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Sample records for ab5 type metal

  1. Non-stoichiometric AB5 alloys for metal hydride electrodes

    DOEpatents

    Reilly, James J.; Adzic, Gordana D.; Johnson, John R.; Vogt, Thomas; McBreen, James

    2001-01-01

    The present invention provides a non-stoichiometric alloy comprising a composition having the formula AB.sub.5+X an atomic ratio wherein A is selected from the group consisting of the rare earth metals, yttrium, mischmetal, or a combination thereof; B is nickel and tin, or nickel and tin and at least a third element selected from the group consisting of the elements in group IVA of the periodic table, aluminum, manganese, iron, cobalt, copper, antimony or a combination thereof; X is greater than 0 and less than or equal to about 2.0; and wherein at least one substituted A site is occupied by at least one of the B elements. An electrode incorporating said alloy and an electrochemical cell incorporating said electrode are also described.

  2. High cycle life, cobalt free, AB{5} metal hydride electrodes [Revised 11/10/98

    SciTech Connect

    Vogt, Tom; Reilly, J.J.; Johnson, J.R.; Adzic, G.D.; Ticianelli, E.A.; Mukerjee, S.; McBreen, J.

    1998-11-10

    Cobalt-free La(Ni,Sn)5+x alloys have been identified as low cost, corrosion resistant electrodes for nickel-metal-hydride batteries. The structure of theses alloys are similar to non-stoichiometric La(Ni,Cu)5+x compounds; i.e., they retain the P6/mmm space group while Ni dumbbells occupy La sites. Electrodes fabricated from some of these novel alloys have capacities and cycle lives equivalent to those made from commercial, battery grade, AB5 alloys with cobalt.

  3. Choosing the Type of Ownership. PACE Revised. Level 1. Unit 5. Research & Development Series No. 240AB5.

    ERIC Educational Resources Information Center

    Ashmore, M. Catherine; Pritz, Sandra G.

    This lesson on choosing the type of ownership, the fifth in a series of 18 units, is part of the first level of a comprehensive entrepreneurship curriculum entitled: A Program for Acquiring Competence in Entrepreneurship (PACE). (Designed for use with secondary students, the first level of PACE introduces students to the concepts involved in…

  4. Improvement in low-temperature and instantaneous high-rate output performance of Al-free AB5-type hydrogen storage alloy for negative electrode in Ni/MH battery: Effect of thermodynamic and kinetic regulation via partial Mn substituting

    NASA Astrophysics Data System (ADS)

    Zhou, Wanhai; Zhu, Ding; Tang, Zhengyao; Wu, Chaoling; Huang, Liwu; Ma, Zhewen; Chen, Yungui

    2017-03-01

    A series of Al-free Mn-modified AB5-type hydrogen storage alloys have been designed and the effects of thermodynamic stability and electrochemical kinetics on electrochemical performance via Mn substituting have been investigated. Compared with high-Al alloys, the Al-free alloys in this study have better low-temperature performance and instantaneous high-rate output because of the higher surface catalytic ability. After partial substitution of Ni by Mn, both the hydrogen desorption capacity and plateau pressure decrease, and correspondingly results in an improved thermodynamic stability which is adverse to low-temperature delivery. Additionally, with the improvement of charge acceptance ability and anti-corrosion property via Mn substitution, the room-temperature discharge capacity and cycling stability increase slightly. However, Mn adversely affects the electrochemical kinetics and deteriorates both the surface catalytic ability and the bulk hydrogen diffusion ability, leading to the drop of low-temperature dischargeability, high-rate dischargeability and peak power (Ppeak). Based on the thermodynamic and kinetic regulation and overall electrochemical properties, the optimal composition is obtained when x = 0.2, the discharge capacity is 243.6 mAh g-1 at -40 °C with 60 mA g-1, and the Ppeak attains to 969.6 W kg-1 at -40 °C.

  5. Structure, Biological Functions and Applications of the AB5 Toxins

    PubMed Central

    Beddoe, Travis; Paton, Adrienne W.; Le Nours, Jérôme; Rossjohn, Jamie; Paton, James C.

    2010-01-01

    AB5 toxins are important virulence factors for several major bacterial pathogens, including Bordetella pertussis, Vibrio cholerae, Shigella dysenteriae and at least two distinct pathotypes of Escherichia coli. The AB5 toxins are so termed because they comprise a catalytic A-subunit, which is responsible for disruption of essential host functions, and a pentameric B-subunit that binds to specific glycan receptors on the target cell surface. The molecular mechanisms by which these AB5 toxins cause disease have been largely unraveled, including recent insights into a novel AB5 toxin family, subtilase cytotoxin (SubAB). Furthermore, AB5 toxins have become a valuable tool for studying fundamental cellular functions, and are now being investigated for potential applications in the clinical treatment of human diseases. PMID:20202851

  6. Blood metals concentration in type 1 and type 2 diabetics.

    PubMed

    Forte, Giovanni; Bocca, Beatrice; Peruzzu, Angela; Tolu, Francesco; Asara, Yolande; Farace, Cristiano; Oggiano, Riccardo; Madeddu, Roberto

    2013-12-01

    Mechanisms for the onset of diabetes and the development of diabetic complications remain under extensive investigations. One of these mechanisms is abnormal homeostasis of metals, as either deficiency or excess of metals, can contribute to certain diabetic outcomes. Therefore, this paper will report the blood levels of chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), mercury (Hg), nickel (Ni), lead (Pb), selenium (Se), and zinc (Zn) in subjects with type 1 diabetes (n = 192, mean age 48.8 years, mean disease duration 20.6 years), type 2 diabetes (n = 68, mean age 68.4 years, mean disease duration 10.2 years), and in control subjects (n = 59, mean age 57.2 years), and discuss the results indicating their possible role in diabetes. The metal concentrations were measured by sector field inductively coupled plasma mass spectrometry after microwave-induced acid digestion of blood samples. The accuracy was checked using a blood-based certified reference material, and recoveries of all elements were in the range of 92-101 % of certified values. Type 1 diabetes was found to be associated with Cr (p = 0.02), Mn (p < 0.001), Ni (p < 0.001), Pb (p = 0.02), and Zn (p < 0.001) deficiency, and type 2 diabetes with Cr (p = 0.014), Mn (p < 0.001), and Ni (p < 0.001) deficiency. These deficiencies were appreciated also subdividing the understudied patients for gender and age groups. Furthermore, in type 1 diabetes, there was a positive correlation between Pb and age (p < 0.001, ρ = 0.400) and Pb and BMI (p < 0.001, ρ = 0.309), while a negative correlation between Fe and age (p = 0.002, ρ = -0.218). In type 2 diabetes, there was a negative correlation between Fe and age (p = 0.017, ρ = -0.294) and Fe and BMI (p = 0.026, ρ = -0.301). Thus, these elements may play a role in both forms of diabetes and combined mineral supplementations could have beneficial effects.

  7. Impregnated-electrode-type liquid metal ion source

    NASA Astrophysics Data System (ADS)

    Ishikawa, J.; Gotoh, Y.; Tsuji, H.; Takagi, T.

    We have developed an impregnated-electrode-type liquid metal ion source whose tip is a sintered-porous structure made of a refractory metal such as tungsten. By this structure the ratio of the liquid metal surface area facing the vacuum to the volume is low, which decreases useless metal evaporation from the surface. The maximum vapour pressure of the metal in operation for this ion source is 10 -1-10 0 Torr, which is 2-3 orders of magnitude higher than that for the needle type. Therefore, useful metal ions such as Ga +, Au +, Ag +, In +, Si 2+, Ge 2+, and Sb 2+ can be extracted from single element metals or alloys. The porous structure of the tip has also an effect on the positive control of the liquid metal flow rate to the tip head. Thus, a stable operation with a high current of a few hundreds of μA can be obtained together with a low current high brightness ion beam. Therefore, this ion source is suitable not only for microfocusing but also for a general use as a metal ion source.

  8. Estimating Type Ia Supernova Metallicities Using Neural Networks

    NASA Astrophysics Data System (ADS)

    Villar, V. Ashley

    2017-01-01

    Normal Type Ia supernovae (SNe) can be used as standardizable candles because their progenitors, white dwarfs, are a fairly homogenous class of objects. However, intrinsic variability in these events arise from a number of factors, including metallicity. Recent studies have investigated the effects of metallicity on Type Ia SNe observables from both a theoretical approach, by tuning model metallicity to analyze spectral features, and an observational approach, by studying the effect of host metallicity on light curves. In this work, we take a new, data-driven approach to the problem. Inspired by the success of neural networks in the field of image processing, we aim to estimate the metallicities of Type Ia SNe progenitors from their near-maximum spectra using feed-forward neural networks. We first collect a sample of near-maximum Type Ia SNe spectra from the literature to be smoothed and down-sampled. We then estimate the metallicities of the SNe hosts using the B-band magnitudes. We build a multilayer perceptron to generate a model that takes as input the down-sampled spectra and returns a scalar metallicity. Finally, we discuss basic considerations to be taken when working with spectral (as opposed to image) data using neural networks.

  9. Progress in Visualizing Atomic Size Effects with DFT-Chemical Pressure Analysis: From Isolated Atoms to Trends in AB5 Intermetallics.

    PubMed

    Berns, Veronica M; Engelkemier, Joshua; Guo, Yiming; Kilduff, Brandon J; Fredrickson, Daniel C

    2014-08-12

    constraints. In approaching this challenge, we have developed a scheme for allocating the grid pressures to contacts inspired by the Hirshfeld charge analysis. Here, each voxel is allocated to the contact between the two atoms whose free atom electron densities show the largest values at that position. In this way, the differing sizes of atoms are naturally included in the division of space without resorting to empirical radii. The use of the improved DFT-CP method is illustrated through analyses of the applicability of radius ratio arguments to Laves phase structures and the structural preferences of AB5 intermetallics between the CaCu5 and AuBe5 structure types.

  10. Creating Two-Dimensional Electron Gas in Polar/Polar Perovskite Oxide Heterostructures: First-Principles Characterization of LaAlO3/A(+)B(5+)O3.

    PubMed

    Wang, Yaqin; Tang, Wu; Cheng, Jianli; Behtash, Maziar; Yang, Kesong

    2016-06-01

    By using first-principles electronic structure calculations, we explored the possibility of producing two-dimensional electron gas (2DEG) at the polar/polar (LaO)(+)/(BO2)(+) interface in the LaAlO3/A(+)B(5+)O3 (A = Na and K, B = Nb and Ta) heterostructures (HS). Unlike the prototype polar/nonpolar LaAlO3/SrTiO3 HS system where there exists a least film thickness of four LaAlO3 unit cells to have an insulator-to-metal transition, we found that the polar/polar LaAlO3/A(+)B(5+)O3 HS systems are intrinsically conducting at their interfaces without an insulator-to-metal transition. The interfacial charge carrier densities of these polar/polar HS systems are on the order of 10(14) cm(-2), much larger than that of the LaAlO3/SrTiO3 system. This is mainly attributed to two donor layers, i.e., (LaO)(+) and (BO2)(+) (B = Nb and Ta), in the polar/polar LaAlO3/A(+)B(5+)O3 systems, while only one (LaO)(+) donor layer in the polar/nonpolar LaAlO3/SrTiO3 system. In addition, it is expected that, due to less localized Nb 4d and Ta 5d orbitals with respect to Ti 3d orbitals, these LaAlO3/A(+)B(5+)O3 HS systems can exhibit potentially higher electron mobility because of their smaller electron effective mass than that in the LaAlO3/SrTiO3 system. Our results demonstrate that the electronic reconstruction at the polar/polar interface could be an alternative way to produce superior 2DEG in the perovskite-oxide-based HS systems.

  11. Environmental Effects on the Metallicities of Early-Type Galaxies

    NASA Technical Reports Server (NTRS)

    Jones, Christine; Oliversen, Ronald (Technical Monitor)

    2004-01-01

    We completed and published two papers in the Astrophysical Journal based on research from grant. In the first paper we analyzed nine X-ray-bright Virgo early-type galaxies observed by both ASCA and ROSAT. Through spatially resolved spectroscopy, we determined the radial temperature profiles and abundances of Mg, Si, and Fe for six galaxies. The temperature profiles are consistent with isothermal temperatures outside of cooler regions at the galaxies' centers. We present new evidence for iron abundance gradients in NGC 4472 and NGC 4649 and confirm the previous results on NGC 4636. Mg and Si abundance gradients on average are flatter than those of iron and correspond to an underabundance of α-process elements at high Fe values, while at low iron the element ratios favor enrichment by Type II supernovae (SNe). We explain the observed trend using the metallicity dependence of SN Ia metal production and present constraints on the available theoretical modeling for low-metallicity inhibition of SNe Ia. In the second paper We analyzed nine X-ray-bright Virgo early-type galaxies observed by both ASCA and ROSAT. Through spatially resolved spectroscopy, we determined the radial temperature profiles and abundances of Mg, Si, and Fe for six galaxies. The temperature profiles are consistent with isothermal temperatures outside of cooler regions at the galaxies' centers. We present new evidence for iron abundance gradients in NGC 4472 and NGC 4649 and confirm the previous results on NGC 4636. Mg and Si abundance gradients on average are flatter than those of iron and correspond to an underabundance of α-process elements at high Fe values, while at low iron the element ratios favor enrichment by Type I1 supernovae (SNe). We explain the observed trend using the metallicity dependence of SN Ia metal production and present constraints on the available theoretical modeling for low-metallicity inhibition of SNe Ia.

  12. Gender and Ethnicity Differences on the Abridged Big Five Circumplex (AB5C) of Personality Traits: A Differential Item Functioning Analysis

    ERIC Educational Resources Information Center

    Mitchelson, Jacqueline K.; Wicher, Eliza W.; LeBreton, James M.; Craig, S. Bartholomew

    2009-01-01

    The current study evaluates the measurement precision of the Abridged Big Five Circumplex (AB5C) of personality traits by identifying those items that demonstrate differential item functioning by gender and ethnicity. Differential item functioning is found in 33 of 45 (73%) of the AB5C scales, across gender and ethnic groups (Caucasian vs. African…

  13. Multiple exposure to metals in eight types of welding.

    PubMed

    Apostoli, P; Porru, S; Brunelli, E; Alessio, L

    1997-01-01

    This article evaluates multiple exposures to metals in different types of metal welding such as manual metal arc for mild and stainless steel, continuous wire, submerged arc, laser and brazing. Environmental monitoring was carried out in eight different occupational situations and the inductively coupled plasma mass spectrometry technique was adopted in order to characterize exposure to several elements simultaneously and with high accuracy. The results showed that up to 23 elements could be measured. The highest concentrations were found for Al, Mn, Fr, Ni, Cr, Cu and Zn. For some elements such as In, Nd, I, Rb the concentrations were very low. A qualitative and quantitative variation in fume composition was observed at a certain distance from the welding point, which should be to taken into account when evaluating indirect exposures. It would also be possible, with this technique, to identify specific elements in the mixture which could also be measured in biological fluids.

  14. Differing ability to transport non-metal substrates by two RND-type metal exporters

    PubMed Central

    Conroy, Otakuye; Kim, Eun-Hae; McEvoy, Megan M.; Rensing, Christopher

    2010-01-01

    The metal-exporting systems CusCFBA of Escherichia coli and GesABC of Salmonella are RND-type multi-protein systems responsible for detoxification during metal stress. In this study the substrate range was determined for each metal transport system and possible amino acid residues important in substrate specificity identified. The Ges system, previously identified as a gold-efflux system, conferred resistance to the greatest number and variety of organic chemicals including chloramphenicol, not previously recognized as a substrate. Phylogenetic analysis showed that GesB is most closely related to a class of RND transporters including MexF that have been shown to be responsible for exporting fluoroquinolones, chloramphenicol, and biocides. However, many of the closest homologs of GesABC appear to have a role in metal resistance judging from the genetic context. In contrast, CusCFBA belongs to a distinct family of RND-type monovalent metal exporter systems containing a number of essential metal-binding methionines resulting in a much narrower substrate range. PMID:20497225

  15. Mechanics of metal-catecholate complexes: the roles of coordination state and metal types.

    PubMed

    Xu, Zhiping

    2013-10-10

    There have been growing evidences for the critical roles of metal-coordination complexes in defining structural and mechanical properties of unmineralized biological materials, including hardness, toughness, and abrasion resistance. Their dynamic (e.g. pH-responsive, self-healable, reversible) properties inspire promising applications of synthetic materials following this concept. However, mechanics of these coordination crosslinks, which lays the ground for predictive and rational material design, has not yet been well addressed. Here we present a first-principles study of representative coordination complexes between metals and catechols. The results show that these crosslinks offer stiffness and strength near a covalent bond, which strongly depend on the coordination state and type of metals. This dependence is discussed by analyzing the nature of bonding between metals and catechols. The responsive mechanics of metal-coordination is further mapped from the single-molecule level to a networked material. The results presented here provide fundamental understanding and principles for material selection in metal-coordination-based applications.

  16. Main types of rare-metal mineralization in Karelia

    NASA Astrophysics Data System (ADS)

    Ivashchenko, V. I.

    2016-03-01

    Rare-metal mineralization in Karelia is represented by V, Be, U deposits and In, Re, Nb, Ta, Li, Ce, La, and Y occurrences, which are combined into 17 types of magmatic, pegmatite, albitite-greisen, hydrothermal-metasomatic, sedimentary, and epigenetic groups. The main vanadium resources are localized in the Onega ore district. These are deposits of the Padma group (556 kt) and the Pudozhgorsky complex (1.5 Mt). The REE occurrences are primarily characterized by Ce-La specialization. The perspective of HREE is related to the Eletozero-Tiksheozero alkaline and Salmi anorthosite-rapakivi granite complexes. Rare-metal pegmatites bear complex mineralization with insignificant low-grade resources. The Lobash and Jalonvaara porphyry Cu-Mo deposits are potential sources of rhenium: Re contents in molybdenite are 20-70 and 50-246 ppm and hypothetical resources are 12 and 7.5 t, respectively. The high-grade (˜100 ppm) and metallogenic potential of indium (˜2400 t) make the deposits of the Pitkäranta ore district leading in the category of Russian ore objects most prospective for indium. Despite the diverse rare-metal mineralization known in Karelia, the current state of this kind of mineral commodities at the world market leaves real metallogenic perspective only for V, U, Re, In, and Nb.

  17. 46 CFR 111.60-23 - Metal-clad (Type MC) cable.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Metal-clad (Type MC) cable. 111.60-23 Section 111.60-23...-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-23 Metal-clad (Type MC) cable. (a) Metal-clad (Type MC) cable permitted on board a vessel must be continuous corrugated metal-clad cable. (b)...

  18. 46 CFR 111.60-23 - Metal-clad (Type MC) cable.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Metal-clad (Type MC) cable. 111.60-23 Section 111.60-23...-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-23 Metal-clad (Type MC) cable. (a) Metal-clad (Type MC) cable permitted on board a vessel must be continuous corrugated metal-clad cable. (b)...

  19. 46 CFR 111.60-23 - Metal-clad (Type MC) cable.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Metal-clad (Type MC) cable. 111.60-23 Section 111.60-23...-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-23 Metal-clad (Type MC) cable. (a) Metal-clad (Type MC) cable permitted on board a vessel must be continuous corrugated metal-clad cable. (b)...

  20. 46 CFR 111.60-23 - Metal-clad (Type MC) cable.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Metal-clad (Type MC) cable. 111.60-23 Section 111.60-23...-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-23 Metal-clad (Type MC) cable. (a) Metal-clad (Type MC) cable permitted on board a vessel must be continuous corrugated metal-clad cable. (b)...

  1. 46 CFR 111.60-23 - Metal-clad (Type MC) cable.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Metal-clad (Type MC) cable. 111.60-23 Section 111.60-23...-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-23 Metal-clad (Type MC) cable. (a) Metal-clad (Type MC) cable permitted on board a vessel must be continuous corrugated metal-clad cable. (b)...

  2. Metal-sulfur type cell having improved positive electrode

    NASA Astrophysics Data System (ADS)

    Dejonghe, Lutgard C.; Visco, Steven J.; Mailhe, Catherine C.; Armand, Michel B.

    1988-03-01

    A novel metal-sulfur type cell operable at a temperature of 200 C or less with an energy density of 150 Whrs/Kg or better is disclosed characterized by an organo-sulfur cathode formed from an organic-sulfur compound having the general formula, in its charged state, of (R(S) sub y) n wherein y = 1 to 6; n = 2 to 20; and R is one or more different aliphatic or aromatic organic moieties having 1 to 20 carbon atoms, which may include one or more oxygen, sulfur, or nitrogen heteroatoms when R comprises one or more aromatic rings, or one or more oxygen, sulfur, nitrogen, or fluorine atoms associated with the chain when R comprises an aliphatic chain, wherein the aliphatic group may be linear or branched, saturated or unsaturated, and wherein either the aliphatic chain or the aromatic ring may have substituted groups thereon.

  3. Metal-sulfur type cell having improved positive electrode

    DOEpatents

    DeJonghe, L.C.; Visco, S.J.; Mailhe, C.C.; Armand, M.B.

    1988-03-31

    A novel metal-sulfur type cell operable at a temperature of 200/degree/C or less with an energy density of 150 Whrs/Kg or better is disclosed characterized by an organo-sulfur cathode formed from an organic-sulfur compound having the general formula, in its charged state, of (R(S)/sub y/)n wherein y = 1 to 6; n = 2 to 20; and R is one or more different aliphatic or aromatic organic moieties having 1 to 20 carbon atoms, which may include one or more oxygen, sulfur, or nitrogen heteroatoms when R comprises one or more aromatic rings, or one or more oxygen, sulfur, nitrogen, or fluorine atoms associated with the chain when R comprises an aliphatic chain, wherein the aliphatic group may be linear or branched, saturated or unsaturated, and wherein either the aliphatic chain or the aromatic ring may have substituted groups thereon. 4 figs.

  4. Metal-sulfur type cell having improved positive electrode

    DOEpatents

    Dejonghe, Lutgard C.; Visco, Steven J.; Mailhe, Catherine C.; Armand, Michel B.

    1989-01-01

    An novel metal-sulfur type cell operable at a temperature of 200.degree. C. or less with an energy density of 150 Whrs/Kg or better is disclosed characterized by an organo-sulfur cathode formed from an organic-sulfur compound having the general formula, in its charged state, of (R(S).sub.y).sub.n wherein y=1 to 6; n=2 to 20; and R is one or more different aliphatic or aromatic organic moieties having 1 to 20 carbon atoms, which may include one or more oxygen, sulfur, or nitrogen heteroatoms when R comprisises one of more aromatic rings, or one or more oxygen, sulfur, nitrogen, or fluorine atoms associtated with the chain when R comprises an aliphatic chain, wherein the aliphatic group may be linear or branched, saturated or unsaturated, and wherein either the aliphatic chain or the aromatic ring may have substituted groups thereon.

  5. PNP-Pincer-Type Phosphaalkene Complexes of Late Transition Metals.

    PubMed

    Ozawa, Fumiyuki; Nakajima, Yumiko

    2016-10-01

    This account summarizes our recent studies on PNP-pincer-type phosphaalkene complexes. Phosphaalkenes with a P=C bond possess an extremely low-lying π* orbital and have a marked tendency to engage in strong π back-bonding with transition metals. This particular ligand property provides PNP-pincer complexes with unique structures and reactivities. 2,6-Bis(phosphaethenyl)pyridine leads to the isolation of coordinatively unsaturated complexes of Fe(I) and Cu(I); the former adopts a trigonal monopyramidal configuration, whereas the latter has a strong affinity for PF6- and SbF6- as non-coordinating anions. Unsymmetrical PNP-pincer-type phosphaalkene complexes of Ir(I) bearing a dearomatized pyridine unit instantly cleave the N-H bond of NH3 and the C-H bond of MeCN at room temperature. The dearomatized iridium complexes catalyze the dehydrative coupling of amines with alcohols to afford N-alkylated amines and imines in high yields.

  6. Determination of metal content in three types of human gallstone

    SciTech Connect

    Yamamoto, I.; Itoh, M.; Narimatsu, S.; Suzuki, N.; Demura, R.; Kotani, N.; Tsukada, S.

    1989-01-01

    In general, human gallstones formed in the bile cyst and/or bile duct are classified into three major groups such as cholesterol stone, pigment stone and rare stone. Each group can further be divided into subgroups. It is well known that metals are minor components in the body but play very important roles for the biological functions. Metal content in human renal calculi was reported previously, but no paper have dealt with metal contents in relation to formation mechanism of gallstone. In this study, the authors have determined the metal content of gallstones. They discussed the differences of metal contents in the various components, and the age and sex differences in the metal contents of the gallstones. They also discussed the relationship between metals and formation mechanism of gallstone as well as the environmental contamination. They focused on calcium, magnesium, manganese, iron, copper, zinc, cadmium and lead.

  7. MELCOR 1.8.2 assessment: Aerosol experiments ABCOVE AB5, AB6, AB7, and LACE LA2

    SciTech Connect

    Souto, F.J.; Haskin, F.E.; Kmetyk, L.N.

    1994-10-01

    The MELCOR computer code has been used to model four of the large-scale aerosol behavior experiments conducted in the Containment System Test Facility (CSTF) vessel. Tests AB5, AB6 and AB7 of the ABCOVE program simulate the dry aerosol conditions during a hypothetical severe accident in an LMFBR. Test LA2 of the LACE program simulates aerosol behavior in a condensing steam environment during a postulated severe accident in an LWR with failure to isolate the containment. The comparison of code results to experimental data show that MELCOR is able to correctly predict most of the thermal-hydraulic results in the four tests. MELCOR predicts reasonably well the dry aerosol behavior of the ABCOVE tests, but significant disagreements are found in the aerosol behavior modelling for the LA2 experiment. These results tend to support some of the concerns about the MELCOR modelling of steam condensation onto aerosols expressed in previous works. During these analyses, a limitation in the MELCOR input was detected for the specification of the aerosol parameters for more than one component. A Latin Hypercube Sampling (LHS) sensitivity study of the aerosol dynamic constants is presented for test AB6. The study shows the importance of the aerosol shape factors in the aerosol deposition behavior, and reveals that MELCOR input/output processing is highly labor intensive for uncertainty and sensitivity analyses based on LHS.

  8. Transition metals as Lewis bases: "Z-type" boron ligands and metal-to-boron dative bonding.

    PubMed

    Braunschweig, Holger; Dewhurst, Rian D

    2011-01-21

    While the vast majority of inorganic chemistry involves electron donation from main-group atoms to metals, an intriguing yet flip-side exists: where Lewis-basic metals donate electron density to Lewis-acidic main-group atoms (most often boron). These so-called "Z-type" ligands, along with other less clear-cut complexes, are examples of this metal-ligand role reversal. This perspective article offers an introduction to metal-to-boron dative bonding, and attempts to correlate spectroscopic and structural data from the complexes.

  9. Metals in the pathogenesis of type 2 diabetes.

    PubMed

    Khan, Abdul Rehman; Awan, Fazli Rabbi

    2014-01-08

    Minerals are one of the components of food, though they are not synthesized in the body but they are essential for optimal health. Several essential metals are required for the proper functioning of many enzymes, transcriptional factors and proteins important in various biochemical pathways. For example Zn, Mg and Mn are cofactors of hundreds of enzymes, and Zn is involved in the synthesis and secretion of insulin from the pancreatic beta-cells. Similarly, Cr enhances the insulin receptor activity on target tissues, especially in muscle cells. Insulin is the key hormone required to maintain the blood glucose level in normal range. In case of insulin deficiency or resistance, blood glucose concentration exceeds the upper limit of the normal range of 126 mg/dl. Persistent increase of blood serum glucose level leads to overt chronic hyperglycemia, which is a major clinical symptom of diabetes mellitus. Poor glycemic control and diabetes alters the levels of essential trace elements such as Zn, Mg, Mn, Cr, Fe etc. by increasing urinary excretion and their concomitant decrease in the blood. Hence, the main purpose of this review is to discuss the important roles of essential trace elements in normal homeostasis and physiological functioning. Moreover, perturbation of essential trace elements is also discussed in perspective of type 2 diabetes pathobiology.

  10. Gas diffusion-type oxygen electrode using perovskite-type oxides for metal-air batteries

    SciTech Connect

    Hyodo, Takeo; Miura, Norio; Yamazoe, Noboru

    1995-12-31

    In order to develop an air cathode of metal-air batteries, oxygen reduction behavior of gas diffusion-type carbon electrodes loaded with perovskite-type oxides, La{sub 1{minus}x}A{prime}{sub x}FeO{sub 3} (A{prime} = Ca, Sr, Ba, 0 {le} x {le} 1.0), was examined in 8 M KOH at 60 C. Among the oxide catalysts tested, La{sub 0.5}Sr{sub 0.5}FeO{sub 3} (specific surface area: 21.5 m{sup 2}{center_dot}g{sup {minus}1}) gave the highest electrode performance. On the basis of electrode reaction kinetics, H{sub 2}O{sub 2} decomposition rates, and temperature programmed desorption of oxygen, it was concluded that such a performance was attributable to the active sites of the oxide for the direct 4-electron reduction of oxygen. Moreover, the electrode using La{sub 0.5}Sr{sub 0.5}FeO{sub 3} was found to be rather stable in a short-term operation for 90 h at 300 mA{center_dot}cm{sup {minus}2}.

