Science.gov

Sample records for misch metal

  1. Mn in misch-metal based superlattice metal hydride alloy - Part 1 structural, hydrogen storage and electrochemical properties

    NASA Astrophysics Data System (ADS)

    Young, K.; Wong, D. F.; Wang, L.; Nei, J.; Ouchi, T.; Yasuoka, S.

    2015-03-01

    The structural, gaseous phase hydrogen storage, and electrochemical properties of a series of Mn-modified misch-metal based superlattice metal hydride alloys were investigated in part one of this two-part series of papers. X-ray diffraction analysis showed that these alloys are all multi-phased compositions with different abundances of AB2, AB3, A2B7, AB4, and AB5 phases. Substitution of Ni in the B-site by Mn promotes AB5 phase formation and decreases both gaseous phase and electrochemical capacities due to the reduction in the abundance of main hexagonal A2B7 phase. AC impedance and magnetic susceptibility measurement were employed to characterize the surface of Mn-free and Mn-modified alloys and show deterioration in surface catalytic ability as the Mn-content increases. Mn-modification adversely affected misch-metal based superlattice metal hydride alloy properties such as phase homogeneity, capacity, cycle stability, high-rate performance, and surface reaction.

  2. Achievement of high coercivity in sintered R-Fe-B magnets based on misch-metal by dual alloy method

    SciTech Connect

    Niu, E Wang, Zhen-Xi; Chen, Zhi-An; Rao, Xiao-Lei; Hu, Bo-Ping; Chen, Guo-An; Zhao, Yu-Gang; Zhang, Jin

    2014-03-21

    The R-Fe-B (R, rare earth) sintered magnets prepared with different ratio of alloys of MM-Fe-B (MM, misch-metal) and Nd-Fe-B by dual alloy method were investigated. As expected, the high ratio of MM-Fe-B alloy degrades the hard magnetic properties heavily with intrinsic coercivity lower than 5 kOe. When the atomic ratio MM/R ≤ 21.5% the magnetic properties can reach a practical level of B{sub r} ≥ 12.1 kGs, H{sub cj} ≥ 10.7 kOe, and (BH){sub max} ≥ 34.0 MGOe. And the effect of H{sub cj} enhancement by the grain boundary diffusion process is obvious when MM/R ≤ 21.5%. It is revealed that the decrement of intrinsic magnetic properties of R{sub 2}Fe{sub 14}B matrix phase is not the main reason of the degradation of the magnets with high MM ratio. The change of deteriorated microstructure together with phase component plays fundamental roles in low H{sub cj}. In high MM ratio magnets, (a) after annealing, Ce atoms inside main phase are inclined to be segregated in the outer layer of the main phase grains; (b) there is no thin layer of Ce-rich phase as an analogue of Nd-rich phase to separate main phase grains; (c) excessive Ce tends to form CeFe{sub 2} grains.

  3. Two stage surgery in IV Class of Misch with SIS device: a case report.

    PubMed

    Grandi, C; Pacifici, L

    2008-10-01

    In IV Class of Misch classification is usually not possible insert fixtures at the same time of the sinus lift procedure. To solve all these situation the use of several appliances have been proposed. Among those the S.I.S. titan plane is the easiest to use. The S.I.S. plane allows to stabilize implants without primary stability and to fix them to osseous ridge. In IV Class of Misch it brings to a real treatment shortening. After six and twelve months RX assessments show bone levels comparables to literature implant success criteria. This technique seems to reach success in Misch IV Class with simultaneous insertion of dental implants, with a simple procedure and without further traumaticity. Literature on S.I.S. plane is lacking and mostly based on case reports. A further investigation based on a larger number of patients is needed.

  4. Sinus implants stabilization in Misch IV Class by means of S.I.S. device: A Clinical Study.

    PubMed

    Grandi, C; Pacifici, L

    2009-10-01

    AIMS.: In Misch Class IV dental implants are not normally placed at the same time as the sinus lift procedure. For this type of situation the use of several devices to immediately stabilise implants lacking in primary stability is proposed. Among these, the titanium S.I.S. plate results as being the most straightforward. This study proposes the evaluation of the effectiveness and stability of the results of this method in the short term on a greater number of patients, monitoring bones levels and implant stability. METHOD.: 14 patients were selected, 9 males and 5 females, aged between 43 and 75 years of age. Overall, 42 implants were placed in the upper posterior edentulous zones with Misch Class IV atrophy including first and second premolars and first molars, opposite fixed teeth, and were stabilised using the S.I.S. plate. RESULTS.: Radiographic controls and ISQ measurements with AFR at 1, 6 and 12 months after loading testify to the stability of the bone levels which concur with success criteria found in literature. The technique described seems to be able to ensure success in cases of Misch Class IV with contemporaneous placement of the osseo-integrated implants. CONCLUSION.: This clinical study, even if carried out on a small number of patients (14) and implants (42) represents the largest case history published. The technique described seems to ensure the success of cases of Misch Class IV with contemporaneous placement of osseo-integrated implants. The technique is straightforward and reproducible and does not cause further trauma. The S.I.S. allows for the stabilisation of the dental implants and the residual crest when there is a lack of primary stability. In Misch Class IV this means a considerable reduction in treatment times.

  5. [Johann Misch Astrophilus' book "Medicina Pauperum" in Hungarian. Copy of a lost or hidden book from 1660].

    PubMed

    Kiss, István; Tavaszy, Mariann; Kiss, Gergely

    2011-07-01

    Doctors and pharmacies in the 15th Century only used handwritten copies of the prescription collections available in their time. At the beginning of book printing the publishing of prescription collections immediately became popular. They could be found on the pages of medical and pharmaceutical books of many various editions with different structure and origin, as the forerunner of the official pharmacopoeias. From the 16th Century onwards books with the title "Medicina Pauperum" were published which helped the educated people to tend to themselves, the household, the servants and their immediate surroundings case of an illness. The first work specifically on the topic or of genre of the "Medicina Pauperum" according to our knowledge appeared in Hungarian in the year 1660 and currently seems to survived only in fragments under the title of "Medicina Pauperum", from an unknown author. A rare incident occurred in the present days as a "book" believed to be lost for us turned up from thin air. It is a "copied" manuscript in the size of 97×139 mm attached to the ribs with hemp cord, cropped around and in an unbound state. The book known before only in fractions is now available entirety handwritten on 318 pages, distributed to seven distinct parts. The research of its origin suggests that the author lived and worked in Nagyszombat and was called Johann Misch Astrophilus. The identification of the printing office was possible thanks to the examination of the initials and the gaudily, as well as the fonts and the watermark. By these results the printing very likely occurred in the Brewer Printing Press in Lőcse. For the possibility of more extensive research and value preservation the manuscript was bounded. The facsimile edition contains the magnified and digitalized pages of the original one and is published in numbered issues.

  6. Metal Preferences and Metallation*

    PubMed Central

    Foster, Andrew W.; Osman, Deenah; Robinson, Nigel J.

    2014-01-01

    The metal binding preferences of most metalloproteins do not match their metal requirements. Thus, metallation of an estimated 30% of metalloenzymes is aided by metal delivery systems, with ∼25% acquiring preassembled metal cofactors. The remaining ∼70% are presumed to compete for metals from buffered metal pools. Metallation is further aided by maintaining the relative concentrations of these pools as an inverse function of the stabilities of the respective metal complexes. For example, magnesium enzymes always prefer to bind zinc, and these metals dominate the metalloenzymes without metal delivery systems. Therefore, the buffered concentration of zinc is held at least a million-fold below magnesium inside most cells. PMID:25160626

  7. Metal aminoboranes

    DOEpatents

    Burrell, Anthony K.; Davis, Benjamin J.; Thorn, David L.; Gordon, John C.; Baker, R. Thomas; Semelsberger, Troy Allen; Tumas, William; Diyabalanage, Himashinie Vichalya Kaviraj; Shrestha, Roshan P.

    2010-05-11

    Metal aminoboranes of the formula M(NH.sub.2BH.sub.3).sub.n have been synthesized. Metal aminoboranes are hydrogen storage materials. Metal aminoboranes are also precursors for synthesizing other metal aminoboranes. Metal aminoboranes can be dehydrogenated to form hydrogen and a reaction product. The reaction product can react with hydrogen to form a hydrogen storage material. Metal aminoboranes can be included in a kit.

  8. Metal inks

    DOEpatents

    Ginley, David S; Curtis, Calvin J; Miedaner, Alex; van Hest, Marinus Franciscus Antonius Maria; Kaydanova, Tatiana

    2014-02-04

    Self-reducing metal inks and systems and methods for producing and using the same are disclosed. In an exemplary embodiment, a method may comprise selecting metal-organic (MO) precursor, selecting a reducing agent, and dissolving the MO precursor and the reducing agent in an organic solvent to produce a metal ink that remains in a liquid phase at room temperature. Metal inks, including self-reducing and fire-through metal inks, are also disclosed, as are various applications of the metal inks.

  9. METAL PHTHALOCYANINES

    DOEpatents

    Frigerio, N.A.

    1962-03-27

    A process is given for preparing heavy metal phthalocyanines, sulfonated or not. The process comprises mixing an inorganic metal salt with dimethyl formamide or methyl sulfoxide; separating the metal complex formed from the solution; mixing the complex with an equimolar amount of sodium, potassium, lithium, magnesium, or beryllium sulfonated or unsulfonated phthalocyanine whereby heavy-metal phthalocyanine crystals are formed; and separating the crystals from the solution. Uranyl, thorium, lead, hafnium, and lanthanide rare earth phthalocyanines can be produced by the process. (AEC)

  10. Silicone metalization

    DOEpatents

    Maghribi, Mariam N.; Krulevitch, Peter; Hamilton, Julie

    2008-12-09

    A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

  11. Silicone metalization

    DOEpatents

    Maghribi, Mariam N.; Krulevitch, Peter; Hamilton, Julie

    2006-12-05

    A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

  12. Metallic glasses.

    PubMed

    Greer, A L

    1995-03-31

    Amorphous metallic alloys, relative newcomers to the world of glasses, have properties that are unusual for solid metals. The metallic glasses, which exist in a very wide variety of compositions, combine fundamental interest with practical applications. They also serve as precursors for exciting new nanocrystalline materials. Their magnetic (soft and hard) and mechanical properties are of particular interest.

  13. Metal oxide films on metal

    DOEpatents

    Wu, Xin D.; Tiwari, Prabhat

    1995-01-01

    A structure including a thin film of a conductive alkaline earth metal oxide selected from the group consisting of strontium ruthenium trioxide, calcium ruthenium trioxide, barium ruthenium trioxide, lanthanum-strontium cobalt oxide or mixed alkaline earth ruthenium trioxides thereof upon a thin film of a noble metal such as platinum is provided.

  14. Metal Coatings

    NASA Technical Reports Server (NTRS)

    1994-01-01

    During the Apollo Program, General Magnaplate Corporation developed process techniques for bonding dry lubricant coatings to space metals. The coatings were not susceptible to outgassing and offered enhanced surface hardness and superior resistance to corrosion and wear. This development was necessary because conventional lubrication processes were inadequate for lightweight materials used in Apollo components. General Magnaplate built on the original technology and became a leader in development of high performance metallurgical surface enhancement coatings - "synergistic" coatings, - which are used in applications from pizza making to laser manufacture. Each of the coatings is designed to protect a specific metal or group of metals to solve problems encountered under operating conditions.

  15. Metals 2000

    SciTech Connect

    Allison, S.W.; Rogers, L.C.; Slaughter, G.; Boensch, F.D.; Claus, R.O.; de Vries, M.

    1993-05-01

    This strategic planning exercise identified and characterized new and emerging advanced metallic technologies in the context of the drastic changes in global politics and decreasing fiscal resources. In consideration of a hierarchy of technology thrusts stated by various Department of Defense (DOD) spokesmen, and the need to find new and creative ways to acquire and organize programs within an evolving Wright Laboratory, five major candidate programs identified are: C-17 Flap, Transport Fuselage, Mach 5 Aircraft, 4.Fighter Structures, and 5. Missile Structures. These results were formed by extensive discussion with selected major contractors and other experts, and a survey of advanced metallic structure materials. Candidate structural applications with detailed metal structure descriptions bracket a wide variety of uses which warrant consideration for the suggested programs. An analysis on implementing smart skins and structures concepts is given from a metal structures perspective.

  16. Metallic Hydrogen

    NASA Astrophysics Data System (ADS)

    Silvera, Isaac; Zaghoo, Mohamed; Salamat, Ashkan

    2015-03-01

    Hydrogen is the simplest and most abundant element in the Universe. At high pressure it is predicted to transform to a metal with remarkable properties: room temperature superconductivity, a metastable metal at ambient conditions, and a revolutionary rocket propellant. Both theory and experiment have been challenged for almost 80 years to determine its condensed matter phase diagram, in particular the insulator-metal transition. Hydrogen is predicted to dissociate to a liquid atomic metal at multi-megabar pressures and T =0 K, or at megabar pressures and very high temperatures. Thus, its predicted phase diagram has a broad field of liquid metallic hydrogen at high pressure, with temperatures ranging from thousands of degrees to zero Kelvin. In a bench top experiment using static compression in a diamond anvil cell and pulsed laser heating, we have conducted measurements on dense hydrogen in the region of 1.1-1.7 Mbar and up to 2200 K. We observe a first-order phase transition in the liquid phase, as well as sharp changes in optical transmission and reflectivity when this phase is entered. The optical signature is that of a metal. The mapping of the phase line of this transition is in excellent agreement with recent theoretical predictions for the long-sought plasma phase transition to metallic hydrogen. Research supported by the NSF, Grant DMR-1308641, the DOE Stockpile Stewardship Academic Alliance Program, Grant DE-FG52-10NA29656, and NASA Earth and Space Science Fellowship Program, Award NNX14AP17H.

  17. Metal nanoshells.

    PubMed

    Hirsch, Leon R; Gobin, Andre M; Lowery, Amanda R; Tam, Felicia; Drezek, Rebekah A; Halas, Naomi J; West, Jennifer L

    2006-01-01

    Metal nanoshells are a new class of nanoparticles with highly tunable optical properties. Metal nanoshells consist of a dielectric core nanoparticle such as silica surrounded by an ultrathin metal shell, often composed of gold for biomedical applications. Depending on the size and composition of each layer of the nanoshell, particles can be designed to either absorb or scatter light over much of the visible and infrared regions of the electromagnetic spectrum, including the near infrared region where penetration of light through tissue is maximal. These particles are also effective substrates for surface-enhanced Raman scattering (SERS) and are easily conjugated to antibodies and other biomolecules. One can envision a myriad of potential applications of such tunable particles. Several potential biomedical applications are under development, including immunoassays, modulated drug delivery, photothermal cancer therapy, and imaging contrast agents. PMID:16528617

  18. Metallized Products

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Since the early 1960's, virtually all NASA spacecraft have used metallized films for a variety of purposes, principally thermal radiation insulation. King Seeley manufactures a broad line of industrial and consumer oriented metallized film, fabric, paper and foam in single layer sheets and multi-layer laminates. A few examples, commercialized by MPI Outdoor Safety Products, are the three ounce Thermos Emergency Blanket which reflects and retains up to 80 percent of the user's body heat helping prevent post accident shock or keeping a person warm for hours under emergency cold weather conditions.

  19. METAL COMPOSITIONS

    DOEpatents

    Seybolt, A.U.

    1959-02-01

    Alloys of uranium which are strong, hard, and machinable are presented, These alloys of uranium contain bctween 0.1 to 5.0% by weight of at least one noble metal such as rhodium, palladium, and gold. The alloys may be heat treated to obtain a product with iniproved tensile and compression strengths,

  20. Heavy Metal.

    ERIC Educational Resources Information Center

    Shoemaker, W. Lee

    1998-01-01

    Discusses the advantages, both functional and economic, of using a standing-seam metal roof in both new roof installations and reroofing projects of educational facilities. Structural versus non-structural standing-seam roofs are described as are the types of insulation that can be added and roof finishes used. (GR)

  1. Composite metal membrane

    DOEpatents

    Peachey, N.M.; Dye, R.C.; Snow, R.C.; Birdsell, S.A.

    1998-04-14

    A composite metal membrane including a first metal layer of Group IVB met or Group VB metals, the first metal layer sandwiched between two layers of an oriented metal of palladium, platinum or alloys thereof is provided together with a process for the recovery of hydrogen from a gaseous mixture including contacting a hydrogen-containing gaseous mixture with a first side of a nonporous composite metal membrane including a first metal of Group IVB metals or Group VB metals, the first metal layer sandwiched between two layers of an oriented metal of palladium, platinum or alloys thereof, and, separating hydrogen from a second side of the nonporous composite metal membrane.

  2. Composite metal membrane

    DOEpatents

    Peachey, Nathaniel M.; Dye, Robert C.; Snow, Ronny C.; Birdsell, Stephan A.

    1998-01-01

    A composite metal membrane including a first metal layer of Group IVB met or Group VB metals, the first metal layer sandwiched between two layers of an oriented metal of palladium, platinum or alloys thereof is provided together with a process for the recovery of hydrogen from a gaseous mixture including contacting a hydrogen-containing gaseous mixture with a first side of a nonporous composite metal membrane including a first metal of Group IVB metals or Group VB metals, the first metal layer sandwiched between two layers of an oriented metal of palladium, platinum or alloys thereof, and, separating hydrogen from a second side of the nonporous composite metal membrane.

  3. Clad metal joint closure

    SciTech Connect

    Siebert, O.W.

    1985-04-09

    A plasma arc spray overlay of cladding metals is used over joints between clad metal pieces to provide a continuous cladding metal surface. The technique permits applying an overlay of a high melting point cladding metal to a cladding metal surface without excessive heating of the backing metal.

  4. Metal dusting

    SciTech Connect

    Edited by K. Natesan

    2004-01-01

    This workshop was held soon after the September 11th incident under a climate of sorrow and uncertainty among the people of the world, in particular the Workshop participants and their host organizations. With considerable help from the partiicpants, the Workshop was conducted as planed and we had excellent participation in spite of the circumstances. A good fraction of the attendees in the Workshop were from abroad and from several industries, indicating the importance and relevance of the subject for the chemical process industry. Degradation of structural metallic alloys by metal dusting has been an issue for over 40 years in the chemical, petrochemical, syngas, and iron ore reduction plants. However, the fundamental scientific reasons for the degradation of complex alloys in high carbon activity environments are not clear. one of the major parameters of importance is the variation in gas chemistry in both the laboratory experiments and in the plant-service environments. the industry has questioned the applicability of the laboratory test data, obtained in low steam environments, in assessment and life prediction for the materials in plant service where the environments contain 25-35% steam. Several other variables such as system pressure, gas flow velocity, incubation time, alloy chemistry, surface finish, and weldments, were also identified in the literature as to having an effect on the initiatino and propagation of metal dusting attack. It is the purpose of this Workshop to establish a forum in which the researchers from scientific and industrial laboratories, alloy manufacturers, end users, and research and development sponsors can exchange information, discuss different points of view, prioritize the issues, and to elaborate on the trends in industry for the future. We believe that we accomplished these goals successfully and sincerely thank the participants for their contributions.

  5. Mechanochemical processing for metals and metal alloys

    DOEpatents

    Froes, Francis H.; Eranezhuth, Baburaj G.; Prisbrey, Keith

    2001-01-01

    A set of processes for preparing metal powders, including metal alloy powders, by ambient temperature reduction of a reducible metal compound by a reactive metal or metal hydride through mechanochemical processing. The reduction process includes milling reactants to induce and complete the reduction reaction. The preferred reducing agents include magnesium and calcium hydride powders. A process of pre-milling magnesium as a reducing agent to increase the activity of the magnesium has been established as one part of the invention.

  6. Metal filled porous carbon

    DOEpatents

    Gross, Adam F.; Vajo, John J.; Cumberland, Robert W.; Liu, Ping; Salguero, Tina T.

    2011-03-22

    A porous carbon scaffold with a surface and pores, the porous carbon scaffold containing a primary metal and a secondary metal, where the primary metal is a metal that does not wet the surface of the pores of the carbon scaffold but wets the surface of the secondary metal, and the secondary metal is interspersed between the surface of the pores of the carbon scaffold and the primary metal.

  7. Extracting metals directly from metal oxides

    DOEpatents

    Wai, Chien M.; Smart, Neil G.; Phelps, Cindy

    1997-01-01

    A method of extracting metals directly from metal oxides by exposing the oxide to a supercritical fluid solvent containing a chelating agent is described. Preferably, the metal is an actinide or a lanthanide. More preferably, the metal is uranium, thorium or plutonium. The chelating agent forms chelates that are soluble in the supercritical fluid, thereby allowing direct removal of the metal from the metal oxide. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is selected from the group consisting of .beta.-diketones, halogenated .beta.-diketones, phosphinic acids, halogenated phosphinic acids, carboxylic acids, halogenated carboxylic acids, and mixtures thereof. In especially preferred embodiments, at least one of the chelating agents is fluorinated. The method provides an environmentally benign process for removing metals from metal oxides without using acids or biologically harmful solvents. The chelate and supercritical fluid can be regenerated, and the metal recovered, to provide an economic, efficient process.

  8. Extracting metals directly from metal oxides

    DOEpatents

    Wai, C.M.; Smart, N.G.; Phelps, C.

    1997-02-25

    A method of extracting metals directly from metal oxides by exposing the oxide to a supercritical fluid solvent containing a chelating agent is described. Preferably, the metal is an actinide or a lanthanide. More preferably, the metal is uranium, thorium or plutonium. The chelating agent forms chelates that are soluble in the supercritical fluid, thereby allowing direct removal of the metal from the metal oxide. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is selected from the group consisting of {beta}-diketones, halogenated {beta}-diketones, phosphinic acids, halogenated phosphinic acids, carboxylic acids, halogenated carboxylic acids, and mixtures thereof. In especially preferred embodiments, at least one of the chelating agents is fluorinated. The method provides an environmentally benign process for removing metals from metal oxides without using acids or biologically harmful solvents. The chelate and supercritical fluid can be regenerated, and the metal recovered, to provide an economic, efficient process. 4 figs.

  9. Metals production

    NASA Astrophysics Data System (ADS)

    Beck, Theodore S.

    1992-02-01

    Existing procedures for design of electrochemical plants can be used for design of lunar processes taking into consideration the differences in environmental conditions. These differences include: 1/6 Earth gravity, high vacuum, solar electrical and heat source, space radiation heat sink, long days and nights, and different availability and economics of materials, energy, and labor. Techniques have already been developed for operation of relatively small scale hydrogen-oxygen fuel cell systems used in the U.S. lunar landing program. Design and operation of lunar aqueous electrolytic process plants appears to be within the state-of-the-art. Finding or developing compatible materials for construction and designing of fused-magma metal winning cells will present a real engineering challenge.

  10. Metals production

    NASA Technical Reports Server (NTRS)

    Beck, Theodore S.

    1992-01-01

    Existing procedures for design of electrochemical plants can be used for design of lunar processes taking into consideration the differences in environmental conditions. These differences include: 1/6 Earth gravity, high vacuum, solar electrical and heat source, space radiation heat sink, long days and nights, and different availability and economics of materials, energy, and labor. Techniques have already been developed for operation of relatively small scale hydrogen-oxygen fuel cell systems used in the U.S. lunar landing program. Design and operation of lunar aqueous electrolytic process plants appears to be within the state-of-the-art. Finding or developing compatible materials for construction and designing of fused-magma metal winning cells will present a real engineering challenge.

  11. Neurotoxicity of metals.

    PubMed

    Caito, Samuel; Aschner, Michael

    2015-01-01

    Metals are frequently used in industry and represent a major source of toxin exposure for workers. For this reason governmental agencies regulate the amount of metal exposure permissible for worker safety. While essential metals serve physiologic roles, metals pose significant health risks upon acute and chronic exposure to high levels. The central nervous system is particularly vulnerable to metals. The brain readily accumulates metals, which under physiologic conditions are incorporated into essential metalloproteins required for neuronal health and energy homeostasis. Severe consequences can arise from circumstances of excess essential metals or exposure to toxic nonessential metal. Herein, we discuss sources of occupational metal exposure, metal homeostasis in the human body, susceptibility of the nervous system to metals, detoxification, detection of metals in biologic samples, and chelation therapeutic strategies. The neurologic pathology and physiology following aluminum, arsenic, lead, manganese, mercury, and trimethyltin exposures are highlighted as classic examples of metal-induced neurotoxicity.

  12. Neurotoxicity of metals.

    PubMed

    Caito, Samuel; Aschner, Michael

    2015-01-01

    Metals are frequently used in industry and represent a major source of toxin exposure for workers. For this reason governmental agencies regulate the amount of metal exposure permissible for worker safety. While essential metals serve physiologic roles, metals pose significant health risks upon acute and chronic exposure to high levels. The central nervous system is particularly vulnerable to metals. The brain readily accumulates metals, which under physiologic conditions are incorporated into essential metalloproteins required for neuronal health and energy homeostasis. Severe consequences can arise from circumstances of excess essential metals or exposure to toxic nonessential metal. Herein, we discuss sources of occupational metal exposure, metal homeostasis in the human body, susceptibility of the nervous system to metals, detoxification, detection of metals in biologic samples, and chelation therapeutic strategies. The neurologic pathology and physiology following aluminum, arsenic, lead, manganese, mercury, and trimethyltin exposures are highlighted as classic examples of metal-induced neurotoxicity. PMID:26563789

  13. Metal-phosphate binders

    SciTech Connect

    Howe, Beth Ann; Chaps-Cabrera, Jesus Guadalupe

    2009-05-12

    A metal-phosphate binder is provided. The binder may include an aqueous phosphoric acid solution, a metal-cation donor including a metal other than aluminum, an aluminum-cation donor, and a non-carbohydrate electron donor.

  14. Memory Metals

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Under contract to NASA during preparations for the space station, Memry Technologies Inc. investigated shape memory effect (SME). SME is a characteristic of certain metal alloys that can change shape in response to temperature variations. In the late 1980s and early 1990s, Memry used its NASA-acquired expertise to produce a line of home and industrial safety products, and refined the technology in the mid-1990s. Among the new products they developed are three MemrySafe units which prevent scalding from faucets. Each system contains a small valve that reacts to temperature, not pressure. When the water reaches dangerous temperatures, the unit reduces the flow to a trickle; when the scalding temperature subsides, the unit restores normal flow. Other products are the FIRECHEK 2 and 4, heat-activated shutoff valves for industrial process lines, which sense excessive heat and cut off pneumatic pressure. The newest of these products is Memry's Demand Management Water Heater which shifts the electricity requirement from peak to off-peak demands, conserving energy and money.

  15. METAL PRODUCTION AND CASTING

    DOEpatents

    Magel, T.T.

    1958-03-01

    This patent covers a method and apparatus for collecting the molten metal produced by high temperature metal salt reduction. It consists essentially of subjecting the reaction vessel to centrifugal force in order to force the liberatcd molten metal into a coherent molten mass, and allowing it to solidify there. The apparatus is particularly suitable for use with small quantities of rare metals.

  16. Ceramic to metal seal

    DOEpatents

    Snow, Gary S.; Wilcox, Paul D.

    1976-01-01

    Providing a high strength, hermetic ceramic to metal seal by essentially heating a wire-like metal gasket and a ceramic member, which have been chemically cleaned, while simultaneously deforming from about 50 to 95 percent the metal gasket against the ceramic member at a temperature of about 30 to 75 percent of the melting temperature of the metal gasket.

  17. Fabrication of metal nanoshells

    NASA Technical Reports Server (NTRS)

    Kim, Jae-Woo (Inventor); Choi, Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, Jr., James R. (Inventor)

    2012-01-01

    Metal nanoshells are fabricated by admixing an aqueous solution of metal ions with an aqueous solution of apoferritin protein molecules, followed by admixing an aqueous solution containing an excess of an oxidizing agent for the metal ions. The apoferritin molecules serve as bio-templates for the formation of metal nanoshells, which form on and are bonded to the inside walls of the hollow cores of the individual apoferritin molecules. Control of the number of metal atoms which enter the hollow core of each individual apoferritin molecule provides a hollow metal nonparticle, or nanoshell, instead of a solid spherical metal nanoparticle.

  18. Amorphous metal composites

    DOEpatents

    Byrne, Martin A.; Lupinski, John H.

    1984-01-01

    An improved amorphous metal composite and process of making the composite. The amorphous metal composite comprises amorphous metal (e.g. iron) and a low molecular weight thermosetting polymer binder. The process comprises placing an amorphous metal in particulate form and a thermosetting polymer binder powder into a container, mixing these materials, and applying heat and pressure to convert the mixture into an amorphous metal composite.

  19. Metal phthalocyanine polymers

    NASA Technical Reports Server (NTRS)

    Achar, B. N.; Fohlen, G. M.; Parker, J. A. (Inventor)

    1984-01-01

    Metal 4, 4', 4", 4"'=tetracarboxylic phthalocyanines (MPTC) are prepared by reaction of trimellitic anhydride, a salt or hydroxide of the desired metal (or the metal in powdered form), urea and a catalyst. A purer form of MPTC is prepared than heretofore. These tetracarboxylic acids are then polymerized by heat to sheet polymers which have superior heat and oxidation resistance. The metal is preferably a divalent metal having an atomic radius close to 1.35A.

  20. Predicting dietborne metal toxicity from metal influxes

    USGS Publications Warehouse

    Croteau, M.-N.; Luoma, S.N.

    2009-01-01

    Dietborne metal uptake prevails for many species in nature. However, the links between dietary metal exposure and toxicity are not well understood. Sources of uncertainty include the lack of suitable tracers to quantify exposure for metals such as copper, the difficulty to assess dietary processes such as food ingestion rate, and the complexity to link metal bioaccumulation and effects. We characterized dietborne copper, nickel, and cadmium influxes in a freshwater gastropod exposed to diatoms labeled with enriched stable metal isotopes. Metal influxes in Lymnaea stagnalis correlated linearly with dietborne metal concentrations over a range encompassing most environmental exposures. Dietary Cd and Ni uptake rate constants (kuf) were, respectively, 3.3 and 2.3 times higher than that for Cu. Detoxification rate constants (k detox) were similar among metals and appeared 100 times higher than efflux rate constants (ke). Extremely high Cu concentrations reduced feeding rates, causing the relationship between exposure and influx to deviate from linearity; i.e., Cu uptake rates leveled off between 1500 and 1800 nmol g-1 day-1. L. stagnalis rapidly takes up Cu, Cd, and Ni from food but detoxifies the accumulated metals, instead of reducing uptake or intensifying excretion. Above a threshold uptake rate, however, the detoxification capabilities of L. stagnalis are overwhelmed.

  1. Predicting dietborne metal toxicity from metal influxes.

    PubMed

    Croteau, Marie-Noële; Luoma, Samuel N

    2009-07-01

    Dietborne metal uptake prevails for many species in nature. However, the links between dietary metal exposure and toxicity are not well understood. Sources of uncertainty include the lack of suitable tracers to quantify exposure for metals such as copper, the difficulty to assess dietary processes such as food ingestion rate, and the complexity to link metal bioaccumulation and effects. We characterized dietborne copper, nickel, and cadmium influxes in a freshwater gastropod exposed to diatoms labeled with enriched stable metal isotopes. Metal influxes in Lymnaea stagnalis correlated linearly with dietborne metal concentrations over a range encompassing most environmental exposures. Dietary Cd and Ni uptake rate constants (k(uf)) were, respectively, 3.3 and 2.3 times higher than thatfor Cu. Detoxification rate constants (k(detox)) were similar among metals and appeared 100 times higher than efflux rate constants (K(e)). Extremely high Cu concentrations reduced feeding rates, causing the relationship between exposure and influx to deviate from linearity, i.e., Cu uptake rates leveled off between 1500 and 1800 nmol g(-1) day(-1). L. stagnalis rapidly takes up Cu, Cd, and Ni from food but detoxifies the accumulated metals, instead of reducing uptake or intensifying excretion. Above a threshold uptake rate, however, the detoxification capabilities of L. stagnalis are overwhelmed.

  2. Metal-Air Batteries

    SciTech Connect

    Zhang, Jiguang; Bruce, Peter G.; Zhang, Gregory

    2011-08-01

    Metal-air batteries have much higher specific energies than most currently available primary and rechargeable batteries. Recent advances in electrode materials and electrolytes, as well as new designs on metal-air batteries, have attracted intensive effort in recent years, especially in the development of lithium-air batteries. The general principle in metal-air batteries will be reviewed in this chapter. The materials, preparation methods, and performances of metal-air batteries will be discussed. Two main metal-air batteries, Zn-air and Li-air batteries will be discussed in detail. Other type of metal-air batteries will also be described.

  3. Alkali metal nitrate purification

    DOEpatents

    Fiorucci, Louis C.; Morgan, Michael J.

    1986-02-04

    A process is disclosed for removing contaminants from impure alkali metal nitrates containing them. The process comprises heating the impure alkali metal nitrates in solution form or molten form at a temperature and for a time sufficient to effect precipitation of solid impurities and separating the solid impurities from the resulting purified alkali metal nitrates. The resulting purified alkali metal nitrates in solution form may be heated to evaporate water therefrom to produce purified molten alkali metal nitrates suitable for use as a heat transfer medium. If desired, the purified molten form may be granulated and cooled to form discrete solid particles of purified alkali metal nitrates.

  4. When are thin films of metals metallic?

    NASA Astrophysics Data System (ADS)

    Plummer, E. W.; Dowben, P. A.

    1993-04-01

    There is an increasing body of experimental information suggesting that very thin films of materials, normally considered to be metals, exhibit behavior characteristic of a nonmetal. In almost all cases, there is a nonmetal-to-metal transition as a function of film density or thickness, frequently accompanied by a structural transition. Amazingly, this behavior seems to occur for metal films on metal substrates, as well as for metals on semiconductors. The identification of this phenomena and the subsequent explanation has been slow in developing, due to the inability to directly measure the conductivity of a submonolayer film. This paper will discuss the evidence accumulated from variety of spectroscopic experimental techniques for three systems: a Mott-Hubbard transition, a Peierls-like distortion, and a Wilson transition.

  5. Metal-on-metal hip joint tribology.

    PubMed

    Dowson, D; Jin, Z M

    2006-02-01

    The basic tribological features of metal-on-metal total hip replacements have been reviewed to facilitate an understanding of the engineering science underpinning the renaissance of these hard-on-hard joints. Metal-on-polymer hip replacements operate in the boundary lubrication regime, thus leading to the design guidance to reduce the femoral head diameter as much as is feasible to minimize frictional torque and volumetric wear. This explains why the gold-standard implant of this form from the past half-century had a diameter of only 22.225 mm (7/8 in). Metal-on-metal implants can operate in the mild mixed lubrication regime in which much of the applied load is supported by elastohydrodynamic films. Correct tribological design leads to remarkably low steady state wear rates. Promotion of the most effective elastohydrodynamic films calls for the largest possible head diameters and the smallest clearances that can reasonably be adopted, consistent with fine surface finishes, good sphericity and minimal structural elastic deformation of the cup on its foundations. This guidance, which is opposite in form to that developed for metal-on-polymer joints, is equally valid for solid (monolithic) metallic heads on metallic femoral stems and surface replacement femoral shells. Laboratory measurements of friction and wear in metal-on-metal joints have confirmed their potential to achieve a very mild form of mixed lubrication. The key lies in the generation of effective elastohydrodynamic lubricating films of adequate thickness compared with the composite roughness of the head and cup. The calculation of the film thickness is by no means easy, but the full procedure is outlined and the use of an empirical formula that displays good agreement with calculations based upon the full numerical solutions is explained. The representation of the lambda ratio, lambda, embracing both film thickness and composite roughness, is described.

  6. "Gloster" metal construction

    NASA Technical Reports Server (NTRS)

    1930-01-01

    This report details the methods of construction employed by the Gloster Company in their fabrication of metal aircraft parts. Ribs, spars, wings, and metal treatments to prevent oxidation are all discussed.

  7. Economic Geology (Metals)

    ERIC Educational Resources Information Center

    Gair, Jacob E.

    1972-01-01

    Reviews metalliferous ore-deposit research reported in 1971. Research was dominated by isotopic studies, and worldwide metals exploration was marked by announcements of important new discoveries of base metals, iron ore, nickel, titanium, and uranium. (Author/PR)

  8. Metal phthalocyanine catalysts

    DOEpatents

    Ellis, P.E. Jr.; Lyons, J.E.

    1994-10-11

    A new composition of matter is described which is an alkali metal or ammonium or tetraalkylammonium diazidoperfluorophthalocyanatoferrate. Other embodiments of the invention comprise compositions wherein the metal of the coordination complex is cobalt, manganese and chromium.

  9. Metal phthalocyanine catalysts

    DOEpatents

    Ellis, Jr., Paul E.; Lyons, James E.

    1994-01-01

    As a new composition of matter, alkali metal or ammonium or tetraalkylammonium diazidoperfluorophthalocyanatoferrate. Other embodiments of the invention comprise compositions wherein the metal of the coordination complex is cobalt, manganese and chromium.

  10. Metal to semiconductor transition in metallic transition metal dichalcogenides

    NASA Astrophysics Data System (ADS)

    Li, Yan; Tongay, Sefaattin; Yue, Qu; Kang, Jun; Wu, Junqiao; Li, Jingbo

    2013-11-01

    We report on tuning the electronic and magnetic properties of metallic transition metal dichalcogenides (mTMDCs) by 2D to 1D size confinement. The stability of the mTMDC monolayers and nanoribbons is demonstrated by the larger binding energy compared to the experimentally available semiconducting TMDCs. The 2D MX2 (M = Nb, Ta; X = S, Se) monolayers are non-ferromagnetic metals and mechanically softer compared to their semiconducting TMDCs counterparts. Interestingly, mTMDCs undergo metal-to-semiconductor transition when the ribbon width approaches to ˜13 Å and ˜7 Å for zigzag and armchair edge terminations, respectively; then these ribbons convert back to metal when the ribbon widths further decrease. Zigzag terminated nanoribbons are ferromagnetic semiconductors, and their magnetic properties can also be tuned by hydrogen edge passivation, whereas the armchair nanoribbons are non-ferromagnetic semiconductors. Our results display that the mTMDCs offer a broad range of physical properties spanning from metallic to semiconducting and non-ferromagnetic to ferromagnetic that is ideal for applications where stable narrow bandgap semiconductors with different magnetic properties are desired.

  11. Nanochemistry of metals

    NASA Astrophysics Data System (ADS)

    Sergeev, Gleb B.

    2001-10-01

    The results of studies on the nanochemistry of metals published in recent years are generalised. Primary attention is centred on the methods for the synthesis of nanoparticles and their chemical reactions. The means of stabilisation of nanoparticles which involve individual metals and incorporate atoms of several metals are considered as well as their physicochemical properties. Self-assembling processes of nanoparticles are described. The prospects of using metal nanoparticles in semiconductor devices, catalysis, biology and medicine are discussed. The bibliography includes 165 references.

  12. PRODUCTION OF METALS

    DOEpatents

    Spedding, F.H.; Wilhelm, H.A.; Keller, W.H.

    1961-09-19

    A process is described producing metallic thorium, titanium, zirconium, or hafnium from the fluoride. In the process, the fluoride is reduced with alkali or alkaline earth metal and a booster compound (e.g. iodine or a decomposable oxysalt) in a sealed bomb at superatmospheric pressure and a temperature above the melting point of the metal to be produced.

  13. Durable metallized polymer mirror

    DOEpatents

    Schissel, Paul O.; Kennedy, Cheryl E.; Jorgensen, Gary J.; Shinton, Yvonne D.; Goggin, Rita M.

    1994-01-01

    A metallized polymer mirror construction having improved durability against delamination and tunneling, comprising: an outer layer of polymeric material; a metal oxide layer underlying the outer layer of polymeric material; a silver reflective layer underneath the metal oxide layer; and a layer of adhesive attaching the silver layer to a substrate.

  14. Durable metallized polymer mirror

    DOEpatents

    Schissel, P.O.; Kennedy, C.E.; Jorgensen, G.J.; Shinton, Y.D.; Goggin, R.M.

    1994-11-01

    A metallized polymer mirror construction is disclosed having improved durability against delamination and tunneling, comprising: an outer layer of polymeric material; a metal oxide layer underlying the outer layer of polymeric material; a silver reflective layer underneath the metal oxide layer; and a layer of adhesive attaching the silver layer to a substrate. 6 figs.

  15. Metal etching composition

    NASA Technical Reports Server (NTRS)

    Otousa, Joseph E. (Inventor); Thomas, Clark S. (Inventor); Foster, Robert E. (Inventor)

    1991-01-01

    The present invention is directed to a chemical etching composition for etching metals or metallic alloys. The composition includes a solution of hydrochloric acid, phosphoric acid, ethylene glycol, and an oxidizing agent. The etching composition is particularly useful for etching metal surfaces in preparation for subsequent fluorescent penetrant inspection.

  16. Liquid metal cold trap

    DOEpatents

    Hundal, Rolv

    1976-01-01

    A cold trap assembly for removing impurities from a liquid metal being provided with a hole between the incoming impure liquid metal and purified outgoing liquid metal which acts as a continuous bleed means and thus prevents the accumulation of cover gases within the cold trap assembly.

  17. Silica Embedded Metal Hydrides

    SciTech Connect

    Heung, L.K.; Wicks, G.G.

    1998-08-01

    A method to produce silica embedded metal hydride was developed. The product is a composite in which metal hydride particles are embedded in a matrix of silica. The silica matrix is highly porous. Hydrogen gas can easily reach the embedded metal hydride particles. The pores are small so that the metal hydride particles cannot leave the matrix. The porous matrix also protects the metal hydride particles from larger and reactive molecules such as oxygen, since the larger gas molecules cannot pass through the small pores easily. Tests show that granules of this composite can absorb hydrogen readily and withstand many cycles without making fines.

  18. Electrolytic purification of metals

    DOEpatents

    Bowman, Kenneth A.

    1980-01-01

    A method of electrolytically separating metal from impurities comprises providing the metal and impurities in a molten state in a container having a porous membrane therein, the membrane having a thickness in the range of about 0.01 to 0.1 inch, being capable of containing the molten metal in the container, and being permeable by a molten electrolyte. The metal is electrolytically transferred through the membrane to a cathode in the presence of the electrolyte for purposes of separating or removing impurities from the metal.

  19. Metals and Breast Cancer

    PubMed Central

    Byrne, Celia; Divekar, Shailaja D.; Storchan, Geoffrey B.; Parodi, Daniela A.; Martin, Mary Beth

    2014-01-01

    Metalloestrogens are metals that activate the estrogen receptor in the absence of estradiol. The metalloestrogens fall into two subclasses: metal/metalloid anions and bivalent cationic metals. The metal/metalloid anions include compounds such as arsenite, nitrite, selenite, and vanadate while the bivalent cations include metals such as cadmium, calcium, cobalt, copper, nickel, chromium, lead, mercury, and tin. The best studied metalloestrogen is cadmium. It is a heavy metal and a prevalent environmental contaminant with no known physiological function. This review addresses our current understanding of the mechanism by which cadmium and the bivalent cationic metals activate estrogen receptor-α. The review also summarizes the in vitro and in vivo evidence that cadmium functions as an estrogen and the potential role of cadmium in breast cancer. PMID:23338949

  20. The Elusive Bose Metal

    NASA Astrophysics Data System (ADS)

    Phillips, Philip; Dalidovich, Denis

    2003-10-01

    The conventional theory of metals is in crisis. In the past 15 years, there has been an unexpected sprouting of metallic states in low-dimensional systems, directly contradicting conventional wisdom. For example, bosons are thought to exist in one of two ground states: condensed in a superconductor or localized in an insulator. However, several experiments on thin metal-alloy films have observed that a metallic phase disrupts the direct transition between the superconductor and the insulator. We analyze the experiments on the insulator-superconductor transition and argue that the intervening metallic phase is bosonic. All relevant theoretical proposals for the Bose metal are discussed, particularly the recent idea that the metallic phase is glassy. The implications for the putative vortex-glass state in the copper oxide superconductors are examined.

  1. Molecularly doped metals.

    PubMed

    Avnir, David

    2014-02-18

    The many millions of organic, inorganic, and bioorganic molecules represent a very rich library of chemical, biological, and physical properties that do not show up among the approximately 100 metals. The ability to imbue metals with any of these molecular properties would open up tremendous potential for the development of new materials. In addition to their traditional features and their traditional applications, metals would have new traits, which would merge their classical virtues such as conductivity and catalytic activity with the diverse properties of these molecules. In this Account, we describe a new materials methodology, which enables, for the first time, the incorporation and entrapment of small organic molecules, polymers, and biomolecules within metals. These new materials are denoted dopant@metal. The creation of dopant@metal yields new properties that are more than or different from the sum of the individual properties of the two components. So far we have developed methods for the doping of silver, copper, gold, iron, palladium, platinum, and some of their alloys, as well as Hg-Ag amalgams. We have successfully altered classical metal properties (such as conductivity), induced unorthodox properties (such as rendering a metal acidic or basic), used metals as heterogeneous matrices for homogeneous catalysts, and formed new metallic catalysts such as metals doped with organometallic complexes. In addition, we have created materials that straddle the border between polymers and metals, we have entrapped enzymes to form bioactive metals, we have induced chirality within metals, we have made corrosion-resistant iron, we formed efficient biocidal materials, and we demonstrated a new concept for batteries. We have developed a variety of methods for synthesizing dopant@metals including aqueous homogeneous and heterogeneous reductions of the metal cations, reductions in DMF, electrochemical entrapments, thermal decompositions of zerovalent metal carbonyls

  2. Molecularly doped metals.

    PubMed

    Avnir, David

    2014-02-18

    The many millions of organic, inorganic, and bioorganic molecules represent a very rich library of chemical, biological, and physical properties that do not show up among the approximately 100 metals. The ability to imbue metals with any of these molecular properties would open up tremendous potential for the development of new materials. In addition to their traditional features and their traditional applications, metals would have new traits, which would merge their classical virtues such as conductivity and catalytic activity with the diverse properties of these molecules. In this Account, we describe a new materials methodology, which enables, for the first time, the incorporation and entrapment of small organic molecules, polymers, and biomolecules within metals. These new materials are denoted dopant@metal. The creation of dopant@metal yields new properties that are more than or different from the sum of the individual properties of the two components. So far we have developed methods for the doping of silver, copper, gold, iron, palladium, platinum, and some of their alloys, as well as Hg-Ag amalgams. We have successfully altered classical metal properties (such as conductivity), induced unorthodox properties (such as rendering a metal acidic or basic), used metals as heterogeneous matrices for homogeneous catalysts, and formed new metallic catalysts such as metals doped with organometallic complexes. In addition, we have created materials that straddle the border between polymers and metals, we have entrapped enzymes to form bioactive metals, we have induced chirality within metals, we have made corrosion-resistant iron, we formed efficient biocidal materials, and we demonstrated a new concept for batteries. We have developed a variety of methods for synthesizing dopant@metals including aqueous homogeneous and heterogeneous reductions of the metal cations, reductions in DMF, electrochemical entrapments, thermal decompositions of zerovalent metal carbonyls

  3. Extraction process for removing metallic impurities from alkalide metals

    SciTech Connect

    Royer, Lamar T.

    1988-01-01

    A development is described for removing metallic impurities from alkali metals by employing an extraction process wherein the metallic impurities are extracted from a molten alkali metal into molten lithium metal due to the immiscibility of the alkali metals in lithium and the miscibility of the metallic contaminants or impurities in the lithium. The purified alkali metal may be readily separated from the contaminant-containing lithium metal by simple decanting due to the differences in densities and melting temperatures of the alkali metals as compared to lithium.

  4. Extraction process for removing metallic impurities from alkalide metals

    SciTech Connect

    Royer, L.T.

    1987-03-20

    A development is described for removing metallic impurities from alkali metals by employing an extraction process wherein the metallic impurities are extracted from a molten alkali metal into molten lithium metal due to the immiscibility of the alkali metals in lithium and the miscibility of the metallic contaminants or impurities in the lithium. The purified alkali metal may be readily separated from the contaminant-containing lithium metal by simple decanting due to the differences in densities and melting temperatures of the alkali metals as compared to lithium.

  5. FORMING PROTECTIVE FILMS ON METAL

    DOEpatents

    Gurinsky, D.H.; Kammerer, O.F.; Sadofsky, J.; Weeks, J.R.

