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Sample records for molybdenum 99

  1. Method of producing molybdenum-99

    SciTech Connect

    Pitcher, Eric John

    2013-05-28

    Method of producing molybdenum-99, comprising accelerating ions by means of an accelerator; directing the ions onto a metal target so as to generate neutrons having an energy of greater than 10 MeV; directing the neutrons through a converter material comprising techentium-99 to produce a mixture comprising molybdenum-99; and, chemically extracting the molybdenum-99 from the mixture.

  2. Molybdenum-99/technetium-99m management: race against time.

    PubMed

    Ahmad, Mushtaq

    2011-11-01

    Molybdenum-99 is a parent of diagnostic nuclear medicine. It decays to technetium-99m, which used in over 30 million investigations per year around the world. Supplies of Tc-99m remained fragile in the last few years, which may occur again in the short and long term. Few suggestions have been registered in this letter to cope inadequate supply of the most wanted radionuclide for patient care.

  3. Future of low specific activity molybdenum-99/technetium-99m generator.

    PubMed

    Mushtaq, A

    2012-10-01

    In last few years, the shortage of molybdenum-99 (99Mo) was felt in the developed and developing countries hospitals, where diagnostic nuclear medicine is practiced. To overcome the shortage of 99Mo various routes of its production by accelerators and reactors generating low and high specific activity products have been planned. High specific activity 99Mo obtained by fission of uranium-235 (235U) has completely dominated in the manufacturing of technetium-99m (99mTc) generators in last 3-4 decades, but due to proliferation and dirty bomb, issues non fission routes of 99Mo production are emphasized. Future of low specific activity 99Mo is discussed.

  4. Production of Molybdenum-99 using Neutron Capture Methods

    SciTech Connect

    Toth, James J; Greenwood, Lawrence R; Soderquist, Chuck Z; Wittman, Richard S; Pierson, Bruce D; Burns, Kimberly A; Lavender, Curt A; Painter, Chad L; Love, Edward F; Wall, Donald E

    2011-01-01

    Pacific Northwest National Laboratory (PNNL), operated by Battelle, has identified a reference process for the production of molybdenum-99 (99Mo) for use in a chromatographic generator to separate the daughter product, technetium-99m (99mTc). The reference process uses the neutron capture reaction of natural or enriched molybdenum oxide via the reaction 98Mo(n,γ)99Mo. The irradiated molybdenum is dissolved in an alkaline solution, whereby the molybdenum, dissolved as the molybdate anion, is loaded on a proprietary ion exchange material in the chromatographic generator. The approach of this investigation is to provide a systematic collection of technologies to make the neutron capture method for Mo-99 production economically viable. This approach would result in the development of a technetium Tc99m generator and a new type of target. The target is comprised of molybdenum, either natural or enriched, and is tailored to the design of currently operating U.S. research reactors. The systematic collection of technologies requires evaluation of new metallurgical methods to produce the target, evaluation of target geometries tailored to research reactors, and chemical methods to dissolve the irradiated target materials for use in a chromatographic generator. A Technical specification for testing the target and neutron capture method in a research reactor is also required. This report includes identification of research and demonstration activities needed to enable deployment of neutron capture production method, including irradiations of prototypic targets, chemical processing of irradiated targets, and loading and extraction tests of Mo99 and Tc99m on the sorbent material in a prototypic generator design. The prototypical generator design is based on the proprietary method and systems for isotope product generation. The proprietary methods and systems described in this report are clearly delineated with footnotes. Ultimately, the Tc-99m generator solution provided by

  5. 10 CFR 35.2204 - Records of molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Records of molybdenum-99, strontium-82, and strontium-85... Records § 35.2204 Records of molybdenum-99, strontium-82, and strontium-85 concentrations. A licensee shall maintain a record of the molybdenum-99 concentration or strontium-82 and...

  6. 10 CFR 35.2204 - Records of molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Records of molybdenum-99, strontium-82, and strontium-85... Records § 35.2204 Records of molybdenum-99, strontium-82, and strontium-85 concentrations. A licensee shall maintain a record of the molybdenum-99 concentration or strontium-82 and...

  7. 10 CFR 35.2204 - Records of molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Records of molybdenum-99, strontium-82, and strontium-85... Records § 35.2204 Records of molybdenum-99, strontium-82, and strontium-85 concentrations. A licensee shall maintain a record of the molybdenum-99 concentration or strontium-82 and...

  8. 10 CFR 35.2204 - Records of molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Records of molybdenum-99, strontium-82, and strontium-85... Records § 35.2204 Records of molybdenum-99, strontium-82, and strontium-85 concentrations. A licensee shall maintain a record of the molybdenum-99 concentration or strontium-82 and...

  9. 10 CFR 35.2204 - Records of molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Records of molybdenum-99, strontium-82, and strontium-85... Records § 35.2204 Records of molybdenum-99, strontium-82, and strontium-85 concentrations. A licensee shall maintain a record of the molybdenum-99 concentration or strontium-82 and...

  10. Measurement of Actinides in Molybdenum-99 Solution Analytical Procedure

    SciTech Connect

    Soderquist, Chuck Z.; Weaver, Jamie L.

    2015-11-01

    This document is a companion report to a previous report, PNNL 24519, Measurement of Actinides in Molybdenum-99 Solution, A Brief Review of the Literature, August 2015. In this companion report, we report a fast, accurate, newly developed analytical method for measurement of trace alpha-emitting actinide elements in commercial high-activity molybdenum-99 solution. Molybdenum-99 is widely used to produce 99mTc for medical imaging. Because it is used as a radiopharmaceutical, its purity must be proven to be extremely high, particularly for the alpha emitting actinides. The sample of 99Mo solution is measured into a vessel (such as a polyethylene centrifuge tube) and acidified with dilute nitric acid. A gadolinium carrier is added (50 µg). Tracers and spikes are added as necessary. Then the solution is made strongly basic with ammonium hydroxide, which causes the gadolinium carrier to precipitate as hydrous Gd(OH)3. The precipitate of Gd(OH)3 carries all of the actinide elements. The suspension of gadolinium hydroxide is then passed through a membrane filter to make a counting mount suitable for direct alpha spectrometry. The high-activity 99Mo and 99mTc pass through the membrane filter and are separated from the alpha emitters. The gadolinium hydroxide, carrying any trace actinide elements that might be present in the sample, forms a thin, uniform cake on the surface of the membrane filter. The filter cake is first washed with dilute ammonium hydroxide to push the last traces of molybdate through, then with water. The filter is then mounted on a stainless steel counting disk. Finally, the alpha emitting actinide elements are measured by alpha spectrometry.

  11. Electron accelerator-based production of molybdenum-99: Bremsstrahlung and photoneutron generation from molybdenum vs. tungsten

    NASA Astrophysics Data System (ADS)

    Tsechanski, A.; Bielajew, A. F.; Archambault, J. P.; Mainegra-Hing, E.

    2016-01-01

    A new "one-stage" approach for production of 99Mo and other radioisotopes by means of an electron linear accelerator is described. It is based on using a molybdenum target both as a bremsstrahlung converter and as a radioisotope producing target for the production of 99Mo via the photoneutron reaction 100Mo(γ,n)99Mo. Bremsstrahlung characteristics, such as bremsstrahlung efficiency, angular distribution, and energy deposition for molybdenum targets were obtained by means of the EGSnrc Monte Carlo simulation code system. As a result of our simulations, it is concluded that a 60 MeV electron beam incident on a thick Mo target will have greater bremsstrahlung efficiency than the same thickness (in units of r0) W target, for target thickness z > 1.84r0, where r0 is the electron range. A 50 MeV electron beam incident on a Mo target will result in greater bremsstrahlung efficiency than the same thickness W target (in units of r0) for target thickness case: z ⩾ 2.0r0. It is shown for the one-stage approach with thicknesses of (1.84-2.0)r0, that the 99Mo-production bremsstrahlung efficiency of a molybdenum target is greater by ∼100% at 30 MeV and by ∼70% at 60 MeV compared to the values for tungsten of the same thickness (in units of the appropriate r0) in the traditional two-stage approach (W converter and separate 99Mo producing target). This advantage of the one-stage approach arises from the fact that the bremsstrahlung produced is attenuated only once from attenuation in the molybdenum converter/target. In the traditional, two-stage approach, the bremsstrahlung generated in the W-converter/target is attenuated both in the converter in the 99Mo-producing molybdenum target. The photoneutron production yield of molybdenum and tantalum (as a substitute for tungsten) target was calculated by means of the MCNP5 transport code. On the basis of these data, the specific activity for the one-stage approach of three enriched 100Mo-targets of a 2 cm diameter and

  12. Challenges of Extracting and Purifying Fission-Produced Molybdenum-99

    SciTech Connect

    Carson, S.D.; McDonald, M.J.; Naranjo, G.E.; Wemple, J.A.

    1998-11-06

    Sandia National Laboratories (SNL) has produced limited quantities of fission-produced molybdenum-99 ~%lo) within industry purity specifications using the Cintichem production process. The chemical extraction and purification of `%lo was petiormed using the Hot Cell Facility (HCF) located at Technical Area-V. To thoroughly understand the production process, two series of tests were designed, the first was a series of cold tests using 20 g samples of depleted or low irradiated uranium dioxide powder and the second series was conducted using irradiated targets. In addition, radiation effects tests were petiormed at the SNL Gamma Irradiation Facility (GIF) on chemicals and hardware used in the processing to evaluate the degradation due to the high radiation field expected during the chemical separation. Unique production hardware, fixtures and tools were developed for remote processing of irradiated targets at the HCF.

  13. Compton Backscattering Concept for the Production of Molybdenum-99

    SciTech Connect

    L. Merminga, G.A. Krafft

    2009-05-01

    The medical isotope Molybdenum-99 is presently used for 80-85% of all nuclear medicine procedures and is produced by irradiating highly enriched uranium U-235 targets in NRU reactors. It was recently proposed that an electron linac be used for the production of 99Mo via photo-fission of a natural uranium target coming from the excitation of the giant dipole resonance around 15 MeV. The photons can be produced using the braking radiation (“bremsstrahlung”) spectrum of an electron beam impinged on a high Z material. In this paper we present an alternate concept for the production of 99Mo which is also based on photo-fission of U-238, but where the ~15 MeV gamma-rays are produced by Compton backscattering of laser photons from relativistic electrons. We assume a laser wavelength of 330 nm, resulting in 485 MeV electron beam energy, and 10 mA of average current. Because the induced energy spread on the electron beam is a few percent, one may recover most of the electron beam energy, which substantially increases the efficiency of the system. The accelerator concept, based on a three-pass recirculation system with energy recovery, is described and efficiency estimates are presented.

  14. 10 CFR 35.204 - Permissible molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Permissible molybdenum-99, strontium-82, and strontium-85... Unsealed Byproduct Material-Written Directive Not Required § 35.204 Permissible molybdenum-99, strontium-82, and strontium-85 concentrations. (a) A licensee may not administer to humans a...

  15. 10 CFR 35.204 - Permissible molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Permissible molybdenum-99, strontium-82, and strontium-85... Unsealed Byproduct Material-Written Directive Not Required § 35.204 Permissible molybdenum-99, strontium-82, and strontium-85 concentrations. (a) A licensee may not administer to humans a...

  16. 10 CFR 35.204 - Permissible molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Permissible molybdenum-99, strontium-82, and strontium-85... Unsealed Byproduct Material-Written Directive Not Required § 35.204 Permissible molybdenum-99, strontium-82, and strontium-85 concentrations. (a) A licensee may not administer to humans a...

  17. 10 CFR 35.204 - Permissible molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Permissible molybdenum-99, strontium-82, and strontium-85... Unsealed Byproduct Material-Written Directive Not Required § 35.204 Permissible molybdenum-99, strontium-82, and strontium-85 concentrations. (a) A licensee may not administer to humans a...

  18. 10 CFR 35.204 - Permissible molybdenum-99, strontium-82, and strontium-85 concentrations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Permissible molybdenum-99, strontium-82, and strontium-85... Unsealed Byproduct Material-Written Directive Not Required § 35.204 Permissible molybdenum-99, strontium-82, and strontium-85 concentrations. (a) A licensee may not administer to humans a...

  19. Estimation of (99)Mo production rates from natural molybdenum in research reactors.

    PubMed

    Blaauw, M; Ridikas, D; Baytelesov, S; Salas, P S Bedregal; Chakrova, Y; Eun-Ha, Cho; Dahalan, R; Fortunato, A H; Jacimovic, R; Kling, A; Muñoz, L; Mohamed, N M A; Párkányi, D; Singh, T; Van Dong Duong

    2017-01-01

    Molybdenum-99 is one of the most important radionuclides for medical diagnostics. In 2015, the International Atomic Energy Agency organized a round-robin exercise where the participants measured and calculated specific saturation activities achievable for the (98)Mo(n,γ)(99)Mo reaction. This reaction is of interest as a means to locally, and on a small scale, produce (99)Mo from natural molybdenum. The current paper summarises a set of experimental results and reviews the methodology for calculating the corresponding saturation activities. Activation by epithermal neutrons and also epithermal neutron self-shielding are found to be of high importance in this case.

  20. Production of {sup 99}Mo using LEU and molybdenum targets in a 1 MW Triga reactor

    SciTech Connect

    Mo, S.C.

    1993-12-31

    The production of {sup 99}Mo using Low Enriched Uranium (LEU) and natural molybdenum targets in a 1 MW Triga reactor is investigated. The successive linear programming technique is applied to minimize the target loadings for different yield constraints. The irradiation time is related to the kinetics of the growth and decay of {sup 99}Mo. The feasibility of a neutron generated based {sup 99}Mo production system is discussed.

  1. A strategy for intensive production of molybdenum-99 isotopes for nuclear medicine using CANDU reactors.

    PubMed

    Morreale, A C; Novog, D R; Luxat, J C

    2012-01-01

    Technetium-99m is an important medical isotope utilized worldwide in nuclear medicine and is produced from the decay of its parent isotope, molybdenum-99. The online fueling capability and compact fuel of the CANDU(®)(1) reactor allows for the potential production of large quantities of (99)Mo. This paper proposes (99)Mo production strategies using modified target fuel bundles loaded into CANDU fuel channels. Using a small group of channels a yield of 89-113% of the weekly world demand for (99)Mo can be obtained.

  2. Molybdenum-99 Isotope Production Preparation at Sandia National Laboratories

    SciTech Connect

    Carson, S.D.; Longley, S.W.; McDonald, M.J.; Parma, E.J.; Vernon, M.E.

    1998-10-07

    `Q&c M. J. McDonald, S. D. Carson, S. W. Longley, E. J. Parma, M. E. Vern `~ I@ .,., Sandia National Laboratories*, P. .0. Box 5800, Albuquerque, NM, 8 W? 1$ tl?;:q `f. (3 . 8 /'~ Abstract This report was prepared as an account of work sponsored byanagency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. loading on the Cintichem targets. These tests were designed to gain process knowledge prior to processing an irradiated target. The chemical separation tests were performed in a fime hood During cold testing, several tests were performed on individual components of the process to complete, a series of `hot' tests was designed to process irradiated targets. These were designed to optimize the process, identify problems prior to processing higher inventory targets, and to the shielded containment box (SCB). Table 1 is a summary of the tests performed prior to the Test Target Power Post irradiation Total inventory 99M0 inventory (kW)/ Irradiation decay (hrs) (TBq*) /decay (TBq)/decay Time (hrs) inventory (TBq) inventory(TBq) in the processing boxes as color comparisons. Product quality control testing was conducted for all the tests and the results were compared to The production process generates a high activity acidic liquid

  3. A 3D Computational fluid dynamics model validation for candidate molybdenum-99 target geometry

    NASA Astrophysics Data System (ADS)

    Zheng, Lin; Dale, Greg; Vorobieff, Peter

    2014-11-01

    Molybdenum-99 (99Mo) is the parent product of technetium-99m (99mTc), a radioisotope used in approximately 50,000 medical diagnostic tests per day in the U.S. The primary uses of this product include detection of heart disease, cancer, study of organ structure and function, and other applications. The US Department of Energy seeks new methods for generating 99Mo without the use of highly enriched uranium, to eliminate proliferation issues and provide a domestic supply of 99mTc for medical imaging. For this project, electron accelerating technology is used by sending an electron beam through a series of 100Mo targets. During this process a large amount of heat is created, which directly affects the operating temperature dictated by the tensile stress limit of the wall material. To maintain the required temperature range, helium gas is used as a cooling agent that flows through narrow channels between the target disks. In our numerical study, we investigate the cooling performance on a series of new geometry designs of the cooling channel. This research is supported by Los Alamos National Laboratory.

  4. Molybdenum target specifications for cyclotron production of 99mTc based on patient dose estimates

    NASA Astrophysics Data System (ADS)

    Hou, X.; Tanguay, J.; Buckley, K.; Schaffer, P.; Bénard, F.; Ruth, T. J.; Celler, A.

    2016-01-01

    In response to the recognized fragility of reactor-produced 99Mo supply, direct production of 99mTc via 100Mo(p,2n)99mTc reaction using medical cyclotrons has been investigated. However, due to the existence of other Molybdenum (Mo) isotopes in the target, in parallel with 99mTc, other technetium (Tc) radioactive isotopes (impurities) will be produced. They will be incorporated into the labeled radiopharmaceuticals and result in increased patient dose. The isotopic composition of the target and beam energy are main factors that determine production of impurities, thus also dose increases. Therefore, they both must be considered when selecting targets for clinical 99mTc production. Although for any given Mo target, the patient dose can be predicted based on complicated calculations of production yields for each Tc radioisotope, it would be very difficult to reverse these calculations to specify target composition based on dosimetry considerations. In this article, a relationship between patient dosimetry and Mo target composition is studied. A simple and easy algorithm for dose estimation, based solely on the knowledge of target composition and beam energy, is described. Using this algorithm, the patient dose increase due to every Mo isotope that could be present in the target is estimated. Most importantly, a technique to determine Mo target composition thresholds that would meet any given dosimetry requirement is proposed.

  5. Experiment on the treatment of waste extraction solvent from the molybdenum-99 process

    SciTech Connect

    Hsien-Ming Hsiao; Chang-Liang Hu; Kuang-Li Chien; Wen-Cheng Lee; Tsong-Yang Wei

    2013-07-01

    In the Mo-99 (Molybdenum-99) isotope extraction test process for radiopharmaceutical applications, organic solvent is used to extract Mo-99 from an irradiated UO{sub 2} dissolution. The extraction solvent was stored when the test work was stopped. A total of about 120 liters of waste solvent was stored at INER (Institute of Nuclear Energy Research, Taiwan). The extraction solvent consisted of 5% di-(2-ethylhexyl)-phosphoric acid (D2EHPA) and kerosene. The radionuclides found in the waste solvent include Cs-137, Am-241, Tc-99, and Sr-90, which give off gross alpha and beta radioactivity of 1898 and 471 Bq/ml, respectively. This study aims to remove radionuclides from the waste solvent using sodium carbonate and sodium hydroxide solutions in different concentrations. After mixing the waste solvent with the alkaline solution followed by settling, a third phase other than organic and aqueous phase appeared which is expected due to the saponification reaction. The experimental results showed that increasing the number of washing and the alkaline solution concentration could enhance the radionuclides removal rate. An optimal removal method was proposed using 2 M Na{sub 2}CO{sub 3} solution twice followed by 1 M NaOH solution one time for the third phase generated early in the mixing stages. The remaining gross alpha and beta radioactivity of the treated organic solvent was 2 and 3 Bq/ml, respectively. The treated solvent could be stabilized by ashing at 500 deg. C and then immobilized. The alkaline solution would be neutralized by hydrochloric or nitric acid and then treated using a variety of adsorbents or bone char via adsorption to remove nuclides to meet the wastewater discharge limitation. (authors)

  6. Molybdenum

    Integrated Risk Information System (IRIS)

    Molybdenum ; CASRN 7439 - 98 - 7 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effec

  7. A Nuclear Reactor and Chemical Processing Design for Production of Molybdenum-99 with Crystalline Uranyl Nitrate Hexahydrate Fuel

    NASA Astrophysics Data System (ADS)

    Stange, Gary Michael

    Medical radioisotopes are used in tens of millions of procedures every year to detect and image a wide variety of maladies and conditions in the human body. The most widely-used diagnostic radioisotope is technetium-99m, a metastable isomer of technetium-99 that is generated by the radioactive decay of molybdenum-99. For a number of reasons, the supply of molybdenum-99 has become unreliable and the techniques used to produce it have become unattractive. This has spurred the investigation of new technologies that avoid the use of highly enriched uranium to produce molybdenum-99 in the United States, where approximately half of the demand originates. The first goal of this research is to develop a critical nuclear reactor design powered by solid, discrete pins of low enriched uranium. Analyses of single-pin heat transfer and whole-core neutronics are performed to determine the required specifications. Molybdenum-99 is produced directly in the fuel of this reactor and then extracted through a series of chemical processing steps. After this extraction, the fuel is left in an aqueous state. The second goal of this research is to describe a process by which the uranium may be recovered from this spent fuel solution and reconstituted into the original fuel form. Fuel recovery is achieved through a crystallization step that generates solid uranyl nitrate hexahydrate while leaving the majority of fission products and transuranic isotopes in solution. This report provides background information on molybdenum-99 production and crystallization chemistry. The previously unknown thermal conductivity of the fuel material is measured. Following this is a description of the modeling and calculations used to develop a reactor concept. The operational characteristics of the reactor core model are analyzed and reported. Uranyl nitrate crystallization experiments have also been conducted, and the results of this work are presented here. Finally, a process flow scheme for uranium

  8. Production of radionuclide molybdenum 99 in a distributed and in situ fashion

    SciTech Connect

    Gentile, Charles A.; Cohen, Adam B.; Ascione, George

    2016-04-19

    A method and apparatus for producing Mo-99 from Mo-100 for the use of the produced Mo-99 in a Tc-99m generator without the use of uranium is presented. Both the method and apparatus employ high energy gamma rays for the transformation of Mo-100 to Mo-99. The high energy gamma rays are produced by exposing a metal target to a moderated neutron output of between 6 MeV and 14 MeV. The resulting Mo-99 spontaneously decays into Tc-99m and can therefore be used in a Tc-99m generator.

  9. The thermal-mechanical analysis of targets for the high volume production of molybdenum-99 using a low-enriched uranium metal foil

    NASA Astrophysics Data System (ADS)

    Turner, Kyler Kriens

    Molybdenum-99 diagnostic imaging is the most commonly practiced procedure in nuclear medicine today with the majority molybdenum-99 produced with proliferation sensitive HEU. International and domestic efforts to develop non-HEU production techniques have taking the first steps toward establishing a new non-HEU molybdenum-99 based supply chain. The focus of the research presented in this work is on the analysis of a new high U-235 density LEU based molybdenum-99 production target. Converting directly to LEU using current manufacturing techniques greatly reduces the molybdenum-99 yield per target making high volume production uneconomical. The LEU based foil target analyzed in this research increases the yield per target making economic high volume production with LEU possible. The research analyzed the thermal-mechanical response of an LEU foil target during irradiation. Thermal-mechanical studies focused on deflections and stresses to assess the probability of target failure. Simpler analytical models were used to determine the proper shape of the target and to benchmark the numerical modeling software. Numerical studies using Abaqus focused on analyzing various heating and cooling conditions and assessing the effects of curvature on the target. Finally, experiments were performed to simulate low power heating and further benchmark the models. The results from all of these analyses indicate a LEU foil target could survive irradiation depending on the conditions seen during irradiation.

  10. Short- and long-term responses to molybdenum-99 shortages in nuclear medicine.

    PubMed

    Ballinger, J R

    2010-11-01

    Most nuclear medicine studies use (99)Tc(m), which is the decay product of (99)Mo. The world supply of (99)Mo comes from only five nuclear research reactors and availability has been much reduced in recent times owing to problems at the largest reactors. In the short-term there are limited actions that can be taken owing to capacity issues on alternative imaging modalities. In the long-term, stability of (99)Mo supply will rely on a combination of replacing conventional reactors and developing new technologies.

  11. A computerized compact module for separation of (99m)Tc-radionuclide from molybdenum.

    PubMed

    Chattopadhyay, Sankha; Barua, Luna; De, Anirban; Saha Das, Sujata; Kuniyil, Remashan; Bhaskar, Partha; Pal, Sasanka Shekhar; Sarkar, Sishir Kumar; Das, Malay Kanti

    2012-11-01

    An automated closed cycle module for the separation and recovery of various isotopes, radioactive or non-radioactive, using solvent extraction and column chromatography techniques, and in particular, for separation and recovery of (99m)Tc from low-medium specific activity (99)Mo, is described. The module may also be applicable for separation of (99m)Tc produced in a cyclotron. The module is safe and reliable to avoid human interference and hazards posed by handling of radioactive and hazardous chemicals. The entire system of automation includes a user-friendly PC based graphical user interface (GUI) that actually supervises the process via an embedded system based electronic controller.

  12. Target and method for the production of fission product molybdenum-99

    DOEpatents

    Vandegrift, George F.; Vissers, Donald R.; Marshall, Simon L.; Varma, Ravi

    1989-01-01

    A target for the reduction of fission product Mo-99 is prepared from uranium of low U-235 enrichment by coating a structural support member with a preparatory coating of a substantially oxide-free substrate metal. Uranium metal is electrodeposited from a molten halide electrolytic bath onto a substrate metal. The electrodeposition is performed at a predetermined direct current rate or by using pulsed plating techniques which permit relaxation of accumulated uranium ion concentrations within the melt. Layers of as much as to 600 mg/cm.sup.2 of uranium can be prepared to provide a sufficient density to produce acceptable concentrations of fission product Mo-99.

  13. Target and method for the production of fission product molybdenum-99

    DOEpatents

    Vandegrift, G.F.; Vissers, D.R.; Marshall, S.L.; Varma, R.

    1987-10-26

    A target for the reduction of fission product Mo-99 is prepared from uranium of low U-235 enrichment by coating a structural support member with a preparatory coating of a substantially oxide-free substrate metal. Uranium metal is electrodeposited from a molten halide electrolytic bath onto a substrate metal. The electrodeposition is performed at a predetermined direct current rate or by using pulsed plating techniques which permit relaxation of accumulated uranium ion concentrations within the melt. Layers of as much as to 600 mg/cm/sup 2/ of uranium can be prepared to provide a sufficient density to produce acceptable concentrations of fission product Mo-99. 2 figs.

  14. Level 1 transient model for a molybdenum-99 producing aqueous homogeneous reactor and its applicability to the tracy reactor

    SciTech Connect

    Nygaard, E. T.; Williams, M. M. R.; Angelo, P. L.

    2012-07-01

    Babcock and Wilcox Technical Services Group (B and W) has identified aqueous homogeneous reactors (AHRs) as a technology well suited to produce the medical isotope molybdenum 99 (Mo-99). AHRs have never been specifically designed or built for this specialized purpose. However, AHRs have a proven history of being safe research reactors. In fact, in 1958, AHRs had 'a longer history of operation than any other type of research reactor using enriched fuel' and had 'experimentally demonstrated to be among the safest of all various type of research reactor now in use [1].' A 'Level 1' model representing B and W's proposed Medical Isotope Production System (MIPS) reactor has been developed. The Level 1 model couples a series of differential equations representing neutronics, temperature, and voiding. Neutronics are represented by point reactor kinetics while temperature and voiding terms are axially varying (one-dimensional). While this model was developed specifically for the MIPS reactor, its applicability to the Japanese TRACY reactor was assessed. The results from the Level 1 model were in good agreement with TRACY experimental data and found to be conservative over most of the time domains considered. The Level 1 model was used to study the MIPS reactor. An analysis showed the Level 1 model agreed well with a more complex computational model of the MIPS reactor (a FETCH model). Finally, a significant reactivity insertion was simulated with the Level 1 model to study the MIPS reactor's time-dependent response. (authors)

  15. Conversion of Molybdenum-99 production process to low enriched uranium: Neutronic and thermal hydraulic analyses of HEU and LEU target plates for irradiation in Pakistan Research Reactor-1

    NASA Astrophysics Data System (ADS)

    Mushtaq, Ahmad; Iqbal, Masood; Bokhari, Ishtiaq Hussain; Mahmood, Tayyab; Muhammad, Atta

    2012-09-01

    Technetium-99m, the daughter product of Molybdenum-99 is the most widely needed radionuclide for diagnostic studies in Pakistan. Molybdenum-99 Production Facility has been established at PINSTECH. Highly enriched uranium (93% 235U) U/Al alloy targets have been irradiated in Pakistan Research Reactor-1 (PARR-1) for the generation of fission Mo-99, while basic dissolution technique is used for separation of Mo-99 from target matrix activity. In line with the international objective of minimizing and eventually eliminating the use of HEU in civil commerce, national and international efforts have been underway to shift the production of medical isotopes from HEU to LEU (LEU; <20% 235U enrichment) targets. To achieve the equivalent amount of 99Mo with LEU targets, approximately 5 times uranium is needed. LEU aluminum uranium dispersion target has been developed, which may replace existing HEU aluminum/uranium alloy targets for production of 99Mo using basic dissolution technique. Neutronic and thermal hydraulic calculations were performed for safe irradiation of targets in the core of PARR-1.

  16. Assessment of candidates for target window material in accelerator-driven molybdenum-99 production

    SciTech Connect

    Strons, Philip; Bailey, James; Makarashvili, Vakhtang; Chemerisov, Sergey; Gromov, Roman; Vandegrift, George

    2016-10-01

    NorthStar Medical Technologies is pursuing production of an important medical isotope, Mo-99, through a photo-nuclear reaction of a Mo-100 target using a high-power electron accelerator. The current target utilizes an Inconel 718 window. The purpose of this study was to evaluate other candidate materials for the target window, which separates the high-pressure helium gas inside the target from the vacuum inside the accelerator beamline and is subjected to significant stress. Our initial analysis assessed the properties (density, thermal conductivity, maximum stress, minimum window thickness, maximum temperature, and figure of merit) for a range of materials, from which the three most promising were chosen: Inconel 718, 250 maraging steel, and standard-grade beryllium. These materials were subjected to further analysis to determine the effects of thermal and mechanical strain versus beam power at varying thicknesses. Both beryllium and the maraging steel were calculated to withstand more than twice as high beam power than Inconel 718.

  17. Application of computational models to estimate organ radiation dose in rainbow trout from uptake of molybdenum-99 with comparison to iodine-131.

    PubMed

    Martinez, N E; Johnson, T E; Pinder, J E

    2016-01-01

    This study compares three anatomical phantoms for rainbow trout (Oncorhynchus mykiss) for the purpose of estimating organ radiation dose and dose rates from molybdenum-99 ((99)Mo) uptake in the liver and GI tract. Model comparison and refinement is important to the process of determining accurate doses and dose rates to the whole body and the various organs. Accurate and consistent dosimetry is crucial to the determination of appropriate dose-effect relationships for use in environmental risk assessment. The computational phantoms considered are (1) a geometrically defined model employing anatomically relevant organ size and location, (2) voxel reconstruction of internal anatomy obtained from CT imaging, and (3) a new model utilizing NURBS surfaces to refine the model in (2). Dose Conversion Factors (DCFs) for whole body as well as selected organs of O. mykiss were computed using Monte Carlo modeling and combined with empirical models for predicting activity concentration to estimate dose rates and ultimately determine cumulative radiation dose (μGy) to selected organs after several half-lives of (99)Mo. The computational models provided similar results, especially for organs that were both the source and target of radiation (less than 30% difference between all models). Values in the empirical model as well as the 14 day cumulative organ doses determined from (99)Mo uptake are compared to similar models developed previously for (131)I. Finally, consideration is given to treating the GI tract as a solid organ compared to partitioning it into gut contents and GI wall, which resulted in an order of magnitude difference in estimated dose for most organs.

  18. Potential impact of releases from a new Molybdenum-99 production facility on regional measurements of airborne xenon isotopes

    SciTech Connect

    Bowyer, Ted W.; Eslinger, Paul W.; Cameron, Ian M.; Friese, Judah I.; Hayes, James C.; Metz, Lori A.; Miley, Harry S.

    2014-03-01

    The monitoring of the radioactive xenon isotopes 131mXe, 133Xe, 133mXe, and 135Xe is important for the detection of nuclear explosions. While backgrounds of the xenon isotopes are short-lived, they are constantly replenished from activities dominated by the fission-based production of 99Mo used for medical procedures. One of the most critical locations on earth for the monitoring of nuclear explosions is the Korean peninsula, where the Democratic Republic of North Korea (DPRK) has announced that it had conducted three nuclear tests between 2009 and 2013. This paper explores the backgrounds that would be caused by the medium to large scale production of 99Mo in the region of the Korean peninsula.

  19. Molybdenum, molybdenum oxides, and their electrochemistry.

    PubMed

    Saji, Viswanathan S; Lee, Chi-Woo

    2012-07-01

    The electrochemical behaviors of molybdenum and its oxides, both in bulk and thin film dimensions, are critical because of their widespread applications in steels, electrocatalysts, electrochromic materials, batteries, sensors, and solar cells. An important area of current interest is electrodeposited CIGS-based solar cells where a molybdenum/glass electrode forms the back contact. Surprisingly, the basic electrochemistry of molybdenum and its oxides has not been reviewed with due attention. In this Review, we assess the scattered information. The potential and pH dependent active, passive, and transpassive behaviors of molybdenum in aqueous media are explained. The major surface oxide species observed, reversible redox transitions of the surface oxides, pseudocapacitance and catalytic reduction are discussed along with carefully conducted experimental results on a typical molybdenum glass back contact employed in CIGS-based solar cells. The applications of molybdenum oxides and the electrodeposition of molybdenum are briefly reviewed.

  20. Breaking America's dependence on imported molybdenum.

    PubMed

    Einstein, Andrew J

    2009-03-01

    Approximately 9 million nuclear cardiology studies performed each year in the U.S. use technetium-99m, which is produced from the decay of molybdenum-99. The fragility of the worldwide technetium-99m supply chain has been underscored by current shortages caused by an unplanned shutdown of Europe's largest reactor. The majority of the U.S. supply derives from a reactor in Canada that is nearing the end of its lifespan and whose planned replacements have been cancelled recently. In this article, the clinical importance of technetium-99m and our tenuous dependence on the foreign supply of molybdenum are addressed, along with potential measures that may be taken to ensure that America's supply chain remains unbroken.

  1. The molybdenum cofactor.

    PubMed

    Mendel, Ralf R

    2013-05-10

    The transition element molybdenum needs to be complexed by a special cofactor to gain catalytic activity. Molybdenum is bound to a unique pterin, thus forming the molybdenum cofactor (Moco), which, in different variants, is the active compound at the catalytic site of all molybdenum-containing enzymes in nature, except bacterial molybdenum nitrogenase. The biosynthesis of Moco involves the complex interaction of six proteins and is a process of four steps, which also require iron, ATP, and copper. After its synthesis, Moco is distributed, involving Moco-binding proteins. A deficiency in the biosynthesis of Moco has lethal consequences for the respective organisms.

  2. Breaking America’s Dependence on Foreign…Molybdenum

    PubMed Central

    Einstein, Andrew J.

    2009-01-01

    Brief Unstructured Abstract Approximately 9 million nuclear cardiology studies performed each year in the United States employ technetium-99m, which is produced from the decay of molybdenum-99. The fragility of the worldwide technetium-99m supply chain has been underscored by current shortages caused by an unplanned shutdown of Europe’s largest reactor. The majority of the United States’ supply derives from a reactor in Canada nearing the end of its lifespan, whose planned replacements have been recently cancelled. In this article, the clinical importance of technetium-99m and our tenuous dependence on foreign supply of Molybdenum is addressed. PMID:19356583

  3. Molybdenum disilicide composites

    DOEpatents

    Rodriguez, Robert P.; Petrovic, John J.

    2001-01-01

    Molybdenum disilicide/.beta.'-Si.sub.6-z Al.sub.z O.sub.z N.sub.8-z, wherein z=a number from greater than 0 to about 5, composites are made by use of in situ reactions among .alpha.-silicon nitride, molybdenum disilicide, and aluminum. Molybdenum disilicide within a molybdenum disilicide/.beta.'-Si.sub.6-z Al.sub.z O.sub.z N.sub.8-z eutectoid matrix is the resulting microstructure when the invention method is employed.

  4. Molybdenum nutriture in humans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Molybdenum is a trace element that functions as a cofactor for at least four enzymes: sulfite oxidase, xanthine oxidase, aldehyde oxidase, and mitochondrial amidoxime reducing component. In each case, molybdenum is bound to a complex, multi-ring organic component called molybdopterin, forming the e...

  5. Molybdenum disilicide matrix composite

    DOEpatents

    Petrovic, John J.; Carter, David H.; Gac, Frank D.

    1990-01-01

    A composition consisting of an intermetallic compound, molybdenum disilicide, which is reinforced with VS silicon carbide whiskers dispersed throughout it and a method of making the reinforced composition. Use of the reinforcing material increases fracture toughness at low temperatures and strength at high temperatures, as compared to pure molybdenum disilicide.

  6. Molybdenum disilicide matrix composite

    DOEpatents

    Petrovic, John J.; Carter, David H.; Gac, Frank D.

    1991-01-01

    A composition consisting of an intermetallic compound, molybdenum disilicide, which is reinforced with VS silicon carbide whiskers dispersed throughout it and a method of making the reinforced composition. Use of the reinforcing material increases fracture toughness at low temperatures and strength at high temperatures, as compared to pure molybdenum disilicide.

  7. Organometallic Chemistry of Molybdenum.

    ERIC Educational Resources Information Center

    Lucas, C. Robert; Walsh, Kelly A.

    1987-01-01

    Suggests ways to avoid some of the problems students have learning the principles of organometallic chemistry. Provides a description of an experiment used in a third-year college chemistry laboratory on molybdenum. (TW)

  8. Biomonitoring Equivalents for molybdenum.

    PubMed

    Hays, Sean M; Macey, Kristin; Poddalgoda, Devika; Lu, Ming; Nong, Andy; Aylward, Lesa L

    2016-06-01

    Molybdenum is an essential trace element for mammalian, plant, and other animal systems. The Institute of Medicine (IOM) has established an Estimated Average Requirement (EAR) to assure sufficient molybdenum intakes for human populations; however excessive exposures can cause toxicity. As a result, several agencies have established exposure guidance values to protect against molybdenum toxicity, including a Reference Dose (RfD), Tolerable Daily Intake (TDI) and a Tolerable Upper Intake Level (UL). Biomonitoring for molybdenum in blood or urine in the general population is being conducted by the Canadian Health Measures Survey (CHMS) and the U.S. National Health and Nutrition Examination Survey (NHANES). Using pharmacokinetic data from controlled human dosing studies, Biomonitoring Equivalents (BEs) were calculated for molybdenum in plasma, whole blood, and urine associated with exposure guidance values set to protect against both nutritional deficits and toxicity. The BEEAR values in plasma, whole blood and urine are 0.5, 0.45 and 22 μg/L, respectively. The BEs associated with toxicity range from 0.9 to 31 μg/L in plasma, 0.8-28 μg/L in whole blood and 200-7500 μg/L in urine. These values can be used to interpret molybdenum biomonitoring data from a nutritional and toxicity perspective.

  9. Incorporation of molybdenum in rubredoxin: models for mononuclear molybdenum enzymes.

    PubMed

    Maiti, Biplab K; Maia, Luisa B; Silveira, Célia M; Todorovic, Smilja; Carreira, Cintia; Carepo, Marta S P; Grazina, Raquel; Moura, Isabel; Pauleta, Sofia R; Moura, José J G

    2015-07-01

    Molybdenum is found in the active site of enzymes usually coordinated by one or two pyranopterin molecules. Here, we mimic an enzyme with a mononuclear molybdenum-bis pyranopterin center by incorporating molybdenum in rubredoxin. In the molybdenum-substituted rubredoxin, the metal ion is coordinated by four sulfurs from conserved cysteine residues of the apo-rubredoxin and two other exogenous ligands, oxygen and thiol, forming a Mo((VI))-(S-Cys)4(O)(X) complex, where X represents -OH or -SR. The rubredoxin molybdenum center is stabilized in a Mo(VI) oxidation state, but can be reduced to Mo(IV) via Mo(V) by dithionite, being a suitable model for the spectroscopic properties of resting and reduced forms of molybdenum-bis pyranopterin-containing enzymes. Preliminary experiments indicate that the molybdenum site built in rubredoxin can promote oxo transfer reactions, as exemplified with the oxidation of arsenite to arsenate.

  10. Radiation Chemistry of Simulated (99)Mo Product

    SciTech Connect

    Carson, S.D.; Garcia, M.J.; McDonald, M.J.; Simpson, R.L.; Tallant, D.R.

    1998-11-06

    PharrnaceuticaI houses that produce {sup 99}Tc/{sup 99}Tc generators have on occasion received {sup 99}Mo that contained a black precipitate. Addition of sodium hypochlorite to product bottles prior to shipment prevents precipitate formation, indicating the precipitate is a reduced form of Mo. The radiation effects of the dose from {sup 99}Mo on the product and product bottle have been determined by irradiating simulated {sup 99}Mo product solutions with the {sup 60}Co source at Sandia National Laboratories' Gamma Irradiation Facility (GE). The GIF experiment successfully generated a black precipitate in amounts sufficient for isolation and analysis by infrared and Rrunan spectroscopy. Changes in the pH of the basic {sup 99}Mo product solution during irradiation were monitored by titration. ResuIts of these analyses and the nature of the process that generates the precipitate, a mixture of molybdenum oxides that forms in plastic bottles, but not in glass containers, are discussed.

  11. Mineral resource of the month: molybdenum

    USGS Publications Warehouse

    Polyak, Désire E.

    2011-01-01

    The article offers information about the mineral molybdenum. Sources includes byproduct or coproduct copper-molybdenum deposits in the Western Cordillera of North and South America. Among the uses of molybdenum are stainless steel applications, as an alloy material for manufacturing vessels and as lubricants, pigments or chemicals. Also noted is the role played by molybdenum in renewable energy technology.

  12. 99Mo/(99m)Tc separation: an assessment of technology options.

    PubMed

    Dash, Ashutosh; Knapp, F F Russ; Pillai, M R A

    2013-02-01

    Several strategies for the effective separation of (99m)Tc from (99)Mo have been developed and validated. Due to the success of column chromatographic separation using acidic alumina coupled with high specific activity fission (99)Mo (F (99)Mo) for production of (99)Mo/(99m)Tc generators, however, most technologies until recently have generated little interest. The reduced availability of F (99)Mo and consequently the shortage of (99)Mo/(99m)Tc column generators in the recent past have resurrected interest in the production of (99)Mo as well as (99m)Tc by alternate routes. Most of these alternative production processes require separation techniques capable of providing clinical grade (99m)Tc from low specific activity (99)Mo or irradiated Mo targets. For this reason there has been renewed interest in alternate separation routes. This paper reviews the reported separation technologies which include column chromatography, solvent extraction, sublimation and gel systems that have been traditionally used for the fabrication of (99)Mo/(99m)Tc generator systems. The comparative advantage, disadvantage, and technical challenges toward adapting the emerging requirements are discussed. New developments such as solid-phase column extraction, electrochemical separation, extraction chromatography, supported liquid membrane (SLM) and thermochromatographic techniques are also being evaluated for their potential application in the changed scenario of providing (99m)Tc from alternate routes. Based on the analysis provided in this review, it appears that some proven separation technologies can be quickly resurrected for the separation of clinical grade (99m)Tc from macroscopic levels of reactor or cyclotron irradiated molybdenum targets. Furthermore, emerging technologies can be developed further to respond to the expected changing modes of (99m)Tc production.

  13. Photo-production of (99)Mo/(99m)Tc with electron linear accelerator beam.

    PubMed

    Avagyan, R; Avetisyan, A; Kerobyan, I; Dallakyan, R

    2014-09-01

    We report on the development of a relatively new method for the production of (99)Mo/(99m)Tc. The method involves the irradiation of natural molybdenum using high-intensity bremsstrahlung photons from the electron beam of the LUE50 linear electron accelerator located at the Yerevan Physics Institute (YerPhi). The production method has been developed and shown to be successful. The linear electron accelerator at YerPhi was upgraded to allow for significant increases of the beam intensity and spatial density. The LUE50 was also instrumented by a remote control system for ease of operation. We have developed and tested the (99m)Tc extraction from the irradiation of natural MoO3. This paper reports on the optimal conditions of our method of (99)Mo production. We show the success of this method with the production and separation of the first usable amounts of (99m)Tc.

  14. Molybdenum enzymes in higher organisms

    PubMed Central

    Hille, Russ; Nishino, Takeshi; Bittner, Florian

    2010-01-01

    Recent progress in our understanding of the structural and catalytic properties of molybdenum-containing enzymes in eukaryotes is reviewed, along with aspects of the biosynthesis of the cofactor and its insertion into apoprotein. PMID:21516203

  15. Sustained Availability of Technetium-99m - Possible Paths Forward

    SciTech Connect

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

    2013-01-01

    The availability of technetium-99m (99mTc) for single-photon imaging in diagnostic nuclear medicine is crucial, and current availability is based on the molybdenum-99 (99Mo)/99mTc generator fabricated from fission-based molybdenum (F 99Mo) produced by use of highly enriched uranium (HEU) targets. The use of HEU targets is being phased out because of risks related to nuclear material proliferation, so alternative strategies for production of both 99Mo and 99mTc are being evaluated intensely. There are evidently no plans for replacement of the limited number of reactors that have primarily provided most of the 99Mo. The uninterrupted, dependable availability of 99mTc is a crucial issue. For these reasons, new options being pursued include both reactor- and accelerator-based strategies to sustain the continued availability of 99mTc without the use of HEU. In this paper the scientific and economic issues for transitioning from HEU to non-HEU are also discussed. In addition, the comparative advantages, disadvantages, technical challenges, present status, future prospects, security concerns, economic viability, and regulatory obstacles are reviewed. In addition, the international actions in progress towards evolving possible alternative strategies to produce 99Mo and/or 99mTc are analyzed. The breadth of technologies and new strategies under development to provide 99Mo and 99mTc reflects both the broad interest in and the importance of the pivotal role of 99mTc in diagnostic nuclear medicine.

  16. Oxide strengthened molybdenum-rhenium alloy

    SciTech Connect

    Bianco, Robert; Buckman, William R. Jr.

    1998-12-01

    Provided is a method of making an ODS molybdenum-rhenium alloy which includes the steps of: (1) forming a slurry containing molybdenum oxide and a metal salt dispersed in an aqueous medium, the metal salt being selected from nitrates or acetates of lanthanum, cerium or thorium; (2) heating the slurry in the presence of hydrogen to form a molybdenum powder comprising molybdenum and an oxide of the metal salt; (3) mixing rhenium powder with the molybdenum powder to form a molybdenum-rhenium powder; (4) pressing the molybdenum-rhenium powder to form a molybdenum-rhenium compact; (5) sintering the molybdenum-rhenium compact in hydrogen or under a vacuum to form a molybdenum-rhenium ingot; and (6) compacting the molybdenum-rhenium ingot to reduce the cross-sectional area of the molybdenum-rhenium ingot and form a molybdenum-rhenium alloy containing said metal oxide. The present invention also provides an ODS molybdenum-rhenium alloy made by the method.

  17. Oxide strengthened molybdenum-rhenium alloy

    DOEpatents

    Bianco, Robert; Buckman, Jr., R. William

    2000-01-01

    Provided is a method of making an ODS molybdenum-rhenium alloy which includes the steps of: (a) forming a slurry containing molybdenum oxide and a metal salt dispersed in an aqueous medium, the metal salt being selected from nitrates or acetates of lanthanum, cerium or thorium; (b) heating the slurry in the presence of hydrogen to form a molybdenum powder comprising molybdenum and an oxide of the metal salt; (c) mixing rhenium powder with the molybdenum powder to form a molybdenum-rhenium powder; (d) pressing the molybdenum-rhenium powder to form a molybdenum-rhenium compact; (e) sintering the molybdenum-rhenium compact in hydrogen or under a vacuum to form a molybdenum-rhenium ingot; and (f) compacting the molybdenum-rhenium ingot to reduce the cross-sectional area of the molybdenum-rhenium ingot and form a molybdenum-rhenium alloy containing said metal oxide. The present invention also provides an ODS molybdenum-rhenium alloy made by the method. A preferred Mo--Re-ODS alloy contains 7-14 weight % rhenium and 2-4 volume % lanthanum oxide.

  18. Superlubricity of molybdenum disulphide

    NASA Astrophysics Data System (ADS)

    Martin, J. M.; Donnet, C.; Le Mogne, Th.; Epicier, Th.

    1993-10-01

    We have studied the atomistic origins of the ultralow friction coefficient of a molybdenum disulphide (MoS2) coating in ultrahigh vacuum conditions. A friction coefficient in the 10-3 range is associated with friction-induced orientation of ``easy shear'' basal planes of the MoS2 crystal structure parallel to the sliding direction. In addition to this basal plane orientation, an orientation disorder around the c axis is observed, indicating that frictional anisotropy during intercrystallite slip could be at the origin of the vanishing of the friction force. Experimental HRTEM lattice fringe imaging of MoS2 wear particles clearly show the existence of characteristic Moiré patterns. We have simulated TEM lattice fringe images of a [0001] MoS2 crystal and produced rotational Moiré patterns by superimposing two such images. A qualitative agreement between experimental and simulated Moiré patterns is demonstrated, which gives credence that ultralow friction of MoS2 in high vacuum can be attributed to a superlubric situation, by frictional anisotropy of sulphur-rich basal planes during intercrystallite slip.

  19. Assessment of Using 99Mo and 99mTc Isotopes in Kuwait Medical Sector

    PubMed Central

    Ali, Naser

    2016-01-01

    Abstract The Ministry of Health (MOH) in the state of Kuwait currently depends on importing the radioisotope molybdenum (Mo) in its isotopic form (99Mo) to fulfill its demands. The present study was conducted on all nuclear medicine departments in the state of Kuwait. Daily, weekly, and monthly data were analyzed to statistically determine the current and future demands for the isotope 99mTc. This analysis was performed by collecting and analyzing data on MOH consumption of 99mTc for different diagnostic applications. The overall results indicate a partial decrease of 1.012% in the overall total demand for 99mTc up to the year 2018 for the state of Kuwait. PMID:26910031

  20. Silicon nitride reinforced with molybdenum disilicide

    DOEpatents

    Petrovic, John J.; Honnell, Richard E.

    1991-01-01

    Compositions of matter comprised of silicon nitride and molybdenum disilicide and methods of making the compositions, where the molybdenum disilicide is present in amounts ranging from about 5 to about 50 vol. %.

  1. Silicon nitride reinforced with molybdenum disilicide

    SciTech Connect

    Petrovic, J.J.; Honnell, R.E.

    1990-12-31

    Compositions of matter comprised of silicon nitride and molybdenum disilicide and methods of making the compositions, where the molybdenum disilicide is present in amounts ranging from about 5 to about 50 vol%.

  2. Nitrogen reduction: Molybdenum does it again

    NASA Astrophysics Data System (ADS)

    Schrock, Richard R.

    2011-02-01

    Nature reduces dinitrogen under mild conditions using nitrogenases, the most active of which contains molybdenum and iron. The only abiological dinitrogen reduction catalyst that avoids the harsh conditions of the Haber-Bosch process contains just molybdenum.

  3. Molybdenum compounds in organic synthesis

    NASA Astrophysics Data System (ADS)

    Khusnutdinov, R. I.; Oshnyakova, T. M.; Dzhemilev, U. M.

    2017-02-01

    The review presents the first analysis and systematic discussion of data published in the last 35–40 years on the use of molybdenum compounds and complexes in organic synthesis and catalysis of various ion coordination and radical reactions. Detailed account is given of the key trends in the use of molybdenum complexes as catalysts of alkene epoxidation and oxyketonation, oxidation of sulfur, nitrogen and phosphorus compounds, hydrosilylation of 1,3-dienes, ketones and aldehydes, hydrostannylation of acetylenes and hydrogermylation of norbornadienes. Considerable attention is paid to the description of new reactions and in situ generation of highly reactive hypohalites, ROX and HOX, induced by molybdenum complexes and the use of hypohalites in oxidative transformations. Data on the application of molybdenum complexes in well-known reactions are discussed, including Kharasch and Pauson–Khand reactions, allylic alkylation of C-nucleophiles, aminocarbonylation of halo derivatives and oligomerization of cyclic dienes, trienes, alkynes and 1,3-dienes. The last Section of the review considers 'unusual' organic reactions involving molybdenum compounds and complexes. The bibliography includes 257 references.