  11. Type Ia Supernovae Keep Memory of their Progenitor Metallicity

    NASA Astrophysics Data System (ADS)

    Piersanti, Luciano; Bravo, Eduardo; Cristallo, Sergio; Domínguez, Inmaculada; Straniero, Oscar; Tornambé, Amedeo; Martínez-Pinedo, Gabriel

    2017-02-01

    The ultimate understanding of SNe Ia diversity is one of the most urgent issues to exploit thermonuclear explosions of accreted White Dwarfs (WDs) as cosmological yardsticks. In particular, we investigate the impact of the progenitor system metallicity on the physical and chemical properties of the WD at the explosion epoch. We analyze the evolution of CO WDs through the accretion and simmering phases by using evolutionary models based on time-dependent convective mixing and an extended nuclear network including the most important electron captures, beta decays, and URCA processes. We find that, due to URCA processes and electron-captures, the neutron excess and density at which the thermal runaway occurs are substantially larger than previously claimed. Moreover, we find that the higher the progenitor metallicity, the larger the neutron excess variation during the accretion and simmering phases and the higher the central density and the convective velocity at the explosion. Hence, the simmering phase acts as an amplifier of the differences existing in SNe Ia progenitors. When applying our results to the neutron excess estimated for the Tycho and Kepler young supernova remnants, we derive that the metallicity of the progenitors should be in the range Z=0.030{--}0.032, close to the average metallicity value of the thin disk of the Milky Way. As the amount of {}56{Ni} produced in the explosion depends on the neutron excess and central density at the thermal runaway, our results suggest that the light curve properties depend on the progenitor metallicity.

  12. Cooperative Assembly of 3-Ring-Based Zeolite-Type Metal-Organic Frameworks and Johnson-Type Dodecahedra

    PubMed Central

    Zheng, Shou-Tian; Zuo, Fan; Wu, Tao; Irfanoglu, Burcin; Chou, Chengtsung; Nieto, Ruben A.; Feng, Pingyun

    2015-01-01

    Two birds with one stone One synthetic strategy led to the preparation of both 3-ring-based zeolite-type metal-organic frameworks (NPO-type) and Johnson-type metal-organic polyhedra. The strategy is based on the cooperative assembly of 4-connected indium nodes with two symmetry-complementary ligands (one serves to generate 3-rings and the other crosslinks 3-rings). Photocatalytic H2 production experiments demonstrated these NPO-zeolite compounds behave as semiconductors and exhibit photocatalytic activity for the generation of dihydrogen from water under ultraviolet irradiation. PMID:21328654

  13. Energy cost of intracellular metal and metalloid detoxification in wild-type eukaryotic phytoplankton.

    PubMed

    Lavoie, Michel; Raven, John A; Jones, Oliver A H; Qian, Haifeng

    2016-10-01

    Microalgae use various cellular mechanisms to detoxify both non-essential and excess essential metals or metalloids. There exists however, a threshold in intracellular metal(loid) concentrations beyond which detoxification mechanisms are no longer effective and inhibition of cell division inevitably occurs. It is therefore important to determine whether the availability of energy in the cell could constrain metal(loid) detoxification capacity and to better define the thresholds beyond which a metal(loid) becomes toxic. To do this we performed the first extensive bioenergetics analysis of intracellular metal(loid) detoxification mechanisms (e.g., metal-binding peptides, polyphosphate granules, metal efflux, metal and metalloid reduction, metalloid methylation, enzymatic and non-enzymatic antioxidants) in wild-type eukaryotic phytoplankton based on the biochemical mechanisms of each detoxification strategy and on experimental measurements of detoxifying biomolecules in the literature. The results show that at the onset of metal(loid) toxicity to growth, all the detoxification strategies considered required only a small fraction of the total cellular energy available for growth indicating that intracellular detoxification ability in wild-type eukaryotic phytoplankton species is not constrained by the availability of cellular energy. The present study brings new insights into metal(loid) toxicity mechanisms and detoxification strategies in wild-type eukaryotic phytoplankton.

  14. Characterization of a heavy metal translocating P-type ATPase gene from an environmental heavy metal resistance Enterobacter sp. isolate.

    PubMed

    Chien, Chih-Ching; Huang, Chia-Hsuan; Lin, Yi-Wei

    2013-03-01

    Heavy metals are common contaminants found in polluted areas. We have identified a heavy metal translocating P-type ATPase gene (hmtp) via fosmid library and in vitro transposon mutagenesis from an Enterobacter sp. isolate. This gene is believed to participate in the bacterium's heavy metal resistance traits. The complete gene was identified, cloned, and expressed in a suitable Escherichia coli host cell. E. coli W3110, RW3110 (zntA::Km), GG48 (ΔzitB::Cm zntA::Km), and GG51 (ΔzitB::Cm) were used to study the possible effects of this gene for heavy metal (cadmium and zinc in particular) resistance. Among the E. coli strains tested, RW3110 and GG48 showed more sensitivity to cadmium and zinc compared to the wild-type E. coli W3110 and strain GG51. Therefore, strains RW3110 and GG48 were chosen for the reference hosts for further evaluation of the gene's effect. The results showed that expression of this heavy metal translocating P-type ATPase gene could increase the ability for zinc and cadmium resistance in the tested microorganisms.

  15. Electrochemical hydrogen storage of Ti-V-based body-centered-cubic phase alloy surface-modified with AB5 nanoparticles

    NASA Astrophysics Data System (ADS)

    Yu, X. B.; Walker, G. S.; Grant, D. M.; Wu, Z.; Xia, B. J.; Shen, J.

    2005-09-01

    A composite of Ti-V-based bcc phase alloy surface-modified with AB5 nanoparticles was prepared by ball milling. The composite showed significantly improved electrochemical hydrogen release capacities. For example, the 30 min ball milled Ti-30V-15Mn-15Cr +10wt%AB5 showed a discharge capacity in the first cycle, at 353 K, of 886mAhg-1, corresponding to 3.38 wt % of hydrogen, with a 45mAg-1 discharge current. It is thought that this high capacity is due to the enhanced electrochemical-catalytic activity from the alloy surface covered with AB5 nanoparticles, which not only have better charge-discharge capacity themselves, acting as both an electrocatalyst and a microcurrent collector, but also result in the greatly enhanced hydrogen atomic diffusivities in the nanocrystalline relative to their conventional coarse-grained counterparts. These results provide new insight for use of Ti-V-based bcc phase alloy for high-energy batteries.

  16. Coexistence of two types of metal filaments in oxide memristors

    NASA Astrophysics Data System (ADS)

    Xu, D.; Shangguan, X. N.; Wang, S. M.; Cao, H. T.; Liang, L. Y.; Zhang, H. L.; Gao, J. H.; Long, W. M.; Wang, J. R.; Zhuge, F.

    2017-02-01

    One generally considers the conducting filament in ZnO-based valence change memristors (VCMs) as an aggregation of oxygen vacancies. Recently, the transmission electron microscopy observation showed the filament is composed of a Zn-dominated ZnOx. In this study, careful analysis of the temperature dependence of the ON state resistance demonstrates that the formation/rupture of a Zn filament is responsible for the resistive switching in ZnO VCMs. Cu/ZnO/Pt memristive devices can be operated in both VCM and ECM (electrochemical metallization memristor) modes by forming different metal filaments including Cu, Zn and a coexistence of these two filaments. The device operation can be reversibly switched between ECM and VCM modes. The dual mode operation capability of Cu/ZnO/Pt provides a wide choice of select devices for constructing memristive crossbar architectures.

  17. Porous nanoarchitectures of spinel-type transition metal oxides for electrochemical energy storage systems.

    PubMed

    Park, Min-Sik; Kim, Jeonghun; Kim, Ki Jae; Lee, Jong-Won; Kim, Jung Ho; Yamauchi, Yusuke

    2015-12-14

    Transition metal oxides possessing two kinds of metals (denoted as AxB3-xO4, which is generally defined as a spinel structure; A, B = Co, Ni, Zn, Mn, Fe, etc.), with stoichiometric or even non-stoichiometric compositions, have recently attracted great interest in electrochemical energy storage systems (ESSs). The spinel-type transition metal oxides exhibit outstanding electrochemical activity and stability, and thus, they can play a key role in realising cost-effective and environmentally friendly ESSs. Moreover, porous nanoarchitectures can offer a large number of electrochemically active sites and, at the same time, facilitate transport of charge carriers (electrons and ions) during energy storage reactions. In the design of spinel-type transition metal oxides for energy storage applications, therefore, nanostructural engineering is one of the most essential approaches to achieving high electrochemical performance in ESSs. In this perspective, we introduce spinel-type transition metal oxides with various transition metals and present recent research advances in material design of spinel-type transition metal oxides with tunable architectures (shape, porosity, and size) and compositions on the micro- and nano-scale. Furthermore, their technological applications as electrode materials for next-generation ESSs, including metal-air batteries, lithium-ion batteries, and supercapacitors, are discussed.

  18. Use of Divalent Metal Ions in the DNA Cleavage Reaction of Human Type II Topoisomerases†

    PubMed Central

    Deweese, Joseph E.; Burch, Amber M.; Burgin, Alex B.; Osheroff, Neil

    2009-01-01

    All type II topoisomerases require divalent metal ions in order to cleave and ligate DNA. In order to further elucidate the mechanistic basis for these critical enzyme-mediated events, the role of the metal ion in the DNA cleavage reaction of human topoisomerase IIβ was characterized and compared to that of topoisomerase IIα. The present study utilized divalent metal ions with varying thiophilicities in conjunction with DNA cleavage substrates that substituted a sulfur atom for the 3′-bridging oxygen or the non-bridging oxygens of the scissile phosphate. Based on time courses of DNA cleavage, cation titrations, and metal ion mixing experiments, we propose the following model for the use of divalent metal ions by human type II topoisomerases. First, both enzymes employ a two-metal-ion mechanism to support DNA cleavage. Second, an interaction between one divalent metal ion and the 3′-bridging atom of the scissile phosphate greatly enhances enzyme-mediated DNA cleavage, most likely by stabilizing the leaving 3′-oxygen. Third, there is an important interaction between a divalent second metal ion and a non-bridging atom of the scissile phosphate that stimulates DNA cleavage mediated by topoisomerase IIβ. If this interaction exists in topoisomerase IIα, its effects on DNA cleavage are equivocal. This last aspect of the model highlights a difference in metal ion utilization during DNA cleavage mediated by human topoisomerase IIα and IIβ. PMID:19222228

  19. Artificial neural network approach to modelling of metal contents in different types of chocolates.

    PubMed

    Podunavac-Kuzmanović, Sanja; Jevrić, Lidija; Švarc-Gajić, Jaroslava; Kovačević, Strahinja; Vasiljević, Ivana; Kecojević, Isidora; Ivanović, Evica

    2015-01-01

    The relationships between the contents of various metals in different types of chocolates were studied using chemometric approach. Chemometric analysis was based on the application of artificial neural networks (ANN). ANN was performed in order to select the significant models for predicting the metal contents. ANN equations, that represent the content of one metal as a function of the contents of other metals were established. The statistical quality of the generated mathematical models was determined by standard statistical measures and cross-validation parameters. High agreement between experimental and predicted values, obtained in the validation procedure, indicated the good quality of the models. The obtained results indicate the possibility of predicting the metal contents in different types of chocolate.

  20. Origin and evolution of metal P-type ATPases in Plantae (Archaeplastida)

    PubMed Central

    Hanikenne, Marc; Baurain, Denis

    2013-01-01

    Metal ATPases are a subfamily of P-type ATPases involved in the transport of metal cations across biological membranes. They all share an architecture featuring eight transmembrane domains in pairs of two and are found in prokaryotes as well as in a variety of Eukaryotes. In Arabidopsis thaliana, eight metal P-type ATPases have been described, four being specific to copper transport and four displaying a broader metal specificity, including zinc, cadmium, and possibly copper and calcium. So far, few efforts have been devoted to elucidating the origin and evolution of these proteins in Eukaryotes. In this work, we use large-scale phylogenetics to show that metal P-type ATPases form a homogenous group among P-type ATPases and that their specialization into either monovalent (Cu) or divalent (Zn, Cd…) metal transport stems from a gene duplication that took place early in the evolution of Life. Then, we demonstrate that the four subgroups of plant metal ATPases all have a different evolutionary origin and a specific taxonomic distribution, only one tracing back to the cyanobacterial progenitor of the chloroplast. Finally, we examine the subsequent evolution of these proteins in green plants and conclude that the genes thoroughly characterized in model organisms are often the result of lineage-specific gene duplications, which calls for caution when attempting to infer function from sequence similarity alone in non-model organisms. PMID:24575101

  1. Age determination of the world's oldest movable metal types through measuring the "meog" using AMS

    NASA Astrophysics Data System (ADS)

    Hong, W.; Lee, S. C.; Park, J. H.; Park, G.; Sung, K. H.; Lee, J. G.; Nam, K. H.

    2015-10-01

    The fabrication year of a set of movable metal types that were thought to be used for printing "Jeungdoga" was investigated. Since the types were made from bronze and did not contain carbon, an organic black ink called "meog" was collected from the type surfaces to quantify their ages. The meog samples were collected from 34 metal types, and 27 ages were obtained. The youngest age was 798 ± 44 yrBP, and the oldest reasonable age was 1166 ± 43 yrBP. The weighted average after eliminating ages with poor statistics was 950 ± 28 yrBP. This age is 300 years older than that of the Jikji (AD 1377), which is a Buddhist document recognized as the world's oldest document printed using metal types, and also older than that of the Gutenberg bible (AD 1450).

  2. Micromachined mold-type double-gated metal field emitters

    NASA Astrophysics Data System (ADS)

    Lee, Yongjae; Kang, Seokho; Chun, Kukjin

    1997-12-01

    Electron field emitters with double gates were fabricated using micromachining technology and the effect of the electric potential of the focusing gate (or second gate) was experimentally evaluated. The molybdenum field emission tip was made by filling a cusplike mold formed when a conformal film was deposited on the hole-trench that had been patterned on stacked metals and dielectric layers. The hole-trench was patterned by electron beam lithography and reactive ion etching. Each field emitter has a 0960-1317/7/4/009/img1 diameter extraction gate (or first gate) and a 0960-1317/7/4/009/img2 diameter focusing gate (or second gate). To make a path for the emitted electrons, silicon bulk was etched anisotropically in KOH and EDP (ethylene-diamine pyrocatechol) solution successively. The I - V characteristics and anode current change due to the focusing gate potential were measured.

  3. Antiferromagnetic half-metals, gapless half-metals, and spin gapless semiconductors: The D0{sub 3}-type Heusler alloys

    SciTech Connect

    Gao, G. Y. Yao, Kai-Lun

    2013-12-02

    High-spin-polarization materials are desired for the realization of high-performance spintronic devices. We combine recent experimental and theoretical findings to theoretically design several high-spin-polarization materials in binary D0{sub 3}-type Heusler alloys: gapless (zero-gap) half-metallic ferrimagnets of V{sub 3}Si and V{sub 3}Ge, half-metallic antiferromagnets of Mn{sub 3}Al and Mn{sub 3}Ga, half-metallic ferrimagnets of Mn{sub 3}Si and Mn{sub 3}Ge, and a spin gapless semiconductor of Cr{sub 3}Al. The high spin polarization, zero net magnetic moment, zero energy gap, and slight disorder compared to the ternary and quaternary Heusler alloys make these binary materials promising candidates for spintronic applications. All results are obtained by the electronic structure calculations from first-principles.

  4. Metamagnetism of η-carbide-type transition-metal carbides and nitrides

    NASA Astrophysics Data System (ADS)

    Waki, T.; Terazawa, S.; Umemoto, Y.; Tabata, Y.; Sato, K.; Kondo, A.; Kindo, K.; Nakamura, H.

    2011-09-01

    η-carbide-type transition-metal compounds include the frustrated stella quadran-gula lattice. Due to characteristics of the lattice, we expect subtle transitions between frustrated and non-frustrated states. Here, we report metamagnetic transitions newly found in η-carbide-type compounds Fe3W3C, Fe6W6C and Co6W6C.

  5. Direct band gap electroluminescence from bulk germanium at room temperature using an asymmetric fin type metal/germanium/metal structure

    SciTech Connect

    Wang, Dong Maekura, Takayuki; Kamezawa, Sho; Yamamoto, Keisuke; Nakashima, Hiroshi

    2015-02-16

    We demonstrated direct band gap (DBG) electroluminescence (EL) at room temperature from n-type bulk germanium (Ge) using a fin type asymmetric lateral metal/Ge/metal structure with TiN/Ge and HfGe/Ge contacts, which was fabricated using a low temperature (<400 °C) process. Small electron and hole barrier heights were obtained for TiN/Ge and HfGe/Ge contacts, respectively. DBG EL spectrum peaked at 1.55 μm was clearly observed even at a small current density of 2.2 μA/μm. Superlinear increase in EL intensity was also observed with increasing current density, due to superlinear increase in population of elections in direct conduction band. The efficiency of hole injection was also clarified.

  6. KMOS view of the Galactic Centre - II. Metallicity distribution of late-type stars

    NASA Astrophysics Data System (ADS)

    Feldmeier-Krause, A.; Kerzendorf, W.; Neumayer, N.; Schödel, R.; Nogueras-Lara, F.; Do, T.; de Zeeuw, P. T.; Kuntschner, H.

    2017-01-01

    Knowing the metallicity distribution of stars in the Galactic Centre has important implications for the formation history of the Milky Way nuclear star cluster. However, this distribution is not well known, and is currently based on a small sample of fewer than 100 stars. We obtained near-infrared K-band spectra of more than 700 late-type stars in the central 4 pc2 of the Milky Way nuclear star cluster with the integral-field spectrograph KMOS (VLT). We analyse the medium-resolution spectra using a full-spectral fitting method employing the Göttingen spectral library of synthetic PHOENIX spectra. The derived stellar metallicities range from metal-rich [M/H] > +0.3 dex to metal-poor [M/H] <-1.0 dex, with a fraction of 5.2^{+6.0}_{-3.1} per cent metal-poor ([M/H] ≤ -0.5 dex) stars. The metal-poor stars are distributed over the entire observed field. The origin of metal-poor stars remains unclear. They could originate from infalling globular clusters. For the metal-rich stellar population ([M/H] > 0 dex), a globular cluster origin can be ruled out. As there is only a very low fraction of metal-poor stars in the central 4 pc2 of the Galactic Centre, we believe that our data can discard a scenario in which the Milky Way nuclear star cluster is purely formed from infalling globular clusters.

  7. Effect of Zr on microstructure of metallic glass coatings prepared by gas tunnel type plasma spraying.

    PubMed

    Kobayashi, A; Kuroda, T; Kimura, H; Inoue, A

    2012-06-01

    Metallic glass is one of the most attractive advanced materials, and many researchers have conducted various developmental research works. Metallic glass is expected to be used as a functional material because of its excellent physical and chemical functions such as high strength and high corrosion resistance. However, the application for small size parts has been carried out only in some industrial fields. In order to widen the industrial application fields, a composite material is preferred for the cost performance. In the coating processes of metallic glass with the conventional deposition techniques, there is a difficulty to form thick coatings due to their low deposition rate. Thermal spraying method is one of the potential candidates to produce metallic glass composites. Metallic glass coatings can be applied to the longer parts and therefore the application field can be widened. The gas tunnel plasma spraying is one of the most important technologies for high quality ceramic coating and synthesizing functional materials. As the gas tunnel type plasma jet is superior to the properties of other conventional type plasma jets, this plasma has great possibilities for various applications in thermal processing. In this study, the gas tunnel type plasma spraying was used to form the metallic glass coatings on the stainless-steel substrate. The microstructure and surface morphology of the metallic glass coatings were examined using Fe-based metallic glass powder and Zr-based metallic glass powder as coating material. For the mechanical properties the Vickers hardness was measured on the cross section of both the coatings and the difference between the powders was compared.

  8. Type of cell death induced by seven metals in cultured mouse osteoblastic cells.

    PubMed

    Contreras, René García; Vilchis, José Rogelio Scougall; Sakagami, Hiroshi; Nakamura, Yuko; Nakamura, Yukio; Hibino, Yasushi; Nakajima, Hiroshi; Shimada, Jun

    2010-01-01

    The use of dental metal alloys in the daily clinic makes it necessary to evaluate the cytotoxicity of eluted metal components against oral cells. However, the cytotoxic mechanism and the type of cell death induced by dental metals in osteoblasts have not been well characterized. This study investigated the cytotoxicity of seven metals against the mouse osteoblastic cell line MC3T3-E1. alpha-MEM was used as a culture medium, since this medium provided much superior proliferation of MC3T3-E1 cells over DMEM. Ag (NH(3))(2)F was the most cytotoxic, followed by CuCl>CuCl(2) >CoCl(2), NiCl(2)>FeCl(3) and FeCl(2) (least toxic). None of the metals showed any apparent growth stimulating effect (so-called 'hormesis') at lower concentrations. A time course study demonstrated that two hours of contact between oral cells and Ag (NH(3))(2)F, CuCl, CoCl(2) or NiCl(2) induced irreversible cell death. Contact with these metals induced a smear pattern of DNA fragmentation without activation of caspase-3. Preincubation of MC3T3-E1 cells with either a caspase inhibitor (Z-VAD-FMK) or autophagy inhibitors (3-methyladenine, bafilomycin) failed to rescue them from metal cytotoxicity. These data suggest the induction of necrotic cell death rather than apoptosis and autophagy by metals in this osteoblastic cell line.

  9. An Investigation Of The Metallicity Dependence Of The Sn Type Ii Mn Production

    NASA Astrophysics Data System (ADS)

    Kim, Yeunjin; Sobeck, J.; Frohlich, C.; Truran, J.

    2010-01-01

    Element abundance trends over the history of our Galaxy serve as important guides in establishing relative contributions from supernovae of Types Ia and II. In particular, spectroscopic studies have revealed a deficiency of manganese (Mn) relative to the abundances of neighboring iron-peak nuclei in metal-poor stars. However, more recent analyses of the observational data have found a constant Mn/Fe abundance ratio over a wide range of metallicity and hence, contradict these previous findings. In this project, we will study the nucleosynthetic yields of Type II supernovae as a function of metallicity by parameterizing the initial properties of the shock. We will compare our results with the two distinct manganese abundance trends identified above. Once we study the metallicity dependency of Type II yields as reflected in observations at lower metallicities, we will explore the constraints this imposes on Type Ia supernova contributions to Mn in different stellar and galactic populations. We acknowledge the financial support by the National Science Foundation for the Frontier Center Joint Institute for Nuclear Astrophysics (JINA). C.F. acknowledges an Enrico Fermi Fellowship.

  10. Metallicity dependence of Type Ib/c and IIb supernova progenitors in binary systems

    NASA Astrophysics Data System (ADS)

    Yoon, Sung-CHul

    2015-08-01

    Type Ib/c supernovae (SNe Ib/c) are characterized by the lack of prominent hydrogen lines in the spectra, implying that their progenitors have lost most of their hydrogen envelopes by the time of the iron core collapse. Binary interactions provide an important evolutionary chanel for SNe Ib/c, and recent observations indicate that the inferred ejecta masses of SNe Ibc are more consistent with the prediction of the binary scenario than that of the single star scenario that invokes mass loss as the key evolutionary factor for SNe Ib/c progenitors. So far, theoretical predictions on the detailed properties of SNe Ib/c progenitors in binary systems have been made mostly with models using solar metallicity. However, unlike the single star scenario, where SNe Ib/c are expected only for sufficiently high metallicity, hydrogen-deficent SN progenitors can be produced via binary interactions at any metallicity. In this talk, I will discuss theoretical predictions on the metallicity dependence of the SNe Ib/c progenitor structure, based on evolutionary models of massive binary stars. Sepefically, I will address how the ejecta masses of SNe Ib and Ic and the ratio of SN Ib/c to SN IIb as well as SN Ib to SN Ic would systematically change as a function of metallicity, and which new types of SNe are expected in binary systems at low metallicity.

  11. Type II supernovae as probes of environment metallicity: observations of host H II regions

    NASA Astrophysics Data System (ADS)

    Anderson, J. P.; Gutiérrez, C. P.; Dessart, L.; Hamuy, M.; Galbany, L.; Morrell, N. I.; Stritzinger, M. D.; Phillips, M. M.; Folatelli, G.; Boffin, H. M. J.; de Jaeger, T.; Kuncarayakti, H.; Prieto, J. L.

    2016-05-01

    Context. Spectral modelling of type II supernova atmospheres indicates a clear dependence of metal line strengths on progenitor metallicity. This dependence motivates further work to evaluate the accuracy with which these supernovae can be used as environment metallicity indicators. Aims: To assess this accuracy we present a sample of type II supernova host H ii-region spectroscopy, from which environment oxygen abundances have been derived. These environment abundances are compared to the observed strength of metal lines in supernova spectra. Methods: Combining our sample with measurements from the literature, we present oxygen abundances of 119 host H ii regions by extracting emission line fluxes and using abundance diagnostics. These abundances are then compared to equivalent widths of Fe ii 5018 Å at various time and colour epochs. Results: Our distribution of inferred type II supernova host H ii-region abundances has a range of ~0.6 dex. We confirm the dearth of type II supernovae exploding at metallicities lower than those found (on average) in the Large Magellanic Cloud. The equivalent width of Fe ii 5018 Å at 50 days post-explosion shows a statistically significant correlation with host H ii-region oxygen abundance. The strength of this correlation increases if one excludes abundance measurements derived far from supernova explosion sites. The correlation significance also increases if we only analyse a "gold" IIP sample, and if a colour epoch is used in place of time. In addition, no evidence is found of a correlation between progenitor metallicity and supernova light-curve or spectral properties - except for that stated above with respect to Fe ii 5018 Å equivalent widths - suggesting progenitor metallicity is not a driving factor in producing the diversity that is observed in our sample. Conclusions: This study provides observational evidence of the usefulness of type II supernovae as metallicity indicators. We finish with a discussion of the

  12. Near-infrared metallicities, radial velocities, and spectral types for 447 nearby M dwarfs

    SciTech Connect

    Newton, Elisabeth R.; Charbonneau, David; Irwin, Jonathan; Berta-Thompson, Zachory K.; Rojas-Ayala, Barbara; Covey, Kevin; Lloyd, James P.

    2014-01-01

    We present metallicities, radial velocities, and near-infrared (NIR) spectral types for 447 M dwarfs determined from moderate resolution (R ≈ 2000) NIR spectra obtained with the NASA Infrared Telescope Facility (IRTF)/SpeX. These M dwarfs are primarily targets of the MEarth Survey, a transiting planet survey searching for super Earths around mid-to-late M dwarfs within 33 pc. We present NIR spectral types for each star and new spectral templates for the IRTF in the Y, J, H, and K-bands, created using M dwarfs with near-solar metallicities. We developed two spectroscopic distance calibrations that use NIR spectral type or an index based on the curvature of the K-band continuum. Our distance calibration has a scatter of 14%. We searched 27 NIR spectral lines and 10 spectral indices for metallicity sensitive features, taking into account correlated noise in our estimates of the errors on these parameters. We calibrated our relation using 36 M dwarfs in common proper pairs with an F-, G-, or K-type star of known metallicity. We validated the physical association of these pairs using proper motions, radial velocities, and spectroscopic distance estimates. Our resulting metallicity calibration uses the sodium doublet at 2.2 μm as the sole indicator for metallicity. It has an accuracy of 0.12 dex inferred from the scatter between the metallicities of the primaries and the estimated metallicities of the secondaries. Our relation is valid for NIR spectral types from M1V to M5V and for –1.0 dex < [Fe/H] < +0.35 dex. We present a new color-color metallicity relation using J – H and J – K colors that directly relates two observables: the distance from the M dwarf main sequence and equivalent width of the sodium line at 2.2 μm. We used radial velocities of M dwarf binaries, observations at different epochs, and comparison between our measurements and precisely measured radial velocities to demonstrate a 4 km s{sup –1} accuracy.

  13. Formation of Schottky-type metal/SrTiO3 junctions and their resistive properties

    NASA Astrophysics Data System (ADS)

    Stöcker, Hartmut; Zschornak, Matthias; Seibt, Juliane; Hanzig, Florian; Wintz, Susi; Abendroth, Barbara; Kortus, Jens; Meyer, Dirk C.

    2010-08-01

    Motivated by the successful use of strontium titanate with different doping metals for memory cells on the basis of resistive switching and the recent findings on the major importance of oxygen vacancy redistribution in this compound, the present work shows the possibility of a non-volatile resistance change memory based on vacancy-doped SrTiO3. The formation of corresponding metal/SrTiO3- δ junctions ( δ>0) in an electric field will be discussed as well as the switching between ohmic and Schottky-type contact behavior. A notable hysteresis in the current-voltage characteristics is used to carry out Write, Read, and Erase operations exemplifying the memory cell properties of such junctions. But whereas the electric field-induced formation of Schottky-type junctions is explainable by oxygen vacancy redistribution, the resistive switching needs to be discussed in terms of vacancies serving as electron trap states at the metal/oxide interface.