    1958-12-16

    Methods are described of inhibiting the corrosion of ferrous metal by contact with heavy liquid metals such as bismuth and gallium at temperatures above 500 icient laborato C generally by bringing nltrogen and either the metal zirconium, hafnium, or titanium into reactlve contact with the ferrous metal to form a thin adherent layer of the nitride of the metal and thereafter maintaining a fractional percentage of the metal absorbed in the heavy liquid metal in contact with the ferrous metal container. The general purpose for uslng such high boiling liquid metals in ferrous contalners would be as heat transfer agents in liquid-metal-fueled nuclear reactors.

  6. Immunology of metal allergies.

    PubMed

    Schmidt, Marc; Goebeler, Matthias

    2015-07-01

    Allergic contact hypersensitivity to metal allergens is a common health concern worldwide, greatly impacting affected individuals with regard to both quality of life and their ability to work. With an estimated 15-20 % of the Western population hypersensitive to at least one metal allergen, sensitization rates for metallic haptens by far outnumber those reported for other common triggers of allergic contact dermatitis such as fragrances and rubber. Unfortunately, the prevalence of metal-induced hypersensitivity remains high despite extensive legislative efforts to ban/reduce the content of allergy-causing metals in recreational and occupational products. Recently, much progress has been made regarding the perception mechanisms underlying the inflammatory responses to this unique group of contact allergens. This review summarizes recent advances in our understanding of this enigmatic disease. Particular emphasis is put on the mechanisms of innate immune activation and T cell activation by common metal allergens such as nickel, cobalt, palladium, and chromate.

  7. Light metal production

    DOEpatents

    Fan, Qinbai

    2016-04-19

    An electrochemical process for the production of light metals, particularly aluminum. Such a process involves contacting a light metal source material with an inorganic acid to form a solution containing the light metal ions in high concentration. The solution is fed to an electrochemical reactor assembly having an anode side containing an anode and a cathode side containing a cathode, with anode side and the cathode side separated by a bipolar membrane, with the solution being fed to the anode side. Light metal ions are electrochemically transferred through the bipolar membrane to the cathode side. The process further involves reducing the light metal ions to light metal powder. An associated processing system is also provided.

  8. Closed cell metal foam method

    DOEpatents

    Patten, James W.

    1978-01-01

    Foamed metals and metal alloys which have a closed cellular structure are prepared by heating a metal body containing entrapped inert gas uniformly distributed throughout to a temperature above the melting point of the metal and maintaining the body at this temperature a period of time sufficient to permit the entrapped gas to expand, forming individual cells within the molten metal, thus expanding and foaming the molten metal. After cell formation has reached the desired amount, the foamed molten metal body is cooled to below the melting temperature of the metal. The void area or density of the foamed metal is controlled by predetermining the amount of inert gas entrapped in the metal body and by the period of time the metal body is maintained in the molten state. This method is useful for preparing foamed metals and metal alloys from any metal or other material of which a body containing entrapped inert gas can be prepared.

  9. Supported metal alloy catalysts

    DOEpatents

    Barrera, Joseph; Smith, David C.

    2000-01-01

    A process of preparing a Group IV, V, or VI metal carbonitride including reacting a Group IV, V, or VI metal amide complex with ammonia to obtain an intermediate product; and, heating the intermediate product to temperatures and for times sufficient to form a Group IV, V, or VI metal carbonitride is provided together with the product of the process and a process of reforming an n-alkane by use of the product.

  10. Metal atomization spray nozzle

    DOEpatents

    Huxford, T.J.

    1993-11-16

    A spray nozzle for a magnetohydrodynamic atomization apparatus has a feed passage for molten metal and a pair of spray electrodes mounted in the feed passage. The electrodes, diverging surfaces which define a nozzle throat and diverge at an acute angle from the throat. Current passes through molten metal when fed through the throat which creates the Lorentz force necessary to provide atomization of the molten metal. 6 figures.

  11. Metal atomization spray nozzle

    DOEpatents

    Huxford, Theodore J.

    1993-01-01

    A spray nozzle for a magnetohydrodynamic atomization apparatus has a feed passage for molten metal and a pair of spray electrodes mounted in the feed passage. The electrodes, diverging surfaces which define a nozzle throat and diverge at an acute angle from the throat. Current passes through molten metal when fed through the throat which creates the Lorentz force necessary to provide atomization of the molten metal.

  12. Metal atom oxidation laser

    DOEpatents

    Jensen, R.J.; Rice, W.W.; Beattie, W.H.

    1975-10-28

    A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides. (auth)

  13. Metal atom oxidation laser

    DOEpatents

    Jensen, R.J.; Rice, W.W.; Beattie, W.H.

    1975-10-28

    A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides.

  14. Mutagenicity of heavy metals

    SciTech Connect

    Wong, P.K.

    1988-04-01

    Certain heavy metals are required, as trace elements for normal cellular functions. However, heavy metals are toxic to cells once their levels exceed their low physiological values. The toxicity of heavy metals on microorganisms, and on animals has been well-documented. These interactions may induce the alteration of the primary as well as secondary structures of the DNA and result in mutation(s). The present communication reports the results in determining the mutagenicity and carcinogenicity of ten heavy metals commonly found in polluted areas by using the Salmonella/mammalian-microsome mutagenicity test.

  15. Method of producing homogeneous mixed metal oxides and metal-metal oxide mixtures

    DOEpatents

    Quinby, Thomas C.

    1978-01-01

    Metal powders, metal oxide powders, and mixtures thereof of controlled particle size are provided by reacting an aqueous solution containing dissolved metal values with excess urea. Upon heating, urea reacts with water from the solution leaving a molten urea solution containing the metal values. The molten urea solution is heated to above about 180.degree. C. whereupon metal values precipitate homogeneously as a powder. The powder is reduced to metal or calcined to form oxide particles. One or more metal oxides in a mixture can be selectively reduced to produce metal particles or a mixture of metal and metal oxide particles.

  16. Metal-on-Metal Hip Resurfacing Arthroplasty

    PubMed Central

    Sehatzadeh, S; Kaulback, K; Levin, L

    2012-01-01

    Background Metal-on-metal (MOM) hip resurfacing arthroplasty (HRA) is in clinical use as an appropriate alternative to total hip arthroplasty in young patients. In this technique, a metal cap is placed on the femoral head to cover the damaged surface of the bone and a metal cup is placed in the acetabulum. Objectives The primary objective of this analysis was to compare the revision rates of MOM HRA using different implants with the benchmark set by the National Institute of Clinical Excellence (NICE). The secondary objective of this analysis was to review the literature regarding adverse biological effects associated with implant material. Review Methods A literature search was performed on February 13, 2012, to identify studies published from January 1, 2009, to February 13, 2012. Results The revision rates for MOM HRA using 6 different implants were reviewed. The revision rates for MOM HRA with 3 implants met the NICE criteria, i.e., a revision rate of 10% or less at 10 years. Two implants had short-term follow-ups and MOM HRA with one of the implants failed to meet the NICE criteria. Adverse tissue reactions resulting in failure of the implants have been reported by several studies. With a better understanding of the factors that influence the wear rate of the implants, adverse tissue reactions and subsequent implant failure can be minimized. Many authors have suggested that patient selection and surgical technique affect the wear rate and the risk of tissue reactions. The biological effects of high metal ion levels in the blood and urine of patients with MOM HRA implants are not known. Studies have shown an increase in chromosomal aberrations in patients with MOM articulations, but the clinical implications and long-term consequences of this increase are still unknown. Epidemiological studies have shown that patients with MOM HRA implants did not have an overall increase in mortality or risk of cancer. There is insufficient clinical data to confirm the

  17. Metal pad instabilities in liquid metal batteries.

    PubMed

    Zikanov, Oleg

    2015-12-01

    A mechanical analogy is used to analyze the interaction between the magnetic field, electric current, and deformation of interfaces in liquid metal batteries. In the framework of a low-mode, nondissipative, linear stability model, it is found that, during charging or discharging, a sufficiently large battery is prone to instabilities of two types. One is similar to the metal pad instability known to exist in the aluminum reduction cells. Another type is new. It is related to the destabilizing effect of the Lorentz force formed by the azimuthal magnetic field induced by the base current, and the current perturbations caused by the local variations of the thickness of the electrolyte layer.

  18. Metal pad instabilities in liquid metal batteries

    NASA Astrophysics Data System (ADS)

    Zikanov, Oleg

    2015-12-01

    A mechanical analogy is used to analyze the interaction between the magnetic field, electric current, and deformation of interfaces in liquid metal batteries. In the framework of a low-mode, nondissipative, linear stability model, it is found that, during charging or discharging, a sufficiently large battery is prone to instabilities of two types. One is similar to the metal pad instability known to exist in the aluminum reduction cells. Another type is new. It is related to the destabilizing effect of the Lorentz force formed by the azimuthal magnetic field induced by the base current, and the current perturbations caused by the local variations of the thickness of the electrolyte layer.

  19. Silicon metal-semiconductor-metal photodetector

    DOEpatents

    Brueck, Steven R. J.; Myers, David R.; Sharma, Ashwani K.

    1995-01-01

    Silicon MSM photodiodes sensitive to radiation in the visible to near infrared spectral range are produced by altering the absorption characteristics of crystalline Si by ion implantation. The implantation produces a defected region below the surface of the silicon with the highest concentration of defects at its base which acts to reduce the contribution of charge carriers formed below the defected layer. The charge carriers generated by the radiation in the upper regions of the defected layer are very quickly collected between biased Schottky barrier electrodes which form a metal-semiconductor-metal structure for the photodiode.

  20. Silicon metal-semiconductor-metal photodetector

    DOEpatents

    Brueck, Steven R. J.; Myers, David R.; Sharma, Ashwani K.

    1997-01-01

    Silicon MSM photodiodes sensitive to radiation in the visible to near infrared spectral range are produced by altering the absorption characteristics of crystalline Si by ion implantation. The implantation produces a defected region below the surface of the silicon with the highest concentration of defects at its base which acts to reduce the contribution of charge carriers formed below the defected layer. The charge carriers generated by the radiation in the upper regions of the defected layer are very quickly collected between biased Schottky barrier electrodes which form a metal-semiconductor-metal structure for the photodiode.

  1. 21 CFR 888.3640 - Shoulder joint metal/metal or metal/polymer constrained cemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Shoulder joint metal/metal or metal/polymer... § 888.3640 Shoulder joint metal/metal or metal/polymer constrained cemented prosthesis. (a) Identification. A shoulder joint metal/metal or metal/polymer constrained cemented prosthesis is a...

  2. 21 CFR 888.3640 - Shoulder joint metal/metal or metal/polymer constrained cemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Shoulder joint metal/metal or metal/polymer... § 888.3640 Shoulder joint metal/metal or metal/polymer constrained cemented prosthesis. (a) Identification. A shoulder joint metal/metal or metal/polymer constrained cemented prosthesis is a...

  3. 21 CFR 888.3640 - Shoulder joint metal/metal or metal/polymer constrained cemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Shoulder joint metal/metal or metal/polymer... § 888.3640 Shoulder joint metal/metal or metal/polymer constrained cemented prosthesis. (a) Identification. A shoulder joint metal/metal or metal/polymer constrained cemented prosthesis is a...

  4. 21 CFR 888.3640 - Shoulder joint metal/metal or metal/polymer constrained cemented prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Shoulder joint metal/metal or metal/polymer... § 888.3640 Shoulder joint metal/metal or metal/polymer constrained cemented prosthesis. (a) Identification. A shoulder joint metal/metal or metal/polymer constrained cemented prosthesis is a...

  5. 21 CFR 888.3640 - Shoulder joint metal/metal or metal/polymer constrained cemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Shoulder joint metal/metal or metal/polymer... § 888.3640 Shoulder joint metal/metal or metal/polymer constrained cemented prosthesis. (a) Identification. A shoulder joint metal/metal or metal/polymer constrained cemented prosthesis is a...

  6. Biosorption of heavy metals

    SciTech Connect

    Volesky, B. |; Holan, Z.R.

    1995-05-01

    Only within the past decade has the potential of metal biosorption by biomass materials been well established. For economic reasons, of particular interest are abundant biomass types generated as a waste byproduct of large-scale industrial fermentations or certain metal-binding algae found in large quantities in the sea. These biomass types serve as a basis for newly developed metal biosorption processes foreseen particularly as a very competitive means for the detoxification of metal-bearing industrial effluents. The assessment of the metal-building capacity of some new biosorbents is discussed. Lead and cadmium, for instance, have been effectively removed from very dilute solutions by the dried biomass of some ubiquitous species of brown marine algae such as Ascophyllum and Sargassum, which accumulate more than 30% of biomass dry weight in the metal. Mycelia of the industrial steroid-transforming fungi Rhizopus and Absidia are excellent biosorbents for lead, cadmium, copper, zinc, and uranium and also bind other heavy metals up to 25% of the biomass dry weight. Biosorption isotherm curves, derived from equilibrium batch sorption experiments, are used in the evaluation of metal uptake by different biosorbents. Further studies are focusing on the assessment of biosorbent performance in dynamic continuous-flow sorption systems. In the course of this work, new methodologies are being developed that are aimed at mathematical modeling of biosorption systems and their effective optimization. 115 refs., 7 figs., 3 tabs.

  7. Superconductivity in bad metals

    SciTech Connect

    Emery, V.J.; Kivelson, S.A.

    1995-12-31

    It is argued that many synthetic metals, including high temperature superconductors are ``bad metals`` with such a poor conductivity that the usual mean-field theory of superconductivity breaks down because of anomalously large classical and quantum fluctuations of the phase of the superconducting order parameter. Some consequences for high temperature superconductors are described.

  8. Metal fume fever

    SciTech Connect

    Offermann, P.V.; Finley, C.J. )

    1992-07-01

    Metal fume fever is an ancient occupational disease still encountered among metal workers. The delay between exposure and onset of non-specific symptoms makes this an elusive diagnosis. We present the case of a patient who developed symptoms several hours after welding. The historical background, pathogenesis, clinical presentation, and self-limited course of this common, yet frequently unrecognized illness are discussed.

  9. Metallized polymeric foam material

    NASA Technical Reports Server (NTRS)

    Birnbaum, B. A.; Bilow, N.

    1974-01-01

    Open-celled polyurethane foams can be coated uniformly with thin film of metal by vapor deposition of aluminum or by sensitization of foam followed by electroless deposition of nickel or copper. Foam can be further processed to increase thickness of metal overcoat to impart rigidity or to provide inert surface with only modest increase in weight.

  10. Metal-dielectric interactions

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1979-01-01

    Metal direlectric surface interactions and dielectric films on metal substrates were investigated. Since interfacial interaction depends so heavily on the nature of the surfaces, analytical surface tools such as Auger emission spectroscopy, X-ray photoelectron spectroscopy and field ion microscopy were used to assist in surface and interfacial characterization. The results indicate that with metals contacting certain glasses in the clean state interfacial, bonding produces fractures in the glasses while when a film such as water is present, fractures occur in the metal near the interface. Friction forces were used to measure the interfacial bond strengths. Studies with metals contacting polymers using field ion microscopy revealed that strong bonding forces could develop being between a metal and polymer surface with polymer transferring to the metal surface in various ways depending upon the forces applied to the surface in contact. With the deposition of refractory carbides, silicides and borides onto metal and alloy substrates the presence of oxides at the interface or active gases in the deposition plasma were shown to alter interfacial properties and chemistry. Auger ion depth profile analysis indicated the chemical composition at the interface and this could be related to the mechanical, friction, and wear behavior of the coating.

  11. Liquid metal hydrogen barriers

    DOEpatents

    Grover, George M.; Frank, Thurman G.; Keddy, Edward S.

    1976-01-01

    Hydrogen barriers which comprise liquid metals in which the solubility of hydrogen is low and which have good thermal conductivities at operating temperatures of interest. Such barriers are useful in nuclear fuel elements containing a metal hydride moderator which has a substantial hydrogen dissociation pressure at reactor operating temperatures.

  12. Four Versatile Metal Reactions.

    ERIC Educational Resources Information Center

    Hearn, Barbara C.

    1988-01-01

    Presents several strategies to teach the reactivity of metal elements. Stresses the safety aspects of these demonstrations using an overhead projector and a plexiglass safety shield. Lists some of the essential learnings desired in these activities. Includes a chart of the activity series of metals. (CW)

  13. Metals fact sheet: Ruthenium

    SciTech Connect

    1996-06-01

    Ruthenium, named after Ruthenia, a province in Western Russia, was discovered in 1827 by Osann in placer ores from Russia`s Ural mountains. A minor platinum group metal (PGM), Ruthenium was the last of the PGMs to be isolated. In 1844, Klaus prepared the first 6 grams of pure ruthenium metal.

  14. Metals Fact Sheet: Yttrium

    SciTech Connect

    1992-09-01

    Yttrium is a metallic element usually included among the rare earth metals, which it resembles chemically and with which it usually occurs in minerals. Yttrium was named after the village of Ytterby in Sweden---the element was discovered in a quarry near the village. This article discusses sources of the element, the world market for the element, and various applications of the material.

  15. Metallic nanowire networks

    DOEpatents

    Song, Yujiang; Shelnutt, John A.

    2012-11-06

    A metallic nanowire network synthesized using chemical reduction of a metal ion source by a reducing agent in the presence of a soft template comprising a tubular inverse micellar network. The network of interconnected polycrystalline nanowires has a very high surface-area/volume ratio, which makes it highly suitable for use in catalytic applications.

  16. Metal Airplane Construction

    NASA Technical Reports Server (NTRS)

    1926-01-01

    It has long been thought that metal construction of airplanes would involve an increase in weight as compared with wood construction. Recent experience has shown that such is not the case. This report describes the materials used, treatment of, and characteristics of metal airplane construction.

  17. Virus templated metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Aljabali, Alaa A. A.; Barclay, J. Elaine; Lomonossoff, George P.; Evans, David J.

    2010-12-01

    Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. <=35 nm. CPMV-templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron.Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. <=35 nm. CPMV-templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron. Electronic supplementary information (ESI) available: Additional experimental detail, agarose gel electrophoresis results, energy dispersive X-ray spectra, ζ-potential measurements, dynamic light scattering data, nanoparticle tracking analysis and an atomic force microscopy image of Ni-CPMV. See DOI: 10.1039/c0nr00525h

  18. PRODUCTION OF PLUTONIUM METAL

    DOEpatents

    Lyon, W.L.; Moore, R.H.

    1961-01-17

    A process is given for producing plutonium metal by the reduction of plutonium chloride, dissolved in alkali metal chloride plus or minus aluminum chloride, with magnesium or a magnesium-aluminum alloy at between 700 and 800 deg C and separating the plutonium or plutonium-aluminum alloy formed from the salt.

  19. Porous metallic bodies

    DOEpatents

    Landingham, R.L.

    1984-03-13

    Porous metallic bodies having a substantially uniform pore size of less than about 200 microns and a density of less than about 25 percent theoretical, as well as the method for making them, are disclosed. Group IIA, IIIB, IVB, VB, and rare earth metal hydrides a

  20. The hard metal diseases

    SciTech Connect

    Cugell, D.W. )

    1992-06-01

    Hard metal is a mixture of tungsten carbide and cobalt, to which small amounts of other metals may be added. It is widely used for industrial purposes whenever extreme hardness and high temperature resistance are needed, such as for cutting tools, oil well drilling bits, and jet engine exhaust ports. Cobalt is the component of hard metal that can be a health hazard. Respiratory diseases occur in workers exposed to cobalt--either in the production of hard metal, from machining hard metal parts, or from other sources. Adverse pulmonary reactions include asthma, hypersensitivity pneumonitis, and interstitial fibrosis. A peculiar, almost unique form of lung fibrosis, giant cell interstitial pneumonia, is closely linked with cobalt exposure.66 references.

  1. Metallization of electronic insulators

    DOEpatents

    Gottesfeld, Shimshon; Uribe, Francisco A.

    1994-01-01

    An electroplated element is formed to include an insulating substrate, a conducting polymer polymerized in situ on the substrate, and a metal layer deposited on the conducting polymer. In one application a circuit board is formed by polymerizing pyrrole on an epoxy-fiberglass substrate in a single step process and then electrodepositing a metal over the resulting polypyrrole polymer. No chemical deposition of the metal is required prior to electroplating and the resulting layer of substrate-polymer-metal has excellent adhesion characteristics. The metal deposition is surprisingly smooth and uniform over the relatively high resistance film of polypyrrole. A continuous manufacturing process is obtained by filtering the solution between successive substrates to remove polymer formed in the solution, by maintaining the solution oxidizing potential within selected limits, and by adding a strong oxidant, such as KMnO.sub.4 at periodic intervals to maintain a low sheet resistivity in the resulting conducting polymer film.

  2. The hard metal diseases.

    PubMed

    Cugell, D W

    1992-06-01

    Hard metal is a mixture of tungsten carbide and cobalt, to which small amounts of other metals may be added. It is widely used for industrial purposes whenever extreme hardness and high temperature resistance are needed, such as for cutting tools, oil well drilling bits, and jet engine exhaust ports. Cobalt is the component of hard metal that can be a health hazard. Respiratory diseases occur in workers exposed to cobalt--either in the production of hard metal, from machining hard metal parts, or from other sources. Adverse pulmonary reactions include asthma, hypersensitivity pneumonitis, and interstitial fibrosis. A peculiar, almost unique form of lung fibrosis, giant cell interstitial pneumonia, is closely linked with cobalt exposure.

  3. Metals and Neurodegeneration.

    PubMed

    Chen, Pan; Miah, Mahfuzur Rahman; Aschner, Michael

    2016-01-01

    Metals play important roles in the human body, maintaining cell structure and regulating gene expression, neurotransmission, and antioxidant response, to name a few. However, excessive metal accumulation in the nervous system may be toxic, inducing oxidative stress, disrupting mitochondrial function, and impairing the activity of numerous enzymes. Damage caused by metal accumulation may result in permanent injuries, including severe neurological disorders. Epidemiological and clinical studies have shown a strong correlation between aberrant metal exposure and a number of neurological diseases, including Alzheimer's disease, amyotrophic lateral sclerosis, autism spectrum disorders, Guillain-Barré disease, Gulf War syndrome, Huntington's disease, multiple sclerosis, Parkinson's disease, and Wilson's disease. Here, we briefly survey the literature relating to the role of metals in neurodegeneration.

  4. Chelation in Metal Intoxication

    PubMed Central

    Flora, Swaran J.S.; Pachauri, Vidhu

    2010-01-01

    Chelation therapy is the preferred medical treatment for reducing the toxic effects of metals. Chelating agents are capable of binding to toxic metal ions to form complex structures which are easily excreted from the body removing them from intracellular or extracellular spaces. 2,3-Dimercaprol has long been the mainstay of chelation therapy for lead or arsenic poisoning, however its serious side effects have led researchers to develop less toxic analogues. Hydrophilic chelators like meso-2,3-dimercaptosuccinic acid effectively promote renal metal excretion, but their ability to access intracellular metals is weak. Newer strategies to address these drawbacks like combination therapy (use of structurally different chelating agents) or co-administration of antioxidants have been reported recently. In this review we provide an update of the existing chelating agents and the various strategies available for the treatment of heavy metals and metalloid intoxications. PMID:20717537

  5. Production of magnesium metal

    DOEpatents

    Blencoe, James G [Harriman, TN; Anovitz, Lawrence M [Knoxville, TN; Palmer, Donald A [Oliver Springs, TN; Beard, James S [Martinsville, VA

    2010-02-23

    A process of producing magnesium metal includes providing magnesium carbonate, and reacting the magnesium carbonate to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The carbon dioxide is used as a reactant in a second process. In another embodiment of the process, a magnesium silicate is reacted with a caustic material to produce magnesium hydroxide. The magnesium hydroxide is reacted with a source of carbon dioxide to produce magnesium carbonate. The magnesium carbonate is reacted to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The invention further relates to a process for production of magnesium metal or a magnesium compound where an external source of carbon dioxide is not used in any of the reactions of the process. The invention also relates to the magnesium metal produced by the processes described herein.

  6. Mutagenicity of heavy metals

    SciTech Connect

    Wong, P.K. )

    1988-05-01

    Certain heavy metals are required, as trace elements for normal cellular functions. However, heavy metals are toxic to cells once their levels exceed their low physiological values. The toxicity of heavy metals on microorganisms, on plants and on animals has been well-documented. These interactions may induce the alteration of the primary as well as secondary structures of the DNA and result in mutation(s). Though the rec assay with Bacillus subtilis and the reversion assay with Escherichia coli were used to assess the mutagenicity of some heavy metals, the present communication reports the results in determining the mutagenicity and carcinogenicity of ten heavy metals commonly found in polluted areas by using the Salmonella/mammalian-microsome mutagenicity test.

  7. Metals and Neurodegeneration

    PubMed Central

    Chen, Pan; Miah, Mahfuzur Rahman; Aschner, Michael

    2016-01-01

    Metals play important roles in the human body, maintaining cell structure and regulating gene expression, neurotransmission, and antioxidant response, to name a few. However, excessive metal accumulation in the nervous system may be toxic, inducing oxidative stress, disrupting mitochondrial function, and impairing the activity of numerous enzymes. Damage caused by metal accumulation may result in permanent injuries, including severe neurological disorders. Epidemiological and clinical studies have shown a strong correlation between aberrant metal exposure and a number of neurological diseases, including Alzheimer’s disease, amyotrophic lateral sclerosis, autism spectrum disorders, Guillain–Barré disease, Gulf War syndrome, Huntington’s disease, multiple sclerosis, Parkinson’s disease, and Wilson’s disease. Here, we briefly survey the literature relating to the role of metals in neurodegeneration. PMID:27006759

  8. The hard metal diseases.

    PubMed

    Cugell, D W

    1992-06-01

    Hard metal is a mixture of tungsten carbide and cobalt, to which small amounts of other metals may be added. It is widely used for industrial purposes whenever extreme hardness and high temperature resistance are needed, such as for cutting tools, oil well drilling bits, and jet engine exhaust ports. Cobalt is the component of hard metal that can be a health hazard. Respiratory diseases occur in workers exposed to cobalt--either in the production of hard metal, from machining hard metal parts, or from other sources. Adverse pulmonary reactions include asthma, hypersensitivity pneumonitis, and interstitial fibrosis. A peculiar, almost unique form of lung fibrosis, giant cell interstitial pneumonia, is closely linked with cobalt exposure. PMID:1511554

  9. Metals and Neurodegeneration.

    PubMed

    Chen, Pan; Miah, Mahfuzur Rahman; Aschner, Michael

    2016-01-01

    Metals play important roles in the human body, maintaining cell structure and regulating gene expression, neurotransmission, and antioxidant response, to name a few. However, excessive metal accumulation in the nervous system may be toxic, inducing oxidative stress, disrupting mitochondrial function, and impairing the activity of numerous enzymes. Damage caused by metal accumulation may result in permanent injuries, including severe neurological disorders. Epidemiological and clinical studies have shown a strong correlation between aberrant metal exposure and a number of neurological diseases, including Alzheimer's disease, amyotrophic lateral sclerosis, autism spectrum disorders, Guillain-Barré disease, Gulf War syndrome, Huntington's disease, multiple sclerosis, Parkinson's disease, and Wilson's disease. Here, we briefly survey the literature relating to the role of metals in neurodegeneration. PMID:27006759

  10. Tests on Double Layer Metalization

    NASA Technical Reports Server (NTRS)

    Woo, D. S.

    1983-01-01

    28 page report describes experiments in fabrication of integrated circuits with double-layer metalization. Double-layer metalization requires much less silicon "real estate" and allows more flexibility in placement of circuit elements than does single-layer metalization.

  11. Metal nanodisks using bicellar templates

    SciTech Connect

    Song, Yujiang; Shelnutt, John A

    2013-12-03

    Metallic nanodisks and a method of making them. The metallic nanodisks are wheel-shaped structures that that provide large surface areas for catalytic applications. The metallic nanodisks are grown within bicelles (disk-like micelles) that template the growth of the metal in the form of approximately circular dendritic sheets. The zero-valent metal forming the nanodisks is formed by reduction of a metal ion using a suitable electron donor species.

  12. Method for producing metallic nanoparticles

    DOEpatents

    Phillips, Jonathan; Perry, William L.; Kroenke, William J.

    2004-02-10

    Method for producing metallic nanoparticles. The method includes generating an aerosol of solid metallic microparticles, generating non-oxidizing plasma with a plasma hot zone at a temperature sufficiently high to vaporize the microparticles into metal vapor, and directing the aerosol into the hot zone of the plasma. The microparticles vaporize in the hot zone to metal vapor. The metal vapor is directed away from the hot zone and to the plasma afterglow where it cools and condenses to form solid metallic nanoparticles.

  13. Method for producing metallic microparticles

    DOEpatents

    Phillips, Jonathan; Perry, William L.; Kroenke, William J.

    2004-06-29

    Method for producing metallic particles. The method converts metallic nanoparticles into larger, spherical metallic particles. An aerosol of solid metallic nanoparticles and a non-oxidizing plasma having a portion sufficiently hot to melt the nanoparticles are generated. The aerosol is directed into the plasma where the metallic nanoparticles melt, collide, join, and spheroidize. The molten spherical metallic particles are directed away from the plasma and enter the afterglow where they cool and solidify.

  14. Semi-metallic polymers.

    PubMed

    Bubnova, Olga; Khan, Zia Ullah; Wang, Hui; Braun, Slawomir; Evans, Drew R; Fabretto, Manrico; Hojati-Talemi, Pejman; Dagnelund, Daniel; Arlin, Jean-Baptiste; Geerts, Yves H; Desbief, Simon; Breiby, Dag W; Andreasen, Jens W; Lazzaroni, Roberto; Chen, Weimin M; Zozoulenko, Igor; Fahlman, Mats; Murphy, Peter J; Berggren, Magnus; Crispin, Xavier

    2014-02-01

    Polymers are lightweight, flexible, solution-processable materials that are promising for low-cost printed electronics as well as for mass-produced and large-area applications. Previous studies demonstrated that they can possess insulating, semiconducting or metallic properties; here we report that polymers can also be semi-metallic. Semi-metals, exemplified by bismuth, graphite and telluride alloys, have no energy bandgap and a very low density of states at the Fermi level. Furthermore, they typically have a higher Seebeck coefficient and lower thermal conductivities compared with metals, thus being suitable for thermoelectric applications. We measure the thermoelectric properties of various poly(3,4-ethylenedioxythiophene) samples, and observe a marked increase in the Seebeck coefficient when the electrical conductivity is enhanced through molecular organization. This initiates the transition from a Fermi glass to a semi-metal. The high Seebeck value, the metallic conductivity at room temperature and the absence of unpaired electron spins makes polymer semi-metals attractive for thermoelectrics and spintronics.

  15. Plants absorb heavy metals

    SciTech Connect

    Parry, J.

    1995-02-01

    Decontamination of heavy metals-polluted soils remains one of the most intractable problems of cleanup technology. Currently available techniques include extraction of the metals by physical and chemical means, such as acid leaching and electroosmosis, or immobilization by vitrification. There are presently no techniques for cleanup which are low cost and retain soil fertility after metals removal. But a solution to the problem could be on the horizon. A small but growing number of plants native to metalliferous soils are known to be capable of accumulating extremely high concentrations of metals in their aboveground portions. These hyperaccumulators, as they are called, contain up to 1,000 times larger metal concentrations in their aboveground parts than normal species. Their distribution is global, including many different families of flowering plants of varying growth forms, from herbaceous plants to trees. Hyperaccumulators absorb metals they do not need for their own nutrition. The metals are accumulated in the leaf and stem vacuoles, and to a lesser extent in the roots.

  16. Hydrogen interactions with metals

    NASA Technical Reports Server (NTRS)

    Mclellan, R. B.; Harkins, C. G.

    1975-01-01

    Review of the literature on the nature and extent of hydrogen interactions with metals and the role of hydrogen in metal failure. The classification of hydrogen-containing systems is discussed, including such categories as covalent hydrides, volatile hydrides, polymeric hydrides, and transition metal hydride complexes. The use of electronegativity as a correlating parameter in determining hydride type is evaluated. A detailed study is made of the thermodynamics of metal-hydrogen systems, touching upon such aspects as hydrogen solubility, the positions occupied by hydrogen atoms within the solvent metal lattice, the derivation of thermodynamic functions of solid solutions from solubility data, and the construction of statistical models for hydrogen-metal solutions. A number of theories of hydrogen-metal bonding are reviewed, including the rigid-band model, the screened-proton model, and an approach employing the augmented plane wave method to solve the one-electron energy band problem. Finally, the mechanism of hydrogen embrittlement is investigated on the basis of literature data concerning stress effects and the kinetics of hydrogen transport to critical sites.

  17. Dyeing fabrics with metals

    NASA Astrophysics Data System (ADS)

    Kalivas, Georgia

    2002-06-01

    Traditionally, in textile dyeing, metals have been used as mordants or to improve the color produced by a natural or synthetic dye. In biomedical research and clinical diagnostics gold colloids are used as sensitive signals to detect the presence of pathogens. It has been observed that when metals are finely divided, a distinct color may result that is different from the color of the metal in bulk. For example, when gold is finely divided it may appear black, ruby or purple. This can be seen in biomedical research when gold colloids are reduced to micro-particles. Bright color signals are produced by few nanometer-sized particles. Dr. William Todd, a researcher in the Department of Veterinary Science at the Louisiana State University, developed a method of dyeing fabrics with metals. By using a reagent to bond the metal particles deep into the textile fibers and actually making the metal a part of the chemistry of the fiber. The chemicals of the fabric influence the resulting color. The combination of the element itself, the size of the particle, the chemical nature of the particle and the interaction of the metal with the chemistry of the fabric determine the actual hue. By using different elements, reagents, textiles and solvents a broad range of reproducible colors and tones can be created. Metals can also be combined into alloys, which will produce a variety of colors. The students of the ISCC chapter at the Fashion Institute of Technology dyed fabric using Dr. Todd's method and created a presentation of the results. They also did a demonstration of dyeing fabrics with metals.

  18. Liquid metal drop ejection

    NASA Technical Reports Server (NTRS)

    Khuri-Yakub, B. T.

    1993-01-01

    The aim of this project was to demonstrate the possibility of ejecting liquid metals using drop on demand printing technology. The plan was to make transducers for operation in the 100 MHz frequency range and to use these transducers to demonstrate the ability to eject drops of liquid metals such as gallium. Two transducers were made by indium bonding piezoelectric lithium niobate to quartz buffer rods. The lithium niobate plates were thinned by mechanical polishing to a thickness of 37 microns for operation at 100 MHz. Hemispherical lenses were polished in the opposite ends of the buffer rods. The lenses, which focus the sound waves in the liquid metal, had an F-number equals 1. A mechanical housing was made to hold the transducers and to allow precise control over the liquid level above the lens. We started by demonstrating the ability to eject drops of water on demand. The drops of water had a diameter of 15 microns which corresponds to the wavelength of the sound wave in the water. A videotape of this ejection was made. We then used a mixture of Gallium and Indium (used to lower the melting temperature of the Gallium) to demonstrate the ejection of liquid metal drops. This proved to be difficult because of the oxide skin which forms on the surface of the liquid. In some instances, we were able to eject metal drops, however, this was not consistent and reproducible. An experiment was set up at NASA-Lewis to stabilize the process of drop on demand liquid metal ejection. The object was to place the transducer and liquid metal in a vacuum station so that no oxide would form on the surface. We were successful in demonstrating that liquid metals could be ejected on demand and that this technology could be used for making sheet metal in space.

  19. Preparation of uniform nanoparticles of ultra-high purity metal oxides, mixed metal oxides, metals, and metal alloys

    DOEpatents

    Woodfield, Brian F.; Liu, Shengfeng; Boerio-Goates, Juliana; Liu, Qingyuan; Smith, Stacey Janel

    2012-07-03

    In preferred embodiments, metal nanoparticles, mixed-metal (alloy) nanoparticles, metal oxide nanoparticles and mixed-metal oxide nanoparticles are provided. According to embodiments, the nanoparticles may possess narrow size distributions and high purities. In certain preferred embodiments, methods of preparing metal nanoparticles, mixed-metal nanoparticles, metal oxide nanoparticles and mixed-metal nanoparticles are provided. These methods may provide tight control of particle size, size distribution, and oxidation state. Other preferred embodiments relate to a precursor material that may be used to form nanoparticles. In addition, products prepared from such nanoparticles are disclosed.

  20. Transition Metal Switchable Mirror

    SciTech Connect

    2009-08-21

    The switchable-mirrors technology was developed by Tom Richardson and Jonathan Slack of Berkeley Lab's Environmental Energy Technologies Division. By using transition metals rather than the rare earth metals used in the first metal-hydride switchable mirrors, Richardson and Slack were able to lower the cost and simplify the manufacturing process. Energy performance is improved as well, because the new windows can reflect or transmit both visible and infrared light. Besides windows for offices and homes, possible applications include automobile sunroofs, signs and displays, aircraft windows, and spacecraft.

  1. Metallized gelled monopropellants

    NASA Technical Reports Server (NTRS)

    Nieder, Erin G.; Harrod, Charles E.; Rodgers, Frederick C.; Rapp, Douglas C.; Palaszewski, Bryan A.

    1992-01-01

    Thermochemical calculations of seven metallized monopropellants were conducted to quantify theoretical specific impulse and density specific impulse performance. On the basis of theoretical performance, commercial availability of formulation constituents, and anticipated viscometric behavior, two metallized monopropellants were selected for formulation characterization: triethylene glycol dinitrate, ammonium perchlorate, aluminum and hydrogen peroxide, aluminum. Formulation goals were established, and monopropellant formulation compatibility and hazard sensitivity were experimentally determined. These experimental results indicate that the friction sensitivity, detonation susceptibility, and material handling difficulties of the elevated monopropellant formulations and their constituents pose formidable barriers to their future application as metallized monopropellants.

  2. Transition Metal Switchable Mirror

    ScienceCinema

    None

    2016-07-12

    The switchable-mirrors technology was developed by Tom Richardson and Jonathan Slack of Berkeley Lab's Environmental Energy Technologies Division. By using transition metals rather than the rare earth metals used in the first metal-hydride switchable mirrors, Richardson and Slack were able to lower the cost and simplify the manufacturing process. Energy performance is improved as well, because the new windows can reflect or transmit both visible and infrared light. Besides windows for offices and homes, possible applications include automobile sunroofs, signs and displays, aircraft windows, and spacecraft. More information at: http://windows.lbl.gov/materials/chromogenics/default.htm

  3. Transition Metal Switchable Mirror

    ScienceCinema

    None

    2016-07-12

    The switchable-mirrors technology was developed by Tom Richardson and Jonathan Slack of Berkeley Lab's Environmental Energy Technologies Division. By using transition metals rather than the rare earth metals used in the first metal-hydride switchable mirrors, Richardson and Slack were able to lower the cost and simplify the manufacturing process. Energy performance is improved as well, because the new windows can reflect or transmit both visible and infrared light. Besides windows for offices and homes, possible applications include automobile sunroofs, signs and displays, aircraft windows, and spacecraft.

  4. Liquid metal electric pump

    DOEpatents

    Abbin, Joseph P.; Andraka, Charles E.; Lukens, Laurance L.; Moreno, James B.

    1992-01-01

    An electrical pump for pumping liquid metals to high pressures in high temperature environments without the use of magnets or moving mechanical parts. The pump employs a non-porous solid electrolyte membrane, typically ceramic, specific to the liquid metal to be pumped. A DC voltage is applied across the thickness of the membrane causing ions to form and enter the membrane on the electrically positive surface, with the ions being neutralized on the opposite surface. This action provides pumping of the liquid metal from one side of the non-porous solid electrolyte membrane to the other.

  5. Laminates and reinforced metals

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1980-01-01

    A selective review is presented of the state of the art of metallic laminates and fiber reinforced metals called metallic matrix laminates (MMLs). Design and analysis procedures that are used for, and typical structural components that have been made from MMLs are emphasized. Selected MMLs, constituent materials, typical material properties and fabrication procedures are briefly described, including hybrids and superhybrids. Advantages, disadvantages, and special considerations required during design, analysis, and fabrication of MMLs are examined. Tabular and graphical data are included to illustrate key aspects of MMLs. Appropriate references are cited to provide a selective bibliography of a rapidly expanding and very promising research and development field.

  6. Prosthetic metal implants and airport metal detectors

    PubMed Central

    Dancey, A; Titley, OG

    2013-01-01

    Introduction Metal detectors have been present in airports and points of departure for some time. With the introduction of heightened security measures in response to fears of an increased threat of terrorism, they may become more prevalent in other public locations. The aim of this study was to ascertain which prosthetic devices activated metal detector devices used for security purposes. Methods A range of prosthetic devices used commonly in orthopaedic and plastic surgery procedures were passed through an arch metal detector at Birmingham Airport in the UK. Additionally, each item was passed under a wand detector. Items tested included expandable breast prostheses, plates used in wrist and hand surgery, screws, K-wires, Autosuture™ ligation clips and staples. Results No prostheses were detected by the arch detector. The expandable implants and wrist plates were the only devices detected by passing the wand directly over them. No device was detected by the wand when it was under cover of the axillary soft tissue. Screws, K-wires, Autosuture™ clips and staples were not detected under any of the study conditions. Conclusions Although unlikely to trigger a detector, it is possible that an expandable breast prosthesis or larger plate may do so. It is therefore best to warn patients of this so they can anticipate detection and further examination. PMID:23827294

  7. Fabrication of Metallic Hollow Nanoparticles

    NASA Technical Reports Server (NTRS)

    Kim, Jae-Woo (Inventor); Choi, Sr., Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2016-01-01

    Metal and semiconductor nanoshells, particularly transition metal nanoshells, are fabricated using dendrimer molecules. Metallic colloids, metallic ions or semiconductors are attached to amine groups on the dendrimer surface in stabilized solution for the surface seeding method and the surface seedless method, respectively. Subsequently, the process is repeated with additional metallic ions or semiconductor, a stabilizer, and NaBH.sub.4 to increase the wall thickness of the metallic or semiconductor lining on the dendrimer surface. Metallic or semiconductor ions are automatically reduced on the metallic or semiconductor nanoparticles causing the formation of hollow metallic or semiconductor nanoparticles. The void size of the formed hollow nanoparticles depends on the dendrimer generation. The thickness of the metallic or semiconductor thin film around the dendrimer depends on the repetition times and the size of initial metallic or semiconductor seeds.

  8. Metal cleaner poisoning

    MedlinePlus

    Metal cleaners contain organic compounds called hydrocarbons, including: 1,2-butylene oxide Boric acid Cocoyl sarcosine Dicarboxylic fatty acid Dimethoxymethane Dodecanedioic acid N-propyl bromide Sodium hydroxide T-butanol

  9. Metal stocks and sustainability

    PubMed Central

    Gordon, R. B.; Bertram, M.; Graedel, T. E.

    2006-01-01

    The relative proportions of metal residing in ore in the lithosphere, in use in products providing services, and in waste deposits measure our progress from exclusive use of virgin ore toward full dependence on sustained use of recycled metal. In the U.S. at present, the copper contents of these three repositories are roughly equivalent, but metal in service continues to increase. Providing today's developed-country level of services for copper worldwide (as well as for zinc and, perhaps, platinum) would appear to require conversion of essentially all of the ore in the lithosphere to stock-in-use plus near-complete recycling of the metals from that point forward. PMID:16432205

  10. Development of metallization process

    NASA Technical Reports Server (NTRS)

    Garcia, A., III

    1984-01-01

    Pastes are evaluated that contain additives to aid in the silicon to metallization contact. None are completely successful. Pastes are evaluated using a heated stage scanning electron microscope (SEM). This equipment shows promise for future evaluations.

  11. Production of magnesium metal

    DOEpatents

    Blencoe, James G.; Anovitz, Lawrence M.; Palmer, Donald A.; Beard, James S.

    2012-04-10

    A process of producing magnesium metal includes providing magnesium carbonate, and reacting the magnesium carbonate to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The carbon dioxide is used as a reactant in a second process. In another embodiment of the process, a magnesium silicate is reacted with a caustic material to produce magnesium hydroxide. The magnesium hydroxide is reacted with a source of carbon dioxide to produce magnesium carbonate. The magnesium carbonate is reacted to produce a magnesium-containing compound and carbon dioxide. The magnesium-containing compound is reacted to produce magnesium metal. The invention also relates to the magnesium metal produced by the processes described herein.

  12. Metal stocks and sustainability.

    PubMed

    Gordon, R B; Bertram, M; Graedel, T E

    2006-01-31

    The relative proportions of metal residing in ore in the lithosphere, in use in products providing services, and in waste deposits measure our progress from exclusive use of virgin ore toward full dependence on sustained use of recycled metal. In the U.S. at present, the copper contents of these three repositories are roughly equivalent, but metal in service continues to increase. Providing today's developed-country level of services for copper worldwide (as well as for zinc and, perhaps, platinum) would appear to require conversion of essentially all of the ore in the lithosphere to stock-in-use plus near-complete recycling of the metals from that point forward. PMID:16432205

  13. Triple Point Topological Metals

    NASA Astrophysics Data System (ADS)

    Zhu, Ziming; Winkler, Georg W.; Wu, QuanSheng; Li, Ju; Soluyanov, Alexey A.

    2016-07-01

    Topologically protected fermionic quasiparticles appear in metals, where band degeneracies occur at the Fermi level, dictated by the band structure topology. While in some metals these quasiparticles are direct analogues of elementary fermionic particles of the relativistic quantum field theory, other metals can have symmetries that give rise to quasiparticles, fundamentally different from those known in high-energy physics. Here, we report on a new type of topological quasiparticles—triple point fermions—realized in metals with symmorphic crystal structure, which host crossings of three bands in the vicinity of the Fermi level protected by point group symmetries. We find two topologically different types of triple point fermions, both distinct from any other topological quasiparticles reported to date. We provide examples of existing materials that host triple point fermions of both types and discuss a variety of physical phenomena associated with these quasiparticles, such as the occurrence of topological surface Fermi arcs, transport anomalies, and topological Lifshitz transitions.

  14. HAZARD ASSESSMENT OF METALS AND METAL COMPOUNDS IN TERRESTRIAL SYSTEMS

    EPA Science Inventory

    Metal accumulation in soil can result in adverse effects on soil biota, and may concentrate metals in food chains to levels detrimental to humans and wildlife. A SETAC Pellston Workshop entitled " Hazard Identification Approach For Metals And Inorganic Metal Substances" examined...

  15. Molten metal reactors

    DOEpatents

    Bingham, Dennis N; Klingler, Kerry M; Turner, Terry D; Wilding, Bruce M

    2013-11-05

    A molten metal reactor for converting a carbon material and steam into a gas comprising hydrogen, carbon monoxide, and carbon dioxide is disclosed. The reactor includes an interior crucible having a portion contained within an exterior crucible. The interior crucible includes an inlet and an outlet; the outlet leads to the exterior crucible and may comprise a diffuser. The exterior crucible may contain a molten alkaline metal compound. Contained between the exterior crucible and the interior crucible is at least one baffle.

  16. PRODUCTION OF HAFNIUM METAL

    DOEpatents

    Elger, G.W.; Boubel, R.W.

    1963-01-01

    This patent deals with a process of producing pure Hf metal from oxygen- contaminated gaseous Hf chloride. The oxygen compounds in the chioride gas are halogenated by contacting the gas at elevated temperature with Cl/sub 2/ in the presence of C. The Hf chloride, still in gaseous form, is contacted with molten Mg whereby Hf metal is formed and condensed on the Mg. (AEC)

  17. Metallic glass composition

    DOEpatents

    Kroeger, Donald M.; Koch, Carl C.

    1986-01-01

    A metallic glass alloy that is either iron-based or nickel-based or based on a mixture of iron and nickel, containing lesser amounts of elements selected from the group boron, silicon carbon and phosphorous to which is added an amount of a ductility enhancing element selected from the group cerium, lanthanum, praseodymium and neodymium sufficient to increase ductility of the metallic glass upon annealing.

  18. SINTERING METAL OXIDES

    DOEpatents

    Roake, W.E.

    1960-09-13

    A process is given for producing uranium dioxide material of great density by preparing a compacted mixture of uranium dioxide and from 1 to 3 wt.% of calcium hydride, heating the mixture to at least 675 deg C for decomposition of the hydride and then for sintering, preferably in a vacuum, at from 1550 to 2000 deg C. Calcium metal is formed, some uranium is reduced by the calcium to the metal and a product of high density is obtained.