  4. Determination of small amounts of molybdenum in tungsten and molybdenum ores

    USGS Publications Warehouse

    Grimaldi, F.S.; Wells, R.C.

    1943-01-01

    A rapid method has been developed for the determination of small amounts of molybdenum in tungsten and molybdenum ores. After removing iron and other major constituents the molybdenum thiocyanate color is developed in water-acetone solutions, using ammonium citrate to eliminate the interference of tungsten. Comparison is made by titrating a blank with a standard molybdenum solution. Aliquots are adjusted to deal with amounts of molybdenum ranging from 0.01 to 1.30 mg.

  5. Molybdenum sulfide/carbide catalysts

    DOEpatents

    Alonso, Gabriel; Chianelli, Russell R.; Fuentes, Sergio; Torres, Brenda

    2007-05-29

    The present invention provides methods of synthesizing molybdenum disulfide (MoS.sub.2) and carbon-containing molybdenum disulfide (MoS.sub.2-xC.sub.x) catalysts that exhibit improved catalytic activity for hydrotreating reactions involving hydrodesulfurization, hydrodenitrogenation, and hydrogenation. The present invention also concerns the resulting catalysts. Furthermore, the invention concerns the promotion of these catalysts with Co, Ni, Fe, and/or Ru sulfides to create catalysts with greater activity, for hydrotreating reactions, than conventional catalysts such as cobalt molybdate on alumina support.

  6. Molybdenum recycling in the United States in 1998

    USGS Publications Warehouse

    Blossom, John W.

    2002-01-01

    This report describes the flow of molybdenum in the United States in 1998 with emphasis on the extent to which molybdenum was recycled. Molybdenum was mostly recycled from products of molybdenum-bearing steels and superalloys, with some molybdenum products recovered specifically for their high molybdenum content. In 1998, 8,000 metric tons (t) of molybdenum was estimated to have been recycled, and the recycling rate was calculated to be 33 percent, with recycling efficiency at about 30 percent.

  7. SURFACE TREATMENT OF MOLYBDENUM METAL

    DOEpatents

    Coffer, C.O.

    1961-12-01

    A process of descaling molybdenum articles comprises first immersing them in an aqueous sodium hydroxide-potassium permanganate solution of between 60 and 85 deg C, rinsing, and then immersing them in an aqueous solution containing a mixture of sulfuric, hydrochloric, and chromic acids.

  8. Enhanced molybdenum uptake in rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Molybdenum (Mo) is a cofactor for nitrate reductase. When nitrate reductase activity is limited by Mo deficiency, crop yields are also potentially limited. Plant deficiencies in Mo often occur in acidic soil due to mineral fixation. The long-term goal is to identify genes that can be used to develop...

  9. Separation of molybdenum from interfering elements by extraction as phosphomolybdenum blue.

    PubMed

    Yatirajam, V; Ram, J

    1973-09-01

    A simple method is described for the separation of molybdenum from titanium, zirconium, chromium, manganese, iron, cobalt, nickel, uranium and aluminium in a wide variety of samples in <30 min. Phosphomolybdenum blue is produced by boiling for 2 min a molybdate solution containing phosphate to give Mo/P = 20-37 (w/w) with hydrazine sulphate in 0.1N sulphuric acid. The volume and acidity are adjusted to give a molybdenum concentration of 0.6-5 my/ml in 0.4-0.5N sulphuric acid. The phosphomolybdenum blue is 99.5% extracted with methyl isobutyl ketone in a single extraction. The residual molybdenum and hydrazine in the aqueous phase are oxidized with a few drops of liquid bromine and the molybdenum is quantitatively extracted with the same solvent from 1N sulphuric acid as its reddish brown thiosulphato complex. The molybdenum is stripped by ammonia-hydrogen peroxide solution. The back-extract is heated to boiling and filtered to remove the insoluble hydroxides of traces of accompanying elements. The thiosulphate in the filtrate is destroyed by boiling for 4-5 min with excess of hydrogen peroxide in slightly ammoniacal medium. The molybdenum is determined finally by cerimetry or other standard methods.

  10. Radionuclide Basics: Technetium-99

    EPA Pesticide Factsheets

    Technetium-99 (chemical symbol Tc-99) is a silver-gray, radioactive metal. It occurs naturally in very small amounts in the earth's crust, but is primarily man-made. Technetium-99m is a short-lived form of Tc-99 that is used as a medical diagnostic tool.

  11. Mechanical properties of electron-beam-melted molybdenum and dilute molybdenum-rhenium alloys

    NASA Technical Reports Server (NTRS)

    Klopp, W. D.; Witzke, W. R.

    1972-01-01

    A study of molybdenum and three dilute molybdenum-rhenium alloys was undertaken to determine the effects of rhenium on the low temperature ductility and other mechanical properties of molybdenum. Alloys containing 3.9, 5.9, and 7.7 atomic percent rhenium exhibited lower ductile-brittle transition temperatures than did the unalloyed molybdenum. The maximum improvement in the annealed condition was observed for molybdenum - 7.7 rhenium, which had a ductile-brittle transition temperature approximately 200 C (360 F) lower than that for unalloyed molybdenum. Rhenium additions also increased the low and high temperature tensile strengths and the high temperature creep strength of molybdenum. The mechanical behavior of dilute molybdenum-rhenium alloys is similar to that observed for dilute tungsten-rhenium alloys.

  12. Molybdenum disilicide alloy matrix composite

    DOEpatents

    Petrovic, John J.; Honnell, Richard E.; Gibbs, W. Scott

    1990-01-01

    Compositions of matter consisting of matrix matrials having silicon carbide dispersed throughout them and methods of making the compositions. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms.

  13. Molybdenum disilicide alloy matrix composite

    DOEpatents

    Petrovic, John J.; Honnell, Richard E.; Gibbs, W. Scott

    1991-01-01

    Compositions of matter consisting of matrix materials having silicon carbide dispersed throughout them and methods of making the compositions. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms.

  14. Molybdenum disilicide alloy matrix composite

    DOEpatents

    Petrovic, J.J.; Honnell, R.E.; Gibbs, W.S.

    1991-12-03

    Compositions of matter consisting of matrix materials having silicon carbide dispersed throughout them and methods of making the compositions are disclosed. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms. 3 figures.

  15. Zirconia-molybdenum disilicide composites

    DOEpatents

    Petrovic, John J.; Honnell, Richard E.

    1991-01-01

    Compositions of matter comprised of molybdenum disilicide and zirconium oxide in one of three forms: pure, partially stabilized, or fully stabilized and methods of making the compositions. The stabilized zirconia is crystallographically stabilized by mixing it with yttrium oxide, calcium oxide, cerium oxide, or magnesium oxide and it may be partially stabilized or fully stabilized depending on the amount of stabilizing agent in the mixture.

  16. Annealed CVD molybdenum thin film surface

    DOEpatents

    Carver, Gary E.; Seraphin, Bernhard O.

    1984-01-01

    Molybdenum thin films deposited by pyrolytic decomposition of Mo(CO).sub.6 attain, after anneal in a reducing atmosphere at temperatures greater than 700.degree. C., infrared reflectance values greater than reflectance of supersmooth bulk molybdenum. Black molybdenum films deposited under oxidizing conditions and annealed, when covered with an anti-reflecting coating, approach the ideal solar collector characteristic of visible light absorber and infrared energy reflector.

  17. Mineral resource of the month: molybdenum

    USGS Publications Warehouse

    Magyar, Michael J.

    2004-01-01

    Molybdenum is a metallic element that is most frequently used in alloy and stainless steels, which together represent the single largest market for molybdenum. Molybdenum has also proven invaluable in carbon steel, cast iron and superalloys. Its alloying versatility is unmatched because its addition enhances material performance under high-stress conditions in expanded temperature ranges and in highly corrosive environments. The metal is also used in catalysts, other chemicals, lubricants and many other applications.

  18. Selective molybdenum deposition by LPCVD

    SciTech Connect

    Lifshitz, N.; Williams, D.S.; Capio, C.D.; Brown, J.M.

    1987-08-01

    Molybdenum films have been deposited by low pressure chemical vapor deposition (LPCVD) on silicon substrates by the reduction of molybdenum hexafluoride in hydrogen and argon atmospheres. The deposition is extremely selective, with no Mo observed on silicon dioxide surfaces over the temperature range of 200/sup 0/-400/sup 0/C. Reduction by both hydrogen and silicon contribute to the deposition, with approximately equal, extremely high deposition rates; no self-limiting thickness was observed. Extensive TEM and SEM studies were conducted in order to characterize the microstructure of the deposited films. The main feature of the films is their extreme porosity - about 30%, which can explain many unusual properties of the process and the films. On the basis of experiments the authors propose a model to explain the origin of the porosity in the films. Comparative studies of tungsten and molybdenum LPCVD reveal that the difference between the two processes lie in the self-limiting mechanism occurring during the silicon reduction of tungsten hexafluoride.

  19. Study of the radiation effect of 99Mo/99mTc generator on Bacillus subtilis and Bacillus pumilus species.

    PubMed

    Fukumori, Neuza T O; Endo, Erica M M; Felgueiras, Carlos F; Matsuda, Margareth M N; Osso Junior, João A

    2016-01-01

    In this work, molybdenum-99 loaded columns were challenged with Bacillus subtilis vegetative cells and Bacillus pumilus spores inside and outside the alumina column, and microbial recovery and radiation effect were assessed. Alumina was a barrier for the passage of microorganisms regardless the species, whilst spores were more retained than vegetative cells with a lower microbial recovery, without significant differences between 9.25 and 74 GBq generators. Bacillus pumilus biological indicator showed lower recoveries, suggesting a radiation inactivating effect on microorganisms.

  20. A comparison of rat SPECT images obtained using (99m)Tc derived from 99Mo produced by an electron accelerator with that from a reactor.

    PubMed

    Galea, R; Wells, R G; Ross, C K; Lockwood, J; Moore, K; Harvey, J T; Isensee, G H

    2013-05-07

    Recent shortages of molybdenum-99 ((99)Mo) have led to an examination of alternate production methods that could contribute to a more robust supply. An electron accelerator and the photoneutron reaction were used to produce (99)Mo from which technetium-99m ((99m)Tc) is extracted. SPECT images of rat anatomy obtained using the accelerator-produced (99m)Tc with those obtained using (99m)Tc from a commercial generator were compared. Disks of (100)Mo were irradiated with x-rays produced by a 35 MeV electron beam to generate about 1110 MBq (30 mCi) of (99)Mo per disk. After target dissolution, a NorthStar ARSII unit was used to separate the (99m)Tc, which was subsequently used to tag pharmaceuticals suitable for cardiac and bone imaging. SPECT images were acquired for three rats and compared to images for the same three rats obtained using (99m)Tc from a standard reactor (99)Mo generator. The efficiency of (99)Mo-(99m)Tc separation was typically greater than 90%. This study demonstrated the delivery of (99m)Tc from the end of beam to the end user of approximately 30 h. Images obtained using the heart and bone scanning agents using reactor and linac-produced (99m)Tc were comparable. High-power electron accelerators are an attractive option for producing (99)Mo on a national scale.

  1. A comparison of rat SPECT images obtained using 99mTc derived from 99Mo produced by an electron accelerator with that from a reactor

    NASA Astrophysics Data System (ADS)

    Galea, R.; Wells, R. G.; Ross, C. K.; Lockwood, J.; Moore, K.; Harvey, J. T.; Isensee, G. H.

    2013-05-01

    Recent shortages of molybdenum-99 (99Mo) have led to an examination of alternate production methods that could contribute to a more robust supply. An electron accelerator and the photoneutron reaction were used to produce 99Mo from which technetium-99m (99mTc) is extracted. SPECT images of rat anatomy obtained using the accelerator-produced 99mTc with those obtained using 99mTc from a commercial generator were compared. Disks of 100Mo were irradiated with x-rays produced by a 35 MeV electron beam to generate about 1110 MBq (30 mCi) of 99Mo per disk. After target dissolution, a NorthStar ARSII unit was used to separate the 99mTc, which was subsequently used to tag pharmaceuticals suitable for cardiac and bone imaging. SPECT images were acquired for three rats and compared to images for the same three rats obtained using 99mTc from a standard reactor 99Mo generator. The efficiency of 99Mo-99mTc separation was typically greater than 90%. This study demonstrated the delivery of 99mTc from the end of beam to the end user of approximately 30 h. Images obtained using the heart and bone scanning agents using reactor and linac-produced 99mTc were comparable. High-power electron accelerators are an attractive option for producing 99Mo on a national scale.

  2. An Unsaturated Four-Coordinate Dimethyl Dimolybdenum Complex with a Molybdenum-Molybdenum Quadruple Bond.

    PubMed

    Curado, Natalia; Carrasco, Mario; Campos, Jesús; Maya, Celia; Rodríguez, Amor; Ruiz, Eliseo; Álvarez, Santiago; Carmona, Ernesto

    2017-01-01

    We describe the synthesis and the molecular and electronic structures of the complex [Mo2 Me2 {μ-HC(NDipp)2 }2 ] (2; Dipp=2,6-iPr2 C6 H3 ), which contains a dimetallic core with an Mo-Mo quadruple bond and features uncommon four-coordinate geometry and has a fourteen-electron count for each molybdenum atom. The coordination polyhedron approaches a square pyramid, with one of the molybdenum atoms nearly co-planar with the basal square plane, in which the trans coordination position with respect to the Mo-Me bond is vacant. The other three sites are occupied by two trans nitrogen atoms of different amidinate ligands and the methyl group. The second Mo atom occupies the apex of the pyramid and forms an Mo-Mo bond of length 2.080(1) Å, consistent with a quadruple bond. Compound 2 reacts with tetrahydrofuran (THF) and trimethylphosphine to yield the mono-adducts [Mo2 Me(μ-Me){μ-HC(NDipp)2 }2 (L)] (3⋅THF and 3⋅PMe3 , respectively) with one terminal and one bridging methyl group. In contrast, 4-dimethylaminopyridine (dmap) forms the bis-adduct [Mo2 Me2 {μ-HC(NDipp)2 }2 (dmap)2 ] (4), with terminally coordinated methyl groups. Hydrogenolysis of complex 2 leads to the bis(hydride) [Mo2 H2 {μ-HC(NDipp)2 }2 (thf)2 ] (5⋅THF) with elimination of CH4 . Computational, kinetic, and mechanistic studies, which included the use of D2 and of complex 2 labelled with (13) C (99 %) at the Mo-CH3 sites, supported the intermediacy of a methyl-hydride reactive species. A computational DFT analysis of the terminal and bridging coordination of the methyl groups to the Mo≣Mo core is also reported.

  3. Formation of alumina-nickel-molybdenum catalysts

    SciTech Connect

    Erofeev, V.I.; Basov, V.G.; Vagin, A.I.; Kalechits, I.V.

    1982-06-01

    On the basis of the results obtained in physical and chemical studies of alumina-nickel-molybdenum oxide catalysts as well as binary system and the individual oxides, the conclusions show that the commercial catalyst consists mainly of nickel and aluminium molybdates, aluminium molybdates, molybdenum oxide, and the alumina support. 4 figures.

  4. Molybdenum Enzymes, Cofactors, and Model Systems.

    ERIC Educational Resources Information Center

    Burgmayer, S. J. N; Stiefel, E. I.

    1985-01-01

    Discusses: (l) molybdoenzymes (examining their distribution and metabolic role, composition and redox strategy, cofactors, substrate reactions, and mechanistic possibilities); (2) structural information on molybdenum (Mo) centers; (3) modeling studies (Mo-co models, nitrogenase models, and the MO-S duo); and (4) the copper-molybdenum antagonism.…

  5. Molybdenum sealing glass-ceramic composition

    DOEpatents

    Eagan, Robert J.

    1976-01-01

    The invention relates to a glass-ceramic composition having low hydrogen and helium permeability properties, along with high fracture strength, a thermal coefficient of expansion similar to that of molybdenum, and adaptable for hermetically sealing to molybdenum at temperatures of between about 900.degree. and about 950.degree.C. to form a hermatically sealed insulator body.

  6. Production optimization of 99Mo/99mTc zirconium molybate gel generators at semi-automatic device: DISIGEG.

    PubMed

    Monroy-Guzman, F; Rivero Gutiérrez, T; López Malpica, I Z; Hernández Cortes, S; Rojas Nava, P; Vazquez Maldonado, J C; Vazquez, A

    2012-01-01

    DISIGEG is a synthesis installation of zirconium (99)Mo-molybdate gels for (99)Mo/(99m)Tc generator production, which has been designed, built and installed at the ININ. The device consists of a synthesis reactor and five systems controlled via keyboard: (1) raw material access, (2) chemical air stirring, (3) gel dried by air and infrared heating, (4) moisture removal and (5) gel extraction. DISIGEG operation is described and dried condition effects of zirconium (99)Mo- molybdate gels on (99)Mo/(99m)Tc generator performance were evaluated as well as some physical-chemical properties of these gels. The results reveal that temperature, time and air flow applied during the drying process directly affects zirconium (99)Mo-molybdate gel generator performance. All gels prepared have a similar chemical structure probably constituted by three-dimensional network, based on zirconium pentagonal bipyramids and molybdenum octahedral. Basic structural variations cause a change in gel porosity and permeability, favouring or inhibiting (99m)TcO(4)(-) diffusion into the matrix. The (99m)TcO(4)(-) eluates produced by (99)Mo/(99m)Tc zirconium (99)Mo-molybdate gel generators prepared in DISIGEG, air dried at 80°C for 5h and using an air flow of 90mm, satisfied all the Pharmacopoeias regulations: (99m)Tc yield between 70-75%, (99)Mo breakthrough less than 3×10(-3)%, radiochemical purities about 97% sterile and pyrogen-free eluates with a pH of 6.

  7. Measurement of low levels of alpha in {sup 99}Mo product solutions.

    SciTech Connect

    Conner, C.; Liberatore, M. W.; Sedlet, J.; Vandegrift, G. F.

    1998-03-05

    The conclusions of this report are that molybdenum can effectively be separated from uranium and plutonium using TRU-Resin; and that separation of the {sup 99}Mo from the actinides will reduce the analyst's exposure and simplify analysis for the actinide elements.

  8. Effect of Prestraining of Recrystallization Temperature and Mechanical Properties of Commercial, Sintered, Wrought Molybdenum

    NASA Technical Reports Server (NTRS)

    Dike, Kenneth C; Long, Roger A

    1953-01-01

    Given three presumably identical lots of commercial, sintered, wrought molybdenum, the 1-hour recrystallization temperature of one lot remained above 2900 F by limiting the amount of effective restraining to 35 percent or less. Different recrystallization temperatures were obtained in various atmospheres, the highest in argon and the lowest in hydrogen. Metal thus fabricated and then stress-relieved possessed an ultimate tensile strength at room temperature within 10 percent of metal swaged 99 percent and also possessed equivalent ductility. At 1800 F, equivalent strength and ductility was obtained irrespective of the amount of swaging over the range of 10 to 99 percent. The amount of swaging greatly influenced the recrystallized grain size but the difference in grain size is not the major controlling factor which determines whether recrystallized molybdenum is ductile or brittle at room temperature.

  9. Dietary pesticides (99. 99% all natural)

    SciTech Connect

    Ames, B.N.; Profet, M.; Gold, L.S. )

    1990-10-01

    The toxicological significance of exposures to synthetic chemicals is examined in the context of exposures to naturally occurring chemicals. The authors calculate that 99.99{percent} (by weight) of the pesticides in the American diet are chemicals that plants produce to defend themselves. Only 52 natural pesticides have been tested in high-dose animal cancer tests, and about half (27) are rodent carcinogens; these 27 are shown to be present in many common foods. They conclude that natural and synthetic chemicals are equally likely to be positive in animal cancer tests. They also conclude that at the low doses of most human exposures the comparative hazards of synthetic pesticide residues are insignificant.

  10. Dietary pesticides (99.99% all natural).

    PubMed Central

    Ames, B N; Profet, M; Gold, L S

    1990-01-01

    The toxicological significance of exposures to synthetic chemicals is examined in the context of exposures to naturally occurring chemicals. We calculate that 99.99% (by weight) of the pesticides in the American diet are chemicals that plants produce to defend themselves. Only 52 natural pesticides have been tested in high-dose animal cancer tests, and about half (27) are rodent carcinogens; these 27 are shown to be present in many common foods. We conclude that natural and synthetic chemicals are equally likely to be positive in animal cancer tests. We also conclude that at the low doses of most human exposures the comparative hazards of synthetic pesticide residues are insignificant. PMID:2217210

  11. 14 CFR 99.19-99.31 - [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false 99.19-99.31 Section 99.19-99.31 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SECURITY CONTROL OF AIR TRAFFIC General §§ 99.19-99.31...

  12. Feasibility of Production of Moly-99 via 1-neutron Exchange Reaction 98 Mo +100 Mo -->299Mo in Strong-Focusing Auto Collider (``EXYDER'') of natural Molybdenum nuclei based on T and He-3 production data from d +d weak focusing Auto-Collider MIGMA IV

    NASA Astrophysics Data System (ADS)

    Hester, Tim; Maglich, Bogdan; Calsec Collaboration

    2015-10-01

    Copious T and 3He production from D(d, p) T and D(d, n) 3He reactions in 725 KeV colliding beams was observed in weak-focusing Self-Collider1-4 radius 15 cm, in B = 3.12 T, stabilized5 non-linearly by electron cloud oscillations with confinement time ~ 23 s. BARC's simulations7 predict that by switching to Strong Focusing Self Collider proposed by Blewett6, 10 deuterons 0.75 MeV each, will generate 1 3He + 1T +1p + 1n at a total input energy cost of 10.72 MeV. Economic value of T and 3He is 65 and 120 MeV/atom respectively. While energy balance is negative, we project economic gain 205 MeV/10.72 MeV ~ 20 i.e. 3He production/sale will fund cost of T. Assuming the luminosity achieved in MIGMA IV, we replace D beam injection with a high energy beam of 14 times ionized natural Mo ions and look for the 1-neutron reactions of the type 98Mo+100Mo -->299Mo, where 99Mo14+ will be EM channeled into a mass spectrometer and collected at one loci/ radius, while all other masses/radii rejected. Physics and engineering parameters required to produce at least 1 g of 99Mo per day, at an electricity cost of 100K, will be presented. 2- and 3-neutron exchange reactions will be considered, too.

  13. Transfer of molybdenum disulfide to various metals

    NASA Technical Reports Server (NTRS)

    Barton, G. C.; Pepper, S. V.

    1977-01-01

    Sliding friction experiments were conducted with molybdenum disulfide single crystals in contact with sputter cleaned surfaces of copper, nickel, gold, and 304 stainless steel. Transfer of the molybdenum disulfide to the metals was monitored with Auger electron spectroscopy. Results of the investigation indicate molybdenum disulfide transfers to all clean metal surfaces after a single pass over the metal surface with film thickness observed to increase with repeated passes over the same surfaces. Large particle transfer occurs when the orientation of the crystallites is other than basal. This is frequently accompanied by abrasion of the metal. Adhesion of molybdenum disulfide films occurred readily to copper and nickel, less readily to 304 stainless steel, and even less effectively to the gold, which indicates a chemical effect.

  14. Upper critical field of copper molybdenum sulfide

    NASA Technical Reports Server (NTRS)

    Alterovitz, S. A.; Woollam, J. A.

    1978-01-01

    The upper critical field of sintered and sputtered copper molybdenum sulfide Cu(x)Mo6S8 was measured and found to exceed the Werthamer, Helfand, and Hohenberg (1966) value for a type II superconductor characterized by dirty limit, weak isotropic electron phonon coupling, and no paramagnetic limiting. It is suggested that the enhancement results from anisotropy or clean limit or both. Other ternary molybdenum sulfides appear to show similar anomalies.

  15. Powder Metallurgy Fabrication of Molybdenum Accelerator Target Disks

    SciTech Connect

    Lowden, Richard Andrew; Kiggans Jr., James O.; Nunn, Stephen D.; Parten, Randy J.

    2015-07-01

    Powder metallurgy approaches for the fabrication of accelerator target disks are being examined to support the development of Mo-99 production by NorthStar Medical Technologies, LLC. An advantage of powder metallurgy is that very little material is wasted and, at present, dense, quality parts are routinely produced from molybdenum powder. The proposed targets, however, are thin wafers, 29 mm in diameter with a thickness of 0.5 mm, with very stringent dimensional tolerances. Although tooling can be machined to very high tolerance levels, the operations of powder feed, pressing and sintering involve complicated mechanisms, each of which affects green density and shrinkage, and therefore the dimensions and shape of the final product. Combinations of powder morphology, lubricants and pressing technique have been explored to produce target disks with minimal variations in thickness and little or no distortion. In addition, sintering conditions that produce densities for optimum target dissolvability are being determined.

  16. Enhanced electrochromism in cerium doped molybdenum oxide thin films

    SciTech Connect

    Dhanasankar, M.; Purushothaman, K.K.; Muralidharan, G.

    2010-12-15

    Cerium (5-15% by weight) doped molybdenum oxide thin films have been prepared on FTO coated glass substrate at 250 {sup o}C using sol-gel dip coating method. The structural and morphological changes were observed with the help of XRD, SEM and EDS analysis. The amorphous structure of the Ce doped samples, favours easy intercalation and deintercalation processes. Mo oxide films with 10 wt.% of Ce exhibit maximum anodic diffusion coefficient of 24.99 x 10{sup -11} cm{sup 2}/s and the change in optical transmittance of ({Delta}T at 550 nm) of 79.28% between coloured and bleached state with the optical density of ({Delta}OD) 1.15.

  17. Effects of copper sulfate supplement on growth, tissue concentration, and ruminal solubilities of molybdenum and copper in sheep fed low and high molybdenum diets

    SciTech Connect

    Ivan, M.; Veira, D.M.

    1985-01-01

    Each of four groups of six wethers were fed one of a low molybdenum, high molybdenum, high molybdenum plus copper sulfate, or high molybdenum plus copper sulfate corn silage-based diet for ad libitum intake for 221 days. Average daily gains and ratios of feed/gain were depressed for the high molybdenum diet as compared with the low molybdenum diet suggesting molybdenum toxicity in sheep fed the high molybdenum diet. This was alleviated partly by the copper sulfate supplement. The supplement also decreased solubility of both copper and molybdenum in the rumen but had no effect on copper concentration in blood plasma. Concentration of molybdenum was higher in both liver and kidney in sheep fed high-molybdenum diets as compared with low-molybdenum diets. Copper concentration was higher in kidneys of sheep fed high-molybdenum diets, but no difference was significant in liver copper between sheep fed diets high or low in molybdenum.

  18. Determination of thiamazole in pharmaceutical samples by phosphorus molybdenum blue spectrophotometry.

    PubMed

    Huo, Jing'e; Li, Quanmin

    2012-02-15

    A novel method is established to determine thiamazole by phosphorus molybdenum blue spectrophotometry. The experiment indicates that PO(4)(3-) reacts with Mo(7)O(24)(6-) in 0.30mol/L H(2)SO(4) solution to form a product with phosphorus-molybdenum heteropoly acid ([H(2)PMo(12)O(40)](-)). Then [H(2)PMo(12)O(40)](-) is deoxidized to form phosphorus molybdenum blue (H(3)PO(4)·10MoO(3)·Mo(2)O(5)) by thiamazole. The amount of thiamazole can be determined based on the absorbance of phosphorus molybdenum blue (λ(max)=710nm). A good linear relationship is obtained between the absorbance and the concentration of thiamazole in the range of 0.035-70μg/mL. The equation of the linear regression is A=0.03384+0.00834c (μg/mL), with a linear correlation coefficient of 0.9990. The apparent molar absorption coefficient is 1.0×10(3)L/(molcm). The method has been successfully applied to the determination of thiamazole in pharmaceutical samples with satisfactory results, and recoveries are in the range of 99.6-100.6%.

  19. The Densification of Molybdenum and Molybdenum Alloy Powders Using Hot Isostatic Pressing.

    DTIC Science & Technology

    1985-08-01

    TECHNICAL REPORT ARLCB-TR-85025 00 THE DENSIFICATION OF MOLYBDENUM (n AND MOLYBDENUM ALLOY POWDERS USING HOT ISOSTATIC PRESSING J. BARRANCO I. AHMAD S...ISOSTATIC PRESSING Final 6. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(o) . CONTRACT OR GRANT NUMBER(e) J. Barranco , I. Ahmad, S. Isserow, and R. Warenchak

  20. A simple spectrophotometric method for the determination of trace levels of molybdenum using N,N'-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane.

    PubMed

    Kara, Derya; Karadaş, Cennet

    2015-08-05

    The present work describes a selective, rapid and economical spectrophotometric method for the determination of molybdenum using N,N'-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane. Molybdenum(VI) reacts with N,N'-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane to form a stable 1:1 yellow complex with an absorption maximum at 342 nm. The reaction is completed within 10 min and the absorbance of the molybdenum complex remains stable for at least 1 week at room temperature. The effective molar absorption coefficient at 342 nm was 9.6 × 10(3)L mol(-1)cm(-1). Under optimal conditions, the complex obeys Beer's law from 0 to 9.9 μg mL(-1). The relative standard deviation was 0.08% (for 11 samples, each containing 6 μg mL(-1) molybdenum). Under the optimum conditions, the detection limit (3σ) was 17.7 μg L(-1) for molybdenum without any preconcentration. The precision was determined from 30 results obtained for 4.80 μg mL(-1) Mo(VI); the mean value of a molybdenum(VI) was 4.83 μg ml(-1) with a standard derivation of 0.002 μg ml(-1) molybdenum(VI).

  1. A simple spectrophotometric method for the determination of trace levels of molybdenum using N,N‧-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane

    NASA Astrophysics Data System (ADS)

    Kara, Derya; Karadaş, Cennet

    2015-08-01

    The present work describes a selective, rapid and economical spectrophotometric method for the determination of molybdenum using N,N‧-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane. Molybdenum(VI) reacts with N,N‧-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane to form a stable 1:1 yellow complex with an absorption maximum at 342 nm. The reaction is completed within 10 min and the absorbance of the molybdenum complex remains stable for at least 1 week at room temperature. The effective molar absorption coefficient at 342 nm was 9.6 × 103 L mol-1 cm-1. Under optimal conditions, the complex obeys Beer's law from 0 to 9.9 μg mL-1. The relative standard deviation was 0.08% (for 11 samples, each containing 6 μg mL-1 molybdenum). Under the optimum conditions, the detection limit (3σ) was 17.7 μg L-1 for molybdenum without any preconcentration. The precision was determined from 30 results obtained for 4.80 μg mL-1 Mo(VI); the mean value of a molybdenum(VI) was 4.83 μg ml-1 with a standard derivation of 0.002 μg ml-1 molybdenum(VI).

  2. Radioactive equilibrium: 99Mo/99mTc decay characteristics.

    PubMed

    Chechev, Valery P; Bé, Marie-Martine

    2014-05-01

    Within the Decay Data Evaluation Project, as an example of a radioactive equilibrium with isomer, the (99)Mo/(99m)Tc equilibrium mixture decay characteristics are examined. The results of a new decay data evaluation are presented for (99)Mo/(99m)Tc decay to nuclear levels in (99)Tc. These evaluated data have been obtained using information published up to 2013.

  3. Molybdenum Isotopes and Soil Processes

    NASA Astrophysics Data System (ADS)

    Siebert, C.; Pett-Ridge, J. C.; Halliday, A. N.; Burton, K. W.

    2011-12-01

    The oxygenation state of Earth's oceans is a driver of evolution and extinction events as well as climate change. In recent years stable isotope fractionation of redox sensitive elements such as molybdenum (Mo) have been used as quantitative tracers of past redox-conditions in a number of marine environments. However, little is known about the processes controlling the Mo isotope compositions of the riverine inputs to the oceans and their short- and long-term variations. Several recent studies [Archer & Vance, 2008; Pearce et al., 2010] have shown that many river waters have heavy Mo isotope compositions. In some terrestrial weathering environments dissolved Mo isotope compositions in rivers are controlled by the catchment lithology [Neubert et al., 2011]. However, many rivers show fractionation of Mo isotopes relative to their catchment lithology. Possible mechanisms causing this fractionation are chemical weathering and pedogenic processes. This study has investigated the behavior of Mo isotopes during weathering of basalt under different conditions. Results from oxic to reducing soil profiles in Hawaii show that redox conditions during soil formation can control Mo isotope compositions in soils. Reducing soil profiles have light isotope compositions whereas oxidizing profiles are heavy. This general isotope behavior is confirmed by results from soil profiles from Iceland. Here reducing layers within the profiles show marked negative isotope excursions. In oxic profiles a surprisingly strong interaction of Mo with organic matter can be observed producing significant Mo isotope fractionation. This behavior might explain long term retention of Mo in soils besides its high mobility in molybdate form. Mo associated with organic matter is bioavailable and essential for processes like nitrogen fixation. In addition, we observe that fractionation relative to the source rock is dependent on the degree of weathering, i.e. relatively un-weathered profiles do not show

  4. Heptacoordinated molybdenum(VI) complexes of phenylenediamine bis(phenolate): a stable molybdenum amidophenoxide radical.

    PubMed

    Hänninen, Mikko M; Paturi, Petriina; Tuononen, Heikki M; Sillanpää, Reijo; Lehtonen, Ari

    2013-05-20

    The syntheses, crystallographic structures, magnetic properties, and theoretical studies of two heptacoordinated molybdenum complexes with N,N'-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-1,2-phenylenediamine (H4N2O2) are reported. A formally molybdenum(VI) complex [Mo(N2O2)Cl2(dmf)] (1) was synthesized by the reaction between [MoO2Cl2(dmf)2] and H4N2O2, whereas the other molybdenum(VI) complex [Mo(N2O2)(HN2O2)] (2) was formed when [MoO2(acac)2] was used as a molybdenum source. Both complexes represent a rare case of the Mo(VI) ion without any multiply bonded terminal ligands. In addition, molecular structures, magnetic measurements, ESR spectroscopy, and density functional theory calculations indicate that complex 2 is the first stable molybdenum(VI) amidophenoxide radical.

  5. Molybdenum reduction to molybdenum blue in Serratia sp. Strain DRY5 is catalyzed by a novel molybdenum-reducing enzyme.

    PubMed

    Shukor, M Y; Halmi, M I E; Rahman, M F A; Shamaan, N A; Syed, M A

    2014-01-01

    The first purification of the Mo-reducing enzyme from Serratia sp. strain DRY5 that is responsible for molybdenum reduction to molybdenum blue in the bacterium is reported. The monomeric enzyme has an apparent molecular weight of 105 kDalton. The isoelectric point of this enzyme was 7.55. The enzyme has an optimum pH of 6.0 and maximum activity between 25 and 35°C. The Mo-reducing enzyme was extremely sensitive to temperatures above 50°C (between 54 and 70°C). A plot of initial rates against substrate concentrations at 15 mM 12-MP registered a V max for NADH at 12.0 nmole Mo blue/min/mg protein. The apparent K m for NADH was 0.79 mM. At 5 mM NADH, the apparent V max and apparent K m values for 12-MP of 12.05 nmole/min/mg protein and 3.87 mM, respectively, were obtained. The catalytic efficiency (k cat/K m ) of the Mo-reducing enzyme was 5.47 M(-1) s(-1). The purification of this enzyme could probably help to solve the phenomenon of molybdenum reduction to molybdenum blue first reported in 1896 and would be useful for the understanding of the underlying mechanism in molybdenum bioremediation involving bioreduction.

  6. Factors affecting eluation characteristics of sorption generators of technetium-99m

    NASA Astrophysics Data System (ADS)

    Skuridin, V. S.; Chernov, V. I.; Sadkin, V. L.; Stasyuk, E. S.; Varlamova, N. V.; Rogov, A. S.; Nesterov, E. A.; Ilina, E. A.; Larionova, L. A.; Medvedeva, A. A.

    2016-08-01

    The influence of the adsorbed mass of molybdenum on the width of eluation profiles of generators and the patterns of molybdenum distribution in the amount of chromatographic columns by scanning them on the germanium-gallium detector using collimating device are studied. The boundary conditions under which the maximum value of 99mTc yield from generators Ye = 1 are defined. After scanning the columns, it was found out that the degree of filling the columns with molybdenum Q and the value of its maximum adsorption depend naturally on the total weight of the adsorbed mass. In order to achieve the condition Ye = 1 the value of Q should be at least 85%.

  7. Molybdenum Metallopharmaceuticals Candidate Compounds - The "Renaissance" of Molybdenum Metallodrugs?

    PubMed

    Jurowska, Anna; Jurowski, Kamil; Szklarzewicz, Janusz; Buszewski, Boguslaw; Kalenik, Tatiana; Piekoszewski, Wojciech

    2016-01-01

    Metal-based drugs, also called "metallopharmaceuticals" or "metallodrugs", are examples of sophisticated compounds that have been used in inorganic medicinal chemistry as therapeutic agents for a long time. Few of them have shown substantially promising results and many of them have been used in different phases of clinical trials. The Mo-based metallodrugs were successfully applied in the past for treating conditions such as anemia or Wilson's disease. Moreover, Mo complexes are supposed to exert their effect by intercalation/ cleavage of DNA/RNA, arrest of the cell cycle, and alteration of cell membrane functions. However, in the current literature, there are no reliable and in-depth reviews about the hypothetical therapeutic applications of all of the known molybdenum complexes as metallopharmaceuticals/ metallodrugs. The main emphasis was on the in-depth review of the potential applications of Mo-based complexes in medicinal chemistry as metallopharmaceuticals in treating diseases such as cancer and tumors, Wilson's disease, diabetes mellitus, Huntington's disease, atherosclerosis, and anemia. It must be emphasized that today the development of innovative and new Mo-based metalo-pharmaceuticals is not rapid, and hence the aim of this paper was also to inspire colleagues working in the field of Mo compounds who are trying to find "signpost" for research. The authors hope that this article will increase interest and initiate the Renaissance of Mo-compounds among medicinal inorganic chemists. This paper is the first review article in the literature that refers to and emphasizes many different and complex aspects of possible applications and capabilities of Mo-based metallodrugs.

  8. Western Molybdenum Company mine, Chewelah District, Stevens County, Washington

    USGS Publications Warehouse

    Cooper, John R.

    1954-01-01

    The Western Molybdenum Co. mine was opened many years ago to obtain copper. The only production was several carloads of crude copper ore shipped during World War I. An unsuccessful attempt to produce molybdenum was made in 1939-1941.

  9. Zinc deficiency in molybdenum poisoned cattle

    SciTech Connect

    Parada, R.

    1981-02-01

    Clinical signs ascribable to zinc deficiency were noted in a group of Friesian cows industrially poisoned with molybdenum. Zinc, copper, and molybdenum were determined in blood serum and black hair, and in the contaminated alfalfa pasture the group grazed on. Hematological parameters, and serum calcium and alkaline phosphatase activity, were also determined. Pooled samples of alfalfa from 2 uncontaminated pastures, and of blood, serum and black hair of clinically normal Friesian cattle grazing on these were used as controls. A mixed contamination of the polluted pasture with molybdenum and copper was found, both metals being inversely correlated with he distance to the polluting chimney. Zinc concentrations were normal and not significantly correlated with the distance to the chimney very high molybdenum was found in serum and hair of the poisoned animals; copper was normal in serum and hair. Low calcium and Alkaline phosphatase activity were found in serum, both variables being significantly correlated with serum zinc. Reduced red blood cell number, packed cell volumes and hemoglobin concentrations were also found, but no significant correlation of these parameters with any of the trace metals in serum or hair was found. Signs ascribed to zinc deficiency were consistent with the reduction of zinc in serum and hair and decreased alkaline phosphatase activity in serum. A zinc deficiency conditioned by a simultaneous increased intake of molybdenum and copper is proposed.

  10. 99 Films on Drugs.

    ERIC Educational Resources Information Center

    Weber, David O., Ed.

    This catalog describes and evaluates 16-millimeter films about various aspects of drug use. Among the subjects covered by the 99 films are the composition and effects of different drugs, reasons why people use drugs, life in the drug culture, the problem of law enforcement, and various means of dealing with drug users. Each film is synopsized. Two…

  11. JENDL Dosimetry File 99.

    SciTech Connect

    KEIICHI,; SHIBATA,

    2001-01-22

    Version 00 JENDL/D-99 contains information for 47 nuclides and 67 reactions in the SAND-II group structure (although it was observed by RSICC that not all of the processed files are in the SAND-II group structure) and as 0K preprocessed pointwise files.

  12. Effect of molybdenum treatment on molybdenum concentration and nitrate reduction in maize seedlings.

    PubMed

    Kovács, Béla; Puskás-Preszner, Anita; Huzsvai, László; Lévai, László; Bódi, Éva

    2015-11-01

    Since 1940 molybdenum has been known as an essential trace element in plant nutrition and physiology. It has a central role in nitrogen metabolism, and its deficiency leads to nitrate accumulation in plants. In this study, we cultivated maize seedlings (Zea mays L. cv. Norma SC) in nutrient solution and soil (rhizoboxes) to investigate the effect of molybdenum treatment on the absorption of molybdenum, sulfur and iron. These elements have been previously shown to play important roles in nitrate reduction, because they are necessary for the function of the nitrate reductase enzyme. We also investigated the relationship between molybdenum treatments and different nitrogen forms in maize. Molybdenum treatments were 0, 0.96, 9.6 and 96 μg kg(-1) in the nutrition solution experiments, and 0, 30, 90, 270 mg kg(-1) in the rhizobox experiments. On the basis of our results, the increased Mo level produced higher plant available Mo concentration in nutrient solution and in soil, which resulted increased concentration of Mo in shoots and roots of maize seedlings. In addition it was observed that maize seedlings accumulated more molybdenum in their roots than in their shoots at all treatments. In contrast, molybdenum treatments did not affect significantly either iron or sulfur concentrations in the plant, even if these elements (Mo, S and Fe) play alike important roles in nitrogen metabolism. Furthermore, the physiological molybdenum level (1× Mo = 0.01 μM) reduced NO3-N and enhanced the NH4-N concentrations in seedlings, suggesting that nitrate reduction was more intense under a well-balanced molybdenum supply.

  13. Reduced molybdenum oxide as an efficient electron injection layer in polymer light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Vasilopoulou, Maria; Palilis, Leonidas C.; Georgiadou, Dimitra G.; Argitis, Panagiotis; Kennou, Stella; Sygellou, Labrini; Kostis, Ioannis; Papadimitropoulos, Giorgos; Konofaos, Nikos; Iliadis, Agis A.; Davazoglou, Dimitris

    2011-03-01

    We report a significant improvement in the performance of single layer polymer light-emitting diodes (PLEDs), based on the green emitting copolymer poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2, 1',3}-thiadiazole)], upon inserting a very thin layer of partially reduced molybdenum oxide (MoOx, where x=2.7) at the polymer/Al cathode interface. Both fully oxidized (x=3) and partially reduced (x=2.7) thin molybdenum oxide layers were investigated as electron injection layers and their influence on PLED device performance was examined. Improved current density, luminance, and efficiency was achieved only in the case of devices with a thin partially reduced MoO2.7 film as electron injection layer, as a result of improved electron injection and more facile transfer at the modified polymer/Al interface.

  14. Recovery of the molybdenum catalyst for fossil fuel hydrogenation

    SciTech Connect

    L.A. Zekel; N.P. Goryunova; N.V. Krasnobaeva; G.B. Skripchenko; M. Y. Shpirt

    2009-07-01

    The composition and the properties of molybdenum-containing residues remaining after catalytic hydrogenation of coals and bitumen were studied. The chemical and the mineralogical composition of the products and the forms of molybdenum compounds were established. The techniques of concentration of molybdenum compounds (flotation, magnetic separation, and oxidative sublimation of MoO{sub 3}) were considered.

  15. Molybdenum Valence in Basaltic Silicate Melts

    NASA Technical Reports Server (NTRS)

    Danielson, L. R.; Righter, K.; Newville, M.; Sutton, S.; Pando, K.

    2010-01-01

    The moderately siderophile element molybdenum has been used as an indicator in planetary differentiation processes, and is particularly relevant to core formation [for example, 1-6]. However, models that apply experimental data to an equilibrium differentiation scenario infer the oxidation state of molybdenum from solubility data or from multivariable coefficients from metal-silicate partitioning data [1,3,7]. Partitioning behavior of molybdenum, a multivalent element with a transition near the J02 of interest for core formation (IW-2) will be sensitive to changes in JO2 of the system and silicate melt structure. In a silicate melt, Mo can occur in either 4+ or 6+ valence state, and Mo6+ can be either octahedrally or tetrahedrally coordinated. Here we present first XANES measurements of Mo valence in basaltic run products at a range of P, T, and JO2 and further quantify the valence transition of Mo.

  16. Densification of molybdenum and molybdenum alloy powders using hot isostatic pressing. Final technical report

    SciTech Connect

    Barranco, J.; Ahmad, I.; Isserow, S.; Warenchak, R.

    1985-08-01

    This study was conducted to determine a superior erosion-resistant gun-barrel liner material with improved properties at higher temperatures. Four categories of powders were examined: 1. TZM spherical containing 0.5 titanium, 0.08 zirconium, and 0.02 carbon (wt. % nominally), balance molybdenum (Mo), produced by REP (Rotating Electrode Process), PREP (Plasma Rotating Electrode Process), and PMRS (Plasma Melted and Rapidly Solidified); 2. Mo reduced 2 and 5 microns; 3. Mo-0.1% cobalt, co-reduced; 4. Mo-5 wt. % alumina (A12O3), dispersion strengthened. Hot Isostatic Pressing (HIP) densification occurred at 15-30 Ksi, 1300-1600 C, for 1.5 to 3.0 hours. The TZM REP/PREP powders (220/74 microns) were not fully densified even at 1600 C, 30 Ksi, 3 hours. Point-particle contact prevented complete void elimination. TZM PMRS powder (24.7 microns) achieved 99% of theoretical density while maintaining a small grain size (10.4 ASTM eq.) Bend deflection and fracture energies were approximately three times those for PREP powder at a bend rupture strength of about 120 Ksi. Mo reduced and Mo-0.1% Co powders showed less (or the same) ductility with increasing HIP temperatures. Fractures were intergranular with decreased bend rupture and compression strength. The Mo-5A1/sub 2/O/sub 3/ powder maintained a fine grain size (13 ASTM eq.), but with fracture energies usually less than 0.6 in.-lbs. Included are results from bending and compression testing with metallographic and fracture mode interpretation.

  17. Pre-treatment for molybdenum or molybdenum-rich alloy articles to be plated

    DOEpatents

    Wright, Ralph R.

    1980-01-01

    This invention is a method for etching a molybdenum or molybdenum-rich alloy surface to promote the formation of an adherent bond with a subsequently deposited metallic plating. In a typical application, the method is used as a pre-treatment for surfaces to be electrolessly plated with nickel. The pre-treatment comprises exposing the crystal boundaries of the surface by (a) anodizing the surface in acidic solution to form a continuous film of gray molybdenum oxide thereon and (b) removing the film.

  18. Evaluation of molybdenum and its alloys. [Reactor core heat pipes

    SciTech Connect

    Lundberg, L.B.

    1981-01-01

    The choice of pure molybdenum as the prime candidate material for space reactor core heat pipes is critically examined. Pure molybdenum's high ductile-brittle transition temperature appears to be its major disadvantage. The candidate materials examined in detail for this application include low carbon arc-cast molybdenum, TZM-molybdenum alloy, and molybdenum-rhenium alloys. Published engineering properties are collected and compared, and it appears that Mo-Re alloys with 10 to 15% rhenium offer the best combination. Hardware is presently being made from electron beam melted Mo-13Re to test this conclusion.

  19. Exploring atomic defects in molybdenum disulphide monolayers

    PubMed Central

    Hong, Jinhua; Hu, Zhixin; Probert, Matt; Li, Kun; Lv, Danhui; Yang, Xinan; Gu, Lin; Mao, Nannan; Feng, Qingliang; Xie, Liming; Zhang, Jin; Wu, Dianzhong; Zhang, Zhiyong; Jin, Chuanhong; Ji, Wei; Zhang, Xixiang; Yuan, Jun; Zhang, Ze

    2015-01-01

    Defects usually play an important role in tailoring various properties of two-dimensional materials. Defects in two-dimensional monolayer molybdenum disulphide may be responsible for large variation of electric and optical properties. Here we present a comprehensive joint experiment–theory investigation of point defects in monolayer molybdenum disulphide prepared by mechanical exfoliation, physical and chemical vapour deposition. Defect species are systematically identified and their concentrations determined by aberration-corrected scanning transmission electron microscopy, and also studied by ab-initio calculation. Defect density up to 3.5 × 1013 cm−2 is found and the dominant category of defects changes from sulphur vacancy in mechanical exfoliation and chemical vapour deposition samples to molybdenum antisite in physical vapour deposition samples. Influence of defects on electronic structure and charge-carrier mobility are predicted by calculation and observed by electric transport measurement. In light of these results, the growth of ultra-high-quality monolayer molybdenum disulphide appears a primary task for the community pursuing high-performance electronic devices. PMID:25695374

  20. Method for welding chromium molybdenum steels

    DOEpatents

    Sikka, Vinod K.

    1986-01-01

    Chromium-molybdenum steels exhibit a weakening after welding in an area adjacent to the weld. This invention is an improved method for welding to eliminate the weakness by subjecting normalized steel to a partial temper prior to welding and subsequently fully tempering the welded article for optimum strength and ductility.

  1. Molybdenum oxide electrodes for thermoelectric generators

    DOEpatents

    Schmatz, Duane J.

    1989-01-01

    The invention is directed to a composite article suitable for use in thermoelectric generators. The article comprises a thin film comprising molybdenum oxide as an electrode deposited by physical deposition techniques onto solid electrolyte. The invention is also directed to the method of making same.

  2. The biosynthesis of the molybdenum cofactors.

    PubMed

    Mendel, Ralf R; Leimkühler, Silke

    2015-03-01

    The biosynthesis of the molybdenum cofactors (Moco) is an ancient, ubiquitous, and highly conserved pathway leading to the biochemical activation of molybdenum. Moco is the essential component of a group of redox enzymes, which are diverse in terms of their phylogenetic distribution and their architectures, both at the overall level and in their catalytic geometry. A wide variety of transformations are catalyzed by these enzymes at carbon, sulfur and nitrogen atoms, which include the transfer of an oxo group or two electrons to or from the substrate. More than 50 molybdoenzymes were identified to date. In all molybdoenzymes except nitrogenase, molybdenum is coordinated to a dithiolene group on the 6-alkyl side chain of a pterin called molybdopterin (MPT). The biosynthesis of Moco can be divided into three general steps, with a fourth one present only in bacteria and archaea: (1) formation of the cyclic pyranopterin monophosphate, (2) formation of MPT, (3) insertion of molybdenum into molybdopterin to form Moco, and (4) additional modification of Moco in bacteria with the attachment of a nucleotide to the phosphate group of MPT, forming the dinucleotide variant of Moco. This review will focus on the biosynthesis of Moco in bacteria, humans and plants.

  3. Minerals yearbook, 1991: Molybdenum. Annual report

    SciTech Connect

    Blossom, J.W.

    1993-01-01

    Mr. Blossom, a physical scientist/engineer with 44 years' industry and Government experience, has been the commodity specialist for molybdenum since 1982. Survey and trade data were prepared by Sherwood C. Jordan, mineral data assistant; and the world production tables were prepared by Harold D. Willis, international data coordinator.

  4. Modification of base-side {sup 99}MO production processes for LEU metal-foil targets.

    SciTech Connect

    Vandegrift, G. F.; Leonard, R. A.; Aase, S.; Sedlet, J.; Koma, Y.; Conner, C.; Clark, C. R.; Meyer, M. K.

    1999-09-30

    Argonne National Laboratory is cooperating with the National Atomic Energy Commission of the Argentine Republic (CNEA) to convert their {sup 99}Mo production process, which uses high enriched uranium (HEU), to low-enriched uranium (LEU), The program is multifaceted; however, discussed in this paper are (1) results of laboratory experiments to develop means for substituting LEU metal-foil targets into the current process and (2) preparation of uranium-alloy or uranium-metal/aluminum-dispersion targets. Although {sup 99}Mo production is a multi-step process, the first two steps (target dissolution and primary molybdenum recovery) are by far the most important in the conversion. Commonly, once molybdenum is separated from the bulk of the uranium, the remainder of the process need not be modified. Our results show that up to this point in our study, conversion of the CNEA process to LEU appears viable.