  14. Multifunctional metal rattle-type nanocarriers for MRI-guided photothermal cancer therapy

    NASA Astrophysics Data System (ADS)

    Huang, Yuran; Wei, Tuo; Yu, Jing; Hou, Yanglong; Cai, Kaiyong; Liang, Xing-jie

    2015-03-01

    Numerous nanomaterials have been developed for biomedical application, especially cancer therapy. Visualizing cancer therapy is highly promising now because of the potential ability to realize accurate, localized treatment. In this work, we firstly synthesized metal nanorattles (MNRs), which utilized porous gold shells capable of photothermal therapy to carry multiple superparmagnetic iron oxide nanoparticles (SPIONs) as MR imaging contrast agents inside. As shown in the infrared light, these metal rattle-typed nanostructures were able to convert to heat to kill cells, and inhibit tumor growth. As a carrier for multiple SPIONs, it also performed a good behavior for T2-weighted MR imaging in tumor site. Moreover, the rest of the inner space of the gold shell also introduced potential ability as nanocarriers for other cargos such as chemotherapeutic drugs, which is still under investigation. This metal-rattle-type nanocarriers is highly potential as a novel platforms for cancer therapy in the future.

  15. Integral fast reactor concept. [Pool type; metal fuel; integral fuel cycle

    SciTech Connect

    Chang, Y.I.; Marchaterre, J.F.; Sevy, R.H.

    1984-01-01

    Key features of the IFR consist of a pool-type plant arrangement, a metal fuel-based core design, and an integral fuel cycle with colocated fuel cycle facility. Both the basic concept and the technology base have been demonstrated through actual integral cycle operation in EBR-II. This paper discusses the inherent safety characteristics of the IFR concept. (DLC)

  16. Altered transition metal homeostasis in Niemann-Pick disease, Type C1

    PubMed Central

    Hung, Ya Hui; Faux, Noel G.; Killilea, David W.; Yanjanin, Nicole; Firnkes, Sally; Volitakis, Irene; Ganio, George; Walterfang, Mark; Hastings, Caroline; Porter, Forbes D.; Ory, Daniel S.; Bush, Ashley I.

    2014-01-01

    The loss of NPC1 protein function is the predominant cause of Niemann-Pick type C1 disease (NP-C1), a systemic and neurodegenerative disorder characterized by late-endosomal/lysosomal accumulation of cholesterol and other lipids. Limited evidence from post-mortem human tissues, an Npc1−/− mouse model, and cell culture studies also suggest failure of metal homeostasis in NP-C1. To investigate these findings, we performed a comprehensive transition metal analysis of cerebrospinal fluid (CSF), plasma and tissue samples from human NP-C1 patients and an Npc1−/− mouse model. NPC1 deficiency in the Npc1−/− mouse model resulted in a perturbation of transition metal homeostasis in the plasma and key organs (brain, liver, spleen, heart, lungs, and kidneys). Analysis of human patient CSF, plasma and post-mortem brain tissues also indicated disrupted metal homeostasis. There was a disparity in the direction of metal changes between the human and the Npc1−/− mouse samples, which may reflect species-specific metal metabolism. Nevertheless, common to both species is brain zinc accumulation. Furthermore, treatment with the glucosylceramide synthase inhibitor miglustat, the only drug shown in a controlled clinical trial to have some efficacy for NP-C1, did not correct the alterations in CSF and plasma transition metal and ceruloplasmin (CP) metabolism in NP-C1 patients. These findings highlight the importance of NPC1 function in metal homeostasis, and indicate that metal-targeting therapy may be of value as a treatment for NP-C. PMID:24343124

  17. Does p-type ohmic contact exist in WSe2-metal interfaces?

    NASA Astrophysics Data System (ADS)

    Wang, Yangyang; Yang, Ruo Xi; Quhe, Ruge; Zhong, Hongxia; Cong, Linxiao; Ye, Meng; Ni, Zeyuan; Song, Zhigang; Yang, Jinbo; Shi, Junjie; Li, Ju; Lu, Jing

    2015-12-01

    Formation of low-resistance metal contacts is the biggest challenge that masks the intrinsic exceptional electronic properties of two dimensional WSe2 devices. We present the first comparative study of the interfacial properties between monolayer/bilayer (ML/BL) WSe2 and Sc, Al, Ag, Au, Pd, and Pt contacts by using ab initio energy band calculations with inclusion of the spin-orbital coupling (SOC) effects and quantum transport simulations. The interlayer coupling tends to reduce both the electron and hole Schottky barrier heights (SBHs) and alters the polarity for the WSe2-Au contact, while the SOC chiefly reduces the hole SBH. In the absence of the SOC, the Pd contact has the smallest hole SBH. Dramatically, the Pt contact surpasses the Pd contact and becomes the p-type ohmic or quasi-ohmic contact with inclusion of the SOC. Therefore, p-type ohmic or quasi-ohmic contact exists in WSe2-metal interfaces. Our study provides a theoretical foundation for the selection of favorable metal electrodes in ML/BL WSe2 devices.Formation of low-resistance metal contacts is the biggest challenge that masks the intrinsic exceptional electronic properties of two dimensional WSe2 devices. We present the first comparative study of the interfacial properties between monolayer/bilayer (ML/BL) WSe2 and Sc, Al, Ag, Au, Pd, and Pt contacts by using ab initio energy band calculations with inclusion of the spin-orbital coupling (SOC) effects and quantum transport simulations. The interlayer coupling tends to reduce both the electron and hole Schottky barrier heights (SBHs) and alters the polarity for the WSe2-Au contact, while the SOC chiefly reduces the hole SBH. In the absence of the SOC, the Pd contact has the smallest hole SBH. Dramatically, the Pt contact surpasses the Pd contact and becomes the p-type ohmic or quasi-ohmic contact with inclusion of the SOC. Therefore, p-type ohmic or quasi-ohmic contact exists in WSe2-metal interfaces. Our study provides a theoretical foundation for

  18. Ultraviolet Spectral Synthesis and Oxygen in Metal-Poor Solar-Type Stars

    NASA Astrophysics Data System (ADS)

    Peterson, R. C.

    1999-05-01

    This report outlines the progress and pitfalls of calculating spectra from first principles in the 2300 -- 3400A region for metal-poor solar-type stars, and how they relate to the derivation of abundances of key species such as oxygen and magnesium. This work is part of a NASA-supported effort with Ben Dorman of Goddard Space Flight Center to develop ab initio spectra suitable for galaxy analysis, and also part of a HST-oriented program with Karel Schrijver of Lockheed Martin to characterize the chromospheric activity of the oldest solar-type stars. The first task has been a reanalysis of the basic stellar parameters of temperature, surface gravity, and metallicity for solar-temperature stars ranging from one-fifth to one-three hundredth solar metallicity, demanding agreement in line strengths and profiles of strong lines and weak, in both optical and ultraviolet, and in the ultraviolet flux distribution. These cross-checks are built in to ensure convergence to a unique solution, or to highlight where standard assumptions are breaking down. Once agreement is achieved for the most metal-deficient stars, the line list used for the spectral calculations is re-examined, and somewhat more metal-rich stars are matched. Abundance results for oxygen from various approaches will be described, from the near-UV OH, 6300A [O I], and near-IR O I lines, and from adopting laboratory versus theoretical versus astrophysical atomic and molecular constants.

  19. Th1 type lymphocyte reactivity to metals in patients with total hip arthroplasty

    PubMed Central

    Hallab, Nadim James; Caicedo, Marco; Finnegan, Alison; Jacobs, Joshua J

    2008-01-01

    Background All prostheses with metallic components release metal debris that can potentially activate the immune system. However, implant-related metal hyper-reactivity has not been well characterized. In this study, we hypothesized that adaptive immunity reaction(s), particularly T-helper type 1 (Th1) responses, will be dominant in any metal-reactivity responses of patients with total joint replacements (TJAs). We tested this hypothesis by evaluating lymphocyte reactivity to metal "ions" in subjects with and without total hip replacements, using proliferation assays and cytokine analysis. Methods Lymphocytes from young healthy individuals without an implant or a history of metal allergy (Group 1: n = 8) were used to assess lymphocyte responses to metal challenge agents. In addition, individuals (Group 2: n = 15) with well functioning total hip arthroplasties (average Harris Hip Score = 91, average time in-situ 158 months) were studied. Age matched controls with no implants were also used for comparison (Group 3, n = 8, 4 male, 4 female average age 70, range 49–80). Group 1 subjects' lymphocyte proliferation response to Aluminum+3, Cobalt+2, Chromium+3, Copper+2, Iron+3, Molybdenum+5, Manganeese+2, Nickel+2, Vanadium+3 and Sodium+2 chloride solutions at a variety of concentrations (0.0, 0.05, 0.1, 0.5, 1.0 and 10.0 mM) was studied to establish toxicity thresholds. Mononuclear cells from Group 2 and 3 subjects were challenged with 0.1 mM CrCl3, 0.1 mM NiCl2, 0.1 mM CoCl2 and approx. 0.001 mM titanium and the reactions measured with proliferation assays and cytokine analysis to determine T-cell subtype prominence. Results Primary lymphocytes from patients with well functioning total hip replacements demonstrated a higher incidence and greater magnitude of reactivity to chromium than young healthy controls (p < 0.03). Of the 15 metal ion-challenged subjects with well functioning total hip arthroplasties, 7 demonstrated a proliferative response to Chromium, Nickel

  20. Description of two-metal biosorption equilibria by Langmuir-type models

    SciTech Connect

    Chong, K.H.; Volesky, B.

    1995-08-20

    A biosorbent prepared from Ascophyllum nodosum seaweed biomass, FCAN2, was examined for its sorption capacity. Equilibrium batch sorption studies were performed using two-metal systems containing either (Cu+Zn), (Cu+Cd), or (Zn+Cd). In the evaluation of the two-metal sorption system performance, simple isotherm curves had to be replaced by three-dimensional sorption isotherm surfaces. In order to describe the isotherm surfaces mathematically, three Langmuir-type models were evaluated. The apparent one-parameter Langmuir constant (b) was used to quantify FCAN2 ``affinity`` for one metal in the presence of another one. The uptake of Zn decreased drastically when Cu of Cd were present. The uptake of Cd was much more sensitive to the presence of Cu than to that of Zn. The presence of Cd and Zn alter the ``affinity`` of FCAN2 for Cu the least at high Cu equilibrium concentrations. The mathematical model of the two-metal sorption system enabled quantitative estimation of one-metal (bio)sorption inhibition due to the influence of a second metal.

  1. n-Type reduced graphene oxide field-effect transistors (FETs) from photoactive metal oxides.

    PubMed

    Yoo, Heejoun; Kim, Youngmin; Lee, Junghyun; Lee, Hyemi; Yoon, Yeoheung; Kim, Giyoun; Lee, Hyoyoung

    2012-04-16

    Graphene is of considerable interest as a next-generation semiconductor material to serve as a possible substitute for silicon. For real device applications with complete circuits, effective n-type graphene field effect transistors (FETs) capable of operating even under atmospheric conditions are necessary. In this study, we investigated n-type reduced graphene oxide (rGO) FETs of photoactive metal oxides, such as TiO(2) and ZnO. These metal oxide doped FETs showed slight n-type electric properties without irradiation. Under UV light these photoactive materials readily generated electrons and holes, and the generated electrons easily transferred to graphene channels. As a result, the graphene FET showed strong n-type electric behavior and its drain current was increased. These n-doping effects showed saturation curves and slowly returned back to their original state in darkness. Finally, the n-type rGO FET was also highly stable in air due to the use of highly resistant metal oxides and robust graphene as a channel.

  2. Production of multicharged metal ion beams on the first stage of tandem-type ECRIS

    SciTech Connect

    Hagino, Shogo Nagaya, Tomoki; Nishiokada, Takuya; Otsuka, Takuro; Sato, Fuminobu; Kato, Yushi; Muramatsu, Masayuki; Kitagawa, Atsushi

    2016-02-15

    Multicharged metal ion beams are required to be applied in a wide range of fields. We aim at synthesizing iron-endohedral fullerene by transporting iron ion beams from the first stage into the fullerene plasma in the second stage of the tandem-type electron cyclotron resonance ion source (ECRIS). We developed new evaporators by using a direct ohmic heating method and a radiation heating method from solid state pure metal materials. We investigate their properties in the test chamber and produce iron ions on the first stage of the tandem-type ECRIS. As a result, we were successful in extracting Fe{sup +} ion beams from the first stage and introducing Fe{sup +} ion beams to the second stage. We will try synthesizing iron-endohedral fullerene on the tandem-type ECRIS by using these evaporators.

  3. TESTING THE METAL OF LATE-TYPE KEPLER PLANET HOSTS WITH IRON-CLAD METHODS

    SciTech Connect

    Mann, Andrew W.; Hilton, Eric J.; Gaidos, Eric; Kraus, Adam

    2013-06-10

    It has been shown that F, G, and early K dwarf hosts of Neptune-sized planets are not preferentially metal-rich. However, it is less clear whether the same holds for late K and M dwarf planet hosts. We report metallicities of Kepler targets and candidate transiting planet hosts with effective temperatures below 4500 K. We use new metallicity calibrations to determine [Fe/H] from visible and near-infrared spectra. We find that the metallicity distribution of late K and M dwarfs monitored by Kepler is consistent with that of the solar neighborhood. Further, we show that hosts of Earth- to Neptune-sized planets have metallicities consistent with those lacking detected planets and rule out a previously claimed 0.2 dex offset between the two distributions at 6{sigma} confidence. We also demonstrate that the metallicities of late K and M dwarfs hosting multiple detected planets are consistent with those lacking detected planets. Our results indicate that multiple terrestrial and Neptune-sized planets can form around late K and M dwarfs with metallicities as low as 0.25 solar. The presence of Neptune-sized planets orbiting such low-metallicity M dwarfs suggests that accreting planets collect most or all of the solids from the disk and that the potential cores of giant planets can readily form around M dwarfs. The paucity of giant planets around M dwarfs compared to solar-type stars must be due to relatively rapid disk evaporation or a slower rate of planet accretion, rather than insufficient solids to form a core.

  4. Frequency of Angina Pectoris After Percutaneous Coronary Intervention and the Effect of Metallic Stent Type.

    PubMed

    Gaglia, Michael A; Torguson, Rebecca; Lipinski, Michael J; Gai, Jiaxiang; Koifman, Edward; Kiramijyan, Sarkis; Negi, Smita; Rogers, Toby; Steinvil, Arie; Suddath, William O; Satler, Lowell F; Pichard, Augusto D; Waksman, Ron

    2016-02-15

    Although metallic coronary stents significantly reduce angina pectoris compared with optimal medical therapy, angina after percutaneous coronary intervention (PCI) remains frequent. We, therefore, sought to compare the incidence of any angina during the 1 year after PCI among the spectrum of commercially available metallic stents. Metallic stent type was classified as bare metal stent, Cypher, Taxus Express, Xience V, Promus Element, and Resolute. The primary end point was patient-reported angina within 1 year of PCI. Multivariable logistic regression was performed to assess the independent association of stent type with any angina at 1 year. Overall, 8,804 patients were queried in regard to angina symptoms; 32.3% experienced angina at some point in the first year after PCI. Major adverse cardiovascular events, a composite of all-cause mortality, target vessel revascularization, and Q-wave myocardial infarction, increased with angina severity: 6.8% for patients without angina, 10.0% for patients with class 1 or 2 angina, and 19.7% for patients with class 3 or 4 angina (p <0.001 for trend). After multivariable adjustment, there was no significant association between stent type and angina at 1 year after PCI. Baseline Canadian Cardiovascular Society class 3 or 4 angina, history of coronary artery bypass grafting, and history of PCI were associated with a higher likelihood of angina at 1 year; increasing age, male gender, presentation with acute coronary syndrome, and higher stented length were associated with less angina. In conclusion, metallic stent type is not associated with the occurrence of angina at up to 1 year after PCI.

  5. Precipitation of sigma and chi phases in δ-ferrite of Type 316FR weld metals

    SciTech Connect

    Chun, Eun Joon; Baba, Hayato; Nishimoto, Kazutoshi; Saida, Kazuyoshi

    2013-12-15

    The decomposition behavior and kinetics of δ-ferrite are examined using aging treatments between 873 and 1073 K for Type 316FR stainless steel weld metals with different solidification modes (316FR AF, 316FR FA). The dominant precipitates are sigma, chi, and secondary austenite nucleated at δ-ferrite/austenite interfaces or in the interior of the ferrite grains. These precipitates consume all the ferrite during isothermal aging in both 316FR AF and FA weld metals. Differences in the precipitation behavior (precipitation initiation time and precipitation speed) between weld metals can be explained by i) the degree of Cr and Mo microsegregation within δ-ferrite or austenite near ferrite and ii) the nucleation sites induced due to the solidification mode (AF or FA), such as the ferrite amount. For both weld materials, a Johnson–Mehl-type equation can express the precipitation behavior of the sigma + chi phases and quantitatively predict the behavior at the service-exposure temperatures of a fast breed reactor. - Highlights: • Precipitation of σ and χ phase in Type 316FR welds (two solidification modes) • Different precipitation behaviors: precipitation initiation time and growth speed • Johnson-Mehl–type equation is the most applicable to the precipitation behaviors • Precipitation behaviors are predicted under service conditions of FBRs.

  6. Metal Selectivity of a Cd-, Co-, and Zn-Transporting P1B-type ATPase

    PubMed Central

    Smith, Aaron T.; Ross, Matthew O.; Hoffman, Brian M.; Rosenzweig, Amy C.

    2017-01-01

    The P1B-ATPases, a family of transmembrane metal transporters important for transition metal homeostasis in all organisms, are subdivided into classes based on sequence conservation and metal specificity. The multifunctional P1B-4-ATPase CzcP is part of the cobalt, zinc, and cadmium resistance system from the metal-tolerant, model organism Cupriavidus metallidurans. Previous work revealed the presence of an unusual soluble metal-binding domain (MBD) at the CzcP N-terminus, but the nature, extent, and selectivity of the transmembrane metal-binding site (MBS) of CzcP have not been resolved. Using homology modeling, we show that four wholly conserved amino acids from the transmembrane (TM) domain (Met254, Ser474, Cys476, and His807) are logical candidates for the TM MBS, which may communicate with the MBD via interactions with the first TM helix. Metal-binding analyses indicate that wild-type (WT) CzcP has three MBSs, and data on N-terminally truncated (ΔMBD) CzcP suggest the presence of a single TM MBS. Electronic absorption and electron paramagnetic resonance spectroscopic analyses of ΔMBD CzcP and variant proteins thereof provide insight into the details of Co2+ coordination by the TM MBS. These spectroscopic data, combined with in vitro functional studies of WT and variant CzcP proteins, show that the side chains of Met254, Cys476, and His807 contribute to Cd2+, Co2+, and Zn2+ binding and transport, whereas the side chain of Ser474 appears to play a minimal role. By comparison to other P1B-4-ATPases, we suggest that an evolutionarily adapted flexibility in the TM region likely afforded CzcP the ability to transport Cd2+ and Zn2+ in addition to Co2+. PMID:28001366

  7. Metallicity dependence of Type Ib/c and IIb supernova progenitors in binary systems

    NASA Astrophysics Data System (ADS)

    Yoon, Sung-Chul

    Type Ib/c supernovae (SNe Ib/c) are characterized by the lack of prominent hydrogen lines in thespectra, implying that their progenitors have lost most of their hydrogen envelopes by the time of the iron corecollapse. Binary interactions provide an important evolutionary chanel for SNe Ib/c, and recent observations indicatethat the inferred ejecta masses of SNe Ibc are more consistent with the prediction of the binary scenario than that ofthe single star scenario that invokes mass loss as the key evolutionary factor for SNe Ib/c progenitors. So far,theoretical predictions on the detailed properties of SNe Ib/c progenitors in binary systems have been made mostlywith models using solar metallicity. However, unlike the single star scenario, where SNe Ib/c are expected only forsufficiently high metallicity, hydrogen-deficent SN progenitors can be produced via binary interactions at anymetallicity. In this talk, I will discuss theoretical predictions on the metallicity dependence of the SNe Ib/c progenitorstructure, based on evolutionary models of massive binary stars. Sepefically, I will address how the ejecta masses ofSNe Ib and Ic and the ratio of SN Ib/c to SN IIb as well as SN Ib to SN Ic would systematically change as a function ofmetallicity, and which new types of SNe are expected in binary systems at low metallicity.

  8. Bellows-Type Accumulators for Liquid Metal Loops of Space Reactor Power Systems

    NASA Astrophysics Data System (ADS)

    Tournier, Jean-Michel; El-Genk, Mohamed S.

    2006-01-01

    In many space nuclear power systems, the primary and/or secondary loops use liquid metal working fluids, and require accumulators to accommodate the change in the liquid metal volume and maintain sufficient subcooling to avoid boiling. This paper developed redundant and light-weight bellows-type accumulators with and without a mechanical spring, and compared the operating condition and mass of the accumulators for different types of liquid metal working fluids and operating temperatures: potassium, NaK-78, sodium and lithium loops of a total capacity of 50 liters and nominal operating temperatures of 840 K, 860 K, 950 K and 1340 K, respectively. The effects of using a mechanical spring and different structural materials on the design, operation and mass of the accumulators are also investigated. The structure materials considered include SS-316, Hastelloy-X, C-103 and Mo-14Re. The accumulator without a mechanical spring weighs 23 kg and 40 kg for a coolant subcooling of 50 K and 100 K, respectively, following a loss of the fill gas. The addition of a mechanical spring comes with a mass penalty, in favor of higher redundancy and maintaining a higher liquid metal subcooling.

  9. Bellows-Type Accumulators for Liquid Metal Loops of Space Reactor Power Systems

    SciTech Connect

    Tournier, Jean-Michel; El-Genk, Mohamed S.

    2006-01-20

    In many space nuclear power systems, the primary and/or secondary loops use liquid metal working fluids, and require accumulators to accommodate the change in the liquid metal volume and maintain sufficient subcooling to avoid boiling. This paper developed redundant and light-weight bellows-type accumulators with and without a mechanical spring, and compared the operating condition and mass of the accumulators for different types of liquid metal working fluids and operating temperatures: potassium, NaK-78, sodium and lithium loops of a total capacity of 50 liters and nominal operating temperatures of 840 K, 860 K, 950 K and 1340 K, respectively. The effects of using a mechanical spring and different structural materials on the design, operation and mass of the accumulators are also investigated. The structure materials considered include SS-316, Hastelloy-X, C-103 and Mo-14Re. The accumulator without a mechanical spring weighs 23 kg and 40 kg for a coolant subcooling of 50 K and 100 K, respectively, following a loss of the fill gas. The addition of a mechanical spring comes with a mass penalty, in favor of higher redundancy and maintaining a higher liquid metal subcooling.

  10. A transmembrane Type-2-like Cu2+ site in the P1B-3-type ATPase CopB: implications for metal selectivity

    PubMed Central

    Meloni, Gabriele; Zhang, Limei; Rees, Douglas C.

    2013-01-01

    Metal selectivity in P1B-type ATPase transporters is determined by conserved amino acid residues in their transmembrane helices responsible for metal binding and transport across the cellular membrane. The Cu2+-selective CopB from Archaeoglobus fulgidus has been investigated to explore the coordination chemistry of the transition metal binding sites in P1B-3-type ATPases. Electronic absorption, electron paramagnetic resonance and X-ray absorption spectroscopic studies indicate the presence of a high-affinity transmembrane Type-2-like Cu2+ center in which a single cupric ion is coordinated in a distorted square pyramidal geometry by mixed nitrogen/oxygen and sulphur ligands. PMID:24144006

  11. Two types of noble metal mineralization in the Kaalamo massif (Karelia)

    NASA Astrophysics Data System (ADS)

    Ivashchenko, V. I.; Ruchyev, A. M.; Golubev, A. I.

    2016-05-01

    Noble metal mineralization of the syngenetic (Southern Kaalamo) and epigenetic (Surisuo) types are defined in the Kaalamo massif. The ƩPt, Pd, Au content is as high as 0.9-1.1 g/t. Syngenetic mineralization started at the late magmatic stage (at around 800°C) gradually evolving to cease during the hydrothermal-metasomatic stage (<271°C). Epigenetic mineralization was formed at temperatures ranging from 500 to <230°C in zones of intense shear deformations and low-temperature metasomatosis during the collisional stage of the Svecofennian tectono-magmatic cycle (approximately 1.85 Ga ago). Taking into consideration the geological position of the Kaalamo massif in the Raakhe-Ladoga metallogenic zone with widely developed intense shear dislocations, the epigenetic mineralization type seems to be more promising with respect to noble metals.

  12. Synthesis and initial transition metal chemistry of the first PGeP pincer-type germylene.

    PubMed

    Álvarez-Rodríguez, Lucía; Brugos, Javier; Cabeza, Javier A; García-Álvarez, Pablo; Pérez-Carreño, Enrique; Polo, Diego

    2017-01-16

    A PGeP pincer-type germylene, Ge(NCH2P(t)Bu2)2C6H4, which contains two phosphane groups hanging from the N atoms of an N-heterocyclic germylene fragment, has been isolated for the first time. This compound has already furnished a rich transition metal derivative chemistry (Co, Rh, and Pd) that includes complexes containing bridging P,Ge,P-, chelating P,Ge- and pincer P,Ge,P-ligands.

  13. Bendable n-Type Metallic Nanocomposites with Large Thermoelectric Power Factor.

    PubMed

    Chen, Yani; He, Minhong; Liu, Bin; Bazan, Guillermo C; Zhou, Jun; Liang, Ziqi

    2017-01-01

    Highly bendable n-type thermoelectric nanocomposites are successfully developed by embedding metallic Ni nanowires within an insulating poly(vinylidene fluoride) (PVDF) matrix in solution. These nanocomposites exhibit an abnormal decoupling of the electrical conductivity and Seebeck coefficient as a function of Ni contents. A maximum power factor of 220 µW m(-1) K(-2) and ZT of 0.15 can thus be obtained with 80 wt% Ni at 380 K.

  14. Predominant factor determining wear properties of β-type and (α+β)-type titanium alloys in metal-to-metal contact for biomedical applications.

    PubMed

    Lee, Yoon-Seok; Niinomi, Mitsuo; Nakai, Masaaki; Narita, Kengo; Cho, Ken

    2015-01-01

    The predominant factor determining the wear properties of a new titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ) and a conventional titanium alloy, Ti-6Al-4V extra-low interstitial (Ti64) was investigated for TNTZ and Ti64 combinations in metal-to-metal contacting bio-implant applications. The worn surfaces, wear debris, and subsurface damages were analyzed using a scanning electron microscopy combined with energy-dispersive spectroscopy and electron-back scattered diffraction analysis. The volume loss of TNTZ is found to be larger than that of Ti64, regardless of the mating material. The wear track of TNTZ exhibits the galled regions and severe plastic deformation with large flake-like debris, indicative of delamination wear, which strongly suggests the occurrence of adhesive wear. Whereas, the wear track of Ti64 have a large number of regular grooves and microcuttings with cutting chip-like wear debris and microfragmentation of fine oxide debris, indicative of abrasive wear combined with oxidative wear. This difference in the wear type is caused by severe and mild subsurface deformations of TNTZ and Ti64, respectively. The lower resistance to plastic shearing for TNTZ compared to that of Ti64 induces delamination, resulting in a higher wear rate.

  15. Calibration of Gurson-type models for porous sheet metals with anisotropic non-quadratic plasticity

    NASA Astrophysics Data System (ADS)

    Gologanu, M.; Kami, A.; Comsa, D. S.; Banabic, D.

    2016-08-01

    The growth and coalescence of voids in sheet metals are not only the main active mechanisms in the final stages of fracture in a necking band, but they also contribute to the forming limits via changes in the normal directions to the yield surface. A widely accepted method to include void effects is the development of a Gurson-type model for the appropriate yield criterion, based on an approximate limit analysis of a unit cell containing a single spherical, spheroidal or ellipsoidal void. We have recently [2] obtained dissipation functions and Gurson-type models for porous sheet metals with ellipsoidal voids and anisotropic non-quadratic plasticity, including yield criteria based on linear transformations (Yld91 and Yld2004-18p) and a pure plane stress yield criteria (BBC2005). These Gurson-type models contain several parameters that depend on the void and cell geometries and on the selected yield criterion. Best results are obtained when these key parameters are calibrated via numerical simulations using the same unit cell and a few representative loading conditions. The single most important such loading condition corresponds to a pure hydrostatic macroscopic stress (pure pressure) and the corresponding velocity field found during the solution of the limit analysis problem describes the expansion of the cavity. However, for the case of sheet metals, the condition of plane stress precludes macroscopic stresses with large triaxiality or ratio of mean stress to equivalent stress, including the pure hydrostatic case. Also, pure plane stress yield criteria like BBC2005 must first be extended to 3D stresses before attempting to develop a Gurson-type model and such extensions are purely phenomenological with no due account for the out- of-plane anisotropic properties of the sheet. Therefore, we propose a new calibration method for Gurson- type models that uses only boundary conditions compatible with the plane stress requirement. For each such boundary condition we use

  16. Frequencies of heavy metal resistance are associated with land cover type in the Upper Mississippi River.

    PubMed

    Staley, Christopher; Johnson, Dylan; Gould, Trevor J; Wang, Ping; Phillips, Jane; Cotner, James B; Sadowsky, Michael J

    2015-04-01

    Taxonomic compositions of freshwater bacterial communities have been well-characterized via metagenomic and amplicon-based approaches, especially next-generation sequencing. However, functional diversity of these communities remains less well-studied. Various anthropogenic sources are known to impact the bacterial community composition in freshwater riverine systems and potentially alter functional diversity. In this study, high-throughput functional screening of large (~10,000 clones) fosmid libraries representing communities in the Upper Mississippi River revealed low frequencies of resistance to heavy metals in the following order: Mn2+>Cr3+>Zn2+>Cd2+>Hg2+. No resistance to Cu2+ was detected. Significant, but weak, correlations were observed between resistance frequencies of Cd and Cr with developed land cover (r2=0.08, P=0.016 and r=0.07, P=0.037, respectively). While discriminant function analyses further supported these associations, redundancy analysis further indicated associations with forested land cover and greater resistance to Hg and Zn. Nutrient and metal ion concentrations and abundances of bacterial orders were poorly correlated with heavy metal resistance, except for an association of Pseudomonadales abundance and resistance to Hg and Zn. Taken together, results of this study suggest that allochthonous bacteria contributed from specific land cover types influence the patterns of metal resistance throughout this river.