  19. Chemistry of carcinogenic metals.

    PubMed Central

    Martell, A E

    1981-01-01

    The periodic distribution of known and suspected carcinogenic metal ions is described, and the chemical behavior of various types of metal ions is explained in terms of the general theory of hard and soft acids and bases. The chelate effect is elucidated, and the relatively high stability of metal chelates in very dilute solutions is discussed. The concepts employed for the chelate effect are extended to explain the high stabilities of macrocyclic and cryptate complexes. Procedures for the use of equilibrium data to determine the speciation of metal ions and complexes under varying solution conditions are described. Methods for assessing the interferences by hydrogen ion, competing metal ions, hydrolysis, and precipitation are explained, and are applied to systems containing iron(III) chelates of fourteen chelating agents designed for effective binding of the ferric ion. The donor groups available for the building up of multidentate ligands are presented, and the ways in which they may be combined to achieve high affinity and selectivity for certain types of metal ions are explained. PMID:6791915

  20. Metal-Polymer Nanocomposites

    NASA Astrophysics Data System (ADS)

    Nicolais, Luigi; Carotenuto, Gianfranco

    2004-09-01

    A unique guide to an essential area of nanoscience Interest in nano-sized metals has increased greatly due to their special characteristics and suitability for a number of advanced applications. As technology becomes more refined-including the ability to effectively manipulate and stabilize metals at the nanoscale-these materials present ever-more workable solutions to a growing range of problems. Metal-Polymer Nanocomposites provides the first guide solely devoted to the unique properties and applications of this essential area of nanoscience. It offers a truly multidisciplinary approach, making the text accessible to readers in physical, chemical, and materials science as well as areas such as engineering and topology. The thorough coverage includes: * The chemical and physical properties of nano-sized metals * Different approaches to the synthesis of metal-polymer nanocomposites (MPN) * Advanced characterization techniques and methods for study of MPN * Real-world applications, including color filters, polarizers, optical sensors, nonlinear optical devices, and more * An extensive list of references on the topics covered A unique, cutting-edge resource for a vital area of nanoscience development, Metal-Polymer Nanocomposites is an invaluable text for students and practitioners of materials science, engineering, polymer science, chemical engineering, electrical engineering, and optics.

  1. Porous metallic bodies

    DOEpatents

    Landingham, Richard L.

    1985-01-01

    Porous metallic bodies having a substantially uniform pore size of less than about 200 microns and a density of less than about 25 percent theoretical, as well as the method for making them, are disclosed. Group IIA, IIIB, IVB, VB, and rare earth metal hydrides are heated in a confining container at a controlled rate to a temperature of about greater than the temperature at which the hydride decomposes. Hydrogen is removed from the container and the remaining metal is heated during a second stage to a temperature greater than the temperature at which it was previously heated but not greater than the temperature of 1/2 to 2/3 the temperature at which the metal melts at a controlled rate. The resulting porous metallic body produced has a density less than about 25 percent theoretical and a pore size of less than about 200 microns. The metallic particles of the present invention have high inner surface area and possess minimum resistance to gas flow.

  2. Lithium metal reduction of plutonium oxide to produce plutonium metal

    DOEpatents

    Coops, Melvin S.

    1992-01-01

    A method is described for the chemical reduction of plutonium oxides to plutonium metal by the use of pure lithium metal. Lithium metal is used to reduce plutonium oxide to alpha plutonium metal (alpha-Pu). The lithium oxide by-product is reclaimed by sublimation and converted to the chloride salt, and after electrolysis, is removed as lithium metal. Zinc may be used as a solvent metal to improve thermodynamics of the reduction reaction at lower temperatures. Lithium metal reduction enables plutonium oxide reduction without the production of huge quantities of CaO--CaCl.sub.2 residues normally produced in conventional direct oxide reduction processes.

  3. Transition Metal Homeostasis.

    PubMed

    Nies, Dietrich H; Grass, Gregor

    2009-08-01

    This chapter focuses on transition metals. All transition metal cations are toxic-those that are essential for Escherichia coli and belong to the first transition period of the periodic system of the element and also the "toxic-only" metals with higher atomic numbers. Common themes are visible in the metabolism of these ions. First, there is transport. High-rate but low-affinity uptake systems provide a variety of cations and anions to the cells. Control of the respective systems seems to be mainly through regulation of transport activity (flux control), with control of gene expression playing only a minor role. If these systems do not provide sufficient amounts of a needed ion to the cell, genes for ATP-hydrolyzing high-affinity but low-rate uptake systems are induced, e.g., ABC transport systems or P-type ATPases. On the other hand, if the amount of an ion is in surplus, genes for efflux systems are induced. By combining different kinds of uptake and efflux systems with regulation at the levels of gene expression and transport activity, the concentration of a single ion in the cytoplasm and the composition of the cellular ion "bouquet" can be rapidly adjusted and carefully controlled. The toxicity threshold of an ion is defined by its ability to produce radicals (copper, iron, chromate), to bind to sulfide and thiol groups (copper, zinc, all cations of the second and third transition period), or to interfere with the metabolism of other ions. Iron poses an exceptional metabolic problem due its metabolic importance and the low solubility of Fe(III) compounds, combined with the ability to cause dangerous Fenton reactions. This dilemma for the cells led to the evolution of sophisticated multi-channel iron uptake and storage pathways to prevent the occurrence of unbound iron in the cytoplasm. Toxic metals like Cd2+ bind to thiols and sulfide, preventing assembly of iron complexes and releasing the metal from iron-sulfur clusters. In the unique case of mercury, the

  4. Porous metal for orthopedics implants

    PubMed Central

    Matassi, Fabrizio; Botti, Alessandra; Sirleo, Luigi; Carulli, Christian; Innocenti, Massimo

    2013-01-01

    Summary Porous metal has been introduced to obtain biological fixation and improve longevity of orthopedic implants. The new generation of porous metal has intriguing characteristics that allows bone healing and high osteointegration of the metallic implants. This article gives an overview about biomaterials properties of the contemporary class of highly porous metals and about the clinical use in orthopaedic surgery. PMID:24133527

  5. Electrochemical nitridation of metal surfaces

    DOEpatents

    Wang, Heli; Turner, John A.

    2015-06-30

    Electrochemical nitridation of metals and the produced metals are disclosed. An exemplary method of electrochemical nitridation of metals comprises providing an electrochemical solution at low temperature. The method also comprises providing a three-electrode potentiostat system. The method also comprises stabilizing the three-electrode potentiostat system at open circuit potential. The method also comprises applying a cathodic potential to a metal.

  6. PROCESS OF PRODUCING ACTINIDE METALS

    DOEpatents

    Magel, T.T.

    1959-07-14

    The preparation of actinide metals in workable, coherent form is described. In general, the objects of the invention are achieved by heating a mixture of an oxide and a halide of an actinide metal such as uranium with an alkali metal on alkaline earth metal reducing agent in the presence of iodine.

  7. Thermally tolerant multilayer metal membrane

    DOEpatents

    Dye, Robert C.; Snow, Ronny C.

    2001-01-01

    A composite metal membrane including a first metal layer of a Group IVB or Group VB metal sandwiched between two layers of a Group VIIIB metal selected from the group consisting of palladium, platinum, nickel, rhodium, iridium, cobalt, and alloys thereof, and a non-continuous layer of a metal chalcogenide upon one layer of the Group VIIIB metal is disclosed together with a process for the recovery of hydrogen from a gaseous mixture using such a composite membrane and a process for forming such a composite metal membrane.

  8. Metal Ions in Unusual Valency States.

    ERIC Educational Resources Information Center

    Sellers, Robin M.

    1981-01-01

    Discusses reactivity of metal ions with the primary products of water radiolysis, hyper-reduced metal ions, zero-valent metal ions, unstable divalent ions from the reduction of bivalent ions, hyper-oxidized metal ions, and metal complexes. (CS)

  9. Toxic metals and autophagy.

    PubMed

    Chatterjee, Sarmishtha; Sarkar, Shuvasree; Bhattacharya, Shelley

    2014-11-17

    The earth's resources are finite, and it can no longer be considered a source of inexhaustible bounty for the human population. However, this realization has not been able to contain the human desire for rapid industrialization. The collateral to overusing environmental resources is the high-level contamination of undesirable toxic metals, leading to bioaccumulation and cellular damage. Cytopathological features of biological systems represent a key variable in several diseases. A review of the literature revealed that autophagy (PCDII), a high-capacity process, may consist of selective elimination of vital organelles and/or proteins that intiate mechanisms of cytoprotection and homeostasis in different biological systems under normal physiological and stress conditions. However, the biological system does survive under various environmental stressors. Currently, there is no consensus that specifies a particular response as being a dependable biomarker of toxicology. Autophagy has been recorded as the initial response of a cell to a toxic metal in a concentration- and time-dependent manner. Various signaling pathways are triggered through cellular proteins and/or protein kinases that can lead to autophagy, apoptosis (or necroptosis), and necrosis. Although the role of autophagy in tumorigenesis is associated with promoting tumor cell survival and/or acting as a tumor suppressive mechanism, PCDII in metal-induced toxicity has not been extensively studied. The aim of this review is to analyze the comparative cytotoxicity of metals/metalloids and nanoparticles (As, Cd, Cr, Hg, Fe, and metal-NP) in cells enduring autophagy. It is noted that metals/metalloids and nanoparticles prefer ATG8/LC3 as a potent inducer of autophagy in several cell lines or animal cells. MAP kinases, death protein kinases, PI3K, AKT, mTOR, and AMP kinase have been found to be the major components of autophagy induction or inhibition in the context of cellular responses to metals/metalloids and

  10. Peroxotitanates for Biodelivery of Metals

    SciTech Connect

    Hobbs, David; Elvington, M.

    2009-02-11

    Metal-based drugs are largely undeveloped in pharmacology. One limiting factor is the systemic toxicity of metal-based compounds. A solid-phase, sequestratable delivery agent for local delivery of metals could reduce systemic toxicity, facilitating new drug development in this nascent area. Amorphous peroxotitanates (APT) are ion exchange materials with high affinity for several heavy metal ions, and have been proposed to deliver or sequester metal ions in biological contexts. In the current study, we tested a hypothesis that APT are able to deliver metals or metal compounds to cells. We exposed fibroblasts (L929) or monocytes (THP1) to metal-APT materials for 72 h in vitro, then measured cellular mitochondrial activity (SDH-MTT method) to assess the biological impact of the metal-APT materials vs. metals or APT alone. APT alone did not significantly affect cellular mitochondrial activity, but all metal-APT materials suppressed the mitochondrial activity of fibroblasts (by 30-65% of controls). The concentration of metal-APT materials required to suppress cellular mitochondrial activity was below that required for metals alone, suggesting that simple extracellular release of the metals from the metal-APT materials was not the primary mechanism of mitochondrial suppression. In contrast to fibroblasts, no metal-APT material had a measurable effect on THP1 monocyte mitochondrial activity, despite potent suppression by metals alone. This latter result suggested that 'biodelivery' by metal-APT materials may be cell type-specific. Therefore, it appears that APT are plausible solid phase delivery agents of metals or metal compounds to some types of cells for potential therapeutic effect.

  11. Method for forming metal contacts

    DOEpatents

    Reddington, Erik; Sutter, Thomas C; Bu, Lujia; Cannon, Alexandra; Habas, Susan E; Curtis, Calvin J; Miedaner, Alexander; Ginley, David S; Van Hest, Marinus Franciscus Antonius Maria

    2013-09-17

    Methods of forming metal contacts with metal inks in the manufacture of photovoltaic devices are disclosed. The metal inks are selectively deposited on semiconductor coatings by inkjet and aerosol apparatus. The composite is heated to selective temperatures where the metal inks burn through the coating to form an electrical contact with the semiconductor. Metal layers are then deposited on the electrical contacts by light induced or light assisted plating.

  12. Liquid metal thermal electric converter

    DOEpatents

    Abbin, Joseph P.; Andraka, Charles E.; Lukens, Laurance L.; Moreno, James B.

    1989-01-01

    A liquid metal thermal electric converter which converts heat energy to electrical energy. The design of the liquid metal thermal electric converter incorporates a unique configuration which directs the metal fluid pressure to the outside of the tube which results in the structural loads in the tube to be compressive. A liquid metal thermal electric converter refluxing boiler with series connection of tubes and a multiple cell liquid metal thermal electric converter are also provided.

  13. Metallicity and Quasar Outflows

    NASA Astrophysics Data System (ADS)

    Wang, Huiyuan; Zhou, Hongyan; Yuan, Weimin; Wang, Tinggui

    2012-06-01

    Correlations of the outflow strength of quasars, as measured by the blueshift and asymmetry index (BAI) of the C IV line, with intensities and ratios of broad emission lines, based on composite quasar spectra built from the Sloan Digital Sky Survey, are investigated. We find that most of the line ratios of other ions to C IV increase prominently with BAI. These behaviors can be well understood in the context of increasing metallicity with BAI. The strength of the dominant coolant, C IV line, decreases, and weak collisionally excited lines increase with gas metallicity as a result of the competition between different line coolants. Using Si IV+O IV]/C IV as an indicator of gas metallicity, we present, for the first time, a strong correlation between the metallicity and the outflow strength of quasars over a wide range of 1.7-6.9 times solar abundance. Our result implies that metallicity plays an important role in the formation of quasar outflows, likely by affecting outflow acceleration. This effect may have a profound impact on galaxy evolution via momentum feedback and chemical enrichment.

  14. Alkali metal ionization detector

    DOEpatents

    Bauerle, James E.; Reed, William H.; Berkey, Edgar

    1978-01-01

    Variations in the conventional filament and collector electrodes of an alkali metal ionization detector, including the substitution of helical electrode configurations for either the conventional wire filament or flat plate collector; or, the substitution of a plurality of discrete filament electrodes providing an in situ capability for transferring from an operationally defective filament electrode to a previously unused filament electrode without removing the alkali metal ionization detector from the monitored environment. In particular, the helical collector arrangement which is coaxially disposed about the filament electrode, i.e. the thermal ionizer, provides an improved collection of positive ions developed by the filament electrode. The helical filament design, on the other hand, provides the advantage of an increased surface area for ionization of alkali metal-bearing species in a monitored gas environment as well as providing a relatively strong electric field for collecting the ions at the collector electrode about which the helical filament electrode is coaxially positioned. Alternatively, both the filament and collector electrodes can be helical. Furthermore, the operation of the conventional alkali metal ionization detector as a leak detector can be simplified as to cost and complexity, by operating the detector at a reduced collector potential while maintaining the sensitivity of the alkali metal ionization detector adequate for the relatively low concentration of alkali vapor and aerosol typically encountered in leak detection applications.

  15. Dissimilar metals joint evaluation

    NASA Technical Reports Server (NTRS)

    Wakefield, M. E.; Apodaca, L. E.

    1974-01-01

    Dissimilar metals tubular joints between 2219-T851 aluminum alloy and 304L stainless steel were fabricated and tested to evaluate bonding processes. Joints were fabricated by four processes: (1) inertia (friction) weldings, where the metals are spun and forced together to create the weld; (2) explosive welding, where the metals are impacted together at high velocity; (3) co-extrusion, where the metals are extruded in contact at high temperature to promote diffusion; and (4) swaging, where residual stresses in the metals after a stretching operation maintain forced contact in mutual shear areas. Fifteen joints of each type were prepared and evaluated in a 6.35 cm (2.50 in.) O.D. size, with 0.32 cm (0.13 in.) wall thickness, and 7.6 cm (3.0 in) total length. The joints were tested to evaluate their ability to withstand pressure cycle, thermal cycle, galvanic corrosion and burst tests. Leakage tests and other non-destructive test techniques were used to evaluate the behavior of the joints, and the microstructure of the bond areas was analyzed.

  16. Ultralight metal foams

    NASA Astrophysics Data System (ADS)

    Jiang, Bin; He, Chunnian; Zhao, Naiqin; Nash, Philip; Shi, Chunsheng; Wang, Zejun

    2015-09-01

    Ultralight (<10 mg/cm3) cellular materials are desirable for thermal insulation; battery electrodes; catalyst supports; and acoustic, vibration, or shock energy damping. However, most of these ultralight materials, especially ultralight metal foams, are fabricated using either expensive materials or complicated procedures, which greatly limit their large-scale production and practical applications. Here we report a simple and versatile method to obtain ultralight monolithic metal foams. These materials are fabricated with a low-cost polymeric template and the method is based on the traditional silver mirror reaction and electroless plating. We have produced ultralight monolithic metal foams, such as silver, nickel, cobalt, and copper via this method. The resultant ultralight monolithic metal foams have remarkably low densities down to 7.4 mg/cm3 or 99.9% porosity. The metal foams have a long flat stress-train curve in compression tests and the densification strain ɛD of the Ni/Ag foam with a porosity of 99.8% can reach 82%. The plateau stress σpl was measured and found to be in agreement with the value predicted by the cellular solids theory.

  17. Ultralight metal foams

    PubMed Central

    Jiang, Bin; He, Chunnian; Zhao, Naiqin; Nash, Philip; Shi, Chunsheng; Wang, Zejun

    2015-01-01

    Ultralight (<10 mg/cm3) cellular materials are desirable for thermal insulation; battery electrodes; catalyst supports; and acoustic, vibration, or shock energy damping. However, most of these ultralight materials, especially ultralight metal foams, are fabricated using either expensive materials or complicated procedures, which greatly limit their large-scale production and practical applications. Here we report a simple and versatile method to obtain ultralight monolithic metal foams. These materials are fabricated with a low-cost polymeric template and the method is based on the traditional silver mirror reaction and electroless plating. We have produced ultralight monolithic metal foams, such as silver, nickel, cobalt, and copper via this method. The resultant ultralight monolithic metal foams have remarkably low densities down to 7.4 mg/cm3 or 99.9% porosity. The metal foams have a long flat stress-train curve in compression tests and the densification strain εD of the Ni/Ag foam with a porosity of 99.8% can reach 82%. The plateau stress σpl was measured and found to be in agreement with the value predicted by the cellular solids theory. PMID:26349002

  18. METALLICITY AND QUASAR OUTFLOWS

    SciTech Connect

    Wang, Huiyuan; Zhou, Hongyan; Wang, Tinggui; Yuan, Weimin

    2012-06-01

    Correlations of the outflow strength of quasars, as measured by the blueshift and asymmetry index (BAI) of the C IV line, with intensities and ratios of broad emission lines, based on composite quasar spectra built from the Sloan Digital Sky Survey, are investigated. We find that most of the line ratios of other ions to C IV increase prominently with BAI. These behaviors can be well understood in the context of increasing metallicity with BAI. The strength of the dominant coolant, C IV line, decreases, and weak collisionally excited lines increase with gas metallicity as a result of the competition between different line coolants. Using Si IV+O IV]/C IV as an indicator of gas metallicity, we present, for the first time, a strong correlation between the metallicity and the outflow strength of quasars over a wide range of 1.7-6.9 times solar abundance. Our result implies that metallicity plays an important role in the formation of quasar outflows, likely by affecting outflow acceleration. This effect may have a profound impact on galaxy evolution via momentum feedback and chemical enrichment.

  19. Size control of noble metal clusters and metallic heterostructures through the reduction kinetics of metal precursors

    NASA Astrophysics Data System (ADS)

    Sevonkaev, Igor V.; Herein, Daniel; Jeske, Gerald; Goia, Dan V.

    2014-07-01

    Eight precious metal salts/complexes were reduced in propylene glycol at temperatures ranging between 110 and 170 °C. We found that the reduction temperature and the size of precipitated metallic nanoparticles formed were significantly affected by the structure and reactivity of the metal precursors. The choice of noble metal precursor offers flexibility for designing, fabricating and controlling the size of metallic heterostructures with tunable properties.Eight precious metal salts/complexes were reduced in propylene glycol at temperatures ranging between 110 and 170 °C. We found that the reduction temperature and the size of precipitated metallic nanoparticles formed were significantly affected by the structure and reactivity of the metal precursors. The choice of noble metal precursor offers flexibility for designing, fabricating and controlling the size of metallic heterostructures with tunable properties. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03045a

  20. Get the metal out

    SciTech Connect

    Fries, W. . Research and Development Lab.); Chew, D.

    1993-02-01

    Wet processes for producing printed circuit boards lead to large volumes of wastewater containing low, but unacceptable, levels of copper ions. This water is usually treated with conventional precipitation technology, which produces hazardous metal hydroxide sludge and an effluent in the low ppm range. These treatment systems are becoming inadequate for printed wiring board (PWB) manufacturers because of the high operating costs, high cost of sludge disposal, and the worldwide trend toward reducing heavy metal discharge limits. Kinetico Engineered Systems, Inc., has developed a treatment for this waste based on ion exchange resin and electrowinning technologies. The program meets copper discharge limits below 1 ppm, recovers copper in a salable metallic form, and recylces 60 to 80 % of the copper-bearing wastes. The process has led to reduced operating costs while meeting regulatory compliance levels reliably.

  1. Metal Resistivity Measuring Device

    DOEpatents

    Renken, Jr, C. J.; Myers, R. G.

    1960-12-20

    An eddy current device is designed for detecting discontinuities in metal samples. Alternate short and long duration pulses are inductively applied to a metal sample via the outer coil of a probe. The lorg pulses give a resultant signal from the metal sample responsive to probe-tosample spacing and discontinuities with the sample, and the short pulses give a resultant signal responsive only to probe-to-sample spacing. The inner coil of the probe detects the two resultant signals and transmits them to a separation network where the two signals are separated. The two separated signals are then transmitted to a compensation network where the detected signals due to the short pulses are used to compensate for variations due to probeto-sample spacing contained in the detected signals from the long pulses. Thus a resultant signal is obtained responsive to discontinuities within the sample and independent of probe-to- sample spacing.

  2. METAL RESISTIVITY MEASURING DEVICE

    DOEpatents

    Renken, J. Jr.; Myers, R.G.

    1960-12-20

    An eddy current device is offered for detecting discontinuities in metal samples. Alternate short and long duration pulses are inductively applied to a metal sample via the outer coil of a probe. The long pulses give a resultant signal from the metal sample responsive to probe-tosample spacing and discontinuities within the sample and the shont pulses give a resultant signal responsive only to probe -to-sample spacing. The inner coil of the probe detects the two resultant signals and transmits them to a separation network where the two signals are separated. The two separated signals are then transmitted to a compensation network where the detected signals due to the short pulses are used to compensate for variations due to probe-to-sample spacing contained in the detected signals from the long pulses. Thus, a resultant signal is obtained responsive to discontinuities within the sample and independent of probe-to- sample spacing.

  3. Noble metal ionic catalysts.

    PubMed

    Hegde, M S; Madras, Giridhar; Patil, K C

    2009-06-16

    Because of growing environmental concerns and increasingly stringent regulations governing auto emissions, new more efficient exhaust catalysts are needed to reduce the amount of pollutants released from internal combustion engines. To accomplish this goal, the major pollutants in exhaust-CO, NO(x), and unburned hydrocarbons-need to be fully converted to CO(2), N(2), and H(2)O. Most exhaust catalysts contain nanocrystalline noble metals (Pt, Pd, Rh) dispersed on oxide supports such as Al(2)O(3) or SiO(2) promoted by CeO(2). However, in conventional catalysts, only the surface atoms of the noble metal particles serve as adsorption sites, and even in 4-6 nm metal particles, only 1/4 to 1/5 of the total noble metal atoms are utilized for catalytic conversion. The complete dispersion of noble metals can be achieved only as ions within an oxide support. In this Account, we describe a novel solution to this dispersion problem: a new solution combustion method for synthesizing dispersed noble metal ionic catalysts. We have synthesized nanocrystalline, single-phase Ce(1-x)M(x)O(2-delta) and Ce(1-x-y)Ti(y)M(x)O(2-delta) (M = Pt, Pd, Rh; x = 0.01-0.02, delta approximately x, y = 0.15-0.25) oxides in fluorite structure. In these oxide catalysts, Pt(2+), Pd(2+), or Rh(3+) ions are substituted only to the extent of 1-2% of Ce(4+) ion. Lower-valent noble metal ion substitution in CeO(2) creates oxygen vacancies. Reducing molecules (CO, H(2), NH(3)) are adsorbed onto electron-deficient noble metal ions, while oxidizing (O(2), NO) molecules are absorbed onto electron-rich oxide ion vacancy sites. The rates of CO and hydrocarbon oxidation and NO(x) reduction (with >80% N(2) selectivity) are 15-30 times higher in the presence of these ionic catalysts than when the same amount of noble metal loaded on an oxide support is used. Catalysts with palladium ion dispersed in CeO(2) or Ce(1-x)Ti(x)O(2) were far superior to Pt or Rh ionic catalysts. Therefore, we have demonstrated that the

  4. LEVELING METAL COATINGS

    DOEpatents

    Gage, H.A.

    1959-02-10

    A method is described for applying metallic coatings to a cylinder of uranium. An aluminum-silicon coat is applied by a process consisting of first cleaning the article by immersion for 5 minutes in 50% nitric acid at 65 C. The article then is dipped through a flux, prepared by adding 10% sodium fluoride to 90% of a flux comprising 53% potassium chloride, 42% lithium chloride, and 5% sodium chloride at 560 for 2 minutes and then directly into a molten metal bath comprising 99% aluminun and 12% silicon at 620 C for 3 minutes. While the coating is yet molten the article is transferred to a pair of steel rollers and rolled until the coating solidifies. By varying the composition of the flux other metals such as zinc, lead or the like may be coated on uranium in a similar manner.

  5. Solidification of undercooled metals

    NASA Technical Reports Server (NTRS)

    Flemings, M. C.; Shiohara, Y.

    1984-01-01

    The present investigation is concerned with the subject of undercooling (i.e., supercooling) in the case of metal alloys, taking into account the effects of undercooling on microstructure and microsegregation in alloys which solidify in a crystalline manner. Techniques for obtaining a large degree of undercooling are discussed. These techniques make it possible to eliminate heterogeneous nucleants from the melt and to remove container nucleation effects. The nucleation behavior of small metal droplets is considered along with the formation of a dispersion of fine droplets in a suitable inert medium, the mixing of fine metal powders with glass powder, and the levitation melting technique. Attention is given to solidification with rapid interface velocity, aspects of dendritic morphology, and thermal measurements during solidification of undercooled droplets.

  6. Metallization of fluid hydrogen

    SciTech Connect

    Nellis, W.J.; Louis, A.A.; Ashcroft, N.W.

    1997-05-14

    The electrical activity of liquid hydrogen has been measured at the high dynamic pressures, and temperatures that can be achieved with a reverberating shock wave. The resulting data are most naturally interpreted in terms of a continuous transition from a semiconducting to a metallic, largely diatomic fluid, the latter at 140 CPa, (ninefold compression) and 3000 K. While the fluid at these conditions resembles common liquid metals by the scale of its resistivity of 500 micro-ohm-cm, it differs by retaining a strong pairing character, and the precise mechanism by which a metallic state might be attained is still a matter of debate. Some evident possibilities include (i) physics of a largely one-body character, such as a band-overlap transition, (ii) physics of a strong-coupling or many-body character,such as a Mott-Hubbard transition, and (iii) process in which structural changes are paramount.

  7. Method for locating metallic nitride inclusions in metallic alloy ingots

    SciTech Connect

    White, Jack C.; Traut, Davis E.; Oden, Laurance L.; Schmitt, Roman A.

    1992-01-01

    A method of determining the location and history of metallic nitride and/or oxynitride inclusions in metallic melts. The method includes the steps of labeling metallic nitride and/or oxynitride inclusions by making a coreduced metallic-hafnium sponge from a mixture of hafnium chloride and the chloride of a metal, reducing the mixed chlorides with magnesium, nitriding the hafnium-labeled metallic-hafnium sponge, and seeding the sponge to be melted with hafnium-labeled nitride inclusions. The ingots are neutron activated and the hafnium is located by radiometric means. Hafnium possesses exactly the proper metallurgical and radiochemical properties for this use.

  8. Metal toxicosis in horses.

    PubMed

    Casteel, S W

    2001-12-01

    The ubiquity and stability of metals in the environment make them unique as a pollutant or an essential dietary component. Metals are neither created nor destroyed by chemical processes but are redistributed in the environment. In combination with other elements, metal compounds and alloys are essential materials of the contemporary world. Inappropriate use or distribution in the environment leads to adverse health effects on all biologic systems, including horses. Gastrointestinal upset is a common feature of acute toxicosis with metals in general. Among the metals discussed, arsenic and inorganic mercury have a propensity to do severe damage to the gut. Deposition of cadmium on forage is the source most likely to intoxicate horses. This subchronic to chronic problem in horses is manifest as disease of the musculoskeletal system and kidneys. Iron-containing hematinics are widely used in racetrack horses and occasionally result in hepatopathy when excessive doses are administered. Lead continues to be recognized as the most significant environmental metal pollutant. Poisoning is encountered routinely in humans and animals. Of the animal species of veterinary concern, lead-poisoned horses are not a frequent encounter. Lead-intoxicated horses show signs of peripheral neuropathy (laryngeal hemiplegia), intermittent colic, and mild anemia. Acute mercury poisoning sometimes occurs from the common use of mercury-containing blistering agents, with most clinical findings related to acute renal failure. Chronic excessive intake of zinc by horses is uncommon but devastating in rapidly growing foals. The mechanism of chronic zinc toxicosis is coupled to the induced copper deficiency. The condition is a disease of cartilage in the articular and growth physes.

  9. Skylab experiments on metals

    NASA Technical Reports Server (NTRS)

    Lundquist, C. A.

    1974-01-01

    The Skylab Materials Processing Facility is described. Eight experiments on metal processing under near-zero-gravity conditions were performed in this facility. Three of these involved metals and procedures of potential application to fabrication in space. A Multipurpose electric furnace within the Materials Processing Facility was employed to heat three ampoules of samples for each of the other five experiments. These five investigations cover diffusion versus convection rates in molten zinc, several immiscible alloy compositions, a whisker-reinforced silver-based composite, heat treating of porous silver samples, and a copper-aluminum eutectic.

  10. Exposure to metals.

    PubMed

    Hu, H

    2000-12-01

    Metals, particularly heavy metals such as lead, cadmium, and arsenic, constitute significant potential threats to human health in both occupational and environmental settings. Lead exposure is of particular concern because of ongoing exposure to thousands of workers in the US and recent research indicating that asymptomatic lead exposure can result in chronic toxicity manifestations, such as hypertension, kidney impairment, and cognitive disturbances. Mercury is neurotoxic, even at the relatively low levels of exposure seen in dentists' offices. Arsenic is clearly carcinogenic, and cadmium is now being recognized as a contributor to osteoporosis. This article reviews these and other issues of concern in the practice of primary care.

  11. Metallic carbon materials

    DOEpatents

    Cohen, Marvin Lou; Crespi, Vincent Henry; Louie, Steven Gwon Sheng; Zettl, Alexander Karlwalter

    1999-01-01

    Novel metallic forms of planar carbon are described, as well as methods of designing and making them. Nonhexagonal arrangements of carbon are introduced into a graphite carbon network essentially without destroying the planar structure. Specifically a form of carbon comprising primarily pentagons and heptagons, and having a large density of states at the Fermi level is described. Other arrangements of pentagons and heptagons that include some hexagons, and structures incorporating squares and octagons are additionally disclosed. Reducing the bond angle symmetry associated with a hexagonal arrangement of carbons increases the likelihood that the carbon material will have a metallic electron structure.

  12. Hard metal composition

    DOEpatents

    Sheinberg, H.

    1983-07-26

    A composition of matter having a Rockwell A hardness of at least 85 is formed from a precursor mixture comprising between 3 and 10 wt % boron carbide and the remainder a metal mixture comprising from 70 to 90% tungsten or molybdenum, with the remainder of the metal mixture comprising nickel and iron or a mixture thereof. The composition has a relatively low density of between 7 and 14 g/cc. The precursor is preferably hot pressed to yield a composition having greater than 100% of theoretical density.

  13. Hard metal composition

    DOEpatents

    Sheinberg, Haskell

    1986-01-01

    A composition of matter having a Rockwell A hardness of at least 85 is formed from a precursor mixture comprising between 3 and 10 weight percent boron carbide and the remainder a metal mixture comprising from 70 to 90 percent tungsten or molybdenum, with the remainder of the metal mixture comprising nickel and iron or a mixture thereof. The composition has a relatively low density of between 7 to 14 g/cc. The precursor is preferably hot pressed to yield a composition having greater than 100% of theoretical density.

  14. Metals fact sheet - lanthanum

    SciTech Connect

    1995-04-01

    Mosander was the first to extract the elusive rare earth, lanthanum, from unrefined cerium nitrate in 1839. The name was derived from the Greek word lanthanein, meaning {open_quotes}to escape notice.{close_quotes} Lanthanum is the lightest rare earth and a very malleable metal-soft enough to be cut with a knife. Used primarily as an additive in steels and non-ferrous metals, lanthanum is the lightest rare earth element and one of four rare earths from which mischmetal is made. Additional applications include advanced batteries, optical fibers, and phosphors.

  15. Liquid-metal corrosion

    SciTech Connect

    Chopra, O.K.; DeVan, J.H.; Smith, D.L.; Sze, D.K.; Tortorelli, P.F.

    1985-09-01

    A review of corrosion and environmental effects on the mechanical properties of candidate structural alloys for use with liquid metals in fusion reactors is presented. The corrosion/mass transfer behavior of austenitic and ferritic steels and vanadium-base alloys is evaluated to determine the preliminary operating temperature limits for circulating and static liquid-lithium and Pb-17Li systems. The influence of liquid-metal environment on the mechanical properties of structural materials is discussed. Corrosion effects of nitrate and fluoride salts are presented. Requirements for additional data are identified.

  16. Electron screening in metals

    NASA Astrophysics Data System (ADS)

    Gajević, J.; Lipoglavšek, M.; Likar, A.; Petrovič, T.; Pelicon, P.; Sánchez Ortiz, A.; Cvetinović, A.

    2016-01-01

    In order to further investigate electron screening effect we studied proton induced nuclear reactions over an energy range from 0.8 to 2.6 MeV for different environments: Mn and Cd metals and MnO and CdO insulators. Shifts in resonance energy for metallic relative to insulator targets were not observed. No large electron screening could be deduced for (p,γ) and (p,n) reactions in Mn. Moreover, no large electron screening can be deduced with certainty for the (p,n) reaction in Cd.

  17. Metal-smelting facility

    SciTech Connect

    Kellogg, D.R.; Mack, J.E.; Thompson, W.T.; Williams, L.C.

    1982-01-01

    Currently there are 90,000 tons of contaminated ferrous and nonferrous scrap metal stored in aboveground scrap yards at the Department of Energy's Uranium Enrichment Facilities in Tennessee, Kentucky, and Ohio. This scrap is primarily contaminated with 100 to 500 ppM uranium at an average enrichment of 1 to 1.5% /sup 235/U. A study was performed that evaluated smelting of the ORGDP metal in a reference facility located at Oak Ridge. The study defined the process systems and baseline requirements, evaluated alternatives to smelting, and provided capital and operating costs for the reference facility. A review of the results and recommendations of this study are presented.

  18. Liquid metal pump

    DOEpatents

    Pennell, William E.

    1982-01-01

    The liquid metal pump comprises floating seal rings and attachment of the pump diffuser to the pump bowl for isolating structural deflections from the pump shaft bearings. The seal rings also eliminate precision machining on large assemblies by eliminating the need for a close tolerance fit between the mounting surfaces of the pump and the seals. The liquid metal pump also comprises a shaft support structure that is isolated from the pump housing for better preservation of alignment of shaft bearings. The shaft support structure also allows for complete removal of pump internals for inspection and repair.

  19. Metal alloy identifier

    DOEpatents

    Riley, William D.; Brown, Jr., Robert D.

    1987-01-01

    To identify the composition of a metal alloy, sparks generated from the alloy are optically observed and spectrographically analyzed. The spectrographic data, in the form of a full-spectrum plot of intensity versus wavelength, provide the "signature" of the metal alloy. This signature can be compared with similar plots for alloys of known composition to establish the unknown composition by a positive match with a known alloy. An alternative method is to form intensity ratios for pairs of predetermined wavelengths within the observed spectrum and to then compare the values of such ratios with similar values for known alloy compositions, thereby to positively identify the unknown alloy composition.

  20. Heavy Metal Pumps in Plants

    SciTech Connect

    Harper, J.F.

    2000-10-01

    The long term goal of the funded research is to understand how heavy metals are taken up from the soil and translocated throughout the plant. The potential application of this research is to create plants with better heavy metal uptake systems and thereby improve the ability of these plants to help clean up toxic metals from soils. A rate limiting step is using plant for bioremediation is the normally poor capacity of plants to concentrate toxic metals. Our interest in metal ion transport systems includes those for essential mineral nutrients such as molybdenum, copper, iron, manganese, as well as toxic metals such as cerium, mercury, cesium, cadmium, arsenic and selenium. Understanding the pathways by which toxic metals accumulate in plants will enable the engineering of plants to exclude toxic metals and create healthier food sources, or to extract toxic metals from the soil as a strategy to clean up polluted lands and water.

  1. [Microbial interactions with heavy metals].

    PubMed

    Cervantes, C; Espino-Saldaña, A E; Acevedo-Aguilar, F; León-Rodriguez, I L; Rivera-Cano, M E; Avila-Rodríguez, M; Wróbel-Kaczmarczyk, K; Wróbel-Zasada, K; Gutiérrez-Corona, J F; Rodríguez-Zavala, J S; Moreno-Sánchez, R

    2006-01-01

    Living organisms are exposed in nature to heavy metals, commonly present in their ionized species. These ions exert diverse toxic effects on microorganisms. Metal exposure both selects and maintains microbial variants able to tolerate their harmful effects. Varied and efficient metal resistance mechanisms have been identified in diverse species of bacteria, fungi and protists. The study of the interactions between microorganisms and metals may be helpful to understand the relations of toxic metals with higher organisms such as mammals and plants. Some microbial systems of metal tolerance have the potential to be used in biotechnological processes, such as the bioremediation of environmental metal pollution or the recovery of valuable metals. In this work we analyze several examples of the interactions of different types of microbes with heavy metals; these cases are related either with basic research or with possible practical applications.

  2. Amorphous metallic films in silicon metallization systems

    NASA Technical Reports Server (NTRS)

    So, F.; Kolawa, E.; Nicolet, M. A.

    1985-01-01

    Diffusion barrier research was focussed on lowering the chemical reactivity of amorphous thin films on silicon. An additional area of concern is the reaction with metal overlays such as aluminum, silver, and gold. Gold was included to allow for technology transfer to gallium arsenide PV cells. Amorphous tungsten nitride films have shown much promise. Stability to annealing temperatures of 700, 800, and 550 C were achieved for overlays of silver, gold, and aluminum, respectively. The lower results for aluminum were not surprising because there is an eutectic that can form at a lower temperature. It seems that titanium and zirconium will remove the nitrogen from a tungsten nitride amorphous film and render it unstable. Other variables of research interest were substrate bias and base pressure during sputtering.

  3. Wick for metal vapor laser

    DOEpatents

    Duncan, David B.

    1992-01-01

    An improved wick for a metal vapor laser is made of a refractory metal cylinder, preferably molybdenum or tungsten for a copper laser, which provides the wicking surface. Alternately, the inside surface of the ceramic laser tube can be metalized to form the wicking surface. Capillary action is enhanced by using wire screen, porous foam metal, or grooved surfaces. Graphite or carbon, in the form of chunks, strips, fibers or particles, is placed on the inside surface of the wick to reduce water, reduce metal oxides and form metal carbides.

  4. Ultraprecision microelectroforming of metals and metal alloys

    NASA Astrophysics Data System (ADS)

    Loewe, Holger; Ehrfeld, Wolfgang; Diebel, Joerg

    1997-09-01

    In recent years, microsystem technology and its growing importance for actuators, sensors, optics and microfluidics, only to name a few, have gained a lot of attention. Specific applications demand fabrication techniques allowing a fast and reliable replication of microstructure products in a variety of materials. An important technique for replication processes of microstructures in many applications of microsystem technology are microelectroforming processes, generating a variety of metals and metal alloys with tailored characteristics. Here, new results in the development of alloys for specific applications as well as their applications are reported: (1) Newly developed alloys: Nickel-iron alloys enable the production of soft magnetic microstructures e.g. for specific applications in microactuators. Nickel-cobalt and Nickel-tungsten alloys have been employed for the manufacture of microstructured tools with excellent mechanical properties regarding wear and mechanical durability. These tools have been applied to hot-embossing and injection molding processes successfully. (2) Microelectroforming within the frame of the LIGA technique allows the manufacturing of extremely precise electrodes with various cross-sections and heights for (mu) - electro discharge machining. The combination of these techniques enables the production of microstructures from non- electrodepositable materials, like stainless steel e.g. for large scale replication processes. (3) The precision of microelectroforming enables the replication of structured surfaces on a nanoscale for molecular microelectronics or special applications. The new types of alloys reported here significantly enlarge the applicability of microelectroforming processes for tool fabrication or direct use. Moreover combining this process with other microstructuring processes like injection molding or (mu) -EDM techniques generates a powerful tool for microsystem technology.

  5. Metals in Metal Salts: A Copper Mirror Demonstration

    ERIC Educational Resources Information Center

    Pike, Robert D.

    2010-01-01

    A simple lecture demonstration is described to show the latent presence of metal atoms in a metal salt. Copper(II) formate tetrahydrate is heated in a round-bottom flask forming a high-quality copper mirror.

  6. Metal-hydrogen bridge bonding of hydrocarbons on metal surfaces

    PubMed Central

    Gavin, Robert M.; Reutt, Janice; Muetterties, Earl L.

    1981-01-01

    Molecular orbital studies implicate multicenter metal-hydrogen-carbon interactions as contributors to the bonding of chemisorbed hydrocarbons on clean metal surfaces. The most stable geometries appear to be those that achieve the maximum multicenter bonding to the coordinately unsaturated metal atoms in the vicinity of the anchoring metal-carbon interaction. Energy differences between possible surface sites are of the same magnitude as stabilization energies for three-center bonding of hydrogen atoms to the metal surface. Accordingly, secondary interactions of hydrogen with neighboring metal atoms may be significant determining factors in surface structures. The model predictions are compared with known structures and are used to propose a mechanism for hydrocarbon reactions on metal surfaces. These metal-hydrogen-carbon interactions are presumed to be intermediate points or states in C—H bond-breaking processes. PMID:16593041

  7. Metal analysis of cotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seven varieties of cotton were investigated for 8 metal ions (K, Na, Mg, Ca, Fe, Cu, Zn, and Mn) using Inductively Coupled Plasma-Optical Emission Spectroscopy. All of the varieties were grown at the same location. Half of the samples were dry (rain fed only) and the other were well-watered (irrigat...

  8. Production of pure metals

    NASA Technical Reports Server (NTRS)

    Philipp, W. H.; Marsik, S. J.; May, C. E. (Inventor)

    1974-01-01

    A process for depositing elements by irradiating liquids is reported. Ultra pure elements are precipitated from aqueous solutions or suspensions of compounds. A solution of a salt of a metal to be prepared is irradiated, and the insoluble reaction product settles out. Some chemical compounds may also be prepared in this manner.

  9. Monolithic metal oxide transistors.

    PubMed

    Choi, Yongsuk; Park, Won-Yeong; Kang, Moon Sung; Yi, Gi-Ra; Lee, Jun-Young; Kim, Yong-Hoon; Cho, Jeong Ho

    2015-04-28

    We devised a simple transparent metal oxide thin film transistor architecture composed of only two component materials, an amorphous metal oxide and ion gel gate dielectric, which could be entirely assembled using room-temperature processes on a plastic substrate. The geometry cleverly takes advantage of the unique characteristics of the two components. An oxide layer is metallized upon exposure to plasma, leading to the formation of a monolithic source-channel-drain oxide layer, and the ion gel gate dielectric is used to gate the transistor channel effectively at low voltages through a coplanar gate. We confirmed that the method is generally applicable to a variety of sol-gel-processed amorphous metal oxides, including indium oxide, indium zinc oxide, and indium gallium zinc oxide. An inverter NOT logic device was assembled using the resulting devices as a proof of concept demonstration of the applicability of the devices to logic circuits. The favorable characteristics of these devices, including (i) the simplicity of the device structure with only two components, (ii) the benign fabrication processes at room temperature, (iii) the low-voltage operation under 2 V, and (iv) the excellent and stable electrical performances, together support the application of these devices to low-cost portable gadgets, i.e., cheap electronics. PMID:25777338

  10. Ductile transplutonium metal alloys

    DOEpatents

    Conner, William V.

    1983-01-01

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  11. Serpentine metal gasket

    DOEpatents

    Rothgeb, Timothy Moore; Reece, Charles Edwin

    2009-06-02

    A metallic seal or gasket for use in the joining of cryogenic fluid conduits, the seal or gasket having a generally planar and serpentine periphery defining a central aperture. According to a preferred embodiment, the periphery has at least two opposing elongated serpentine sides and two opposing arcuate ends joining the opposing elongated serpentine sides and is of a hexagonal cross-section.

  12. Metal allergy in Singapore.

    PubMed

    Goon, Anthony T J; Goh, C L

    2005-03-01

    This is a clinical epidemiologic study to determine the frequency of metal allergy among patch-tested patients in the years 2001-2003. The results are compared with those of previous studies. All patients diagnosed as having allergic contact dermatitis in the National Skin Centre, Singapore, from January 2001 to December 2003 were studied retrospectively. The frequency of positive patch tests to the following metals were nickel 19.9%, chromate 5.6%, cobalt 8.2% and gold 8.3%. The frequency of nickel allergy has been steadily rising over the last 20 years. The most common sources of nickel allergy are costume jewelry, belt buckles, wrist watches and spectacle frames. After declining from 1984 to 1990, chromate and cobalt allergies have also been steadily increasing subsequently. The most common sources of chromate allergy were cement, leather and metal objects. Most positive patch tests to cobalt are regarded as co-sensitization due to primary nickel or chromate allergies. There has been a steep increase in positive patch tests to gold from 2001 to 2003, which is difficult to explain because the relevance and sources of such positive patch tests can rarely be determined with certainty. There has been an overall rise in the frequency of metal allergy in the last 20 years.

  13. Handbook of liquid metals

    NASA Technical Reports Server (NTRS)

    Ukanwa, A. O.

    1976-01-01

    Metals are described by physical appearance followed by atomic weight, atomic number, and valence. Data includes laboratory handling and safety procedures, heat transfer correlations, diffusion coefficients in liquid gallium/indium solution, melting and boiling points, thermal conductivity, heat capacity, and electrical resistivity.

  14. Memories in Metal

    ERIC Educational Resources Information Center

    Knepper, Claire A.

    2008-01-01

    In this article, the author shares a classroom project that she introduced to her students. The project involved decorating photographs with some metal materials. The project was inspired by "The Frame," a painting by the artist Frida Kahlo. This project aims to make students think critically and connect art to their lives.

  15. Metal optics and superconductivity

    SciTech Connect

    Golovashkin, A.L.

    1989-01-01

    The articles contained in this collection are dedicated to the study of the electron structure of transition metals and superconducting alloys and compounds based on them. The study of the electron structure of materials is one of the central problems of solid-state physics and defines the solution of a number of problems. One of them is the problem of high-temperature superconductivity which has attracted exceptional attention from physicists in connection with the discovery of new classes of ceramic oxides which are superconducting at liquid-nitrogen temperature. The electron structure is one of the three whales on which all of superconductivity rests. It is frequently our ignorance of the electronic properties of a metal, alloy or compound in its normal state which makes it impossible to predict superconductivity in the material, preventing use from calculating the parameters of the superconducting state. There are now a number of effective methods for investigation of the electron structure of the metals and allows. This collection discusses metal optics, tunneling and magnetic measurements in superconductors. These methods are quite informative and allow us to obtain many important electron characteristics and temperature relations. Various characteristics of the superconducting compounds Nb{sub 3}Ge, Nb{sub 3}Al, nb{sub 3}Sn and Nb{sub 3}Ga with A15 structure and NbN with B1 structure, having rather high critical temperatures, are experimentally studied.

  16. STRIPPING METAL COATINGS

    DOEpatents

    Siefen, H.T.; Campbell, J.M.

    1959-02-01

    A method is described for removing aluminumuranium-silicon alloy bonded to metallic U comprising subjecting the Al-U -Si alloy to treatment with hot concentrated HNO/sun 3/ to partially dissolve and embrittle the alloy and shot- blasting the embrittled alloy to loosen it from the U.

  17. Curriculum Guide for Metals.

    ERIC Educational Resources Information Center

    Oregon State Board of Education, Salem. Div. of Community Colleges and Career Education.

