorination of these oxides against Cl2+CO is approximately 2. The carbochlorination rates of these oxides are much greater than those of chlorination by Cl2 + N2. The carbochlorination kinetics of tin furnace slag leaching concentrates containing tantalum and niobium compounds are also studied and compared with the carbochlorination kinetics of the pure oxides.

    En este trabajo se estudia la cinética de carbocloruración del Nb2O5 y del Ta2O5 por la mezcla de gases (Cl2 + CO + N2 entre 380 y 1000°C. Se hace un cálculo de la energía libre estándar de carbocloruración y se dibujan los diagramas de equilibrio de fases. Se estudia la influencia del flujo de gas, la temperatura y la presión parcial de Cl2 y CO a temperaturas por debajo de 650°C sobre la velocidad de reacción. La energía de activación es aproximadamente 75 y 110 kJ/mol para el Nb2O5 y el Ta2O5, respectivamente. A temperaturas por encima de 650°C, el diagrama de Arrhenius presenta una anomalía que puede ser atribuida a la

  8. Absolute Transition Rates in {sup 188}lr

    Energy Technology Data Exchange (ETDEWEB)

    Malmskog, S G; Berg, V

    1969-09-15

    Half-lives of several excited levels in {sup 188}lr have been measured using an electron-electron delayed coincidence spectrometer. Active {sup 188}Pt sources were prepared from spallation products using the ISOLDE on-line mass separator facility at CERN. The following half-lives were obtained: T{sub 1/2} (54.8 keV level) = (1.93 {+-} 0.10) nsec; T{sub 1/2} (96.7 keV level) = (0.59 {+-} 0.12) nsec; T{sub 1/2} (187.6 keV level) = (0.056 {+-} 0.013) nsec; T{sub 1/2} (195.1 keV level) = (0.051 {+-} 0.010) nsec; T{sub 1/2} (478. 3 keV level) {<=} 0.15 nsec The 54.8 keV transition was found to have an enhanced E2 transition probability indicating a collective character for this transition.

  9. Study of electrochemical behaviour of tantalum in molten alkali metal chlorides

    International Nuclear Information System (INIS)

    Bajmakov, A.N.; Ezrokhina, A.M.; Sashinina, O.A.; Shkol'nikov, S.N.

    1985-01-01

    Equilibrium potentials of metallic tantalum in the melt TaCl 5 +KCl-NaCl are studied. Are average degree of tantalum ion oxidation, which are in equilibrium with metallic tantalum, is determined. Anodic behaviour of tantalum in equimolar mixture of potassium and sodium chlorides with Ta and F ion additions is considered. An average degree of oxidation of Ta ions, which transfer into the melt, depending on current density, is determined. It is established that tantalum is dissolved in the regime of diffusional kinetics. It is shown that tantalum corrodes in equimolar mixture of potassium and sodiUm chlorides, at that, corrosion rate increases with introdUction of Ta and F ions into solution. The corrosion is of electrochemical nature and it proceeds in the regime of diffusional kinetics

  10. Separation of niobium and tantalum by paper chromatography and their following spectrographic determination

    International Nuclear Information System (INIS)

    Moroshkina, T.M.; Peres Sanfiel', F.

    1975-01-01

    The paper presents the results of an investigation into the use of water-saturated furfural to separate niobium and tantalum in a 1:1 ratio by means of ascending paper chromatography. The influence of sulphuric acid, ammonium fluoride and hydrofluoric acid concentrations on the completeness of the niobium and tantalum separation was investigated, the extent of the separation being checked by a spectral method. The results indicate that the use of furfural creates favourable conditions for niobium and tantalum separation. The purest tantalum is obtained at concentrations of sulphuric acid 600 k/l, hydrofluoric acid 4.6% and ammonium fluoride 30 g/l. To obtain pure niobium the acid concentrations remain the same but the quantity of ammonium fluoride is doubled. The fluoride ion concentration has a significant effect on the completeness of niobium and tantalum separation. The variation coefficient for the niobium determination is 14%, for the tantalum determination 1O% (author)

  11. Synthesis of {sup 188}Re-DMSA complex using carrier-free {sup 188}Re

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Kazuyuki; Izumo, Mishiroku [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Islam, M S

    1997-03-01

    The synthesis of rhenium-DMSA labelled compound using carrier-free {sup 188}Re from the {sup 188}W/{sup 188}Re generator has been carried out. Stannous chloride was used as the reducing agent for reduction of rhenium and ascorbic acid was used as an antioxidant in the reaction media. The dependence of the yield of Re-DMSA complex upon the concentration of reducing agent, pH, reaction time, anti-oxidant, carrier and temperature was investigated. Under optimum conditions, the yield of Re-DMSA complexes were more than 98% for the carrier-free as well as carrier-added {sup 188}Re. The stability of the Re-DMSA complexes at different pH and time were also investigated. It was found that the Re-DMSA complex was very stable and did not undergo any changes or decomposition with the changes of pH from its initial values even after 48 hours of pH change for carrier-free as well as carrier-added complexes. (author)

  12. Reaction of tantalum-alkyne complexes with isocyanates or acyl cyanides

    International Nuclear Information System (INIS)

    Kataoka, Yasutaka; Oguchi, Yoshiyuki; Yoshizumi, Kazuyuki; Miwatashi, Seiji; Takai, Kazuhiko; Utimoto, Kiitiro

    1992-01-01

    Treatment of alkynes with low-valent tantalum derived from TiCl 5 and zinc produces tantalum-alkyne complexes (not isolated), which react in situ with phenyl isocyanate (or butyl isocyanate) to give (E)-α, β-unsaturated amides stereoselectively. The tantalum-alkyne complexes also react with acyl cyanides in the presence of BF 3 ·OEt 2 to give α-cyanohydrins. In both reactions, filtration of the reaction mixture containing the tantalum-alkyne complexes before addition of isocyanates (or acyl cyanides) is indispensable to obtain good yields. (author)

  13. Kinetic Study of the Chemical Vapor Deposition of Tantalum in Long Narrow Channels

    DEFF Research Database (Denmark)

    Mugabi, James Atwoki; Eriksen, Søren; Petrushina, Irina

    2016-01-01

    A kinetic study of the chemical vapor deposition of tantalum in long narrow channels is done to optimize the industrial process for the manufacture of tantalum coated plate heat exchangers. The developed model fits well at temperatures between 750 and 850 °C, and in the pressure range of25–990 mbar....... According to the model, the predominant tantalum growth species is TaCl3. The temperature is shown to have a pronounced effect onthe morphology and rate of deposition of the tantalum and an apparent change in deposition mechanism occurs between 850–900 °C, resulting in the deposition rate at 900 °C being...

  14. Corrosion resistance of high-performance materials titanium, tantalum, zirconium

    CERN Document Server

    2012-01-01

    Corrosion resistance is the property of a material to resist corrosion attack in a particular aggressive environment. Although titanium, tantalum and zirconium are not noble metals, they are the best choice whenever high corrosion resistance is required. The exceptionally good corrosion resistance of these high–performance metals and their alloys results from the formation of a very stable, dense, highly adherent, and self–healing protective oxide film on the metal surface. This naturally occurring oxide layer prevents chemical attack of the underlying metal surface. This behavior also means, however, that high corrosion resistance can be expected only under neutral or oxidizing conditions. Under reducing conditions, a lower resistance must be reckoned with. Only very few inorganic and organic substances are able to attack titanium, tantalum or zirconium at ambient temperature. As the extraordinary corrosion resistance is coupled with an excellent formability and weldability these materials are very valua...

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

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Huiliang, E-mail: hlc@mail.sic.ac.cn; Meng, Fanhao; Liu, Xuanyong, E-mail: xyliu@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2016-07-15

    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 be a promising procedure for improving the antibacterial properties for orthopedic and dental implants.

  16. Recent advances in P/M-tantalum products

    International Nuclear Information System (INIS)

    Kumar, P.; Uhlenhut, H.

    2001-01-01

    The metallurgical grade tantalum powder is used for producing parts and mill products. Some of the key requirements include purity, physical characteristics (flow, fill density and compressibility) and interstitial contents. A process to produce 99.99 % pure tantalum powder with less than 150 ppm oxygen has been developed. This powder was consolidated into metallurgical products via conventional P/M processing; resulting products had high purity and low oxygen. It also retained fine grain-size and uniform properties inherent in P/M-derived products. In addition, the desired crystallographic texture was obtained by controlled thermo-mechanical processing (TMP) of the consolidated powder. Fully dense products of this powder were tested for various applications, such as deep drawing, sputtering, ballistics and capacitors. Critical functional requirements in these applications along with the results of evaluations are discussed. (author)

  17. Hydroxyaromatic compounds of tantalum, tungsten, and the lighter actinides

    International Nuclear Information System (INIS)

    Gfaller, H.

    1980-01-01

    Some hydroxyaromatic compounds of the elements tantalum, tungsten, thorium and uranium were prepared as well as the basic materials for these synthesis processes, i.e. metal halides and metal alkoxides. The hydroxyaromatic compounds were studied by elemental analysis, IR spectroscopy, 1 H-NMR spectroscopy (if soluble in suitable solvents) and, in some cases, by X-ray fine structure analysis. (orig./EF) [de

  18. Inter-diffusion study of rhodium and tantalum by RBS

    International Nuclear Information System (INIS)

    Nuttens, V.E.; Hubert, R.L.; Bodart, F.; Lucas, S.

    2005-01-01

    The inter-diffusion of rhodium and tantalum has been studied with the goal of synthesizing an alloy acting as a diffusion barrier for high temperature applications. Rh/Ta sandwiched samples were annealed in vacuum at temperature ranging from 800 to 900 deg. C and from 1000 to 1075 deg. C. The diffusion profiles were obtained by RBS. They suggest the formation of two clearly different phases in each temperature range considered

  19. Preparation of 188Re labelled antibodies

    International Nuclear Information System (INIS)

    Zhu Minghua; Cao Rongzhen; Li Wenxin; Sheng Rong; Yin Duanzhi; He Weiyu; Zhou Wei; Wang Yongxian

    1998-01-01

    A simple technique of directly labelling antibodies with 188 Re has been developed. The reduction of antibody disulfide groups was achieved by incubation of antibody with ascorbic acid (pH = 6.5) for an hour at room temperature and a solution of excess SnCl 2 in sodium gluconate was added to the AA-reduced antibody followed by the addition of perrhenate. Some factors that influence labelling efficiency, such as the pH of the reaction mixture, the labelling time, and the amount of antibodies and reductive agent, were studied experimentally and a better labelling method was established. The labelling yields, as determined by paper chromatography, were greater than 80%

  20. Bone uptake by di and tetraphosphonates labeled with Rhenium-188

    International Nuclear Information System (INIS)

    Faintuch, B.L.; Osso, J.A. Jr.; Muramoto, E.; Faintuch, S.

    2002-01-01

    MDP (methylenediphosphonate) and HEDP (hydroxyethylidenediphosphonate), both diphosphonates, and EDTMP (ethylenediamine tetramethylene phosphonic acid) a tetraphosphonate ligand, have been labeled with 188 Re for use in metastatic bone-pain palliation. The aim of this study was a comparison between the three complexes 188 Re-MDP, 188 Re-HEDP and 188 Re-EDTMP concerning the complexation conditions, in order to achieve maximum yield, stability and bone uptake. Methods: MDP was dissolved in water and HEDP and EDTMP were dissolved in NaOH 1N followed by decreasing pH with HCl 1N. To all mixtures stannous chloride and 188 ReO 4 were added in a nitrogen atmosphere. The preparations were heated in a boiling water bath for 15 min. The yields as well as the radiochemical stability were estimated by ITLC. Different concentrations of phosphonates and stannous chloride were evaluated. Biodistribution studies in swiss mice were done for the three 188 Re-phosphonates that presented the best radiochemical yield. Results: For 188 Re-MDP and 188 Re-HEDP the optimal ligand concentration for maximum complexation was 30 mg whereas for 188 Re-EDTMP, it was 40 mg. The best amount of SnCl 2 .2H 2 O was 2 mg/mL for MDP, 3 mg/mL for HEDP and 1 mg/mL for EDTMP. In these conditions the three complexes showed a complexation yield above 95%. All of them presented 4-hour radiochemical stability without the need for ascorbic acid solution, but for 24 hours this stability existed only in the presence of that substance otherwise re-oxidation of 188 Re occurred. All products showed a great uptake by the kidneys. 188 Re-EDTMP had the greatest uptake by the bone (3.13 ± 0.18% ID/g) followed by 188 Re-MDP (1.18 ± 0.05%ID/g) and 188 Re-HEDP (1.03 ± 0.12 %ID/g), 4 hour postinjection. 188 Re-EDTMP displayed a bone/muscle ratio of 28.5, 188 Re-MDP 4.9 and 188 Re-HEDP 4.9. Conclusion: 188 Re-EDTMP demonstrated the best potential as a radiopharmaceutical for bone cancer pain relief, encouraging further

  1. Random Vibration Testing of Advanced Wet Tantalum Capacitors

    Science.gov (United States)

    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.

  2. Microstructures and phase transformations in interstitial alloys of tantalum

    International Nuclear Information System (INIS)

    Dahmen, U.

    1979-01-01

    The analysis of microstructures, phases, and possible ordering of interstitial solute atoms is fundamental to an understanding of the properties of metal-interstitial alloys in general. As evidenced by the controversies on phase transformations in the particular system tantalum--carbon, our understanding of this class of alloys is inferior to our knowledge of substitutional metal alloys. An experimental clarification of these controversies in tantalum was made. Using advanced techniques of electron microscopy and ultrahigh vacuum techology, an understanding of the microstructures and phase transformations in dilute interstitial tantalum--carbon alloys is developed. Through a number of control experiments, the role and sources of interstitial contamination in the alloy preparation (and under operating conditions) are revealed. It is demonstrated that all previously published work on the dilute interstitially ordered phase Ta 64 C can be explained consistently in terms of ordering of the interstitial contaminants oxygen and hydrogen, leading to the formation of the phases Ta 12 O and Ta 2 H

  3. Carbon monoxide and carbon dioxide interaction with tantalum

    International Nuclear Information System (INIS)

    Belov, V.D.; Ustinov, Yu.K.; Komar, A.P.

    1978-01-01

    The adsorption of carbon monoxide and carbon dioxide on tantalum and the dissolution of these gases in the adsorbent at T >= 300 K have been studied. The flash-filament method (FFM) in a monopole mass-spectrometer and a field emission microscopy was used in the same apparatus. Carbon monoxide and carbon dioxide dissociate on the tantalum surface, carbon monoxide being desorbed in both cases during the flash. The desorption curves of CO reveal three different binding states: two of them (α and β' 1 ) for the adsorbed particles whereas the high temperature desorption state relates to the adsorbate dissolved in the metal. For the β' 1 state of CO the activation energy, the pre-exponential factor and the kinetic order in the kinetic equation of desorption have been estimated. They turned out to be E = 110 kcal/mol, C = 3 X 10 12 sec -1 , and γ = 1. The activation energy of diffusion for CO in tantalum and the energy of outgassing for the metal were found to be 9.4 and 49 kcal/mole, respectively. (Auth.)

  4. Carbon monoxide and carbon dioxide interaction with tantalum

    Energy Technology Data Exchange (ETDEWEB)

    Belov, V D; USTINOV, YU K; KOMAR, A P [AN SSSR, LENINGRAD. FIZIKO-TEKHNICHESKIJ INST.

    1978-03-01

    The adsorption of carbon monoxide and carbon dioxide on tantalum and the dissolution of these gases in the adsorbent at T >= 300 K have been studied. The flash-filament method (FFM) in a monopole mass-spectrometer and a field emission microscopy was used in the same apparatus. Carbon monoxide and carbon dioxide dissociate on the tantalum surface, carbon monoxide being desorbed in both cases during the flash. The desorption curves of CO reveal three different binding states: two of them (..cap alpha.. and ..beta..'/sub 1/) for the adsorbed particles whereas the high temperature desorption state relates to the adsorbate dissolved in the metal. For the ..beta..'/sub 1/ state of CO the activation energy, the pre-exponential factor and the kinetic order in the kinetic equation of desorption have been estimated. They turned out to be E = 110 kcal/mol, C = 3 X 10/sup 12/ sec/sup -1/, and ..gamma.. = 1. The activation energy of diffusion for CO in tantalum and the energy of outgassing for the metal were found to be 9.4 and 49 kcal/mole, respectively.

  5. Recovery of hafnium radioisotopes from a proton irradiated tantalum target

    International Nuclear Information System (INIS)

    Taylor, W.A.; Garcia, J.G.; Hamilton, V.T.; Heaton, R.C.; Jamriska, D.J.; Ott, M.A.; Philips, D.R.; Radzinski, S.D.

    1998-01-01

    The 178m2 Hf nucleus, with its long half-life (31 y) and high-spin isomeric state (16 + ) is desired for new and exotic nuclear physics studies. The Los Alamos Radioisotope Program irradiated a kilogram of natural tantalum at the Los Alamos Meson Physics Facility in early 1981. After fifteen years of decay, this target was ideal for the recovery of 178m2 Hf. There was more than a millicurie of 178m2 Hf produced during this irradiation and there has been a sufficient period of time for most of the other hafnium radioisotopes to decayed away. Traditionally, separation techniques for recovering hafnium isotopes from tantalum targets employ solvent extractions with reagents that are considered hazardous. These techniques are no longer condoned because they generate a mixed-waste (radioactive and hazardous components) that can not be treated for disposal. In this paper we describe a new and unique procedure for the recovery of hafnium radioisotopes from a highly radioactive, proton irradiated, tantalum target using reagents that do not contribute a hazardous waste component. (author)

  6. Poisoning Experiments Aimed at Discriminating Active and Less-Active Sites of Silica-Supported Tantalum Hydride for Alkane Metathesis

    KAUST Repository

    Saggio, Guillaume; Taoufik, Mostafa; Basset, Jean-Marie; Thivolle-Cazat, Jean

    2010-01-01

    Only 50% of the silica-supported tantalum hydride sites are active in the metathesis of propane. Indeed, more than 45% of the tantalum hydride can be eliminated by a selective oxygen poisoning of inactive sites with no significant decrease

  7. Development of a high performance {sup 188}W/{sup 188}Re generator by using a synthetic alumina

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jun Sig [Korea Atomic Energy Research Institute, 1045 Daeduk-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)], E-mail: jlee15@kaeri.re.kr; Lee, Jong-Soup; Park, Ul-Jae; Son, Kwang-Jae; Han, Hyon-Soo [Korea Atomic Energy Research Institute, 1045 Daeduk-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

    2009-07-15

    A synthetic alumina functionalized with a sulfate moiety has been developed as the column material of {sup 99}Mo/{sup 99m}Tc and {sup 188}W/{sup 188}Re generators. This material is synthesized by a sol-gel processing. In order to characterize the adsorbent for the {sup 188}W/{sup 188}Re separation, both batch and column contact experiments were conducted. As a result of the experiments, it is found that the maximum capacity of the adsorbent for tungsten is higher than 450 mg/g. Hence it is possible to produce {approx}3 Ci {sup 188}W/{sup 188}Re generator with only 1 g of the adsorbent from {sup 188}W solutions supplied from ORNL, USA or RIAR, Russia. A demonstration study was conducted to show the performance of an {sup 188}W/{sup 188}Re generator column. In this study, 1 Ci of {sup 188}W purchased from RIAR, Russia, is loaded on a 0.9 cm ID column packed with 0.7 g of the adsorbent. Elution of {sup 188}Re is performed every 4-7 days by using the saline solution for more than three months. Nearly 100% of tungsten is loaded by passing 5 ml of the {sup 188}W solution (pH=8) through the dry packed column at a 1 ml/min flow rate. Elution efficiency of {sup 188}Re is 70-90% by using 5 ml of the saline solution. The ratio of {sup 188}W/{sup 188}Re in the eluted solution is 0.002-0.003%. When a Sep-Pak containing 0.26 g of acid alumina is installed as a tandem column, the ratio is decreased to less than 10{sup -3}%. Thin layer chromatography for the eluted {sup 188}Re solution shows 100% radiochemical purity. Also, alumina content in the eluted solution shows less than 10 ppm. Through this study, the performance of this adsorbent was successfully demonstrated. By using the developed adsorbent, minimization of the generator column and consequently the volume of eluant could be possible while maintaining the quality of {sup 188}Re just as much as that available in the market.

  8. Synthesis and characterization of hydroxyapatite (HAp) for binder tungstate in 188W/188Re generator system

    International Nuclear Information System (INIS)

    Eni Hartati; Yati B Yuliyati; Duyeh Setiawan

    2014-01-01

    In this study, the synthesis of hydroxyapatite has been carried out through a process of precipitation of calcium hydroxide (Ca(OH) 2 ) with phosphoric acid (H 3 PO 4 ) based on acid base reaction process that produce crystalline solid and then it will be used for binder tungstate in 188 W/ 188 Re generator system. The purpose of this study were to characterize the results of synthesized hydroxyapatite and to determine the optimum conditions on generator 188 W/ 188 Re performance such as activation of the heating hydroxyapatite, pH of Na 2 WO 4 , reaction temperature, distribution coefficient and the adsorption capacity (adsorption coefficient) of hydroxyapatite. The characterization of synthesized hydroxyapatite was done using FTIR, XRD and SEM-EDAX, while the determination of the optimum condition of each parameters based on distribution coefficient and adsorption capacity hydroxyapatite using spectrophotometric method. The FTIR results of hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 ) showed the appearance of peaks in the O-H stretching wave number (υ) and 3434.9 cm -1 and 563.8 cm -1 , while the group PO 4 -3 is shown by the P-O bond in (υ) 1033.8 cm -1 . The XRD results indicate that hydroxyapatite had three peaks at 2θ region is 31,875° , 32,205° and 33,080°. Characterization by SEM showed columnar morphology with a particle size of 200 nm. The optimum conditions of each parameter obtained at hydroxyapatite heating temperature 100 °C, Na 2 WO 4 solution pH 3, and the reaction temperature of 60 °C, which gave result on distribution coefficients of 193.74 mL/g and adsorption capacity (adsorption coefficient) of 5.20 mg W/g HAp. (author)

  9. Experimental lumbar spine fusion with novel tantalum-coated carbon fiber implant

    DEFF Research Database (Denmark)

    Li, Haisheng; Zou, Xuenong; Woo, Charlotte

    2007-01-01

    the possibility of coating a biocompatible metal layer on top of the carbon fiber material, to improve its biological performance. Tantalum was chosen because of its bone compatibility, based on our previous studies. A novel spinal fusion cage was fabricated by applying a thin tantalum coating on the surface...

  10. A Novel Method for Assessment of Polyethylene Liner Wear in Radiopaque Tantalum Acetabular Cups

    DEFF Research Database (Denmark)

    Troelsen, Anders; Greene, Meridith E; Ayers, David C

    2015-01-01

    Conventional radiostereometric analysis (RSA) for wear is not possible in patients with tantalum cups. We propose a novel method for wear analysis in tantalum cups. Wear was assessed by gold standard RSA and the novel method in total hip arthroplasty patients enrolled in a randomized controlled...

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

    Science.gov (United States)

    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

  12. Durability of adhesive bonds to uranium alloys, tungsten, tantalum, and thorium

    International Nuclear Information System (INIS)

    Childress, F.G.

    1975-01-01

    Long-term durability of epoxy bonds to alloys of uranium (U-Nb and Mulberry), nickel-plated uranium, thorium, tungsten, tantalum, tantalum--10 percent tungsten, and aluminum was evaluated. Significant strengths remain after ten years of aging; however, there is some evidence of bond deterioration with uranium alloys and thorium stored in ambient laboratory air

  13. 40 CFR 159.188 - Failure of performance information.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Failure of performance information. 159.188 Section 159.188 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... submitted concerning substantiation of any incident of a pest having developed resistance to any pesticide...

  14. 47 CFR 1.88 - Predesignation pleading procedure.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Predesignation pleading procedure. 1.88 Section... Rules of Practice and Procedure Miscellaneous Proceedings § 1.88 Predesignation pleading procedure. In... staff, in its discretion, may in writing, advise such licensee of the general nature of the...

  15. 46 CFR 188.27-1 - Lifesaving appliances and arrangements.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Lifesaving appliances and arrangements. 188.27-1 Section... VESSELS GENERAL PROVISIONS Lifesaving Appliances and Arrangements § 188.27-1 Lifesaving appliances and arrangements. All lifesaving appliances and arrangements shall be in accordance with the requirements for...

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

    Science.gov (United States)

    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.

  17. Bronchography by tantalum aerosols, an experimental investigation of lung clearance and retention

    International Nuclear Information System (INIS)

    Causse, Andre.

    1974-01-01

    Lung clearance of tantalum used as contrast medium has been studied in three animal species: rat, monkey and cat. In rats and monkeys, 80 to 90 percent of the inhaled tantalum was removed with a half life of 10 to 30 hr, but the residual fraction was removed with a half life longer than 100 days; consequently persistent roentgenographic pictures could be observed. These results were in accordance with those obtained by other authors studying dogs and men (accidental inhalation of radioactive tantalum). In cats, about 98 percent was removed with a half life of 15 hr and the remaining fraction with a half life of 18 days. In the three species, the physiological lung clearance mechanisms did not seem disturbed. Microscopic examination showed the peribronchiolar localisation of remaining tantalum in rats and monkeys, with proliferation of granulomes and fibrotic reaction. These results must induce to the greatest care when using tantalum in man in order to outline peripheral airways [fr

  18. Spectrographic determination of impurities in high-purity tantalum oxide and niobium oxide

    International Nuclear Information System (INIS)

    Anderson, S.T.G.; Russell, G.M.

    1990-01-01

    The development of spectrographic methods by direct current arc excitation and carrier distillation for the determination of impurities in tantalum and niobium oxides are described. Iron, silicon, aluminium, titanium, calcium, silver, tin, magnesium, and manganese can be determined in tantalum oxide and niobium oxide in concentrations ranging from 3 to 300 p.p.m. Niobium can be determined in tantalum oxide in concentrations ranging from 10 to 300 p.p.m. Tantalum cannot be determined in niobium oxide, and tungsten cannot be determined in either matrix as a result of the absence of sensitive lines in the spectra of these elements. Relative standard deviations of analyte element concentrations are in the region of 0,18 for tantalum oxide samples, and 0,13 for niobium oxide samples. A detailed laboratory method is included. 4 figs., 4 tabs., 3 refs

  19. HIP (hot isostatic pressing) sintering of Tantalum (Ta) and tantalum carbide (TaC) powder mixture: relations between microstructure and properties

    International Nuclear Information System (INIS)

    Valin, F.; Schnedecker, M.

    1994-01-01

    HIP sintering at 1630 C and 195 MPa, during 2 hours, can be used for complete densification of mixtures of commercial tantalum carbide and tantalum powders. HIPed material properties are depending upon initial compositions. For C/Ta ratios inferior to 80%, the monocarbide structure is preserved. A partial ordering of the carbon vacancies will result, for TaC(0.80), in microhardness maximization. The microstructurally homogenous TaC(0.45) shows an excellent toughness. 2 figs., 2 refs

  20. The pressure, internal energy, and conductivity of tantalum plasma

    Energy Technology Data Exchange (ETDEWEB)

    Apfelbaum, E.M. [Russian Academy of Sciences, Joint Institute for High Temperatures, Department of Computational Physics, Moscow (Russian Federation)

    2017-11-15

    The pressure, internal energy, and conductivity of a tantalum plasma were calculated at the temperatures 10-100 kK and densities less than 3 g/cm{sup 3}. The plasma composition, pressure, and internal energy were obtained by means of the corresponding system of the coupled mass action law equations. We have considered atom ionization up to +3. The conductivity was calculated within the relaxation time approximation. Comparisons of our results with available measurements and calculation data show good agreement in the area of correct applicability of the present model. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Trace diffusion of different nuclear reactions products in polycrystalline tantalum

    International Nuclear Information System (INIS)

    Beyer, G.J.; Fromm, W.D.; Novgorodov, A.F.

    1976-07-01

    Measurements of the lattice diffusion coefficients for carrier free isotopes of Hf, Lu, Yb, Tm, Tb, Gd, Eu, Ba, Cs, Y, Sr, Rb and As in polycrystalline tantalum were made over the temperature range 1700 Fsub(As)>Fsub(lanthanides)>Fsub(Sr)>Fsub(Ba)>Fsub(Hf)>Fsub(Rb)>Fsub(Cs). The data indicate, that the Arrhenius relation was obeyed over the entire temperature range. Within the lanthanide-group no differences in the diffusion velocities could be detected, this fact points to a diffusion mechanism of Me 3+ -ions of lanthanides, Me 2+ -ions of earth alkaline elements and Me + -ions of alkaline elements. (author)

  2. Diffusion-Cooled Tantalum Hot-Electron Bolometer Mixers

    Science.gov (United States)

    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.

  3. Low-temperature diffusion of hydrogen isotopes in tantalum

    International Nuclear Information System (INIS)

    Peichl, R.; Ziegler, P.; Weidinger, A.

    1987-01-01

    The mobility of hydrogen and deuterium in tantalum is investigated in the temperature range between 4.2 and 30 K. On the time scale of the present experiment (25 μs) we find that hydrogen begins to move above 15 K whereas deuterium remains immobile at least up to 30 K. Since the interpretation of the data depends critically on the exact hydrogen configurations a major part of the paper is devoted to this problem. We suggest that hydrogen can exist in fairly localized or more extended states depending on the local homogeneity of the crystal. (orig.)

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

    Science.gov (United States)

    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.

  5. Synergistic helium and deuterium blistering in tungsten–tantalum composites

    Energy Technology Data Exchange (ETDEWEB)

    Dias, M., E-mail: marta.dias@itn.pt [Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Mateus, R.; Catarino, N.; Franco, N. [Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Nunes, D. [CENIMAT-I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Correia, J.B. [LNEG, Laboratório Nacional de Energia e Geologia, Estrada do Paço do Lumiar, 1649-038 Lisboa (Portugal); Carvalho, P.A. [Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); ICEMS, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Hanada, K. [AIST, National Institute of Advanced Industrial Science and Technology, 1-2-1 Namiki, Tsukuba, 305-8564 Ibaraki (Japan); Sârbu, C. [National Institute of Materials and Physics, 105bis Atomistilor street, 077125 Magurele-Ilfov (Romania); and others

    2013-11-15

    Abstruct: Tungsten–tantalum composites with 10 and 20 at.% Ta were prepared by ball milling W powder with Ta fibers and by consolidating the milled materials with spark plasma sintering. The composites were implanted at room temperature with He{sup +} (30 keV with a fluence 5 × 10{sup 21} at/m{sup 2}) and/or D{sup +} (15 keV with a fluence 5 × 10{sup 21} at/m{sup 2}) ion beams. The materials were studied by scanning and high-resolution transmission electron microscopy, both coupled with energy dispersive X-ray spectroscopy, and by X-ray diffraction, Rutherford backscattering spectrometry and nuclear reaction analysis. The microstructure observations revealed that the milling operation resulted in severe fragmentation of the Ta fibers. Furthermore, during the consolidation process the Ta phase acted as oxygen getter and reduced the W oxide present in the original material. The surface of the tungsten–tantalum composites implanted with D{sup +} remained essentially unaltered, while the materials implanted with He{sup +} evidenced blisters on the Ta-rich regions. D retention in the composites increased with He{sup +} pre-implantation.

  6. Synergistic helium and deuterium blistering in tungsten–tantalum composites

    International Nuclear Information System (INIS)

    Dias, M.; Mateus, R.; Catarino, N.; Franco, N.; Nunes, D.; Correia, J.B.; Carvalho, P.A.; Hanada, K.; Sârbu, C.

    2013-01-01

    Abstruct: Tungsten–tantalum composites with 10 and 20 at.% Ta were prepared by ball milling W powder with Ta fibers and by consolidating the milled materials with spark plasma sintering. The composites were implanted at room temperature with He + (30 keV with a fluence 5 × 10 21 at/m 2 ) and/or D + (15 keV with a fluence 5 × 10 21 at/m 2 ) ion beams. The materials were studied by scanning and high-resolution transmission electron microscopy, both coupled with energy dispersive X-ray spectroscopy, and by X-ray diffraction, Rutherford backscattering spectrometry and nuclear reaction analysis. The microstructure observations revealed that the milling operation resulted in severe fragmentation of the Ta fibers. Furthermore, during the consolidation process the Ta phase acted as oxygen getter and reduced the W oxide present in the original material. The surface of the tungsten–tantalum composites implanted with D + remained essentially unaltered, while the materials implanted with He + evidenced blisters on the Ta-rich regions. D retention in the composites increased with He + pre-implantation

  7. Cracking and delamination of vapor-deposited tantalum films

    International Nuclear Information System (INIS)

    Fisher, R.M.; Duan, J.Z.; Liu, J.B.

    1990-01-01

    This paper reports on tantalum films which begin to crack and spall during vapor deposition on glass at a thickness of 180 nm. Islands and ribbons, 10 - 30 μm in size, delaminate by crack growth along the Ta/glass interface for several μm after which the crack penetrates into the glass to a depth of 0.5 - 1 μm and complete spalling occurs. X-ray diffraction showed that about 50% of the original bct, β-tantalum, phase had transformed to the bcc α-Ta phase. When Ta was deposited on glass that was first covered with 52 nm of copper, spalling was observed to begin at a thickness of 105 nm. In this case, the film first cracks and then peels along the Cu/glass interface and curls into scrolls indicating the presence of a small stress gradient. X-ray diffraction of the as-deposited film, and electron diffraction of ion-milled flakes, showed that the Ta films deposited on Cu-coated glass almost completely transform to bcc α-Ta. The critical thickness for delamination along the Cu/glass interface is about 1/2 that for cracking in the glass substrate when an intermediate layer of Cu is not present. All of the above findings are in good agreement with previous observations on Cr films

  8. Characterization of a texture gradient in tantalum plate

    International Nuclear Information System (INIS)

    Wright, S.I.; Gray, G.T. III.

    1994-01-01

    Clark et al. have shown that significant texture gradients can be produced in rolled tantalum plate and that the strength of the gradient is dependent on the processing path. Texture gradients are often ignored because they are time consuming to characterize and add significant complexity to materials modeling. The variation in texture through the thickness of rolled materials is most commonly measured by sectioning samples to different depths through the thickness of the plate and then measuring the texture from these section planes by X-ray diffraction. A new technique based on automatic indexing of electron backscatter diffraction patterns in the scanning electron microscope enables spatially specific orientations to be measured in a practical manner. This technique allows spatial variations in texture to be measured directly enabling gradients in texture to be investigated in more detail than previously possible. This data can be used directly in coupled finite-element/polycrystal-plasticity models to simulate the effects of variations in texture on the plastic behavior of polycrystals. This work examines the variation in texture through the thickness of a tantalum plate and its resultant effect on the compressive deformation of samples prepared from the plate. The characterization of the texture gradient using the automatic point-by-point measurement technique mentioned above is described in detail. The effect of the gradient on the plastic response of through-thickness compression tests is also discussed

  9. NEPP Evaluation of Automotive Grade Tantalum Chip Capacitors

    Science.gov (United States)

    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.

  10. Bacterial adherence to tantalum versus commonly used orthopedic metallic implant materials.

    Science.gov (United States)

    Schildhauer, Thomas A; Robie, Bruce; Muhr, Gert; Köller, Manfred

    2006-07-01

    Evaluation of bacterial adhesion to pure tantalum and tantalum-coated stainless steel versus commercially pure titanium, titanium alloy (Ti-6Al-4V), and grit-blasted and polished stainless steel. Experimental in vitro cell culture study using Staphylococcus aureus and Staphylococcus epidermidis to evaluate qualitatively and quantitatively bacterial adherence to metallic implants. A bacterial adhesion assay was performed by culturing S. aureus (ATCC 6538) and S. epidermidis (clinical isolate) for one hour with tantalum, tantalum-coated stainless steel, titanium, titanium alloy, grit-blasted and polished stainless steel metallic implant discs. Adhered living and dead bacteria were stained using a 2-color fluorescence assay. Adherence was then quantitatively evaluated by fluorescence microscopy and digital image processing. Qualitative adherence of the bacteria was analyzed with a scanning electron microscope. The quantitative data were related to the implant surface roughness (Pa-value) as measured by confocal laser scanning microscopy. Bacterial adherence of S. aureus varied significantly (p = 0.0035) with the type of metallic implant. Pure tantalum presented with significantly (p titanium alloy, polished stainless steel, and tantalum-coated stainless steel. Furthermore, pure tantalum had a lower, though not significantly, adhesion than commercially pure titanium and grit-blasted stainless steel. Additionally, there was a significantly higher S. aureus adherence to titanium alloy than to commercially pure titanium (p = 0.014). S. epidermidis adherence was not significantly different among the tested materials. There was no statistically significant correlation between bacterial adherence and surface roughness of the tested implants. Pure tantalum presents with a lower or similar S. aureus and S. epidermidis adhesion when compared with commonly used materials in orthopedic implants. Because bacterial adhesion is an important predisposing factor in the development of

  11. Spectrochemical determination of tantalum in plutonium metal using direct current plasma emission spectrometry

    International Nuclear Information System (INIS)

    Fadeff, S.K.; Morris, W.F.

    1983-01-01

    Tantalum is determined by direct current plasma spectrometry after separation of plutonium from solution as PuF 3 . After centrifugation of the PuF 3 precipitate, a low level of plutonium remains in solution in sufficient quantity to cause spectral interferences. It is necessary to determine the plutonium by dc plasma spectrometry and apply a correction to determine low tantalum concentrations with good accuracy and precision. Tantalum can be determined down to 0.4 ppM in solution with a relative standard deviation of 10 percent. Better precision can be achieved at higher concentrations. The procedure is simple and convenient for glovebox work. 5 references, 1 figure, 1 table

  12. Synthesis and characterization of tantalum organometallic complexes. Catalytic activity for olefins

    International Nuclear Information System (INIS)

    Baley, A.S.

    1990-11-01

    Synthesis of monoaryloxy (alcoxy) neopentyl compounds is investigated. The tantalum-oxygen bond is formed by two parallel ways from TaCl 5 or TaR 2 Cl 3 with R = neopentyl and the tantalum carbon bond from a neopentyl derivative of the main series. Some compounds were isolated and characterized by NMR, elemental analysis and sometimes X-ray structure, some others are characterized in solution only. Catalytic effect is tested by ethylene dimerization and olefin polymerization. Reactivity of tantalum aryloxy neopentyl in respect to complexing and chelating ligands is studied for preparation of neopentylidene complexes

  13. Structural characterisation of oxygen diffusion hardened alpha-tantalum PVD-coatings on titanium.

    Science.gov (United States)

    Hertl, C; Koll, L; Schmitz, T; Werner, E; Gbureck, U

    2014-08-01

    Titanium substrates were coated with tantalum layers of 5 μm thickness using physical vapour deposition (PVD). The tantalum layers showed a (110)-preferred orientation. The coated samples were hardened by oxygen diffusion. Using X-ray diffraction the crystallographic structure of the tantalum coatings was characterised, comparing untreated and diffusion hardened specimen conditions. Oxygen depth profiles were determined by glow discharge spectrometry. The hardening effect of the heat treatment was examined by Vickers microhardness testing. The increase of surface hardness caused by oxygen diffusion was at least 50%. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. 46 CFR 188.10-21 - Compressed gas.

    Science.gov (United States)

    2010-10-01

    ... PROVISIONS Definition of Terms Used in This Subchapter § 188.10-21 Compressed gas. This term includes any... by the Reid method covered by the American Society for Testing Materials Method of Test for Vapor...

  15. Production of carrier-free 188Re in the past ten years in Taiwan

    International Nuclear Information System (INIS)

    Bor-Tsung Hsieh; Institute of Nuclear Energy Research, Taiwan; Wan-Yu Lin; Tsai-Yueh Luo; Kai-Yuan Cheng

    2007-01-01

    Twenty clinical scale alumina-based 188 W/ 188 Re generators and carrier-free 188 Re has been produced at the Institute of Nuclear Energy Research (INER-Taiwan) for over ten years. 2845.6 GBq (76.9 Ci) of 188 Re-perrhenate solution has been eluted from generators during the past ten years. We have used the harvesting 188 Re solution for labeling radiopharmaceuticals, such as 188 Re-HEDP, 188 Re-MDP, 188 Re-microsphere, 188 Relipiodol, and 188 Re-sulfur colloid, etc. The average eluting yield of 188 Re is 78.6±5.8% that was investigated at 1115 harvesting times from 20 generators. Each generator can be used more than six months but the Millipore needs to be changed every two months for smooth harvesting and high yield of 188 Re solution. (author)

  16. Studies of gel metal-oxide composite samples as filling materials for W-188/Re-188 generator column

    Czech Academy of Sciences Publication Activity Database

    Iller, E.; Polkowska-Motrenko, H.; Lada, W.; Wawszczak, D.; Sypula, M.; Doner, K.; Konior, M.; Milczarek, J.; Zoladek, J.; Ráliš, Jan

    2009-01-01

    Roč. 281, č. 1 (2009), s. 83-86 ISSN 0236-5731. [9th International Conference on Nuclear Analytical Methods in the Life Sciences. Lisbon, 07.09.2008-12.09.2008] Institutional research plan: CEZ:AV0Z10480505 Keywords : W-188/Re-188 generator * W-Zr gels * W-Zr composites * Sol-gel process Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 0.631, year: 2009

  17. Tantalum oxide-based compounds as new non-noble cathodes for polymer electrolyte fuel cell

    International Nuclear Information System (INIS)

    Ishihara, Akimitsu; Tamura, Motoko; Matsuzawa, Koichi; Mitsushima, Shigenori; Ota, Ken-ichiro

    2010-01-01

    Tantalum oxide-based compounds were examined as new non-noble cathodes for polymer electrolyte fuel cell. Tantalum carbonitride powder was partially oxidized under a trace amount of oxygen gas at 900 o C for 4 or 8 h. Onset potential for oxygen reduction reaction (ORR) of the specimen heat-treated for 8 h was 0.94 V vs. reversible hydrogen electrode in 0.1 mol dm -3 sulfuric acid at 30 o C. The partial oxidation of tantalum carboniride was effective to enhance the catalytic activity for the ORR. The partially oxidized specimen with highest catalytic activity had ca. 5.25 eV of ionization potential, indicating that there was most suitable strength of the interaction of oxygen and tantalum on the catalyst surface.

  18. Tantalum Nitride Electron-Selective Contact for Crystalline Silicon Solar Cells

    KAUST Repository

    Yang, Xinbo; Aydin, Erkan; Xu, Hang; Kang, Jingxuan; Hedhili, Mohamed N.; Liu, Wenzhu; Wan, Yimao; Peng, Jun; Samundsett, Christian; Cuevas, Andres; De Wolf, Stefaan

    2018-01-01

    novel electron‐selective, passivating contact for c‐Si solar cells is presented. Tantalum nitride (TaN x ) thin films deposited by atomic layer deposition are demonstrated to provide excellent electron‐transporting and hole‐blocking properties

  19. Thermal and electrical conductivities of high purity tantalum

    International Nuclear Information System (INIS)

    Archer, S.L.

    1978-01-01

    The electrical resistivity and thermal conductivity of three high purity tantalum samples have been measured as functions of temperature over a temperature range of 5K to 65K. Sample purities ranged up to a resistivity ratio of 1714. The highest purity sample had a residual resistivity of .76 x 10 -10 OMEGA-m. The intrinsic resistivity varied as T 3 . 9 from 10K to 31K. The thermal conductivity of the purest sample had a maximum of 840 W/mK at 9.8K. The intrinsic thermal resistivity varied as T 2 . 4 from 10K to 35K. At low temperatures electrons were scattered primarily by impurities and by phonons with both interband and intraband transitions observed. The electrical and thermal resistivity is departed from Matthiessen's rule at low temperatures

  20. Raman spectra of ruthenium and tantalum trimers in argon matrices

    Science.gov (United States)

    Fang, Li; Shen, Xiaole; Chen, Xiaoyu; Lombardi, John R.

    2000-12-01

    The resonance Raman spectra of ruthenium trimers (Ru 3) in argon matrices have been obtained. Three resonance Raman transitions were observed between 570 and 590 nm. Two of them (303.4 and 603.7 cm -1) are assigned to the totally symmetric vibrational progression, giving k e=1.86 mdyne/ Å. The line at 581.5 cm-1 is assigned as the origin of a low-lying electronic state. We also report on the observation of a resonance Raman spectrum of tantalum trimers (Ta 3). Observed lines include 251.2 and 501.9 cm-1 which we assign to the fundamental and the first overtone of the symmetric stretch in Ta 3. This gives k e=2.25 mdyne/ Å.

  1. Diffusion coefficient of hydrogen in niobium and tantalum

    International Nuclear Information System (INIS)

    Vargas, P.; Miranda, L.; Lagos, M.

    1988-08-01

    We show that the current data on hydrogen diffusion in Tantalum between 15K and 550K and in Niobium between 135K and 400K can be quantitatively explained by the small polaron theory. The experimental data can be understood assuming ground-state to ground-state tunneling between interstitial sites with tetrahedral symmetry plus an activated contribution due to tunneling between excited states having octahedral symmetry. The break of the diffusivity curve at T approx. = 250K follows naturally. It evidences the transition between the tetrahedral and octahedral hopping. For Ta the second break of the diffusivity curve at T approx. = 20K indicated the recovering of the ground-state hopping with tetrahedral symmetry. Below T approx. = 10K for Ta and T approx. = 7K for Nb the diffusion coefficient becomes independent of T. (author). 17 refs, 3 figs, 1 tab

  2. KAJIAN SIFAT OPTIK FILM TIPIS BST DIDADAH NIOBIUM DAN TANTALUM

    Directory of Open Access Journals (Sweden)

    Farida Huriawati

    2016-11-01

    Full Text Available In this research thin films of Barium Strontium Titanate (BST has been synthesis with different compositions Ba0,5Sr0,5TiO3 and Ba0,25Sr0,75TiO3 which doped by Nb2O5 (Niobium and Ta2O5 (Tantalum on Si (100 type-p substrate. Thin films were produced by chemical solution deposition technique (CSD and spin coating technique with annealing temperature at 850oC, 900oC dan 950oC. Rotation velocity at 3000 rpm and time of rotation is 30 seconds. Characterization of Films is optic Characterization (absorbance ana reflectance. From the Characterizations were obtained BNST thin film with 5% doping and anneling temperature at 8500C as photodiode light sensor which applied in electronic circuit.

  3. Dielectric properties of tantalum powder with broccoli-like morphology

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Masahiko [Department of Energy Science and Technology, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501 (Japan); Suzuki, Ryosuke O [Department of Energy Science and Technology, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501 (Japan)

    2005-04-19

    Metallic tantalum powder with broccoli-like morphology, consisting of spherical fine particles and of long rods or thin plates, was prepared in a hundred gram scale by calcium reduction of Ta{sub 2}O{sub 5} in molten CaCl{sub 2}. The properties as electrolytic capacitor were evaluated in comparison with commercial powder obtained by Na reduction and with powder consisting of only fine particles obtained by Ca reduction. The capacitance was larger than that of conventional powder with the same surface area, because the broccoli-like powder showed a strong resistance against shrinkage during high temperature annealing due to the framework of branches. The powder with new broccoli-like morphology can circumvent the conventional treatments for grain size control and gas removal.

  4. Dielectric properties of tantalum powder with broccoli-like morphology

    International Nuclear Information System (INIS)

    Baba, Masahiko; Suzuki, Ryosuke O.

    2005-01-01

    Metallic tantalum powder with broccoli-like morphology, consisting of spherical fine particles and of long rods or thin plates, was prepared in a hundred gram scale by calcium reduction of Ta 2 O 5 in molten CaCl 2 . The properties as electrolytic capacitor were evaluated in comparison with commercial powder obtained by Na reduction and with powder consisting of only fine particles obtained by Ca reduction. The capacitance was larger than that of conventional powder with the same surface area, because the broccoli-like powder showed a strong resistance against shrinkage during high temperature annealing due to the framework of branches. The powder with new broccoli-like morphology can circumvent the conventional treatments for grain size control and gas removal

  5. Split-Hopkinson pressure bar tests on pure tantalum

    International Nuclear Information System (INIS)

    Dick, Richard D.; Armstrong, Ronald W.; Williams, John D.

    1998-01-01

    Pure tantalum (Ta) was loaded in compression by a split-Hopkinson pressure bar (SHPB) to strain rates from 450 to 6350 s -1 . The results are compared with SHPB data for commercial Ta and with predictions from the constitutive model for Ta developed by Zerilli and Armstrong (Z-A). The main conclusions are: (1) the flow stress versus log strain rate agree with the Z-A constitutive model and other reported data, (2) uniform strain exponents computed on a true stress-strain basis for pure Ta are somewhat greater than those determined from SHPB data for commercial Ta, and (3) in both cases the uniform strain exponents versus log strain rate are in good agreement with predictions from the Z-A constitutive model for strain rates above 1500 s -1 without a clear indication of dislocation generation

  6. Cast and hipped gamma titanium aluminum alloys modified by chromium, boron, and tantalum

    International Nuclear Information System (INIS)

    Huang, Shyhchin.

    1993-01-01

    A cast body is described of a chromium, boron, and tantalum modified titanium aluminum alloy, said alloy consisting essentially of titanium, aluminum, chromium, boron, and tantalum in the following approximate atomic ratio: Ti-Al 45-50 Cr 1-3 Ta 1-8 B 0.1-0.3 , and said alloy having been prepared by casting the alloy to form said cast body and by HIPping said body

  7. Sputter deposition of tantalum-nitride films on copper using an rf-plasma

    International Nuclear Information System (INIS)

    Walter, K.C.; Fetherston, R.P.; Sridharan, K.; Chen, A.; Shamim, M.M.; Conrad, J.R.

    1994-01-01

    A tantalum-nitride film was successfully deposited at ambient temperature on copper with a modified ion-assisted-deposition (IAD) technique. The process uses an argon and nitrogen plasma to sputter deposit from a tantalum rf-cathode and ion implant the deposited film simultaneously. Both argon and nitrogen ions are used for sputtering and ion implantation. Auger spectroscopy and x-ray diffraction were used to characterize the resulting film

  8. Potentiometric determination of the tungsten content of tantalum-tungsten alloys with chromium II

    International Nuclear Information System (INIS)

    Gavra, Z.; Ronen, S.; Levin, R.

    1977-05-01

    A method was developed for the potentiometric determination of the tungsten content of tantalum-tungsten alloys of different compositions. These were dissolved under conditions that enabled the tungsten content to be determined with chromium (II). Phosphoric acid was selected as a suitable complexing agent for the prevention of the precipitation of tungsten and tantalum compounds. The use of chromium (II) required an oxygen-tight system and therefore the work was carried out in suitable vessels for storage and tritation

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

    OpenAIRE

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

    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 co...

  10. Electron tunneling in tantalum surface layers on niobium

    International Nuclear Information System (INIS)

    Ruggiero, S.T.; Track, E.K.; Prober, D.E.; Arnold, G.B.; DeWeert, M.J.

    1986-01-01

    We have performed electron tunneling measurements on tantalum surface layers on niobium. The tunnel junctions comprise 2000-A-circle Nb base electrodes with 10--100-A-circle in situ--deposited Ta overlayers, an oxide barrier, and Ag, Pb, or Pb-Bi alloy counterelectrodes. The base electrodes were prepared by ion-beam sputter deposition. The characteristics of these junctions have been studied as a function of Ta-layer thickness. These include the critical current, bound-state energy, phonon structure, and oxide barrier shape. We have compared our results for the product I/sub c/R versus tantalum-layer thickness with an extended version of the Gallagher theory which accounts for both the finite mean free path in the Ta overlayers and suppression of the I/sub c/R product due to strong-coupling effects. Excellent fits to the data yield a value of the intrinsic scattering probability for electrons at the Ta/Nb interface of r 2 = 0.01. This is consistent with the value expected from simple scattering off the potential step created by the difference between the Fermi energies of Ta and Nb. We have found a universal empirical correlation in average barrier height phi-bar and width s in the form phi-bar = 6 eV/(s-10 A-circle) for measured junctions which holds both for our data and results for available data in the literature for oxide-barrier junctions. The latter are composed of a wide variety of base and counterelectrode materials. These results are discussed in the general context of oxide growth and compared with results for artificial tunnel barriers

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Ding Ding

    2018-04-01

    Full Text Available 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.

  13. Effect of sputtering parameters and substrate composition on the structure of tantalum thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hallmann, Lubica, E-mail: lubica.hallmann@zzm.uzh.c [Clinic of Fixed and Removable Prosthodontics and Dental Material Science, Center of Dental Medicine, University of Zürich (Switzerland); Ulmer, Peter [Institute of Geochemistry and Petrology, ETH Zürich (Switzerland)

    2013-10-01

    The crystallographic properties of tantalum films deposited as a bioactive coating on Co–Cr–Mo and Ti–Al–Nb alloys have been investigated. The desired tough and ductile alpha phase of tantalum has been obtained by DC magnetron sputtering on Co–Cr–Mo and Ti–Al–Nb substrates. The thickness of the tantalum layer was between 20 and 600 nm. The crystallographic structure of tantalum thin film was dependent on the sputtering parameters such as DC power, bias voltage and gas impurities. Oxygen is an important factor for the stabilization of the tantalum alpha phase on Co–Cr–Mo substrate. The crystallographic structure and texture of tantalum thin films was found to be additionally dependent on the substrate composition. For Ti–Al–Nb substrate, oxygen content was not an important factor for the stabilization of the alpha phase. The observed shift of X-ray diffraction peaks to lower 2(θ) is an indication of stress evolving during the sputtering process and was dependent on bias voltage and oxygen content of the carrier gas.

  14. The evaluation of hydroxyapatite (HA) coated and uncoated porous tantalum for biomedical material applications

    International Nuclear Information System (INIS)

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

    2014-01-01

    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.

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

    Science.gov (United States)

    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.

  16. C-188 cobalt-60 sealed source integrity: source monitoring

    International Nuclear Information System (INIS)

    Defalco, G.M.; Shah, V.

    1995-01-01

    The integrity of C-188 cobalt-60 sealed sources used for radiation processing will be a key factor in the continued industrial acceptance and growth of gamma irradiation technology. Given the public's relatively poor understanding of most nuclear topics and the news media's tendency to sensationalize events, it is appropriate for suppliers and users of gamma technology to be vigilant and conservative regarding the application of cobalt-60 sources to industrial purposes. Nordion's recent decision to extend the optional warranty on its C-188 cobalt-60 sealed source from 15 years to 20 years is based on over 30 years of data generated from its on-going SOURCE SURVEILLANCE PROGRAM. This paper presents an overview of the C-188 SOURCE SURVEILLANCE PROGRAM. (author)

  17. Study of radiation synovectomy using 188Re-sulfide

    International Nuclear Information System (INIS)

    Chen Gang; Li Peiyong; Jiang Xufeng; Zhang Liying; Wang Xuefeng; Sun Zhenming; Zhang Huan

    2002-01-01

    Objective: To study the radiation synovectomy with 188 Re-sulfide. Methods: Thirty cases were divided into 2 groups, the group with hemophilia and the group with rheumatoid arthritis (RA). Patients with joint synovitis were injected different doses of 188 Re-sulfide, 222 - 444 MBq intra-articular. MRI was taken before and 3 - 6 months after the radiation synovectomy to evaluate the treatment efficacy, and the symptoms were also evaluated. Results: MRI study showed that after the treatment the synovium became thiner and the edema was reduced in the lesioned joint. The symptoms were improved with the pain relieved and duration of intra-articular hemorrhage reduced. Conclusions: Radiation synovectomy using 188 Re-sulfide has effects on synovitis. It can be used clinically to improve the symptoms of joint synovitis and reduce the duration of intra-articular hemorrhage

  18. Probing intruder configurations in $^{186, 188}$Pb using Coulomb excitation

    CERN Multimedia

    Columb excitation measurements to study the shape coexistence, mixing and quadrupole collectivity of the low-lying levels in neutron-deficient $^{188}$Pb nuclei are proposed with a view to extending similar studies to the $^{186}$Pb midshell nucleus. The HIE-ISOLDE beam of $^{186,188}$Pb nuclei will be delivered to MINIBALL+SPEDE set-up for simultaneous in-beam $\\gamma$-ray and conversion electron spectroscopy. The proposed experiment will allow the sign of the quadrupole deformation parameter to be extracted for the two lowest 2$^{+}$ states in $^{188}$Pb. Moreover, the advent of SPEDE will allow probing of the bandhead 0$^{+}$ states via direct measurements of E0 transitions. Beam development is requested to provide pure and instense $^{186}$Pb beam.