  17. Long-Term Sorption of Metals Is Similar among Plastic Types: Implications for Plastic Debris in Aquatic Environments

    PubMed Central

    Rochman, Chelsea M.; Hentschel, Brian T.; Teh, Swee J.

    2014-01-01

    Concerns regarding plastic debris and its ability to accumulate large concentrations of priority pollutants in the aquatic environment led us to quantify relationships between different types of mass-produced plastic and metals in seawater. At three locations in San Diego Bay, we measured the accumulation of nine targeted metals (aluminum, chromium, manganese, iron, cobalt, nickel, zinc, cadmium and lead) sampling at 1, 3, 6, 9 and 12 months, to five plastic types: polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), and polypropylene (PP). Accumulation patterns were not consistent over space and time, and in general all types of plastic tended to accumulate similar concentrations of metals. When we did observe significant differences among concentrations of metals at a single sampling period or location in San Diego Bay, we found that HDPE typically accumulated lesser concentrations of metals than the other four polymers. Furthermore, over the 12-month study period, concentrations of all metals increased over time, and chromium, manganese, cobalt, nickel, zinc and lead did not reach saturation on at least one plastic type during the entire 12-month exposure. This suggests that plastic debris may accumulate greater concentrations of metals the longer it remains at sea. Overall, our work shows that a complex mixture of metals, including those listed as priority pollutants by the US EPA (Cd, Ni, Zn and Pb), can be found on plastic debris composed of various plastic types. PMID:24454866

  18. Metals in proteins: correlation between the metal-ion type, coordination number and the amino-acid residues involved in the coordination.

    PubMed

    Dokmanić, Ivan; Sikić, Mile; Tomić, Sanja

    2008-03-01

    Metal ions are constituents of many metalloproteins, in which they have either catalytic (metalloenzymes) or structural functions. In this work, the characteristics of various metals were studied (Cu, Zn, Mg, Mn, Fe, Co, Ni, Cd and Ca in proteins with known crystal structure) as well as the specificity of their environments. The analysis was performed on two data sets: the set of protein structures in the Protein Data Bank (PDB) determined with resolution <1.5 A and the set of nonredundant protein structures from the PDB. The former was used to determine the distances between each metal ion and its electron donors and the latter was used to assess the preferred coordination numbers and common combinations of amino-acid residues in the neighbourhood of each metal. Although the metal ions considered predominantly had a valence of two, their preferred coordination number and the type of amino-acid residues that participate in the coordination differed significantly from one metal ion to the next. This study concentrates on finding the specificities of a metal-ion environment, namely the distribution of coordination numbers and the amino-acid residue types that frequently take part in coordination. Furthermore, the correlation between the coordination number and the occurrence of certain amino-acid residues (quartets and triplets) in a metal-ion coordination sphere was analysed. The results obtained are of particular value for the identification and modelling of metal-binding sites in protein structures derived by homology modelling. Knowledge of the geometry and characteristics of the metal-binding sites in metalloproteins of known function can help to more closely determine the biological activity of proteins of unknown function and to aid in design of proteins with specific affinity for certain metals.

  19. Direct metal micropatterning on needle-type structures towards bioimpedance and chemical sensing applications

    NASA Astrophysics Data System (ADS)

    Kim, Sanghyeok; Park, Jae-ho; Kang, Kyungnam; Park, Chong-Ook; Park, Inkyu

    2015-01-01

    Direct metal patterning methods, such as screen printing, inkjet printing and gravure/flexography printing, are widely used to form electrodes or interconnections for printed electronic devices due to their inexpensive, simple and rapid fabrication as compared to vacuum-based conventional metallization processes. Here, we present direct metal patterning by modified screen printing on the curved surface of needle-type rod structures (i.e. rods with radius of ρ < 1 mm). We achieved various microscale patterns such as straight lines, zigzag lines, wavy lines and alphabetic words with a minimum width of 70 µm on the surface of the rod. Also, four pairs of line patterns were printed on the single rod for electrical interconnection. Printed patterns on the surface of the rod were used as electrodes for the control of a light emission diode (LED) as well as the real-time electrochemical impedance spectroscopy of electrolyte solutions and solid objects by the rod insertion. Furthermore, needles with multiple pairs of microelectrodes were used to measure the electrical impedance of biological samples such as fat and muscle tissues of porcine meat. In addition, a needle-type probe sensor with gas sensing capability was demonstrated by using a needle with printed Ag electrodes and Pd thin films.

  20. Annihilation momentum density of positrons trapped at vacancy-type defects in metals and alloys

    SciTech Connect

    Bansil, A.; Prasad, R.; Benedek, R.

    1988-01-01

    Positron annihilation, especially the angular correlation of annihilation radiation, is a powerful tool for investigating the electronic spectra of ordered as well as defected materials. The tendency of positrons to trap at vacancy-type defects should enable this technique to study the local environment of such defects. However, we need to develop a theoretical basis for calculating the two-photon annihilation momentum density rho/sub 2gamma/(p-vector). We have recently formulated and implemented a theory of rho/sub 2gamma/(p-vector) from vacancy-type defects in metals and alloys. This article gives an outline of our approach together with a few of our results. Section 2 summarizes the basic equations for evaluating rho/sub 2gamma/(p-vector). Our Green's function-based approach is nonperturbative and employs a realistic (one-particle) muffin-tin Hamiltonian for treating electrons and positrons. Section 3 presents and discusses rho/sub 2gamma/(p-vector) results for a mono-vacancy in Cu. We have neglected the effects of electron-positron correlations and of lattice distortion around the vacancy. Section 4 comments briefly on the question of treating defects such as divacancies and metal-impurity complexes in metals and alloys. Finally, in Section 5, we remark on the form of rho/sub 2gamma/(p-vector) for a mono-vacancy in jellium. 2 figs.

  1. Coronal Thermal Structure and Abundance of Super-Metal-Rich Late-Type Stars

    NASA Technical Reports Server (NTRS)

    Brickhouse, Nancy; Mushotzky, Richard F. (Technical Monitor)

    2002-01-01

    This report covers the NASA grant NAG5-9943 for Cycle 1 XMM Guest Observer Program. The project is entitled 'Coronal Thermal Structure and Abundances of Super-Metal-Rich Late-Type Stars.' This observation is for grating spectroscopy of 30 Ari, a late-type star with very high metallicity (about twice solar). The goal is to use extreme cases to help understand how abundances change from the photosphere to the corona. The target was obtained by XMM-Newton on 2001 January 16 for 28000 sec. Data processing could not proceed until last fall because the SAS RGS software did not work. A poster was presented at the conference 'New Visions of the X-ray Universe in the XMM-Newton and Chandra Era,' held in Noordwijk 26-30 November 2001. The paper was entitled,'Coronal Abundances and Thermal Structure of the Super-Metal-Rich Star 30 Ari,'. The poster presented analysis of EPIC and RGS data to determine the individual abundances from the star and the emission measure distribution as a function of temperature. Results were compared with previous results on this star by our team using ASCA data.

  2. Analysis of Metal Contents in Portland Type V and MTA-Based Cements

    PubMed Central

    Dorileo, Maura Cristiane Gonçales Orçati; Bandeca, Matheus Coelho; Pedro, Fábio Luis Miranda; Volpato, Luiz Evaristo Ricci; Guedes, Orlando Aguirre; Villa, Ricardo Dalla; Tonetto, Mateus Rodrigues; Borges, Alvaro Henrique

    2014-01-01

    The aim of this study was to determine, by Atomic Absorption Spectrometry (AAS), the concentration levels of 11 metals in Type V gray and structural white PC, ProRoot MTA, and MTA Bio. Samples, containing one gram of each tested cement, were prepared and transferred to a 100 mL Teflon tube with a mixture of 7.0 mL of nitric acid and 21 mL of hydrochloric acid. After the reaction, the mixture was filtered and then volumed to 50 mL of distilled water. For each metal, specific patterns were determined from universal standards. Arsenic quantification was performed by hydride generator. The analysis was performed five times and the data were statistically analyzed at 5% level of significance. Only the cadmium presented concentration levels of values lower than the quantification limit of the device. The AAS analysis showed increased levels of calcium, nickel, and zinc in structural white PC. Type V PC presented the greatest concentration levels of arsenic, chromium, copper, iron, lead, and manganese (P < 0.05). Bismuth was found in all cements, and the lowest concentration levels were observed in Portland cements, while the highest were observed in ProRoot MTA. Both PC and MTA-based cements showed evidence of metals inclusion. PMID:25436238

  3. Analysis of metal contents in Portland Type V and MTA-based cements.

    PubMed

    Dorileo, Maura Cristiane Gonçales Orçati; Bandeca, Matheus Coelho; Pedro, Fábio Luis Miranda; Volpato, Luiz Evaristo Ricci; Guedes, Orlando Aguirre; Dalla Villa, Ricardo; Tonetto, Mateus Rodrigues; Borges, Alvaro Henrique

    2014-01-01

    The aim of this study was to determine, by Atomic Absorption Spectrometry (AAS), the concentration levels of 11 metals in Type V gray and structural white PC, ProRoot MTA, and MTA Bio. Samples, containing one gram of each tested cement, were prepared and transferred to a 100 mL Teflon tube with a mixture of 7.0 mL of nitric acid and 21 mL of hydrochloric acid. After the reaction, the mixture was filtered and then volumed to 50 mL of distilled water. For each metal, specific patterns were determined from universal standards. Arsenic quantification was performed by hydride generator. The analysis was performed five times and the data were statistically analyzed at 5% level of significance. Only the cadmium presented concentration levels of values lower than the quantification limit of the device. The AAS analysis showed increased levels of calcium, nickel, and zinc in structural white PC. Type V PC presented the greatest concentration levels of arsenic, chromium, copper, iron, lead, and manganese (P < 0.05). Bismuth was found in all cements, and the lowest concentration levels were observed in Portland cements, while the highest were observed in ProRoot MTA. Both PC and MTA-based cements showed evidence of metals inclusion.

  4. Randomly Distributed Fabry-Pérot-type Metal Nanowire Resonators and Their Lasing Action

    PubMed Central

    Kwon, Kyungmok; Jung, Youngho; Kim, Minkyung; Shim, Jaeho; Yu, Kyoungsik

    2016-01-01

    Optical feedback mechanisms are often obtained from well-defined resonator structures fabricated by top-down processes. Here, we demonstrate that two-dimensional networks of metallic nanowires dispersed on the semiconductor slab can provide strong in-plane optical feedback and, thus, form randomly-distributed Fabry-Pérot-type resonators that can achieve multi- or single-mode lasing action in the near infrared wavelengths. Albeit with their subwavelength-scale cross-sections and uncontrolled inter-nanowire distances, a cluster of nearly parallel metal nanowires acts as an effective in-situ reflector for the semiconductor-metal slab waveguide modes for coherent optical feedback in the lateral direction. Fabry-Pérot type resonance can be readily developed by a pair of such clusters coincidentally formed in the solution-processed random nanowire network. Our low-cost and large-area approach for opportunistic random cavity formation would open a new pathway for integrated planar light sources for low-coherence imaging and sensing applications. PMID:27102220

  5. Type-II Dirac fermions in the PtSe2 class of transition metal dichalcogenides

    NASA Astrophysics Data System (ADS)

    Huang, Huaqing; Zhou, Shuyun; Duan, Wenhui

    2016-09-01

    Recently, a new "type-II" Weyl fermion, which exhibits exotic phenomena, such as an angle-dependent chiral anomaly, was discovered in a new phase of matter where electron and hole pockets contact at isolated Weyl points [Nature (London) 527, 495 (2015), 10.1038/nature15768]. This raises an interesting question about whether its counterpart, i.e., a type-II Dirac fermion, exists in real materials. Here, we predict the existence of symmetry-protected type-II Dirac fermions in a class of transition metal dichalcogenide materials. Our first-principles calculations on PtSe2 reveal its bulk type-II Dirac fermions which are characterized by strongly tilted Dirac cones, novel surface states, and exotic doping-driven Lifshitz transition. Our results show that the existence of type-II Dirac fermions in PtSe2-type materials is closely related to its structural P 3 ¯m 1 symmetry, which provides useful guidance for the experimental realization of type-II Dirac fermions and intriguing physical properties distinct from those of the standard Dirac fermions known before.

  6. Evidence for Half-Metallicity in n -type HgCr2 Se4

    NASA Astrophysics Data System (ADS)

    Guan, Tong; Lin, Chaojing; Yang, Chongli; Shi, Youguo; Ren, Cong; Li, Yongqing; Weng, Hongming; Dai, Xi; Fang, Zhong; Yan, Shishen; Xiong, Peng

    2015-08-01

    High quality HgCr2 Se4 single crystals have been investigated by magnetization, electron transport, and Andreev reflection spectroscopy. In the ferromagnetic ground state, the saturation magnetic moment of each unit cell corresponds to an integer number of electron spins (3 μB/Cr3 + ), and the Hall effect measurements suggest n -type charge carriers. Spin polarizations as high as 97% were obtained from fits of the differential conductance spectra of HgCr2 Se4 /Pb junctions with the modified Blonder-Tinkham-Klapwijk theory. The temperature and bias-voltage dependencies of the subgap conductance are consistent with recent theoretical calculations based on spin active scatterings at a superconductor-half-metal interface. Our results suggest that n -HgCr2Se4 is a half-metal, in agreement with theoretical calculations that also predict undoped HgCr2 Se4 is a magnetic Weyl semimetal.

  7. A precious-metal free micro fuel cell accumulator

    NASA Astrophysics Data System (ADS)

    Bretthauer, C.; Müller, C.; Reinecke, H.

    2011-05-01

    In recent years, integrated fuel cell (FC) type primary and secondary batteries attracted a great deal of attention as integrated on-chip power sources due to their high theoretical power densities. Unfortunately, the costs of these devices have been rather high. This is partially due to the involved clean-room processes, but also due to the fact that these devices generally rely on expensive precious-metals such as Pd and Pt. Therefore we developed a novel integrated FC type accumulator that is based on non-precious-metals only. The key component of the presented accumulator is its alkaline polymer electrolyte membrane that allows not only the usage of a low-cost AB5 type hydrogen storage electrode, but also the usage of La0.6Ca0.4CoO3 as a precious-metal free bifunctional catalyst for the air-breathing electrode. Additionally the presented design requires only comparatively few cleanroom processes which further reduces the overall production costs. Although abdicating precious-metals, the presented accumulator shows an open circuit voltage of 0.81 V and a maximum power density of 0.66 mW cm-2 which is comparable or even superior to former precious-metal based cells.

  8. The metal abundance of circumnuclear star-forming regions in early-type spirals. Spectrophotometric observations

    NASA Astrophysics Data System (ADS)

    Díaz, Ángeles I.; Terlevich, Elena; Castellanos, Marcelo; Hägele, Guillermo F.

    2007-11-01

    We have obtained long-slit observations in the optical and near-infrared of 12 circumnuclear HII regions [circumnuclear star-forming regions (CNSFR)] in the early-type spiral galaxies NGC2903, 3351 and 3504 with the aim of deriving their chemical abundances. Only for one of the regions, the [SIII] λ6312Å was detected providing, together with the nebular [SIII] lines at λλ9069, 9532Å, a value of the electron temperature of . A semi-empirical method for the derivation of abundances in the high metallicity regime is presented. We obtain abundances which are comparable to those found in high metallicity disc HII regions from direct measurements of electron temperatures and consistent with solar values within the errors. The region with the highest oxygen abundance is R3+R4 in NGC3504, 12 + log(O/H) = 8.85, about 1.5 solar if the solar oxygen abundance is set at the value derived by Asplund, Grevesse & Sauval, 12 + log(O/H)solar = 8.66 +/- 0.05. Region R7 in NGC3351 has the lowest oxygen abundance of the sample, about 0.6 times solar. In all the observed CNSFR the O/H abundance is dominated by the O+/H+ contribution, as is also the case for high metallicity disc HII regions. For our observed regions, however, also the S+/S2+ ratio is larger than one, contrary to what is found in high metallicity disc HII regions for which, in general, the sulphur abundances are dominated by S2+/H+. The derived N/O ratios are in average larger than those found in high metallicity disc HII regions and they do not seem to follow the trend of N/O versus O/H which marks the secondary behaviour of nitrogen. On the other hand, the S/O ratios span a very narrow range between 0.6 and 0.8 of the solar value. As compared to high metallicity disc HII regions, CNSFR show values of the O23 and the N2 parameters whose distributions are shifted to lower and higher values, respectively, hence, even though their derived oxygen and sulphur abundances are similar, higher values would in principle be

  9. On the Design of High Efficiency Thermoelectric Type I Clathrates through Transition Metal Doping

    SciTech Connect

    Shi, Xun; Yang, Jiong; Yang, Jihui; Salvador, James R.; Bai, Shengqiang; Zhang, Weiqing; Chen, Lidong; Wong-Ng, W.; Wang, Hsin

    2010-01-01

    The lack of high efficiency thermoelectric materials hinders their deployment into wide ranging applications such as power generation from waste heat and solid state heating and cooling, which could lead to significant energy savings. Type I clathrates have recently been identified as prospective thermoelectric materials for power generation purposes due to their very low lattice thermal conductivity values. The maximum thermoelectric figure of merit of almost all type I clathrates is, however, less than 1; and occurs at, or above, 1000 K making them unfavorable especially for intermediate temperature applications. In this report, we demonstrate that transition metal doping introduces charge distortion and lattice defects into these materials which increases the ionized impurity scattering of carriers and point defect scattering of lattice phonons, respectively; leading to an enhanced power factor, reduced lattice thermal conductivity, and therefore improved thermoelectric figure of merit. Most importantly, the band gap of these materials can be tuned between 0.1 eV and 0.5 eV by adjusting the transition metal content, making it possible to design type I clathrates with excellent thermoelectric properties between 500 K and 1000 K.

  10. Metal removal and associated binding fraction transformation in contaminated river sediment washed by different types of agents

    PubMed Central

    Wang, Hong; Liu, Tongzhou; Feng, Shuai; Zhang, Weihua

    2017-01-01

    In ex-situ washing, HCl, EDTA and H2O2 solutions can effectively extract heavy metals in river sediment. Nevertheless they often target different sediment components, possibly transforming metal species into more bioavailable and hence toxic ones. This study, in batch settings, investigated the influences of different types of washing agents (i.e. HCl, EDTA and H2O2) on metal (i.e. Cu and Zn) removal from contaminated river sediment, destroy or dissolution of sediment components, and transformation of metal fractions during chemical washing treatment. Additionally, bioavailability of these metals left in the washed sediment was assessed. Results showed that HCl obtained the highest Cu and Zn removal through destroying the reducible, oxidizable and residual sediment components. Meanwhile, it transformed metal fractions to acid extractable one, resulting in an increase in metal bioavailability. Thus, the feasibility of washing with HCl for sediment remediation shall be reconsidered due to the caused high metal bioavailability. EDTA was capable of removing metals via direct complexation of labile metal species and indirect dissolution of reducible and oxidizable sediment components, where the transformation of corresponding metal binding fraction may occur. H2O2 obtained the lowest total Cu and Zn removal, but it preferentially removed the oxidizable metal species by oxidizing sulfides in the sediment. The bioavailable levels of Cu and Zn in the sediment washed by EDTA or H2O2 seemed not increase. To maintain a good balance between labile metal species removal and avoiding increase of metal bioavailability, EDTA and H2O2 are promising additives for metal removal by sediment washing. PMID:28350832

  11. Metal removal and associated binding fraction transformation in contaminated river sediment washed by different types of agents.

    PubMed

    Wang, Hong; Liu, Tongzhou; Feng, Shuai; Zhang, Weihua

    2017-01-01

    In ex-situ washing, HCl, EDTA and H2O2 solutions can effectively extract heavy metals in river sediment. Nevertheless they often target different sediment components, possibly transforming metal species into more bioavailable and hence toxic ones. This study, in batch settings, investigated the influences of different types of washing agents (i.e. HCl, EDTA and H2O2) on metal (i.e. Cu and Zn) removal from contaminated river sediment, destroy or dissolution of sediment components, and transformation of metal fractions during chemical washing treatment. Additionally, bioavailability of these metals left in the washed sediment was assessed. Results showed that HCl obtained the highest Cu and Zn removal through destroying the reducible, oxidizable and residual sediment components. Meanwhile, it transformed metal fractions to acid extractable one, resulting in an increase in metal bioavailability. Thus, the feasibility of washing with HCl for sediment remediation shall be reconsidered due to the caused high metal bioavailability. EDTA was capable of removing metals via direct complexation of labile metal species and indirect dissolution of reducible and oxidizable sediment components, where the transformation of corresponding metal binding fraction may occur. H2O2 obtained the lowest total Cu and Zn removal, but it preferentially removed the oxidizable metal species by oxidizing sulfides in the sediment. The bioavailable levels of Cu and Zn in the sediment washed by EDTA or H2O2 seemed not increase. To maintain a good balance between labile metal species removal and avoiding increase of metal bioavailability, EDTA and H2O2 are promising additives for metal removal by sediment washing.

  12. Levels of heavy metals and their binding protein metallothionein in type 2 diabetics with kidney disease.

    PubMed

    Raudenska, Martina; Dvorakova, Veronika; Pacal, Lukas; Chalasova, Katarina; Kratochvilova, Monika; Gumulec, Jaromir; Ruttkay-Nedecky, Branislav; Zitka, Ondrej; Kankova, Katerina; Adam, Vojtech; Masarik, Michal

    2017-01-06

    Hyperglycemia, a major metabolic disturbance present in diabetes, promotes oxidative stress. Activation of antioxidant defense is an important mechanism to prevent cell damage. Levels of heavy metals and their binding proteins can contribute to oxidative stress. Antiradical capacity and levels of metallothionein (MT), metals (zinc and copper), and selected antioxidants (bilirubin, cysteine, and glutathione) were determined in 70 type 2 diabetes mellitus (T2DM) subjects and 80 healthy subjects of Caucasian origin. Single nucleotide polymorphism (rs28366003) in MT gene was detected. Antiradical capacity, conjugated bilirubin, and copper were significantly increased in diabetics, whereas MT and glutathione were decreased. Genotype AA of rs28366003 was associated with higher zinc levels in the diabetic group. The studied parameters were not influenced by renal function. This is the first study comprehensively investigating differences in MT and metals relevant to oxidative stress in T2DM. Ascertained differences indicate increased oxidative stress in T2DM accompanied by abnormalities in non-enzymatic antioxidant defense systems.

  13. Types and concentrations of metal ions affect local structure and dynamics of RNA

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Xiao, Yi

    2016-10-01

    The roles that metal ions play in the structure and dynamics of RNA molecules are long-standing problems that have been studied extensively but are still not well understood. Here we show that metal ions have distributions around RNA molecules that strongly depend on the types and concentrations of the metal ions and also the electrostatic surface of the molecule. In particular, the ion distributions may not balance all the local electronegativity of the molecule. These ion distributions do not only greatly affect local structures but also lead to different local dynamics of RNA. We studied the effects of different ion solutions on the structure and dynamics of RNA by taking the pre Q1 riboswitch aptamer domain as an illustrative example and using molecular dynamics simulations. Since the local structures and dynamics of RNAs are important to their functions, our results also indicate that the selection of proper ion conditions is necessary to model them correctly, in contrast to the use of diverse ion solutions in current molecular dynamics simulations.

  14. Effect of metal type and surface treatment on shear bond strength of resin cement (in vitro study)

    PubMed Central

    Al-Helou, Hiba; Swed, Eyad

    2016-01-01

    Background: Resin-bonded fixed partial dentures appeared to prevent the excessive preparation of dental tissue. Investigation of surface treatments to improve the bond of resin cements to metals may contribute to the longevity of these restorations. Due to the potential lack of ideal preparation form, the type of alloy and its surface pretreatment may have clinically relevant correlations with the retentive strength of castings to minimally retentive preparations. Aim: The aim of this search is to study the bonding resin cement strength to different types of the metal alloy due to the surface treatment. Purpose: Evaluate the effects of two different surface treatments on shear bond strength (SBS) between a palladium-silver alloy (Pb-Ag) and commercially pure titanium (CP Ti) cast alloy with resin luting cements. Materials and Methods: A total of 120 cylinders having 5 mm in diameter and 4 mm in height were divided into two different main groups of metal type: 60 cylinders cast from CP Ti Grade I (Tritan - Reintitan - Germany-Dentaurum) as a base metal and 60 cylinders cast from Pb-Ag (Status-Yamakin, Japan) as a noble metal. 30 cylinders from each type were embedded in acrylic resin, and the rest were left without embedded in acrylic resin. All of the cylinders were smoothed with silicon carbide papers and sandblasting with 50-μm aluminum oxide. Specimens of each metal type were divided into two subgroups, which received one of the following luting techniques: (1) Multilink (Ivoclar Vivadent), (2) Multilink (Ivoclar Vivadent) plus metal zirconia primer (MZP). Every two cylinders from the same metal type and surface treatment were bonded to each other. All specimens were stored in distilled water at 37°C for 24 h and then thermal cycled (500 cycles, 5–55°C). After thermal cycling, the specimens were stored in 37°C distilled water for an additional 24 h before being tested in shear strength. Data (MPa) were analyzed using T-s tests to study the significance of

  15. The direct and indirect effects of watershed land use and soil type on stream water metal concentrations

    NASA Astrophysics Data System (ADS)

    Taka, M.; Aalto, J.; Virkanen, J.; Luoto, M.

    2016-10-01

    Identifying the factors controlling stream water pollutants is challenged by the diversity of potential sources, pathways, and processes. This study tests the effects of watershed characteristics on stream water metal concentrations across environmental gradients. By using an extensive data set of 83 watersheds in southern Finland and structural equation modeling (SEM), the direct and indirect effects of land use and soil type on metal concentrations were explored. Both land use and soil type resulted in statistically significant direct effects on metals; for example, land use was found to control dissolved metal concentrations, whereas soil type had the strongest links for total metal concentrations. The consideration of indirect correlation further strengthened the effects of soil type up to 50%, thus suggesting the dominant role of soil across land use intensities. Moreover, the results indicate that modified landscapes mediate the effect of natural soil processes in controlling stream metal concentrations. This work highlights the benefits of structural equation model framework, as the underlying paths for water quality are more likely to be identified, compared to traditional regression methods. Thus, the implementation of SEM on water quality studies is highly encouraged.

  16. Relationship of surface changes to metal leaching from tungsten composite shot exposed to three different soil types.

    PubMed

    Felt, Deborah; Larson, Steven; Griggs, Chris; Nestler, Catherine; Wynter, Michelle

    2011-05-01

    Physical changes that occur on the surface of fired shots due to firing and impact with soil may increase the dissolution of muniton metals. Increased metal dissolution could potentially increase metal transport and leaching, affecting metal concentrations in surface and groundwater. This research describes the relationship between the surface changes on fired tungsten-nickel-iron (94% W:2% Ni:4% Fe) composite shots and metals leaching from those shots. Tungsten composite shot was fired into, and aged in, three soil types (Silty Sand, Sandy Clay, and Silt) in mesoscale rainfall lysimeters to simulate live-fire conditions and subsequent interactions between the metals of the composite and soil. Leachate, runoff, and soil samples were collected from the lysimeters and analyzed for metal content. The shots were analyzed using scanning electron microscopy (SEM) to evaluate surface changes. SEM results indicated that a soil's particle size distribution initially affected the amount of metal that was sheared from the surface of the fired W-composite shots. Shearing was greatest in soils with larger soil particles (sand and gravel); shearing was least in soils composed of small soil particles (fines). Increased metallic shearing from the shot's surface was associated with increased W dissolution, compared to controls, following a simulated 1 year soil aging.

  17. Streptococcus agalactiae from pregnant women: antibiotic and heavy-metal resistance mechanisms and molecular typing.

    PubMed

    Rojo-Bezares, B; Azcona-Gutiérrez, J M; Martin, C; Jareño, M S; Torres, C; Sáenz, Y

    2016-11-01

    We investigated the antibiotic and heavy-metal resistance mechanisms, virulence genes and clonal relationships of macrolide- and/or lincosamide-resistant (M+/-LR) Streptococcus agalactiae (group B Streptococcus, GBS) isolates from pregnant women in La Rioja in Northern Spain, a region with a significant immigrant population. In total 375 GBS isolates were recovered during 2011. About three-quarters of isolates were from European nationals and the remainder distributed among 23 other nationalities. Seventy-five (20%) were classified as M+/-LR strains and 28 (37%) of these were resistant to ⩾3 classes of antibiotics. Capsular serotypes III (29·3%), V (21·3%) and II (12%) were the most frequent. A wide variety of antibiotic resistance genes were detected in M+/-LR strains; notably, 5·3% harboured the lsa(C) gene associated with cross-resistance, and tet(W) was identified in a single strain. We report, for the first time, the detection of cadmium and copper resistance encoded by tcrB + cadA + cadC genes in 20 M+/-LR strains, which raises the possibility of co-selection of antibiotic and heavy-metal resistance disseminated through mobile genetic elements. The M+/-LR strains were highly diverse by DNA macrorestriction profiles (65 patterns) and 16 multilocus sequence types (STs) distributed among six clonal complexes; the most frequent were ST1, ST19, and ST12, and two strains were novel (ST586 and ST601). In conclusion, a wide diversity of genetic lineages of macrolide, lincosamide and heavy-metal- resistant GBS strains was observed in an ethnically diverse maternal population.