    Developed through a cooperative effort by industry and education, this curriculum guide outlines the basic skills and knowledge necessary for entry-level competencies in the broad field of metals, or for entrance into an apprenticeship, post-high school, or university program. This guide is one of several developed for Oregon's new approach to…

  18. Hysteresis in Metal Hydrides.

    ERIC Educational Resources Information Center

    Flanagan, Ted B., And Others

    1987-01-01

    This paper describes a reproducible process where the irreversibility can be readily evaluated and provides a thermodynamic description of the important phenomenon of hysteresis. A metal hydride is used because hysteresis is observed during the formation and decomposition of the hydride phase. (RH)

  19. Ductile transplutonium metal alloys

    DOEpatents

    Conner, W.V.

    1981-10-09

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as souces of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  20. Memory Metals (Marchon Eyewear)

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Another commercial application of memory metal technology is found in a "smart" eyeglass frame that remembers its shape and its wearer's fit. A patented "memory encoding process" makes this possible. Heat is not required to return the glasses to shape. A large commercial market is anticipated.

  1. Wings of Stretched Metal

    ERIC Educational Resources Information Center

    Nelken, Miranda

    2010-01-01

    This article presents a lesson that allows students to make bird ornaments using a metal tooling as it can be textured, cut, and colored. In this lesson, students choose a bird and sketch it on a piece of paper. Once the sketches are complete, students copy their pictures on a second piece of paper by taping the sketch over a sheet of blank paper…

  2. Cysteine metabolism and metal toxicity.

    PubMed

    Quig, D

    1998-08-01

    Chronic, low level exposure to toxic metals is an increasing global problem. The symptoms associated with the slow accumulation of toxic metals are multiple and rather nondescript, and overt expression of toxic effects may not appear until later in life. The sulfhydryl-reactive metals (mercury, cadmium, lead, arsenic) are particularly insidious and can affect a vast array of biochemical and nutritional processes. The primary mechanisms by which the sulfhydryl-reactive metals elicit their toxic effects are summarized. The pro-oxidative effects of the metals are compounded by the fact that the metals also inhibit antioxidative enzymes and deplete intracellular glutathione. The metals also have the potential to disrupt the metabolism and biological activities of many proteins due to their high affinity for free sulfhydryl groups. Cysteine has a pivotal role in inducible, endogenous detoxication mechanisms in the body, and metal exposure taxes cysteine status. The protective effects of glutathione and the metallothioneins are discussed in detail. Basic research pertaining to the transport of toxic metals into the brain is summarized, and a case is made for the use of hydrolyzed whey protein to support metal detoxification and neurological function. Metal exposure also affects essential element status, which can further decrease antioxidation and detoxification processes. Early detection and treatment of metal burden is important for successful detoxification, and optimization of nutritional status is paramount to the prevention and treatment of metal toxicity.

  3. Direct metal laser sintering: a digitised metal casting technology.

    PubMed

    Venkatesh, K Vijay; Nandini, V Vidyashree

    2013-12-01

    Dental technology is undergoing advancements at a fast pace and technology is being imported from various other fields. One such imported technology is direct metal laser sintering technology for casting metal crowns. This article will discuss the process of laser sintering for making metal crowns and fixed partial dentures with a understanding of their pros and cons. PMID:24431766

  4. 14. VIEW OF METAL ROLLING OPERATION. THE METALS ARE BEING ...

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

    14. VIEW OF METAL ROLLING OPERATION. THE METALS ARE BEING PREPARED TO BE ROLLED INTO SHEETS OF SPECIFIC THICKNESS. COMPONENT PARTS WERE FABRICATED FROM THE METAL SHEETS. (11/82) - Rocky Flats Plant, Uranium Rolling & Forming Operations, Southeast section of plant, southeast quadrant of intersection of Central Avenue & Eighth Street, Golden, Jefferson County, CO

  5. CORRELATING METAL SPECIATION IN SOILS

    EPA Science Inventory

    Understanding bioavailability of metals from exposure to contaminated soils is a challenging aspect of environmental research. This presentation will examine three areas of research with respect to metal speciation in soils as it relates to bioavailability: 1) Pb immobilization a...

  6. Purification of alkali metal nitrates

    DOEpatents

    Fiorucci, Louis C.; Gregory, Kevin M.

    1985-05-14

    A process is disclosed for removing heavy metal contaminants from impure alkali metal nitrates containing them. The process comprises mixing the impure nitrates with sufficient water to form a concentrated aqueous solution of the impure nitrates, adjusting the pH of the resulting solution to within the range of between about 2 and about 7, adding sufficient reducing agent to react with heavy metal contaminants within said solution, adjusting the pH of the solution containing reducing agent to effect precipitation of heavy metal impurities and separating the solid impurities from the resulting purified aqueous solution of alkali metal nitrates. The resulting purified solution of alkali metal nitrates may be heated to evaporate water therefrom to produce purified molten alkali metal nitrate suitable for use as a heat transfer medium. If desired, the purified molten form may be granulated and cooled to form discrete solid particles of alkali metal nitrates.

  7. Metal-binding proteins as metal pollution indicators

    SciTech Connect

    Hennig, H.F.

    1986-03-01

    The fact that metal-binding proteins are a consequence of elevated metal concentration in organisms is well known. What has been overlooked is that the presence of these proteins provides a unique opportunity to reformulate the criteria of metal pollution. The detoxification effect of metal-binding proteins in animals from polluted areas has been cited, but there have been only very few studies relating metal-binding proteins to pollution. This lack is due partly to the design of most experiments, which were aimed at isolation of metal-binding proteins and hence were of too short duration to allow for correlation to adverse physiological effects on the organism. In this study metal-binding proteins were isolated and characterized from five different marine animals (rock lobster, Jasus lalandii; hermit crab, Diogenes brevirostris; sandshrimp, Palaemon pacificus; black mussel, Choromytilus meridionalis; and limpet, Patella granularis). These animals were kept under identical metal-enriched conditions, hence eliminating differences in method and seasons. The study animals belonged to different phyla; varied in size, mass, age, behavior, food requirements and life stages; and accumulated metals at different rates. It is possible to link unseasonal moulting in crustacea, a known physiological effect due to a metal-enriched environment, to the production of the metal-binding protein without evidence of obvious metal body burden. Thus a new concept of pollution is defined: the presence of metal-binding proteins confirms toxic metal pollution. This concept was then tested under field conditions in the whelk Bullia digitalis and in metal-enriched grass.

  8. Electroless metal plating of plastics

    DOEpatents

    Krause, Lawrence J.

    1984-01-01

    Process for plating main group metals on aromatic polymers is carried out by the use of a nonaqueous solution of a salt of an alkali metal in a positive valence state and a main group metal in a negative valence state with contact between the solution and polymer providing a redox reaction causing the deposition of the main group metal and the reduction of the polymer. Products from the process exhibit useful decorative and electrical properties.

  9. Electroless metal plating of plastics

    DOEpatents

    Krause, Lawrence J.

    1986-01-01

    Process for plating main group metals on aromatic polymers is carried out by the use of a nonaqueous solution of a salt of an alkali metal in a positive valence state and a main group metal in a negative valence state with contact between the solution and polymer providing a redox reaction causing the deposition of the main group metal and the reduction of the polymer. Products from the process exhibit useful decorative and electrical properties.

  10. Electroless metal plating of plastics

    DOEpatents

    Krause, L.J.

    1982-09-20

    Process for plating main group metals on aromatic polymers is carried out by the use of a nonaqueous solution of a salt of an alkali metal in a positive valence state and a main group metal in a negative valence state with contact between the solution and polymer providing a redox reaction causing the deposition of the main group metal and the reduction of the polymer. Products from the process exhibit useful decorative and electrical properties.

  11. Upgrading platform using alkali metals

    SciTech Connect

    Gordon, John Howard

    2014-09-09

    A process for removing sulfur, nitrogen or metals from an oil feedstock (such as heavy oil, bitumen, shale oil, etc.) The method involves reacting the oil feedstock with an alkali metal and a radical capping substance. The alkali metal reacts with the metal, sulfur or nitrogen content to form one or more inorganic products and the radical capping substance reacts with the carbon and hydrogen content to form a hydrocarbon phase. The inorganic products may then be separated out from the hydrocarbon phase.

  12. Metal oxide-polymer composites

    NASA Technical Reports Server (NTRS)

    Wellinghoff, Stephen T. (Inventor)

    1994-01-01

    A method of making metal oxide clusters in a single stage by reacting a metal oxide with a substoichiometric amount of an acid in the presence of an oxide particle growth terminator and solubilizer. A method of making a ceramer is also disclosed in which the metal oxide clusters are reacted with a functionalized polymer. The resultant metal oxide clusters and ceramers are also disclosed.

  13. Metal oxide-polymer composites

    NASA Technical Reports Server (NTRS)

    Wellinghoff, Stephen T. (Inventor)

    1997-01-01

    A method of making metal oxide clusters in a single stage by reacting a metal oxide with a substoichiometric amount of an acid in the presence of an oxide particle growth terminator and solubilizer. A method of making a ceramer is also disclosed in which the metal oxide clusters are reacted with a functionalized polymer. The resultant metal oxide clusters and ceramers are also disclosed.

  14. Methods of recovering alkali metals

    DOEpatents

    Krumhansl, James L; Rigali, Mark J

    2014-03-04

    Approaches for alkali metal extraction, sequestration and recovery are described. For example, a method of recovering alkali metals includes providing a CST or CST-like (e.g., small pore zeolite) material. The alkali metal species is scavenged from the liquid mixture by the CST or CST-like material. The alkali metal species is extracted from the CST or CST-like material.

  15. SURFACE TREATMENT OF METALLIC URANIUM

    DOEpatents

    Gray, A.G.; Schweikher, E.W.

    1958-05-27

    The treatment of metallic uranium to provide a surface to which adherent electroplates can be applied is described. Metallic uranium is subjected to an etchant treatment in aqueous concentrated hydrochloric acid, and the etched metal is then treated to dissolve the resulting black oxide and/or chloride film without destroying the etched metal surface. The oxide or chloride removal is effected by means of moderately concentrated nitric acid in 3 to 20 seconds.

  16. Metal-on-metal: history, state of the art (2010)

    PubMed Central

    2011-01-01

    The history of metal-on-metal bearing began with K. Mc Kee. Several "episodes" have marked the history of metal-on-metal articulations, and each has contributed to a better understanding of this type of tribology. But to date the indications for this bearing are debated and are subject to reservations because of the existence of permanently elevated levels of circulating metal ions. It therefore appears that the monitoring of our patients, the documentation of our revisions and the collaboration with our industry partners as well as communicating with our biology and pathology colleagues is necessary to help us solve these problems. PMID:21234564

  17. Metals processing control by counting molten metal droplets

    DOEpatents

    Schlienger, Eric; Robertson, Joanna M.; Melgaard, David; Shelmidine, Gregory J.; Van Den Avyle, James A.

    2000-01-01

    Apparatus and method for controlling metals processing (e.g., ESR) by melting a metal ingot and counting molten metal droplets during melting. An approximate amount of metal in each droplet is determined, and a melt rate is computed therefrom. Impedance of the melting circuit is monitored, such as by calculating by root mean square a voltage and current of the circuit and dividing the calculated current into the calculated voltage. Analysis of the impedance signal is performed to look for a trace characteristic of formation of a molten metal droplet, such as by examining skew rate, curvature, or a higher moment.

  18. Metal-on-metal joint bearings and hematopoetic malignancy

    PubMed Central

    2012-01-01

    Abstract This is a review of the hip arthroplasty era. We concentrate on new metal bearings, surface replacements, and the lessons not learned, and we highlight recent reports on malignancies and joint implants. A low incidence of blood malignancies has been found in bone marrow taken at prosthetic surgery. The incidence is increased after replacement with knee implants that release very low systemic levels of metal ions. A carcinogenic effect of the high levels of metal ions released by large metal-on-metal implants cannot be excluded. Ongoing Swedish implant registry studies going back to 1975 can serve as a basis for evaluation of this risk. PMID:23140092

  19. Inert electrode containing metal oxides, copper and noble metal

    DOEpatents

    Ray, Siba P.; Woods, Robert W.; Dawless, Robert K.; Hosler, Robert B.

    2000-01-01

    A cermet composite material is made by treating at an elevated temperature a mixture comprising a compound of iron and a compound of at least one other metal, together with an alloy or mixture of copper and a noble metal. The alloy or mixture preferably comprises particles having an interior portion containing more copper than noble metal and an exterior portion containing more noble metal than copper. The noble metal is preferably silver. The cermet composite material preferably includes alloy phase portions and a ceramic phase portion. At least part of the ceramic phase portion preferably has a spinel structure.

  20. Inert electrode containing metal oxides, copper and noble metal

    DOEpatents

    Ray, Siba P.; Woods, Robert W.; Dawless, Robert K.; Hosler, Robert B.

    2001-01-01

    A cermet composite material is made by treating at an elevated temperature a mixture comprising a compound of iron and a compound of at least one other metal, together with an alloy or mixture of copper and a noble metal. The alloy or mixture preferably comprises particles having an interior portion containing more copper than noble metal and an exterior portion containing more noble metal than copper. The noble metal is preferably silver. The cermet composite material preferably includes alloy phase portions and a ceramic phase portion. At least part of the ceramic phase portion preferably has a spinel structure.

  1. Electrical Conductivity in Transition Metals

    ERIC Educational Resources Information Center

    Talbot, Christopher; Vickneson, Kishanda

    2013-01-01

    The aim of this "Science Note" is to describe how to test the electron-sea model to determine whether it accurately predicts relative electrical conductivity for first-row transition metals. In the electron-sea model, a metal crystal is viewed as a three-dimensional array of metal cations immersed in a sea of delocalised valence…

  2. Fabrication of metallic glass structures

    DOEpatents

    Cline, Carl F.

    1986-01-01

    Amorphous metal powders or ribbons are fabricated into solid shapes of appreciable thickness by the application of compaction energy. The temperature regime wherein the amorphous metal deforms by viscous flow is measured. The metal powders or ribbons are compacted within the temperature range.

  3. Metal Fabricating Specialist (AFSC 55252).

    ERIC Educational Resources Information Center

    Air Univ., Gunter AFS, Ala. Extension Course Inst.

    This seven-volume student text is designed for use by Air Force personnel enrolled in a self-study extension course for metal fabricating specialists. Covered in the individual volumes are general subjects (career progression, management of activities and resources, shop mathematics, and characteristics of metals); sheet metal tools and equipment…

  4. Integrated decontamination process for metals

    DOEpatents

    Snyder, Thomas S.; Whitlow, Graham A.

    1991-01-01

    An integrated process for decontamination of metals, particularly metals that are used in the nuclear energy industry contaminated with radioactive material. The process combines the processes of electrorefining and melt refining to purify metals that can be decontaminated using either electrorefining or melt refining processes.

  5. Fabrication of metallic glass structures

    DOEpatents

    Cline, C.F.

    1983-10-20

    Amorphous metal powders or ribbons are fabricated into solid shapes of appreciable thickness by the application of compaction energy. The temperature regime wherein the amorphous metal deforms by viscous flow is measured. The metal powders or ribbons are compacted within the temperature regime.

  6. Bonding Elastomers To Metal Substrates

    NASA Technical Reports Server (NTRS)

    Dickerson, George E.; Kelley, Henry L.

    1990-01-01

    Improved, economical method for bonding elastomers to metals prevents failures caused by debonding. In new technique, vulcanization and curing occur simultaneously in specially designed mold that acts as form for desired shape of elastomer and as container that positions and supports metal parts. Increases interface adhesion between metal, adhesive, and elastomer.

  7. Metal Recovery from Industrial Wastes

    NASA Astrophysics Data System (ADS)

    Brooks, Clyde S.

    1986-07-01

    This article reviews the principal factors affecting the feasibility of recovering nonferrous metals from industrial wastes. Major emphasis is on available separation process technologies with potential for metal recovery and the economics of recycling. Consideration is also given to government regulations and the strategic character of certain metals that provide important incentives for recycling.

  8. Metal species involved in long distance metal transport in plants

    PubMed Central

    Álvarez-Fernández, Ana; Díaz-Benito, Pablo; Abadía, Anunciación; López-Millán, Ana-Flor; Abadía, Javier

    2014-01-01

    The mechanisms plants use to transport metals from roots to shoots are not completely understood. It has long been proposed that organic molecules participate in metal translocation within the plant. However, until recently the identity of the complexes involved in the long-distance transport of metals could only be inferred by using indirect methods, such as analyzing separately the concentrations of metals and putative ligands and then using in silico chemical speciation software to predict metal species. Molecular biology approaches also have provided a breadth of information about putative metal ligands and metal complexes occurring in plant fluids. The new advances in analytical techniques based on mass spectrometry and the increased use of synchrotron X-ray spectroscopy have allowed for the identification of some metal-ligand species in plant fluids such as the xylem and phloem saps. Also, some proteins present in plant fluids can bind metals and a few studies have explored this possibility. This study reviews the analytical challenges researchers have to face to understand long-distance metal transport in plants as well as the recent advances in the identification of the ligand and metal-ligand complexes in plant fluids. PMID:24723928

  9. Heavy metal tolerance in metal hyperaccumulator plant, Salvinia natans.

    PubMed

    Dhir, B; Srivastava, S

    2013-06-01

    Metal tolerance capacity of Salvinia natans, a metal hyperaccumulator, was evaluated. Plants were exposed to 10, 30 and 50 mg L⁻¹ of Zn, Cd, Co, Cr, Fe, Cu, Pb, and Ni. Plant biomass, photosynthetic efficiency, quantum yield, photochemical quenching, electron transport rate and elemental (%C, H and N) constitution remained unaffected in Salvinia exposed to 30 mg L⁻¹ of heavy metals, except for Cu and Zn exposed plants, where significant reductions were noted in some of the measured parameters. However, a significant decline was noted in most of the measured parameters in plants exposed to 50 mg L⁻¹ of metal concentration. Results suggest that Salvinia has fairly high levels of tolerance to all the metals tested, but the level of tolerance varied from metal to metal. PMID:23553503

  10. Superconductivity in transition metals.

    PubMed

    Slocombe, Daniel R; Kuznetsov, Vladimir L; Grochala, Wojciech; Williams, Robert J P; Edwards, Peter P

    2015-03-13

    A qualitative account of the occurrence and magnitude of superconductivity in the transition metals is presented, with a primary emphasis on elements of the first row. Correlations of the important parameters of the Bardeen-Cooper-Schrieffer theory of superconductivity are highlighted with respect to the number of d-shell electrons per atom of the transition elements. The relation between the systematics of superconductivity in the transition metals and the periodic table high-lights the importance of short-range or chemical bonding on the remarkable natural phenomenon of superconductivity in the chemical elements. A relationship between superconductivity and lattice instability appears naturally as a balance and competition between localized covalent bonding and so-called broken covalency, which favours d-electron delocalization and superconductivity. In this manner, the systematics of superconductivity and various other physical properties of the transition elements are related and unified.

  11. Superconductivity in transition metals.

    PubMed

    Slocombe, Daniel R; Kuznetsov, Vladimir L; Grochala, Wojciech; Williams, Robert J P; Edwards, Peter P

    2015-03-13

    A qualitative account of the occurrence and magnitude of superconductivity in the transition metals is presented, with a primary emphasis on elements of the first row. Correlations of the important parameters of the Bardeen-Cooper-Schrieffer theory of superconductivity are highlighted with respect to the number of d-shell electrons per atom of the transition elements. The relation between the systematics of superconductivity in the transition metals and the periodic table high-lights the importance of short-range or chemical bonding on the remarkable natural phenomenon of superconductivity in the chemical elements. A relationship between superconductivity and lattice instability appears naturally as a balance and competition between localized covalent bonding and so-called broken covalency, which favours d-electron delocalization and superconductivity. In this manner, the systematics of superconductivity and various other physical properties of the transition elements are related and unified. PMID:25666075

  12. FLUIDIC: Metal Air Recharged

    ScienceCinema

    Friesen, Cody

    2016-07-12

    Fluidic, with the help of ARPA-E funding, has developed and deployed the world's first proven high cycle life metal air battery. Metal air technology, often used in smaller scale devices like hearing aids, has the lowest cost per electron of any rechargeable battery storage in existence. Deploying these batteries for grid reliability is competitive with pumped hydro installations while having the advantages of a small footprint. Fluidic's battery technology allows utilities and other end users to store intermittent energy generated from solar and wind, as well as maintain reliable electrical delivery during power outages. The batteries are manufactured in the US and currently deployed to customers in emerging markets for cell tower reliability. As they continue to add customers, they've gained experience and real world data that will soon be leveraged for US grid reliability.

  13. FLUIDIC: Metal Air Recharged

    SciTech Connect

    Friesen, Cody

    2014-03-07

    Fluidic, with the help of ARPA-E funding, has developed and deployed the world's first proven high cycle life metal air battery. Metal air technology, often used in smaller scale devices like hearing aids, has the lowest cost per electron of any rechargeable battery storage in existence. Deploying these batteries for grid reliability is competitive with pumped hydro installations while having the advantages of a small footprint. Fluidic's battery technology allows utilities and other end users to store intermittent energy generated from solar and wind, as well as maintain reliable electrical delivery during power outages. The batteries are manufactured in the US and currently deployed to customers in emerging markets for cell tower reliability. As they continue to add customers, they've gained experience and real world data that will soon be leveraged for US grid reliability.

  14. Metals fact sheet - indium

    SciTech Connect

    1994-01-01

    Indium is generally found in concentrations averaging 10 to 20 ppm in sphalerite and chalcopyrite ores associated with zinc, copper, lead and tin deposits. Indium is recovered as a by-product of base metal mining by open pit, underground and other methods. After the recovery of zinc by the electrolytic process (copper concentrate by flotation, and lead and tin by electrolysis), indium antimonide slimes left on the anode and the indium-containing spent electrolyte become the input material for the processing of indium. Sulfuric acid is combined with the residues and heated to form sulfates which are then leached with water to filter off the remaining tin, lead and antimony. The indium in solution is recovered by cementation on aluminum, washed, melted, and refined into a metal.

  15. Invisible metallic mesh.

    PubMed

    Ye, Dexin; Lu, Ling; Joannopoulos, John D; Soljačić, Marin; Ran, Lixin

    2016-03-01

    A solid material possessing identical electromagnetic properties as air has yet to be found in nature. Such a medium of arbitrary shape would neither reflect nor refract light at any angle of incidence in free space. Here, we introduce nonscattering corrugated metallic wires to construct such a medium. This was accomplished by aligning the dark-state frequencies in multiple scattering channels of a single wire. Analytical solutions, full-wave simulations, and microwave measurement results on 3D printed samples show omnidirectional invisibility in any configuration. This invisible metallic mesh can improve mechanical stability, electrical conduction, and heat dissipation of a system, without disturbing the electromagnetic design. Our approach is simple, robust, and scalable to higher frequencies. PMID:26884208

  16. Invisible metallic mesh

    PubMed Central

    Ye, Dexin; Lu, Ling; Joannopoulos, John D.; Soljačić, Marin; Ran, Lixin

    2016-01-01

    A solid material possessing identical electromagnetic properties as air has yet to be found in nature. Such a medium of arbitrary shape would neither reflect nor refract light at any angle of incidence in free space. Here, we introduce nonscattering corrugated metallic wires to construct such a medium. This was accomplished by aligning the dark-state frequencies in multiple scattering channels of a single wire. Analytical solutions, full-wave simulations, and microwave measurement results on 3D printed samples show omnidirectional invisibility in any configuration. This invisible metallic mesh can improve mechanical stability, electrical conduction, and heat dissipation of a system, without disturbing the electromagnetic design. Our approach is simple, robust, and scalable to higher frequencies. PMID:26884208

  17. Noble metals in oncology

    PubMed Central

    Markowska, Anna; Jaszczyńska-Nowinka, Karolina; Lubin, Jolanta; Markowska, Janina

    2015-01-01

    Worldwide research groups are searching for anticancer compounds, many of them are organometalic complexes having platinum group metals as their active centers. Most commonly used cytostatics from this group are cisplatin, carboplatin and oxaliplatin. Cisplatin was used fot the first time in 1978, from this time many platinum derivatives were created. In this review we present biological properties and probable future clinical use of platinum, gold, silver, iridium and ruthenium derivatives. Gold derivative Auranofin has been studied extensively. Action of silver nanoparticles on different cell lines was analysed. Iridium isotopes are commonly used in brachyterapy. Ruthenium compound new anti-tumour metastasis inhibitor (NAMI-A) is used in managing lung cancer metastases. Electroporation of another ruthenium based compound KP1339 was also studied. Most of described complexes have antiproliferative and proapoptotic properties. Further studies need to be made. Nevertheless noble metal based chemotherapheutics and compounds seem to be an interesting direction of research. PMID:26557773

  18. Fragmentation properties of metals

    SciTech Connect

    Grady, D.E.; Kipp, M.E.

    1996-06-01

    In the present study we are developing an experimental fracture material property test method specific to dynamic fragmentation. Spherical test samples of the metals of interest are subjected to controlled impulsive stress loads by acceleration to high velocities with a light-gas launcher facility and subsequent normal impact on thin plates. Motion, deformation and fragmentation of the test samples are diagnosed with multiple flash radiography methods. The impact plate materials are selected to be transparent to the x-ray method so that only test metal material is imaged. Through a systematic series of such tests, both strain-to-failure and fragmentation resistance properties are determined through this experimental method. Fragmentation property data for several steels, copper, aluminum, tantalum and titanium have been obtained to date. Aspects of the dynamic data have been analyzed with computational methods to achieve a better understanding of the processes leading to failure and fragmentation, and to test an existing computational fragmentation model.

  19. Amorphous metal alloy

    DOEpatents

    Wang, R.; Merz, M.D.

    1980-04-09

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  20. Memory metal actuator

    NASA Technical Reports Server (NTRS)

    Ruoff, C. F. (Inventor)

    1985-01-01

    A mechanical actuator can be constructed by employing a plurality of memory metal actuator elements in parallel to control the amount of actuating force. In order to facilitate direct control by digital control signals provided by a computer or the like, the actuating elements may vary in stiffness according to a binary relationship. The cooling or reset time of the actuator elements can be reduced by employing Peltier junction cooling assemblies in the actuator.

  1. Glycosylated Metal Phthalocyanines.

    PubMed

    Hanack, Michael

    2015-11-10

    In the first part; the syntheses of mono-; di-; and tetra-glycosylated phthalonitriles is described; which are the most used starting materials for the preparation of the corresponding glycosylated metal (mostly zinc) phthalocyanines. In the second section; the preparation of symmetric and unsymmetric mono-; tetra-; and octa- glycosylated zinc phthalocyanines are reviewed; in which the sugar is attached to the phthalocyanine macrocycle; either anomerically or via another one of its OH-groups.

  2. Development of metallization process

    NASA Astrophysics Data System (ADS)

    Garcia, A., III

    1983-04-01

    Solar cells were produced using a Mo/Sn/TiH screen printed paste with a lead/borosilicate frit that are electrically comparable to control silver cells. The process is currently unsuccessful because the soldering of interconnects to these cells has proved difficult. Future work will investigate using CO instead of H2 as the reducing gas and putting an ITO coating on the cell prior to metallization.

  3. Metals and kidney autoimmunity.

    PubMed Central

    Bigazzi, P E

    1999-01-01

    The causes of autoimmune responses leading to human kidney pathology remain unknown. However, environmental agents such as microorganisms and/or xenobiotics are good candidates for that role. Metals, either present in the environment or administered for therapeutic reasons, are prototypical xenobiotics that cause decreases or enhancements of immune responses. In particular, exposure to gold and mercury may result in autoimmune responses to various self-antigens as well as autoimmune disease of the kidney and other tissues. Gold compounds, currently used in the treatment of patients with progressive polyarticular rheumatoid arthritis, can cause a nephrotic syndrome. Similarly, an immune-mediated membranous nephropathy frequently occurred when drugs containing mercury were commonly used. Recent epidemiologic studies have shown that occupational exposure to mercury does not usually result in autoimmunity. However, mercury induces antinuclear antibodies, sclerodermalike disease, lichen planus, or membranous nephropathy in some individuals. Laboratory investigations have confirmed that the administration of gold or mercury to experimental animals leads to autoimmune disease quite similar to that observed in human subjects exposed to these metals. In addition, studies of inbred mice and rats have revealed that a few strains are susceptible to the autoimmune effects of gold and mercury, whereas the majority of inbred strains are resistant. These findings have emphasized the importance of genetic (immunogenetic and pharmacogenetic) factors in the induction of metal-associated autoimmunity. (italic)In vitro(/italic) and (italic)in vivo(/italic) research of autoimmune disease caused by mercury and gold has already yielded valuable information and answered a number of important questions. At the same time it has raised new issues about possible immunostimulatory or immunosuppressive mechanisms of xenobiotic activity. Thus it is evident that investigations of metal

  4. Metals fact sheet - uranium

    SciTech Connect

    1996-04-01

    About 147 million pounds of this radioactive element are consumed annually by the worldwide nuclear power and weapons industries, as well as in the manufacture of ceramics and metal products. The heaviest naturally occurring element, uranium is typically found in intrusive granites, igneous and metamorphic veins, tabular sedimentary deposits, and unconformity-related structures. This article discusses the geology, exploitation, market, and applications of uranium and uranium ores.

  5. PRODUCTION OF ACTINIDE METAL

    DOEpatents

    Knighton, J.B.

    1963-11-01

    A process of reducing actinide oxide to the metal with magnesium-zinc alloy in a flux of 5 mole% of magnesium fluoride and 95 mole% of magnesium chloride plus lithium, sodium, potassium, calcium, strontium, or barium chloride is presented. The flux contains at least 14 mole% of magnesium cation at 600-- 900 deg C in air. The formed magnesium-zinc-actinide alloy is separated from the magnesium-oxide-containing flux. (AEC)

  6. METAL COATING BATHS

    DOEpatents

    Robinson, J.W.

    1958-08-26

    A method is presented for restoring the effectiveness of bronze coating baths used for hot dip coating of uranium. Such baths, containing a high proportion of copper, lose their ability to wet uranium surfaces after a period of use. The ability of such a bath to wet uranium can be restored by adding a small amount of metallic aluminum to the bath, and skimming the resultant hard alloy from the surface.

  7. PREFACE: Half Metallic Ferromagnets

    NASA Astrophysics Data System (ADS)

    Dowben, Peter

    2007-08-01

    Since its introduction by de Groot and colleagues in the early 1980s [1], the concept of half metallic ferromagnetism has attracted great interest. Idealized, half-metals have only one spin channel for conduction: the spin-polarized band structure exhibits metallic behavior for one spin channel, while the other spin band structure exhibits a gap at the Fermi level. Due to the gap for one spin direction, the density of states at the Fermi level has, theoretically, 100 & spin polarization. This gap in the density of states in one spin at the Fermi level, for example ↓ so N↓ (EF) = 0, also causes the resistance of that channel to go to infinity. At zero or low temperatures, the nonquasiparticle density of states (electron correlation effects), magnons and spin disorder reduce the polarization from the idealized 100 & polarization. At higher temperatures magnon-phonon coupling and irreversible compositional changes affect polarization further. Strategies for assessing and reducing the effects of finite temperatures on the polarization are now gaining attention. The controversies surrounding the polarization stability of half metallic ferromagnets are not, however, limited to the consideration of finite temperature effects alone. While many novel half metallic materials have been predicted, materials fabrication can be challenging. Defects, surface and interface segregation, and structural stability can lead to profound decreases in polarization, but can also suppress long period magnons. There is a 'delicate balance of energies required to obtain half metallic behaviour: to avoid spin flip scattering, tiny adjustments in atomic positions might occur so that a gap opens up in the other spin channel' [2]. When considering 'spintronics' devices, a common alibi for the study of half metallic systems, surfaces and interfaces become important. Free enthalpy differences between the surface and the bulk will lead to spin minority surface and interface states, as well as

  8. Half metallic ferromagnets.

    PubMed

    Dowben, Peter

    2007-08-01

    Since its introduction by de Groot and colleagues in the early 1980s [1], the concept of half metallic ferromagnetism has attracted great interest. Idealized, half-metals have only one spin channel for conduction: the spin-polarized band structure exhibits metallic behavior for one spin channel, while the other spin band structure exhibits a gap at the Fermi level. Due to the gap for one spin direction, the density of states at the Fermi level has, theoretically, 100 & spin polarization. This gap in the density of states in one spin at the Fermi level, for example ↓ so N(↓) (E(F)) = 0, also causes the resistance of that channel to go to infinity. At zero or low temperatures, the nonquasiparticle density of states (electron correlation effects), magnons and spin disorder reduce the polarization from the idealized 100 & polarization. At higher temperatures magnon-phonon coupling and irreversible compositional changes affect polarization further. Strategies for assessing and reducing the effects of finite temperatures on the polarization are now gaining attention. The controversies surrounding the polarization stability of half metallic ferromagnets are not, however, limited to the consideration of finite temperature effects alone. While many novel half metallic materials have been predicted, materials fabrication can be challenging. Defects, surface and interface segregation, and structural stability can lead to profound decreases in polarization, but can also suppress long period magnons. There is a 'delicate balance of energies required to obtain half metallic behaviour: to avoid spin flip scattering, tiny adjustments in atomic positions might occur so that a gap opens up in the other spin channel' [2]. When considering 'spintronics' devices, a common alibi for the study of half metallic systems, surfaces and interfaces become important. Free enthalpy differences between the surface and the bulk will lead to spin minority surface and interface states, as well

  9. Electron energies in metals

    SciTech Connect

    Mahan, G.D. Tennessee Univ., Knoxville, TN . Dept. of Physics and Astronomy)

    1991-07-10

    The modern era of electron-electron interactions began a decade ago. Plummer's group initiated a program of using angular resolved photoemission to examine the band structure of the simple metals. Beginning with aluminum, and carrying on to sodium and potassium, they always found that the occupied energy bands were much narrower than expected. For example, the compressed energy bands for metallic potassium suggest a band effective mass of m* = 1.33m{sub e}. This should be compared to the band mass found from optical conductivity m*/m{sub e} = 1.01 {plus minus} 0.01. The discrepancy between these results is startling. It was this great difference which started my group doing calculations. Our program was two-fold. On one hand, we reanalyzed the experimental data, in order to see if Plummer's result was an experimental artifact. On the other hand, we completely redid the electron-electron self-energy calculations for simple metals, using the most modern choices of local-field corrections and vertex corrections. Our results will be reported in these lectures. They can be summarized as following: Our calculations give the same effective masses as the older calculations, so the theory is relatively unchanged; Our analysis of the experiments suggests that the recent measurements of band narrowing are an experimental artifact. 38 refs., 9 figs.

  10. Metal Nanoparticle Aerogel Composites

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Sibille, Laurent; Ignont, Erica; Snow, Lanee; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    We have fabricated sol-gels containing gold and silver nanoparticles. Formation of an aerogel produces a blue shift in the surface plasmon resonance as a result of the decrease in the dielectric constant of the matrix upon supercritical extraction of the solvent. However, as a result of chemical interface damping this blue shift does not obey effective medium theories. Annealing the samples in a reducing atmosphere at 400 C eliminates this discrepancy and results in narrowing and further blue shifting of the plasmon resonance. Metal particle aggregation also results in a deviation from the predictions of effective medium theories, but can be controlled through careful handling and by avoiding the use of alcohol. By applying effective medium theories to the heterogeneous interlayer surrounding each metal particle, we extend the technique of immersion spectroscopy to inhomogeneous materials characterized by spatially dependent dielectric constants, such as aerogels. We demonstrate that the shift in the surface plasmon wavelength provides the average fractional composition of each component (air and silica) in this inhomogeneous layer, i.e. the porosity of the aerogel or equivalently, for these materials, the catalytic dispersion. Additionally, the kinetics suggest that collective particle interactions in coagulated metal clusters are perturbed during silica gelation resulting in a change in the aggregate geometry.

  11. Spray casting of metallic preforms

    DOEpatents

    Flinn, John E.; Burch, Joseph V.; Sears, James W.

    2000-01-01

    A metal alloy is melted in a crucible and ejected from the bottom of the crucible as a descending stream of molten metal. The descending stream is impacted with a plurality of primary inert gas jets surrounding the molten metal stream to produce a plume of atomized molten metal droplets. An inert gas is blown onto a lower portion of the plume with a plurality of auxiliary inert gas jets to deflect the plume into a more restricted pattern of high droplet density, thereby substantially eliminating unwanted overspray and resulting wasted material. The plume is projected onto a moving substrate to form a monolithic metallic product having generally parallel sides.

  12. Critical points of metal vapors

    SciTech Connect

    Khomkin, A. L. Shumikhin, A. S.

    2015-09-15

    A new method is proposed for calculating the parameters of critical points and binodals for the vapor–liquid (insulator–metal) phase transition in vapors of metals with multielectron valence shells. The method is based on a model developed earlier for the vapors of alkali metals, atomic hydrogen, and exciton gas, proceeding from the assumption that the cohesion determining the basic characteristics of metals under normal conditions is also responsible for their properties in the vicinity of the critical point. It is proposed to calculate the cohesion of multielectron atoms using well-known scaling relations for the binding energy, which are constructed for most metals in the periodic table by processing the results of many numerical calculations. The adopted model allows the parameters of critical points and binodals for the vapor–liquid phase transition in metal vapors to be calculated using published data on the properties of metals under normal conditions. The parameters of critical points have been calculated for a large number of metals and show satisfactory agreement with experimental data for alkali metals and with available estimates for all other metals. Binodals of metals have been calculated for the first time.

  13. Heavy metals bioremediation of soil.

    PubMed

    Diels, L; De Smet, M; Hooyberghs, L; Corbisier, P

    1999-09-01

    Historical emissions of old nonferrous factories lead to large geographical areas of metals-contaminated sites. At least 50 sites in Europe are contaminated with metals like Zn, Cd, Cu, and Pb. Several methods, based on granular differentiation, were developed to reduce the metals content. However, the obtained cleaned soil is just sand. Methods based on chemical leaching or extraction or on electrochemistry do release a soil without any salts and with an increased bioavailability of the remaining metals content. In this review a method is presented for the treatment of sandy soil contaminated with heavy metals. The system is based on the metal solubilization on biocyrstallization capacity of Alcaligenes eutrophus CH34. The bacterium can solubilize the metals (or increase their bioavailability) via the production of siderophores and adsorb the metals in their biomass on metal-induced outer membrane proteins and by bioprecipitation. After the addition of CH34 to a soil slurry, the metals move toward the biomass. As the bacterium tends to float quite easily, the biomass is separated from the water via a flocculation process. The Cd concentration in sandy soils could be reduced from 21 mg Cd/kg to 3.3 mg Cd/kg. At the same time, Zn was reduced from 1070 mg Zn/kg to 172 mg Zn/kg. The lead concentration went down from 459 mg Pb/kg to 74 mg Pb/kg. With the aid of biosensors, a complete decrease in bioavailability of the metals was measured.

  14. Hydrothermal alkali metal recovery process

    DOEpatents

    Wolfs, Denise Y.; Clavenna, Le Roy R.; Eakman, James M.; Kalina, Theodore

    1980-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by treating them with a calcium or magnesium-containing compound in the presence of water at a temperature between about 250.degree. F. and about 700.degree. F. and in the presence of an added base to establish a pH during the treatment step that is higher than would otherwise be possible without the addition of the base. During the treating process the relatively high pH facilitates the conversion of water-insoluble alkali metal compounds in the alkali metal residues into water-soluble alkali metal constituents. The resultant aqueous solution containing water-soluble alkali metal constituents is then separated from the residue solids, which consist of the treated particles and any insoluble materials formed during the treatment step, and recycled to the gasification process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst. Preferably, the base that is added during the treatment step is an alkali metal hydroxide obtained by water washing the residue solids produced during the treatment step.

  15. Flexible thin metal film thermal sensing system

    NASA Technical Reports Server (NTRS)

    Thomsen, Donald L. (Inventor)

    2010-01-01

    A flexible thin metal film thermal sensing system is provided. A self-metallized polymeric film has a polymeric film region and a metal surface disposed thereon. A layer of electrically-conductive metal is deposited directly onto the self-metallized polymeric film's metal surface. Coupled to at least one of the metal surface and the layer of electrically-conductive metal is a device/system for measuring an electrical characteristic associated therewith as an indication of temperature.

  16. Synthetic Metal-Containing Polymers

    NASA Astrophysics Data System (ADS)

    Manners, Ian

    2004-04-01

    The development of the field of synthetic metal-containing polymers - where metal atoms form an integral part of the main chain or side group structure of a polymer - aims to create new materials which combine the processability of organic polymers with the physical or chemical characteristics associated with the metallic element or complex. This book covers the major developments in the synthesis, properties, and applications of synthetic metal-containing macromolecules, and includes chapters on the preparation and characterization of metal-containing polymers, metallocene-based polymers, rigid-rod organometallic polymers, coordination polymers, polymers containing main group metals, and also covers dendritic and supramolecular systems. The book describes both polymeric materials with metals in the main chain or side group structure and covers the literature up to the end of 2002.

  17. Dimensionally stable metallic hydride composition

    DOEpatents

    Heung, Leung K.

    1994-01-01

    A stable, metallic hydride composition and a process for making such a composition. The composition comprises a uniformly blended mixture of a metal hydride, kieselguhr, and a ballast metal, all in the form of particles. The composition is made by subjecting a metal hydride to one or more hydrogen absorption/desorption cycles to disintegrate the hydride particles to less than approximately 100 microns in size. The particles are partly oxidized, then blended with the ballast metal and the kieselguhr to form a uniform mixture. The mixture is compressed into pellets and calcined. Preferably, the mixture includes approximately 10 vol. % or more kieselguhr and approximately 50 vol. % or more ballast. Metal hydrides that can be used in the composition include Zr, Ti, V, Nb, Pd, as well as binary, tertiary, and more complex alloys of La, Al, Cu, Ti, Co, Ni, Fe, Zr, Mg, Ca, Mn, and mixtures and other combinations thereof. Ballast metals include Al, Cu and Ni.

  18. Reduction of Metal Oxide to Metal using Ionic Liquids

    SciTech Connect

    Dr. Ramana Reddy

    2012-04-12

    A novel pathway for the high efficiency production of metal from metal oxide means of electrolysis in ionic liquids at low temperature was investigated. The main emphasis was to eliminate the use of carbon and high temperature application in the reduction of metal oxides to metals. The emphasis of this research was to produce metals such as Zn, and Pb that are normally produced by the application of very high temperatures. The reduction of zinc oxide to zinc and lead oxide to lead were investigated. This study involved three steps in accomplishing the final goal of reduction of metal oxide to metal using ionic liquids: 1) Dissolution of metal oxide in an ionic liquid, 2) Determination of reduction potential using cyclic voltammetry (CV) and 3) Reduction of the dissolved metal oxide. Ionic liquids provide additional advantage by offering a wide potential range for the deposition. In each and every step of the process, more than one process variable has been examined. Experimental results for electrochemical extraction of Zn from ZnO and Pb from PbO using eutectic mixtures of Urea ((NH2)2CO) and Choline chloride (HOC2H4N(CH3)3+Cl-) or (ChCl) in a molar ratio 2:1, varying voltage and temperatures were carried out. Fourier Transform Infra-Red (FTIR) spectroscopy studies of ionic liquids with and without metal oxide additions were conducted. FTIR and induction coupled plasma spectroscopy (ICPS) was used in the characterization of the metal oxide dissolved ionic liquid. Electrochemical experiments were conducted using EG&G potentiostat/galvanostat with three electrode cell systems. Cyclic voltammetry was used in the determination of reduction potentials for the deposition of metals. Chronoamperometric experiments were carried out in the potential range of -0.6V to -1.9V for lead and -1.4V to -1.9V for zinc. The deposits were characterized using XRD and SEM-EDS for phase, morphological and elemental analysis. The results showed that pure metal was deposited on the cathode

  19. Metal bioremediation through growing cells.

    PubMed

    Malik, Anushree

    2004-04-01

    Heavy-metal pollution represents an important environmental problem due to the toxic effects of metals, and their accumulation throughout the food chain leads to serious ecological and health problems. Metal remediation through common physico-chemical techniques is expensive and unsuitable in case of voluminous effluents containing complexing organic matter and low metal contamination. Biotechnological approaches that are designed to cover such niches have, therefore, received great deal of attention in the recent years. Biosorption studies involving low-cost and often dead/pretreated biomass have dominated the literature and, subsequently, extensive reviews focusing on equilibrium and kinetics of metal biosorption have also come up. However, the low binding capacity of biomass for certain recalcitrant metals such as Ni and failure to effectively remove metals from real industrial effluents due to presence of organic or inorganic ligands limit this approach. At times, when pure biosorptive metal removal is not feasible, application of a judicious consortium of growing metal-resistant cells can ensure better removal through a combination of bioprecipitation, biosorption and continuous metabolic uptake of metals after physical adsorption. Such approach may lead to simultaneous removal of toxic metals, organic loads and other inorganic impurities, as well as allow optimization through development of resistant species. However, sensitivity of living cells to extremes of pH or high metal concentration and need to furnish metabolic energy are some of the major constraints of employing growing cells for bioremediation. The efforts to meet such challenges via isolation of metal-resistant bacterial/fungal strains and exploitation of organic wastes as carbon substrates have began. Recent studies show that the strains (bacteria, yeast and fungi) isolated from contaminated sites possess excellent capability of metal scavenging. Some bacterial strains possess high tolerance to

  20. Corrosion protective coating for metallic materials

    DOEpatents

    Buchheit, Rudolph G.; Martinez, Michael A.

    1998-01-01

    Corrosion protective coatings for metallic materials, particularly aluminum and aluminum alloys, produced with simple, low-cost equipment and materials other than toxic metals or metal salts, or metal cyanides. The metallic material is cleaned, degreased, and deoxidized, the surface is converted to a substantially alkaline condition, and the surface is chemically sealed with inorganic metal compounds.

  1. Corrosion protective coating for metallic materials

    DOEpatents

    Buchheit, R.G.; Martinez, M.A.

    1998-05-26

    Corrosion protective coatings for metallic materials, particularly aluminum and aluminum alloys, produced with simple, low-cost equipment and materials other than toxic metals or metal salts, or metal cyanides is disclosed. The metallic material is cleaned, degreased, and deoxidized, the surface is converted to a substantially alkaline condition, and the surface is chemically sealed with inorganic metal compounds. 1 fig.

  2. Mechanical failure of metal-polyethylene sandwich liner in metal-on-metal total hip replacement.

    PubMed

    Oshima, Yasushi; Fetto, Joseph F

    2015-01-01

    Metal-on-metal had been proposed as an optimal articulation in THRs, however, many monoblock prostheses have been recalled in the USA because of significant high rates of early failure. Metal-on-metal prostheses had been implanted in our institution, and this is a case history of a single patient, in whom metal-on-metal THRs with different femoral sizes of heads were implanted. A 57-year-old female patient underwent bilateral total hip replacements with metal-on-metal prostheses using metal-polyethylene "sandwich" liners 9 years ago on the right side and 7 years ago on the left side respectively. The only difference in both sides was the femoral head diameter of 28 mm in right and 34 mm in left. Seven years after the left surgery, the acetabular liner was dissociated, however, metallosis was not detected. Although the larger femoral head was thought to increase hip joint stability, it dictated a reduction in polyethylene thickness in this prosthesis design, and it was 4 mm in the left hip. Recently, metal-on-metal articulations are thought not to be optimal for hip joint bearing surface, however, this clinical failure was due to the polyethylene thickness and quality.

  3. The interaction of a metal deactivator with metal surfaces

    SciTech Connect

    Schreifels, J.A. ); Morris, R.E.; Turner, N.H.; Mowery, R.L. )

    1990-01-01

    In modern aircraft fuel systems, the fuel is used as a heat transfer medium to dissipate heat from the avionics and hydraulic systems. Under these conditions, the fuel can undergo autooxidations. Autooxidations of net fuel can result in the formation of insoluble gum and sediment which can impair operation of the jet engine. Metal deactivator additives (MDA) were developed to counteract the catalytic activity of dissolved metals. The authors have directed their efforts at ascertaining the various mechanisms by which MDA can act, particularly in accelerated stability testing. One objective of this study was to determine to what extent interactions with metal surfaces of the test apparent govern the effectiveness of metal deactivators. This paper describes an examination of metal surfaces exposed to MDA solutions to determine under what, if any, conditions metal passivation can occur.