  5. Post-Irradiation Fracture Toughness of Unalloyed Molybdenum, ODS molybdenum, and TZM molybdenum following irradiation at 244C to 507C

    SciTech Connect

    Cockeram, Brian V; Byun, Thak Sang; Leonard, Keith J; Snead, Lance Lewis

    2013-01-01

    Commercially available unalloyed molybdenum (Low Carbon Arc Cast (LCAC)), Oxide Dispersion Strengthened (ODS) molybdenum, and TZM molybdenum were neutron irradiated at temperatures of nominally 244 C, 407 C, and 509 C to neutron fluences between 1.0 to 4.6x1025 n/m2 (E>0.1 MeV). Post-irradiation fracture toughness testing was performed. All alloys exhibited a Ductile to Brittle Transition Temperature that was defined to occur at 30 4 MPa-m1/2. The highest post-irradiated fracture toughness values (26-107 MPa-m1/2) and lowest DBTT (100-150 C) was observed for ODS molybdenum in the L-T orientation. The finer grain size for ODS molybdenum results in fine laminates that improve the ductile laminate toughening. The results for ODS molybdenum are anisotropic with lower post-irradiated toughness values (20-30 MPa-m1/2) and higher DBTT (450-600 C) in the T-L orientation. The results for T-L ODS molybdenum are consistent or slightly better than those for LCAC molybdenum (21-71 MPa-m1/2 and 450-800 C DBTT). The fracture toughness values measured for LCAC and T-L ODS molybdenum at temperatures below the DBTT were determined to be 8-18 MPa-m1/2. Lower non-irradiated fracture toughness values were measured for TZM molybdenum that are attributed to the large carbide precipitates serving as preferential fracture initiation sites. The role of microstructure and grain size on post-irradiated fracture toughness was evaluated by comparing the results for LCAC molybdenum and ODS molybdenum.

  6. Electronic properties of reduced molybdenum oxides.

    PubMed

    Inzani, K; Nematollahi, M; Vullum-Bruer, F; Grande, T; Reenaas, T W; Selbach, S M

    2017-03-29

    The electronic properties of MoO3 and reduced molybdenum oxide phases are studied by density functional theory (DFT) alongside characterization of mixed phase MoOx films. Molybdenum oxide is utilized in compositions ranging from MoO3 to MoO2 with several intermediary phases. With increasing degree of reduction, the lattice collapses and the layered MoO3 structure is lost. This affects the electronic and optical properties, which range from the wide band gap semiconductor MoO3 to metallic MoO2. DFT is used to determine the stability of the most relevant molybdenum oxide phases, in comparison to oxygen vacancies in the layered MoO3 lattice. The non-layered phases are more stable than the layered MoO3 structure for all oxygen stoichiometries of MoOx studied where 2 ≤ x < 3. Reduction and lattice collapse leads to strong changes in the electronic density of states, especially the filling of the Mo 4d states. The DFT predictions are compared to experimental studies of molybdenum oxide films within the same range of oxygen stoichiometries. We find that whilst MoO2 is easily distinguished from MoO3, intermediate phases and phase mixtures have similar electronic structures. The effect of the different band structures is seen in the electrical conductivity and optical transmittance of the films. Insight into the oxide phase stability ranges and mixtures is not only important for understanding molybdenum oxide films for optoelectronic applications, but is also relevant to other transition metal oxides, such as WO3, which exist in analogous forms.

  7. Technetium-99m generator system

    DOEpatents

    Mirzadeh, S.; Knapp, F.F. Jr.; Collins, E.D.

    1998-06-30

    A {sup 99}Mo/{sup 99m}Tc generator system includes a sorbent column loaded with a composition containing {sup 99}Mo. The sorbent column has an effluent end in fluid communication with an anion-exchange column for concentrating {sup 99m}Tc eluted from the sorbent column. A method of preparing a concentrated solution of {sup 99m}Tc includes the general steps of: (a) providing a sorbent column loaded with a composition containing {sup 99}Mo, the sorbent column having an effluent end in fluid communication with an anion-exchange column; (b) eluting the sorbent column with a salt solution to elute {sup 99m}Tc from the sorbent and to trap and concentrate the eluted {sup 99m}Tc on the ion-exchange column; and (c) eluting the concentrated {sup 99m}Tc from the ion-exchange column with a solution comprising a reductive complexing agent. 1 fig.

  8. Technetium-99m generator system

    DOEpatents

    Mirzadeh, Saed; Knapp, Jr., Furn F.; Collins, Emory D.

    1998-01-01

    A .sup.99 Mo/.sup.99m Tc generator system includes a sorbent column loaded with a composition containing .sup.99 Mo. The sorbent column has an effluent end in fluid communication with an anion-exchange column for concentrating .sup.99m Tc eluted from the sorbent column. A method of preparing a concentrated solution of .sup.99m Tc includes the general steps of: a. providing a sorbent column loaded with a composition containing .sup.99 Mo, the sorbent column having an effluent end in fluid communication with an anion-exchange column; b. eluting the sorbent column with a salt solution to elute .sup.99m Tc from the sorbent and to trap and concentrate the eluted .sup.99m Tc on the ion-exchange column; and c. eluting the concentrated .sup.99m Tc from the ion-exchange column with a solution comprising a reductive complexing agent.

  9. A novel route for processing cobalt–chromium–molybdenum orthopaedic alloys

    PubMed Central

    Patel, Bhairav; Inam, Fawad; Reece, Mike; Edirisinghe, Mohan; Bonfield, William; Huang, Jie; Angadji, Arash

    2010-01-01

    Spark plasma sintering has been used for the first time to prepare the ASTM F75 cobalt–chromium–molybdenum (Co–Cr–Mo) orthopaedic alloy composition using nanopowders. In the preliminary work presented in this report, the effect of processing variables on the structural features of the alloy (phases present, grain size and microstructure) has been investigated. Specimens of greater than 99.5 per cent theoretical density were obtained. Carbide phases were not detected in the microstructure but oxides were present. However, harder materials with finer grains were produced, compared with the commonly used cast/wrought processing methods, probably because of the presence of oxides in the microstructure. PMID:20200035

  10. Optimization of the dissolution of molybdenum disks. FY-16 results

    SciTech Connect

    Tkac, Peter; Rotsch, David A.; Chemerisov, Sergey D.; Bailey, James L.; Krebs, John F.; Vandegrift, George F.

    2016-09-01

    Argonne National Laboratory is providing technical development assistance to NorthStar Medical Technologies LLC in its pursuit of two pathways for production of molybdenum-99: the 98Mo(n,γ) 99Mo reaction and the photonuclear reaction, 100Mo(γ,n)99Mo. Processing of irradiated targets, from either production mode, requires dissolution of the target material in H2O2 followed by a concentration step, addition of ferric ion to precipitate impurities, and conversion of the final solution to 5M potassium hydroxide solution of potassium molybdate. Currently, NorthStar is using pressed and sintered Mo disks as targets. Several options are being considered for the design of Mo targets for the production of 99Mo using the (γ,n) reaction. In the current design, the target holder contains a series of sintered Mo disks lined up perpendicular to two incident electron beams, one entering from each side of the target stack. In this configuration, the front-most disks absorb most of the heat from the electron beam and need to be thinner to allow for better cooling, while the middle of the target can be thicker. Distribution of the total mass of Mo allows for larger masses of Mo material and thus larger production batches of 99Mo. A limitation of the sintering approach is the production of very thin disks. Recent advances in 3D printing allow for much thinner target components can be achieved than when the traditional press-and-sinter approach is used. We have demonstrated that several factors can play important roles in dissolution behavior: particle size of Mo metal used for production of targets, sintering conditions, degree of open porosity, and thickness of the sintered Mo targets. Here we report experimental results from studies of small-scale dissolution of sintered Mo disks fabricated from various recycled and commercial Mo materials, and dissolution of 3D-printed Mo disks that were

  11. Technetium-99 in generator systems.

    PubMed

    Moore, P W

    1984-04-01

    Technetium-99m solutions always contain Tc-99. The amount varies considerably, depending on production methods and conditions, generator performance, and the time between production or separation and use. There is increasing evidence that labeling and imaging with some radiopharmaceutical kits is adversely affected when the Tc-99 exceeds certain amounts. The sensitivity of particular kits to Tc-99 depends on the ligand, the amount of usable Sn2+, and the ratio of Tc to ligand. Although Tc-99 formed during production is removed in the final steps of generator manufacture, some may appear in early extractions in the solvent extraction process. If elution or extraction efficiencies are high, any Tc-99 is reduced within about two elutions to an insignificant level that is maintained in subsequent elutions. If efficiencies are below about 40%, however, the ratio of Tc-99 to Tc-99m increases with each elution.

  12. A Solution-Based Approach for Mo-99 Production: Considerations for Nitrate versus Sulfate Media

    DOE PAGES

    Youker, Amanda J.; Chemerisov, Sergey D.; Kalensky, Michael; ...

    2013-01-01

    Molybdenum-99 is the parent of Technetium-99m, which is used in nearly 80% of all nuclear medicine procedures. The medical community has been plagued by Mo-99 shortages due to aging reactors, such as the NRU (National Research Universal) reactor in Canada. There are currently no US producers of Mo-99, and NRU is scheduled for shutdown in 2016, which means that another Mo-99 shortage is imminent unless a potential domestic Mo-99 producer fills the void. Argonne National Laboratory is assisting two potential domestic suppliers of Mo-99 by examining the effects of a uranyl nitrate versus a uranyl sulfate target solution configuration onmore » Mo-99 production. Uranyl nitrate solutions are easier to prepare and do not generate detectable amounts of peroxide upon irradiation, but a high radiation field can lead to a large increase in pH, which can lead to the precipitation of fission products and uranyl hydroxides. Uranyl sulfate solutions are more difficult to prepare, and enough peroxide is generated during irradiation to cause precipitation of uranyl peroxide, but this can be prevented by adding a catalyst to the solution. A titania sorbent can be used to recover Mo-99 from a highly concentrated uranyl nitrate or uranyl sulfate solution; however, different approaches must be taken to prevent precipitation during Mo-99 production.« less

  13. Extraction, spectrophotometric and atomic absorption spectrophotometric determination of molybdenum with caffeic acid and application in high purity grade steel and environmental samples

    SciTech Connect

    Shah, N.; Desai, M.N. ); Menon, S.K.; Agrawal, Y.K. )

    1989-06-01

    A new selective and sensitive method for extraction of yellow Mo(VI)-caffeic acid complex with a liquid ion exchanger, Aliquat 336 from 4.0 pH, and spectrophotometric determination of molybdenum in trace amounts is described. The molar absorptivity of the complex is 1.1 {times} 10{sup 5} 1 mol{sup {minus}1} cm{sup {minus}1} at 340 nm and the color system obeys Beers law in the range 0.04-0.99 ppm of Mo(VI). The molybdenum is also determined with AAS and the method is applied for its determination in steel and environmental samples.

  14. Evaluation of oxide dispersion strengthened (ODS) molybdenum and molybdenum-rhenium Alloys

    SciTech Connect

    Mueller, A.J.; Bianco, R.; Buckman, R.W. Jr.

    1999-10-22

    Oxide dispersion strengthened (ODS) molybdenum alloys being developed for high temperature applications possess excellent high temperature strength and creep resistance. In addition they exhibit a ductile-to-brittle transition temperature (DBIT) in the worked and stress-relieved condition under longitudinal tensile load well below room temperature. However, in the recrystallized condition, the DBTT maybe near or above room temperature, depending on the volume fraction of oxide dispersion and the amount of prior work. Dilute rhenium additions (7 and 14 wt.%) to ODS molybdenum were evaluated to determine their effect on low temperature ductility. The addition of 7 wt.% rhenium to the ODS molybdenum did not significantly enhance the mechanical properties. However, the addition of 14 wt.% rhenium to the ODS molybdenum resulted in a DBTT well below room temperature in both the stress-relieved and recrystallized condition. Additionally, the tensile strength of ODS Mo-14Re is greater than the base ODS molybdenum at 1,000 to 1,250 C.

  15. Kinetics of Molybdenum Reduction to Molybdenum Blue by Bacillus sp. Strain A.rzi

    PubMed Central

    Othman, A. R.; Bakar, N. A.; Halmi, M. I. E.; Johari, W. L. W.; Ahmad, S. A.; Jirangon, H.; Syed, M. A.; Shukor, M. Y.

    2013-01-01

    Molybdenum is very toxic to agricultural animals. Mo-reducing bacterium can be used to immobilize soluble molybdenum to insoluble forms, reducing its toxicity in the process. In this work the isolation of a novel molybdate-reducing Gram positive bacterium tentatively identified as Bacillus sp. strain A.rzi from a metal-contaminated soil is reported. The cellular reduction of molybdate to molybdenum blue occurred optimally at 4 mM phosphate, using 1% (w/v) glucose, 50 mM molybdate, between 28 and 30°C and at pH 7.3. The spectrum of the Mo-blue product showed a maximum peak at 865 nm and a shoulder at 700 nm. Inhibitors of bacterial electron transport system (ETS) such as rotenone, sodium azide, antimycin A, and potassium cyanide could not inhibit the molybdenum-reducing activity. At 0.1 mM, mercury, copper, cadmium, arsenic, lead, chromium, cobalt, and zinc showed strong inhibition on molybdate reduction by crude enzyme. The best model that fitted the experimental data well was Luong followed by Haldane and Monod. The calculated value for Luong's constants pmax, Ks, Sm, and n was 5.88 μmole Mo-blue hr−1, 70.36 mM, 108.22 mM, and 0.74, respectively. The characteristics of this bacterium make it an ideal tool for bioremediation of molybdenum pollution. PMID:24369531

  16. Kinetics of molybdenum reduction to molybdenum blue by Bacillus sp. strain A.rzi.

    PubMed

    Othman, A R; Bakar, N A; Halmi, M I E; Johari, W L W; Ahmad, S A; Jirangon, H; Syed, M A; Shukor, M Y

    2013-01-01

    Molybdenum is very toxic to agricultural animals. Mo-reducing bacterium can be used to immobilize soluble molybdenum to insoluble forms, reducing its toxicity in the process. In this work the isolation of a novel molybdate-reducing Gram positive bacterium tentatively identified as Bacillus sp. strain A.rzi from a metal-contaminated soil is reported. The cellular reduction of molybdate to molybdenum blue occurred optimally at 4 mM phosphate, using 1% (w/v) glucose, 50 mM molybdate, between 28 and 30 °C and at pH 7.3. The spectrum of the Mo-blue product showed a maximum peak at 865 nm and a shoulder at 700 nm. Inhibitors of bacterial electron transport system (ETS) such as rotenone, sodium azide, antimycin A, and potassium cyanide could not inhibit the molybdenum-reducing activity. At 0.1 mM, mercury, copper, cadmium, arsenic, lead, chromium, cobalt, and zinc showed strong inhibition on molybdate reduction by crude enzyme. The best model that fitted the experimental data well was Luong followed by Haldane and Monod. The calculated value for Luong's constants p max, K(s), S(m), and n was 5.88 μmole Mo-blue hr(-1), 70.36 mM, 108.22 mM, and 0.74, respectively. The characteristics of this bacterium make it an ideal tool for bioremediation of molybdenum pollution.

  17. Benchmark experiment for the cross section of the 100Mo(p,2n)99mTc and 100Mo(p,pn)99Mo reactions

    NASA Astrophysics Data System (ADS)

    Takács, S.; Ditrói, F.; Aikawa, M.; Haba, H.; Otuka, N.

    2016-05-01

    As nuclear medicine community has shown an increasing interest in accelerator produced 99mTc radionuclide, the possible alternative direct production routes for producing 99mTc were investigated intensively. One of these accelerator production routes is based on the 100Mo(p,2n)99mTc reaction. The cross section of this nuclear reaction was studied by several laboratories earlier but the available data-sets are not in good agreement. For large scale accelerator production of 99mTc based on the 100Mo(p,2n)99mTc reaction, a well-defined excitation function is required to optimise the production process effectively. One of our recent publications pointed out that most of the available experimental excitation functions for the 100Mo(p,2n)99mTc reaction have the same general shape while their amplitudes are different. To confirm the proper amplitude of the excitation function, results of three independent experiments were presented (Takács et al., 2015). In this work we present results of a thick target count rate measurement of the Eγ = 140.5 keV gamma-line from molybdenum irradiated by Ep = 17.9 MeV proton beam, as an integral benchmark experiment, to prove the cross section data reported for the 100Mo(p,2n)99mTc and 100Mo(p,pn)99Mo reactions in Takács et al. (2015).

  18. Laser-assisted growth of molybdenum rods

    NASA Astrophysics Data System (ADS)

    Björklund, K. L.; Heszler, P.; Boman, M.

    2002-01-01

    In this paper, we report for the first time the laser-assisted growth of molybdenum rods via the H 2 reduction of MoF 6 with a focused Ar + laser beam as the heat source. By varying the gas composition, total pressure, and laser power rods with different morphologies were deposited on a tungsten wire. At low H 2/MoF 6 molar ratios crystal-like rods were obtained and at higher molar ratios the rods became dendrite-like. The activation energy for the process was determined to be 77±7 kJ mol -1 in the temperature range 705-840 K. The reaction order showed to be nearly 3 with respect to the hydrogen partial pressure and zero order with respect to the molybdenum hexafluoride partial pressure. Compositional and morphological characterisation were performed with scanning electron microscopy, energy dispersed X-ray spectroscopy and Auger electron spectroscopy.

  19. Reactively evaporated films of copper molybdenum sulfide

    NASA Technical Reports Server (NTRS)

    Chi, K. C.; Dillon, R. O.; Bunshah, R. F.; Alterovitz, S.; Woollam, J. A.

    1978-01-01

    Films of superconducting Chevrel-phase copper molybdenum sulfide CuxMo6S8 were deposited on sapphire substrates by reactive evaporation using H2S as the reacting gas. Two superconducting temperatures (10.0 K and 5.0 K) of the films were found, corresponding to two different phases with different copper concentrations. All films were superconducting above 4.2 K and contained Chevrel-phase compound as well as free molybdenum. The critical current was measured as a function of applied field. One sample was found to deviate from the scaling law found for co-evaporated or sputtered samples, which possibly indicates a different pinning mechanism or inhomogeneity of the sample.

  20. Critical currents in sputtered copper molybdenum sulphide

    NASA Technical Reports Server (NTRS)

    Alterovitz, S. A.; Woollam, J. A.; Kammerdiner, L.; Luo, H.-L.

    1977-01-01

    Critical currents in a sputtered Chevrel-phase copper molybdenum sulfide have been measured at 4.2 K as a function of applied magnetic field. Self-field critical-current values up to 10 to the 9th A/sq m were found, decreasing to 10 to the 8th A/sq m at 3 T. Graphs of pinning forces versus field were found to be independent of field direction, and the pinning mechanism is sample independent. Critical-current densities for sputtered lead molybdenum sulphide are estimated to be about 10 to the 8th A/sq m at 26 T based on a scaling law for pinning.

  1. A clock reaction based on molybdenum blue.

    PubMed

    Neuenschwander, Ulrich; Negron, Arnaldo; Jensen, Klavs F

    2013-05-30

    Clock reactions are rare kinetic phenomena, so far limited mostly to systems with ionic oxoacids and oxoanions in water. We report a new clock reaction in cyclohexanol that forms molybdenum blue from a noncharged, yellow molybdenum complex as precursor, in the presence of hydrogen peroxide. Interestingly, the concomitant color change is reversible, enabling multiple clock cycles to be executed consecutively. The kinetics of the clock reaction were experimentally characterized, and by adding insights from quantum chemical calculations, a plausible reaction mechanism was postulated. Key elementary reaction steps comprise sigmatropic rearrangements with five-membered or bicyclo[3.1.0] transition states. Importantly, numerical kinetic modeling demonstrated the mechanism's ability to reproduce the experimental findings. It also revealed that clock behavior is intimately connected to the sudden exhaustion of hydrogen peroxide. Due to the stoichiometric coproduction of ketone, the reaction bears potential for application in alcohol oxidation catalysis.

  2. Molybdenum Sound Velocity and Shear Strength Softening

    NASA Astrophysics Data System (ADS)

    Nguyen, Jeffrey; Akin, Minta; Chau, Ricky; Fratandouno, Dayne; Ambrose, Pat; Fat'yanov, Oleg; Asimow, Paul; Holmes, Neil

    2013-06-01

    We recently carried out a series of light-gas gun experiments to measure molybdenum acoustic sound speed up to 5 Mbars on the Hugoniot. Our measured sound speeds increase linearly with pressure up to 2.6 Mbars and taper off near the melting pressure. The gradual leveling off of sound speed suggests a possible loss of shear strength near the melt. A linear extrapolation of our data to zero pressure is in good agreement with the sound speed measured at ambient condition. The results indicate that molybdenum remains in the bcc phase on the Hugoniot up to the melting pressure. There is no bcc solid phase transition on the Hugoniot as previously reported. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  3. The alkaline earth intercalates of molybdenum disulfide

    NASA Technical Reports Server (NTRS)

    Somoano, R. B.; Hadek, V.; Rembaum, A.; Samson, S.; Woollam, J. A.

    1975-01-01

    Molybdenum disulfide has been intercalated with calcium and strontium by means of the liquid ammonia technique. Chemical, X-ray, and superconductivity data are presented. The X-ray data reveal a lowering of crystal symmetry and increase of complexity of the structure upon intercalation with the alkaline earth metals. The Ca and Sr intercalates start to superconduct at 4 and 5.6 K, respectively, and show considerable anisotropy regarding the critical magnetic field.

  4. Method for welding chromium molybdenum steels

    SciTech Connect

    Sikka, V.K.

    1986-09-16

    A process is described for welding chromium-molybdenum steels which consist of: subjecting the steel to normalization by heating to above the transformation temperature and cooling in air; subjecting the steel to a partial temper by heating to a temperature less than a full temper; welding the steel using an appropriate filler metal; subjecting the steel to a full temper by heating to a temperature sufficient to optimize strength, reduce stress, increase ductility and reduce hardness.

  5. A solvent extraction study of molybdenum chloride and molybdenum thiocyanate complexes

    USGS Publications Warehouse

    Greenland, L.P.; Lillie, E.G.

    1974-01-01

    The effect of reducing agents on molybdenum(VI) solutions in hydrochloric acid was studied by a solvent extraction technique to elucidate the composition of the colored molybdenum thiocyanate complex. Neither copper(I) chloride nor ascorbic acid have any effect on the extraction of MoO2Cl2; it is inferred that tin(II) chloride reduces Mo(VI) stepwise to a polynuclear Mo(V)??Mo(VI) complex and then to Mo(V). The colored thiocyanate complex produced by copper(I) and by ascorbic acid differs only slightly in extraction characteristics from the uncolored Mo(VI) complex. It is suggested that the color may be produced by an isomerization reaction of MoO2(SCN)2, and thus that the colored species may be a hexavalent rather than pentavalent molybdenum complex. ?? 1974.

  6. STS-99 Crew Insignia

    NASA Technical Reports Server (NTRS)

    1999-01-01

    The STS-99 crew members designed the flight insignia for the Shuttle Radar Topography Mission (SRTM), the most ambitious Earth mapping mission to date. Two radar anternas, one located in the Shuttle bay and the other located on the end of a 60-meter deployable mast, was used during the mission to map Earth's features. The goal was to provide a 3-dimensional topographic map of the world's surface up to the Arctic and Antarctic Circles. In the patch, the clear portion of Earth illustrates the radar beams penetrating its cloudy atmosphere and the unique understanding of the home planet that is provided by space travel. The grid on Earth reflects the mapping character of the SRTM mission. The patch depicts the Space Shuttle Endeavour orbiting Earth in a star spangled universe. The rainbow along Earth's horizon resembles an orbital sunrise. The crew deems the bright colors of the rainbow as symbolic of the bright future ahead because of human beings' venturing into space. The crew of six launched aboard the Space Shuttle Endeavor on February 11, 2000 and completed 222 hours of around the clock radar mapping gathering enough information to fill more than 20,000 CDs.

  7. Spectrophotometric determination of molybdenum in rocks with thiocyanate

    USGS Publications Warehouse

    Lillie, E.G.; Greenland, L.P.

    1974-01-01

    A rapid procedure for the determination of microgram amounts of molybdenum in rocks is described. After acid decomposition, molybdenum is extracted from a hydrochloric acid solution into xylene with tributyl phosphate. After back-extraction with water, molybdenum is extracted as the ??-benzoinoximate into chloroform, stripped into hydrochloric acid extracted as the thiocyanate into amyl alcohol, and determined spectrophotometrically. The molybdenum thiocyanate color produced is stable, sensitive, and reproducible. Results of analyses of several of the U.S. Geological Survey standard rocks are given. ?? 1974.

  8. Recovery of tungsten and molybdenum from sulfur--bearing material

    SciTech Connect

    Ritsko, J. E.; Acia, H. L.

    1984-11-13

    Tungsten and molybdenum are recovered from sulfur bearing material such as sulfide sludges by a pollution free process in which the sulfur bearing material is heated with agitation in an aqueous solution of sodium carbonate to form water soluble molybdenum and tungsten compounds without forming any appreciable amount of water soluble sulfur compounds. The reaction mixture is oxidized to convert partially reduced tungsten values or molybdenum values to sodium tungstate and sodium molybdate respectively. The liquid phase containing tungsten and molybdenum is separated from the solid phase containing free sulfur.

  9. Sequential biological process for molybdenum extraction from hydrodesulphurization spent catalyst.

    PubMed

    Vyas, Shruti; Ting, Yen-Peng

    2016-10-01

    Spent catalyst bioleaching with Acidithiobacillus ferrooxidans has been widely studied and low Mo leaching has often been reported. This work describes an enhanced extraction of Mo via a two stage sequential process for the bioleaching of hydrodesulphurization spent catalyst containing Molybdenum, Nickel and, Aluminium. In the first stage, two-step bioleaching was performed using Acidithiobacillus ferrooxidans, and achieved 89.4% Ni, 20.9% Mo and 12.7% Al extraction in 15 days. To increase Mo extraction, the bioleached catalyst was subjected to a second stage bioleaching using Escherichia coli, during which 99% of the remaining Mo was extracted in 25 days. This sequential bioleaching strategy selectively extracted Ni in the first stage and Mo in the second stage, and is a more environmentally friendly alternative to sequential chemical leaching with alkaline reagents for improved Mo extraction. Kinetic modelling to establish the rate determining step in both stages of bioleaching showed that in the first stage, Mo extraction was chemical reaction controlled whereas in the subsequent stage, product layer diffusion model provided the best fit.

  10. Analytical electron microscopy of aluminum ion-implanted with molybdenum

    SciTech Connect

    Stephenson, L.D.; Bentley, J.; Benson, R.B. Jr.; Parrish, P.A.

    1983-01-01

    The microstructures of aluminum ion-implanted with molybdenum and subjected to various heat treatments were investigated for correlation with near-surface properties such as corrosion. Previous work indicated enhanced corrosion resistance, but dealt chiefly with the as-implanted condition and involved little microstructural characterization. In addition, the Al-Mo binary system is of interest because metastable phase formation was considered to be possible and the equilibrium phase diagram is poorly defined. Electropolished coupons 38 x 28 x 0.5 mm of 99.999% Al with approx.0.5 mm grain size were implanted with Mo/sup +/ ions at the Naval Research Laboratory. The dual energy implant schedule of 4.88 x 10/sup 19/ ions/m/sup 2/ at 50 keV plus 6.14 x 10/sup 19/ ions/m/sup 2/ at 110 keV resulted in a peak concentration of 4.4 at. % Mo (measured by ion backscattering) within the projected range of approx.50 nm. Results of the studies are presented.

  11. Selective cleavage of pepsin by molybdenum metallopeptidase

    SciTech Connect

    Yenjai, Sudarat; Malaikaew, Pinpinat; Liwporncharoenvong, Teerayuth; Buranaprapuk, Apinya

    2012-03-02

    Graphical abstract: Molybdenum metallopeptidase: the Mo(VI) cluster with six molybdenum cations has the ability to cleave protein under mild conditions (37 Degree-Sign C, pH 7) without reducing agents. The reaction required only low concentration of ammonium heptamolybdatetetrahydrate ((NH{sub 4}){sub 6}Mo{sub 7}O{sub 24}{center_dot}4H{sub 2}O) (0.125 mM). The reaction undergoes possibly via a hydrolytic mechanism. This is the first demonstration of protein cleavage by a molybdenum cluster. Highlights: Black-Right-Pointing-Pointer This is the first demonstration of protein cleavage by a Mo(VI) cluster with six molybdenum cations. Black-Right-Pointing-Pointer The cleavage reaction undergoes at mild conditions. Black-Right-Pointing-Pointer No need of reducing agents. Black-Right-Pointing-Pointer Only low concentration of Mo(VI) cluster and short time of incubation are needed. -- Abstract: In this study, the cleavage of protein by molybdenum cluster is reported for the first time. The protein target used is porcine pepsin. The data presented in this study show that pepsin is cleaved to at least three fragments with molecular weights of {approx}23, {approx}19 and {approx}16 kDa when the mixture of the protein and ammonium heptamolybdate tetrahydrate ((NH{sub 4}){sub 6}Mo{sub 7}O{sub 24}{center_dot}4H{sub 2}O) was incubated at 37 Degree-Sign C for 24 h. No self cleavage of pepsin occurs at 37 Degree-Sign C, 24 h indicating that the reaction is mediated by the metal ions. N-terminal sequencing of the peptide fragments indicated three cleavage sites of pepsin between Leu 112-Tyr 113, Leu 166-Leu 167 and Leu 178-Asn 179. The cleavage reaction occurs after incubation of the mixture of pepsin and (NH{sub 4}){sub 6}Mo{sub 7}O{sub 24}{center_dot}4H{sub 2}O) only for 2 h. However, the specificity of the cleavage decreases when incubation time is longer than 48 h. The mechanism for cleavage of pepsin is expected to be hydrolytic chemistry of the amide bonds in the protein

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

    PubMed

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

    2014-07-01

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

  13. Selective recovery of molybdenum from spent HDS catalyst using oxidative soda ash leach/carbon adsorption method.

    PubMed

    Park, Kyung Ho; Mohapatra, D; Reddy, B Ramachandra

    2006-11-16

    The petroleum refining industry makes extensive use of hydroprocessing catalysts. These catalysts contain environmentally critical and economically valuable metals such as Mo, V, Ni and Co. In the present study, a simple hydrometallurgical processing of spent hydrodesulphurization (HDS) catalyst for the recovery of molybdenum using sodium carbonate and hydrogen peroxide mixture was investigated. Recovery of molybdenum was largely dependent on the concentrations of Na2CO3 and H2O2 in the reaction medium, which in turn controls the pH of leach liquor and the presence of Al and Ni as impurities. Under the optimum leaching conditions (40 g L(-1) Na2CO3, 6 vol.% H2O2, room temperature, 1h) about 85% recovery of Mo was achieved. The leach liquor was processed by the carbon adsorption method, which selectively adsorbs Mo at pH around 0.75. Desorption of Mo was selective at 15 vol.% NH4OH. With a single stage contact, it was found possible to achieve >99%, adsorption and desorption efficiency. Using this method, recovery of molybdenum as MoO3 product of 99.4% purity was achieved.

  14. Extraction and determination of molybdenum with tributyl phosphate Application to analysis of copper-molybdenum ores.

    PubMed

    Caiozzi, M; Zunino, H; Sepúlveda, L

    1969-12-01

    A differential spectrophotometric method is described for the determination of molybdenum by means of solvent extraction with tributylphosphate of the peroxymolybdate complex formed with H(2)O(2) in 3.5N H(2)SO(4). The extraction parameters are studied, and the behaviour of some other ions is reported. The method is used for ore analysis.

  15. Molybdenum limitation of asymbiotic nitrogen fixation in tropical forest soils

    NASA Astrophysics Data System (ADS)

    Barron, Alexander R.; Wurzburger, Nina; Bellenger, Jean Phillipe; Wright, S. Joseph; Kraepiel, Anne M. L.; Hedin, Lars O.

    2009-01-01

    Nitrogen fixation, the biological conversion of di-nitrogen to plant-available ammonium, is the primary natural input of nitrogen to ecosystems, and influences plant growth and carbon exchange at local to global scales. The role of this process in tropical forests is of particular concern, as these ecosystems harbour abundant nitrogen-fixing organisms and represent one third of terrestrial primary production. Here we show that the micronutrient molybdenum, a cofactor in the nitrogen-fixing enzyme nitrogenase, limits nitrogen fixation by free-living heterotrophic bacteria in soils of lowland Panamanian forests. We measured the fixation response to long-term nutrient manipulations in intact forests, and to short-term manipulations in soil microcosms. Nitrogen fixation increased sharply in treatments of molybdenum alone, in micronutrient treatments that included molybdenum by design and in treatments with commercial phosphorus fertilizer, in which molybdenum was a `hidden' contaminant. Fixation did not respond to additions of phosphorus that were not contaminated by molybdenum. Our findings show that molybdenum alone can limit asymbiotic nitrogen fixation in tropical forests and raise new questions about the role of molybdenum and phosphorus in the tropical nitrogen cycle. We suggest that molybdenum limitation may be common in highly weathered acidic soils, and may constrain the ability of some forests to acquire new nitrogen in response to CO2 fertilization.

  16. Structural state of native molybdenum in the lunar regolith

    NASA Astrophysics Data System (ADS)

    Mokhov, A. V.; Gornostaeva, T. A.; Kartashov, P. M.; Bogatikov, O. A.; Sakharov, O. A.; Trubkin, N. V.

    2016-11-01

    The structural state was determined for zero-valence molybdenum in the lunar regolith. The body- and face-centered molybdenum forms (BCC and FCC, respectively) were identified. Disruption of the structure down to complete amorphization was noted. This might be caused by the long-term influence of the solar wind.

  17. Normal state properties of the ternary molybdenum sulfides

    NASA Technical Reports Server (NTRS)

    Woollam, J. A.; Alterovitz, S. A.

    1978-01-01

    By making a large number of normal state and superconducting properties measurements, all on the same ternary molybdenum sulfide samples, we obtain values for Fermi surface and superconducting parameters. From these we conclude that sputtered ternary molybdenum sulfides are not completely in the dirty superconductor limit, and that they are d-band metals with a high electron carrier density.

  18. Predicting Boron, Molybdenum, Selenium, and Arsenic Adsorption in Soil Systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A chemical surface complexation model was applied to boron, molybdenum, selenium, and arsenic adsorption on up to 49 soils selected for variation in soil properties. The surface complexation model was able to fit boron, molybdenum, selenite, and arsenate adsorption on the soils. General regression...

  19. Influence of Soil Solution Salinity on Molybdenum Adsorption by Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Molybdenum (Mo) adsorption on five arid-zone soils from California was investigated as a function of equilibrium solution Mo concentration (0-30 mg L-1), solution pH (4-8), and electrical conductivity (EC = 0.3 or 8 dS m-1). Molybdenum adsorption decreased with increasing pH. An adsorption maximum...

  20. Molybdenum In Cathodes Of Sodium/Metal Chloride Cells

    NASA Technical Reports Server (NTRS)

    Bugga, Ratnakumar V.; Attia, Alan I.; Halpert, Gerald

    1992-01-01

    Cyclic voltammetric curves of molybdenum wire in NaAlCl4 melt indicate molybdenum chloride useful as cathode material in rechargeable sodium/metal chloride electrochemical cells. Batteries used in electric vehicles, for electric-power load leveling, and other applications involving high energy and power densities.

  1. Molybdenum blue: binding to collagen fibres and microcrystal formation.

    PubMed

    Harris, J Robin; Reiber, Andreas; Therese, Helen Annal; Tremel, Wolfgang

    2005-01-01

    Collagen fibres have been shown by transmission electron microscopy to progressively bind the polyoxomolybdate ring-complex, termed molybdenum blue. Nucleation of cuboidal molybdenum blue microcrystals occurs on the surface of the collagen fibres, leading eventually to extensive coating of the fibres with microcrystals.

  2. Processing of a Mullite Matrix, Molybdenum Disilicide Reinforced Composite

    DTIC Science & Technology

    1991-01-01

    NWW 1/22/92 II University of Washington Abstract Processing of a Mullite Matrix, Molybdenum Disilicide Reinforced Composite for Potential High...39 2.5 Mullite Compcsites .................................... 43 2.6 Molybdenum Disilicide ...44 2.7 Testing of Mechanical Properties of Ceramics .. *................. 47 2.8 Strength

  3. Molybdenum enhanced low-temperature deposition of crystalline silicon nitride

    DOEpatents

    Lowden, Richard A.

    1994-01-01

    A process for chemical vapor deposition of crystalline silicon nitride which comprises the steps of: introducing a mixture of a silicon source, a molybdenum source, a nitrogen source, and a hydrogen source into a vessel containing a suitable substrate; and thermally decomposing the mixture to deposit onto the substrate a coating comprising crystalline silicon nitride containing a dispersion of molybdenum silicide.

  4. Molybdenum oxide nanocubes: Synthesis and characterizations

    NASA Astrophysics Data System (ADS)

    Muthamizh, S.; Suresh, R.; Giribabu, K.; Manigandan, R.; Kumar, S. Praveen; Munusamy, S.; Stephen, A.; Narayanan, V.

    2015-06-01

    Molybdenum oxide nanoparticles were prepared by Solid state synthesis. The MoO3 nanoparticles were synthesized by using commercially available ammonium heptamolybdate. The XRD pattern reveals that the synthesized MoO3 has orthorhombic structure. In addition, lattice parameter values were also calculated using XRD data. The Raman analysis confirm the presence of Mo-O in MoO3 nanoparticles. DRS-UV analysis shows that MoO3 has a band gap of 2.89 eV. FE-SEM analysis confirms the material morphology in cubes with nano scale.

  5. Molybdenum oxide nanocubes: Synthesis and characterizations

    SciTech Connect

    Muthamizh, S.; Suresh, R.; Giribabu, K.; Manigandan, R.; Kumar, S. Praveen; Munusamy, S.; Narayanan, V.; Stephen, A.

    2015-06-24

    Molybdenum oxide nanoparticles were prepared by Solid state synthesis. The MoO{sub 3} nanoparticles were synthesized by using commercially available ammonium heptamolybdate. The XRD pattern reveals that the synthesized MoO{sub 3} has orthorhombic structure. In addition, lattice parameter values were also calculated using XRD data. The Raman analysis confirm the presence of Mo-O in MoO{sub 3} nanoparticles. DRS-UV analysis shows that MoO{sub 3} has a band gap of 2.89 eV. FE-SEM analysis confirms the material morphology in cubes with nano scale.

  6. Hot rolling of thick uranium molybdenum alloys

    DOEpatents

    DeMint, Amy L.; Gooch, Jack G.

    2015-11-17

    Disclosed herein are processes for hot rolling billets of uranium that have been alloyed with about ten weight percent molybdenum to produce cold-rollable sheets that are about one hundred mils thick. In certain embodiments, the billets have a thickness of about 7/8 inch or greater. Disclosed processes typically involve a rolling schedule that includes a light rolling pass and at least one medium rolling pass. Processes may also include reheating the rolling stock and using one or more heavy rolling passes, and may include an annealing step.

  7. Biennial Report, 1997-99.

    ERIC Educational Resources Information Center

    Wisconsin Technical Coll. System Board, Madison.

    This report describes the 1997-99 biennium activities of the Wisconsin Technical College System (WTCS) Board. Part 1 provides an Agency Overview. Details are given on mission and purpose, cooperative relationships, the State Board, the State Board Staff, and WTCS Districts. Part 2 explores the 1997-99 Budget and Policy Actions. It discusses the…

  8. Biosynthesis of the iron-molybdenum cofactor and the molybdenum cofactor in Klebsiella pneumoniae: effect of sulfur source

    SciTech Connect

    Ugalde, R.A.; Imperial, J.; Shah, V.K.; Brill, W.J.

    1985-12-01

    NifQ/sup -/ and Mol/sup -/ mutants of Klebsiella pneumoniae show an elevated molybdenum requirement for nitrogen fixation. Substitution of cystine for sulfate as the sulfur source in the medium reduced the molybdenum requirement of these mutants to levels required by the wild type. Cystine also increased the intracellular molybdenum accumulation of NifQ/sup -/ and Mol/sup -/ mutants. Cystine did not affect the molybdenum requirement or accumulation in wild-type K. pneumoniae. Sulfate transport and metabolism in K. pneumoniae were repressed by cystine. However, the effect of cystine on the molybdenum requirement could not be explained by an interaction between sulfate and molybdate at the transport level. The data show that cystine does not have a generalized effect on molybdenum metabolism. Millimolar concentrations of molybdate inhibited nitrogenase and nitrate reductase derepression with sulfate as the sulfur source, but not with cystine. The inhibition was the result of a specific antagonism of sulfate metabolism by molybdate. This study suggests that a sulfur donor and molybdenum interact at an early step in the biosynthesis of the iron-molybdenum cofactor. This interaction might occur nonenzymatically when the levels of the reactants are high.

  9. Segregation of carbon in iron and molybdenum

    NASA Astrophysics Data System (ADS)

    Arabczyk, W.; Narkiewicz, U.

    1996-05-01

    The segregation of nitrogen, phosphorus, sulphur and carbon in iron causes the formation of FeXX bonds on the surface. The system metal (Fe(111),Mo(100))-carbon has been studied using the AES method. The bonds FeC observed for lower surface coverages were transformed to FeCC bonds for higher coverages and the interaction between iron atoms and carbon atoms decreased. In the case of molybdenum the two different adsorption states were observed without a formation of CC bonding. The enthalpy of segregation for both adsorption states for iron and molybdenum has been determined using the Langmuir-McLean equation. The enthalpy of carbon segregation at the first adsorption state (lower carbon coverages) was - 140 and - 68 kJ/mol for Fe(111) and Mo(100) surfaces, respectively, and for the second adsorption state - 60 and - 47 kJ/mol, respectively. The further increase of the carbon surface concentration caused the formation of 3D graphite on the Fe(111) surface and of carbide-like compounds on the Mo(100) surface.

  10. Boron modified molybdenum silicide and products

    DOEpatents

    Meyer, M.K.; Akinc, M.

    1999-02-02

    A boron-modified molybdenum silicide material is disclosed having the composition comprising about 80 to about 90 weight % Mo, about 10 to about 20 weight % Si, and about 0.1 to about 2 weight % B and a multiphase microstructure including Mo{sub 5}Si{sub 3} phase as at least one microstructural component effective to impart good high temperature creep resistance. The boron-modified molybdenum silicide material is fabricated into such products as electrical components, such as resistors and interconnects, that exhibit oxidation resistance to withstand high temperatures in service in air as a result of electrical power dissipation, electrical resistance heating elements that can withstand high temperatures in service in air and other oxygen-bearing atmospheres and can span greater distances than MoSi{sub 2} heating elements due to improved creep resistance, and high temperature structural members and other fabricated components that can withstand high temperatures in service in air or other oxygen-bearing atmospheres while retaining creep resistance associated with Mo{sub 5}Si{sub 3} for structural integrity. 7 figs.

  11. Boron modified molybdenum silicide and products

    DOEpatents

    Meyer, Mitchell K.; Akinc, Mufit

    1999-02-02

    A boron-modified molybdenum silicide material having the composition comprising about 80 to about 90 weight % Mo, about 10 to about 20 weight % Si, and about 0.1 to about 2 weight % B and a multiphase microstructure including Mo.sub.5 Si.sub.3 phase as at least one microstructural component effective to impart good high temperature creep resistance. The boron-modified molybdenum silicide material is fabricated into such products as electrical components, such as resistors and interconnects, that exhibit oxidation resistance to withstand high temperatures in service in air as a result of electrical power dissipation, electrical resistance heating elements that can withstand high temperatures in service in air and other oxygen-bearing atmospheres and can span greater distances than MoSi.sub.2 heating elements due to improved creep resistance, and high temperature structural members and other fabricated components that can withstand high temperatures in service in air or other oxygen-bearing atmospheres while retaining creep resistance associated with Mo.sub.5 Si.sub.3 for structural integrity.

  12. Climax-Type Porphyry Molybdenum Deposits

    USGS Publications Warehouse

    Ludington, Steve; Plumlee, Geoffrey S.

    2009-01-01

    Climax-type porphyry molybdenum deposits, as defined here, are extremely rare; thirteen deposits are known, all in western North America and ranging in age from Late Cretaceous to mainly Tertiary. They are consistently found in a postsubduction, extensional tectonic setting and are invariably associated with A-type granites that formed after peak activity of a magmatic cycle. The deposits consist of ore shells of quartz-molybdenite stockwork veins that lie above and surrounding the apices of cupola-like, highly evolved, calc-alkaline granite and subvolcanic rhyolite-porphyry bodies. These plutons are invariably enriched in fluorine (commonly >1 percent), rubidium (commonly >500 parts per million), and niobium-tantalum (Nb commonly >50 parts per million). The deposits are relatively high grade (typically 0.1-0.3 percent Mo) and may be very large (typically 100-1,000 million tons). Molybdenum, as MoS2, is the primary commodity in all known deposits. The effect on surface-water quality owing to natural influx of water or sediment from a Climax-type mineralized area can extend many kilometers downstream from the mineralized area. Waste piles composed of quartz-silica-pyrite altered rocks will likely produce acidic drainage waters. The potential exists for concentrations of fluorine or rare metals in surface water and groundwater to exceed recommended limits for human consumption near both mined and unmined Climax-type deposits.

  13. Facile and novel synthetic method to prepare nano molybdenum and its catalytic activity.

    PubMed

    Sam Jaikumar, Sugumaran; Yuvakkumar, Rathinam; Suriya Prabha, Rangaraj; Karunakaran, Gopalu; Rajendran, Venkatachalam; Hong, Sun Ig

    2015-08-01

    This study reports on a facile and economical synthetic method to prepare nano molybdenum by solid-state reaction technique. Metallic nano molybdenum was synthesised from molybdenum trioxide, molybdenum IV oxide and molybdenum VI oxide through thermal decomposition technique. Metallic nano molybdenum prepared from molybdenum IV oxide was used to study the catalytic effect of molybdenum nanoparticles on the growth of Anabaena sp. The increase in concentration of nano molybdenum from 0.1 to 100% in BG11 (N⁻ Mo⁻ + nano Mo) medium increases heterocyst frequency. The chlorophyll and protein content in Anabaena sp. was found to improve when compared with bulk molybdenum particles and showed a positive influence to be used as a nano nutrient for Anabaena sp.

  14. Chill block melt spinning of nickel-molybdenum alloys

    NASA Technical Reports Server (NTRS)

    Hemker, Kevin J.; Glasgow, Thomas K.

    1987-01-01

    Samples of Ni-Mo alloys ranging in composition from pure nickel to Ni-40 at. pct molybdenum were cast by the chill block melt-spinning rapid solidification technique and examined by optical metallography, X-ray diffraction, and microhardness testing. Casting difficulties were encountered with lean alloys, but richer alloys spread more readily on the casting wheel. Alloy microstructures for 5 to 37.5 at. pct molybdenum ribbons were primarily cellular/dendritic; microstructure feature size decreased with increasing molybdenum content. Extended solubility of molybdenum in gamma-nickel, with fcc lattice parameter increasing with composition to the 1.05 power, was observed up to 37/5 at. pct molybdenum. Substoichiometric Ni-Mo (delta) nucleated on the wheel side of the ribbons of compositions 35, 37.5, and 40 at. pct molybdenum. The amount of partitionless delta-phase thus formed increased with increasing molybdenum content and quench rate. This substoichiometric delta transformed readily to a fine structure gamma-delta mixture.

  15. Atomic layer deposition of molybdenum oxide using bis(tert-butylimido)bis(dimethylamido) molybdenum

    SciTech Connect

    Bertuch, Adam Sundaram, Ganesh

    2014-01-15

    Molybdenum trioxide films have been deposited using thermal atomic layer deposition techniques with bis(tert-butylimido)bis(dimethylamido)molybdenum. Films were deposited at temperatures from 100 to 300 °C using ozone as the oxidant for the process. The Mo precursor was evaluated for thermal stability and volatility using thermogravimetric analysis and static vapor pressure measurements. Film properties were evaluated with ellipsometry, x-ray photoelectron spectroscopy, secondary ion mass spectroscopy, and secondary electron microscopy. The growth rate per cycle was determined to extend from 0.3 to 2.4 Å/cycle with <4% nonuniformity (1-sigma) with-in-wafer across a 150 mm wafer for the investigated temperature range.

  16. A solvent-extraction module for cyclotron production of high-purity technetium-99m.

    PubMed

    Martini, Petra; Boschi, Alessandra; Cicoria, Gianfranco; Uccelli, Licia; Pasquali, Micòl; Duatti, Adriano; Pupillo, Gaia; Marengo, Mario; Loriggiola, Massimo; Esposito, Juan

    2016-12-01

    The design and fabrication of a fully-automated, remotely controlled module for the extraction and purification of technetium-99m (Tc-99m), produced by proton bombardment of enriched Mo-100 molybdenum metallic targets in a low-energy medical cyclotron, is here described. After dissolution of the irradiated solid target in hydrogen peroxide, Tc-99m was obtained under the chemical form of (99m)TcO4(-), in high radionuclidic and radiochemical purity, by solvent extraction with methyl ethyl ketone (MEK). The extraction process was accomplished inside a glass column-shaped vial especially designed to allow for an easy automation of the whole procedure. Recovery yields were always >90% of the loaded activity. The final pertechnetate saline solution Na(99m)TcO4, purified using the automated module here described, is within the Pharmacopoeia quality control parameters and is therefore a valid alternative to generator-produced (99m)Tc. The resulting automated module is cost-effective and easily replicable for in-house production of high-purity Tc-99m by cyclotrons.

  17. Mechanical properties of oxide dispersion strengthened (ODS) molybdenum alloys

    SciTech Connect

    Bianco, R.; Buckman, R.W. Jr.

    1998-03-01

    Oxide dispersion strengthened molybdenum, Mo-ODS, developed by a proprietary powder metallurgy process, exhibits a creep rupture life at 0.65T{sub m} (1,600 C) of three to five orders of magnitude greater than unalloyed molybdenum, while maintaining ductile fracture behavior at temperatures significantly below room temperature. In comparison, the creep rupture life of the Mo-50Re solid solution strengthened alloy at 1,600 C is only an order of magnitude greater than unalloyed molybdenum. The results of microstructural characterization and thermal stability and mechanical property testing are discussed.

  18. Superconducting properties of evaporated copper molybdenum sulfide films

    NASA Technical Reports Server (NTRS)

    Woollam, J. A.; Chi, K. C.; Dillon, R. O.; Bunshah, R. F.; Alterovitz, S. A.

    1978-01-01

    Films of copper molybdenum sulfide were produced by coevaporation. Those that were superconducting contained only the ternary compound and free molybdenum. The range of copper content in the ternary compound was as large as that in polycrystalline material, that is, it includes either phase alone, or a mixture of the two phases of this material. This is in contrast with sputtered materials where copper concentration has been limited to a narrower range. The upper critical field and the critical current were measured as functions of external magnetic field, and found to be similar to those of sputtered copper molybdenum sulfide, when the comparison was made for samples having the same amount of copper.

  19. Pterin chemistry and its relationship to the molybdenum cofactor

    PubMed Central

    Basu, Partha; Burgmayer, Sharon J.N.

    2011-01-01

    The molybdenum cofactor is composed of a molybdenum coordinated by one or two rather complicated ligands known as either molybdopterin or pyranopterin. Pterin is one of a large family of bicyclic N-heterocycles called pteridines. Such molecules are widely found in Nature, having various forms to perform a variety of biological functions. This article describes the basic nomenclature of pterin, their biological roles, structure, chemical synthesis and redox reactivity. In addition, the biosynthesis of pterins and current models of the molybdenum cofactor are discussed. PMID:21607119

  20. Field method for the determination of molybdenum in plants

    USGS Publications Warehouse

    Reichen, Laura E.; Ward, F.N.

    1951-01-01

    Fresh plant material is ashed directly by heating in nickel or platinum dishes over a "flame. An acid solution of 25 milligrams of ash is treated with stannous chloride and potassium thiocyanate. The amber-colored molybdenum thiocyanate complex ion is extracted with isopropyl ether, and the intensity of the color of the ether layer over a sample solution is compared with the ether layer over standard molybdenum solutions treated similarly. Field determinations can be made quickly and the method requires no special equipment. As little as 0.25 microgram or 0.001 percent molybdenum can be determined in plant ash.