  18. 18-Electron Resonance Structures in the BCC Transition Metals and Their CsCl-type Derivatives.

    PubMed

    Vinokur, Anastasiya I; Fredrickson, Daniel C

    2017-03-06

    Bonding in elemental metals and simple alloys has long been thought of as involving intense delocalization, with little connection to the localized bonds of covalent systems. In this Article, we show that the bonding in body-centered cubic (bcc) structures of the group 6 transition metals can in fact be represented, via the concepts of the 18-n rule and isolobal bonding, in terms of two balanced resonance structures. We begin with a reversed approximation Molecular Orbital (raMO) analysis of elemental Mo in its bcc structure. The raMO analysis indicates that, despite the low electron count (six valence electrons per Mo atom), nine electron pairs can be associated with any given Mo atom, corresponding to a filled 18-electron configuration. Six of these electron pairs take part in isolobal bonds along the second-nearest neighbor contacts, with the remaining three (based on the t2g d orbitals) interacting almost exclusively with first-nearest neighbors. In this way, each primitive cubic network defined by the second-nearest neighbor contacts comprises an 18-n electron system with n = 6, which essentially describes the full electronic structure of the phase. Of course, either of the two interpenetrating primitive cubic frameworks of the bcc structure can act as a basis for this discussion, leading us to write two resonance structures with equal weights for bcc-Mo. The electronic structures of CsCl-type variants with the same electron count can then be interpreted in terms of changing the relative weights of these two resonance structures, as is qualitatively confirmed with raMO analysis. This combination of raMO analysis with the resonance concept offers an avenue to extend the 18-n rule into other transition metal-rich structures.

  19. Stability of alkali-metal hydrides: effects of n-type doping

    NASA Astrophysics Data System (ADS)

    Olea Amezcua, Monica Araceli; de La Peña Seaman, Omar; Rivas Silva, Juan Francisco; Heid, Rolf; Bohnen, Klaus-Peter

    Metal hydrides could be considered ideal solid-state hydrogen storage systems, they have light weight and high hydrogen volumetric densities, but the hydrogen desorption process requires excessively high temperatures due to their high stability. Efforts have been performed to improve their dehydrogenation properties, based on the introduction of defects, impurities and doping. We present a systematic study of the n-type (electronic) doping effects on the stability of two alkali-metal hydrides: Na1-xMgxH and Li1-xBexH. These systems have been studied within the framework of density functional perturbation theory, using a mixed-basis pseudopotential method and the self-consistent version of the virtual crystal approximation to model the doping. The full-phonon dispersions are analyzed for several doping content, paying special attention to the crystal stability. It is found a doping content threshold for each system, where they are close to dynamical instabilities, which are related to charge redistribution in interstitial zones. Applying the quasiharmonic approximation, the vibrational free energy, the linear thermal expansion and heat capacities are obtained for both hydrides systems and are analyzed as a function of the doping content. This work is partially supported by the VIEP-BUAP 2016 and CONACYT-México (No.221807) projects.

  20. ON THE DEPENDENCE OF TYPE Ia SNe LUMINOSITIES ON THE METALLICITY OF THEIR HOST GALAXIES

    SciTech Connect

    Moreno-Raya, Manuel E.; Mollá, Mercedes; López-Sánchez, Ángel R.; Galbany, Lluís; Vílchez, José Manuel; Rosell, Aurelio Carnero; Domínguez, Inmaculada

    2016-02-10

    The metallicity of the progenitor system producing a type Ia supernova (SN Ia) could play a role in its maximum luminosity, as suggested by theoretical predictions. We present an observational study to investigate if such a relationship exists. Using the 4.2 m William Herschel Telescope (WHT) we have obtained intermediate-resolution spectroscopy data of a sample of 28 local galaxies hosting SNe Ia, for which distances have been derived using methods independent of those based on SN Ia parameters. From the emission lines observed in their optical spectra, we derived the gas-phase oxygen abundance in the region where each SN Ia exploded. Our data show a trend, with an 80% of chance not being due to random fluctuation, between SNe Ia absolute magnitudes and the oxygen abundances of the host galaxies, in the sense that luminosities tend to be higher for galaxies with lower metallicities. This result seems likely to be in agreement with both the theoretically expected behavior and with other observational results. This dependence M{sub B}–Z might induce systematic errors when it is not considered when deriving SNe Ia luminosities and then using them to derive cosmological distances.

  1. On the Dependence of Type Ia SNe Luminosities on the Metallicity of Their Host Galaxies

    NASA Astrophysics Data System (ADS)

    Moreno-Raya, Manuel E.; Mollá, Mercedes; López-Sánchez, Ángel R.; Galbany, Lluís; Vílchez, José Manuel; Carnero Rosell, Aurelio; Domínguez, Inmaculada

    2016-02-01

    The metallicity of the progenitor system producing a type Ia supernova (SN Ia) could play a role in its maximum luminosity, as suggested by theoretical predictions. We present an observational study to investigate if such a relationship exists. Using the 4.2 m William Herschel Telescope (WHT) we have obtained intermediate-resolution spectroscopy data of a sample of 28 local galaxies hosting SNe Ia, for which distances have been derived using methods independent of those based on SN Ia parameters. From the emission lines observed in their optical spectra, we derived the gas-phase oxygen abundance in the region where each SN Ia exploded. Our data show a trend, with an 80% of chance not being due to random fluctuation, between SNe Ia absolute magnitudes and the oxygen abundances of the host galaxies, in the sense that luminosities tend to be higher for galaxies with lower metallicities. This result seems likely to be in agreement with both the theoretically expected behavior and with other observational results. This dependence MB-Z might induce systematic errors when it is not considered when deriving SNe Ia luminosities and then using them to derive cosmological distances.

  2. Role of thin n-type metal-oxide interlayers in inverted organic solar cells.

    PubMed

    Gadisa, Abay; Liu, Yingchi; Samulski, Edward T; Lopez, Rene

    2012-08-01

    We have investigated the photovoltaic properties of inverted solar cells comprising a bulk heterojunction film of poly(3-hexylthiophene) and phenyl-C(61)-butyric acid methyl ester, sandwiched between an indium-tin-oxide/Al-doped zinc oxide (ZnO-Al) front, and tungsten oxide/aluminum back electrodes. The inverted solar cells convert photons to electrons at an external quantum efficiency (EQE) exceeding 70%. This is a 10-15% increase over EQEs of conventional solar cells. The increase in EQE is not fully explained by the difference in the optical transparency of electrodes, interference effects due to an optical spacer effect of the metal-oxide electrode buffer layers, or variation in charge generation profile. We propose that a large additional splitting of excited states at the ZnO-Al/polymer interface leads to the considerably large photocurrent yield in inverted cells. Our finding provides new insights into the benefits of n-type metal-oxide interlayers in bulk heterojunction solar cells, namely the splitting of excited states and conduction of free electrons simultaneously.

  3. Metal separation from mixed types of batteries using selective precipitation and liquid-liquid extraction techniques.

    PubMed

    Provazi, Kellie; Campos, Beatriz Amaral; Espinosa, Denise Crocce Romano; Tenório, Jorge Alberto Soares

    2011-01-01

    The purpose of this paper is to study metal separation from a sample composed of a mixture of the main types of spent household batteries, using a hydrometallurgical route, comparing selective precipitation and liquid-liquid extraction separation techniques. The preparation of the solution consisted of: grinding the waste of mixed batteries, reduction and volatile metals elimination using electric furnace and acid leaching. From this solution two different routes were studied: selective precipitation with sodium hydroxide and liquid-liquid extraction using Cyanex 272 [bis(2,4,4-trimethylpentyl) phosphoric acid] as extracting agent. The best results were obtained from liquid-liquid extraction in which Zn had a 99% extraction rate at pH 2.5. More than 95% Fe was extracted at pH 7.0, the same pH at which more than 90% Ce was extracted. About 88% Mn, Cr and Co was extracted at this pH. At pH 3.0, more than 85% Ni was extracted, and at pH 3.5 more than 80% of Cd and La was extracted.

  4. Grain Boundary Penetration of Various Types of Ni Layer by Molten Metals

    NASA Astrophysics Data System (ADS)

    Yang, S.; Chang, C. Y.; Zhu, Z. X.; Lin, Y. F.; Kao, C. R.

    2017-02-01

    The grain boundary penetration of three types of Ni layer, Ni foil, electroplated Ni, and electroless Ni, by molten Pb and 95Pb5Sn (wt.%) is investigated. The average grain sizes of Ni foil and electroplated Ni are 10 μm and 1 μm, respectively, while the electroless Ni is amorphous. The purpose of using two molten metals is to study the effect of intermetallic formation on grain boundary penetration. Molten Pb was able to penetrate or disintegrate all three types of Ni, including amorphous Ni, which does not contain any grain boundaries. On the other hand, the addition of merely 5 wt.% Sn into molten Pb was able to slow the penetration down substantially for all three types of Ni layer, with the greatest suppression found in electroless Ni where a grain boundary penetration event did not take place. The mechanism for the Sn effect is due to the formation of a protective Ni3Sn4 intermetallic compound at the interface acting as a barrier against grain boundary penetration.

  5. Size-resolved trace metal characterization of aerosols emitted by four important source types in Switzerland

    NASA Astrophysics Data System (ADS)

    Buerki, Peter R.; Gaelli, Brigitte C.; Nyffeler, Urs P.

    In central Switzerland five types of emission sources are mainly responsible for airborne trace metals: traffic, industrial plants burning heavy oil, resuspension of soil particles, residential heatings and refuse incineration plants. The particulate emissions of each of these source types except refuse incineration were sampled using Berner impactors and the mass and elemental size distributions of Cd, Cu, Mn, Pb, Zn, As and Na determined. Cd, Na and Zn are not characteristic for any of these source types. As and Cu, occurring in the fine particle fractions are characteristic for heavy oil combustion, Mn for soil dust and sometimes for heavy and fuel oil combustion and Pb for traffic aerosols. The mass size distributions of aerosols originating from erosion and abrasion processes show a maximum mass fraction in the coarse particle range larger than about 1 μm aerodynamic equivalent diameters (A.E.D.). Aerosols originating from combustion processes show a second maximum mass fraction in the fine particle range below about 0.5μm A.E.D. Scanning electron microscopy combined with an EDS analyzer was used for the morphological characterization of emission and ambient aerosols.

  6. Site-selective synthesis of Janus-type metal-organic framework composites.

    PubMed

    Yadnum, Sudarat; Roche, Jérome; Lebraud, Eric; Négrier, Philippe; Garrigue, Patrick; Bradshaw, Darren; Warakulwit, Chompunuch; Limtrakul, Jumras; Kuhn, Alexander

    2014-04-07

    Herein, bipolar electrochemistry is applied in a straightforward way to the site-selective in situ synthesis of metal-organic framework (MOF) structures, which have attracted tremendous interest in recent years because of their significant application potential, ranging from sensing to gas storage and catalysis. The novelty of the presented work is that the deposit can be intentionally confined to a defined area of a substrate without using masks or templates. The intrinsic site-selectivity of bipolar electrochemistry makes it a method of choice to generate, in a highly controlled way, hybrid particles that may have different functionalities combined on the same particle. The wireless nature of electrodeposition allows the potential for mass production of such Janus-type objects.

  7. Quality assurance: recommended guidelines for safe heating by capacitive-type heating technique to treat patients with metallic implants.

    PubMed

    Kato, Hirokazu; Kondo, Motoharu; Imada, Hajime; Kuroda, Masahiro; Kamimura, Yoshitsugu; Saito, Kazuyuki; Kuroda, Kagayaki; Ito, Koichi; Takahashi, Hideaki; Matsuki, Hidetoshi

    2013-05-01

    This article is a redissemination of the previous Japanese Quality Assurance Guide guidelines. Specific absorption rate and temperature distribution were investigated with respect to various aspects including metallic implant size and shape, insertion site, insertion direction, blood flow and heating power, and simulated results were compared with adverse reactions of patients treated by radio frequency capacitive-type heating. Recommended guidelines for safe heating methods for patients with metallic implants are presented based on our findings.

  8. The End of Amnesia: Measuring the Metallicities of Type Ia SN Progenitors with Manganese Lines in Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Badenes, Carles; Bravo, Eduardo; Hughes, John P.

    2009-05-01

    The Mn to Cr mass ratio in supernova ejecta has recently been proposed as a tracer of Type Ia SN progenitor metallicity. We review the advantages and problems of this observable quantity, and discuss them in the framework of the Tycho Supernova Remnant. The fluxes of the Mn and Cr Kα lines in the X-ray spectra of Tycho observed by the Suzaku satellite suggests a progenitors of supersolar metallicity.

  9. Pyrometallurgical Extraction of Valuable Elements in Ni-Metal Hydride Battery Electrode Materials

    NASA Astrophysics Data System (ADS)

    Jiang, Yin-ju; Deng, Yong-chun; Bu, Wen-gang

    2015-10-01

    Gas selective reduction-oxidation (redox) and melting separation were consecutively applied to electrode materials of AB5-type Ni-metal hydride batteries leading to the production of a Ni-Co alloy and slag enriched with rare earth oxides (REO). In the selective redox process, electrode materials were treated with H2/H2O at 1073 K and 1173 K (800 °C and 900 °C). Active elements such as REs, Al, and Mn were oxidized whereas relatively inert elements such as Ni and Co were transformed into their elemental states in the treated materials. SiO2 and Al2O3 powders were added into the treated materials as fluxes which were then melted at 1823 K (1550 °C) to yield a Ni-Co alloy and a REO-SiO2-Al2O3-MnO slag. The high-purity Ni-Co alloy produced can be used as a raw material for AB5-type hydrogen-storage alloy. The REO content in slag was very high, i.e., 48.51 pct, therefore it can be used to recycle rare earth oxides.

  10. Two-dimensional ferromagnet/semiconductor transition metal dichalcogenide contacts: p-type Schottky barrier and spin-injection control

    NASA Astrophysics Data System (ADS)

    Gan, Li-Yong; Zhang, Qingyun; Cheng, Yingchun; Schwingenschlögl, Udo

    2013-12-01

    We study the ferromagnet/semiconductor contacts formed by transition metal dichalcogenide monolayers, focusing on semiconducting MoS2 and WS2 and ferromagnetic VS2. We investigate the degree of p-type doping and demonstrate tuning of the Schottky barrier height by vertical compressive pressure. An analytical model is presented for the barrier heights that accurately describes the numerical findings and is expected to be of general validity for all transition metal dichalcogenide metal/semiconductor contacts. Furthermore, magnetic proximity effects induce a 100% spin polarization at the Fermi level in the semiconductor where the spin splitting increases up to 0.70 eV for increasing pressure.

  11. Respiration of metal (hydr)oxides by Shewanella and Geobacter: a key role for multihaem c-type cytochromes

    SciTech Connect

    Shi, Liang; Squier, Thomas C.; Zachara, John M.; Fredrickson, Jim K.

    2007-07-01

    Dissimilatory reduction of metal (e.g. Fe, Mn) (hydr)oxides represents a challenge for microorganisms, as their cell envelopes are impermeable to metal (hydr)oxides that are poorly soluble in water. To overcome this physical barrier, the Gram-negative bacteria Shewanella oneidensis MR-1 and Geobactersulfurreducens have developed electron transfer (ET) strategies that require multihaem c-type cytochromes (c-Cyts). In S. oneidensis MR-1, multihaem c-Cyts CymA and MtrA are believed to transfer electrons from the inner membrane quinone/quinol pool through the periplasm to the outer membrane. The type II secretion system of S. oneidensis MR-1 has been implicated in the reduction of metal (hydr)oxides, most likely by translocating decahaem c-Cyts MtrC and OmcA across outer membrane to the surface of bacterial cells where they form a protein complex. The extracellular MtrC and OmcA can directly reduce solid metal (hydr)oxides. Likewise, outer membrane multihaem c-Cyts OmcE and OmcS of G. sulfurreducens are suggested to transfer electrons from outer membrane to type IV pili that are hypothesized to relay the electrons to solid metal (hydr)oxides. Thus, multihaem c-Cyts play critical roles in S. oneidensis MR-1-and G. sulfurreducens-mediated dissimilatory reduction of solid metal (hydr)oxides by facilitating ET across the bacterial cell envelope.

  12. Respiration of metal (hydr)oxides by Shewanella and Geobacter: a key role for multihaem c-type cytochromes.

    PubMed

    Shi, Liang; Squier, Thomas C; Zachara, John M; Fredrickson, James K

    2007-07-01

    Dissimilatory reduction of metal (e.g. Fe, Mn) (hydr)oxides represents a challenge for microorganisms, as their cell envelopes are impermeable to metal (hydr)oxides that are poorly soluble in water. To overcome this physical barrier, the Gram-negative bacteria Shewanella oneidensis MR-1 and Geobacter sulfurreducens have developed electron transfer (ET) strategies that require multihaem c-type cytochromes (c-Cyts). In S. oneidensis MR-1, multihaem c-Cyts CymA and MtrA are believed to transfer electrons from the inner membrane quinone/quinol pool through the periplasm to the outer membrane. The type II secretion system of S. oneidensis MR-1 has been implicated in the reduction of metal (hydr)oxides, most likely by translocating decahaem c-Cyts MtrC and OmcA across outer membrane to the surface of bacterial cells where they form a protein complex. The extracellular MtrC and OmcA can directly reduce solid metal (hydr)oxides. Likewise, outer membrane multihaem c-Cyts OmcE and OmcS of G. sulfurreducens are suggested to transfer electrons from outer membrane to type IV pili that are hypothesized to relay the electrons to solid metal (hydr)oxides. Thus, multihaem c-Cyts play critical roles in S. oneidensis MR-1- and G. sulfurreducens-mediated dissimilatory reduction of solid metal (hydr)oxides by facilitating ET across the bacterial cell envelope.

  13. Irradiation-induced structural changes in surveillance material of VVER 440-type weld metal

    NASA Astrophysics Data System (ADS)

    Grosse, M.; Denner, V.; Böhmert, J.; Mathon, M.-H.

    2000-01-01

    The irradiation-induced microstructural changes in surveillance materials of the VVER 440-type weld metal Sv-10KhMFT were investigated by small angle neutron scattering (SANS) and anomalous small angle X-ray scattering (SAXS). Due to the high fluence, a strong effect was found in the SANS experiment. No significant effect of the irradiation is detected by SAXS. The reason for this discrepancy is the different scattering contrast of irradiation-induced defects for neutrons and X-rays. An analysis of the SAXS shows that the scattering intensity is mainly caused by vanadium-containing (VC) precipitates and grain boundaries. Both types of scattering defects are hardly changed by irradiation. Neutron irradiation rather produces additional scattering defects of a few nanometers in size. Assuming these defects are clusters containing copper and other foreign atoms with a composition according to results of atom probe field ion microscopy (APFIM) investigations, both the high SANS and the low SAXS effect can be explained.

  14. Closed loop control of a cylindrical tube type Ionic Polymer Metal Composite (IPMC)

    NASA Astrophysics Data System (ADS)

    Mead, Benjamin T.

    The goal of this research is to provide a framework for the integration of tube type, cylindrical Ionic Polymer Metal-Composite (IPMC) into conventional devices. IPMCs are one of the most widely used types of electro-active polymer actuator, due to their low electric driving potential and large deformation range. For this research a tube type IPMC was investigated. This IPMC has a circular cross section with four separate electrodes on its surface and a hole through the middle. The four electrodes allow for biaxial bending and accurate control of the tip location. One of the main advantages of using this type of IPMC is the ability to embed a specific tool and accurately control the tool tip location using the large deflection range of the IPMC. This ability has widespread applications including in the biomedical field for use in active catheter procedures. First, this relatively new type of IPMC is investigated and characterized. The processes and materials used are described and the functional design is explored. Before the modeling process beings the basic functions of the IPMC are investigated. To this end force and displacement experiments are performed to describe the activation of the tube type IPMC. This data will be used later to verify and calibrate the mathematical simulations. Second, a three dimensional multi-physics finite element model is developed using COMSOL 4.3a. This model will automatically couple three physics packages and provide a description of the fluid interactions within the tube type IPMC. This model is then compared against the experimental displacement results to calibrate the simulation. Using this simulation design parameters are declared including, overall diameter, and tool hole size. The performance of the IPMC is then simulated while varying these parameters. Third, an electro-mechanical model of the IPMC is developed. This macroscopic model is used to relate the input voltage to an associated tip deflection. Several model types

  15. The effect of sprue design and alloy type on the fit of three-unit metal/ceramic bridges.

    PubMed

    Johnson, A

    1995-12-01

    This study was designed to compare the effect of three sprue designs and three types of metal alloy/ceramic on the accuracy of fit of three unit bridges. A sprue design which has straight sprues attached directly to the pattern but does not have a button of excess metal connecting the sprues together after casting, produced the best marginal accuracy, irrespective of the alloy type used. Of the three alloys used (gold, palladium and nickel/chromium based alloys) the gold alloy produced better fitting bridges with each sprue design used.

  16. Distribution and risk assessment of metals and arsenic contamination in man-made ditch sediments with different land use types.

    PubMed

    Nsenga Kumwimba, Mathieu; Zhu, Bo; Wang, Tao; Muyembe, Diana Kavidia

    2016-12-01

    Ditches are subjected to a large input of nutrients, trace metals, and arsenic and the enhancement of sedimentation due to human activities. However, the influence of different types of land uses on the distribution and associated environmental risk of metals and arsenic in the Red purple Sichuan Basin remains largely unclear, which is needed for water management. This study was carried out to characterize metal/metalloid status in ditch sediments from different land uses. A total of 68 surface sediment samples (0-5 cm) were collected from open ditches distributed in different land use types, i.e., cultivated ditches (CD), barren land ditches (BLD), roadside ditches (RSD), and residential ditches (RD), within the Sichuan Basin. Mean concentrations of Cr, Ni, Cu, Zn, Cd, Pb, and Mn in both RD and RSD were above the soil background values of Sichuan Basin, but Cd in ditch sediments of the basin posed considerable ecological risk to the environment. Overall, metals/metalloid (except Pb) decreased in the following order of RD > RSD > BLD > CD. Of the different land use types in the hilly region, residential and roadside land uses were likely to adverse effects on aquatic life. Multivariate statistical analysis showed that Mn, As, Cu, Ni, Zn, Fe, and Al were mainly influenced by natural weathering (erosion), while Pb might come from heavy vehicular traffic. The degree of contamination (Md), enrichment factor (EF), and the geo-accumulation index (Igeo) showed that Cd causes strong sediment pollution in the basin. Sediment quality guidelines SQG-Q values displayed that metals and arsenic created medium-low potential of adverse biological effects. These results provide baseline information on the metals and arsenic pollution in the Sichuan Basin. Awareness of land use type contributions to metals and arsenic requires that these man-made ditches be considered for their mitigation of pollutants in this region.

  17. Thermoelectric material including a multiple transition metal-doped type I clathrate crystal structure

    DOEpatents

    Yang, Jihui [Lakeshore, CA; Shi, Xun [Troy, MI; Bai, Shengqiang [Shanghai, CN; Zhang, Wenqing [Shanghai, CN; Chen, Lidong [Shanghai, CN; Yang, Jiong [Shanghai, CN

    2012-01-17

    A thermoelectric material includes a multiple transition metal-doped type I clathrate crystal structure having the formula A.sub.8TM.sub.y.sub.1.sup.1TM.sub.y.sub.2.sup.2 . . . TM.sub.y.sub.n.sup.nM.sub.zX.sub.46-y.sub.1.sub.-y.sub.2.sub.- . . . -y.sub.n.sub.-z. In the formula, A is selected from the group consisting of barium, strontium, and europium; X is selected from the group consisting of silicon, germanium, and tin; M is selected from the group consisting of aluminum, gallium, and indium; TM.sup.1, TM.sup.2, and TM.sup.n are independently selected from the group consisting of 3d, 4d, and 5d transition metals; and y.sub.1, y.sub.2, y.sub.n and Z are actual compositions of TM.sup.1, TM.sup.2, TM.sup.n, and M, respectively. The actual compositions are based upon nominal compositions derived from the following equation: z=8q.sub.A-|.DELTA.q.sub.1|y.sub.1-|.DELTA.q.sub.2|y.sub.2- . . . -|.DELTA.q.sub.n|y.sub.n, wherein q.sub.A is a charge state of A, and wherein .DELTA.q.sub.1, .DELTA.q.sub.2, .DELTA.q.sub.n are, respectively, the nominal charge state of the first, second, and n-th TM.

  18. Parameterization of Highly Charged Metal Ions Using the 12-6-4 LJ-Type Nonbonded Model in Explicit Water

    PubMed Central

    2015-01-01

    Highly charged metal ions act as catalytic centers and structural elements in a broad range of chemical complexes. The nonbonded model for metal ions is extensively used in molecular simulations due to its simple form, computational speed, and transferability. We have proposed and parametrized a 12-6-4 LJ (Lennard-Jones)-type nonbonded model for divalent metal ions in previous work, which showed a marked improvement over the 12-6 LJ nonbonded model. In the present study, by treating the experimental hydration free energies and ion–oxygen distances of the first solvation shell as targets for our parametrization, we evaluated 12-6 LJ parameters for 18 M(III) and 6 M(IV) metal ions for three widely used water models (TIP3P, SPC/E, and TIP4PEW). As expected, the interaction energy underestimation of the 12-6 LJ nonbonded model increases dramatically for the highly charged metal ions. We then parametrized the 12-6-4 LJ-type nonbonded model for these metal ions with the three water models. The final parameters reproduced the target values with good accuracy, which is consistent with our previous experience using this potential. Finally, tests were performed on a protein system, and the obtained results validate the transferability of these nonbonded model parameters. PMID:25145273

  19. Parameterization of highly charged metal ions using the 12-6-4 LJ-type nonbonded model in explicit water.

    PubMed

    Li, Pengfei; Song, Lin Frank; Merz, Kenneth M

    2015-01-22

    Highly charged metal ions act as catalytic centers and structural elements in a broad range of chemical complexes. The nonbonded model for metal ions is extensively used in molecular simulations due to its simple form, computational speed, and transferability. We have proposed and parametrized a 12-6-4 LJ (Lennard-Jones)-type nonbonded model for divalent metal ions in previous work, which showed a marked improvement over the 12-6 LJ nonbonded model. In the present study, by treating the experimental hydration free energies and ion-oxygen distances of the first solvation shell as targets for our parametrization, we evaluated 12-6 LJ parameters for 18 M(III) and 6 M(IV) metal ions for three widely used water models (TIP3P, SPC/E, and TIP4PEW). As expected, the interaction energy underestimation of the 12-6 LJ nonbonded model increases dramatically for the highly charged metal ions. We then parametrized the 12-6-4 LJ-type nonbonded model for these metal ions with the three water models. The final parameters reproduced the target values with good accuracy, which is consistent with our previous experience using this potential. Finally, tests were performed on a protein system, and the obtained results validate the transferability of these nonbonded model parameters.

  20. Counter-cation modulation of hydrogen and methane storage in a sodalite-type porous metal-organic framework.

    PubMed

    Gong, Yun-Nan; Meng, Miao; Zhong, Di-Chang; Huang, Yong-Liang; Jiang, Long; Lu, Tong-Bu

    2012-12-21

    A μ(4)-Cl bridged anionic sodalite-type porous metal-organic framework (Et(2)NH(2))(3)[(Cu(4)Cl)(3)(TTCA)(8)]·26DEF was synthesized, in which Et(2)NH(2)(+) can be exchanged by Li(+) cations. The results of gas measurements indicate that Et(2)NH(2)(+) and Li(+) are beneficial for methane and hydrogen storage, respectively.

  1. Biochar soil amendment: Impact of soil types on heavy metal sorption-desorption behaviors and repeated nutrient leaching

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Depending on soil types, properties of chars especially pH and leachable organic/inorganic components can have varying impacts when used as a soil amendment. We have investigated sorption-desorption behaviors of metal contaminant of concern in shooting ranges and urban soils (Cu), nutrient supply (...

  2. Sewage sludge ash to phosphorus fertiliser (II): Influences of ash and granulate type on heavy metal removal.

    PubMed

    Mattenberger, H; Fraissler, G; Jöller, M; Brunner, T; Obernberger, I; Herk, P; Hermann, L

    2010-01-01

    Ashes from monoincineration of sewage sludge suggest themselves as an ideal base for inorganic fertiliser production due to their relatively high phosphorus (P)-content. However, previously they need to be detoxified by reducing their heavy metal content. The core process considered in this paper consists of three steps: mixing of the ashes with suitable chlorine-containing additives, granulation of the mixture and thermochemical treatment in a rotary kiln. Here relevant heavy metal compounds are first transformed into volatile species with the help of the additives and then evaporated from the granules. In this study two chemically different ashes and their mixture were agglomerated to two different granulate types, briquettes and rolled pellets. The resulting six different materials were subjected to thermal treatment at different temperatures. The heavy metals examined were Cu and Zn due to their strong dependence on treatment conditions and their relevance concerning thermal treatment of sewage sludge ashes. Besides, the behaviour of Cl and K was monitored and evaluated. The experiments showed that ash type and temperature are more influential on Cl and heavy metal chemistry than granulate type. Temperature is a primary variable for controlling removal in both cases. Cu removal was less dependent on both ash and granulate type than Zn. The Cl utilization was more effective for Cu than for Zn. Depending on the treatment conditions some K could be retained, whereas always all P remained in the treated material. This satisfies the requirement for complete P recycling.