  19. The Synthesis And Characterization Of Wolfram Phthalocyanine For The Target Material Of High Specific Activity Radioisotope Wolfram - 188 (188W)

    International Nuclear Information System (INIS)

    Setiawan, Duyeh

    2000-01-01

    The application of 188 Re radioisotope separation on aluminia column through elution solution has increased significantly since the last two decades. The 188 Re radioisotope has been done fram 188 Re beta-decay through a neutron capture radiation on wolfram -186 target. In trhe column separation, high specific activity of 188 W radioisotope is required to get sufficient activity in small quality 188 W radioisotope has been carried out in this research. Wolfram-phthalocyanine compound was prepared by refluxing a mixture of wolfram trioxyde, (WO 3 ) and phthalonitrile, (C 8 H 4 N 2 ) at 250 o C for two hours. The synthesis of wolfram phthalocyanine is 70% purity yield, the product are green crystals, have a 193,0-193,8 o C melting points, and has a molecular formula C 3 2H 1 6 N8 WO 2 . The infra red spectrum of wolfram-phthalocyanine was the absorption band at 964,3 cm - 1 was due to the vibration of W=O bond of the wolfram dioxy-phthalocyanine. The x-ray diffraction of the wolfram dioxy-phthalocyanine was similar with molybdenum dioxy-phthalocyanine compound. This fact showed that the product was wolfram dioxy-phthalocyanine

  20. Labeling of MDP with 188Re for bone tumour therapy

    International Nuclear Information System (INIS)

    Barbezan, Angelica B.; Osso Junior, Joao A.

    2011-01-01

    188 Re is one of the most attractive radioisotopes for a variety of therapeutic applications in nuclear medicine, due to its physical decay properties, such as β - emission of 2.12 MeV, γ emission of 155 keV and half life of 16.9 hours. Biphosphonates are potent inhibitors of osteoclastic bone resorption and are effective in several diseases that cause bone fragility and bone metastases. Because of these characteristics, labeled biphosphonates have been studied for bone pathologies, also acting as palliation of bone pain in case of metastasis.The aim of this study was to optimize the labeling of a phosphonate-MDP (Sodium Methylene Diphosphonate) with 188 Re for use in bone pain palliation. 188 Re was obtained by eluting a 188 W- 188 Re generator from POLATOM. The labeling was performed at room temperature using MDP, SnCl 2 as reducing agent and ascorbic acid. The variables studied were: Mass of ligand (3, 6 and 10 mg), reducing agent mass (5, 7, 10 and 11 mg), ascorbic acid mass (1, 3, 5 and 6 mg), pH (1 and 2) and time of reaction (15, 60, 120, 360 and 4320 minutes), that also reflected the stability of the radiopharmaceutical. The radiochemical control, that also measures the labeling efficiency was evaluated by paper chromatography using Whatman 3MM paper and the solvents acetone and 0.9%NaCl. The best formulation was the following: Mass of ligand MDP: 10 mg, mass of SnCl 2 : 5 mg, ascorbic acid mass: 3 mg, time of reaction: 30 minutes, pH: 1. Under optimum conditions, 188 Re MDP radiolabeling yield was 98,07% and the radiopharmaceutical was stable up to 72 h. (author)

  1. Treatment of liver cancer with Rhenium-188 Lipiodol: Colombian experience

    International Nuclear Information System (INIS)

    Bernal, P.; Osorio, M.; Mendoza, M.; Esguerra, R.; Ucros, G.; Gutierrez, C.; Velez, O.; Cerquera, A.M.; Padhy, A.K.

    2002-01-01

    Aim:Trans-arterial Radio-conjugate therapy plays an important role in the palliative treatment of inoperable liver cancer. It also helps in reduction of the tumor to an operable state from an inoperable one. As a part of an IAEA sponsored coordinated research project, a new radiopharmaceutical, Rhenium-188 Lipiodol has been developed. The aim of this study was to establish the safety of the radiopharmaceutical and to find out the efficacy of treatment. Materials and Methods: Eight patients suffering from various forms of liver cancer (Hepatocellular carcinoma-4, Metastases from carcinoma of colon-3 and Carcinoid- 1) were treated with Rhenium -188 Lipiodol. Seven out of the eight patients were classified as ECOG- 1 and one as ECOG- 3. Labelling of Rhenium-188 with Lipiodol was carried out according to a protocol developed under the CRP and standardized in our service. Rhenium-188 Lipiodol was administered through the trans-arterial route by either selective (75%) or ultra selective (25%) hepatic arteriography. Administered therapeutic doses ranged between 170 MBq and 4181 MBq. Dosimetric evaluations were made using the IAEA developed dosimetry spreadsheet. All patients were followed up (1-5 months, average = 2 months) after treatment by clinical examination, liver function tests, haematological examinations and CT scans of liver to determine the size of hepatic tumor. Results: Rhenium-188 Lipiodol treatment was well tolerated by all patients. No immediate systemic complications were noted in any of the patients within 72 hrs. following therapy. Only two patients had mild rise in temperature in the immediate post-therapy period, which subsided subsequently. One patient who was classified as Child B and ECOG 3, developed encephalopathy on the seventh day after treatment. He died of hepatic failure. Another one present depressive syndrome, didn't accept food and died Follow-up CT scans in all the surviving (6/8) patients revealed significant reduction of the tumours

  2. A study for an electrolytic reduction of tantalum oxide in a LiCl-Li2O molten salt

    International Nuclear Information System (INIS)

    Park, Sung Bin; Park, Byung Heung; Seo, Chung Seok; Kang, Dae Seung; Kwon, Seon Gil; Park, Seong Won

    2005-01-01

    Korea Atomic Energy Research Institute (KAERI) has developed the Advanced Spent Fuel Conditioning Process (ACP) to be an innovative technology for handling the PWR spent fuel. As part of ACP, the electrolytic reduction process (ER process) is the electrochemical reduction process of uranium oxide to uranium metal in a molten salt. The ER process has advantages in a technical stability, an economic potential and a good proliferation resistance. KAERI has reported on the good experimental results of an electrochemical reduction of the uranium oxide in a 20 kg HM/batch lab-scale. The ER process can be applicable to the reduction of other metal oxides. Metal tantalum powder has attracted attention for a variety of applications. A tantalum capacitor made from superfine and pliable tantalum powders is very small in size and it has a higher-capacitance part, therefore it is useful for microelectronic devices. By the ER process the metal tantalum can be obtained from tantalum pentoxide. In this work, a 40 g Ta 2 O 5 /batch electrochemical reactor was used for the synthesis of the metal tantalum. From the results of the cyclic voltammograms for the Ta 2 O 5 -LiCl-Li 2 O system, the mechanism of the tantalum reduction in a molten LiCl-Li 2 O salt system was investigated. Tantalum pentoxide is chemically reduced to tantalum metal by the lithium metal which is electrochemically deposited into an integrated cathode assembly in the LiCl-Li 2 O molten salt. The experiments for the tantalum reduction were performed with a chronopotentiometry in the reactor cell, the reduced products were analyzed from an analysis of the X-ray diffraction (XRD), scanning electron microscope and energy dispersive X-ray (SEM-EDX). From the results, the electrolytic reduction process is applicable to the synthesis of metal tantalum

  3. Lifetime measurements in shape transition nucleus 188Pt

    Science.gov (United States)

    Rohilla, Aman; Gupta, C. K.; Singh, R. P.; Muralithar, S.; Chakraborty, S.; Sharma, H. P.; Kumar, A.; Govil, I. M.; Biswas, D. C.; Chamoli, S. K.

    2017-04-01

    Nuclear level lifetimes of high spin states in yrast and non-yrast bands of 188Pt nucleus have been measured using recoil distance plunger setup present at IUAC, Delhi. In the experiment nuclear states of interest were populated via 174Yb(18O,4 n)188Pt reaction at a beam energy of 79MeV provided by 15 UD Pelletron accelerator. The extracted B(E2\\downarrow) values show an initial rise up to 4+ state and then a nearly constant behavior with spin along yrast band, indicating change of nuclear structure in 188Pt at low spins. The good agreement between experimental and TPSM model B(E2\\downarrow) values up to 4^+ state suggests an increase in axial deformation of the nucleus. The average absolute β2 = 0.20 (3) obtained from measured B(E2\\downarrow) values matches well the values predicted by CHFB and IBM calculations for oblate ( β2 ˜ -0.19) and prolate (β2 ˜ 0.22) shapes. As the lifetime measurements do not yield the sign of β2, no definite conclusion can be drawn on the prolate or oblate collectivity of 188Pt on the basis of present measurements.

  4. 17 CFR 256.188 - Research, development, or demonstration expenditures.

    Science.gov (United States)

    2010-04-01

    ... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Research, development, or... COMPANIES, PUBLIC UTILITY HOLDING COMPANY ACT OF 1935 4. Deferred Debits § 256.188 Research, development, or... of all expenditures for research, development or demonstration undertaken by or sponsored through the...

  5. Lifetime measurements in shape transition nucleus {sup 188}Pt

    Energy Technology Data Exchange (ETDEWEB)

    Rohilla, Aman; Gupta, C.K.; Chamoli, S.K. [University of Delhi, Department of Physics and Astrophysics, New Delhi (India); Singh, R.P.; Muralithar, S. [Inter University Accelerator Centre, New Delhi (India); Chakraborty, S.; Sharma, H.P. [Banaras Hindu University, Department of Physics, Varanasi (India); Kumar, A.; Govil, I.M. [Panjab University, Department of Physics, Chandigarh (India); Biswas, D.C. [Bhabha Atomic Research Center, Nuclear Physics Division, Trombay, Mumbai (India)

    2017-04-15

    Nuclear level lifetimes of high spin states in yrast and non-yrast bands of {sup 188}Pt nucleus have been measured using recoil distance plunger setup present at IUAC, Delhi. In the experiment nuclear states of interest were populated via {sup 174}Yb({sup 18}O,4n){sup 188}Pt reaction at a beam energy of 79MeV provided by 15 UD Pelletron accelerator. The extracted B(E2 ↓) values show an initial rise up to 4{sup +} state and then a nearly constant behavior with spin along yrast band, indicating change of nuclear structure in {sup 188}Pt at low spins. The good agreement between experimental and TPSM model B(E2 ↓) values up to 4{sup +} state suggests an increase in axial deformation of the nucleus. The average absolute β{sub 2} = 0.20 (3) obtained from measured B(E2 ↓) values matches well the values predicted by CHFB and IBM calculations for oblate (β{sub 2} ∝ -0.19) and prolate (β{sub 2} ∝ 0.22) shapes. As the lifetime measurements do not yield the sign of β{sub 2}, no definite conclusion can be drawn on the prolate or oblate collectivity of {sup 188}Pt on the basis of present measurements. (orig.)

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  8. Use of sulfoxides for extraction-gravimetric determination of niobium and tantalum

    International Nuclear Information System (INIS)

    Nikolaev, A.I.; Babkin, A.G.; Tkachenko, V.G.

    1977-01-01

    An extraction-gravimetrical technique has been developed for determination of niobium and tantalum. The technique permits simultaneous extraction of tantalum and its concentrating in the aqueous phase; the range of Ta concentrations determined is essentially wider than in case of the routine gravimetric methods. The technique is based upon the fact, that tantalum is extracted by sulfoxides from fluorine-sulphate solutions at lower concentration of Hf and at lower ratios between the volumes of organic and aqueous phases than niobium. Two subsequent extractions by 1M sulfoxide solutions provide for practically complete transfer of tantalum into the organic phase, whereas extraction of niobium is only 3-20%. Sufficient recovery of Ta and Nb from organic phases is provided by re-extraction by NH 4 F solution. The technique is suitable for niobium and tantalum determination at the ratios of their pentoxides from 1:100 to 100:1. The disturbing influence of Fe(3) is suppressed by reductions to Fe(2)

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

    Science.gov (United States)

    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.

  10. Cracking in dissimilar laser welding of tantalum to molybdenum

    Science.gov (United States)

    Zhou, Xingwen; Huang, Yongde; Hao, Kun; Chen, Yuhua

    2018-06-01

    Dissimilar joining of tantalum (Ta) to molybdenum (Mo) is of great interest in high temperature structural component applications. However, few reports were found about joining of these two hard-to-weld metals. The objective of this experimental study was to assess the weldability of laser butt joining of 0.2 mm-thick Ta and Mo. In order to study cracking mechanism in Ta/Mo joint, similar Ta/Ta and Mo/Mo joints were compared under the same welding conditions. An optical microscope observation revealed presence of intergranular cracks in the Mo/Mo joint, while both transgranular and intergranular cracks were observed in Ta/Mo joint. The cracking mechanism of the Ta/Mo joint was investigated further by micro-hardness testing, micro X-ray diffraction and scanning electron microscopy. The results showed that solidification cracking tendency of Mo is a main reason for crack initiation in the Ta/Mo joint. Low ductility feature in fusion zone most certainly played a role in the transgranular propagation of cracking.

  11. Laser-induced breakdown spectroscopy of tantalum plasma

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Sidra; Bashir, Shazia; Hayat, Asma; Khaleeq-ur-Rahman, M.; Faizan–ul-Haq [Centre for Advanced Studies in Physics, GC University, Lahore (Pakistan)

    2013-07-15

    Laser Induced Breakdown spectroscopy (LIBS) of Tantalum (Ta) plasma has been investigated. For this purpose Q-switched Nd: YAG laser pulses (λ∼ 1064 nm, τ∼ 10 ns) of maximum pulse energy of 100 mJ have been employed as an ablation source. Ta targets were exposed under the ambient environment of various gases of Ar, mixture (CO{sub 2}: N{sub 2}: He), O{sub 2}, N{sub 2}, and He under various filling pressure. The emission spectrum of Ta is observed by using LIBS spectrometer. The emission intensity, excitation temperature, and electron number density of Ta plasma have been evaluated as a function of pressure for various gases. Our experimental results reveal that the optical emission intensity, the electron temperature and density are strongly dependent upon the nature and pressure of ambient environment. The SEM analysis of the ablated Ta target has also been carried out to explore the effect of ambient environment on the laser induced grown structures. The growth of grain like structures in case of molecular gases and cone-formation in case of inert gases is observed. The evaluated plasma parameters by LIBS analysis such as electron temperature and the electron density are well correlated with the surface modification of laser irradiated Ta revealed by SEM analysis.

  12. Hydrocode analysis of lateral stress gauges in shocked tantalum

    International Nuclear Information System (INIS)

    Harris, E. J.; Winter, R. E.

    2007-01-01

    Experiments published by other workers, on the resistance change of manganin stress gauges embedded in a lateral orientation in tantalum targets shocked to a range of stresses, have been analysed using an adaptive mesh refinement hydrocode. It was found that for all of the four experiments the shape of the time profile of the computed lateral stress in the mounting layer closely matched the shape of the experimental lateral stress profiles. However, the calculated lateral stresses at the gauge location in the mounting layer are significantly less than the lateral stresses that would have been produced in the target if no gauge had been present. The perturbation caused by the gauge increased as the strength of the applied shock increased. When the perturbations are taken into account values of flow stress that are significantly smaller than those reported in the original research paper are derived. The work shows that the lateral gauge technique can give valuable information on strength provided high resolution simulation is used to compensate for the perturbations caused by the gauges

  13. Laser-induced breakdown spectroscopy of tantalum plasma

    International Nuclear Information System (INIS)

    Khan, Sidra; Bashir, Shazia; Hayat, Asma; Khaleeq-ur-Rahman, M.; Faizan–ul-Haq

    2013-01-01

    Laser Induced Breakdown spectroscopy (LIBS) of Tantalum (Ta) plasma has been investigated. For this purpose Q-switched Nd: YAG laser pulses (λ∼ 1064 nm, τ∼ 10 ns) of maximum pulse energy of 100 mJ have been employed as an ablation source. Ta targets were exposed under the ambient environment of various gases of Ar, mixture (CO 2 : N 2 : He), O 2 , N 2 , and He under various filling pressure. The emission spectrum of Ta is observed by using LIBS spectrometer. The emission intensity, excitation temperature, and electron number density of Ta plasma have been evaluated as a function of pressure for various gases. Our experimental results reveal that the optical emission intensity, the electron temperature and density are strongly dependent upon the nature and pressure of ambient environment. The SEM analysis of the ablated Ta target has also been carried out to explore the effect of ambient environment on the laser induced grown structures. The growth of grain like structures in case of molecular gases and cone-formation in case of inert gases is observed. The evaluated plasma parameters by LIBS analysis such as electron temperature and the electron density are well correlated with the surface modification of laser irradiated Ta revealed by SEM analysis

  14. Effect of structural transition on magnetic susceptibility of tantalum carbide

    International Nuclear Information System (INIS)

    Lipatnikov, V.N.; Gusev, A.I.; Rempel', A.A.; Shvejkin, G.P.

    1987-01-01

    Ordering of carbon atoms and vacancies in nonmetal sublattice of TaC y is investigated for the first time by methods of magnetic susceptibility and structural neutron diffraction analysis. Measurements of magnetic susceptibility were conducted on high-sensitive magnetic scales in temperature interval of 300 - 1300 K with holding at each temperature up to the establishment of constant, nonchanging in the course of time value of susceptibility x. When investigating x-hardened tantalum carbide within the interval of TaC 0.82 - TaC 0.85 compositions under the conditions of slow heating, it was observed nonrecorded earlier irreversible decrease of susceptibility at temperature of 960 - 1000 K. With further temperature increase T>T tr it was observed at first even and than uneven increase of x value at a temperature of T tr equal to 1090, 1130 and 1150 K for TaC 0.82 , TaC 0.83 and TaC 0.85 respectively. The measuring of magnetic susceptibility of the same samples at temperature decrease reveals the presence of susceptibility temperature hysteresis in the interval of 1070 - 1090, 1100 - 1130 and 1120 - 1150 for TaC 0.82 , TaC 0.83 and TaC 0.85 . Reversible susceptibility jump corresponding to the temperature hysteresis range at dependences of x(T), is connected with equilibrium structural phase transition of order-disorder

  15. Plasma arc melting of titanium-tantalum alloys

    International Nuclear Information System (INIS)

    Dunn, P.; Patterson, R.A.; Haun, R.

    1994-01-01

    Los Alamos has several applications for high temperature, oxidation and liquid-metal corrosion resistant materials. Further, materials property constraints are dictated by a requirement to maintain low density; e.g., less than the density of stainless steel. Liquid metal compatibility and density requirements have driven the research toward the Ti-Ta system with an upper bound of 60 wt% Ta-40 wt% Ti. Initial melting of these materials was performed in a small button arc melter with several hundred grams of material; however, ingot quantities were soon needed. But, refractory metal alloys whose constituents possess very dissimilar densities, melting temperatures and vapor pressures pose significant difficulty and require specialized melting practices. The Ti-Ta alloys fall into this category with the density of tantalum 16.5 g/cc and that of titanium 4.5 g/cc. Melting is further complicated by the high melting point of Ta(3020 C) and the relatively low boiling point of Ti(3287 C). Previous electron beam melting experience with these materials resulted, in extensive vaporization of the titanium and poor chemical homogeneity. Vacuum arc remelting(VAR) was considered as a melting candidate and discarded due to density and vapor pressure issues associated with electron beam. Plasma arc melting offered the ability to supply a cover gas to deal with vapor pressure issues as well as solidification control to help with macrosegregation in the melt and has successfully produced high quality ingots of the Ti-Ta alloys

  16. The dislocation-internal friction peak γ in tantalum

    International Nuclear Information System (INIS)

    Baur, J.; Benoit, W.; Schultz, H.

    1989-01-01

    Torsion-pendulum measurements were carried out on high-purity single crystal specimens of tantalum, having extremely low oxygen contents ( 2 peak, which appears close to γ is small traces of oxygen are presents. The γ 2 peak was formerly explained as a ''dislocation-enhanced Snoek peak''. The γ peak recovers at the peak temperature, whereas the γ 2 peak is more stable. On the basis of their results, and making use of earlier investigations of Rodrian and Schultz, the authors suggest that γ 2 is modified γ relaxation, related to screw-dislocation segments, stabilized by oxygen-decorated kinks. The stability of the γ 2 peak allows an accurate determination of the activation energy, found to be 1.00 +- 0.03 eV. This value is distinctly lower than the activation energy of the oxygen Snoek effect (1.10 eV) and is related here to the mechanism of ''kink-pair formation'' in screw dislocations, as the original γ peak. The numerical value is compatible with recent values derived from flow-stress measurements. The peak γ 2 shows increasing stability with increasing oxygen content. This is explained by single- and multi-decorated kinks

  17. Structures and photocatalytic behavior of tantalum-oxynitride thin films

    International Nuclear Information System (INIS)

    Hsieh, J.H.; Li, Chuan; Liang, H.C.

    2011-01-01

    Tantalum oxynitride films were created by direct nitridation/oxidation during rapid thermal annealing at temperatures 450-700 deg. C. Instead of during deposition, this post process may be proved to be an alternative way to make transition metallic oxynitride films. With sufficient supply of oxygen flow (≥ 30 sccm), TaO x N y was formed as examined from X-ray diffraction (XRD) analysis. This oxynitride film has a broad optical absorption over the range of visible light and sufficient photocatalytic function. For optical absorption, the films' transmittance and reflectance were measured by a UV-VIS-NIR spectrophotometer with wavelengths ranging from 300 to 900 nm. The broad visible light absorption is associated with the formation of band gap in TaO x N y film, which was examined by the theoretical calculations combining the Beer-Lambert law and Tauc formula. Lastly, the photocatalysis of TaO x N y was gauged by the photodegradation test which measured the reduction of light absorbance affected by the decomposition of methylene blue (C 16 H 18 N 3 SCl.3H 2 O) on TaO x N y under visible light irradiation.

  18. Multistate Memristive Tantalum Oxide Devices for Ternary Arithmetic

    Science.gov (United States)

    Kim, Wonjoo; Chattopadhyay, Anupam; Siemon, Anne; Linn, Eike; Waser, Rainer; Rana, Vikas

    2016-11-01

    Redox-based resistive switching random access memory (ReRAM) offers excellent properties to implement future non-volatile memory arrays. Recently, the capability of two-state ReRAMs to implement Boolean logic functionality gained wide interest. Here, we report on seven-states Tantalum Oxide Devices, which enable the realization of an intrinsic modular arithmetic using a ternary number system. Modular arithmetic, a fundamental system for operating on numbers within the limit of a modulus, is known to mathematicians since the days of Euclid and finds applications in diverse areas ranging from e-commerce to musical notations. We demonstrate that multistate devices not only reduce the storage area consumption drastically, but also enable novel in-memory operations, such as computing using high-radix number systems, which could not be implemented using two-state devices. The use of high radix number system reduces the computational complexity by reducing the number of needed digits. Thus the number of calculation operations in an addition and the number of logic devices can be reduced.

  19. Porous tantalum coatings prepared by vacuum plasma spraying enhance bmscs osteogenic differentiation and bone regeneration in vitro and in vivo.

    Directory of Open Access Journals (Sweden)

    Ze Tang

    Full Text Available Tantalum, as a potential metallic implant biomaterial, is attracting more and more attention because of its excellent anticorrosion and biocompatibility. However, its significantly high elastic modulus and large mechanical incompatibility with bone tissue make it unsuitable for load-bearing implants. In this study, porous tantalum coatings were first successfully fabricated on titanium substrates by vacuum plasma spraying (VPS, which would exert the excellent biocompatibility of tantalum and alleviate the elastic modulus of tantalum for bone tissue. We evaluated cytocompatibility and osteogenesis activity of the porous tantalum coatings using human bone marrow stromal cells (hBMSCs and its ability to repair rabbit femur bone defects. The morphology and actin cytoskeletons of hBMSCs were observed via electron microscopy and confocal, and the cell viability, proliferation and osteogenic differentiation potential of hBMSCs were examined quantitatively by PrestoBlue assay, Ki67 immunofluorescence assay, real-time PCR technology and ALP staining. For in vivo detection, the repaired femur were evaluated by histomorphology and double fluorescence labeling 3 months postoperation. Porous tantalum coating surfaces promoted hBMSCs adhesion, proliferation, osteogenesis activity and had better osseointegration and faster new bone formation rate than titanium coating control. Our observation suggested that the porous tantalum coatings had good biocompatibility and could enhance osseoinductivity in vitro and promote new bone formation in vivo. The porous tantalum coatings prepared by VPS is a promising strategy for bone regeneration.

  20. Superconducting properties and uniaxial strain characteristics of Nb3Sn fiber-reinforced superconductors with tantalum reinforcement fibers

    International Nuclear Information System (INIS)

    Arai, Kazuaki; Umeda, Masaichi; Agatsuma, Koh; Tateishi, Hiroshi

    1998-01-01

    We have been developing fiber-reinforced superconductors (FRS) for high-field and large-scale magnets. Tungsten fibers have been selected as the reinforcement fiber for FRS so far because tungsten has the highest elastic modulus of approximately 400 GPa which can minimize the strain from electromagnetic force. The preparation process of FRS consists of sputtering deposition and heat treatment because it may be difficult to apply drawing methods to materials of high-elastic modulus such as tungsten. Tantalum has high elastic modulus of 178 GPa and its thermal expansion coefficient that is closer to that of Nb 3 Sn than tungsten's, which means prestrain in Nb 3 Sn in FRS is reduced by adopting tantalum fibers. Tantalum has been used as barriers between bronze and copper in conventional Nb 3 Sn superconductors which are usually prepared with drawing process despite of the tantalum's high elastic modulus. That implies drawing process may be applied to prepare FRS with tantalum reinforcement fibers. In this paper, FRS using tantalum fibers prepared with sputtering process are described with making comparison with FRS of tungsten to clarify the basic properties of FRS using tantalum fibers. Depth profiles in Nb 3 Sn layer in FRS were measured to examine reaction between superconducting layers and reinforcement fibers. Superconducting properties including strain and stress characteristics were shown. Those data will contribute to design of FRS using tantalum reinforcement fibers with adopts the drawing processes. (author)

  1. The recovery of tin, and the production of niobium pentoxide and potassium tantalum fluoride, from a tin slag

    International Nuclear Information System (INIS)

    Iorio, G.; Tyler, M.S.

    1987-01-01

    This report describes the results of testwork on the recovery of tin, niobium, and tantalum from a tin slag. The slag, which consisted mainly of amorphous silica, with varying amounts of calcuim, magnesium, manganese, iron, and aluminium, contained an average of 8,8 per cent niobium pentoxide and 6,2 per cent tantalum pentoxide. The metallic tin-ion phase was removed from the crushed slag by magnetic separation. The slag was then leached with hydrochloric acid to remove magnesium, calcium, aluminium, iron, manganese, and the remainder of the tin. Leaching with sodium hydroxide for the removal of silica and phosphorous was followed by a final leach with hydrochloric acid for the removal of sodium. The upgraded concentrate thus obtained was purified by leaching with hydrofluoric acid, solvent extraction of niobium and tantalum into tri-n-butyl phosphate and methyl isobutyl ketone, and selective stripping of niobium with sulphuric acid and tantalum with ammonium floride. Niobium pentoxide and potassium tantalum fluoride were then precipitated by the addition of ammonium hydroxide and potassium fluoride to the respective strip liquors. The overall recoveries in the upgraded concentrate were 98 per cent for tantalum and 92 per cent for niobium. Dissolutions and recoveries of over 99 per cent were obtained for both tantalum and niobium in the purification steps. The niobium pentoxide and potassium tantalum fluoride precipitates obtained were of high purity

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

    Science.gov (United States)

    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.

  3. Tantalum(V) impurity extraction by octanol from niobium(V) fluoride solutions

    International Nuclear Information System (INIS)

    Majorov, V.G.; Nikolaev, A.I.; Kopkov, V.K.

    2002-01-01

    The conditions of the niobium and tantalum extraction separation by octanol in the fluoride solutions, depending on the metals and free hydrofluoric acid concentration as well as on the organic and water phases voluminous relation, are studied for the purpose of developing the technology of niobium deep purification from the tantalum impurities. The technological scheme of the niobium solutions(V) extraction purification from the tantalum impurities(V), which provides for obtaining the niobium oxide(V), containing less than 0.005 mass % Ta 2 O 5 , is proposed on the basis of the established optimal separation conditions. The possibility of using the developed technology by the pyrochlore reprocessing is indicated [ru

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

    Science.gov (United States)

    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.

  5. Tantalum and niobium carbides obtention by carbothermic reduction of columbotantalite ores

    International Nuclear Information System (INIS)

    Gordo, E.; Garcia-Carcedo, F.; Torralba, J.M.

    1998-01-01

    Tantalum and niobium carbides are characterized by its high hardness and chemical corrosion resistance. Both carbides, but mainly TaC, are used in hard metals (sintered carbides), together with their carbides, to manufacture cutting tools and dies in special machining applications involving mechanical shock at high temperature. Its use as reinforcement of wear resistant materials through powder metallurgy techniques are being investigated. However, the use of TaC is usually limited because of its high cost. Therefore tantalum carbide with niobium content, which is cheaper, is used. In this work the obtention of complex tantalum and niobium carbides from a Spanish columbotantalite ore is studied through relatively cheap and simple process as it is carbothermic reduction. Concentration of the ore, its reduction and the characterization of products are described. (Author) 11 refs

  6. Assembly of tantalum porous films with graded oxidation profile from size-selected nanoparticles

    Science.gov (United States)

    Singh, Vidyadhar; Grammatikopoulos, Panagiotis; Cassidy, Cathal; Benelmekki, Maria; Bohra, Murtaza; Hawash, Zafer; Baughman, Kenneth W.; Sowwan, Mukhles

    2014-05-01

    Functionally graded materials offer a way to improve the physical and chemical properties of thin films and coatings for different applications in the nanotechnology and biomedical fields. In this work, design and assembly of nanoporous tantalum films with a graded oxidation profile perpendicular to the substrate surface are reported. These nanoporous films are composed of size-selected, amorphous tantalum nanoparticles, deposited using a gas-aggregated magnetron sputtering system, and oxidized after coalescence, as samples evolve from mono- to multi-layered structures. Molecular dynamics computer simulations shed light on atomistic mechanisms of nanoparticle coalescence, which govern the films porosity. Aberration-corrected (S) TEM, GIXRD, AFM, SEM, and XPS were employed to study the morphology, phase and oxidation profiles of the tantalum nanoparticles, and the resultant films.

  7. Recovery of metal values and hydrofluoric acid from tantalum and columbium waste sludge

    International Nuclear Information System (INIS)

    Bielecki, E.; Romberger, K.; Bakke, B.; Hobin, M.A.; Clark, C.

    1992-01-01

    A metallurgical processing system for economically recovering metal values, such as columbium, tantalum, thorium, and uranium from dilute source solids, such as digestion sludges, by a series of steps including: (1) slurrying the source solids with dilute hydrofluoric acid to produce a solid phase and a liquid phase containing dissolved tantalum and columbium, then extracting tantalum and/or columbium from the liquid phase by means of a liquid ion-exchange process and then, additionally; (2) roasting the solid phase with sulfuric acid to recover and recycle hydrofluoric acid, leaching the roasted solids with dilute sulfuric acid to produce a disposable solid phase and a liquid phase containing thorium and uranium, and extracting thorium and uranium from the liquid phase by means of a liquid-liquid amine extraction process

  8. Tantalum-based multilayer coating on cobalt alloys in total hip and knee replacement

    Energy Technology Data Exchange (ETDEWEB)

    Balagna, C., E-mail: cristina.balagna@polito.it [Institute of Materials Engineering and Physics, Applied Science and Technology Department, Politecnico di Torino, Corso Duca degli Abruzzi 24,10129 Torino (Italy); Faga, M.G. [Istituto di Scienza e Tecnologia dei Materiali Ceramici, Consiglio Nazionale delle Ricerche, Strada delle Cacce 73, 10135 Torino (Italy); Spriano, S. [Institute of Materials Engineering and Physics, Applied Science and Technology Department, Politecnico di Torino, Corso Duca degli Abruzzi 24,10129 Torino (Italy)

    2012-05-01

    Cobalt-chromium-molybdenum (CoCrMo) alloys are widely used in total hip and knee joint replacement, due to high mechanical properties and resistance to wear and corrosion. They are able to form efficient artificial joints by means of coupling metal-on-polymer or metal-on-metal contacts. However, a high concentration of stress and direct friction between surfaces leads to the formation of polyethylene wear debris and the release of toxic metal ions into the human body, limiting, as a consequence, the lifetime of implants. The aim of this research is a surface modification of CoCrMo alloys in order to improve their biocompatibility and to decrease the release of metal ions and polyethylene debris. Thermal treatment in molten salts was the process employed for the deposition of tantalum-enriched coating. Tantalum and its compounds are considered biocompatible materials with low ion release and high corrosion resistance. Three different CoCrMo alloys were processed as substrates. An adherent coating of about 1 {mu}m of thickness, with a multilayer structure consisting of two tantalum carbides and metallic tantalum was deposited. The substrates and modified layers were characterized by means of structural, chemical and morphological analysis. Moreover nanoindentation, scratch and tribological tests were carried out in order to evaluate the mechanical behavior of the substrates and coating. The hardness of the coated samples increases more than double than the untreated alloys meanwhile the presence of the coating reduced the wear volume and rate of about one order of magnitude. - Highlights: Black-Right-Pointing-Pointer Thermal treatment in molten salts deposits a Ta-based coating on Co-based alloys. Black-Right-Pointing-Pointer Coating is composed by one or two tantalum carbides and/or metallic tantalum. Black-Right-Pointing-Pointer The coating structure depends on thermal temperature and substrates carbon content. Black-Right-Pointing-Pointer Coating is able to

  9. Cation mobility in H+/Na+ ion exchange products of acid tantalum and zirconium phosphates

    International Nuclear Information System (INIS)

    Tarnopol'skij, V.A.; Yaroslavtsev, A.B.

    2000-01-01

    Ionic conductivity of Na + /H + exchange products on acid zirconium phosphate with different substitution degree and on acid tantalum phosphate, where ion exchange occurs via formation of a continuous series of solid solutions, was studied by the method of conductometry. It was ascertained that ionic conductivity decreases monotonously with growth in substitution degree of H + for Na + in acid tantalum phosphate. Anomalous increase in ionic conductivity of ion exchange products on acid zirconium phosphate with a low substitution degree has been detected for the first time. Formation of a double electric layer with a high concentration of cationic defects on the interface surface is the reason for increase in ionic conductivity [ru

  10. Partial molar volumes of hydrogen and deuterium in niobium, vanadium, and tantalum

    International Nuclear Information System (INIS)

    Peterson, D.T.; Herro, H.M.

    1983-01-01

    The partial molar volumes of hydrogen and deuterium were measured in vanadium, niobium, and tantalum by a differential pressure technique. One-half of an electrolytically charged sample plat was compressed between hardened steel blocks in a hydraulic press. The activity of hydrogen in the hig pressure region was raised and caused hydrogen to diffuse into the low pressure region. The partia molar volume was calculated from the ratio of the hydrogen concentrations in the high and low pressure regions of the sample. Small isotope effects were found in the partial molar volume. Hydrogen had the larger volume in niobium and tantalum, but the reverse was true in vanadium

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

    Science.gov (United States)

    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.

  12. Rapid synthesis of tantalum oxide dielectric films by microwave microwave-assisted atmospheric chemical vapor deposition

    International Nuclear Information System (INIS)

    Ndiege, Nicholas; Subramanian, Vaidyanathan; Shannon, Mark A.; Masel, Richard I.

    2008-01-01

    Microwave-assisted chemical vapor deposition has been used to generate high quality, high-k dielectric films on silicon at high deposition rates with film thicknesses varying from 50 nm to 110 μm using inexpensive equipment. Characterization of the post deposition products was performed by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Auger electron spectroscopy and Raman spectroscopy. Film growth was determined to occur via rapid formation and accumulation of tantalum oxide clusters from tantalum (v) ethoxide (Ta(OC 2 H 5 ) 5 ) vapor on the deposition surface

  13. Analytical fingerprint for tantalum ores from African deposits

    Science.gov (United States)

    Melcher, F.; Graupner, T.; Sitnikova, M.; Oberthür, T.; Henjes-Kunst, F.; Gäbler, E.; Rantitsch, G.

    2009-04-01

    Illegal mining of gold, diamonds, copper, cobalt and, in the last decade, "coltan" has fuelled ongoing armed conflicts and civil war in a number of African countries. Following the United Nations initiative to fingerprint the origin of conflict materials and to develop a traceability system, our working group is investigating "coltan" (i.e. columbite-tantalite) mineralization especially in Africa, also within the wider framework of establishing certified trading chains (CTC). Special attention is directed towards samples from the main Ta-Nb-Sn provinces in Africa: DR Congo, Rwanda, Mozambique, Ethiopia, Egypt and Namibia. The following factors are taken into consideration in a methodological approach capable of distinguishing the origin of tantalum ores and concentrates with the utmost probability: (1) Quality and composition of coltan concentrates vary considerably. (2) Mineralogical and chemical compositions of Ta-Nb ores are extremely complex due to the wide range of the columbite-tantalite solid solution series and its ability to incorporate many additional elements. (3) Coltan concentrates may contain a number of other tantalum-bearing minerals besides columbite-tantalite. In our approach, coltan concentrates are analyzed in a step-by-step mode. State-of-the-art analytical tools employed are automated scanning electron microscopy (Mineral Liberation Analysis; MLA), electron microprobe analysis (major and trace elements), laser ablation-ICP-MS (trace elements, isotopes), and TIMS (U-Pb dating). Mineral assemblages in the ore concentrates, major and trace element concentration patterns, and zoning characteristics in the different pegmatites from Africa distinctly differ from each other. Chondrite-normalized REE distribution patterns vary significantly between columbite, tantalite, and microlite, and also relative to major element compositions of columbites. Some locations are characterized by low REE concentrations, others are highly enriched. Samples with

  14. Poloamer 188 as an Adjunct in Prolonged Hypotensive Resucitation

    Science.gov (United States)

    2017-07-01

    exsanguinations remains a leading cause of deaths (approximately 40 %) in both civilian and military trauma. A subset of injured soldiers develop...maintain BP at 60mmHg (mg/kg/h) 81.28±8.29 Total Resus volume till death (ml/kg/h) 11.17±1.3 7 4.72±0.81 0.0005 Total P188 resus till death (mg/kg/h) 94.50

  15. Optimum deposition, structure, and properties of tantalum oxide films

    International Nuclear Information System (INIS)

    Lin, Y.C.

    1985-01-01

    Amorphous, ductile, and uniform Ta 2 O 5 films that acted as diffusion barriers were developed by sputter depositing Ta metal on Al single crystals (99.99%) and subsequently anodizing these thin films. The morphology, microstructure, composition and properties were characterized by scanning and transmission electron microscopy, surface and Fourier transform infrared spectroscopy, X-ray diffraction, and fluorescence. Superior corrosion resistance in a water saturated Cl 2 atmosphere was provided by Ta 2 O 5 coating on Al single crystal substrates but not on Al alloys. The strong Ta-O bond, the non-porous nature of the film and good adhesion to the substrate are attributed to the outstanding corrosion resistance of these oxide coatings. Al alloy surfaces are not protected, since the anodic film formed over grain boundaries, processing lines and emergent precipitates is poorly adherent, thus providing loci for corrosion. These problems were eliminated by casting a 400 A layer of tantalum oxyhydroxide polymer from ethanol solution onto Al substrate and curing to a Ta 2 O 5 layer that effectively resisted attack by wet Cl 2 . The mechanical properties of Ta 2 O 5 films on Al alloys were studied at various pH's by in-situ fatigue loading coupled with electrochemical measurements of corrosion potential and corrosion current. These results indicate the fatigue resistance of this oxide film effectively protects the underlying metal from strong HCl solution attack. The very unusual ductility and high corrosion resistance of Ta 2 O 5 films could be related to the graphite-like structure that exists in the amorphous state of this oxide

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

    Science.gov (United States)

    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.

  17. β-radiation exposure with 188Re-labelled pharmaceuticals

    International Nuclear Information System (INIS)

    Andreeff, M.; Wunderlich, G.; Kotzerke, J.; Behge, K.; Schoenmuth, Th.

    2005-01-01

    Aim: The number of therapies with radiopharmaceuticals labelled with 188 Re is increasing requiring the documentation of the beta radiation exposure Hp(0.07) of the staff at all working and production sites and during the application and follow-up of the patient according to the new German Radiation Protection Law (StrlSchV). However, data for β-radiation exposure are rare. Therefore, we determined the personal dose Hp(0.07) of the skin of the hands handling 188 Re radiopharmaceuticals to identify steps of high radiation exposure and to optimize working conditions. Method: Thermoluminescence dosimeters (TLD 100) were fixed to the fingertips of the radiochemist, the physician and the nurse and compared to official ring dosimeters. In addition, to monitor radiation exposure continuously readable electronic beta- and gamma dosimeters EPD (Siemens) were used. At eight days in which therapies were performed these readings were evaluated. Results: Considering one therapy with a 188 Re-labelled radiopharmaceutical the middle finger of the radiochemist (production) and the physician (application) showed a radiation burden of 894 and 664 μSv/GBq, respectively. The cumulative dose of the fingertips after eight days of therapy was 249 and 110 mSv for the radiochemist and physician, respectively. A cumulative finger dose after eight days of therapy of 17 and 39 μSv/GBq was found for physician and nurse leading to a Hp(0.07) of 3 and 6 mSv, respectively. Preparing the radiopharmaceutical labelled with 20 GBq of 188 Re the reading of the personal electronic dosimeter of the radiochemist showed a γ-dose rate Hp(10) of 55 μSv/h and a β-dose rate Hp(0.07) of 663 μSv/h which are obviously not representative for the true radiation dose to the skin of the fingertips. Conclusion: During therapy with 188 Re-labelled radiopharmaceuticals the true radiation dose to the skin of the finger tips exceeds by far the readings of the official ring dosimeters as well as the continuously

  18. A 175 Hz / 188 Hz active filter for private power producers; Filtre actif 175 HZ/188 HZ pour producteurs autonomes

    Energy Technology Data Exchange (ETDEWEB)

    Michalak, P.

    1996-12-31

    The connection of certain private electric power producers on the source station bus bars may disturb the 175 Hz or 188 Hz centralized control system signals, which carry tariff messages to the Electricite de France (EDF) grid clients. A new active filter has been developed by EDF and Schlumberger, which raise the tariff signal level at the bus bars by injection of a signal with the same frequency. A prototype has been tested in real conditions

  19. 34 CFR 668.188 - Preventing evasion of the consequences of cohort default rates.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 3 2010-07-01 2010-07-01 false Preventing evasion of the consequences of cohort default rates. 668.188 Section 668.188 Education Regulations of the Offices of the Department of Education... Two Year Cohort Default Rates § 668.188 Preventing evasion of the consequences of cohort default rates...

  20. 46 CFR 188.05-5 - Specific application noted in text.

    Science.gov (United States)

    2010-10-01

    ... which the text pertains, and in many cases limits the application of the text to vessels contracted for... 46 Shipping 7 2010-10-01 2010-10-01 false Specific application noted in text. 188.05-5 Section 188... GENERAL PROVISIONS Application § 188.05-5 Specific application noted in text. (a) At the beginning of the...

  1. Interaction between lipid monolayers and poloxamer 188: An X-ray reflectivity and diffraction study

    DEFF Research Database (Denmark)

    Wu, G.H.; Majewski, J.; Ege, C.

    2005-01-01

    The mechanism by which poloxamer 188 (P188) seals a damaged cell membrane is examined using the lipid monolayer as a model system. X-ray reflectivity and grazing-incidence x-ray diffraction results show that at low nominal lipid density, P188, by physically occupying the available area and phase ...

  2. 19 CFR 122.188 - Issuance of temporary Customs access seal.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Issuance of temporary Customs access seal. 122.188 Section 122.188 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY AIR COMMERCE REGULATIONS Access to Customs Security Areas § 122.188 Issuance of...

  3. Comparison of the mechanical properties between tantalum and nickel-titanium foams implant materials for bone ingrowth applications

    International Nuclear Information System (INIS)

    Sevilla, P.; Aparicio, C.; Planell, J.A.; Gil, F.J.

    2007-01-01

    Metallic porous materials are designed to allow the ingrowth of living tissue inside the pores and to improve the mechanical anchorage of the implant. In the present work, tantalum and nickel-titanium porous materials have been characterized. The tantalum foams were produced by vapour chemical deposition (CVD/CVI) and the NiTi foams by self-propagating high temperature synthesis (SHS). The former exhibited an open porosity ranging between 65 and 73% and for the latter it ranged between 63 and 68%. The pore sizes were between 370 and 440 μm for tantalum and between 350 and 370 μm for nickel-titanium. The Young's modulus in compression of the foams studied, especially for tantalum, were very similar to those of cancellous bone. This similitude may be relevant in order to minimize the stress shielding effect in the load transfer from the implant to bone. The strength values for NiTi foam are higher than for tantalum, especially of the strain to fracture which is about 23% for NiTi and only 8% for tantalum. The fatigue endurance limit set at 10 8 cycles is about 7.5 MPa for NiTi and 13.2 MPa for tantalum. The failure mechanisms have been studied by scanning electron microscopy

  4. The Chemistry of Re-188 Radiopharmaceuticals: Could Re-188 Play the Same Role in Therapy as Tc-99m in Diagnostics?

    International Nuclear Information System (INIS)

    Duatti, A.

    2009-01-01

    Radiopharmaceuticals incorporating the β-emitting radionuclide Re-188 are still attracting much interest for their potential application in nuclear medicine as therapeutic agents. There are many advantages of employing this class of radioactive compounds as briefly summarized in the following. (1) Re-188 emits a high-energy β- particle (2.1 MeV) that can be efficiently used to deliver high-dose radiation to the target. (2) Re-188 concomitantly emits a 155-keV γ photon that can be conveniently employed to obtain good-quality SPECT images of the biodistribution of Re-188 radiopharmaceuticals and, ultimately, following in vivo the course of the therapy. (3) Re-188 has a relatively short half-life (17 hours) that may allow multiple treatments of the same patient's disease. (4) Re-188 is a radiometal belonging to the same group of Tc-99m in the transition metal series of the Periodic Table, and shares with its cogener similar (though not identical) chemical properties that could be useful for designing a broad class of Re-188 radiopharmaceuticals having the same biodistribution properties of the corresponding Tc-99m analogues. (5) Similarly to Tc-99m, the radionuclide Re-188 is produced in high-specific activity through the 188 W/ 188 Re transportable generator system. A first challenge encountered in the attempt to develop efficient labeling procedures for Re-188 was related to the low radiochemical yield usually observed in tracer-level preparations of Re-188 radiopharmaceuticals starting from generator-produced [ 188 ReO 4 ]-. This drawback is commonly associated with the low value of the standard reduction potential of the tetraoxo anion as compared to the corresponding Tc-99m pertechnetate anion. In recent years, we reported a simple and efficient procedure for overcoming this problem based on a general chemical principle called 'expansion of the coordination sphere' and involving the addition to the reaction vial of an ancillary ligand (usually, chelating hard

  5. Electrochemical Properties of Transparent Conducting Films of Tantalum-Doped Titanium Dioxide

    Czech Academy of Sciences Publication Activity Database

    Krýsová, Hana; Mazzolini, P.; Casari, C. S.; Russo, V.; Li Bassi, A.; Kavan, Ladislav

    2017-01-01

    Roč. 232, APR 2017 (2017), s. 44-53 ISSN 0013-4686 R&D Projects: GA ČR GA13-07724S Institutional support: RVO:61388955 Keywords : titanium dioxide * tantalum doping * electrochemistry Subject RIV: CG - Electrochemistry OBOR OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) Impact factor: 4.798, year: 2016

  6. Activation analysis of trace amounts of rare earth in high purity tantalum

    International Nuclear Information System (INIS)

    Ishibashi, Wataru; Saito, Shinichi; Hirayama, Tooru.

    1975-01-01

    It is necessary to separate rare earth from tantalum by rapid methods in order to remove effects of a strong radioactivity and a short half-life. Tantalum is extracted with 10%N-lauryl (trialkylmethyl) amino-benzene pre-equilibrated with a solution of 9 M hydrochloric and 0.15 M hydrofluoric acid. A non-radioactive rare earth element is added to this aqueous solution, a precipitate of trace amounts of radioactive rare earth in aqueous solution is formed by this addition of rare earth. Some factors in the determination are: 1) the effect of the irradiation position of the sample in the atomic reactor, 2) the effect on the extraction with 10%N-lauryl (trialkylmethyl) amino-benzene for the radioactive rare earth, 3) the effect of the concentration of hydrofluoric acid, ammonia water and nitric acid on co-precipitation. As a result of the investigation we obtained the following satisfactory results: 1) Rare earth was not effected by the extraction of tantalum with 10%N-lauryl (trialkylmethyl) amino-benzene. 2) The recovery of rare earth by co-precipitation increases when an ammonium ion coexists, and when the concentration of hydrofluoric acid decreases, but the recovery decreases with the increase of nitric acid concentration. 3) The time required for the extraction is 9 hours. In case of determination for dysprosium, tantalum extracted with 10%N-lauryl (trialkylmethyl) amino-benzene before activation and the time for separation is 2 hours. (auth.)

  7. Synthesis of a Bis(thiophenolate)pyridine Ligand and Its Titanium, Zirconium, and Tantalum Complexes

    KAUST Repository

    Lenton, Taylor N.; VanderVelde, David G.; Bercaw, John E.

    2012-01-01

    -membered chelate with longer metal-sulfur and carbon-sulfur bonds. Solid-state structures of tantalum complexes (SNS)Ta(NMe 2) 3 (5) and (SNS)TaCl(NEt 2) 2 (6) also display pronounced C 2 twisting of the SNS ligand. 1D and 2D NMR experiments show that 5

  8. Electrosynthesis of tantalum borides in oxygen-free and oxygen-containing fluoride melts

    DEFF Research Database (Denmark)

    Polyakova, L.P.; Polyakov, E.G.; Makarova, O.V.

    2001-01-01

    Results of electrosynthesis of tantalum borides in fluoride and oxyfluoride melts are compared. It is shown that the single-phase X-ray-amorphous micro-layered coatings form only in the latter case. Linear and square-wave voltammetry, complemented by X-ray diffraction analysis, IR spectroscopy...

  9. Morphology, proliferation, and osteogenic differentiation of mesenchymal stem cells cultured on titanium, tantalum, and chromium surfaces

    DEFF Research Database (Denmark)

    Stiehler, Maik; Lind, M.; Mygind, Tina

    2007-01-01

    the interactions between human mesenchymal stem cells (MSCs) and smooth surfaces of titanium (Ti), tantalum (Ta), and chromium (Cr). Mean cellular area was quantified using fluorescence microscopy (4 h). Cellular proliferation was assessed by (3)H-thymidine incorporation and methylene blue cell counting assays (4...

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

    Energy Technology Data Exchange (ETDEWEB)

    Denny, Yus Rama [Department of Physics Education, University of Sultan Ageng Tirtayasa, Banten 42435 (Indonesia); Firmansyah, Teguh [Department of Electrical Engineering, University of Sultan Ageng Tirtayasa, Banten 42435 (Indonesia); Oh, Suhk Kun [Department of Physics, Chungbuk National University, Cheongju 28644 (Korea, Republic of); Kang, Hee Jae, E-mail: hjkang@cbu.ac.kr [Department of Physics, Chungbuk National University, Cheongju 28644 (Korea, Republic of); Yang, Dong-Seok [Department of Physics Education, Chungbuk National University, Cheongju 28644 (Korea, Republic of); Heo, Sung; Chung, JaeGwan; Lee, Jae Cheol [Analytical Engineering Center, Samsung Advanced Institute of Technology, Suwon 16678 (Korea, Republic of)

    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), 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.

  11. Oxidation and Volatilization from Tantalum Alloy T-222 During Air Exposure

    Energy Technology Data Exchange (ETDEWEB)

    Smolik, Galen Richard; Petti, David Andrew; Sharpe, John Phillip; Schuetz, Stanley Thomas

    2000-10-01

    Tantalum alloys are one of the refractory metals with renewed consideration for high temperatures in fusion reactor applications. Tantalum alloys perform well in protective environments but oxidized readily in gases containing higher oxygen levels. In addition, the radioactive isotope Ta-182 would be produced in tantalum and could be a significant contributor to dose if mobilized. Other isotopes of importance are produced from tungsten and hafnium. Mobilization of activated products during an accident with air ingress is therefore a safety issue. In this study, we measured the extent of oxidation and mobilization from tantalum alloy T-222 oxidized in flowing air between 500 and 1200°C. This alloy nominally contains 10 wt% tungsten, 2.5 wt% hafnium and 0.01 wt% carbon. We found that the mobilization of Ta and Hf was closely linked to the occurrence of oxide spalling. These elements showed no migration from the test chamber. Some W was mobilized by volatilization as evidenced by transport from the chamber. Tungsten volatilization could occur primarily during initial stages of oxidation before an oxide scale forms and impedes the process. The mobilization of Ta and W are presented in terms of the mass flux (g/m 2 -h) as a function of test temperature. These measurements along with specific designs, activation calculations, and accident scenarios provide information useful for dose calculations of future fusion devices

  12. Oxidation and Volatilization from Tantalum Alloy T-222 During Air Exposure

    Energy Technology Data Exchange (ETDEWEB)

    Smolik, G.R.; Petti, D.A.; Sharpe, J.P.; Schuetz, S.T.

    2000-10-31

    Tantalum alloys are one of the refractory metals with renewed consideration for high temperatures in fusion reactor applications. Tantalum alloys perform well in protective environments but oxidized readily in gases containing higher oxygen levels. In addition, the radioactive isotope Ta-182 would be produced in tantalum and could be a significant contributor to dose if mobilized. Other isotopes of importance are produced from tungsten and hafnium. Mobilization of activated products during an accident with air ingress is therefore a safety issue. In this study, we measured the extent of oxidation and mobilization from tantalum alloy T-222 oxidized in flowing air between 500 and 1200 C. This alloy nominally contains 10 wt% tungsten, 2.5 wt% hafnium and 0.01 wt% carbon. We found that the mobilization of Ta and Hf was closely linked to the occurrence of oxide spalling. These elements showed no migration from the test chamber. Some W was mobilized by volatilization as evidenced by transport from the chamber. Tungsten volatilization could occur primarily during initial stages of oxidation before an oxide scale forms and impedes the process. The mobilization of Ta and W are presented in terms of the mass flux (g/m 2 -h) as a function of test temperature. These measurements along with specific designs, activation calculations, and accident scenarios provide information useful for dose calculations of future fusion devices.

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

    Science.gov (United States)

    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.

  14. Contact Resistance of Tantalum Coatings in Fuel Cells and Electrolyzers using Acidic Electrolytes at Elevated Temperatures

    DEFF Research Database (Denmark)

    Jensen, Annemette Hindhede; Christensen, Erik; Barner, Jens H. Von

    2014-01-01

    stainless steel were found to be far below the US Department of Energy target value of 10mcm2. The good contact resistance of tantalum was demonstrated by simulating high temperature polymer electrolyte membrane electrolysis conditions by anodization performed in 85% phosphoric acid at 130◦C, followed...

  15. Synthesis and magnetic properties of highly dispersed tantalum carbide nanoparticles decorated on carbon spheres

    CSIR Research Space (South Africa)

    Bhattacharjee, K

    2016-01-01

    Full Text Available The decoration of carbon spheres (CS) by highly dispersed tantalum carbide nanoparticles (TaC NPs) was achieved, for the first time by a unique carbothermal reduction method at 1350 °C for 30 min under reduced oxygen partial pressure. TaC NPs...

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

    Science.gov (United States)

    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.

  17. Formation of oxide layers on aluminum, niobium, and tantalum in molten alkali metal carbonates

    Science.gov (United States)

    Nikitina, E. V.; Kazakovtseva, N. A.

    2013-08-01

    The electrochemical synthesis of niobium, tantalum, and aluminum oxide nanolayers is studied in the melt of lithium, sodium, and potassium carbonates with various additives to a salt phase in an oxidizing atmosphere at a temperature of 773 and 873 K. A scheme is proposed for high-temperature anion local activation of the process.