  1. The extended family of hexagonal molybdenum oxide

    SciTech Connect

    Hartl, Monika; Daemen, Luke; Lunk, J H; Hartl, H; Frisk, A T; Shendervich, I; Mauder, D; Feist, M; Eckelt, R

    2009-01-01

    Over the last 40 years, a large number of isostructural compounds in the system MoO{sub 3}-NH{sub 3}-H{sub 2}O have been published. The reported molecular formulae of 'hexagonal molybdenum oxide' (HEMO) varied from MoO{sub 3}, MoO{sub 3} {center_dot} 0.33NH{sub 3}, MoO{sub 3} {center_dot} nH{sub 2}O (0.09 {le} n {le} 0.69) to MoO{sub 3} {center_dot} mNH{sub 3} {center_dot} nH{sub 2}O (0.09 {le} m {le} 0.20; 0.18 {le} n {le} 0.60). Samples, prepared by the acidification route, were investigated using thermal analysis coupled on-line to a mass spectrometer for evolved gas analysis; X-ray powder diffraction; Fourier Transform Infrared, Raman and Magic-Angle-Spinning {sup 1}H-NMR spectroscopy; Incoherent Inelastic Neutron Scattering. The X-ray study of a selected monocrystal confirmed the presence of the well-known framework of edge-sharing MoO{sub 6} octahedra: Space group P6{sub 3}/m, a = 10.527(1), c =3.7245(7) {angstrom}, {gamma} = 120{sup o}. The structure of the synthesized samples can best be described by the structural formula (NH{sub 4})[Mo{sub x}{open_square}{sub 1/2+p/2}(O{sub 3x + 1/2-p/2})(OH){sub p}] {center_dot} yH{sub 2}O (x 5.9-7.1; p {approx} 0.1; y = 1.2-2.6), which is consistent with the existence of one vacancy for 12-15 molybdenum sites. The 'chimie douce' reaction of MoO{sub 3} {center_dot} 0.155NH{sub 3} {center_dot} 0.440H{sub 2}O with a 1:1 mixture of NO/NO{sub 2} at 100 C resulted in the synthesis of MoO{sub 3} {center_dot} 0.539H{sub 2}O. Tailored nano-sized molybdenum powders can be produced using HEMO as precursor.

  2. Amorphous molybdenum sulfides as hydrogen evolution catalysts.

    PubMed

    Morales-Guio, Carlos G; Hu, Xile

    2014-08-19

    Providing energy for a population projected to reach 9 billion people within the middle of this century is one of the most pressing societal issues. Burning fossil fuels at a rate and scale that satisfy our near-term demand will irreversibly damage the living environment. Among the various sources of alternative and CO2-emission-free energies, the sun is the only source that is capable of providing enough energy for the whole world. Sunlight energy, however, is intermittent and requires an efficient storage mechanism. Sunlight-driven water splitting to make hydrogen is widely considered as one of the most attractive methods for solar energy storage. Water splitting needs a hydrogen evolution catalyst to accelerate the rate of hydrogen production and to lower the energy loss in this process. Precious metals such as Pt are superior catalysts, but they are too expensive and scarce for large-scale applications. In this Account, we summarize our recent research on the preparation, characterization, and application of amorphous molybdenum sulfide catalysts for the hydrogen evolution reaction. The catalysts can be synthesized by electrochemical deposition under ambient conditions from readily available and inexpensive precursors. The catalytic activity is among the highest for nonprecious catalysts. For example, at a loading of 0.2 mg/cm(2), the optimal catalyst delivers a current density of 10 mA/cm(2) at an overpotential of 160 mV. The growth mechanism of the electrochemically deposited film catalysts was revealed by an electrochemical quartz microcrystal balance study. While different electrochemical deposition methods produce films with different initial compositions, the active catalysts are the same and are identified as a "MoS(2+x)" species. The activity of the film catalysts can be further promoted by divalent Fe, Co, and Ni ions, and the origins of the promotional effects have been probed. Highly active amorphous molybdenum sulfide particles can also be prepared

  3. Molybdenum enzymes, their maturation and molybdenum cofactor biosynthesis in Escherichia coli.

    PubMed

    Iobbi-Nivol, Chantal; Leimkühler, Silke

    2013-01-01

    Molybdenum cofactor (Moco) biosynthesis is an ancient, ubiquitous, and highly conserved pathway leading to the biochemical activation of molybdenum. Moco is the essential component of a group of redox enzymes, which are diverse in terms of their phylogenetic distribution and their architectures, both at the overall level and in their catalytic geometry. A wide variety of transformations are catalyzed by these enzymes at carbon, sulfur and nitrogen atoms, which include the transfer of an oxo group or two electrons to or from the substrate. More than 50 molybdoenzymes were identified in bacteria to date. In molybdoenzymes Mo is coordinated to a dithiolene group on the 6-alkyl side chain of a pterin called molybdopterin (MPT). The biosynthesis of Moco can be divided into four general steps in bacteria: 1) formation of the cyclic pyranopterin monophosphate, 2) formation of MPT, 3) insertion of molybdenum into molybdopterin to form Moco, and 4) additional modification of Moco with the attachment of GMP or CMP to the phosphate group of MPT, forming the dinucleotide variant of Moco. This review will focus on molybdoenzymes, the biosynthesis of Moco, and its incorporation into specific target proteins focusing on Escherichia coli. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems.

  4. Environmental behavior of two molybdenum porphyry systems

    USGS Publications Warehouse

    Tuttle, M.L.W.; Wanty, R.B.; Berger, B.R.

    2004-01-01

    Our study focuses on the geology, hydrology, and geochemistry of a variety of molybdenum (Mo) porphyry systems. The systems are either high fluorine, granite, Climax-type, systems (e.g. Mount Emmons/ Redwell Mo deposit, Colorado and Questa Mo deposit, New Mexico) or low fluorine granodiorite systems (e.g. Buckingham Stockwork Mo deposit, Battle Mountain, Nevada and Cannivan Gulch Mo deposit, Montana). The water quality of streams, natural springs, mine discharge, and ground water from drill holes were assessed in the region of these deposits. The ultimate goal of our study is to understand the environmental behavior of these Mo porphyry systems in the context of geologic setting, hydrologic regime, and climate.

  5. Measured oscillator strengths in singly ionized molybdenum

    NASA Astrophysics Data System (ADS)

    Mayo-García, R.; Aragón, C.; Aguilera, J. A.; Ortiz, M.

    2015-11-01

    In this article, 112 oscillator strengths from Mo II have been measured, 79 of which for the first time. The radiative parameters have been obtained by laser-induced breakdown spectroscopy (LIBS). The plasma is produced from a fused glass sample prepared from molybdenum oxide with a Mo atomic concentration of 0.1%. The plasma evolved in air at atmospheric pressure, and measurements were carried out with the following plasma parameters: an electron density of (2.5+/- 0.1)\\cdot {10}17 cm-3 and an electron temperature of 14,400+/- 200 K. In these conditions, a local thermodynamic equilibrium environment and an optically thin plasma were confirmed for the measurements. The relative intensities were placed on an absolute scale by combining branching fractions with the measured lifetimes and by comparing well-known lines using the plasma temperature. Comparisons were made to previously obtained experimental and theoretical values wherever possible.

  6. Nanomechanical cleavage of molybdenum disulphide atomic layers.

    PubMed

    Tang, Dai-Ming; Kvashnin, Dmitry G; Najmaei, Sina; Bando, Yoshio; Kimoto, Koji; Koskinen, Pekka; Ajayan, Pulickel M; Yakobson, Boris I; Sorokin, Pavel B; Lou, Jun; Golberg, Dmitri

    2014-04-03

    The discovery of two-dimensional materials became possible due to the mechanical cleavage technique. Despite its simplicity, the as-cleaved materials demonstrated surprising macro-continuity, high crystalline quality and extraordinary mechanical and electrical properties that triggered global research interest. Here such cleavage processes and associated mechanical behaviours are investigated by a direct in situ transmission electron microscopy probing technique, using atomically thin molybdenum disulphide layers as a model material. Our technique demonstrates layer number selective cleavage, from a monolayer to double layer and up to 23 atomic layers. In situ observations combined with molecular dynamics simulations reveal unique layer-dependent bending behaviours, from spontaneous rippling (<5 atomic layers) to homogeneous curving (~ 10 layers) and finally to kinking (20 or more layers), depending on the competition of strain energy and interfacial energy.

  7. Nanomechanical cleavage of molybdenum disulphide atomic layers

    NASA Astrophysics Data System (ADS)

    Tang, Dai-Ming; Kvashnin, Dmitry G.; Najmaei, Sina; Bando, Yoshio; Kimoto, Koji; Koskinen, Pekka; Ajayan, Pulickel M.; Yakobson, Boris I.; Sorokin, Pavel B.; Lou, Jun; Golberg, Dmitri

    2014-04-01

    The discovery of two-dimensional materials became possible due to the mechanical cleavage technique. Despite its simplicity, the as-cleaved materials demonstrated surprising macro-continuity, high crystalline quality and extraordinary mechanical and electrical properties that triggered global research interest. Here such cleavage processes and associated mechanical behaviours are investigated by a direct in situ transmission electron microscopy probing technique, using atomically thin molybdenum disulphide layers as a model material. Our technique demonstrates layer number selective cleavage, from a monolayer to double layer and up to 23 atomic layers. In situ observations combined with molecular dynamics simulations reveal unique layer-dependent bending behaviours, from spontaneous rippling (<5 atomic layers) to homogeneous curving (~ 10 layers) and finally to kinking (20 or more layers), depending on the competition of strain energy and interfacial energy.

  8. Advances in rechargeable lithium molybdenum disulfide batteries

    NASA Technical Reports Server (NTRS)

    Brandt, K.; Stiles, J. A. R.

    1985-01-01

    The lithium molybdenum disulfide system as demonstrated in a C size cell, offers performance characteristics for applications where light weight and low volume are important. A gravimetric energy density of 90 watt hours per kilogram can be achieved in a C size cell package. The combination of charge retention capabilities, high energy density and a state of charge indicator in a rechargeable cell provides power package for a wide range of devices. The system overcomes the memory effect in Nicads where the full capacity of the battery cannot be utilized unless it was utilized on previous cycles. The development of cells with an advanced electrolyte formulation led to an improved rate capability especially at low temperatures and to a significantly improved life cycle.

  9. Ultrafast response of monolayer molybdenum disulfide photodetectors

    PubMed Central

    Wang, Haining; Zhang, Changjian; Chan, Weimin; Tiwari, Sandip; Rana, Farhan

    2015-01-01

    The strong light emission and absorption exhibited by single atomic layer transitional metal dichalcogenides in the visible to near-infrared wavelength range make them attractive for optoelectronic applications. In this work, using two-pulse photovoltage correlation technique, we show that monolayer molybdenum disulfide photodetector can have intrinsic response times as short as 3 ps implying photodetection bandwidths as wide as 300 GHz. The fast photodetector response is a result of the short electron–hole and exciton lifetimes in this material. Recombination of photoexcited carriers in most two-dimensional metal dichalcogenides is dominated by nonradiative processes, most notable among which is Auger scattering. The fast response time, and the ease of fabrication of these devices, make them interesting for low-cost ultrafast optical communication links. PMID:26572726

  10. Hole injection in tri-arylamine containing polyfluorene co-polymer devices with molybdenum oxide contacts

    NASA Astrophysics Data System (ADS)

    Buckley, Alastair; Pickup, David; Yates, Chris; Zhao, Yi; Lidzey, David

    2011-04-01

    We report spectroscopic and electrical measurements to explore hole injection and conduction in devices comprising a molybdenum sub-oxide (MoOx) hole injection layers and poly[(9,9-dioctylfluorenyl-2, 7-diyl)-co-(4,4'(N-(4-sec-butylphenyl))) diphenylamine](TFB) hole transporting polymer. We report improvements in device conductivity over benchmark structures incorporating an ITO electrode and polyethylenedioxythiophene polystyrene sulfonate (PEDOT:PSS) hole injection layers and furthermore achieve injection from MoOx to TFB that is efficient even with an underlying low workfunction Al electrode. XPS spectroscopy has been used to investigate the electronic structure of the interfaces and we find discrete energy alignment regimes consistent with recent surface science studies by Tengstedt et al. [Appl. Phys. Lett. 88, 053502 (2006)], corresponding to Fermi level pinning for MoOx/TFB and vacuum level pinning in the case of Al/TFB. While the energetic alignment regime is measured to be independent of MoOx thickness, the device conductivity continuously varies with MoOx thickness; an observation that can be qualitatively explained by considering two independent charge injection mechanisms from molybdenum oxide sites having different stoicheometry.

  11. Improved molybdenum disulfide-silver motor brushes have extended life

    NASA Technical Reports Server (NTRS)

    Horton, J. C.; King, H. M.

    1964-01-01

    Motor brushes of proper quantities of molybdenum disulfide and copper or silver are manufactured by sintering techniques. Graphite molds are used. These brushes operate satisfactorily for long periods in normal atmosphere or in a high-vacuum environment.

  12. Electroplating and stripping copper on molybdenum and niobium

    NASA Technical Reports Server (NTRS)

    Power, J. L.

    1978-01-01

    Molybdenum and niobium are often electroplated and subsequently stripped of copper. Since general standard plating techniques produce poor quality coatings, general procedures have been optimized and specified to give good results.

  13. High Molybdenum availability for evolution in a Mesoproterozoic lacustrine environment.

    PubMed

    Parnell, John; Spinks, Samuel; Andrews, Steven; Thayalan, Wanethon; Bowden, Stephen

    2015-05-19

    Trace metal data for Proterozoic marine euxinic sediments imply that the expansion of nitrogen-fixing cyanobacteria and diversification of eukaryotes were delayed while the availability of bioessential metals such as molybdenum in the ocean was limited. However, there is increasing recognition that the Mesoproterozoic evolution of nitrogen fixation and eukaryotic life may have been promoted in marginal marine and terrestrial environments, including lakes, rather than in the deep ocean. Molybdenum availability is critical to life in lakes, just as it is in the oceans. It is, therefore, important to assess molybdenum availability to the lacustrine environment in the Mesoproterozoic. Here we show that the flux of molybdenum to a Mesoproterozoic lake was 1 to 2 orders of magnitude greater than typical fluxes in the modern and ancient marine environment. Thus, there was no barrier to availability to prevent evolution in the terrestrial environment, in contrast to the nutrient-limited Mesoproterozoic oceans.

  14. Synthesis of Dinitrogen and Dihydrogen Complexes of Molybdenum.

    ERIC Educational Resources Information Center

    Archer, Leonard J.; And Others

    1981-01-01

    Presents background information, safety notes, and laboratory procedures for synthesizing dinitrogen and dihydrogen complexes of molybdenum. The one-step method described is suitable for advanced inorganic chemistry classes. (SK)

  15. Molybdenum-A Key Component of Metal Alloys

    USGS Publications Warehouse

    Kropschot, S.J.

    2010-01-01

    Molybdenum, whose chemical symbol is Mo, was first recognized as an element in 1778. Until that time, the mineral molybdenite-the most important source of molybdenum-was believed to be a lead mineral because of its metallic gray color, greasy feel, and softness. In the late 19th century, French metallurgists discovered that molybdenum, when alloyed (mixed) with steel in small quantities, creates a substance that is remarkably tougher than steel alone and is highly resistant to heat. The alloy was found to be ideal for making tools and armor plate. Today, the most common use of molybdenum is as an alloying agent in stainless steel, alloy steels, and superalloys to enhance hardness, strength, and resistance to corrosion.

  16. High Molybdenum availability for evolution in a Mesoproterozoic lacustrine environment

    NASA Astrophysics Data System (ADS)

    Parnell, John; Spinks, Samuel; Andrews, Steven; Thayalan, Wanethon; Bowden, Stephen

    2015-05-01

    Trace metal data for Proterozoic marine euxinic sediments imply that the expansion of nitrogen-fixing cyanobacteria and diversification of eukaryotes were delayed while the availability of bioessential metals such as molybdenum in the ocean was limited. However, there is increasing recognition that the Mesoproterozoic evolution of nitrogen fixation and eukaryotic life may have been promoted in marginal marine and terrestrial environments, including lakes, rather than in the deep ocean. Molybdenum availability is critical to life in lakes, just as it is in the oceans. It is, therefore, important to assess molybdenum availability to the lacustrine environment in the Mesoproterozoic. Here we show that the flux of molybdenum to a Mesoproterozoic lake was 1 to 2 orders of magnitude greater than typical fluxes in the modern and ancient marine environment. Thus, there was no barrier to availability to prevent evolution in the terrestrial environment, in contrast to the nutrient-limited Mesoproterozoic oceans.

  17. Molybdenum enhanced low-temperature deposition of crystalline silicon nitride

    DOEpatents

    Lowden, R.A.

    1994-04-05

    A process for chemical vapor deposition of crystalline silicon nitride is described which comprises the steps of: introducing a mixture of a silicon source, a molybdenum source, a nitrogen source, and a hydrogen source into a vessel containing a suitable substrate; and thermally decomposing the mixture to deposit onto the substrate a coating comprising crystalline silicon nitride containing a dispersion of molybdenum silicide. 5 figures.

  18. A study of the mechanisms of hydrogen embrittlement in molybdenum

    NASA Technical Reports Server (NTRS)

    Taheri, M.

    1978-01-01

    The mechanical properties of polycrystalline molybdenum samples in both the 'as annealed' and hydrogenized conditions were studied. The results indicate that hydrogen does not alter the yield stress of samples significantly although it reduces both the ultimate tensile strength and the ductility considerably. Fractographic study of samples shows a tendency to intercrystalline cracking of the hydrogenised molybdenum at low temperatures. In the light of the results, a mechanism involving grain boundary weakening is suggested.

  19. Isotopically Modified Molybdenum: Production for Application in Nuclear Energy

    NASA Astrophysics Data System (ADS)

    Smirnov, A. Yu.; Bonarev, A. K.; Sulaberidze, G. A.; Borisevich, V. D.; Kulikov, G. G.; Shmelev, A. N.

    The possibility to use the isotopically modified molybdenum as a constructive material for the fuel rods of light water and fast reactors is discussed. The calculations demonstrate that the isotopically modified molybdenum with an average neutron absorption cross-section comparable to that of zirconium can be obtained with the reasonable for practice cost by a cascade of gas centrifuges, specially designed for separation of non-uranium isotopes.

  20. Oxidation characteristics of molybdenum-zirconium oxide cermets

    NASA Technical Reports Server (NTRS)

    Heitzinger, B.

    1984-01-01

    The oxidation of molybdenum is affected by the factors of temperature, the oxygen pressure in the oxidizing atmosphere, and the time of exposure. Studies of the oxidation characteristics of Mo show that the oxidation rate increases strongly when the temperature exceeds 600 C. Investigations of the behavior of cermets with various percentages of zirconium oxide are discussed, taking into account oxidation conditions at temperatures under and above the melting point of molybdenum trioxide.

  1. Solvent extraction, ion chromatography, and mass spectrometry of molybdenum isotopes.

    PubMed

    Dauphas, N; Reisberg, L; Marty, B

    2001-06-01

    A procedure was developed that allows precise determination of molybdenum isotope abundances in natural samples. Purification of molybdenum was first achieved by solvent extraction using di(2-ethylhexyl) phosphate. Further separation of molybdenum from isobar nuclides was obtained by ion chromatography using AG1-X8 strongly basic anion exchanger. Finally, molybdenum isotopic composition was measured using a multiple collector inductively coupled plasma hexapole mass spectrometer. The abundances of molybdenum isotopes 92, 94, 95, 96, 97, 98, and 100 are 14.8428(510), 9.2498(157), 15.9303(133), 16.6787(37), 9.5534(83), 24.1346(394), and 9.6104(312) respectively, resulting in an atomic mass of 95.9304(45). After internal normalization for mass fractionation, no variation of the molybdenum isotopic composition is observed among terrestrial samples within a relative precision on the order of 0.00001-0.0001. This demonstrates the reliability of the method, which can be applied to searching for possible isotopic anomalies and mass fractionation.

  2. Rotational bands in99Sr

    NASA Astrophysics Data System (ADS)

    Pfeiffer, B.; Monnand, E.; Pinston, J. A.; Münzel, J.; Möller, P.; Krumlinde, J.; Ziegert, W.; Kratz, K.-L.

    1984-02-01

    The β-decay of 59 ms99Rb has been studied at OSTIS. As is confirmed by RPA calculations with Nilsson model wave functions, the lowest energy levels in99Sr are consistent with rotational bands built on the [411 3/2], [413 5/2] and [422 3/2] Nilsson neutron configurations at 0, 423 and 1071 keV, respectively. All three bands have similar values of the inertial parameter ħ2/2θ indicating a nearly rigid rotor.

  3. Determination of technetium-99 in aqueous samples by isotope dilution inductively coupled plasma-mass spectrometry

    SciTech Connect

    Beals, D.M.

    1992-09-01

    An isotope dilution/inductively coupled plasma mass spectrometric method (ID/ICP-MS) for measuring the concentration of technetium-99 in aqueous samples was developed at the Savannah River Technology Center (SRTC). The procedure is faster than radiometric techniques, is also less subject to interferences, and has equal or better detection limits. It is currently being used to measure the concentration of {sup 99}Tc in samples of Savannah River water collected in the vicinity of the Savannah River Site. In this method, one liter samples of water are spiked with {sup 97}Tc. After equilibration, the technetium is extracted from the sample with a chromatographic resin. Interfering elements, molybdenum and ruthenium, are either not retained by the resin or are washed off with dilute nitric acid. The technetium is then eluted with more concentrated nitric acid, and the {sup 99}Tc/{sup 97}Tc ratio in the eluant is measured with an ICP-MS. The {sup 99}Tc concentration in the original sample is calculated from the {sup 99}Tc/{sup 97}Tc ratio. The chemical recovery of the extraction procedure is greater than 90%. The detection limit of the instrument, taken as three times the background counts at m/z = 99, is 0.6 part per trillion (ppt). The detection limit of the procedure, taken as three times the standard deviation of several reagent blank analyses, is 0.33 pCi/L.

  4. Determination of technetium-99 in aqueous samples by isotope dilution inductively coupled plasma-mass spectrometry

    SciTech Connect

    Beals, D.M.

    1992-01-01

    An isotope dilution/inductively coupled plasma mass spectrometric method (ID/ICP-MS) for measuring the concentration of technetium-99 in aqueous samples was developed at the Savannah River Technology Center (SRTC). The procedure is faster than radiometric techniques, is also less subject to interferences, and has equal or better detection limits. It is currently being used to measure the concentration of {sup 99}Tc in samples of Savannah River water collected in the vicinity of the Savannah River Site. In this method, one liter samples of water are spiked with {sup 97}Tc. After equilibration, the technetium is extracted from the sample with a chromatographic resin. Interfering elements, molybdenum and ruthenium, are either not retained by the resin or are washed off with dilute nitric acid. The technetium is then eluted with more concentrated nitric acid, and the {sup 99}Tc/{sup 97}Tc ratio in the eluant is measured with an ICP-MS. The {sup 99}Tc concentration in the original sample is calculated from the {sup 99}Tc/{sup 97}Tc ratio. The chemical recovery of the extraction procedure is greater than 90%. The detection limit of the instrument, taken as three times the background counts at m/z = 99, is 0.6 part per trillion (ppt). The detection limit of the procedure, taken as three times the standard deviation of several reagent blank analyses, is 0.33 pCi/L.

  5. Beta decay of 99Tcm

    NASA Astrophysics Data System (ADS)

    Alburger, D. E.; Richards, P.; Ku, T. H.

    1980-02-01

    The emission of β rays from 6.02-h 99Tcm has been detected with an intermediate-image magnetic spectrometer. β-ray components with end-point energies of 434.8+/-2.6 keV (β0) to the 99Ru ground state and 346.7+/-2.0 keV (β1) to the 90-keV state were found with intensities per decay of (1.0+/-0.3) × 10-5 for β0 and (2.6+/-0.5) × 10-5 for β1. In the Kurie plot analysis the unique first-forbidden "α" shape was assumed for β0 and an allowed shape was assumed for β1. Values of f1t=9.39+/-0.11 for β0 and f0t=8.66+/-0.08 for β1 were derived. γ rays of 322, 233, and 140 keV were observed in a calibrated Ge(Li) detector with relative source intensities of I322:I233:I140=(1.13+/-0.09)×10-6:(0.95+/-0.17)×10-7:1.000. The total β-ray branching of 3.7 × 10-5 results in a negligible correction to dosage calculations in the use of 99Tcm for diagnostic nuclear medicine. RADIOACTIVITY 99Tcm: measured Eβ, Iβ, and Iγ magnetic spectrometer, Ge(Li); deduced decay scheme.

  6. 99 Tips for Safe Schools.

    ERIC Educational Resources Information Center

    Kaufer, Steve

    This pamphlet highlights 99 tips for maintaining safe schools. Areas of interest include: alarm systems and control of access, vandalism, parent education, transportation, school design, personnel training, and graffiti. The majority of the pointers deal with maintaining and implementing various forms of electronic surveillance and strategies for…

  7. Molybdenum oxide and molybdenum oxide-nitride back contacts for CdTe solar cells

    SciTech Connect

    Drayton, Jennifer A. Geisthardt, Russell M. Sites, James R.; Williams, Desiree D. Cramer, Corson L. Williams, John D.

    2015-07-15

    Molybdenum oxide (MoO{sub x}) and molybdenum oxynitride (MoON) thin film back contacts were formed by a unique ion-beam sputtering and ion-beam-assisted deposition process onto CdTe solar cells and compared to back contacts made using carbon–nickel (C/Ni) paint. Glancing-incidence x-ray diffraction and x-ray photoelectron spectroscopy measurements show that partially crystalline MoO{sub x} films are created with a mixture of Mo, MoO{sub 2}, and MoO{sub 3} components. Lower crystallinity content is observed in the MoON films, with an additional component of molybdenum nitride present. Three different film thicknesses of MoO{sub x} and MoON were investigated that were capped in situ in Ni. Small area devices were delineated and characterized using current–voltage (J-V), capacitance–frequency, capacitance–voltage, electroluminescence, and light beam-induced current techniques. In addition, J-V data measured as a function of temperature (JVT) were used to estimate back barrier heights for each thickness of MoO{sub x} and MoON and for the C/Ni paint. Characterization prior to stressing indicated the devices were similar in performance. Characterization after stress testing indicated little change to cells with 120 and 180-nm thick MoO{sub x} and MoON films. However, moderate-to-large cell degradation was observed for 60-nm thick MoO{sub x} and MoON films and for C/Ni painted back contacts.

  8. Molybdenum-base cermet fuel development

    NASA Astrophysics Data System (ADS)

    Pilger, James P.; Gurwell, William E.; Moss, Ronald W.; White, George D.; Seifert, David A.

    Development of a multimegawatt (MMW) space nuclear power system requires identification and resolution of several technical feasibility issues before selecting one or more promising system concepts. Demonstration of reactor fuel fabrication technology is required for cermet-fueled reactor concepts. The MMW reactor fuel development activity at Pacific Northwest Laboratory (PNL) is focused on producing a molybdenum-matrix uranium-nitride (UN) fueled cermte. This cermet is to have a high matrix density (greater than or equal to 95 percent) for high strength and high thermal conductance coupled with a high particle (UN) porosity (approximately 25 percent) for retention of released fission gas at high burnup. Fabrication process development involves the use of porous TiN microspheres as surrogate fuel material until porous Un microspheres become available. Process development was conducted in the areas of microsphere synthesis, particle sealing/coating, and high-energy-rate forming (HERF) and the vacuum hot press consolidation techniques. This paper summarizes the status of these activities.

  9. Amorphous molybdenum silicon superconducting thin films

    SciTech Connect

    Bosworth, D. Sahonta, S.-L.; Barber, Z. H.; Hadfield, R. H.

    2015-08-15

    Amorphous superconductors have become attractive candidate materials for superconducting nanowire single-photon detectors due to their ease of growth, homogeneity and competitive superconducting properties. To date the majority of devices have been fabricated using W{sub x}Si{sub 1−x}, though other amorphous superconductors such as molybdenum silicide (Mo{sub x}Si{sub 1−x}) offer increased transition temperature. This study focuses on the properties of MoSi thin films grown by magnetron sputtering. We examine how the composition and growth conditions affect film properties. For 100 nm film thickness, we report that the superconducting transition temperature (Tc) reaches a maximum of 7.6 K at a composition of Mo{sub 83}Si{sub 17}. The transition temperature and amorphous character can be improved by cooling of the substrate during growth which inhibits formation of a crystalline phase. X-ray diffraction and transmission electron microscopy studies confirm the absence of long range order. We observe that for a range of 6 common substrates (silicon, thermally oxidized silicon, R- and C-plane sapphire, x-plane lithium niobate and quartz), there is no variation in superconducting transition temperature, making MoSi an excellent candidate material for SNSPDs.

  10. The dynamics of copper intercalated molybdenum ditelluride

    NASA Astrophysics Data System (ADS)

    Onofrio, Nicolas; Guzman, David; Strachan, Alejandro

    2016-11-01

    Layered transition metal dichalcogenides are emerging as key materials in nanoelectronics and energy applications. Predictive models to understand their growth, thermomechanical properties, and interaction with metals are needed in order to accelerate their incorporation into commercial products. Interatomic potentials enable large-scale atomistic simulations connecting first principle methods and devices. We present a ReaxFF reactive force field to describe molybdenum ditelluride and its interactions with copper. We optimized the force field parameters to describe the energetics, atomic charges, and mechanical properties of (i) layered MoTe2, Mo, and Cu in various phases, (ii) the intercalation of Cu atoms and small clusters within the van der Waals gap of MoTe2, and (iii) bond dissociation curves. The training set consists of an extensive set of first principles calculations computed using density functional theory (DFT). We validate the force field via the prediction of the adhesion of a single layer MoTe2 on a Cu(111) surface and find good agreement with DFT results not used in the training set. We characterized the mobility of the Cu ions intercalated into MoTe2 under the presence of an external electric field via finite temperature molecular dynamics simulations. The results show a significant increase in drift velocity for electric fields of approximately 0.4 V/Å and that mobility increases with Cu ion concentration.

  11. Molybdenum disilicide composites produced by plasma spraying

    SciTech Connect

    Castro, R.G.; Hollis, K.J.; Kung, H.H.; Bartlett, A.H.

    1998-05-25

    The intermetallic compound, molybdenum disilicide (MoSi{sub 2}) is being considered for high temperature structural applications because of its high melting point and superior oxidation resistance at elevated temperatures. The lack of high temperature strength, creep resistance and low temperature ductility has hindered its progress for structural applications. Plasma spraying of coatings and structural components of MoSi{sub 2}-based composites offers an exciting processing alternative to conventional powder processing methods due to superior flexibility and the ability to tailor properties. Laminate, discontinuous and in situ reinforced composites have been produced with secondary reinforcements of Ta, Al{sub 2}O{sub 3}, SiC, Si{sub 3}N{sub 4} and Mo{sub 5}Si{sub 3}. Laminate composites, in particular, have been shown to improve the damage tolerance of MoSi{sub 2} during high temperature melting operations. A review of research which as been performed at Los Alamos National Laboratory on plasma spraying of MoSi{sub 2}-based composites to improve low temperature fracture toughness, thermal shock resistance, high temperature strength and creep resistance will be discussed.

  12. Vertically aligned biaxially textured molybdenum thin films

    SciTech Connect

    Krishnan, Rahul; Riley, Michael; Lee, Sabrina; Lu, Toh-Ming

    2011-09-15

    Vertically aligned, biaxially textured molybdenum nanorods were deposited using dc magnetron sputtering with glancing flux incidence (alpha = 85 degrees with respect to the substrate normal) and a two-step substrate-rotation mode. These nanorods were identified with a body-centered cubic crystal structure. The formation of a vertically aligned biaxial texture with a [110] out-of-plane orientation was combined with a [-110] in-plane orientation. The kinetics of the growth process was found to be highly sensitive to an optimum rest time of 35 seconds for the two-step substrate rotation mode. At all other rest times, the nanorods possessed two separate biaxial textures each tilted toward one flux direction. While the in-plane texture for the vertical nanorods maintains maximum flux capture area, inclined Mo nanorods deposited at alpha = 85 degrees without substrate rotation display a [-1-1-4] in-plane texture that does not comply with the maximum flux capture area argument. Finally, an in situ capping film was deposited with normal flux incidence over the biaxially textured vertical nanorods resulting in a thin film over the porous nanorods. This capping film possessed the same biaxial texture as the nanorods and could serve as an effective substrate for the epitaxial growth of other functional materials.

  13. Structural phase transitions in monolayer molybdenum dichalcogenides

    NASA Astrophysics Data System (ADS)

    Choe, Duk-Hyun; Sung, Ha June; Chang, Kee Joo

    2015-03-01

    The recent discovery of two-dimensional materials such as graphene and transition metal dichalcogenides (TMDs) has provided opportunities to develop ultimate thin channel devices. In contrast to graphene, the existence of moderate band gap and strong spin-orbit coupling gives rise to exotic electronic properties which vary with layer thickness, lattice structure, and symmetry. TMDs commonly appear in two structures with distinct symmetries, trigonal prismatic 2H and octahedral 1T phases which are semiconducting and metallic, respectively. In this work, we investigate the structural and electronic properties of monolayer molybdenum dichalcogenides (MoX2, where X = S, Se, Te) through first-principles density functional calculations. We find a tendency that the semiconducting 2H phase is more stable than the metallic 1T phase. We show that a spontaneous symmetry breaking of 1T phase leads to various distorted octahedral (1T') phases, thus inducing a metal-to-semiconductor transition. We discuss the effects of carrier doping on the structural stability and the modification of the electronic structure. This work was supported by the National Research Foundation of Korea (NRF) under Grant No. NRF-2005-0093845 and Samsung Science and Technology Foundation under Grant No. SSTFBA1401-08.

  14. Aquatic acute toxicity assessments of molybdenum (+VI) to Daphnia magna.

    PubMed

    Wang, Chi-Wei; Liang, Chenju; Yeh, Hui-Ju

    2016-03-01

    Generally, molybdenum (Mo) metals in the environment are very rare, but wastewater discharges from industrial processes may contain high concentrations of Mo, which has the potential to contaminate water or soil if not handled properly. In this study, the impact of three common compounds of hexavalent Mo (sodium molybdate (Na2MoO4‧2H2O), ammonium molybdate ((NH4)6Mo7O24‧4H2O) and molybdenum trioxide (MoO3)) in an aquatic system were assessed based on 48-h exposure acute toxicity to Daphnia magna (D. magna). The LC50 toxicities for associated conjugate ions including Na(+), Cl(-), SO4(2-), and NH4(+) were determined. Furthermore, the LC50 values for the three forms of hexavalent Mo were determined, and the acute toxicities of the Mo forms were found to follow the order: (NH4)6Mo7O24‧4H2O > MoO3 > Na2MoO4‧2H2O in solution. (NH4)6Mo7O24‧4H2O exhibited the lowest LC50 of 43.3 mg L(-1) (corresponding to 23.5 mg Mo L(-1)) among the three molybdenum salts. The research confirmed that the toxicity of molybdenum in the aquatic system is highly dependent on the form of molybdenum salts used, and is also associated with the influence of the background water quality.

  15. Preliminary investigations on the use of uranium silicide targets for fission Mo-99 production

    SciTech Connect

    Cols, H.; Cristini, P.; Marques, R.

    1997-08-01

    The National Atomic Energy Commission (CNEA) of Argentine Republic owns and operates an installation for production of molybdenum-99 from fission products since 1985, and, since 1991, covers the whole national demand of this nuclide, carrying out a program of weekly productions, achieving an average activity of 13 terabecquerel per week. At present they are finishing an enlargement of the production plant that will allow an increase in the volume of production to about one hundred of terabecquerel. Irradiation targets are uranium/aluminium alloy with 90% enriched uranium with aluminium cladding. In view of international trends held at present for replacing high enrichment uranium (HEU) for enrichment values lower than 20 % (LEU), since 1990 the authors are in contact with the RERTR program, beginning with tests to adapt their separation process to new irradiation target conditions. Uranium silicide (U{sub 3}Si{sub 2}) was chosen as the testing material, because it has an uranium mass per volume unit, so that it allows to reduce enrichment to a value of 20%. CNEA has the technology for manufacturing miniplates of uranium silicide for their purposes. In this way, equivalent amounts of Molybdenum-99 could be obtained with no substantial changes in target parameters and irradiation conditions established for the current process with Al/U alloy. This paper shows results achieved on the use of this new target.

  16. Capture chromatography for Mo-99 recovery from uranyl sulfate solutions: minimum-column-volume design method.

    PubMed

    Ling, Lei; Chung, Pei-Lun; Youker, Amanda; Stepinski, Dominique C; Vandegrift, George F; Wang, Nien-Hwa Linda

    2013-09-27

    Molybdenum-99 (Mo-99), generated from the fission of Uranium-235 (U-235), is the radioactive parent of the most widely used medical isotope, technetium-99m (Tc-99m). An efficient, robust, low-pressure process is developed for recovering Mo-99 from uranyl sulfate solutions. The minimum column volume and the maximum column length for required yield, pressure limit, and loading time are determined using a new graphical method. The method is based on dimensionless groups and intrinsic adsorption and diffusion parameters, which are estimated using a small number of experiments and simulations. The design is tested with bench-scale experiments with titania columns. The results show a high capture yield and a high stripping yield (95±5%). The design can be adapted to changes in design constraints or the variations in feed concentration, feed volume, or material properties. The graph shows clearly how the column utilization is affected by the required yield, loading time, and pressure limit. The cost effectiveness of various sorbent candidates can be evaluated based on the intrinsic parameters. This method can be used more generally for designing other capture chromatography processes.

  17. A Network Model and Computational Approach for the Mo-99 Supply Chain for Nuclear Medicine

    NASA Astrophysics Data System (ADS)

    Nagurney, Ladimer; Nagurney, Anna

    2011-11-01

    Technetium-99m, produced from the decay of Molybdenum-99, is the most commonly used radioisotope for medical imaging, specifically in cardiac and cancer diagnostics. The MO-99 is produced in a small number of reactors and is processed and distributed worldwide. We have developed a tractable network model and computational approach for the design and redesign of the MO-99 supply chains. This topic is of special relevance to medical physics given the product's widespread use and the aging of the nuclear reactors where it is produced. This generalized network model, for which we derived formulae for the arc and path multipliers that capture the underlying physics of radioisotope decay, includes total operational cost minimization, and the minimization of cost associated with nuclear waste disposal, coupled with capacity investment (or disinvestment) costs. Its solution yields the optimal link capacities as well as the optimal MO-99 flows so that demand at the medical facilities is satisfied. We illustrate the framework with a Western Hemisphere case study. The framework provides the foundation for further empirical research and the basis for the modeling and analysis of supply chain networks for other very time-sensitive medical products.

  18. METHOD FOR FORMING A COATING OF MOLYBDENUM CARBIDE ON A CARBON BODY

    DOEpatents

    Simnad, M.T.

    1962-04-01

    A method is described for coating a carbon bodywith molybdenum carbide in such a manner that the carbon body is rendered less permeable to the flow of gases and has increased resistance to corrosion and erosion. The method includes coating a carbon body with molybdenum trioxide by contacting it at a temperature below the condensation temperature with molybdenum trioxide vapors and thereafter carburizing the molybdenum trioxide in situ in an inert atmosphere on the carhon body. (AEC)

  19. Groundwater Molybdenum from Emerging Industries in Taiwan.

    PubMed

    Tsai, Kuo-Sheng; Chang, Yu-Min; Kao, Jimmy C M; Lin, Kae-Long

    2016-01-01

    This study determined the influence of emerging industries development on molybdenum (Mo) groundwater contamination. A total of 537 groundwater samples were collected for Mo determination, including 295 samples from potentially contaminated areas of 3 industrial parks in Taiwan and 242 samples from non-potentially contaminated areas during 2008-2014. Most of the high Mo samples are located downstream from a thin film transistor-liquid crystal display (TFT-LCD) panel factory. Mean groundwater Mo concentrations from potentially contaminated areas (0.0058 mg/L) were significantly higher (p < 0.05) than those from non-potentially contaminated areas (0.0022 mg/L). The highest Mo wastewater concentrations in the effluent from the optoelectronics industry and following wastewater batch treatment were 0.788 and 0.0326 mg/L, respectively. This indicates that wastewater containing Mo is a possible source of both groundwater and surface water contamination. Nine samples of groundwater exceed the World Health Organization's suggested drinking water guideline of 0.07 mg/L. A non-carcinogenic risk assessment for Mo in adults and children using the Mo concentration of 0.07 mg/L yielded risks of 0.546 and 0.215, respectively. These results indicate the importance of the development of a national drinking water quality standard for Mo in Taiwan to ensure safe groundwater for use. According to the human health risk calculation, the groundwater Mo standard is suggested as 0.07 mg/L. Reduction the discharge of Mo-contaminated wastewater from factories in the industrial parks is also the important task in the future.

  20. Isotopic delta values of molybdenum reference solutions

    NASA Astrophysics Data System (ADS)

    Wen, Hanjie; Carignan, Jean; Cloquet, Christophe; Zhu, Xiangkun; Zhang, Yuxu

    2010-05-01

    We report the isotopic composition of five molybdenum (Mo) standard reference solutions and four fractions from one of these solutions eluted through anion resin column relative to a sixth reference solution. Measurements were conducted using Isoprobe multi collector inductively coupled plasma mass spectrometer (MC-ICP-MS) at the Centre de Recherches Pétrographiques et Géochimiques (France) and Nu Plasma MC-ICP-MS at either the Ecole Normale Supérieure de Lyon (France) or the Laboratory of Isotope Geology in the Ministry of Land and Resources (China). The sample-standard bracketing method was employed to correct the mass bias for Mo isotopes during instrumental measurement. Except for the Merck Mo solution, all the Mo solutions were identical in isotopic composition within error. Although the JMC Mo solution has been used as the internal reference material by various groups, uncertainty may still occur with different lot numbers and availability might be limited. Here, we propose the NIST 3134 Mo solution as a new candidate for delta zero reference material, used for reporting Mo isotopic composition of natural samples. Isotopic compositions for four eluted fractions of the Sigma-Aldrich Mo solution range from 2.2 ‰ to -2.0 ‰ for δ97/95Mo relative to the NIST Mo standard. These values span the range of reported isotopic composition for natural terrestrial and experimental samples (approximately -0.5‰ to 1.6‰ for δ97/95Mo). We propose these eluted fractions to be used as secondary reference for Mo isotope measurements.

  1. 40 CFR 421.210 - Applicability: Description of the primary molybdenum and rhenium subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... primary molybdenum and rhenium subcategory. 421.210 Section 421.210 Protection of Environment... POINT SOURCE CATEGORY Primary Molybdenum and Rhenium Subcategory § 421.210 Applicability: Description of the primary molybdenum and rhenium subcategory. The provisions of this subpart are applicable...

  2. 40 CFR 421.210 - Applicability: Description of the primary molybdenum and rhenium subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... primary molybdenum and rhenium subcategory. 421.210 Section 421.210 Protection of Environment... POINT SOURCE CATEGORY Primary Molybdenum and Rhenium Subcategory § 421.210 Applicability: Description of the primary molybdenum and rhenium subcategory. The provisions of this subpart are applicable...

  3. 40 CFR 421.210 - Applicability: Description of the primary molybdenum and rhenium subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... primary molybdenum and rhenium subcategory. 421.210 Section 421.210 Protection of Environment... POINT SOURCE CATEGORY Primary Molybdenum and Rhenium Subcategory § 421.210 Applicability: Description of the primary molybdenum and rhenium subcategory. The provisions of this subpart are applicable...

  4. 40 CFR 421.210 - Applicability: Description of the primary molybdenum and rhenium subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... primary molybdenum and rhenium subcategory. 421.210 Section 421.210 Protection of Environment... POINT SOURCE CATEGORY Primary Molybdenum and Rhenium Subcategory § 421.210 Applicability: Description of the primary molybdenum and rhenium subcategory. The provisions of this subpart are applicable...

  5. 40 CFR 421.210 - Applicability: Description of the primary molybdenum and rhenium subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... primary molybdenum and rhenium subcategory. 421.210 Section 421.210 Protection of Environment... POINT SOURCE CATEGORY Primary Molybdenum and Rhenium Subcategory § 421.210 Applicability: Description of the primary molybdenum and rhenium subcategory. The provisions of this subpart are applicable...

  6. 40 CFR 421.220 - Applicability: Description of the secondary molybdenum and vanadium subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... secondary molybdenum and vanadium subcategory. 421.220 Section 421.220 Protection of Environment... POINT SOURCE CATEGORY Secondary Molybdenum and Vanadium Subcategory § 421.220 Applicability: Description of the secondary molybdenum and vanadium subcategory. The provisions of this subpart are...

  7. 40 CFR 421.220 - Applicability: Description of the secondary molybdenum and vanadium subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... secondary molybdenum and vanadium subcategory. 421.220 Section 421.220 Protection of Environment... POINT SOURCE CATEGORY Secondary Molybdenum and Vanadium Subcategory § 421.220 Applicability: Description of the secondary molybdenum and vanadium subcategory. The provisions of this subpart are...

  8. 40 CFR 421.220 - Applicability: Description of the secondary molybdenum and vanadium subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... secondary molybdenum and vanadium subcategory. 421.220 Section 421.220 Protection of Environment... POINT SOURCE CATEGORY Secondary Molybdenum and Vanadium Subcategory § 421.220 Applicability: Description of the secondary molybdenum and vanadium subcategory. The provisions of this subpart are...

  9. 40 CFR 421.220 - Applicability: Description of the secondary molybdenum and vanadium subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... secondary molybdenum and vanadium subcategory. 421.220 Section 421.220 Protection of Environment... POINT SOURCE CATEGORY Secondary Molybdenum and Vanadium Subcategory § 421.220 Applicability: Description of the secondary molybdenum and vanadium subcategory. The provisions of this subpart are...

  10. 40 CFR 421.220 - Applicability: Description of the secondary molybdenum and vanadium subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... secondary molybdenum and vanadium subcategory. 421.220 Section 421.220 Protection of Environment... POINT SOURCE CATEGORY Secondary Molybdenum and Vanadium Subcategory § 421.220 Applicability: Description of the secondary molybdenum and vanadium subcategory. The provisions of this subpart are...

  11. Microstructures define melting of molybdenum at high pressures

    PubMed Central

    Hrubiak, Rostislav; Meng, Yue; Shen, Guoyin

    2017-01-01

    High-pressure melting anchors the phase diagram of a material, revealing the effect of pressure on the breakdown of the ordering of atoms in the solid. An important case is molybdenum, which has long been speculated to undergo an exceptionally steep increase in melting temperature when compressed. On the other hand, previous experiments showed nearly constant melting temperature as a function of pressure, in large discrepancy with theoretical expectations. Here we report a high-slope melting curve in molybdenum by synchrotron X-ray diffraction analysis of crystalline microstructures, generated by heating and subsequently rapidly quenching samples in a laser-heated diamond anvil cell. Distinct microstructural changes, observed at pressures up to 130 gigapascals, appear exclusively after melting, thus offering a reliable melting criterion. In addition, our study reveals a previously unsuspected transition in molybdenum at high pressure and high temperature, which yields highly textured body-centred cubic nanograins above a transition temperature. PMID:28248309

  12. A molybdenum disulfide/carbon nanotube heterogeneous complementary inverter.

    PubMed

    Huang, Jun; Somu, Sivasubramanian; Busnaina, Ahmed

    2012-08-24

    We report a simple, bottom-up/top-down approach for integrating drastically different nanoscale building blocks to form a heterogeneous complementary inverter circuit based on layered molybdenum disulfide and carbon nanotube (CNT) bundles. The fabricated CNT/MoS(2) inverter is composed of n-type molybdenum disulfide (MOS(2)) and p-type CNT transistors, with a high voltage gain of 1.3. The CNT channels are fabricated using directed assembly while the layered molybdenum disulfide channels are fabricated by mechanical exfoliation. This bottom-up fabrication approach for integrating various nanoscale elements with unique characteristics provides an alternative cost-effective methodology to complementary metal-oxide-semiconductors, laying the foundation for the realization of high performance logic circuits.

  13. Achieving the ideal strength in annealed molybdenum nanopillars

    SciTech Connect

    Lowry, M. B.; Kiener, D.; LeBlanc, M. M.; Chisholm, Claire; Florando, Jeff; Morris, J. W.; Minor, Andrew

    2010-01-01

    The theoretical strength of a material is the stress required to deform an infinite, defect-free crystal. Achieving the theoretical strength of a material experimentally is hindered by the ability to create and mechanically test an absolutely defect-free material. Here we show that through annealing it is possible to employ the versatility of the focused ion beam (FIB) but recover a mechanically pristine limited volume. Starting with FIB-milled molybdenum pillars, we anneal them in situ in a transmission electron microscope (TEM) producing a molybdenum pillar with a spherical cap. This geometry allows for the maximum stress to occur in the interior of the spherical cap and is ideally suited for experimentally achieving the ideal strength. During in situ compression testing in the TEM the annealed pillars show initial elastic loading followed by catastrophic failure at, or very near, the calculated theoretical strength of molybdenum. Published by Elsevier Ltd. on behalf of Acta Materialia Inc.

  14. Microstructures define melting of molybdenum at high pressures

    NASA Astrophysics Data System (ADS)

    Hrubiak, Rostislav; Meng, Yue; Shen, Guoyin

    2017-03-01

    High-pressure melting anchors the phase diagram of a material, revealing the effect of pressure on the breakdown of the ordering of atoms in the solid. An important case is molybdenum, which has long been speculated to undergo an exceptionally steep increase in melting temperature when compressed. On the other hand, previous experiments showed nearly constant melting temperature as a function of pressure, in large discrepancy with theoretical expectations. Here we report a high-slope melting curve in molybdenum by synchrotron X-ray diffraction analysis of crystalline microstructures, generated by heating and subsequently rapidly quenching samples in a laser-heated diamond anvil cell. Distinct microstructural changes, observed at pressures up to 130 gigapascals, appear exclusively after melting, thus offering a reliable melting criterion. In addition, our study reveals a previously unsuspected transition in molybdenum at high pressure and high temperature, which yields highly textured body-centred cubic nanograins above a transition temperature.

  15. Molybdenum chloride catalysts for Z-selective olefin metathesis reactions

    NASA Astrophysics Data System (ADS)

    Koh, Ming Joo; Nguyen, Thach T.; Lam, Jonathan K.; Torker, Sebastian; Hyvl, Jakub; Schrock, Richard R.; Hoveyda, Amir H.

    2017-01-01

    The development of catalyst-controlled stereoselective olefin metathesis processes has been a pivotal recent advance in chemistry. The incorporation of appropriate ligands within complexes based on molybdenum, tungsten and ruthenium has led to reactivity and selectivity levels that were previously inaccessible. Here we show that molybdenum monoaryloxide chloride complexes furnish higher-energy (Z) isomers of trifluoromethyl-substituted alkenes through cross-metathesis reactions with the commercially available, inexpensive and typically inert Z-1,1,1,4,4,4-hexafluoro-2-butene. Furthermore, otherwise inefficient and non-stereoselective transformations with Z-1,2-dichloroethene and 1,2-dibromoethene can be effected with substantially improved efficiency and Z selectivity. The use of such molybdenum monoaryloxide chloride complexes enables the synthesis of representative biologically active molecules and trifluoromethyl analogues of medicinally relevant compounds. The origins of the activity and selectivity levels observed, which contradict previously proposed principles, are elucidated with the aid of density functional theory calculations.

  16. Recent Developments in Homogeneous Dinitrogen Reduction by Molybdenum and Iron

    PubMed Central

    MacLeod, K. Cory; Holland, Patrick L.