  3. Tetrahedral Clusters of GaMo 4S 8-Type Compounds: A Metal Bonding Analysis

    NASA Astrophysics Data System (ADS)

    Le Beuze, A.; Loirat, H.; Zerrouki, M. C.; Lissillour, R.

    1995-11-01

    Extended Hückel tight binding calculations have been performed on ligated as well as on ligand-free Mo4 and Mo6 extended frames, in order to analyze the metal-metal bonding within the clusters and particularly the appreciable changes of the metal-metal bond lengths through the M4 tetrahedral units contained in GaM4X8 (M = Mo, Nb, V, Ta; X = S, Se, Te), Mo4S4Y4 (Y = Cl, Br, I). A comparison with the M6 octahedral units of the M Mo6X8 (M = Pb, Ag, La; X = S, Se) series is made. By means of DOS, COOP curves, and overlap populations, results clearly display the strong reorganization of the electronic structure of the bare metal clusters network while the ligand interactions occur, inducing a strong reduction of the strength of the metal-metal bonds. We outline the relationship between the metal-metal bond lengths and various parameters such as the valence electron count (VEC) per cluster and the nature of the ligands. Our results indicate that the two series M4 and M6 differ: M-M bond lengths are unaffected by the VEC in the regular M4 cluster, whereas some M-M bond lengths undergo a significant change when the VEC increases in the distorded M6 clusters. Likewise, it is worthy to note that metal d orbitals have a more significant effect in M4 cluster series. In contrast, the metal-ligand covalency induces similar elongations of metal-metal bonds in the two series.

  4. Microscopic magnetic nature of K2NiF4-type 3d transition metal oxides

    NASA Astrophysics Data System (ADS)

    Sugiyama, J.; Nozaki, H.; Umegaki, I.; Higemoto, W.; Ansaldo, E. J.; Brewer, J. H.; Sakurai, H.; Kao, T.-H.; Yang, H.-D.; Månsson, M.

    2014-12-01

    In order to elucidate the magnetic nature of K2NiF4-type 3d transition metal oxides, we have measured μ+SR spectra for Sr2VO4, LaSrVO4, and Sr2CrO4 using powder samples. ZF- and wTF-μ+SR measurements propose that Sr2VO4 enters into the static antiferromagnetic (AF) order phase below 8 K. In addition, TF-μ+SR measurements evidence that the transition at 105 K is not magnetic but structural and/or electronic in origin. For LaSrVO4, static long-range order has not been observed down to 20 K, while, as T decreases from 145 K, wTF asymmetry starts to decrease below 60 K, suggesting the appearance and evolution of localized magnetic moments below 60 K. For Sr2CrO4, by contrast, both ZF- and wTF-μ+SR have confirmed the presence of antiferromagnetic order below 117 K, as predicted in the χ(T) curve.

  5. Comparison of Whole-Blood Metal Ion Levels Among Four Types of Large-Head, Metal-on-Metal Total Hip Arthroplasty Implants: A Concise Follow-up, at Five Years, of a Previous Report.

    PubMed

    Hutt, Jonathan; Lavigne, Martin; Lungu, Eugen; Belzile, Etienne; Morin, François; Vendittoli, Pascal-André

    2016-02-17

    Few studies of total hip arthroplasty (THA) implants with a large-diameter femoral head and metal-on-metal design have directly compared the progression of metal ion levels over time and the relationship to complications. As we previously reported, 144 patients received one of four types of large-diameter-head, metal-on-metal THA designs (Durom, Birmingham, ASR XL, or Magnum implants). Cobalt, chromium, and titanium ion levels were measured over five years. We compared ion levels and clinical results over time. The Durom group showed the highest levels of cobalt (p ≤ 0.002) and titanium ions (p ≤ 0.03). Both the Durom and Birmingham groups demonstrated significant ongoing cobalt increases up to five years. Eight patients (seven with a Durom implant and one with a Birmingham implant) developed adverse local tissue reaction. Six Durom implants and one Birmingham implant required revision, with one pseudotumor under surveillance at the time of the most recent follow-up. We found that ion generation and related complications varied among designs. More concerning was that, for some designs, ion levels continued to increase. Coupling a cobalt-chromium adapter sleeve to an unmodified titanium femoral trunnion along with a large metal-on-metal bearing may explain the poor performances of two of the designs in the current study.

  6. A New Type of Carbon Nanostructure Formed Within a Metal-Matrix

    DTIC Science & Technology

    2012-06-01

    during a reaction process in molten aluminum, copper, silver, and other metals. These materials developed by Third Millennium Metals, LLC are called...resolidification. The carbon incorporates into the metal matrix and has an effect on several of the properties of the material . We have performed a detailed...investigation of the structure and composition of several covetics using a variety of microscopy and spectroscopy techniques and found that the

  7. Spectroscopic evidence of 3-hydroxyflavone sorption within MFI type zeolites: ESIPT and metal complexation.

    PubMed

    Moissette, A; Hureau, M; Kokaislova, A; Le Person, A; Cornard, J P; De Waele, I; Batonneau-Gener, I

    2015-10-21

    Due to its chemical and photochemical properties and potential applications in numerous domains as a molecular probe, 3-hydroxyflavone (3HF) is a molecule of high interest. In particular, the processes of intramolecular proton transfer in the excited state and metallic complexation are known to be dependent on the chemical environment. In this context, the particular properties of zeolites make these microporous materials an environment adapted to study the reactivity of isolated molecules adsorbed in their porous void space. Thus, this report investigates the incorporation without any solvent of 3HF into the internal volume of various channel-type MFI zeolites. Using complementary techniques (diffuse reflectance UV-vis absorption, Raman scattering, FTIR, fluorescence emission and molecular modelling), very different spectral behaviours are observed in totally dealuminated silicalite-1 and in Al rich MZSM-5 (M = H(+), Na(+), Zn(2+)). In silicalite-1, the non-polar and non-protic internal micro-environment does not induce any valuable interaction between 3HF and the channel walls. Therefore, the molecule shows easy tautomer formation upon excitation. Within HZSM-5, 3HF is adsorbed in close proximity of the acid proton of the zeolite which inhibits the intramolecular proton transfer and then, only the normal form is observed at the excited state. For NaZSM-5, the spectral data show an intermediary behaviour due to the aprotic but polar environment, in agreement with 3HF sorption in close proximity of the Na(+) extra framework cation. After mixing 3HF and ZnZSM-5, the spectral features clearly indicate metallic complexation of the guest molecule. The zeolite dependent reactivity reported here demonstrates the adsorption of the guest within the internal volume because the charge balancing cations which clearly control the reaction are principally located in the zeolite channels. The 3HF incorporation into the internal volume is proved by the decrease of the microporous

  8. The relation of metal composition to rock type for clasts in Apollo 16 soils

    NASA Technical Reports Server (NTRS)

    Hewins, R. H.; Goldstein, J. I.; Axon, H. J.

    1976-01-01

    The moderately magnetic fractions of soils from a bright ray of South Ray Crater and from the continuous ejecta of North Ray Crater are described. The clasts in these fractions are classified as agglutinate, ANT melt rocks, glassy melt rocks, and ANT hornfels/breccia. Determinations are made of the Ni-Co and P contents of single-phase metal grains in the clasts. It is found that most of these grains have compositions in the meteoritic range and that the compositions tend to cluster at about 6% Ni. A significant amount of Fe-rich metal is also detected in some clasts along with a clear P-enrichment in metal from one soil sample. Meteoritic contamination of lunar metal having compositions in or close to the meteoritic range is considered. A model involving nine separate factors is proposed as an explanation of the observed metal compositions.

  9. Conversion and displacement reaction types of transition metal compounds for sodium ion battery

    NASA Astrophysics Data System (ADS)

    Chen, Guo-Ying; Sun, Qian; Yue, Ji-Li; Shadike, Zulipiya; Yang, Yin; Ding, Fei; Sang, Lin; Fu, Zheng-Wen

    2015-06-01

    Transition metal compounds of FeSe and CuWO4 thin films have been successfully fabricated by using R.F. sputtering method. Although two kinds of transition metal compounds of FeSe and CuWO4 thin films can react with sodium electrochemically, they exhibit different electrochemical features. The nanosized metal Fe is highly dispersed into Na2Se matrix and metal Cu is extruded from Na2WO4 mixture after the FeSe/Na and CuWO4/Na cells are discharged, respectively. The conversion reaction mechanism between FeSe and Na2Se is proposed for the FeSe/Na cell. While the displacement reaction mechanism for CuWO4/Na cell is proposed for the first time based on the transmission electron microscopy (TEM) and selected area electron diffraction (SAED) data. These various mechanisms make transition metal compounds interesting materials for rechargeable sodium ion batteries.

  10. Skyrmion crystal and topological Hall effect in B20-type transition-metal compounds

    NASA Astrophysics Data System (ADS)

    Onose, Yoshinori

    2011-03-01

    Topological objects in solids such as domain walls and vortices have been attracting much attention for long. Among them the spin texture called skyrmion is an unusual topological object, in which the spins point in all the directions wrapping a sphere. The skyrmion hosts finite spin chirality, and therefore is anticipated to induce novel electromagnetic phenomena such as topological Hall effect. In B20-type transition metal compounds MnSi and Fe 1-x Co x Si, the crystallization of skyrmions was observed by the neutron diffraction studies. , . Recently, we have observed the real-space images of skyrmion crystal in thin films of related compounds (Fe 0.5 Co 0.5 Si and FeGe) using Lorentz transmission electron spectroscopy., Nature material, inpress.} We have observed the hexagonal arrangement of skyrmions including the topological defects (chiral domains and dislocations) under the magnetic field normal to the films, and found that the two dimensional skyrmion crystal phase is fairly stabilized by the thin film form of the samples. We have also studied the topological Hall effect caused by the spin chirality of the skyrmion crystal in a related material MnGe. In terms of the Hall measurement, they have shown the real space nature of the fictitious magnetic field caused by the magnetic configuration of the skyrmion crystal, in contrast with the momentum-space fictitious field in another spin chirality system, Nd 2 Mo 2 O7 . This work was done in collaboration with X. Z. Yu, N. Kanazawa, J. H. Park, J. H. Han, K. Kimoto, W. Z. Zhang, S. Ishiwata, Y. Matsui, N. Nagaosa, and Y. Tokura. S. Mühlbauer et al. Science 323, 915 (2009).}

  11. All-weld-metal design for AWS E10018M, E11018M and E12018M type electrodes

    SciTech Connect

    Surian, E.S.; Vedia, L.A. de

    1999-06-01

    This paper presents the results of a research program conducted to design the all-weld metal deposited with AWS A5.5-81 E10018M, E11018M and E12018M SMAW-type electrodes. The role that different alloying elements such as manganese, carbon and chromium play on the tensile properties, hardness and toughness as well as on the microstructure was studied. Criteria for selecting the weld metal composition leading to optimum combination of tensile strength and toughness are suggested. The effect of the variation of heat input, within the requirements of the AWS standard, on the mentioned properties was also analyzed. It was found that the E11018M and E12018M all-weld-metal tensile properties are very sensitive to variations in heat input. For certain values of chemical composition, welding parameter ranges suitable to guarantee the fulfillment of AWS requirements were determined.

  12. Trace metal accumulation in soil and their phytoavailability as affected by greenhouse types in north China.

    PubMed

    Yang, Lanqin; Huang, Biao; Mao, Mingcui; Yao, Lipeng; Hickethier, Martina; Hu, Wenyou

    2015-05-01

    Long-term heavy organic fertilizer application has linked greenhouse vegetable production (GVP) with trace metal contamination in north China. Given that trace metals release from fertilizers and their availability may be affected by discrepant environmental conditions, especially temperature under different greenhouses, this study investigated Cd, Cu, Pb, and Zn accumulation and contamination extent in soil as well as their phytoavailability under two major greenhouses in Tongshan, north China, namely solar greenhouse (SG) and round-arched plastic greenhouse (RAPG), to evaluate their presumed difference. The results showed significant Cd, Cu, Pb, and Zn accumulation in GVP soil by comparing with those in open-field soil, but their accumulation extent and rates were generally greater in SG than those in RAPG. This may be related to more release of trace metals to soil due to the acceleration of decomposition and humification process of organic fertilizers under higher soil temperature in SG relative to that in RAPG. Overall, soil in both greenhouses was generally less polluted or moderately polluted by the study metals. Similarly, decreased soil pH and elevated soil available metals in SG caused higher trace metals in leaf vegetables in SG than those in RAPG, although there was no obvious risk via vegetable consumption under both greenhouses. Lower soil pH may be predominantly ascribed to more intensive farming practices in SG while elevated soil available metals may be attributed to more release of dissolved organic matter-metal complexes from soil under higher temperature in SG. The data provided in this study may assist in developing reasonable and sustainable fertilization strategies to abate trace metal contamination in both greenhouses.

  13. Heavy metal tolerance in the fission yeast requires an ATP-binding cassette-type vacuolar membrane transporter.

    PubMed Central

    Ortiz, D F; Kreppel, L; Speiser, D M; Scheel, G; McDonald, G; Ow, D W

    1992-01-01

    In response to heavy metal stress, plants and certain fungi, such as the fission yeast Schizosaccharomyces pombe, synthesize small metal-binding peptides known as phytochelatins. We have identified a cadmium sensitive S. pombe mutant deficient in the accumulation of a sulfide-containing phytochelatin-cadmium complex, and have isolated the gene, designated hmt1, that complements this mutant. The deduced protein sequence of the hmt1 gene product shares sequence identity with the family of ABC (ATP-binding cassette)-type transport proteins which includes the mammalian P-glycoproteins and CFTR, suggesting that the encoded product is an integral membrane protein. Analysis of fractionated fission yeast cell components indicates that the HMT1 polypeptide is associated with the vacuolar membrane. Additionally, fission yeast strains harboring an hmt1-expressing multicopy plasmid exhibit enhanced metal tolerance along with a higher intracellular level of cadmium, implying a relationship between HMT1 mediated transport and compartmentalization of heavy metals. This suggests that tissue-specific overproduction of a functional hmt1 product in transgenic plants might be a means to alter the tissue localization of these elements, such as for sequestering heavy metals away from consumable parts of crop plants. Images PMID:1396551

  14. Investigation of Surfactant Type, Dosage and Ultrasonication Temperature Control on Dispersity of Metal-Coated Multi-Walled Carbon Nanotubes.

    PubMed

    Liang, Xiaoning; Li, Wei

    2016-04-01

    We studied the dispersity of multi-walled carbon nanotubes (MWNTs) combined with different metal- lic particles (Ni and Fe). An ultrasonic-assisted water-bath dispersion process was used to dis- perse the metal-coated MWNTs in different solutions and the dispersity was measured using an ultraviolet-visible spectrophotometer. The dispersity and morphology of the MWNTs were characterized using field-emission scanning electron microscopy (FE-SEM) together with digital image processing technology. Effects of dispersant type (sodium dodecyl benzene sulfonate (SDBS), oleic acid, and polymer (TNEDIS)) and surfactant dosage on the dispersity of the metal-coated MWNTs were investigated under controlled and uncontrolled temperatures and results were compared with those from the untreated MWNTs. The results showed that the negative effects of temperature on the ultrasonic dispersion process could be eliminated through a temperature-controlled system. Moreover, the TNEDIS, SDBS, and oleic acid were arranged in the descending order of the dispersion effect degree. The untreated MWNTs, Ni-coated MWNTs, and Fe-coated MWNTs were arranged in the descending degree of dispersity order. Since the metal coating makes the MWNTs harder and more fragile, the metal-coated MWNTs are more likely to fracture during the ultrasonic dispersion process.

  15. Heavy metal content in various types of candies and their daily dietary intake by children.

    PubMed

    Devi, Parmila; Bajala, Vandana; Garg, V K; Mor, Suman; Ravindra, Khaiwal

    2016-02-01

    Children are vulnerable to heavy metal contamination through consumption of candies and chocolates. Considering this representative samples (69) of candies and chocolates based on cocoa, milk and sugar were analyzed for selected heavy metals by means of flame atomic absorption spectrometry. The average concentration of Zn, Pb, Ni, and Cd was found to be 2.52 ± 2.49, 2.0 ± 1.20, 0.84 ± 1.35, and 0.17 ± 0.22 μg/g respectively. Results indicate that cocoa-based candies have higher metal content than milk- or sugar-based candies. The daily dietary intake of metals for children eating candies and chocolates was also calculated, and results indicated highest intake of Pb and Zn followed by Ni, Cd, and Cu. Comparison of the current study results with other studies around the globe shows that the heavy metal content in candies and chocolates is lower in India than reported elsewhere. However, to reduce the further dietary exposure of heavy metals through candies and chocolates, their content should be monitored regularly and particularly for Pb as children are highly susceptible to its toxicity.

  16. Revealing a universal planet-metallicity correlation for planets of different solar-type stars

    SciTech Connect

    Wang, Ji; Fischer, Debra A.

    2015-01-01

    The metallicity of exoplanet systems serves as a critical diagnostic of planet formation mechanisms. Previous studies have demonstrated the planet–metallicity correlation for large planets (R{sub P} ⩾ 4 R{sub E}); however, a correlation has not been found for smaller planets. With a sample of 406 Kepler objects of interest whose stellar properties are determined spectroscopically, we reveal a universal planet–metallicity correlation: not only gas-giant planets (3.9 R{sub E} metal-rich stars. The planet occurrence rates of gas-giant planets, gas-dwarf planets, and terrestrial planets are 9.30{sub −3.04}{sup +5.62}, 2.03{sub −0.26}{sup +0.29}, and 1.72{sub −0.17}{sup +0.19} times higher for metal-rich stars than for metal-poor stars, respectively.

  17. Zeolite-type metal organic frameworks immobilized Eu³⁺ for cation sensing in aqueous environment.

    PubMed

    Liu, Chang; Yan, Bing

    2015-12-01

    A novel luminescent lanthanide metal organic framework (Ln-MOF) is synthesized by in situ encapsulating Eu(3+) ions to partial replace the transition-metal clusters in the channels of CPM-17-Zn nanocrystals. The Eu(3+) functionalized zeolite-type MOF hybrid system shows excellent luminescence property and photo-stability in aqueous environment for the sensitization and protection from the host framework. Subsequently, as a highly selective and sensitive sensor, its nanocrystals can be used to detect Cd(2+) in aqueous solution. In addition, the possible sensing mechanism based on ion exchange is discussed in detail. This work is one of the few cases for detecting Cd(2+) in aqueous solution based on a zeolite-type MOF. The good fluorescence stability, low detection limit and broad linear range in aqueous environment make this probe to be expected to have potential application in intracellular sensing and imaging of Cd(2+) potentially.

  18. Interface states and internal photoemission in p-type GaAs metal-oxide-semiconductor surfaces

    NASA Technical Reports Server (NTRS)

    Kashkarov, P. K.; Kazior, T. E.; Lagowski, J.; Gatos, H. C.

    1983-01-01

    An interface photodischarge study of p-type GaAs metal-oxide-semiconductor (MOS) structures revealed the presence of deep interface states and shallow donors and acceptors which were previously observed in n-type GaAs MOS through sub-band-gap photoionization transitions. For higher photon energies, internal photoemission was observed, i.e., injection of electrons to the conduction band of the oxide from either the metal (Au) or from the GaAs valence band; the threshold energies were found to be 3.25 and 3.7 + or - 0.1 eV, respectively. The measured photoemission current exhibited a thermal activation energy of about 0.06 eV, which is consistent with a hopping mechanism of electron transport in the oxide.

  19. Large-scale metal zoning in a late-Precambrian skarn-type mineralization, Wadi Kid, SE Sinai, Egypt

    NASA Astrophysics Data System (ADS)

    Helmy, H. M.; Shalaby, I. M.; Abdel Rahman, H. B.

    2014-02-01

    A Precambrian skarn-type mineralization is recently discovered in the Wadi Kid area in southeast Sinai, Egypt. Two sulfide ore types define large scale metal zoning; Cu-Zn-Co in calc-silicate rocks and Zn-Pb-As-Ag in metapelites. The sulfides and host rocks underwent amphibolite facies metamorphism (2.1-4.2 kbar and 500-620 °C). Dating by the chemical Th-U-total Pb isochrone method yields an Th-Pb isochrone age of 660 ± 25 Ma for metamorphic monazite from metapelites. Overall structural and textural relationships of silicate and sulfide minerals favor syn-tectonic formation during granitoids emplacement in a continental margin setting. Large-scale metal zoning reflects variable distances from the causative pluton(s). The Wadi Kid area is highly prospective for Cu, Zn, Pb and Ag mineralization.

  20. Effect of metal oxide nanoparticles on microbial community structure and function in two different soil types.

    PubMed

    Frenk, Sammy; Ben-Moshe, Tal; Dror, Ishai; Berkowitz, Brian; Minz, Dror

    2013-01-01

    Increased availability of nanoparticle-based products will, inevitably, expose the environment to these materials. Engineered nanoparticles (ENPs) may thus find their way into the soil environment via wastewater, dumpsters and other anthropogenic sources; metallic oxide nanoparticles comprise one group of ENPs that could potentially be hazardous for the environment. Because the soil bacterial community is a major service provider for the ecosystem and humankind, it is critical to study the effects of ENP exposure on soil bacteria. These effects were evaluated by measuring bacterial community activity, composition and size following exposure to copper oxide (CuO) and magnetite (Fe3O4) nanosized (<50 nm) particles. Two different soil types were examined: a sandy loam (Bet-Dagan) and a sandy clay loam (Yatir), under two ENP concentrations (1%, 0.1%). Results indicate that the bacterial community in Bet-Dagan soil was more susceptible to change due to exposure to these ENPs, relative to Yatir soil. More specifically, CuO had a strong effect on bacterial hydrolytic activity, oxidative potential, community composition and size in Bet-Dagan soil. Few effects were noted in the Yatir soil, although 1% CuO exposure did cause a significant decreased oxidative potential and changes to community composition. Fe3O4 changed the hydrolytic activity and bacterial community composition in Bet-Dagan soil but did not affect the Yatir soil bacterial community. Furthermore, in Bet-Dagan soil, abundance of bacteria annotated to OTUs from the Bacilli class decreased after addition of 0.1% CuO but increased with 1% CuO, while in Yatir soil their abundance was reduced with 1% CuO. Other important soil bacterial groups, including Rhizobiales and Sphingobacteriaceae, were negatively affected by CuO addition to soil. These results indicate that both ENPs are potentially harmful to soil environments. Furthermore, it is suggested that the clay fraction and organic matter in different soils

  1. Nickel metal hydride LEO cycle testing

    NASA Technical Reports Server (NTRS)

    Lowery, Eric

    1995-01-01

    The George C. Marshall Space Flight Center is working to characterize aerospace AB5 Nickel Metal Hydride (NiMH) cells. The cells are being evaluated in terms of storage, low earth orbit (LEO) cycling, and response to parametric testing (high rate charge and discharge, charge retention, pulse current ability, etc.). Cells manufactured by Eagle Picher are the subjects of the evaluation. There is speculation that NiMH cells may become direct replacements for current Nickel Cadmium cells in the near future.

  2. DETECTION OF A DISTINCT METAL-POOR STELLAR HALO IN THE EARLY-TYPE GALAXY NGC 3115

    SciTech Connect

    Peacock, Mark B.; Strader, Jay; Romanowsky, Aaron J.; Brodie, Jean P.

    2015-02-10

    We present the resolved stellar populations in the inner and outer halo of the nearby lenticular galaxy NGC 3115. Using deep Hubble Space Telescope observations, we analyze stars 2 mag fainter than the tip of the red giant branch (TRGB). We study three fields along the minor axis of this galaxy, 19, 37, and 54 kpc from its center—corresponding to 7, 14, and 21 effective radii (r{sub e} ). Even at these large galactocentric distances, all of the fields are dominated by a relatively enriched population, with the main peak in the metallicity distribution decreasing with radius from [Z/H] ∼ –0.5 to –0.65. The fraction of metal-poor stars ([Z/H] < –0.95) increases from 17% at 16-37 kpc to 28% at ∼54 kpc. We observe a distinct low-metallicity population (peaked at [Z/H] ∼ –1.3 and with total mass 2 × 10{sup 10} M {sub ☉} ∼ 14% of the galaxy's stellar mass) and argue that this represents the detection of an underlying low-metallicity stellar halo. Such halos are generally predicted by galaxy formation theories and have been observed in several late-type galaxies, including the Milky Way and M31. The metallicity and spatial distribution of the stellar halo of NGC 3115 are consistent with the galaxy's globular cluster system, which has a similar low-metallicity population that becomes dominant at these large radii. This finding supports the use of globular clusters as bright chemodynamical tracers of galaxy halos. These data also allow us to make a precise measurement of the magnitude of the TRGB, from which we derive a distance modulus of NGC 3115 of 30.05 ± 0.05 ± 0.10{sub sys} (10.2 ± 0.2 ± 0.5{sub sys} Mpc)

  3. Bulk and surface half-metallicity: The case of D0{sub 3}-type Mn{sub 3}Ge

    SciTech Connect

    Liu, Hao; Gao, G. Y. Hu, Lei; Ni, Yun; Zu, Fengxia; Zhu, Sicong; Wang, Shuling; Yao, K. L.

    2014-01-21

    Motivated by the experimental realization of D0{sub 22}-type Mn{sub 3}Ge (001) films [Kurt et al. Appl. Phys. Lett. 101, 132410 (2012)] and the structural stability of D0{sub 3}-type Heusler alloy Mn{sub 3}Ge [Zhang et al. J. Phys.: Condens. Matter 25, 206006 (2013)], we use the first-principles calculations based on the full potential linearized augmented plane-wave method to investigate the electronic and magnetic properties of D0{sub 3}-type Heusler alloy Mn{sub 3}Ge and its (001) surface. We show that bulk D0{sub 3}-Mn{sub 3}Ge is a half-metallic ferromagnet with the minority-spin energy gap of 0.52 eV and the magnetic moment of 1.00 μ{sub B} per formula unit. The bulk half-metallicity is preserved at the pure Mn-terminated (001) surface due to the large exchange split, but the MnGe-terminated (001) surface destroys the bulk half-metallicity. We also reveal that the surface stabilities are comparable between the D0{sub 3}-Mn{sub 3}Ge (001) and the experimental D0{sub 22}-Mn{sub 3}Ge (001), which indicates the feasibility to grow the Mn{sub 3}Ge (001) films with D0{sub 3} phase other than D0{sub 22} one. The surface half-metallicity and stability make D0{sub 3}-Mn{sub 3}Ge a promising candidate for spintronic applications.

  4. Study of compensation in insulating and metallic n-type CdSe using transport measurements

    SciTech Connect

    Levy, M.; Roy, A.; Sarachik, M.P.; Isaacs, L.L.

    1988-08-15

    The resistivity and the Hall coefficient of indium-doped cadmium selenide with carrier concentrations spanning the insulator-to-metal transition have been measured as a function of temperature. We demonstrate that use of the Hall mobility deduced from these data and careful analysis and application of recent theory yield an estimate of the degree of compensation, K = N/sub A//N/sub D/, for metallic as well as insulating material. Combining these results with Hall coefficient measurements at room temperature, one can then estimate both the number of donors, N/sub D/, and acceptors, N/sub A/. .AE

  5. NRF2 Oxidative Stress Induced by Heavy Metals is Cell Type Dependent

    EPA Science Inventory

    Exposure to metallic environmental toxicants has been demonstrated to induce a variety of oxidative stress responses in mammalian cells. The transcription factor Nrf2 is activated in response to oxidative stress and coordinates the expression of antioxidant gene products. In this...

  6. Evaluation of serum ferritin and some metal elements in type 2 diabetes mellitus patients: comparative cross-sectional study

    PubMed Central

    Wolide, Amare Desalegn; Zawdie, Belay; Alemayehu, Tilahun; Tadesse, Samuel

    2016-01-01

    Background The chronic hyperglycemia of diabetes has been associated with an imbalance of some trace metal elements in the blood sample of type 2 diabetes patients. Aim To evaluate the status of serum ferritin and some selected metal elements among type 2 diabetes mellitus (T2DM) patients. Methods Facility-based comparative cross-sectional study was conducted from February 15, 2015 to October 30, 2015, at Jimma University Specialized Hospital, Ethiopia. A total of 428 type 2 diabetes and nondiabetes study subjects were recruited to the study. After overnight fasting, 10 mL of venous blood samples were taken for biochemical and trace metal element analysis. Data were entered into EpiData version 3.5.1 and exported to SPSS version 20 for Windows for analysis. Results Serum concentration of Zn+2, Mg+2, Cr+3, ferritin, and Fe+3 in patients with type 2 diabetes was significantly lower (p<0.0001) than nondiabetes patients. In contrast, serum Cu+2 was significantly higher (p<0.0001) in type 2 diabetes patients than nondiabetics. In addition, significant differences were not seen in both groups with regard to serum Mn+2, Ca+2, and Po4−3. Waist-to-hip ratio (WHR), serum Fe+3, ferritin, and Mn+2 were significantly higher among oral hypoglycemic agent users of type 2 diabetes patients than the injectable insulin users. Serum Zn+2 had significant positive correlation with serum Mg+2 (r=0.738), Cr+3 (r=0.233), Ca+2 (r=0.238), and Po4−3 (r=0.222). In addition, serum Zn+2 had shown significant and negative correlation with body mass index (BMI, r=−0.331), WHR (r=−0.340), and fasting blood glucose (FBG, r=−0.186). Likewise, serum Mg+2 and Po4−3 are significantly and negatively correlated with BMI, WHR, and FBG. Conclusion The imbalance of trace metal elements in the blood sample of diabetes is uncertain. Thus, we recommend a prospective cohort study to find out the principal factors behind the problem. PMID:27980430

  7. 3c/4e σ-type long-bonding: a novel transitional motif toward the metallic delocalization limit.