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

    Science.gov (United States)

    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...

  19. The development of fast tantalum foil targets for short-lived isotopes

    CERN Document Server

    Bennett, J R J; Drumm, P V; Ravn, H L

    2003-01-01

    The development of fast tantalum foil targets for short-lived isotopes was discussed. It was found that the effusion was faster but the diffusion out of the foils was a limiting factor. The performance of the targets at ISOLDE with beams of **1**1Li, **1**2Be and **1**4Be was also analyzed. (Edited abstract) 13 Refs.

  20. Swelling and tensile properties of EBR-II-irradiated tantalum alloys for space reactor applications

    International Nuclear Information System (INIS)

    Grossbeck, M.L.; Wiffen, F.W.

    1985-01-01

    The tantalum alloys T-111, ASTAR-811C, Ta-10 W, and unalloyed tantalum were examined following EBR-II irradiation to a fluence of 1.7 x 10 26 neutrons/m 2 (E > 0.1 MeV) at temperatures from 650 to 950 K. Swelling was found to be negligible for all alloys; only tantalum was found to exhibit swelling, 0.36%. Tensile testing revealed that irradiated T-111 and Ta-10 W are susceptible to plastic instability, but ASTAR-811C and tantalum were not. The tensile properties of ASTAR-811C appeared adequate for current SP-100 space nuclear reactor designs. Irradiated, oxygen-doped T-111 exhibited no plastic deformation, and the abrupt failure was intergranular in nature. The absence of plastic instability in ASTAR-811C is encouraging for alloys containing carbide precipitates. These fine precipitates might prevent dislocation channeling, which leads to plastic instability in many bcc metals after irradiation. 10 refs., 13 figs., 8 tabs

  1. Technological challenges in extractive metallurgy and refining of niobium, tantalum and preparation of their alloys

    International Nuclear Information System (INIS)

    Mirji, K.V.; Sheela; Saibaba, N.

    2016-01-01

    Manufacturing of refractory and reactive metals, their alloys and fabricated products has been always difficult due to their high affinity with atmospheric gases, stringent specifications and exhaustive quality requirements. In the field of development of these materials, Nuclear Fuel Complex (NFC), Hyderabad has been at the fore front in accepting the challenges for the advancement of technological growth. Extensive developments have been carried out during the last few decades in the field of niobium, tantalum, zirconium etc in the form of pure metal, their compounds and alloys. Over the period of time, efforts have been made for developing sophisticated facilities along with trained man power for manufacturing of critical items for which technical knowhow is not available either with private industries or any other organizations in the country. In the field of reactive metals, though general theory is well established, production is intriguing and requires expert handling on the field. At NFC, efforts were put towards industrial adoptability of the useful knowledge gained from lab scale to reliable production scale. Comprehensive study was conducted to systematically study the effects of various process parameters starting from ore to the metals and their alloys, equipment were modified for ease of operation with stress on recycling/reusing of the waste and handling of effluents. However scale of operation and therefore cost of production has been matter of concern in the field of tantalum and niobium. Electron beam refining is used for production of highly pure reactive and refractory metals like tantalum, niobium, zirconium etc. and their alloys under high vacuum. Special Materials Plant (SMP) at Nuclear Fuel Complex, Hyderabad has developed processes for production of niobium oxide, tantalum oxide, tantalum metal powder, tantalum anodes/capacitors, potassium tantalum fluoride, Nb thermit, Nb metal granules, RRR grade niobium, Nb base alloys such as Zr

  2. Tin(2) difluoride and antimony(3) trifluoride as fluorine donors in reactions with tantalum halides in various solvents

    International Nuclear Information System (INIS)

    Kokunov, Yu.V.; Ershova, M.M.; Razgonyaeva, G.A.; Buslaev, Yu.A.

    2001-01-01

    The reactions of SnF 2 , SbF 3 with TaF 5 and TaCl 5 in acetonitrile and dimethylsulfoxide were studied by means of 19 F and 119 Sn NMR. SnF 2 and SbF 3 were established to be donors of fluorine ions for the tantalum(5). It was found that the anion and cation tantalum fluorochloride complexes were formed in acetonitrile, and [TaF 6 ] - was dominated in dimethylsulfoxide. In the solution the tin(2) is present as fluorine-containing polymer cations. Dimethylsulfoxide, as distinct from acetonitrile, leads to disproportionation of tantalum fluorochlorides [ru

  3. Study on the preparation and stability of 188Re biomolecules via EHDP

    International Nuclear Information System (INIS)

    Ferro-Flores, G.; Garcia-Salinas, L.; Paredes-Gutierrez, L.; Hashimoto, K.; Melendez-Alafort, L.; Murphy, C.A.

    2001-01-01

    A direct labelling technique via ethane-1-hydroxy-1,1-diphosphonic acid (EHDP) as a weak competing ligand was developed for the preparation of several biomolecules: 188 Re-monoclonal antibody ior cea1 against carcinoembryonic antigen ( 188 Re-MoAb), biotinylated 188 Re-MoAb ( 188 Re-MoAb-biotin), 188 Re-polyclonal IgG ( 188 Re-IgG), 188 Re-peptide (somatostatine analogue peptide b-(2-naphtyl)-D-Ala-Cys-Tyr-D-Trp-Lys-Val-Cys-Thr-amide), 188 Re-MoAb fragments ( 188 Re-F(ab') 2 ) and biotinylated 188 Re-F(ab') 2 ( 188 Re-F(ab') 2 -biotin). The reaction conditions such as pH, temperature, weak ligand concentration and stannous chloride concentration were optimized during the radiolabelling of each biomolecule. Before the labelling procedure, disulphide bridge groups of the biomolecules were reduced with 2-mercaptoethanol (2-ME). To obtain 188 Re labelled antibodies and peptides in high radiochemical yields (>90%) via EHDP, it was necessary to use acidic conditions and a high concentration of stannous chloride to allow the redox reaction Re +7 →Re +5 :Re +4 . The labelling of MoAb and F(ab') 2 with 188 Re via EHDP was also evaluated employing a pretargeted technique by avidin-biotin strategy in normal mice, demonstrating that the 188 Re-labelled biotinylated antibodies are stable complexes in vivo. The 188 Re-peptide complex prepared by this method, was stable for 24 h and no radiolytic degradation was observed. (author)

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

    Science.gov (United States)

    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

  5. Rhenium-188-Lipiodol therapy of liver cancer: Optimization of conjugate-view imaging of 188Re for patient-specific dosimetry

    International Nuclear Information System (INIS)

    Chaudakshetrin, P.; Osorio, M.; Padhy, A.K.; Divgi, C.; Zanzonico, P.

    2004-01-01

    Full text: Intrahepatic artery Lipiodol labeled with generator-produced, β-emitting 188Re (17 hr; Eβ=0.53-0.70 MeV; Range=4 mm) localizes in and may effectively treat inoperable liver tumors. Although 188Re emits an imageable 155-keV γ ray (15%), its 478- and 633-keV β rays (2.3%) complicate imaging. Our objective was to optimize 188Re image quality and conjugate-view accuracy for quantitative imaging-based patient-specific dosimetry for 188Re-Lipiodol. Using an ADAC dual-EpicO-circumflex-detector gamma camera, 188Re intrinsic and extrinsic (with LEGP, MEGP, and HEGP collimation) uniformities using either 99mTc intrinsic or 188Re extrinsic flood corrections were evaluated. 188Re conjugate view count rate vs. activity concentration linearity as a function of scattering/attenuating medium thickness was then evaluated with and without corrections for attenuation (a 188Re transmission image) and for scatter and septal penetration, subtracting a fraction of counts in a lower-energy (109-140 keV)- and a higher-energy (170-201 keV)-window image, respectively, from the 20% (140-171 keV) photopeak image. Our phantom consisted of 5 10-ml vials containing 25 to 400 μCi/ml of 188Re with 0 to 6 cm at different positions (∼5 cm apart) between the detectors (60 cm apart) and with a 0- to 6-cm thickness of non-radioactive water between the vials and each detector. With a 99mTc intrinsic correction, 188Re intrinsic uniformity was excellent ( 10% and 'tubey'), and was poorer the lower the energy rating of the collimation. Uniformity with HEGP collimation and an extrinsic 188Re correction was acceptable ( 0.95) and the slope (cps/pixel/μCi/ml) was constant +25% (vs +10% for 99mTc) for 0- to 6-cm thicknesses of water. Regardless of the fraction of counts subtracted, neither scatter nor septal-penetration correction improved the slope constancy. Conclusion: Downscatter/septal penetration of the 478- and 633-keV 188Re γ-rays complicates imaging of its 155-keV γ-ray. Using HEGP

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

    Science.gov (United States)

    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.

  7. Young stars in the old galactic cluster NGC 188

    International Nuclear Information System (INIS)

    Veer, F. van 't

    1984-01-01

    We first briefly discuss the age of the oldest known galactic clusters, according to recently published determinations. The now definitely established membership of our W UMa type contact binaries in this cluster is difficult to understand if the age of these stars is that of the cluster. It appears therefore that these binaries are much younger and that the several episodes of star formation took place in NGC 188. This conclusion is reached after a new study of the mean density of the four contact binaries and a critical discussion of the chemical composition and the mixing length parameter. (orig.)

  8. Intraspecific responses of 188 rice cultivars to enhanced UVB radiation

    International Nuclear Information System (INIS)

    Dai, Q.; Peng, A.; Chavez, A.Q.; Vergara, B.S.

    1994-01-01

    Phytotron studies were conducted to determine the intraspecific variation in sensitivity of rice (Oryza sativa L.) to enhanced UVB and to test the hypothesis that rice cultivars originating from regions with higher ambient UVB radiation are more tolerant to enhanced UVB. Out of the 188 rice cultivars (from various rice growing regions and ecosystems) tested, 143 had significantly reduced plant height, 52 had smaller leaf area, 61 had lower plant dry weight and 41 had less tiller number under elevated UVB radiation (13.0 kJ m −2 day −1 ) for 3 weeks. Six cultivars showed significant positive growth response to enhanced UVB radiation, although the mechanism is not clear at present. These six cultivars were from the summer rice crop of Bangladesh and from high elevation rice areas where prevailing UVB radiation is most likely to be greater. However, there was no correlation between the dry matter changes under enhanced UVB and the ambient UVB level at the origin of the cultivar across the 188 cultivars tested. Therefore, cultivars originating from regions with higher ambient UVB are not necessarily more tolerant to enhanced UVB radiation. (author)

  9. Labeling Lanreotide with 125I and 188Re

    International Nuclear Information System (INIS)

    Bai Hongsheng

    2000-01-01

    Lanreotide is a new somatostatin analogue. It can bind to human somatostatin receptor (hSSTR) subtype 2 through 5 with high affinity and to hSSTR subtype I with low affinity. We investigate labeling condition, quality control and stability in vitro of 125 I-Lanreotide and 188 Re-lanreotide respectively. (A) Lanreotide is labeled with 125 I using Chloramine T. The effect of reaction condition (such as reaction time, pH value, Lanreotide amount, quantity of Chloramine T and reaction volume) on labeling yield is investigated in detail. (B) The labeling yield and radiochemical purity (RP) is measured with paper chromatography (PC) and Sep-Pak C 18 Cartridge. (C) The stability of 125 I-Lanreotide in vitro is investigated by labeling compound incubating for 48 hours at 37 deg C in the 0.9% sodium chloride solution and RP is tested by PC at specific time intervals. (D) Lanreotide is labeled directly with 188 Re via the mixture of citrate and tartate using stannous chloride as reduced agent. The influence of reaction conditions such as pH, temperature, amount of stannous chloride, amount of Lanreotide and reaction time on labeling yield is investigated in detail. At the time, the stability in vitro quality control and animal test are evaluated

  10. Poisoning Experiments Aimed at Discriminating Active and Less-Active Sites of Silica-Supported Tantalum Hydride for Alkane Metathesis

    KAUST Repository

    Saggio, Guillaume

    2010-10-04

    Only 50% of the silica-supported tantalum hydride sites are active in the metathesis of propane. Indeed, more than 45% of the tantalum hydride can be eliminated by a selective oxygen poisoning of inactive sites with no significant decrease in the global turnover. Conversely, cyclopentane induces no such selective poisoning. Hence, the active tantalum hydride sites that show greater resistance to oxygen poisoning correspond to the νTa-H bands of higher wavenumbers, particularly that at 1860cm-1. These active tantalum hydride sites should correspond to tris- or monohydride species relatively far from silica surface oxygen atoms. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Evaluation of corrosion behaviour of tantalum coating obtained by low pressure chemical vapor deposition using electrochemical polarization

    Science.gov (United States)

    Levesque, A.; Bouteville, A.; de Baynast, H.; Laveissière, B.

    2002-06-01

    antalum coatings are elaborated on titanium substrates through Low Pressure Chemical Vapor Deposition from tantalum pentachloride-hydrogen gaseous phase at a deposition temperature of 800 °C and a total pressure of 3.3 mbar. The aim of this paper is to evaluate the effectiveness of this tantalum coating in corrosive solution. Optical Microscopy and Scanning Electron Microscopy observations reveal that deposits are of 1.7 μm in thickness and conformal. The corrosion resistance of tantalum coated titanium substrates is quantified through standard potentiodynamic polarization method. Even for tantalum coatings exhibiting some defects as pores, the corrosion current density is as low as 0.25 mA/cm^2.in very agressive solutions like kroll reagent (HN03/HF).

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

    CSIR Research Space (South Africa)

    Archer, M

    2003-12-01

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

  13. Study of different absorbent materials for the preparation of generator systems of 99Mo - 99mTc and 188W-188Re

    International Nuclear Information System (INIS)

    Lopes, Paula Regina Corain; Osso Junior, Joao Alberto

    2009-01-01

    Amongst some currently radioisotopes, 99m Tc and 188 Re present adequate decay properties for use in Nuclear Medicine. In the current times the most diagnosis examinations are performed with 99m Tc and 188 Re is one radioisotope of potential use in therapy techniques. The objective of this work consists of determining the capacity of some adsorbent materials for retention of molybdenum and tungsten, aiming the optimization of generator systems of 99 Mo- 99m Tc and 188 W- 188 Re with suitable characteristics for application in Nuclear Medicine. Known amounts, in mass, of molybdenum and tungsten were percolated through different chromatographic columns containing different commercial adsorbent materials such as: PZC (poly-zirconium compound), acid alumina and calcinated alumina used in the routine preparation of 99 Mo- 99m Tc generators at IPEN. The tungsten ( 188 W), as well the PZC used in this project, supplied by Russia and Japan, respectively, through the International Atomic Energy Agency (IAEA) and used without any previous preparation. Also trace amounts of 99 Mo and 188 W were added to the initial solutions and the generators were assembled. The 99 Mo- 99m Tc generators were then eluted with known volumes of 0.9% NaCl solution every 24 hours whereas the 188 W- 188 Re generators were eluted every 48 hours. The eluted samples were analyzed by Gamma Spectroscopy and later submitted to quality control evaluation. The results showed that the PZC presents superior retention capacity for Mo of 97.50mg Mo/gPZC, higher than in acid and calcinated alumina, however the elution efficiency at lower pHs is not so high. With regards to the experiments carried out with 188 W and alumina, it was verified that the elution efficiency of 188 Re was not reproducible and the retention capacity of W was 90.23mgW/gAl 2 O 3 at pH 7. (author)

  14. Experimental study of the biological properties of 188Re-Hepama-1 biologic superparamagnetic nanoparticles

    International Nuclear Information System (INIS)

    Feng Yanlin; Tan Jiaju; Sun Jing; Wen Guanghua; Wu Xiaolian; Liang Sheng; Xia Jiaoyun

    2007-01-01

    Objective: To investigate a new biologic-superparamagnetic nanoparticles's characteristics of immunological activity, biological distributing in vivo, targeting and inhibiting tumor effect. Methods: The experimental group 188 Re-Hepama-l-superparamagnetic nanoparticles, and control groups, including 188 ReO 4 - , 188 Re-Hepama-1, and 188 Re-superparamagnetic nanoparticles, were set up. The distributions were measured after injection 4 h and 24 h by caudal vein of Kuming mice. The magnetic targeting experiments in vivo were clone with and without magnetic field in liver after injection in New Zealand rabbit. The inhibiting tumor effect on hepatic cancer cell lines SMMC-7721 of the above four 188 Re labeled products were measured by mono nuclear cell direct cytotoxicity assay method. Results: After injection 4 h and 24 h by vein, the liver taking was highest in group 188 Re-Hepama-l-superparamagnetic nanoparticles. The radiative activity in liver in magnetism zoo was higher than in non magnetism zoo in 188 Re- Hepama-1-superparamagnetic nanoparticles after applying magnetic field in left lobe of liver, and the ratio of in magnetism zoo to non magnetism zoo was 1.87. And the half effective inhibition radioactive concentrations (IC 50 ) in 188 Re-Hepama-l-superparamagnetic nanoparticles was one forth of 188 ReO 4 - . Conclusion: 188 Re- Hepama-l-superparamagnetic nanoparticles showed its fine stability in intro, good immunological activity and significant liver target. (authors)

  15. Establishment of an analytical procedure for the determination of niobium and tantalum in minerals containing these elements using X-ray fluorescence technique

    International Nuclear Information System (INIS)

    Nguyen Xuan Chien

    2003-01-01

    The study of determination of niobium, tantalum in mineral and tin slags using X-ray fluorescence spectrometry was carried out. Analytical samples of powder and pellet were prepared. the interference of the major accompanied elements in sample with the determination of niobium and tantalum was also studied. The analysis of niobium and tantalum in mineral and in tin slags samples was given in this work. (author)

  16. Complexation of 188Re-phosphonates: in vitro and in vivo studies

    International Nuclear Information System (INIS)

    Faintuch, B.L.; Muramoto, E.; Faintuch, S.

    2003-01-01

    MDP (methylenediphosphonate) and HEDP (hydroxyethylidene diphosphonate), both disphosphonates, and EDTMP (ethylenediamine tetramethylene phosphonic acid), a tetraphosphonate ligand, have been previously labeled with 188 Re for use in metastatic bone-pain palliation. The aim of this study was a comparison between the three complexes 188 Re-MDP, 188 Re-HEDP and 188 Re-EDTMP concerning the complexation conditions, in order to achieve maximum yield, stability and bone uptake. Methods: MDP was dissolved in water and HEDP and EDTMP were dissolved in NaOH 1 N followed by reduction of pH with HCl 1 N. To all mixtures stannous chloride and 188 ReO 4 - were added in a nitrogen atmosphere. The preparations were heated in boiling water bath for 15 min. Yield as well as radiochemical stability was estimated by ITLC. Different concentrations of phosphonates and stannous chloride were evaluated. Biodistribution studies in Swiss mice were done for the three 188 Re-phosphonates that presented the best radiochemical yield. The optimal ligand concentration for maximum complexation was 85.2 mM for MDP, 72.8 mM for HEDP and 45.8 mM for EDTMP. The best amount of SnCl 2 .2H 2 O was 1.5 mg/mL for 188 Re-HEDP and 1 mg/mL for both 188 Re-MDP and 188 Re-EDTMP. In these conditions the three complexes showed a complexation rate above 95%. Reasonable radiochemical stability for 24 hours was achieved by 188 Re-EDTMP when employing ascorbic acid. All products showed a great uptake by the kidneys. 188 Re-EDTMP had the greatest uptake by femur (3.1 ± 0.2% ID/g) followed by 188 Re-MDP (1.2 ± 0.1% ID/g) and 188 Re-HEDP (1.0 ± 0.1% ID/g), 4 hours post injection. 188 Re-EDTMP displayed a femur bone/muscle ratio of 28.5, 188 Re-MDP 4.9 and 188 Re-HEDP 4.9. In conclusion 188 Re-EDTMP demonstrated the best potential as a radiopharmaceutical for bone cancer pain relief, encouraging further dosimetric studies and clinical trials. (orig.)

  17. Tantalum X-ray contrast media, by M.G. Zuev and L.P. Larionov (Ekaterinburg: UrO RAN, 2002. 155 p.)

    International Nuclear Information System (INIS)

    Zhuravleva, E.Yu.

    2004-01-01

    The monograph of M.G. Zuev and L.P. Larionov Tantalum X-ray contrast media (Solid state chemistry for medicine series) is discussed. The monograph includes information on physical and chemical properties of tantalum, rare earths, and their oxides, phase compositions and phase diagrams of M 2 O 3 -Ta 2 O 5 (M - rare earths) systems is performed. Data on preclinical tests of yttrium orthotantalate and lanthanum orthotantalate as X-ray contrast media are given. Procedures for the production of X-ray contrast media involving tantalum oxide, rare earth tantalate and tantalum powder are described [ru

  18. Niobium, tantalum and titanium extraction from natural and technogenic raw materials of the Kola Peninsula by liquid-liquid extraction methods

    International Nuclear Information System (INIS)

    Kassikova, N.I.; Kassikov, A.G.; Balabanov, Yu.I.; Petrov, V.B.; Kalinnikov, V.T.

    2003-01-01

    Such rare metals as niobium and tantalum are important strategic materials underlying many of the modern advanced technologies. Since the extraction and processing of rare metal concentrates from own deposits has diminished abruptly in recent years, it is essential to look into the possibility of extracting these elements from various production wastes. This work discusses liquid-liquid extraction and purification of niobium, tantalum and titanium from process solutions of loparite, perovskite and sphene concentrate decomposition with sulphuric and hydrochloric acids; niobium from lithium niobate production wastes decomposed by hydrochloric acid; and tantalum from tantalum capacitor and heat-resistant alloy wastes. (Original)

  19. Effect of tantalum on α-martensite crystal structure in Co-Ta alloy

    International Nuclear Information System (INIS)

    Skorodzievskij, V.S.; Ustinov, A.I.; Chuistov, K.V.

    1985-01-01

    Changes in the crystal structure of α-martensite, formed during Co-Ta alloy hardening from the region of a homogeneous solid solution, are investigated by X-ray analysis methods. In case of increasing tantalum content in the alloy, intensity redistribution of X-ray scattering along the direction of the reverse space of H-K not equal to 3N (N=0, +-1, +-2...) type is fixed, which appears, depending on concentration, in continuous displacement of maxima from positions being characteristic for the initial 2H structure, as well as in occurring additional maxima and in changing the ratio between them by ipteΣity. For limiting values of tantalum concentration, where β → α-transformations are still observed, the number of intepsity maxima and their positions an the period of α-martensite reverse lattice recurrence period is closer to the location of 15R 1 -structure reverse structure unit

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

    International Nuclear Information System (INIS)

    Huang, Heng-Li; Chang, Yin-Yu; Chen, Hung-Jui; Chou, Yu-Kai; Lai, Chih-Ho; Chen, Michael Y. C.

    2014-01-01

    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) on the coatings are also determined by using the microculture tetrazolium assay. This study shows that Ta 2 O 5 and Ta 2 O 5 -Ag coatings with 12.5 at. % of Ag exhibit improved antibacterial effects against S. aureus and have good skin fibroblast cell cellular biocompatibility

  1. Determination of tantalum in standard steels by INAA and absorption spectrophotometry

    Energy Technology Data Exchange (ETDEWEB)

    Obrusnik, I; Posta, S [Ustav Jaderneho Vyzkumu, Rez (Czechoslovakia)

    1978-02-14

    Two analytical methods, instrumental neutron activation analysis (INAA) and absorption spectrophotometry with malachite green, have been used for the determination of tantalum in standard steels produced by the Research Institute of CKD Prague - steels No. 167 and No. 169 with expected concentrations of Ta 0.01% and 0.03%, respectively. INAA method consisted of irradiation of steel samples (chips) in a nuclear reactor and Ge(Li) ..gamma..-ray spectrometry after a cooling period of one month. A spectrophotometric determination is based on the extraction of ionic associate of TaF/sub 6//sup -/ with malachite green into Oenzene from a solution of diluted sulphuric acid and hydrofluoric acid. The results obtained by the two methods are in a good agreement. However, INAA method is more sensitive and precise then spectrophotometry for the determination of tantalum in steels in the above-mentioned concentration ranges.

  2. Determination of tantalum in standard steels by INAA and absorption spectrophotometry

    International Nuclear Information System (INIS)

    Obrusnik, I.; Posta, S.

    1978-01-01

    Two analytical methods, instrumental neutron activation analysis (INAA) and absorption spectrophotometry with malachite green, have been used for the determination of tantalum in standard steels produced by the Research Institute of CKD Prague - steels No. 167 and No. 169 with expected concentrations of Ta 0.01% and 0.03%, respectively. INAA method consisted of irradiation of steel samples (chips) in a nuclear reactor and Ge(Li) γ-ray spectrometry after a cooling period of one month. A spectrophotometric determination is based on the extraction of ionic associate of TaF 6 - with malachite green into Oenzene from a solution of diluted sulphuric acid and hydrofluoric acid. The results obtained by the two methods are in a good agreement. However, INAA method is more sensitive and precise then spectrophotometry for the determination of tantalum in steels in the above-mentioned concentration ranges. (author)

  3. Characterization of anodic barrier films on tantalum and 1100 aluminum by ISS/SIMS

    International Nuclear Information System (INIS)

    McCune, R.C.

    1978-01-01

    Ion scattering spectrometry (ISS) and concurrent secondary ion mass spectrometry (SIMS) were used to determine the depth profiles of anodic barrier oxide films grown on tantalum and type 1100 aluminum. The sputter rate in each case was determined from the film thickness measured by the anodic overvoltage, and the penetration time determined by the decrease in intensity of the metal oxide fragment observed using SIMS. A mixture of helium and neon ions was used to sputter aluminum oxide films in order to observe ion scattering of helium by oxygen, while taking advantage of the higher sputtering rate available with neon. A comparison of sputter rates for helium and neon on tantalum oxide indicated that neon sputtered the film at a rate eight times that of helium. SIMS depth profiling of the residual boron in the anodic aluminum oxide indicated a mixing effect which did not permit adequate resolution of the interface between the oxide film and the underlying metal

  4. Tantalum-containing Z-phase in 12%Cr martensitic steels

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson; Hald, John

    2009-01-01

    Z-phases in tantalum-containing 12%Cr steels have been investigated. In 12%Cr steel without any Nb or V, the formation of CrTaN Z-phases was observed. In 12%Cr steel which also contained V, the Ta entered Z-phase as a minor element, Cr(V,Ta)N. The crystal structure of Cr(V,Ta)N seems to be identi......Z-phases in tantalum-containing 12%Cr steels have been investigated. In 12%Cr steel without any Nb or V, the formation of CrTaN Z-phases was observed. In 12%Cr steel which also contained V, the Ta entered Z-phase as a minor element, Cr(V,Ta)N. The crystal structure of Cr(V,Ta)N seems...

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

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes, O [Univ. of California, Davis, CA (United States)

    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-3 or 93% relative density. In addition, those samples were consolidated without significant pre-reaction of the constituents, thus retaining their stored chemical energy.

  6. 188Re labeling and biodistribution of magnetic nanoparticles for the tumor targeting

    International Nuclear Information System (INIS)

    Li Guiping; Zhang Hui; Wang Yongxian; Zhang Chunfu

    2006-01-01

    Objective: To prepare 188 Re labeled monoclonal antibody (Herceptin)-coated magnetic nanoparticles for tumor targeting and to study its biodistribution in mice. Methods: Herceptin and histidine were covalently linked to the amine group upon silica-coated magnetic nanoparticles modified by N-[3-(trimethyoxysilyl)prowl]-ethylenediamine using glutaraldehyde method. The Herceptin-coated magnetic nanoparticles and Herceptin were radiolabeled with 188 Re by a direct labelling method, whereas the histidine-coated magnetic nanoparticles was radiolabeled with 188 Re using fac-[ 188 Re(CO) 3 (H 2 0) 3 ] + as a precursor. The labelling efficiency and immunoreactivity as well as labelling stability were determined. Also, the biodistribution of 188 Re-magnetic and 188 Re-Herceptin-magnetic nanoparticles were observed in mice. Results: Herceptin-coated magnetic nanoparticles was characterized by transmission electron microscope (TEM) with diameter about 60 nm, while histidine-coated magnetic nanoparticles about 30 nm. The labeling efficiency for 188 Re-Herceptin, 188 Re-magnetic nanoparticles and 188 Re-Herceptin-magnetic nanoparticles were all > 90% and had a better stability in vitro. The immunoreactivity of Herceptin linked to magnetic nanoparticles was still high. The biodistribution in mice was shown that 188 Re-magnetic nanoparticles and 188 Re-Herceptin- magnetic nanoparticles had higher radioactivity levels in blood. Magnetic nanoparticles with diameter of 30 or 60 nm had a long half-life in blood stream and were accumulated in liver. Conclusion: The efficiency and stability of labelling Herceptin-coated magnetic nanoparticles and labelling magnetic nanoparticles with 188 Re are suitable for in vivo study in tumor-beating nude mice models. (authors)

  7. Study on the pharmacal of 186,188Re-SZ39

    International Nuclear Information System (INIS)

    Zu Jianhua; Wu Yuanfang; Dong Mo; Li Huiyuan; ZhangYulong

    2000-01-01

    The stability, immunocompetence and cytotoxicity in tumor as well as tumor inhibiting rate of 186,188 Re-SZ39 are investigated. The results indicate that 186,188 Re-SZ39 is stable in vivo by imaging and the volume of tumor of nude mice reduced obviously. So 186,188 Re-SZ39 has a strong cytotoxicity effect against glioma cells and is of good prospect as immuno-radiotherapeutic agent

  8. Metal halide-phosphorus halide-alkyl halide complexes: reaction with niobium and tantalum pentachlorides

    International Nuclear Information System (INIS)

    Puri, D.M.; Saini, M.S.

    1978-01-01

    The reactions of niobium and tantalum pentachlorides with trichlorophosphine and phenyldichlorophosphine have been studied in presence of alkylating agents such as sec-butyl chloride, iso-butyl chloride, tert-butyl chloride, tert-anylchloride, cyclohexyl chloride and triphenylmethyl chloride. Solid products have been isolated and characterised by vibrational spectroscopy as ionic complexes of alkyl- and/or aryl-phosphonium cations with hexachloroniobate and hexachlorotantalate anions. (author)

  9. On-line separation of refractory hafnium and tantalum isotopes at the ISOCELE separator

    CERN Document Server

    Liang, C F; Obert, J; Paris, P; Putaux, J C

    1981-01-01

    By chemical evaporation technique, neutron deficient hafnium nuclei have been on-line separated at the ISOCELE facility, from the isobar rare-earth elements, in the metal-fluoride HfF/sub 3//sup +/ ion form. Half-lives of /sup 162-165/Hf have been measured. Similarly, tantalum has been selectively separated on the TaF/sub 4//sup +/ form. (4 refs) .

  10. Influence of strain-rate on the flow stress and ductility of copper and tantalum

    International Nuclear Information System (INIS)

    Regazzoni, G.; Montheillet, F.; Dormeval, R.; Stelly, M.

    1981-09-01

    Tensile experiments were carried out at strain-rates in a range from epsilon = 6.10 -5 to 3.10 3 s -1 at 293 K and 673 K or 773 K. Two types of copper (FCC) and pure tantalum (BCC) were tested. The variations of ductility have been investigated in relation with the σ - epsilon equations of the materials and the examinations of fracture surfaces. They can be explained in terms of stability and intrinsic ductility

  11. Hydrogen in niobium, tantalum, and vanadium: Structures, phase diagrams, and morphologies

    International Nuclear Information System (INIS)

    Schober, T.

    1978-07-01

    The paper discusses basic aspects of the reactions between the metals niobium, tantalum, vanadium, and hydrogen or deuterium. After an introduction to problems of preparation experimental technqiues for the investigation of hydrides are presented. The possible hydride structures are discussed. With vanadium, there are great differences between the structures of hydrides and deuterides. Detailed mention is also made of recent measurements of the NGH, TaH, VH, and VD phase diagrams. (orig./WBU) [de

  12. Estimation of niobium, tantalum and zirconium in a carbonate rich ore

    International Nuclear Information System (INIS)

    Navale, A.S.; Venkatakrishnan, R.R.; Sreenivas, T.

    2013-01-01

    A simple method using ICP-OES for estimation of tantalum, niobium and zirconium in a carbonate rich matrix is described. The sample is boiled with 10% v/v hydrochloric acid for 15 min and filtered. The residue is fused with ammonium bifluoride-ammonium sulphate flux and the melt is leached with water. Nb, Ta and Zr are estimated in the water leach by ICP-OES. (author)

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

    Science.gov (United States)

    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.

  14. A polycrystalline model for stress-strain behaviour of tantalum at 300 K

    International Nuclear Information System (INIS)

    Frenois, S.; Munier, E.; Pilvin, P.

    2001-01-01

    A polycrystalline model is proposed to model the large plastic deformation and texture evolutions in tantalum over a wide range of strain rates at room temperature. The mechanical behaviour is discussed in terms of back and effective stresses with the help of qualitative and quantitative TEM observations. Using these observations, an elasto-visco-plastic formulation for b.c.c. crystals is developed in the thermal activation framework. (orig.)

  15. Experimental investigation of thermophysical properties of eutectic Mo–C, graphite and tantalum at high temperatures

    International Nuclear Information System (INIS)

    Senchenko, V N; Belikov, R S; Popov, V S

    2016-01-01

    An experimental technique based on fast electrical heating for investigation of thermophysical properties of refractory materials under high pressures and at high temperatures is considered. A set of thermophysical properties of refractory materials such as specific enthalpy, specific heat capacity, specific resistivity, melting heat of eutectic Mo-C and thermal expansion of graphite and tantalum were determined. The obtained temperature of eutectic melting of MoC 0.82 shows close agreement with equilibrium Mo-C phase diagram. (paper)

  16. Preparation of tantalum carbide layers on carbon using the metalliding process

    Energy Technology Data Exchange (ETDEWEB)

    Massot, L. [Laboratoire de Genie Chimique UMR 5503, Departement Procedes Electrochimiques, Universite Paul Sabatier, 31062 Toulouse Cedex 9 (France)], E-mail: massot@chimie.ups-tlse.fr; Chamelot, P. [Laboratoire de Genie Chimique UMR 5503, Departement Procedes Electrochimiques, Universite Paul Sabatier, 31062 Toulouse Cedex 9 (France); Winterton, P. [UFR Langues vivantes, Universite Paul Sabatier, 31062 Toulouse Cedex 9 (France); Taxil, P. [Laboratoire de Genie Chimique UMR 5503, Departement Procedes Electrochimiques, Universite Paul Sabatier, 31062 Toulouse Cedex 9 (France)

    2009-03-05

    This work concerns the preparation of tantalum carbide films on carbon-based substrates using the metalliding process in LiF/NaF molten medium (60-40 mol%), containing tantalum heptafluorotantalate ions TaF{sub 7}{sup 2-}, in the 800-900 deg. C temperature range. The process uses a metalliding cell symbolised as: (+) C, TaC{sub x}/LiF-NaF-K{sub 2}TaF{sub 7}/Ta (-) involving the dissolution of Ta at the anode and the reduction of Ta ions in TaC{sub x} at the cathode. The experiments of this process were performed with different carbon substrates as cathodic material: graphite, glassy carbon and carbon braid. Samples analysis (SEM-EDS and XRD) after metalliding showed the formation of tantalum carbides (TaC and Ta{sub 2}C) at the surface of the substrate at a relatively low temperature. A kinetic study, based on the control of the cathodic reaction by the intermetallic diffusion, allowed the diffusion parameters, such as Ta/C diffusion coefficient, to be determined at several temperatures. Furthermore, the results are shown to be independent of the type of carbon substrate.

  17. Silicon transport in sputter-deposited tantalum layers grown under ion bombardment

    International Nuclear Information System (INIS)

    Gallais, P.; Hantzpergue, J.J.; Remy, J.C.; Roptin, D.

    1988-01-01

    Tantalum was sputter deposited on (111) Si substrate under low-energy ion bombardment in order to study the effects of the ion energy on the silicon transport into the Ta layer. The Si substrate was heated up to 500 0 C during growth. For ion energies up to 180 eV silicon is not transported into tantalum and the growth temperature has no effect. An ion bombardment energy of 280 eV enhances the transport of silicon throughout the tantalum layer. Growth temperatures up to 300 0 C have no effect on the silicon transport which is mainly enhanced by the ion bombardment. For growth temperatures between 300 and 500 0 C, the silicon transport is also enhanced by the thermal diffusion. The experimental depth distribution of silicon is similar to the theoretical depth distribution calculated for the case of an interdiffusion. The ion-enhanced process of silicon transport is characterized by an activation energy of 0.4 eV. Silicon into the layers as-grown at 500 0 C is in both states, amorphous silicide and microcrystalline cubic silicon

  18. Yield strength of molybdenum, tantalum and tungsten at high strain rates and very high temperatures

    International Nuclear Information System (INIS)

    Škoro, G.P.; Bennett, J.R.J.; Edgecock, T.R.; Booth, C.N.

    2012-01-01

    Highlights: ► New experimental data on the yield strength of molybdenum, tantalum and tungsten. ► High strain rate effects at record high temperatures (up to 2700 K). ► Test of the consistency of the Zerilli–Armstrong model at very high temperatures. - Abstract: Recently reported results of the high strain rate, high temperature measurements of the yield strength of tantalum and tungsten have been analyzed along with new experimental results on the yield strength of molybdenum. Thin wires are subjected to high stress by passing a short, fast, high current pulse through a thin wire; the amplitude of the current governs the stress and the repetition rate of the pulses determines the temperature of the wire. The highest temperatures reached in the experiments were 2100 °C (for molybdenum), 2250 °C (for tantalum) and 2450 °C (for tungsten). The strain-rates in the tests were in the range from 500 to 1500 s −1 . The parameters for the constitutive equation developed by Zerilli and Armstrong have been determined from the experimental data and the results have been compared with the data obtained at lower temperatures. An exceptionally good fit is obtained for the deformation of tungsten.

  19. Redox Chemisty of Tantalum Clusters on Silica Characterized by X-ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nemana,S.; Gates, B.

    2006-01-01

    SiO{sub 2}-supported clusters of tantalum were synthesized from adsorbed Ta(CH{sub 2}Ph){sub 5} by treatment in H{sub 2} at 523 K. The surface species were characterized by X-ray absorption spectroscopy (extended X-ray absorption fine structure (EXAFS) spectroscopy and X-ray absorption near edge spectroscopy (XANES)) and ultraviolet-visible spectroscopy. The EXAFS data show that SiOO{sub 2}-supported tantalum clusters were characterized by a Ta-Ta coordination number of approximately 2, consistent with the presence of tritantalum clusters, on average. When these were reduced in H{sub 2} and reoxidized in O{sub 2}, the cluster nuclearity remained essentially unchanged, although reduction and oxidation occurred, respectively, as shown by XANES and UV-vis spectra; in the reoxidation, the tantalum oxidation state change was approximately two electronic charges per tritantalum cluster. The data demonstrate an analogy between the chemistry of group 5 metals on the SiO{sub 2} support and their chemistry in solution, as determined by the group of Cotton.

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

    Science.gov (United States)

    Papp, John F.

    2014-01-01

    The U.S. Geological Survey (USGS) analyzes mineral and metal supply chains to identify and describe major components of mineral and metal material flows from ore extraction, through intermediate forms, to a final product. Supply chain analyses may be used (1) to identify risks to the United States associated with the supply of critical and strategic minerals and metals and (2) to provide greater supply chain transparency so that policymakers have the fact-based information needed to formulate public policy. This fact sheet focuses on the post-mining/pre-consumer-product part of the tantalum supply chain. The USGS National Minerals Information Center (NMIC) has been asked by governmental and non-governmental organizations to provide information about tantalum, tin, tungsten, and gold (collectively known as “3TG minerals”) processing facilities worldwide in response to U.S. legislation aimed at identifying and removing the supply chain links between the trade in these minerals and civil unrest in the Democratic Republic of the Congo and adjacent countries.

  1. Labeling Lanreotide with 125I and 188Re. China

    International Nuclear Information System (INIS)

    Bai Hongsheng

    2000-01-01

    Lanreotide (D-β-Nal-Cys-Try-D-Trp-Lys-Val-Cys-Thr-NH2) is a new somatostatin analogue. It can bind to human somatostatin receptor (hSSTR) subtype 2 through 5 with high affinity and to hSSTR subtype 1 with low affinity. We investigate labeling condition, quality control and stability in vitro of 125 I-Lanreotide and 188 Re-lanreotide respectively. (A) Lanreotide is labeled with 125 I using Chloramine T. The effect of reaction condition (such as reaction time, pH value, Lanreotide amount, quantity of Chloramine T and reaction volume) on labeling yield is investigated in detail. (B) The labeling yield and radiochemical purity (RP) is measured with paper chromatography (PC) and Sep-Pak C 18 Cartridge. For PC method, 125 I-Lanreotide is spotted on the Whatman No.1 paper and developed in the mixture of CH 3 CH 2 CH 2 CH 2 OH and CH 3 CH 2 OH and NH 4 OH (v/v/v=5:2:1), the Rf value of every component in the mobile phase is given in table 1. For Sep-Pak C 18 Cartridge methods each cartridge is washed with 10 ml of ethanol followed by 10 ml of iso-CH 3 CH 2 CH 2 OH solution. Aliquots of 0.1 mI sample is loaded onto the cartridge, unbound peptide (sodium iodine-125) is eluted with 5 ml of 0.5mol/L sodium acetate solution, 125 I-Lanreotide is eluted with 5 mI of 95% aqueous ethanol solution. (C) The stability of 125 I-Lanreotide in vitro is investigated by labeling compound incubating for 48 hours at 37 deg. C in the 0.9% sodium chloride solution and RP is tested by PC at specific time intervals. (D) Lanreotide is labeled directly with 188 Re via the mixture of citrate and tartate using stannous chloride as reduced agent. The influence of reaction conditions such as pH, temperature, amount of stannous chloride, amount of Lanreotide and reaction time on labeling yield is investigated in detail. At the time, the stability in vitro quality control and animal test are evaluated

  2. Half-life measurements in doubly-odd sup(186,188,190)Au nuclei and the 188Hg -> Au decay

    International Nuclear Information System (INIS)

    Abreu, M.C.; Berg, V.; Fransson, K.; Hoeglund, A.; Oms, J.; Porquet, M.G.

    1985-01-01

    A level scheme has been established for 188 Hg -> Au decay which was studied with the online isotope separator ISOCELE. Precise conversion-electron measurements were performed with a semicircular magnetic spectrograph. The half-lives of the 16.0, 82.7 and 114.8 keV levels in 188 Au were measured with a lens electron spectrometer and reduced transition rates were deduced. Similarly the half-lives of the 36.1, 113.9, 227.7, 251.5, 288.0 and 363.6 keV levels in 186 Au and of the 28.9 and 171.5 keV levels in 190 Au were measured. Comparison of the reduced e.m. transition rates shows that a 1 + and a 2 - state have respectively the same structure in sup(186,) sup(188,) sup(190,) 192 Au, the same conclusion holding for the 1 - sub(g.s.) of sup(188,) sup(190,) 192 Au. Additional measurements in 189 , 191 Hg and 185 , 187 Au together with data from the literature enable us to interpret them as a coupling of certain quasiparticle states of neighbouring odd-A nuclei corresponding to oblate shapes. Indications are given that some other negative- and positive-parity states in 188 Au also belong to an oblate system. The nucleus 188 Au appears as the last of a series of doubly-odd gold nuclei where no shape coexistence has, as yet, been observed. (orig.)

  3. Elevated temperature axial and torsional fatigue behavior of Haynes 188

    Science.gov (United States)

    Bonacuse, Peter J.; Kalluri, Sreeramesh

    1992-06-01

    The results of high-temperature axial and torsional low-cycle fatigue experiments performed on Haynes 188, a wrought cobalt-base superalloy, are reported. Fatigue tests were performed at 760 C in air on thin-walled tubular specimens at various ranges under strain control. Data are also presented for coefficient of thermal expansion, elastic modulus, and shear modulus at various temperatures from room to 1000 C, and monotonic and cyclic stress-strain curves in tension and in shear at 760 C. The data set is used to evaluate several multiaxial fatigue life models (most were originally developed for room temperature multiaxial life prediction) including von Mises equivalent strain range (ASME boiler and pressure vessel code), Manson-Halford, Modified Multiaxiality Factor (proposed here), Modified Smith-Watson-Topper, and Fatemi-Socie-Kurath. At von Mises equivalent strain ranges (the torsional strain range divided by the square root of 3, taking the Poisson's ratio to be 0.5), torsionally strained specimens lasted, on average, factors of 2 to 3 times longer than axially strained specimens. The Modified Multiaxiality Factor approach shows promise as a useful method of estimating torsional fatigue life from axial fatigue data at high temperatures. Several difficulties arose with the specimen geometry and extensometry used in these experiments. Cracking at extensometer probe indentations was a problem at smaller strain ranges. Also, as the largest axial and torsional strain range fatigue tests neared completion, a small amount of specimen buckling was observed.

  4. Light Duty Utility Arm deployment in Tank WM-188

    International Nuclear Information System (INIS)

    Patterson, M.

    1999-01-01

    The Light Duty Utility Arm (LDUA) was successfully deployed in Tank WM-188 during February and March of 1999 at the Idaho Nuclear Technology and Engineering Center (INTEC) tank farm at the Idaho National Engineering and Environmental Laboratory. Some equipment problems were identified, but most were indicative of any first time activity. Deployment during cold weather imposed additional equipment risks, but in general, equipment response to the winter conditions was better than expected. Three end effectors were demonstrated during the deployment. All performed as expected, although the limited resolution of the Alternating Current Field Measurement end effector cannot absolutely confirm tank integrity, which is necessary for future tank inspections. Four heel samples were taken with the sampler end effector and a broad spectrum of analyses were performed. A detailed inspection of the tank interior was performed with the High Resolution Stereo Video System end effector. The sample information is proving invaluable to the development of new treatment flowsheets and waste forms. It is expected that the LDUA will be deployed for tank inspections through the next several years to support other Notice of Non-Compliance (NON) Consent Order requirements and several other ongoing initiatives

  5. Light Duty Utility Arm deployment in Tank WM-188

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, M.W.

    1999-12-01

    The Light Duty Utility Arm (LDUA) was successfully deployed in Tank WM-188 during February and March of 1999 at the Idaho Nuclear Technology and Engineering Center (INTEC) tank farm at the Idaho National Engineering and Environmental Laboratory. Some equipment problems were identified, but most were indicative of any first time activity. Deployment during cold weather imposed additional equipment risks, but in general, equipment response to the winter conditions was better than expected. Three end effectors were demonstrated during the deployment. All performed as expected, although the limited resolution of the Alternating Current Field Measurement end effector cannot absolutely confirm tank integrity, which is necessary for future tank inspections. Four heel samples were taken with the sampler end effector and a broad spectrum of analyses were performed. A detailed inspection of the tank interior was performed with the High Resolution Stereo Video System end effector. The sample information is proving invaluable to the development of new treatment flowsheets and waste forms. It is expected that the LDUA will be deployed for tank inspections through the next several years to support other Notice of Non-Compliance (NON) Consent Order requirements and several other ongoing initiatives.

  6. Light Duty Utility Arm Deployment in Tank WM-188

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, Michael W

    2000-01-01

    The Light Duty Utility Arm (LDUA) was successfully deployed in Tank WM-188 during February and March of 1999 at the Idaho Nuclear Technology and Engineering Center (INTEC) tank farm at the Idaho National Engineering and Environmental Laboratory. Some equipment problems were identified, but most were indicative of any first time activity. Deployment during cold weather imposed additional equipment risks, but in general, equipment response to the winter conditions was better than expected. Three end effectors were demonstrated during the deployment. All performed as expected, although the limited resolution of the Alternating Current Field Measurement end effector cannot absolutely confirm tank integrity, which is necessary for future tank inspections. Four heel samples were taken with the sampler end effector and a broad spectrum of analyses were performed. A detailed inspection of the tank interior was performed with the High Resolution Stereo Video System end effector. The sample information is proving invaluable to the development of new treatment flowsheets and waste forms. It is expected that the LDUA will be deployed for tank inspections through the next several years to support other Notice of NonCompliance (NON) Consent Order requirements and several other ongoing initiatives.

  7. 46 CFR 188.10-56 - Pilot boarding equipment and point of access.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Pilot boarding equipment and point of access. 188.10-56... VESSELS GENERAL PROVISIONS Definition of Terms Used in This Subchapter § 188.10-56 Pilot boarding equipment and point of access. (a) Pilot boarding equipment means a pilot ladder, accomodation ladder, pilot...

  8. Dosimetric evaluation of anti-CD20 labelled with 188Re

    International Nuclear Information System (INIS)

    Barrio, Graciela; Osso Junior, Joao A.

    2011-01-01

    Radioimmunotherapy has the potential to deliver lethal radiation energy directly to malignant cells via targeting of radioisotope-conjugated monoclonal antibodies (MAbs) to specific antigens. B-cell lymphoma is a particularly good candidate for radioimmunotherapy because the disease is inherently radiosensitive, malignant cells in the blood, bone marrow, spleen and lymphonodes are accessible, and MAbs have been developed to B-cell surface antigens that do not shed or modulate. Rituximab (RTX), the human IgG1-type chimeric form of the parent murine antibody ibritumomab, is specifically targeted against CD20, a surface antigen expressed by pre-B and mature human B lymphocytes. The use of rhenium-188 from a 188 W/ 188 Re generator system represents an attractive alternative radionuclide for therapy. 188 Re is produced from beta decay of the 188 W parent. In addition to the emission of high-energy electrons (Eβ= 2118 keV), 188 Re also decays with emission of a gamma photon with an energy of 155 keV in 15% abundance. Besides the therapeutic usefulness of 188 Re, the emission of gamma photon is an added advantage since the biodistribution of 188 Re-labeled antibodies can be evaluated in vivo with a gamma camera. Also, rhenium has chemical properties similar to technetium. Thus, both can be conjugated to antibodies using similar chemistry methods. The objective of this work is to prove the usefulness of this radiopharmaceutical based on dosimetric studies, that are also required by the Brazilian Regulatory Agency (ANVISA). (author)

  9. Study of different absorbent materials for the preparation of generator systems of {sup 99}Mo - {sup 99m}Tc and {sup 188}W-{sup 188}Re

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Paula Regina Corain; Osso Junior, Joao Alberto, E-mail: paulinhacorain@usp.b, E-mail: jaosso@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2009-07-01

    Amongst some currently radioisotopes, {sup 99m}Tc and {sup 188}Re present adequate decay properties for use in Nuclear Medicine. In the current times the most diagnosis examinations are performed with {sup 99m}Tc and {sup 188}Re is one radioisotope of potential use in therapy techniques. The objective of this work consists of determining the capacity of some adsorbent materials for retention of molybdenum and tungsten, aiming the optimization of generator systems of {sup 99}Mo-{sup 99m}Tc and {sup 188}W-{sup 188}Re with suitable characteristics for application in Nuclear Medicine. Known amounts, in mass, of molybdenum and tungsten were percolated through different chromatographic columns containing different commercial adsorbent materials such as: PZC (poly-zirconium compound), acid alumina and calcinated alumina used in the routine preparation of {sup 99}Mo-{sup 99m}Tc generators at IPEN. The tungsten ({sup 188}W), as well the PZC used in this project, supplied by Russia and Japan, respectively, through the International Atomic Energy Agency (IAEA) and used without any previous preparation. Also trace amounts of {sup 99}Mo and {sup 188}W were added to the initial solutions and the generators were assembled. The {sup 99}Mo-{sup 99m}Tc generators were then eluted with known volumes of 0.9% NaCl solution every 24 hours whereas the {sup 188}W-{sup 188}Re generators were eluted every 48 hours. The eluted samples were analyzed by Gamma Spectroscopy and later submitted to quality control evaluation. The results showed that the PZC presents superior retention capacity for Mo of 97.50mg Mo/gPZC, higher than in acid and calcinated alumina, however the elution efficiency at lower pHs is not so high. With regards to the experiments carried out with {sup 188}W and alumina, it was verified that the elution efficiency of {sup 188}Re was not reproducible and the retention capacity of W was 90.23mgW/gAl{sub 2}O{sub 3} at pH 7. (author)

  10. Tantalum acetabular augments in one-stage exchange of infected total hip arthroplasty: a case-control study.

    Science.gov (United States)

    Klatte, Till Orla; Kendoff, Daniel; Sabihi, Reza; Kamath, Atul F; Rueger, Johannes M; Gehrke, Thorsten

    2014-07-01

    During the one-stage exchange procedure for periprosthetic joint infection (PJI) after total hip arthroplasty (THA), acetabular defects challenge reconstructive options. Porous tantalum augments are an established tool for addressing acetabular destruction in aseptic cases, but their utility in septic exchange is unknown. This retrospective case-control study presents the initial results of tantalum augmentation during one-stage exchange for PJI. Primary endpoints were rates of re-infection and short-term complications associated with this technique. Study patients had no higher risk of re-infection with equivalent durability at early follow-up with a re-infection rate in both groups of 4%. In conclusion, tantalum augments are a viable option for addressing acetabular defects in one-stage exchange for septic THA. Further study is necessary to assess long-term durability when compared to traditional techniques for acetabular reconstruction. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Study of different adsorbent materials for the preparation of generator systems of 99Mo - 99mTc and 188W-188Re

    International Nuclear Information System (INIS)

    Lopes, Paula Regina Corain

    2009-01-01

    Amongst some existing radioisotopes, 99m Tc and 188 Re present adequate physical chemical properties for use in Nuclear Medicine in the areas of diagnosis and therapy, respectively. Moreover, these radioisotopes can be distributed to medical centers in the form of generator systems of 99 Mo- 99m Tc and 188 W- 188 Re, allowing autonomy and practicity in use. The objective of this work consists of determining the capacity of some adsorbent materials for retention of molibdenium and tungsten, aiming the optimization of generator systems of 99 Mo- 99 mTc and 188 W- 188 Re with suitable characteristics for application in Nuclear Medicine. Known amounts, in mass, of molybdenum (Mo) and tungsten (W) were added to the loading solutions previously prepared, with values of pH adjusted between 1 and 7, and these were then percolated through different devices containing in its interior alumina, resin or poly-zirconium compound also known as PZC. The elutions were carried out within an interval of time of approximately 24 hours for the generator systems of 99 Mo - 99 mTc and 48 hours for the generator systems of 188 W- 188 Re due to the difference between the half-lives of radionuclides involved in the reactions. The eluted samples from both generator systems containing 99m Tc or 188 Re were submitted to quality control tests aiming to evaluate the radionuclidic, radiochemical and chemical purity, but no significant contamination for 99 Mo, 188 W, technetium or rhenium in the colloidal states and zirconium were detected in the eluted solutions and in the solutions extracted with saline solution for any value of pH studied. The commercial alumina cartridges known as Acid Sep Pak were more efficient in retaining the molybdenum in the loading solutions when compared with the others commercial retention devices employed. However, when this comparison extends to the chromatographic alumina columns, the use of acid alumina as adsorbent is more efficient when compared to the Acid Sep

  12. Influence of process parameters on plasma electrolytic surface treatment of tantalum for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Sowa, Maciej, E-mail: maciej.sowa@polsl.pl [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland); Woszczak, Maja; Kazek-Kęsik, Alicja [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland); Dercz, Grzegorz [Institute of Materials Science, University of Silesia, 75 Pułku Piechoty Street 1A, 41-500 Chorzów (Poland); Korotin, Danila M. [M.N. Mikheev Institute of Metal Physics of the Ural Branch of Russian Academy of Sciences, S. Kovalevskoi Street 18, 620990 Yekaterinburg (Russian Federation); Institute of Physics and Technology, Ural Federal University, Mira Street 19, 620002 Yekaterinburg (Russian Federation); Zhidkov, Ivan S. [Institute of Physics and Technology, Ural Federal University, Mira Street 19, 620002 Yekaterinburg (Russian Federation); Kurmaev, Ernst Z. [M.N. Mikheev Institute of Metal Physics of the Ural Branch of Russian Academy of Sciences, S. Kovalevskoi Street 18, 620990 Yekaterinburg (Russian Federation); Institute of Physics and Technology, Ural Federal University, Mira Street 19, 620002 Yekaterinburg (Russian Federation); Cholakh, Seif O. [Institute of Physics and Technology, Ural Federal University, Mira Street 19, 620002 Yekaterinburg (Russian Federation); Basiaga, Marcin [Faculty of Biomedical Engineering, Silesian University of Technology, Gen. de Gaulle’a Street 66, 41-800 Zabrze (Poland); Simka, Wojciech, E-mail: wojciech.simka@polsl.pl [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland)

    2017-06-15

    Highlights: • 2-step plasma electrolytic oxidation (PEO) of tantalum was investigated. • PEO coatings surface composition were reflected by the composition of anodizing baths. • Hydrophobic surfaces were obtained from acetate and formate containing baths. • Bioactive phases were identified. - Abstract: This work aims to quantify the effect of anodization voltage and electrolyte composition used during DC plasma electrolytic oxidation (PEO), operated as a 2-step process, on the surface properties of the resulting oxide coatings on tantalum. The first step consisted of galvanostatic anodization (150 mA cm{sup −2}) of the tantalum workpiece up to several limiting voltages (200, 300, 400 and 500 V). After attaining the limiting voltage, the process was switched to voltage control, which resulted in a gradual decrease of the anodic current density. The anodic treatment was realized in a 0.5 M Ca(H{sub 2}PO{sub 2}){sub 2} solution, which was then modified by the addition of 1.15 M Ca(HCOO){sub 2} as well as 1.15 M and 1.5 M Mg(CH{sub 3}COO){sub 2}. The increasing voltage of anodization led to the formation of thicker coatings, with larger pores and enriched with electrolytes species to a higher extent. The solutions containing HCOO{sup −} and CH{sub 3}COO{sup −} ions caused the formation of coatings which were slightly hydrophobic (high contact angle). In the case of the samples anodized up to 500 V, scattered crystalline deposits were observed. Bioactive phases, such as hydroxyapatite, were detected in the treated oxide coatings by XRD and XPS.