    2013-01-01

    The reduction of gaseous nitrogen (N2) is a challenge for industrial, biological and synthetic chemists, who want to understand the formation of ammonia (NH3) for agriculture and also want to form N-C and N-Si bonds for fine chemical synthesis. The iron-molybdenum active site of nitrogenase has inspired chemists to explore the ability of iron and molybdenum complexes to bring about transformations related to N2 reduction. This area of research has gained significant momentum, and the last two years have witnessed a number of significant advances in synthetic Fe-N2 and Mo-N2 chemistry. In addition, the identities of all atoms in the iron-molybdenum cofactor of nitrogenase have finally been elucidated, and the discovery of a carbide has generated new questions and targets for coordination chemists. This Perspective summarizes the recent work on iron and molydenum complexes, and highlights the opportunities for continued research. PMID:23787744

  17. Onset of superconductivity in sodium and potassium intercalated molybdenum disulphide

    NASA Technical Reports Server (NTRS)

    Somoano, R. B.; Rembaum, A.

    1971-01-01

    Molybdenum disulfide in the form of natural crystals or powder has been intercalated at -65 to -70 C with sodium and potassium using the liquid ammonia technique. All intercalated samples were found to show a superconducting transition. A plot of the percent of diamagnetic throw versus temperature indicates the possible existence of two phases in the potassium intercalated molybdenum disulfide. The onset of superconductivity in potassium and sodium intercalated molybdenite powder was found to be approximately 6.2 and approximately 4.5 K, respectively. The observed superconductivity is believed to be due to an increase in electron density as a result of intercalation.

  18. A review of chromium, molybdenum, and tungsten alloys

    NASA Technical Reports Server (NTRS)

    Klopp, W. D.

    1975-01-01

    The mechanical properties of chromium, molybdenum, and tungsten alloys are reviewed with particular emphasis on high-temperature strength and low-temperature ductility. Precipitate strengthening is highly effective at 0.4 to 0.8 times the melting temperature in these metals, with HfC being most effective in tungsten and molybdenum, and Ta(B,C) most effective in chromium. Low-temperature ductility can be improved by alloying to promote rhenium ductilizing or solution softening. The low-temperature mechanical properties of these alloys appear related to electronic interactions rather than to the usual metallurgical considerations.

  19. Selective emission multilayer coatings for a molybdenum thermophotovoltaic radiator

    SciTech Connect

    Cockeram, Brian Vern

    2004-01-27

    Multilayer coating designs have been developed to provide selective emission for a molybdenum thermophotovoltaic (TPV) radiator surface. These coatings increase the surface emissivity of a molybdenum TPV radiator substrate in the wavelength range that matches the bandgap of the TPV cells to increase the power density of the TPV system. Radiator emission at wavelengths greater than the bandgap energy of the TPV cells is greatly reduced through the use of these coatings, which significantly increases the efficiency of the TPV system. The use of this coating greatly improves the performance of a TPV system, and the coating can be tailored to match the bandgap of any practical TPV system.

  20. Nitrogen incorporation in sputter deposited molybdenum nitride thin films

    SciTech Connect

    Stöber, Laura Patocka, Florian Schneider, Michael Schmid, Ulrich; Konrath, Jens Peter Haberl, Verena

    2016-03-15

    In this paper, the authors report on the high temperature performance of sputter deposited molybdenum (Mo) and molybdenum nitride (Mo{sub 2}N) thin films. Various argon and nitrogen gas compositions are applied for thin film synthetization, and the amount of nitrogen incorporation is determined by Auger measurements. Furthermore, effusion measurements identifying the binding conditions of the nitrogen in the thin film are performed up to 1000 °C. These results are in excellent agreement with film stress and scanning electron microscope analyses, both indicating stable film properties up to annealing temperatures of 500 °C.

  1. Femtosecond laser surface structuring of molybdenum thin films

    NASA Astrophysics Data System (ADS)

    Kotsedi, L.; Mthunzi, P.; Nuru, Z. Y.; Eaton, S. M.; Sechoghela, P.; Mongwaketsi, N.; Ramponi, R.; Maaza, M.

    2015-10-01

    This contribution reports on the femtosecond surface structuring of molybdenum thin coatings deposited by electron beam evaporation onto Corning glass substrates. The 1-D type periodic grating lines created by such an ablation showed that the widths of the shallow grooves followed a logarithmic dependence with the laser energy incident on the molybdenum film. The electronic valence "x" of the created oxide surface layer MoOx was found to be incident laser power dependent via Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy and X-ray diffraction investigations. Such a photo-induced MoOx-Mo nanocomposite exhibited effective selective solar absorption in the UV-vis-IR spectral range.

  2. Investigation of the α-particle induced nuclear reactions on natural molybdenum

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

    Cross-sections of alpha particle induced nuclear reactions on natural molybdenum have been studied in the frame of a systematic investigation of charged particle induced nuclear reactions on metals for different applications. The excitation functions of 93mTc, 93gTc(m+), 94mTc, 94gTc, 95mTc, 95gTc, 96gTc(m+), 99mTc, 93mMo, 99Mo(cum), 90Nb(m+), 94Ru, 95Ru,97Ru, 103Ru and 88Zr were measured up to 40 MeV alpha energy by using a stacked foil technique and activation method. The main goals of this work were to get experimental data for accelerator technology, for monitoring of alpha beam, for thin layer activation technique and for testing nuclear reaction theories. The experimental data were compared with critically analyzed published data and with the results of model calculations, obtained by using the ALICE-IPPE, EMPIRE and TALYS codes (TENDL-2011).

  3. STS-99: Post Flight Presentation

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Live footage shows the crewmembers of STS-99, Commander Kevin R. Kregel, Pilot Dominic L. Pudwill Gorie, and Mission Specialists Janet L. Kavandi, Janice E. Voss, Mamoru Mohri, and Gerhard P.J. Thiele, arriving at Kennedy Space Center (KSC) in the T-38 aircraft. Crewmembers are seen speaking to the welcoming crowd at KSC, suiting-up, walking out to the Astro-van, being strapped in the shuttle, and performing various activities while in orbit. Scenes include the astronaut training process, main engine ignition, liftoff, solid rocket booster separation, mast deployment and retraction, and the changing of the mapping tapes. Footage also includes the crewmembers sleeping, eating, exercising, dancing and having fun in zero gravity. The High Definition Television Camera (HDTV) picks up images from the Earth. These images includes Bolivia, Paraguay, Brazil, Bahamas, Mauritania, Saudi Arabia, Mount Fuji, Tokyo Bay, Southern Russia, the Black Sea, Equador, Northern Peru, the Mediterranean Sea, Malta, Sicily and Italy. The crewmembers of STS-99 each took a turn to narrate the scenes and events as they occur.

  4. Alloy hardening and softening in binary molybdenum alloys as related to electron concentration

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Witzke, W. R.

    1972-01-01

    An investigation was conducted to determine the effects of alloy additions of hafnium, tantalum, tungsten, rhenium, osmium, iridium, and platinum on hardness of molybdenum. Special emphasis was placed on alloy softening in these binary molybdenum alloys. Results showed that alloy softening was produced by those elements having an excess of s+d electrons compared to molybdenum, while those elements having an equal number or fewer s+d electrons that molybdenum failed to produce alloy softening. Alloy softening and alloy hardening can be correlated with the difference in number of s+d electrons of the solute element and molybdenum.

  5. Tungsten-molybdenum fractionation in estuarine environments

    NASA Astrophysics Data System (ADS)

    Mohajerin, T. Jade; Helz, George R.; Johannesson, Karen H.

    2016-03-01

    Dissolved tungsten (W) and molybdenum (Mo) concentrations were measured in surface waters and sediment pore waters of Terrebonne Bay, a shallow estuary in the Mississippi River delta, to investigate the biogeochemical processes that fractionate these Group 6 elements relative to one another during transit from weathering to sedimentary environments. Although many of the chemical properties of W and Mo are similar, the two elements behave autonomously, and the fractionation mechanisms are only partly understood. In sulfidic pore waters, dissolved Mo is depleted relative to river water-seawater mixtures, whereas dissolved W is >10-fold enriched. Reductive dissolution of poorly crystalline phases like ferrihydrite, which is a preferential host of W relative to Mo in grain coatings on river-borne particles, can explain the dissolved W enrichment. Dissolved W becomes increasingly enriched as H2S(aq) rises above about 60 μM due to transformation of WO42- to thiotungstates as well as to additional reductive dissolution of phases that host W. In contrast, as rising sulfide transforms MoO42- to thiomolybdates in pore waters, dissolved Mo is suppressed, probably owing to equilibration with an Fe-Mo-S phase. This putative phase appears to control the aqueous ion product, Q = [Fe2+][MoS42-]0.6 [H2S0]0.4/[H+]0.8, at a value of 10-7.78. Concentrations of dissolved W and Mo in pore waters bear no relation to concentrations in surface waters of the same salinity. In surface waters, dissolved Mo is nearly conserved in the estuarine mixing zone. Dissolved W appears also to be conserved except for several cases where W may have been enhanced by exchange with underlying, W-rich pore waters. With increasing salinity, the molar Mo/W ratio rises from about 10 to about 1000 in surface waters whereas it is mostly <10 in underlying pore waters and in highly sulfidic pore waters is mostly near 1. Differences in two chemical properties may account for this fractionation of Mo with respect to

  6. Corrosion Evaluation of RERTR Uranium Molybdenum Fuel

    SciTech Connect

    A K Wertsching

    2012-09-01

    As part of the National Nuclear Security Agency (NNSA) mandate to replace the use of highly enriched uranium (HEU) fuel for low enriched uranium (LEU) fuel, research into the development of LEU fuel for research reactors has been active since the late 1970’s. Originally referred to as the Reduced Enrichment for Research and Test Reactor (RERTR) program the new effort named Global Threat Reduction Initiative (GTRI) is nearing the goal of replacing the standard aluminum clad dispersion highly enriched uranium aluminide fuel with a new LEU fuel. The five domestic high performance research reactors undergoing this conversion are High Flux Isotope reactor (HFIR), Advanced Test Reactor (ATR), National Institute of Standards and Technology (NIST) Reactor, Missouri University Research Reactor (MURR) and the Massachusetts Institute of Technology Reactor II (MITR-II). The design of these reactors requires a higher neutron flux than other international research reactors, which to this point has posed unique challenges in the design and development of the new mandated LEU fuel. The new design utilizes a monolithic fuel configuration in order to obtain sufficient 235U within the LEU stoichoimetry to maintain the fission reaction within the domestic test reactors. The change from uranium aluminide dispersion fuel type to uranium molybdenum (UMo) monolithic configuration requires examination of possible corrosion issues associated with the new fuel meat. A focused analysis of the UMo fuel under potential corrosion conditions, within the ATR and under aqueous storage indicates a slow and predictable corrosion rate. Additional corrosion testing is recommended for the highest burn-up fuels to confirm observed corrosion rate trends. This corrosion analysis will focus only on the UMo fuel and will address corrosion of ancillary components such as cladding only in terms of how it affects the fuel. The calculations and corrosion scenarios are weighted with a conservative bias to

  7. Storage and Bioavailability of Molybdenum in Soils Increased by Organic Matter Complexation

    SciTech Connect

    Wichard, T.; Mishra, B; Myneni, S; Bellenger, J; Kraepiel, A

    2009-01-01

    The micronutrient molybdenum is a necessary component of the nitrogen-fixing enzyme nitrogenase1, 2. Molybdenum is very rare in soils, and is usually present in a highly soluble form, making it susceptible to leaching3, 4. However, it is generally thought that molybdenum attaches to mineral surfaces in acidic soils; this would prevent its escape into the groundwater, but would also impede uptake by microbes3. Here we use X-ray spectroscopy to examine the chemical speciation of molybdenum in soil samples from forests in Arizona and New Jersey. We show that in the leaf litter layer, most of the molybdenum forms strong complexes with plant-derived tannins and tannin-like compounds; molybdenum binds to these organic ligands across a wide pH range. In deeper soils, molybdenum binds to both iron oxides and natural organic matter. We suggest that the molybdenum bound to organic matter can be captured by small complexing agents that are released by nitrogen-fixing bacteria; the molybdenum can then be incorporated into nitrogenase. We conclude that the binding of molybdenum to natural organic matter helps prevent leaching of molybdenum, and is thus a critical step in securing new nitrogen in terrestrial ecosystems.

  8. Storage and bioavailability of molybdenum in soils increased by organic matter complexation

    NASA Astrophysics Data System (ADS)

    Wichard, Thomas; Mishra, Bhoopesh; Myneni, Satish C. B.; Bellenger, Jean-Philippe; Kraepiel, Anne M. L.

    2009-09-01

    The micronutrient molybdenum is a necessary component of the nitrogen-fixing enzyme nitrogenase. Molybdenum is very rare in soils, and is usually present in a highly soluble form, making it susceptible to leaching. However, it is generally thought that molybdenum attaches to mineral surfaces in acidic soils; this would prevent its escape into the groundwater, but would also impede uptake by microbes. Here we use X-ray spectroscopy to examine the chemical speciation of molybdenum in soil samples from forests in Arizona and New Jersey. We show that in the leaf litter layer, most of the molybdenum forms strong complexes with plant-derived tannins and tannin-like compounds; molybdenum binds to these organic ligands across a wide pH range. In deeper soils, molybdenum binds to both iron oxides and natural organic matter. We suggest that the molybdenum bound to organic matter can be captured by small complexing agents that are released by nitrogen-fixing bacteria; the molybdenum can then be incorporated into nitrogenase. We conclude that the binding of molybdenum to natural organic matter helps prevent leaching of molybdenum, and is thus a critical step in securing new nitrogen in terrestrial ecosystems.

  9. Electrodeposition of low contraction chromium/molybdenum alloys using pulse-reverse plating. Final report

    SciTech Connect

    Miller, M.D.; Langston, S.

    1994-12-01

    The use of modulated pulse periodic reverse (pulse-reverse) current to electrodeposit a low contraction (LC) chromium/molybdenum alloy has been evaluated. When using one full pulse-reverse plating cycle, the percent molybdenum in the deposit increased almost 400 percent (from 1 to 4 percent) as the current in the reverse cycle was increased from 0 to 10 amps. However, when the pulse reverse current was carried to six full plating cycles, the percent molybdenum in the deposit was not dependent upon the current and remained constant at about 1 percent. This is about the same percent molybdenum that could be expected in direct current-plated LC chromium/molybdenum alloy and about half the percent molybdenum that could be expected in an on/off pulse-plated LC chromium/molybdenum alloy.

  10. Flexible Molybdenum Electrodes towards Designing Affinity Based Protein Biosensors

    PubMed Central

    Kamakoti, Vikramshankar; Panneer Selvam, Anjan; Radha Shanmugam, Nandhinee; Muthukumar, Sriram; Prasad, Shalini

    2016-01-01

    Molybdenum electrode based flexible biosensor on porous polyamide substrates has been fabricated and tested for its functionality as a protein affinity based biosensor. The biosensor performance was evaluated using a key cardiac biomarker; cardiac Troponin-I (cTnI). Molybdenum is a transition metal and demonstrates electrochemical behavior upon interaction with an electrolyte. We have leveraged this property of molybdenum for designing an affinity based biosensor using electrochemical impedance spectroscopy. We have evaluated the feasibility of detection of cTnI in phosphate-buffered saline (PBS) and human serum (HS) by measuring impedance changes over a frequency window from 100 mHz to 1 MHz. Increasing changes to the measured impedance was correlated to the increased dose of cTnI molecules binding to the cTnI antibody functionalized molybdenum surface. We achieved cTnI detection limit of 10 pg/mL in PBS and 1 ng/mL in HS medium. The use of flexible substrates for designing the biosensor demonstrates promise for integration with a large-scale batch manufacturing process. PMID:27438863

  11. Irradiation testing of a niobium-molybdenum developmental thermocouple

    SciTech Connect

    Knight, R.C.; Greenslade, D.L.

    1991-10-01

    A need exists for a radiation-resistant thermocouple capable of monitoring temperatures in excess of the limits of the chromel/alumel system. Tungsten/rhenium and platinum/rhodium thermocouples have sufficient temperature capability but have proven to be unstable because of irradiation-induced decalibration. The niobium/molybdenum system is believed to hold great potential for nuclear applications at temperatures up to 2000 K. However, the fragility of pure niobium and fabrication problems with niobium/molybdenum alloys have limited development of this system. Utilizing the Fast Flux Test Facility, a developmental thermocouple with a thermoelement pair consisting of a pure molybdenum and a niobium-1%zirconium alloy wire was irradiated fro 7200 hours at a temperature of 1070 K. The thermocouple performed flawlessly for the duration of the experiment and exhibited stability comparable to a companion chromel/alumel unit. A second thermocouple, operating at 1375 K, is currently being employed to monitor a fusion materials experiment in the Fast Flux Test Facility. This experiment, also scheduled for 7200 hours, will serve to further evaluate the potential of the niobium-1%zirconium/molybdenum thermoelement system. 7 refs., 7 figs.

  12. Rhenium, Molybdenum, Tungsten - Prospects for Production and Industrial Applications

    DTIC Science & Technology

    1998-06-18

    hydronmetallurgical facilities for molybdenum and tungsten production has been investigated. They contain mainly sodium nitrate , ammonium nitrate , sodium...effluents are evaporated to dryness leaving a mixture of salts consisting of sodium and sulfoammonia nitrates , sodium and ammonium sulfates, and suitable for...improvement of solvent-extraction process for ammonium paratungstate production G.P.Giganov, V.G.Giganov .............................. 77 Utilization of

  13. Molybdenum-platinum-oxide electrodes for thermoelectric generators

    DOEpatents

    Schmatz, Duane J.

    1990-01-01

    The invention is directed to a composite article suitable for use in thermoelectric generators. The article comprises a solid electrolyte carrying a thin film comprising molybdenum-platinum-oxide as an electrode deposited by physical deposition techniques. The invention is also directed to the method of making same.

  14. Dissolution kinetics of a sintered molybdenum coating applied on ceramics

    SciTech Connect

    Kuz`ko, V.S.

    1994-11-01

    Using weighing and corrosion diagrams, the etching parameters are determined for a sintered M-21 molybdenum coating applied to VK 94-1 vacuum-tight ceramics. Dissolution of M-21 in an alkaline solution of potassium hexacyanoferrate(III) can be treated as a corrosion process proceeding with kinetic control.

  15. Flexible Molybdenum Electrodes towards Designing Affinity Based Protein Biosensors.

    PubMed

    Kamakoti, Vikramshankar; Panneer Selvam, Anjan; Radha Shanmugam, Nandhinee; Muthukumar, Sriram; Prasad, Shalini

    2016-07-18

    Molybdenum electrode based flexible biosensor on porous polyamide substrates has been fabricated and tested for its functionality as a protein affinity based biosensor. The biosensor performance was evaluated using a key cardiac biomarker; cardiac Troponin-I (cTnI). Molybdenum is a transition metal and demonstrates electrochemical behavior upon interaction with an electrolyte. We have leveraged this property of molybdenum for designing an affinity based biosensor using electrochemical impedance spectroscopy. We have evaluated the feasibility of detection of cTnI in phosphate-buffered saline (PBS) and human serum (HS) by measuring impedance changes over a frequency window from 100 mHz to 1 MHz. Increasing changes to the measured impedance was correlated to the increased dose of cTnI molecules binding to the cTnI antibody functionalized molybdenum surface. We achieved cTnI detection limit of 10 pg/mL in PBS and 1 ng/mL in HS medium. The use of flexible substrates for designing the biosensor demonstrates promise for integration with a large-scale batch manufacturing process.

  16. Preparation of isotopic molybdenum foils utilizing small quantities of material

    NASA Astrophysics Data System (ADS)

    Lipski, A. R.; Lee, L. L.; Liang, J. F.; Mahon, J. C.

    1993-09-01

    A simple method utilizing a small amount of isotopic material for production of molybdenum foils is discussed. An e-gun is used in the procedure. The Mo powder undergoes reduction-sintering and melting-solidifying steps leading to the creation of a metallic droplet suitable for further cold rolling or vacuum deposition.

  17. Molybdenum disilicide composites reinforced with zirconia and silicon carbide

    SciTech Connect

    Petrovic, J.J.

    1992-12-31

    This patent pertains to compositions consisting essentially of molybdenum disilicide, silicon carbide, and a zirconium oxide component. The silicon carbide used in the compositions is in whisker or powder form. The zirconium oxide component is pure zirconia or partially stabilized zirconia or fully stabilized zirconia. Fabrication, fracture toughness, and bend strength are covered.

  18. Synthesis and characterization of molybdenum incorporated mesoporous aluminophosphate

    NASA Astrophysics Data System (ADS)

    Ho, Li-Ngee; Ikegawa, Tasuku; Nishiguchi, Hiroyasu; Nagaoka, Katsutoshi; Takita, Yusaku

    2006-07-01

    A synthesis of molybdenum incorporated mesoporous aluminophosphate with long-chain n-alkylamine as template material had been prepared under non-aqueous condition. These materials were extensively characterized by using X-ray diffraction (XRD), nitrogen sorption isotherms, nuclear magnetic resonance of 27Al and 31P (NMR), inductive coupled plasma (ICP), electron spin resonance (ESR), Fourier transform infrared (FTIR) and thermogravimetric-differential thermal analysis (TG-DTA). Morphology of the materials had been observed by using transmission electron microscope (TEM) that revealed the mesoporous materials possessed wormhole-like structures. Alkaline solvent extraction using n-butylamine/ethanol had been efficiently removed the n-alkylamine from the mesoporous samples which yielded BET surface areas around 550-730 m 2/g. BJH analysis showed a narrow pore size distribution which increased with increasing of the carbon chain length of alkylamine (template). Valence state and coordination of the molybdenum in the obtained samples were investigated by using ESR and FTIR where it was found that Mo 4+ and Mo 6+ molybdenum species existed in the molybdenum incorporated mesoporous aluminophosphate in tetrahedral coordination.

  19. Discovery of rubidium, strontium, molybdenum, and rhodium isotopes

    SciTech Connect

    Parker, A.M.; Thoennessen, M.

    2012-07-15

    Currently, 31 rubidium, 35 strontium, 35 molybdenum, and 38 rhodium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  20. Molybdenum disilicide composites reinforced with zirconia and silicon carbide

    DOEpatents

    Petrovic, John J.

    1995-01-01

    Compositions consisting essentially of molybdenum disilicide, silicon carbide, and a zirconium oxide component. The silicon carbide used in the compositions is in whisker or powder form. The zirconium oxide component is pure zirconia or partially stabilized zirconia or fully stabilized zirconia.

  1. Molybdenum disilicide composites reinforced with zirconia and silicon carbide

    DOEpatents

    Petrovic, J.J.

    1995-01-17

    Compositions are disclosed consisting essentially of molybdenum disilicide, silicon carbide, and a zirconium oxide component. The silicon carbide used in the compositions is in whisker or powder form. The zirconium oxide component is pure zirconia or partially stabilized zirconia or fully stabilized zirconia.

  2. 49 CFR 229.99 - Safety hangers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Safety hangers. 229.99 Section 229.99..., DEPARTMENT OF TRANSPORTATION RAILROAD LOCOMOTIVE SAFETY STANDARDS Safety Requirements Internal Combustion Equipment § 229.99 Safety hangers. Drive shafts shall have safety hangers....

  3. 49 CFR 229.99 - Safety hangers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Safety hangers. 229.99 Section 229.99..., DEPARTMENT OF TRANSPORTATION RAILROAD LOCOMOTIVE SAFETY STANDARDS Safety Requirements Internal Combustion Equipment § 229.99 Safety hangers. Drive shafts shall have safety hangers....

  4. 49 CFR 229.99 - Safety hangers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Safety hangers. 229.99 Section 229.99..., DEPARTMENT OF TRANSPORTATION RAILROAD LOCOMOTIVE SAFETY STANDARDS Safety Requirements Internal Combustion Equipment § 229.99 Safety hangers. Drive shafts shall have safety hangers....

  5. 49 CFR 229.99 - Safety hangers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Safety hangers. 229.99 Section 229.99..., DEPARTMENT OF TRANSPORTATION RAILROAD LOCOMOTIVE SAFETY STANDARDS Safety Requirements Internal Combustion Equipment § 229.99 Safety hangers. Drive shafts shall have safety hangers....

  6. 49 CFR 229.99 - Safety hangers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Safety hangers. 229.99 Section 229.99..., DEPARTMENT OF TRANSPORTATION RAILROAD LOCOMOTIVE SAFETY STANDARDS Safety Requirements Internal Combustion Equipment § 229.99 Safety hangers. Drive shafts shall have safety hangers....

  7. 45 CFR 99.2 - Presiding officer.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 1 2013-10-01 2013-10-01 false Presiding officer. 99.2 Section 99.2 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PROCEDURE FOR HEARINGS FOR THE CHILD CARE AND DEVELOPMENT FUND General § 99.2 Presiding officer. (a) (1) The presiding officer at...

  8. 14 CFR 99.9 - Radio requirements.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Radio requirements. 99.9 Section 99.9... AND GENERAL OPERATING RULES SECURITY CONTROL OF AIR TRAFFIC General § 99.9 Radio requirements. (a) A person who operates a civil aircraft into an ADIZ must have a functioning two-way radio, and the...

  9. 14 CFR 99.9 - Radio requirements.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 2 2013-01-01 2013-01-01 false Radio requirements. 99.9 Section 99.9... AND GENERAL OPERATING RULES SECURITY CONTROL OF AIR TRAFFIC General § 99.9 Radio requirements. (a) A person who operates a civil aircraft into an ADIZ must have a functioning two-way radio, and the...

  10. 14 CFR 99.9 - Radio requirements.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false Radio requirements. 99.9 Section 99.9... AND GENERAL OPERATING RULES SECURITY CONTROL OF AIR TRAFFIC General § 99.9 Radio requirements. (a) A person who operates a civil aircraft into an ADIZ must have a functioning two-way radio, and the...

  11. 14 CFR 99.9 - Radio requirements.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Radio requirements. 99.9 Section 99.9... AND GENERAL OPERATING RULES SECURITY CONTROL OF AIR TRAFFIC General § 99.9 Radio requirements. (a) A person who operates a civil aircraft into an ADIZ must have a functioning two-way radio, and the...

  12. 14 CFR 99.9 - Radio requirements.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 2 2014-01-01 2014-01-01 false Radio requirements. 99.9 Section 99.9... AND GENERAL OPERATING RULES SECURITY CONTROL OF AIR TRAFFIC General § 99.9 Radio requirements. (a) A person who operates a civil aircraft into an ADIZ must have a functioning two-way radio, and the...

  13. 14 CFR 99.49 - Hawaii ADIZ.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Hawaii ADIZ. 99.49 Section 99.49 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC... Zones § 99.49 Hawaii ADIZ. (a) Outer boundary. The area included in the irregular octagonal...

  14. 14 CFR 99.49 - Hawaii ADIZ.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Hawaii ADIZ. 99.49 Section 99.49 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC... Zones § 99.49 Hawaii ADIZ. (a) Outer boundary. The area included in the irregular octagonal...

  15. 14 CFR 99.3 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Definitions. 99.3 Section 99.3 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SECURITY CONTROL OF AIR TRAFFIC General § 99.3 Definitions. Aeronautical...

  16. 14 CFR 99.15 - Position reports.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Position reports. 99.15 Section 99.15 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SECURITY CONTROL OF AIR TRAFFIC General § 99.15 Position reports. (a)...

  17. 14 CFR 99.12 - [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false 99.12 Section 99.12 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SECURITY CONTROL OF AIR TRAFFIC General § 99.12...

  18. 14 CFR 99.5 - Emergency situations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Emergency situations. 99.5 Section 99.5 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SECURITY CONTROL OF AIR TRAFFIC General § 99.5 Emergency situations. In...

  19. 14 CFR 99.1 - Applicability.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Applicability. 99.1 Section 99.1 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SECURITY CONTROL OF AIR TRAFFIC General § 99.1 Applicability. (a)...

  20. 29 CFR 99.405 - Management decision.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 1 2010-07-01 2010-07-01 true Management decision. 99.405 Section 99.405 Labor Office of... Agencies and Pass-through Entities § 99.405 Management decision. (a) General. The management decision shall... the management decision, the Federal agency or pass-through entity may request additional...

  1. 29 CFR 99.505 - Audit reporting.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 1 2014-07-01 2013-07-01 true Audit reporting. 99.505 Section 99.505 Labor Office of the Secretary of Labor AUDITS OF STATES, LOCAL GOVERNMENTS, AND NON-PROFIT ORGANIZATIONS Auditors § 99.505 Audit... the audit was conducted in accordance with this part and include the following: (a) An opinion...

  2. 29 CFR 99.510 - Audit findings.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 1 2014-07-01 2013-07-01 true Audit findings. 99.510 Section 99.510 Labor Office of the Secretary of Labor AUDITS OF STATES, LOCAL GOVERNMENTS, AND NON-PROFIT ORGANIZATIONS Auditors § 99.510 Audit findings. (a) Audit findings reported. The auditor shall report the following as audit findings in...

  3. 29 CFR 99.230 - Audit costs.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 1 2014-07-01 2013-07-01 true Audit costs. 99.230 Section 99.230 Labor Office of the Secretary of Labor AUDITS OF STATES, LOCAL GOVERNMENTS, AND NON-PROFIT ORGANIZATIONS Audits § 99.230 Audit costs. (a) Allowable costs. Unless prohibited by law, the cost of audits made in accordance with...

  4. 29 CFR 99.200 - Audit requirements.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 1 2014-07-01 2013-07-01 true Audit requirements. 99.200 Section 99.200 Labor Office of the Secretary of Labor AUDITS OF STATES, LOCAL GOVERNMENTS, AND NON-PROFIT ORGANIZATIONS Audits § 99.200 Audit requirements. (a) Audit required. Non-Federal entities that expend $300,000 or more in...

  5. 46 CFR 111.99-5 - General.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false General. 111.99-5 Section 111.99-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Fire Door Holding and Release Systems § 111.99-5 General. Fire door release systems, if installed, must...

  6. 46 CFR 111.99-1 - Applicability.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Applicability. 111.99-1 Section 111.99-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Fire Door Holding and Release Systems § 111.99-1 Applicability. This subpart applies to fire...

  7. 30 CFR 7.99 - Critical characteristics.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Critical characteristics. 7.99 Section 7.99... Areas of Underground Coal Mines Where Permissible Electric Equipment is Required § 7.99 Critical characteristics. The following critical characteristics shall be inspected or tested on each diesel power...

  8. 29 CFR 99.405 - Management decision.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 1 2014-07-01 2013-07-01 true Management decision. 99.405 Section 99.405 Labor Office of... Agencies and Pass-through Entities § 99.405 Management decision. (a) General. The management decision shall... the management decision, the Federal agency or pass-through entity may request additional...

  9. 25 CFR 700.99 - Salvage value.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 25 Indians 2 2010-04-01 2010-04-01 false Salvage value. 700.99 Section 700.99 Indians THE OFFICE OF NAVAJO AND HOPI INDIAN RELOCATION COMMISSION OPERATIONS AND RELOCATION PROCEDURES General Policies and Instructions Definitions § 700.99 Salvage value. Salvage value means the probable sale price of...

  10. 45 CFR 99.2 - Presiding officer.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 1 2012-10-01 2012-10-01 false Presiding officer. 99.2 Section 99.2 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PROCEDURE FOR HEARINGS FOR THE CHILD CARE AND DEVELOPMENT FUND General § 99.2 Presiding officer. (a) (1) The presiding officer at...

  11. 45 CFR 99.2 - Presiding officer.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Presiding officer. 99.2 Section 99.2 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PROCEDURE FOR HEARINGS FOR THE CHILD CARE AND DEVELOPMENT FUND General § 99.2 Presiding officer. (a) (1) The presiding officer at...

  12. 45 CFR 99.25 - Evidence.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 1 2014-10-01 2014-10-01 false Evidence. 99.25 Section 99.25 Public Welfare... DEVELOPMENT FUND Hearing Procedures § 99.25 Evidence. (a) Testimony. Testimony shall be given orally under... conference or otherwise prior to the hearing if the presiding officer so requires. (c) Rules of...

  13. 45 CFR 99.25 - Evidence.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 1 2013-10-01 2013-10-01 false Evidence. 99.25 Section 99.25 Public Welfare... DEVELOPMENT FUND Hearing Procedures § 99.25 Evidence. (a) Testimony. Testimony shall be given orally under... conference or otherwise prior to the hearing if the presiding officer so requires. (c) Rules of...

  14. 45 CFR 99.25 - Evidence.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 1 2011-10-01 2011-10-01 false Evidence. 99.25 Section 99.25 Public Welfare... DEVELOPMENT FUND Hearing Procedures § 99.25 Evidence. (a) Testimony. Testimony shall be given orally under... conference or otherwise prior to the hearing if the presiding officer so requires. (c) Rules of...

  15. 45 CFR 99.25 - Evidence.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 1 2012-10-01 2012-10-01 false Evidence. 99.25 Section 99.25 Public Welfare... DEVELOPMENT FUND Hearing Procedures § 99.25 Evidence. (a) Testimony. Testimony shall be given orally under... conference or otherwise prior to the hearing if the presiding officer so requires. (c) Rules of...

  16. 29 CFR 99.400 - Responsibilities.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 1 2011-07-01 2011-07-01 false Responsibilities. 99.400 Section 99.400 Labor Office of the... Pass-through Entities § 99.400 Responsibilities. (a) Cognizant agency for audit responsibilities... programs of more than one agency. (8) Coordinate the audit work and reporting responsibilities...

  17. 29 CFR 99.400 - Responsibilities.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 1 2014-07-01 2013-07-01 true Responsibilities. 99.400 Section 99.400 Labor Office of the... Pass-through Entities § 99.400 Responsibilities. (a) Cognizant agency for audit responsibilities... programs of more than one agency. (8) Coordinate the audit work and reporting responsibilities...

  18. 29 CFR 99.400 - Responsibilities.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 1 2012-07-01 2012-07-01 false Responsibilities. 99.400 Section 99.400 Labor Office of the... Pass-through Entities § 99.400 Responsibilities. (a) Cognizant agency for audit responsibilities... programs of more than one agency. (8) Coordinate the audit work and reporting responsibilities...

  19. Diversification of 99Mo/99mTc separation: non–fission reactor production of 99Mo as a strategy for enhancing 99mTc availability.

    PubMed

    Pillai, Maroor R A; Dash, Ashutosh; Knapp, Furn F Russ

    2015-01-01

    This paper discusses the benefits of obtaining (99m)Tc from non-fission reactor-produced low-specific-activity (99)Mo. This scenario is based on establishing a diversified chain of facilities for the distribution of (99m)Tc separated from reactor-produced (99)Mo by (n,γ) activation of natural or enriched Mo. Such facilities have expected lower investments than required for the proposed chain of cyclotrons for the production of (99m)Tc. Facilities can receive and process reactor-irradiated Mo targets then used for extraction of (99m)Tc over a period of 2 wk, with 3 extractions on the same day. Estimates suggest that a center receiving 1.85 TBq (50 Ci) of (99)Mo once every 4 d can provide 1.48-3.33 TBq (40-90 Ci) of (99m)Tc daily. This model can use research reactors operating in the United States to supply current (99)Mo needs by applying natural (nat)Mo targets. (99)Mo production capacity can be enhanced by using (98)Mo-enriched targets. The proposed model reduces the loss of (99)Mo by decay and avoids proliferation as well as waste management issues associated with fission-produced (99)Mo.

  20. 14 CFR 99.49 - Hawaii ADIZ.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 2 2013-01-01 2013-01-01 false Hawaii ADIZ. 99.49 Section 99.49 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC... Zones § 99.49 Hawaii ADIZ. (a) Outer boundary. The area included in the irregular octagonal...

  1. 14 CFR 99.49 - Hawaii ADIZ.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false Hawaii ADIZ. 99.49 Section 99.49 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC... Zones § 99.49 Hawaii ADIZ. (a) Outer boundary. The area included in the irregular octagonal...

  2. 14 CFR 99.49 - Hawaii ADIZ.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 2 2014-01-01 2014-01-01 false Hawaii ADIZ. 99.49 Section 99.49 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC... Zones § 99.49 Hawaii ADIZ. (a) Outer boundary. The area included in the irregular octagonal...

  3. 46 CFR 111.99-5 - General.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false General. 111.99-5 Section 111.99-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Fire Door Holding and Release Systems § 111.99-5 General. Fire door release systems, if installed, must...

  4. 46 CFR 111.99-1 - Applicability.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Applicability. 111.99-1 Section 111.99-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Fire Door Holding and Release Systems § 111.99-1 Applicability. This subpart applies to fire...

  5. 32 CFR 552.99 - Applicability.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Applicability. 552.99 Section 552.99 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY MILITARY RESERVATIONS AND NATIONAL CEMETERIES REGULATIONS AFFECTING MILITARY RESERVATIONS Firearms and Weapons § 552.99 Applicability. (a)...

  6. 32 CFR 552.99 - Applicability.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 3 2012-07-01 2009-07-01 true Applicability. 552.99 Section 552.99 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY MILITARY RESERVATIONS AND NATIONAL CEMETERIES REGULATIONS AFFECTING MILITARY RESERVATIONS Firearms and Weapons § 552.99 Applicability. (a)...

  7. 45 CFR 99.27 - Official transcript.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Official transcript. 99.27 Section 99.27 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PROCEDURE FOR HEARINGS FOR THE CHILD CARE AND DEVELOPMENT FUND Hearing Procedures § 99.27 Official transcript. The Department...

  8. 45 CFR 99.25 - Evidence.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Evidence. 99.25 Section 99.25 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PROCEDURE FOR HEARINGS FOR THE CHILD CARE AND DEVELOPMENT FUND Hearing Procedures § 99.25 Evidence. (a) Testimony. Testimony shall be given orally...

  9. 45 CFR 99.24 - Evidentiary purpose.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Evidentiary purpose. 99.24 Section 99.24 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PROCEDURE FOR HEARINGS FOR THE CHILD CARE AND DEVELOPMENT FUND Hearing Procedures § 99.24 Evidentiary purpose. The purpose of...

  10. 45 CFR 99.13 - Place.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Place. 99.13 Section 99.13 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PROCEDURE FOR HEARINGS FOR THE CHILD CARE AND DEVELOPMENT FUND Preliminary Matters-Notice and Parties § 99.13 Place. The hearing shall be held in the...

  11. 15 CFR 9.9 - Consumer education.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Consumer education. 9.9 Section 9.9 Commerce and Foreign Trade Office of the Secretary of Commerce PROCEDURES FOR A VOLUNTARY LABELING PROGRAM FOR HOUSEHOLD APPLIANCES AND EQUIPMENT TO EFFECT ENERGY CONSERVATION § 9.9 Consumer education....

  12. 15 CFR 9.9 - Consumer education.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 15 Commerce and Foreign Trade 1 2014-01-01 2014-01-01 false Consumer education. 9.9 Section 9.9 Commerce and Foreign Trade Office of the Secretary of Commerce PROCEDURES FOR A VOLUNTARY LABELING PROGRAM FOR HOUSEHOLD APPLIANCES AND EQUIPMENT TO EFFECT ENERGY CONSERVATION § 9.9 Consumer education....

  13. 15 CFR 9.9 - Consumer education.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 15 Commerce and Foreign Trade 1 2011-01-01 2011-01-01 false Consumer education. 9.9 Section 9.9 Commerce and Foreign Trade Office of the Secretary of Commerce PROCEDURES FOR A VOLUNTARY LABELING PROGRAM FOR HOUSEHOLD APPLIANCES AND EQUIPMENT TO EFFECT ENERGY CONSERVATION § 9.9 Consumer education....

  14. 15 CFR 9.9 - Consumer education.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 15 Commerce and Foreign Trade 1 2013-01-01 2013-01-01 false Consumer education. 9.9 Section 9.9 Commerce and Foreign Trade Office of the Secretary of Commerce PROCEDURES FOR A VOLUNTARY LABELING PROGRAM FOR HOUSEHOLD APPLIANCES AND EQUIPMENT TO EFFECT ENERGY CONSERVATION § 9.9 Consumer education....

  15. 15 CFR 9.9 - Consumer education.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 15 Commerce and Foreign Trade 1 2012-01-01 2012-01-01 false Consumer education. 9.9 Section 9.9 Commerce and Foreign Trade Office of the Secretary of Commerce PROCEDURES FOR A VOLUNTARY LABELING PROGRAM FOR HOUSEHOLD APPLIANCES AND EQUIPMENT TO EFFECT ENERGY CONSERVATION § 9.9 Consumer education....

  16. 29 CFR 99.320 - Report submission.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 1 2011-07-01 2011-07-01 false Report submission. 99.320 Section 99.320 Labor Office of the Secretary of Labor AUDITS OF STATES, LOCAL GOVERNMENTS, AND NON-PROFIT ORGANIZATIONS Auditees § 99... finance, chief executive officer, or chief financial officer) shall sign a statement to be included...

  17. Uranium-Molybdenum Dissolution Flowsheet Studies

    SciTech Connect

    Pierce, R. A.

    2007-03-01

    The Super Kukla (SK) Prompt Burst Reactor operated at the Nevada Test Site from 1964 to 1978. The SK material is a uranium-molybdenum (U-Mo) alloy material of 90% U/10% Mo by weight at approximately 20% 235U enrichment. H-Canyon Engineering (HCE) requested that the Savannah River National Lab (SRNL) define a flowsheet for safely and efficiently dissolving the SK material. The objective is to dissolve the material in nitric acid (HNO3) in the H-Canyon dissolvers to a U concentration of 15-20 g/L (3-4 g/L 235U) without the formation of precipitates or the generation of a flammable gas mixture. Testing with SK material validated the applicability of dissolution and solubility data reported in the literature for various U and U-Mo metals. Based on the data, the SK material can be dissolved in boiling 3.0-6.0 M HNO3 to a U concentration of 15-20 g/L and a corresponding Mo concentration of 1.7-2.2 g/L. The optimum flowsheet will use 4.0-5.0 M HNO3 for the starting acid. Any nickel (Ni) cladding associated with the material will dissolve readily. After dissolution is complete, traditional solvent extraction flowsheets can be used to recover and purify the U. Dissolution rates for the SK material are consistent with those reported in the literature and are adequate for H-Canyon processing. When the SK material dissolved at 70-100 o C in 1-6 M HNO3, the reaction bubbled vigorously and released nitrogen oxide (NO) and nitrogen dioxide (NO2) gas. Gas generation tests in 1 M and 2 M HNO3 at 100 o C generated less than 0.1 volume percent hydrogen (H2) gas. It is known that higher HNO3 concentrations are less favorable for H2 production. All tests at 70-100 o C produced sufficient gas to mix the solutions without external agitation. At room temperature in 5 M HNO3, the U-Mo dissolved slowly and the U-laden solution sank to the bottom of the dissolution vessel because of its greater density. The effect of the density difference insures that the SK material cannot dissolve and

  18. Rhenium and Molybdenum in Rivers and Estuaries.

    NASA Astrophysics Data System (ADS)

    Walker, B. D.; Peucker-Ehrenbrink, B.

    2004-12-01

    Due to their redox-sensitive nature, the geochemical cycles of Re and Mo are linked to the global organic carbon cycle. Reducing sediments constitute a globally important sink and weathering of organic-rich sediments is responsible for a large portion of the Re and - to a lesser extent - Mo flux to the oceans (Colodner et al., 1993; Jaffe et al., 2002). Riverine concentrations of Re and Mo are a function of the river basin lithology, but are also likely to be affected by anthropogenic contributions (Colodner et al., 1995). Current estimates of global natural riverine Re flux are restricted to single analyses of four major rivers, which characterize only 23%\\ of the global freshwater flux (Colodner et al., 1993). Annual variability of Re and Mo concentrations in rivers has not been studied. A single study of Re concentrations along the salinity gradient of the Amazon shelf is suggestive of conservative mixing, but scatter in the data do not allow to exclude the possibility of Re addition in the low-salinity end of the profile (Colodner et al., 1993). Careful evaluation of samples from the Hudson River estuary using a variety of extraction techniques indicates that spike-sample equilibration was not fully achieved using commonly used methods. We have therefore developed a simple, clean and efficient method of extracting Re from filtered water samples. Our method utilizes syringe filtration, prolonged heating to achieve spike-sample equilibration, batch equilibration with TEVA resin, and extraction of Re and Mo using syringe filtration. Rhenium concentrations in the Hudson, Housatonic and Connecticut rivers are 38 pM, 6.6 pM and 14 pM, respectively, much higher than the estimated global average of 2.1 pM (Colodner et al., 1993). Molybdenum concentrations are 4.6 nM, 5.5 nM, 7.8 nM, respectively. These rivers drain basins of Precambrian basement as well as predominantly Paleozoic sediments and have been substantially urbanized. Data for a salinity profile along the

  19. Characterization of Rhodobacter capsulatus genes encoding a molybdenum transport system and putative molybdenum-pterin-binding proteins.

    PubMed Central

    Wang, G; Angermüller, S; Klipp, W

    1993-01-01

    The alternative, heterometal-free nitrogenase of Rhodobacter capsulatus is repressed by traces of molybdenum in the medium. Strains carrying mutations located downstream of nifB copy II were able to express the alternative nitrogenase even in the presence of high molybdate concentrations. DNA sequence analysis of a 5.5-kb fragment of this region revealed six open reading frames, designated modABCD, mopA, and mopB. The gene products of modB and modC are homologous to ChlJ and ChlD of Escherichia coli and represent an integral membrane protein and an ATP-binding protein typical of high-affinity transport systems, respectively. ModA and ModD exhibited no homology to known proteins, but a leader peptide characteristic of proteins cleaved during export to the periplasm is present in ModA, indicating that ModA might be a periplasmic molybdate-binding protein. The MopA and MopB proteins showed a high degree of amino acid sequence homology to each other. Both proteins contained a tandem repeat of a domain encompassing 70 amino acid residues, which had significant sequence similarity to low-molecular-weight molybdenum-pterin-binding proteins from Clostridium pasteurianum. Compared with that for the parental nifHDK deletion strain, the molybdenum concentrations necessary to repress the alternative nitrogenase were increased 4-fold in a modD mutant and 500-fold in modA, modB, and modC mutants. No significant inhibition of the heterometal-free nitrogenase by molybdate was observed for mopA mopB double mutants. The uptake of molybdenum by mod and mop mutants was estimated by measuring the activity of the conventional molybdenum-containing nitrogenase. Molybdenum transport was not affected in a mopA mopB double mutant, whereas strains carrying lesions in the binding-protein-dependent transport system were impaired in molybdenum uptake. PMID:8491722

  20. Use of a new tandem cation/anion exchange system with clinical-scale generators provides high specific volume solutions of technetium-99m and rhenium-188

    SciTech Connect

    Knapp, F.R. Jr.; Beets, A.L.; Mirzadeh, S.; Guhlke, S. |

    1998-03-01

    In this paper the authors describe the first application of a simple and inexpensive post elution tandem cation-anion exchange column system which is based on generator elution with salts of weak acids such as ammonium acetate instead of saline solution to provide very high specific volume solutions of technetium-99m and rhenium-188 from clinical scale molybdenum-99/technetium-99m generator prepared from low specific activity (n,y) molybdenum-99, and tungsten-188/rhenium-188 generators, respectively. Initial passage of the bolus through a strong cation exchange cartridge converts the ammonium acetate to acetic acid which is essentially not ionized at the acidic pH, allowing specific subsequent amine type (QMA SepPak{trademark}) anion exchange cartridge column trapping of the microscopic levels of the pertechnetate or perrhenate. Subsequent elution of the anion cartridge with a small volume (< 1 mL) of saline then provides high specific volume solutions of technetium-99m by concentration of the high eluant volumes obtained by elution of clinical-scale (1 Ci) generators. This new approach also works very effectively to obtain high specific volume solutions of rhenium-188 (> 500 mCi/mL) from the alumina-based tungsten-188/rhenium-188 generator.

  1. Reflectance, Optical Properties, and Stability of Molybdenum/Strontium and Molybdenum/Yttrium Multilayer Mirrors

    SciTech Connect

    Kjornrattanawanich, Benjawan

    2002-09-01

    The motivation of this work is to develop high reflectance normal-incidence multilayer mirrors in the 8-12 nm wavelength region for applications in astronomy and extreme ultraviolet lithography. To achieve this goal, Mo/Sr and Mo/Y multilayers were studied. These multilayers were deposited with a UHV magnetron sputtering system and their reflectances were measured with synchrotron radiation. High normal-incidence reflectances of 23% at 8.8 nm, 40.8% at 9.4 nm, and 48.3% at 10.5 nm were achieved. However, the reflectance of Mo/Sr multilayers decreased rapidly after exposure to air. Attempts to use thin layers of carbon to passivate the surface of Mo/Sr multilayers were unsuccessful. Experimental results on the refractive index $\\tilde{n}$ = 1-δ + iβ of yttrium and molybdenum in the 50-1300 eV energy region are reported in this work. This is the first time ever that values on the refractive index of yttrium are measured in this energy range. The absorption part β was determined through transmittance measurements. The dispersive part δ was calculated by means of the Kramers-Kronig formalism. The newly determined values of the refractive index of molybdenum are in excellent agreement with the published data. Those of yttrium are more accurate and contain fine structures around the yttrium M-absorption edges where Mo/Y multilayers operate. These improved sets of optical data lead to better design and modeling of the optical properties of Mo/Y multilayers. The reflectance quality of Mo/Y multilayers is dependent on their optical and structural properties. To correlate these properties with the multilayer reflectance, x-ray diffraction, Rutherford backscattering spectrometry, and transmission electron microscopy were used to analyze samples. Normal-incidence reflectances of 32.6% at 9.27 nm, 38.4% at 9.48 nm, and 29.6% at 9.46 nm were obtained from three representative Mo/Y multilayers which had about 0%, 25%, and 39% atomic oxygen assimilated in their yttrium layers

  2. STS-99 Prelaunch Press Briefing

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The primary objective of the STS-99 mission was to complete high resolution mapping of large sections of the Earth's surface using the Shuttle Radar Topography Mission (SRTM), a specially modified radar system. This radar system produced unrivaled 3-D images of the Earth's Surface. The mission was launched at 12:31 on February 11, 2000 onboard the space shuttle Endeavour, and led by Commander Kevin Kregel. The crew was Pilot Dominic L. Pudwill Gorie and Mission Specialists Janet L. Kavandi, Janice E. Voss, Mamoru Mohri from the National Space Development Agency (Japanese Space Agency), and Gerhard P. J. Thiele from DARA (German Space Agency). This videotape shows a press briefing about a mechanical problem that the shuttle was having. There was discussion about possibly scrubbing the launch due to the problem with the Enhanced Master Events Controller. A problem with a fuel pump part had also become evident and there was discussion about the impact that this could have on the flight.

  3. STS-99 / Endeavour Mission Overview

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The primary objective of the STS-99 mission was to complete high resolution mapping of large sections of the Earth's surface using the Shuttle Radar Topography Mission (SRTM). This radar system will produce unrivaled 3-D images of the Earth's Surface. This videotape presents a mission overview press briefing. The panel members are Dr. Ghassem Asrar, NASA Associate Administrator Earth Sciences; General James C. King, Director National Imagery and Mapping Agency (NIMA); Professor Achim Bachem, Member of the Executive Board, Deutschen Zentrum fur Luft- und Raumfahrt (DLR), the German National Aerospace Research Center; and Professor Sergio Deiulio, President of the Italian Space Agency. Dr. Asrar opened with a summary of the history of Earth Observations from space, relating the SRTM to this history. This mission, due to cost and complexity, required partnership with other agencies and nations, and the active participation of the astronauts. General King spoke to the expectations of NIMA, and the use of the Synthetic Aperture Radar to produce the high resolution topographic images. Dr. Achim Bachem spoke about the international cooperation that this mission required, and some of the commercial applications and companies that will use this data. Dr Deiulio spoke of future plans to improve knowledge of the Earth using satellites. Questions from the press concerned use of the information for military actions, the reason for the restriction on access to the higher resolution data, the mechanism to acquire that data for scientific research, and the cost sharing from the mission's partners. There was also discussion about the mission's length.

  4. Mo99 Production Plant Layout

    SciTech Connect

    Woloshun, Keith Albert; Dale, Gregory E.; Naranjo, Angela Carol

    2015-06-25

    The NorthStar Medical Technologies 99Mo production facility configuration is envisioned to be 8 accelerator pairs irradiating 7 100Mo targets (one spare accelerator pair undergoing maintenance while the other 7 pairs are irradiating targets). The required shielding in every direction for the accelerators is initially estimated to be 10 feet of concrete. With the accelerator pairs on one (ground) level and spaced with the required shielding between adjacent pairs, the only practical path for target insertion and removal while minimizing floor space is vertical. The current scheme then requires a target vertical lift of nominally 10 feet through a shield stack. It is envisioned that the lift will be directly into a hot cell where an activated target can be removed from its holder and a new target attached and lowered. The hot cell is on a rail system so that a single hot cell can service all active target locations, as well as deliver the ready targets to the separations lab. On this rail system, coupled to the hot cell, will be a helium recovery and clean-up system. All helium coolant equipment is located on the upper level near to the target removal point.