  4. Alkali metal-refractory metal biphase electrode for AMTEC

    NASA Technical Reports Server (NTRS)

    Williams, Roger M. (Inventor); Bankston, Clyde P. (Inventor); Cole, Terry (Inventor); Khanna, Satish K. (Inventor); Jeffries-Nakamura, Barbara (Inventor); Wheeler, Bob L. (Inventor)

    1989-01-01

    An electrode having increased output with slower degradation is formed of a film applied to a beta-alumina solid electrolyte (BASE). The film comprises a refractory first metal M.sup.1 such as a platinum group metal, suitably platinum or rhodium, capable of forming a liquid or a strong surface adsorption phase with sodium at the operating temperature of an alkali metal thermoelectric converter (AMTEC) and a second refractory metal insoluble in sodium or the NaM.sup.1 liquid phase such as a Group IVB, VB or VIB metal, suitably tungsten, molybdenum, tantalum or niobium. The liquid phase or surface film provides fast transport through the electrode while the insoluble refractory metal provides a structural matrix for the electrode during operation. A trilayer structure that is stable and not subject to deadhesion comprises a first, thin layer of tungsten, an intermediate co-deposited layer of tungsten-platinum and a thin surface layer of platinum.

  5. Graphitic Tribological Layers in Metal-on-Metal Hip Replacements

    NASA Astrophysics Data System (ADS)

    Liao, Y.; Pourzal, R.; Wimmer, M. A.; Jacobs, J. J.; Fischer, A.; Marks, L. D.

    2011-12-01

    Arthritis is a leading cause of disability, and when nonoperative methods have failed, a prosthetic implant is a cost-effective and clinically successful treatment. Metal-on-metal replacements are an attractive implant technology, a lower-wear alternative to metal-on-polyethylene devices. Relatively little is known about how sliding occurs in these implants, except that proteins play a critical role and that there is a tribological layer on the metal surface. We report evidence for graphitic material in the tribological layer in metal-on-metal hip replacements retrieved from patients. As graphite is a solid lubricant, its presence helps to explain why these components exhibit low wear and suggests methods of improving their performance; simultaneously, this raises the issue of the physiological effects of graphitic wear debris.

  6. Metals at high redshifts

    NASA Astrophysics Data System (ADS)

    Petitjean, Patrick

    The amount of metals present in the Universe and its cosmological evolution is a key issue for our understanding of how star formation proceeds from the collapse of the first objects to the formation of present day galaxies. We discuss here recent results at the two extremes of the density scale. 1. Part of the tenuous intergalactic medium (IGM) revealed by neutral hydrogen absorptions in the spectra of remote quasars (the so-called Lyman-α forest) contains metals. This is not surprising as there is a close interplay between the formation of galaxies and the evolution of the IGM. The IGM acts as the baryonic reservoir from which galaxies form, while star formation in the forming galaxies strongly influences the IGM by enrichment with metals and the emission of ionizing radiation. The spatial distribution of metals in the IGM is largely unknown however. The possibility remains that metals are associated with the filaments and sheets of the dark matter spatial distribution where stars are expected to form, whereas the space delineated by these features remains unpolluted. 2. Damped Lyman-α (DLA) systems observed in the spectra of high-redshift quasars are considered as the progenitors of present-day galaxies. Indeed, the large neutral hydrogen column densities observed and the presence of metals imply that the gas is somehow closely associated with regions of star formation. The nature of the absorbing objects is unclear however. It is probable that very different objects contribute to this population of absorption systems. Here we concentrate on summarizing the properties of the gas: presence of dust in small amount; nucleosynthesis signature and lack of H_2 molecules. The presence of H_2 molecules has been investigated in the course of a mini-survey with UVES at the VLT. The upper limits on the molecular fraction, f = 2N(H_2)/(2N(H_2)+N(HI)), derived in eight systems are in the range 1.2 ×10^-7 - 1.6 × 10^-5. There is no evidence in this sample for any

  7. High temperature, oxidation resistant noble metal-Al alloy thermocouple

    NASA Technical Reports Server (NTRS)

    Smialek, James L. (Inventor); Gedwill, Michael G. (Inventor)

    1994-01-01

    A thermocouple is disclosed. The thermocouple is comprised of an electropositive leg formed of a noble metal-Al alloy and an electronegative leg electrically joined to form a thermocouple junction. The thermocouple provides for accurate and reproducible measurement of high temperatures (600 - 1300 C) in inert, oxidizing or reducing environments, gases, or vacuum. Furthermore, the thermocouple circumvents the need for expensive, strategic precious metals such as rhodium as a constituent component. Selective oxidation of rhodium is also thereby precluded.

  8. Adhesion at metal interfaces

    NASA Technical Reports Server (NTRS)

    Banerjea, Amitava; Ferrante, John; Smith, John R.

    1991-01-01

    A basic adhesion process is defined, the theory of the properties influencing metallic adhesion is outlined, and theoretical approaches to the interface problem are presented, with emphasis on first-principle calculations as well as jellium-model calculations. The computation of the energies of adhesion as a function of the interfacial separation is performed; fully three-dimensional calculations are presented, and universality in the shapes of the binding energy curves is considered. An embedded-atom method and equivalent-crystal theory are covered in the framework of issues involved in practical adhesion.

  9. Metallic magnetic nanoparticles.

    PubMed

    Hernando, A; Crespo, P; García, M A

    2005-12-22

    In this paper, we reviewed some relevant aspects of the magnetic properties of metallic nanoparticles with small size (below 4 nm), covering the size effects in nanoparticles of magnetic materials, as well as the appearance of magnetism at the nanoscale in materials that are nonferromagnetic in bulk. These results are distributed along the text that has been organized around three important items: fundamental magnetic properties, different fabrication procedures, and characterization techniques. A general introduction and some experimental results recently obtained in Pd and Au nanoparticles have also been included. Finally, the more promising applications of magnetic nanoparticles in biomedicine are indicated. Special care was taken to complete the literature available on the subject.

  10. Novel Photocatalytic Metal Oxides

    SciTech Connect

    Smith, Robert W.; Mei, Wai-Ning; Sabirianov, Renat; Wang, Lu

    2012-08-31

    The principal short-term objective is to develop improved solid-state photocatalysts for the decomposition of water into hydrogen gas using ultraviolet and visible solar radiation. We will pursue our objective by modeling candidate metal oxides through computer simulations followed by synthesis of promising candidates. We will characterize samples through standard experimental techniques. The long-term objective is to provide a more efficient source of hydrogen gas for fixed-site hydrogen fuel cells, particularly for energy users in remote locations.

  11. Perforating Thin Metal Sheets

    NASA Technical Reports Server (NTRS)

    Davidson, M. E.

    1985-01-01

    Sheets only few mils thick bonded together, punched, then debonded. Three-step process yields perforated sheets of metal. (1): Individual sheets bonded together to form laminate. (2): laminate perforated in desired geometric pattern. (3): After baking, laminate separates into individual sheets. Developed for fabricating conductive layer on blankets that collect and remove ions; however, perforated foils have other applications - as conductive surfaces on insulating materials; stiffeners and conductors in plastic laminates; reflectors in antenna dishes; supports for thermal blankets; lightweight grille cover materials; and material for mockup of components.

  12. Fluorescent noble metal nanoclusters

    NASA Astrophysics Data System (ADS)

    Zheng, Jie

    Water-soluble fluorescent metallic clusters at sizes comparable to the Fermi wavelength of an electron (˜0.5 nm for gold and silver) were created and their photophysical properties were investigated at the bulk and single molecule levels. We employed biocompatible dendrimer and peptide to prepare a series of strong fluorescent gold and silver clusters with chemical or photo reduction methods. Facilitated by the well-defined dendrimer size, electrospray ionization mass spectrometry indicates that the fluorescent silver nanocluster size ranges from 2 to 8 Ag atoms. The correlation of emission energy with the number of atoms, N, in each gold nanocluster is quantitatively fit for the smallest nanoclusters with no adjustable parameters by the simple scaling relation of EFermi/N1/3, in which EFermi is the Fermi energy of bulk gold. The transition energy scaling inversely with cluster radius indicates that electronic structure can be well described with the spherical jellium model and further demonstrates that these nanomaterials are "multi-electron artificial atoms". Fluorescence from these small metal clusters can be considered protoplasmonic, molecular transitions of the free conduction electrons before the onset of collective dipole oscillations occurring when a continuous density of states is reached. In addition, very strong single molecular Stokes and anti-Stokes Raman enhancement by fluorescent silver clusters was observed. Pushing to larger sizes, we also created ˜2nm diameter glutathione encapsulated luminescent gold nanoparticles. Distinct from similarly sized but nonluminescent gold nanoparticles, these 2 nm gold nanoparticles show bright, long lifetime emission but no plasmon absorption. The emission might arise from charge transfer between gold atoms and the thiol ligand. Providing the "missing link" between atomic and nanoparticle behavior in noble metals, these highly fluorescent, water-soluble gold and silver nanoclusters offer complementary transition

  13. Metal nanoparticle inks

    DOEpatents

    Lewis, Jennifer A.; Ahn, Bok Yeop; Duoss, Eric B.

    2011-04-12

    Stabilized silver particles comprise particles comprising silver, a short-chain capping agent adsorbed on the particles, and a long-chain capping agent adsorbed on the particles. The short-chain capping agent is a first anionic polyelectrolyte having a molecular weight (Mw) of at most 10,000, and the long-chain capping agent is a second anionic polyelectrolyte having a molecular weight (Mw) of at least 25,000. The stabilized silver particles have a solid loading of metallic silver of at least 50 wt %.

  14. Metal/metal exothermic reactions induced by low velocity impact

    SciTech Connect

    Woody, D.L.; Davis, J.J.; Miller, P.J.

    1996-07-01

    This paper discusses experimental results from an effort conducted to discern the basic mechanism of reactions in porous metal/metal compositions under rapid plastic flow conditions. Small-scale impact tests were performed on various intermetallic mixtures: 3CuO + 2Al, Fe{sub 2}O{sub 3} + 2Al, Ni + Al, and 5Ti + 3Si. The addition of polytetrafluoroethylene (Teflon) to the metal/metal mixtures has been demonstrated to affect the extent of the reactions. Real-time emissivity and species evolution measurements of the reacting materials were used to discern the chemical reactions occurring under rapid plastic flow conditions.

  15. Anaerobes into heavy metal: Dissimilatory metal reduction in anoxic environments

    USGS Publications Warehouse

    Lovley, D.R.

    1993-01-01

    Within the last decade, a novel form of microbial metabolism of major environmental significance has been elucidated. In this process, known as dissimilatory metal reduction, specialized microorganisms, living in anoxic aquatic sediments and ground water, oxidize organic compounds to carbon dioxide with metals serving as the oxidant. Recent studies have demonstrated that this metabolism explains a number of important geochemical phenomena in ancient and modern sedimentary environments, affecting not only the cycling of metals but also the fate of organic matter. Furthermore, this metabolism may have practical application in remediation of environments contaminated with toxic metals and/or organics.

  16. Metal-metal multiply bonded complexes of technetium. Final report

    SciTech Connect

    Cotton, F.A.; Haefner, S.C.

    1995-03-30

    The primary objective of this project was to explore and develop the area of technetium metal-metal multiple bond chemistry. At the outset of the project, examples of metal-metal multiply bonded complexes of technetium were primarily limited to those supported by halide and carboxylate ligands. As a result, we intended to significantly expand the number of complexes containing Tc-Tc multiple bonds using ligands other than carboxylates or halides. In order to achieve this goal, the results obtained from years of dirhenium research was used as a guide for the development of new technetium compounds. Our emphasis, however, was on pursuing unanticipated results and exploiting the inherent differences between technetium and rhenium in order to develop chemistry beyond that which exists for rhenium. We have focused our attention on the preparation of dinuclear complexes with ligand sets that are known to support dinuclear metal-metal bonded cores in a variety of different metal oxidation states. Investigation of the consequences of electron addition and removal from metal-metal bonding manifold on the structural and physical properties of such dinuclear species will provide vital information regarding the electronic structure of Tc-Tc multiply bonded compounds.

  17. Enhanced rectifying response from metal-insulator-insulator-metal junctions

    NASA Astrophysics Data System (ADS)

    Maraghechi, P.; Foroughi-Abari, A.; Cadien, K.; Elezzabi, A. Y.

    2011-12-01

    We present on a metal-insulator-insulator-metal quantum electronic tunneling devices suitable for high speed rectifiers. Through the introduction of double oxide layer between similar metallic electrodes, a cascaded potential barrier is formed which alters the electron tunneling mechanism at forward versus the reverse bias. The cascaded potential barrier engineering manifests itself in both a highly nonlinear and asymmetric I-V junction characteristic. It is envisioned that high speed rectifiers and mixers having extraordinary nonlinearity can be realized through the incorporation of the cascaded potential barrier architecture and dissimilar metallic electrodes.

  18. Antimicrobial activity of the metals and metal oxide nanoparticles.

    PubMed

    Dizaj, Solmaz Maleki; Lotfipour, Farzaneh; Barzegar-Jalali, Mohammad; Zarrintan, Mohammad Hossein; Adibkia, Khosro

    2014-11-01

    The ever increasing resistance of pathogens towards antibiotics has caused serious health problems in the recent years. It has been shown that by combining modern technologies such as nanotechnology and material science with intrinsic antimicrobial activity of the metals, novel applications for these substances could be identified. According to the reports, metal and metal oxide nanoparticles represent a group of materials which were investigated in respect to their antimicrobial effects. In the present review, we focused on the recent research works concerning antimicrobial activity of metal and metal oxide nanoparticles together with their mechanism of action. Reviewed literature indicated that the particle size was the essential parameter which determined the antimicrobial effectiveness of the metal nanoparticles. Combination therapy with the metal nanoparticles might be one of the possible strategies to overcome the current bacterial resistance to the antibacterial agents. However, further studies should be performed to minimize the toxicity of metal and metal oxide nanoparticles to apply as proper alternatives for antibiotics and disinfectants especially in biomedical applications. PMID:25280707

  19. Photoelectrochemical detection of metal ions.

    PubMed

    Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-07-21

    Depending on the situation, metal ions may either play beneficial roles or be harmful to human health and ecosystems. Sensitive and accurate detection of metal ions is thus a critical issue in the field of analytical sciences and great efforts have been devoted to the development of various metal ion sensors. Photoelectrochemical (PEC) detection is an emerging technique for the bio/chemical detection of metal ions, and features a fast response, low cost and high sensitivity. Using representative examples, this review will first introduce the fundamentals and summarize recent progress in the PEC detection of metal ions. In addition, interesting strategies for the design of particular PEC metal ion sensors are discussed. Challenges and opportunities in this field are also presented. PMID:27297834

  20. Metal speciation by Donnan dialysis

    SciTech Connect

    Cox, J.A.; Slonawska, K.; Gatchell, D.K.; Hiebert, A.G.

    1984-04-01

    In Donnan dialysis aqueous samples are separated from receiver electrolytes by an ion exchange membrane. The present work demonstrates that the dialysis of metals into salt solutions occurs in proportion to the sum of the concentrations of the free metal and the metal held in the form of labile complexes; however, with strongly acidic or chelating receivers, the dialysis occurs in proportion to the total soluble metal. Hence, Donnan dialysis provides the basis for a rapid estimation of the total soluble (i.e., free plus labile complexed) metal and nonlabile-complexed metal. The method is demonstrated with Pb, Zn, Cu, and Cd complexes of glycine, humic acid, and nitrilotriacetic acid and is applied to a lake water sample. The results are compared to values obtained from an established approach that utilizes stripping voltammetry and separations with a chelating ion exchange resin.

  1. Supported molten-metal catalysts

    DOEpatents

    Datta, Ravindra; Singh, Ajeet; Halasz, Istvan; Serban, Manuela

    2001-01-01

    An entirely new class of catalysts called supported molten-metal catalysts, SMMC, which can replace some of the existing precious metal catalysts used in the production of fuels, commodity chemicals, and fine chemicals, as well as in combating pollution. SMMC are based on supporting ultra-thin films or micro-droplets of the relatively low-melting (<600.degree. C.), inexpensive, and abundant metals and semimetals from groups 1, 12, 13, 14, 15 and 16, of the periodic table, or their alloys and intermetallic compounds, on porous refractory supports, much like supported microcrystallites of the traditional solid metal catalysts. It thus provides orders of magnitude higher surface area than is obtainable in conventional reactors containing molten metals in pool form and also avoids corrosion. These have so far been the chief stumbling blocks in the application of molten metal catalysts.

  2. Metal to ceramic sealed joint

    DOEpatents

    Lasecki, J.V.; Novak, R.F.; McBride, J.R.

    1991-08-27

    A metal to ceramic sealed joint which can withstand wide variations in temperature and maintain a good seal is provided for use in a device adapted to withstand thermal cycling from about 20 to about 1000 degrees C. The sealed joint includes a metal member, a ceramic member having an end portion, and an active metal braze forming a joint to seal the metal member to the ceramic member. The joint is positioned remote from the end portion of the ceramic member to avoid stresses at the ends or edges of the ceramic member. The sealed joint is particularly suited for use to form sealed metal to ceramic joints in a thermoelectric generator such as a sodium heat engine where a solid ceramic electrolyte is joined to metal parts in the system. 11 figures.

  3. Metal to ceramic sealed joint

    DOEpatents

    Lasecki, John V.; Novak, Robert F.; McBride, James R.

    1991-01-01

    A metal to ceramic sealed joint which can withstand wide variations in temperature and maintain a good seal is provided for use in a device adapted to withstand thermal cycling from about 20 to about 1000 degrees C. The sealed joint includes a metal member, a ceramic member having an end portion, and an active metal braze forming a joint to seal the metal member to the ceramic member. The joint is positioned remote from the end portion of the ceramic member to avoid stresses at the ends or edges of the ceramic member. The sealed joint is particularly suited for use to form sealed metal to ceramic joints in a thermoelectric generator such as a sodium heat engine where a solid ceramic electrolyte is joined to metal parts in the system.

  4. Metals removal from spent salts

    DOEpatents

    Hsu, Peter C.; Von Holtz, Erica H.; Hipple, David L.; Summers, Leslie J.; Brummond, William A.; Adamson, Martyn G.

    2002-01-01

    A method and apparatus for removing metal contaminants from the spent salt of a molten salt oxidation (MSO) reactor is described. Spent salt is removed from the reactor and analyzed to determine the contaminants present and the carbonate concentration. The salt is dissolved in water, and one or more reagents may be added to precipitate the metal oxide and/or the metal as either metal oxide, metal hydroxide, or as a salt. The precipitated materials are filtered, dried and packaged for disposal as waste or can be immobilized as ceramic pellets. More than about 90% of the metals and mineral residues (ashes) present are removed by filtration. After filtration, salt solutions having a carbonate concentration >20% can be spray-dried and returned to the reactor for re-use. Salt solutions containing a carbonate concentration <20% require further clean-up using an ion exchange column, which yields salt solutions that contain less than 1.0 ppm of contaminants.

  5. Degenerate doping of metallic anodes

    DOEpatents

    Friesen, Cody A; Zeller, Robert A; Johnson, Paul B; Switzer, Elise E

    2015-05-12

    Embodiments of the invention relate to an electrochemical cell comprising: (i) a fuel electrode comprising a metal fuel, (ii) a positive electrode, (iii) an ionically conductive medium, and (iv) a dopant; the electrodes being operable in a discharge mode wherein the metal fuel is oxidized at the fuel electrode and the dopant increases the conductivity of the metal fuel oxidation product. In an embodiment, the oxidation product comprises an oxide of the metal fuel which is doped degenerately. In an embodiment, the positive electrode is an air electrode that absorbs gaseous oxygen, wherein during discharge mode, oxygen is reduced at the air electrode. Embodiments of the invention also relate to methods of producing an electrode comprising a metal and a doped metal oxidation product.

  6. Magnetic metallic multilayers

    SciTech Connect

    Hood, R.Q.

    1994-04-01

    Utilizing self-consistent Hartree-Fock calculations, several aspects of multilayers and interfaces are explored: enhancement and reduction of the local magnetic moments, magnetic coupling at the interfaces, magnetic arrangements within each film and among non-neighboring films, global symmetry of the systems, frustration, orientation of the various moments with respect to an outside applied field, and magnetic-field induced transitions. Magnetoresistance of ferromagnetic-normal-metal multilayers is found by solving the Boltzmann equation. Results explain the giant negative magnetoresistance encountered in these systems when an initial antiparallel arrangement is changed into a parallel configuration by an external magnetic field. The calculation depends on (1) geometric parameters (thicknesses of layers), (2) intrinsic metal parameters (number of conduction electrons, magnetization, and effective masses in layers), (3) bulk sample properties (conductivity relaxation times), (4) interface scattering properties (diffuse scattering versus potential scattering at the interfaces, and (5) outer surface scattering properties (specular versus diffuse surface scattering). It is found that a large negative magnetoresistance requires considerable asymmetry in interface scattering for the two spin orientations. Features of the interfaces that may produce an asymmetrical spin-dependent scattering are studied: varying interfacial geometric random roughness with no lateral coherence, correlated (quasi-periodic) roughness, and varying chemical composition of the interfaces. The interplay between these aspects of the interfaces may enhance or suppress the magnetoresistance, depending on whether it increases or decreases the asymmetry in the spin-dependent scattering of the conduction electrons.

  7. Lanthanides: New life metals?

    PubMed

    Chistoserdova, Ludmila

    2016-08-01

    Lanthanides (Ln(3+)) that are Rare Earth Elements, until recently thought to be biologically inert, have recently emerged as essential metals for activity and expression of a special type of methanol dehydrogenase, XoxF. As XoxF enzyme homologs are encoded in a wide variety of microbes, including microbes active in important environmental processes such as methane and methanol metabolism, Ln(3+) may represent some of the key biogeochemical drivers in cycling of carbon and other elements. However, significant gaps in understanding the role of Ln(3+) in biological systems remain as the functions of most of the proteins potentially dependent of Ln(3+) and their roles in specific metabolic networks/respective biogeochemical cycles remain unknown. Moreover, enzymes dependent on Ln(3+) but not related to XoxF enzymes may exist, and these so far have not been recognized. Through connecting the recently uncovered genetic divergence and phylogenetic distribution of XoxF-like enzymes and through elucidation of their activities, metal and substrate specificities, along with the biological contexts of respective biochemical pathways, most parsimonious scenarios for their evolution could be uncovered. Generation of such data will firmly establish the role of Ln(3+) in the biochemistry of Life inhabiting this planet. PMID:27357406

  8. Metallic threaded composite fastener

    NASA Technical Reports Server (NTRS)

    Dunn, Thomas J. (Inventor)

    1992-01-01

    A metallic threaded composite fastener, particularly suited for high temperature applications, has a body member made of high temperature resistant composite material with a ceramic coating. The body member has a head portion configured to be installed in a countersunk hole and a shank portion which is noncircular and tapered. One part of the shank may be noncircular and the other part tapered, or the two types of surface could be combined into a frustum of a noncircular cone. A split collar member made of high strength, high temperature tolerant metal alloy is split into two halves and the interior of the halves are configured to engage the shank. The exterior of the collar has a circumferential groove which receives a lock ring to secure the collar halves to the shank. In the assembled condition torque may be transmitted from the body to the split collar by the engaged noncircular portions to install and remove the fastener assembly into or from a threaded aperture and shear loads in the collar threads are transferred to the shank tapered portion as a combination of radial compression and axial tension loads. Thus, tension loads may be applied to the fastener shank without damaging the ceramic coating.

  9. ``Towards Strange Metallic Holography'

    SciTech Connect

    Hartnoll, Sean A.; Polchinski, Joseph; Silverstein, Eva; Tong, David; /Cambridge U., DAMTP /Santa Barbara, KITP /UC, Santa Barbara

    2010-08-26

    We initiate a holographic model building approach to 'strange metallic' phenomenology. Our model couples a neutral Lifshitz-invariant quantum critical theory, dual to a bulk gravitational background, to a finite density of gapped probe charge carriers, dually described by D-branes. In the physical regime of temperature much lower than the charge density and gap, we exhibit anomalous scalings of the temperature and frequency dependent conductivity. Choosing the dynamical critical exponent z appropriately we can match the non-Fermi liquid scalings, such as linear resistivity, observed in strange metal regimes. As part of our investigation we outline three distinct string theory realizations of Lifshitz geometries: from F theory, from polarized branes, and from a gravitating charged Fermi gas. We also identify general features of renormalization group flow in Lifshitz theories, such as the appearance of relevant charge-charge interactions when z {ge} 2. We outline a program to extend this model building approach to other anomalous observables of interest such as the Hall conductivity.

  10. Clean Metal Casting

    SciTech Connect

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The objective of this project is to develop a technology for clean metal processing that is capable of consistently providing a metal cleanliness level that is fit for a given application. The program has five tasks: Development of melt cleanliness assessment technology, development of melt contamination avoidance technology, development of high temperature phase separation technology, establishment of a correlation between the level of melt cleanliness and as cast mechanical properties, and transfer of technology to the industrial sector. Within the context of the first task, WPI has developed a standardized Reduced Pressure Test that has been endorsed by AFS as a recommended practice. In addition, within the context of task1, WPI has developed a melt cleanliness sensor based on the principles of electromagnetic separation. An industrial partner is commercializing the sensor. Within the context of the second task, WPI has developed environmentally friendly fluxes that do not contain fluorine. Within the context of the third task, WPI modeled the process of rotary degassing and verified the model predictions with experimental data. This model may be used to optimize the performance of industrial rotary degassers. Within the context of the fourth task, WPI has correlated the level of melt cleanliness at various foundries, including a sand casting foundry, a permanent mold casting foundry, and a die casting foundry, to the casting process and the resultant mechanical properties. This is useful in tailoring the melt cleansing operations at foundries to the particular casting process and the desired properties of cast components.

  11. Twisting of sheet metals

    NASA Astrophysics Data System (ADS)

    Pham, C. H.; Thuillier, S.; Manach, P. Y.

    2013-12-01

    Twisting of metallic sheets is one particular mode of springback that occurs after drawing of elongated parts, i.e. with one dimension much larger than the two others. In this study, a dedicated device for drawing of elongated part with a U-shaped section has been designed on purpose, in order to obtain reproducible data. Very thin metallic sheet, of thickness 0.15 mm, has been used, so that the maximum length of the part is 100 mm. Two different orientations of the part with respect to the tools have been chosen: either aligned with the tools, or purposefully misaligned by 2°. Several samples were drawn for each configuration, leading to the conclusion that almost no twisting occurs in the first case whereas a significant one can be measured for the second one. In a second step, 2D and 3D numerical simulations within the implicit framework for drawing and springback were carried out. A mixed hardening law associated to von Mises yield criterion represents accurately the mechanical behavior of the material. This paper highlights a comparison of numerical predictions with experiments, e.g. the final shape of the part and the twisting parameter.

  12. Nodal-chain metals

    NASA Astrophysics Data System (ADS)

    Bzdušek, Tomáš; Wu, Quansheng; Rüegg, Andreas; Sigrist, Manfred; Soluyanov, Alexey A.

    2016-10-01

    The band theory of solids is arguably the most successful theory of condensed-matter physics, providing a description of the electronic energy levels in various materials. Electronic wavefunctions obtained from the band theory enable a topological characterization of metals for which the electronic spectrum may host robust, topologically protected, fermionic quasiparticles. Many of these quasiparticles are analogues of the elementary particles of the Standard Model, but others do not have a counterpart in relativistic high-energy theories. A complete list of possible quasiparticles in solids is lacking, even in the non-interacting case. Here we describe the possible existence of a hitherto unrecognized type of fermionic excitation in metals. This excitation forms a nodal chain—a chain of connected loops in momentum space—along which conduction and valence bands touch. We prove that the nodal chain is topologically distinct from previously reported excitations. We discuss the symmetry requirements for the appearance of this excitation and predict that it is realized in an existing material, iridium tetrafluoride (IrF4), as well as in other compounds of this class of materials. Using IrF4 as an example, we provide a discussion of the topological surface states associated with the nodal chain. We argue that the presence of the nodal-chain fermions will result in anomalous magnetotransport properties, distinct from those of materials exhibiting previously known excitations.

  13. First pentahaptofullerene metal complexes

    SciTech Connect

    Masaya, Sawamura; Iikura, Hitoshi; Nakamura, Eiichi

    1996-12-18

    Cyclopentadienyl metal complexes have played important roles in chemistry owing to their unique structures and functional activities. Here we report the synthesis and characterization of an entirely new class of cyclopentadienyl (Cp) metal complexes ({eta}{sup 5}-C{sub 60}Ph{sub 5})MLn (MLn = Li, K, Tl, and Cu.PEt{sub 3}). In these molecules, the five Cp carbons represent one pentagon of C{sub 60}, isolated from the remaining 50 sp{sup 2} carbon atoms by five surrounding sp{sup 3} carbon atoms each bearing a phenyl group. The X-ray crystal structure analysis of the thallium complex Tl({eta}{sup 5}-C{sub 60}Ph{sub 5}).2.5THF revealed its unique and esthetically pleasing C{sub 5} symmetrical molecular structure with the phenyl groups forming a chiral propeller array. The thallium atom is deeply buried in the cavity created by the phenyl groups, bonding to the five Cp carbons ({eta}{sup 5}-coordination) with an averaged Tl-C distance of 2.87 A. The key finding that we made in this research was a remarkable 5-fold addition of an organocopper reagent to C{sub 60}, which stands in contrast to the monoaddition reaction of Grignard or organolithium reagents. 10 refs., 1 fig.

  14. Sinuous flow in metals

    PubMed Central

    Yeung, Ho; Viswanathan, Koushik; Compton, Walter Dale; Chandrasekar, Srinivasan

    2015-01-01

    Annealed metals are surprisingly difficult to cut, involving high forces and an unusually thick “chip.” This anomaly has long been explained, based on ex situ observations, using a model of smooth plastic flow with uniform shear to describe material removal by chip formation. Here we show that this phenomenon is actually the result of a fundamentally different collective deformation mode—sinuous flow. Using in situ imaging, we find that chip formation occurs via large-amplitude folding, triggered by surface undulations of a characteristic size. The resulting fold patterns resemble those observed in geophysics and complex fluids. Our observations establish sinuous flow as another mesoscopic deformation mode, alongside mechanisms such as kinking and shear banding. Additionally, by suppressing the triggering surface undulations, sinuous flow can be eliminated, resulting in a drastic reduction of cutting forces. We demonstrate this suppression quite simply by the application of common marking ink on the free surface of the workpiece material before the cutting. Alternatively, prehardening a thin surface layer of the workpiece material shows similar results. Besides obvious implications to industrial machining and surface generation processes, our results also help unify a number of disparate observations in the cutting of metals, including the so-called Rehbinder effect. PMID:26216980

  15. MetalS(3), a database-mining tool for the identification of structurally similar metal sites.

    PubMed

    Valasatava, Yana; Rosato, Antonio; Cavallaro, Gabriele; Andreini, Claudia

    2014-08-01

    We have developed a database search tool to identify metal sites having structural similarity to a query metal site structure within the MetalPDB database of minimal functional sites (MFSs) contained in metal-binding biological macromolecules. MFSs describe the local environment around the metal(s) independently of the larger context of the macromolecular structure. Such a local environment has a determinant role in tuning the chemical reactivity of the metal, ultimately contributing to the functional properties of the whole system. The database search tool, which we called MetalS(3) (Metal Sites Similarity Search), can be accessed through a Web interface at http://metalweb.cerm.unifi.it/tools/metals3/ . MetalS(3) uses a suitably adapted version of an algorithm that we previously developed to systematically compare the structure of the query metal site with each MFS in MetalPDB. For each MFS, the best superposition is kept. All these superpositions are then ranked according to the MetalS(3) scoring function and are presented to the user in tabular form. The user can interact with the output Web page to visualize the structural alignment or the sequence alignment derived from it. Options to filter the results are available. Test calculations show that the MetalS(3) output correlates well with expectations from protein homology considerations. Furthermore, we describe some usage scenarios that highlight the usefulness of MetalS(3) to obtain mechanistic and functional hints regardless of homology.

  16. Metals extraction from sea water

    SciTech Connect

    Chryssostomidis, C.; Larue, G.J.; Morgan, D.T.

    1981-10-06

    A method and system for continuously extracting metals from sea water by deploying adsorber sheets in a suitable current of sea water, recovering the adsorber sheets after they become loaded with metal and eluting the metal from the recovered sheets. The system involves the use of hollow, perforated bobbins on which the sheets are rolled as they are recovered and through which elutant is introduced.

  17. Metal-ceramic joint assembly

    DOEpatents

    Li, Jian

    2002-01-01

    A metal-ceramic joint assembly in which a brazing alloy is situated between metallic and ceramic members. The metallic member is either an aluminum-containing stainless steel, a high chromium-content ferritic stainless steel or an iron nickel alloy with a corrosion protection coating. The brazing alloy, in turn, is either an Au-based or Ni-based alloy with a brazing temperature in the range of 9500 to 1200.degree. C.

  18. Corrosion-resistant metal surfaces

    DOEpatents

    Sugama, Toshifumi

    2009-03-24

    The present invention relates to metal surfaces having thereon an ultrathin (e.g., less than ten nanometer thickness) corrosion-resistant film, thereby rendering the metal surfaces corrosion-resistant. The corrosion-resistant film includes an at least partially crosslinked amido-functionalized silanol component in combination with rare-earth metal oxide nanoparticles. The invention also relates to methods for producing such corrosion-resistant films.

  19. Potential use of metal hyperaccumulators

    SciTech Connect

    Chaney, R.; Li, Yin-Ming; Green, C.

    1996-12-31

    Experiments involving biological accumulation of metal contaminants are summarized in the article. The focus is on identification of hyperaccumulating plant species for cadmium and zinc. Two of the studies examined Thlaspi caerulescens (alpine pennycress) as a bioadsorbent; the third study compared different species of Thlaspi. The T. caerulescens accumulated both metals, but with low yields. Other plant species were identified which adsorbed cadmium or zinc, but not both metals.

  20. Electronic structure of metallic glasses

    SciTech Connect

    Oelhafen, P.; Lapka, R.; Gubler, U.; Krieg, J.; DasGupta, A.; Guentherodt, H.J.; Mizoguchi, T.; Hague, C.; Kuebler, J.; Nagel, S.R.

    1981-01-01

    This paper is organized in six sections and deals with (1) the glassy transition metal alloys, their d-band structure, the d-band shifts on alloying and their relation to the alloy heat of formation (..delta..H) and the glass forming ability, (2) the glass to crystal phase transition viewed by valence band spectroscopy, (3) band structure calculations, (4) metallic glasses prepared by laser glazing, (5) glassy normal metal alloys, and (6) glassy hydrides.

  1. Metal-ion recycle technology for metal electroplating waste waters

    SciTech Connect

    Sauer, N.N.; Smith, B.F.

    1993-06-01

    As a result of a collaboration with Boeing Aerospace, the authors have begun a program to identify suitable treatments or to develop new treatments for electroplating baths. The target baths are mixed-metal or alloy baths that are being integrated into the Boeing electroplating complex. These baths, which are designed to replace highly toxic chromium and cadmium baths, contain mixtures of two metals, either nickel-tungsten, nickel-zinc, or zinc-tin. This report reviews the literature and details currently available on emerging technologies that could affect recovery of metals from electroplating baths under development by Boeing Aerospace. This literature survey summarizes technologies relevant to the recovery of metals from electroplating processes. The authors expanded the scope to investigate single metal ion recovery technologies that could be applied to metal ion recovery from alloy baths. This review clearly showed that the electroplating industry has traditionally relied on precipitation and more recently on electrowinning as its waste treatment methods. Despite the almost ubiquitous use of precipitation to remove contaminant metal ions from waste electroplating baths and rinse waters, this technology is clearly no longer feasible for the electroplating industry for several reasons. First, disposal of unstabilized sludge is no longer allowed by law. Second, these methods are no longer adequate as metal-removal techniques because they cannot meet stringent new metal discharge limits. Third, precious resources are being wasted or discarded because these methods do not readily permit recovery of the target metal ions. As a result, emerging technologies for metal recovery are beginning to see application to electroplating waste recycle. This report summarizes current research in these areas. Included are descriptions of various membrane technologies, such as reverse osmosis and ultrafiltration, ion exchange and chelating polymer technology, and electrodialysis.

  2. SOLDERING OF ALUMINUM BASE METALS

    DOEpatents

    Erickson, G.F.

    1958-02-25

    This patent deals with the soldering of aluminum to metals of different types, such as copper, brass, and iron. This is accomplished by heating the aluminum metal to be soldered to slightly above 30 deg C, rubbing a small amount of metallic gallium into the part of the surface to be soldered, whereby an aluminum--gallium alloy forms on the surface, and then heating the aluminum piece to the melting point of lead--tin soft solder, applying lead--tin soft solder to this alloyed surface, and combining the aluminum with the other metal to which it is to be soldered.

  3. Antimicrobial Polymers with Metal Nanoparticles

    PubMed Central

    Palza, Humberto

    2015-01-01

    Metals, such as copper and silver, can be extremely toxic to bacteria at exceptionally low concentrations. Because of this biocidal activity, metals have been widely used as antimicrobial agents in a multitude of applications related with agriculture, healthcare, and the industry in general. Unlike other antimicrobial agents, metals are stable under conditions currently found in the industry allowing their use as additives. Today these metal based additives are found as: particles, ions absorbed/exchanged in different carriers, salts, hybrid structures, etc. One recent route to further extend the antimicrobial applications of these metals is by their incorporation as nanoparticles into polymer matrices. These polymer/metal nanocomposites can be prepared by several routes such as in situ synthesis of the nanoparticle within a hydrogel or direct addition of the metal nanofiller into a thermoplastic matrix. The objective of the present review is to show examples of polymer/metal composites designed to have antimicrobial activities, with a special focus on copper and silver metal nanoparticles and their mechanisms. PMID:25607734

  4. Metal deposition using seed layers

    DOEpatents

    Feng, Hsein-Ping; Chen, Gang; Bo, Yu; Ren, Zhifeng; Chen, Shuo; Poudel, Bed

    2013-11-12

    Methods of forming a conductive metal layers on substrates are disclosed which employ a seed layer to enhance bonding, especially to smooth, low-roughness or hydrophobic substrates. In one aspect of the invention, the seed layer can be formed by applying nanoparticles onto a surface of the substrate; and the metallization is achieved by electroplating an electrically conducting metal onto the seed layer, whereby the nanoparticles serve as nucleation sites for metal deposition. In another approach, the seed layer can be formed by a self-assembling linker material, such as a sulfur-containing silane material.

  5. The biogeochemistry of metal cycling

    NASA Technical Reports Server (NTRS)

    Nealson, Kenneth H. (Editor); Nealson, Molly (Editor); Dutcher, F. Ronald (Editor)

    1990-01-01

    The results of the Planetary Biology and Microbial Ecology's summer 1987 program are summarized. The purpose of the interdisciplinary PBME program is to integrate, via lectures and laboratory work, the contributions of university and NASA scientists and student interns. The 1987 program examined various aspects of the biogeochemistry of metal cycling, and included such areas as limnology, metal chemistry, metal geochemistry, microbial ecology, and interactions with metals. A particular area of focus was the use of remote sensing in the study of biogeochemistry. Abstracts and bibliographies of the lectures and reports of the laboratory projects are presented.

  6. Metallic coating reduces thermal stress

    NASA Technical Reports Server (NTRS)

    Morgan, R. D.

    1977-01-01

    Addition of metallic outer layer deposited by standard plating method, having high thermal conductivity, substantially reduces thermal stress in high-temperature/high-strength materials, preventing structural overloads.

  7. Alkali metal ion battery with bimetallic electrode

    SciTech Connect

    Boysen, Dane A; Bradwell, David J; Jiang, Kai; Kim, Hojong; Ortiz, Luis A; Sadoway, Donald R; Tomaszowska, Alina A; Wei, Weifeng; Wang, Kangli

    2015-04-07

    Electrochemical cells having molten electrodes having an alkali metal provide receipt and delivery of power by transporting atoms of the alkali metal between electrode environments of disparate chemical potentials through an electrochemical pathway comprising a salt of the alkali metal. The chemical potential of the alkali metal is decreased when combined with one or more non-alkali metals, thus producing a voltage between an electrode comprising the molten the alkali metal and the electrode comprising the combined alkali/non-alkali metals.

  8. Method for preparing porous metal hydride compacts

    DOEpatents

    Ron, Moshe; Gruen, Dieter M.; Mendelsohn, Marshall H.; Sheft, Irving

    1981-01-01

    A method for preparing porous metallic-matrix hydride compacts which can be repeatedly hydrided and dehydrided without disintegration. A mixture of a finely divided metal hydride and a finely divided matrix metal is contacted with a poison which prevents the metal hydride from dehydriding at room temperature and atmospheric pressure. The mixture of matrix metal and poisoned metal hydride is then compacted under pressure at room temperature to form porous metallic-matrix hydride compacts.

  9. Method for preparing porous metal hydride compacts

    DOEpatents

    Ron, M.; Gruen, D.M.; Mendelsohn, M.H.; Sheft, I.

    1980-01-21

    A method for preparing porous metallic-matrix hydride compacts which can be repeatedly hydrided and dehydrided without disintegration. A mixture of a finely divided metal hydride and a finely divided matrix metal is contacted with a poison which prevents the metal hydride from dehydriding at room temperature and atmospheric pressure. The mixture of matrix metal and poisoned metal hydride is then compacted under pressure at room temperature to form porous metallic-matrix hydride compacts.

  10. Metal decontamination for waste minimization using liquid metal refining technology

    SciTech Connect

    Joyce, E.L. Jr.; Lally, B.; Ozturk, B.; Fruehan, R.J.

    1993-09-01

    The current Department of Energy Mixed Waste Treatment Project flowsheet indicates that no conventional technology, other than surface decontamination, exists for metal processing. Current Department of Energy guidelines require retrievable storage of all metallic wastes containing transuranic elements above a certain concentration. This project is in support of the National Mixed Low Level Waste Treatment Program. Because of the high cost of disposal, it is important to develop an effective decontamination and volume reduction method for low-level contaminated metals. It is important to be able to decontaminate complex shapes where surfaces are hidden or inaccessible to surface decontamination processes and destruction of organic contamination. These goals can be achieved by adapting commercial metal refining processes to handle radioactive and organic contaminated metal. The radioactive components are concentrated in the slag, which is subsequently vitrified; hazardous organics are destroyed by the intense heat of the bath. The metal, after having been melted and purified, could be recycled for use within the DOE complex. In this project, we evaluated current state-of-the-art technologies for metal refining, with special reference to the removal of radioactive contaminants and the destruction of hazardous organics. This evaluation was based on literature reports, industrial experience, plant visits, thermodynamic calculations, and engineering aspects of the various processes. The key issues addressed included radioactive partitioning between the metal and slag phases, minimization of secondary wastes, operability of the process subject to widely varying feed chemistry, and the ability to seal the candidate process to prevent the release of hazardous species.

  11. Making A Noble-Metal-On-Metal-Oxide Catalyst

    NASA Technical Reports Server (NTRS)

    Miller, Irvin M.; Davis, Patricia P.; Upchurch, Billy T.

    1989-01-01

    Catalyst exhibits superior performance in oxidation of CO in CO2 lasers. Two-step process developed for preparing platinum- or palladium-on-tin-oxide catalyst for recombination of CO and O2, decomposition products that occur in high-voltage discharge region of closed-cycle CO2 laser. Process also applicable to other noble-metal/metal-oxide combinations.

  12. Development of techniques for processing metal-metal oxide systems

    NASA Technical Reports Server (NTRS)

    Johnson, P. C.

    1976-01-01

    Techniques for producing model metal-metal oxide systems for the purpose of evaluating the results of processing such systems in the low-gravity environment afforded by a drop tower facility are described. Because of the lack of success in producing suitable materials samples and techniques for processing in the 3.5 seconds available, the program was discontinued.

  13. Interplay of metal-allyl and metal-metal bonding in dimolybdenum allyl complexes.

    SciTech Connect

    Trovitch, R. J.; John, K. D.; Martin, R. L.; Obrey, S. J.; Sattelberger, A. P.; Scott, B. L.; Baker, R. T.; LANL; Univ. of Ottawa

    2009-01-01

    Addition of PMe{sub 3} to Mo{sub 2}(allyl){sub 4} afforded Mo{sub 2}(allyl){sub 4}(PMe{sub 3}){sub 2}, in which two of the allyl groups adopt an unprecedented {mu}{sub 2}-{eta}{sup 1}, {eta}{sup 3} bonding mode; theoretical studies elucidate the roles of the {sigma}- and {pi}-donor ligands in the interplay of metal-allyl and metal-metal bonding.

  14. Liquid metal embrittlement. [crack propagation in metals with liquid metal in crack space

    NASA Technical Reports Server (NTRS)

    Tiller, W. A.

    1973-01-01

    Crack propagation is discussed for metals with liquid metal in the crack space. The change in electrochemical potential of an electron in a metal due to changes in stress level along the crack surface was investigated along with the change in local chemistry, and interfacial energy due to atomic redistribution in the liquid. Coupled elastic-elastrostatic equations, stress effects on electron energy states, and crack propagation via surface roughening are discussed.

  15. Interplay of metal-allyl and metal-metal bonding in dimolybdenum allyl complexes

    SciTech Connect

    John, Kevin D; Martin, Richard L; Obrey, Steven J; Scott, Brian L

    2008-01-01

    Addition of PMe{sub 3} to Mo{sub 2}(allyl){sub 4} afforded Mo{sub 2}(allyl){sub 4}(PMe{sub 3}){sub 2}, in which two of the allyl groups adopt an unprecedented {mu}{sub 2{sup -}}{eta}{sup 1}, {eta}{sup 3} bonding mode; theoretical studies elucidate the role sof the {sigma}- and {pi}-donor ligands in the interplay of metal-allyl and metal-metal bonding.

  16. Catalytic production of metal carbonyls from metal oxides

    DOEpatents

    Sapienza, R.S.; Slegeir, W.A.; Foran, M.T.

    1984-01-06

    This invention relates to the formation of metal carbonyls from metal oxides and specially the formation of molybdenum carbonyl and iron carbonyl from their respective oxides. Copper is used here in admixed form or used in chemically combined form as copper molybdate. The copper/metal oxide combination or combined copper is utilized with a solvent, such as toluene and subjected to carbon monoxide pressure of 25 atmospheres or greater at about 150 to 260/sup 0/C. The reducing metal copper is employed in catalytic concentrations or combined concentrations as CuMoO/sub 4/ and both hydrogen and water present serve as promoters. It has been found that the yields by this process have been salutary and that additionally the catalytic metal may be reused in the process to good effect. 3 tables.

  17. Catalytic production of metal carbonyls from metal oxides

    DOEpatents

    Sapienza, Richard S.; Slegeir, William A.; Foran, Michael T.

    1984-01-01

    This invention relates to the formation of metal carbonyls from metal oxides and specially the formation of molybdenum carbonyl and iron carbonyl from their respective oxides. Copper is used here in admixed form or used in chemically combined form as copper molybdate. The copper/metal oxide combination or combined copper is utilized with a solvent, such as toluene and subjected to carbon monoxide pressure of 25 atmospheres or greater at about 150.degree.-260.degree. C. The reducing metal copper is employed in catalytic concentrations or combined concentrations as CuMoO.sub.4 and both hydrogen and water present serve as promoters. It has been found that the yields by this process have been salutary and that additionally the catalytic metal may be reused in the process to good effect.

  18. Metal sulfide initiators for metal oxide sorbent regeneration

    DOEpatents

    Turk, B.S.; Gupta, R.P.

    1999-06-22

    A process of regenerating a sulfided sorbent is provided. According to the process of the invention, a substantial portion of the energy necessary to initiate the regeneration reaction is provided by the combustion of a particulate metal sulfide additive. In using the particulate metal sulfide additive, the oxygen-containing gas used to regenerate the sulfided sorbent can be fed to the regeneration zone without heating or at a lower temperature than used in conventional processes wherein the regeneration reaction is initiated only by heating the oxygen-containing gas. The particulate metal sulfide additive is preferably an inexpensive mineral ore such as iron pyrite which does not adversely affect the regeneration or corresponding desulfurization reactions. The invention further includes a sorbent composition comprising the particulate metal sulfide additive in admixture with an active metal oxide sorbent capable of removing one or more sulfur compounds from a sulfur-containing gas stream. 1 fig.

  19. Metal sulfide initiators for metal oxide sorbent regeneration

    DOEpatents

    Turk, Brian S.; Gupta, Raghubir P.