  13. Synthesis of tantalum carbide and nitride nanoparticles using a reactive mesoporous template for electrochemical hydrogen evolution

    KAUST Repository

    Alhajri, Nawal Saad; Yoshida, Hiroshi; Anjum, Dalaver H.; Garcia Esparza, Angel T.; Kubota, Jun; Domen, Kazunari; Takanabe, Kazuhiro

    2013-01-01

    Tantalum carbide and nitride nanocrystals were prepared through the reaction of a tantalum precursor with mesoporous graphitic (mpg)-C 3N4. The effects of the reaction temperature, the ratio of the Ta precursor to the reactive template (mpg-C3N4), and the selection of the carrier gas (Ar, N2 and NH3) on the resultant crystal phases and structures were investigated. The produced samples were characterized using powder X-ray diffraction (XRD), CHN elemental analyses, thermogravimetric analyses (TGA), nitrogen sorption, a temperature-programmed reaction with mass spectroscopy (MS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The results indicate that the different tantalum phases with cubic structure, TaN, Ta2CN, and TaC, can be formed under a flow of nitrogen when formed at different temperatures. The Ta3N5 phase with a Ta5+ oxidation state was solely obtained at 1023 K under a flow of ammonia, which gasified the C 3N4 template and was confirmed by detecting the decomposed gaseous products via MS. Significantly, the formation of TaC, Ta2CN, and TaN can be controlled by altering the weight ratio of the C 3N4 template relative to the Ta precursor at 1573 K under a flow of nitrogen. The high C3N4/Ta precursor ratio generally resulted in high carbide content rather than a nitride one, consistent with the role of mpg-C3N4 as a carbon source. Electrochemical measurements revealed that the synthesized nanomaterials were consistently able to produce hydrogen under acidic conditions (pH 1). The obtained Tafel slope indicates that the rate-determining step is the Volmer discharge step, which is consistent with adsorbed hydrogen being weakly bound to the surface during electrocatalysis. © 2013 The Royal Society of Chemistry.

  14. Environment sensitive embedding energies of impurities, and grain boundary stability in tantalum

    International Nuclear Information System (INIS)

    Krasko, G.L.

    1996-01-01

    Metalloid impurities have a very low solubility in tantalum, and therefore prefer to segregate at the grain boundaries (GBs). In order to analyze the energetics of the impurities on the tantalum GB, the LMTO calculations were performed on a simple 8-atom supercell emulating a typical (capped trigonal prism) GB environment. The so-called environment-sensitive embedding energies were calculated for hydrogen, boron, carbon, nitrogen, oxygen, phosphorus, and sulphur, as a function of the electron charge density due to the host atoms at the impurity site. The calculations showed that, at the electron density typical of a GB, carbon has the lowest energy (followed by Nitrogen and Boron) and thus would compete with the other impurities for the site on the GB, tending to displace them from the GB. The above energies were then used in a modified Finnis-Sinclair embedded atom approach for calculating the cohesive energies and the equilibrium interplanar distances in the vicinity of a (111) Σ3 tilt GB plane, both for the clean GB and that with an impurity. These distances were found to oscillate, returning to the value corresponding to the equilibrium spacing between (111) planes in bulk BCC tantalum by the 10th--12th plane off the GB. Carbon, nitrogen and boron somewhat dampen the deformation wave (making the oscillations less than in the clean GB), while oxygen, phosphorus and sulphur result in an increase of the oscillations. The cohesive energies follow the same trend, the GB with carbon being the most stable. Thus, carbon, nitrogen and boron may be thought of as being cohesion enhancers, while oxygen, phosphorus and sulphur result in decohesion effects

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

    Science.gov (United States)

    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

  16. XPS and GDOES Characterization of Porous Coating Enriched with Copper and Calcium Obtained on Tantalum via Plasma Electrolytic Oxidation

    Directory of Open Access Journals (Sweden)

    Krzysztof Rokosz

    2016-01-01

    Full Text Available XPS and GDOES characterizations of porous coatings on tantalum after Plasma Electrolytic Oxidation (PEO at 450 V for 3 minutes in electrolyte containing concentrated (85% phosphoric acid with calcium nitrate and copper (II nitrate are described. Based on the obtained data, it may be concluded that the PEO coating consists of tantalum (Ta5+, calcium (Ca2+, copper (Cu2+  and Cu+, and phosphates (PO43-. It has to be pointed out that copper and calcium are distributed throughout the volume. The authors also propose a new model of PEO, based on the derivative of GDOES signals with sputtering time.

  17. Therapeutic applications of Rhenium-188 in nuclear medicine and oncology - Current status and expected future perspectives

    International Nuclear Information System (INIS)

    Knapp, F. F. Jr.

    2005-01-01

    Full text: The increasing use of unsealed radioactive targeting agents for cancer treatment requires the routine availability of cost-effective radioisotopes. Rhenium-188 (Re-188; half-life 16.9 hours) is a high-energy beta-emitter (E max 2.12 MeV), readily available no- max carrier-added from the alumina-based tungsten-188 (half-life 69 days)/rhenium-188 generator system. Rhenium-188 also emits a 155 keV (15%) gamma photon, permitting gamma camera imaging for biodistribution and dosimetry evaluation. The versatile chemistry of rhenium allows attachment to a wide variety of targeting molecules for Re-188 applications in nuclear oncology for both palliative metastatic treatment and targeted tumor therapy - radionuclide synovectomy, and coronary restenosis therapy. The long parent half-life and consistent performance provide an indefinite generator shelf-life of several months with high Re-188 elution yields (75-85 %) and consistently low W-188 parent breakthrough ( -6 ). Simple post-elution concentration methods have been developed which provide very high specific volume solution of Re-188 for radiolabeling (> 700 mCi/mL saline/1 Ci generator). Over 60 physician-sponsored clinical trials are currently in progress worldwide with applications in nuclear medicine, nuclear oncology and interventional cardiology. A variety of Re-188-labeled therapeutic radiopharmaceuticals and devices are being developed for clinical trials currently in progress for treatment of both benign and metastatic oncological disorders. Palliation of metastatic bone pain with Re-188-HEDP - prepared from a simple 'kit' - has been demonstrated as a cost-effective alternative to similar agents. Recent studies have in fact demonstrated the enhancement of progression-free interval and survival time by repeated Re-188-HEDP injections to patients with metastatic disease from prostate cancer. The use of the Re-188-labeled antiNCA95 (CD66) antibody in conjunction with external beam irradiation is an

  18. Safety and Efficacy of 188-Rhenium-Labeled Antibody to Melanin in Patients with Metastatic Melanoma

    Directory of Open Access Journals (Sweden)

    M. Klein

    2013-01-01

    Full Text Available There is a need for effective “broad spectrum” therapies for metastatic melanoma which would be suitable for all patients. The objectives of Phase Ia/Ib studies were to evaluate the safety, pharmacokinetics, dosimetry, and antitumor activity of 188Re-6D2, a 188-Rhenium-labeled antibody to melanin. Stage IIIC/IV metastatic melanoma (MM patients who failed standard therapies were enrolled in both studies. In Phase Ia, 10 mCi 188Re-6D2 were given while unlabeled antibody preload was escalated. In Phase Ib, the dose of 188Re-6D2 was escalated to 54 mCi. SPECT/CT revealed 188Re-6D2 uptake in melanoma metastases. The mean effective half-life of 188Re-6D2 was 12.4 h. Transient HAMA was observed in 9 patients. Six patients met the RECIST criteria for stable disease at 6 weeks. Two patients had durable disease stabilization for 14 weeks and one for 22 weeks. Median overall survival was 13 months with no dose-limiting toxicities. The data demonstrate that 188Re-6D2 was well tolerated, localized in melanoma metastases, and had antitumor activity, thus warranting its further investigation in patients with metastatic melanoma.

  19. Effect of second spherical cations on ionic equilibrium displacement of pentavalent tantalum complexes in fluoride melts

    International Nuclear Information System (INIS)

    Agulyanskij, A.I.

    1980-01-01

    The melts of the systems M 2 TaF 7 -MF (where M-Na, K, Rb) and CsTaF 4 -CsF are investigated at 850 deg using the method of IR spectroscopy. It is shown that ion equilibrium TaF 7 2- reversible TaF 6 - +F - is shifted to the left when sodium to cesium electrolytes are used. The change of vibrational frequencies of TaF 7 2- and TaF 6 - ions is explained by the change of the ratio of ion and covalent contributions to the interaction energy in the inner and outer spheres of coordination in pentavalent tantalum

  20. Study the effect of nitrogen flow rate on tribological properties of tantalum nitride based coatings

    Science.gov (United States)

    Chauhan, Dharmesh B.; Chauhan, Kamlesh V.; Sonera, Akshay L.; Makwana, Nishant S.; Dave, Divyeshkumar P.; Rawal, Sushant K.

    2018-05-01

    Tantalum Nitride (TaN) based coatings are well-known for their high temperature stability and chemical inertness. We have studied the effect of nitrogen flow rate variation on the structural and tribological properties of TaN based coating deposited by RF magnetron sputtering process. The nitrogen flow rate was varied from 5 to 30 sccm. X-ray diffractometer (XRD) and Atomic Force Microscopy (AFM) were used to determine structure and surface topography of coating. Pin on disc tribometer was used to determine tribological properties of coating. TaN coated brass and mild steel substrates shows higher wear resistance compared to uncoated substrates of brass and mild steel.

  1. Reduction of a dimeric tantalum(III) compound in acetonitrile solution by pulse radiolysis

    International Nuclear Information System (INIS)

    Koulkes-Pujo, A.-M.; Le Motais, B.; Hubert-Pfalzgraf, L.G.

    1986-01-01

    The reduction of the compound [Ta 2 Cl 6 (4Me-py) 4 ] (4Me-py 4-methylpyridine), having a metal-metal double bond, has been achieved by pulse radiolysis in dry oxygen-free acetonitrile. The reduction occurs by CH 3 CN - which leads to a transient species assigned to a tantalum dimer in a 2.5 oxidation state. The spectrum of this species has been established. It decays by a first-order process to give a new transient species which in turn decays more slowly by a second-order reaction. (author)

  2. Some organoperoxo complexes of antimony, niobium and tantalum and their oxidation properties

    International Nuclear Information System (INIS)

    Tarafder, M.T.H.

    1999-05-01

    Several novel organoperoxo complexes of Nb(V), Ta(V) and Sb(V) have been synthesized and characterized. The complexes have the compositions [M(O 2 ) 2 L Cl] and [M(O 2 ) 2 L'] [L = monodentate and bidentate, neutral ligand; L' = bidentate, uninegative ligand]. These complexes are very reactive to both organic and inorganic substrates. Niobium and tantalum complexes were found to oxidize phosphines and arsines to their oxides. These also oxidize olefins to epoxides under stoichiometric conditions while under catalytic conditions, ring opening of the epoxides occur producing α-hydroxyketone when the substrate is trans-stilbene. The antimony complexes are decidedly inert towards oxidation. (author)

  3. Leakage Current Degradation Due to Ion Drift and Diffusion in Tantalum and Niobium Oxide Capacitors

    Directory of Open Access Journals (Sweden)

    Kuparowitz Martin

    2017-06-01

    Full Text Available High temperature and high electric field applications in tantalum and niobium capacitors are limited by the mechanism of ion migration and field crystallization in a tantalum or niobium pentoxide insulating layer. The study of leakage current (DCL variation in time as a result of increasing temperature and electric field might provide information about the physical mechanism of degradation. The experiments were performed on tantalum and niobium oxide capacitors at temperatures of about 125°C and applied voltages ranging up to rated voltages of 35 V and 16 V for tantalum and niobium oxide capacitors, respectively. Homogeneous distribution of oxygen vacancies acting as positive ions within the pentoxide layer was assumed before the experiments. DCL vs. time characteristics at a fixed temperature have several phases. At the beginning of ageing the DCL increases exponentially with time. In this period ions in the insulating layer are being moved in the electric field by drift only. Due to that the concentration of ions near the cathode increases producing a positively charged region near the cathode. The electric field near the cathode increases and the potential barrier between the cathode and insulating layer decreases which results in increasing DCL. However, redistribution of positive ions in the insulator layer leads to creation of a ion concentration gradient which results in a gradual increase of the ion diffusion current in the direction opposite to the ion drift current component. The equilibrium between the two for a given temperature and electric field results in saturation of the leakage current value. DCL vs. time characteristics are described by the exponential stretched law. We found that during the initial part of ageing an exponent n = 1 applies. That corresponds to the ion drift motion only. After long-time application of the electric field at a high temperature the DCL vs. time characteristics are described by the exponential

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  6. Tantalum films with well-controlled roughness grown by oblique incidence deposition

    Science.gov (United States)

    Rechendorff, K.; Hovgaard, M. B.; Chevallier, J.; Foss, M.; Besenbacher, F.

    2005-08-01

    We have investigated how tantalum films with well-controlled surface roughness can be grown by e-gun evaporation with oblique angle of incidence between the evaporation flux and the surface normal. Due to a more pronounced shadowing effect the root-mean-square roughness increases from about 2 to 33 nm as grazing incidence is approached. The exponent, characterizing the scaling of the root-mean-square roughness with length scale (α), varies from 0.75 to 0.93, and a clear correlation is found between the angle of incidence and root-mean-square roughness.

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

    Science.gov (United States)

    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. Pre-equilibrium decay process in alpha particle induced reactions on thulium and tantalum

    International Nuclear Information System (INIS)

    Mohan, Rao, A.V.; Chintalapudi, S.N.

    1994-01-01

    Alpha particle induced reactions on the target elements Thulium and Tantalum were investigated upto 60 MeV using stacked foil activation technique and Ge(Li) gamma ray spectroscopy method. Excitation functions for six reactions of 169 Tm(α,xn); x=1-4 and 181 Ta(α,xn); x=2,4 were studied. The experimental results were compared with the updated version of Hybrid model (ALICE/90) using initial exciton configuration n 0 =4(4pOh). A general agreement was found for all the reactions with this option. (author)

  9. Pre-equilibrium decay process in alpha particle induced reactions on thulium and tantalum

    Energy Technology Data Exchange (ETDEWEB)

    Mohan, Rao, A.V.; Chintalapudi, S.N. (Inter Univ. Consortium for Dept. of atomic Energy Facilities, Calcutta (India))

    1994-01-01

    Alpha particle induced reactions on the target elements Thulium and Tantalum were investigated upto 60 MeV using stacked foil activation technique and Ge(Li) gamma ray spectroscopy method. Excitation functions for six reactions of [sup 169]Tm([alpha],xn); x=1-4 and [sup 181]Ta([alpha],xn); x=2,4 were studied. The experimental results were compared with the updated version of Hybrid model (ALICE/90) using initial exciton configuration n[sub 0]=4(4pOh). A general agreement was found for all the reactions with this option. (author).

  10. Graphene-induced strengthening in spark plasma sintered tantalum carbide–nanotube composite

    International Nuclear Information System (INIS)

    Lahiri, Debrupa; Khaleghi, Evan; Bakshi, Srinivasa Rao; Li, Wei; Olevsky, Eugene A.; Agarwal, Arvind

    2013-01-01

    Transverse rupture strength of spark plasma sintered tantalum carbide (TaC) composites reinforced with long and short carbon nanotubes (CNTs) is reported. The rupture strength depends on the transformation behavior of the CNTs during spark plasma sintering, which is dependent on their length. The TaC composite with short nanotubes shows the highest specific rupture strength. Shorter CNTs transform into multi-layered graphene sheets between TaC grains, whereas long ones retain the tubular structure. Two-dimensionsal graphene platelets offer higher resistance to pull-out, resulting in delayed fracture and higher strength.

  11. Linkage of molecular units in the chemistry of niobium and tantalum cluster halides

    International Nuclear Information System (INIS)

    Perrin, C.; Sergent, M.

    1991-01-01

    In low valency niobium and tantalum halides, interunit linkages are observed between the (Me 6 X 12 )X 6 units. They are insulators and interesting magnetic properties are observed, due to the intrinsic potential magnetism of the Me 6 cluster and depending on the inserted cations, for instance rare earths in MM'Nb 6 Cl 18 (M = monovalent cation, M' = rare earth). Of special interest are the niobium iodides which exhibit (Me 6 X 8 )X 6 units, an exception in the niobium chemistry; interesting properties have been reported for some of these iodides

  12. Tantalum-178 - a short-lived nuclide for nuclear medicine: development of a potential generator system

    International Nuclear Information System (INIS)

    Neirinckx, R.D.; Jones, A.G.; Davis, M.A.; Harris, G.I.; Holman, B.L.

    1978-01-01

    We describe a chemical separation that may form the basis of a generator system for the short-lived radionuclide Ta-178 (T/sub 1/2/ = 9 min). The parent nuclide W-178 (T/sub 1/2/ = 21.7 days) is loaded on an anion-exchange column and the daughter eluted with a mixture of dilute hydrochloric acid and hydrogen peroxide. The yields of tantalum and the breakthrough of the tungsten parent as a function of the eluting conditions are discussed, and preliminary animal distribution data are presented for various treatments of the eluant solution

  13. Influence of tantalum underlayer on magnetization dynamics in Ni81Fe19 films

    International Nuclear Information System (INIS)

    Kwon, Jae Hyun; Deorani, Praveen; Yoon, Jungbum; Yang, Hyunsoo; Hayashi, Masamitsu

    2015-01-01

    The effect of tantalum (Ta) underlayer is investigated in Ni 81 Fe 19 thin films for magnetization dynamics. The damping parameters extracted from spin wave measurements increase systematically with increasing Ta thickness, whereas the damping parameters from ferromagnetic resonance measurements are found to be weakly dependent on the Ta thickness. The difference is attributed to propagating properties of spin wave and short spin diffusion length in Ta. The group velocity of spin waves is found to be constant for different Ta thicknesses, and nonreciprocity of spin waves is not affected by the Ta thickness. The experimental observations are supported by micromagnetic simulations

  14. Compartmental and dosimetric studies of anti-CD20 labeled with 188Re

    International Nuclear Information System (INIS)

    Barrio Kuramoto Graciela; Mie Nakamura Matsuda Margareth; Osso Joao Jr, Alberto

    2016-01-01

    Radioimmunotherapy has the potential to deliver lethal radiation energy directly to malignant cells via targeting of radioisotope-conjugated monoclonal antibodies (MAbs) to specific antigens. Rituximab (RTX) is specifically targeted against CD20, a surface antigen expressed by B-lymphocytes. The use of 188 Re from a 188 W/ 188 Re generator system represents an alternative radionuclide for therapy. Rhenium has chemical properties similar to technetium and both can be conjugated to antibodies using similar chemistry methods. The objective of this work is to prove the usefulness of this radiopharmaceutical based on dosimetric and pharmacokinetic studies that are also required by the Brazilian Regulatory Agency. (author)

  15. Microendoscopic lumbar discectomy: Technique and results of 188 cases

    Directory of Open Access Journals (Sweden)

    Arvind G Kulkarni

    2014-01-01

    Full Text Available Background: Discectomy performed open or with an operating microscope remains the standard surgical management. Tubular retractor system is being increasingly used. Potential benefits include less muscle and local damage, better cosmesis, decreased pain and operative time and faster recovery after surgery. We have evaluated the outcome of micro endoscopic discectomy (MED utilizing tubular retractors in terms of safety and efficacy of the technique. Materials and Methods: 188 consecutive patients who underwent surgery for herniated disc using the tubular retractors between April 2007 and April 2012 are reported. All patients had a preoperative MRI (Magnetic Resonance Imaging and were operated by a single surgeon with the METRx system (Medtronic, Sofamor-Danek, Memphis, TN using 18 and 16 mm ports. All patients were mobilized as soon as pain subsided and discharged within 24-48 hours post surgery. The results were evaluated by using VAS (Visual Analog Scale 0-5 for back and leg pain and ODI (Oswestry Disability Index. Patients were followed up at intervals of 1 week, 6 weeks, 3 months, 6 months, 12 months and 2 years. Results: The mean age of patients was 46 years (range 16-78 years and the sex ratio was 1.5 males to 1 female. The mean followup was 22 months (range 8-69 months. The mean VAS scale for leg pain improved from 4.14 to 0.76 ( P < 0.05 and the mean VAS scale for back pain improved from 4.1 to 0.9 ( P < 0.05. The mean ODI changed from 59.5 to 22.6 ( P < 0.05. The mean operative time per level was about 50 minutes (range 20-90 minutes. Dural punctures occurred in 11 (5% cases. Average blood loss was 30 ml (range 10-500 ml. A wrong level was identified and later corrected in a case of revision discectomy. Four patients with residual disc-herniation had revision MED and three patients with recurrent disc herniation later underwent fusion. One patient had wound infection which needed a debridement. Conclusion: MED for herniated discs

  16. Country Report: Rep. of Korea. {sup 188}re-Tricabonyl Labeling Strategy: Preparation of 1{sup 188}Re(I) Tricarbonyl Precursor [{sup 188}Re(OH{sub 2}){sub 3}(CO){sub 3}]+ for the Labeling of Biomolecules

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sang Hyun [Radiation Research Division for Biotechnology, Korea Atomic Energy Research Institute (Korea, Republic of)

    2010-07-01

    The {sup 99m}Tc(I) and {sup 188}Re(I) tricarbonyl precursors [M(OH{sub 2}){sub 3}(CO){sub 3}]{sup +} have been shown to be excellent starting materials for the synthesis of {sup 99m}Tc(I) and {sup 188}Re(I) tricarbonyl complexes as well as radiolabeling of target-specific biomolecules.{sup 1-8} Recently, a user-friendly kit formulation (IsoLink{sup TM}) was developed using potassium boranocarbonate, K{sub 2}[BH{sub 3}CO{sub 2}], for preparation of the {sup 99m}Tc precursor complex. This solid reagent serves both as a source of carbon monoxide and a reducing agent for technetium. It was also used by Schibli and coworkers for the preparation of the corresponding {sup 188}Re precursor complex (“Schibili’s kit”).{sup 9} This approach involved the reduction of [{sup 188}Re]perrhenate eluate (1 ml) in neutral solution with 3 mg K{sub 2}[BH{sub 3}CO{sub 2}] and 5 mg BH3≅NH3 by incubation at 60 °C for 15 min. The amounts of reducing agents and acid (concentrated phosphoric acid) were carefully balanced not only to avoid fast hydrolysis of the boranes, but also to maintain a sufficiently low pH to stabilize reduced rhenium intermediates. The preparations resulted in yields >85 % of the desired precursor complex. In addition, perrhenate (7±3 %), colloidal {sup 188}ReO{sub 2} (<5 %), and a byproduct of unknown composition were also detected. To increase the yields even further, we evaluated the recently described borohydride exchange resin (BER) as an additional reducing agent and an anion scavengers.

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

    Science.gov (United States)

    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.

  18. Structural changes in the human vas deferens after tantalum clip occlusion and conventional vasectomy.

    Science.gov (United States)

    Kothari, L K; Gupta, A S

    1978-02-01

    In 15 human subjects, the vasa deferentia were occluded by applying two tantalum clips on one side and by conventional vasectomy with silk ligatures on the other. After 2 weeks, the occluded segments were recovered for histopathologic examination of serial sections. Obstructing the seminal tract did not, as such, produce any significant change in the vas: the distal and proximal segments appeared to be essentially similar and normal. At the actual site of occlusion, however, tantalum clips produced marked flattening of the tube, complete loss of lining epithelium, distortion of the muscular lamellae, and areas of hemorrhage. The lumen was converted into a narrow slit. Under the ligatures, the damage was largely confined to denudation of the mucosal epithelium. The mucosa of the intersegment left unexcised between two clips showed hyalinization, invasion by macrophages, and degeneration of the epithelium. The changes under the clips suggest that, although clip occlusion may offer several advantages, sterility cannot be reversed merely by removing the clips. The mechanisms of these changes, different in the case of clips and ligatures, are discussed and some possible long-term consequences are considered.

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

    Science.gov (United States)

    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.

  20. Structural and dielectric characterization of sputtered Tantalum Titanium Oxide thin films for high temperature capacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Rouahi, A., E-mail: rouahi_ahlem@yahoo.fr [Univ. Grenoble Alpes, G2Elab, F-38000 (France); Laboratoire Matériaux Organisation et Propriétés (LMOP), Université de Tunis El Manar, 2092 Tunis (Tunisia); Challali, F. [Laboratoire des Sciences des Procédés et des Matériaux (LSPM)-CNRS-UPR3407, Université Paris13, 99 Avenue Jean-Baptiste Clément, 93430, Villetaneuse (France); Dakhlaoui, I. [Laboratoire Matériaux Organisation et Propriétés (LMOP), Université de Tunis El Manar, 2092 Tunis (Tunisia); Vallée, C. [CNRS, LTM, CEA-LETI, F-38000 Grenoble (France); Salimy, S. [Institut des Matériaux Jean Rouxel (IMN) UMR CNRS 6502, Université de Nantes, 2, rue de la Houssinière, B.P. 32229, 44322, Nantes, Cedex 3 (France); Jomni, F.; Yangui, B. [Laboratoire Matériaux Organisation et Propriétés (LMOP), Université de Tunis El Manar, 2092 Tunis (Tunisia); Besland, M.P.; Goullet, A. [Institut des Matériaux Jean Rouxel (IMN) UMR CNRS 6502, Université de Nantes, 2, rue de la Houssinière, B.P. 32229, 44322, Nantes, Cedex 3 (France); Sylvestre, A. [Univ. Grenoble Alpes, G2Elab, F-38000 (France)

    2016-05-01

    In this study, the dielectric properties of metal-oxide-metal capacitors based on Tantalum Titanium Oxide (TiTaO) thin films deposited by reactive magnetron sputtering on aluminum bottom electrode are investigated. The structure of the films was characterized by Atomic Force Microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The dielectric properties of TiTaO thin films were studied by complex impedance spectroscopy over a wide frequency range (10{sup -2} - to 10{sup 5} Hz) and temperatures in -50 °C to 325 °C range. The contributions of different phases, phases’ boundaries and conductivity effect were highlighted by Cole – Cole diagram (ε” versus ε’). Two relaxation processes have been identified in the electric modulus plot. A first relaxation process appears at low temperature with activation energy of 0.37 eV and it is related to the motion of Ti{sup 4+} (Skanavi’s model). A second relaxation process at high temperature is related to Maxwell-Wagner-Sillars relaxation with activation energy of 0.41 eV. - Highlights: • Titanium Tantalum Oxide thin films are grown on Aluminum substrate. • The existence of phases was confirmed by X-ray photoelectron spectroscopy. • Conductivity effect appears in Cole-Cole plot. • At low temperatures, a relaxation phenomenon obeys to Skanavi’s model. • Maxwell-Wagner-Sillars polarization is processed at high temperatures.

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

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Heng-Li [School of Dentistry, China Medical University, Taichung 404, Taiwan (China); Chang, Yin-Yu, E-mail: yinyu@mail2000.com.tw; Chen, Hung-Jui; Chou, Yu-Kai [Department of Mechanical and Computer-Aided Engineering, National Formosa University, Yunlin 632, Taiwan (China); Lai, Chih-Ho [School of Medicine, China Medical University, Taichung 404, Taiwan (China); Chen, Michael Y. C. [Division of Oral and Maxillofacial Surgery, China Medical University Hospital, Taichung 404, Taiwan (China)

    2014-03-15

    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) on 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.

  2. Electrochemical Capacitors Based on Aligned Carbon Nanotubes Directly Synthesized on Tantalum Substrates

    International Nuclear Information System (INIS)

    Kim, Byung Woo; Chung, Hae Geun; Kim, Woong; Min, Byoung Koun; Kim, Hong Gon

    2010-01-01

    We demonstrate that vertically aligned carbon nanotubes can be synthesized directly on tantalum substrate via waterassisted chemical vapor deposition and evaluate their properties as electrochemical capacitors. The mean diameter of the carbon nanotubes was 7.1 ± 1.5 nm, and 70% of them had double walls. The intensity ratio of G-band to D-band in Raman spectra was as high as 5, indicating good quality of the carbon nanotubes. Owing to the alignment and low equivalent series resistance, the carbon nanotube based supercapacitors showed good rate performance. Rectangular shape of cyclic voltammogram was maintained even at the scan rate of > 1 V/s in 1 M sulfuric acid aqueous solution. Specific capacitance was well-retained (∼94%) even when the discharging current density dramatically increased up to 145 A/g. Consequently, specific power as high as 60 kW/kg was obtained from as-grown carbon nanotubes in aqueous solution. Maximum specific energy of ∼20 Wh/kg was obtained when carbon nanotubes were electrochemically oxidized and operated in organic solution. Demonstration of direct synthesis of carbon nanotubes on tantalum current collectors and their applications as supercapacitors could be an invaluable basis for fabrication of high performance carbon nanotube supercapacitors

  3. M551 metals melting experiment. [space manufacturing of aluminum alloys, tantalum alloys, stainless steels

    Science.gov (United States)

    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.

  4. Characteristics of laser produced plasmas of hafnium and tantalum in the 1-7 nm region

    Science.gov (United States)

    Li, Bowen; Otsuka, Takamitsu; Sokell, Emma; Dunne, Padraig; O'Sullivan, Gerry; Hara, Hiroyuki; Arai, Goki; Tamura, Toshiki; Ono, Yuichi; Dinh, Thanh-Hung; Higashiguchi, Takeshi

    2017-11-01

    Soft X-ray (SXR) spectra from hafnium and tantalum laser produced plasmas were recorded in the 1-7 nm region using two Nd:YAG lasers with pulse lengths of 170 ps and 10 ns, respectively, operating at a range of power densities. The maximum focused peak power density was 2. 3 × 1014 W cm-2 for 170 ps pulses and 1. 8 × 1012 W cm-2 for 10 ns pulses, respectively. Two intense quasicontinuous intensity bands resulting from n = 4 - n = 4 and n = 4 - n = 5 unresolved transition arrays (UTAs) dominate both sets of experimental spectra. Comparison with calculations performed with the Cowan suite of atomic structure codes as well as consideration of previous experimental and theoretical results aided identification of the most prominent features in the spectra. For the 10 ns spectrum, the highest ion stage that could be identified from the n = 4 - n = 5 arrays were lower than silver-like Hf25+ and Ta26+ (which has a 4 d 104 f ground configuration) indicating that the plasma temperature attained was too low to produce ions with an outermost 4 d subshell, while for the 170 ps plasmas the presence of significantly higher stages was deduced and lines due to 4 d-5 p transitions were clearly evident. Furthermore, we show an enhancement of emission from tantalum using dual laser irradiation, and the effect of pre-pulse durations and delay times between two pulses are demonstrated.

  5. Mid-term results of total knee arthroplasty with a porous tantalum monoblock tibial component.

    Science.gov (United States)

    Hayakawa, Kazue; Date, Hideki; Tsujimura, Shunzo; Nojiri, Sho; Yamada, Harumoto; Nakagawa, Kenji

    2014-01-01

    The objectives of the present study were to assess the mid-term results of cementless total knee arthroplasty (TKA) with the porous tantalum monoblock tibial component and to examine the time course of bone changes on plain radiographs. The subjects were 32 patients, 29 patients were available for follow-up. We investigated the mid-term results of TKA after a mean follow-up period of 7 years and 8 months. We also examined changes of the bone over time on plain radiographs. The Knee Society Clinical Rating scores showed significant improvement. Bone changes around the tibial component were as follows: new bone formation and longitudinal trabecular thickening in 41.4% (Type A), only longitudinal trabecular thickening in 41.4% (Type B), and no changes in 17.2% (Type C). Type A and B changes were more frequent in patients with osteoarthritis, whereas Type C was only seen in patients with rheumatoid arthritis. Three knees had an initial gap, but this disappeared in all cases, and no new radiolucent lines were detected. Stress shielding was observed in seven knees (21.9%), but there was no implant loosening related to it. When we examined the relationship between the mechanical axis and the locations of the tips of the tibial pegs in patients with or without stress shielding, no significant differences were found. The results of mid-term follow-up have demonstrated favorable bone ingrowth, suggesting that porous tantalum is a promising material for cementless TKA. © 2013.

  6. Effect of strain rate and dislocation density on the twinning behavior in tantalum

    Energy Technology Data Exchange (ETDEWEB)

    Florando, Jeffrey N., E-mail: florando1@llnl.gov; Swift, Damian C.; Barton, Nathan R.; McNaney, James M.; Kumar, Mukul [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550 (United States); El-Dasher, Bassem S. [TerraPower LLC, Bellevue, WA 98005 (United States); Chen, Changqiang [Materials Research Laboratory, University of Illinois at Urbana Champaign, Urbana, IL 61801 (United States); Ramesh, K. T.; Hemker, Kevin J. [Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218 (United States)

    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 given 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.

  7. Measurement of the production of charged pions by protons on a tantalum target

    CERN Document Server

    Catanesi, M.G.; Edgecock, R.; Ellis, Malcolm; Robbins, S.; Soler, F.J.P.; Gossling, C.; Bunyatov, S.; Krasnoperov, A.; Popov, B.; Serdiouk, V.; Tereschenko, V.; Di Capua, E.; Vidal-Sitjed, G.; Artamonov, A.; Arce, P.; Giani, S.; Gilardoni, S.; Gorbunov, P.; Grant, A.; Grossheim, A.; Gruber, P.; Ivanchenko, V.; Kayis-Topaksu, A.; Panman, J.; Papadopoulos, I.; Pasternak, J.; Tcherniaev, E.; Tsukerman, I.; Veenhof, R.; Wiebusch, C.; Zucchelli, P.; Blondel, A.; Borghi, S.; Campanelli, M.; Morone, M.C.; Prior, G.; Schroeter, R.; Engel, R.; Meurer, C.; Kato, I.; Gastaldi, U.; Mills, G.B.; Graulich, J.S.; Gregoire, G.; Bonesini, M.; De Min, A.; Ferri, F.; Paganoni, M.; Paleari, F.; Kirsanov, M.; Bagulya, A.; Grichine, V.; Polukhina, N.; Palladino, V.; Coney, L.; Schmitz, D.; Barr, G.; De Santo, A.; Pattison, C.; Zuber, K.; Bobisut, F.; Gibin, D.; Guglielmi, A.; Mezzetto, M.; Dumarchez, J.; Vannucci, F.; Dore, U.; Orestano, D.; Pastore, F.; Tonazzo, A.; Tortora, L.; Booth, C.; Buttar, C.; Hodgson, P.; Howlett, L.; Bogomilov, M.; Chizhov, M.; Kolev, D.; Tsenov, R.; Apollonio, M.; Chimenti, P.; Giannini, G.; Santin, G.; Burguet-Castell, J.; Cervera-Villanueva, A.; Gomez-Cadenas, J.J.; Martin-Albo, J.; Novella, P.; Sorel, M.; Tornero, A.

    2007-01-01

    A measurement of the double-differential cross-section for the production of charged pions in proton--tantalum collisions emitted at large angles from the incoming beam direction is presented. The data were taken in 2002 with the HARP detector in the T9 beam line of the CERN PS. The pions were produced by proton beams in a momentum range from 3 \\GeVc to 12 \\GeVc hitting a tantalum target with a thickness of 5% of a nuclear interaction length. The angular and momentum range covered by the experiment ($100 \\MeVc \\le p < 800 \\MeVc$ and $0.35 \\rad \\le \\theta <2.15 \\rad$) is of particular importance for the design of a neutrino factory. The produced particles were detected using a small-radius cylindrical time projection chamber (TPC) placed in a solenoidal magnet. Track recognition, momentum determination and particle identification were all performed based on the measurements made with the TPC. An elaborate system of detectors in the beam line ensured the identification of the incident particles. Results a...

  8. Labelling of Re-ABP with 188Re for bone pain palliation

    International Nuclear Information System (INIS)

    Arteaga de Murphy, Consuelo; Ferro-Flores, Guillermina; Pedraza-Lopez, Martha; Melendez-Alafort, Laura; Croft, B.Y.Barbara Y.; Ramirez, Flor de Maria; Padilla, Juan

    2001-01-01

    Etidronate and medronate have been labelled with technetium-99m ( 99m Tc-HEDP, 99m Tc-MDP) for bone scanning and, with rhenium-188 ( 188 Re-HEDP) to palliate the pain resulting from bone metastases. The objective of this study was to label alendronate, ABP, a new bisphosphonate, with SnF 2 -reduced- 188 Re. The reagents for the 5 mg ABP kit were SnF 2 , KReO 4 and gentisic acid at acid pH. The chemical, spectroscopic and microscopic characteristics, quality control, rat bone uptake of [ 188 Re]Re-ABP and similarities with 99m Tc-ABP are presented. We conclude that this is a promising new radiopharmaceutical for bone metastases pain palliation

  9. Preparation of 188 Re-lanreotide as a potential tumor therapeutic agent

    International Nuclear Information System (INIS)

    Bai Hongsheng; Jin Xiaohai; Fan Hongqiang; Jia Bing; Wang Yuqing; Lu Weiwei

    2001-01-01

    Radiolabeled peptides hold unlimited potential in diagnostic applications and therapy of malignant tumor. Somatostatin analogue peptide (Lanreotide) is labeled directly with 188 Re via the mixture of citrate and tartrate. The influences of reaction conditions such as pH, temperature, amount of stannous chloride, Lanreotide quantity, reaction time on labeling yield are investigated in detail. At the same time, the stability in vitro, quality control and animal test are evaluated. The experimental results show that Lanreotide reacts with 188 Re for 40 min at pH 2 - 3 and 60 degree C, the labeling yield is at range of 88% - 94%. After purification of 188 Re-Lanreotide with Sep-Pak C 18 reverse phase extraction cartridge, the radiochemical purity (RP) is more than 95%. 188 Re-Lanreotide is eliminated rapidly from the blood and is excreted through liver, the uptake of lung and intestine is high

  10. Optimization of labelling procedure of 188rE-DMSA(v)

    International Nuclear Information System (INIS)

    Dantas, Danielle M.; Brambilla, Tania P.; Reis, Nicoli F.; Osso Junior, Joao A.

    2011-01-01

    Radionuclide therapy (RNT) is emerging as an important tool of nuclear medicine. Apart from the well established 131 I, several other promising radionuclides have been identified, among them 188 Re, 90 Y and 177 Lu. 188 Re has received a lot of attention in the past decade, due to its favourable nuclear characteristics [t 1/2 16.9 h, E b eta m ax 2.12 MeV and E g amma 155 keV (15%) suitable for imaging, including the fact that it is carrier-free and can be obtained cost-effectively through the generator 188 W- 188 Re. Biodistribution studies of 188 Re-DMSA(V) have shown that its general pharmacokinetic properties are similar to that of 99m Tc-DMSA(V), so this agent could be used for targeted radiotherapy of medullary thyroid carcinoma, bone metastases, soft tissue and others tumors. The aim of this work is to evaluate two labeling procedures for the preparation of 188 Re-DMSA(V). The first method was prepared using a commercial kit of DMSA(III) for labeling with 99m Tc at high temperature (100 deg C). The second method was prepared in a vial containing 2.5 mg of DMSA, 1.00 mg of SnCl 2 .2H 2 O and 10 mg of sodium oxalate, 10 mg of cyclodextrin, in a total volume of 2.0 mL. The pH was adjusted to 3 with 37% HCl. After labeling the solution was stirred and incubated for 30 min at room temperature. The radiochemical purity was determined using TLC-SG developed with two different solvent systems: Acetone and glycine. Preliminary results for both methods of labeling 188 Re-DMSA(V) showed that the labeling yield was >95%. Further experiments are also necessary to optimize the labeling methodology of 188 Re-DMSA(V).author)

  11. Dosimetric evaluation of anti-CD20 labelled with {sup 188}Re

    Energy Technology Data Exchange (ETDEWEB)

    Barrio, Graciela; Osso Junior, Joao A., E-mail: gracielabarrio@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Radioimmunotherapy has the potential to deliver lethal radiation energy directly to malignant cells via targeting of radioisotope-conjugated monoclonal antibodies (MAbs) to specific antigens. B-cell lymphoma is a particularly good candidate for radioimmunotherapy because the disease is inherently radiosensitive, malignant cells in the blood, bone marrow, spleen and lymphonodes are accessible, and MAbs have been developed to B-cell surface antigens that do not shed or modulate. Rituximab (RTX), the human IgG1-type chimeric form of the parent murine antibody ibritumomab, is specifically targeted against CD20, a surface antigen expressed by pre-B and mature human B lymphocytes. The use of rhenium-188 from a {sup 188}W/{sup 188}Re generator system represents an attractive alternative radionuclide for therapy. {sup 188}Re is produced from beta decay of the {sup 188}W parent. In addition to the emission of high-energy electrons (E{beta}= 2118 keV), {sup 188}Re also decays with emission of a gamma photon with an energy of 155 keV in 15% abundance. Besides the therapeutic usefulness of {sup 188}Re, the emission of gamma photon is an added advantage since the biodistribution of {sup 188}Re-labeled antibodies can be evaluated in vivo with a gamma camera. Also, rhenium has chemical properties similar to technetium. Thus, both can be conjugated to antibodies using similar chemistry methods. The objective of this work is to prove the usefulness of this radiopharmaceutical based on dosimetric studies, that are also required by the Brazilian Regulatory Agency (ANVISA). (author)

  12. Nuclear spin of 185Au and hyperfine structure of 188Au

    International Nuclear Information System (INIS)

    Ekstroem, C.; Ingelman, S.; Wannberg, G.

    1977-03-01

    The nuclear spin of 185 Au, I = 5/2, and the hyperfine separation of 188 Au, Δγ = +- 2992(30) MHz, have been measured with the atomic-beam magnetic resonance method. The spin of 185 Au indicates a deformed nuclear shape in the ground state. The small magnetic moment of 188 Au is close in value to those of the heavier I = 1 gold isotopes 190 192 194 Au, being located in a typical transition region. (Auth.)

  13. Poloxamer [corrected] 188 has a deleterious effect on dystrophic skeletal muscle function.

    Directory of Open Access Journals (Sweden)

    Rebecca L Terry

    Full Text Available Duchenne muscular dystrophy (DMD is an X-linked, fatal muscle wasting disease for which there is currently no cure and limited palliative treatments. Poloxomer 188 (P188 is a tri-block copolymer that has been proposed as a potential treatment for cardiomyopathy in DMD patients. Despite the reported beneficial effects of P188 on dystrophic cardiac muscle function, the effects of P188 on dystrophic skeletal muscle function are relatively unknown. Mdx mice were injected intraperitoneally with 460 mg/kg or 30 mg/kg P188 dissolved in saline, or saline alone (control. The effect of single-dose and 2-week daily treatment was assessed using a muscle function test on the Tibialis Anterior (TA muscle in situ in anaesthetised mice. The test comprises a warm up, measurement of the force-frequency relationship and a series of eccentric contractions with a 10% stretch that have previously been shown to cause a drop in maximum force in mdx mice. After 2 weeks of P188 treatment at either 30 or 460 mg/kg/day the drop in maximum force produced following eccentric contractions was significantly greater than that seen in saline treated control mice (P = 0.0001. Two week P188 treatment at either dose did not significantly change the force-frequency relationship or maximum isometric specific force produced by the TA muscle. In conclusion P188 treatment increases susceptibility to contraction-induced injury following eccentric contractions in dystrophic skeletal muscle and hence its suitability as a potential therapeutic for DMD should be reconsidered.

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

    Science.gov (United States)

    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.

  15. Successive heterolytic cleavages of H2 achieve N2 splitting on silica-supported tantalum hydrides: A DFT proposed mechanism

    KAUST Repository

    Solá ns, Xavier Luis; Chow, Catherine; Gouré , Eric; Kaya, Yasemin; Basset, Jean-Marie; Taoufik, Mostafa; Quadrelli, Elsje Alessandra; Eisenstein, Odile

    2012-01-01

    DFT(B3PW91) calculations have been carried out to propose a pathway for the N2 cleavage by H2 in the presence of silica-supported tantalum hydride complexes [(≡ SiO)2TaHx] that forms [(≡SiO)2Ta(NH)(NH2)] (Science2007, 317, 1056). The calculations

  16. ICP-MS determination of rare earth elements, yttrium, uranium and thorium in niobium-tantalum rich samples

    International Nuclear Information System (INIS)

    Sunilkumar, Beena; Padmasubashini, V.

    2013-01-01

    ICP-MS is a powerful and extremely sensitive technique which has been applied successfully for the determination of REEs in diverse geological samples. In the present work, ICP-MS has been applied for the rapid determination of REEs, yttrium as well as uranium and thorium in niobium and tantalum rich samples, using a fluoride fusion method for sample dissolution

  17. Tantalum coating on TiO{sub 2} nanotubes induces superior rate of matrix mineralization and osteofunctionality in human osteoblasts

    Energy Technology Data Exchange (ETDEWEB)

    Frandsen, Christine J.; Brammer, Karla S. [Materials Science and Engineering, University of California at San Diego, La Jolla, CA 92093 (United States); Noh, Kunbae [Corporate Research Institute, Cheil Industries, Inc., Gocheon-Dong, Uiwang-Si, Gyeonggi-Do, 437-711 (Korea, Republic of); Johnston, Gary [Materials Science and Engineering, University of California at San Diego, La Jolla, CA 92093 (United States); Jin, Sungho, E-mail: jin@ucsd.edu [Materials Science and Engineering, University of California at San Diego, La Jolla, CA 92093 (United States); Mechanical and Aerospace Engineering, University of California at San Diego, La Jolla, CA 92093 (United States)

    2014-04-01

    Nanostructured surface geometries have been the focus of a multitude of recent biomaterial research, and exciting findings have been published. However, only a few publications have directly compared nanostructures of various surface chemistries. The work herein directly compares the response of human osteoblast cells to surfaces of identical nanotube geometries with two well-known orthopedic biomaterials: titanium oxide (TiO{sub 2}) and tantalum (Ta). The results reveal that the Ta surface chemistry on the nanotube architecture enhances alkaline phosphatase activity, and promotes a ∼ 30% faster rate of matrix mineralization and bone-nodule formation when compared to results on bare TiO{sub 2} nanotubes. This study implies that unique combinations of surface chemistry and nanostructure may influence cell behavior due to distinctive physico-chemical properties. These findings are of paramount importance to the orthopedics field for understanding cell behavior in response to subtle alterations in nanostructure and surface chemistry, and will enable further insight into the complex manipulation of biomaterial surfaces. With increased focus in the field of orthopedic materials research on nanostructured surfaces, this study emphasizes the need for careful and systematic review of variations in surface chemistry in concurrence with nanotopographical changes. - Highlights: • A TiO{sub 2} nanotube surface structure was coated with tantalum. • Osteoblast cell response was compared between the tantalum coated and as-formed TiO{sub 2} nanotube surface. • We observed superior rates of bone matrix mineralization and osteoblast maturation on the tantalum coated nanotube surface.

  18. Tantalum coating on TiO2 nanotubes induces superior rate of matrix mineralization and osteofunctionality in human osteoblasts

    International Nuclear Information System (INIS)

    Frandsen, Christine J.; Brammer, Karla S.; Noh, Kunbae; Johnston, Gary; Jin, Sungho

    2014-01-01

    Nanostructured surface geometries have been the focus of a multitude of recent biomaterial research, and exciting findings have been published. However, only a few publications have directly compared nanostructures of various surface chemistries. The work herein directly compares the response of human osteoblast cells to surfaces of identical nanotube geometries with two well-known orthopedic biomaterials: titanium oxide (TiO 2 ) and tantalum (Ta). The results reveal that the Ta surface chemistry on the nanotube architecture enhances alkaline phosphatase activity, and promotes a ∼ 30% faster rate of matrix mineralization and bone-nodule formation when compared to results on bare TiO 2 nanotubes. This study implies that unique combinations of surface chemistry and nanostructure may influence cell behavior due to distinctive physico-chemical properties. These findings are of paramount importance to the orthopedics field for understanding cell behavior in response to subtle alterations in nanostructure and surface chemistry, and will enable further insight into the complex manipulation of biomaterial surfaces. With increased focus in the field of orthopedic materials research on nanostructured surfaces, this study emphasizes the need for careful and systematic review of variations in surface chemistry in concurrence with nanotopographical changes. - Highlights: • A TiO 2 nanotube surface structure was coated with tantalum. • Osteoblast cell response was compared between the tantalum coated and as-formed TiO 2 nanotube surface. • We observed superior rates of bone matrix mineralization and osteoblast maturation on the tantalum coated nanotube surface

  19. Radiolabeling of anti-CD20 with Re0-188: liquid kit

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Carla Roberta; Osso Junior, Joao Alberto [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mail: carlarobertab@yahoo.com.br; jaosso@ipen.br

    2007-07-01

    Radioimmunotherapy uses the targeting features of monoclonal antibody to deliver radiation from an attached radionuclide. The radionuclide {sup 188}Re is currently produced from the father nuclide {sup 188}W through a transportable generator system. Because of its easy availability and suitable nuclear properties (E{sub {beta}}{sub MAX} =2.1 MeV, t{sub 1/2}=16.9 h, E{sub {gamma}}=155 keV), this radionuclide is considered an attractive candidate for application as therapeutic agents and could be conveniently utilized for imaging and dosimetric purposes. The objective of this work is the optimization of radiolabeling of anti-CD20 with {sup 188}Re using a liquid formulation. Anti-CD20 was reduced by incubation with 2-ME and purified over a PD-10 column. The number of resulting free SH was assayed with Ellman's reagent. Optimization of radiolabeling was achieved by varying parameters: antibody mass, reducing agent, reaction time and {sup 188}Re volume in the liquid kit. Radiochemical purity of {sup 188}Re-anti-CD20 was evaluated. An average of 12 SH groups per mol in the reductions was found. The best labeling efficiency (> 93%) was achieved in the following conditions: 1 mg anti-CD20; 82.8 mg sodium tartrate; 1 mg SnCl{sub 2}; 0.25 mg gentisic acid, 1 mL {sup 188}Re and reaction time of 1 hour at room temperature. (author)

  20. Radiolabeling of anti-CD20 with Re0-188: liquid kit

    International Nuclear Information System (INIS)

    Dias, Carla Roberta; Osso Junior, Joao Alberto

    2007-01-01

    Radioimmunotherapy uses the targeting features of monoclonal antibody to deliver radiation from an attached radionuclide. The radionuclide 188 Re is currently produced from the father nuclide 188 W through a transportable generator system. Because of its easy availability and suitable nuclear properties (E βMAX =2.1 MeV, t 1/2 =16.9 h, E γ =155 keV), this radionuclide is considered an attractive candidate for application as therapeutic agents and could be conveniently utilized for imaging and dosimetric purposes. The objective of this work is the optimization of radiolabeling of anti-CD20 with 188 Re using a liquid formulation. Anti-CD20 was reduced by incubation with 2-ME and purified over a PD-10 column. The number of resulting free SH was assayed with Ellman's reagent. Optimization of radiolabeling was achieved by varying parameters: antibody mass, reducing agent, reaction time and 188 Re volume in the liquid kit. Radiochemical purity of 188 Re-anti-CD20 was evaluated. An average of 12 SH groups per mol in the reductions was found. The best labeling efficiency (> 93%) was achieved in the following conditions: 1 mg anti-CD20; 82.8 mg sodium tartrate; 1 mg SnCl 2 ; 0.25 mg gentisic acid, 1 mL 188 Re and reaction time of 1 hour at room temperature. (author)

  1. microRNA-188 is downregulated in oral squamous cell carcinoma and inhibits proliferation and invasion by targeting SIX1.

    Science.gov (United States)

    Wang, Lili; Liu, Hongchen

    2016-03-01

    microRNA-188 expression is downregulated in several tumors. However, its function and mechanism in human oral squamous cell carcinoma (OSCC) remains obscure. The present study aims to identify the expression pattern, biological roles, and potential mechanism by which miR-188 dysregulation is associated with oral squamous cell carcinoma. Significant downregulation of miR-188 was observed in OSCC tissues compared with paired normal tissues. In vitro, gain-of-function, loss-of-function experiments were performed to examine the impact of miR-188 on cancer cell proliferation, invasion, and cell cycle progression. Transfection of miR-188 mimics suppressed Detroit 562 cell proliferation, cell cycle progression and invasion, with downregulation of cyclin D1, MMP9, and p-ERK. Transfection of miR-188 inhibitor in FaDu cell line with high endogenous expression exhibited the opposite effects. Using fluorescence reporter assays, we confirmed that SIX1 was a direct target of miR-188 in OSCC cells. Transfection of miR-188 mimics downregulated SIX1 expression. SIX1 siRNA treatment abrogated miR-188 inhibitor-induced cyclin D1 and MMP9 upregulation. In addition, we found that SIX1 was overexpressed in 32 of 80 OSCC tissues. In conclusion, this study indicates that miR-188 downregulation might be associated with oral squamous cell carcinoma progression. miR-188 suppresses proliferation and invasion by targeting SIX1 in oral squamous cell carcinoma cells.