  5. In-situ molybdenum nano-attached particle synthesis from spent Mo scrap.

    PubMed

    Han, Chulwoong; Kim, Byungmoon; Choi, Hanshin

    2014-10-01

    Radio frequency thermal plasma is a versatile process for engineering powder preparation owing to its high energy density and reactivity. Molybdenum powders were prepared from molybdenum sheet scrap by RF thermal plasma in association with powder comminution process. Molybdenum scrap which was used in high temperature environment was friable enough to be broken into micropowders by hammer milling. Spherical molybdenum micro-powder was obtained from the hammer milled powders were treated via thermal plasma. On the other hand, vaporization and condensation pathway for nanoparticle synthesis is largely dependent on both thermo-physical properties and thermal plasma properties. In this regard, molybdenum trioxide was chosen for the feedstock of nanoparticle synthesis. Additional reactivity of argon-hydrogen thermal plasma, oxide feedstock was fully reduced to bcc molybdenum. Considering different reaction pathway of each feedstock, molybdenum nanoparticle attached molybdenum spherical micro-powder could be effectively synthesized by feeding a blended feedstock of molybdenum micro-powder and molybdenum trioxide micro-powder into argon-hydrogen thermal plasma.

  6. Preparation of molybdenum carbides with multiple morphologies using surfactants as carbon sources

    SciTech Connect

    Wang, Hongfen; Wang, Zhiqi; Chen, Shougang

    2012-10-15

    Molybdenum carbides with surfactants as carbon sources were prepared using the carbothermal reduction of the appropriate precursors (molybdenum oxides deposited on surfactant micelles) at 1023 K under hydrogen gas. The carburized products were characterized using scanning electron microscopy (SEM), X-ray diffraction and BET surface area measurements. From the SEM images, hollow microspherical and rod-like molybdenum carbides were observed. X-ray diffraction patterns showed that the annealing time of carburization had a large effect on the conversion of molybdenum oxides to molybdenum carbides. And BET surface area measurements indicated that the difference of carbon sources brought a big difference in specific surface areas of molybdenum carbides. - Graphical abstract: Molybdenum carbides having hollow microspherical and hollow rod-like morphologies that are different from the conventional monodipersed platelet-like morphologies. Highlights: Black-Right-Pointing-Pointer Molybdenum carbides were prepared using surfactants as carbon sources. Black-Right-Pointing-Pointer The kinds of surfactants affected the morphologies of molybdenum carbides. Black-Right-Pointing-Pointer The time of heat preservation at 1023 K affected the carburization process. Black-Right-Pointing-Pointer Molybdenum carbides with hollow structures had larger specific surface areas.

  7. Low molybdenum state induced by tungsten as a model of molybdenum deficiency in rats.

    PubMed

    Yoshida, Munehiro; Nakagawa, Mikihito; Hosomi, Ryota; Nishiyama, Toshimasa; Fukunaga, Kenji

    2015-05-01

    Organ molybdenum (Mo) concentration and the activity of hepatic sulfite oxidase and xanthine oxidase were compared in tungsten-administered rats as well as rats fed with a low Mo diet to evaluate the use of tungsten-administered rats as a model of Mo deficiency. Twenty-four male 6-week-old Wistar rats were divided into four groups according to diet (AIN93G diet (control diet) or the control diet minus ammonium molybdate (low Mo diet)) and drinking water (deionized water or deionized water containing 200 μg/mL tungsten in the form of sodium tungstate). Mo content in the control and low Mo diets were 196 and 42 ng/g, respectively. Intake of the low Mo diet significantly reduced the Mo content of several organs and serum. Decrease in hepatic sulfite oxidase activity was also induced by the low Mo diet. The administration of tungsten induced marked decreases in organ Mo content and the activity of hepatic sulfite oxidase and xanthine oxidase. These decreases induced by tungsten administration were more pronounced than those induced by just a low Mo diet. Serum uric acid was also reduced by tungsten administration irrespective of Mo intake. Although a comparatively high accumulation of tungsten (3 to 9 μg/g) was observed in the kidneys and liver, adverse effects of tungsten accumulation on liver and kidney function were not observed in serum biochemical tests. These results indicate that tungsten-administered animals may be used as a model of Mo deficiency.

  8. Molybdenum isotope fractionation in the mantle

    NASA Astrophysics Data System (ADS)

    Liang, Yu-Hsuan; Halliday, Alex N.; Siebert, Chris; Fitton, J. Godfrey; Burton, Kevin W.; Wang, Kuo-Lung; Harvey, Jason

    2017-02-01

    We report double-spike molybdenum (Mo) isotope data for forty-two mafic and fifteen ultramafic rocks from diverse locations and compare these with results for five chondrites. The δ98/95Mo values (normalized to NIST SRM 3134) range from -0.59 ± 0.04 to +0.10 ± 0.08‰. The compositions of one carbonaceous (CI) and four ordinary chondrites are relatively uniform (-0.14 ± 0.01‰, 95% ci (confidence interval)) in excellent agreement with previous data. These values are just resolvable from the mean of 10 mid-ocean ridge basalts (MORBs) (0.00 ± 0.02‰, 95% ci). The compositions of 13 mantle-derived ultramafic xenoliths from Kilbourne Hole, Tariat and Vitim are more diverse (-0.39 to -0.07‰) with a mean of -0.22 ± 0.06‰ (95% ci). On this basis, the isotopic composition of the bulk silicate Earth (BSE or Primitive Mantle) is within error identical to chondrites. The mean Mo concentration of the ultramafic xenoliths (0.19 ± 0.07 ppm, 95% ci) is similar in magnitude to that of MORB (0.48 ± 0.13 ppm, 95% ci), providing evidence, either for a more compatible behaviour than previously thought or for selective Mo enrichment of the subcontinental lithospheric mantle. Intraplate and ocean island basalts (OIBs) display significant isotopic variability within a single locality from MORB-like to strongly negative (-0.59 ± 0.04‰). The most extreme values measured are for nephelinites from the Cameroon Line and Trinidade, which also have anomalously high Ce/Pb and low Mo/Ce relative to normal oceanic basalts. δ98/95Mo correlates negatively with Ce/Pb and U/Pb, and positively with Mo/Ce, explicable if a phase such as an oxide or a sulphide liquid selectively retains isotopically heavy Mo in the mantle and fractionates its isotopic composition in low degree partial melts. If residual phases retain Mo during partial melting, it is possible that the [Mo] for the BSE may be misrepresented by values estimated from basalts. This would be consistent with the high Mo

  9. Processing temperature effects on molybdenum disilicide

    SciTech Connect

    Wade, R.K. ); Petrovic, J.J. . Materials Science and Technology Div.)

    1992-11-01

    This paper reports on a series of MoSi[sub 2] compacts that were fabricated at increasing hot-pressing temperatures to achieve different grain sizes. The materials were evaluated by Vickers indentation fracture to determine room-temperature fracture toughness, hardness, and fracture mode. From 1500[degrees] to 1800[degrees] C, MoSi[sub 2] had a constant 67% transgranular fracture and linearly increasing rain size from 14 to 21 [mu]m. Above 1800[degrees]C, the fracture percentage increased rapidly to 97% transgranular at 1920[degrees]C (32 [mu] grain size). Fracture toughness and hardness decreased slightly with increasing temperature. MoSi[sub 2] processed at 1600[degrees]C had the highest fracture toughness and hardness values of 3.6 MPa[center dot]m[sup 1/2] and 9.9 GPa, respectively. The effects of SiO[sub 2] formation from oxygen impurities in the MoSi[sub 2] starting powders and MoSi[sub 2]-Mo[sub 5]Si[sub 3] eutectic liquid formation were studied.

  10. Sintering, Microstructure, and Electrical Conductivity of Zirconia-Molybdenum Cermet

    NASA Astrophysics Data System (ADS)

    Guo, Yanling; Tang, Lei; Zhang, Jieyu

    2015-08-01

    Monolithic zirconia-molybdenum ( m-ZrO2/Mo) cermets of different compositions (5-40 vol.% Mo) and different initial Mo particles sizes (0.08-13 μm) were prepared by traditional powder metallurgy process. The influences of metal content and initial particle sizes on the densification behavior, microstructure, and electrical conductivity of the cermets were studied. A percolation threshold value was obtained about 17.1 vol.% molybdenum fraction, above which a sharp increase in the electrical conductivity was observed. The temperature dependence of the electrical conductivity of cermets was studied. The cermet containing 5 vol.% Mo showed the ionic nature of the conductivity, while the metallic nature was observed in the samples of Mo fraction up to 16 vol.%. The activation of conductivity for ionic type of conductivity and the temperature coefficient of resistivity as well as the effect of porosity on electronic type conductivity are discussed.

  11. Modified chemical route for deposition of molybdenum disulphide thin films

    SciTech Connect

    Vyas, Akshay N. Sartale, S. D.

    2014-04-24

    Molybdenum disulphide (MoS{sub 2}) thin films were deposited on quartz substrates using a modified chemical route. Sodium molybdate and sodium sulphide were used as precursors for molybdenum and sulphur respectively. The route involves formation of tetrathiomolybdate ions (MoS{sub 4}{sup 2−}) and further reduction by sodium borohydride to form MoS{sub 2}. The deposition was performed at room temperature. The deposited films were annealed in argon atmosphere at 1073 K for 1 hour to improve its crystallinity. The deposited films were characterized using scanning electron microscopy (SEM) for morphology, UV-Vis absorption spectroscopy for optical studies and X-ray diffraction (XRD) for structure determination.

  12. Solar thermal thruster made of single crystal molybdenum

    NASA Astrophysics Data System (ADS)

    Shimizu, Morio; Itoh, Katsuya; Sato, Hitoshi; Fujii, Tadayuki; Igarashi, Tadashi; Okamoto, Ken-ichi

    1997-07-01

    The heart element of solar thermal propulsion (STP) system is a thruster made of refractory metals such as tungsten, tantalum and molybdenum or advance high temperature ceramics because of the high operating temperature (1000-2500 K) involved. In this paper, design, fabrication and preliminary experimental results in the JSUS Research Plan are presented, using 20 mm diameter of thrusters made of single crystal molybdenum which NRIM has patented and is a perfect (non-defect) material, namely no brittleness due to recrystallization under high operating temperature conditions. The working gas temperature within the thruster chamber reached higher than 1850 K (namely, the Isp is approximately 700 s for hydrogen gas propellant) at 0.2 MPa of the plenum chamber pressure, using the small solar concentrator (1.6 m diameter of half paraboloid and 0.65 m of the focal length).

  13. Predicting molybdenum toxicity to higher plants: influence of soil properties.

    PubMed

    McGrath, S P; Micó, C; Curdy, R; Zhao, F J

    2010-10-01

    The effect of soil properties on the toxicity of molybdenum (Mo) to four plant species was investigated. Soil organic carbon or ammonium-oxalate extractable Fe oxides were found to be the best predictors of the 50% effective dose (ED50) of Mo in different soils, explaining>65% of the variance in ED50 for four species except for ryegrass (26-38%). Molybdenum concentrations in soil solution and consequently plant uptake were increased when soil pH was artificially raised because sorption of Mo to amorphous oxides is greatly reduced at high pH. The addition of sulphate significantly decreased Mo uptake by oilseed rape. For risk assessment, we suggest that Mo toxicity values for plants should be normalised using soil amorphous iron oxide concentrations.

  14. Genetic characterization of the Neurospora crassa molybdenum cofactor biosynthesis.

    PubMed

    Probst, Corinna; Ringel, Phillip; Boysen, Verena; Wirsing, Lisette; Alexander, Mariko Matsuda; Mendel, Ralf R; Kruse, Tobias

    2014-05-01

    Molybdenum (Mo) is a trace element that is essential for important cellular processes. To gain biological activity, Mo must be complexed in the molybdenum cofactor (Moco), a pterin derivative of low molecular weight. Moco synthesis is a multi-step pathway that involves a variable number of genes in eukaryotes, which are assigned to four steps of eukaryotic Moco biosynthesis. Moco biosynthesis mutants lack any Moco-dependent enzymatic activities, including assimilation of nitrate (plants and fungi), detoxification of sulfite (humans and plants) and utilization of hypoxanthine as sole N-source (fungi). We report the first comprehensive genetic characterization of the Neurospora crassa (N. crassa) Moco biosynthesis pathway, annotating five genes which encode all pathway enzymes, and compare it with the characterized Aspergillus nidulans pathway. Biochemical characterization of the corresponding knock-out mutants confirms our annotation model, documenting the N. crassa/A. nidulans (fungal) Moco biosynthesis as unique, combining the organizational structure of both plant and human Moco biosynthesis genes.

  15. Spectrophotometric determination of molybdenum by extraction of its thiosulphate complex.

    PubMed

    Yatirajam, V; Ram, J

    1974-12-01

    A simple and rapid spectrophotometric determination of molybdenum is described. The molybdenum thiosulphate complex is extracted into isoamyl alcohol from 1.0-1.5M hydrochloric acid containing 36-40 mg of Na(2)S(2)O(3).5H(2)O per ml. The absorbance at lambda(max) = 475 nm obeys Beer's law over the range 0-32 microg of Mo per ml of solvent phase. Up to 5 mg/ml of Ti(IV), V(V), Cr(VI), Fe(III), Co(II), Ni(II), U(VI), W(VI), Sb(III), 1 mg/ml of Cu(II), Sn(II), Bi(V) and 10 microg/ml of Pt(IV) and Pd(II) do not interfere. Large amounts of complexing agents interfere. The method has been applied to analysis of synthetic and industrial samples.

  16. Mechanical Properties of Iron Alumininides Intermetallic Alloy with Molybdenum Addition

    SciTech Connect

    Zuhailawati, H.; Fauzi, M. N. A.

    2010-03-11

    In this work, FeAl-based alloys with and without molybdenum addition were fabricated by sintering of mechanically alloyed powders in order to investigate the effect of molybdenum on iron aluminide mechanical properties. Bulk samples were prepared by mechanical alloying for 4 hours, pressing at 360 MPa and sintering at 1000 deg. C for 2 hours. The specimens were tested in compression at room temperature using Instron machine. The phase identification and microstructure of the consolidated material was examined by x-ray diffraction and scanning electron microscope correspondingly. Results show that 2.5 wt%Mo addition significantly increased the ultimate stress and ultimate strain in compressive mode due to solid solution hardening. However, the addition of Mo more than 2.5 wt% was accompanied by a reduction in both properties caused by the presence of Mo-rich precipitate particles.

  17. Dichroic spin–valley photocurrent in monolayer molybdenum disulphide

    PubMed Central

    Eginligil, Mustafa; Cao, Bingchen; Wang, Zilong; Shen, Xiaonan; Cong, Chunxiao; Shang, Jingzhi; Soci, Cesare; Yu, Ting

    2015-01-01

    The aim of valleytronics is to exploit confinement of charge carriers in local valleys of the energy bands of semiconductors as an additional degree of freedom in optoelectronic devices. Thanks to strong direct excitonic transitions in spin-coupled K valleys, monolayer molybdenum disulphide is a rapidly emerging valleytronic material, with high valley polarization in photoluminescence. Here we elucidate the excitonic physics of this material by light helicity-dependent photocurrent studies of phototransistors. We demonstrate that large photocurrent dichroism (up to 60%) can also be achieved in high-quality molybdenum disulphide monolayers grown by chemical vapour deposition, due to the circular photogalvanic effect on resonant excitations. This opens up new opportunities for valleytonic applications in which selective control of spin–valley-coupled photocurrents can be used to implement polarization-sensitive light-detection schemes or integrated spintronic devices, as well as biochemical sensors operating at visible frequencies. PMID:26134143

  18. Monitoring silica supported molybdenum oxide catalysts at work: a Raman spectroscopic study.

    PubMed

    Thielemann, Jörg P; Hess, Christian

    2013-02-04

    The structure of silica SBA-15-supported molybdenum oxide catalysts is investigated during selective oxidation of propylene at 500 °C using operando Raman spectroscopy. The active catalysts contain mixtures of dispersed molybdenum oxide species exhibiting monooxo and dioxo structure. An increase in molybdenum oxide loading results in a decrease of the ratio of dioxo and monooxo species from 3.8 to 1.9, as determined by quantitative analysis of Raman spectra. Additional in situ Raman studies at 500 °C reveal that the dioxo/monooxo ratio increases in the presence of steam at higher molybdenum oxide loadings. The observed structural changes are assigned to shifts in the equilibrium between dioxo and monooxo species resulting from hydration/dehydration of the catalyst. This study demonstrates that the detailed structure of nanostructured molybdenum oxide catalysts depends on temperature, gas-phase composition, and molybdenum oxide loading.

  19. Molybdenum as a contact material in zinc tin oxide thin film transistors

    SciTech Connect

    Hu, W.; Peterson, R. L.

    2014-05-12

    Amorphous oxide semiconductors are of increasing interest for a variety of thin film electronics applications. Here, the contact properties of different source/drain electrode materials to solution-processed amorphous zinc tin oxide (ZTO) thin-film transistors are studied using the transmission line method. The width-normalized contact resistance between ZTO and sputtered molybdenum is measured to be 8.7 Ω-cm, which is 10, 20, and 600 times smaller than that of gold/titanium, indium tin oxide, and evaporated molybdenum electrodes, respectively. The superior contact formed using sputtered molybdenum is due to a favorable work function lineup, an insulator-free interface, bombardment of ZTO during molybdenum sputtering, and trap-assisted tunneling. The transfer length of the sputtered molybdenum/ZTO contact is 0.34 μm, opening the door to future radio-frequency sub-micron molybdenum/ZTO thin film transistors.

  20. Critical evaluation of molybdenum and its alloys for use in space reactor core heat pipes

    SciTech Connect

    Lundberg, L.B.

    1981-01-01

    The choice of pure molybdenum as the prime candidate material for space reactor core heat pipes is examined, and the advantages and disadvantages of this material are brought into focus. Even though pure molybdenum heat pipes have been built and tested, this metal's high ductile-brittle transition temperature and modest creep strength place significant design restrictions on a core heat pipe made from it. Molybdenum alloys are examined with regard to their promise as potential replacements for pure molybdenum. The properties of TZM and molybdenum-rhenium alloys are examined, and it appears that Mo-Re alloys with 10 to 15 wt % rhenium offer the most advantage as an alternative to pure molybdenum in space reactor core heat pipes.

  1. Structural properties of molybdenum-lead-borate glasses.

    PubMed

    Rada, M; Rada, S; Pascuta, P; Culea, E

    2010-11-01

    Glasses and glass ceramics in the system xMoO₃·(100 - x)[3B₂O₃·PbO] with 0 ≤ x ≤ 30 mol% have been prepared from melt quenching method and characterized by means of X-ray diffraction, FTIR, UV-VIS and EPR spectroscopy. We have examined and analyzed the effects of systematic molybdenum ions intercalation on lead-borate glasses and glass ceramics with interesting results. The observations present in these mechanisms show the lead ions bonded ionic have a strong affinity towards [BO₃] units containing non-bridging oxygens and [MoO₄]²⁻ molybdate units. The pronounced affinity towards molybdate anions yields the formation of the PbMoO₄ crystalline phase. Then, the excess of oxygen can be supported into the glass network by the formation of [MoO₆] and [Mo₂O₇] structural units. Pb²(+) ions with 6s² configuration show strong absorption in the ultraviolet due to parity allowed s²-sp transition and yield an absorption band centered at about 310 nm. The changes in the features of the absorption bands centered at about 310 nm can be explained as a consequence of the appearance of additional absorption shoulder due to photoinduced color centers in the glass such as the formation of borate-molybdate and lead-molybdate paramagnetic defect centers in the glasses. The concentration of molybdenum ions influences the shape and width of the EPR signals located at g ∼ 1.86, 1.91 and 5.19. The microenvironment of molybdenum ions in glasses is expected to have mainly sixfold coordination. However, there is a possibility of reduction of a part of molybdenum ions from the Mo⁶(+) to the Mo⁵(+) and Mo⁴(+) to the Mo³(+) states.

  2. Evaluation of Oxide Dispersion Strengthened (ODS) Molybdenum Alloys

    DTIC Science & Technology

    1997-01-01

    containing 4 parts concentrated sulfuric acid and 1 part distilled water using a Type 304 stainless steel cathode and a direct current accelerating...Ductile-to-Brittle Transition Temperature ( DBTT ): The following mechanical properties were measured from the ODS molybdenum alloy rods: (a) 0.2...and to determine the DBTT . Elevated Temperature Tensile Tests: Elevated temperature tensile specimens of each as- swaged alloy were equilibrated

  3. The nuclear response of molybdenum to supernova neutrinos

    SciTech Connect

    Ydrefors, E.; Suhonen, J.

    2011-12-16

    Neutrino-nucleus interactions play a prominent role in many astrophysical applications. Knowledge about nuclear responses to neutrinos is therefore of paramount importance. We present cross sections for neutral-current neutrino-nucleus scattering off the stable (A = 92,94,95,96,97,98,100) molybdenum isotopes. The nuclear responses for these nuclei are additionally computed by folding the computed cross sections with a Fermi-Dirac distribution.

  4. Performance and Safety Characteristics of Lithium-molybdenum Disulfide Cells

    NASA Technical Reports Server (NTRS)

    Stiles, J. A.

    1984-01-01

    The lithium-molybdenum disulfide system offers attractive characteristics including high rate capability, successful operation up to 75 C, a very low self-discharge rate, a good cycle life and safety characteristics which compare favorably to those of other lithium cells. Moreover, the materials and manufacturing costs for the system is effectively controlled, so the cells should ultimately be competitive with currently marketed rechargeable cells.

  5. Retention of Sputtered Molybdenum on Ion Engine Discharge Chamber Surfaces

    NASA Technical Reports Server (NTRS)

    Sovey, James S.; Dever, Joyce A.; Power, John L.

    2001-01-01

    Grit-blasted anode surfaces are commonly used in ion engines to ensure adherence of sputtered coatings. Next generation ion engines will require higher power levels, longer operating times, and thus there will likely be thicker sputtered coatings on their anode surfaces than observed to date on 2.3 kW-class xenon ion engines. The thickness of coatings on the anode of a 10 kW, 40-centimeter diameter thruster, for example, may be 22 micrometers or more after extended operation. Grit-blasted wire mesh, titanium, and aluminum coupons were coated with molybdenum at accelerated rates to establish coating stability after the deposition process and after thermal cycling tests. These accelerated deposition rates are roughly three orders of magnitude more rapid than the rates at which the screen grid is sputtered in a 2.3 kW-class, 30-centimeter diameter ion engine. Using both RF and DC sputtering processes, the molybdenum coating thicknesses ranged from 8 to 130 micrometers, and deposition rates from 1.8 micrometers per hour to 5.1 micrometers per hour. In all cases, the molybdenum coatings were stable after the deposition process, and there was no evidence of spalling of the coatings after 20 cycles from about -60 to +320 C. The stable, 130 micrometer molybdenum coating on wire mesh is 26 times thicker than the thickest coating found on the anode of a 2.3 kW, xenon ion engine that was tested for 8200 hr. Additionally, this coating on wire mesh coupon is estimated to be a factor of greater than 4 thicker than one would expect to obtain on the anode of the next generation ion engine which may have xenon throughputs as high as 550 kg.

  6. Structural properties of molybdenum-lead-borate glasses

    NASA Astrophysics Data System (ADS)

    Rada, M.; Rada, S.; Pascuta, P.; Culea, E.

    2010-11-01

    Glasses and glass ceramics in the system xMoO 3·(100 - x)[3B 2O 3·PbO] with 0 ≤ x ≤ 30 mol% have been prepared from melt quenching method and characterized by means of X-ray diffraction, FTIR, UV-VIS and EPR spectroscopy. We have examined and analyzed the effects of systematic molybdenum ions intercalation on lead-borate glasses and glass ceramics with interesting results. The observations present in these mechanisms show the lead ions bonded ionic have a strong affinity towards [BO 3] units containing non-bridging oxygens and [MoO 4] 2- molybdate units. The pronounced affinity towards molybdate anions yields the formation of the PbMoO 4 crystalline phase. Then, the excess of oxygen can be supported into the glass network by the formation of [MoO 6] and [Mo 2O 7] structural units. Pb 2+ ions with 6s 2 configuration show strong absorption in the ultraviolet due to parity allowed s 2-sp transition and yield an absorption band centered at about 310 nm. The changes in the features of the absorption bands centered at about 310 nm can be explained as a consequence of the appearance of additional absorption shoulder due to photoinduced color centers in the glass such as the formation of borate-molybdate and lead-molybdate paramagnetic defect centers in the glasses. The concentration of molybdenum ions influences the shape and width of the EPR signals located at g ˜ 1.86, 1.91 and 5.19. The microenvironment of molybdenum ions in glasses is expected to have mainly sixfold coordination. However, there is a possibility of reduction of a part of molybdenum ions from the Mo 6+ to the Mo 5+ and Mo 4+ to the Mo 3+ states.

  7. Feasibility of preparing patterned molybdenum coatings on bismuth telluride thermoelectric modules.

    SciTech Connect

    Sarobol, Pylin; Hall, Aaron Christopher; Miller, Stephen Samuel; Knight, Marlene E.; LePage, William S.; Sobczak, Catherine Elizabeth.; Wesolowski, Daniel Edward

    2013-09-01

    Molybdenum electrical interconnects for thermoelectric modules were produced by air plasma spraying a 30%CE%BCm size molybdenum powder through a laser-cut Kapton tape mask. Initial feasibility demonstrations showed that the molybdenum coating exhibited excellent feature and spacing retention (~170%CE%BCm), adhered to bismuth-telluride, and exhibited electrical conductivity appropriate for use as a thermoelectric module interconnect. A design of experiments approach was used to optimize air plasma spray process conditions to produce a molybdenum coating with low electrical resistivity. Finally, a molybdenum coating was successfully produced on a fullscale thermoelectric module. After the addition of a final titanium/gold layer deposited on top of the molybdenum coating, the full scale module exhibited an electrical resistivity of 128%CE%A9, approaching the theoretical resistivity value for the 6mm module leg of 112%CE%A9. Importantly, air plasma sprayed molybdenum did not show significant chemical reaction with bismuth-telluride substrate at the coating/substrate interface. The molybdenum coating microstructure consisted of lamellar splats containing columnar grains. Air plasma sprayed molybdenum embedded deeply (several microns) into the bismuth-telluride substrate, leading to good adhesion between the coating and the substrate. Clusters of round pores (and cracks radiating from the pores) were found immediately beneath the molybdenum coating. These pores are believed to result from tellurium vaporization during the spray process where the molten molybdenum droplets (2623%C2%B0C) transferred their heat of solidification to the substrate at the moment of impact. Substrate cooling during the molybdenum deposition process was recommended to mitigate tellurium vaporization in future studies.

  8. Mechanical properties of electron-beam-melted molybdenum and dilute Mo-Re alloys.

    NASA Technical Reports Server (NTRS)

    Klopp, W. D.; Witzke, W. R.

    1973-01-01

    Study of Mo-Re alloys aimed at examining the effects of small rhenium additions on the low-temperature ductility of molybdenum and determining the mechanical properties of dilute Mo-Re alloys. The results obtained indicate that high-purity Mo-Re alloys have ductile-brittle transition temperatures considerably lower than those for unalloyed molybdenum and that rhenium promotes normal solid-solution strengthening in molybdenum at elevated temperatures.

  9. Criticality experiments and analysis of molybdenum reflected cylindrical uranyl fluoride water solution reactors

    NASA Technical Reports Server (NTRS)

    Fieno, D.; Fox, T.; Mueller, R.

    1972-01-01

    Clean criticality data were obtained from molybdenum-reflected cylindrical uranyl-fluoride-water solution reactors. Using ENDF/B molybdenum cross sections, a nine energy group two-dimensional transport calculation of a reflected reactor configuration predicted criticality to within 7 cents of the experimental value. For these reactors, it was necessary to compute the reflector resonance integral by a detailed transport calculation at the core-reflector interface volume in the energy region of the two dominant resonances of natural molybdenum.

  10. Basic ammonothermal GaN growth in molybdenum capsules

    NASA Astrophysics Data System (ADS)

    Pimputkar, S.; Speck, J. S.; Nakamura, S.

    2016-12-01

    Single crystal, bulk gallium nitride (GaN) crystals were grown using the basic ammonothermal method in a high purity growth environment created using a non-hermetically sealed molybdenum (Mo) capsule and compared to growths performed in a similarly designed silver (Ag) capsule and capsule-free René 41 autoclave. Secondary ion mass spectrometry (SIMS) analysis revealed transition metal free (<1×1017 cm-3) GaN crystals. Anomalously low oxygen concentrations ((2-6)×1018 cm-3) were measured in a {0001} seeded crystal boule grown using a Mo capsule, despite higher source material oxygen concentrations ((1-5)×1019 cm-3) suggesting that molybdenum (or molybdenum nitrides) may act to getter oxygen under certain conditions. Total system pressure profiles from growth runs in a Mo capsule system were comparable to those without a capsule, with pressures peaking within 2 days and slowly decaying due to hydrogen diffusional losses. Measured Mo capsule GaN growth rates were comparable to un-optimized growth rates in capsule-free systems and appreciably slower than in Ag-capsule systems. Crystal quality replicated that of the GaN seed crystals for all capsule conditions, with high quality growth occurring on the (0001) Ga-face. Optical absorption and impurity concentration characterization suggests reduced concentrations of hydrogenated gallium vacancies (VGa-Hx).

  11. Structure of Molybdenum Under Dynamic Compression to 1 TPa

    NASA Astrophysics Data System (ADS)

    Duffy, Thomas; Wang, Jue; Coppari, Federica; Smith, Raymond; Eggert, Jon; Lazicki, Amy; Fratanduono, Dayne; Rygg, Ryan; Boehly, Thomas; Collins, Gilbert

    2015-06-01

    Molybdenum (Mo) is a refractory 4d transition metal that is widely used as a standard in static and dynamic high-pressure experiments. However, there are significant unanswered questions and unresolved discrepancies about the melting curve and high-pressure phase stability of this fundamental material. Similar questions surround the melting curve and phase stabilities of other transition metals including Ta and Fe, and so a better understanding of Mo has broad implications for high-pressure science and geophysics. Here we use x-ray diffraction to determine the crystal structure of molybdenum under both shock and ramp compression to pressures as high as 1 TPa. Under shock loading, we find that Mo remains in body centered cubic (BCC) structure until melting begins at near 390 GPa. Our results are in good agreement with recent theoretical calculations and recent re-measurement of sound speeds along the Hugoniot. We also carried out x-ray diffraction measurements of ramp-loaded molybdenum up to 1050 GPa. Our x-ray diffraction patterns are consistent with the persistence of the BCC phase up to the highest pressure achieved. The measured densities under ramp loading are intermediate between those achieved under shock compression and those expected from extrapolation of room-temperature data. We do not observe evidence for the theoretically predicted transition to face centered cubic or double hexagonal close packed phases above 600 GPa.

  12. The mammalian molybdenum enzymes of mARC.

    PubMed

    Ott, Gudrun; Havemeyer, Antje; Clement, Bernd

    2015-03-01

    The "mitochondrial amidoxime reducing component" (mARC) is the most recently discovered molybdenum-containing enzyme in mammals. All mammalian genomes studied to date contain two mARC genes: MARC1 and MARC2. The proteins encoded by these genes are mARC-1 and mARC-2 and represent the simplest form of eukaryotic molybdenum enzymes, only binding the molybdenum cofactor. In the presence of NADH, mARC proteins exert N-reductive activity together with the two electron transport proteins cytochrome b5 type B and NADH cytochrome b5 reductase. This enzyme system is capable of reducing a great variety of N-hydroxylated substrates. It plays a decisive role in the activation of prodrugs containing an amidoxime structure, and in detoxification pathways, e.g., of N-hydroxylated purine and pyrimidine bases. It belongs to a group of drug metabolism enzymes, in particular as a counterpart of P450 formed N-oxygenated metabolites. Its physiological relevance, on the other hand, is largely unknown. The aim of this article is to summarize our current knowledge of these proteins with a special focus on the mammalian enzymes and their N-reductive activity.

  13. Molybdate Reduction to Molybdenum Blue by an Antarctic Bacterium

    PubMed Central

    Ahmad, S. A.; Shukor, M. Y.; Shamaan, N. A.; Mac Cormack, W. P.; Syed, M. A.

    2013-01-01

    A molybdenum-reducing bacterium from Antarctica has been isolated. The bacterium converts sodium molybdate or Mo6+ to molybdenum blue (Mo-blue). Electron donors such as glucose, sucrose, fructose, and lactose supported molybdate reduction. Ammonium sulphate was the best nitrogen source for molybdate reduction. Optimal conditions for molybdate reduction were between 30 and 50 mM molybdate, between 15 and 20°C, and initial pH between 6.5 and 7.5. The Mo-blue produced had a unique absorption spectrum with a peak maximum at 865 nm and a shoulder at 710 nm. Respiratory inhibitors such as antimycin A, sodium azide, potassium cyanide, and rotenone failed to inhibit the reducing activity. The Mo-reducing enzyme was partially purified using ion exchange and gel filtration chromatography. The partially purified enzyme showed optimal pH and temperature for activity at 6.0 and 20°C, respectively. Metal ions such as cadmium, chromium, copper, silver, lead, and mercury caused more than 95% inhibition of the molybdenum-reducing activity at 0.1 mM. The isolate was tentatively identified as Pseudomonas sp. strain DRY1 based on partial 16s rDNA molecular phylogenetic assessment and the Biolog microbial identification system. The characteristics of this strain would make it very useful in bioremediation works in the polar and temperate countries. PMID:24381945

  14. Molybdenum accumulation, tolerance and molybdenum-selenium-sulfur interactions in Astragalus selenium hyperaccumulator and nonaccumulator species.

    PubMed

    DeTar, Rachael Ann; Alford, Élan R; Pilon-Smits, Elizabeth A H

    2015-07-01

    Some species hyperaccumulate selenium (Se) upwards of 0.1% of dry weight. This study addressed whether Se hyperaccumulators also accumulate and tolerate more molybdenum (Mo). A field survey revealed on average 2-fold higher Mo levels in three hyperaccumulator Astragali compared to three nonaccumulator Astragali, which were not significantly different. Next, a controlled study was performed where hyperaccumulators Astragalus racemosus and Astragalus bisulcatus were compared with nonaccumulators Astragalus drummondii and Astragalus convallarius for Mo accumulation and tolerance, alone or in the presence of Se. When grown on agar media with 0, 12, 24 or 48 mg L(-1) molybdate and/or 0, 1.6 or 3.2 mg L(-1) selenate, all species decreased in biomass with increasing Mo supply. Selenium did not impact biomass at the supplied levels. All Astragali accumulated Mo upwards of 0.1% of dry weight. Selenium levels were up to 0.08% in Astragalus racemosus and 0.04% Se in the other species. Overall, there was no correlation between Se hyperaccumulation and Mo accumulation capacity. However, the hyperaccumulators and nonaccumulators differed in some respects. While none of the species had a higher tissue Mo to sulfur (S) ratio than the growth medium, nonaccumulators had a higher Mo/S ratio than hyperaccumulators. Also, while molybdate and selenate reduced S accumulation in nonaccumulators, it did not in hyperaccumulators. Furthermore, A. racemosus had a higher Se/S ratio than its medium, while the other species did not. Additionally, Mo and Se treatment affected S levels in nonaccumulators, but not in hyperaccumulators. In conclusion, there is no evidence of a link between Se and Mo accumulation and tolerance in Astragalus. Sulfate transporters in hyperaccumulating Astragali appear to have higher sulfate specificity over other oxyanions, compared to nonaccumulators, and A. racemosus may have a transporter with enhanced selenate specificity relative to sulfate or molybdate.

  15. Hypersensitivity to molybdenum as a possible trigger of ANA-negative systemic lupus erythematosus.

    PubMed Central

    Federmann, M; Morell, B; Graetz, G; Wyss, M; Elsner, P; von Thiessen, R; Wüthrich, B; Grob, D

    1994-01-01

    After implantation of two metal plates a 24 year old woman developed fever of unknown origin and successively more symptoms of an ANA-negative systemic lupus erythematosus (SLE). These symptoms resolved after removal of the plates and recurred during patch testing of the metal components, which showed a reaction to molybdenum. A lymphocyte transformation test indicated a delayed-type hypersensitivity to molybdenum. Subsequent progressive flare ups of SLE appeared without molybdenum reexposure. This is the first report suggesting the existence of a hypersensitivity to molybdenum, which may act as another environmental trigger for SLE. PMID:8037499

  16. Tc-99 Ion Exchange Resin Testing

    SciTech Connect

    Valenta, Michelle M.; Parker, Kent E.; Pierce, Eric M.

    2010-08-01

    Pacific Northwest National Laboratory was contracted by CHPRC to evaluate the release of 99Tc from spent resin used to treat water from well 299-W15-765 and stored for several years. The key questions to be answered are: 1) does 99Tc readily release from the spent ion exchange resin after being in storage for several years; 2) if hot water stripping is used to remove the co-contaminant carbon tetrachloride, will 99Tc that has been sequestered by the resin be released; and 3) can spent resin be encapsulated into a cementitious waste form; if so, how much 99Tc would be released from the weathering of the monolith waste form? The results from the long term stability leach test results confirm that the resin is not releasing a significant amount of the sequestered 99Tc, evident by the less than 0.02% of the total 99Tc loaded being identified in the solution. Furthermore, it is possible that the measured 99Tc concentration is the result of 99Tc contained in the pore spaces of the resin. In addition to these results, analyses conducted to examine the impact of hot water on the release of 99Tc suggest that only a small percentage of the total is being released. This suggest that hot water stripping to remove carbon tetrachloride will not have a significant affect on the resin’s ability to hold-on to sequestered 99Tc. Finally, encapsulation of spent resin in a cementitious material may be a viable disposal option, but additional tests are needed to examine the extent of physical degradation caused by moisture loss and the effect this degradation process can have on the release of 99Tc.

  17. Process R&D for Particle Size Control of Molybdenum Oxide

    SciTech Connect

    Sen, Sujat; Dzwiniel, Trevor; Pupek, Krzysztof; Krumdick, Gregory; Tkac, Peter; Vandegrift, George F.

    2016-12-01

    The primary goal of this study was to produce MoO3 powder with a particle size range of 50 to 200 μm for use in targets for production of the medical isotope 99Mo. Molybdenum metal powder is commercially produced by thermal reduction of oxides in a hydrogen atmosphere. The most common source material is MoO3, which is derived by the thermal decomposition of ammonium heptamolybdate (AHM). However, the particle size of the currently produced MoO3 is too small, resulting in Mo powder that is too fine to properly sinter and press into the desired target. In this study, effects of heating rate, heating temperature, gas type, gas flow rate, and isothermal heating were investigated for the decomposition of AHM. The main conclusions were as follows: lower heating rate (2-10°C/min) minimizes breakdown of aggregates, recrystallized samples with millimeter-sized aggregates are resistant to various heat treatments, extended isothermal heating at >600°C leads to significant sintering, and inert gas and high gas flow rate (up to 2000 ml/min) did not significantly affect particle size distribution or composition. In addition, attempts to recover AHM from an aqueous solution by several methods (spray drying, precipitation, and low temperature crystallization) failed to achieve the desired particle size range of 50 to 200 μm. Further studies are planned.

  18. Nanowire CdS-CdTe solar cells with molybdenum oxide as contact

    DOE PAGES

    Dang, Hongmei; Singh, Vijay P.

    2015-10-06

    Using a 10 nm thick molybdenum oxide (MoO3-x) layer as a transparent and low barrier contact to p-CdTe, we demonstrate nanowire CdS-CdTe solar cells with a power conversion efficiency of 11% under front side illumination. Annealing the as-deposited MoO3 film in N2 resulted in a reduction of the cell’s series resistance, from 9.97 Ω/cm2 to 7.69 Ω/cm2, and increase in efficiency from 9.9% to 11%. Under illumination from the back, the MoO3-x/Au side, the nanowire solar cells yielded Jsc of 21 mA/cm2 and efficiency of 8.67%. Our results demonstrate use of a thin layer transition metal oxide as a potentialmore » way for a transparent back contact to nanowire CdS-CdTe solar cells. As a result, this work has implications toward enabling a novel superstrate structure nanowire CdS-CdTe solar cell on Al foil substrate by a low cost roll-to roll fabrication process.« less

  19. Nanowire CdS-CdTe solar cells with molybdenum oxide as contact

    SciTech Connect

    Dang, Hongmei; Singh, Vijay P.

    2015-10-06

    Using a 10 nm thick molybdenum oxide (MoO3-x) layer as a transparent and low barrier contact to p-CdTe, we demonstrate nanowire CdS-CdTe solar cells with a power conversion efficiency of 11% under front side illumination. Annealing the as-deposited MoO3 film in N2 resulted in a reduction of the cell’s series resistance, from 9.97 Ω/cm2 to 7.69 Ω/cm2, and increase in efficiency from 9.9% to 11%. Under illumination from the back, the MoO3-x/Au side, the nanowire solar cells yielded Jsc of 21 mA/cm2 and efficiency of 8.67%. Our results demonstrate use of a thin layer transition metal oxide as a potential way for a transparent back contact to nanowire CdS-CdTe solar cells. As a result, this work has implications toward enabling a novel superstrate structure nanowire CdS-CdTe solar cell on Al foil substrate by a low cost roll-to roll fabrication process.

  20. Nanowire CdS-CdTe Solar Cells with Molybdenum Oxide as Contact.

    PubMed

    Dang, Hongmei; Singh, Vijay P

    2015-10-06

    Using a 10 nm thick molybdenum oxide (MoO3-x) layer as a transparent and low barrier contact to p-CdTe, we demonstrate nanowire CdS-CdTe solar cells with a power conversion efficiency of 11% under front side illumination. Annealing the as-deposited MoO3 film in N2 resulted in a reduction of the cell's series resistance, from 9.97 Ω/cm(2) to 7.69 Ω/cm(2), and increase in efficiency from 9.9% to 11%. Under illumination from the back, the MoO3-x/Au side, the nanowire solar cells yielded Jsc of 21 mA/cm(2) and efficiency of 8.67%. Our results demonstrate use of a thin layer transition metal oxide as a potential way for a transparent back contact to nanowire CdS-CdTe solar cells. This work has implications toward enabling a novel superstrate structure nanowire CdS-CdTe solar cell on Al foil substrate by a low cost roll-to roll fabrication process.

  1. Nanowire CdS-CdTe Solar Cells with Molybdenum Oxide as Contact

    NASA Astrophysics Data System (ADS)

    Dang, Hongmei; Singh, Vijay P.

    2015-10-01

    Using a 10 nm thick molybdenum oxide (MoO3-x) layer as a transparent and low barrier contact to p-CdTe, we demonstrate nanowire CdS-CdTe solar cells with a power conversion efficiency of 11% under front side illumination. Annealing the as-deposited MoO3 film in N2 resulted in a reduction of the cell’s series resistance, from 9.97 Ω/cm2 to 7.69 Ω/cm2, and increase in efficiency from 9.9% to 11%. Under illumination from the back, the MoO3-x/Au side, the nanowire solar cells yielded Jsc of 21 mA/cm2 and efficiency of 8.67%. Our results demonstrate use of a thin layer transition metal oxide as a potential way for a transparent back contact to nanowire CdS-CdTe solar cells. This work has implications toward enabling a novel superstrate structure nanowire CdS-CdTe solar cell on Al foil substrate by a low cost roll-to roll fabrication process.

  2. Nanowire CdS-CdTe Solar Cells with Molybdenum Oxide as Contact

    PubMed Central

    Dang, Hongmei; Singh, Vijay P.

    2015-01-01

    Using a 10 nm thick molybdenum oxide (MoO3−x) layer as a transparent and low barrier contact to p-CdTe, we demonstrate nanowire CdS-CdTe solar cells with a power conversion efficiency of 11% under front side illumination. Annealing the as-deposited MoO3 film in N2 resulted in a reduction of the cell’s series resistance, from 9.97 Ω/cm2 to 7.69 Ω/cm2, and increase in efficiency from 9.9% to 11%. Under illumination from the back, the MoO3−x/Au side, the nanowire solar cells yielded Jsc of 21 mA/cm2 and efficiency of 8.67%. Our results demonstrate use of a thin layer transition metal oxide as a potential way for a transparent back contact to nanowire CdS-CdTe solar cells. This work has implications toward enabling a novel superstrate structure nanowire CdS-CdTe solar cell on Al foil substrate by a low cost roll-to roll fabrication process. PMID:26439839

  3. 14 CFR 99.41 - General.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false General. 99.41 Section 99.41 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SECURITY CONTROL OF AIR TRAFFIC Designated Air Defense Identification Zones §...

  4. 14 CFR 99.45 - Alaska ADIZ.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Alaska ADIZ. 99.45 Section 99.45 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SECURITY CONTROL OF AIR TRAFFIC Designated Air Defense...

  5. 7 CFR 1956.99 - Exception authority.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 14 2010-01-01 2009-01-01 true Exception authority. 1956.99 Section 1956.99 Agriculture Regulations of the Department of Agriculture (Continued) RURAL HOUSING SERVICE, RURAL BUSINESS...) PROGRAM REGULATIONS (CONTINUED) DEBT SETTLEMENT Debt Settlement-Farm Loan Programs and...

  6. 14 CFR 99.47 - Guam ADIZ.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Guam ADIZ. 99.47 Section 99.47 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND..., 145°11′21″ E; then to the point of origin. (b) Outer boundary. The area bounded by a circle with...

  7. 7 CFR 1786.99 - Eligibility criteria.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 12 2013-01-01 2013-01-01 false Eligibility criteria. 1786.99 Section 1786.99 Agriculture Regulations of the Department of Agriculture (Continued) RURAL UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE (CONTINUED) PREPAYMENT OF RUS GUARANTEED AND INSURED LOANS TO ELECTRIC AND TELEPHONE...

  8. 45 CFR 99.31 - Posthearing briefs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 1 2012-10-01 2012-10-01 false Posthearing briefs. 99.31 Section 99.31 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PROCEDURE FOR HEARINGS FOR THE... fact and conclusions of law. The presiding officer shall also fix the time for reply briefs,...

  9. 45 CFR 99.31 - Posthearing briefs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Posthearing briefs. 99.31 Section 99.31 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PROCEDURE FOR HEARINGS FOR THE... fact and conclusions of law. The presiding officer shall also fix the time for reply briefs,...

  10. Tc-99m Labeled carrier for imaging

    DOEpatents

    Henze, Eberhard

    1984-01-01

    Novel radionuclide imaging agents, having particular application for lymphangiography are provided by non-covalently binding Tc-99m to a pharmaceutically acceptable cross-linked polysaccharide. Upon injection of the Tc-99m labeled polysaccharide into the blood stream, optimum contrast can be obtained within one hour.

  11. 10 CFR 51.99 - [Reserved

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 2 2013-01-01 2013-01-01 false 51.99 Section 51.99 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) ENVIRONMENTAL PROTECTION REGULATIONS FOR DOMESTIC LICENSING AND RELATED REGULATORY FUNCTIONS National Environmental Policy Act-Regulations Implementing Section 102(2) Final Environmental...

  12. 10 CFR 51.99 - [Reserved

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 2 2011-01-01 2011-01-01 false 51.99 Section 51.99 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) ENVIRONMENTAL PROTECTION REGULATIONS FOR DOMESTIC LICENSING AND RELATED REGULATORY FUNCTIONS National Environmental Policy Act-Regulations Implementing Section 102(2) Final Environmental...

  13. 10 CFR 51.99 - [Reserved

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 2 2012-01-01 2012-01-01 false 51.99 Section 51.99 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) ENVIRONMENTAL PROTECTION REGULATIONS FOR DOMESTIC LICENSING AND RELATED REGULATORY FUNCTIONS National Environmental Policy Act-Regulations Implementing Section 102(2) Final Environmental...

  14. 10 CFR 51.99 - [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 2 2014-01-01 2014-01-01 false 51.99 Section 51.99 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) ENVIRONMENTAL PROTECTION REGULATIONS FOR DOMESTIC LICENSING AND RELATED REGULATORY FUNCTIONS National Environmental Policy Act-Regulations Implementing Section 102(2) Final Environmental...

  15. NARSTO SOS99NASH WIND PROFILER DATA

    Atmospheric Science Data Center

    2014-04-25

    NARSTO SOS99NASH WIND PROFILER DATA Project Title:  NARSTO ... Platform:  Ground Station Instrument:  Wind Profiler Location:  Nashville, Tennessee Spatial ... Data Guide Documents:  SOS99Nash Wind Profiler Guide Related Data:  Southern Oxidants ...

  16. 10 CFR 51.99 - [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 2 2010-01-01 2010-01-01 false 51.99 Section 51.99 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) ENVIRONMENTAL PROTECTION REGULATIONS FOR DOMESTIC LICENSING AND RELATED REGULATORY FUNCTIONS National Environmental Policy Act-Regulations Implementing Section 102(2) Final Environmental...

  17. 29 CFR 99.310 - Financial statements.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 1 2012-07-01 2012-07-01 false Financial statements. 99.310 Section 99.310 Labor Office of....310 Financial statements. (a) Financial statements. The auditee shall prepare financial statements that reflect its financial position, results of operations or changes in net assets, and,...

  18. 29 CFR 99.310 - Financial statements.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 1 2014-07-01 2013-07-01 true Financial statements. 99.310 Section 99.310 Labor Office of....310 Financial statements. (a) Financial statements. The auditee shall prepare financial statements that reflect its financial position, results of operations or changes in net assets, and,...

  19. Scintillating 99Tc Selective Ion Exchange Resins

    SciTech Connect

    Mitchell Greenhalgh; Richard D. Tillotson

    2012-07-01

    Scintillating technetium (99Tc) selective ion exchange resins have been developed and evaluated for equilibrium capacities and detection efficiencies. These resins can be utilized for the in-situ concentration and detection of low levels of pertechnetate anions (99TcO4-) in natural waters. Three different polystyrene type resin support materials were impregnated with varying amounts of tricaprylmethylammonium chloride (Aliquat 336) extractant, several different scintillating fluors and wavelength shifters. The prepared resins were contacted batch-wise to equilibrium over a wide range of 99TcO4- concentrations in natural water. The measured capacities were used to develop Langmuir adsorption isotherms for each resin. 99Tc detection efficiencies were determined and up to 71.4 ± 2.6% was achieved with some resins. The results demonstrate that a low level detection limit for 99TcO4- in natural waters can be realized.

  20. Images of liposarcoma using technetium-99m bleomycin and technetium (V)-99m DMSA

    SciTech Connect

    Ohta, H.; Shane, F.I.; Endo, K.; Torizuka, K.; Horiuchi, K.; Yokoyama, A.; Ishii, M.

    1986-12-01

    The effectiveness of Tc-99m bleomycin (BLM) and Tc(V)-99m DMSA are compared with that of Ga-67 citrate, which is currently the most widely used agent. In four patients with lipomatous tumors, the clinical significance of tumor imaging with each of these three agents is discussed and compared. Results indicate that both Tc-99m BLM and Tc(V)-99m DMSA are superior in detecting the extension or localization of liposarcomas.

  1. 9. PHOTOCOPY OF PHOTOGRAPH OF BUILDINGS 99 AND 99A WITH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. PHOTOCOPY OF PHOTOGRAPH OF BUILDINGS 99 AND 99A WITH PERIOD FIRE FIGHTING VEHICLE AND PERSONNEL. HOSE DRYING TOWER OF 99A HAS YET TO BE LOWERED IN HEIGHT. DATE OF PHOTOGRAPH UNKNOWN. (4x5 in neg.) - Mare Island Naval Shipyard, Fire House Annex, Vallejo, Solano County, CA

  2. Inorganic polarography in organic solvents-II: polarographic examination of the molybdenum(V) thiocyanate complex in diethyl ether.