    1999-01-01

    A process of regenerating a sulfided sorbent is provided. According to the process of the invention, a substantial portion of the energy necessary to initiate the regeneration reaction is provided by the combustion of a particulate metal sulfide additive. In using the particulate metal sulfide additive, the oxygen-containing gas used to regenerate the sulfided sorbent can be fed to the regeneration zone without heating or at a lower temperature than used in conventional processes wherein the regeneration reaction is initiated only by heating the oxygen-containing. The particulate metal sulfide additive is preferably an inexpensive mineral ore such as iron pyrite which does not adversely affect the regeneration or corresponding desulfurization reactions. The invention further includes a sorbent composition comprising the particulate metal sulfide additive in admixture with an active metal oxide sorbent capable of removing one or more sulfur compounds from a sulfur-containing gas stream.

  20. Metal sulfide initiators for metal oxide sorbent regeneration

    DOEpatents

    Turk, Brian S.; Gupta, Raghubir P.

    2001-01-01

    A process of regenerating a sulfided sorbent is provided. According to the process of the invention, a substantial portion of the energy necessary to initiate the regeneration reaction is provided by the combustion of a particulate metal sulfide additive. In using the particulate metal sulfide additive, the oxygen-containing gas used to regenerate the sulfided sorbent can be fed to the regeneration zone without heating or at a lower temperature than used in conventional processes wherein the regeneration reaction is initiated only by heating the oxygen-containing gas. The particulate metal sulfide additive is preferably an inexpensive mineral ore such as iron pyrite which does not adversely affect the regeneration or corresponding desulfurization reactions. The invention further includes a sorbent composition comprising the particulate metal sulfide additive in admixture with an active metal oxide sorbent capable of removing one or more sulfur compounds from a sulfur-containing gas stream.

  1. METAL EXTRACTION PROCESS

    DOEpatents

    Lewis, G.W. Jr.; Rhodes, D.E.

    1957-11-01

    An improved method for extracting uranium from aqueous solutions by solvent extraction is presented. A difficulty encountered in solvent extraction operations using an organic extractant (e.g., tributyl phosphate dissolved in kerosene or carbon tetrachloride) is that emulsions sometimes form, and phase separation is difficult or impossible. This difficulty is overcome by dissolving the organic extractant in a molten wax which is a solid at operating temperatures. After cooling, the wax which now contains the extractant, is broken into small particles (preferably flakes) and this wax complex'' is used to contact the uranium bearing solutions and extract the metal therefrom. Microcrystalline petroleum wax and certain ethylene polymers have been found suitable for this purpose.

  2. Dry etching of metallization

    NASA Technical Reports Server (NTRS)

    Bollinger, D.

    1983-01-01

    The production dry etch processes are reviewed from the perspective of microelectronic fabrication applications. The major dry etch processes used in the fabrication of microelectronic devices can be divided into two categories - plasma processes in which samples are directly exposed to an electrical discharge, and ion beam processes in which samples are etched by a beam of ions extracted from a discharge. The plasma etch processes can be distinguished by the degree to which ion bombardment contributes to the etch process. This, in turn is related to capability for anisotropic etching. Reactive Ion Etching (RIE) and Ion Beam Etching are of most interest for etching of thin film metals. RIE is generally considered the best process for large volume, anisotropic aluminum etching.

  3. Multiscale metallic metamaterials.

    PubMed

    Zheng, Xiaoyu; Smith, William; Jackson, Julie; Moran, Bryan; Cui, Huachen; Chen, Da; Ye, Jianchao; Fang, Nicholas; Rodriguez, Nicholas; Weisgraber, Todd; Spadaccini, Christopher M

    2016-10-01

    Materials with three-dimensional micro- and nanoarchitectures exhibit many beneficial mechanical, energy conversion and optical properties. However, these three-dimensional microarchitectures are significantly limited by their scalability. Efforts have only been successful only in demonstrating overall structure sizes of hundreds of micrometres, or contain size-scale gaps of several orders of magnitude. This results in degraded mechanical properties at the macroscale. Here we demonstrate hierarchical metamaterials with disparate three-dimensional features spanning seven orders of magnitude, from nanometres to centimetres. At the macroscale they achieve high tensile elasticity (>20%) not found in their brittle-like metallic constituents, and a near-constant specific strength. Creation of these materials is enabled by a high-resolution, large-area additive manufacturing technique with scalability not achievable by two-photon polymerization or traditional stereolithography. With overall part sizes approaching tens of centimetres, these unique nanostructured metamaterials might find use in a broad array of applications.

  4. Creating bulk nanocrystalline metal.

    SciTech Connect

    Fredenburg, D. Anthony; Saldana, Christopher J.; Gill, David D.; Hall, Aaron Christopher; Roemer, Timothy John; Vogler, Tracy John; Yang, Pin

    2008-10-01

    Nanocrystalline and nanostructured materials offer unique microstructure-dependent properties that are superior to coarse-grained materials. These materials have been shown to have very high hardness, strength, and wear resistance. However, most current methods of producing nanostructured materials in weapons-relevant materials create powdered metal that must be consolidated into bulk form to be useful. Conventional consolidation methods are not appropriate due to the need to maintain the nanocrystalline structure. This research investigated new ways of creating nanocrystalline material, new methods of consolidating nanocrystalline material, and an analysis of these different methods of creation and consolidation to evaluate their applicability to mesoscale weapons applications where part features are often under 100 {micro}m wide and the material's microstructure must be very small to give homogeneous properties across the feature.

  5. Metal-Mesh Lithography

    PubMed Central

    Tang, Zhao; Wei, Qingshan; Wei, Alexander

    2011-01-01

    Metal-mesh lithography (MML) is a practical hybrid of microcontact printing and capillary force lithography that can be applied over millimeter-sized areas with a high level of uniformity. MML can be achieved by blotting various inks onto substrates through thin copper grids, relying on preferential wetting and capillary interactions between template and substrate for pattern replication. The resulting mesh patterns, which are inverted relative to those produced by stenciling or serigraphy, can be reproduced with low micrometer resolution. MML can be combined with other surface chemistry and lift-off methods to create functional microarrays for diverse applications, such as periodic islands of gold nanorods and patterned corrals for fibroblast cell cultures. PMID:22103322

  6. Metal-mesh lithography.

    PubMed

    Tang, Zhao; Wei, Qingshan; Wei, Alexander

    2011-12-01

    Metal-mesh lithography (MML) is a practical hybrid of microcontact printing and capillary force lithography that can be applied over millimeter-sized areas with a high level of uniformity. MML can be achieved by blotting various inks onto substrates through thin copper grids, relying on preferential wetting and capillary interactions between template and substrate for pattern replication. The resulting mesh patterns, which are inverted relative to those produced by stenciling or serigraphy, can be reproduced with low micrometer resolution. MML can be combined with other surface chemistry and lift-off methods to create functional microarrays for diverse applications, such as periodic islands of gold nanorods and patterned corrals for fibroblast cell cultures.

  7. Liquid Metal Drop Impingement

    NASA Astrophysics Data System (ADS)

    Che, Judy; Han, Jaehoon; Tryggvason, Gretar; Ceccio, Steven

    1996-11-01

    "Ballistic Partical Manufacturing" is a process in which individual drops are layered to form a part. We examine how metal drops deform and solidify, and how the solidification rate affects the material microstructure using both numerical simulations and experiments. A single set of equations governing the conservation of mass, energy, and momentum are written for all phases involved, and the phase boundary is treated as an imbedded interface by adding the appropriate source terms. We have simulated single drops colliding with a surface using a simple model which assumes that a melt solidifies below the melting point. Although simple, this model captures many aspects of the fluid flow and solidification. The experimental apparatus creates a single drop of prescribed size and propels it toward a cooled substrate. Favorable comparisons of experimental and numerical results have been achieved.

  8. Multiscale metallic metamaterials.

    PubMed

    Zheng, Xiaoyu; Smith, William; Jackson, Julie; Moran, Bryan; Cui, Huachen; Chen, Da; Ye, Jianchao; Fang, Nicholas; Rodriguez, Nicholas; Weisgraber, Todd; Spadaccini, Christopher M

    2016-10-01

    Materials with three-dimensional micro- and nanoarchitectures exhibit many beneficial mechanical, energy conversion and optical properties. However, these three-dimensional microarchitectures are significantly limited by their scalability. Efforts have only been successful only in demonstrating overall structure sizes of hundreds of micrometres, or contain size-scale gaps of several orders of magnitude. This results in degraded mechanical properties at the macroscale. Here we demonstrate hierarchical metamaterials with disparate three-dimensional features spanning seven orders of magnitude, from nanometres to centimetres. At the macroscale they achieve high tensile elasticity (>20%) not found in their brittle-like metallic constituents, and a near-constant specific strength. Creation of these materials is enabled by a high-resolution, large-area additive manufacturing technique with scalability not achievable by two-photon polymerization or traditional stereolithography. With overall part sizes approaching tens of centimetres, these unique nanostructured metamaterials might find use in a broad array of applications. PMID:27429209

  9. Evolution of Metals

    NASA Astrophysics Data System (ADS)

    Shull, J. M.

    1998-05-01

    This review will cover a mystery story. Actually, two mysteries of the Structure and Evolution of the Universe involving the history of the baryons and the chemical elements synthesized in the first stars. When did the gas and metals first form? How did they evolve to their current distribution? The original crime scene is unknown, but evidence has been collected in the diffuse intergalactic medium and in hot intracluster gas. In these scattered locales, large amounts of gas has accumulated, contaminated by heavy elements from the first stars. Unfortunately, some of the evidence has been destroyed by gravity. Also, the earliest quasars, massive stars, and supernovae altered the physical state of the gas and transported the elements far from the original scene. I will briefly review current observations and theories relevant to these processes and suggest ways in which future NASA missions could constrain the many speculative ideas on this subject.

  10. Melting of Transition Metals

    SciTech Connect

    Ross, M; Japel, S; Boehler, R

    2005-04-11

    We review the transition melting studies carried out at Mainz, and describe a recently developed model used to explain that the relatively low melting slopes are due to the partially filled d-bands, and the persistence of the pressure induced s-d transition. The basic tenets of the model have now been reconfirmed by new measurements for Cu and Ni. The measurements show that Cu which has a filled 3d-band, has a melt slope that is about 2.5 greater than its neighbor Ni. In the case of Mo, the apparent discrepancy of DAC melting measurements with shock melting can be explained by accounting for the change in melt slope due to the bcc-cp transition observed in the shock studies. The Fe melt curve is revisited. The possible relevance of the Jahn-Teller effect and recently observed transition metal melts with Icosahedral Short-Range Order (ISRO) is discussed.

  11. Multiscale metallic metamaterials

    NASA Astrophysics Data System (ADS)

    Zheng, Xiaoyu; Smith, William; Jackson, Julie; Moran, Bryan; Cui, Huachen; Chen, Da; Ye, Jianchao; Fang, Nicholas; Rodriguez, Nicholas; Weisgraber, Todd; Spadaccini, Christopher M.

    2016-10-01

    Materials with three-dimensional micro- and nanoarchitectures exhibit many beneficial mechanical, energy conversion and optical properties. However, these three-dimensional microarchitectures are significantly limited by their scalability. Efforts have only been successful only in demonstrating overall structure sizes of hundreds of micrometres, or contain size-scale gaps of several orders of magnitude. This results in degraded mechanical properties at the macroscale. Here we demonstrate hierarchical metamaterials with disparate three-dimensional features spanning seven orders of magnitude, from nanometres to centimetres. At the macroscale they achieve high tensile elasticity (>20%) not found in their brittle-like metallic constituents, and a near-constant specific strength. Creation of these materials is enabled by a high-resolution, large-area additive manufacturing technique with scalability not achievable by two-photon polymerization or traditional stereolithography. With overall part sizes approaching tens of centimetres, these unique nanostructured metamaterials might find use in a broad array of applications.

  12. Expanding hollow metal rings

    DOEpatents

    Peacock, Harold B.; Imrich, Kenneth J.

    2009-03-17

    A sealing device that may expand more planar dimensions due to internal thermal expansion of a filler material. The sealing material is of a composition such that when desired environment temperatures and internal actuating pressures are reached, the sealing materials undergoes a permanent deformation. For metallic compounds, this permanent deformation occurs when the material enters the plastic deformation phase. Polymers, and other materials, may be using a sealing mechanism depending on the temperatures and corrosivity of the use. Internal pressures are generated by either rapid thermal expansion or material phase change and may include either liquid or solid to gas phase change, or in the gaseous state with significant pressure generation in accordance with the gas laws. Sealing material thickness and material composition may be used to selectively control geometric expansion of the seal such that expansion is limited to a specific facing and or geometric plane.

  13. Shape-Controlled Metal-Metal and Metal-Polymer Janus Structures by Thermoplastic Embossing.

    PubMed

    Hasan, Molla; Kahler, Niloofar; Kumar, Golden

    2016-05-01

    We report the fabrication of metal-metal and metal-polymer Janus structures by embossing of thermoplastic metallic glasses and polymers. Hybrid structures with controllable shapes and interfaces are synthesized by template-assisted embossing. Different manufacturing strategies such as co-embossing and additive embossing are demonstrated for joining the materials with diverse compositions and functionalities. Structures with distinct combinations of properties such as hydrophobic-hydrophilic, opaque-transparent, insulator-conductor, and nonmagnetic-ferromagnetic are produced using this approach. These anisotropic properties are further utilized for selective functionalization of Janus structures.

  14. Radioprotection by metals: Selenium

    NASA Astrophysics Data System (ADS)

    Weiss, J. F.; Srinivasan, V.; Kumar, K. S.; Landauer, M. R.

    The need exists for compounds that will protect individuals from high-dose acute radiation exposure in space and for agents that might be less protective but less toxic and longer acting. Metals and metal derivatives provide a small degree of radioprotection (dose reduction factor <= 1.2 for animal survival after whole-body irradiation). Emphasis is placed here on the radioprotective potential of selenium (Se). Both the inorganic salt, sodium selenite, and the organic Se compound, selenomethionine, enhance the survival of irradiated mice (60Co, 0.2 Gy/min) when injected IP either before (-24 hr and -1 hr) or shortly after (+15 min) radiation exposure. When administered at equitoxic doses (one-fourth LD10; selenomethionine = 4.0 mg/kg Se, sodium selenite = 0.8 mg/kg Se), both drugs enhanced the 30-day survival of mice irradiated at 9 Gy. Survival after 10-Gy exposure was significantly increased only after selenomethionine treatment. An advantage of selenomethionine is lower lethal and behavioral toxicity (locomotor activity depression) compared to sodium selenite, when they are administered at equivalent doses of Se. Sodium selenite administered in combination with WR-2721, S-2-(3-aminopropylamino)ethylphosphorothioic acid, enhances the radioprotective effect and reduces the lethal toxicity, but not the behavioral toxicity, of WR-2721. Other studies on radioprotection and protection against chemical carcinogens by different forms of Se are reviewed. As additional animal data and results from human chemoprevention trials become available, consideration also can be given to prolonged administration of Se compounds for protection against long-term radiation effects in space.

  15. Liquid metal thermoacoustic engine

    SciTech Connect

    Swift, G.W.; Migliori, A.; Wheatley, J.C.

    1986-01-01

    We are studying a liquid metal thermoacoustic engine both theoretically and experimentally. This type of engine promises to produce large quantities of electrical energy from heat at modest efficiency with no moving parts. A sound wave is usually thought of as consisting of pressure oscillations, but always attendant to the pressure oscillation are temperature oscillations. The combination produces a rich variety of ''thermoacoustic'' effects. These effects are usually so small that they are never noticed in everyday life; nevertheless under the right circumstances they can be harnessed to produce powerful heat engines, heat pumps, and refrigerators. In our liquid metal thermoacoustic engine, heat flow from a high temperature source to a low temperature sink generates a high-amplitude standing acoustic wave in liquid sodium. This acoustic power is converted to electric power by a simple magnetohydrodynamic effect at the acoustic oscillation frequency. We have developed a detailed thermoacoustic theory applicable to this engine, and find that a reasonably designed liquid sodium engine operating between 700/sup 0/C and 100/sup 0/C should generate about 60 W/cm/sup 2/ of acoustic power at about 1/3 of Carnot's efficiency. Construction of a 3000 W-thermal laboratory model engine has just been completed, and we have exciting preliminary experimental results as of the time of preparation of this manuscript showing, basically, that the engine works. We have also designed and built a 1 kHz liquid sodium magnetohydrodynamic generator and have extensive measurements on it. It is now very well characterized both experimentally and theoretically. The first generator of its kind, it already converts acoustic power to electric power with 40% efficiency. 16 refs., 5 figs.

  16. Synthesis metal nanoparticle

    DOEpatents

    Bunge, Scott D.; Boyle, Timothy J.

    2005-08-16

    A method for providing an anhydrous route for the synthesis of amine capped coinage-metal (copper, silver, and gold) nanoparticles (NPs) using the coinage-metal mesityl (mesityl=C.sub.6 H.sub.2 (CH.sub.3).sub.3 -2,4,6) derivatives. In this method, a solution of (Cu(C.sub.6 H.sub.2 (CH.sub.3).sub.3).sub.5, (Ag(C.sub.6 H.sub.2 (CH.sub.3).sub.3).sub.4, or (Au(C.sub.6 H.sub.2 (CH.sub.3).sub.3).sub.5 is dissolved in a coordinating solvent, such as a primary, secondary, or tertiary amine; primary, secondary, or tertiary phosphine, or alkyl thiol, to produce a mesityl precursor solution. This solution is subsequently injected into an organic solvent that is heated to a temperature greater than approximately 100.degree. C. After washing with an organic solvent, such as an alcohol (including methanol, ethanol, propanol, and higher molecular-weight alcohols), oxide free coinage NP are prepared that could be extracted with a solvent, such as an aromatic solvent (including, for example, toluene, benzene, and pyridine) or an alkane (including, for example, pentane, hexane, and heptane). Characterization by UV-Vis spectroscopy and transmission electron microscopy showed that the NPs were approximately 9.2.+-.2.3 nm in size for Cu.degree., (no surface oxide present), approximately 8.5.+-.1.1 nm Ag.degree. spheres, and approximately 8-80 nm for Au.degree..

  17. Thin film hydrous metal oxide catalysts

    DOEpatents

    Dosch, Robert G.; Stephens, Howard P.

    1995-01-01

    Thin film (<100 nm) hydrous metal oxide catalysts are prepared by 1) synthesis of a hydrous metal oxide, 2) deposition of the hydrous metal oxide upon an inert support surface, 3) ion exchange with catalytically active metals, and 4) activating the hydrous metal oxide catalysts.

  18. RECOVERY OF METAL USING ALUMINUM DISPLACEMENT

    EPA Science Inventory

    The removal of typical metals (Cu, Pb, Sn, Ni) from printed circuit and metal finishing waste streams was evaluated using displacement with aluminum. he metal is recovered as non-hazardous metal particles and can be recycled by smelting. n acceptable aluminum metal configuration ...

  19. Method of foaming a liquid metal

    DOEpatents

    Fischer, Albert K.; Johnson, Carl E.

    1980-01-01

    The addition of a small quantity of barium to liquid metal NaK or sodium has been found to promote foam formation and improve bubble retention in the liquid metal. A stable liquid metal foam will provide a more homogeneous liquid metal flow through the channel of a two-phase liquid metal MHD power generator to improve operating efficiency.

  20. Structural basis of metal hypersensitivity

    PubMed Central

    Wang, Yang

    2014-01-01

    Metal hypersensitivity is a common immune disorder. Human immune systems mount the allergic attacks on metal ions through skin contacts, lung inhalation and metal-containing artificial body implants. The consequences can be simple annoyances to life-threatening systemic illness. Allergic hyper-reactivities to nickel (Ni) and beryllium (Be) are the best-studied human metal hypersensitivities. Ni-contact dermatitis affects 10 % of the human population, whereas Be compounds are the culprits of chronic Be disease (CBD). αβ T cells (T cells) play a crucial role in these hypersensitivity reactions. Metal ions work as haptens and bind to the surface of major histocompatibility complex (MHC) and peptide complex. This modifies the binding surface of MHC and triggers the immune response of T cells. Metal-specific αβ T cell receptors (TCRs) are usually MHC restricted, especially MHC class II (MHCII) restricted. Numerous models have been proposed, yet the mechanisms and molecular basis of metal hypersensitivity remain elusive. Recently, we determined the crystal structures of the Ni and Be presenting human MHCII molecules, HLA-DR52c (DRA*0101, DRB3*0301) and HLA-DP2 (DPA1*0103, DPB1*0201). These structures revealed unusual features of MHCII molecules and shed light on how metal ions are recognized by T cells. PMID:22983897

  1. MOD silver metallization for photovoltaics

    NASA Technical Reports Server (NTRS)

    Vest, G. M.; Vest, R. W.

    1984-01-01

    Photovoltaic cells require back side metallization and a collector grid system on the front surface. Both front and back surface metallizations should have good adhesion, low contact resistance, low sheet resistance, long term stability, and their deposition methods should not degrade the n-p junction. Advantages and disadvantages of different deposition methods are discussed.

  2. PROCESS OF RECOVERING ALKALI METALS

    DOEpatents

    Wolkoff, J.

    1961-08-15

    A process is described of recovering alkali metal vapor by sorption on activated alumina, activated carbon, dehydrated zeolite, activated magnesia, or Fuller's earth preheated above the vaporization temperature of the alkali metal and subsequent desorption by heating the solvent under vacuum. (AEC)

  3. General aspects of metal toxicity.

    PubMed

    Kozlowski, H; Kolkowska, P; Watly, J; Krzywoszynska, K; Potocki, S

    2014-01-01

    This review is focused on the general mechanisms of metal toxicity in humans. The possible and mainly confirmed mechanisms of their action are discussed. The metals are divided into four groups due to their toxic effects. First group comprises of metal ions acting as Fenton reaction catalyst mainly iron and copper. These types of metal ions participate in generation of the reactive oxygen species. Metals such as nickel, cadmium and chromium are considered as carcinogenic agents. Aluminum, lead and tin are involved in neurotoxicity. The representative of the last group is mercury, which may be considered as a generally toxic metal. Fenton reaction is a naturally occurring process producing most active oxygen species, hydroxyl radical: Fe(2+) + He2O2 ↔ Fe(3+) + OH(-) + OH(•) It is able to oxidize most of the biomolecules including DNA, proteins, lipids etc. The effect of toxicity depends on the damage of molecules i.e. production site of the hydroxyl radical. Chromium toxicity depends critically on its oxidation state. The most hazardous seems to be Cr(6+) (chromates) which are one of the strongest inorganic carcinogenic agents. Cr(6+) species act also as oxidative agents damaging among other nucleic acids. Redox inactive Al(3+), Cd(2+) or Hg(2+) may interfere with biology of other metal ions e.g. by occupying metal binding sites in biomolecules. All these aspects will be discussed in the review. PMID:25039781

  4. Agriculture Education. Agricultural Metal Working.

    ERIC Educational Resources Information Center

    Stuttgart Public Schools, AR.

    This curriculum guide is designed for group instruction of secondary agricultural education students enrolled in one or two semester-long courses in agricultural metal working. The guide presents units of study in the following areas: (1) oxyacetylene welding, (2) arc welding, (3) sheet metal, (4) blueprint reading for welders and (5) job…

  5. Alzheimer's disease & metals: therapeutic opportunities

    PubMed Central

    Kenche, Vijaya B; Barnham, Kevin J

    2011-01-01

    Alzheimer's disease (AD) is the most common age related neurodegenerative disease. Currently, there are no disease modifying drugs, existing therapies only offer short-term symptomatic relief. Two of the pathognomonic indicators of AD are the presence of extracellular protein aggregates consisting primarily of the Aβ peptide and oxidative stress. Both of these phenomena can potentially be explained by the interactions of Aβ with metal ions. In addition, metal ions play a pivotal role in synaptic function and their homeostasis is tightly regulated. A breakdown in this metal homeostasis and the generation of toxic Aβ oligomers are likely to be responsible for the synaptic dysfunction associated with AD. Therefore, approaches that are designed to prevent Aβ metal interactions, inhibiting the formation of toxic Aβ species as well as restoring metal homeostasis may have potential as disease modifying strategies for treating AD. This review summarizes the physiological and pathological interactions that metal ions play in synaptic function with particular emphasis placed on interactions with Aβ. A variety of therapeutic strategies designed to address these pathological processes are also described. The most advanced of these strategies is the so-called ‘metal protein attenuating compound’ approach, with the lead molecule PBT2 having successfully completed early phase clinical trials. The success of these various strategies suggests that manipulating metal ion interactions offers multiple opportunities to develop disease modifying therapies for AD. PMID:21232050

  6. Metal recovery from porous materials

    DOEpatents

    Sturcken, E.F.

    1991-01-01

    The present invention relates to recovery of metals. More specifically, the present invention relates to the recovery of plutonium and other metals from porous materials using microwaves. The United States Government has rights in this invention pursuant to Contract No. DE-AC09-89SR18035 between the US Department of Energy and Westinghouse Savannah River Company.

  7. Nanostructured metal-polyaniline composites

    DOEpatents

    Wang, Hsing-Lin; Li, Wenguang; Bailey, James A.; Gao, Yuan

    2010-08-31

    Metal-polyaniline (PANI) composites are provided together with a process of preparing such composites by an electrodeless process. The metal of the composite can have nanoscale structural features and the composites can be used in applications such as catalysis for hydrogenation reactions and for analytical detection methods employing SERS.

  8. Metal Working and Welding Operations.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    This student guide, one of a series of correspondence training courses designed to improve the job performance of members of the Marine Corps, deals with the skills needed by metal workers and welders. Addressed in the six individual units of the course are the following topics: weldable metals and their alloys, arc welding, gas welding,…

  9. Cluster-assembled metallic glasses

    NASA Astrophysics Data System (ADS)

    Kartouzian, Aras

    2013-07-01

    A bottom-up approach to nanofabricate metallic glasses from metal clusters as building blocks is presented. Considering metallic glasses as a subclass of cluster-assembled materials, the relation between the two lively fields of metal clusters and metallic glasses is pointed out. Deposition of selected clusters or collections of them, generated by state-of-the-art cluster beam sources, could lead to the production of a well-defined amorphous material. In contrast to rapidly quenched glasses where only the composition of the glass can be controlled, in cluster-assembled glasses, one can precisely control the structural building blocks. Comparing properties of glasses with similar compositions but differing in building blocks and therefore different in structure will facilitate the study of structure-property correlation in metallic glasses. This bottom-up method provides a novel alternative path to the synthesis of glassy alloys and will contribute to improving fundamental understanding in the field of metallic glasses. It may even permit the production of glassy materials for alloys that cannot be quenched rapidly enough to circumvent crystallization. Additionally, gaining deeper insight into the parameters governing the structure-property relation in metallic glasses can have a great impact on understanding and design of other cluster-assembled materials.

  10. Cluster-assembled metallic glasses.

    PubMed

    Kartouzian, Aras

    2013-07-30

    A bottom-up approach to nanofabricate metallic glasses from metal clusters as building blocks is presented. Considering metallic glasses as a subclass of cluster-assembled materials, the relation between the two lively fields of metal clusters and metallic glasses is pointed out. Deposition of selected clusters or collections of them, generated by state-of-the-art cluster beam sources, could lead to the production of a well-defined amorphous material. In contrast to rapidly quenched glasses where only the composition of the glass can be controlled, in cluster-assembled glasses, one can precisely control the structural building blocks. Comparing properties of glasses with similar compositions but differing in building blocks and therefore different in structure will facilitate the study of structure-property correlation in metallic glasses. This bottom-up method provides a novel alternative path to the synthesis of glassy alloys and will contribute to improving fundamental understanding in the field of metallic glasses. It may even permit the production of glassy materials for alloys that cannot be quenched rapidly enough to circumvent crystallization. Additionally, gaining deeper insight into the parameters governing the structure-property relation in metallic glasses can have a great impact on understanding and design of other cluster-assembled materials.

  11. Metals Cluster. Secondary Curriculum Guide.

    ERIC Educational Resources Information Center

    Watkins, James F.; And Others

    This curriculum guide was designed for use in secondary metal trades education in Georgia. Its purpose is to provide for development of entry level skills in metal trades in the areas of knowledge, theoretical structure, tool usage, diagnostic ability, related supportive skills, and occupational survival skills. The first section of six explains…

  12. Geomycology: metals, actinides and biominerals.

    PubMed

    Gadd, Geoffrey Michael; Rhee, Young Joon; Stephenson, Karen; Wei, Zhan

    2012-06-01

    Geomycology can be simply defined as 'the scientific study of the roles of fungi in processes of fundamental importance to geology' and the biogeochemical importance of fungi is significant in several key areas. These include nutrient and element cycling, rock and mineral transformations, bioweathering, mycogenic biomineral formation and interactions of fungi with clay minerals and metals. Such processes can occur in aquatic and terrestrial habitats, but it is in the terrestrial environment where fungi probably have the greatest geochemical influence. Of special significance are the mutualistic relationships with phototrophic organisms, lichens (algae, cyanobacteria) and mycorrhizas (plants). Central to many geomycological processes are transformations of metals and minerals, and fungi possess a variety of properties that can effect changes in metal speciation, toxicity and mobility, as well as mineral formation or mineral dissolution or deterioration. Some fungal transformations have beneficial applications in environmental biotechnology, e.g. in metal and radionuclide leaching, recovery, detoxification and bioremediation, and in the production or deposition of biominerals or metallic elements with catalytic or other properties. Metal and mineral transformations may also result in adverse effects when these processes result in spoilage and destruction of natural and synthetic materials, rock and mineral-based building materials (e.g. concrete), acid mine drainage and associated metal pollution, biocorrosion of metals, alloys and related substances, and adverse effects on radionuclide speciation, mobility and containment. The ubiquity and importance of fungi in biosphere processes underlines the importance of geomycology as an interdisciplinary subject area within microbiology and mycology. PMID:23760792

  13. Metal imaging in neurodegenerative diseases

    PubMed Central

    Bourassa, Megan W.

    2014-01-01

    Metal ions are known to play an important role in many neurodegenerative diseases including Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), and prion diseases. In these diseases, aberrant metal binding or improper regulation of redox active metal ions can induce oxidative stress by producing cytotoxic reactive oxygen species (ROS). Altered metal homeostasis is also frequently seen in the diseased state. As a result, the imaging of metals in intact biological cells and tissues has been very important for understanding the role of metals in neurodegenerative diseases. A wide range of imaging techniques have been utilized, including X-ray fluorescence microscopy (XFM), particle induced X-ray emission (PIXE), energy dispersive X-ray spectroscopy (EDS), laser ablation inductively coupled mass spectrometry (LA-ICP-MS), and secondary ion mass spectrometry (SIMS), all of which allow for the imaging of metals in biological specimens with high spatial resolution and detection sensitivity. These techniques represent unique tools for advancing the understanding of the disease mechanisms and for identifying possible targets for developing treatments. In this review, we will highlight the advances in neurodegenerative disease research facilitated by metal imaging techniques. PMID:22797194

  14. Computer simulation of liquid metals

    NASA Astrophysics Data System (ADS)

    Belashchenko, D. K.

    2013-12-01

    Methods for and the results of the computer simulation of liquid metals are reviewed. Two basic methods, classical molecular dynamics with known interparticle potentials and the ab initio method, are considered. Most attention is given to the simulated results obtained using the embedded atom model (EAM). The thermodynamic, structural, and diffusion properties of liquid metal models under normal and extreme (shock) pressure conditions are considered. Liquid-metal simulated results for the Groups I - IV elements, a number of transition metals, and some binary systems (Fe - C, Fe - S) are examined. Possibilities for the simulation to account for the thermal contribution of delocalized electrons to energy and pressure are considered. Solidification features of supercooled metals are also discussed.

  15. Metallic surfaces with special wettability

    NASA Astrophysics Data System (ADS)

    Liu, Kesong; Jiang, Lei

    2011-03-01

    Metals are important and irreplaceable engineered materials in our society. Nature is a school for scientists and engineers, which has long served as a source of inspiration for humans. Inspired by nature, a variety of metallic surfaces with special wettability have been fabricated in recent years through the combination of surface micro- and nanostructures and chemical composition. These metallic surfaces with special wettability exhibit important applications in anti-corrosion, microfluidic systems, oil-water separation, liquid transportation, and other fields. Recent achievements in the fabrication and application of metallic surfaces with special wettability are presented in this review. The research prospects and directions of this field are also briefly addressed. We hope this review will be beneficial to expand the practical applications of metals and offer some inspirations to the researchers in the fields of engineering, biomedicine, and materials science.

  16. Durability of metals from archaeological objects, metal meteorites, and native metals

    SciTech Connect

    Johnson, A.B. Jr.; Francis, B.

    1980-01-01

    Metal durability is an important consideration in the multi-barrier nuclear waste storage concept. This study summarizes the ancient metals, the environments, and factors which appear to have contributed to metal longevity. Archaeological and radiochemical dating suggest that human use of metals began in the period 6000 to 7000 BC. Gold is clearly the most durable, but many objects fashioned from silver, copper, bronze, iron, lead, and tin have survived for several thousand years. Dry environments, such as tombs, appear to be optimum for metal preservation, but some metals have survived in shipwrecks for over a thousand years. The metal meteorites are Fe-base alloys with 5 to 60 wt% Ni and minor amounts of Co, I, and S. Some meteoritic masses with ages estimated to be 5,000 to 20,000 years have weathered very little, while other masses from the same meteorites are in advanced stages of weathering. Native metals are natural metallic ores. Approximately five million tonnes were mined from native copper deposits in Michigan. Copper masses from the Michigan deposits were transported by the Pleistocene glaciers. Areas on the copper surfaces which appear to represent glacial abrasion show minimal corrosion. Dry cooling tower technology has demonstrated that in pollution-free moist environments, metals fare better at temperatures above than below the dewpoint. Thus, in moderate temperature regimes, elevated temperatures may be useful rather than detrimental for exposures of metal to air. In liquid environments, relatively complex radiolysis reactions can occur, particularly where multiple species are present. A dry environment largely obviates radiolysis effects.

  17. CoCrMo Metal-on-Metal Hip Replacements

    PubMed Central

    Liao, Yifeng; Hoffman, Emily; Wimmer, Markus; Fischer, Alfons; Jacobs, Joshua; Marks, Laurence

    2012-01-01

    After the rapid growth in the use of CoCrMo metal-on-metal hip replacements since the second generation was introduced circa 1990, metal-on-metal hip replacements have experienced a sharp decline in the last two years due to biocompatibility issues related to wear and corrosion products. Despite some excellent clinical results, the release of wear and corrosion debris and the adverse response of local tissues have been of great concern. There are many unknowns regarding how CoCrMo metal bearings interact with the human body. This perspective article is intended to outline some recent progresses in understanding wear and corrosion of metal-on-metal hip replacement both in-vivo and in-vitro. The materials, mechanical deformation, corrosion, wear-assisted corrosion, and wear products will be discussed. Possible adverse health effects caused by wear products will be briefly addressed, as well as some of the many open questions such as the detailed chemistry of corrosion, tribochemical reactions and the formation of graphitic layers. Nowadays we design almost routinely for high performance materials and lubricants for automobiles; humans are at least as important. It is worth remembering that a hip implant is often the difference between walking and leading a relatively normal life, and a wheelchair. PMID:23196425

  18. Atom scattering from metals

    NASA Astrophysics Data System (ADS)

    Hayes, W. W.

    In the initial portion of this dissertation studies of Ar scattering from Ru(0001) at thermal and hyperthermal energies are compared to calculations with classical scattering theory. These data exhibited a number of characteristics that are unusual in comparison to other systems for which atomic beam experiments have been carried out under similar conditions. The measured energy losses were unusually small. Some of the angular distributions exhibited an anomalous shoulder feature in addition to a broad peak near the specular direction and quantum mechanical diffraction was observed under conditions for which it was not expected. Many of the unusual features observed in the measurements are explained, but only upon using an effective surface mass of 2.3 Ru atomic masses, which implies collective effects in the Ru crystal. The large effective mass, because it leads to substantially larger Debye-Waller factors, explains and confirms the observations of diffraction features. It also leads to the interesting conclusion that Ru is a metal for which atomic beam scattering measurements in the purely quantum mechanical regime, where diffraction and single-phonon creation are dominant, should be possible not only with He atoms, but with many other atomic species with larger masses. A useful theoretical expression for interpreting and analyzing observed scattering intensity spectra for atomic and molecular collisions with surfaces is the differential reflection coefficient for a smooth, vibrating surface. This differential reflection coefficient depends on a parameter, usually expressed in dimensions of velocity, that arises due to correlated motions of neighboring regions of the surface and can be evaluated if the polarization vectors of the phonons near the surface are known. As a part of this dissertation experimental conditions are suggested under which this velocity paramenter may be more precisely measured than it has been in the past. Experimental data for scattering

  19. Alkali metal and alkali earth metal gadolinium halide scintillators

    DOEpatents

    Bourret-Courchesne, Edith; Derenzo, Stephen E.; Parms, Shameka; Porter-Chapman, Yetta D.; Wiggins, Latoria K.

    2016-08-02

    The present invention provides for a composition comprising an inorganic scintillator comprising a gadolinium halide, optionally cerium-doped, having the formula A.sub.nGdX.sub.m:Ce; wherein A is nothing, an alkali metal, such as Li or Na, or an alkali earth metal, such as Ba; X is F, Br, Cl, or I; n is an integer from 1 to 2; m is an integer from 4 to 7; and the molar percent of cerium is 0% to 100%. The gadolinium halides or alkali earth metal gadolinium halides are scintillators and produce a bright luminescence upon irradiation by a suitable radiation.

  20. New Concentric Electrode Metal-Semiconductor-Metal Photodetectors

    NASA Technical Reports Server (NTRS)

    Towe, Elias

    1996-01-01

    A new metal-semiconductor-metal (MSM) photodetector geometry is proposed. The new device has concentric metal electrodes which exhibit a high degree of symmetry and a design flexibility absent in the conventional MSM device. The concentric electrodes are biased to alternating potentials as in the conventional interdigitated device. Because of the high symmetry configuration, however, the new device also has a lower effective capacitance. This device and the conventional MSM structure are analyzed within a common theoretical framework which allows for the comparison of the important performance characteristics.

  1. Surface polaritons of a metal-insulator-metal curved slab

    NASA Astrophysics Data System (ADS)

    Moradi, Afshin

    2016-09-01

    The properties of s- and p-polarized surface polariton modes propagating circumferentially around a portion of a cylindrical metal-insulator-metal structure are studied, theoretically. By using the Maxwell equations in conjunction with the Drude model for the dielectric function of the metals and applying the appropriate boundary conditions, the dispersion relations of surface waves for two types of modes, are derived and numerically solved. The effects of the slab curvature and insulator thickness on the propagation of electromagnetic modes are investigated. The differences of the s- and p-polarized surface modes are also shown.

  2. A study of different metals employed in metal-metal waveguides for terahertz quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Szymański, Michał; Szerling, Anna; Kosiel, Kamil; Płuska, Mariusz

    2016-07-01

    We consider the possibility of improvement of metal-metal waveguides designed for terahertz quantum cascade lasers (THz QCL) with respect to waveguide losses. We calculate {α\\text{wg}} solving Helmholtz equation by transfer matrix method. The essence of our work is the error analysis. We notice that the refractive indices of metals in THz range are known with very poor accuracy. We present divergences among numerous measurements and calculations reported in the literature. In addition, we point out that optical properties of metals and semiconductors depend on temperature which varies throughout the working device. At last, we present our scanning electron microscope photos showing that semiconductor-metal and metal-metal interfaces are not perfect. In adjacent areas mixing of materials occurs and hence the spatial refractive index distribution is perturbed. Our error analysis shows that today’s accuracy of refractive index data (±37% is the best reported in the literature) makes the problem of optimization of considered waveguides ambiguous. According to our calculations the precision level of about  ±10% is required. Once improving the precision turns out to be impossible, we suggest focusing the design works on criteria such as choosing metals minimizing the risk of damaging the active region by atom migration, providing the best ohmic contact or allowing the most effective heat removal.

  3. Mysteries of metals in metalloenzymes.

    PubMed

    Valdez, Crystal E; Smith, Quentin A; Nechay, Michael R; Alexandrova, Anastassia N

    2014-10-21

    Natural metalloenzymes are often the most proficient catalysts in terms of their activity, selectivity, and ability to operate at mild conditions. However, metalloenzymes are occasionally surprising in their selection of catalytic metals, and in their responses to metal substitution. Indeed, from the isolated standpoint of producing the best catalyst, a chemist designing from first-principles would likely choose a different metal. For example, some enzymes employ a redox active metal where a simple Lewis acid is needed. Such are several hydrolases. In other cases, substitution of a non-native metal leads to radical improvements in reactivity. For example, histone deacetylase 8 naturally operates with Zn(2+) in the active site but becomes much more active with Fe(2+). For β-lactamases, the replacement of the native Zn(2+) with Ni(2+) was suggested to lead to higher activity as predicted computationally. There are also intriguing cases, such as Fe(2+)- and Mn(2+)-dependent ribonucleotide reductases and W(4+)- and Mo(4+)-dependent DMSO reductases, where organisms manage to circumvent the scarcity of one metal (e.g., Fe(2+)) by creating protein structures that utilize another metal (e.g., Mn(2+)) for the catalysis of the same reaction. Naturally, even though both metal forms are active, one of the metals is preferred in every-day life, and the other metal variant remains dormant until an emergency strikes in the cell. These examples lead to certain questions. When are catalytic metals selected purely for electronic or structural reasons, implying that enzymatic catalysis is optimized to its maximum? When are metal selections a manifestation of competing evolutionary pressures, where choices are dictated not just by catalytic efficiency but also by other factors in the cell? In other words, how can enzymes be improved as catalysts merely through the use of common biological building blocks available to cells? Addressing these questions is highly relevant to the enzyme

  4. 21 CFR 888.3550 - Knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Knee joint patellofemorotibial polymer/metal/metal... § 888.3550 Knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis. (a) Identification. A knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis is a...

  5. 21 CFR 888.3550 - Knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Knee joint patellofemorotibial polymer/metal/metal... § 888.3550 Knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis. (a) Identification. A knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis is a...

  6. 21 CFR 888.3550 - Knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Knee joint patellofemorotibial polymer/metal/metal... § 888.3550 Knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis. (a) Identification. A knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis is a...

  7. Method for preparing metal powder, device for preparing metal powder, method for processing spent nuclear fuel

    DOEpatents

    Park, Jong-Hee

    2011-11-29

    A method for producing metal powder is provided the comprising supplying a molten bath containing a reducing agent, contacting a metal oxide with the molten bath for a time and at a temperature sufficient to reduce the metal in the metal oxide to elemental metal and produce free oxygen; and isolating the elemental metal from the molten bath.

  8. 21 CFR 888.3210 - Finger joint metal/metal constrained cemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Finger joint metal/metal constrained cemented... metal/metal constrained cemented prosthesis. (a) Identification. A finger joint metal/metal constrained... together. This generic type of device includes prostheses that are made of alloys, such as...

  9. 21 CFR 888.3210 - Finger joint metal/metal constrained cemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Finger joint metal/metal constrained cemented... metal/metal constrained cemented prosthesis. (a) Identification. A finger joint metal/metal constrained... together. This generic type of device includes prostheses that are made of alloys, such as...

  10. 21 CFR 888.3200 - Finger joint metal/metal constrained uncemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Finger joint metal/metal constrained uncemented... metal/metal constrained uncemented prosthesis. (a) Identification. A finger joint metal/metal... prostheses made of alloys, such as cobalt-chromium-molybdenum, or protheses made from alloys and...

  11. 21 CFR 888.3210 - Finger joint metal/metal constrained cemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Finger joint metal/metal constrained cemented... metal/metal constrained cemented prosthesis. (a) Identification. A finger joint metal/metal constrained... together. This generic type of device includes prostheses that are made of alloys, such as...

  12. 21 CFR 888.3200 - Finger joint metal/metal constrained uncemented prosthesis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Finger joint metal/metal constrained uncemented... metal/metal constrained uncemented prosthesis. (a) Identification. A finger joint metal/metal... prostheses made of alloys, such as cobalt-chromium-molybdenum, or protheses made from alloys and...

  13. 21 CFR 888.3200 - Finger joint metal/metal constrained uncemented prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Finger joint metal/metal constrained uncemented... metal/metal constrained uncemented prosthesis. (a) Identification. A finger joint metal/metal... prostheses made of alloys, such as cobalt-chromium-molybdenum, or protheses made from alloys and...

  14. 21 CFR 888.3200 - Finger joint metal/metal constrained uncemented prosthesis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Finger joint metal/metal constrained uncemented... metal/metal constrained uncemented prosthesis. (a) Identification. A finger joint metal/metal... prostheses made of alloys, such as cobalt-chromium-molybdenum, or protheses made from alloys and...

  15. 21 CFR 888.3210 - Finger joint metal/metal constrained cemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Finger joint metal/metal constrained cemented... metal/metal constrained cemented prosthesis. (a) Identification. A finger joint metal/metal constrained... together. This generic type of device includes prostheses that are made of alloys, such as...

  16. 21 CFR 888.3210 - Finger joint metal/metal constrained cemented prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Finger joint metal/metal constrained cemented... metal/metal constrained cemented prosthesis. (a) Identification. A finger joint metal/metal constrained... together. This generic type of device includes prostheses that are made of alloys, such as...

  17. 21 CFR 888.3200 - Finger joint metal/metal constrained uncemented prosthesis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Finger joint metal/metal constrained uncemented... metal/metal constrained uncemented prosthesis. (a) Identification. A finger joint metal/metal... prostheses made of alloys, such as cobalt-chromium-molybdenum, or protheses made from alloys and...

  18. 21 CFR 888.3550 - Knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Knee joint patellofemorotibial polymer/metal/metal... § 888.3550 Knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis. (a) Identification. A knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis is a...

  19. 21 CFR 888.3550 - Knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Knee joint patellofemorotibial polymer/metal/metal... § 888.3550 Knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis. (a) Identification. A knee joint patellofemorotibial polymer/metal/metal constrained cemented prosthesis is a...

  20. Method for controlled hydrogen charging of metals

    DOEpatents

    Cheng, Bo-Ching; Adamson, Ronald B.

    1984-05-29

    A method for controlling hydrogen charging of hydride forming metals through a window of a superimposed layer of a non-hydriding metal overlying the portion of the hydride forming metals to be charged.

  1. La planète Vulcain, une perspective américaine, traduction d'un article de William Shehan et Tony Misch

    NASA Astrophysics Data System (ADS)

    Lequeux, James

    2016-10-01

    After his discovery of Neptune in 1846, Le Verrier attempted to extend Newton's theory to the innermost planet, Mercury. He found a small unexplained discrepancy in its motion. Applying the same assumption as had succeeded to explain the motion of Uranus with Neptune, he proposed the existence of an intra-Mercurial planet, named Vulcan, which would have perturbed Mercury. This article describes the long searches for Vulcan in America. Vulcan was never found from either side of the Atlantic, as well as a possible ring of debris which could have played the same role. The anomalous precession of the perihelion of Mercury was finally explained by Einstein in1915 in terms of the General Theory of Relativity, and provided one of the first confirmations of the theory's correctness.

  2. APPARATUS FOR HIGH PURITY METAL RECOVERY

    DOEpatents

    Magel, T.T.

    1959-02-10

    An apparatus is described for preparing high purity metal such as uranium, plutonium and the like from an impure mass of the same metal. The apparatus is arranged so that the impure metal is heated and swept by a stream of hydrogen gas bearing a halogen such as iodine. The volatiie metal halide formed is carried on to a hot filament where the metal halide is decomposed and the molten high purity metal is collected in a rceeiver below

  3. Ceramic TBS/porous metal compliant layer

    NASA Technical Reports Server (NTRS)

    Tolokan, Robert P.; Jarrabet, G. P.

    1992-01-01

    Technetics Corporation manufactures metal fiber materials and components used in aerospace applications. Our technology base is fiber metal porous sheet material made from sinter bonded metal fibers. Fiber metals have percent densities (metal content by volume) from 10 to 65 percent. Various topics are covered and include the following: fiber metal materials, compliant layer thermal bayer coatings (TBC's), pad properties, ceramic/pad TBC design, thermal shock rig, fabrication, and applications.

  4. Catalysis using hydrous metal oxide ion exchanges

    DOEpatents

    Dosch, Robert G.; Stephens, Howard P.; Stohl, Frances V.

    1985-01-01

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  5. Catalysis using hydrous metal oxide ion exchangers

    DOEpatents

    Dosch, R.G.; Stephens, H.P.; Stohl, F.V.