  2. Compartmental and dosimetric studies of anti-CD20 labelled with {sup 188}Re; Estudo compartimental e dosimetrico do Anti-CD20 marcado com {sup 188}Re

    Energy Technology Data Exchange (ETDEWEB)

    Kuramoto, Graciela Barrio

    2016-10-01

    The radioimmunotherapy (RIT) uses MAbs conjugated to radionuclides α or β{sup -} emitters, both for therapy. Your treatment is based on the irradiation and tumor destruction, preserving the normal organs as the excess radiation. Radionuclides β{sup -} emitters as {sup 131}I, {sup 90}Y, {sup 188}Re {sup 177}Lu and are useful for the development of therapeutic radiopharmaceuticals and, when coupled with MAb and Anti-CD20 it is important mainly for the treatment of non-Hodgkin's lymphomas (NHL). {sup 188}Re (E{sub β} = 2.12 MeV; E{sub γ} = 155 keV; t1/2 = 16.9 h) is an attractive radionuclide for RIT. However, {sup 188}Re can be obtained from a radionuclide generator of {sup 188}W/{sup 188}Re, commercially available, making it convenient for use in research and for clinical routine. The CR of IPEN has a project aimed at the production of radiopharmaceutical {sup 188}Re-Anti-CD20, where the radionuclide can be obtained from a generator system {sup 188}W/{sup 188}Re. With this proposed a study to assess the efficiency of this labeling technique for treatment in accordance compartmental and dosimetry. The objective of this study was to compare the marking of anti-CD20 MAb with {sup 188}Re with the marking of the antibody with {sup 90}Y, {sup 131}I, {sup 177}Lu and {sup 99m}Tc (for their similar chemical characteristics) and {sup 211}At, {sup 213}Bi, {sup 223}Ra and {sup 225}Ac); through the study of labeling techniques reported in literature, the proposal of a compartmental model to evaluate its pharmacokinetic and dosimetric studies, high interest for therapy. The result of the study shows a favorable kinetics for {sup 188}Re, by their physical and chemical characteristics compared to the other evaluated radionuclides. The compartment proposed study describes the metabolism of {sup 188}Reanti- CD20 through a compartment mammillary model, which by their pharmacokinetic analysis, performed compared to products emitters β{sup -131}I-labeled anti CD20, {sup 177

  3. SKLB188 inhibits the growth of head and neck squamous cell carcinoma by suppressing EGFR signalling.

    Science.gov (United States)

    Barzegar, Mansoureh; Ma, Shuang; Zhang, Chao; Chen, Xin; Gu, Ying; Shang, Chaowei; Jiang, Xiaojuan; Yang, Jiao; Nathan, Cherie-Ann; Yang, Shengyong; Huang, Shile

    2017-10-10

    Overexpression of epidermal growth factor receptor (EGFR) occurs in approximately 90% of head and neck squamous cell carcinoma (HNSCC), and is correlated with poor prognosis. Thus, targeting EGFR is a promising strategy for treatment of HNSCC. Several small molecule EGFR inhibitors have been tested in clinical trials for treatment of HNSCC, but none of them are more effective than the current chemotherapeutic drugs. Thus, it is urgently needed to develop novel EGFR inhibitors for HNSCC treatment. By screening an in-house focused library containing approximately 650 000 known kinase inhibitors and kinase inhibitor-like compounds containing common kinase inhibitor core scaffolds, we identified SKLB188 as a lead compound for inhibition of EGFR. The anticancer effects of SKLB188 on HNSCC cells were investigated by in vitro cell growth, cell cycle and apoptosis assays, as well as in vivo FaDu xenograft mouse model. Molecular docking, in vitro kinase profiling and western blotting were performed to characterise EGFR as the molecular target. SKLB188 inhibited HNSCC cell proliferation by inducing G 1 cell cycle arrest, which was associated with downregulating the expression of Cdc25A, cyclins D1/A and cyclin-dependent kinases (CDK2/4), and upregulating the expression of cyclin-dependent kinase (CDK) inhibitors (p21 Cip1 and p27 Kip1 ), leading to decreased phosphorylation of Rb. SKLB188 also induced caspase-dependent apoptosis of HNSCC cells by downregulating the expression of Mcl-1 and survivin. Molecular docking revealed that SKLB188 could bind to the kinase domain of EGFR through hydrogen bonds and hydrophobic interactions. In vitro kinase assay showed that SKLB188 inhibited the activity of a recombinant human EGFR very potently (IC 50 =5 nM). Western blot analysis demonstrated that SKLB188 inhibited the phosphorylation of EGFR and its downstream targets, extracellular signal-regulated protein kinases 1 and 2 (Erk1/2) and Akt in the cells. In addition, SKLB188 dose

  4. Modified porous tantalum rod technique for the treatment of femoral head osteonecrosis.

    Science.gov (United States)

    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

  5. TiO2 effect on break-down of low-grade tantalum-niobium concentrates in the process of sulphatization

    International Nuclear Information System (INIS)

    Petrova, N.V.; Popov, A.D.; Mulenko, V.N.

    1982-01-01

    The effect of TiO 2 additive or materials containing it on tantalum-niobate decomposition in the process of sulphatization is investigated. It is shown that favourable effect of titanium dioxide in the process of sulphatization is especially noticeable in reprocessing of hard-brokening down tantalum-niobium concentrates with low Nb:Ta ratio etc. Chemical composition and type of tantalum-niobium mineralization of enrichment products used in the given investigation is presented. It is stated that the degree of concentrate break-down under similar sulphatization conditions (t=230 deg C; tau=2 h) essentially depends on the quantity of the introduced titanium dioxide. It is shown that sulphatization in the presence of titanium dioxide additive or materials containing it permits to exercise practically complete break-down of lean tantalum-niobium raw material, to avoid application of complexers in leaching of sulphatization products

  6. Texture evolution in upset-forged P/M and wrought tantalum: Experimentation and modeling

    International Nuclear Information System (INIS)

    Bingert, J.F.; Desch, P.B.; Bingert, S.R.; Maudlin, P.J.; Tome, C.N.

    1997-11-01

    Preferred orientations in polycrystalline materials can significantly affect their physical and mechanical response through the retention of anisotropic properties inherent to the single crystal. In this study the texture evolution in upset-forged PIM and wrought tantalum was measured as a function of initial texture, compressive strain, and relative position in the pressing. A / duplex fiber texture parallel to the compression axis was generally observed, with varying degrees of a radial component evident in the wrought material. The development of deformation textures derives from restricted crystallographic slip conditions that generate lattice rotations, and these grain reorientations can be modeled as a function of the prescribed deformation gradient. Texture development was simulated for equivalent deformations using both a modified Taylor approach and a viscoplastic self-consistent (VPSC) model. A comparison between the predicted evolution and experimental results shows a good correlation with the texture components, but an overly sharp prediction at large strains from both the Taylor and VPSC models

  7. Study on the property of low friction complex graphite-like coating containing tantalum

    Science.gov (United States)

    Wang, Zuoping; Feng, Lajun; Shen, Wenning

    2018-03-01

    In order to enhance equipment lifetime under low oil or even dry conditions, tantalum was introduced into the graphite-like coating (GLC) by sputtering mosaic targets. The results showed that the introduction of Ta obviously reduced the friction coefficient and hardness of the GLC, while improved the wearability. When the atomic percentage of Ta was larger than 3%, the steady friction coefficient was lower than 0.01, suggesting the coating exhibited super lubricity. When the content of Ta was about 5.0%, the average friction coefficient was 0.02 by a sliding friction test under load of 20 N in unlubricated condition. Its average friction coefficient reduced by 75%, compared with that of control GLC (0.0825).

  8. Investigation and modeling of the anomalous yield point phenomenon in pure tantalum

    Energy Technology Data Exchange (ETDEWEB)

    Colas, D. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Université de Bourgogne, 9 avenue Alain Savary, BP 17870, 21078 Dijon Cedex (France); CEA Valduc, 21120 Is-sur-Tille (France); Mines ParisTech, Centre des Matériaux, CNRS, UMR 7633, BP 87, 91003 Evry Cedex (France); Finot, E. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Université de Bourgogne, 9 avenue Alain Savary, BP 17870, 21078 Dijon Cedex (France); Flouriot, S. [CEA Valduc, 21120 Is-sur-Tille (France); Forest, S. [Mines ParisTech, Centre des Matériaux, CNRS, UMR 7633, BP 87, 91003 Evry Cedex (France); Mazière, M., E-mail: matthieu.maziere@mines-paristech.fr [Mines ParisTech, Centre des Matériaux, CNRS, UMR 7633, BP 87, 91003 Evry Cedex (France); Paris, T. [CEA Valduc, 21120 Is-sur-Tille (France)

    2014-10-06

    The monotonic and cyclic behavior of commercially pure tantalum has been investigated at room temperature, in order to capture and understand the occurrence of the anomalous yield point phenomenon. Interrupted tests have been performed, with strain reversals (tensile or compressive loading) after an aging period. The stress drop is attributed to the interactions between dislocations and solute atoms (oxygen) and its macroscopic occurrence is not systematically observed. InfraRed Thermography (IRT) measurements supported by Scanning Electron Microscopy (SEM) pictures of the polished gauge length of a specimen during an interrupted tensile test reveal the nucleation and propagation of a strain localization band. The KEMC (Kubin–Estrin–McCormick) phenomenological model accounting for strain aging has been identified for several loadings and strain rates at room temperature. Simulations on full specimen using the KEMC model do not show strain localization, because of the competition between viscosity and strain localization. However, a slight misalignment of the sample can promote strain localization.

  9. Variability in dynamic properties of tantalum : spall, attenuation and load/unload.

    Energy Technology Data Exchange (ETDEWEB)

    Furnish, Michael David; Reinhart, William Dodd; Trott, Wayne Merle; Vogler, Tracy John; Chhabildas, Lalit Chandra

    2005-07-01

    A suite of impact experiments was conducted to assess spatial and shot-to-shot variability in dynamic properties of tantalum. Samples had a uniform refined {approx}20 micron grain structure with a strong axisymmetric [111] crystallographic texture. Two experiments performed with sapphire windows (stresses of approximately 7 and 12 GPa) clearly showed elastic-plastic loading and slightly hysteretic unloading behavior. An HEL amplitude of 2.8 GPa (corresponding to Y 1.5 GPa) was observed. Free-surface spall experiments showed clear wave attenuation and spallation phenomena. Here, loading stresses were {approx} 12.5 GPa and various ratios of impactor to target thicknesses were used. Spatial and shot-to-shot variability of the spall strength was {+-} 20%, and of the HEL, {+-} 10%. Experiments conducted with smaller diameter flyer plates clearly showed edge effects in the line and point VISAR records, indicating lateral release speeds of roughly 5 km/s.

  10. Spatial and temporal changes in the morphology of preosteoblastic cells seeded on microstructured tantalum surfaces

    DEFF Research Database (Denmark)

    Justesen, Jørn; Lorentzen, M.; Andersen, L. K.

    2009-01-01

    It has been widely reported that surface morphology on the micrometer scale affects cell function as well as cell shape. In this study, we have systematically compared the influence of 13 topographically micropatterned tantalum surfaces on the temporal development of morphology, including spreading......, and length of preosteoblastic cells (MC3T3-E1). Cells were examined after 0.5, 1, 4, and 24 h on different Ta microstructures with vertical dimensions (heights) of 0.25 and 1.6 mu m. Cell morphologies depended upon the underlying Surface topography, and the length and spreading of cells varied as a function...... to depend on the distance between the pillars with one specific pillar Structure exhibiting a decreased spreading combined with a radical change in morphology of the cells. Interestingly, this morphology on the particular pillar structure was associated with a markedly different distribution of the actio...

  11. Comparative study of tantalum deposition by chemical vapor deposition and electron beam vacuum evaporation

    International Nuclear Information System (INIS)

    Spitz, J.; Chevallier, J.

    1975-01-01

    The coating by tantalum of steel parts has been carried out by the two following methods: chemical vapor deposition by hydrogen reduction of TaCl 5 (temperature=1100 deg C, pressure=200 mmHg, H 2 /TaCl 5 =10); electron beam vacuum evaporation. In this case Ta was firstly condensed by ion plating (P(Ar)=5x10 -3 up to 2x10 -2 mmHg; U(c)=3 to -4kV and J(c)=0.2 to 1mAcm -2 ) in order to ensure a good adhesion between deposit and substrate; then by vacuum condensation (substrate temperature: 300 to 650 deg C) to ensure that the coating is impervious to HCl an H 2 SO 4 acids. The advantages and inconveniences of each method are discussed [fr

  12. High temperature thermodynamics of solutions of oxygen in vanadium, niobium and tantalum

    International Nuclear Information System (INIS)

    Boureau, G.; Gerdanian, P.

    1981-01-01

    The Tian-Calvet microcalorimetric method has been applied to the determination at 1323 K of ΔH(O 2 ), the partial molar enthalpy of mixing of oxygen in vanadium, niobium and tantalum. The present results are in good agreement with earlier studies using e.m.f. techniques. Nevertheless in the first two solutions, ΔH(O 2 ) has been found somewhat more negative than previously reported. The partial molar entropies of mixing have been recalculated. The low values of the excess entropies are explained by a strong increase of the Debye temperature and a decrease of the electronic density of states at the Fermi level as the oxygen content increases. (author)

  13. Sound velocity of tantalum under shock compression in the 18–142 GPa range

    Energy Technology Data Exchange (ETDEWEB)

    Xi, Feng, E-mail: xifeng@caep.cn; Jin, Ke; Cai, Lingcang, E-mail: cai-lingcang@aliyun.com; Geng, Huayun; Tan, Ye; Li, Jun [National Key Laboratory of Shock Waves and Detonation Physics, Institute of Fluid Physics, CAEP, P.O. Box 919-102 Mianyang, Sichuan 621999 (China)

    2015-05-14

    Dynamic compression experiments of tantalum (Ta) within a shock pressure range from 18–142 GPa were conducted driven by explosive, a two-stage light gas gun, and a powder gun, respectively. The time-resolved Ta/LiF (lithium fluoride) interface velocity profiles were recorded with a displacement interferometer system for any reflector. Sound velocities of Ta were obtained from the peak state time duration measurements with the step-sample technique and the direct-reverse impact technique. The uncertainty of measured sound velocities were analyzed carefully, which suggests that the symmetrical impact method with step-samples is more accurate for sound velocity measurement, and the most important parameter in this type experiment is the accurate sample/window particle velocity profile, especially the accurate peak state time duration. From these carefully analyzed sound velocity data, no evidence of a phase transition was found up to the shock melting pressure of Ta.

  14. Examination of the damage and failure response of tantalum and copper under varied shock loading conditions

    Energy Technology Data Exchange (ETDEWEB)

    Bronkhorst, Curt A [Los Alamos National Laboratory; Dennis - Koller, Darcie [Los Alamos National Laboratory; Cerreta, Ellen K [Los Alamos National Laboratory; Gray Ill, George T [Los Alamos National Laboratory; Bourne, Neil [AWE-ALDERMASTON

    2010-12-16

    A number of plate impact experiments have been conducted on high purity polycrystalline tantalum and copper samples using graded flyer plate configurations to alter the loading profile. These experiments are designed in a way so that a broad range of damage regimes are probed. The results show that the nucleation of damage primarily occurs at the grain boundaries of the materials. This affords us the opportunity to propose a porosity damage nucleation criterion which begins to account for the length scales of the microstructure (grain size distribution) and the mechanical response of the grain boundary regions (failure stress distribution). This is done in the context of a G-T-N type model for the ductile damage and failure response of both the materials examined. The role of micro-inertial effects on the porosity growth process is also considered.

  15. Corrosion resistance and cytocompatibility of tantalum-surface-functionalized biomedical ZK60 Mg alloy

    International Nuclear Information System (INIS)

    Jin, Weihong; Wang, Guomin; Lin, Zhengjie; Feng, Hongqing; Li, Wan; Peng, Xiang; Qasim, Abdul Mateen; Chu, Paul K.

    2017-01-01

    Highlights: • Films comprising Ta_2O_5, Ta suboxide, and Ta are sputter-deposited on ZK60 Mg alloy. • The Ta-containing film significantly mitigates degradation of ZK60. • The modified ZK60 exhibits notably enhanced cell adhesion and proliferation. - Abstract: Tantalum (Ta) is introduced to the surface of the ZK60 Mg alloy by reactive magnetron sputtering to enhance the corrosion resistance and cytocompatibility. The film thickness and composition, corrosion behavior, and cytocompatibility are studied by various techniques systematically. The surface layer composed of Ta_2O_5, Ta suboxide, and Ta increases the corrosion resistance of ZK60 while simultaneously improving cell attachment, spreading, and proliferation in vitro. The enhancement mechanism is proposed and discussed.

  16. Experimental investigation into the crack propagation in multiphase tantalum carbide ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Bradford C. [Department of Metallurgical & Materials Engineering, The University of Alabama, 301 7th Avenue, 116 Houser Hall, Tuscaloosa, AL 35487-0202 (United States); Lee, HeeDong; Mogilevsky, Pavel [UES, Inc., 4401 Dayton-Xenia Road, Dayton, OH 45432-1894 (United States); Weinberger, Christopher R. [Department of Mechanical Engineering, Colorado State University, 1374 Campus Delivery, Fort Collins, CO 80523 (United States); Parthasarathy, Triplicane A. [UES, Inc., 4401 Dayton-Xenia Road, Dayton, OH 45432-1894 (United States); Matson, Lawrence E. [Air Force Research Laboratory Materials & Manufacturing Directorate, Structural Material Division (AFRL/RXLN), 2230 Tenth St., Wright-Patterson AFB, OH 4543307817 (United States); Smith, Chase [Department of Metallurgical & Materials Engineering, The University of Alabama, 301 7th Avenue, 116 Houser Hall, Tuscaloosa, AL 35487-0202 (United States); Thompson, Gregory B., E-mail: gthompson@eng.ua.edu [Department of Metallurgical & Materials Engineering, The University of Alabama, 301 7th Avenue, 116 Houser Hall, Tuscaloosa, AL 35487-0202 (United States)

    2017-05-17

    Tantalum carbide ceramics with high volume fractions of the ζ-Ta{sub 4}C{sub 3} phase have been shown to exhibit high fracture strength and toughness as compared to those in absence of this phase. In this work, we investigated how microcracks propagated in this these high toughness ceramics using Knoop and Vickers microindentation. The Knoop indentations demonstrated that cracking preferentially occurred parallel to the lath structure in ζ-Ta{sub 4}C{sub 3}; however shorter cracks did form between the laths when a sufficient driving force was present. The resulting crack path was tortuous providing direct evidence for toughening through crack deflection; however, the microscale nature of the work cannot rule out crack bridging as a toughening mechanism as well. Plasticity is also observed under the indents, but is likely a result of the high confining pressures that occurred during indentation allowing for plastic flow.

  17. III-V group compound semiconductor light-emitting element having a doped tantalum barrier layer

    International Nuclear Information System (INIS)

    Oanna, Y.; Ozawa, N.; Yamashita, M.; Yasuda, N.

    1984-01-01

    Disclosed is a III-V Group compound semiconductor light-emitting element having a III-V Group compound semiconductor body with a p-n junction and including a p-type layer involved in forming the p-n junction; and a multi-layer electrode mounted on the p-type layer of the semiconductor body. The electrode comprises a first layer of gold alloy containing a small amount of beryllium or zinc and formed in direct contact with the p-type layer of the semiconductor body and an uppermost layer formed of gold or aluminum. A tantalum layer doped with carbon, nitrogen and/or oxygen is formed between the first layer and the uppermost layer by means of vacuum vapor deposition

  18. Attractive short-range interatomic potential in the lattice dynamics of niobium and tantalum

    International Nuclear Information System (INIS)

    Onwuagba, B.N.; Pal, S.

    1987-01-01

    It is shown in the framework of the pseudopotential approach that there is a sizable attractive short-range component of the interatomic potential due to the s-d interaction which has the same functional form in real space as the Born-Mayer repulsion due to the overlap of core electron wave functions centred on neighbouring ions. The magnitude of this attractive component is such as to completely cancel the conventional Born-Mayer repulsion, making the resultant short-range interatomic potential attractive rather than repulsive. Numerical calculations show that the attractive interatomics potential, which represents the local-field correction, leads to a better understanding of the occurrence of the soft modes in the phonon dispersion curves of niobium and tantalum

  19. Experimental and Theoretical Studies on Corrosion Inhibition of Niobium and Tantalum Surfaces by Carboxylated Graphene Oxide

    Directory of Open Access Journals (Sweden)

    Valbonë Mehmeti

    2018-05-01

    Full Text Available The corrosion of two different metals, niobium and tantalum, in aqueous sulfuric acid solution has been studied in the presence and absence of carboxylated graphene oxide. Potentiodynamic measurements indicate that this nanomaterial inhibits corrosion due to its adsorption on the metal surfaces. The adsorbed layer of carboxylated graphene hinders two electrochemical reactions: the oxidation of the metal and the transport of metal ions from the metal to the solution but also hydrogen evolution reaction by acting as a protective barrier. The adsorption behavior at the molecular level of the carboxylated graphene oxide with respect to Nb, NbO, Ta, and TaO (111 surfaces is also investigated using Molecular Dynamic and Monte Carlo calculations.

  20. Estimation of niobium, tantalum and zirconium in a carbonate rich ore

    International Nuclear Information System (INIS)

    Navale, A.S.; Venkatakrishnan, R.R.; Sreenivas, T.

    2013-01-01

    Tantalum, niobium and zirconium form refractory compounds and therefore pose problems in estimation by methods like spectrophotometry, AAS etc. Their estimation is best carried out with ICP-OES as the plasma is capable of breaking the refractory compounds and releases these elements in the form of excited atoms. But another major problem is bringing these elements in solution as they require very strong reagents and tend to hydrolyze easily in solution. Complexing agents need to be added to maintain these elements in dissolved condition. The commonly employed dissolution techniques for these elements are fusion with potassium pyrosulfate (for Nb and Ta), sodium hydroxide or peroxide (for zirconium). Digestion with mineral acids in combination with hydrofluoric acid is also employed

  1. Shear-induced anisotropic plastic flow from body-centred-cubic tantalum before melting

    Science.gov (United States)

    Wu, Christine J.; Söderlind, Per; Glosli, James N.; Klepeis, John E.

    2009-03-01

    There are many structural and optical similarities between a liquid and a plastic flow. Thus, it is non-trivial to distinguish between them at high pressures and temperatures, and a detailed description of the transformation between these phenomena is crucial to our understanding of the melting of metals at high pressures. Here we report a shear-induced, partially disordered viscous plastic flow from body-centred-cubic tantalum under heating before it melts into a liquid. This thermally activated structural transformation produces a unique, one-dimensional structure analogous to a liquid crystal with the rheological characteristics of Bingham plastics. This mechanism is not specific to Ta and is expected to hold more generally for other metals. Remarkably, this transition is fully consistent with the previously reported anomalously low-temperature melting curve and thus offers a plausible resolution to a long-standing controversy about melting of metals under high pressures.

  2. A study of nitride formation during the oxidation of titanium-tantalum alloys

    International Nuclear Information System (INIS)

    Hanrahan, R.J. Jr.; Lu, Y.C.; Kung, H.; Butt, D.P.

    1996-01-01

    The oxidation rates of Ti rich titanium-tantalum alloys are significantly lower in air than in oxygen. This nitrogen effect has been shown to be associated with the formation of a nitride layer at or near the scale-metal interface. In the present work the authors used transmission electron microscopy and microdiffraction to identify the nitrides formed on Ti5Ta and Ti40Ta (5 and 40 weight percent Ta alloys) during identical exposures. In both alloys the nitride develops in contact with the oxygen stabilized α-phase in the substrate. In Ti5Ta a continuous layer of TiN forms, while in Ti40Ta a discontinuous layer of Ti 2 N interspersed with Ta 2 O 5 (formed from the Ta rich β-phase) is formed. The nitride layer acts as an oxygen diffusion barrier, reducing the dissolution of oxygen in the substrate

  3. [(≡SiO)TaV (=CH2)Cl2], the first tantalum methylidene species prepared and identified on the silica surface

    KAUST Repository

    Chen, Yin

    2013-11-01

    A novel surface tantalum methylidene [(≡SiO)TaV (=CH 2)Cl2] was obtained via thermal decomposition of the well-defined surface species [(≡SiO)TaVCl2Me 2]. This first surface tantalum methylidene ever synthesized has been fully characterized and the kinetics of the a-hydrogen abstraction reaction has also been investigated in the heterogeneous system. © 2013 Elsevier B.V. All rights reserved.

  4. [(≡SiO)TaV (=CH2)Cl2], the first tantalum methylidene species prepared and identified on the silica surface

    KAUST Repository

    Chen, Yin; Callens, Emmanuel; Abou-Hamad, Edy; Basset, Jean-Marie

    2013-01-01

    A novel surface tantalum methylidene [(≡SiO)TaV (=CH 2)Cl2] was obtained via thermal decomposition of the well-defined surface species [(≡SiO)TaVCl2Me 2]. This first surface tantalum methylidene ever synthesized has been fully characterized and the kinetics of the a-hydrogen abstraction reaction has also been investigated in the heterogeneous system. © 2013 Elsevier B.V. All rights reserved.

  5. EFFICACY of P188 ON LAPINE MENISCUS PRESERVATION FOLLOWING BLUNT TRAUMA

    Science.gov (United States)

    Coatney, Garrett A.; Abraham, Adam C.; Fischenich, Kristine M.; Button, Keith D.; Haut, Roger C.; Haut Donahue, Tammy L.

    2015-01-01

    Traumatic injury to the knee leads to the development of posttraumatic osteoarthritis. The objective of this study was to characterize the effects of a single intra-articular injection of a non-ionic surfactant, Poloxamer 188 (P188), in preservation of meniscal tissue following trauma through maintenance of meniscal glycosaminoglycan (GAG) content and mechanical properties. Flemish Giant rabbits were subjected to a closed knee joint, traumatic compressive impact with the joint constrained to prevent anterior tibial translation. The contralateral limb served as an un-impacted control. Six animals (treated) received an injection of P188 in phosphate buffered saline (PBS) post trauma, and another six animals (sham) received a single injection of PBS to the impacted limb. Histological analyses for GAG was determined 6 weeks post trauma, and functional outcomes were assessed using stress relaxation micro-indentation. The impacted limbs of the sham group demonstrated a significant decrease in meniscal GAG coverage compared to non-impacted limbs (p < 0.05). GAG coverage of the impacted P188 treated limbs was not significantly different than contralateral non-impacted limbs in all regions except the medial anterior (p < 0.05). No significant changes were documented in mechanics for either the sham or treated groups compared to their respective control limbs. This suggests that a single intra-articular injection of P188 shows promise in prevention of trauma induced GAG loss. PMID:25846264

  6. Country report: India. Development of Radiopharmaceuticals Based on 188Re and 90Y for Radionuclide Therapy

    International Nuclear Information System (INIS)

    Venkatesh, M.; Pandey, U.; Dhami, P.S.; Chakravarty, R.; Kameswaran, M.; Subramanian, S.; Dash, A.; Samuel, G.

    2010-01-01

    During the past decade, our group has focused attention on the development of therapeutic radiopharmaceuticals incorporating radioisotopes such as 90 Y, 188 Re etc. As the primary source of the radioisotopes 90 Y and 188 Re are the 90 Sr/ 90 Y generators and 188 W/ 188 Re generators respectively, the local availability of these generator systems is very important for the successful development of radiopharmaceuticals incorporating these radioisotopes. In this context, 90 Sr/ 90 Y generators based on Supported Liquid Membrane (SLM) [1-3] and electrochemical techniques [4] could be designed and deployed in our laboratories for the elution of 90 Y to be used for preparation of 90 Y labeled products. This work formed a part of the IAEA co-ordinated CRP on “Development of Generator Technologies for Therapeutic Radionuclides: 90 Y and 188 Re”. In this report, work on the development of 90 Y radiopharmaceuticals for treatment of liver cancer and non-Hodgkin’s lymphoma (NHL) is reported. In addition, comparison of the Extraction Paper Chromatography technique (EPC) developed for determination of 90 Sr contamination in 90 Y samples with the US Pharmacopeia recommended method as well as the validation of the EPC technique is presented

  7. 188Re-microspheres of albumin - the potential preparation for radiotherapy

    International Nuclear Information System (INIS)

    Dyomin, D.N.; Petriev, V.M.

    2000-01-01

    In this paper author describe preparation the albumin microspheres labelled with rhenium-188. We undertake an attempt to develop kits to the generator of rhenium-188 on the basis of albumin microspheres for radiotherapy of both oncological and non-oncological diseases. Microspheres, rhenium-188 with sizes 1 0-20 micron for treatment of rheumatoid arthritis (damage of large and intermediate joints), intraperitoneal administration and intrapleural administration at metastases covering a cavity. Microspheres, Re-188 with sizes 40-60 micron for treatment of disseminated kidney cancer (intraarterial, selectively), intratumoral administration to damaged nodules less than 2-3 cm. Microspheres, Re-188 with sizes 80-100 micron for large neoplasms and metastases of liver (intraarterial, selectively), intratumoral administration to damaged nodules with sizes over 3 cm. Preparation of albumin microspheres is carried out by thermal denaturation of protein in vegetable oil. Microspheres are obtained with the necessary range of sizes by ultrasonic fractionation. At our laboratory the method of preparation of albumin microspheres with any sizes of particles (from 5 -10 up to 800 -1000 microns) has been developed. (authors)

  8. Composition dependence of the kinetics and mechanisms of thermal oxidation of titanium-tantalum alloys

    International Nuclear Information System (INIS)

    Park, Y.S.; Butt, D.P.

    1999-01-01

    The oxidation behavior of titanium-tantalum alloys was investigated with respective concentrations of each element ranging from 0 to 100 wt.%. Alloys were exposed to argon-20% oxygen at 800 to 1400 C. The slowest oxidation rates were observed in alloys with 5--20% Ta. The oxidation kinetics of alloys containing less than approximately 40% Ta were approximately parabolic. Pure Ta exhibited nearly linear kinetics. Alloys containing 50% or more Ta exhibited paralinear kinetics. The activation energies for oxidation ranged between 232 kJ/mole for pure Ti and 119 kJ/mole for pure Ta, with the activation energies of the alloys falling between these values and generally decreasing with increasing Ta content. The activation energies for oxidation of the end members, Ti and Ta, agree well with published values for the activation energies for diffusion of oxygen in α-Ti and Ta. Scale formation in the alloys was found to be complex exhibiting various layers of Ti-, Ta-, and TiTa-oxides. The outermost layer of the oxidized alloys was predominantly rutile (TiO 2 ). Beneath the TiO 2 grew a variety of other oxides with the Ta content generally increasing with proximity to the metal-oxide interface. It was found that the most oxidation-resistant alloys had compositions falling between Ti-5Ta and Ti-15Ta. Although Ta stabilizes the β-phase of Ti, the kinetics of oxidation appeared to be rate limited by oxygen transport through the oxygen-stabilized α-phase. However, the kinetics are complicated by the formation of a complex oxide, which cracks periodically. Tantalum appears to increase the compositional range of oxygen-stabilized α-phase and reduces both the solubility of oxygen and diffusivity of Ti in the α- and β-phases

  9. Development of tantalum oxynitride thin films produced by PVD: Study of structural stability

    Energy Technology Data Exchange (ETDEWEB)

    Cristea, D. [Centro de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Department of Materials Science, Transylvania University, 500036 Brasov (Romania); Crisan, A. [Department of Materials Science, Transylvania University, 500036 Brasov (Romania); Barradas, N.P.; Alves, E. [Instituto Superior Técnico, Universidade Técnica de Lisboa Estrada Nacional 10, ao km 139,7 2695-066, Bobadela LRS (Portugal); Moura, C.; Vaz, F. [Centro de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Cunha, L., E-mail: lcunha@fisica.uminho.pt [Centro de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2013-11-15

    The purpose of this work is to study the evolution of the structure and of the thermal stability of a group of tantalum oxynitride thin films, prepared by magnetron sputtering, under the influence of vacuum annealing, up to a temperature of 800 °C. When varying the partial pressure of the reactive gases (P{sub O{sub 2+N{sub 2}}}), during the deposition process, the films change from a structure with a combination of poorly developed crystallites of the tetragonal β-Ta and of the face centred cubic (fcc) Ta(O,N) phases, for the films deposited with low P{sub O2+N2}, to a quasi-amorphous structure, for the films deposited with highest pressures. For intermediate pressures, the films reveal the presence of the fcc-Ta(O,N) structure. This structure corresponds to O atoms substituting some of the N atoms on the fcc-TaN structure and/or N atoms substituting O atoms of the fcc-γ-TaO structure. When subjected to the thermal annealing at 700 °C or higher, the film produced with lowest partial pressure revealed a remarkable structural change. New diffraction peaks appear and can only be attributed to a sub-stoichiometric hexagonal tantalum nitride structure. The film did not reveal any signs of delamination or cracks after all annealing temperatures. The two films produced with highest partial pressure proved to be the most stable. Structurally, they maintain the amorphous structure after all the annealing treatments and, in addition, no cracks or delamination were detected.

  10. Fabrication and characterization of powder metallurgy tantalum components prepared by high compaction pressure technique

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Youngmoo [Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141 (Korea, Republic of); Agency for Defense Development, Yuseong, P.O. Box 35, Yuseong-gu, Daejeon 34186, Republic of Korea. (Korea, Republic of); Lee, Dongju [Korea Atomic Energy Research Institute, 111 Daedeok-daero, Yuseong-gu, Daejeon 34057 (Korea, Republic of); Hwang, Jaewon [Samsung Electronics, 129 Samsung-ro, Youngtong-gu, Suwon 16677 (Korea, Republic of); Ryu, Ho Jin, E-mail: hojinryu@kaist.ac.kr [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141 (Korea, Republic of); Hong, Soon Hyung, E-mail: shhong@kaist.ac.kr [Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141 (Korea, Republic of)

    2016-04-15

    The present study has investigated the consolidation behaviors of tantalum powders during compaction and sintering, and the characteristics of sintered components. For die compaction, the densification behaviors of the powders are simulated by finite element analyses based on the yield function proposed by Shima and Oyane. Accordingly, the green density distribution for coarser particles is predicted to be more uniform because they exhibits higher initial relative tap density owing to lower interparticle friction. It is also found that cold isostatic pressing is capable of producing higher dense compacts compared to the die pressing. However, unlike the compaction behavior, the sintered density of smaller particles is found to be higher than those of coarser ones owing to their higher specific surface area. The maximum sintered density was found to be 0.96 of theoretical density where smaller particles were pressed isostatically at 400 MPa followed by sintering at 2000 °C. Moreover, the effects of processing conditions on grain size and texture were also investigated. The average grain size of the sintered specimen is 30.29 μm and its texture is less than 2 times random intensity. Consequently, it is concluded that the higher pressure compaction technique is beneficial to produce high dense and texture-free tantalum components compared to hot pressing and spark plasma sintering. - Highlights: • Higher Ta density is obtained from higher pressure and sintering temperature. • High compaction method enables P/M Ta to achieve the density of 16.00 g·cm{sup −3}. • A P/M Ta component with fine microstructure and random orientation is developed.

  11. Structure dependent resistivity and dielectric characteristics of tantalum oxynitride thin films produced by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Cristea, D., E-mail: daniel.cristea@unitbv.ro [Department of Materials Science, Transilvania University, 500036 Brasov (Romania); Crisan, A. [Department of Materials Science, Transilvania University, 500036 Brasov (Romania); Cretu, N. [Electrical Engineering and Applied Physics Department, Transilvania University, 500036 Brasov (Romania); Borges, J. [Centro de Física, Universidade do Minho, Campus de Gualtar, 4710 - 057 Braga (Portugal); Instituto Pedro Nunes, Laboratório de Ensaios, Desgaste e Materiais, Rua Pedro Nunes, 3030-199 Coimbra (Portugal); SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); Lopes, C.; Cunha, L. [Centro de Física, Universidade do Minho, Campus de Gualtar, 4710 - 057 Braga (Portugal); Ion, V.; Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, “Photonic Processing of Advanced Materials” Group, PO Box MG-16, RO 77125 Magurele-Bucharest (Romania); Barradas, N.P. [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10 ao km 139,7, 2695-066 Bobadela LRS (Portugal); Alves, E. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10 ao km 139,7, 2695-066 Bobadela LRS (Portugal); Apreutesei, M. [MATEIS Laboratory-INSA de Lyon, 21 Avenue Jean Capelle, 69621 Villeurbanne cedex (France); Université de Lyon, Institut des Nanotechnologies de Lyon INL-UMR5270, CNRS, Ecole Centrale de Lyon, Ecully F-69134 (France); Munteanu, D. [Department of Materials Science, Transilvania University, 500036 Brasov (Romania)

    2015-11-01

    Highlights: • Tantalum oxynitride thin films have been deposited by magnetron sputtering, in various configurations. • The rising of the reactive gases mixture flow has the consequence of a gradual increase in the non-metallic content in the films, which results in a 10 orders of magnitude resistivity domain. • The higher resistivity films exhibit dielectric constants up to 41 and quality factors up to 70. - Abstract: The main purpose of this work is to present and to interpret the change of electrical properties of Ta{sub x}N{sub y}O{sub z} thin films, produced by DC reactive magnetron sputtering. Some parameters were varied during deposition: the flow of the reactive gases mixture (N{sub 2} and O{sub 2}, with a constant concentration ratio of 17:3); the substrate voltage bias (grounded, −50 V or −100 V) and the substrate (glass, (1 0 0) Si or high speed steel). The obtained films exhibit significant differences. The variation of the deposition parameters induces variations of the composition, microstructure and morphology. These differences cause variation of the electrical resistivity essentially correlated with the composition and structural changes. The gradual decrease of the Ta concentration in the films induces amorphization and causes a raise of the resistivity. The dielectric characteristics of some of the high resistance Ta{sub x}N{sub y}O{sub z} films were obtained in the samples with a capacitor-like design (deposited onto high speed steel, with gold pads deposited on the dielectric Ta{sub x}N{sub y}O{sub z} films). Some of these films exhibited dielectric constant values higher than those reported for other tantalum based dielectric films.

  12. Synthesis of chemical vapor deposition graphene on tantalum wire for supercapacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Li, Mingji, E-mail: limingji@163.com [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China); Guo, Wenlong [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China); Li, Hongji, E-mail: hongjili@yeah.net [Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384 (China); Xu, Sheng [School of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072 (China); Qu, Changqing; Yang, Baohe [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China)

    2014-10-30

    Highlights: • The capacitance of graphene/tantalum (Ta) wire electrodes is firstly reported. • Graphene was grown on the Ta surface by hot-filament chemical vapor deposition. • Graphene/Ta wire structure is favorable for fast ion and electron transfer. • The graphene/Ta wire electrode shows high capacitive properties. - Abstract: This paper studies the synthesis and electrochemical characterization of graphene/tantalum (Ta) wires as high-performance electrode material for supercapacitors. Graphene on Ta wires is prepared by the thermal decomposition of methane under various conditions. The graphene nanosheets on the Ta wire surface have an average thickness of 1.3–3.4 nm and consist typically of a few graphene monolayers, and TaC buffer layers form between the graphene and Ta wire. A capacitor structure is fabricated using graphene/Ta wire with a length of 10 mm and a diameter of 0.6 mm as the anode and Pt wire of the same size as the cathode. The electrochemical behavior of the graphene/Ta wires as supercapacitor electrodes is characterized by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy in 1 M Na{sub 2}SO{sub 4} aqueous electrolyte. The as-prepared graphene/Ta electrode has highest capacitance of 345.5 F g{sup −1} at current density of 0.5 A g{sup −1}. The capacitance remains at about 84% after 1000 cycles at 10 A g{sup −1}. The good electrochemical performance of the graphene/Ta wire electrode is attributed to the unique nanostructural configuration, high electrical conductivity, and large specific surface area of the graphene layer. This suggests that graphene/Ta wire electrode materials have potential applications in high-performance energy storage devices.

  13. Synthesis of chemical vapor deposition graphene on tantalum wire for supercapacitor applications

    International Nuclear Information System (INIS)

    Li, Mingji; Guo, Wenlong; Li, Hongji; Xu, Sheng; Qu, Changqing; Yang, Baohe

    2014-01-01

    Highlights: • The capacitance of graphene/tantalum (Ta) wire electrodes is firstly reported. • Graphene was grown on the Ta surface by hot-filament chemical vapor deposition. • Graphene/Ta wire structure is favorable for fast ion and electron transfer. • The graphene/Ta wire electrode shows high capacitive properties. - Abstract: This paper studies the synthesis and electrochemical characterization of graphene/tantalum (Ta) wires as high-performance electrode material for supercapacitors. Graphene on Ta wires is prepared by the thermal decomposition of methane under various conditions. The graphene nanosheets on the Ta wire surface have an average thickness of 1.3–3.4 nm and consist typically of a few graphene monolayers, and TaC buffer layers form between the graphene and Ta wire. A capacitor structure is fabricated using graphene/Ta wire with a length of 10 mm and a diameter of 0.6 mm as the anode and Pt wire of the same size as the cathode. The electrochemical behavior of the graphene/Ta wires as supercapacitor electrodes is characterized by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy in 1 M Na 2 SO 4 aqueous electrolyte. The as-prepared graphene/Ta electrode has highest capacitance of 345.5 F g −1 at current density of 0.5 A g −1 . The capacitance remains at about 84% after 1000 cycles at 10 A g −1 . The good electrochemical performance of the graphene/Ta wire electrode is attributed to the unique nanostructural configuration, high electrical conductivity, and large specific surface area of the graphene layer. This suggests that graphene/Ta wire electrode materials have potential applications in high-performance energy storage devices

  14. Structural changes and tribological behaviors of nitrogen ion-implanted tantalum

    International Nuclear Information System (INIS)

    Wang, W.J.; Wang, T.M.; Wang, X.J.

    1996-01-01

    Single-crystal tantalum sheets were implanted by 110 keV nitrogen ions to a dose of 5 x 10 17 ions/cm 2 at a temperature less than 100 C. The structural changes and the concentration depth profiles of the implanted layers were characterized by glancing-angle X-ray diffraction (GXRD), selected area diffraction (SAD) and Auger electron spectroscopy (AES), respectively. The microhardness, the friction coefficient and the wear rate of the specimens against hardened GCr15 steel balls were also determined before and after the implantation. Scanning electron microscopy (SEM) and electron probe micro-analyzer (EPMA) were used to analyze the wear tracks. The results showed that there exist deviations between the characterization results of AES and GXRD or SAD. The AES measurement suggests the formation of the tantalum nitrides with a maximum N/Ta ratio of 1/2, while the GXRD and SAD reveal the formation of bcc Ta(N), fcc TaN and a trace amount of hcp Ta 2 N. This can be explained by considering the inhomogeneous distribution of nitrogen atoms in micro-regions: the enrichment of nitrogen atoms in local micro-regions leads to the formation of fcc TaN; however, the unfavorable structural compatibility between bcc Ta and hcp Ta 2 N hinders the formation of hcp Ta 2 N in the regions where the N/Ta ratio reaches 1/2. The detected trace amount of the hcp Ta 2 N phase in the implanted layers can be considered as an after effect of nitrogen loss from the originally formed nitrides. The results also showed that the tribological properties of the Ta surfaces were improved due to the implantation. It is believed that the implantation-induced Ta(N), fcc TaN, and hcp Ta 2 N phases are responsible for this improvement. (orig.)

  15. Sol–gel synthesis of tantalum oxide and phosphonic acid-modified carbon nanotubes composite coatings on titanium surfaces

    International Nuclear Information System (INIS)

    Maho, Anthony; Detriche, Simon; Delhalle, Joseph; Mekhalif, Zineb

    2013-01-01

    Carbon nanotubes used as fillers in composite materials are more and more appreciated for the outstanding range of accessible properties and functionalities they generate in numerous domains of nanotechnologies. In the framework of biological and medical sciences, and particularly for orthopedic applications and devices (prostheses, implants, surgical instruments, …), titanium substrates covered by tantalum oxide/carbon nanotube composite coatings have proved to constitute interesting and successful platforms for the conception of solid and biocompatible biomaterials inducing the osseous regeneration processes (hydroxyapatite growth, osteoblasts attachment). This paper describes an original strategy for the conception of resistant and homogeneous tantalum oxide/carbon nanotubes layers on titanium through the introduction of carbon nanotubes functionalized by phosphonic acid moieties (-P(=O)(OH) 2 ). Strong covalent C-P bonds are specifically inserted on their external sidewalls with a ratio of two phosphonic groups per anchoring point. Experimental results highlight the stronger “tantalum capture agent” effect of phosphonic-modified nanotubes during the sol–gel formation process of the deposits compared to nanotubes bearing oxidized functions (-OH, -C=O, -C(=O)OH). Particular attention is also paid to the relative impact of the rate of functionalization and the dispersion degree of the carbon nanotubes in the coatings, as well as their wrapping level by the tantalum oxide matrix material. The resulting effect on the in vitro growth of hydroxyapatite is also evaluated to confirm the primary osseous bioactivity of those materials. Chemical, structural and morphological features of the different composite deposits described herein are assessed by X-ray photoelectron spectroscopy (XPS), scanning (SEM) and transmission (TEM) electronic microscopies, energy dispersive X-rays analysis (EDX) and peeling tests. Highlights: ► Formation of tantalum/carbon nanotube

  16. Sol–gel synthesis of tantalum oxide and phosphonic acid-modified carbon nanotubes composite coatings on titanium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Maho, Anthony [Laboratory of Chemistry and Electrochemistry of Surfaces, University of Namur (FUNDP), Rue de Bruxelles 61, B-5000 Namur (Belgium); Fonds pour la Formation à la Recherche dans l' Industrie et dans l' Agriculture (FRIA), Rue d' Egmont 5, B-1000 Bruxelles (Belgium); Detriche, Simon; Delhalle, Joseph [Laboratory of Chemistry and Electrochemistry of Surfaces, University of Namur (FUNDP), Rue de Bruxelles 61, B-5000 Namur (Belgium); Mekhalif, Zineb, E-mail: zineb.mekhalif@fundp.ac.be [Laboratory of Chemistry and Electrochemistry of Surfaces, University of Namur (FUNDP), Rue de Bruxelles 61, B-5000 Namur (Belgium)

    2013-07-01

    Carbon nanotubes used as fillers in composite materials are more and more appreciated for the outstanding range of accessible properties and functionalities they generate in numerous domains of nanotechnologies. In the framework of biological and medical sciences, and particularly for orthopedic applications and devices (prostheses, implants, surgical instruments, …), titanium substrates covered by tantalum oxide/carbon nanotube composite coatings have proved to constitute interesting and successful platforms for the conception of solid and biocompatible biomaterials inducing the osseous regeneration processes (hydroxyapatite growth, osteoblasts attachment). This paper describes an original strategy for the conception of resistant and homogeneous tantalum oxide/carbon nanotubes layers on titanium through the introduction of carbon nanotubes functionalized by phosphonic acid moieties (-P(=O)(OH){sub 2}). Strong covalent C-P bonds are specifically inserted on their external sidewalls with a ratio of two phosphonic groups per anchoring point. Experimental results highlight the stronger “tantalum capture agent” effect of phosphonic-modified nanotubes during the sol–gel formation process of the deposits compared to nanotubes bearing oxidized functions (-OH, -C=O, -C(=O)OH). Particular attention is also paid to the relative impact of the rate of functionalization and the dispersion degree of the carbon nanotubes in the coatings, as well as their wrapping level by the tantalum oxide matrix material. The resulting effect on the in vitro growth of hydroxyapatite is also evaluated to confirm the primary osseous bioactivity of those materials. Chemical, structural and morphological features of the different composite deposits described herein are assessed by X-ray photoelectron spectroscopy (XPS), scanning (SEM) and transmission (TEM) electronic microscopies, energy dispersive X-rays analysis (EDX) and peeling tests. Highlights: ► Formation of tantalum

  17. The physicochemical/biological properties of porous tantalum and the potential surface modification techniques to improve its clinical application in dental implantology

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yindong [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu (China); Bao, Chongyun, E-mail: cybao9933@scu.edu.cn [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu (China); Wismeijer, Daniel [Department of Oral Implantology and Prosthetic Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), MOVE Research Institute Amsterdam, VU University Amsterdam and University of Amsterdam, Amsterdam (Netherlands); Wu, Gang, E-mail: g.wu@acta.nl [Department of Oral Implantology and Prosthetic Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), MOVE Research Institute Amsterdam, VU University Amsterdam and University of Amsterdam, Amsterdam (Netherlands)

    2015-04-01

    More rapid restoration and more rigid functionality have been pursued for decades in the field of dental implantology. Under such motivation, porous tantalum has been recently introduced to design a novel type of dental implant. Porous tantalum bears interconnected porous structure with pore size ranging from 300 to 600 μm and a porosity of 75–85%. Its elastic modulus (1.3–10 GPa) more closely approximates that of natural cortical (12–18 GPa) and cancellous bone (0.1–0.5 GPa) in comparison with the most commonly used dental materials, such as titanium and titanium alloy (106–115 GPa). Porous tantalum is highly corrosion-resistant and biocompatible. It can significantly enhance the proliferation and differentiation of primary osteoblasts derived from elderly people than titanium. Porous tantalum can allow bone ingrowth and establish not only osseointegration but also osseoincorporation, which will significantly enhance the secondary stability of implants in bone tissue. In this review, we summarize the physicochemical, mechanical and biological properties of porous tantalum. We further discuss the performance of current tantalum dental implants and present the methodologies of surface modifications in order to improve their biological performance.

  18. The physicochemical/biological properties of porous tantalum and the potential surface modification techniques to improve its clinical application in dental implantology

    International Nuclear Information System (INIS)

    Liu, Yindong; Bao, Chongyun; Wismeijer, Daniel; Wu, Gang

    2015-01-01

    More rapid restoration and more rigid functionality have been pursued for decades in the field of dental implantology. Under such motivation, porous tantalum has been recently introduced to design a novel type of dental implant. Porous tantalum bears interconnected porous structure with pore size ranging from 300 to 600 μm and a porosity of 75–85%. Its elastic modulus (1.3–10 GPa) more closely approximates that of natural cortical (12–18 GPa) and cancellous bone (0.1–0.5 GPa) in comparison with the most commonly used dental materials, such as titanium and titanium alloy (106–115 GPa). Porous tantalum is highly corrosion-resistant and biocompatible. It can significantly enhance the proliferation and differentiation of primary osteoblasts derived from elderly people than titanium. Porous tantalum can allow bone ingrowth and establish not only osseointegration but also osseoincorporation, which will significantly enhance the secondary stability of implants in bone tissue. In this review, we summarize the physicochemical, mechanical and biological properties of porous tantalum. We further discuss the performance of current tantalum dental implants and present the methodologies of surface modifications in order to improve their biological performance

  19. 188Re-Labeled Nimotuzumab in the Locoregional Treatment of Malignant Gliomas

    International Nuclear Information System (INIS)

    Montana, R. Leyva; Barrabi, M. Zamora; Casaco, A.; Torres, L.; Perera, A.; Lopez, G.

    2009-01-01

    A new formulation of 188 Re-Nimotuzumab was developed to evaluate the biodistribution, internal radiation dosimetry and safety in the locoregional treatment of malignant gliomas. A phase I clinical trial was performed to evaluate the toxicity and clinical effect of an intracavitary administration of single dose of Nimotuzumab labeled with 188 Re. Nimotuzumab is a humanized monoclonal antibody directed against epidermal growth factor receptors. Nine patients with anaplastic astrocytoma or glioblastoma multiforme were intended to be treated with 3 mg of mAb labeled with 10 or 15 mCi of 188 Re. The radioimmunoconjugated showed a high retention in the surgical created resection cavity and the brain adjacent tissues with a mean value of 85.5% of the injected dose one hour post- administration. No patient developed human anti-mouse antibody response. This radioimmunoconjugate may be relatively safe and a promising therapeutic approach for treating high grade gliomas. (author)

  20. Pitfalls in Using Limitation Clauses in the International General Conditions ECE 188 and Orgalime S 2000

    DEFF Research Database (Denmark)

    Henschel, Rene Franz

    2008-01-01

    various individual provisions contained in the general conditions - for example limitation of the right to require repair and further limitation of liability. If this is not motivated by the circumstances surrounding the particular contract, the parties risk creating imbalances in the otherwise well-balanced......The article centers on the rules on the limitation of liability in the general conditions ECE 188 and Orgalime S 2000. ECE 188 differ considerably from S 2000, as the provisions in ECE 188 do not give the necessary consideration to the development in industry practices and legal rules, including...... the approximation and harmonization of legal systems that have taken place during the last 50 years. S 2000 reflects an international trend that increasingly recognizes the importance of striking a balance between the interests of the parties. However, in practice the parties often derogate considerably from...

  1. Comparative studies of antibody anti-CD20 labeled with 188Re

    International Nuclear Information System (INIS)

    Dias, Carla Roberta de Barros Rodrigues

    2010-01-01

    Nuclear Medicine is an unique and important modality in oncology and the development of new tumor-targeted radiopharmaceuticals for both diagnosis and therapy is an area of interest for researchers. Rituximab (RTX) is a quimeric monoclonal antibody (mAb) (IgG 1) that specifically binds to CD20 antigen with high affinity and has been successfully used for the treatment of Non-Hodgkin Lymphoma (NHL) of cell B. The CD20 antigen is expressed over more than 90% of cell B NHL. Technetium-99m ( 99m Tc) and rhenium-188 ( 188 Re) are an attractive radionuclide pair for clinical use due to their favorable decay properties for diagnosis ( 99m Tc: T 1/2 = 6 h, γ radiation = 140 keV) and therapy ( 188 Re: T 1/2 = 17 h, maximum β energy = 2.12 MeV) and to their availability in the form of 99 Mo/ 99 mTc and 188 W/ 188 Re generators. The radionuclides can be conjugated to mAb using similar chemical procedures. The aim of this work was to study the labeling of anti-CD20 mAb (RTX) with 188 Re using two techniques: the direct labeling method [ 188 Re(V)] and the labeling method via the carbonyl nucleus [ 188 Re(I)]. Besides the quality control, the radiolabeled mAb was submitted to in vivo, in vitro and ex vivo biological studies. For the direct labeling, RTX was reducing by incubation with 2-mercaptoethanol for generating sulphydryl groups (-SH) and further labeled with 188 Re(V), in a study of several parameters in order to reach an optimized formulation. The labeling via the carbonyl nucleus both 99 mTc and 188 Re were employed through 2 different procedures: (1) labeling of intact RTX with 99 mTc(I) and (2) reduced RTX (RTX red ) labeled with 99 mTc(I)/ 188 Re(I). Also a parameter study was performed to obtain an optimized formulation. The quality control method for evaluating the radiochemical purity showed a good labeling yield (93%) for the direct method. The labeling method via carbonyl group, the results showed that the - SH groups of RTX red are a possible way of labeling

  2. Investigations of labeling insulin-like growth factor-1 analogue with 188Re

    International Nuclear Information System (INIS)

    Zhang Bin; Wu Yiwei; Fan Wo

    2007-01-01

    Objective: To establish a stable method for labeling insulin-like growth factor-1 analogue (IGF-1A) with 188 Re. Methods: The directly labeling method was adopted. Several labeling conditions were tested, such as the volume of Tween-80, the concentration of SnCl 2 ·2H 2 O, the amount of IGF-1A, and the volume of 188 Re perrhenate. The labeling efficiency was determined from 15 min to 8 h after labeling. The in vitro stability of 188 Re-IGF-1A was analyzed by using human serum or sodium chloride as challenging agent, and the labeling efficiency was determined from 2 to 24 h after added challenging agent. Results: The optimum labeling conditions were 10 μl 0.1% Tween-80, 100 μl SnCl 2 · 2H 2 O (10 mg/ml), 50 μl IGF-1A (2 mg/ml), and 50 μl 188 Re perrhenate, incubated 30 min at room temperature. The labeling efficiency of 188 Re-IGF-1A could reach (94.07 ± 0.32)% and the amount of radiocolloid was (5.50 ± 1.50)%. It was (89.07 ± 0.74)% after incubation for 6 h at room temperature, and was (76.57 ± 9.96)% after incubation for 24 h with human serum. Conclusion: This method of labeling IGF- 1A with 188 Re using SnCl 2 ·2H 2 O is stable and high labeling efficiency can be obtained. (authors)

  3. Labeling of MDP with {sup 188}Re for bone tumour therapy

    Energy Technology Data Exchange (ETDEWEB)

    Barbezan, Angelica B.; Osso Junior, Joao A., E-mail: jaosso@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    {sup 188}Re is one of the most attractive radioisotopes for a variety of therapeutic applications in nuclear medicine, due to its physical decay properties, such as {beta}{sup -} emission of 2.12 MeV, {gamma} emission of 155 keV and half life of 16.9 hours. Biphosphonates are potent inhibitors of osteoclastic bone resorption and are effective in several diseases that cause bone fragility and bone metastases. Because of these characteristics, labeled biphosphonates have been studied for bone pathologies, also acting as palliation of bone pain in case of metastasis.The aim of this study was to optimize the labeling of a phosphonate-MDP (Sodium Methylene Diphosphonate) with {sup 188}Re for use in bone pain palliation. {sup 188}Re was obtained by eluting a {sup 188}W-{sup 188}Re generator from POLATOM. The labeling was performed at room temperature using MDP, SnCl{sub 2} as reducing agent and ascorbic acid. The variables studied were: Mass of ligand (3, 6 and 10 mg), reducing agent mass (5, 7, 10 and 11 mg), ascorbic acid mass (1, 3, 5 and 6 mg), pH (1 and 2) and time of reaction (15, 60, 120, 360 and 4320 minutes), that also reflected the stability of the radiopharmaceutical. The radiochemical control, that also measures the labeling efficiency was evaluated by paper chromatography using Whatman 3MM paper and the solvents acetone and 0.9%NaCl. The best formulation was the following: Mass of ligand MDP: 10 mg, mass of SnCl{sub 2}: 5 mg, ascorbic acid mass: 3 mg, time of reaction: 30 minutes, pH: 1. Under optimum conditions, {sup 188}Re MDP radiolabeling yield was 98,07% and the radiopharmaceutical was stable up to 72 h. (author)

  4. Automation of labelling of Lipiodol with high-activity generator-produced 188Re

    International Nuclear Information System (INIS)

    Lepareur, Nicolas; Ardisson, Valerie; Noiret, Nicolas; Boucher, Eveline; Raoul, Jean-Luc; Clement, Bruno; Garin, Etienne

    2011-01-01

    This work describes optimisation of the kit formulation for labelling of Lipiodol with high-activity generator-produced rhenium-188. Radiochemical purity (RCP) was 92.52±2.3% and extraction yield was 98.56±1.2%. The synthesis has been automated with a TADDEO module (Comecer) giving a mean final yield of 52.68±9.6%, and reducing radiation burden to the radiochemist by 80%. Radiolabelled Lipiodol ( 188 Re-SSS/Lipiodol) is stable for at least 7 days (RCP=91.07±0.9%).