    PubMed

    Afghan, B K; Dagnall, R M

    1967-02-01

    A procedure involving the solvent extraction of molybdenum(V) thiocyanate into diethyl ether followed by a direct polarographic examination of the organic phase offers a selective method for the determination of molybdenum down to 0.5 ppm. Only molybdenum, amongst 21 elements examined, is observed to give a reduction wave under the recommended conditions. The method is evaluated with respect to various experimental factors and is applied to the determination of molybdenum in mild and alloy steels.

  3. The effect of molybdenum on the in vitro development of mouse preimplantation embryos.

    PubMed

    Bi, Cong-Ming; Zhang, Yu-Ling; Liu, Feng-Jun; Zhou, Tie-Zhong; Yang, Zi-Jun; Gao, Shen-Yang; Wang, Shu-De; Chen, Xiao-Li; Zhai, Xiao-Wei; Ma, Xue-Gang; Jin, Li-Jun; Wang, Shen

    2013-04-01

    The object of this study was to investigate the effect of molybdenum on the development of mouse preimplantation embryos cultured in vitro. Zygotes were flushed from one outbred mouse strain (Kunming), and then were cultured in potassium simplex optimized medium (KSOM) containing 0, 5, 10, 20, 40, 80, 120, and 160 µg/ml of molybdenum for 5 days until the mid-blastocyst stage. The addition of ≤ 20 µg/ml molybdenum did not affect the blastocyst and birth rates. Molybdenum at doses of 40 µg/ml and higher significantly decreased the cleavage, blastocyst and birth rates, the average cell number, and significantly increased the proportion of degenerative blastocysts. At 120 µg/ml molybdenum inhibited the blastocysts development to birth. At 160 µg/ml molybdenum caused overall developmental arrest (up to 16-cells) of embryos and their massive degeneration. In conclusion, molybdenum negatively affected the development of embryos in a dose-dependent manner. With lower doses (≤ 20 µg/ml), mouse embryos were not apparently damaged. With very high doses (≥ 40 µg/ml), embryo quality significantly decreased. This assessment of the effect of molybdenum on the preimplantation embryo is an initial survey of toxicological risk.

  4. Synthesis of nanocrystalline molybdenum carbide (Mo{sub 2}C) by solution route

    SciTech Connect

    Patel, Manish Subrahmanyam, J.

    2008-08-04

    Nanocrystalline molybdenum carbide (Mo{sub 2}C) of less than 10 nm size was synthesized by solution route. The process temperature and composition of raw materials were optimized by thermodynamic equilibrium calculation. The raw materials as well as synthesized nanocrystalline molybdenum carbide were characterized by X-ray diffraction (XRD) and thermogravimetric analysis/differential thermal analysis (TGA/DTA)

  5. Conceptual design of a new homogeneous reactor for medical radioisotope Mo-99/Tc-99m production

    SciTech Connect

    Liem, Peng Hong; Tran, Hoai Nam; Sembiring, Tagor Malem; Arbie, Bakri

    2014-09-30

    To partly solve the global and regional shortages of Mo-99 supply, a conceptual design of a nitrate-fuel-solution based homogeneous reactor dedicated for Mo-99/Tc-99m medical radioisotope production is proposed. The modified LEU Cintichem process for Mo-99 extraction which has been licensed and demonstrated commercially for decades by BATAN is taken into account as a key design consideration. The design characteristics and main parameters are identified and the advantageous aspects are shown by comparing with the BATAN's existing Mo-99 supply chain which uses a heterogeneous reactor (RSG GAS multipurpose reactor)

  6. Conceptual design of a new homogeneous reactor for medical radioisotope Mo-99/Tc-99m production

    NASA Astrophysics Data System (ADS)

    Liem, Peng Hong; Tran, Hoai Nam; Sembiring, Tagor Malem; Arbie, Bakri

    2014-09-01

    To partly solve the global and regional shortages of Mo-99 supply, a conceptual design of a nitrate-fuel-solution based homogeneous reactor dedicated for Mo-99/Tc-99m medical radioisotope production is proposed. The modified LEU Cintichem process for Mo-99 extraction which has been licensed and demonstrated commercially for decades by BATAN is taken into account as a key design consideration. The design characteristics and main parameters are identified and the advantageous aspects are shown by comparing with the BATAN's existing Mo-99 supply chain which uses a heterogeneous reactor (RSG GAS multipurpose reactor).

  7. 40 CFR 440.100 - Applicability; description of the copper, lead, zinc, gold, silver, and molybdenum ores subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... copper, lead, zinc, gold, silver, and molybdenum ores subcategory. 440.100 Section 440.100 Protection of... DRESSING POINT SOURCE CATEGORY Copper, Lead, Zinc, Gold, Silver, and Molybdenum Ores Subcategory § 440.100 Applicability; description of the copper, lead, zinc, gold, silver, and molybdenum ores subcategory. (a)...

  8. 40 CFR 440.100 - Applicability; description of the copper, lead, zinc, gold, silver, and molybdenum ores subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... copper, lead, zinc, gold, silver, and molybdenum ores subcategory. 440.100 Section 440.100 Protection of... DRESSING POINT SOURCE CATEGORY Copper, Lead, Zinc, Gold, Silver, and Molybdenum Ores Subcategory § 440.100 Applicability; description of the copper, lead, zinc, gold, silver, and molybdenum ores subcategory. (a)...

  9. 40 CFR 440.100 - Applicability; description of the copper, lead, zinc, gold, silver, and molybdenum ores subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... copper, lead, zinc, gold, silver, and molybdenum ores subcategory. 440.100 Section 440.100 Protection of... MINING AND DRESSING POINT SOURCE CATEGORY Copper, Lead, Zinc, Gold, Silver, and Molybdenum Ores Subcategory § 440.100 Applicability; description of the copper, lead, zinc, gold, silver, and molybdenum...

  10. 40 CFR 440.100 - Applicability; description of the copper, lead, zinc, gold, silver, and molybdenum ores subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... copper, lead, zinc, gold, silver, and molybdenum ores subcategory. 440.100 Section 440.100 Protection of... MINING AND DRESSING POINT SOURCE CATEGORY Copper, Lead, Zinc, Gold, Silver, and Molybdenum Ores Subcategory § 440.100 Applicability; description of the copper, lead, zinc, gold, silver, and molybdenum...

  11. Pyranopterin Coordination Controls Molybdenum Electrochemistry in Escherichia coli Nitrate Reductase.

    PubMed

    Wu, Sheng-Yi; Rothery, Richard A; Weiner, Joel H

    2015-10-09

    We test the hypothesis that pyranopterin (PPT) coordination plays a critical role in defining molybdenum active site redox chemistry and reactivity in the mononuclear molybdoenzymes. The molybdenum atom of Escherichia coli nitrate reductase A (NarGHI) is coordinated by two PPT-dithiolene chelates that are defined as proximal and distal based on their proximity to a [4Fe-4S] cluster known as FS0. We examined variants of two sets of residues involved in PPT coordination: (i) those interacting directly or indirectly with the pyran oxygen of the bicyclic distal PPT (NarG-Ser(719), NarG-His(1163), and NarG-His(1184)); and (ii) those involved in bridging the two PPTs and stabilizing the oxidation state of the proximal PPT (NarG-His(1092) and NarG-His(1098)). A S719A variant has essentially no effect on the overall Mo(VI/IV) reduction potential, whereas the H1163A and H1184A variants elicit large effects (ΔEm values of -88 and -36 mV, respectively). Ala variants of His(1092) and His(1098) also elicit large ΔEm values of -143 and -101 mV, respectively. An Arg variant of His(1092) elicits a small ΔEm of +18 mV on the Mo(VI/IV) reduction potential. There is a linear correlation between the molybdenum Em value and both enzyme activity and the ability to support anaerobic respiratory growth on nitrate. These data support a non-innocent role for the PPT moieties in controlling active site metal redox chemistry and catalysis.

  12. Molybdenum intake of adults in Germany and Mexico.

    PubMed

    Holzinger, S; Anke, M; Röhrig, B; Gonzalez, D

    1998-03-01

    Molybdenum is an essential micronutrient. It plays a complex role in the ecosystem, because the metal is a part of a cofactor for several important enzymes in human, animal and plant metabolism. The physiological requirement for this element is relatively low. Our investigations were aimed at determining the Mo intake of adults in Germany and Mexico by means of duplicate portion technique. Molybdenum was estimated in the food duplicate samples by inductively coupled plasma atomic emission spectrometry. In 1988, 1992 and 1996 the Mo consumption of humans was investigated in 14 test groups of persons with mixed diets. Each test population consisted of seven men and seven women. Furthermore, in 1996 the Mo intake of 10 female and 10 male vegetarians and of two Mexican test groups was also determined. Different factors, such as sex, time of investigation, location and eating habits have an effect on the individual Mo intake, Molybdenum intake of adults with mixed diets has increased significantly from 1988 to 1996. Furthermore, results of our study showed that Mo intake of German adults differs depending on location and the kind of diet. German women with a mixed diet consumed 89 micrograms d-1 in 1996 and men 100 micrograms d-1. In comparison, female and male vegetarians consumed 179 micrograms d-1 and 170 micrograms d-1, respectively. There was a significant difference in Mo consumption between German and Mexican test persons. Mexican women consumed on average 162 micrograms d-1 and Mexican men 208 micrograms d-1. The Mo requirement of adults amounts to about 25 micrograms d-1. Our investigations showed that the Mo requirement is met by normal intake. An intake of 150 micrograms kg-1 body weight may be toxic for humans. Therefore, people in Germany and Mexico are not endangered by Mo exposure.

  13. Evaluation of Molybdenum as a Surrogate for Iridium in the GPHS Weld Development

    SciTech Connect

    Stine, Andrew Martin; Pierce, Stanley W.; Moniz, Paul F.

    2015-10-17

    The welding equipment used for welding iridium containers (clads) at Los Alamos National Laboratory is twenty five years old and is undergoing an upgrade. With the upgrade, there is a requirement for requalification of the welding process, and the opportunity for process improvement. Testing of the new system and requalification will require several welds on iridium test parts and clads, and any efforts to improve the process will add to the need for iridium parts. The extreme high cost of iridium imposes a severe limitation on the extent of test welding that can be done. The 2 inch diameter, 0.027 inch thick, iridium blank disc that the clad cup is formed from, is useful for initial weld trials, but it costs $5000. The development clad sets needed for final tests and requalification cost $15,000 per set. A solution to iridium cost issue would be to do the majority of the weld development on a less expensive surrogate metal with similar weld characteristics. One such metal is molybdenum. Since its melting index (melting temperature x thermal conductivity) is closest to iridium, welds on molybdenum should be similar in size for a given weld power level. Molybdenum is inexpensive; a single 2 inch molybdenum disc costs only $9. In order to evaluate molybdenum as a surrogate for iridium, GTA welds were first developed to provide full penetration on 0.030 inch thick molybdenum discs at speeds of 20, 25, and 30 inches per minute (ipm). These weld parameters were then repeated on the standard 0.027 inch thick iridium blanks. The top surface and bottom surface (root) width and grain structure of the molybdenum and iridium welds were compared, and similarities were evident between the two metals. Due to material and thickness differences, the iridium welds were approximately 35% wider than the molybdenum welds. A reduction in iridium weld current of 35% produce welds slightly smaller than the molybdenum welds yet showed that current could be scaled according to molybdenum

  14. Procedure for Uranium-Molybdenum Density Measurements and Porosity Determination

    SciTech Connect

    Prabhakaran, Ramprashad; Devaraj, Arun; Joshi, Vineet V.; Lavender, Curt A.

    2016-08-13

    The purpose of this document is to provide guidelines for preparing uranium-molybdenum (U-Mo) specimens, performing density measurements, and computing sample porosity. Typical specimens (solids) will be sheared to small rectangular foils, disks, or pieces of metal. A mass balance, solid density determination kit, and a liquid of known density will be used to determine the density of U-Mo specimens using the Archimedes principle. A standard test weight of known density would be used to verify proper operation of the system. By measuring the density of a U-Mo sample, it is possible to determine its porosity.

  15. Ultrafast Optical Microscopy of Single Monolayer Molybdenum Disulfide Flakes

    SciTech Connect

    Seo, Minah; Yamaguchi, Hisato; Mohite, Aditya D.; Boubanga-Tombet, Stephane; Blancon, Jean-Christophe; Najmaei, Sina; Ajayan, Pulickel M.; Lou, Jun; Taylor, Antoinette J.; Prasankumar, Rohit P.

    2016-02-15

    We performed ultrafast optical microscopy on single flakes of atomically thin CVD-grown molybdenum disulfide, using non-degenerate femtosecond pump-probe spectroscopy to excite and probe carriers above and below the indirect and direct band gaps. These measurements reveal the influence of layer thickness on carrier dynamics when probing near the band gap. Furthermore, fluence-dependent measurements indicate that carrier relaxation is primarily influenced by surface-related defect and trap states after above-bandgap photoexcitation. Furthermore, the ability to probe femtosecond carrier dynamics in individual flakes can thus give much insight into light-matter interactions in these two-dimensional nanosystems.

  16. A 65 Ah rechargeable lithium molybdenum disulfide battery

    NASA Technical Reports Server (NTRS)

    Brandt, K.

    1986-01-01

    A rechargeable lithium molybdenum disulfide battery which has a number of superior performance characteristics which includes a high energy density, a high power density, and a long charge retention time was developed. The first cell sizes developed included a C size cell and an AA size cell. Over the last two years, a project to demonstrate the feasibility of the scale up to this technology to a BC size cell with 65 Ah capacity was undertaken. The objective was to develop, build, and test a .6 kWh storage battery consisting of 6 BC cells in series.

  17. Physicochemical investigation of NiAl with small molybdenum additions

    NASA Technical Reports Server (NTRS)

    Troshkina, V. A.; Kucherenko, L. A.; Fadeeva, V. I.; Aristova, N. M.

    1982-01-01

    Specimens of four cast NiAl alloys, three of them containing 0.5, 1.0 and 1.5 at. % Mo., were homogenized for 10, 10, and 140 hr at 1373, 1523 and 1273 K, respectively, then kept at 1073, 1173 and 1323 K for 60, 120 and 3 hr, respectively, and quenched in icy water. The precipitation of a metastable Ni3Mo phase was observed at temperatures between 1073 and 1523 K. Molybdenum substituted for nickel was found to inhibit the lattice disordering in NiAl at 1073 and 1523 K.

  18. Processing-Structure Correlation in DC Sputtered Molybdenum Thin Films

    NASA Astrophysics Data System (ADS)

    Khan, Majid; Islam, Mohammad; Akram, Aftab; Manzoor, Umair

    2013-12-01

    Molybdenum thin films were sputter deposited under different conditions of DC power and chamber pressure. The structure and topography of the films were investigated using AFM, SEM and XRD techniques. Van der Pauw method and tape test were employed to determine electrical resistivity and interfacial strength to the substrate, respectively. All the films are of sub-micron thickness with maximum growth rate of 78 nm/min and crystallite size in the range of 4 to 21 nm. The films produced at high power and low pressure exhibit compressive residual strains, low electrical resistivity and poor adhesion to the glass substrate, whereas the converse is true for films produced at high pressure.

  19. Temperature in molybdenum at high shock pressure: Experiment and theory

    NASA Astrophysics Data System (ADS)

    Zhang, Xiu-lu; Liu, Zhong-li; Gu, Yun-jun; Cai, Ling-cang; Jing, Fu-qian

    2008-09-01

    Shock temperature of molybdenum is deduced to be 7853±813 K from release temperature at 374 GPa via pyrometry experiment. Theoretically, temperatures along the Hügoniot are calculated up to pressures of 500 GPa, over the shock melting pressure region, with contributions from electrons considered. At low pressures, the calculated results are consistent with NRS temperature measurements and pyrometry measurements, and accord with SESAME EOS and theoretical calculations taking the strength of the sample into account. At pressures above 100 GPa the results are much different from calculations without the contribution from the electrons, but consistent with the shock temperature deduced from experimental results in this work.

  20. Ultrafast Optical Microscopy of Single Monolayer Molybdenum Disulfide Flakes

    PubMed Central

    Seo, Minah; Yamaguchi, Hisato; Mohite, Aditya D.; Boubanga-Tombet, Stephane; Blancon, Jean-Christophe; Najmaei, Sina; Ajayan, Pulickel M.; Lou, Jun; Taylor, Antoinette J.; Prasankumar, Rohit P.

    2016-01-01

    We have performed ultrafast optical microscopy on single flakes of atomically thin CVD-grown molybdenum disulfide, using non-degenerate femtosecond pump-probe spectroscopy to excite and probe carriers above and below the indirect and direct band gaps. These measurements reveal the influence of layer thickness on carrier dynamics when probing near the band gap. Furthermore, fluence-dependent measurements indicate that carrier relaxation is primarily influenced by surface-related defect and trap states after above-bandgap photoexcitation. The ability to probe femtosecond carrier dynamics in individual flakes can thus give much insight into light-matter interactions in these two-dimensional nanosystems. PMID:26876194

  1. The prototype detector for MOON (Molybdenum Observatory Of Neutrinos)

    NASA Astrophysics Data System (ADS)

    Moon Collaboration; Nakamura, H.; Ogama, T.; Shimada, Y.; Sugaya, Y.

    2005-06-01

    The MOON (Molybdenum Observatory Of Neutrinos), as an extension of ELEGANT V, is a hybrid ββ and solar neutrino experiment with 100Mo. It aims at measuring neutrino-less ββ decay with sensitivity to the Majorana mass of the order of 50 meV and charged current interactions of 7Be solar neutrinos. One detector option of MOON is a super-module with one ton of 100Mo foils and fiber-plate scintillator planes. A prototype detector, MOON-1 with ˜ 0.5 kg of Mo foils, is being constructed. Simulation studies, test experiments and the status of MOON are discussed.

  2. Leaching of molybdenum and arsenic from uranium ore and mill tailings

    USGS Publications Warehouse

    Landa, E.R.

    1984-01-01

    A sequential, selective extraction procedure was used to assess the effects of sulfuric acid milling on the geochemical associations of molybdenum and arsenic in a uranium ore blend, and the tailings derived therefrom. The milling process removed about 21% of the molybdenum and 53% of the arsenic initially present in the ore. While about one-half of the molybdenum in the ore was water soluble, only about 14% existed in this form in the tailings. The major portion of the extractable molybdenum in the tailings appears to be associated with hydrous oxides of iron, and with alkaline earth sulfate precipitates. In contrast with the pattern seen for molybdenum, the partitioning of arsenic into the various extractable fractions differs little between the ore and the tailings. ?? 1984.

  3. Influence of Chromium and Molybdenum on the Corrosion of Nickel Based Alloys

    SciTech Connect

    Hayes, J R; Gray, J; Szmodis, A W; Orme, C A

    2005-08-02

    The addition of chromium and molybdenum to nickel creates alloys with exceptional corrosion resistance in a diverse range of environments. This study examines the complementary roles of Cr and Mo in Ni alloy passivation. Four nickel alloys with varying amounts of chromium and molybdenum were studied in 1 molar salt solutions over a broad pH range. The passive corrosion and breakdown behavior of the alloys suggests that chromium is the primary element influencing general corrosion resistance. The breakdown potential was nearly independent of molybdenum content, while the repassivation potential is strongly dependant on the molybdenum content. This indicates that chromium plays a strong role in maintaining the passivity of the alloy, while molybdenum acts to stabilize the passive film after a localized breakdown event.

  4. Acidic ammonothermal growth of gallium nitride in a liner-free molybdenum alloy autoclave

    NASA Astrophysics Data System (ADS)

    Malkowski, Thomas F.; Pimputkar, Siddha; Speck, James S.; DenBaars, Steven P.; Nakamura, Shuji

    2016-12-01

    This paper discusses promising materials for use as internal, non-load bearing components as well as molybdenum-based alloys for autoclave structural components for an ammonothermal autoclave. An autoclave was constructed from the commercial titanium-zirconium-molybdenum (TZM) alloy and was found to be chemically inert and mechanically stable under acidic ammonothermal conditions. Preliminary seeded growth of GaN was demonstrated with negligible incorporation of transition metals (including molybdenum) into the grown material (<1017 cm-3). Molybdenum and TZM were exposed to a basic ammonothermal environment, leading to slight degradation through formation of molybdenum nitride powders on their surface at elevated temperatures (T>560 °C). The possibility of a 'universal', inexpensive, liner-free ammonothermal autoclave capable of exposure to basic and acidic chemistry is demonstrated.

  5. Cellulose acetate-based composites with antimicrobial properties from embedded molybdenum trioxide particles.

    PubMed

    Shafaei, S; Dörrstein, J; Guggenbichler, J P; Zollfrank, C

    2017-01-01

    The objective of this research was to develop novel cellulose acetate (biopolymer) composite materials with an excellent antimicrobial activity by embedding molybdenum trioxide particles with unique high specific surface area. High surface area molybdenum trioxide particles were prepared from freshly precipitated molybdenum trioxide dihydrate (MoO3 ·2H2 O) and subsequent calcination at 340°C under H2 /N2 gas. Microbiological evaluation against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were performed applying a roll-on test and excellent antimicrobial activities were determined for composites with embedded anhydrous molybdenum trioxide with a high specific surface area. Cellulose acetate composites comprising MoO3 particles can eliminate three harmful bacteria as a result of the release of protons from the material and surface enlargement of the molybdenum trioxide particles. The findings support a proposed antimicrobial mechanism based on local acidity increase due to large specific surface areas.

  6. Molybdenum and copper levels in white-tailed deer near uranium mines in Texas

    USGS Publications Warehouse

    King, K.A.; LeLeux, J.; Mulhern, B.M.

    1984-01-01

    Molybdenum toxicity, molybdenosis, in ruminant animals has been identified in at least 15 states and in Canada, England, Australia, and New Zealand. In most western states, molybdenosis has been associated with strip-mine spoil deposits. Molybdenum toxicity has been diagnosed in cattle pastured near uranium strip-mine spoils in several Texas counties. Recent reports from hunters and the authors' observations indicated that white-tailed deer (Odocoileus virginianus ) that fed near uranium-mine spoil deposits may also have been exposed to high levels of molybdenum. The objectives of this study were to determine if white-tailed deer from a South Texas uranium mining district were accumulating harmful levels of molybdenum and to compare molybdenum and copper levels with antler development in deer from the mined area vs. an unmined control area.

  7. 32 CFR 552.99 - Applicability.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... in conjunction with Active Army elements, military family members; civilians employed on, visiting... Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY MILITARY RESERVATIONS AND NATIONAL CEMETERIES REGULATIONS AFFECTING MILITARY RESERVATIONS Firearms and Weapons § 552.99 Applicability. (a)...

  8. 32 CFR 552.99 - Applicability.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... in conjunction with Active Army elements, military family members; civilians employed on, visiting... Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY MILITARY RESERVATIONS AND NATIONAL CEMETERIES REGULATIONS AFFECTING MILITARY RESERVATIONS Firearms and Weapons § 552.99 Applicability. (a)...

  9. 32 CFR 552.99 - Applicability.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... in conjunction with Active Army elements, military family members; civilians employed on, visiting... Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY MILITARY RESERVATIONS AND NATIONAL CEMETERIES REGULATIONS AFFECTING MILITARY RESERVATIONS Firearms and Weapons § 552.99 Applicability. (a)...

  10. 50 CFR 665.99 - Area restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES IN THE WESTERN PACIFIC American Samoa Fisheries § 665.99 Area... are no-take MPAs: Landward of the 50 fm (91.5 m) curve around Rose Atoll, as depicted on...

  11. 50 CFR 665.99 - Area restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES IN THE WESTERN PACIFIC American Samoa Fisheries § 665.99 Area... are no-take MPAs: Landward of the 50 fm (91.5 m) curve around Rose Atoll, as depicted on...

  12. Upgrading of a Moroccan deasphalted shale oil over mechanical mixtures of sulfided cobalt-molybdenum and nickel-molybdenum alumina supported catalysts

    SciTech Connect

    Moreau, C.; Geneste, P.; Benyamna, A.; Bennouna, C.

    1994-12-31

    Experimental factorial design was used to study the influence of the different parameters such as the reaction temperature, the hydrogen pressure and the reaction time on the hydroprocessing of a deasphalted shale oil over mechanical mixtures of sulfided cobalt-molybdenum and nickel-molybdenum alumina supported catalysts. It was shown that hydrodesulfurization, hydrodeoxygenation hydrodenitrogenation and hydrodearomatization were more important for high temperature, high pressure and long reaction time operating conditions as generally observed for separate experiments carried under conditions of industrial catalytic tests. The most striking feature was the existence of a promotion effect due to the simultaneous presence of those catalysts mechanical mixtures, i.e. cobalt-molybdenum-rich mixtures are more efficient for hydrodenitrogenation reactions, whereas nickel-molybdenum-rich mixtures exhibit a better activity for hydrodesulfurization and hydrodearomatization reactions, thus confirming first the previous findings in this field concerning the influence of cobalt and nickel promoters and then the general knowledge on the separate behavior of sulfided cobalt-molybdenum and nickel-molybdenum alumina supported catalysts.

  13. Diversification in the Supply Chain of (99)Mo Ensures a Future for (99m)Tc.

    PubMed

    Cutler, Cathy S; Schwarz, Sally W

    2014-07-01

    The uncertain availability of (99m)Tc has become a concern for nuclear medicine departments across the globe. An issue for the United States is that currently it is dependent on a supply of (99m)Tc (from (99)Mo) that is derived solely by production outside the United States. Since the United States uses half the world's (99)Mo production, the U.S. (99)Mo supply chain would be greatly enhanced if a producer were located within the United States. The fragility of the old (99)Mo supply chain is being addressed as new facilities are constructed and new processes are developed to produce (99)Mo without highly enriched uranium. The conversion to low-enriched uranium is necessary to minimize the potential misuse of highly enriched uranium in the world for nonpeaceful means. New production facilities, new methods for the production of (99)Mo, and a new generator elution system for the supply of (99m)Tc are currently being pursued. The progress made in all these areas will be discussed, as they all highlight the need to embrace diversity to ensure that we have a robust and reliable supply of (99m)Tc in the future.

  14. Physical properties about metal matrix FGM of molybdenum and copper

    SciTech Connect

    Nakano, Kouichi; Nishida, Shinichi

    1995-11-01

    Metal matrix composites (MMC) have been made trials to produce by a lot of fabrication processes such as the powder metallurgical method, the plasma spraying, the diffusion bonding, the physical vapor deposition method, the hot isostatic pressing (HIP) etc. In the most cases of these processes, dissimilar materials are combined or bonded directly. The various physical properties are discontinuous at the bonded interface of the dissimilar materials. In order to overcome the problem, functionally gradient materials (FGM) have been considered recently, and have attracted the authors. Its compositions are prepared so that physical properties continuously vary across the bond interface of the dissimilar metals. In this study, a FGM is produced by a new process based on HIP. Copper and molybdenum, which are distinct in the thermo-physical property to each other, are the constitutents for the FGM. This composition have been confirmed by absorbed electron and characteristics X-ray images of each mixed layer for FGM to be uniform or continuous. The following items have been investigated and compared with the linear law of mixture rule: Vickers hardness, thermal expansion, and thermal conductivity at a one-dimensional non-steady state. Those physical properties have been identified to depend on the mixing ratios of copper and molybdenum. Pretty good agreements have been obtained between the experimental data and the calculated values according to the linear law of mixture rule.

  15. Magnetic ordering in lanthanide-molybdenum oxide nanostructure arrays

    NASA Astrophysics Data System (ADS)

    Hagmann, Joseph; Le, Son; Schneemeyer, Lynn; Olsen, Patti; Besara, Tiglet; Siegrist, Theo; Seiler, David; Richter, Curt

    Reduced ternary molybdenum oxides, or bronzes, offer an attractive materials platform to study a wide variety of remarkable physical phenomena in a system with highly varied structural chemistry. Interesting electronic behaviors, such as superconductivity, charge density waves, and magnetism, in these materials arise from the strong hybridization of the 4d states of high-valent Mo with O p orbitals. We investigate a series of molybdenum bronze materials with Lanthanide-Mo16O44 composition that can be described as a three-dimensional array of metallic Mo8O32 nanostructures computationally predicted to contain a single charge with spin 1/2 separated by insulating MoO4 tetrahedra. This study reveals novel magnetic ordering in Lanthanide-Mo16O44 systems arising, not from the inclusion of magnetic elements, but rather from an exchange interaction between cubic Mo8O32 units. Here, we report the magnetometry and transport behaviors of a series of Lanthanide-Mo16O44 materials, emphasizing an observed low-temperature phase transition signifying the onset of antiferromagnetic ordering between the arrayed nanostructures, and relate these behaviors to their experimentally-characterized structures to reveal the intriguing physics of these correlated electronic systems.

  16. Molybdenum-silicon multilayer mirrors for the extreme ultraviolet

    NASA Technical Reports Server (NTRS)

    Barbee, T. W., Jr.; Mrowka, S.; Hetrick, M. C.

    1985-01-01

    Multilayer structures of molybdenum and silicon have been synthesized by sputter deposition onto flat silicon single-crystal silicon substrates and spherically ground (0.5and 22.0-m radii) fused silica substrates; and the reflectivities for 170.4-A (72.8-eV), 160.1-A (77.4-eV), and 228-A (54.4-eV) light measured at near normal incidence. Observed peak values ranged from 26.2 to 78 percent, the highest reflectivities occurring closest to normal incidence. Energy resolutions were about 10 in all cases. Model calculations were performed using optical constants and experimentally determined multilayer structural parameters. In all cases the measured reflectivities were equal to or larger (by up to a factor of 2) than the calculated values, a result attributed to uncertainty in the optical constants used in the calculations. Experimental and calculated angular-peak positions and energy resolutions were in good agreement. The high reflectivities of these molybdenum-silicon structures will make possible application of traditional optics approaches in the EUV and support new developments including free-electron lasers.

  17. Extraction of molybdenum by a supported liquid membrane method.

    PubMed

    Basualto, Carlos; Marchese, José; Valenzuela, Fernando; Acosta, Adolfo

    2003-04-10

    This is a report on the extraction of molybdenum(VI) ions using a supported liquid membrane, prepared by dissolving in kerosene, the extractant Alamine 336 (a long-chain tertiary amine) employed as mobile carrier. A flat hydrophobic microporous membrane was utilised as solid support. Appropriate conditions for Mo(VI) extraction through the liquid membrane were obtained from the results of liquid-liquid extraction and stripping partition experiments. The influence of feed solution acidity, the carrier extractant concentration in the organic liquid film and the content of strip agent on the metal flux through membrane were investigated. It was established that maximal extraction of metal is achieved at a pH 2.0 if sulphuric acid is used in the feed solution and at a pH value over 11.0 if Na(2)CO(3) is used as strip agent. Moreover, the molybdenum extraction through membrane is enhanced when a 0.02 mol l(-1) content of the amine carrier in the organic phase is used. The present paper deals with an equilibrium investigation of the extraction of Mo(VI) by Alamine 336 and its permeation conditions through the liquid membrane, and examines a possible mechanism of extraction.

  18. Optical absorption and transmission in a molybdenum disulfide monolayer

    NASA Astrophysics Data System (ADS)

    Rukelj, Zoran; Štrkalj, Antonio; Despoja, Vito

    2016-09-01

    Our recently proposed theoretical formulation [presented in D. Novko et al., Phys. Rev. B 93, 125413 (2016), 10.1103/PhysRevB.93.125413] is used to study optical absorption and transmission in molybdenum disulfide (MoS2) monolayer as a function of incident photon energy and angle. The investigation is not focused on exploration of well-documented spin-orbit split excitons around optical absorption onset, but rather on the most intensive features in absorption spectrum in the visible and near-ultraviolet photon energy range (1.7 -4 eV ). It is shown that three most intensive peaks, at 2.7, 3.1, and 3.7 eV, result from transitions between Mo(d ) and S(p ) valence and conduction bands and that the character of their charge/current density fluctuations is intrinsically in plane, located in the molybdenum plane. This also implies that MoS2 monolayer is completely transparent when illuminated by grazing incidence p -polarized light. The validity of the presented results is supported by our effective two-band tight-binding model and finally by good agreement with some recent experimental results.

  19. Investigation of adhesion between molybdenum and polysilazane by XPS

    NASA Astrophysics Data System (ADS)

    Amouzou, Dodji; Fourdrinier, Lionel; Sporken, Robert

    2015-07-01

    Here, we investigate the interface between polysilazane (PSZ) coatings and Mo films for understanding adhesion. Two kinds of Mo/PSZ samples are investigated (the well-adhered samples and the non-adhered samples) and the chemical environments of their interfaces are compared. For some investigations, ultra-thin Mo films (2-5 nm) are deposited on PSZ coatings to probe the interface directly by X-ray photoelectron spectroscopy (XPS) and to avoid long sputtering times in depth profiling of Mo films. It was found that the sputtered Mo films systematically adhere well to PSZ coatings. The good adhesion arises from a formation of molybdenum oxycarbonitride or molybdenum carbonitride ceramics through covalent bonding between atoms from PSZ and Mo at the interface. The nature of ceramic newly formed at the interface between PSZ and Mo films depends on deposition conditions and can lead to cohesion failure in PSZ coatings. We demonstrated that the adhesion failure observed for some samples does not occur due to the absence of bonding between atoms at interface of Mo/PSZ but may result from the chemical change.

  20. Toxicity of arsenic, molybdenum and selenium combinations to Ceriodaphnia dubia

    SciTech Connect

    Naddy, R.B. . Dept. of Biology); La Point, T.W.; Klaine, S.J. )

    1995-02-01

    Previous research done on the effects of contaminant mixtures has been evaluated primarily by using acute exposures. While this was an important initial step, characterizing the effects of chronic exposures of these mixtures is more environmentally pragmatic. This study examined the sublethal interactive effects of arsenic (As), molybdenum (Mo), and selenium (Se) on Ceriodaphnia dubia using the three-brood static renewal toxicity test. A complete factorial design experiment using four levels (zero, IC12.5, IC25, and IC50 values) of each metal was performed to investigate the binary and tertiary interactions of these metals on C. Dubia survival and fecundity. Results indicate three-way interactive effects in survival and fecundity with the strongest effect exhibited by Se. Molybdenum and As in binary combinations appear to be strongly antagonistic in their effects on C. dubia, even at their respective IC50 concentrations. However, generally the addition of Se to As-Mo mixtures significantly reduced survival and reproduction. The IC50 concentrations of either Mo or Se significantly reduced fecundity in all binary and tertiary mixtures. All tertiary metal mixtures, except the combination of the IC12.5 concentrations of each metal, significantly reduced C. dubia fecundity.

  1. Grains and grain boundaries in highly crystalline monolayer molybdenum disulphide.

    PubMed

    van der Zande, Arend M; Huang, Pinshane Y; Chenet, Daniel A; Berkelbach, Timothy C; You, YuMeng; Lee, Gwan-Hyoung; Heinz, Tony F; Reichman, David R; Muller, David A; Hone, James C

    2013-06-01

    Recent progress in large-area synthesis of monolayer molybdenum disulphide, a new two-dimensional direct-bandgap semiconductor, is paving the way for applications in atomically thin electronics. Little is known, however, about the microstructure of this material. Here we have refined chemical vapour deposition synthesis to grow highly crystalline islands of monolayer molybdenum disulphide up to 120 μm in size with optical and electrical properties comparable or superior to exfoliated samples. Using transmission electron microscopy, we correlate lattice orientation, edge morphology and crystallinity with island shape to demonstrate that triangular islands are single crystals. The crystals merge to form faceted tilt and mirror twin boundaries that are stitched together by lines of 8- and 4-membered rings. Density functional theory reveals localized mid-gap states arising from these 8-4 defects. We find that mirror twin boundaries cause strong photoluminescence quenching whereas tilt boundaries cause strong enhancement. Meanwhile, mirror twin boundaries slightly increase the measured in-plane electrical conductivity, whereas tilt boundaries slightly decrease the conductivity.

  2. Fabrication and characterization of carbon doped molybdenum oxide nanostructures.

    PubMed

    Wisitsoraat, A; Tuantranont, A; Patthanasettakul, V; Lomas, T

    2009-02-01

    Molybdenum oxide (MoOx) nanostructure has gained considerable attention because of its low-cost fabrication by low-temperature evaporation/condensation technique and its promising properties for applications in the field of catalysts and chemical sensors. However, MoOx has some inferior properties including very high electrical resistivity and instability at elevated temperature. These properties may be improved by means of foreign atom addition into its nanostructure. In this work, we develop a simple mean for doping of MoOx nanostructures by introduction of gas source dopant during evaporation. Carbon doped MoOx nanostructures have been synthesized by MoOx powder evaporation in Argon/Acetylene mixture with varying process parameters. Depending on growth conditions, various nanostructures including, nanorod, nanoplate, nanodots, can be formed with different dimensions and doping concentrations. Structural characterization by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD) indicate that the MoOx based nanostructures are highly crystalline and carbon dopant is successfully incorporated in the structure with controllable concentration. Electrical characterization shows that the electrical conductivity of molybdenum oxide nanostructures can be increased by several orders of magnitude with carbon incorporation.

  3. Sulphur shuttling across a chaperone during molybdenum cofactor maturation.

    PubMed

    Arnoux, Pascal; Ruppelt, Christian; Oudouhou, Flore; Lavergne, Jérôme; Siponen, Marina I; Toci, René; Mendel, Ralf R; Bittner, Florian; Pignol, David; Magalon, Axel; Walburger, Anne

    2015-02-04

    Formate dehydrogenases (FDHs) are of interest as they are natural catalysts that sequester atmospheric CO2, generating reduced carbon compounds with possible uses as fuel. FDHs activity in Escherichia coli strictly requires the sulphurtransferase EcFdhD, which likely transfers sulphur from IscS to the molybdenum cofactor (Mo-bisPGD) of FDHs. Here we show that EcFdhD binds Mo-bisPGD in vivo and has submicromolar affinity for GDP-used as a surrogate of the molybdenum cofactor's nucleotide moieties. The crystal structure of EcFdhD in complex with GDP shows two symmetrical binding sites located on the same face of the dimer. These binding sites are connected via a tunnel-like cavity to the opposite face of the dimer where two dynamic loops, each harbouring two functionally important cysteine residues, are present. On the basis of structure-guided mutagenesis, we propose a model for the sulphuration mechanism of Mo-bisPGD where the sulphur atom shuttles across the chaperone dimer.

  4. Direct 99m Tc labeling of Herceptin (trastuzumab) by 99m Tc(I) tricarbonyl ion.

    PubMed

    Chen, Wan-Jou; Yen, Chao-Liang; Lo, Su-Tang; Chen, Kuo-Ting; Lo, Jem-Mau

    2008-03-01

    By simply incubating Herceptin (trastuzumab) with [99m Tc(CO)3(OH2)3]+ ion in saline, a significant yield of 99m Tc-labeled trastuzumab was found to be achievable. The effective labeling may be based on that trastuzumab is inherent with endogenous histidine group to which 99m Tc(I) tricarbonyl ion can be strongly bound. For practical 99m Tc labeling processing, trastuzumab was purified beforehand from the commercial product, Herceptin (Genentech) via size exclusion chromatography to remove the excipient, alpha-histidine and a high-labeled yield could be obtained by incubating the purified trastuzumab with [99m Tc(CO)3(OH2)3]+. Retention of bioactivity of the 99m Tc(I)-labeled trastuzumab was validated using a cell binding test.

  5. Hydroxyapatite Based 99Mo - 99Tc and 188W - 188Re Generator Systems

    SciTech Connect

    Knapp Jr, Russ F; Monroy-Guzman, F.; Badillo, V. E.; Cosgrove, John M; De La Torre, J.A. Flores

    2006-01-01

    This paper describes studies evaluating the use of hydroxyapatite as the adsorbent material for both {sup 99}Mo-{sup 99m}Tc and {sup 188}W-{sup 188}Re generator systems. Hydroxyapatite is an insoluble solid with anion exchange properties. A study of the sorption behaviour of {sup 99}Mo, {sup 99m}Tc, {sup 188}W and {sup 188}Re on hydroxyapatite in NaCl medium was evaluated by batch experiments. The results demonstrated that while {sup 99}Mo, {sup 99m}Tc and {sup 188}Re are not adsorbed by the hydroxyapatite in NaCl solutions (Kd <5), {sup 188}W is strongly adsorbed (Kd >500). On the basis of these measurements, hydroxyapatite {sup 188}W-{sup 188}Re generator systems were then constructed and eluted in NaCl solutions. The hydroxyapatite based {sup 188}W-{sup 188}Re generator performances are presented.

  6. Assessment of Using 99Mo and 99mTc Isotopes in Kuwait Medical Sector.

    PubMed

    Ali, Naser

    2016-04-01

    The Ministry of Health (MOH) in the state of Kuwait currently depends on importing the radioisotope molybdenum (Mo) in its isotopic form (Mo) to fulfill its demands. The present study was conducted on all nuclear medicine departments in the state of Kuwait. Daily, weekly, and monthly data were analyzed to statistically determine the current and future demands for the isotope Tc. This analysis was performed by collecting and analyzing data on MOH consumption of Tc for different diagnostic applications. The overall results indicate a partial decrease of 1.012% in the overall total demand for Tc up to the year 2018 for the state of Kuwait.

  7. Impact of molybdenum nanoparticles on survival, activity of enzymes, and chemical elements in Eisenia fetida using test on artificial substrata.

    PubMed

    Lebedev, Sviatoslav; Yausheva, Elena; Galaktionova, Lyudmila; Sizova, Elena

    2016-09-01

    The influence of molybdenum oxide nanoparticles (MoO3) on the growth and survival of Eisenia fetida was established. The activity of antioxidant enzymes and changes in concentration of molybdenum in the body of E. fetida were determined. The degree of bacterial bioluminescence inhibition in extracts of substrates and worm was studied using luminescent strain Escherichia coli K12 TG1. The enzymatic activity of substrates before and after exposure with nanoparticles and worms was assessed. Nanoparticles have concentrations of 10, 40, and 500 mg/kg of dry matter, and substrata are made of artificial soil (substrate A) and microcrystalline cellulose (substrate B). Spherical nanoparticles MoO3, yellow in color, with size 92 ± 0.3 nm, Z-potential 42 ± 0.52 mV, molybdenum content 99.8 mass/%, and specific area 12 m(2)/g were used in the study. A significant decrease by 23.3 % in weight was registered (for MoO3 NPs at 500 mg/kg) on substrate A (p ≤ 0.05). On substrate B, the maximum decrease in weight by 20.5, 33.3, and 16.9 % (p ≤ 0.05) was registered at a dose of 10, 40, and 500 mg/kg, respectively; mortality was from 6.6 to 73 %. After the assessment of bacterial bioluminescence inhibition in substrates A and B (extracts) and before worms were put, the toxicity of substrates was established at doses of 40 and 500 mg/kg, expressed in inhibitory concentration (IC) 30 and IC 50 values. Comparatively, on days 7 and 14, after exposure in the presence of E. fetida, no inhibition of bioluminescence was registered in extracts of substrates A and B, indicating the reduction in toxicity of substrates. The initial content of molybdenum in E. fetida was 0.9 ± 0.018 mg/kg of dry matter. The degree of molybdenum accumulation in worm tissue was dependent on the dose and substrate quality. In particular, 2-7 mg/kg of molybdenum accumulated from substrate A, while up to 15 kg/kg of molybdenum accumulated from substrate B (day 7). Molybdenum

  8. Potential Ways to Address Shortage Situations of (99)Mo/(99m)Tc.

    PubMed

    Filzen, Leah M; Ellingson, Lacey R; Paulsen, Andrew M; Hung, Joseph C

    2017-03-01

    (99m)Tc, the most common radioisotope used in nuclear medicine, is produced in a nuclear reactor from the decay of (99)Mo. There are only a few aging nuclear reactors around the world that produce (99)Mo, and one of the major contributors, the National Research Universal (Canada), ceased production on October 31, 2016. The National Research Universal produced approximately 40% of the world's (99)Mo supply, so with its shut down, shortages of (99)Mo/(99m)Tc are expected. Methods: Nuclear pharmacies and nuclear medicine departments throughout the United States were contacted and asked to provide their strategies for coping with a shortage of (99)Mo/(99m)Tc. Each of these strategies was evaluated on the basis of its effectiveness for conserving (99m)Tc while still meeting the needs of the patients. Results: From the responses, the following 6 categories of strategies, in order of importance, were compiled: contractual agreements with commercial nuclear pharmacies, alternative imaging protocols, changes in imaging schedules, software use, generator management, and reduction of ordered doses or elimination of backup doses. Conclusion: The supply chain of (99)Mo/(99m)Tc is quite fragile; therefore, being aware of the most appropriate coping strategies is crucial. It is essential to build a strong collaboration between the nuclear pharmacy and nuclear medicine department during a shortage situation. With both nuclear medicine departments and nuclear pharmacies implementing viable strategies, such as the ones proposed, the amount of (99m)Tc available during a shortage situation can be maximized.

  9. Selective Autooxidation of Ethanol over Titania-Supported Molybdenum Oxide Catalysts: Structure and Reactivity

    PubMed Central

    Caro, Carlos; Thirunavukkarasu, K; Anilkumar, M; Shiju, N R; Rothenberg, Gadi

    2012-01-01

    We study the selective catalytic oxidation of ethanol with air as a sustainable alternative route to acetaldehyde. The reaction is catalysed by molybdenum oxide supported on titania, in a flow reactor under ambient pressure. High selectivity to acetaldehyde (70%–89%, depending on the Mo loading) is obtained at 150 °C. Subsequently, we investigate the structure/performance relationship for various molybdenum oxide species using a combination of techniques including diffuse reflectance UV-visible, infrared, X-ray photoelectron spectroscopies, X-ray diffraction and temperature programmed reduction. As their surface density increases, the monomeric molybdenum oxide species undergo two-dimensional and three-dimensional oligomerisation. This results in polymolybdates and molybdenum oxide crystallites. Importantly, the ethanol oxidation rate depends not only on the overall molybdenum loading and dispersion, but also on the type of molybdenum oxide species prevalent at each surface density and on the domain size. As the molybdenum oxide oligomerisation increases, electron delocalisation becomes easier. This lowers the absorption edge energy and increases the reaction rate. PMID:23396482

  10. Environmental Benign Process for Production of Molybdenum Metal from Sulphide Based Minerals

    NASA Astrophysics Data System (ADS)

    Rajput, Priyanka; Janakiram, Vangada; Jayasankar, Kalidoss; Angadi, Shivakumar; Bhoi, Bhagyadhar; Mukherjee, Partha Sarathi

    2017-02-01

    Molybdenum is a strategic and high temperature refractory metal which is not found in nature in free state, it is predominantly found in earth's crust in the form of MoO3/MoS2. The main disadvantage of the industrial treatment of Mo concentrate is that the process contains many stages and requires very high temperature. Almost in every step many gaseous, liquid, solid chemical substances are formed which require further treatment. To overcome the above drawback, a new alternative one step novel process is developed for the treatment of sulphide and trioxide molybdenum concentrates. This paper presents the results of the investigations on molybdenite dissociation (MoS2) using microwave assisted plasma unit as well as transferred arc thermal plasma torch. It is a single step process for the preparation of pure molybdenum metal from MoS2 by hydrogen reduction in thermal plasma. Process variable such as H2 gas, Ar gas, input current, voltage and time have been examined to prepare molybdenum metal. Molybdenum recovery of the order of 95% was achieved. The XRD results confirm the phases of molybdenum metal and the chemical analysis of the end product indicate the formation of metallic molybdenum (Mo 98%).

  11. Pulsating White Dwarf Star GD99

    NASA Astrophysics Data System (ADS)

    Chynoweth, K. M.; Thompson, S.; Mullally, F.; Yeates, C.

    2004-12-01

    We present 15 hours of time-series photometry of the variable white dwarf star GD99. These data were obtained at the McDonald Observatory 2.1m Otto Struve Telescope in January 2003, using the Argos CCD photometer. We achieved a noise level as low as 0.07 %, as measured from the power spectrum of our first night. Our observations confirm that GD99 is a unique pulsating white dwarf whose modes show characteristics of both the hot and cold type of DA variable stars. Additionally, GD99 has a large number of modes, making it a good candidate for asteroseismological study. Our preliminary results indicate that this star merits further study to decipher its abundant set of unusual modes. With such a rich period structure, longer continuous data sets will be required to fully resolve the pulsation spectrum.

  12. Characterization of chlD gene required for molybdenum utilization in Escherichia coli

    SciTech Connect

    Scott, D.J.; Amy, N.K.

    1986-05-01

    ChlD mutants in E. coli have altered biochemical utilization of molybdenum from wild type cells. These mutants have reduced nitrate reductase and molybdenum cofactor activities when grown in low concentrations of molybdenum. When molybdenum is supplemented to 100..mu..M the mutants have wild type levels of both activities. In this study they have isolated a single copy episome containing the chlD gene using interrupted mating techniques as well as a multiple copy plasmid pBR322 with an insert containing the chlD gene using cloning techniques. The introduction of these additional chlD genes into a chlD mutant healed the phenotype when grown in low molybdenum concentrations. This indicates the chlD locus encodes for a transacting gene product. The restoration of phenotype was identical for both the single copy as well as multiple copy merodiploids. The pBR322 with the insert containing the chlD gene is currently being further characterized by restriction mapping. Previous studies have shown that the expression of the chlD gene as measured by ..beta..-galactosidase activity in chlD lac operon fusion mutants was high in cells grown in low molybdenum concentrations and low in cells grown in high molybdenum concentrations. This expression was unaltered when the episome containing the chlD gene was introduced into the chlD lac operon fusion mutant. This indicates that the product of the chlD gene is not required for regulation by molybdenum. The effect of multiple copies of the chlD gene on the expression of the chlD lac operon fusion is presently being studied. The eventual goal of these studies is to determine the function of the chlD gene in the activation of molybdenum.

  13. Porphyry molybdenum deposits in the Tianshan-Xingmeng orogenic belt, northern China

    NASA Astrophysics Data System (ADS)

    Zeng, Qingdong; Qin, Kezhang; Liu, Jianming; Li, Guangming; Zhai, Mingguo; Chu, Shaoxiong; Guo, Yunpeng

    2015-06-01

    Molybdenum (Mo) exploration activity in China has increased tremendously over the past decade, and China is now known to have the largest Mo reserves in the world. The Tianshan-Xingmeng orogenic belt, the second largest Mo metallogenic belt, possesses over 8.2 Mt of Mo reserves. Porphyry Mo deposits contain 99 % of the Mo reserves in the Tianshan-Xingmeng orogenic belt; other Mo deposits contain 1 % of the Mo reserves. Five subtypes of the porphyry Mo deposits can be distinguished by deposit associations, such as Mo, Mo-Cu, Mo-W, Mo-Pb-Zn-Ag, and Cu-Mo deposits. These porphyry Mo deposits are formed at different stages: during the Ordovician, Devonian, Carboniferous, Late Permian, Triassic, Jurassic, and Cretaceous Periods. The polystage porphyry Mo mineralizations indicate that polystage tectonic-magmatic activity occurred in the orogenic belt. The Ordovician-Carboniferous porphyry Cu-Mo deposits are formed in an island-arc setting; the Late Permian porphyry Mo deposits are formed in a syn-collisional tectonic setting; and the Triassic porphyry Mo deposits are formed in a syn-collisional to post-collisional tectonic setting. The Ordovician-Triassic porphyry deposits are related to the Paleo-Asian Ocean tectonic system. The Jurassic porphyry Mo deposits are formed at the eastern margin of the Asian continent and are associated with a Paleo-Pacific plate-subduction tectonic setting. Cretaceous porphyry Mo deposits are formed in a lithospheric thinning setting and are related to the rollback of the Paleo-Pacific subduction plate.

  14. STS-99 Countdown Status Press Conference

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Live footage shows the participants in the Press Conference disclosing the status of the STS-99 flight. The panelists consists of NASA's test Director Jeff Spaulding, the STS-99 Payload Manager Scott Higginbotham, and the Shuttle Weather Officer Ed Priselac. Bruce Buckingham NASA's Public Affairs introduces each panelist as they discuss the servicing of fuel tanks, checkout, closeouts, payload status, and favorable weather conditions. The panelists also answer questions from the audience. Also shown are various shots of the Shuttle on the launch pad.

  15. Compressibility of tungsten and molybdenum bars during rotary swaging and rolling

    NASA Astrophysics Data System (ADS)

    Barkov, L. A.; Mymrin, S. A.; Samodurova, M. N.; Dzhigun, N. S.; Latfulina, Yu. S.