    1983-07-21

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  6. A dynamic inert metal anode.

    SciTech Connect

    Hryn, J. N.

    1998-11-09

    A new concept for a stable anode for aluminum electrowinning is described. The anode consists of a cup-shaped metal alloy container filled with a molten salt that contains dissolved aluminum. The metal alloy can be any of a number of alloys, but it must contain aluminum as a secondary alloying metal. A possible alloy composition is copper with 5 to 15 weight percent aluminum. In the presence of oxygen, aluminum on the metal anode's exterior surface forms a continuous alumina film that is thick enough to protect the anode from chemical attack by cryolite during electrolysis and thin enough to maintain electrical conductivity. However, the alumina film is soluble in cryolite, so it must be regenerated in situ. Film regeneration is achieved by the transport of aluminum metal from the anode's molten salt interior through the metal wall to the anode's exterior surface, where the transported aluminum oxidizes to alumina in the presence of evolving oxygen to maintain the protective alumina film. Periodic addition of aluminum metal to the anode's interior keeps the aluminum activity in the molten salt at the desired level. This concept for an inert anode is viable as long as the amount of aluminum produced at the cathode greatly exceeds the amount of aluminum required to maintain the anode's protective film.

  7. Mycobacteria, metals, and the macrophage.

    PubMed

    Neyrolles, Olivier; Wolschendorf, Frank; Mitra, Avishek; Niederweis, Michael

    2015-03-01

    Mycobacterium tuberculosis is a facultative intracellular pathogen that thrives inside host macrophages. A key trait of M. tuberculosis is to exploit and manipulate metal cation trafficking inside infected macrophages to ensure survival and replication inside the phagosome. Here, we describe the recent fascinating discoveries that the mammalian immune system responds to infections with M. tuberculosis by overloading the phagosome with copper and zinc, two metals which are essential nutrients in small quantities but are toxic in excess. M. tuberculosis has developed multi-faceted resistance mechanisms to protect itself from metal toxicity including control of uptake, sequestration inside the cell, oxidation, and efflux. The host response to infections combines this metal poisoning strategy with nutritional immunity mechanisms that deprive M. tuberculosis from metals such as iron and manganese to prevent bacterial replication. Both immune mechanisms rely on the translocation of metal transporter proteins to the phagosomal membrane during the maturation process of the phagosome. This review summarizes these recent findings and discusses how metal-targeted approaches might complement existing TB chemotherapeutic regimens with novel anti-infective therapies.

  8. Photochemistry of Transition Metal Hydrides.

    PubMed

    Perutz, Robin N; Procacci, Barbara

    2016-08-10

    Photochemical reactivity associated with metal-hydrogen bonds is widespread among metal hydride complexes and has played a critical part in opening up C-H bond activation. It has been exploited to design different types of photocatalytic reactions and to obtain NMR spectra of dilute solutions with a single pulse of an NMR spectrometer. Because photolysis can be performed on fast time scales and at low temperature, metal-hydride photochemistry has enabled determination of the molecular structure and rates of reaction of highly reactive intermediates. We identify five characteristic photoprocesses of metal monohydride complexes associated with the M-H bond, of which the most widespread are M-H homolysis and R-H reductive elimination. For metal dihydride complexes, the dominant photoprocess is reductive elimination of H2. Dihydrogen complexes typically lose H2 photochemically. The majority of photochemical reactions are likely to be dissociative, but hydride complexes may be designed with equilibrated excited states that undergo different photochemical reactions, including proton transfer or hydride transfer. The photochemical mechanisms of a few reactions have been analyzed by computational methods, including quantum dynamics. A section on specialist methods (time-resolved spectroscopy, matrix isolation, NMR, and computational methods) and a survey of transition metal hydride photochemistry organized by transition metal group complete the Review.

  9. Mycobacteria, Metals, and the Macrophage

    PubMed Central

    Niederweis, Michael; Wolschendorf, Frank; Mitra, Avishek; Neyrolles, Olivier

    2015-01-01

    Summary Mycobacterium tuberculosis is a facultative intracellular pathogen that thrives inside host macrophages. A key trait of M. tuberculosis is to exploit and manipulate metal cation trafficking inside infected macrophages to ensure survival and replication inside the phagosome. Here we describe the recent fascinating discoveries that the mammalian immune system responds to infections with M. tuberculosis by overloading the phagosome with copper and zinc, two metals which are essential nutrients in small quantities but are toxic in excess. M. tuberculosis has developed multi-faceted resistance mechanisms to protect itself from metal toxicity including control of uptake, sequestration inside the cell, oxidation, and efflux. The host response to infections combines this metal poisoning strategy with nutritional immunity mechanisms that deprive M. tuberculosis from metals such as iron and manganese to prevent bacterial replication. Both immune mechanisms rely on the translocation of metal transporter proteins to the phagosomal membrane during the maturation process of the phagosome. This review summarizes these recent findings and discusses how metal-targeted approaches might complement existing TB chemotherapeutic regimens with novel anti-infective therapies. PMID:25703564

  10. Mycobacteria, metals, and the macrophage.

    PubMed

    Neyrolles, Olivier; Wolschendorf, Frank; Mitra, Avishek; Niederweis, Michael

    2015-03-01

    Mycobacterium tuberculosis is a facultative intracellular pathogen that thrives inside host macrophages. A key trait of M. tuberculosis is to exploit and manipulate metal cation trafficking inside infected macrophages to ensure survival and replication inside the phagosome. Here, we describe the recent fascinating discoveries that the mammalian immune system responds to infections with M. tuberculosis by overloading the phagosome with copper and zinc, two metals which are essential nutrients in small quantities but are toxic in excess. M. tuberculosis has developed multi-faceted resistance mechanisms to protect itself from metal toxicity including control of uptake, sequestration inside the cell, oxidation, and efflux. The host response to infections combines this metal poisoning strategy with nutritional immunity mechanisms that deprive M. tuberculosis from metals such as iron and manganese to prevent bacterial replication. Both immune mechanisms rely on the translocation of metal transporter proteins to the phagosomal membrane during the maturation process of the phagosome. This review summarizes these recent findings and discusses how metal-targeted approaches might complement existing TB chemotherapeutic regimens with novel anti-infective therapies. PMID:25703564

  11. Metal-doped organic foam

    DOEpatents

    Rinde, James A.

    1982-01-01

    Organic foams having a low density and very small cell size and method for producing same in either a metal-loaded or unloaded (nonmetal loaded) form are described. Metal-doped foams are produced by soaking a polymer gel in an aqueous solution of desired metal salt, soaking the gel successively in a solvent series of decreasing polarity to remove water from the gel and replace it with a solvent of lower polarity with each successive solvent in the series being miscible with the solvents on each side and being saturated with the desired metal salt, and removing the last of the solvents from the gel to produce the desired metal-doped foam having desired density cell size, and metal loading. The unloaded or metal-doped foams can be utilized in a variety of applications requiring low density, small cell size foam. For example, rubidium-doped foam made in accordance with the invention has utility in special applications, such as in x-ray lasers.

  12. Thin-film metal hydrides.

    PubMed

    Remhof, Arndt; Borgschulte, Andreas

    2008-12-01

    The goal of the medieval alchemist, the chemical transformation of common metals into nobel metals, will forever be a dream. However, key characteristics of metals, such as their electronic band structure and, consequently, their electric, magnetic and optical properties, can be tailored by controlled hydrogen doping. Due to their morphology and well-defined geometry with flat, coplanar surfaces/interfaces, novel phenomena may be observed in thin films. Prominent examples are the eye-catching hydrogen switchable mirror effect, the visualization of solid-state diffusion and the formation of complex surface morphologies. Thin films do not suffer as much from embrittlement and/or decrepitation as bulk materials, allowing the study of cyclic absorption and desorption. Therefore, thin-metal hydride films are used as model systems to study metal-insulator transitions, for high throughput combinatorial research or they may be used as indicator layers to study hydrogen diffusion. They can be found in technological applications as hydrogen sensors, in electrochromic and thermochromic devices. In this review, we discuss the effect of hydrogen loading of thin niobium and yttrium films as archetypical examples of a transition metal and a rare earth metal, respectively. Our focus thereby lies on the hydrogen induced changes of the electronic structure and the morphology of the thin films, their optical properties, the visualization and the control of hydrogen diffusion and on the study of surface phenomena and catalysis.

  13. Quench Crucibles Reinforced with Metal

    NASA Technical Reports Server (NTRS)

    Holmes, Richard R.; Carrasquillo, Edgar; O'Dell, J. Scott; McKehnie, N.

    2008-01-01

    Improved crucibles consisting mainly of metal-reinforced ceramic ampules have been developed for use in experiments in which material specimens are heated in the crucibles to various high temperatures, then quenched by, for example, plunging the crucibles into water at room temperature. In a traditional quench crucible, the gap between the ampule and the metal cartridge impedes the transfer of heat to such a degree that the quench rate (the rate of cooling of the specimen) can be too low to produce the desired effect in the specimen. One can increase the quench rate by eliminating the metal cartridge to enable direct quenching of the ampule, but then the thermal shock of direct quenching causes cracking of the ampule. In a quench crucible of the present improved type, there is no gap and no metal cartridge in the traditional sense. Instead, there is an overlay of metal in direct contact with the ampule, as shown on the right side of the figure. Because there is no gap between the metal overlay and the ampule, the heat-transfer rate can be much greater than it is in a traditional quench crucible. The metal overlay also reinforces the ampule against cracking.

  14. Method of coating metal surfaces to form protective metal coating thereon

    DOEpatents

    Krikorian, Oscar H.; Curtis, Paul G.

    1992-01-01

    A process is disclosed for forming a protective metal coating on a metal surface using a flux consisting of an alkali metal fluoride, an alkaline earth metal fluoride, an alkali metal fluoaluminate, an alkali metal fluosilicate, and mixtures thereof. The flux, in particulate form, is mixed with particles of a metal coating material which may comprise aluminum, chromium, mixtures thereof, and alloys containing at least 50 wt. % aluminum and the particulate mixture is applied to the metal surface in a single step, followed by heating the coated metal surface to a temperature sufficient to cause the metal coating material to react with the metal surface to form a protective reaction product in the form of a metal coating bonded to the metal surface. The metal surface which reacts with the metal coating material to form the protective coating may comprise Fe, Co, Ni, Ti, V, Cr, Mn, Zr, Nb, Mo, Tc, Hf, Ta, W, Re and alloys thereof.

  15. Method of coating metal surfaces to form protective metal coating thereon

    DOEpatents

    Krikorian, O.H.; Curtis, P.G.

    1992-03-31

    A process is disclosed for forming a protective metal coating on a metal surface using a flux consisting of an alkali metal fluoride, an alkaline earth metal fluoride, an alkali metal fluoaluminate, an alkali metal fluosilicate, and mixtures thereof. The flux, in particulate form, is mixed with particles of a metal coating material which may comprise aluminum, chromium, mixtures thereof, and alloys containing at least 50 wt. % aluminum and the particulate mixture is applied to the metal surface in a single step, followed by heating the coated metal surface to a temperature sufficient to cause the metal coating material to react with the metal surface to form a protective reaction product in the form of a metal coating bonded to the metal surface. The metal surface which reacts with the metal coating material to form the protective coating may comprise Fe, Co, Ni, Ti, V, Cr, Mn, Zr, Nb, Mo, Tc, Hf, Ta, W, Re and alloys thereof. 1 figure.

  16. Thermal conductivity of metals

    NASA Technical Reports Server (NTRS)

    Kazem, Sayyed M.

    1990-01-01

    The objective is to familiarize students with steady and unsteady heat transfer by conduction and with the effect of thermal conductivity upon temperature distribution through a homogeneous substance. The elementary heat conduction experiment presented is designed for associate degree technology students in a simple manner to enhance their intuition and to clarify many confusing concepts such as temperature, thermal energy, thermal conductivity, heat, transient and steady flows. The equipment set is safe, small, portable (10 kg) and relatively cheap (about $1200): the electric hot plate 2 kg (4.4 lb) for $175: the 24 channel selector and Thermocouple Digital Readout (Trendicator) 4.5 kg (10 lb) for about $1000; the three metal specimens (each of 2.5 cm diameter and 11 cm length), base plate and the bucket all about 3 kg (7 lb) for about $25. The experiment may take from 60 to 70 minutes. Although the hot plate surface temperature could be set from 90 to 370 C (maximum of 750 watts) it is a good practice to work with temperatures of 180 to 200 C (about 400 watts). They may experiment in squads of 2, 3 or even 4, or the instructor may demonstrate it for the whole class.

  17. Introduction to metallic nanoparticles.

    PubMed

    Mody, Vicky V; Siwale, Rodney; Singh, Ajay; Mody, Hardik R

    2010-10-01

    Metallic nanoparticles have fascinated scientist for over a century and are now heavily utilized in biomedical sciences and engineering. They are a focus of interest because of their huge potential in nanotechnology. Today these materials can be synthesized and modified with various chemical functional groups which allow them to be conjugated with antibodies, ligands, and drugs of interest and thus opening a wide range of potential applications in biotechnology, magnetic separation, and preconcentration of target analytes, targeted drug delivery, and vehicles for gene and drug delivery and more importantly diagnostic imaging. Moreover, various imaging modalities have been developed over the period of time such as MRI, CT, PET, ultrasound, SERS, and optical imaging as an aid to image various disease states. These imaging modalities differ in both techniques and instrumentation and more importantly require a contrast agent with unique physiochemical properties. This led to the invention of various nanoparticulated contrast agent such as magnetic nanoparticles (Fe(3)O(4)), gold, and silver nanoparticles for their application in these imaging modalities. In addition, to use various imaging techniques in tandem newer multifunctional nanoshells and nanocages have been developed. Thus in this review article, we aim to provide an introduction to magnetic nanoparticles (Fe(3)O(4)), gold nanoparticles, nanoshells and nanocages, and silver nanoparticles followed by their synthesis, physiochemical properties, and citing some recent applications in the diagnostic imaging and therapy of cancer. PMID:21180459

  18. Introduction to metallic nanoparticles

    PubMed Central

    Mody, Vicky V.; Siwale, Rodney; Singh, Ajay; Mody, Hardik R.

    2010-01-01

    Metallic nanoparticles have fascinated scientist for over a century and are now heavily utilized in biomedical sciences and engineering. They are a focus of interest because of their huge potential in nanotechnology. Today these materials can be synthesized and modified with various chemical functional groups which allow them to be conjugated with antibodies, ligands, and drugs of interest and thus opening a wide range of potential applications in biotechnology, magnetic separation, and preconcentration of target analytes, targeted drug delivery, and vehicles for gene and drug delivery and more importantly diagnostic imaging. Moreover, various imaging modalities have been developed over the period of time such as MRI, CT, PET, ultrasound, SERS, and optical imaging as an aid to image various disease states. These imaging modalities differ in both techniques and instrumentation and more importantly require a contrast agent with unique physiochemical properties. This led to the invention of various nanoparticulated contrast agent such as magnetic nanoparticles (Fe3O4), gold, and silver nanoparticles for their application in these imaging modalities. In addition, to use various imaging techniques in tandem newer multifunctional nanoshells and nanocages have been developed. Thus in this review article, we aim to provide an introduction to magnetic nanoparticles (Fe3O4), gold nanoparticles, nanoshells and nanocages, and silver nanoparticles followed by their synthesis, physiochemical properties, and citing some recent applications in the diagnostic imaging and therapy of cancer. PMID:21180459

  19. Quinary metallic glass alloys

    DOEpatents

    Lin, X.; Johnson, W.L.

    1998-04-07

    At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10{sup 3}K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf){sub a}(Al,Zn){sub b}(Ti,Nb){sub c}(Cu{sub x}Fe{sub y}(Ni,Co){sub z}){sub d} wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d{hor_ellipsis}y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

  20. Mixed valent metals

    NASA Astrophysics Data System (ADS)

    Riseborough, P. S.; Lawrence, J. M.

    2016-08-01

    We review the theory of mixed-valent metals and make comparison with experiments. A single-impurity description of the mixed-valent state is discussed alongside the description of the nearly-integer valent or Kondo limit. The degeneracy N of the f-shell plays an important role in the description of the low-temperature Fermi-liquid state. In particular, for large N, there is a rapid cross-over between the mixed-valent and the Kondo limit when the number of f electrons is changed. We discuss the limitations on the application of the single-impurity description to concentrated compounds such as those caused by the saturation of the Kondo effect and those due to the presence of magnetic interactions between the impurities. This discussion is followed by a description of a periodic lattice of mixed-valent ions, including the role of the degeneracy N. The article concludes with a comparison of theory and experiment. Topics covered include the single-impurity Anderson model, Luttinger’s theorem, the Friedel sum rule, the Schrieffer–Wolff transformation, the single-impurity Kondo model, Kondo screening, the Wilson ratio, local Fermi-liquids, Fermi-liquid sum rules, the Noziéres exhaustion principle, Doniach’s diagram, the Anderson lattice model, the Slave-Boson method, etc.

  1. Laser generating metallic components

    NASA Astrophysics Data System (ADS)

    McLean, Marc A.; Shannon, G. J.; Steen, William M.

    1997-04-01

    Recent developments in rapid prototyping have led to the concept of laser generating, the first additive manufacturing technology. This paper presents an innovative process of depositing multi-layer tracks, by fusing successive powder tracks, to generate three dimensional components, thereby offering an alternative to casting for small metal component manufacture. A coaxial nozzle assembly has been designed and manufactured enabling consistent omni-directional multi-layer deposition. In conjunction with this the software route from a CAD drawing to machine code generation has been established. The part is manufactured on a six axes machining center incorporating a 1.8 kW carbon-dioxide laser, providing an integrated opto-mechanical workstation. The part build-up program is controlled by a P150 host computer, linked directly to the DNC machining center. The direct manufacturing route is shown, including initial examples of simple objects (primitives -- cube, cylinder, cone) leading to more complex turbine blade generation, incorporating build-up techniques and the associated mechanical properties.

  2. Quinary metallic glass alloys

    DOEpatents

    Lin, Xianghong; Johnson, William L.

    1998-01-01

    At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10.sup.3 K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf).sub.a (Al,Zn).sub.b (Ti,Nb).sub.c (Cu.sub.x Fe.sub.y (Ni,Co).sub.z).sub.d wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d.multidot.y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

  3. Mixed valent metals

    NASA Astrophysics Data System (ADS)

    Riseborough, P. S.; Lawrence, J. M.

    2016-08-01

    We review the theory of mixed-valent metals and make comparison with experiments. A single-impurity description of the mixed-valent state is discussed alongside the description of the nearly-integer valent or Kondo limit. The degeneracy N of the f-shell plays an important role in the description of the low-temperature Fermi-liquid state. In particular, for large N, there is a rapid cross-over between the mixed-valent and the Kondo limit when the number of f electrons is changed. We discuss the limitations on the application of the single-impurity description to concentrated compounds such as those caused by the saturation of the Kondo effect and those due to the presence of magnetic interactions between the impurities. This discussion is followed by a description of a periodic lattice of mixed-valent ions, including the role of the degeneracy N. The article concludes with a comparison of theory and experiment. Topics covered include the single-impurity Anderson model, Luttinger’s theorem, the Friedel sum rule, the Schrieffer-Wolff transformation, the single-impurity Kondo model, Kondo screening, the Wilson ratio, local Fermi-liquids, Fermi-liquid sum rules, the Noziéres exhaustion principle, Doniach’s diagram, the Anderson lattice model, the Slave-Boson method, etc.

  4. Metallic quantum ferromagnets

    NASA Astrophysics Data System (ADS)

    Brando, M.; Belitz, D.; Grosche, F. M.; Kirkpatrick, T. R.

    2016-04-01

    An overview of quantum phase transitions (QPTs) in metallic ferromagnets, discussing both experimental and theoretical aspects, is given. These QPTs can be classified with respect to the presence and strength of quenched disorder: Clean systems generically show a discontinuous, or first-order, QPT from a ferromagnetic to a paramagnetic state as a function of some control parameter, as predicted by theory. Disordered systems are much more complicated, depending on the disorder strength and the distance from the QPT. In many disordered materials the QPT is continuous, or second order, and Griffiths-phase effects coexist with QPT singularities near the transition. In other systems the transition from the ferromagnetic state at low temperatures is to a different type of long-range order, such as an antiferromagnetic or a spin-density-wave state. In still other materials a transition to a state with glasslike spin dynamics is suspected. The review provides a comprehensive discussion of the current understanding of these various transitions and of the relation between experiment and theory.

  5. [Lung disorders due to metals].

    PubMed

    Rüegger, M

    1995-03-11

    Though metals represent the largest group of elements they rather rarely cause respiratory diseases. This article will therefore review the most important ones caused by inhaled dusts of metals and some of their inorganic compounds, but leaving aside silicosis and silicatosis as well as iatrogenically induced metal pneumopathies. Among toxic inflammatory diseases metal fume fever, an influenza-like condition caused by zinc oxide, ranks as the commonest. Activities such as oxi-acetylene cutting and welding of zinc covered metal pieces account for about 90% of all cases compensated in Switzerland. Due to the non-recurrent character of this type of work, the typical waning of symptoms while exposure is going on has become seldom. Toxic pneumonia caused by inhaled metal fumes occurs rather seldom. However, serious cases have been reported where soldiers were exposed to zinc chloride from smoke bombs. The existence and extent of chronic airflow limitation due to occupational exposure to metallic dusts have not been widely examined but are to be assumed when there is poor occupational hygiene. Concerning asthma, there are at least four metals and several of their compounds which have been proven to cause variable airway narrowing, namely chromium, nickel, platinum and cobalt (the latter as hardmetal). Platinum complex salts (chloro-compounds) are very potent sensitizers leading to a notable prevalence of asthma among exposed workforces. Nevertheless, there have been no such cases in Switzerland for more than ten years. Hard-metal not only causes asthma but also an alveolitis-like interstitial lung disease progressing to fibrosis.(ABSTRACT TRUNCATED AT 250 WORDS)

  6. Metal nanoparticles functionalized with metal-ligand covalent bonds

    NASA Astrophysics Data System (ADS)

    Kang, Xiongwu

    Metal-organic contact has been recognized to play important roles in regulation of optical and electronic properties of nanoparticles. In this thesis, significant efforts have been devoted into synthesis of ruthenium nanoparticles with various metal-ligand interfacial linkages and investigation of their electronic and optical properties. Ruthenium nanoparticles were prepared by the self-assembly of functional group onto bare Ru colloid surface. As to Ru-alkyne nanoparticles, the formation of a Ru-vinylidene (Ru=C=CH--R) interfacial bonding linkage was confirmed by the specific reactivity of the nanoparticles with imine derivatives and olefin at the metal-ligand interface, as manifested in NMR, photoluminescence, and electrochemical measurements. Interestingly, it was found the electronic coupling coefficient (beta)for strongly depend upon such metal-ligand interfacial bonding. Next, such metal-ligand interfacial bonding was extended to ruthenium-nitrene pi bonds on ruthenium colloids, which were investigated by XPS. The nanoparticles exhibited a 1:1 atomic ratio of nitrogen to sulfur, consistent with that of sulfonyl nitrene fragments. In addition, the nanoparticle-bound nitrene moieties behaved analogously to azo derivatives, as manifested in UV-vis and fluorescence measurements. Further testimony of the formation of Ru=N interfacial linkages was highlighted in the unique reactivity of the nanoparticles with alkenes by imido transfer. Extensive conjugation between metal-ligand interfacial bond results in remarkable intraparticle charge delocalization on Ru-alkynide nanoparticles, which was manipulated by simple chemical reduction or oxidation. Charging of extra electrons into the nanoparticle cores led to an electron-rich metal core and hence red-shift of the triple bond stretching mode, lower binding energy of sp hybridized C 1s and dimmed fluorescence of nanoparticles. Instead, chemical oxidation resulted in the opposite impacts on these properties. By taking

  7. Self-Healing Metals and Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Ferguson, J. B.; Schultz, Benjamin F.; Rohatgi, Pradeep K.

    2014-06-01

    Self-healing in inorganic materials is a relatively new area in materials science and engineering that draws inspiration from biological systems that can self-repair damage. This article reviews the preliminary attempts to impart self-healing behavior to metals. Several challenges yet exist in the development of metallic alloys that can self-repair damage, including surface bonding issues, such as liquid/solid contact angle (wetting) and oxidation, and practical issues, such as capillary pressure for delivery of a liquid metal to a damaged area or crack, and the overall mechanical properties of a composite system. Although the applied research approaches reviewed have obtained marginal success, the development of self-healing metallic systems has the potential to benefit a wide range of industrial applications and thus deserves greater investment in fundamental research.

  8. Breast milk metal ion levels in a young and active patient with a metal-on-metal hip prosthesis.

    PubMed

    Nelis, Raymond; de Waal Malefijt, Jan; Gosens, Taco

    2013-01-01

    Metal-on-metal resurfacing arthroplasty of the hip has been used increasingly over the last 10 years in younger active patients. The dissolution of the metal wear particles results in measurable increases in cobalt and chromium ions in the serum and urine of patients with a metal-on-metal bearing. We measured the cobalt, chromium, and molybdenum ion levels in urine; serum; and breast milk in a young and active patient with a metal-on-metal hip prosthesis after a pathologic fracture of the femoral neck. Metal-on-metal hip prosthesis leads to increasing levels of molybdenum in breast milk in the short-term follow-up. There are no increasing levels of chromium and cobalt ions in breast milk. Besides the already known elevated concentrations in serum of chromium and cobalt after implantation of a metal-on-metal hip prosthesis, we found no increasing levels of chromium and cobalt in urine. PMID:22868068

  9. Asbestos and metals as carcinogens

    SciTech Connect

    Norseth, T.

    1980-09-01

    Increased incidences of lung carcinoma and pleural mesothelioma in humans exposed to asbestos have been irrefutably established. Different forms of asbestos may have different tumorigenic activities, depending on surface properties, durability, and size of the fibers. A number of metals, such as nickel, chromium and arsenic, are known to be carcinogenic to humans; for beryllium and cadmium the epidemiologic evidence is less extensive. All these metals also induce genetic toxicity in vitro. At present it cannot be concluded that all metals act by the same carcinogenic mechanism, even though direct modification of DNA seems to be the common experimental finding.

  10. Light metal explosives and propellants

    DOEpatents

    Wood, Lowell L.; Ishikawa, Muriel Y.; Nuckolls, John H.; Pagoria, Phillip F.; Viecelli, James A.

    2005-04-05

    Disclosed herein are light metal explosives, pyrotechnics and propellants (LME&Ps) comprising a light metal component such as Li, B, Be or their hydrides or intermetallic compounds and alloys containing them and an oxidizer component containing a classic explosive, such as CL-20, or a non-explosive oxidizer, such as lithium perchlorate, or combinations thereof. LME&P formulations may have light metal particles and oxidizer particles ranging in size from 0.01 .mu.m to 1000 .mu.m.

  11. CORROSION RESISTANT JACKETED METAL BODY

    DOEpatents

    Brugmann, E.W.

    1958-08-26

    S>Metal jacketed metallic bodies of the type used as feel elements fer nuclear reactors are presented. The fuel element is comprised of a plurality of jacketed cylindrical bodies joined in end to end abutting relationship. The abutting ends of the internal fissionable bodies are provided with a mating screw and thread means for joining the two together. The jacket material is of a corrosion resistant metal and overlaps the abutting ends of the internal bodies, thereby effectively sealing these bodies from contact with exteral reactive gases and liquids.

  12. Metal Stable Isotopes in Paleoceanography

    NASA Astrophysics Data System (ADS)

    Anbar, Ariel D.; Rouxel, Olivier

    2007-05-01

    Considered esoteric only a few years ago, research into the stable isotope geochemistry of transition metals is moving into the geoscience mainstream. Although initial attention focused on the potential use of some of these nontraditional isotope systems as biosignatures, they are now emerging as powerful paleoceanographic proxies. In particular, the Fe and Mo isotope systems are providing information about changes in oxygenation and metal cycling in ancient oceans. Zn, Cu, Tl, and a number of other metals and metalloids also show promise. Here we review the basis of stable isotope fractionation as it applies to these elements, analytical considerations, and the current status and future prospects of this rapidly developing research area.

  13. Metal ion-containing epoxies

    NASA Technical Reports Server (NTRS)

    Stoakley, D. M.; St.clair, A. K.

    1982-01-01

    A variety of metallic and organometallic complexes to be used as potential additives for an epoxy used by the aerospace industry as a composite matrix resin were investigated. A total of 9 complexes were screened for compatibility and for their ability to accelerate or inhibit the cure of a highly crosslinkable epoxy resin. Methods for combining the metallic complexes with the resin were investigated, gel times recorded, and cure exotherms studied by differential scanning calorimetry. Glass transition temperatures of cured metal ion containing epoxy castings were determined by thermomechanical analysis. Thermal stabilities of the castings were determined by thermogravimetric analysis. Mechanical strength and stiffness of these doped epoxies were also measured.

  14. EXPERIMENTAL LIQUID METAL FUEL REACTOR

    DOEpatents

    Happell, J.J.; Thomas, G.R.; Denise, R.P.; Bunts, J.L. Jr.

    1962-01-23

    A liquid metal fuel nuclear fission reactor is designed in which the fissionable material is dissolved or suspended in a liquid metal moderator and coolant. The liquid suspension flows into a chamber in which a critical amount of fissionable material is obtained. The fluid leaves the chamber and the heat of fission is extracted for power or other utilization. The improvement is in the support arrangement for a segrnented graphite core to permit dif ferential thermal expansion, effective sealing between main and blanket liquid metal flows, and avoidance of excessive stress development in the graphite segments. (AEC)

  15. Novel metals and metal complexes as platforms for cancer therapy.

    PubMed

    Frezza, Michael; Hindo, Sarmad; Chen, Di; Davenport, Andrew; Schmitt, Sara; Tomco, Dajena; Dou, Q Ping

    2010-06-01

    Metals are essential cellular components selected by nature to function in several indispensable biochemical processes for living organisms. Metals are endowed with unique characteristics that include redox activity, variable coordination modes, and reactivity towards organic substrates. Due to their reactivity, metals are tightly regulated under normal conditions and aberrant metal ion concentrations are associated with various pathological disorders, including cancer. For these reasons, coordination complexes, either as drugs or prodrugs, become very attractive probes as potential anticancer agents. The use of metals and their salts for medicinal purposes, from iatrochemistry to modern day, has been present throughout human history. The discovery of cisplatin, cis-[Pt(II) (NH(3))(2)Cl(2)], was a defining moment which triggered the interest in platinum(II)- and other metal-containing complexes as potential novel anticancer drugs. Other interests in this field address concerns for uptake, toxicity, and resistance to metallodrugs. This review article highlights selected metals that have gained considerable interest in both the development and the treatment of cancer. For example, copper is enriched in various human cancer tissues and is a co-factor essential for tumor angiogenesis processes. However the use of copper-binding ligands to target tumor copper could provide a novel strategy for cancer selective treatment. The use of nonessential metals as probes to target molecular pathways as anticancer agents is also emphasized. Finally, based on the interface between molecular biology and bioinorganic chemistry the design of coordination complexes for cancer treatment is reviewed and design strategies and mechanisms of action are discussed.

  16. Synthesis of Graphite Encapsulated Metal Nanoparticles and Metal Catalyzed Nanotubes

    NASA Technical Reports Server (NTRS)

    vanderWal, R. L.; Dravid, V. P.

    1999-01-01

    This work focuses on the growth and inception of graphite encapsulated metal nanoparticles and metal catalyzed nanotubes using combustion chemistry. Deciphering the inception and growth mechanism(s) for these unique nanostructures is essential for purposeful synthesis. Detailed knowledge of these mechanism(s) may yield insights into alternative synthesis pathways or provide data on unfavorable conditions. Production of these materials is highly desirable given many promising technological applications.

  17. Heavy Metal Stars

    NASA Astrophysics Data System (ADS)

    2001-08-01

    thereafter dies as a burnt-out, dim "white dwarf" . Stars with masses between 0.8 and 8 times that of the Sun are believed to evolve to AGB-stars and to end their lives in this particular way. At the same time, they produce beautiful nebulae like the "Dumbbell Nebula". Our Sun will also end its active life this way, probably some 7 billion years from now. Low-metallicity stars The detailed understanding of the "s-process" and, in particular, where it takes place inside an AGB-star, has been an area of active research for many years. Current state-of-the-art computer-based stellar models predict that the s-process should be particularly efficient in stars with a comparatively low content of metals ("metal-poor" or "low-metallicity" stars) . In such stars - which were born at an early epoch in our Galaxy and are therefore quite old - the "s-process" is expected to effectively produce atomic nuclei all the way up to the most heavy, stable ones, like Lead (atomic number 82 [2]) and Bismuth (atomic number 83) - since more neutrons are available per Iron-seed nucleus when there are fewer such nuclei (as compared to the solar composition). Once these elements have been produced, the addition of more s-process neutrons to those nuclei will only produce unstable elements that decay back to Lead. Hence, when the s-process is sufficiently efficient, atomic nuclei with atomic numbers around 82, that is, the Lead region, just continue to pile up. As a result, when compared to stars with "normal" abundances of the metals (like our Sun), those low-metallicity stars should thus exhibit a significant "over-abundance" of those very heavy elements with respect to Iron, in particular of Lead . Looking for Lead Direct observational support for this theoretical prediction would be the discovery of some low-metallicity stars with a high abundance of Lead. At the same time, the measured amounts of all the heavy elements and their relative abundances would provide very valuable information and

  18. Selenophene transition metal complexes

    SciTech Connect

    White, C.J.

    1994-07-27

    This research shows that selenophene transition metal complexes have a chemistry that is similar to their thiophene analogs. Selenophene coordination has been demonstrated and confirmed by molecular structure in both the {eta}{sup 5}- and the {eta}{sup 1}(Se)-coordination modes. The reaction chemistry of selenophene complexes closely resembles that of the analogous thiophene complexes. One major difference, however, is that selenophene is a better donor ligand than thiophene making the selenophene complexes more stable than the corresponding thiophene complexes. The {sup 77}Se NMR chemical shift values for selenophene complexes fall within distinct regions primarily depending on the coordination mode of the selenophene ligand. In the final paper, the C-H bond activation of {eta}{sup 1}(S)-bound thiophenes, {eta}{sup 1}(S)-benzothiophene and {eta}{sup 1}(Se)-bound selenophenes has been demonstrated. The deprotonation and rearrangement of the {eta}{sup 1}(E)-bound ligand to the carbon bound L-yl complex readily occurs in the presence of base. Reprotonation with a strong acid gives a carbene complex that is unreactive towards nucleophilic attack at the carbene carbon and is stable towards exposure to air. The molecular structure of [Cp(NO)(PPh{sub 3})Re(2-benzothioenylcarbene)]O{sub 3}SCF{sub 3} was determined and contains a Re-C bond with substantial double bond character. Methyl substitution for the thienylcarbene or selenylcarbene gives a carbene that rearranges thermally to give back the {eta}{sup 1}(E)-bound complex. Based on these model reactions, a new mechanism for the H/D exchange of thiophene over the hydrodesulfurization catalyst has been proposed.

  19. Methods for synthesizing metal oxide nanowires

    DOEpatents

    Sunkara, Mahendra Kumar; Kumar, Vivekanand; Kim, Jeong H.; Clark, Ezra Lee

    2016-08-09

    A method of synthesizing a metal oxide nanowire includes the steps of: combining an amount of a transition metal or a transition metal oxide with an amount of an alkali metal compound to produce a mixture; activating a plasma discharge reactor to create a plasma discharge; exposing the mixture to the plasma discharge for a first predetermined time period such that transition metal oxide nanowires are formed; contacting the transition metal oxide nanowires with an acid solution such that an alkali metal ion is exchanged for a hydrogen ion on each of the transition metal oxide nanowires; and exposing the transition metal oxide nanowires to the plasma discharge for a second predetermined time period to thermally anneal the transition metal oxide nanowires. Transition metal oxide nanowires produced using the synthesis methods described herein are also provided.

  20. Biofilm susceptibility to metal toxicity.

    PubMed

    Harrison, Joe J; Ceri, Howard; Stremick, Carol A; Turner, Raymond J

    2004-12-01

    This study compared bacterial biofilm and planktonic cell susceptibility to metal toxicity by evaluating the minimum inhibitory concentration (MIC), the planktonic minimum bactericidal concentration (MBC), and minimum biofilm eradication concentration (MBEC) using the MBEC device. In total, 17 metal cations and oxyanions, chosen to represent groups VIB to VIA of the periodic table, were each tested on biofilm and planktonic cultures of Escherichia coli JM109, Staphylococcus aureus ATCC 29213, and Pseudomonas aeruginosa ATCC 27853. In contrast to control antibiotic assays, where biofilm cultures were 2 to 64 times less susceptible to killing than logarithmically growing planktonic bacteria, metal compounds killed planktonic and biofilm cultures at the same concentration in the vast majority of combinations. Our data indicate that, under the conditions reported, growth in a biofilm does not provide resistance to bacteria against killing by metal cations or oxyanions.

  1. Metal containing polymeric functional microspheres

    NASA Technical Reports Server (NTRS)

    Yen, Shiao-Ping S. (Inventor); Rembaum, Alan (Inventor); Molday, Robert S. (Inventor)

    1979-01-01

    Polymeric functional microspheres containing metal or metal compounds are formed by addition polymerization of a covalently bondable olefinic monomer such as hydroxyethylmethacrylate in the presence of finely divided metal or metal oxide particles, such as iron, gold, platinum or magnetite, which are embedded in the resulting microspheres. The microspheres can be covalently bonded to chemotherapeutic agents, antibodies, or other proteins providing a means for labeling or separating labeled cells. Labeled cells or microspheres can be concentrated at a specific body location such as in the vicinity of a malignant tumor by applying a magnetic field to the location and then introducing the magnetically attractable microspheres or cells into the circulatory system of the subject. Labeled cells can be separated from a cell mixture by applying a predetermined magnetic field to a tube in which the mixture is flowing. After collection of the labeled cells, the magnetic field is discontinued and the labeled sub-cell population recovered.

  2. Method of producing metallic materials

    DOEpatents

    Branagan, Daniel J.

    2004-02-10

    The invention includes a method of producing a hard metallic material by forming a mixture containing at least 55% iron and at least one of B, C, Si and P. The mixture is formed into an alloy and cooled to form a metallic material having a hardness greater than about 9.2 GPa. The invention includes a method of forming a wire by combining a metal strip and a powder. The strip and the powder are rolled to form a wire containing at least 55% iron and from 2-7 additional elements including at least one of C, Si and B. The invention also includes a method of forming a hardened surface on a substrate by processing a solid mass to form a powder, applying the powder to a surface to form a layer containing metallic glass, and converting the glass to a crystalline material having a nanocrystalline grain size.

  3. Transition metal contacts to graphene

    SciTech Connect

    Politou, Maria De Gendt, Stefan; Heyns, Marc; Asselberghs, Inge; Radu, Iuliana; Conard, Thierry; Richard, Olivier; Martens, Koen; Huyghebaert, Cedric; Tokei, Zsolt; Lee, Chang Seung; Sayan, Safak

    2015-10-12

    Achieving low resistance contacts to graphene is a common concern for graphene device performance and hybrid graphene/metal interconnects. In this work, we have used the circular Transfer Length Method (cTLM) to electrically characterize Ag, Au, Ni, Ti, and Pd as contact metals to graphene. The consistency of the obtained results was verified with the characterization of up to 72 cTLM structures per metal. Within our study, the noble metals Au, Ag and Pd, which form a weaker bond with graphene, are shown to result in lower contact resistance (Rc) values compared to the more reactive Ni and Ti. X-ray Photo Electron Spectroscopy and Transmission Electron Microscopy characterization for the latter have shown the formation of Ti and Ni carbides. Graphene/Pd contacts show a distinct intermediate behavior. The weak carbide formation signature and the low Rc values measured agree with theoretical predictions of an intermediate state of weak chemisorption of Pd on graphene.

  4. Metal seal for wellhead apparatus

    SciTech Connect

    Boecker, R.A.

    1987-03-03

    A method is described of effecting a fluid-tight seal between a surface of an oil and/or gas well tubing or casing and a wellhead member, wherein the surface has been unprepared to form the seal, comprising the steps of: positioning the wellhead member circumferentially about a stub of the tubing or casing; positioning a metal-to-metal fluid-tight sealing means of the wellhead member adjacent the unprepared surface of the tubing or casing, the sealing means having at least one metallic projection positioned to extend toward the unprepared surface of the tubing or casing; and forcing the metallic projection into and penetrating the unprepared surface of the tubing or casing to form a seal therebetween.

  5. Metal structures with parallel pores

    NASA Technical Reports Server (NTRS)

    Sherfey, J. M.

    1976-01-01

    Four methods of fabricating metal plates having uniformly sized parallel pores are studied: elongate bundle, wind and sinter, extrude and sinter, and corrugate stack. Such plates are suitable for electrodes for electrochemical and fuel cells.

  6. Chapter 4 embedded metal fragments.

    PubMed

    Kalinich, John F; Vane, Elizabeth A; Centeno, Jose A; Gaitens, Joanna M; Squibb, Katherine S; McDiarmid, Melissa A; Kasper, Christine E

    2014-01-01

    The continued evolution of military munitions and armor on the battlefield, as well as the insurgent use of improvised explosive devices, has led to embedded fragment wounds containing metal and metal mixtures whose long-term toxicologic and carcinogenic properties are not as yet known. Advances in medical care have greatly increased the survival from these types of injuries. Standard surgical guidelines suggest leaving embedded fragments in place, thus individuals may carry these retained metal fragments for the rest of their lives. Nursing professionals will be at the forefront in caring for these wounded individuals, both immediately after the trauma and during the healing and rehabilitation process. Therefore, an understanding of the potential health effects of embedded metal fragment wounds is essential. This review will explore the history of embedded fragment wounds, current research in the field, and Department of Defense and Department of Veterans Affairs guidelines for the identification and long-term monitoring of individuals with embedded fragments.

  7. Electrography: A Metal Detective Story.

    ERIC Educational Resources Information Center

    Parrott, Sister Mary Ethel

    1983-01-01

    Electrography is a technique in which unknown metals are identified by the precipitates they form with known electrolytes. The technique illustrates both electrochemistry and precipitation reactions. Describes the technique, suggesting its use in science and forensic science classes. (JN)

  8. Manganese As a Metal Accumulator

    EPA Science Inventory

    Manganese deposits in water distribution systems accumulate metals, radionuclides and oxyanions by a combination of surface complexation, adsorption and solid substitution, as well as a combination of oxidation followed by manganese reduction and sorption of the oxidized constitu...

  9. Metal-Insulator-Semiconductor Photodetectors

    PubMed Central

    Lin, Chu-Hsuan; Liu, Chee Wee

    2010-01-01

    The major radiation of the Sun can be roughly divided into three regions: ultraviolet, visible, and infrared light. Detection in these three regions is important to human beings. The metal-insulator-semiconductor photodetector, with a simpler process than the pn-junction photodetector and a lower dark current than the MSM photodetector, has been developed for light detection in these three regions. Ideal UV photodetectors with high UV-to-visible rejection ratio could be demonstrated with III–V metal-insulator-semiconductor UV photodetectors. The visible-light detection and near-infrared optical communications have been implemented with Si and Ge metal-insulator-semiconductor photodetectors. For mid- and long-wavelength infrared detection, metal-insulator-semiconductor SiGe/Si quantum dot infrared photodetectors have been developed, and the detection spectrum covers atmospheric transmission windows. PMID:22163382

  10. Organometallic chemistry of metal surfaces

    SciTech Connect

    Muetterties, E.L.

    1981-06-01

    The organometallic chemistry of metal surfaces is defined as a function of surface crystallography and of surface composition for a set of cyclic hydrocarbons that include benzene, toluene, cyclohexadienes, cyclohexene, cyclohexane, cyclooctatetraene, cyclooctadienes, cyclooctadiene, cycloheptatriene and cyclobutane. 12 figures.

  11. Passivating metals on cracking catalysts

    SciTech Connect

    Mckay, D.L.

    1980-01-15

    Metals such as nickel, vanadium and iron contaminating a cracking catalyst are passivated by contacting the cracking catalyst under elevated temperature conditions with antimony selenide, antimony sulfide, antimony sulfate, bismuth selenide, bismuth sulfide, or bismuth phosphate.

  12. Organic Superconductor, Made without Metals.

    ERIC Educational Resources Information Center

    Science News, 1980

    1980-01-01

    The discovery of a superconducting organic compound is reported. The compound, (TMTSF)-2, has no metal in its composition, and the author believes that it is the precursor of a family of superconducting organics. (Author/SA)

  13. The Metallicity of Giant Planets

    NASA Astrophysics Data System (ADS)

    Thorngren, Daniel P.; Fortney, Jonathan

    2015-12-01

    Unique clues about the formation processes of giant planets can be found in their bulk compositions. Transiting planets provide us with bulk density determinations that can then be compared to models of planetary structure and evolution, to deduce planet bulk metallicities. At a given mass, denser planets have a higher mass fraction of metals. However, the unknown hot Jupiter "radius inflation" mechanism leads to under-dense planets that severely biases this work. Here we look at cooler transiting gas giants (Teff < 1000 K), which do not exhibit the radius inflation effect seen in their warmer cousins. We identified 40 such planets between 20 M_Earth and 20 M_Jup from the literature and used evolution models to determine their bulk heavy-element ("metal") mass. Several important trends are apparent. We see that all planets have at least ~10 M_Earth of metals, and that the mass of metal correlates strongly with the total mass of the planet. The heavy-element mass goes as the square root of the total mass. Both findings are consistent with the core accretion model. We also examined the effect of the parent star metallicity [Fe/H], finding that planets around high-metallicity stars are more likely to have large amounts of metal, but the relation appears weaker than previous studies with smaller sample sizes had suggested. We also looked for connections between bulk composition and planetary orbital parameters and stellar parameters, but saw no pattern, which is also an important result. This work can be directly compared to current and future outputs from planet formation models, including population synthesis.

  14. Solute diffusion in liquid metals

    NASA Technical Reports Server (NTRS)

    Bhat, B. N.

    1973-01-01

    A gas model of diffusion in liquid metals is presented. In this model, ions of liquid metals are assumed to behave like the molecules in a dense gas. Diffusion coefficient of solute is discussed with reference to its mass, ionic size, and pair potential. The model is applied to the case of solute diffusion in liquid silver. An attempt was made to predict diffusion coefficients of solutes with reasonable accuracy.

  15. Metals, Molecules, Life and Death

    SciTech Connect

    George, Graham

    2004-08-31

    In our normal everyday lives we are exposed to an incredibly complex chemical soup consisting of an enormous variety of different chemical compounds. Many of these compounds contain metal atoms which, once inside us, can either fulfill roles that are essential to health, or act as poisons. Studies at SLAC's Stanford Synchrotron Radiation Laboratory (SSRL) reveal the molecular details of metals in living systems; how they interact with one another, how they confer beneficial properties, and how they act as poisons.

  16. Vacuum distillation of americium metal

    SciTech Connect

    Berry, J W; Knighton, J B; Nannie, C A

    1982-01-22

    High-purity americium metal has been distilled in multigram quantities from a plutonium-americium alloy. The procedure consisted of a two-stage vacuum distillation carried out at 1200/sup 0/C and 10/sup -6/ torr pressure. Four batches of americium metal were produced ranging in weight from 13.3 grams to 54.1 grams. The purity of the americium product ranged from 99.27 to 99.79%.

  17. LIQUID METAL COMPOSITIONS CONTAINING URANIUM

    DOEpatents

    Teitel, R.J.

    1959-04-21

    Liquid metal compositions containing a solid uranium compound dispersed therein is described. Uranium combines with tin to form the intermetallic compound USn/sub 3/. It has been found that this compound may be incorporated into a liquid bath containing bismuth and lead-bismuth components, if a relatively small percentage of tin is also included in the bath. The composition has a low thermal neutron cross section which makes it suitable for use in a liquid metal fueled nuclear reactor.