  5. Optimization of labelling procedure of {sup 188}rE-DMSA(v)

    Energy Technology Data Exchange (ETDEWEB)

    Dantas, Danielle M.; Brambilla, Tania P.; Reis, Nicoli F.; Osso Junior, Joao A., E-mail: jaosso@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Radionuclide therapy (RNT) is emerging as an important tool of nuclear medicine. Apart from the well established {sup 131}I, several other promising radionuclides have been identified, among them {sup 188}Re, {sup 90}Y and {sup 177}Lu. {sup 188}Re has received a lot of attention in the past decade, due to its favourable nuclear characteristics [t{sub 1/2} 16.9 h, E{sub b}eta{sub m}ax 2.12 MeV and E{sub g}amma 155 keV (15%) suitable for imaging, including the fact that it is carrier-free and can be obtained cost-effectively through the generator {sup 188}W-{sup 188}Re. Biodistribution studies of {sup 188}Re-DMSA(V) have shown that its general pharmacokinetic properties are similar to that of {sup 99m}Tc-DMSA(V), so this agent could be used for targeted radiotherapy of medullary thyroid carcinoma, bone metastases, soft tissue and others tumors. The aim of this work is to evaluate two labeling procedures for the preparation of {sup 188}Re-DMSA(V). The first method was prepared using a commercial kit of DMSA(III) for labeling with {sup 99m}Tc at high temperature (100 deg C). The second method was prepared in a vial containing 2.5 mg of DMSA, 1.00 mg of SnCl{sub 2}.2H{sub 2}O and 10 mg of sodium oxalate, 10 mg of cyclodextrin, in a total volume of 2.0 mL. The pH was adjusted to 3 with 37% HCl. After labeling the solution was stirred and incubated for 30 min at room temperature. The radiochemical purity was determined using TLC-SG developed with two different solvent systems: Acetone and glycine. Preliminary results for both methods of labeling {sup 188}Re-DMSA(V) showed that the labeling yield was >95%. Further experiments are also necessary to optimize the labeling methodology of {sup 188}Re-DMSA(V).author)

  6. Radiolabeling of rituximab with 188Re and 99mTc using the tricarbonyl technology

    International Nuclear Information System (INIS)

    Dias, Carla Roberta; Jeger, Simone; Osso, Joao Alberto; Mueller, Cristina; De Pasquale, Christine; Hohn, Alexander; Waibel, Robert; Schibli, Roger

    2011-01-01

    Introduction: The most successful clinical studies of immunotherapy in patients with non-Hodgkin's lymphoma (NHL) use the antibody rituximab (RTX) targeting CD20 + B-cell tumors. Rituximab radiolabeled with β - emitters could potentiate the therapeutic efficacy of the antibody by virtue of the particle radiation. Here, we report on a direct radiolabeling approach of rituximab with the 99m Tc- and 188 Re-tricarbonyl core (IsoLink technology). Methods: The native format of the antibody (RTX wt ) as well as a reduced form (RTX red ) was labeled with 99m Tc/ 188 Re(CO) 3 . The partial reduction of the disulfide bonds to produce free sulfhydryl groups (-SH) was achieved with 2-mercaptoethanol. Radiolabeling efficiency, in vitro human plasma stability as well as transchelation toward cysteine and histidine was investigated. The immunoreactivity and binding affinity were determined on Ramos and/or Raji cells expressing CD20. Biodistribution was performed in mice bearing subcutaneous Ramos lymphoma xenografts. Results: The radiolabeling efficiency and kinetics of RTX red were superior to that of RTX wt ( 99m Tc: 98% after 3 h for RTX red vs. 70% after 24 h for RTX wt ). 99m Tc(CO) 3 -RTX red was used without purification for in vitro and in vivo studies whereas 188 Re(CO) 3 -RTX red was purified to eliminate free 188 Re-precursor. Both radioimmunoconjugates were stable in human plasma for 24 h at 37 o C. In contrast, displacement experiments with excess cysteine/histidine showed significant transchelation in the case of 99m Tc(CO) 3 -RTX red but not with pre-purified 188 Re(CO) 3 -RTX red . Both conjugates revealed high binding affinity to the CD20 antigen (K d =5-6 nM). Tumor uptake of 188 Re(CO) 3 -RTX red was 2.5 %ID/g and 0.8 %ID/g for 99m Tc(CO) 3 -RTX red 48 h after injection. The values for other organs and tissues were similar for both compounds, for example the tumor-to-blood and tumor-to-liver ratios were 0.4 and 0.3 for 99m Tc(CO) 3 -RTX red and for 188 Re

  7. Quadrupole moments of the 12+ isomers in 188Hg and 190Hg

    International Nuclear Information System (INIS)

    Dracoulis, G.D.; Lonnroth, T.; Vajda, S.; Dafni, E.; Schatz, G.

    1984-01-01

    The electric quadrupole interaction of the 12 + isomers in 188 Hg and 190 Hg has been measured in solid Hg. The quadrupole moments deduced, vertical strokeQ[ 188 Hg(12 + )]vertical stroke = 91(11) e fm 2 and vertical strokeQ[ 190 Hg(12 + )]vertical stroke = 117(14) e fm 2 suggest a possible change in γ-deformation due to the rotation alignment of the isub(13/2) quasi-neutrons. The temperature dependence of the electric field gradient tensor in Hg was also determined. (orig.)

  8. Study on therapy of 188Re labelled stannic sulfur suspension in nude mice bearing human colon tumor

    International Nuclear Information System (INIS)

    Li Huiyuan; Wu Yuanfang; Dong Mo

    2003-01-01

    The effect of therapy, tissue distribution and stability are studied in nude mice bearing human colon tumor after injections of 188 Re labelled stannic sulfur suspension. The tissues are observed with electric microscope. The results show that 188 Re labelled stannic sulfur suspension is stabilized in the tumor and its inhibitive effects on human colon tumor cells are obvious. 188 Re labelled stannic sulfur suspension is a potential radiopharmaceuticals for therapy of human tumor

  9. Conflict minerals in the compute sector: estimating extent of tin, tantalum, tungsten, and gold use in ICT products.

    Science.gov (United States)

    Fitzpatrick, Colin; Olivetti, Elsa; Miller, Reed; Roth, Richard; Kirchain, Randolph

    2015-01-20

    Recent legislation has focused attention on the supply chains of tin, tungsten, tantalum, and gold (3TG), specifically those originating from the eastern part of the Democratic Republic of Congo. The unique properties of these so-called “conflict minerals” lead to their use in many products, ranging from medical devices to industrial cutting tools. This paper calculates per product use of 3TG in several information, communication, and technology (ICT) products such as desktops, servers, laptops, smart phones, and tablets. By scaling up individual product estimates to global shipment figures, this work estimates the influence of the ICT sector on 3TG mining in covered countries. The model estimates the upper bound of tin, tungsten, tantalum, and gold use within ICT products to be 2%, 0.1%, 15%, and 3% of the 2013 market share, respectively. This result is projected into the future (2018) based on the anticipated increase in ICT device production.

  10. Influence of laser alloyed layer of carbon steel with tantalum on the structure and surface layer properties

    International Nuclear Information System (INIS)

    Woldan, A.; Kusinski, J.; Kac, S.

    1999-01-01

    The paper describes the microstructure and properties (chemical composition and microhardness) of the surface laser alloyed layer with tantalum. The surface alloyed zones varied in microstructure, zones depth and width, as well as Ta content according to the thickness of the coated layer, bonding paint type and process parameters (power and scanning velocity). The electron microprobe analysis of melts showed that higher tantalum content in the melted zone resulted from the thicker original Ta coating as well as slower scanning velocity. Scanning electron microscopy examinations show that dendritic structure of the melted zone becomes evident when carbon was used as one of the components of the binder, while structure is typically martensitic when silicon containing binder was used for powder deposition. Samples covered with Ta and carbon containing binder showed after laser alloying higher hardness than in case of using silicon containing binder. (author)

  11. Elasticity of Tantalum to 105 Gpa using a stress and angle-resolved x-ray diffraction

    International Nuclear Information System (INIS)

    Cynn, H; Yoo, C S

    1999-01-01

    Determining the mechanical properties such as elastic constants of metals at Mbar pressures has been a difficult task in experiment. Following the development of anisotropic elastic theory by Singh et al.[l], Mao et a1.[2] have recently developed a novel experimental technique to determine the elastic constants of Fe by using the stress and energy-dispersive x-ray diffraction (SEX). In this paper, we present an improved complementary technique, stress and angle-resolved x-ray diffraction (SAX), which we have applied to determine the elastic constants of tantalum to 105 GPa. The extrapolation of the tantalum elastic data shows an excellent agreement with the low-pressure ultrasonic data[3]. We also discuss the improvement of this SAX method over the previous SEX.[elastic constant, anisotropic elastic theory, angle-dispersive synchrotron x-ray diffraction, mechanical properties

  12. Extraction - spectrophotometric determination of tantalum (V) with 2-(2-thiazolylazo)-5-dimethylaminophenol and 1,3-diphenylguanidine

    International Nuclear Information System (INIS)

    Tsurumi, C.; Furuya, K.; Kamada, H.

    1981-01-01

    Tantalum(V)-2-(2-thiazolylazo)-5-dimethylaminophenol (TAM) chelate anion is extracted quantitatively into benzyl alcohol with 1,3-diphenylguanidine (DPG) to form a ternary complex. In the organic phase, the complex has an absorption maximum at 605 nm. The optimum pH range for the extraction is 4.1 to 4.9 and the ternary complex is stable for at least 50 min. Beer's law is obeyed over a concentration range of 2 to 18 μg of tantalum(V) in 10 ml of the organic phase. The molar absorptivity of the ternary complex is 4.1 x 10 4 l mol -1 at 605 nm. The composition of the ternary complex is considered to be (TaO 2 ) 2 (TAM) 3 (DPG + ). (author)

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

    Science.gov (United States)

    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

  14. Corrosion studies of tantalum in oxidizing media - intercomparison of data obtained in model media and in a test facility

    International Nuclear Information System (INIS)

    Vehlow, J.; Wieczorek, H.

    1989-01-01

    The suitability of tantalum as a material for wet incineration of combustible wastes has been tested in model mixtures of sulfuric and nitric acid at about 250deg C. In addition parts of a semi-technical test facility have been investigated, which had been in operation for more than 3000 h. In general there is good correspondence between predicted wall losses and those found under real conditions. (orig.) [de

  15. In situ production of tantalum carbide nanodispersoids in a copper matrix by reactive milling and hot extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Manotas-Albor, Milton, E-mail: manotasm@uninorte.edu.co [Grupo de Investigación en Física Aplicada, Departamento de Física, Universidad del Norte, Km. 5 vía a Puerto Colombia, Barranquilla (Colombia); Departamento de Ingeniería Mecánica, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Beauchef 850, Santiago (Chile); Vargas-Uscategui, Alejandro [Laboratorio de Materiales a Nanoescala, Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Tupper Av. 2069, Santiago (Chile); Palma, Rodrigo [Departamento de Ingeniería Mecánica, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Beauchef 850, Santiago (Chile); Mosquera, Edgar [Laboratorio de Materiales a Nanoescala, Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Tupper Av. 2069, Santiago (Chile)

    2014-06-15

    Highlights: • Tantalum carbide nanodispersoids were obtained in a copper matrix. • Nanodispersoids were obtained by means of reactive milling followed by hot extrusion. • Hexane was used as the liquid medium for the reactive mechanical alloying process. • Hexane provides the carbon (C) needed for the process. • The reaction of tantalum carbide formation takes place in the hot extrusion. - Abstract: This paper presents a study of the in situ production of tantalum carbide nanodispersoids in a copper matrix. The copper matrix composites were produced by means of reactive milling in hexane (C{sub 6}H{sub 14}) followed by hot extrusion. The composite materials were characterized by means of optical emission spectroscopy (OES), X-ray fluorescence (XRF), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Vickers micro-hardness. The effect of milling time was analyzed in 10, 20 and 30 h in a composite with a nominal composition Cu–5 vol.% TaC. A systematic increase of the dislocations density and the carbon concentration were observed when the milling time was increased, whereas the crystallite size of the composite matrix decreased. The material milled for 30 h and hot-extruded showed a density of 9037 kg m{sup −3} (98.2% densification) and a softening resistance of 204 HV; however the latter value showed an abrupt drop after an annealing treatment at 923 K for 1 h. Finally, the TEM analysis showed the presence of tantalum carbide (Ta{sub 4}C{sub 3}) nanodispersoids.

  16. The effect of yttrium addition on oxidation of a sputtered nanocrystalline coating with moderate amount of tantalum in composition

    International Nuclear Information System (INIS)

    Wang, Jinlong; Chen, Minghui; Yang, Lanlan; Liu, Li; Zhu, Shenglong; Wang, Fuhui; Meng, Guozhe

    2016-01-01

    Graphical abstract: - Highlights: • Effect of Y addition on oxidation of nanocrystalline coating is studied. • Y addition delays transformation of q-Al_2O_3 to a-Al_2O_3 during oxidation. • Y addition prevents scale rumpling. • Y segregates at grain boundaries of the nanocrystalline coating. • Y retards the transportation of Ta thus reduces its oxidation. - Abstract: The effect of yttrium addition on isothermal oxidation at 1050 °C of a sputtered nanocrystalline coating with moderate amount of tantalum in composition was investigated. Results indicate that yttrium addition delays transformation of metastable θ-Al_2O_3 to equilibrium α-Al_2O_3 grown on the nanocrystalline coatings. It prevents scale rumpling and promotes the formation of oxide pegs at interface between the oxide scale and the underlying coating. Besides, yttrium prefers to segregate at grain boundaries of the nanocrystalline coating and retards the outward transportation of tantalum from coating to oxide scale, thus reducing the excessive oxidation of tantalum.

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

    Science.gov (United States)

    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.

  18. Effect of tungsten and tantalum on the low cycle fatigue behavior of reduced activation ferritic/martensitic steels

    Energy Technology Data Exchange (ETDEWEB)

    Shankar, Vani, E-mail: vani@igcar.gov.in [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Mariappan, K.; Nagesha, A.; Prasad Reddy, G.V.; Sandhya, R.; Mathew, M.D.; Jayakumar, T. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Effect of tungsten and tantalum on low cycle fatigue behavior of RAFM steels. Black-Right-Pointing-Pointer Both alloying elements W and Ta improved fatigue life. Black-Right-Pointing-Pointer Increase in Ta content improved fatigue life more than W. Black-Right-Pointing-Pointer Optimization of W content at 1.4 wt.%. Black-Right-Pointing-Pointer Softening behavior closely related to W and Ta content. - Abstract: Reduced activation ferritic/martensitic (RAFM) steels are candidate materials for the test blanket modules of International Thermonuclear Experimental Reactor (ITER). Several degradation mechanisms such as thermal fatigue, low cycle fatigue, creep fatigue interaction, creep, irradiation hardening, swelling and phase instability associated irradiation embrittlement must be understood in order to estimate the component lifetime and issues concerning the structural integrity of components. The current work focuses on the effect of tungsten and tantalum on the low cycle fatigue (LCF) behavior of RAFM steels. Both alloying elements tungsten and tantalum improved the fatigue life. Influence of Ta on increasing fatigue life was an order of magnitude higher than the influence of W on improving the fatigue life. Based on the present study, the W content was optimized at 1.4 wt.%. Softening behavior of RAFM steels showed a strong dependence on W and Ta content in RAFM steels.

  19. Structural and photoluminescent properties of a composite tantalum oxide and silicon nanocrystals embedded in a silicon oxide film

    International Nuclear Information System (INIS)

    Díaz-Becerril, T.; Herrera, V.; Morales, C.; García-Salgado, G.; Rosendo, E.; Coyopol, A.; Galeazzi, R.; Romano, R.; Nieto-Caballero, F.G.; Sarmiento, J.

    2017-01-01

    Tantalum oxide crystals encrusted in a silicon oxide matrix were synthesized by using a hot filament chemical vapor deposition system (HFCVD). A solid source composed by a mixture in different percentages of Ta 2 O 5 and silicon (Si) powders were used as reactants. The films were grown at 800 °C and 1000 °C under hydrogen ambient. The deposited films were characterized by X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and photoluminescence (PL) at room temperature. From the XPS results it was confirmed the formation of a mixture of Tantalum oxide, silicon oxide and Si nanoparticles (Ta 2 O 5- SiO 2 -Si(nc)) as seen from the Si (2p) and Ta (4f) lines corresponding to Si + and Ta + states respectively. Ta 2 O 5 and Si nanocrystals (Si-NCs) embedded in the silicon oxide films were observed on HRTEM images which corroborate the XPS results. Finally the emission properties of the films exhibited a broad band from 400 to 850 nm caused by the independent PL properties of tantalum oxide and Si-NCs that compose the film. The intensity of the emissions was observed to be dependent on both temperature of deposition and the ratio Ta 2 O 5 /Si, used as initial reactants. Results from this work might supply useful data for the development of future light emitter devices.

  20. Activation of human leukocytes on tantalum trabecular metal in comparison to commonly used orthopedic metal implant materials.

    Science.gov (United States)

    Schildhauer, T A; Peter, E; Muhr, G; Köller, M

    2009-02-01

    We analyzed leukocyte functions and cytokine response of human leukocytes toward porous tantalum foam biomaterial (Trabecular Metaltrade mark, TM) in comparison to equally sized solid orthopedic metal implant materials (pure titanium, titanium alloy, stainless steel, pure tantalum, and tantalum coated stainless steel). Isolated peripheral blood mononuclear cells (PBMC) and polymorphonuclear neutrophil leukocytes (PMN) were cocultured with equally sized metallic test discs for 24 h. Supernatants were analyzed for cytokine content by enzyme-linked immunosorbent assay. Compared to the other used test materials there was a significant increase in the release of IL (interleukin)-1ra and IL-8 from PMN, and of IL-1ra, IL-6, and TNF-alpha from PBMC in response to the TM material. The cytokine release correlated with surface roughness of the materials. In contrast, the release of IL-2 was not induced showing that mainly myeloid leukocytes were activated. In addition, supernatants of these leukocyte/material interaction (conditioned media, CM) were subjected to whole blood cell function assays (phagocytosis, chemotaxis, bacterial killing). There was a significant increase in the phagocytotic capacity of leukocytes in the presence of TM-conditioned media. The chemotactic response of leukocytes toward TM-conditioned media was significantly higher compared to CM obtained from other test materials. Furthermore, the bactericidal capacity of whole blood was enhanced in the presence of TM-conditioned media. These results indicate that leukocyte activation at the surface of TM material induces a microenvironment, which may enhance local host defense mechanisms.

  1. Multifunctional hybrid coating on titanium towards hydroxyapatite growth: Electrodeposition of tantalum and its molecular functionalization with organophosphonic acids films

    International Nuclear Information System (INIS)

    Arnould, Christelle; Delhalle, Joseph; Mekhalif, Zineb

    2008-01-01

    Titanium and its alloys are base materials used in the dental and orthopaedic fields owing to suitable intrinsic properties: good biocompatibility, high corrosion resistance and excellent mechanical properties. However, the bonding between titanium and bone tissue is not always strong enough and can become a critical problem. In this context, the two main objectives of this paper are the increase of the corrosion resistance and the improvement of the hydroxyapatite (HAp) growth. The surface modification considered here is achieved in three main steps and consists in the elaboration of different inorganic and organic coatings. The first step is the elaboration of electrodeposition of tantalum on the titanium oxide film of a titanium substrate. The second step is the modification of the tantalum oxide coating with organophosphonic acids. The last step is the nucleation and growth of HAP on the outermost layer of the system by immersion in a simulated body fluid. The hybrid coating tantalum oxide/organophosphonic acids/molecular layer is shown to be promising for orthopaedic implants

  2. Preliminary study of metabolic radiotherapy with 188Re via small animal imaging

    International Nuclear Information System (INIS)

    Antoccia, A.; Baldazzi, G.; Bello, M.

    2006-01-01

    188 Re is a β - (Emax=2.12 MeV) and γ (155 keV) emitter. Since its chemistry is similar to that of the largely employed tracer, 99m Tc, molecules of hyaluronic acid (HA) have been labelled with 188 Re to produce a target specific radiopharmaceutical. The radiolabeled compound, i.v. injected in healthy mice, is able to accumulate into the liver after a few minutes. To study the effect of metabolic radiotherapy in mice, we have built a small gamma camera based on a matrix of YAP:Ce crystals, with 0.6x0.6x10 mm 3 pixels, read out by a R2486 Hamamatsu PSPMT. A high-sensitivity 20 mm thick lead parallel-hole collimator, with hole diameter 1.5 mm and septa of 0.18 mm, is placed in front of the YAP matrix. Preliminary results obtained with various phantoms containing a solution of 188 Re and with C57 black mice injected with the 188 Re-HA solution are presented. To increase the space resolution and to obtain two orthogonal projections simultaneously we are building in parallel two new cameras to be positioned at 90 degrees. They use a CsI(Tl) matrix with 1x1x5 mm 3 pixels read out by H8500 Hamamatsu Flat panel PMT

  3. 31 CFR 103.188 - Special measures against Commercial Bank of Syria.

    Science.gov (United States)

    2010-07-01

    ... Programs Law Enforcement Access to Foreign Bank Records § 103.188 Special measures against Commercial Bank of Syria. (a) Definitions. For purposes of this section: (1) Commercial Bank of Syria means any branch, office, or subsidiary of Commercial Bank of Syria operating in Syria or in any other jurisdiction...

  4. 18 CFR 367.1880 - Account 188, Research, development, or demonstration expenditures.

    Science.gov (United States)

    2010-04-01

    ... 188, Research, development, or demonstration expenditures. (a) This account must be charged with the cost of all expenditures coming within the meaning of research, development and demonstration (RD&D) of..., development, and demonstration expenditures that are nonrecurring and that would distort the annual research...

  5. Study of radiation synovectomy using 188Re-sulfide in hemophilic arthritis

    International Nuclear Information System (INIS)

    Li, P.Y.; Cheng, G.; Jiang, X.F.; Wang, X.F.; Shen, Z.M.; Zhang, Z.H.

    2002-01-01

    Purpose: Based on results of previous animal studies, the efficacy of 188 Re-sulfide on radiation synovectomy in hemophilia synovitis.was evaluated. Material and Methods: 188 Re-sulfide suspension was produced by dispersion method. 25 hemophilic patients with 30 synovitic joints including 22 knees and 8 ankles received the radiation synovectomy. The stage of synovitic joint was classified by joint score including the pain, stability and range of motion and MR score. The doses of 188 Re-sulfide injected into knee and ankle were determined as 12mCi and 6mCi respectively, according to the depth and curve and the results of our previous animal study. To exam the distribution of 188 Re-sulfide in vivo after the injection, a whole-body scan was taken 24 and 48 hours later to calculate the retention of 188 Re-sulfide in joint by percentage of join counts in whole body. The follow up was take place at 6-12 months after the synovectomy by joint score, MRI score, synovial structure, the times and interval of hemorrhage of the joints. Results: Few patients complained discomfort after the injection such as hurt of the superficial tissues around the injected point and swelling (2 patients,.8%).The symptoms in this two patients continued up to 3 days and gradually decreased in severity. All patients felt relief of the pain and swelling in joints. 90% joints including 20 knees and 7 ankles did not bleed any more during the 3-month term of follow up, 3 joints from 2 patients with intra-article bleeding had hemorrhage in one month after long distance walk. 16%(5/30) of joints including 4 knees and 1 ankles had recurrent hemorrhage in 12 months after the radiation synovectomy. However, their interval of intra-article bleeding was prolonged MRI showed the thick synovium became thin, villi reduced and the joint edema relieved. The retention of 188 Re-sulfide in administrated joint was more than 95% until 48 hours later. No any sign of radioactive distribution was found in bone marrow

  6. MAG2GABA-biocytin synthesized with new intermediates for radiolabelling 99mTc and 188Re

    International Nuclear Information System (INIS)

    Ahn, S.H.; Choi, T.H.; Choi, C.W.; Yang, S.D.; Woo, K.S.; Chung, W.S.; Lim, S.M.

    2001-01-01

    188 Re from 188 W- 188 Re generator, is recently introduced in therapeutic nuclear medicine and made it possible to use whenever needed. We synthesized MAG 2 GABA-Biocytin (MGB), labelled with 188 Re for pretargeted radioimmunotherapy and evaluated biological behavior of 188 Re-MGB. N-hydroxysuccinimidyl ester of S-benzoyl mercaptoacetyldiglycine (NHS-MAG 2 ) was synthesized first, reacted with aminobutyric acid(GABA) to give MAG 2 GABA and then converted to NHS-MAG 2 GABA and conjugated to biocytin to give the MGB. To label MGB with 188 Re (50mA), ag, 200ml 1M tartrate pH7, 200 l stannous (10mg/mL) and 180MBq perrhenate were mixed and heated for 30min at 100 deg. C. The reactant was purified with C 18 Sep-Pak. HPLC analysis of the 188 Re-MGB performed on reverse phase C 18 column with a gradient. To see the stability, 188 Re-MGB was added to serum at 37 deg. C. Binding capacity of 188 Re-MGB to avidin or streptavidin was determined by size exclusion HPLC system. Biodistribution was studied in ICR normal mice(n=4/group), from 5min to 120min. In Raji cells tumour bearing nude mice(n=3), biotinylated Lym-1(40MEG) injection after 48 h, streptavidin(50MEG) was injected. 24 h later, 188 Re-MGB(0.5MEG) was injected, and biodistribution was observed 2 h later. 188 Re-MGB was obtained with labelling yield 98%. Stability in serum was maintained over 70% until 3 h. Binding capacity of 188 Re-MGB to streptavidin was greater than avidin. In normal mice, 188 Re-MGB was excreted via hepatobiliary pathway,%ID/g of GI tract was 52.1 at 120min. In Raji cells tumour bearing nude mice, liver and colon were higher than those of normal mouse. Tumour uptake at 120min was 0.05%ID/g. 188 Re-MGB was effectively labelled and retained binding activity with streptavidin. 188 Re-MGB may have a role in pretargeted radioimmunotherapy. (author)

  7. Chronic Dosing with Membrane Sealant Poloxamer 188 NF Improves Respiratory Dysfunction in Dystrophic Mdx and Mdx/Utrophin-/- Mice.

    Directory of Open Access Journals (Sweden)

    Bruce E Markham

    Full Text Available Poloxamer 188 NF (national formulary (NF grade of P-188 improves cardiac muscle function in the mdx mouse and golden retriever muscular dystrophy models. However in vivo effects on skeletal muscle have not been reported. We postulated that P-188 NF might protect diaphragm muscle membranes from contraction-induced injury in mdx and mdx/utrophin-/- (dko muscular dystrophy models. In the first study 7-month old mdx mice were treated for 22 weeks with subcutaneous (s.c. injections of saline or P-188 NF at 3 mg/Kg. In the second, dkos were treated with saline or P-188 NF (1 mg/Kg for 8 weeks beginning at age 3 weeks. Prednisone was the positive control in both studies. Respiratory function was monitored using unrestrained whole body plethysmography. P-188 NF treatment affected several respiratory parameters including tidal volume/BW and minute volume/BW in mdx mice. In the more severe dko model, P-188 NF (1 mg/Kg significantly slowed the decline in multiple respiratory parameters compared with saline-treated dko mice. Prednisone's effects were similar to those seen with P-188 NF. Diaphragms from P-188 NF or prednisone treated mdx and dko mice showed signs of muscle fiber protection including less centralized nuclei, less variation in fiber size, greater fiber density, and exhibited a decreased amount of collagen deposition. P-188 NF at 3 mg/Kg s.c. also improved parameters of systolic and diastolic function in mdx mouse hearts. These results suggest that P-188 NF may be useful in treating respiratory and cardiac dysfunction, the leading causes of death in Duchenne muscular dystrophy patients.

  8. Formulation, radiopharmaceutical kinetics and dosimetry of the {sup 188}Re(V)-DMSA complex; Formulacion, radiofarmacocinetica y dosimetria del complejo {sup 188}Re(V)-DMSA

    Energy Technology Data Exchange (ETDEWEB)

    Garcia S, L; Ferro F, G [Departamento de Materiales Radiactivos. Instituto Nacional de Investigaciones Nucleares, C.P. 52045 Salazar, Estado de Mexico (Mexico); Murphy, C.A. de; Pedraza L, M [Departamento de Medicina Nuclear, Instituto Nacional de la Nutricion, Salvador Zubiran, Mexico D.F. (Mexico); Azorin N, J [Departamento de Fisica, Universidad Autonoma Metropolitana Iztapalapa, Mexico D.F. (Mexico)

    1999-07-01

    It was developed through experimental design (ANOVA), a formulation to prepare the {sup 188} Re(V)-Dmsa complex. Likewise, there were realized studies of radiopharmaceutical kinetics and internal dosimetry in animals, its normal and with induced tumors, considering an open bi compartmental model using the MIRD methodology. The {sup 188} Re(V)-Dmsa complex was obtained with a radiochemical purity greater than 95% incubating 30 min at 90 Centigrade under the following formulation: [SnCl{sub 2}] = 1.4 mg/ml, [ascorbic acid] = 0.5 mg/ml, p H = 2.0 - 3.0. The stability test of the formulation, shows that after 48 h of its preparation, does not produce radiolytic degradation neither chemical decomposition. The radiopharmaceutical kinetics data show an average residence time 7.2h, velocity constant {alpha} = 0.6508h{sup -1} and {beta} = 0.1046 h{sup -1} with an apparent distribution volume 6.9 l. The main elimination via was renal and it was observed osseous caption with an accumulated activity 522.049 {+-} 62 MBq h (residence time 14.1094 {+-} 1.69h). In according with the dosimetric calculations, by each 37 MBq injected, the equivalent dose at the tumor was 9.67{+-} 0.33 Sv/g, for an effective dose 0.292 {+-} 0.0017 mSv/MBq. The images obtained in the gamma camera of the mice with induced tumors, show that do not have significant accumulation in the metabolic organs. The caption in bone and in tumors induced of the {sup 188} Re(V)-Dmsa complex, show its potential for be used as a palliative agent for pain in patients with osseous metastasis and in the treatment of tumors of soft tissue. (Author)

  9. Effect of carrier on labeling and biodistribution of Re-188-hydroxyethylidene disphosphonate (HEDP)

    International Nuclear Information System (INIS)

    Jang, Y. S.; Jeong, J. M.; Kim, B. K.; Lee, D. S.; Jeong, J. K.; Lee, M. C.; Cho, J. H.

    1998-01-01

    Re-188- hydroxyethylidene disphosphonate (HEDP) is a new cost-effective agent for systemic radioisotope therapy of metastatic bone pain. We investigated the influence of carrier for labeling and biodistribution of Re-188-HEDP using HEDP kit(HEDP 15 mg, gentisic acid 4 mg and SnCl 2 2H 2 O 4.5 mg) with or without carrier (KReO 4 0.1 mg). The kits labeled with Re-188 solution available from an in-house generator by boiling for 15 min. The generator provides high 70-80 % equil yields and has an indefnite self-life. We compared the stability of carrier-added(CA) and carrier-free(CF) preparations of Re-188-HEDP. Biodistribution and imaging studies of each preparation were performed in ICR mice(1.85-3.7 MBq/0.1 ml) and SD rats(74.1-85.2 MBq/0.5 ml). The CA preparation showed high labeling efficiency(95% at pH 5) and high stability in serum(88%, 3 hr). However, the CF preparation showed low labeling efficiency(59% at pH 5) and low stability(43%, 3 hr). The CA preparation showed high uptake in bone and low uptake in stomach and kidneys. However, the CF preparation showed lower uptake in bone and higher uptake in both stomach and kidney, which is supposed to be due to released perrhenate. The CA preparation also showed better images with higher skeletal accumulation, lower uptake in other organs and lower soft tissue uptake than the CF preparation of carrier perrhenate is required for high labeling efficiency, stability, bone uptake and good image quality of Re-188-HEDP

  10. Effect of carrier on labeling and biodistribution of Re-188-Hydroxyethylidene diphosphonate

    International Nuclear Information System (INIS)

    Chang, Young Soo; Jeong, Jae Min; Kim, Bo Kwang; Cho, Jung Hyuk; Lee, Dong Soo; Chung, June Key; Lee, Myung Chul; Lee, Seung Jin; Jin, Ren Jie; Lee, Sang Eun

    2000-01-01

    Re-188-Hydroxyethylidene diphosphonate (HEDP) is a new cost-effective agent for systemic radioisotope therapy of metastatic bone pain. We investigated the influence of carrier for labeling and biodistribution of Re-188-HEDP using HEDP kit with or without carrier (KReO 4 ). The kits (HEDP 15 mg, gentisic acid 4 mg and SnC1 2 .2H 2 O 4.5 mg) with or without carrier (KReO 4 0.1 mg) were labeled with Re-188 solution, made available from an in-house generator by boiling for 15 min. We compared the labeling efficiency and stability of carrier-added and carrier-free preparations of Re-188-HEDP. Biodistribution and imaging studies of each preparation were performed in ICR mice (1.85-3.7 MBq/0.1 ml) and SD rats (74.1-85.2 MBq/0.5 ml). The carrier-added preparation showed high labeling efficiency (95% at pH 5) and high stability in serum (88%, 3hr). However, the carrier-free preparation showed low labeling efficiency (59% at pH 5) and low stability (43%, 3 hr). The carrier-added preparation showed high uptake in bone and low uptake in stomach and kidneys. However, the carrier-free preparation showed lower uptake in bone and higher uptake in both stomach and kidneys, which is supposed to be due to released perrhenate. The carrier-added preparation also showed better images with higher skeletal accumulation, lower uptake in other organs and lower soft tissue uptake than the carrier-free preparation. The results of these studies clearly demonstrate that addition of carrier perrhenate is required for high labeling efficiency, stability, bone uptake and good image quality of Re-188-HEDP.=20

  11. Physico-chemical characterisation and biological evaluation of 188-Rhenium colloids for radiosynovectomy

    International Nuclear Information System (INIS)

    Ures, Ma Cristina; Savio, Eduardo; Malanga, Antonio; Fernández, Marcelo; Paolino, Andrea; Gaudiano, Javier

    2002-01-01

    Radiosynovectomy is a type of radiotherapy used to relieve pain and inflammation from rheumatoid arthritis. In this study, 188-Rhenium ( 188 Re) colloids were characterized by physical and biological methodologies. This was used to assess which parameters of the kit formulation would be the basis in the development of a more effective radiopharmaceutical for synovectomy. Intraarticular injection in knees of rabbits assessed cavity leakage of activity. The physical characteristics of tin (Sn) and sulphur (S) colloids were determined to assess the formulation with suitable properties. Particles were grouped in three ranges for analyzing their distribution according to their number, volume and surface. The ideal particle size range was considered to be from 2 to 10 microns. Membrane filtration and laser diffraction characterization methodologies were used. While membrane filtration could give misleading data, laser diffraction proportions more reliable results. The Sn colloid showed a better distribution of particle volume and surface than S colloid, in the 2 to 10 microns range. The 188 Re-Sn colloid was obtained with a radiochemical purity higher than 95% after 30 minutes of autoclaving. While Sn colloid kit stability was verified for 60 days, the 188 Re-Sn preparation was stable in the first 24 hrs. No significant intrabatch variability (n = 3) was detected. Biodistribution and scintigraphic studies in rabbits after intraarticular injection showed relevant activity only in knee, being 90% at 48 hours. The 188 Re-Sn colloid is easy to prepare, is stable for 24 hours and shows minimal cavity leakage after intraarticular injection into rabbit knees, suggesting this radiotherapeutical agent has suitable physical properties for evaluation for joint treatment in humans

  12. Affinity of hydroxyapatite by radionuclides parent/child in {sup 188}Re/{sup 188}W generator for radiotherapy; Afinidad de la hidroxiapatita por los radionuclidos padre/hijo en el generador {sup 188}Re/{sup 188}W para radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Carrera D, A. A. [Universidad Autonoma de Zacatecas, Unidad Academica de Ciencias Quimicas, Campus Universitario Siglo XXI, Ejido La Escondida, Carretera a Guadalajara Km. 6 (Mexico); Badillo A, V. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela 98068, Zacatecas (Mexico); Badillo A, V. E.; Monroy G, F. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)], e-mail: ana_carrera7@hotmail.com

    2009-10-15

    To assess the feasibility of using apatites as matrices of {sup 188}W/{sup 188}Re generator is essential to obtain the distribution coefficients as much of parent radionuclide as child radionuclide in apatite, that is to say to know their affinity for the solid. It was selected the mineral species more representative as adsorbent, the hydroxyapatite Ca{sub 10} (PO{sub 4}){sub 6}(OH){sub 2} it is known for its great capacity of ions retention and by presenting a large affinity for anionic species in their surface. In this paper we use a synthetic hydroxyapatite marketed by Bio-Rad. This paper presents the preliminary results regarding the affinity of hydroxyapatite for the anionic species tungstates (WO{sub 4}{sup 2-}) and perrhenates (ReO{sub 4}{sup -} in EDTA, as background electrolyte expressed as distribution coefficients between two immiscible phases obtained with the help of radioactive tracers {sup 187}W and {sup 188}Re respectively. The retention measures of these ions, traces show that Bio-Gel hydroxyapatite presents moderate values of distribution coefficients for anionic species of W(Vi) in EDTA 0.01 mol/L that are in the range p H 5 to 6.5; the parent radionuclide of generator {sup 188}Re/{sup 188}W is fixed but not enough to consider it a good absorbent. By contrast, the fixation of perrhenate ions is virtually wiped as may be easily removed from a hydroxyapatite column packed with a saline solution. The influence of this saline solution in the removal of perrhenate ions is null practically. (Author)

  13. Arg188 in rice sucrose transporter OsSUT1 is crucial for substrate transport

    Directory of Open Access Journals (Sweden)

    Sun Ye

    2012-11-01

    Full Text Available Abstract Background Plant sucrose uptake transporters (SUTs are H+/sucrose symporters related to the major facilitator superfamily (MFS. SUTs are essential for plant growth but little is known about their transport mechanism. Recent work identified several conserved, charged amino acids within transmembrane spans (TMS in SUTs that are essential for transport activity. Here we further evaluated the role of one of these positions, R188 in the fourth TMS of OsSUT1, a type II SUT. Results The OsSUT1(R188K mutant, studied by expression in plants, yeast, and Xenopus oocytes, did not transport sucrose but showed a H+ leak that was blocked by sucrose. The H+ leak was also blocked by β-phenyl glucoside which is not translocated by OsSUT1. Replacing the corresponding Arg in type I and type III SUTs, AtSUC1(R163K and LjSUT4(R169K, respectively, also resulted in loss of sucrose transport activity. Fluorination at the glucosyl 3 and 4 positions of α-phenyl glucoside greatly decreased transport by wild type OsSUT1 but did not affect the ability to block H+ leak in the R188K mutant. Conclusion OsSUT1 R188 appears to be essential for sucrose translocation but not for substrate interaction that blocks H+ leak. Therefore, we propose that an additional binding site functions in the initial recognition of substrates. The corresponding Arg in type I and III SUTs are equally important. We propose that R188 interacts with glucosyl 3-OH and 4-OH during translocation.

  14. Mechanism investigation for poloxamer 188 raw material variation in cell culture.

    Science.gov (United States)

    Peng, Haofan; Ali, Amr; Lanan, Maureen; Hughes, Erik; Wiltberger, Kelly; Guan, Bing; Prajapati, Shashi; Hu, Weiwei

    2016-05-01

    Variability in poloxamer 188 (P188) raw material, which is routinely used in cell culture media to protect cells from hydrodynamic forces, plays an important role in the process performance. Even though tremendous efforts have been spent to understand the mechanism of poloxamer's protection, the root cause for lot-to-lot variation was not clear. A recent study reported that the low performance was not due to toxicity but inefficiency to protect cells (Peng et al., Biotechnol Prog. 2014;30:1411-1418). In this study, it was demonstrated for the first time that the addition of other surfactants even at a very low level can interfere with P188 resulting in a loss of efficiency. It was also found that the performance of P188 lots correlated well with its foam stability. Foam generated from low performing lots in baffled shaker flask lasts longer, which suggests that the components in the foam layers are different. The spiking of foam generated from a low performing lot into the media containing a high performance lot resulted in cell damage and low growth. Analytical studies using size exclusion chromatography (SEC) identified differences in high molecular weight (HMW) species present in the P188 lots. These differences are much clearer when comparing the HMW region of the SEC chromatogram of foam vs. bulk liquid samples. This study shows that low performing lots have enriched HMW species in foam samples due to high hydrophobicity, which can be potentially used as a screening assay. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:767-775, 2016. © 2016 American Institute of Chemical Engineers.

  15. WIYN Open Cluster Study. XXXII. Stellar Radial Velocities in the Old Open Cluster NGC 188

    Science.gov (United States)

    Geller, Aaron M.; Mathieu, Robert D.; Harris, Hugh C.; McClure, Robert D.

    2008-06-01

    We present the results of our ongoing radial-velocity (RV) survey of the old (7 Gyr) open cluster NGC 188. Our WIYN 3.5 m data set spans a time baseline of 11 years, a magnitude range of 12 =3 measurements, finding 473 to be likely cluster members. We detect 124 velocity-variable cluster members, all of which are likely to be dynamically hard-binary stars. Using our single member stars, we find an average cluster radial velocity of -42.36 ± 0.04 km s-1. We use our precise RV and proper-motion membership data to greatly reduce field-star contamination in our cleaned color-magnitude diagram, from which we identify six stars of note that lie far from a standard single-star isochrone. We present a detailed study of the spatial distribution of cluster-member populations, and find the binaries to be centrally concentrated, providing evidence for the presence of mass segregation in NGC 188. We observe the BSs to populate a bimodal spatial distribution that is not centrally concentrated, suggesting that we may be observing two populations of BSs in NGC 188, including a centrally concentrated distribution as well as a halo population. Finally, we find NGC 188 to have a global RV dispersion of 0.64 ± 0.04 km s-1, which may be inflated by up to 0.23 km s-1 from unresolved binaries. When corrected for unresolved binaries, the NGC 188 RV dispersion has a nearly isothermal radial distribution. We use this mean-corrected velocity dispersion to derive a virial mass of 2300 ± 460 M sun .

  16. A novel tantalum-containing bioglass. Part I. Structure and solubility

    Energy Technology Data Exchange (ETDEWEB)

    Alhalawani, Adel MF. [Department of Mechanical & Industrial Engineering, Ryerson University, Toronto, Ontario (Canada); Towler, Mark R., E-mail: mtowler@ryerson.ca [Department of Mechanical & Industrial Engineering, Ryerson University, Toronto, Ontario (Canada); Li Ka Shing Knowledge Institute, St. Michael' s Hospital, Toronto, Ontario (Canada)

    2017-03-01

    Bioglasses are employed for surgical augmentation in a range of hard tissue applications. Tantalum is a bioactive and biocompatible transition metal that has been used as an orthopedic medical device. It has a range of biological and physical properties that make its incorporation into ionic form into bioactive glass systems promising for various clinical applications. The work herein reports the characterization and properties of novel tantalum-containing glasses. A series of glasses based on the system 48SiO{sub 2}-(36-X)ZnO-6CaO-8SrO-2P{sub 2}O{sub 5}-XTa{sub 2}O{sub 5} with X varying from 0 mol% (TA0) to 0.5 mol% (TA2) were synthesized. The addition of small amounts of Ta{sub 2}O{sub 5} did not cause crystallization of the glasses but increasing Ta{sub 2}O{sub 5} content at the expense of ZnO was found to result in an increased number of bridging oxygens (BOs). This, along with the data recorded by differential thermal analysis (DTA) and magic angle spinning-nuclear magnetic resonance (MAS-NMR), confirms that Ta acts as a glass former in this series. Solubility experiments showed that minor changes in the glass structure caused by Ta incorporation (0.5 mol%) exhibited greater cumulative % weight loss, pH values and cumulative Zn{sup 2+} and Sr{sup 2+} ion concentration over a period of 30 days of maturation, when compared to Ta{sub 2}O{sub 5}-free glasses. The results presented in this article confirm that replacing ZnO with Ta{sub 2}O{sub 5} in silicate glasses results in the formation of stronger bonds within the glass network without any adverse effects on the solubility of the glasses prepared from them. - Highlights: • Ta{sub 2}O{sub 5} can be incorporated into silicate based ionomer glasses up to 0.5 mol%. • Incorporation resulted in amorphous glasses. • Insertion of TaO units into the silicate network confirms the former role of Ta{sub 2}O{sub 5}. • The incorporation increased the glass solubility.

  17. Compartmental and dosimetric studies of anti-CD20 labelled with 188Re

    International Nuclear Information System (INIS)

    Kuramoto, Graciela Barrio

    2016-01-01

    The radioimmunotherapy (RIT) uses MAbs conjugated to radionuclides α or β - emitters, both for therapy. Your treatment is based on the irradiation and tumor destruction, preserving the normal organs as the excess radiation. Radionuclides β - emitters as 131 I, 90 Y, 188 Re 177 Lu and are useful for the development of therapeutic radiopharmaceuticals and, when coupled with MAb and Anti-CD20 it is important mainly for the treatment of non-Hodgkin's lymphomas (NHL). 188 Re (E β = 2.12 MeV; E γ = 155 keV; t1/2 = 16.9 h) is an attractive radionuclide for RIT. However, 188 Re can be obtained from a radionuclide generator of 188 W/ 188 Re, commercially available, making it convenient for use in research and for clinical routine. The CR of IPEN has a project aimed at the production of radiopharmaceutical 188 Re-Anti-CD20, where the radionuclide can be obtained from a generator system 188 W/ 188 Re. With this proposed a study to assess the efficiency of this labeling technique for treatment in accordance compartmental and dosimetry. The objective of this study was to compare the marking of anti-CD20 MAb with 188 Re with the marking of the antibody with 90 Y, 131 I, 177 Lu and 99m Tc (for their similar chemical characteristics) and 211 At, 213 Bi, 223 Ra and 225 Ac); through the study of labeling techniques reported in literature, the proposal of a compartmental model to evaluate its pharmacokinetic and dosimetric studies, high interest for therapy. The result of the study shows a favorable kinetics for 188 Re, by their physical and chemical characteristics compared to the other evaluated radionuclides. The compartment proposed study describes the metabolism of 188 Reanti- CD20 through a compartment mammillary model, which by their pharmacokinetic analysis, performed compared to products emitters β -131 I-labeled anti CD20, 177 Luanti- CD20, the γ emitter 99m Tc-Anti-CD20 and α emitter 211 At-Anti-CD20 presented a elimination constant of approximately 0.05 hours

  18. Biological behavior of 188Re-biotin chelate for multistep therapy with the avidin-biotin system

    International Nuclear Information System (INIS)

    Choi, T. H.; Ahn, S. H.; Choi, C. W.; Woo, K. S.; Jung, W. S.; Lim, S. J.; Lim, S. M.

    1999-01-01

    The purpose of this study was to test the three-step targeting of tumors in mice using biotinylated antibody, streptavidin and radiolabeled biotin for radioimmunotherapy (RAIT). Three-step pretargetting can potentially decreases harmful radiation to normal tissues in radioimmunotherapy. 188 Re from 188 W- 188 Re generator, is recently introduced in therapeutic nuclear medicine and made it possible to use whenever needed. We studied biotin-chelates MGB for use in the avidin/biotin pretargetting system. Chelates that hold radiometals with high stability under physiological conditions are essential to avoid excessive radiation damage to non-target cells. We synthesized MAG 2 GABA-Biocytin (MGB), labeled with 188 Re and evaluated biological behavior of 188 Re-MGB. biotinyl MAG 2 GABA bind the therapeutic radiometal 188 Re with excellent in vitro stability and have the required physiological properties for pretargetted therapy. In normal mice, 188 Re-MGB was excreted via hepatobiliary pathway, %ID/g of GI tract was 52.1 at 120min. In Raji cells tumor bearing nude mice, liver and colon were higher than those of normal mouse. Tumor uptake at 120min was 0.05%ID/g. 188 Re-MGB may have a role in pretargetted radioimmunotherapy

  19. 188Re radiopharmaceuticals for radiosynovectomy: evaluation and comparison of tin colloid, hydroxyapatite and tin-ferric hydroxide macroaggregates

    International Nuclear Information System (INIS)

    Savio, Eduardo; Ures, María Cristina; Zeledón, Patricia; Trindade, Victoria; Paolino, Andrea; Mockford, Virginia; Malanga, Antonio; Fernández, Marcelo; Gaudiano, Javier

    2004-01-01

    Radiosynovectomy is a therapy used to relieve pain and inflammation from rheumatoid arthritis and related diseases. In this study three 188 Re particulate compounds were characterized according to their physico-chemical properties and their biological behavior in rabbits. The results were compared in order to establish which was the radiopharmaceutical that better fits the requirements of this kind of radiotherapy. Three radiopharmaceutical formulations, tin colloid, hydroxyapatite particles (HA) and ferric hydroxide macroaggregates coated with tin colloid (FHMA), were physically characterized (number, volume and surface of the particles). For this purpose laser diffraction methodology was used. To evaluate cavity leakage of activity the following studies in New Zealand rabbits were performed: scintigraphic images for 48 hr after intraarticular injection of each radiopharmaceutical, biodistribution at 48 hr and urine samples collection during the first 24 hr post-radiopharmaceutical administration. Labeling procedures for 188 Re-HA and 188 Re-Sn-FHMA were labour intensive while 188 Re-Sn was easily prepared. Furthermore, 188 Re-Sn colloid offered the greatest surface area in the 2–10 microm range and was obtained with a radiochemical purity over 95%, while percentage of bound activity for 188 Re-HA and 188 Re-Sn-FHMA were 55% and 92% respectively. Stability was verified for the three radiopharmaceuticals for 24 hr. Scintigraphic studies and biodistribution in rabbits after intraarticular administration of the radiopharmaceuticals showed relevant activity only in the knee, this being over 90% of the residual activity in the whole body at 48 hr in every case. Renal elimination of 188 Re-Sn colloid and 188 Re-Sn-FHMA was detected by activity measurements in urine samples, during the first 12 hr post-radiopharmaceutical injection. The percentage of activity retained in the knee was 69.1% for 188 Re-Sn colloid, 55.1% for 188 Re-Sn-FHMA and 33.6% for 188 Re-HA. The 188

  20. In-vitro studies with 188Re-HEDP, a clinically used bone pain palliating agent, on bone cancer cells

    International Nuclear Information System (INIS)

    Sharma, Rohit; Kumar, Chandan; Mallia, Madhava B.; Banerjee, Sharmila; Kameswaran, Mythili

    2017-01-01

    Rhenium-188 is an attractive radioisotope for a wide variety of radiotherapy applications. 188 Re-HEDP (HEDPhydroxyethylidene- 1,1-diphosphonic acid) is one such, clinically useful, radiopharmaceutical for palliation of bone pain due to osseous metastasis. Herein, our aim was to study the uptake and retention of 188 Re-HEDP in mineralized bone and to assess its cellular toxicity, along with its underlying mechanism in human osteocarcinoma (MG-63 and Soas-2) cell lines. 188 Re-HEDP uptake was found to be significantly higher in mineralized bone. The 188 Re-HEDP complex also induces G2-M cell cycle arrest and thus contributing to apoptosis and cellular toxicity in bone cancer cells. (author)

  1. A study of factors affecting the labelling of tartrate with 188Re and the transchelation of the 188Re from the tartrate to a protein

    International Nuclear Information System (INIS)

    Sailerova, Eva; Billinghurst, M.W.

    2003-01-01

    The formation of 188 Re-tartrate for use in transchelation reactions and the transchelation of the 188 Re onto albumin was studied. Two labelled tartrate products were separated using a non-traditional mobile phase on ITLC strips. Tartrate labelling yield increases with pH but so does the instability when the product is exposed to air. Lower pH's are preferred when oxygen-free labelling conditions can be achieved. Higher tin levels protect against air oxidation. Stability of the Re-tartrate complex is supported by addition of ascorbic acid and ferrous sulphate, however both these agents decreased the rate of the formation of the Re-tartrate complex. The labelling efficiency of a perrhenate solution decreased with the time for which it is stored prior to the labelling reaction, depending on the radioactive concentration. Re-albumin transchelation efficiency increases with the tartrate concentration, while increased stability of the Re-tartrate complex lowers the transchelation yields of Re-albumin

  2. The effects of tantalum addition on the microtexture and mechanical behaviour of tungsten for ITER applications

    Energy Technology Data Exchange (ETDEWEB)

    Tejado, E., E-mail: elena.tejado@mater.upm.es [Departamento de Ciencia de Materiales-CIME, ETSI Caminos, Canales y Puertos, Universidad Politécnica de Madrid, Madrid (Spain); Centro Nacional de Investigaciones Metalúrgicas (CSIC), Madrid (Spain); Carvalho, P.A. [Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); ICEMS, Departamento de Bioengenharia, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Munoz, A. [Departamento de Física, Universidad Carlos III, Leganés (Spain); Dias, M. [Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Correia, J.B. [Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); LNEG, Laboratório Nacional de Energia e Geologia, Estrada do Paço do Lumiar, 1649-038 Lisboa (Portugal); and others

    2015-12-15

    Tungsten (W) and its alloys are very promising materials for producing plasma-facing components (PFCs) in the fusion power reactors of the near future, even as a structural part in them. However, whereas the properties of pure tungsten are suitable for a PFC, its structural applications are still limited due to its low toughness, ductile to brittle transition temperature and recrystallization behaviour. Therefore, many efforts have been made to improve its performance by alloying tungsten with other elements. Hence, in this investigation, the thermo-mechanical performance of two new tungsten-tantalum materials has been evaluated. Materials with W–5wt.%Ta and W–15wt.%Ta were processed by mechanical alloying (MA) and later consolidation by hot isostatic pressing (HIP), with distinct settings for each composition. Thus, it was possible to determine the relationship between the microstructure and the addition of Ta with the macroscopic mechanical properties. These were measured by means of hardness, flexural strength and fracture toughness, in the temperature range of 300–1473 K. The microstructure and the fracture surfaces features of the tested materials were analysed by Field Emission Scanning Electron Microscopy (FESEM).

  3. Argon Shrouded Plasma Spraying of Tantalum over Titanium for Corrosion Protection in Fluorinated Nitric Acid Media

    Science.gov (United States)

    Vetrivendan, E.; Jayaraj, J.; Ningshen, S.; Mallika, C.; Kamachi Mudali, U.

    2018-02-01

    Argon shrouded plasma spraying (ASPS) was used to deposit a Ta coating on commercially pure Ti (CP-Ti) under inert argon, for dissolver vessel application in the aqueous spent fuels reprocessing plant with high plutonium content. Oxidation during plasma spraying was minimized by shrouding argon system. Porosity and oxide content were controlled by optimizing the spraying parameters, to obtain a uniform and dense Ta coating. The Ta particle temperature and velocity were optimized by judiciously controlling the spray parameters, using a spray diagnostic charge-coupled device camera. The corrosion resistance of the Ta coatings developed by ASPS was investigated by electrochemical studies in 11.5 M HNO3 and 11.5 M HNO3 + 0.05 M NaF. Similarly, the durability of the ASPS Ta coating/substrate was evaluated as per ASTM A262 Practice-C test in boiling nitric acid and fluorinated nitric acid for 240 h. The ASPS Ta coating exhibited higher corrosion resistance than the CP-Ti substrate, as evident from electrochemical studies, and low corrosion rate with excellent coating stability in boiling nitric, and fluorinated nitric acid. The results of the present study revealed that tantalum coating by ASPS is a promising strategy for improving the corrosion resistance in the highly corrosive reprocessing environment.