    2015-05-01

    The compressibility of bars and hydraulically forged workpieces made of tungsten and molybdenum is studied during rotary swaging and rolling in mills with two-, three-, and four-roll passes. The compressibility of molybdenum MCh bars and hydraulically forged molybdenum M-MP workpieces is investigated during rotary swaging and rolling in three- and four-roll passes. The compressibility of tungsten VA and VL bars and hydraulically forged tungsten V-MP workpieces is investigated during rotary swaging and rolling in three- and four-roll passes. The compressibility of the hydraulically forged tungsten V-MP workpieces is analyzed under two- and four-roll pass rolling conditions.

  16. Role of electron concentration in softening and hardening of ternary molybdenum alloys

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Witzke, W. R.

    1975-01-01

    Effects of various combinations of hafnium, tantalum, rhenium, osmium, iridium, and platinum in ternary molybdenum alloys on alloy softening and hardening were determined. Hardness tests were conducted at four test temperatures over the temperature range 77 to 411 K. Results showed that hardness data for ternary molybdenum alloys could be correlated with anticipated results from binary data based upon expressions involving the number of s and d electrons contributed by the solute elements. The correlation indicated that electron concentration plays a dominant role in controlling the hardness of ternary molybdenum alloys.

  17. Differential pulse polarographic determination of molybdenum after separation by 8-hydroxyquinoline extraction into dichloromethane.

    PubMed

    Nagaosa, Y; Kobayashi, K

    1984-08-01

    A polarographic investigation of several metal 8-hydroxyquinolinates in dichloromethane medium following solvent extraction has been made. From the data obtained, a selective, specific and sensitive method for the determination of molybdenum at ng ml levels has been developed involving direct differential pulse polarographic measurement on the dichloromethane extract. In this work, EDTA is used as an effective masking agent to separate molybdenum from other metals. The proposed method has been applied to the determination of molybdenum in a variety of steels and NBS-SRM 1577 bovine liver with good accuracy and precision.

  18. Comparison of effects on crustaceans: carbon nanoparticles and molybdenum compounds nanowires

    NASA Astrophysics Data System (ADS)

    Baumerte, A.; Sakale, G.; Zavickis, J.; Putna, I.; Balode, M.; Mrzel, A.; Knite, M.

    2013-04-01

    Carbon nanomaterials (CNM) and molybdenum compound nanostructures are materials with various applications yet little is known regarding the toxicity of these nanoparticles in pristine form in aquatic environment. Daphnia magna standard acute toxicity test (EN ISO 6341:1996; freshwater) and Artemia salina standard acute toxicity test (ArtoxKit standard method; 15 ppt saltwater) were applied to assess the toxicity of non-modified CNM and molybdenum compound nanowires in water. It has been observed that CNM are more toxic in freshwater suspensions and somewhat more toxic than the tested molybdenum compound nanowires.

  19. Special features in the electroreduction of oxidic molybdenum(VI) forms in tungstate melt

    SciTech Connect

    Shapoval, V.I.; Baraboshkin, A.N.; Kushkhov, K.B.; Malyshev, V.V.

    1988-01-01

    The electrochemical behavior of oxidic molybdenum in tungstate melt was studied under equilibrium and nonequilibrium conditions. Chronovoltammetry and transient polarization was used. The current-voltage curves were recorded with a pulse potentiostat and the experiments were performed in a quartz reactor with platinum and molybdenum electrodes and a platinum crucible served as the melt container and anode. The end product of the oxidic molybdenum forms were shown to depend on the acid-base properties of the melt which allows for choosing the properties and controlling the electrode process.

  20. Reduced ternary molybdenum and tungsten sulfides and hydroprocessing catalysis therewith

    DOEpatents

    Hilsenbeck, S.J.; McCarley, R.E.; Schrader, G.L.; Xie, X.B.

    1999-02-16

    New amorphous molybdenum/tungsten sulfides with the general formula M{sup n+}{sub 2x/n}(L{sub 6}S{sub 8})S{sub x}, where L is molybdenum or tungsten and M is a ternary metal, has been developed. Characterization of these amorphous materials by chemical and spectroscopic methods (IR, Raman, PES) shows that the (M{sub 6}S{sub 8}){sup 0} cluster units are present. Vacuum thermolysis of the amorphous Na{sub 2x}(Mo{sub 6}S{sub 8})S{sub x}{hor_ellipsis}yMeOH first produces poorly crystalline NaMo{sub 6}S{sub 8} by disproportionation at 800 C and well-crystallized NaMo{sub 6}S{sub 8} at {>=} 900 C. Ion-exchange of the sodium material in methanol with soluble M{sup 2+} and M{sup 3+} salts (M=Sn, Co, Ni, Pb, La, Ho) produces the M{sup n+}{sub 2x/n}(Mo{sub 6}S{sub 8})S{sub x}{hor_ellipsis}yMeOH compounds. Additionally, the new reduced ternary molybdenum sulfides with the general formula M{sup n+}{sub 2x/n}Mo{sub 6}S{sub 8+x}(MeOH){sub y}[MMOS] (M=Sn, Co, Ni) is an effective hydrodesulfurization (HDS) catalyst both as-prepared and after a variety of pretreatment conditions. Under specified pretreatment conditions with flowing hydrogen gas, the SnMoS type catalyst can be stabilized, and while still amorphous, can be considered as ``Chevrel phase-like`` in that both contain Mo{sub 6}S{sub 8} cluster units. Furthermore, the small cation NiMoS and CoMoS type pretreated catalyst is shown to be very active HDS catalysts with rates that exceeded the model unpromoted and cobalt-promoted MoS{sub 2} catalysts. 9 figs.

  1. Reduced ternary molybdenum and tungsten sulfides and hydroprocessing catalysis therewith

    DOEpatents

    Hilsenbeck, Shane J.; McCarley, Robert E.; Schrader, Glenn L.; Xie, Xiaobing

    1999-02-16

    New amorphous molybdenum/tungsten sulfides with the general formula M.sup.n+.sub.2x/n (L.sub.6 S.sub.8)S.sub.x, where L is molybdenum or tungsten and M is a ternary metal, has been developed. Characterization of these amorphous materials by chemical and spectroscopic methods (IR, Raman, PES) shows that the (M.sub.6 S.sub.8).sup.0 cluster units are present. Vacuum thermolysis of the amorphous Na.sub.2x (Mo.sub.6 S.sub.8)S.sub.x .multidot.yMeOH first produces poorly crystalline NaMo.sub.6 S.sub.8 by disproportionation at 800.degree. C. and well-crystallized NaMo.sub.6 S.sub.8 at .gtoreq. 900.degree. C. Ion-exchange of the sodium material in methanol with soluble M.sup.2+ and M.sup.3+ salts (M=Sn, Co, Ni, Pb, La, Ho) produces the M.sup.n+.sub.2x/n (Mo.sub.6 S.sub.8)S.sub.x .multidot.yMeOH compounds. Additionally, the new reduced ternary molybdenum sulfides with the general formula M.sup.n+.sub.2x/n Mo.sub.6 S.sub.8+x (MeOH).sub.y ›MMOS! (M=Sn, Co, Ni) is an effective hydrodesulfurization (HDS) catalyst both as-prepared and after a variety of pretreatment conditions. Under specified pretreatment conditions with flowing hydrogen gas, the SnMoS type catalyst can be stabilized, and while still amorphous, can be considered as "Chevrel phase-like" in that both contain Mo.sub.6 S.sub.8 cluster units. Furthermore, the small cation NiMoS and CoMoS type pretreated catalyst showed to be very active HDS catalysts with rates that exceeded the model unpromoted and cobalt-promoted MoS.sub.2 catalysts.

  2. Molybdenum Disilicide Oxidation Kinetics in High Temperature Steam

    SciTech Connect

    Wood, Elizabeth Sooby; Parker, Stephen Scott; Nelson, Andrew Thomas

    2016-09-07

    The Fuel Cycle Research and Development program’s Advanced Fuels Campaign is currently supporting a range of experimental efforts aimed at the development and qualification of ‘accident tolerant’ nuclear fuel forms. One route to enhance the accident tolerance of nuclear fuel is to replace the zirconium alloy cladding, which is prone to rapid oxidation in steam at elevated temperatures, with a more oxidation-resistant cladding. Several cladding replacement solutions have been envisaged. The cladding can be completely replaced with a more oxidation resistant alloy, a layered approach can be used to optimize the strength, creep resistance, and oxidation tolerance of various materials, or the existing zirconium alloy cladding can be coated with a more oxidation-resistant material. Molybdenum is one candidate cladding material favored due to its high temperature creep resistance. However, it performs poorly under autoclave testing and suffers degradation under high temperature steam oxidation exposure. Development of composite cladding architectures consisting of a molybdenum core shielded by a molybdenum disilicide (MoSi2) coating is hypothesized to improve the performance of a Mo-based cladding system. MoSi2 was identified based on its high temperature oxidation resistance in O2 atmospheres (e.g. air and “wet air”). However, its behavior in H2O is less known. This report presents thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and x-ray diffraction (XRD) results for MoSi2 exposed to 670-1498 K water vapor. Synthetic air (80-20%, Ar-O2) exposures were also performed, and those results are presented here for a comparative analysis. It was determined that MoSi2 displays drastically different oxidation behavior in water vapor than in dry air. In the 670-1498 K temperature range, four distinct behaviors are observed. Parabolic oxidation is exhibited in only 670

  3. Feasibility study on the medical isotopes production with solution target using OSTR: (99)Mo and related isotopes

    NASA Astrophysics Data System (ADS)

    Baik, Seung-Hyuk

    1999-11-01

    Molybdenum-99 (99Mo) is the parent nuclide of Technetium-99m (99mTc), a radioisotope which is widely used in nuclear medicine. 99Mo is produced from the fission of 235U or the irradiation of 98Mo. This study shows the feasibility of the using an 'aqueous homogeneous uranium solution target' for the production of a medical isotope, 99Mo. Some of the advantages that the solution target has over a solid target include the inherent reactor safety features offered by large negative temperature and power reactivity coefficients, the fabrication convenience, the straightforward extraction process, and a low volume of waste generated. To evaluate the core configuration and the production rate of 99Mo, a three-dimensional model of the Oregon State University TRIGA Reactor (OSTR) core was developed for use with the Monte Carlo N-Particle Transport Code (MCNP) and then verified by comparing with the measured values. Two values are in good agreement within one percent in the keffective values calculated. Two types of solution targets are analyzed for the OSTR. The first one has the same outer-dimensions as an OSTR fuel element but is filled with a uranium solution. The other is the continuous flow target system (CFTS) like solution fuel reactors. Uranyl nitrate and uranyl sulfate solutions enriched to 20% or 93% are investigated as a target material without raising any safety concern to the OSTR operation. A seven-day irradiation of ten tube-type-93% enriched uranyl nitrate solution targets would produce 43% of the 99Mo required in the US for one week. The CFTS would generate 31% of the required 99Mo in a 7-day cycle. The conceptual chemical extraction processes for irradiated solution targets are developed. This work also includes an analysis of nuclear safety issues such as the radiolytic gas, thermal hydraulics, the waste, and the radiological impacts of an accident. The production of 99Mo in the OSTR with the uranium solution is technically feasible as demonstrated in this

  4. An examination of the association of selected toxic metals with total and central obesity indices: NHANES 99-02.

    PubMed

    Padilla, Miguel A; Elobeid, Mai; Ruden, Douglas M; Allison, David B

    2010-09-01

    It is conceivable that toxic metals contribute to obesity by influencing various aspects of metabolism, such as by substituting for essential micronutrients and vital metals, or by inducing oxidative stress. Deficiency of the essential metal zinc decreases adiposity in humans and rodent models, whereas deficiencies of chromium, copper, iron, and magnesium increases adiposity. This study utilized the NHANES 99-02 data to explore the association between waist circumference and body mass index with the body burdens of selected toxic metals (barium, cadmium, cobalt, cesium, molybdenum, lead, antimony, thallium, and tungsten). Some of the associations were significant direct relationships (barium and thallium), and some of the associations were significant inverse relationships (cadmium, cobalt, cesium, and lead). Molybdenum, antimony, and tungsten had mostly insignificant associations with waist circumference and body mass index. This is novel result for most of the toxic metals studied, and a surprising result for lead because high stored lead levels have been shown to correlate with higher rates of diabetes, and obesity may be a key risk factor for developing diabetes. These associations suggest the possibility that environmental exposure to metals may contribute to variations in human weight gain/loss. Future research, such as prospective studies rather than the cross-sectional studies presented here, is warranted to confirm these findings.

  5. An Examination of the Association of Selected Toxic Metals with Total and Central Obesity Indices: NHANES 99-02

    PubMed Central

    Padilla, Miguel A.; Elobeid, Mai; Ruden, Douglas M.; Allison, David B.

    2010-01-01

    It is conceivable that toxic metals contribute to obesity by influencing various aspects of metabolism, such as by substituting for essential micronutrients and vital metals, or by inducing oxidative stress. Deficiency of the essential metal zinc decreases adiposity in humans and rodent models, whereas deficiencies of chromium, copper, iron, and magnesium increases adiposity. This study utilized the NHANES 99-02 data to explore the association between waist circumference and body mass index with the body burdens of selected toxic metals (barium, cadmium, cobalt, cesium, molybdenum, lead, antimony, thallium, and tungsten). Some of the associations were significant direct relationships (barium and thallium), and some of the associations were significant inverse relationships (cadmium, cobalt, cesium, and lead). Molybdenum, antimony, and tungsten had mostly insignificant associations with waist circumference and body mass index. This is novel result for most of the toxic metals studied, and a surprising result for lead because high stored lead levels have been shown to correlate with higher rates of diabetes, and obesity may be a key risk factor for developing diabetes. These associations suggest the possibility that environmental exposure to metals may contribute to variations in human weight gain/loss. Future research, such as prospective studies rather than the cross-sectional studies presented here, is warranted to confirm these findings. PMID:20948927

  6. Utility of the Static-99 and Static-99R With Latino Sex Offenders.

    PubMed

    Leguízamo, Alejandro; Lee, Seung C; Jeglic, Elizabeth L; Calkins, Cynthia

    2015-12-16

    The predictive validity of the Static-99 measures with ethnic minorities in the United States has only recently been assessed with mixed results. We assessed the predictive validity of the Static-99 and Static-99R with a sample of Latino sex offenders (N = 483) as well as with two subsamples (U.S.-born, including Puerto Rico, and non-U.S.-born). The overall sexual recidivism rate was very low (1.9%). Both the Static-99 measures were able to predict sexual recidivism for offenders born in the United States and Puerto Rico, but neither was effective in doing so for other Latino immigrants. Calibration analyses (N = 303) of the Static-99R were consistent with the literature and provided support for the potential use of the measure with Latinos born in the United States and Puerto Rico. These findings and their implications are discussed as they pertain to the assessment of Latino sex offenders.

  7. Spreading of Viscous Liquids at High Temperature: Silicate Glasseson Molybdenum

    SciTech Connect

    Lopez-Esteban, Sonia; Saiz, Eduardo; Moya, Jose S.; Tomsia,Antoni P.

    2004-12-15

    The spreading of Si-Ca-Al-Ti-O glasses on molybdenum has been investigated. By controlling the oxygen activity in the furnace, spreading can take place under reactive or non-reactive conditions. As the nucleation of the reaction product under reactive conditions is slow in comparison to the spreading kinetics, in both cases the glass front moves on the metal surface with similar spreading velocities. Spreading can be described using a molecular dynamics model where the main contribution to the wetting activation energy comes from the viscous interactions in the liquid. Enhanced interfacial diffusions in low-oxygen activities (reactive cases) form triple-line ridges that can pin the wetting front and cause a stick-slip motion.

  8. Ethanol Reduced Molybdenum Trioxide for Li-ion Capacitors

    DOE PAGES

    Li, Tianqi; Beidaghi, Majid; Xiao, Xu; ...

    2016-05-06

    Orthorhombic molybdenum trioxide (α-MoO3) is a layered oxide with promising performance as electrode material for Li-ion capacitors. In this study, we show that expansion of the interlayer spacing (by ~0.32 Å) of the structure along the b-axis, introduced by partial reduction of α-MoO3 and formation of MoO3-x (x=0.06–0.43), results in enhanced diffusion of Li ions. Binder-free hybrid electrodes made of MoO3-x nanobelts and carbon nanotubes show excellent electrical conductivity. The combination of increased interlayer spacing and enhanced electron transport leads to high gravimetric and volumetric capacitances of about 420 F/g or F/cm3 and excellent cycle life of binder-free MoO3-x electrodes.

  9. Temperature-dependent morphology of chemical vapor grown molybdenum disulfide

    NASA Astrophysics Data System (ADS)

    Yang, Xiaoyin; Wang, Yantao; Zhou, Jiadong; Liu, Zheng

    2017-04-01

    Monolayered molybdenum disulfide (MoS2) is a 2D direct band gap semiconductor with promising potential applications. In this work, we observed the temperature dependency of the morphologies of MoS2 monolayers from chemical vapor deposition. At a low growing temperature below 850 °C, MoS2 flakes tend to be trianglular in shape. At 850–950 °C, hexagonal MoS2 flakes can be observed. While at a temperature over 950 °C, MoS2 flakes can form rectangular shapes. Complementary characterizations have been made to these samples. We also proposed a mechanism for such temperature-dependent shape evolution based on thermodynamic simulation.

  10. The history of development of molybdenum alloys for structural applications

    SciTech Connect

    Wadsworth, J.; Wittenauer, J.P.

    1993-02-01

    Molybdenum was first isolated as an element in 1893 and found initial commercial application as a filament support for incandescent lamps in 1910. The advent of arc melting practice in the 1940s led to an increase in availability of Mo sheet, bar, and plate products. Alloy development programs were heavily supported starting in the 1950s and several key alloys emerged over the next twenty years that remain in use to the present time such as Mo-TZM, unalloyed Mo, and Mo-Re. In recent years, improved understanding of the role of oxygen and carbide distributions at grain boundaries have led to increased reliability and use of Mo in aerospace products. Current developmental programs in areas of propulsion and energy conversion will ensure the prominent position of Mo as a high-temperature structural material. This paper highlights some of these key developments in the evolution of Mo alloys.

  11. Evaluation of Oxide Dispersion Strengthened (ODS) molybdenum alloys

    SciTech Connect

    Bianco, R.; Buckman, R.W. Jr.

    1995-12-31

    A series of fourteen (14) novel high-strength molybdenum alloy compositions containing a dispersion of very fine (< 1 {mu}m diameter) oxide particles were consolidated using two proprietary powder metallurgy techniques. The developmental compositions were evaluated to determine the microstructural stability and mechanical properties from cryogenic (-148{degrees}F) to elevated temperatures (4000{degrees}F) for material in the as-swaged (>98% cold work) condition and for as-swaged material in the heat treated condition. Extremely fine oxide particle sizes (<1000 {Angstrom}) were observed by Transmission Electron Microscopy (TEM) for a number of the experimental compositions in the as-swaged condition. A one hour recrystallization temperature as high as 3990{degrees}F was measured and a ductile-to-brittle transition temperature as low as {approximately}58{degrees}F for material in the recrystallized condition was determined. The preliminary results support the alloy design concept feasibility.

  12. Magnetic properties of sputtered Permalloy/molybdenum multilayers

    SciTech Connect

    Romera, M.; Ciudad, D.; Maicas, M.; Aroca, C.

    2011-10-15

    In this work, we report the magnetic properties of sputtered Permalloy (Py: Ni{sub 80}Fe{sub 20})/molybdenum (Mo) multilayer thin films. We show that it is possible to maintain a low coercivity and a high permeability in thick sputtered Py films when reducing the out-of-plane component of the anisotropy by inserting thin film spacers of a non-magnetic material like Mo. For these kind of multilayers, we have found coercivities which are close to those for single layer films with no out-of-plane anisotropy. The coercivity is also dependent on the number of layers exhibiting a minimum value when each single Py layer has a thickness close to the transition thickness between Neel and Bloch domain walls.

  13. Tuning thermal conductivity in molybdenum disulfide by electrochemical intercalation

    PubMed Central

    Zhu, Gaohua; Liu, Jun; Zheng, Qiye; Zhang, Ruigang; Li, Dongyao; Banerjee, Debasish; Cahill, David G.

    2016-01-01

    Thermal conductivity of two-dimensional (2D) materials is of interest for energy storage, nanoelectronics and optoelectronics. Here, we report that the thermal conductivity of molybdenum disulfide can be modified by electrochemical intercalation. We observe distinct behaviour for thin films with vertically aligned basal planes and natural bulk crystals with basal planes aligned parallel to the surface. The thermal conductivity is measured as a function of the degree of lithiation, using time-domain thermoreflectance. The change of thermal conductivity correlates with the lithiation-induced structural and compositional disorder. We further show that the ratio of the in-plane to through-plane thermal conductivity of bulk crystal is enhanced by the disorder. These results suggest that stacking disorder and mixture of phases is an effective mechanism to modify the anisotropic thermal conductivity of 2D materials. PMID:27767030

  14. Superconductivity in the alkali metal intercalates of molybdenum disulphide

    NASA Technical Reports Server (NTRS)

    Somoano, R. B.; Hadek, V.; Rembaum, A.

    1972-01-01

    The complete series of alkali metals, lithium through cesium, have been intercalated into molybdenum disulphide, using both the liquid ammonia and vapor techniques. All the intercalates with the exception of lithium yielded full superconducting transitions with onset temperatures of 6 K for AxMoS2(Ax=K,Rb,Cs) and 4 K for BxMoS2(Bx=Li,Na). The superconducting transition for lithium was incomplete down to 1.5 K. Stoichiometries and unit cell parameters have been determined for the intercalation compounds. Both rhombohedral and hexagonal polymorphs of MoS2 have been intercalated and found to exhibit the same superconductivity behavior. The nature of the extraneous superconducting transition of some intercalated samples on exposure to air was elucidated.

  15. Antifriction and antiwear characteristics of molybdenum dithiophosphate in engine oils

    SciTech Connect

    Yichao Lin

    1995-10-01

    Antifriction and antiwear studies of lubricating oil compounded with engine oil additives such as petroleum calcium sulfonate (PCS) metal detergents, polyisobutylene succinimide (PSI) ashless dispersant, zinc dithiophosphate (ZnDTP) antioxidant and molybdenum dithiophosphate (MoDTP) using the four-ball machine (FBM) are reported. The results show that binary or ternary mixtures of MoDTP with ZnDTP, or ZnDTP and dipolyisobutylene succinimide (DPSI) obviously have beneficial effects on the antifriction and antiwear properties of MoDTP. However, binary or ternary mixtures of MoDTP with PCS, multipolyisobutylene succinimide (MPSI), or PCS and ZnDTP show different responses to the MoDTP antifriction and antiwear properties which depend upon different compositions. The molecular structures of the components of the MoDTP additive are analyzed by {sup 31}P-NMR spectroscopy. 18 refs., 11 figs., 4 tabs.

  16. Immobilization and fixation of molybdenum (6) by Portland cement

    SciTech Connect

    Kindness, A.; Lachowski, E.E.; Minocha, A.K.; Glasser, F.P. . Dept. of Chemistry)

    1994-01-01

    The immobilization of molybdenum (6) in Portland cement has been studied. Analytical methods are reviewed. As a precursor to studies using commercial cements, the cement constituent phases Ca[sub 3]Al[sub 2]O[sub 6] and Ca[sub 3]SiO[sub 5] and mixtures of Ca[sub 3]Al[sub 2]O[sub 6] and gypsum (CaSO[sub 4][center dot]2H[sub 2]O) have been synthesized and subsequently hydrated with an aqueous solution containing initially 2,000 ppm Mo. The aqueous Mo contents decrease slowly over the first 12 days before attaining a steady-state concentration, ca. 40--50 ppm. Its main speciation is as molybdate, MoO[sub 4][sup 2[minus

  17. Electronic origin of solid solution softening in bcc molybdenum alloys.

    PubMed

    Medvedeva, N I; Gornostyrev, Yu N; Freeman, A J

    2005-04-08

    The intrinsic mechanism of solid solution softening in bcc molybdenum alloys due to 5d transition metal additions is investigated on the basis of ab initio electronic-structure calculations that model the effect of alloying elements on the generalized stacking fault (GSF) energies. We demonstrate that additions with an excess of electrons (Re, Os, Ir, and Pt) lead to a decrease in the GSF energy and those with a lack of electrons (Hf and Ta) to its sharp increase. Using the generalized Peierls-Nabarro model for a nonplanar core, we associate the local reduction of the GSF energy with an enhancement of double kink nucleation and an increase of the dislocation mobility, and we reveal the electronic reasons for the observed dependence of the solution softening on the atomic number of the addition.

  18. Development of Solvent Extraction Approach to Recycle Enriched Molybdenum Material

    SciTech Connect

    Tkac, Peter; Brown, M. Alex; Sen, Sujat; Bowers, Delbert L.; Wardle, Kent; Copple, Jacqueline M.; Pupek, Krzysztof Z.; Dzwiniel, Trevor L.; Pereira, Candido; Krumdick, Gregory K.; Vandegrift, George F.

    2016-06-01

    Argonne National Laboratory, in cooperation with Oak Ridge National Laboratory and NorthStar Medical Technologies, LLC, is developing a recycling process for a solution containing valuable Mo-100 or Mo-98 enriched material. Previously, Argonne had developed a recycle process using a precipitation technique. However, this process is labor intensive and can lead to production of large volumes of highly corrosive waste. This report discusses an alternative process to recover enriched Mo in the form of ammonium heptamolybdate by using solvent extraction. Small-scale experiments determined the optimal conditions for effective extraction of high Mo concentrations. Methods were developed for removal of ammonium chloride from the molybdenum product of the solvent extraction process. In large-scale experiments, very good purification from potassium and other elements was observed with very high recovery yields (~98%).

  19. High Performance Molybdenum Disulfide Amorphous Silicon Heterojunction Photodetector

    PubMed Central

    Esmaeili-Rad, Mohammad R.; Salahuddin, Sayeef

    2013-01-01

    One important use of layered semiconductors such as molybdenum disulfide (MoS2) could be in making novel heterojunction devices leading to functionalities unachievable using conventional semiconductors. Here we demonstrate a metal-semiconductor-metal heterojunction photodetector, made of MoS2 and amorphous silicon (a-Si), with rise and fall times of about 0.3 ms. The transient response does not show persistent (residual) photoconductivity, unlike conventional a-Si devices where it may last 3–5 ms, thus making this heterojunction roughly 10X faster. A photoresponsivity of 210 mA/W is measured at green light, the wavelength used in commercial imaging systems, which is 2−4X larger than that of a-Si and best reported MoS2 devices. The device could find applications in large area electronics, such as biomedical imaging, where a fast response is critical. PMID:23907598

  20. Selective and efficient electrochemical biosensing of ultrathin molybdenum disulfide sheets

    NASA Astrophysics Data System (ADS)

    Narayanan, Tharangattu N.; Vusa, Chiranjeevi S. R.; Alwarappan, Subbiah

    2014-08-01

    Atomically thin molybdenum disulfide (MoS2) sheets were synthesized and isolated via solvent-assisted chemical exfoliation. The charge-dependent electrochemical activities of these MoS2 sheets were studied using positively charged hexamine ruthenium (III) chloride and negatively charged ferricyanide/ferrocyanide redox probes. Ultrathin MoS2 sheet-based electrodes were employed for the electrochemical detection of an important neurotransmitter, namely dopamine (DA), in the presence of ascorbic acid (AA). MoS2 electrodes were identified as being capable of distinguishing the coexistence of the DA and the AA with an excellent stability. Moreover, the enzymatic detection of the glucose was studied by immobilizing glucose oxidase on the MoS2. This study opens enzymatic and non-enzymatic electrochemical biosensing applications of atomic MoS2 sheets, which will supplement their established electronic applications.

  1. Piezoelectric resonator assembly with thin molybdenum mounting clips

    DOEpatents

    Peters, R. Donald

    1981-01-01

    A resonator mounting assembly wherein the resonator blank is mounted agai an essentially planar surface presented by a plurality of peripherally disposed mounting clips and bonded to this surface to provide substantially all the mechanical support for the blank in a direction normal to the major faces of the resonator blank, while being flexible in the directions parallel to said major faces so as to minimize radial stresses on the resonator blank, particularly during thermal cycling of the resonator assembly. The clips are fabricated of a low thermal expansion material, such as molybdenum, which also has considerable yield strength after exposure to processing temperatures; the bonding of the clips to the edges of the resonator blank can be achieved by a polyimide containing electrically conductive particles.

  2. Molybdenum-tin as a solar cell metallization system

    NASA Technical Reports Server (NTRS)

    Boyd, D. W.; Radics, C.

    1981-01-01

    The operations of solar cell manufacture are briefly examined. The formation of reliable, ohmic, low-loss, and low-cost metal contacts on solar cells is a critical process step in cell manufacturing. In a commonly used process, low-cost metallization is achieved by screen printing a metal powder-glass frit ink on the surface of the Si surface and the conductive metal powder. A technique utilizing a molybdenum-tin alloy for the metal contacts appears to lower the cost of materials and to reduce process complexity. The ink used in this system is formulated from MoO3 with Sn powder and a trace amount of titanium resonate. Resistive losses of the resulting contacts are low because the ink contains no frit. The MoO3 is finally melted and reduced in forming gas (N2+H2) to Mo metal. The resulting Mo is highly reactive which facilitates the Mo-Si bonding.

  3. Wet chemical thinning of molybdenum disulfide down to its monolayer

    SciTech Connect

    Amara, Kiran Kumar; Chu, Leiqiang; Kumar, Rajeev; Toh, Minglin; Eda, Goki

    2014-09-01

    We report on the preparation of mono- and bi-layer molybdenum disulfide (MoS{sub 2}) from a bulk crystal by facile wet chemical etching. We show that concentrated nitric acid (HNO{sub 3}) effectively etches thin MoS{sub 2} crystals from their edges via formation of MoO{sub 3}. Interestingly, etching of thin crystals on a substrate leaves behind unreacted mono- and bilayer sheets. The flakes obtained by chemical etching exhibit electronic quality comparable to that of mechanically exfoliated counterparts. Our findings indicate that the self-limiting chemical etching is a promising top-down route to preparing atomically thin crystals from bulk layer compounds.

  4. Ethanol Reduced Molybdenum Trioxide for Li-ion Capacitors

    SciTech Connect

    Li, Tianqi; Beidaghi, Majid; Xiao, Xu; Huang, Liang; Hu, Zhimi; Sun, Wanmei; Chen, Xun; Gogotsi, Yury G.; Zhou, Jun

    2016-05-06

    Orthorhombic molybdenum trioxide (α-MoO3) is a layered oxide with promising performance as electrode material for Li-ion capacitors. In this study, we show that expansion of the interlayer spacing (by ~0.32 Å) of the structure along the b-axis, introduced by partial reduction of α-MoO3 and formation of MoO3-x (x=0.06–0.43), results in enhanced diffusion of Li ions. Binder-free hybrid electrodes made of MoO3-x nanobelts and carbon nanotubes show excellent electrical conductivity. The combination of increased interlayer spacing and enhanced electron transport leads to high gravimetric and volumetric capacitances of about 420 F/g or F/cm3 and excellent cycle life of binder-free MoO3-x electrodes.

  5. Extraction of Molybdenum from Molybdenite Concentrates with Hydrometallurgical Processing

    NASA Astrophysics Data System (ADS)

    Jiang, Kaixi; Wang, Yufang; Zou, Xiaoping; Zhang, Lei; Liu, Sanping

    2012-11-01

    Molybdenite concentrates are usually treated by roasting, but low-concentration SO2 pollution is an associated problem. A hydrometallurgical process with pressure oxidation leaching (POX) and solvent extraction (SX) was developed in recent years. During POX, the oxidation of molybdenum (Mo) is above 98%. More than 95% of the rhenium (Re) and 15% to 20% of the Mo are leached into solution. The sulfur in the concentrate is converted to H2SO4, which results in high acidity of the solution. SX was used to recover the Re and Mo from the solution. The extraction of Re and Mo were above 98%. The loaded organic reagent is stripped with ammonia. More than 98% of the Mo can be stripped from the organic phase. Compared with the roasting process, the total recovery of Mo increased from 93% to 97% and that of Re from 60% to 90% when POX and SX are utilized.

  6. Intercalation Pseudocapacitance of Exfoliated Molybdenum Disulfide for Ultrafast Energy Storage

    DOE PAGES

    Yoo, Hyun Deog; Li, Yifei; Liang, Yanliang; ...

    2016-05-23

    In this study, we report intercalation pseudocapacitance of 250 F g-1 for exfoliated molybdenum disulfide (MoS2) in non-aqueous electrolytes that contain lithium ions. The exfoliated MoS2 shows surface-limited reaction kinetics with high rate capability up to 3 min of charge or discharge. The intercalation pseudocapacitance originates from the extremely fast kinetics due to the enhanced ionic and electronic transport enabled by the slightly expanded layer structure as well as the metallic 1T-phase. The exfoliated MoS2 could be also used in a Li-Mg-ion hybrid capacitor, which shows full cell specific capacitance of 240 F g-1.

  7. Towards slide enhancement with the titanium-molybdenum wire?

    PubMed

    Thiry, Pol; Barthélémi, Stéphane

    2010-12-01

    This study aims to improve the tribological properties of titanium-molybdenum wire. Following an analysis of the wire/bracket/ligation friction parameters and an overview of the technological research into means of reducing such friction,we set up several types of surface treatment in the laboratory by physical deposition in the vapor phase and using cold plasma technology. The specimens obtained underwent two types of tribological tests and were then subjected to traction and bending tests in order to determine the variations in their mechanical properties induced by the different types of treatment. For purposes of comparison, all the tests were conducted on untreated wire, TMA® Low-friction® wire and stainless steel wire and with two types of elastomeric ties. We were able to demonstrate some remarkable slide performances obtained using cold plasma nitriding while preserving the mechanical properties. A significant difference was observed relative to the other surface treatments.

  8. Intercalation Pseudocapacitance of Exfoliated Molybdenum Disulfide for Ultrafast Energy Storage

    SciTech Connect

    Yoo, Hyun Deog; Li, Yifei; Liang, Yanliang; Lan, Yucheng; Wang, Feng; Yao, Yan

    2016-05-23

    In this study, we report intercalation pseudocapacitance of 250 F g-1 for exfoliated molybdenum disulfide (MoS2) in non-aqueous electrolytes that contain lithium ions. The exfoliated MoS2 shows surface-limited reaction kinetics with high rate capability up to 3 min of charge or discharge. The intercalation pseudocapacitance originates from the extremely fast kinetics due to the enhanced ionic and electronic transport enabled by the slightly expanded layer structure as well as the metallic 1T-phase. The exfoliated MoS2 could be also used in a Li-Mg-ion hybrid capacitor, which shows full cell specific capacitance of 240 F g-1.

  9. An unusual variation of stability and hardness in molybdenum borides

    NASA Astrophysics Data System (ADS)

    Liang, Yongcheng; Yuan, Xun; Fu, Zhao; Li, Yuan; Zhong, Zheng

    2012-10-01

    Molybdenum borides are currently raising great expectations for superhard materials, but their crystal structures and mechanical behaviors are still under discussion. Here, we report an unexpected reduction of stability and hardness from porous hP16-MoB3 and hR18-MoB2 to dense hP20-MoB4 and hR21-Mo2B5, respectively. Furthermore, we demonstrate that this anomalous variation has its electronic origin. These findings not only manifest that the long-recognized hP20-MoB4 (hP3-MoB2) and hR21-Mo2B5 should be hP16-MoB3 and hR18-MoB2, respectively, but also challenge the general design principle for ultrahard materials only pursuing the dense transition-metal borides with high boron content.

  10. Tuning thermal conductivity in molybdenum disulfide by electrochemical intercalation.

    PubMed

    Zhu, Gaohua; Liu, Jun; Zheng, Qiye; Zhang, Ruigang; Li, Dongyao; Banerjee, Debasish; Cahill, David G

    2016-10-21

    Thermal conductivity of two-dimensional (2D) materials is of interest for energy storage, nanoelectronics and optoelectronics. Here, we report that the thermal conductivity of molybdenum disulfide can be modified by electrochemical intercalation. We observe distinct behaviour for thin films with vertically aligned basal planes and natural bulk crystals with basal planes aligned parallel to the surface. The thermal conductivity is measured as a function of the degree of lithiation, using time-domain thermoreflectance. The change of thermal conductivity correlates with the lithiation-induced structural and compositional disorder. We further show that the ratio of the in-plane to through-plane thermal conductivity of bulk crystal is enhanced by the disorder. These results suggest that stacking disorder and mixture of phases is an effective mechanism to modify the anisotropic thermal conductivity of 2D materials.

  11. The Myszkow porphyry copper-molybdenum deposit, Poland

    USGS Publications Warehouse

    Chaffee, M.A.; Eppinger, R.G.; Lason, K.; Slosarz, J.; Podemski, M.

    1994-01-01

    The porphyry copper-molybdenum deposit at Myszkow, south-central Poland, lies in the Cracow-Silesian orogenic belt, in the vicinity of a Paleozoic boundary between two tectonic plates. The deposit is hosted in a complex that includes early Paleozoic metasedimentary rocks intruded in the late Paleozoic by a predominantly granodioritic pluton. This deposit exhibits many features that are typical of porphyry copper deposits associated with calc-alkaline intrusive rocks, including ore- and alteration-mineral suites, zoning of ore and alteration minerals, fluid-inclusion chemistry, tectonic setting, and structural style of veining. Unusual features of the Myszkow deposit include high concentrations of tungsten and the late Paleozoic (Variscan) age. -Authors

  12. Work function recovery of air exposed molybdenum oxide thin films

    NASA Astrophysics Data System (ADS)

    Irfan, Irfan; James Turinske, Alexander; Bao, Zhenan; Gao, Yongli

    2012-08-01

    We report substantial work function (WF) recovery of air exposed molybdenum oxide thin films with vacuum annealing. We observed a sharp reduction in the MoOx WF (from 6.8 eV to 5.6 eV) as well as a very thin layer of oxygen rich adsorbate on the MoOx film after an hour of air exposure. The WF of the exposed MoOx film started to gradually recover with increasing annealing temperature in vacuum, and the saturation in the WF recovery was observed at 450 °C with WF ˜6.4 eV. We further studied the interface formation between the annealed MoOx and copper phthalocyanine (CuPc). The highest occupied molecular orbital (HOMO) level of CuPc was observed to be almost pinned to the Fermi level, strongly suggesting the possibility of efficient hole injection with the vacuum annealed MoOx film.

  13. Predicting the stability of surface phases of molybdenum selenides

    SciTech Connect

    Roma, Guido; Ghorbani, Elaheh; Mirhosseini, Hossein; Kühne, Thomas D.; Kiss, Janos; Felser, Claudia

    2014-02-10

    The selenization of molybdenum might become an important step in the production of nanostructures based on the layered compound MoSe{sub 2}. It is already technologically relevant for the production of thin film chalcopyrite solar cells. However, the control of the process is still very poor, due to the lack of basic knowledge of the surface thermodynamics of the system. Here, we present a theoretical study on the stability of surface adlayers of Se on the Mo(110) surface, predicting surface patterns and their stability range in terms of temperature and selenium partial pressure. Our results, based on density functional theory, show that the attainable Se coverages range from 1/4 to 3/4 of a monolayer for systems in equilibrium with a gas formed of Se molecules. We provide simulated scanning tunneling microscopy images to help the experimental characterization of adsorbed surface patterns.

  14. 40 CFR 763.99 - Exclusions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT ASBESTOS Asbestos-Containing Materials in Schools § 763.99 Exclusions. (a) A local education agency shall not be... that school. (4) The lead agency responsible for asbestos inspection in a State that has been granted...

  15. 40 CFR 763.99 - Exclusions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT ASBESTOS Asbestos-Containing Materials in Schools § 763.99 Exclusions. (a) A local education agency shall not be... that school. (4) The lead agency responsible for asbestos inspection in a State that has been granted...

  16. 40 CFR 763.99 - Exclusions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT ASBESTOS Asbestos-Containing Materials in Schools § 763.99 Exclusions. (a) A local education agency shall not be... that school. (4) The lead agency responsible for asbestos inspection in a State that has been granted...

  17. 40 CFR 763.99 - Exclusions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT ASBESTOS Asbestos-Containing Materials in Schools § 763.99 Exclusions. (a) A local education agency shall not be... that school. (4) The lead agency responsible for asbestos inspection in a State that has been granted...

  18. 40 CFR 763.99 - Exclusions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT ASBESTOS Asbestos-Containing Materials in Schools § 763.99 Exclusions. (a) A local education agency shall not be... that school. (4) The lead agency responsible for asbestos inspection in a State that has been granted...

  19. 14 CFR 99.1 - Applicability.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SECURITY CONTROL OF AIR TRAFFIC General § 99.1 Applicability. (a) This... aircraft) in a defense area, or into, within, or out of the United States through an Air...

  20. SunBlock '99- An Educational Resource

    NASA Astrophysics Data System (ADS)

    Pike, C. D.; Mason, H. E.; Walsh, R. W.

    2000-04-01

    SunBlock `99 is a web-based Public Understanding of Science and educational project which presents the very latest solar research as seen through the eyes of young British scientists. It seeks both to increase public awareness of solar physics and to provide an educational resource for use in the classroom.

  1. 29 CFR 99.400 - Responsibilities.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Secretary of Labor AUDITS OF STATES, LOCAL GOVERNMENTS, AND NON-PROFIT ORGANIZATIONS Federal Agencies and Pass-through Entities § 99.400 Responsibilities. (a) Cognizant agency for audit responsibilities. Recipients expending more than $25 million a year in Federal awards shall have a cognizant agency for...

  2. Virulence Evolution Within the Ug99 Lineage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Race TTKSK (syn. Ug99) of Puccinia graminis f. sp. tritici, recognized for possessing virulence to the stem rust resistance gene Sr31, was first identified in Uganda in 1998. Since then, TTKSK has been identified in Kenya in 2005 and Yemen in 2006. In addition to virulence to Sr31, race TTKSK was ...

  3. Texas Almanac Teacher's Guide, 1998-99.

    ERIC Educational Resources Information Center

    Dallas Morning News, TX.

    This teacher's guide utilizes the subject matter in the 1998-99 Texas Almanac in a variety of interdisciplinary student activities for grades 3-8. The guide includes a grade-by-grade curriculum chart detailing which lessons correspond to specific Texas Assessment of Academic Skills (TAAS) objectives and Essential Element requirements. The 45…

  4. 46 CFR 111.99-3 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... REQUIREMENTS Fire Door Holding and Release Systems § 111.99-3 Definitions. As used in this subpart— Central... releasing one or more fire doors. Fire door means a door that is in a fire boundary, such as a stairway enclosure or main vertical zone bulkhead, that is not usually kept closed. Fire door holding magnet means...

  5. Projected 1998-99 Cost Allocation Summary.

    ERIC Educational Resources Information Center

    Chin, Edward

    Designed for use in calculating the distribution of state aid to colleges in the Wisconsin Technical College System (WTCS) and in preparing financial and enrollment reports, this document provides a summary of projected cost allocations for the WTCS for 1998-99, derived from data submitted by the colleges on cost allocation schedules. Following a…

  6. 27 CFR 21.99 - Brucine alkaloid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Brucine alkaloid. 21.99... Brucine alkaloid. (a) Identification test. Add a few drops of concentrated nitric acid to about 10 mg of brucine alkaloid. A vivid red color is produced. Dilute the red solution with a few drops of water and...

  7. 27 CFR 21.99 - Brucine alkaloid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Brucine alkaloid. 21.99... Brucine alkaloid. (a) Identification test. Add a few drops of concentrated nitric acid to about 10 mg of brucine alkaloid. A vivid red color is produced. Dilute the red solution with a few drops of water and...

  8. 27 CFR 21.99 - Brucine alkaloid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Brucine alkaloid. 21.99... Brucine alkaloid. (a) Identification test. Add a few drops of concentrated nitric acid to about 10 mg of brucine alkaloid. A vivid red color is produced. Dilute the red solution with a few drops of water and...

  9. 27 CFR 21.99 - Brucine alkaloid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Brucine alkaloid. 21.99... Brucine alkaloid. (a) Identification test. Add a few drops of concentrated nitric acid to about 10 mg of brucine alkaloid. A vivid red color is produced. Dilute the red solution with a few drops of water and...

  10. 27 CFR 21.99 - Brucine alkaloid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Brucine alkaloid. 21.99... Brucine alkaloid. (a) Identification test. Add a few drops of concentrated nitric acid to about 10 mg of brucine alkaloid. A vivid red color is produced. Dilute the red solution with a few drops of water and...

  11. 42 CFR 9.9 - Facility staffing.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... CHIMPANZEES HELD IN THE FEDERALLY SUPPORTED SANCTUARY SYSTEM § 9.9 Facility staffing. How many personnel are required to staff the chimpanzee sanctuary and what qualifications and training must the staff possess? (a... of the activities and chimpanzee population of the sanctuary. The level of staffing shall be...

  12. 42 CFR 9.9 - Facility staffing.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... CHIMPANZEES HELD IN THE FEDERALLY SUPPORTED SANCTUARY SYSTEM § 9.9 Facility staffing. How many personnel are required to staff the chimpanzee sanctuary and what qualifications and training must the staff possess? (a... of the activities and chimpanzee population of the sanctuary. The level of staffing shall be...

  13. 42 CFR 9.9 - Facility staffing.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... CHIMPANZEES HELD IN THE FEDERALLY SUPPORTED SANCTUARY SYSTEM § 9.9 Facility staffing. How many personnel are required to staff the chimpanzee sanctuary and what qualifications and training must the staff possess? (a... of the activities and chimpanzee population of the sanctuary. The level of staffing shall be...

  14. 42 CFR 9.9 - Facility staffing.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... CHIMPANZEES HELD IN THE FEDERALLY SUPPORTED SANCTUARY SYSTEM § 9.9 Facility staffing. How many personnel are required to staff the chimpanzee sanctuary and what qualifications and training must the staff possess? (a... of the activities and chimpanzee population of the sanctuary. The level of staffing shall be...

  15. 42 CFR 9.9 - Facility staffing.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... CHIMPANZEES HELD IN THE FEDERALLY SUPPORTED SANCTUARY SYSTEM § 9.9 Facility staffing. How many personnel are required to staff the chimpanzee sanctuary and what qualifications and training must the staff possess? (a... of the activities and chimpanzee population of the sanctuary. The level of staffing shall be...

  16. 2020 Vision Project Summary: FY99

    SciTech Connect

    K.W. Gordon; K.P. Scott

    2000-01-01

    During the 1998-99 school year, students from participating schools completed and submitted a variety of scenarios describing potential world and regional conditions in the year 2020 and their possible effect on U.S. national security. This report summarizes the student's views and describes trends observed over the course of the 2020 Vision project's four years.

  17. Plasma-flash radiography utilizing a molybdenum target in dentistry

    NASA Astrophysics Data System (ADS)

    Yamamoto, Mariko; Takabe, Akihito; Sakamaki, Kimio; Sato, Eiichi; Takahashi, Kei; Sagae, Michiaki; Oizumi, Teiji; Hayasi, Yasuomi; Sasaki, Katsuaki; Tamakawa, Yoshiharu; Yanagisawa, Toru

    1995-09-01

    The construction and the radiographic characteristics of a plasma flash x-ray generator having a molybdenum-target (anode tip) triode are described. This generator was primarily designed in order to perform soft radiography in dental medicine and employed the following essential components: a high-voltage power supply, a low-impedance coaxial transmission line with a gap switch, a coaxial oil condenser of 0.2 (mu) F, a turbo-molecular pump, a Krytron pulser as a trigger device, and a flash x-ray tube. The high-voltage main condenser of 0.2 (mu) F was charged from 40 to 60 kV by the power supply, and the electric charges in the condenser were discharged to the tube after closing the gap switch. Because this tube employed a long target, the plasma x-ray source which consists of molybdenum ions and electrons was easily produced by the target evaporating. The maximum tube voltage was nearly equivalent to the initial charge voltage of the main condenser, and the maximum current had a value of about 25 kA with a charging voltage of 60 kV. The average width of flash x rays was less than 1 microsecond(s) , and the time-integrated x-ray intensity with a charging voltage of 60 kV was approximately 20 (mu) C/kg at 1.0 m per pulse. The characteristic K-series intensity substantially increased according to increases in the charged voltage. High-speed dental radiography was performed using a laser timing switch and a trigger-delay device.

  18. Plasma-flash radiography utilizing a molybdenum target in dentistry

    SciTech Connect

    Yamamoto, Mariko; Takabe, Akihito; Sakamaki, Kimio

    1995-12-31

    The construction and the radiographic characteristics of a plasma flash x-ray generator having a molybdenum-target (anode tip) triode are described. This generator was primarily designed in order to perform soft radiography in dental medicine and employed the following essential components: a high-voltage power supply, a low-impedance coaxial transmission line with a gap switch, a coaxial oil condenser of 0.2 {micro}F, a turbo-molecular pump, a Krytron pulser as a trigger device, and a flash x-ray tube. The high-voltage main condenser of 0.2 {micro}F was charged from 40 to 60 kV by the power supply, and the electric charges in the condenser were discharged to the tube after closing the gap switch. Because this tube employed a long target, the plasma x-ray source which consists of molybdenum ions and electrons was easily produced by the target evaporating. The maximum tube voltage was nearly equivalent to the initial charging voltage of the main condenser, and the maximum current had a value of about 25 kA with a charging voltage of 60 kV. The average width of flash x rays was less than 1 {micro}s, and the time-integrated x-ray intensity with a charging voltage of 60 kV was approximately 20 {micro}C/kg at 1.0 m per pulse. The characteristic K-series intensity substantially increased according to increases in the charging voltage. High-speed dental radiography was performed by using a laser timing switch and a trigger-delay device.

  19. Soil organic matter regulates molybdenum storage and mobility in forests

    USGS Publications Warehouse

    Marks, Jade A; Perakis, Steven; King, Elizabeth K; Pett-Ridge, Julie

    2015-01-01

    The trace element molybdenum (Mo) is essential to a suite of nitrogen (N) cycling processes in ecosystems, but there is limited information on its distribution within soils and relationship to plant and bedrock pools. We examined soil, bedrock, and plant Mo variation across 24 forests spanning wide soil pH gradients on both basaltic and sedimentary lithologies in the Oregon Coast Range. We found that the oxidizable organic fraction of surface mineral soil accounted for an average of 33 %of bulk soil Mo across all sites, followed by 1.4 % associated with reducible Fe, Al, and Mn-oxides, and 1.4 % in exchangeable ion form. Exchangeable Mo was greatest at low pH, and its positive correlation with soil carbon (C) suggests organic matter as the source of readily exchangeable Mo. Molybdenum accumulation integrated over soil profiles to 1 m depth (τMoNb) increased with soil C, indicating that soil organic matter regulates long-term Mo retention and loss from soil. Foliar Mo concentrations displayed no relationship with bulk soil Mo, and were not correlated with organic horizon Mo or soil extractable Mo, suggesting active plant regulation of Mo uptake and/or poor fidelity of extractable pools to bioavailability. We estimate from precipitation sampling that atmospheric deposition supplies, on average, over 10 times more Mo annually than does litterfall to soil. In contrast, bedrock lithology had negligible effects on foliar and soil Mo concentrations and on Mo distribution among soil fractions. We conclude that atmospheric inputs may be a significant source of Mo to forest ecosystems, and that strong Mo retention by soil organic matter limits ecosystem Mo loss via dissolution and leaching pathways.

  20. High-strength, creep-resistant molybdenum alloy and process for producing the same

    SciTech Connect

    Bianco, Robert; Buckman, Jr. William R.; Geller, Clint B.

    1997-12-01

    A wet-doping process for producing an oxide-dispersion strengthened (ODS), creep-resistant molybdenum alloy is disclosed. The alloy is made by adding nitrate or acetate salts of lanthanum, cerium, thorium, or yttrium to molybdenum oxide to produce a slurry, heating the slurry in a hydrogen atmosphere to produce a powder, mixing and cold isostatically pressing the powder, sintering in a hydrogen atmosphere, and thermomechanically processing (swaging, extruding, cold drawing) the product. The ODS molybdenum alloy produced by the process contains 2--4% by volume ({approximately}1--4% by weight) of an oxide of lanthanum, cerium, thorium, or yttrium. The alloy has high strength and improved creep-resistance at temperatures greater than 0.55T{sub m} of molybdenum.