  18. Actively convected liquid metal divertor

    NASA Astrophysics Data System (ADS)

    Shimada, Michiya; Hirooka, Yoshi

    2014-12-01

    The use of actively convected liquid metals with j × B force is proposed to facilitate heat handling by the divertor, a challenging issue associated with magnetic fusion experiments such as ITER. This issue will be aggravated even more for DEMO and power reactors because the divertor heat load will be significantly higher and yet the use of copper would not be allowed as the heat sink material. Instead, reduced activation ferritic/martensitic steel alloys with heat conductivities substantially lower than that of copper, will be used as the structural materials. The present proposal is to fill the lower part of the vacuum vessel with liquid metals with relatively low melting points and low chemical activities including Ga and Sn. The divertor modules, equipped with electrodes and cooling tubes, are immersed in the liquid metal. The electrode, placed in the middle of the liquid metal, can be biased positively or negatively with respect to the module. The j × B force due to the current between the electrode and the module provides a rotating motion for the liquid metal around the electrodes. The rise in liquid temperature at the separatrix hit point can be maintained at acceptable levels from the operation point of view. As the rotation speed increases, the current in the liquid metal is expected to decrease due to the v × B electromotive force. This rotating motion in the poloidal plane will reduce the divertor heat load significantly. Another important benefit of the convected liquid metal divertor is the fast recovery from unmitigated disruptions. Also, the liquid metal divertor concept eliminates the erosion problem.

  19. Metallization of Large Silicon Wafers

    NASA Technical Reports Server (NTRS)

    Pryor, R. A.

    1978-01-01

    A metallization scheme was developed which allows selective plating of silicon solar cell surfaces. The system is comprised of three layers. Palladium, through the formation of palladium silicide at 300 C in nitrogen, makes ohmic contact to the silicon surface. Nickel, plated on top of the palladium silicide layer, forms a solderable interface. Lead-tin solder on the nickel provides conductivity and allows a convenient means for interconnection of cells. To apply this metallization, three chemical plating baths are employed.

  20. Fractography handbook of spaceflight metals

    NASA Technical Reports Server (NTRS)

    Derro, Rebecca J.

    1993-01-01

    This handbook was produced with the intention of providing failure analysts who work with space flight metals a reference of scanning electron microscope (SEM) fractographs of fracture surfaces produced under known condition. The metals and the fracture conditions were chosen to simulate situations that are encountered in spaceflight applications. This includes tensile overload at both room temperature and liquid nitrogen temperature, and fatigue at room temperature.

  1. PRETREATING URANIUM FOR METAL PLATING

    DOEpatents

    Wehrmann, R.F.

    1961-05-01

    A process is given for anodically treating the surface of uranium articles, prior to metal plating. The metal is electrolyzed in an aqueous solution of about 10% polycarboxylic acid, preferably oxalic acid, from 1 to 5% by weight of glycerine and from 1 to 5% by weight of hydrochloric acid at from 20 to 75 deg C for from 30 seconds to 15 minutes. A current density of from 60 to 100 amperes per square foot is used.

  2. METHOD OF DISSOLVING URANIUM METAL

    DOEpatents

    Slotin, L.A.

    1958-02-18

    This patent relates to an economicai means of dissolving metallic uranium. It has been found that the addition of a small amount of perchloric acid to the concentrated nitric acid in which the uranium is being dissolved greatly shortens the time necessary for dissolution of the metal. Thus the use of about 1 or 2 percent of perchioric acid based on the weight of the nitric acid used, reduces the time of dissolution of uranium by a factor of about 100.

  3. Interaction of Burning Metal Particles

    NASA Technical Reports Server (NTRS)

    Dreizin, Edward L.; Berman, Charles H.; Hoffmann, Vern K.

    1999-01-01

    Physical characteristics of the combustion of metal particle groups have been addressed in this research. The combustion behavior and interaction effects of multiple metal particles has been studied using a microgravity environment, which presents a unique opportunity to create an "aerosol" consisting of relatively large particles, i.e., 50-300 micrometer diameter. Combustion behavior of such an aerosol could be examined using methods adopted from well-developed single particle combustion research. The experiment included fluidizing relatively large (order of 100 micrometer diameter) uniform metal particles under microgravity and igniting such an "aerosol" using a hot wire igniter. The flame propagation and details of individual particle combustion and particle interaction have been studied using a high speed movie and video-imaging with cameras coupled with microscope lenses to resolve individual particles. Interference filters were used to separate characteristic metal and metal oxide radiation bands form the thermal black body radiation. Recorded flame images were digitized and employed to understand the processes occurring in the burning aerosol. The development of individual particle flames, merging or separation, and extinguishing as well as induced particle motion have been analyzed to identify the mechanisms governing these processes. Size distribution, morphology, and elemental compositions of combustion products were characterized and used to link the observed in this project aerosol combustion phenomena with the recently expanded mechanism of single metal particle combustion.

  4. Interaction of Burning Metal Particles

    NASA Technical Reports Server (NTRS)

    Dreizin, Edward L.; Berman, Charles H.; Hoffmann, Vern K.

    1999-01-01

    Physical characteristics of the combustion of metal particle groups have been addressed in this research. The combustion behavior and interaction effects of multiple metal particles has been studied using a microgravity environment, which presents a unique opportunity to create an "aerosol" consisting of relatively large particles, i.e., 50-300 m diameter. Combustion behavior of such an aerosol could be examined using methods adopted from well-developed single particle combustion research. The experiment included fluidizing relatively large (order of 100 m diameter) uniform metal particles under microgravity and igniting such an "aerosol" using a hot wire igniter. The flame propagation and details of individual particle combustion and particle interaction have been studied using a high speed movie and video-imaging with cameras coupled with microscope lenses to resolve individual particles. Interference filters were used to separate characteristic metal and metal oxide radiation bands from the thermal black body radiation. Recorded flame images were digitized and various image processing techniques including flame position tracking, color separation, and pixel by pixel image comparison were employed to understand the processes occurring in the burning aerosol. The development of individual particle flames, merging or separation, and extinguishment as well as induced particle motion have been analyzed to identify the mechanisms governing these processes. Size distribution, morphology, and elemental compositions of combustion products were characterized and used to link the observed in this project aerosol combustion phenomena with the recently expanded mechanism of single metal particle combustion.

  5. Titanium metal: extraction to application

    SciTech Connect

    Gambogi, Joseph; Gerdemann, Stephen J.

    2002-09-01

    In 1998, approximately 57,000 tons of titanium metal was consumed in the form of mill products (1). Only about 5% of the 4 million tons of titanium minerals consumed each year is used to produce titanium metal, with the remainder primarily used to produce titanium dioxide pigment. Titanium metal production is primarily based on the direct chlorination of rutile to produce titanium tetrachloride, which is then reduced to metal using the Kroll magnesium reduction process. The use of titanium is tied to its high strength-to-weight ratio and corrosion resistance. Aerospace is the largest application for titanium. In this paper, we discuss all aspects of the titanium industry from ore deposits through extraction to present and future applications. The methods of both primary (mining of ore, extraction, and purification) and secondary (forming and machining) operations will be analyzed. The chemical and physical properties of titanium metal will be briefly examined. Present and future applications for titanium will be discussed. Finally, the economics of titanium metal production also are analyzed as well as the advantages and disadvantages of various alternative extraction methods.

  6. Criticality of metals and metalloids

    PubMed Central

    Graedel, T. E.; Harper, E. M.; Nassar, N. T.; Nuss, Philip; Reck, Barbara K.

    2015-01-01

    Imbalances between metal supply and demand, real or anticipated, have inspired the concept of metal criticality. We here characterize the criticality of 62 metals and metalloids in a 3D “criticality space” consisting of supply risk, environmental implications, and vulnerability to supply restriction. Contributing factors that lead to extreme values include high geopolitical concentration of primary production, lack of available suitable substitutes, and political instability. The results show that the limitations for many metals important in emerging electronics (e.g., gallium and selenium) are largely those related to supply risk; those of platinum group metals, gold, and mercury, to environmental implications; and steel alloying elements (e.g., chromium and niobium) as well as elements used in high-temperature alloys (e.g., tungsten and molybdenum), to vulnerability to supply restriction. The metals of most concern tend to be those available largely or entirely as byproducts, used in small quantities for highly specialized applications, and possessing no effective substitutes. PMID:25831527

  7. Metal detector technology data base

    SciTech Connect

    Porter, L.K.; Gallo, L.R.; Murray, D.W.

    1990-08-01

    The tests described in this report were conducted to obtain information on the effects target characteristics have on portal type metal detector response. A second purpose of the tests was to determine the effect of detector type and settings on the detection of the targets. Although in some cases comparison performance of different types and makes of metal detectors is found herein, that is not the primary purpose of the report. Further, because of the many variables that affect metal detector performance, the information presented can be used only in a general way. The results of these tests can show general trends in metal detection, but do little for making accurate predictions as to metal detector response to a target with a complex shape such as a handgun. The shape of an object and its specific metal content (both type and treatment) can have a significant influence on detection. Thus it should not be surprising that levels of detection for a small 100g stainless steel handgun are considerably different than for detection of the 100g stainless steel right circular cylinder that was used in these tests. 7 figs., 1 tab.

  8. Metal sponge for cryosorption pumping applications

    DOEpatents

    Myneni, G.R.; Kneisel, P.

    1995-12-26

    A system has been developed for adsorbing gases at high vacuum in a closed area. The system utilizes large surface clean anodized metal surfaces at low temperatures to adsorb the gases. The large surface clean anodized metal is referred to as a metal sponge. The metal sponge generates or maintains the high vacuum by increasing the available active cryosorbing surface area. 4 figs.

  9. Metal sponge for cryosorption pumping applications

    DOEpatents

    Myneni, Ganapati R.; Kneisel, Peter

    1995-01-01

    A system has been developed for adsorbing gases at high vacuum in a closed area. The system utilizes large surface clean anodized metal surfaces at low temperatures to adsorb the gases. The large surface clean anodized metal is referred to as a metal sponge. The metal sponge generates or maintains the high vacuum by increasing the available active cryosorbing surface area.

  10. Metal salt catalysts for enhancing hydrogen spillover

    DOEpatents

    Yang, Ralph T; Wang, Yuhe

    2013-04-23

    A composition for hydrogen storage includes a receptor, a hydrogen dissociating metal doped on the receptor, and a metal salt doped on the receptor. The hydrogen dissociating metal is configured to spill over hydrogen to the receptor, and the metal salt is configured to increase a rate of the spill over of the hydrogen to the receptor.

  11. Maskless laser writing of microscopic metallic interconnects

    DOEpatents

    Maya, Leon

    1995-01-01

    A method of forming a metal pattern on a substrate. The method includes depositing an insulative nitride film on a substrate and irradiating a laser beam onto the nitride film, thus decomposing the metal nitride into a metal constituent and a gaseous constituent, the metal constituent remaining in the nitride film as a conductive pattern.

  12. Maskless laser writing of microscopic metallic interconnects

    DOEpatents

    Maya, L.

    1995-10-17

    A method of forming a metal pattern on a substrate is disclosed. The method includes depositing an insulative nitride film on a substrate and irradiating a laser beam onto the nitride film, thus decomposing the metal nitride into a metal constituent and a gaseous constituent, the metal constituent remaining in the nitride film as a conductive pattern. 4 figs.

  13. Metal oxide nanostructures with hierarchical morphology

    DOEpatents

    Ren, Zhifeng; Lao, Jing Yu; Banerjee, Debasish

    2007-11-13

    The present invention relates generally to metal oxide materials with varied symmetrical nanostructure morphologies. In particular, the present invention provides metal oxide materials comprising one or more metallic oxides with three-dimensionally ordered nanostructural morphologies, including hierarchical morphologies. The present invention also provides methods for producing such metal oxide materials.

  14. BIOMETHYLATION AND ENVIRONMENTAL TRANSPORT OF METALS

    EPA Science Inventory

    Toxic heavy metals are ubiquitous in the environment. They are found as metal or oxide dust in air, metal ions attached to humic substances in surface and ground water, and as metal ions bound to soils and sediments. The transformations, mobilization, transport, and bioaccumulati...

  15. Anaerobic microbial remobilization of coprecipitated metals

    DOEpatents

    Francis, Arokiasamy J.; Dodge, Cleveland J.

    1994-10-11

    A process is provided for solubilizing coprecipitated metals. Metals in wastestreams are concentrated by treatment with an iron oxide coprecipitating agent. The coprecipitated metals are solubilized by contacting the coprecipitate with a bacterial culture of a Clostridium species ATCC 53464. The remobilized metals can then be recovered and recycled.

  16. Metal nanoparticles as a conductive catalyst

    SciTech Connect

    Coker, Eric N.

    2010-08-03

    A metal nanocluster composite material for use as a conductive catalyst. The metal nanocluster composite material has metal nanoclusters on a carbon substrate formed within a porous zeolitic material, forming stable metal nanoclusters with a size distribution between 0.6-10 nm and, more particularly, nanoclusters with a size distribution in a range as low as 0.6-0.9 nm.

  17. Impregnated metal-polymeric functional beads

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Volksen, Willi (Inventor)

    1978-01-01

    Amine containing polymeric microspheres such as polyvinyl pyridine are complexed with metal salts or acids containing metals such as gold, platinum or iron. After reduction with sodium borohydride, the salt is reduced to finely divided free metal or metal oxides, useful as catalysts. Microspheres containing covalent bonding sites can be used for labeling or separating proteins.

  18. Dispersion enhanced metal/zeolite catalysts

    DOEpatents

    Sachtler, Wolfgang M. H.; Tzou, Ming-Shin; Jiang, Hui-Jong

    1987-01-01

    Dispersion stabilized zeolite supported metal catalysts are provided as bimetallic catalyst combinations. The catalyst metal is in a reduced zero valent form while the dispersion stabilizer metal is in an unreduced ionic form. Representative catalysts are prepared from platinum or nickel as the catalyst metal and iron or chromium dispersion stabilizer.

  19. Dispersion enhanced metal/zeolite catalysts

    DOEpatents

    Sachtler, W.M.H.; Tzou, M.S.; Jiang, H.J.

    1987-03-31

    Dispersion stabilized zeolite supported metal catalysts are provided as bimetallic catalyst combinations. The catalyst metal is in a reduced zero valent form while the dispersion stabilizer metal is in an unreduced ionic form. Representative catalysts are prepared from platinum or nickel as the catalyst metal and iron or chromium dispersion stabilizer.

  20. Anaerobic microbial remobilization of coprecipitated metals

    DOEpatents

    Francis, A.J.; Dodge, C.J.

    1994-10-11

    A process is provided for solubilizing coprecipitated metals. Metals in waste streams are concentrated by treatment with an iron oxide coprecipitating agent. The coprecipitated metals are solubilized by contacting the coprecipitate with a bacterial culture of a Clostridium species ATCC 53464. The remobilized metals can then be recovered and recycled. 4 figs.

  1. Horizontal electromagnetic casting of thin metal sheets

    DOEpatents

    Hull, John R.; Lari, Robert J.; Praeg, Walter F.; Turner, Larry R.

    1987-01-01

    Thin metal sheets are cast by magnetically suspending molten metal deposited within a ferromagnetic yoke and between AC conducting coils and linearly displacing the magnetically levitated liquid metal while it is being cooled to form a solid metal sheet. Magnetic flux increases as the molten metal sheet moves downward and decreases as the molten metal sheet moves upward to stabilize the sheet and maintain it in equilibrium as it is linearly displaced and solidified by cooling gases. A conducting shield is electrically coupled to the molten metal sheet by means of either metal sheet engaging rollers or brushes on the solidified metal, and by means of an electrode in the vessel containing the molten metal thereby providing a return path for the eddy currents induced in the metal sheet by the AC coil generated magnetic flux. Variation in the geometry of the conducting shield allows the magnetic flux between the metal sheet and the conducting shield to be varied and the thickness in surface quality of the metal sheet to be controlled. Side guards provide lateral containment for the molten metal sheet and stabilize and shape the magnetic field while a leader sheet having electromagnetic characteristics similar to those of the metal sheet is used to start the casting process and precedes the molten metal sheet through the magnet and forms a continuous sheet therewith. The magnet may be either U-shaped with a single racetrack coil or may be rectangular with a pair of facing bedstead coils.

  2. Horizontal electromagnetic casting of thin metal sheets

    DOEpatents

    Hull, John R.; Lari, Robert J.; Praeg, Walter F.; Turner, Larry R.

    1988-01-01

    Thin metal sheets are cast by magnetically suspending molten metal deposited within a ferromagnetic yoke and between AC conducting coils and linearly displacing the magnetically levitated liquid metal while it is being cooled to form a solid metal sheet. Magnetic flux increases as the molten metal sheet moves downward and decreases as the molten metal sheet moves upward to stabilize the sheet and maintain it in equilibrium as it is linearly displaced and solidified by cooling gases. A conducting shield is electrically coupled to the molten metal sheet by means of either metal sheet engaging rollers or brushes on the solidified metal, and by means of an electrode in the vessel containing the molten metal thereby providing a return path for the eddy currents induced in the metal sheet by the AC coil generated magnetic flux. Variation in the geometry of the conducting shield allows the magnetic flux between the metal sheet and the conducting shield to be varied and the thickness in surface quality of the metal sheet to be controlled. Side guards provide lateral containment for the molten metal sheet and stabilize and shape the magnetic field while a leader sheet having electromagnetic characteristics similar to those of the metal sheet is used to start the casting process and precedes the molten metal sheet through the magnet and forms a continuous sheet therewith. The magnet may be either U-shaped with a single racetrack coil or may be rectangular with a pair of facing bedstead coils.

  3. Molten metal injector system and method

    DOEpatents

    Meyer, Thomas N.; Kinosz, Michael J.; Bigler, Nicolas; Arnaud, Guy

    2003-04-01

    Disclosed is a molten metal injector system including a holder furnace, a casting mold supported above the holder furnace, and a molten metal injector supported from a bottom side of the mold. The holder furnace contains a supply of molten metal having a metal oxide film surface. The bottom side of the mold faces the holder furnace. The mold defines a mold cavity for receiving the molten metal from the holder furnace. The injector projects into the holder furnace and is in fluid communication with the mold cavity. The injector includes a piston positioned within a piston cavity defined by a cylinder for pumping the molten metal upward from the holder furnace and injecting the molten metal into the mold cavity under pressure. The piston and cylinder are at least partially submerged in the molten metal when the holder furnace contains the molten metal. The cylinder further includes a molten metal intake for receiving the molten metal into the piston cavity. The molten metal intake is located below the metal oxide film surface of the molten metal when the holder furnace contains the molten metal. A method of injecting molten metal into a mold cavity of a casting mold is also disclosed.

  4. Stabilizing Crystal Oscillators With Melting Metals

    NASA Technical Reports Server (NTRS)

    Stephens, J. B.; Miller, C. G.

    1984-01-01

    Heat of fusion provides extended period of constant temperature and frequency. Crystal surrounded by metal in spherical container. As outside temperature rises to melting point of metal, metal starts to liquefy; but temperature stays at melting point until no solid metal remains. Potential terrestrial applications include low-power environmental telemetering transmitters and instrumentation transmitters for industrial processes.

  5. Impregnated metal-polymeric functional beads

    NASA Technical Reports Server (NTRS)

    Rembaum, Alan (Inventor); Volksen, Willi (Inventor)

    1980-01-01

    Amine containing polymeric microspheres such as polyvinyl pyridine are complexed with metal salts or acids containing metals such as gold, platinum or iron. After reduction with sodium borohydride, the salt is reduced to finely divided free metal or metal oxides, useful as catalysts. Microspheres containing covalent bonding sites can be used for labeling or separating proteins.

  6. Metal-metal bonding using silver/copper nanoparticles

    NASA Astrophysics Data System (ADS)

    Kobayashi, Y.; Maeda, T.; Yasuda, Y.; Morita, T.

    2016-08-01

    A method for producing nanoparticles composed of silver and copper and a metal-metal bonding technique using the silver/copper nanoparticles are proposed. The method consists of three steps. First, copper oxide nanoparticles are produced by mixing Cu(NO3)2 aqueous solution and NaOH aqueous solution. Second, copper metal nanoparticles are fabricated by reducing the copper oxide nanoparticles with hydrazine in the presence of poly(vinylpyrrolidone) (PVP). Third, silver/copper nanoparticles are synthesized by reducing Ag+ ions with hydrazine in the presence of the copper metal nanoparticles. Initial concentrations in the final silver/copper particle colloid, composed of 0.0075 M Cu2+, 0.0025 M Ag+, 1.0 g/L PVP, and 0.6 M hydrazine, produced silver/copper nanoparticles with an average size of 49 nm and a crystal size of 16.8 nm. Discs of copper metal were successfully bonded by the silver/copper nanoparticles under annealing at 400 °C and pressurizing at 1.2 MPa for 5 min in not only hydrogen gas but also nitrogen gas. The shear force required to separate the bonded discs was 22.3 MPa for the hydrogen gas annealing and 14.9 MPa for the nitrogen gas annealing (namely, 66.8 % of that for hydrogen gas annealing).

  7. Direct Nanoimprint of Metal Bilayer for Tunnable Metal Photonic Properties

    NASA Astrophysics Data System (ADS)

    Sung, Sangkeun; Kim, Chul-Hyun; Choi, Dae-Geun; Lee, Jihye; Choi, Jun-Hyuk; Lee, Eung-Sug

    2013-10-01

    Tunable metal optical properties were realized by directly nanoimprinting metal onto silver-coated poly(methyl methacrylate) (PMMA) bilayer glass substrates. Imprinting at elevated temperatures enabled the molding of a stamp pattern consisting of a hexagonal pillar array with a 265 nm diameter and 530 nm pitch size, which produced a corrugated-metal nanohole array. The transmittance of the sample imprinted at 200 °C and 50 bar was uniquely improved from below 20% to more than 30% in the visible-infrared region, and its reflectance was reduced by more than 65% compared to a reference sample. The optical properties of the investigated metal depended significantly on the imprint temperature and relatively less on the imprint pressure and deposited silver film thickness. The improved transmittance was obtained only for the direct-imprinted silver-PMMA and not when the silver was simply deposited onto the predefined PMMA pattern. The presented fabrication strategy enables the provision of accessible optical tunability as well as improved cost-labor effectiveness for metal nanostructuring.

  8. Heavy metal chelation in neurotoxic exposures.

    PubMed

    Jang, David H; Hoffman, Robert S

    2011-08-01

    Metals such as iron and copper are critical to living organisms, whereas other metals such as lead and arsenic have no known biologic role. Any metals in large amounts may cause toxicity. Many metals cause pervasive systemic effects involving the nervous system, which can be subtle in some cases. Although challenging, the diagnosis and treatment of metal poisoning can be made based on history, physical examination, and the proper use of metal testing. This article focuses on the use, and misuse, of chelation in the diagnosis and management of metal intoxication. PMID:21803213

  9. Inert anode containing base metal and noble metal useful for the electrolytic production of aluminum

    DOEpatents

    Ray, Siba P.; Liu, Xinghua

    2000-01-01

    An inert anode for production of metals such as aluminum is disclosed. The inert anode comprises a base metal selected from Cu and Ag, and at least one noble metal selected from Ag, Pd, Pt, Au, Rh, Ru, Ir and Os. The inert anode may optionally be formed of sintered particles having interior portions containing more base metal than noble metal and exterior portions containing more noble metal than base metal. In a preferred embodiment, the base metal comprises Cu, and the noble metal comprises Ag, Pd or a combination thereof.

  10. INEL metal recycle radioactive scrap metal survey report

    SciTech Connect

    Funk, D.M.

    1994-09-01

    DOE requested that inventory and characterization of radioactive scrap metal (RSM) be conducted across the DOE complex. Past studies have estimated the metal available from unsubstantiated sources. In meetings held in FY-1993, with seven DOE sites represented and several DOE-HQ personnel present, INEL personnel discovered that these numbers were not reliable and that large stockpiles did not exist. INEL proposed doing in-field measurements to ascertain the amount of RSM actually available. This information was necessary to determine the economic viability of recycling and to identify feed stock that could be used to produce containers for radioactive waste. This inventory measured the amount of RSM available at the selected DOE sites. Information gathered included radionuclide content and chemical form, general radiation field, alloy type, and mass of metal.

  11. Carbide-reinforced metal matrix composite by direct metal deposition

    NASA Astrophysics Data System (ADS)

    Novichenko, D.; Thivillon, L.; Bertrand, Ph.; Smurov, I.

    Direct metal deposition (DMD) is an automated 3D laser cladding technology with co-axial powder injection for industrial applications. The actual objective is to demonstrate the possibility to produce metal matrix composite objects in a single-step process. Powders of Fe-based alloy (16NCD13) and titanium carbide (TiC) are premixed before cladding. Volume content of the carbide-reinforced phase is varied. Relationships between the main laser cladding parameters and the geometry of the built-up objects (single track, 2D coating) are discussed. On the base of parametric study, a laser cladding process map for the deposition of individual tracks was established. Microstructure and composition of the laser-fabricated metal matrix composite objects are examined. Two different types of structures: (a) with the presence of undissolved and (b) precipitated titanium carbides are observed. Mechanism of formation of diverse precipitated titanium carbides is studied.

  12. Process for fabrication of metal oxide films

    SciTech Connect

    Tracy, C.E.; Benson, D.; Svensson, S.

    1990-07-17

    This invention is comprised of a method of fabricating metal oxide films from a plurality of reactants by inducing a reaction by plasma deposition among the reactants. The plasma reaction is effective for consolidating the reactants and producing thin films of metal oxides, e.g. electro-optically active transition metal oxides, at a high deposition rate. The presence of hydrogen during the plasma reaction enhances the deposition rate of the metal oxide. Various types of metal oxide films can be produced.

  13. Metal alkoxides and methods of making same

    DOEpatents

    Hentges, Patrick J.; Greene, Laura H.; Pafford, Margaret Mary; Westwood, Glenn; Klemperer, Walter G.

    2005-01-04

    A method of making a superconducting structure includes depositing a metal alkoxide on a surface of a metal and hydrolyzing the metal alkoxide on the surface to form a pinhole-free film. The metal is a superconductor. The metal alkoxide may be a compound of formula (I): where M is zirconium or hafnium, and the purity of the compound is at least 97% as measured by NMR spectroscopy.

  14. Mesoporous metal oxide graphene nanocomposite materials

    DOEpatents

    Liu, Jun; Aksay, Ilhan A.; Kou, Rong; Wang, Donghai

    2016-05-24

    A nanocomposite material formed of graphene and a mesoporous metal oxide having a demonstrated specific capacity of more than 200 F/g with particular utility when employed in supercapacitor applications. A method for making these nanocomposite materials by first forming a mixture of graphene, a surfactant, and a metal oxide precursor, precipitating the metal oxide precursor with the surfactant from the mixture to form a mesoporous metal oxide. The mesoporous metal oxide is then deposited onto a surface of the graphene.

  15. Reversible photodeposition and dissolution of metal ions

    DOEpatents

    Foster, Nancy S.; Koval, Carl A.; Noble, Richard D.

    1994-01-01

    A cyclic photocatalytic process for treating waste water containing metal and organic contaminants. In one embodiment of the method, metal ions are photoreduced onto the photocatalyst and the metal concentrated by resolubilization in a smaller volume. In another embodiment of the method, contaminant organics are first oxidized, then metal ions removed by photoreductive deposition. The present invention allows the photocatalyst to be recycled until nearly complete removal of metal ions and organic contaminants is achieved.

  16. Method of bonding metals to ceramics

    DOEpatents

    Maroni, V.A.

    1991-04-23

    A ceramic or glass having a thin layer of silver, gold or alloys thereof at the surface thereof is disclosed. A first metal is bonded to the thin layer and a second metal is bonded to the first metal. The first metal is selected from the class consisting of In, Ga, Sn, Bi, Zn, Cd, Pb, Tl and alloys thereof, and the second metal is selected from the class consisting of Cu, Al, Pb, Au and alloys thereof. 3 figures.

  17. Method of bonding metals to ceramics

    DOEpatents

    Maroni, Victor A.

    1991-01-01

    A ceramic or glass having a thin layer of silver, gold or alloys thereof at the surface thereof. A first metal is bonded to the thin layer and a second metal is bonded to the first metal. The first metal is selected from the class consisting of In, Ga, Sn, Bi, Zn, Cd, Pb, Tl and alloys thereof, and the second metal is selected from the class consisting of Cu, Al, Pb, An and alloys thereof.

  18. Coated Metal Articles and Method of Making

    DOEpatents

    Boller, Ernest R.; Eubank, Lowell D.

    2004-07-06

    The method of protectively coating metallic uranium which comprises dipping the metallic uranium in a molten alloy comprising about 20-75% of copper and about 80-25% of tin, dipping the coated uranium promptly into molten tin, withdrawing it from the molten tin and removing excess molten metal, thereupon dipping it into a molten metal bath comprising aluminum until it is coated with this metal, then promptly withdrawing it from the bath.

  19. Coated metal articles and method of making

    DOEpatents

    Boller, Ernest R.; Eubank, Lowell D.

    2004-07-06

    The method of protectively coating metallic uranium which comprises dipping the metallic uranium in a molten alloy comprising about 20-75% of copper and about 80-25% of tin, dipping the coated uranium promptly into molten tin, withdrawing it from the molten tin and removing excess molten metal, thereupon dipping it into a molten metal bath comprising aluminum until it is coated with this metal, then promptly withdrawing it from the bath.

  20. Semiconductor assisted metal deposition for nanolithography applications

    DOEpatents

    Rajh, Tijana; Meshkov, Natalia; Nedelijkovic, Jovan M.; Skubal, Laura R.; Tiede, David M.; Thurnauer, Marion

    2001-01-01

    An article of manufacture and method of forming nanoparticle sized material components. A semiconductor oxide substrate includes nanoparticles of semiconductor oxide. A modifier is deposited onto the nanoparticles, and a source of metal ions are deposited in association with the semiconductor and the modifier, the modifier enabling electronic hole scavenging and chelation of the metal ions. The metal ions and modifier are illuminated to cause reduction of the metal ions to metal onto the semiconductor nanoparticles.

  1. Semiconductor assisted metal deposition for nanolithography applications

    DOEpatents

    Rajh, Tijana; Meshkov, Natalia; Nedelijkovic, Jovan M.; Skubal, Laura R.; Tiede, David M.; Thurnauer, Marion

    2002-01-01

    An article of manufacture and method of forming nanoparticle sized material components. A semiconductor oxide substrate includes nanoparticles of semiconductor oxide. A modifier is deposited onto the nanoparticles, and a source of metal ions are deposited in association with the semiconductor and the modifier, the modifier enabling electronic hole scavenging and chelation of the metal ions. The metal ions and modifier are illuminated to cause reduction of the metal ions to metal onto the semiconductor nanoparticles.

  2. Valence-Bond Concepts in Coordination Chemistry and the Nature of Metal-Metal Bonds.

    ERIC Educational Resources Information Center

    Pauling, Linus; Herman, Zelek S.

    1984-01-01

    Discusses the valence-bond method, applying it to some coordination compounds of metals, especially those involving metal-metal bonds. Suggests that transition metals can form as many as nine covalent bonds, permitting valence-theory to be extended to transition metal compounds in a more effective way than has been possible before. (JN)

  3. Process Of Bonding A Metal Brush Structure To A Planar Surface Of A Metal Substrate

    DOEpatents

    Slattery, Kevin T.; Driemeyer, Daniel E.; Wille; Gerald W.

    1999-11-02

    Process for bonding a metal brush structure to a planar surface of a metal substrate in which an array of metal rods are retained and immobilized at their tips by a common retention layer formed of metal, and the brush structure is then joined to a planar surface of a metal substrate via the retention layer.

  4. THE METAL CARBONYLS.

    PubMed

    Blanchard, A A

    1941-10-01

    When the metal carbonyls were first discovered, their properties were startling because they seemed to violate nearly all the previously recognized generalizations of chemistry. Even to-day the existence of the carbonyls is not particularly emphasized in elementary courses of chemistry because it is rather hard to reconcile them with the first presentations of the generalizations of chemistry. Nevertheless, as the student progresses deeper into the knowledge of chemistry it becomes desirable to include the knowledge of the carbonyls both because they become more comprehensible when viewed in the light of Werner's system of coordination and because they themselves contribute to the comprehension of the Werner theory. As long ago as 1931, Reiff in his discussion of cobalt nitrosyl carbonyl recognized the correlation between the effective atomic number and the volatility of carbonyls. A more recent study of charged Werner coordination complexes, that is, of complex ions, has shown a similar role of the effective atomic number. We are standing on fairly firm ground when we point out the correlation between E.A.N. and the volatility of the carbonyl complexes and the existence of complex ions. Be it noted that we have made no postulates as to the arrangement of the electrons in quantum levels. In the inert gases the outer principal quantum group is supposed always to contain eight electrons. In the carbonyls and other Werner complexes there is no compelling reason to suppose that the electrons in the coordinating layer, be this layer of eight, ten, twelve or sixteen electrons, are not all at the same energy level. Although we have confined our discussion almost exclusively to the property of volatility, the carbonyls are very interesting from the standpoint of several other properties, for example, magnetic susceptibility and dielectric constant. Enthusiasts in the interpretation of such properties try to draw conclusions as to the condition of the electrons, sometimes

  5. Metal Compression Forming of aluminum alloys and metal matrix composites

    SciTech Connect

    Viswanathan, S.; Ren, W.; Porter, W.D.; Brinkman, C.R.; Sabau, A.S.; Purgert, R.M.

    2000-02-01

    Metal Compression Forming (MCF) is a variant of the squeeze casting process, in which molten metal is allowed to solidify under pressure in order to close porosity and form a sound part. However, the MCF process applies pressure on the entire mold face, thereby directing pressure on all regions of the casting and producing a uniformly sound part. The process is capable of producing parts with properties close to those of forgings, while retaining the near net shape, complexity in geometry, and relatively low cost of the casting process.

  6. Metal induced gap states at alkali halide/metal interface

    NASA Astrophysics Data System (ADS)

    Kiguchi, Manabu; Yoshikawa, Genki; Ikeda, Susumu; Saiki, Koichiro

    2004-10-01

    The electronic state of a KCl/Cu(0 0 1) interface was investigated using the Cl K-edge near-edge X-ray absorption fine structure (NEXAFS). A pre-peak observed on the bulk edge onset of thin KCl films has a similar feature to the peak at a LiCl/Cu(0 0 1) interface, which originates from the metal induced gap state (MIGS). The present result indicates that the MIGS is formed universally at alkali halide/metal interfaces. The decay length of MIGS to an insulator differs from each other, mainly due to the difference in the band gap energy of alkali halide.

  7. Formation of metallic and metal hydrous oxide dispersions

    NASA Technical Reports Server (NTRS)

    Matijevic, E.; Sapieszko, R. S.

    1979-01-01

    The formation, via hydrothermally induced precipitation from homogeneous solution, of a variety of well-defined dispersions of metallic and hydrous metal in the conditions under which the particles are produced (e.g., pH and composition of the growth medium, aging temperature, rate of heating, or degree of agitation) can be readily discerned by following changes in the mass, composition, and morphology of the final solid phase. The generation of colloidal dispersions in the absence of gravity convection or sedimentation effects may result in the appearance of morphological modifications not previously observed in terrestrially formed hydrosols.

  8. Luminescence from electroformed metal-isolator-metal-structures

    NASA Astrophysics Data System (ADS)

    Bischoff, Manfred

    The electroluminescence from metal-isolator-metal diodes is measured with a photon counter. From the time dependance of the electron temperature and density it appears that the electrons are not heated in the conduction band of the separating isolator or in vaccuum between the electrodes but in a highly degenerated semiconductor. The experimental results show that the grid temperature of the semiconductor filament material in case of a voltage pulse adds up to 1,500 K. The temperature of the hot electrons drops from 3,000 to 2,000 K. The charge carrier density and the recombination rate also increase.

  9. Analysis of metal-metal contacts in RF MEMS switches

    NASA Astrophysics Data System (ADS)

    Kurth, Steffen; Voigt, Sven; Haas, Sven; Bertz, Andreas; Kaufmann, Christian; Gessner, Thomas; Akiba, Akira; Ikeda, Koichi

    2013-03-01

    This contribution reports on the analysis of metal-metal contacts of MEMS switches. A novel high aspect ratio MEMS fabrication sequence in combination with wafer level packaging is applied for fabrication of an RF MEMS switch with lateral motion. It allows for a relatively large actuation electrode area in a small package, and for high actuation force even with an actuation voltage of 5 V. The focus of this contribution is on the contact behavior. It is shown how operation conditions as like as actuation voltage, RF power, and DC bias influence the contact resistance. The power handling capability and its influence on the contacts, and the intermodulation were investigated also.

  10. Hidden scale invariance of metals

    NASA Astrophysics Data System (ADS)

    Hummel, Felix; Kresse, Georg; Dyre, Jeppe C.; Pedersen, Ulf R.

    2015-11-01

    Density functional theory (DFT) calculations of 58 liquid elements at their triple point show that most metals exhibit near proportionality between the thermal fluctuations of the virial and the potential energy in the isochoric ensemble. This demonstrates a general "hidden" scale invariance of metals making the condensed part of the thermodynamic phase diagram effectively one dimensional with respect to structure and dynamics. DFT computed density scaling exponents, related to the Grüneisen parameter, are in good agreement with experimental values for the 16 elements where reliable data were available. Hidden scale invariance is demonstrated in detail for magnesium by showing invariance of structure and dynamics. Computed melting curves of period three metals follow curves with invariance (isomorphs). The experimental structure factor of magnesium is predicted by assuming scale invariant inverse power-law (IPL) pair interactions. However, crystal packings of several transition metals (V, Cr, Mn, Fe, Nb, Mo, Ta, W, and Hg), most post-transition metals (Ga, In, Sn, and Tl), and the metalloids Si and Ge cannot be explained by the IPL assumption. The virial-energy correlation coefficients of iron and phosphorous are shown to increase at elevated pressures. Finally, we discuss how scale invariance explains the Grüneisen equation of state and a number of well-known empirical melting and freezing rules.

  11. All-Metal Magnetic RAM

    NASA Technical Reports Server (NTRS)

    Torok, E. J.; Spitzer, R.

    2000-01-01

    The factors that enter into the development of an all-metal, nonvolatile magnetic RAM, in which multilayer giant magnetoresistive films are used for all functions - storage, readout, and support electronics - are described. Four significant characteristics are expected to favor all-metal over hybrid magnetic RAM. First, silicon-technology fabrication requires a large number of masking steps, including complex ones such as ion implantation. Conversely, all-metal technology is inherently simple: fewer masking steps, no doping, scaling to lithographic limits, very little operating power. Second, the all-metal footprint is significantly smaller than the hybrid one. Third, an all-metal RAM is expected to be able to be miniaturized to lithographic limits; miniaturization of hybrid magnetic RAMs is likely to be limited by the semiconductor circuitry. Finally, semiconductor processing and magnetic processing in MRAM are done separately because the former requires high temperatures, whereas magnetic fabrication is a low-temperature process. By contrast, because both GMR electronics and the memory elements are made of the same materials, the two major components are deposited and patterned concurrently on the same substrate.

  12. Sputter Deposition of Metallic Sponges

    SciTech Connect

    Jankowski, A F; Hayes, J P

    2002-01-18

    Metallic films are grown with a sponge-like morphology in the as-deposited condition using planar magnetron sputtering. The morphology of the deposit is characterized by metallic continuity in three dimensions with continuous porosity on the sub-micron scale. The stabilization of the metallic sponge is directly correlated with a limited range for the sputter deposition parameters of working gas pressure and substrate temperature. This sponge-like morphology augments the features as generally understood in the classic zone models of growth for physical vapor deposits. Nickel coatings are deposited with working gas pressures up to 4 Pa and for substrate temperatures up to 1100 K. The morphology of the deposits is examined in plan and in cross-section with scanning electron microscopy. The parametric range of gas pressure and substrate temperature (relative to absolute melt point) for the deposition processing under which the metallic sponges are produced appear universal for many metals, as for example, including gold, silver, and aluminum.

  13. Zone refining of plutonium metal

    SciTech Connect

    Blau, M.S.

    1994-08-01

    The zone refining process was applied to Pu metal containing known amounts of impurities. Rod specimens of plutonium metal were melted into and contained in tantalum boats, each of which was passed horizontally through a three-turn, high-frequency coil in such a manner as to cause a narrow molten zone to pass through the Pu metal rod 10 times. The impurity elements Co, Cr, Fe, Ni, Np, U were found to move in the same direction as the molten zone as predicted by binary phase diagrams. The elements Al, Am, and Ga moved in the opposite direction of the molten zone as predicted by binary phase diagrams. As the impurity alloy was zone refined, {delta}-phase plutonium metal crystals were produced. The first few zone refining passes were more effective than each later pass because an oxide layer formed on the rod surface. There was no clear evidence of better impurity movement at the slower zone refining speed. Also, constant or variable coil power appeared to have no effect on impurity movement during a single run (10 passes). This experiment was the first step to developing a zone refining process for plutonium metal.

  14. Metal-metal multiple bonding in C3-symmetric bimetallic complexes of the first row transition metals.

    PubMed

    Krogman, Jeremy P; Thomas, Christine M

    2014-05-25

    Metal-metal multiple bonds have been an intense area of focus in inorganic chemistry for many decades as a result of their fundamentally interesting bonding properties, as well as their potential applications in multielectron transfer and small molecule activation processes. Much of what is known in this field revolves around 2nd and 3rd row transition metals, with fundamental knowledge lacking in the area of bonds between elements of the first transition series. The smaller size and tendency of first row ions to adopt high-spin electron configurations weaken metal-metal interactions and serve to complicate the interpretation of the electronic structure and bonding in bimetallic species containing first row transition metals. Furthermore, traditional tetragonal "paddlewheel" complexes dominate the metal-metal multiple bond literature, and only recently have researchers begun to take advantage of the weaker ligand field in three-fold symmetric bimetallic complexes to encourage more favourable metal-metal bonding interactions. In the past 5 years, several research groups have exploited three-fold symmetric frameworks to investigate new trends in metal-metal bonding involving the first row transition metals. This feature article serves to highlight recent achievements in this area and to use C3-symmetric systems as a model to better understand the fundamental aspects of multiple bonds featuring first row transition metals.

  15. Nanoscale metal-organic materials.

    PubMed

    Carné, Arnau; Carbonell, Carlos; Imaz, Inhar; Maspoch, Daniel

    2011-01-01

    Metal-organic materials are found to be a fascinating novel class of functional nanomaterials. The limitless combinations between inorganic and organic building blocks enable researchers to synthesize 0- and 1-D metal-organic discrete nanostructures with varied compositions, morphologies and sizes, fabricate 2-D metal-organic thin films and membranes, and even structure them on surfaces at the nanometre length scale. In this tutorial review, the synthetic methodologies for preparing these miniaturized materials as well as their potential properties and future applications are discussed. This review wants to offer a panoramic view of this embryonic class of nanoscale materials that will be of interest to a cross-section of researchers working in chemistry, physics, medicine, nanotechnology, materials chemistry, etc., in the next years.

  16. The Outer Halo Metallicity Distribution

    NASA Astrophysics Data System (ADS)

    MA, ZHIBO; Morrison, H.; Harding, P.; Xue, X.; Rix, H.; Rockosi, C.; Johnson, J.; Lee, Y.; Cudworth, K.

    2012-01-01

    We present a new determination of the metallicity distribution function in the Milky Way halo, based on an in situ sample of more than 5000 K giants from SDSS/SEGUE. We have also measured the metallicity gradient in the halo, using our sample which stretches from 5 kpc to more than 100 kpc from the galactic center. The halo metallicity gradient has been a controversial topic in recent studies, but our in-situ study overcomes the problems caused in these studies by their extrapolations from local samples to the distant halo. We also describe our extensive checks of the log g and [Fe/H] measurements from the SEGUE Stellar Parameters pipeline, using globular and open cluster stars and SEGUE stars with follow-up high-resolution analysis. In addition, we present a new Bayesian estimate of distances to the K giants, which avoids the distance bias introduced by the red giant branch luminosity function.

  17. Jumplike microdeformation of nanostructured metals

    NASA Astrophysics Data System (ADS)

    Peschanskaya, N. N.; Smirnov, B. I.; Shpeĭzman, V. V.

    2008-05-01

    The parameters of microdeformation jumps for copper, aluminum, titanium, and Armco iron with the initial (annealed) structure and after equal-channel angular pressing are investigated in a creep mode under low compressive stresses. The strain rate is measured with a laser interferometer in 0.15-μm linear displacements. It is demonstrated that the values of the microstrain rate and the mean sizes of jumps for the annealed metals are larger than those for the metals subjected to severe deformation. It is revealed that there is a correlation between the jumps of microplastic deformation and the size of nanometal grains. The inference is made that, for nanostructured metals, as for other materials, the structural heterogeneity is one of the factors responsible for the jumplike deformation.

  18. Nuclear Scattering from Transition Metals

    NASA Astrophysics Data System (ADS)

    Hira, Ajit; McKeough, James; Valerio, Mario; Cathey, Tommy

    2016-03-01

    In view of the continued interest in the scattering of light projectiles by metallic nuclei, we present a computational study of the interactions between different nuclear species of atoms such as H through F (Z <= 9) and the nuclei of Silver, Palladium and other metals. Recent work has shown that neutron scattering can be used to record holographic images of materials. We have developed a FORTRAN computer program to compute stopping cross sections and scattering angles in Ag and other metals for the small nuclear projectiles, using Monte Carlo calculation. This code allows for different angles of incidence. Next, simulations were done in the energy interval from 50 to 210 keV. The computational results thus obtained are compared with relevant experimental data. The data are further analyzed to identify periodic trends in terms of the atomic number of the projectile. Such studies also have potential applications in nuclear physics and in nuclear medicine. Funding from National Science Foundation.

  19. Mechanics of plutonium metal aerosolization

    SciTech Connect

    Alvis, J.M.

    1996-06-01

    Reliable estimates of hazards posed by a plutonium release are contingent on the availability of technical data to define the source term for aerosolization of plutonium oxide particles and the resulting size distribution. The release of aerosols from the oxidation of plutonium metal depends partly on the forces acting on the particles while they remain attached to the bulk material and partly on the ability of the airstream around the metal ingot to transport the particles when they detach. The forces that attach or detach the plutonium oxide particles can be described as binding of the particle to the metal or oxide layer around it and expansion and contraction stresses and external vibration. Experimental data forms the basis for defining size distributions and release fractions for plutonium oxide. The relevance of the data must be evaluated in the light of the chemical and physical properties of plutonium metal, plutonium oxide, and intermediate Plutonium compounds. The effects of temperature on reaction kinetics must also be understood when evaluating experimental data. Size distribution functions are remarkably similar for products of all Pu+gas reactions. The distributions are all bimodal. Marked differences are seen in the sizes of large particles depending on reaction temperature and reaction rate. However, the size distributions of small particles are very similar. The bimodal distribution of small particles vanishes as the sizes of the large particles decrease to the point of equal dimensions with the small particles. This is the situation realized for the fine plutonium oxide powder produced by air oxidation at room temperature. This report addresses important factors for defining the formation of an aerosol from the oxidation of plutonium metal. These factors are oxidation kinetics of plutonium metal and plutonium hydride, the particle distribution of products formed by the reactions, and the kinetics of processes limiting entrainment of particles.

  20. Quantum Conductance in Metal Nanowires

    NASA Astrophysics Data System (ADS)

    Ugarte, Daniel

    2004-03-01

    Quantum Conductance in Metal Nanowires D. Ugarte Brazilian National Synchrotron Light Laboratory C.P. 6192, 13084-971 Campinas SP, Brazil. Electrical transport properties of metallic nanowires (NWs) have received great attention due to their quantum conductance behavior. Atomic scale wires can be generated by stretching metal contacts; during the elongation and just before rupture, the NW conductance shows flat plateaus and abrupt jumps of approximately a conductance quantum. In this experiments, both the NW atomic arrangement and conductance change simultaneously, making difficult to discriminate electronic and structural effects. In this work, the atomic structure of NWs was studied by time-resolved in situ experiments in a high resolution transmission electron microscope, while their electrical properties using an UHV mechanically controllable break junction (MCBJ). From the analysis of numerous HRTEM images and videos, we have deduced that metal (Au, Ag, Pt, etc.) junctions generated by tensile deformation are crystalline and free of defects. The neck structure is strongly dependent on the surface properties of the analyzed metal, this was verified by comparing different metal NWs (Au, Ag, Cu), which have similar atomic structure (FCC), but show very different faceting patterns. The correlation between the observed structural and transport properties of NW points out that the quantum conductance behavior is defined by preferred atomic arrangement at the narrowest constriction. In the case of magnetic (ex. Fe,Co,Ni) or quasi-magnetic (ex. Pd) wires, we have observed that one-atom-thick structures show a conductance of half the quantum as expected for a fully spin polarized current. This phenomenon seems to occur spontaneously for magnetic suspended atom-chains in zero magnetic field and at room temperature. These results open new opportunities for spin control in nanostructures. Funded by FAPESP, LNLS and CNPq.