  4. The effects of tantalum addition on the microtexture and mechanical behaviour of tungsten for ITER applications

    International Nuclear Information System (INIS)

    Tejado, E.; Carvalho, P.A.; Munoz, A.; Dias, M.; Correia, J.B.

    2015-01-01

    Tungsten (W) and its alloys are very promising materials for producing plasma-facing components (PFCs) in the fusion power reactors of the near future, even as a structural part in them. However, whereas the properties of pure tungsten are suitable for a PFC, its structural applications are still limited due to its low toughness, ductile to brittle transition temperature and recrystallization behaviour. Therefore, many efforts have been made to improve its performance by alloying tungsten with other elements. Hence, in this investigation, the thermo-mechanical performance of two new tungsten-tantalum materials has been evaluated. Materials with W–5wt.%Ta and W–15wt.%Ta were processed by mechanical alloying (MA) and later consolidation by hot isostatic pressing (HIP), with distinct settings for each composition. Thus, it was possible to determine the relationship between the microstructure and the addition of Ta with the macroscopic mechanical properties. These were measured by means of hardness, flexural strength and fracture toughness, in the temperature range of 300–1473 K. The microstructure and the fracture surfaces features of the tested materials were analysed by Field Emission Scanning Electron Microscopy (FESEM).

  5. Reduced-graphene-oxide supported tantalum-based electrocatalysts: Controlled nitrogen doping and oxygen reduction reaction

    Science.gov (United States)

    Yang, Xiaoyun; Mo, Qijie; Guo, Yulin; Chen, Nana; Gao, Qingsheng

    2018-03-01

    Controlled N-doping is feasible to engineer the surface stoichiometry and the electronic configuration of metal-oxide electrocatalysts toward efficient oxygen reduction reactions (ORR). Taking reduced graphene oxide supported tantalum-oxides (TaOx/RGO) for example, this work illustrated the controlled N-doping in both metal-oxides and carbon supports, and the contribution to the improved ORR activity. The active N-doped TaOx/RGO electrocatalysts were fabricated via SiO2-assisted pyrolysis, in which the amount and kind of N-doping were tailored toward efficient electrocatalysis. The optimal nanocomposites showed a quite positive half-wave potential (0.80 V vs. RHE), the excellent long-term stability, and the outstanding tolerance to methanol crossing. The improvement in ORR was reasonably attributed to the synergy between N-doped TaOx and N-doped RGO. Elucidating the importance of controlled N-doping for electrocatalysis, this work will open up new opportunities to explore noble-metal-free materials for renewable energy applications.

  6. A critical examination of pure tantalum processed by high-pressure torsion

    Energy Technology Data Exchange (ETDEWEB)

    Maury, Nicolas [École Nationale Supérieure des Ingénieurs en Arts Chimiques et Technologiques (ENSIACET), National Polytechnic Institute of Toulouse (INPT), 31077 Toulouse Cedex 04 (France); Zhang, Nian Xian; Huang, Yi [Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom); Zhilyaev, Alexander P. [Institute for Metals Superplasticity Problems, Russian Academy of Sciences, 39 Khalturina, 450001 Ufa (Russian Federation); Research Laboratory for Mechanics of New Nanomaterials, St. Petersburg State Polytechnical University, St. Petersburg 195251 (Russian Federation); Langdon, Terence G., E-mail: langdon@usc.edu [Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom); Departments of Aerospace & Mechanical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1453 (United States)

    2015-06-25

    Tantalum, a common refractory metal with body-centred cubic (BCC) crystalline structure, was processed by high-pressure torsion (HPT) at room temperature through different numbers of rotations. Significant grain refinement and high strength were achieved with a reduction in grain size from ∼60 μm to ∼160 nm and an increase in strength from ∼200 to >1300 MPa. Hardness measurements revealed a high level of homogeneity after 10 turns of HPT but the hardness after 10 turns was slightly lower than after 5 turns indicating the occurrence of some recovery. Tensile testing at a strain rate of 1.0×10{sup −3} s{sup −1} gave high strengths of ∼1200 MPa but little or no ductility after processing through 1, 5 and 10 turns. The introduction of a short-term (15 min) anneal immediately after HPT processing led to significant ductility in all samples and a reasonable level of strength at ∼800 MPa.

  7. Equation of State and Viscosity of Tantalum and Iron from First Principles

    Science.gov (United States)

    Miljacic, Ljubomir; Demers, Steven; van de Walle, Axel

    2011-03-01

    To understand and model at continuum level the high-energy-density dynamic response in transition metals like Tantalum and Iron, as it arises in hypervelocity impact experiments, an accurate prediction of the underlying thermodynamic and kinetic properties for a range of temperatures and pressures is of critical importance. The relevant time scale of atomic motion in a dense gas, liquid, and solid is accessible with ab-initio Molecular Dynamics (MD) simulations. We calculate EoS for Ta and Fe via Thermodynamical Integration in 2D (V,T) phase space throughout different single and two-component phases. To reduce the ab-initio demand in selected regions of the space, we fit available gas-liquid data to the Peng-Robinson model and treat the solid phase within the Boxed-quasi-harmonic approximation. In the fluid part of the 2D phase space, we calculate shear viscosity via Green-Kubo relations, as time integration of the stress autocorrelation function.

  8. Characteristics and production of tantalum powders for solid-electrolyte capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jae Sik [Korea Basic Science Institute, Sunchon Branch, Sunchon 540-742 (Korea); Department of Chemical and Materials Engineering, University of Alberta, Edmonton T6G 2G6 (Canada); Kim, Byung Il [Department of Material Science and Metallurgical Engineering, Sunchon National, University, Sunchon 540-742 (Korea)

    2007-02-10

    The effects of using K{sub 2}TaF{sub 7} as the raw material and sodium as the reducing agent on the characteristics of tantalum powder are investigated. Batch-type metallothermic reduction (BTMR) is used to charge the reactor with the raw material and the reducing agent, and external continuous supply metallothermic reduction (ESMR) is used to supply the raw material and the reducing agent at a constant rate at the temperature of the reduction reaction. In the case of ESMR, the yield increases by several tens of percent because of the uniform reaction between the raw material and the reducing agent. It is possible to obtain a powder of over 99.5% purity. The powder particles obtained with BTMR are relatively large (4-6 {mu}m) and have a coarse lamellar shape, while those prepared via ESMR are of uniform 1-2 {mu}m size with a coral-like shape. Measurements of the electric properties show that the leakage current and the dielectric dissipation are low with higher reliability in ESMR than in BTMR, and the capacitance is 26,000 and 8400 CV for ESMR and in BTMR, respectively. (author)

  9. Laser ablation synthesis of tantalum carbide particles with specific phase assemblage and special interface

    Energy Technology Data Exchange (ETDEWEB)

    Lin, S.S.; Shen, P. [National Sun Yat-sen University, Department of Materials and Optoelectronic Science, Kaohsiung (China); Chen, S.Y. [I-Shou University, Department of Mechanical and Automation Engineering, Kaohsiung (China)

    2015-07-15

    Pulsed laser ablation of bulk TaC in vacuum under a high power density was used to fabricate fine-sized tantalum carbide particles, i.e., γ-TaC{sub 1-x} with varied extent of carbon deficiency and α-Ta{sub 2}C surrounded by an amorphous phase of Ta-doped carbon clusters or lamellae according to X-ray and electron diffraction. The predominant γ-TaC{sub 1-x} has a high x value (∝0.4) and almost spherical shape when rapidly solidified as submicron-sized particulates, whereas x ∝ 0.2 and facetted with occasional {111} coalescence twin when condensed as nanoparticles. The minor α-Ta{sub 2}C occurred either as nanocondensates with hexagonal crystal form or as a stable epitaxial intergrowth with the γ-TaC{sub 1-x} particulate having close-packed planes in parallel with the precipitation process. The γ-TaC{sub 1-x} and α-Ta{sub 2}C nanocondensates were also coalesced approaching a secondary relationship, i.e., [011]{sub TaC1-x}//[01 anti 1]{sub Ta2C} and (100){sub TaC1-x}//(0001){sub Ta2C} having a fair coincidence site lattice at the interface. The refractory materials have a bimodal minimum band gap (ca. 3.8 and 2.3 eV) for potential optocatalytic and tribology applications at high temperatures. (orig.)

  10. Effect of Tantalum content on the low cycle fatigue properties of CLAM steel at 823 K

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Xiangwei [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); University of Science and Technology of China, Hefei, Anhui, 230027 (China); Liu, Shaojun, E-mail: shaojun.liu@fds.org.cn [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); Zhao, Yanyun; Wang, Kun [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China)

    2017-01-15

    Highlights: • The fatigue life initially decreased and then increased as the Ta content was increased from 0.027 wt% to 0.18 wt%. • The softening rate had declined with Ta content increased and the reduced softening rate was attributed to the increased number of Ta-rich MX particles. • The grain size and M{sub 23}C{sub 6} were closely associated with the Ta content. • The crack distribution was quite sensitive to the Ta content. - Abstract: The effect of tantalum (Ta) content on the low cycle fatigue (LCF) properties of CLAM steel at 823 K was investigated in this paper. Low cycle fatigue tests were carried out on four ingots of CLAM steel with Ta contents of 0.027 wt%, 0.078 wt%, 0.15 wt% and 0.18 wt%, respectively. The results showed that the fatigue life and softening behavior of CLAM steel were influenced by Ta content. The fatigue life initially decreased and then increased as the Ta content was increased from 0.027 wt% to 0.18 wt%. The softening rate had declined with Ta content increased and the reduced softening rate was attributed to the increased number of Ta-rich MX particles.

  11. Atomic-absorption determination of tantalum and niobium in ore concentrates

    International Nuclear Information System (INIS)

    Elinson, S.V.; Korovin, Yu.I.; Kuchumov, V.A.

    1975-01-01

    A flame atom-absorption method was developed for determining tantalum and niobium at their level greater than 5% in Ta-Nb ore concentrates. Flame was produced by a nitrous oxide-acetylene mixture. The optimal composition of a buffer (3 mg/ml) of iron was determined by the method of factorial planning of the experiment and steep ascention by gradient. The optimizing parameter in factorial planning was obtained from the difference of optical densities of Ta and Nb, by taking the average value for two solutions which had dissimilar total composition and which imitated the real composition of the ore concentrates, i.e., the value of (ΔD/Dsub(av))sub(Ta) or (ΔD/Dsub(av))sub(Nb). The optimization of analytical conditions corresponded to the condition (ΔD/Dsub(av))→ 0, which indicated that the chosen optimizing parameter also facilitated the attainment of maximum D values. The variation coefficient in the determination of Ta and Nb was respectively 0.8 and 1.4%. There was a good agreement between the results obtained in Ta analysis by the atom-absorption and the extraction-gravimetric methods, and in Nb analysis by the atom-absorption, differential spectrophotometric and x-ray fluorescence methods

  12. Dislocation-drag contribution to high-rate plastic deformation in shock-loaded tantalum

    International Nuclear Information System (INIS)

    Tonks, D.L.; Hixson, R.S.; Johnson, J.N.; Gray, G.T. III

    1994-01-01

    Time-resolved plastic waves in plate-impact experiments give information on the relationship between applied shear stress and plastic strain rate at low plastic strain. This information is essentially different from that obtained at intermediate strain rates using Hopkins on bar techniques, because in the former case the material deformation state is driven briefly into the regime dominated by dislocation drag rather than thermal activation. Two VISAR records of the particle velocity at the tantalum/sapphire (window) interface are obtained for symmetric impact producing peak in situ longitudinal stresses of approximately 75 kbar and 111 kbar. The risetimes of the plastic waves are about 100 ns and 60 ns, respectively, with peak strain rates of about 2x10 5 /s and 1x10 6 /s, respectively, as determined by weak-shock analysis [Wallace, Phys. Rev. B 22, 1487 (1980), and Tonks, Los Alamos DataShoP Report LA-12068-MS (1991)]. These data show a much stronger dependence of plastic strain rate on applied shear stress than previously predicted by linear viscous drag models in combination with thermal activation through a large Peierls barrier. The data also show complex evolution of the mobile dislocation density during early stages of high-rate plastic flow. This measurement and analysis aid significantly in establishing the fundamental picture of dynamic deformation of BCC metals and the evolution of the internal material state at early times following shock compression. copyright 1994 American Institute of Physics

  13. Effect of concentrated light on morphology and vibrational properties of boron and tantalum mixtures

    Directory of Open Access Journals (Sweden)

    Lina Sartinska

    2018-03-01

    Full Text Available Heating a mixture of boron (impurities: carbon ∼ B50C2, boric acid – H3BO3 and tantalum (Ta powders in nitrogen flow in a xenon high-flux optical furnace was performed. As-received powder composed of h-BN, H3BO3, TaB2, B9H11 and a number of other phases including β-rhombohedral boron, apparently, heavily doped with Ta. FT–IR examination of any sample of the material reveals the complicated vibration spectrum containing, in particular, an absorption band near 2260 cm−1. The shapes of these bands are different for samples because powders were synthesized at different temperatures. Known, that in β-rhombohedral boron lattice, there are nano-sized voids of different types, which allow an accommodation of single atoms or small groups of atoms. Theoretical calculations performed by the method of quasi-classical type yields the same value, 2260 cm−1, for the vibrations frequency of Ta atoms in D-type crystallographic voids in β-rhombohedral boron lattice. Since, Ta atoms are known to prefer accommodation just in D-voids the experimentally detected bands can be identified with localized vibrations of Ta atoms. Keywords: Condensed matter physics, Materials science, Nanotechnology

  14. Dynamic behaviour of tantalum hydride supported on silica or MCM-41 in the metathesis of alkanes

    KAUST Repository

    Soignier, Sophie

    2014-01-01

    The metathesis of ethane and propane catalysed by tantalum hydride supported on silica or MCM-41 was studied under static and dynamic conditions. During the reaction, the rate decreased over time, indicating deactivation of the catalyst. The evolution of the catalytic system and surface species over time was monitored by various physico-chemical methods: FTIR, 13C NMR spectroscopy, elemental analysis and chemical reactivity. A carbonaceous deposit composed of unsaturated hydrocarbyl species was observed by 13C NMR. This deposit was responsible for poisoning of the catalyst. The deactivation of the catalyst proved more severe at higher temperatures and under static rather than dynamic conditions. A partial regeneration of the catalyst could be achieved during a series of repeated runs. Mechanistically, the deconvolution of the products\\' distribution over time indicated the occurrence of hydrogenolysis in the early stages of the reaction, while pure metathesis dominated later on. The hydrogen was supplied by the dehydrogenation of hydrocarbyl surface species involved in the deactivation process. © 2014 The Royal Society of Chemistry.

  15. Evaluation of diffusion barrier and electrical properties of tantalum oxynitride thin films for silver metallization

    International Nuclear Information System (INIS)

    Misra, E.; Wang, Y.; Theodore, N.D.; Alford, T.L.

    2004-01-01

    The thermal stability and the diffusion barrier properties of DC reactively sputtered tantalum oxynitride (Ta-O-N) thin films, between silver (Ag) and silicon (Si) p + n diodes were investigated. Both materials characterization (X-ray diffraction analysis, Rutherford backscattering spectrometry (RBS), Auger depth profiling) and electrical measurements (reverse-biased junction leakage current-density) were used to evaluate diffusion barrier properties of the thin films. The leakage current density of p + n diodes with the barrier (Ta-O-N) was approximately four orders of magnitude lower than those without barriers after a 30 min, 400 deg. C back contact anneal. The Ta-O-N barriers were stable up to 500 deg. C, 30 min anneals. However, this was not the case for the 600 deg. C anneal. RBS spectra and cross-sectional transmission electron microscopy of as-deposited and vacuum annealed samples of Ag/barrier (Ta-O-N)/Si indicate the absence of any interfacial interaction between the barrier and substrate (silicon). The failure of the Ta-O-N barriers has been attributed to thermally induced stresses, which cause the thin film to crack at elevated temperatures

  16. Tantalum Nitride Electron-Selective Contact for Crystalline Silicon Solar Cells

    KAUST Repository

    Yang, Xinbo

    2018-04-19

    Minimizing carrier recombination at contact regions by using carrier‐selective contact materials, instead of heavily doping the silicon, has attracted considerable attention for high‐efficiency, low‐cost crystalline silicon (c‐Si) solar cells. A novel electron‐selective, passivating contact for c‐Si solar cells is presented. Tantalum nitride (TaN x ) thin films deposited by atomic layer deposition are demonstrated to provide excellent electron‐transporting and hole‐blocking properties to the silicon surface, due to their small conduction band offset and large valence band offset. Thin TaNx interlayers provide moderate passivation of the silicon surfaces while simultaneously allowing a low contact resistivity to n‐type silicon. A power conversion efficiency (PCE) of over 20% is demonstrated with c‐Si solar cells featuring a simple full‐area electron‐selective TaNx contact, which significantly improves the fill factor and the open circuit voltage (Voc) and hence provides the higher PCE. The work opens up the possibility of using metal nitrides, instead of metal oxides, as carrier‐selective contacts or electron transport layers for photovoltaic devices.

  17. Thick sputtered tantalum coatings for high-temperature energy conversion applications

    Energy Technology Data Exchange (ETDEWEB)

    Stelmakh, Veronika, E-mail: stelmakh@mit.edu; Peykov, Daniel; Chan, Walker R.; Senkevich, Jay J.; Joannopoulos, John D.; Soljačić, Marin; Celanovic, Ivan [Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Castillo, Robert; Coulter, Kent; Wei, Ronghua [Materials Engineering Department, Southwest Research Institute, San Antonio, Texas 78238 (United States)

    2015-11-15

    Thick sputtered tantalum (Ta) coatings on polished Inconel were investigated as a potential replacement for bulk refractory metal substrates used for high-temperature emitters and absorbers in thermophotovoltaic energy conversion applications. In these applications, high-temperature stability and high reflectance of the surface in the infrared wavelength range are critical in order to sustain operational temperatures and reduce losses due to waste heat. The reflectance of the coatings (8 and 30 μm) was characterized with a conformal protective hafnia layer as-deposited and after one hour anneals at 700, 900, and 1100 °C. To further understand the high-temperature performance of the coatings, the microstructural evolution was investigated as a function of annealing temperature. X-ray diffraction was used to analyze the texture and residual stress in the coatings at four reflections (220, 310, 222, and 321), as-deposited and after anneal. No significant changes in roughness, reflectance, or stress were observed. No delamination or cracking occurred, even after annealing the coatings at 1100 °C. Overall, the results of this study suggest that the thick Ta coatings are a promising alternative to bulk substrates and pave the way for a relatively low-cost and easily integrated platform for nanostructured devices in high-temperature energy conversion applications.

  18. Reactivity Control of Rhodium Cluster Ions by Alloying with Tantalum Atoms.

    Science.gov (United States)

    Mafuné, Fumitaka; Tawaraya, Yuki; Kudoh, Satoshi

    2016-02-18

    Gas phase, bielement rhodium and tantalum clusters, RhnTam(+) (n + m = 6), were prepared by the double laser ablation of Rh and Ta rods in He carrier gas. The clusters were introduced into a reaction gas cell filled with nitric oxide (NO) diluted with He and were subjected to collisions with NO and He at room temperature. The product species were observed by mass spectrometry, demonstrating that the NO molecules were sequentially adsorbed on the RhnTam(+) clusters to form RhnTam(+)NxOx (x = 1, 2, 3, ...) species. In addition, oxide clusters, RhnTam(+)O2, were also observed, suggesting that the NO molecules were dissociatively adsorbed on the cluster, the N atoms migrated on the surface to form N2, and the N2 molecules were released from RhnTam(+)N2O2. The reactivity, leading to oxide formation, was composition dependent: oxide clusters were dominantly formed for the bielement clusters containing both Rh and Ta atoms, whereas such clusters were hardly formed for the single-element Rhn(+) and Tam(+) clusters. DFT calculations indicated that the Ta atoms induce dissociation of NO on the clusters by lowering the dissociation energy, whereas the Rh atoms enable release of N2 by lowering the binding energy of the N atoms on the clusters.

  19. Oxidative Desulfurization of Dibenzothiophene Using Dawson Type Heteropoly Compounds/Tantalum as Catalyst

    Directory of Open Access Journals (Sweden)

    Risfidian Mohadi

    2016-03-01

    Full Text Available Catalyst (NH46[b-P2W18O62]/Ta has been synthesized by simple wet impregnation at 30-40 °C under atmospheric conditions using Dawson type polyoxometalate (NH46[b-P2W18O62] and tantalum. The catalyst was characterized by FTIR spectrophotometer, XRD, SEM, and N2 adsorption desorption methods. FTIR spectrum of (NH46[b-P2W18O62]/Ta showed that Dawson type polyoxometalate (NH46[b-P2W18O62] and Ta was successfully impregnated which was indicated by vibration spectrum at wavenumber of 900-1100 cm-1 for polyoxometalate and 550 cm-1 for Ta. The surface area of the (NH46[b-P2W18O62]/Ta after impregnation was higher than (NH46[b-P2W18O62]•nH2O and its morphology was found to be uniform. The catalytic activity of (NH46[b-P2W18O62]/Ta toward desulfurization of dibenzothiophene was three times higher than the original catalyst of (NH46[b-P2W18O62]•nH2O without impregnation. The catalytic regeneration test of catalyst (NH46[b-P2W18O62]/Ta showed that the catalytic activity for first regeneration of catalyst has similar catalytic activity with the fresh catalyst without loss of catalytic activity indicated by almost similar percent conversion.

  20. A search for the ground state structure and the phase stability of tantalum pentoxide

    International Nuclear Information System (INIS)

    Pérez-Walton, S; Valencia-Balvín, C; Padilha, A C M; Dalpian, G M; Osorio-Guillén, J M

    2016-01-01

    Tantalum pentoxide (Ta 2 O 5 ) is a wide-gap semiconductor that presents good catalytic and dielectric properties, conferring to this compound promising prospective use in a variety of technological applications. However, there is a lack of understanding regarding the relations among its crystalline phases, as some of them are not even completely characterized and there is currently no agreement about which models better explain the crystallographic data. Additionally, its phase diagram is unknown. In this work we performed first-principles density functional theory calculations to study the structural properties of the different phases and models of Ta 2 O 5 , the equation of state and the zone-centered vibrational frequencies. From our results, we conclude that the phases that are built up from only distorted octahedra instead of combinations with pentagonal and/or hexagonal bipyramids are energetically more favorable and dynamically stable. More importantly, this study establishes that, given the pressure range considered, the B-phase is the most favorable structure and there is no a crystallographic phase transition to another phase at high-pressure. Additionally, for the equilibrium volume of the B-phase and the λ-model, the description of the electronic structure and optical properties were performed using semi-local and hybrid functionals. (paper)

  1. Electrochemical Impedance and Polarization Corrosion Studies of Tantalum Surface Modified by DC Plasma Electrolytic Oxidation

    Directory of Open Access Journals (Sweden)

    Maciej Sowa

    2018-04-01

    Full Text Available Tantalum has recently become an actively researched biomaterial for the bone reconstruction applications because of its excellent corrosion resistance and successful clinical records. However, a bare Ta surface is not capable of directly bonding to the bone upon implantation and requires some method of bioactivation. In this study, this was realized by direct current (DC plasma electrolytic oxidation (PEO. Susceptibility to corrosion is a major factor determining the service-life of an implant. Therefore, herein, the corrosion resistance of the PEO coatings on Ta was investigated in Ringer’s solution. The coatings were formed by galvanostatic anodization up to 200, 300 and 400 V, after which the treatment was conducted potentiostatically until the total process time amounted to 5 min. Three solutions containing Ca(H2PO22, Ca(HCOO2 and Mg(CH3COO2 were used in the treatment. For the corrosion characterization, electrochemical impedance spectroscopy and potentiodynamic polarization techniques were chosen. The coatings showed the best corrosion resistance at voltages low enough so that the intensive sparking was absent, which resulted in the formation of thin films. The impedance data were fitted to the equivalent electrical circuits with two time constants, namely R(Q[R(QR] and R(Q[R(Q[RW

  2. Carbonized tantalum catalysts for catalytic chemical vapor deposition of silicon films

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Shimin [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Dalian National Laboratory for Clean Energy, Dalian 116023 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Gao Huiping; Ren Tong; Ying Pinliang [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Dalian National Laboratory for Clean Energy, Dalian 116023 (China); Li Can, E-mail: canli@dicp.ac.cn [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Dalian National Laboratory for Clean Energy, Dalian 116023 (China)

    2012-06-01

    Catalytic chemical vapor deposition (Cat-CVD) has been demonstrated as a promising way to prepare device-quality silicon films. However, catalyst ageing due to Si contamination is an urgency to be solved for the practical application of the technique. In this study, the effect of carbonization of tantalum catalyst on its structure and performance was investigated. The carbonized Ta catalyst has a TaC surface layer which is preserved over the temperature range between 1450 and 1750 Degree-Sign C and no Si contamination occurs on the catalyst after long-term use. Si film prepared using the carbonized Ta catalyst has a similar crystal structure to that prepared by uncarbonized Ta catalyst. Formation of the TaC surface layer can alleviate the ageing problem of the catalyst, which shows great potential as a stable catalyst for Cat-CVD of Si films. - Highlights: Black-Right-Pointing-Pointer Si films prepared by catalytic chemical vapor deposition. Black-Right-Pointing-Pointer Carbonized Ta with a TaC surface layer used as catalyst. Black-Right-Pointing-Pointer TaC surface structure preserved after long-term use in a wide temperature range. Black-Right-Pointing-Pointer Help to solve the ageing problem of metal catalysts. Black-Right-Pointing-Pointer Si film obtained has a similar crystal structure to that prepared by Ta catalyst.

  3. Two-dimensional tantalum disulfide: controlling structure and properties via synthesis

    Science.gov (United States)

    Zhao, Rui; Grisafe, Benjamin; Krishna Ghosh, Ram; Holoviak, Stephen; Wang, Baoming; Wang, Ke; Briggs, Natalie; Haque, Aman; Datta, Suman; Robinson, Joshua

    2018-04-01

    Tantalum disulfide (TaS2) is a transition metal dichalcogenide (TMD) that exhibits phase transition induced electronic property modulation at low temperature. However, the appropriate phase must be grown to enable the semiconductor/metal transition that is of interest for next generation electronic applications. In this work, we demonstrate direct and controllable synthesis of ultra-thin 1T-TaS2 and 2H-TaS2 on a variety of substrates (sapphire, SiO2/Si, and graphene) via powder vapor deposition. The synthesis process leads to single crystal domains ranging from 20 to 200 nm thick and 1-10 µm on a side. The TaS2 phase (1T or 2H) is controlled by synthesis temperature, which subsequently is shown to control the electronic properties. Furthermore, this work constitutes the first demonstration of a metal-insulator phase transition in directly synthesized 1T-TaS2 films and domains by electronic means.

  4. Effects of processing parameters on the properties of tantalum nitride thin films deposited by reactive sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Nazon, J.; Sarradin, J.; Flaud, V.; Tedenac, J.C. [Institut Charles Gerhardt, UMR 5253 CNRS-UM2-ENSCM-UM1, cc 1504, Place E. Bataillon, 34095 Montpellier Cedex 5 (France); Frety, N. [Institut Charles Gerhardt, UMR 5253 CNRS-UM2-ENSCM-UM1, cc 1504, Place E. Bataillon, 34095 Montpellier Cedex 5 (France)], E-mail: Nicole.Frety@univ-montp2.fr

    2008-09-22

    The effects of processing parameters on the properties of tantalum nitride thin films deposited by radio frequency reactive sputtering have been investigated. The influence of the N{sub 2} partial and (Ar + N{sub 2}) total gas pressures as well as the sputtering power on the microstructure and electrical properties is reported. Rising the N{sub 2} partial pressure, from 2 to 10.7%, induces a change in the composition of the {delta}-TaN phase, from TaN to TaN{sub 1.13}. This composition change is associated with a drastic increase of the electrical resistivity over a 7.3% N{sub 2} partial pressure. The total gas pressure is revealed to strongly affect the film microstructure since a variation in both composition and grain size is observed when the gas pressure rises from 6.8 to 24.6 Pa. When the sputtering power varied between 50 and 110 W, an increase of the grain size related to a decrease of the electrical resistivity is observed.

  5. Dynamic behaviour of tantalum hydride supported on silica or MCM-41 in the metathesis of alkanes

    KAUST Repository

    Soignier, Sophie; Saggio, Guillaume; Taoufik, Mostafa; Basset, Jean-Marie; Thivolle-Cazat, Jean

    2014-01-01

    The metathesis of ethane and propane catalysed by tantalum hydride supported on silica or MCM-41 was studied under static and dynamic conditions. During the reaction, the rate decreased over time, indicating deactivation of the catalyst. The evolution of the catalytic system and surface species over time was monitored by various physico-chemical methods: FTIR, 13C NMR spectroscopy, elemental analysis and chemical reactivity. A carbonaceous deposit composed of unsaturated hydrocarbyl species was observed by 13C NMR. This deposit was responsible for poisoning of the catalyst. The deactivation of the catalyst proved more severe at higher temperatures and under static rather than dynamic conditions. A partial regeneration of the catalyst could be achieved during a series of repeated runs. Mechanistically, the deconvolution of the products' distribution over time indicated the occurrence of hydrogenolysis in the early stages of the reaction, while pure metathesis dominated later on. The hydrogen was supplied by the dehydrogenation of hydrocarbyl surface species involved in the deactivation process. © 2014 The Royal Society of Chemistry.

  6. Reconstruction mechanisms of tantalum oxide coatings with low concentrations of silver for high temperature tribological applications

    Energy Technology Data Exchange (ETDEWEB)

    Stone, D. S.; Bischof, M.; Aouadi, S. M., E-mail: samir.aouadi@unt.edu [Department of Material Science and Engineering, University of North Texas, Denton, Texas 76207 (United States); Gao, H.; Martini, A. [School of Engineering, University of California Merced, Merced, California 95343 (United States); Chantharangsi, C.; Paksunchai, C. [Department of Physics, King Mongkut' s University of Technology Thonburi, Bangkok 10140 (Thailand)

    2014-11-10

    Silver tantalate (AgTaO{sub 3}) coatings have been found to exhibit outstanding tribological properties at elevated temperatures. To understand the mechanisms involved in the tribological behavior of the Ag-Ta-O system, tantalum oxide coatings with a small content of silver were produced to investigate the metastable nature of this self-lubricating material. The coatings were produced by unbalanced magnetron sputtering, ball-on-disk wear tested at 750 °C, and subsequently characterized by X-ray diffraction, Scanning Auger Nanoprobe, cross-sectional Scanning Electron Microscopy, and Transmission Electron Microscopy. Complementary molecular dynamic simulations were carried out to investigate changes in the chemical and structural properties at the interface due to sliding for films with varying silver content. Both the experimental characterization and the theoretical modeling showed that silver content affects friction and wear, through the role of silver in film reconstruction during sliding. The results suggest that the relative amount of silver may be used to tune film performance for a given application.

  7. Reconstruction mechanisms of tantalum oxide coatings with low concentrations of silver for high temperature tribological applications

    International Nuclear Information System (INIS)

    Stone, D. S.; Bischof, M.; Aouadi, S. M.; Gao, H.; Martini, A.; Chantharangsi, C.; Paksunchai, C.

    2014-01-01

    Silver tantalate (AgTaO 3 ) coatings have been found to exhibit outstanding tribological properties at elevated temperatures. To understand the mechanisms involved in the tribological behavior of the Ag-Ta-O system, tantalum oxide coatings with a small content of silver were produced to investigate the metastable nature of this self-lubricating material. The coatings were produced by unbalanced magnetron sputtering, ball-on-disk wear tested at 750 °C, and subsequently characterized by X-ray diffraction, Scanning Auger Nanoprobe, cross-sectional Scanning Electron Microscopy, and Transmission Electron Microscopy. Complementary molecular dynamic simulations were carried out to investigate changes in the chemical and structural properties at the interface due to sliding for films with varying silver content. Both the experimental characterization and the theoretical modeling showed that silver content affects friction and wear, through the role of silver in film reconstruction during sliding. The results suggest that the relative amount of silver may be used to tune film performance for a given application

  8. Intracoronary Poloxamer 188 Prevents Reperfusion Injury in a Porcine Model of ST-Segment Elevation Myocardial Infarction

    Directory of Open Access Journals (Sweden)

    Jason A. Bartos, MD, PhD

    2016-06-01

    Full Text Available Poloxamer 188 (P188 is a nonionic triblock copolymer believed to prevent cellular injury after ischemia and reperfusion. This study compared intracoronary (IC infusion of P188 immediately after reperfusion with delayed infusion through a peripheral intravenous catheter in a porcine model of ST-segment elevation myocardial infarction (STEMI. STEMI was induced in 55 pigs using 45 min of endovascular coronary artery occlusion. Pigs were then randomized to 4 groups: control, immediate IC P188, delayed peripheral P188, and polyethylene glycol infusion. Heart tissue was collected after 4 h of reperfusion. Assessment of mitochondrial function or infarct size was performed. Mitochondrial yield improved significantly with IC P188 treatment compared with control animals (0.25% vs. 0.13%, suggesting improved mitochondrial morphology and survival. Mitochondrial respiration and calcium retention were also significantly improved with immediate IC P188 compared with control animals (complex I respiratory control index: 7.4 vs. 3.7; calcium retention: 1,152 nmol vs. 386 nmol. This benefit was only observed with activation of complex I of the mitochondrial respiratory chain, suggesting a specific effect from ischemia and reperfusion on this complex. Infarct size and serum troponin I were significantly reduced by immediate IC P188 infusion (infarct size: 13.9% vs. 41.1%; troponin I: 19.2 μg/l vs. 77.4 μg/l. Delayed P188 and polyethylene glycol infusion did not provide a significant benefit. These results demonstrate that intracoronary infusion of P188 immediately upon reperfusion significantly reduces cellular and mitochondrial injury after ischemia and reperfusion in this clinically relevant porcine model of STEMI. The timing and route of delivery were critical to achieve the benefit.

  9. Improved conditions for labeling EDTMP with 188Re for bone pain palliation

    International Nuclear Information System (INIS)

    Faintuch, B.L.; Osso, J.A. Jr.; Muramoto, E.; Faintuch, S.

    2002-01-01

    Introduction: Ethilenediamine tetramethylene phosphonate (EDTMP) is a tetraphosphonate ligand which, when labeled with 188 Re, can be used for relief of metastatic bone pain. The preferential localization of phosphonate complexes in bone is attributed to their affinity for calcium, and tetraphosphonates may be equal or superior to diphosphonates in this regard. In the present study, it was aimed to determine optimal conditions for preparation of a kit of EDTMP to be labeled with 188 Re. Methods: EDTMP was dissolved in NaOH 1N, and alkalinity was reversed with HCl till pH 2, when SnCl 2 . 2H 2 0 and also ascorbic acid were introduced in the mixture, followed by Na 188 ReO 4 . The preparation was incubated in water bath for 30 minutes and after cooling radiochemical purity was assessed. Optimization of the process consisted in varying the values of EDTMP mass (20, 30, 40 mg) SnCl 2 .2H 2 0 concentration (0.5, 1.0, 2.0 and 3.0 mg/mL), and reaction time (15 and 30 minutes). Radiochemical purity and stability were ascertained in vitro and also in Swiss mice. Bone/muscle uptake ratio was calculated from %ID/g of these organs. Results: The best 188 Re-EDTMP complex was obtained with 40 mg of the ligand and 2 mg/mL of stannous chloride heated during 15 minutes, and the product was radiochemically stable during 24 hours. Kidney and bone uptake were very significant (respectively 4.5 ± 0.5% and 3.1 ± 0.3 %ID/g). Bone/muscle ratio observed four hours post-injection was also very adequate (28.5). Conclusions: A stable and biologically useful complex of 188 Re-EDTMP can be prepared with high concentration of EDTMP and considerable uptake by bone. It compares favorably with 153 Sm-EDTMP, as 188 Re has more advantageous radioisotopic properties than 153 Sm, and it can be recommended for further studies in conditions of painful bone metastases

  10. Determination of niobium, tantalum, and uranium in tantalite-columbite ores by X-ray fluorescence spectrometry; Application de la spectrometrie de fluorescence de rayos X a la determination de niobium, tantale et uranium dans niobiotantalites

    Energy Technology Data Exchange (ETDEWEB)

    Latorre, O; Bermudez Polonio, J

    1964-07-01

    A simple and quick procedure is carried out to determine niobium, tantalum and uranium employing the internal standard technique; zinc as internal standard for tantalum and molybdenum for niobium and uranium were selected. Some inter element effects were studied and the ratios. (Author)

  11. In vivo examination of {sup 188}Re(I)-tricarbonyl-labeled trastuzumab to target HER2-overexpressing breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Chen, K.-T. [Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Lee, T.-W. [Institute of Nuclear Energy Research, Longtan 32546, Taiwan (China); Lo, Jem-Mau [Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 30013, Taiwan (China)], E-mail: jmlo@mx.nthu.edu.tw

    2009-05-15

    Introduction: Trastuzumab (Herceptin), a humanized IgG1 monoclonal antibody directed against the extracellular domain of the HER2 protein, acts as an immunotherapeutic agent for HER2-overexpressing human breast cancers. Radiolabeled trastuzumab with {beta}- or {alpha} emitters can be used as radioimmunotherapeutic agent for the similar purpose but with additional radiation effect. Methods: In this study, trastuzumab was labeled with {sup 188}Re for radioimmunotherapy of HER2/neu-positive breast cancer. {sup 188}Re(I)-tricarbonyl ion, [{sup 188}Re(OH{sub 2}){sub 3}(CO){sub 3}]{sup +}, was employed as a precursor for directly labeling the monoclonal antibody with {sup 188}Re. The immunoreactivity of {sup 188}Re(I)-trastuzumab was estimated by competition receptor-binding assay using HER2/neu-overexpressive BT-474 human breast cancer cells. The localization properties of {sup 188}Re(I)-trastuzumab within both tumor and normal tissues of athymic mice bearing BT-474 human breast cancer xenografts (HER2/neu-overexpressive) and similar mice bearing MCF-7 human breast cancer xenografts (HER2/neu-low expressive) were investigated. Results: When incubated with human serum albumin and histidine at 25{sup o}C, {sup 188}Re(I)-trastuzumab was found to be stable within 24 h. The IC{sub 50} of {sup 188}Re(I)-trastuzumab was found to be 22.63{+-}4.57 nM. {sup 188}Re(I)-trastuzumab was shown to accumulate specifically in BT-474 tumor tissue in in vivo biodistribution studies. By microSPECT/CT, the image of {sup 188}Re localized BT-474 tumor was clearly visualized within 24 h. In contrast, {sup 188}Re(I)-trastuzumab uptake in HER2-low-expressing MCF-7 tumor was minimal, and the {sup 188}Re image at the localization of the tumor was dim. Conclusion: These results reveal that {sup 188}Re(I)-trastuzumab could be an appropriate radioimmunotherapeutic agent for the treatment of HER2/neu-overexpressing cancers.

  12. Synthesis and in Vitro evaluation of ''1''8''8Re-biotinyl-hydrazino-etda

    International Nuclear Information System (INIS)

    Pervez, S; Mushtaq, A.; Jehangir, M.

    2002-01-01

    Pretargeting strategies have overcome many drawbacks associated with the use of directly labelled MoAbs in the diagnosis / treatment of various solid tumors. In particular the avidin-biotin system has received much attention due to extremely high affinity between avidin and biotin. An EDTA derivative of biotin has been synthesized (yield-35%). In order or label biotin derivative (biotinyl-hydrazino-EDTA) , stannous ion was used to reduce ''1''8''8ReO 4 (VII) to lower oxidation state and weak chelating agent glucoheptonate as stabilizer and trans chelating agent. Thin layer chromatography and high performance liquid chromatography techniques were employed to monitor the radiolabeling efficiency. The radiolabeling yield of ''1''8''8Re-EDTA B1 was >95%. The radiolabeled product was found to bind to avidin (70-80%), thereby demonstrating retention of its biological integrity

  13. Electrochemical characterisation of X10CrNi 18-8 steel in artificial plasma

    Directory of Open Access Journals (Sweden)

    J. Przondziono

    2015-01-01

    Full Text Available Quality of applied guide wires conditions the course of treatment and its success to a great extent. In order to simulate conditions that can be found in blood vascular system samples were exposed to artificial blood plasma (T = 37 } 1 oC for the time of 8 h. In order to obtain information regarding physical and chemical properties of modified surface of wire made of X10CrNi 18-8 steel, electrochemical impedance spectroscopy (EIS test and tests of chemical composition of the surface layer X-ray photoelectron spectroscopy (XPS were made. On the ground of performed EIS and XPS tests, favourable impact of steam sterilisation process on corrosion resistance of X10CrNi 18-8 steel was observed only for the case when chemical passivation was applied prior to sterilisation.

  14. 188Rhenium-HEDP in the Treatment of Pain in Bone Metastases

    International Nuclear Information System (INIS)

    Gaudiano, J.; Savio, E.; Robles, A.; Muniz, S.; Leon, A.; Verdera, S.; Martinez, G.; Hermida, J.C.; Knapp, F.F. Jr.

    1999-01-01

    Systemic use of radiopharmaceuticals is a recognized alternative method for the treatment of pain in patients with multiple bone metastasis. A new option, 188 Re-HEDP is proposed, using generator-obtained 188 Rhenium (β energy = 2.1 MeV, γ energy = 155 keV, half-life = 16.9 hours). After establishing parameters of biodistribution, dosimetry and image acquisition in mice, rats and rabbits, Phase I and II studies were conducted on 12 patients with multiple metastasis from carcinomas, with pain surpassing other analgesic options. More than 50% pain relief was found in 91% of the patients, with total relief during a variable period in 41% of them allowing opiate and other analgesic drugs to be decreased or withdrawn, and showing a lower bone marrow contribution to total absorbed dose than that reported for other similar radiopharmaceuticals. Further study of this option is recommended in order to determine higher dose protocols without toxic bone marrow reaction possibilities

  15. On the Magnetic Properties of the K=1 Rotational Band in {sup 188}Re

    Energy Technology Data Exchange (ETDEWEB)

    Malmskog, S G; Hoejeberg, M

    1967-05-15

    The transitions in the decay of the 18.6 min {sup 188}Re isomer have been studied with a Ge(Li) detector. Two new weak gamma ray transitions of 156 and 169 keV were found and interpreted as cross-over transitions. From a delayed coincidence experiment using a double lens electron-electron coincidence spectrometer the half-life of the first excited 63.6 keV level in Re was determined as T{sub 1/2} = 56 {+-} 7 psec. The half lives of the first excited 2{sup +} levels in {sup 186}Os and {sup 188}Os were also measured and found to be 0.81 {+-} 0.03 nsec and 0.68 {+-} 0.03 nsec respectively.

  16. Development of methods of labeling pentavalent DMSA with 99mTc and 188Re

    International Nuclear Information System (INIS)

    Brambilla, Tania de Paula

    2009-01-01

    Technetium-99 m is the most useful radionuclide in diagnostic imaging procedures in Nuclear Medicine, more than 80 percent of radiopharmaceuticals are 99m Tc-labeled compounds. 99m Tc-DMSA(V) has been used for imaging of soft tissue, head and neck tumors. It shows a particularly high specificity for medullary thyroid carcinoma and bone metastases in a variety of cancers. Biodistribution studies of 188 Re-DMSA(V) have shown that its general pharmacokinetic properties are similar to that of 99m Tc-DMSA(V), so this agent could be used for targeted radiotherapy of these tumors. The aim of this work is the development of methods of labeling DMSA(V) with 99m Tc and 188 Re. 99m Tc-DMSA(V) can be prepared by two methods. One of them is the indirect one, through the use of a commercial kit of DMSA (III), by adjusting the pH from 2.5 to ∼ 8.5 with NaHCO 3 . This method was evaluated and optimized presenting high labeling yields. The other method is the direct one, through the preparation of a lyophilised kit ready for labeling with 99m Tc, being the method of interest of this work, due to the easy of its clinical use. The most adequate formulation of the kit was: 1.71 mg of DMSA, 0.53 mg of SnCl 2 .2H 2 O and 0.83 mg of ascorbic acid (pH 9). Labeling yields higher than 95% were achieved labeling this kit with 1 to 2 m L of 99m Tc with activities up to 4736 MBq (128 mCi). The kit was stable up to 6 months and biodistribution studies confirmed the quality of the DMSA (V) labeled with 99m Tc using this kit. The reduction potential of Re is lower than the one for Tc, so the labeling conditions of 188 Re-DMSA(V) are different from the ones used for 99m Tc- DMSA(V). 188 Re-DMSA(V) is prepared in acid solution, that makes it possible to use the DMSA (III) commercial kit developed for labeling with 99m Tc, prepared in pH 2.5, for labeling with 188 Re. Labeling yields higher than 95% were achieved with this methodology, with a rection time of 30 minutes at 100 deg C using no more

  17. Rhenium-188 - advantages and clinical potential for use of a readily available, cost effective therapeutic radioisotope for applications in nuclear medicine, oncology and interventional cardiology

    International Nuclear Information System (INIS)

    Knapp, F.F. jr.

    2002-01-01

    Full text: Carrier-free rhenium-188 (Re-188) is readily available from the alumina-based tungsten-188/rhenium-188 generator system and has many attractive properties for a wide variety of therapeutic applications. The 16.9 h half-life, emission of the 2.2 MeV beta particle and versatile chemistry make Re-188 an important candidate for applications where high radiation penetration is required. In addition, emission of a gamma photon (155 KeV, 15 %) permits evaluation of biodistribution, pharmacokinetics and dosimetry estimates. The long physical half-life of the tungsten-188 (W-188) parent (t 1/2 69 days) and consistent generator performance - with high Re-188 yields and low W-188 parent breakthrough - result in an indefinite shelf-life of several months, dependent on the levels of Re-188 required. Post generator elution in-growth of 62 % of Re-188 after 24 hours in combination with high elution yields (75-85 %) result in 50 % daily yields of the maximal Re-188 available. In addition to research being conducted for the development of a wide variety of new therapeutic radiopharmaceuticals and devices, Re-188 is also being evaluated in physician-sponsored clinical trials in over 15 countries, with applications in nuclear medicine, oncology and interventional cardiology. One major current clinical application involves post-angiographic treatment of arterial segments following PTCA using Re-188 perrhenate or MAG3 liquid-filled balloons as an effective and cost-effective approach for inhibition of the hyperplastic response to vessel damage, which delivers uniform dose to the vessel wall. Re-188-HEDP is being used for palliation of metastatic bone pain palliation. This agent is readily prepared from a simple 'kit' and provides pain palliation as effective as other commercially available agents. The use of the Re-188-labeled Anti-NCA-95 antibody (BW 50/183; CD66 a,b,c,e) in conjunction which external beam irradiation and chemotherapy is an effective method for

  18. 16 CFR 18.8 - Deception as to origin or source of industry products.

    Science.gov (United States)

    2010-01-01

    ... misrepresentation as to source or origin (e.g., “Colorado Blue Spruce,” “Arizona Cypress,” “Black Hills Spruce... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Deception as to origin or source of industry... GUIDES FOR THE NURSERY INDUSTRY § 18.8 Deception as to origin or source of industry products. (a) It is...

  19. Labelled biomolecules with Sm-153, Re-188 and Y-90 for targeted radiotherapy

    International Nuclear Information System (INIS)

    Ahmad, M.; Pervez, S.

    2000-01-01

    Direct labeling of Lanreotide with Rhenium-188 was studied. Reduction of cysteine bridge was performed by reducing agents (ascorbic acid, 2ME). The perrhenate eluted from the generator was reduced with stannous chloride. Tartarate was used as transchelating agent. After pH adjustment, shaking and incubation for various time intervals were carried out. Thin Layer chromatography and reverse phase chromatography were used to monitor the radiolabelling yield. Stability of radiolabelled Lanreotide was also checked

  20. Labelled biomolecules with SM-153, Re-188 and Y-90 for targeted radiotherapy. Pakistan

    International Nuclear Information System (INIS)

    Ahmad, Mushtaq; Pervez, Shahid

    2000-01-01

    Direct labeling of Lanreotide with Rhenium-188 was studied. Reduction of cysteine bridge was performed by reducing agents (ascorbic acid, 2ME). The perrhenate eluted from the generator was reduced with stannous chloride. Tartarate was used as transchelating agent. After pH adjustment, shaking and incubation for various time intervals were carried out. Thin layer chromatography and reverse phase chromatography were used to monitor the radiolabelling yield. Stability of radiolabelled Lanreotide was also checked

  1. Low conversion loss 94 GHz and 188 GHz doublers in InP DHBT technology

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Johansen, Tom Keinicke; Squartecchia, Michele

    2017-01-01

    An Indium Phosphide (InP) Double Heterojunction Bipolar Transistor (DHBT) process has been utilized to design two doublers to cover the 94 GHz and 188 GHz bands. The 94 GHz doubler employs 4-finger DHBTs and provides conversion loss of 2 dB. A maximum output power of nearly 3 dBm is measured whil...... operate over a broad bandwidth. The total circuit area of each chip is 1.41 mm2....

  2. Application of on-line HPLC-ICP-MS for the determination of the nuclide abundances of lanthanides produced via spallation reactions in an irradiated tantalum target of a spallation neutron source

    International Nuclear Information System (INIS)

    Kerl, W.; Becker, J.S.; Dietze, H.J.

    1998-01-01

    An analytical procedure has been developed for the determination of spallation nuclides in an irradiated tantalum target using HPLC coupled on-line to ICP-MS after dissolution and separation of the tantalum matrix. Pieces of tantalum were taken from different locations of the irradiated tantalum target which had been used as the target material in a spallation neutron source. Tantalum was dissolved in a HNO 3 /HF mixture and the tantalum matrix was separated by liquid-liquid extraction so that only the spallation nuclides were left in the sample solutions. The major fraction of the spallation nuclides in the tantalum target are lanthanide metals in the μg g -1 concentration range determined in the present study. Additional reaction products are formed by the irradiation of trace impurities in the original tantalum target. The nuclide abundances of the lanthanide metals measured in the tantalum target differ significantly from the natural isotopic composition so that a lot of isobaric interferences of long-lived radionuclides and stable isotopes in the mass spectrum are to be expected. Therefore, all the lanthanide metals had to be separated chemically prior to their mass spectrometric determination. The separation of all rare earth elements was performed by ion chromatography on-line to ICP-MS. The nuclide abundances of each lanthanide were determined using a sensitive double-focusing sector field inductively coupled plasma mass spectrometer. The nuclide abundances of the lanthanides in the irradiated tantalum target calculated theoretically and the experimental results obtained by on-line HPLC-ICP-MS proved to be in good agreement. (orig.)

  3. The alpha-branching ratios of the 188,190,192Pb isotopes

    International Nuclear Information System (INIS)

    Wauters, J.; Dendooven, P.; Decrock, P.; Huyse, M.; Reusen, G.; Duppen, P. van

    1992-01-01

    The α-branching ratios (b α ) of 192,190,188 Pb are measured using mass-separated sources. Different experimental set-ups are used - one detector as well as two detector set-ups - thereby detecting the α particles from the parent and/or via α decay formed daughter nuclei, the β-delayed gamma radiation from the parent and/or via β decay formed daughter nuclei in the Tl KX Rays from electron capture decay. Values for b α of 6.2(6) 10 -5 and 4.0(4) 10 -3 were found for 191,190 Pb respectively. For 188 Pb, limits on the b α values were obtained: 0.03 α α values showed that the discrepancies in the b α values were not due to inadequate correction procedures, as was suggested, but to experimental uncertainties in the efficiency determination of the different detection set-ups and to an unreliable β-decay scheme for 188 Pb. The b α obtained in this work show that the lead α decay is not faster than the Hg α decay and that there is no need to assume a disappearance of the Z=82 shell closure halfway between N=82 and N=126. (orig.)

  4. A new technique for labeling of Lipiodol with 188Re in the treatment of hepatic tumor

    International Nuclear Information System (INIS)

    Shyh-Jen Wang; Wan-Yu Lin; Bor-Tsung Hsieh; Kai-Yuan Cheng; Lie-Hang Shen; Ming-Ja Su

    2004-01-01

    A new method for the synthesis of 188 Re-Lipiodol without using a chelating agent and to evaluate the stability and biodistribution of the new agent in rats with hepatic tumors was attempted. Eighteen male Sprague -Dawley rats with liver tumors were sacrificed at 1, 24, and 48 hours (six rats at each time) after injection of approximately 7.4 MBq (0.2 mCi) of 188 Re Lipiodol via the hepatic artery. Samples of tumor, liver and other organs were collected and tissue concentration (%ID/g) of the markers were calculated. A high level of radioactivity in the hepatic tumors was found at every time of the study. The ratios of tumor to normal liver tissue concentration (T/N ratio) were 7.62 at 1 hour, 8.03 at 24 hours, and 7.70 at 48 hours. Except for the liver, kidneys and lungs, concentrations in other organs were low. The new method for labeling Lipiodol with 188 Re is simple and has potential for the treatment of hepatic tumors. (author)

  5. Preventive study of gastric cancer peritoneal micrometastasis in nude mice with 188Re-labelled monoclonal antibody 3H11

    International Nuclear Information System (INIS)

    Yang Zhi; Zhang Meiying; Lin Baohe; Zhao Changying; Han Yan; Mou Aping; Ma Yunxia

    2001-01-01

    In advanced gastric cancer, especially when the serosa is invaded, the implantation of cancer cells in the peritoneum is common, and it affects patients' survival time severely. Based on successfully labelled monoclonal antibody 3H11 with 188 Re, we investigated the effect of RIT (radioimmunotherapy) with 188 Re-3H11 on preventing the establishment of gastric cancer cell peritoneal micrometastasis in nude mice. After 1x10 6 BGC-823, gastric cancer cells were injected into the peritoneal cavity of each mouse, 45 BABL/C nude mice were divided into 9 groups. Each group received the various doses of 188 Re-3H11 or 188 Re-IgG or saline I.P.16 hours postoperation. The injected volume of each mouse was 1.0 mL. The results showed that the survival time depended on injected doses from 0 to 37MBq. The survival time was 170 ± 25.3 days after 37MBq 188 Re-3H11 were treated . It was over 5 times that of the saline group and about 3 times that of the 74MBq 188 Re-IgG group (p 188 Re-3H11 I.P. is effective and safe in the prevention of intra-peritoneally injected gastric cancer cells from surviving, growing and disseminating in nude mice. (author)

  6. 188Re-SSS lipiodol: radiolabelling and biodistribution following injection into the hepatic artery of rats bearing hepatoma.

    Science.gov (United States)

    Garin, Etienne; Denizot, Benoit; Noiret, Nicolas; Lepareur, Nicolas; Roux, Jerome; Moreau, Myriam; Herry, Jean-Yves; Bourguet, Patrick; Benoit, Jean-Pierre; Lejeune, Jean-Jacques

    2004-10-01

    Although intra-arterial radiation therapy with 131I-lipiodol is a useful therapeutic approach to the treatment of hepatocellular carcinoma, various disadvantages limit its use. To describe the development of a method for the labelling of lipiodol with 188Re-SSS (188Re (S2CPh)(S3CPh)2 complex) and to investigate its biodistribution after injection into the hepatic artery of rats with hepatoma. 188Re-SSS lipiodol was obtained after dissolving a chelating agent, previously labelled with 188Re, in cold lipiodol. The radiochemical purity (RCP) of labelling was checked immediately. The 188Re-SSS lipiodol was injected into the hepatic artery of nine rats with a Novikoff hepatoma. They were sacrificed 1, 24 and 48 h after injection, and used for ex vivo counting. Labelling of 188Re-SSS lipiodol was achieved with a yield of 97.3+/-2.1%. The immediate RCP was 94.1+/-1.7%. Ex vivo counting confirmed a predominantly hepatic uptake, with a good tumoral retention of 188Re-SSS lipiodol, a weak pulmonary uptake and a very faint digestive uptake. The 'tumour/non-tumoral liver' ratio was high at 1, 24 and 48 h after injection (2.9+/-1.5, 4.1+/-/4.1 and 4.1+/-0.7, respectively). Using the method described here, 188Re-SSS lipiodol can be obtained with a very high yield and a satisfactory RCP. The biodistribution in rats with hepatoma indicates a good tumoral retention of 188Re-SSS lipiodol associated with a predominant hepatic uptake, a weak pulmonary uptake and a very faint digestive uptake. This product should be considered for intra-arterial radiation therapy in human hepatoma.