    PubMed

    Landis, C R; Weinhold, F

    2013-05-06

    We describe a novel "long-bonding" motif that appears in the framework of natural bond orbital (NBO) analysis as a surprising form of 3-center, 4-electron (3c/4e) L···A···L' bonding with "inverted" electronegativity pattern Ξ(A) > Ξ(L), Ξ(L'). Such long-bonding (denoted L(^)L') underlies the predicted (meta)stability of exotic rare gas species with highly electronegative ligands (e.g., HeF2, NeF2) as well as the absolute stability of low-electronegativity metallic triads (e.g., BeLi2, ZnCu2, and related species) that are experimentally unknown but can be anticipated from simple valency and electronegativity trends. We focus particularly on the BeLi2 triad, whose Lewis-type Li(^)Li' long bond is of paradoxical antibonding phase pattern, denoted σ*(LiLi') to suggest its essential 2(-1/2)(s(Li) - s(Li')) orbital composition. We demonstrate how the long-bonded triad serves as a fundamental building-block for numerous 1-, 2-, and 3-d structures that are predicted to exhibit extraordinary calorimetric, vibrational, and electric polarizability properties, commonly associated with the delocalized metallic limit. Both thermodynamic and kinetic results support the NBO inference that σ/σ*-type long-bonding signals the transition to a fundamentally new regime of chemical association, separated by significant activation barriers from the covalent molecular domain and characterized by reversed perturbative precedence of Lewis-type vs resonance-type donor-acceptor contributions. Long-bond resonance therefore appears to be of central importance to a broadened conceptual picture of molecular and metallic interaction phenomena.

  8. Improving metal/semiconductor conductivity using AlO{sub x} interlayers on n-type and p-type Si

    SciTech Connect

    King, P. J.; Arac, E.; Ganti, S.; Kwa, K. S. K.; Ponon, N.; O'Neill, A. G.

    2014-08-04

    Thermal atomic layer deposition was used to form ultra-thin interlayers in metal/interlayer/ semiconductor Ohmic contacts on n-type and p-type Si. AlO{sub x} of thickness 1–2 nm was deposited at 120 °C on Si substrates prior to metallization, forming Ni/AlO{sub x}/Si contacts. Conductivity improved by two orders of magnitude but the contacts remained rectifying. When they were annealed at 200 °C, the conductivity increased by another order of magnitude and the samples became Ohmic. A minimum specific contact resistivity of 1.5 × 10{sup −4} Ω-cm{sup 2} was obtained for structures based on lightly doped (10{sup 15 }cm{sup −3}) Si substrates. Existing models that describe Fermi level de-pinning do not fully explain our results, which are however consistent with other experimental data in the literature.

  9. THE X-RAY LUMINOSITY FUNCTION OF LOW MASS X-RAY BINARIES IN EARLY-TYPE GALAXIES, THEIR METAL-RICH, AND METAL-POOR GLOBULAR CLUSTERS

    SciTech Connect

    Peacock, Mark B.; Zepf, Stephen E.

    2016-02-10

    We present the X-ray luminosity function (XLF) of low-mass X-ray binaries (LMXBs) in the globular clusters (GCs) and fields of seven early-type galaxies. These galaxies are selected to have both deep Chandra observations, which allow their LMXB populations to be observed to X-ray luminosities of 10{sup 37}–10{sup 38} erg s{sup −1}, and Hubble Space Telescope optical mosaics that enable the X-ray sources to be separated into field LMXBs, GC LMXBs, and contaminating background and foreground sources. We find that at all luminosities the number of field LMXBs per stellar mass is similar in these galaxies. This suggests that the field LMXB populations in these galaxies are not effected by the GC specific frequency, and that properties such as binary fraction and the stellar initial mass function are either similar across the sample or change in a way that does not affect the number of LMXBs. We compare the XLF of the field LMXBs to that of the GC LMXBs and find that they are significantly different with a p-value of 3 × 10{sup −6} (equivalent to 4.7σ for a normal distribution). The difference is such that the XLF of the GC LMXBs is flatter than that of the field LMXBs, with the GCs hosting relatively more bright sources and fewer faint sources. A comparison of the XLF of the metal-rich and metal-poor GCs hints that the metal-poor clusters may have more bright LMXBs, but the difference is not statistically significant.

  10. How to avoid a negative shift in reflection-type surface plasmon resonance biosensors with metallic nanostructures.

    PubMed

    Kim, Nak-Hyeon; Kim, Tae Woo; Byun, Kyung Min; Leem, Jung Woo; Yu, Jae Su

    2014-02-24

    We experimentally demonstrate that introduction of a dielectric film can prevent the surface plasmon resonance (SPR) curve from being shifted to a smaller angle, called negative shift, which occurs unpredictably when metallic nanostructures deposited on a metal film are exposed to an adsorption of binding analytes. From parylene coating experiments, we find that the proposed reflection-type SPR system with a low refractive index MgF2 film and gold nanorods can provide an enhanced sensitivity by more than 6 times as well as a reliable positive shift. It is due to the fact that use of a dielectric film can contribute to the compensation of an anomalous dispersion relation and the prevention of a destructive interaction of propagating surface plasmons with multiple localized plasmon modes. Our approach is intended to show the feasibility and extend the applicability of the proposed SPR system to diverse biomolecular reactions.

  11. Transition rates of selected metals determined in various types of teas (Camellia sinensis L. Kuntze) and herbal/fruit infusions.

    PubMed

    Schulzki, Grit; Nüßlein, Birgit; Sievers, Hartwig

    2017-01-15

    Teas and raw materials used as ingredients of herbal and fruit infusions (HFI) were analysed by means of ICP-MS for their content of aluminium, arsenic, cadmium, copper, lead and mercury in the dry product and in the infusion. Samples of tea (Camellia sinensis L. Kuntze) were selected to include different origins, types (black, green), leaf grades (whole leaf, broken, fannings, dust) and manufacturing techniques (orthodox, "crush, tear, curl"). The selected HFI raw materials (chamomile, elderberries, fennel, hibiscus, mate, peppermint, rooibos and rose hip) cover the most important matrices (flower, fruit, seed, herb, leaf) and reflect the economic significance of these HFI materials in trade. Infusions were prepared under standardised conditions representing typical household brewing. Transition rates for the investigated metals vary significantly but are mostly well below 100%. We propose default transition rates for metals to avoid overestimation of exposure levels from tea/HFI consumption.

  12. Toxicity of 11 Metal Oxide Nanoparticles to Three Mammalian Cell Types In Vitro.

    PubMed

    Ivask, Angela; Titma, Tiina; Visnapuu, Meeri; Vija, Heiki; Kakinen, Aleksandr; Sihtmae, Mariliis; Pokhrel, Suman; Madler, Lutz; Heinlaan, Margit; Kisand, Vambola; Shimmo, Ruth; Kahru, Anne

    2015-01-01

    The knowledge on potential harmful effects of metallic nanomaterials lags behind their increased use in consumer products and therefore, the safety data on various nanomaterials applicable for risk assessment are urgently needed. In this study, 11 metal oxide nanoparticles (MeOx NPs) prepared using flame pyrolysis method were analyzed for their toxicity against human alveolar epithelial cells A549, human epithelial colorectal cells Caco2 and murine fibroblast cell line Balb/c 3T3. The cell lines were exposed for 24 h to suspensions of 3-100 μg/mL MeOx NPs and cellular viability was evaluated using. Neutral Red Uptake (NRU) assay. In parallel to NPs, toxicity of soluble salts of respective metals was analyzed, to reveal the possible cellular effects of metal ions shedding from the NPs. The potency of MeOx to produce reactive oxygen species was evaluated in the cell-free assay. The used three cell lines showed comparable toxicity responses to NPs and their metal ion counterparts in the current test setting. Six MeOx NPs (Al2O3, Fe3O4, MgO, SiO2, TiO2, WO3) did not show toxic effects below 100 µg/mL. For five MeOx NPs, the averaged 24 h IC50 values for the three mammalian cell lines were 16.4 µg/mL for CuO, 22.4 µg/mL for ZnO, 57.3 µg/mL for Sb2O3, 132.3 µg/mL for Mn3O4 and 129 µg/mL for Co3O4. Comparison of the dissolution level of MeOx and the toxicity of soluble salts allowed to conclude that the toxicity of CuO, ZnO and Sb2O3 NPs was driven by release of metal ions. The toxic effects of Mn3O4 and Co3O4 could be attributed to the ROS-inducing ability of these NPs. All the NPs were internalized by the cells according to light microscopy studies but also proven by TEM, and internalization of Co3O4 NPs seemed to be most prominent in this aspect. In conclusion, this work provides valuable toxicological data for a library of 11 MeOx NPs. Combining the knowledge on toxic or non-toxic nature of nanomaterials may be used for safe-by-design approach.

  13. Uncovering the transmembrane metal binding site of the novel bacterial major facilitator superfamily-type copper importer CcoA

    DOE PAGES

    Khalfaoui-Hassani, Bahia; Verissimo, Andreia F.; Koch, Hans -Georg; ...

    2016-01-19

    In this study, uptake and trafficking of metals and their delivery to their respective metalloproteins are important processes. Cells need precise control of each step to avoid exposure to excessive metal concentrations and their harmful consequences. Copper (Cu) is a required micronutrient used as a cofactor in proteins. However, in large amounts, it can induce oxidative damage; hence, Cu homeostasis is indispensable for cell survival. Biogenesis of respiratory heme-Cu oxygen (HCO) reductases includes insertion of Cu into their catalytic subunits to form heme-Cu binuclear centers. Previously, we had shown that CcoA is a major facilitator superfamily (MFS)-type bacterial Cu importermore » required for biogenesis of cbb3-type cytochromecoxidase (cbb3-Cox). Here, using Rhodobacter capsulatus, we focused on the import and delivery of Cu to cbb3-Cox. By comparing the CcoA amino acid sequence with its homologues from other bacterial species, we located several well-conserved Met, His, and Tyr residues that might be important for Cu transport. We determined the topology of the transmembrane helices that carry these residues to establish that they are membrane embedded, and substituted for them amino acids that do not ligand metal atoms. Characterization of these mutants for their uptake of radioactive64Cu and cbb3-Cox activities demonstrated that Met233 and His261 of CcoA are essential and Met237 and Met265 are important, whereas Tyr230 has no role for Cu uptake or cbb3-Cox biogenesis. These findings show for the first time that CcoA-mediated Cu import relies on conserved Met and His residues that could act as metal ligands at the membrane-embedded Cu binding domain of this transporter.« less

  14. Uncovering the Transmembrane Metal Binding Site of the Novel Bacterial Major Facilitator Superfamily-Type Copper Importer CcoA

    PubMed Central

    Khalfaoui-Hassani, Bahia; Verissimo, Andreia F.; Koch, Hans-Georg

    2016-01-01

    ABSTRACT Uptake and trafficking of metals and their delivery to their respective metalloproteins are important processes. Cells need precise control of each step to avoid exposure to excessive metal concentrations and their harmful consequences. Copper (Cu) is a required micronutrient used as a cofactor in proteins. However, in large amounts, it can induce oxidative damage; hence, Cu homeostasis is indispensable for cell survival. Biogenesis of respiratory heme-Cu oxygen (HCO) reductases includes insertion of Cu into their catalytic subunits to form heme-Cu binuclear centers. Previously, we had shown that CcoA is a major facilitator superfamily (MFS)-type bacterial Cu importer required for biogenesis of cbb3-type cytochrome c oxidase (cbb3-Cox). Here, using Rhodobacter capsulatus, we focused on the import and delivery of Cu to cbb3-Cox. By comparing the CcoA amino acid sequence with its homologues from other bacterial species, we located several well-conserved Met, His, and Tyr residues that might be important for Cu transport. We determined the topology of the transmembrane helices that carry these residues to establish that they are membrane embedded, and substituted for them amino acids that do not ligand metal atoms. Characterization of these mutants for their uptake of radioactive 64Cu and cbb3-Cox activities demonstrated that Met233 and His261 of CcoA are essential and Met237 and Met265 are important, whereas Tyr230 has no role for Cu uptake or cbb3-Cox biogenesis. These findings show for the first time that CcoA-mediated Cu import relies on conserved Met and His residues that could act as metal ligands at the membrane-embedded Cu binding domain of this transporter. PMID:26787831

  15. Recent progress on metal core@semiconductor shell nanocomposites as a promising type of photocatalyst

    NASA Astrophysics Data System (ADS)

    Zhang, Nan; Liu, Siqi; Xu, Yi-Jun

    2012-03-01

    The creation of core-shell nanocomposites (CSNs) has attracted considerable attention and developed into an increasingly important research area at the frontier of advanced materials chemistry. CSNs, which are nanoscaled assemblies with a chemical composition that is different on the surface compared to the core region, have found versatile applications in many fields, such as electrooptics, quantum dots, microscopy labels, drug delivery, chemical sensors, nanoreactors and catalysis. This review is primarily focused on the applications of metal core@semiconductor shell nanocomposites in heterogeneous photocatalysis, including photocatalytic nonselective processes for environmental remediation, selective organic transformations to fine chemicals and water splitting to clean hydrogen energy. It is hoped that this minireview can inspire multidisciplinary research interest in the precisely morphology-controlled synthesis of a variety of metal core@semiconductor shell nanoassemblies and their wide applications in the realm of heterogeneous photocatalysis.

  16. Micro-Reactions on Metal Contacts on Various Types of GaAs Surfaces.

    DTIC Science & Technology

    1986-02-01

    GaAs surfaces as generally employed for the manufacture of MeSFETs and their IC’s, particularly _- . - in view of device-life-time optimization...electrodes (points A(v) and (vii) of Section C-I, Award Dec.); in particular here the formation of ._ narrow, short circuiting metal filaments by field... MeSFETs has beco . -’.. a field of wide current interest particularly from the device aging point of view /9/. : - . -. . p. . Here, we describe the

  17. A novel P(1B)-type Mn2+-transporting ATPase is required for secreted protein metallation in mycobacteria.

    PubMed

    Padilla-Benavides, Teresita; Long, Jarukit E; Raimunda, Daniel; Sassetti, Christopher M; Argüello, José M

    2013-04-19

    Transition metals are central for bacterial virulence and host defense. P(1B)-ATPases are responsible for cytoplasmic metal efflux and play roles either in limiting cytosolic metal concentrations or in the maturation of secreted metalloproteins. The P(1B)-ATPase, CtpC, is required for Mycobacterium tuberculosis survival in a mouse model (Sassetti, C. M., and Rubin, E. J. (2003) Genetic requirements for mycobacterial survival during infection. Proc. Natl. Acad. Sci. U.S.A. 100, 12989-12994). CtpC prevents Zn(2+) toxicity, suggesting a role in Zn(2+) export from the cytosol (Botella, H., Peyron, P., Levillain, F., Poincloux, R., Poquet, Y., Brandli, I., Wang, C., Tailleux, L., Tilleul, S., Charriere, G. M., Waddell, S. J., Foti, M., Lugo-Villarino, G., Gao, Q., Maridonneau-Parini, I., Butcher, P. D., Castagnoli, P. R., Gicquel, B., de Chastellièr, C., and Neyrolles, O. (2011) Mycobacterial P1-type ATPases mediate resistance to zinc poisoning in human macrophages. Cell Host Microbe 10, 248-259). However, key metal-coordinating residues and the overall structure of CtpC are distinct from Zn(2+)-ATPases. We found that isolated CtpC has metal-dependent ATPase activity with a strong preference for Mn(2+) over Zn(2+). In vivo, CtpC is unable to complement Escherichia coli lacking a functional Zn(2+)-ATPase. Deletion of M. tuberculosis or Mycobacterium smegmatis ctpC leads to cytosolic Mn(2+) accumulation but no alterations in other metals levels. Whereas ctpC-deficient M. tuberculosis is sensitive to extracellular Zn(2+), the M. smegmatis mutant is not. Both ctpC mutants are sensitive to oxidative stress, which might explain the Zn(2+)-sensitive phenotype of the M. tuberculosis ctpC mutant. CtpC is a high affinity/slow turnover ATPase, suggesting a role in protein metallation. Consistent with this hypothesis, mutation of CtpC leads to a decrease of Mn(2+) bound to secreted proteins and of the activity of secreted Fe/Mn-superoxide dismutase, particularly in M. smegmatis

  18. Half-metallicity in Heusler-type Fe2Cr1-x Co x Si alloys

    NASA Astrophysics Data System (ADS)

    Ramudu, M.; Inamdar, Swaleha; Arout Chelvane, J.; Manivel Raja, M.; Kamat, S. V.

    2016-02-01

    The effects of the substitution of Cr with Co on microstructure, phase composition, structure, magnetic, and electrical properties in \\text{F}{{\\text{e}}2}\\text{C}{{\\text{r}}1-x}\\text{C}{{\\text{o}}x}\\text{Si} (0  ⩽  x  ⩽  1) alloys was investigated to identify the compositions with the potential to exhibit half-metallicity. The microstructural and structural studies revealed that only \\text{F}{{\\text{e}}2}\\text{C}{{\\text{r}}1-x}\\text{C}{{\\text{o}}x}\\text{Si} alloys with x  ⩾  0.5 exhibited the desired single phase L21 full Heusler alloy structure. Both the saturation magnetization (M s) and Curie temperature (T C) were found to increase with the increase in Co concentration. The experimentally measured M s values are in good agreement with the Slater-Pauling rule. The electrical resistivity measurements in the temperature range 10-300 K gives indirect evidence of half-metallic behaviour in these alloys at low temperatures. The temperature range in which the half-metallic behaviour was observed also increased with an increase in Co concentration.

  19. PROSPECTING IN LATE-TYPE DWARFS: A CALIBRATION OF INFRARED AND VISIBLE SPECTROSCOPIC METALLICITIES OF LATE K AND M DWARFS SPANNING 1.5 dex

    SciTech Connect

    Mann, Andrew W.; Hilton, Eric J.; Brewer, John M.; Gaidos, Eric; Lepine, Sebastien

    2013-02-01

    Knowledge of late K and M dwarf metallicities can be used to guide planet searches and constrain planet formation models. However, the determination of metallicities of late-type stars is difficult because visible wavelength spectra of their cool atmospheres contain many overlapping absorption lines, preventing the measurement of equivalent widths. We present new methods, and improved calibrations of existing methods, to determine metallicities of late K and M dwarfs from moderate resolution (1300 < R < 2000) visible and infrared spectra. We select a sample of 112 wide binary systems that contain a late-type companion to a solar-type primary star. Our sample includes 62 primary stars with previously published metallicities, as well as 50 stars with metallicities determined from our own observations. We use our sample to empirically determine which features in the spectrum of the companion are best correlated with the metallicity of the primary. We find {approx_equal}120 features in K and M dwarf spectra that are useful for predicting metallicity. We derive metallicity calibrations for different wavelength ranges, and show that it is possible to get metallicities reliable to <0.10 dex using either visible, J-, H-, or K-band spectra. We find that the most accurate metallicities derived from visible spectra requires the use of different calibrations for early-type (K5.5-M2) and late-type (M2-M6) dwarfs. Our calibrations are applicable to dwarfs with metallicities of -1.04 < [Fe/H] <+0.56 and spectral types from K7 to M5. Lastly, we use our sample of wide binaries to test and refine existing calibrations to determine M dwarf metallicities. We find that the {zeta} parameter, which measures the ratio of TiO can CaH bands, is correlated with [Fe/H] for super-solar metallicities, and {zeta} does not always correctly identify metal-poor M dwarfs. We also find that existing calibrations in the K and H bands are quite reliable for stars with [Fe/H] >-0.5, but are less useful

  20. Response to metal stress of Nicotiana langsdorffii plants wild-type and transgenic for the rat glucocorticoid receptor gene.

    PubMed

    Fuoco, Roger; Bogani, Patrizia; Capodaglio, Gabriele; Del Bubba, Massimo; Abollino, Ornella; Giannarelli, Stefania; Spiriti, Maria Michela; Muscatello, Beatrice; Doumett, Saer; Turetta, Clara; Zangrando, Roberta; Zelano, Vincenzo; Buiatti, Marcello

    2013-05-01

    Recently our findings have shown that the integration of the gene coding for the rat gluco-corticoid receptor (GR receptor) in Nicotiana langsdorffii plants induced morphophysiological effects in transgenic plants through the modification of their hormonal pattern. Phytohormones play a key role in plant responses to many different biotic and abiotic stresses since a modified hormonal profile up-regulates the activation of secondary metabolites involved in the response to stress. In this work transgenic GR plants and isogenic wild type genotypes were exposed to metal stress by treating them with 30ppm cadmium(II) or 50ppm chromium(VI). Hormonal patterns along with changes in key response related metabolites were then monitored and compared. Heavy metal up-take was found to be lower in the GR plants. The transgenic plants exhibited higher values of S-abscisic acid (S-ABA) and 3-indole acetic acid (IAA), salicylic acid and total polyphenols, chlorogenic acid and antiradical activity, compared to the untransformed wild type plants. Both Cd and Cr treatments led to an increase in hormone concentrations and secondary metabolites only in wild type plants. Analysis of the results suggests that the stress responses due to changes in the plant's hormonal system may derive from the interaction between the GR receptor and phytosteroids, which are known to play a key role in plant physiology and development.

  1. Radiochemical Separation and Quantification of Tritium in Metallic Radwastes Generated from CANDU Type NPP - 13279

    SciTech Connect

    Ahn, H.J.; Choi, K.C.; Choi, K.S.; Park, T.H.; Park, Y.J.; Song, K.

    2013-07-01

    As a destructive quantification method of {sup 3}H in low and intermediate level radwastes, bomb oxidation, sample oxidation, and wet oxidation methods have been introduced. These methods have some merits and demerits in the radiochemical separation of {sup 3}H radionuclides. That is, since the bomb oxidation and sample oxidation methods are techniques using heating at high temperature, the separation methods of the radionuclides are relatively simple. However, since {sup 3}H radionuclide has a property of being diffused deeply into the inside of metals, {sup 3}H which is distributed on the surface of the metals can only be extracted if the methods are applied. As an another separation method, the wet oxidation method makes {sup 3}H oxidized with an acidic solution, and extracted completely to an oxidized HTO compound. However, incomplete oxidized {sup 3}H compounds, which are produced by reactions of acidic solutions and metallic radwastes, can be released into the air. Thus, in this study, a wet oxidation method to extract and quantify the {sup 3}H radionuclide from metallic radwastes was established. In particular, a complete extraction method and complete oxidation method of incomplete chemical compounds of {sup 3}H using a Pt catalyst were studied. The radioactivity of {sup 3}H in metallic radwastes is extracted and measured using a wet oxidation method and liquid scintillation counter. Considering the surface dose rate of the sample, the appropriate size of the sample was determined and weighed, and a mixture of oxidants was added to a 200 ml round flask with 3 tubes. The flask was quickly connected to the distilling apparatus. 20 mL of 16 wt% H{sub 2}SO{sub 4} was given into the 200-ml round flask through a dropping funnel while under stirring and refluxing. After dropping, the temperature of the mixture was raised to 96 deg. C and the sample was leached and oxidized by refluxing for 3 hours. At that time, the incomplete oxidized {sup 3}H compounds were

  2. A porous sodalite-type MOF based on tetrazolcarboxylate ligands and [Cu4Cl]7+ squares with open metal sites for gas sorption.

    PubMed

    Wang, Dongmei; Zhao, Tingting; Li, Guanghua; Huo, Qisheng; Liu, Yunling

    2014-02-14

    A porous sodalite-type metal-organic framework based on tetrazolcarboxylate ligands and [Cu4Cl](7+) squares was successfully synthesized, which exhibited permanent porosity and high adsorption abilities of H2, CO2 and organic chemical pollutants.

  3. A sodalite-type porous metal-organic framework with polyoxometalate templates: adsorption and decomposition of dimethyl methylphosphonate.

    PubMed

    Ma, Feng-Ji; Liu, Shu-Xia; Sun, Chun-Yan; Liang, Da-Dong; Ren, Guo-Jian; Wei, Feng; Chen, Ya-Guang; Su, Zhong-Min

    2011-03-30

    A sodalite-type porous metal-organic framework with polyoxometalate templates, H(3)[(Cu(4)Cl)(3)(BTC)(8)](2)[PW(12)O(40)]·(C(4)H(12)N)(6)·3H(2)O (NENU-11; BTC = 1,3,5-benzenetricarboxylate), was obtained by a hydrothermal reaction. As a reasonable candidate for eliminating nerve gas, NENU-11 displays good adsorption behavior for dimethyl methylphosphonate (15.5 molecules per formula unit). In virtue of the catalytic activity of polyoxometalate guests, this nerve gas mimic could be facilely decomposed by a hydrolysis reaction.

  4. Physically-Based and Power-Law Constitutive Relations for Higher Temperature Metal Processing and Creep-Type Deformations

    NASA Astrophysics Data System (ADS)

    Armstrong, R. W.; Balasubramanian, N.

    2017-02-01

    There is continuing research interest in the development and use of constitutive relations for assistance with description and optimization of higher temperature metal and alloy processing conditions and desired mechanical property performances, particularly in the latter case for nanopolycrystalline materials under creep-type loading deformations. Here, we focus on the plastic flow stress dependence on strain rate, temperature, and especially, on material grain size. Connection is established between, on the one hand, relatively recent thermal-activation-based relations for dislocation motion and, on the other hand, comparative power law expressions.

  5. SPR-based PCF D-type sensor based on a metamaterial composed of planar metals for refractive index sensing

    NASA Astrophysics Data System (ADS)

    Santos, D. F.; Guerreiro, A.; Baptista, J. M.

    2016-05-01

    This paper presents a numerically investigation of the performance analysis of a conventional photonic crystal fiber (PCF) with a planar metamaterials structure for refractive index sensing, based on surface plasmon resonance (SPR), using the finite element method (FEM). We study the concentration metamaterials conformed by the aluminium oxide (Al2O3) and silver (Ag) and compared its performance with a single metal (Ag), assessing their impacts in the effective refractive index. Furthermore, we also use different types of mechanics to describe the effects of varying the structural parameters sensor on the evanescent field and the sensor performance.

  6. In operando neutron diffraction study of LaNdMgNi9H13 as a metal hydride battery anode

    NASA Astrophysics Data System (ADS)

    Nazer, N. S.; Denys, R. V.; Yartys, V. A.; Hu, Wei-Kang; Latroche, M.; Cuevas, F.; Hauback, B. C.; Henry, P. F.; Arnberg, L.

    2017-03-01

    La2MgNi9-related alloys are superior metal hydride battery anodes as compared to the commercial AB5 alloys. Nd-substituted La2-yNdyMgNi9 intermetallics are of particular interest because of increased diffusion rate of hydrogen and thus improved performance at high discharge currents. The present work presents in operando characterization of the LaNdMgNi9 intermetallic as anode for the nickel metal hydride (Ni-MH) battery. We have studied the structural evolution of LaNdMgNi9 during its charge and discharge using in situ neutron powder diffraction. The work included experiments using deuterium gas and electrochemical charge-discharge measurements. The alloy exhibited a high electrochemical discharge capacity (373 mAh/g) which is 20% higher than the AB5 type alloys. A saturated β-deuteride synthesized by solid-gas reaction at PD2 = 1.6 MPa contained 12.9 deuterium atoms per formula unit (D/f.u.) which resulted in a volume expansion of 26.1%. During the electrochemical charging, the volume expansion (23.4%) and D-contents were found to be slightly reduced. The reversible electrochemical cycling is performed through the formation of a two-phase mixture of the α-solid solution and β-hydride phases. Nd substitution contributes to the high-rate dischargeability, while maintaining a good cyclic stability. Electrochemical Impedance Spectroscopy (EIS) was used to characterize the anode electrode on cycling. A mathematical model for the impedance response of a porous electrode was utilized. The EIS showed a decreased hydrogen transport rate during the long-term cycling, which indicated a corresponding slowing down of the electrochemical processes at the surface of the metal hydride anode.

  7. Noble-metal minerals in ores of the black-shale type in the Voronezh Crystalline Massif, central Russia

    NASA Astrophysics Data System (ADS)

    Chernyshov, N. M.