  7. The effect of low energy helium ion irradiation on tungsten-tantalum (W-Ta) alloys under fusion relevant conditions

    Science.gov (United States)

    Gonderman, S.; Tripathi, J. K.; Novakowski, T. J.; Sizyuk, T.; Hassanein, A.

    2017-08-01

    Currently, tungsten remains the best candidate for plasma-facing components (PFCs) for future fusion devices because of its high melting point, low erosion, and strong mechanical properties. However, continued investigation has shown tungsten to undergo severe morphology changes under fusion-like conditions. These results motivate the study of innovative PFC materials which are resistant to surface morphology evolution. The goal of this work is to examine tungsten-tantalum (W-Ta) alloys, a potential PFC material, and their response to low energy helium ion irradiation. Specifically, W-Ta samples are exposed to 100 eV helium irradiations with a flux of 1.15 × 1021 ions m-2 s-1, at 873 K, 1023 K, and 1173 K for 1 h duration. Scanning electron microscopy (SEM) reveals significant changes in surface deterioration due to helium ion irradiation as a function of both temperature and tantalum concentration in W-Ta samples. X-Ray Diffraction (XRD) studies show a slight lattice parameter expansion in W-Ta alloy samples compared to pure W samples. The observed lattice parameter expansion in W-Ta alloy samples (proportional to increasing Ta wt.% concentrations) reflect significant differences observed in the evolution of surface morphology, i.e., fuzz development processes for both increasing Ta wt.% concentration and target temperature. These results suggest a correlation between the observed morphology differences and the induced crystal structure change caused by the presence of tantalum. Shifts in the XRD peaks before and after 100 eV helium irradiation with a flux of 1.15 × 1021 ions m-2 s-1, 1023 K, for 1 h showed a significant difference in the magnitude of the shift. This has suggested a possible link between the atomic spacing of the material and the accumulated damage. Ongoing research is needed on W-Ta alloys and other innovative materials for their application as irradiation resistant materials in future fusion or irradiation environments.

  8. Structural and photoluminescent properties of a composite tantalum oxide and silicon nanocrystals embedded in a silicon oxide film

    Energy Technology Data Exchange (ETDEWEB)

    Díaz-Becerril, T., E-mail: tomas.diaz.be@gmail.com; Herrera, V.; Morales, C.; García-Salgado, G.; Rosendo, E.; Coyopol, A., E-mail: acoyopol@gmail.com; Galeazzi, R.; Romano, R.; Nieto-Caballero, F.G.; Sarmiento, J.

    2017-04-15

    Tantalum oxide crystals encrusted in a silicon oxide matrix were synthesized by using a hot filament chemical vapor deposition system (HFCVD). A solid source composed by a mixture in different percentages of Ta{sub 2}O{sub 5} and silicon (Si) powders were used as reactants. The films were grown at 800 °C and 1000 °C under hydrogen ambient. The deposited films were characterized by X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and photoluminescence (PL) at room temperature. From the XPS results it was confirmed the formation of a mixture of Tantalum oxide, silicon oxide and Si nanoparticles (Ta{sub 2}O{sub 5-}SiO{sub 2}-Si(nc)) as seen from the Si (2p) and Ta (4f) lines corresponding to Si{sup +} and Ta{sup +} states respectively. Ta{sub 2}O{sub 5} and Si nanocrystals (Si-NCs) embedded in the silicon oxide films were observed on HRTEM images which corroborate the XPS results. Finally the emission properties of the films exhibited a broad band from 400 to 850 nm caused by the independent PL properties of tantalum oxide and Si-NCs that compose the film. The intensity of the emissions was observed to be dependent on both temperature of deposition and the ratio Ta{sub 2}O{sub 5}/Si, used as initial reactants. Results from this work might supply useful data for the development of future light emitter devices.

  9. Tantalum coating on porous Ti6Al4V scaffold using chemical vapor deposition and preliminary biological evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiang, E-mail: xiangliwj@sjtu.edu.cn [School of Mechanical Engineering, Shanghai Jiao Tong University, State Key Laboratory of Mechanical System and Vibration, Shanghai, 200240 (China); Wang, Lin [Institute of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi' an, 710032 (China); Yu, Xiaoming [The Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016 (China); Feng, Yafei [Institute of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi' an, 710032 (China); Wang, Chengtao [School of Mechanical Engineering, Shanghai Jiao Tong University, State Key Laboratory of Mechanical System and Vibration, Shanghai, 200240 (China); Yang, Ke [The Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016 (China); Su, Daniel [School of Mechanical Engineering, Shanghai Jiao Tong University, State Key Laboratory of Mechanical System and Vibration, Shanghai, 200240 (China)

    2013-07-01

    Porous tantalum (Ta), produced via chemical vapor deposition (CVD) of commercially pure Ta onto a vitreous carbon, is currently available for use in orthopedic applications. However, the relatively high manufacturing cost and the incapability to produce customized implant using medical image data have limited its application to gain widespread acceptance. In this study, Ta film was deposited on porous Ti6Al4V scaffolds using CVD technique. Digital microscopy and scanning electron microscopy indicated that the Ta coating evenly covered the entire scaffold structure. X-ray diffraction analysis showed that the coating consisted of α and β phases of Ta. Goat mesenchymal stem cells were seeded and cultured on the Ti6Al4V scaffolds with and without coating. The tetrazolium-based colorimetric assay exhibited better cell adhesion and proliferation on Ta-coated scaffolds compared with uncoated scaffolds. The porous scaffolds were subsequently implanted in goats for 12 weeks. Histological analysis revealed similar bone formation around the periphery of the coated and uncoated implants, but bone ingrowth is better within the Ta-coated scaffolds. To demonstrate the ability of producing custom implant for clinical applications via this technology, we designed and fabricated a porous Ti6Al4V scaffold with segmental mandibular shape derived from patient computerized tomography data. - Highlights: • Ta film was coated on porous Ti6Al4V scaffold using chemical vapor deposition. • Tantalum coating allowed for higher levels of cell adhesion and proliferation. • Better new bone formation occurred inside the tantalum-coated scaffolds. • Clinical image data was integrated with EBM to fabricate customized scaffold.

  10. Tantalum coating on porous Ti6Al4V scaffold using chemical vapor deposition and preliminary biological evaluation

    International Nuclear Information System (INIS)

    Li, Xiang; Wang, Lin; Yu, Xiaoming; Feng, Yafei; Wang, Chengtao; Yang, Ke; Su, Daniel

    2013-01-01

    Porous tantalum (Ta), produced via chemical vapor deposition (CVD) of commercially pure Ta onto a vitreous carbon, is currently available for use in orthopedic applications. However, the relatively high manufacturing cost and the incapability to produce customized implant using medical image data have limited its application to gain widespread acceptance. In this study, Ta film was deposited on porous Ti6Al4V scaffolds using CVD technique. Digital microscopy and scanning electron microscopy indicated that the Ta coating evenly covered the entire scaffold structure. X-ray diffraction analysis showed that the coating consisted of α and β phases of Ta. Goat mesenchymal stem cells were seeded and cultured on the Ti6Al4V scaffolds with and without coating. The tetrazolium-based colorimetric assay exhibited better cell adhesion and proliferation on Ta-coated scaffolds compared with uncoated scaffolds. The porous scaffolds were subsequently implanted in goats for 12 weeks. Histological analysis revealed similar bone formation around the periphery of the coated and uncoated implants, but bone ingrowth is better within the Ta-coated scaffolds. To demonstrate the ability of producing custom implant for clinical applications via this technology, we designed and fabricated a porous Ti6Al4V scaffold with segmental mandibular shape derived from patient computerized tomography data. - Highlights: • Ta film was coated on porous Ti6Al4V scaffold using chemical vapor deposition. • Tantalum coating allowed for higher levels of cell adhesion and proliferation. • Better new bone formation occurred inside the tantalum-coated scaffolds. • Clinical image data was integrated with EBM to fabricate customized scaffold

  11. Mass transfer modeling on the separation of tantalum and niobium from dilute hydrofluoric media through a hollow fiber supported liquid membrane

    International Nuclear Information System (INIS)

    Buachuang, Duenphen; Ramakul, Prakorn; Leepipatpiboon, Natchanun; Pancharoen, Ura

    2011-01-01

    Highlights: → Simultaneous separation of tantalum and niobium from the mixture solution. → An extraction through a hollow fiber supported liquid membrane (HFSLM). → The effect on tantalum removal found from Aliquat 336. → The mathematical model focusing on the extraction side of the liquid membrane system was presented. → The mass transfer coefficients of the aqueous feed (k i ) and the organic membrane phase (k m ) for the system were estimated as 1.19 x 10 -5 and 1.39 x 10 -7 cm/s, respectively. → Experimental data and theoretical values were found to be in good agreement when the concentration of Aliquat336 in the membrane phase was below 4% (v/v). - Abstract: The separation of a mixture of tantalum and niobium in dilute hydrofluoric media via hollow fiber supported liquid membrane (HFSLM) was examined. Quaternary ammonium salt (Aliquat336) diluted in kerosene was used as a carrier. The various effects on the transport and separation of tantalum and niobium were studied: concentration of hydrofluoric acid in the feed solution, concentration of the carrier (Aliquat336) in the membrane phase, types of stripping solutions (NaClO 4 , thiourea and HCl) and their concentration. The extraction of tantalum in the membrane phase from 0.3 M hydrofluoric acid (HF) by 3% (v/v) Aliquat336 was achieved by leaving niobium in the feed solution. Quantitative recovery of tantalum was achieved by 0.2 M NaClO 4 . Furthermore, a mathematical model focusing on the extraction side of the liquid membrane system was presented in order to predict the concentration of tantalum at different times. The mass transfer coefficients of the aqueous feed (k i ) and the organic membrane phase (k m ) were estimated as 1.19 x 10 -5 and 1.39 x 10 -7 cm/s, respectively. Therefore, the mass transfer limiting step is the diffusion of tantalum-Aliquat336 through the liquid membrane. Moreover, mass transfer modeling was performed and the validity of the developed model evaluated. Experimental

  12. Mass transfer modeling on the separation of tantalum and niobium from dilute hydrofluoric media through a hollow fiber supported liquid membrane

    Energy Technology Data Exchange (ETDEWEB)

    Buachuang, Duenphen [Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330 (Thailand); Ramakul, Prakorn [Department of Chemical Engineering, Faculty of Engineering and Industrial Technology, Silpakorn University, Nakhon Pathom 73000 (Thailand); Leepipatpiboon, Natchanun [Chromatography and Separation Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Pancharoen, Ura, E-mail: ura.p.@chula.ac.th [Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330 (Thailand)

    2011-09-29

    Highlights: > Simultaneous separation of tantalum and niobium from the mixture solution. > An extraction through a hollow fiber supported liquid membrane (HFSLM). > The effect on tantalum removal found from Aliquat 336. > The mathematical model focusing on the extraction side of the liquid membrane system was presented. > The mass transfer coefficients of the aqueous feed (k{sub i}) and the organic membrane phase (k{sub m}) for the system were estimated as 1.19 x 10{sup -5} and 1.39 x 10{sup -7} cm/s, respectively. > Experimental data and theoretical values were found to be in good agreement when the concentration of Aliquat336 in the membrane phase was below 4% (v/v). - Abstract: The separation of a mixture of tantalum and niobium in dilute hydrofluoric media via hollow fiber supported liquid membrane (HFSLM) was examined. Quaternary ammonium salt (Aliquat336) diluted in kerosene was used as a carrier. The various effects on the transport and separation of tantalum and niobium were studied: concentration of hydrofluoric acid in the feed solution, concentration of the carrier (Aliquat336) in the membrane phase, types of stripping solutions (NaClO{sub 4}, thiourea and HCl) and their concentration. The extraction of tantalum in the membrane phase from 0.3 M hydrofluoric acid (HF) by 3% (v/v) Aliquat336 was achieved by leaving niobium in the feed solution. Quantitative recovery of tantalum was achieved by 0.2 M NaClO{sub 4}. Furthermore, a mathematical model focusing on the extraction side of the liquid membrane system was presented in order to predict the concentration of tantalum at different times. The mass transfer coefficients of the aqueous feed (k{sub i}) and the organic membrane phase (k{sub m}) were estimated as 1.19 x 10{sup -5} and 1.39 x 10{sup -7} cm/s, respectively. Therefore, the mass transfer limiting step is the diffusion of tantalum-Aliquat336 through the liquid membrane. Moreover, mass transfer modeling was performed and the validity of the

  13. Neutron displacement cross-sections for tantalum and tungsten at energies up to 1 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Broeders, C.H.M. [Institut fuer Reaktorsicherheit, Forschungszentrum Karlsruhe GmbH, Postfach 3640, 76021 Karlsruhe (Germany)]. E-mail: cornelis.broeders@irs.fzk.de; Konobeyev, A.Yu. [Institut fuer Reaktorsicherheit, Forschungszentrum Karlsruhe GmbH, Postfach 3640, 76021 Karlsruhe (Germany); Institute of Nuclear and Power Engineering, 249020 Obninsk (Russian Federation); Villagrasa, C. [Institut fuer Reaktorsicherheit, Forschungszentrum Karlsruhe GmbH, Postfach 3640, 76021 Karlsruhe (Germany)

    2005-06-30

    The neutron displacement cross-section has been evaluated for tantalum and tungsten at energies from 10{sup -5} eV up to 1 GeV. The nuclear optical model, the intranuclear cascade model combined with the pre-equilibrium and evaporation models were used for the calculations. The number of defects produced by recoil atoms nuclei in materials was calculated by the Norgett, Robinson, Torrens model and by the approach combining calculations using the binary collision approximation model and the results of the molecular dynamics simulation. The numerical calculations were done using the NJOY code, the ECIS96 code, the MCNPX code and the IOTA code.

  14. Fabrication and use of zircaloy/tantalum-sheathed cladding thermocouples and molybdenum/rhenium-sheathed fuel centerline thermocouples

    International Nuclear Information System (INIS)

    Wilkins, S.C.; Sepold, L.K.

    1985-01-01

    The thermocouples described in this report are zircaloy/tantalum-sheathed and molybdenum/rhenium alloy-sheathed instruments intended for fuel rod cladding and fuel centerline temperature measurements, respectively. Both types incorporate beryllium oxide insulation and tungsten/rhenium alloy thermoelements. These thermocouples, operated at temperatures of 2000 0 C and above, were developed for use in the internationally sponsored Severe Fuel Damage test series in the Power Burst Facility. The fabrication steps for both thermocouple types are described in detail. A laser-welding attachment technique for the cladding-type thermocouple is presented, and experience with alternate materials for cladding and fuel therocouples is discussed

  15. Metal derivatives of organo-phosphorous compounds. Part II : niobium(V) and tantalum(V) derivatives

    International Nuclear Information System (INIS)

    Puri, D.M.; Singh, Soran

    1981-01-01

    Reactions between niobium(V) chloride, tantalum(V) chloride and dialkyl/diaryl (Et-, Prsup(i)-, Busup(n)- and Ph-) phosphites have been studied in different molar ratios and under different conditions of temperature and solvent systems. The isolated complex compounds have been characterised on the basis of infrared spectral measurements, elemental analyses and magnetic susceptibility data. The polymeric nature of the products has been indicated by their molecular weights. The coordination of phosphite units to metal atom of the other molecule through phosphoryl oxygen gave rise to O-P-O-bridges. (author)

  16. Extension of the lifetime of tantalum filaments in the hot-wire (Cat) 3 Chemical Vapor Deposition process

    CSIR Research Space (South Africa)

    Knoesen, D

    2008-01-01

    Full Text Available , the filament is again exposed to pure hydrogen for a minimum of 5 min, the chamber then again evacuated to a vacuum better than 8×10−8 mbar before cutting the power to the filament. This has resulted in a filament life of 11 months, with an accumulated... process only treated by annealing before a deposition run, did not last long, and typically broke after 3 to 5 h of accumulated deposition time. Silicide formation is found along the full length of these tantalum filaments, with severe structural...

  17. Strength of shock-loaded single-crystal tantalum [100] determined using in situ broadband x-ray Laue diffraction.

    Science.gov (United States)

    Comley, A J; Maddox, B R; Rudd, R E; Prisbrey, S T; Hawreliak, J A; Orlikowski, D A; Peterson, S C; Satcher, J H; Elsholz, A J; Park, H-S; Remington, B A; Bazin, N; Foster, J M; Graham, P; Park, N; Rosen, P A; Rothman, S R; Higginbotham, A; Suggit, M; Wark, J S

    2013-03-15

    The strength of shock-loaded single crystal tantalum [100] has been experimentally determined using in situ broadband x-ray Laue diffraction to measure the strain state of the compressed crystal, and elastic constants calculated from first principles. The inferred strength reaches 35 GPa at a shock pressure of 181 GPa and is in excellent agreement with a multiscale strength model [N. R. Barton et al., J. Appl. Phys. 109, 073501 (2011)], which employs a hierarchy of simulation methods over a range of length scales to calculate strength from first principles.

  18. Influence of tantalum underlayer on magnetization dynamics in Ni{sub 81}Fe{sub 19} films

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Jae Hyun; Deorani, Praveen; Yoon, Jungbum; Yang, Hyunsoo, E-mail: eleyang@nus.edu.sg [Department of Electrical and Computer Engineering and NUSNNI, National University of Singapore, Singapore 117576 (Singapore); Hayashi, Masamitsu [National Institute for Materials Science, Tsukuba 305–0047 (Japan)

    2015-07-13

    The effect of tantalum (Ta) underlayer is investigated in Ni{sub 81}Fe{sub 19} thin films for magnetization dynamics. The damping parameters extracted from spin wave measurements increase systematically with increasing Ta thickness, whereas the damping parameters from ferromagnetic resonance measurements are found to be weakly dependent on the Ta thickness. The difference is attributed to propagating properties of spin wave and short spin diffusion length in Ta. The group velocity of spin waves is found to be constant for different Ta thicknesses, and nonreciprocity of spin waves is not affected by the Ta thickness. The experimental observations are supported by micromagnetic simulations.

  19. 188Re-loaded lipid nanocapsules as a promising radiopharmaceutical carrier for internal radiotherapy of malignant gliomas

    International Nuclear Information System (INIS)

    Allard, E.; Hindre, F.; Passirani, C.; Lemaire, L.; Benoit, J.P.; Lepareur, N.; Noiret, N.; Menei, P.

    2008-01-01

    Lipid nanocapsules (LNC) entrapping lipophilic complexes of 188 Re( 188 Re(S 3 CPh) 2 (S 2 CPh) [ 188 Re-SSS]) were investigated as a novel radiopharmaceutical carrier for internal radiation therapy of malignant gliomas. The present study was designed to evaluate the efficacy of intra-cerebral administration of 188 Re-SSS LNC by means of convection-enhanced delivery (CED) on a 9L rat brain tumour model. Female Fischer rats with 9L glioma were treated with a single injection of 188 Re-SSS LNC by CED 6days after cell implantation. Rats were put into random groups according to the dose infused: 12, 10, 8 and 3Gy in comparison with blank LNC, perrhenate solution (4Gy) and non-treated animals. The radionuclide brain retention level was evaluated by measuring 188 Re elimination in faeces and urine over 72h after the CED injection. The therapeutic effect of 188 Re-SSS LNC was assessed based on animal survival. CED of 188 Re perrhenate solution resulted in rapid drug clearance with a brain T 1/2 of 7h. In contrast, when administered in LNC, 188 Re tissue retention was greatly prolonged, with only 10% of the injected dose being eliminated at 72h. Rat median survival was significantly improved for the group treated with 8Gy 188 Re-SSS LNC compared to the control group and blank LNC-treated animals. The increase in the median survival time was about 80% compared to the control group; 33% of the animals were long-term survivors. The dose of 8Gy proved to be a very effective dose, between toxic (10-12Gy) and ineffective (3-4Gy) doses. These findings show that CED of 188 Re-loaded LNC is a safe and potent anti-tumour system for treating malignant gliomas. Our data are the first to show the in vivo efficacy of 188 Re internal radiotherapy for the treatment of brain malignancy. (orig.)

  20. Sintered tantalum carbide coatings on graphite substrates: Highly reliable protective coatings for bulk and epitaxial growth

    International Nuclear Information System (INIS)

    Nakamura, Daisuke; Suzumura, Akitoshi; Shigetoh, Keisuke

    2015-01-01

    Highly reliable low-cost protective coatings have been sought after for use in crucibles and susceptors for bulk and epitaxial film growth processes involving wide bandgap materials. Here, we propose a production technique for ultra-thick (50–200 μmt) tantalum carbide (TaC) protective coatings on graphite substrates, which consists of TaC slurry application and subsequent sintering processes, i.e., a wet ceramic process. Structural analysis of the sintered TaC layers indicated that they have a dense granular structure containing coarse grain with sizes of 10–50 μm. Furthermore, no cracks or pinholes penetrated through the layers, i.e., the TaC layers are highly reliable protective coatings. The analysis also indicated that no plastic deformation occurred during the production process, and the non-textured crystalline orientation of the TaC layers is the origin of their high reliability and durability. The TaC-coated graphite crucibles were tested in an aluminum nitride (AlN) sublimation growth process, which involves extremely corrosive conditions, and demonstrated their practical reliability and durability in the AlN growth process as a TaC-coated graphite. The application of the TaC-coated graphite materials to crucibles and susceptors for use in bulk AlN single crystal growth, bulk silicon carbide (SiC) single crystal growth, chemical vapor deposition of epitaxial SiC films, and metal-organic vapor phase epitaxy of group-III nitrides will lead to further improvements in crystal quality and reduced processing costs

  1. Temperature and strain-rate dependence of the flow stress of ultrapure tantalum single crystals

    International Nuclear Information System (INIS)

    Werner, M.

    1987-01-01

    Measurements of the temperature dependence of the cyclic flow stress of ultrapure tantalum single crystals (RRR >∼ 14000) are extended to lower temperatures. After cyclic deformation well into saturation at 400 K, the temperature dependence of the flow stress is measured between 80 and 450 K at five different plastic resolved shear-strain rates, ε pl , in the range 2 x 10 -5 to 6 x 10 -3 s -1 . Below a critical temperature T k the flow stress is dominantly controlled by the mobility of screw dislocations. A recent theory of Seeger describes the 'thermal' component, σ*, of the flow stress (resolved shear stress) in the temperature and stress regime where the strain rate is determined by the formation and migration of kink pairs. The analytical expressions are valid in well-defined ranges of stress and temperature. The evaluation of the experimental data yields a value for the formation enthalpy of two isolated kinks 2H k = 0.98 eV. From the low-stress (σ* k = 2.0 x 10 -6 m 2 s -1 . The product of the density of mobile screw dislocations and the distance between insurmountable obstacles is found to be 2 x 10 -5 m -1 . The stress dependence of the kink-pair formation enthalpy H kp follows the theoretically predicted curve in the elastic-interaction stress regime. At the transition to the line-tension approximation (near σ* ∼ 80 MPa) the activation volume increases rather abruptly. Moreover, the quantitative analysis involves kinks other than those of minimum height. The most likely candidates are kinks on {211} planes. (author)

  2. Surface chemistry and cytotoxicity of reactively sputtered tantalum oxide films on NiTi plates

    Energy Technology Data Exchange (ETDEWEB)

    McNamara, K. [Materials and Surface Science Institute, University of Limerick, Limerick (Ireland); Department of Physics & Energy, University of Limerick, Limerick (Ireland); Kolaj-Robin, O.; Belochapkine, S.; Laffir, F. [Materials and Surface Science Institute, University of Limerick, Limerick (Ireland); Gandhi, A.A. [Materials and Surface Science Institute, University of Limerick, Limerick (Ireland); Department of Physics & Energy, University of Limerick, Limerick (Ireland); Tofail, S.A.M., E-mail: tofail.syed@ul.ie [Materials and Surface Science Institute, University of Limerick, Limerick (Ireland); Department of Physics & Energy, University of Limerick, Limerick (Ireland)

    2015-08-31

    NiTi, an equiatomic alloy containing nickel and titanium, exhibits unique properties such as shape memory effect and superelasticity. NiTi also forms a spontaneous protective titanium dioxide (TiO{sub 2}) layer that allows its use in biomedical applications. Despite the widely perceived biocompatibility there remain some concerns about the sustainability of the alloy's biocompatibility due to the defects in the TiO{sub 2} protective layer and the presence of high amount of sub-surface Ni, which can give allergic reactions. Many surface treatments have been investigated to try to improve both the corrosion resistance and biocompatibility of this layer. For such purposes, we have sputter deposited tantalum (Ta) oxide thin films onto the surface of the NiTi alloy. Despite being one of the promising metals for biomedical applications, Ta, and its various oxides and their interactions with cells have received relatively less attention. The oxidation chemistry, crystal structure, morphology and biocompatibility of these films have been investigated. In general, reactive sputtering especially in the presence of a low oxygen mixture yields a thicker film with better control of the film quality. The sputtering power influenced the surface oxidation states of Ta. Both microscopic and quantitative cytotoxicity measurements show that Ta films on NiTi are biocompatible with little to no variation in cytotoxic response when the surface oxidation state of Ta changes. - Highlights: • Reactive sputtering in low oxygen mixture yields thicker better quality films. • Sputtering power influenced surface oxidation states of Ta. • Cytotoxicity measurements show Ta films on NiTi are biocompatible. • Little to no variation in cytotoxic response when oxidation state changes.

  3. Unrecoverable bi-products of drilling titanium alloy and tantalum metal implants: a pilot study.

    Science.gov (United States)

    Skowronek, Paweł; Olszewski, Paweł; Święszkowski, Wojciech; Synder, Marek; Sibiński, Marcin; Mazek, Jacek

    2018-05-01

    Trabecular metal implants with a porous architecture that allows for the incorporation of bone into the implant during healing are gaining popularity in alloplastic revision procedures. The bi-products of drilling titanium alloy (Ti) and tantalum (Ta) implants have not been previously assessed. Four holes were drilled in each of two spatially porous trabecular implants, one Ta and the other Ti alloy (Ti-6Al-7Nb), for this pilot in vitro study. The particles were flushed out with a continuous flow of saline. The particles' weight and the volume were then measured using a Radwag XA 110/2X (USA) laboratory balance. The total volume of the obtained metal fines was measured by titration using a 10 mm 3 measurement system. A cobalt carbide bit was used since the holes could not be made with a standard bone drill. Each Ti and Ta implant lost 1.26 g and 2.48 g of mass, respectively. The volume of free particles recovered after each stage was 280 mm 3 and 149 mm 3 , respectively. Approximately 0.6% of the total implant mass was not recovered after drilling (roughly 2% of the mass of the particles created by drilling), despite the use of 5 µm filters. It is technically difficult to drill holes in Ti and Ta implants using standard surgical tools. The drilling process creates a considerable amount of metal particles, which cannot be recovered despite intensive flushing. This may have an adverse influence on the bio-functionality (survival) of the endoprosthesis and present deleterious systemic consequences.

  4. Determination of phase boundaries and diffusion parameters in tantalum hydrides in pulsed NMR

    International Nuclear Information System (INIS)

    Hornung, P.A.

    1978-04-01

    Proton spin-lattice relaxation times T 1 were measured over a wide range of temperature (77 K to 470 K) and compositions (H/Ta = 0.155 to 0.677) in the tantalum-hydrogen system at a frequency of 40,000 MHz. In the high temperature solid solution α phase, the activation energy for hydrogen diffusion was found to be 0.140 +- 0.002 eV/atom, and the value of the jump rate (or its corresponding correlation time) was found to be essentially constant throughout the range of compositions studied. The conduction electron contribution to T 1 measured in the α phase agreed qualitatively with the trend shown by previously published susceptibility data. The single phase epsilon region and the α + epsilon two-phase region were particularly noted. It could also be concluded from the measurements that the hydrogen jump rate decreased by a factor of approximately 7.2 from the α phase to the ordered phases at low temperatures and slightly decreased further in the epsilon phase. Anomalous relaxation times were found in the low temperature range (77 K less than or equal to T less than or equal to K). In this region, T 1 remains essentially constant, and does not follow the usual temperature dependence for either motional or electronic relaxation. Two possible explanations for this behavior were considered. The first involves proton cross-relaxation to the 181 Ta nuclei which would sample the spectral density of magnetic fluctuations in the sample at several frequencies because of the probable very strong 181 Ta quadrupole interaction strength. The second explanation postulates that the hydrogen diffusional jump path involves an intermediate metastable state

  5. Evaluation of 10V Chip Polymer Tantalum Capacitors for Space Applications

    Science.gov (United States)

    Teverovsky, Alexander A.

    2016-01-01

    Due to low ESR and safe failure mode, new technology chip polymer tantalum capacitors (CPTC) have gained popularity in the electronics design community, first in commercial applications, and now in hi-rel and space systems. The major drawbacks of these parts are high leakage currents, degradation under environmental stresses, and a relatively narrow temperature range of operating and storage conditions. Several studies have shown that a certain amount of moisture in polymer cathodes is necessary for a normal operation of the parts. This might limit applications of CPTCs in space systems and requires analysis of long-term exposure to deep vacuum conditions on their performance and reliability. High leakage currents and limited maximum operational temperature complicate accelerated testing that is necessary to assess long-term reliability and require new screening and qualification procedures for quality assurance. A better understanding of behavior of CPTCs as compared to traditional, MnO2, capacitors is necessary to develop adequate approaches for QA system for space applications. A specific of CPTCs is that different materials and processes might be used for low-voltage (10 V and less) and high-voltage (above 10 V) capacitors, so performance and degradation processes in these groups require separate analysis. In this work, that is a part of the NASA Electronic Parts and Packaging (NEPP) program, degradation of AC and DC characteristics under environmental stresses at different temperatures and voltages have been studied in nine lots of commercial and automotive grade capacitors rated to 10 V. Results of analysis of leakage currents, high temperature storage (HTS) up to 5000 hrs in vacuum and air at different temperatures, and Highly Accelerated Life Testing (HALT) in the range from 85 C to 145 C are presented. Temperature and voltage acceleration factors were calculated based on approximation of distributions of degradation rates with a general log-linear Weibull

  6. Electrodeposition of tantalum on carbon black in non-aqueous solution and its electrocatalytic properties

    International Nuclear Information System (INIS)

    Jo, Ara; Lee, Youngmi; Lee, Chongmok

    2016-01-01

    In this work, we synthesized tantalum (Ta) nanoclusters on carbon black (Ta/CB) via simple electrodeposition in non-aqueous solvent, acetonitrile (ACN) at ambient temperature. Transmission electron microscopy (TEM) images showed that the electrodeposited Ta nanoclusters consisted of tiny Ta nanoparticles. X-ray photoelectron spectroscopy (XPS) result represented that the outermost Ta formed the native oxide on Ta/CB due to its ambient exposure to air. Electrochemical catalytic properties of prepared Ta/CB on glassy carbon electrode (Ta/CB/GC) were investigated toward reductions of oxygen and hydrogen peroxide, and oxidations of ascorbic acid and dopamine. For oxygen reduction reaction (ORR) in acid, Ta/CB/GC represented a decent electrocatalytic performance which was better or comparable to bare Pt. The operational stability in acidic condition was maintained up to 500 repetitive potential cycles presumably due to the protective native Ta oxide layer. Ta/CB/GC also showed high amperometric sensitivity (4.5 (±0.1_6) mA mM"−"1 cm"−"2, n = 5) for reduction of hydrogen peroxide in 0.1 M phosphate buffer solution (PBS, pH 7.4). In addition, Ta/CB/GC was demonstrated for the possibility of simultaneous detection of ascorbic acid and dopamine using differential pulse voltammetry (DPV). - Highlights: • We electrodeposited Ta nanoclusters (Ta/CB/GC) in acetonitrile at room temperature. • The Ta/CB/GC showed better or comparable performance to bare Pt for ORR. • The Ta/CB/GC showed high sensitivity for reduction of hydrogen peroxide at pH 7.4. • The Ta/CB/GC showed possible simultaneous detection of ascorbic acid and dopamine. • We extended the applicability of Ta electrode material for various electrocatalytic reactions.

  7. Measurement and Analysis of Activation Induced in Lanthanum, Erbium and Tantalum by Fusion Peak Neutrons

    International Nuclear Information System (INIS)

    Klix, A.; Eichin, R.; Freiesleben, H.; Schomburg, K.; Seidel, K.; Unholzer, S.; Forrest, R.A.

    2006-01-01

    The large fluxes of neutrons in the materials of a fusion device during operation produce activation that is relevant to operational safety and decommissioning. Nuclides with a broad range of half-lives have to be included in the corresponding analyses. The activity with decay times ranging from the order of magnitude of minutes to weeks is of interest with respect to heat production and shut-down dose rates, whereas the long-term activity determines the waste management. The activity is mainly produced by two components of the neutron flux spectrum, by thermal neutrons and by the 14-MeV D-T fusion neutrons. Analyses of the material activation rely on calculations with inventory codes and libraries containing activation and decay data. To gain trust in the results of such calculations data and codes have to be validated experimentally. In the present work, the European Activation System (EASY, inventory code FISPACT and data library EAF) was tested in benchmark experiments on Lanthanum, Erbium and Tantalum. They are constituents of fusion reactor structural materials such as EUROFER and insulating coatings for liquid breeder systems. Small samples of the materials were irradiated in a D-T neutron field. The gamma-radioactivity following irradiation was measured several times during decay and nuclide activities were derived. For each of the measured activities the corresponding value was calculated with EASY, and the calculated-to-experimental ratios (C/E) were determined. The nuclear reactions producing the activities were also analysed. The C/E ratios obtained for the individual activities will be used for discussing the activation performance and the contact dose rate of the materials at fusion power plant conditions. (author)

  8. Sintered tantalum carbide coatings on graphite substrates: Highly reliable protective coatings for bulk and epitaxial growth

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Daisuke; Suzumura, Akitoshi; Shigetoh, Keisuke [Toyota Central R and D Labs., Inc., Nagakute, Aichi 480-1192 (Japan)

    2015-02-23

    Highly reliable low-cost protective coatings have been sought after for use in crucibles and susceptors for bulk and epitaxial film growth processes involving wide bandgap materials. Here, we propose a production technique for ultra-thick (50–200 μmt) tantalum carbide (TaC) protective coatings on graphite substrates, which consists of TaC slurry application and subsequent sintering processes, i.e., a wet ceramic process. Structural analysis of the sintered TaC layers indicated that they have a dense granular structure containing coarse grain with sizes of 10–50 μm. Furthermore, no cracks or pinholes penetrated through the layers, i.e., the TaC layers are highly reliable protective coatings. The analysis also indicated that no plastic deformation occurred during the production process, and the non-textured crystalline orientation of the TaC layers is the origin of their high reliability and durability. The TaC-coated graphite crucibles were tested in an aluminum nitride (AlN) sublimation growth process, which involves extremely corrosive conditions, and demonstrated their practical reliability and durability in the AlN growth process as a TaC-coated graphite. The application of the TaC-coated graphite materials to crucibles and susceptors for use in bulk AlN single crystal growth, bulk silicon carbide (SiC) single crystal growth, chemical vapor deposition of epitaxial SiC films, and metal-organic vapor phase epitaxy of group-III nitrides will lead to further improvements in crystal quality and reduced processing costs.

  9. Synthesis of a Bis(thiophenolate)pyridine Ligand and Its Titanium, Zirconium, and Tantalum Complexes

    KAUST Repository

    Lenton, Taylor N.

    2012-11-12

    A precursor to a new tridentate LX 2 type ligand, bis(thiophenol)pyridine ((SNS)H 2 = (2-C 6H 4SH) 2-2,6-C 5H 3N), was prepared. Bis(thiophenolate)pyridine complexes of Ti, Zr, and Ta having dialkylamido coligands were synthesized and structurally characterized. The zirconium complex (SNS)Zr(NMe 2) 2 (4) displays C 2 symmetry in the solid state, unlike a related bis(phenolate)pyridine compound, C s-symmetric (ONO)Ti(NMe 2) 2. This change is likely the result of strain about the sulfur atom in the six-membered chelate with longer metal-sulfur and carbon-sulfur bonds. Solid-state structures of tantalum complexes (SNS)Ta(NMe 2) 3 (5) and (SNS)TaCl(NEt 2) 2 (6) also display pronounced C 2 twisting of the SNS ligand. 1D and 2D NMR experiments show that 5 is fluxional, with rotation about the Ta-N(amide) bonds occurring on the NMR time scale that interchange the equatorial amide methyl groups (ΔG ‡ 393 = 25.0(3) kcal/mol). The fluxional behavior of 6 in solution was also studied by variable-temperature 1H NMR. Observation of separate signals for the diastereotopic protons of the methylene unit of the diethylamide indicates that the complex remains locked on the NMR time scale in one diastereomeric conformation at temperatures below -50 °C, fast rotation about the equatorial amide Ta-N bonds occurs at higher temperature (ΔG ‡ 393 = 13.4(3) kcal/mol), and exchange of diastereomeric methylene protons occurs via inversion at Ta that interconverts antipodes (ΔG ‡ 393 ≈ 14(1) kcal/mol). © 2012 American Chemical Society.

  10. Early stage of deformation in tungsten, tantalum, and nickel single crystals

    International Nuclear Information System (INIS)

    Pinatti, D.G.

    1977-01-01

    High purity Tantalum, Tungsten and Nickel single crystals were tested in simple tension between 77 and 300 K. The Ta and W was oriented for maximum resolved shear stress on the [111] (101) system. Simultaneously microstrain and ultrasonic propagation measurements (attenuation and modulus defect) were performed at various stress bias in order to test details of theories concerning the preyield region and the flow stress in body-centered cubic refractory metals. The experimental retical predictions for the kink chain model over the string model for dislocation. It appears that double kink nucleation in non-screw dislocations has negligible effect in this domains. The results for annealed Ta exhibited no stress bias effect on the ultrasonic propagation measurements, which suggest that the strong influence of impurities mask our ability to discern this fine structure for dislocation motion. For prestrained W and Ta, it was found that double-kink nucleation on nonscrew dislocation plays an important role and revealed interesting results with respect to our understanding of the intrinsic dislocation structure in bcc metals. These results support the kink chain model for dislocation unambiguously. The experiments on the prestrained samples also exhibited experimental results which are qualitatively but not quantitatively in agreement with the theoretical predictions of Seeger and Sectak. The Ni single crystals were prestrained between 10 and 23 percent in stage II, and the microstrain damping loops have been studied as a function of stress amplitude, temperature and magnetic field. The predominant hysteretic contribution to the observed decrement was analyzed according to the model of Roberts (Al. 14, Al. 15), and good agreement between theory and experiment was found

  11. Tantalum, Niobium and Titanium Coatings for Biocompatibility Improvement of Dental Implants

    Directory of Open Access Journals (Sweden)

    Vajihesadat Mortazavi

    2007-01-01

    Full Text Available Introduction: Metals have a wide range of applications in implant and prosthetic materials in dentistry.Corrosion resistance and biocompatibility of metals should be improved in order to utilizethem as biomaterials. The aim of this work was to prepare metallic coatings on 316L stainless steel dental implants, to evaluate the corrosion characteristics of the uncoated and metallic coated dentalimplants as an indication of biocompatibility and, to compare the effect of the type of the coatings on biocompatibility.Materials and Methods: In this in vitro evaluation, three types of metallic coatings including tantalum, niobium and titanium coatings were compared using a physical vapor deposition process on 316L stainless steel dental implants. Structural characterization techniques including X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis were utilized to investigatethe microstructure and morphology of the coatings. Electrochemical potentiodynamic tests were performed in two types of physiological solutions at 37±1°C in order to determine and compare the corrosioncurrent density and corrosion potential characteristics. The mean values were statistically compared by ANOVA at a 95% level of confidence.Results: the findings showed that all of the three types of metallic coatings had a positive effect on improvement of the corrosion behavior. The coatings could increase the corrosion resistance of 316L stainless steel and this trend was independent of the type of physiological environment.Conclusion: The biocompatible metallic coatings could decrease the corrosion current density and is a distinct advantage for prevention of ion release. Decreasing ion release can improve the biocompatibility of the dental implant, and consequently can prevent tissue damage, tissue inflammation and irritation, and can also lead to obtaining a desirable histopathological response.

  12. Electrodeposition of tantalum on carbon black in non-aqueous solution and its electrocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Ara; Lee, Youngmi, E-mail: youngmilee@ewha.ac.kr; Lee, Chongmok, E-mail: cmlee@ewha.ac.kr

    2016-08-24

    In this work, we synthesized tantalum (Ta) nanoclusters on carbon black (Ta/CB) via simple electrodeposition in non-aqueous solvent, acetonitrile (ACN) at ambient temperature. Transmission electron microscopy (TEM) images showed that the electrodeposited Ta nanoclusters consisted of tiny Ta nanoparticles. X-ray photoelectron spectroscopy (XPS) result represented that the outermost Ta formed the native oxide on Ta/CB due to its ambient exposure to air. Electrochemical catalytic properties of prepared Ta/CB on glassy carbon electrode (Ta/CB/GC) were investigated toward reductions of oxygen and hydrogen peroxide, and oxidations of ascorbic acid and dopamine. For oxygen reduction reaction (ORR) in acid, Ta/CB/GC represented a decent electrocatalytic performance which was better or comparable to bare Pt. The operational stability in acidic condition was maintained up to 500 repetitive potential cycles presumably due to the protective native Ta oxide layer. Ta/CB/GC also showed high amperometric sensitivity (4.5 (±0.1{sub 6}) mA mM{sup −1} cm{sup −2}, n = 5) for reduction of hydrogen peroxide in 0.1 M phosphate buffer solution (PBS, pH 7.4). In addition, Ta/CB/GC was demonstrated for the possibility of simultaneous detection of ascorbic acid and dopamine using differential pulse voltammetry (DPV). - Highlights: • We electrodeposited Ta nanoclusters (Ta/CB/GC) in acetonitrile at room temperature. • The Ta/CB/GC showed better or comparable performance to bare Pt for ORR. • The Ta/CB/GC showed high sensitivity for reduction of hydrogen peroxide at pH 7.4. • The Ta/CB/GC showed possible simultaneous detection of ascorbic acid and dopamine. • We extended the applicability of Ta electrode material for various electrocatalytic reactions.

  13. Cobalt and tantalum tracers measured by activation analysis in sediment transport studies

    Energy Technology Data Exchange (ETDEWEB)

    Groot, A.J. de [Institute for Soil Fertility, Haren (Netherlands); Allersma, E [Delft Hydraulics Laboratory, Delft (Netherlands); Bruin, M de; Houtman, J P.W. [Reactor Institute, Delft (Netherlands)

    1970-09-15

    The paper proposes certain principles of research to be used in investigating the origin and transport of fine-grained sediments in rivers and sea arms in connection with siltation problems of harbours and navigation channels. An element, which either does not occur in the sediment or only occurs in minute quantities, is fixed to the mud from the river or sea arm. After the material is marked it is returned to the water course where it mixes with the solids moving naturally. At specified points throughout the water course sediment samples are taken to determine the marking element by activation analysis. This gives an insight into the flow path of the suspended matter. The selection and successful application of tracers that can be measured by activation analysis depends on the sensitivity of detection, the natural occurrence of the relevant elements in the sediments under investigation and the fixation capacity of the tracer to the various grain size fractions. Further, the influence of the added element on the sedimentation behaviour of the mud in suspension and on the desorption properties must be considered. The irradiation of Co and Ta with thermal neutrons gives rise to a very sensitive evaluation of the original elements present. The fixation process of Co is restricted to sediments with special characteristics; Ta, however, can adhere tightly to any sediment. Tantalum also has the advantage that its natural content in sediments is very low. Large quantities (several per cent by weight) can adhere to the sediment without changing the sedimentation properties to an appreciable extent. Hardly any losses occur during leaching experiments simulating natural conditions. A detailed treatment is given of the chemical aspects of the method, including the behaviour of the elements used in the light of the general environmental processes of sediment constituents in deltaic systems. Finally, the scope and limits of the method are discussed. (author)

  14. Cobalt and Tantalum Tracers Measured by Activation Analysis in Sediment Transport Studies

    Energy Technology Data Exchange (ETDEWEB)

    Groot, A.J. de [Institute for Soil Fertility, Haren (Netherlands); Allersma, E. [Delft Hydraulics Laboratory, Delft (Netherlands); Bruin, M. de; Houtman, J. P.W. [Reactor Institute, Delft (Netherlands)

    1970-09-15

    The paper proposes certain principles of research to be used in investigating the origin and transport of fine-grained sediments in rivers and sea arms in connection with siltation problems of harbours and navigation channels. An element, which either does not occur in the sediment or only occurs in minute quantities, is fixed to the mud from the river or sea arm. After the material is marked it is returned to the water course where it mixes with the solids moving naturally. At specified points throughout the water course sediment samples are taken to determine the marking element by activation analysis. This gives an insight into the flow path of the suspended matter. The selection and successful application of tracers that can be measured by activation analysis depends on the sensitivity of detection, the natural occurrence of the relevant elements in the sediments under investigation and the fixation capacity of the tracer to the various grain size fractions. Further, the influence of the added element on the sedimentation behaviour of the mud in suspension and on the desorption properties must be considered. The irradiation of Co and Ta with thermal neutrons gives rise to a very sensitive evaluation of the original elements present. The fixation process of Co is restricted to sediments with special characteristics; Ta, however, can adhere tightly to any sediment. Tantalum also has the advantage that its natural content in sediments is very low. Large quantities (several per cent by weight) can adhere to the sediment without changing the sedimentation properties to an appreciable extent. Hardly any losses occur during leaching experiments simulating natural conditions. A detailed treatment is given of the chemical aspects of the method, including the behaviour of the elements used in the light of the general environmental processes of sediment constituents in deltaic systems. Finally, the scope and limits of the method are discussed. (author)

  15. XPS investigation of monatomic and cluster argon ion sputtering of tantalum pentoxide

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, Robin, E-mail: r.simpson@surrey.ac.uk [The Surface Analysis Laboratory, Department of Mechanical Engineering Sciences, University of Surrey (United Kingdom); Thermo Scientific, East Grinstead (United Kingdom); White, Richard G. [Thermo Scientific, East Grinstead (United Kingdom); Watts, John F.; Baker, Mark A. [The Surface Analysis Laboratory, Department of Mechanical Engineering Sciences, University of Surrey (United Kingdom)

    2017-05-31

    Highlights: • Ion beam induced oxide reduction from monatomic and gas cluster ion beam exposure are compared. • Lower relative level of preferential sputtering is shown in gas cluster ion beam depth profiling. • A lack of “steady state” is observed in gas cluster ion beam depth profiles of tantalum pentoxide. • Possible mechanisms behind the observed results, including temperature effects are proposed. - Abstract: In recent years, gas cluster ion beams (GCIB) have become the cutting edge of ion beam technology to sputter etch organic materials in surface analysis. However, little is currently known on the ability of argon cluster ions (Ar{sub n}{sup +}) to etch metal oxides and other technologically important inorganic compounds and no depth profiles have previously been reported. In this work, XPS depth profiles through a certified (European standard BCR-261T) 30 nm thick Ta{sub 2}O{sub 5} layer grown on Ta foil using monatomic Ar{sup +} and Ar{sub 1000}{sup +} cluster ions have been performed at different incident energies. The preferential sputtering of oxygen induced using 6 keV Ar{sub 1000}{sup +} ions is lower relative to 3 keV and 500 eV Ar{sup +} ions. Ar{sup +} ions exhibit a steady state O/Ta ratio through the bulk oxide but Ar{sub 1000}{sup +} ions show a gradual decrease in the O/Ta ratio as a function of depth. The depth resolution and etch rate is substantially better for the monatomic beam compared to the cluster beam. Higher O concentrations are observed when the underlying Ta bulk metal is sputtered for the Ar{sub 1000}{sup +} profiles compared to the Ar{sup +} profiles.

  16. Biokinetic and dosimetric studies of 188Re-hyaluronic acid: a new radiopharmaceutical for treatment of hepatocellular carcinoma

    International Nuclear Information System (INIS)

    Melendez-Alafort, Laura; Nadali, Anna; Zangoni, Elena; Banzato, Alessandra; Rondina, Maria; Rosato, Antonio; Mazzi, Ulderico

    2009-01-01

    Hepatocellular carcinoma (HCC) is the most common primary liver cancer and has very limited therapeutic options. Recently, it has been found that hyaluronic acid (HA) shows selective binding to CD44 receptors expressed in most cancer histotypes. Since the trend in cancer treatment is the use of targeted radionuclide therapy, the aim of this research was to label HA with rhenium-188 and to evaluate its potential use as a hepatocarcinoma therapeutic radiopharmaceutical. Methods: 188 Re-HA was prepared by a direct labelling method to produce a ReO(O-COO) 2 -type coordination complex. 188 Re-HA protein binding and its stability in saline, phosphate buffer, human serum and cysteine solutions were determined. Biokinetic and dosimetric data were estimated in healthy mice (n=60) using the Medical Internal Radiation Dose methodology and mouse model beta-absorbed fractions. To evaluate liver toxicity, alanine aminotranferase (AST) and aspartate aminotranferase (ALT) levels in mice were assessed and the liver maximum tolerated dose (MTD) of 188 Re-HA was determined. Results: A stable complex of 188 Re-HA was obtained with high radiochemical purity (>90%) and low serum protein binding (2%). Biokinetic studies showed a rapid blood clearance (T 1/2 α=21 min). Four hours after administration, 188 Re-HA was almost totally removed from the blood by the liver due to the selective uptake via HA-specific receptors (73.47±5.11% of the injected dose). The liver MTD in mice was ∼40 Gy after 7.4 MBq of 188 Re-HA injection. Conclusions: 188 Re-HA complex showed good stability, pharmacokinetic and dosimetric characteristics that confirm its potential as a new agent for HCC radiation therapy.

  17. Biokinetic and dosimetric studies of {sup 188}Re-hyaluronic acid: a new radiopharmaceutical for treatment of hepatocellular carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Melendez-Alafort, Laura [Dipartimento di Scienze Farmaceutiche, Universita degli Studi di Padova, 35131 Padua (Italy); Nadali, Anna; Zangoni, Elena [Dipartimento di Scienze Farmaceutiche, Universita degli Studi di Padova, 35131 Padua (Italy); Banzato, Alessandra; Rondina, Maria [Dipartimento di Scienze Oncologiche e Chirurgiche, Universita degli Studi di Padova, Padua (Italy); Rosato, Antonio [Dipartimento di Scienze Oncologiche e Chirurgiche, Universita degli Studi di Padova, Padua (Italy); Istituto Oncologico Veneto, IOV, Padova, Padua (Italy); Mazzi, Ulderico [Dipartimento di Scienze Farmaceutiche, Universita degli Studi di Padova, 35131 Padua (Italy)

    2009-08-15

    Hepatocellular carcinoma (HCC) is the most common primary liver cancer and has very limited therapeutic options. Recently, it has been found that hyaluronic acid (HA) shows selective binding to CD44 receptors expressed in most cancer histotypes. Since the trend in cancer treatment is the use of targeted radionuclide therapy, the aim of this research was to label HA with rhenium-188 and to evaluate its potential use as a hepatocarcinoma therapeutic radiopharmaceutical. Methods: {sup 188}Re-HA was prepared by a direct labelling method to produce a ReO(O-COO){sub 2}-type coordination complex. {sup 188}Re-HA protein binding and its stability in saline, phosphate buffer, human serum and cysteine solutions were determined. Biokinetic and dosimetric data were estimated in healthy mice (n=60) using the Medical Internal Radiation Dose methodology and mouse model beta-absorbed fractions. To evaluate liver toxicity, alanine aminotranferase (AST) and aspartate aminotranferase (ALT) levels in mice were assessed and the liver maximum tolerated dose (MTD) of {sup 188}Re-HA was determined. Results: A stable complex of {sup 188}Re-HA was obtained with high radiochemical purity (>90%) and low serum protein binding (2%). Biokinetic studies showed a rapid blood clearance (T{sub 1/2}{alpha}=21 min). Four hours after administration, {sup 188}Re-HA was almost totally removed from the blood by the liver due to the selective uptake via HA-specific receptors (73.47{+-}5.11% of the injected dose). The liver MTD in mice was {approx}40 Gy after 7.4 MBq of {sup 188}Re-HA injection. Conclusions: {sup 188}Re-HA complex showed good stability, pharmacokinetic and dosimetric characteristics that confirm its potential as a new agent for HCC radiation therapy.

  18. Fabrication of Nano-Crossbar Resistive Switching Memory Based on the Copper-Tantalum Pentoxide-Platinum Device Structure

    Science.gov (United States)

    Olga Gneri, Paula; Jardim, Marcos

    Resistive switching memory has been of interest lately not only for its simple metal-insulator-metal (MIM) structure but also for its promising ease of scalability an integration into current CMOS technologies like the Field Programmable Gate Arrays and other non-volatile memory applications. There are several resistive switching MIM combinations but under this scope of research, attention will be paid to the bipolar resistive switching characteristics and fabrication of Tantalum Pentaoxide sandwiched between platinum and copper. By changing the polarity of the voltage bias, this metal-insulator-metal (MIM) device can be switched between a high resistive state (OFF) and low resistive state (ON). The change in states is induced by an electrochemical metallization process, which causes a formation or dissolution of Cu metal filamentary paths in the Tantalum Pentaoxide insulator. There is very little thorough experimental information about the Cu-Ta 2O5-Pt switching characteristics when scaled to nanometer dimensions. In this light, the MIM structure was fabricated in a two-dimensional crossbar format. Also, with the limited available resources, a multi-spacer technique was formulated to localize the active device area in this MIM configuration to less than 20nm. This step is important in understanding the switching characteristics and reliability of this structure when scaled to nanometer dimensions.

  19. A genetic algorithm approach for evaluation of optical functions of very thin tantalum pentoxide films on Si substrate

    International Nuclear Information System (INIS)

    Sharlandjiev, P S; Nazarova, D I

    2013-01-01

    The optical characteristics of tantalum pentoxide films, deposited on Si(100) substrate by reactive sputtering, are studied. These films are investigated as high-kappa materials for the needs of nano-electronics, i.e. design of dynamic random access memories, etc. One problem in their implementation is that metal oxides are thermodynamically unstable with Si and an interfacial layer is formed between the oxide film and the silicon substrate during the deposition process. Herein, the center of attention is on the optical properties of that interfacial layer, which is studied by spectral photometric measurements. The evaluation of the optical parameters of the structure is fulfilled with the genetic algorithm approach. The spectral range of evaluation covers deep UV to NIR. The equivalent physical thickness (2.5 nm) and the equivalent refractive index of the interfacial layer are estimated from 236 to 750 nm as well as the thickness of the tantalum pentoxide film (9.5 nm). (paper)

  20. Electrochemical lithium and sodium intercalation into the tantalum-rich layered chalcogenides Ta2Se and Ta2Te3

    International Nuclear Information System (INIS)

    Lavela, P.; Tirado, J.L.

    1999-01-01

    Two-layered tantalum chalcogenides are evaluated as alkali metal intercalation hosts in lithium and sodium electrochemical cells. The metal-rich pseudo-two-dimensional solid Ta 2 Se shows a poor intercalation behaviour. Lithium reacts with the selenide by deintercalating selenium from the blocks of Ta-related b.c.c. structure leading to a collapse of the structure and the formation of tantalum metal. Sodium is reversibly intercalated to a limited extent leading to complex structural changes in the selenide, as revealed by electron diffraction. The two-dimensional telluride Ta 2 Te 3 allows a topotactic intercalation of lithium below 1 F/mol, while a more extended reaction leads to sample amorphization. The better intercalation behaviour of this solid can be related with the one-atom thick metal layer and the van der Waals gap separating tellurium atoms of successive layers. Sodium can be reversibly intercalated into Ta 2 Te 3 in sodium cells which show a good cycling behaviour. Exposure of the intercalated solid to water vapour allows the preparation of hydrated products with a monolayer or a bilayer of water molecules solvating sodium in the interlayer space. (orig.)