    2009-12-01

    High-carbonaceous stratified formations and related metasomatic rocks of global abundance are among highly promising sources of gold and platinum-group metals (PGMs) in the 21st century. The Au-PGM mineralization of the black-shale type hosted in the Early Karelian Kursk and Oskol groups in central Russia is characterized by complex multicomponent and polymineralic composition (more than 60 ore minerals, including more than 20 Au and PGM phases) and diverse speciation of noble metals in form of (1) native elements (gold, palladium, platinum, osmium, silver); (2) metallic solid solutions and intermetallic compounds (Pt-bearing palladium, Fe-bearing platinum, gold-platinum-palladium, osmiridium, rutheniridosmin, platiridosmin, platosmiridium, Hg-Te-Ag-bearing gold, gold-silver amalgam, arquerite, palladium stannide (unnamed mineral), platinum-palladium-gold-silver-tin); (3) PGM, Au, and Ag sulfoarsenides, tellurides, antimonides, selenides, and sulfosalts (sperrylite, irarsite, hessite, Pd and Pt selenide (unnamed mineral)), testibiopalladinite, Pd antimonide (unnamed mineral), etc.; and (4) impurities in ore-forming sulfides, sulfoarsenides, tellurides, antimonides, and selenides. The chemical analyses of PGM and Au minerals are presented, and their morphology and microstructure are considered.

  8. THE QUEST FOR CRADLES OF LIFE: USING THE FUNDAMENTAL METALLICITY RELATION TO HUNT FOR THE MOST HABITABLE TYPE OF GALAXY

    SciTech Connect

    Dayal, Pratika; Cockell, Charles; Rice, Ken; Mazumdar, Anupam

    2015-09-01

    The field of astrobiology has made huge strides in understanding the habitable zones around stars (stellar habitable zones) where life can begin, sustain its existence and evolve into complex forms. A few studies have extended this idea by modeling galactic-scale habitable zones (galactic habitable zones) for our Milky Way (MW) and specific elliptical galaxies. However, estimating the habitability for galaxies spanning a wide range of physical properties has so far remained an outstanding issue. Here, we present a “cosmobiological” framework that allows us to sift through the entire galaxy population in the local universe and answer the question, “Which type of galaxy is most likely to host complex life in the cosmos?” Interestingly, the three key astrophysical criteria governing habitability (total mass in stars, total metal mass and ongoing star formation rate) are found to be intricately linked through the “fundamental metallicity relation” as shown by Sloan Digital Sky Survey observations of more than a hundred thousand galaxies in the local universe. Using this relation we show that metal-rich, shapeless giant elliptical galaxies at least twice as massive as the MW (with a tenth of its star formation rate) can potentially host ten thousand times as many habitable (Earth-like) planets, making them the most probable “cradles of life” in the universe.

  9. The Quest for Cradles of Life: Using the Fundamental Metallicity Relation to Hunt for the Most Habitable Type of Galaxy

    NASA Astrophysics Data System (ADS)

    Dayal, Pratika; Cockell, Charles; Rice, Ken; Mazumdar, Anupam

    2015-09-01

    The field of astrobiology has made huge strides in understanding the habitable zones around stars (stellar habitable zones) where life can begin, sustain its existence and evolve into complex forms. A few studies have extended this idea by modeling galactic-scale habitable zones (galactic habitable zones) for our Milky Way (MW) and specific elliptical galaxies. However, estimating the habitability for galaxies spanning a wide range of physical properties has so far remained an outstanding issue. Here, we present a “cosmobiological” framework that allows us to sift through the entire galaxy population in the local universe and answer the question, “Which type of galaxy is most likely to host complex life in the cosmos?” Interestingly, the three key astrophysical criteria governing habitability (total mass in stars, total metal mass and ongoing star formation rate) are found to be intricately linked through the “fundamental metallicity relation” as shown by Sloan Digital Sky Survey observations of more than a hundred thousand galaxies in the local universe. Using this relation we show that metal-rich, shapeless giant elliptical galaxies at least twice as massive as the MW (with a tenth of its star formation rate) can potentially host ten thousand times as many habitable (Earth-like) planets, making them the most probable “cradles of life” in the universe.

  10. Photodegradation of malachite green dye catalyzed by Keggin-type polyoxometalates under visible-light irradiation: Transition metal substituted effects

    NASA Astrophysics Data System (ADS)

    Liu, Chun-Guang; Zheng, Ting; Liu, Shuang; Zhang, Han-Yu

    2016-04-01

    In the present paper, Keggin-type polyoxometalates (POMs) (NH4)3[PW12O40] and its mono-transition-metal-substituted species (NH4)5[{PW11O39}MII(H2O)] (M = Mn, Fe, Co, Ni, Cu, Zn) have been synthesized and used as photocatalyst to activate O2 for the degradation of dye molecule under visible-light irradiation. Because of the strong adsorption on the surface of POM catalyst, malachite green (MG) molecule was employed as a molecular probe to test their photocatalytic activity. The photodegradation study shows that introduction of transition metal ion leads to an increase in the degradation of MG in the following order: Mn < Fe < Co < [PW12O40]3- < Ni < Cu < Zn, which indicates that the photocatalytic activity of these POMs is sensitive to the transition metal substituted effects. Electronic structure analysis based on the density functional theory calculations shows that a moderate decrease of oxidizing ability of POM catalyst may improve the photocatalytic activity in the degradation of dye molecule under visible-light irradiation. Meanwhile, intermediate products about the photocatalytic oxidation of MG molecule were proposed on the basis of gas chromatograph mass spectrometer analysis.

  11. Interface metallization and electrical characterization of Ta-Pt multilayers on n-type SiC

    NASA Astrophysics Data System (ADS)

    Yang, H.; Peng, T. H.; Wang, W. J.; Wang, W. Y.; Chen, X. L.

    2008-12-01

    A multilayered metallization Ta/Pt/Ta has been developed for obtaining low resistance ohmic contact to n-type SiC. The electrical, chemical and microstructural properties of the contacts are studied. It is observed that the conducting behavior is rectifying in the as-deposited state, whereas becomes ohmic upon annealing above 900 °C for 5 min in an Ar ambient, resulting in a typical specific contact resistance as low as 10 -4 Ω cm 2 range corresponding to a doping level of 2 × 10 18 cm -3. The Auger electron spectroscopy (AES) and X-ray diffraction analysis results indicate that platinum atoms migrate towards SiC to form platinum silicides in intimate contact with SiC substrate. While the C atoms released from the SiC interface interact with out-diffused Ta atoms to form TaC at the contact surface. The addition of Ta into the Pt metallization scheme serves to reduce the residual carbon left behind from SiC dissociation and Pt-silicides formation, thus could lead to improvement of the thermal and electrical stability. Ta/Pt/Ta metallization on n-SiC is an effective method to realize ohmic contact.

  12. Generation of highly N-type, defect passivated transition metal oxides using plasma fluorine insertion

    SciTech Connect

    Baker, L. Robert; Seo, Hyungtak; Hervier, Antoine; Somorjai, Gabor A.

    2016-04-12

    A new composition of matter is disclosed wherein oxygen vacancies in a semiconducting transition metal oxide such as titanium dioxide are filled with a halogen such as Fluorine, whereby the conductivity of the composition is greatly enhanced, while at the same time the chemical stability of the composition is greatly improved. Stoichiometric titanium dioxide having less than 3 % oxygen vacancies is subject to fluorine insertion such that oxygen vacancies are filled, limited amounts of fluorine replace additional oxygen atoms and fluorine interstitially inserts into the body of the TiO.sub.2 composition.

  13. INVESTIGATING THE POTENTIAL DILUTION OF THE METAL CONTENT OF HOT GAS IN EARLY-TYPE GALAXIES BY ACCRETED COLD GAS

    SciTech Connect

    Su, Yuanyuan; Irwin, Jimmy A.

    2013-03-20

    The measured emission-weighted metal abundance of the hot gas in early-type galaxies has been known to be lower than theoretical expectations for 20 years. In addition, both X-ray luminosity and metal abundance vary significantly among galaxies of similar optical luminosities. This suggests some missing factors in the galaxy evolution process, especially the metal enrichment process. With Chandra and XMM-Newton, we studied 32 early-type galaxies (kT {approx}< 1 keV) covering a span of two orders of L{sub X,gas}/L{sub K} to investigate these missing factors. Contrary to previous studies that X-ray faint galaxies show extremely low Fe abundance ({approx}0.1 Z{sub Sun }), nearly all galaxies in our sample show an Fe abundance at least 0.3 Z{sub Sun }, although the measured Fe abundance difference between X-ray faint and X-ray bright galaxies remains remarkable. We investigated whether this dichotomy of hot gas Fe abundances can be related to the dilution of hot gas by mixing with cold gas. With a subset of 24 galaxies in this sample, we find that there is virtually no correlation between hot gas Fe abundances and their atomic gas content, which disproves the scenario that the low metal abundance of X-ray faint galaxies might be a result of the dilution of the remaining hot gas by pristine atomic gas. In contrast, we demonstrate a negative correlation between the measured hot gas Fe abundance and the ratio of molecular gas mass to hot gas mass, although it is unclear what is responsible for this apparent anti-correlation. We discuss several possibilities including that externally originated molecular gas might be able to dilute the hot gas metal content. Alternatively, the measured hot gas Fe abundance may be underestimated due to more complex temperature and abundance structures and even a two-temperature model might be insufficient to reflect the true value of the emission weighted mean Fe abundance.

  14. Rajkonkoski gold-telluride ore occurrence: A new high prospective type of complex noble metal mineralization in the Karelian Proterozoic

    NASA Astrophysics Data System (ADS)

    Ivashchenko, V. I.; Sundblad, K.; Toritsin, A. N.; Golubev, A. I.; Lavrov, O. B.

    2008-11-01

    The Rajkonkoski ore occurrence is located within the region of the Karelian craton (AR2) and the Svecofennian folded belt (PR1) conjugation. It is presented by quartz-carbonate veins in metadoleriles and a zone of brecciation, crumple, and silification of carbonaceous shales within the volcanites of the Soanlakhtinsky suite (PR1). Ore mineralization in black shales and quartz veins has features of genetic similarity presenting different levels of the ore system controlled by different range strike-slip fault dislocations. At the Rajkonkoski ore occurrence, 41 ore minerals have been identified: 12 tellurides (native tellurium, hedleyite, pilsenite, tsumoite, tellurobismuthite, hessite, stuetzite, radclidzhite, joseite-B, altaite, volynskite, petzite); 4 bismuth-tellurides of the following compositions Bi3Te, Bi3Te2, BiTe4, PbBiTe; 3 selenides (clausthalite, tellurolaitakarite, native selenium); and 12 native metals (gold, silver, electrum, copper, iron, lead, tin, bismuth, osmiridium). The contents of the main ore minerals in places exceed 10%, and the concentrations of elements reach as follows: Cu and Pb, 5%; Zn, Bi, 1%; Se, 219 ppm; Te, 171 ppm; Sb, 3 ppm; As, 5 ppm; Ag, >0.1%; Au, 35.28 ppm. Ore mineralization is formed during the temperature interval from 550°C up to <170oC in the conditions of high activity of Se and Te, and beginning from medium temperatures (>300°C) complete miscibilities galenite-clausthalite and galenite-altaite are observed. In aggregate with a wide temperature interval (>400°C) of ore process evolution and mineral specia variety of telluride and native metal mineralizations, the original “torsion” of different temperature mineralizations makes it possible to determine the affiliation of the Rajkonkoski ore occurrence to the xenothermal type deposits or epithermal “alkaline,” gold-telluride A-type characterized by a close connection with magmatism of increased alkalinity and the original geochemical (Te-V-F) and mineral

  15. Horizontal Gene Transfer of PIB-Type ATPases among Bacteria Isolated from Radionuclide- and Metal-Contaminated Subsurface Soils

    PubMed Central

    Martinez, Robert J.; Wang, Yanling; Raimondo, Melanie A.; Coombs, Jonna M.; Barkay, Tamar; Sobecky, Patricia A.

    2006-01-01

    Aerobic heterotrophs were isolated from subsurface soil samples obtained from the U.S. Department of Energy's (DOE) Field Research Center (FRC) located at Oak Ridge, Tenn. The FRC represents a unique, extreme environment consisting of highly acidic soils with cooccurring heavy metals, radionuclides, and high nitrate concentrations. Four hundred isolates obtained from contaminated soil were assayed for heavy metal resistance, and a smaller subset was assayed for tolerance to uranium. The vast majority of the isolates were gram-positive bacteria and belonged to the high-G+C- and low-G+C-content genera Arthrobacter and Bacillus, respectively. Genomic DNA from a randomly chosen subset of 50 Pb-resistant (Pbr) isolates was amplified with PCR primers specific for PIB-type ATPases (i.e., pbrA/cadA/zntA). A total of 10 pbrA/cadA/zntA loci exhibited evidence of acquisition by horizontal gene transfer. A remarkable dissemination of the horizontally acquired PIB-type ATPases was supported by unusual DNA base compositions and phylogenetic incongruence. Numerous Pbr PIB-type ATPase-positive FRC isolates belonging to the genus Arthrobacter tolerated toxic concentrations of soluble U(VI) (UO22+) at pH 4. These unrelated, yet synergistic, physiological traits observed in Arthrobacter isolates residing in the contaminated FRC subsurface may contribute to the survival of the organisms in such an extreme environment. This study is, to the best of our knowledge, the first study to report broad horizontal transfer of PIB-type ATPases in contaminated subsurface soils and is among the first studies to report uranium tolerance of aerobic heterotrophs obtained from the acidic subsurface at the DOE FRC. PMID:16672448

  16. Weak effect of metal type and ica genes on staphylococcal infection of titanium and stainless steel implants.

    PubMed

    Hudetz, D; Ursic Hudetz, S; Harris, L G; Luginbühl, R; Friederich, N F; Landmann, R

    2008-12-01

    Currently, ica is considered to be the major operon responsible for staphylococcal biofilm. The effect of biofilm on susceptibility to staphylococcal infection of different implant materials in vivo is unclear. The interaction of ica-positive (wild-type (WT)) and ica-negative (ica(-)) Staphylococcus aureus and Staphylococcus epidermidis strains with titanium and both smooth and rough stainless steel surfaces was studied by scanning electron microscopy in vitro and in a mouse tissue cage model during 2 weeks following perioperative or postoperative inoculation in vivo. In vitro, WT S. epidermidis adhered equally and more strongly than did WT S. aureus to all materials. Both WT strains, but not ica(-) strains, showed multilayered biofilm. In vivo, 300 CFUs of WT and ica(-)S. aureus led, in all metal cages, to an infection with a high level of planktonic CFUs and only 0.89% adherent CFUs after 8 days. In contrast, 10(6) CFUs of the WT and ica(-) strains were required for postoperative infection with S. epidermidis. In all metal types, planktonic numbers of S. epidermidis dropped to <100 WT, and adherent CFUs were low in WT-infected cages and absent in ica(-)-infected cages after 14 days. Perioperative S. epidermidis inoculation resulted in slower clearance than postoperative inoculation, and in titanium cages adherent WT bacteria survived in higher numbers than ica(-) bacteria. In conclusion, the metal played a minor role in susceptibility to and persistence of staphylococcal infection; the presence of ica genes had a strong effect on biofilm in vitro and a weak effect in vivo; and S. epidermidis was more pathogenic when introduced during implantation than after implantation.

  17. Formation of Tsai-type 1/1 approximants in In-Pd-RE (RE: rare earth metal) alloys

    NASA Astrophysics Data System (ADS)

    So, Yeong-Gi; Saruhashi, Fukuaki; Kimoto, Koji; Tamura, Ryuji; Edagawa, Keiichi

    2014-09-01

    The formation of the 1/1 crystal approximant phase (1/1 phase) to the icosahedral phase (i phase) in In-Pd-RE (RE: rare earth metal) systems has been investigated. A new series of 1/1 phases were found in In53Pd33RE14 (RE; Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm) alloys. For Y, Sm, Gd, Tb, Dy, and Ho, the 1/1 phases were found in annealed alloys, indicating that they are thermodynamically stable. The atomic structure of the 1/1 phases was directly observed by high-angle annular dark-field imaging performed via scanning transmission electron microscopy, revealing that the 1/1 phases consisted of a periodic arrangement of Tsai-type icosahedral clusters. Further, the atomic size effect on i phase formation, as well as formation conditions previously reported for other Tsai-type i and 1/1 phases were examined. It was found that the ratio of the atomic radius of base metals such as In and Pd affects i phase formation. Moreover, the appropriate range of the radius ratio for i phase formation was narrower than that for 1/1 phase formation. Present address: Department of Materials Science and Engineering, Akita University, Tegata Gakuen-machi, Akita-shi, Akita 010-8502, Japan

  18. New p-type absorber films formed by interfacial diffusion in chemically deposited metal chalcogenide multilayer films

    SciTech Connect

    Nair, P.K.; Nair, M.T.S.; Hu, H.; Huang, L.; Zingaro, R.A.; Meyers, E.A.

    1995-12-31

    The authors report on new p-type ternary metal chalcogenide absorber films for possible solar energy applications. The films are formed by interfacial diffusion in chemically deposited multilayer films: CuS films (0.15--0.6 {micro}m) deposited on ZnS, PbS or Bi{sub 2}S{sub 3} films ({approx} 0.1 {micro}m). The diffusion takes place during annealing at temperatures above 150 C and is shown in the XPS depth profile spectra of the annealed samples: metal atoms (Zn, Pb or Bi) of the underlying substrate films are detected at the surface layers after the annealing. The peculiarity of the multilayer films is that they show almost constant sheet resistance upon further annealing until 350 C. The sheet resistances are in the range of 20--100 {Omega} suggesting conductivities (p-type) of up to 400 {Omega}{sup {minus}1}. In the case of CuS on Bi{sub 2}S{sub 3} films, the formation of a compound, Cu{sub 3}BiS{sub 3}, is clearly detected. These have applications for solar cells.

  19. Delay times and jitter in triggered vacuum spark gaps using metal vapor and surface flashover types of triggers

    SciTech Connect

    Voshall, R.E.; Bhasavanich, D.; Gorman, J.G.; Buttram, M.T.

    1985-01-01

    Triggered vacuum spark gap experiments have been performed in a demountable arc chamber with a pressure of 10/sup -2/ to 10/sup -4/ mtorr. Planar copper electrodes were used in which one electrode contained the trigger. Metal vapor spark triggers and surface flash-over types of triggers were explored. We have measured the delay time between the trigger breakdown and the conduction of the main gap, and the jitter in this time, as a function of main gap voltage ranging from 3 to 20 kV and main gap separations of 13 to 19 mm. Main gap current following breakdown ranged from 3 to 15 kA. Using the metal vapor trigger, delay times as long as 500 ns were observed for a gap field of 500 V/mm while using the surface flashover type of triggers, delay times of 300 ns were observed for a similar main gap field strength. When the trigger was in the cathode electrode and the trigger was pulsed negatively, the operation of the gap was more consistent and the delay times were observed to increase with main gap voltage. The experimental data have been interpreted on the basis of plasma expansion models.

  20. Metal Emission Lines as Diagnostic Tools for Shock Waves in Outer Atmospheres of M-type Mira Stars

    NASA Astrophysics Data System (ADS)

    Richter, He.; Sedlmayr, E.; Wood, P. R.

    One way to reveal the thermo- and hydrodynamical conditions in M-type Mira atmospheres is to study the various emission lines which are emitted behind a shock front and can be observed over a substantial portion of the pulsation period. Analysing a time-resolved series of these emission lines offers the possibility to determine these conditions in different atmospheric layers influenced by the passing shock wave. In particular, the metal emission lines are a diagnostic tool to probe the hydrodynamical conditions of the outer, dust-forming layers of the atmosphere, because they appear late in the pulsation cycle when the shock wave has reached these layers. We present quantitive data on radial velocities, shapes, widths and fluxes of metal emission lines obtained by spectral observations in the optical wavelength region for a sample of six M-type Miras (periods 281-389 days), namely R Aql, RR Sco, R Car, R Leo, S Scl and R Hya (cf. Richter & Wood 2001, A&A 369, 1027-1047). Because of the multiple phase coverage of our observations, the data shows the history of the shock as it emerges through the deep photosphere and then moves out through the atmosphere. The observations are analysed and discussed with regard to the atmospheric conditions.

  1. Winds of low-metallicity OB-type stars: HST-COS spectroscopy in IC 1613

    SciTech Connect

    Garcia, Miriam; Najarro, Francisco; Herrero, Artemio; Urbaneja, Miguel Alejandro

    2014-06-10

    We present the first quantitative ultraviolet spectroscopic analysis of resolved OB stars in IC 1613. Because of its alleged very low metallicity (≲1/10 Z {sub ☉}, from H II regions), studies in this Local Group dwarf galaxy could become a significant step forward from the Small Magellanic Cloud (SMC) toward the extremely metal-poor massive stars of the early universe. We present HST-COS data covering the ∼1150-1800 Å wavelength range with resolution R ∼ 2500. We find that the targets do exhibit wind features, and these are similar in strength to SMC stars. Wind terminal velocities were derived from the observed P Cygni profiles with the Sobolev plus Exact Integration method. The v {sub ∞}-Z relationship has been revisited. The terminal velocity of IC 1613 O stars is clearly lower than Milky Way counterparts, but there is no clear difference between IC 1613 and SMC or LMC analog stars. We find no clear segregation with host galaxy in the terminal velocities of B-supergiants, nor in the v {sub ∞}/v {sub esc} ratio of the whole OB star sample in any of the studied galaxies. Finally, we present the first evidence that the Fe-abundance of IC 1613 OB stars is similar to the SMC, which is in agreement with previous results on red supergiants. With the confirmed ∼1/10 solar oxygen abundances of B-supergiants, our results indicate that IC 1613's α/Fe ratio is sub-solar.

  2. G -type antiferromagnetic order in the metallic oxide LaC u3C r4O12

    NASA Astrophysics Data System (ADS)

    Saito, Takashi; Zhang, Shoubao; Khalyavin, Dmitry; Manuel, Pascal; Attfield, J. Paul; Shimakawa, Yuichi

    2017-01-01

    The A -site-ordered cubic perovskite LaC u3C r4O12 , where a partial Cu-Cr intersite charge transfer transition occurs at TCT=220 K , was found to be an unconventional metallic and G -type antiferromagnetic oxide. Neutron powder diffraction revealed a G -type antiferromagnetic ordering at the Cr sites and no ordered moments at the Cu sites. Ab initio electronic structure calculations revealed that the narrowing of the Cr-O-Cr bands due to heavy tilting of the Cr O6 octahedra and the strong hybridization of the Cu -3 d ,Cr -3 d , and O - 2 p orbitals near the Fermi level give an unusual electronic structure in the vicinity of a localized-electron regime. The G -type magnetic structure is primarily stabilized by nearest-neighbor antiferromagnetic superexchange interactions of the near-localized Cr spins. The ferromagnetic {1 1 1 } layers of the G -type antiferromagnetic Cr-spin sublattice allow the spin-polarized electron transfer through the strongly hybridized Cu orbitals.

  3. Investigation of long term stability in metal hydrides

    NASA Technical Reports Server (NTRS)

    Marmaro, Roger W.; Lynch, Franklin E.; Chandra, Dhanesh; Lambert, Steve; Sharma, Archana

    1991-01-01

    It is apparent from the literature and the results of this study that cyclic degradation of AB(5) type metal hydrides varies widely according to the details of how the specimens are cycled. The Rapid Cycle Apparatus (RCA) used produced less degradation in 5000 to 10000 cycles than earlier work with a Slow Cycle Apparatus (SCA) produced in 1500 cycles. Evidence is presented that the 453 K (356 F) Thermal Aging (TA) time spent in the saturated condition causes hydride degradation. But increasing the cooling (saturation) period in the RCA did not greatly increase the rate of degradation. It appears that TA type degradation is secondary at low temperatures to another degradation mechanism. If rapid cycles are less damaging than slow cycles when the saturation time is equal, the rate of hydriding/dehydriding may be an important factor. The peak temperatures in the RCA were about 30 C lower than the SCA. The difference in peak cycle temperatures (125 C in the SCA, 95 C in RCA) cannot explain the differences in degradation. TA type degradation is similar to cyclic degradation in that nickel peaks and line broadening are observed in X ray diffraction patterns after either form of degradation.

  4. Transition-metal-free Sonogashira-type cross-coupling of alkynes with fluoroarenes.

    PubMed

    Jin, Guanyi; Zhang, Xuxue; Cao, Song

    2013-06-21

    A novel, inexpensive, and efficient palladium-, copper-, ligand-, and amine-free Sonogashira-type cross-coupling reaction of terminal alkynes with unreactive aryl fluorides in the presence of sodium, sodium methoxide, and calcium hydroxide under the assistance of a Grignard reagent was developed. A plausible mechanism was also suggested.

  5. Metal nanoparticle assisted polymerase chain reaction for strain typing of Salmonella Typhi.

    PubMed

    Rehman, Asma; Sarwar, Yasra; Raza, Zulfiqar Ali; Hussain, Syed Zajif; Mustafa, Tanveer; Khan, Waheed S; Ghauri, Muhammad Afzal; Haque, Abdul; Hussain, Irshad

    2015-11-07

    Salmonella enterica serotype Typhi (S. Typhi) is the causative agent of typhoid fever and remains a major health threat in most of the developing countries. The prompt diagnosis of typhoid directly from the patient's blood requires high level of sensitivity and specificity. Some of us were the first to report PCR based diagnosis of typhoid. This approach has since then been reported by many scientists using different genomic targets. Since the number of bacteria circulating in the blood of a patient can be as low as 0.3 cfu ml(-1), there is always a room for improvement in diagnostic PCR. In the present study, the role of different types of nanoparticles was investigated to improve the existing PCR based methods for diagnosis and strain typing of S. Typhi (targeting Variable Number of Tandem Repeats [VNTR]) by using optimized PCR systems. Three different types of nanoparticles were used i.e., citrate stabilized gold nanoparticles, rhamnolipid stabilized gold and silver nanoparticles, and magnetic iron oxide nanoparticles. The non-specific amplification was significantly reduced in VNTR typing when gold and silver nanoparticles were used in an appropriate concentration. More importantly, the addition of nanoparticles decreased the non-specificity to a significant level in the case of multiplex PCR thus further validating the reliability of PCR for the diagnosis of typhoid.

  6. Uncovering the transmembrane metal binding site of the novel bacterial major facilitator superfamily-type copper importer CcoA

    SciTech Connect

    Khalfaoui-Hassani, Bahia; Verissimo, Andreia F.; Koch, Hans -Georg; Daldal, Fevzi

    2016-01-19

    In this study, uptake and trafficking of metals and their delivery to their respective metalloproteins are important processes. Cells need precise control of each step to avoid exposure to excessive metal concentrations and their harmful consequences. Copper (Cu) is a required micronutrient used as a cofactor in proteins. However, in large amounts, it can induce oxidative damage; hence, Cu homeostasis is indispensable for cell survival. Biogenesis of respiratory heme-Cu oxygen (HCO) reductases includes insertion of Cu into their catalytic subunits to form heme-Cu binuclear centers. Previously, we had shown that CcoA is a major facilitator superfamily (MFS)-type bacterial Cu importer required for biogenesis of cbb3-type cytochromecoxidase (cbb3-Cox). Here, using Rhodobacter capsulatus, we focused on the import and delivery of Cu to cbb3-Cox. By comparing the CcoA amino acid sequence with its homologues from other bacterial species, we located several well-conserved Met, His, and Tyr residues that might be important for Cu transport. We determined the topology of the transmembrane helices that carry these residues to establish that they are membrane embedded, and substituted for them amino acids that do not ligand metal atoms. Characterization of these mutants for their uptake of radioactive64Cu and cbb3-Cox activities demonstrated that Met233 and His261 of CcoA are essential and Met237 and Met265 are important, whereas Tyr230 has no role for Cu uptake or cbb3-Cox biogenesis. These findings show for the first time that CcoA-mediated Cu import relies on conserved Met and His residues that could act as metal ligands at the membrane-embedded Cu binding domain of this transporter.

  7. Design of ternary alkaline-earth metal Sn(II) oxides with potential good p-type conductivity

    SciTech Connect

    Du, Mao -Hua; Singh, David J.; Zhang, Lijun; Li, Yuwei; Xu, Qiaoling; Ma, Yanming; Zheng, Weitao

    2016-04-19

    Oxides with good p-type conductivity have been long sought after to achieve high performance all-oxide optoelectronic devices. Divalent Sn(II) based oxides are promising candidates because of their rather dispersive upper valence bands caused by the Sn-5s/O-2p anti-bonding hybridization. There are so far few known Sn(II) oxides being p-type conductive suitable for device applications. Here, we present via first-principles global optimization structure searches a material design study for a hitherto unexplored Sn(II)-based system, ternary alkaline-earth metal Sn(II) oxides in the stoichiometry of MSn2O3 (M = Mg, Ca, Sr, Ba). We identify two stable compounds of SrSn2O3 and BaSn2O3, which can be stabilized by Sn-rich conditions in phase stability diagrams. Their structures follow the Zintl behaviour and consist of basic structural motifs of SnO3 tetrahedra. Unexpectedly they show distinct electronic properties with band gaps ranging from 1.90 (BaSn2O3) to 3.15 (SrSn2O3) eV, and hole effective masses ranging from 0.87 (BaSn2O3) to above 6.0 (SrSn2O3) m0. Further exploration of metastable phases indicates a wide tunability of electronic properties controlled by the details of the bonding between the basic structural motifs. Lastly, this suggests further exploration of alkaline-earth metal Sn(II) oxides for potential applications requiring good p-type conductivity such as transparent conductors and photovoltaic absorbers.

  8. Design of ternary alkaline-earth metal Sn(II) oxides with potential good p-type conductivity

    DOE PAGES

    Du, Mao -Hua; Singh, David J.; Zhang, Lijun; ...

    2016-04-19

    Oxides with good p-type conductivity have been long sought after to achieve high performance all-oxide optoelectronic devices. Divalent Sn(II) based oxides are promising candidates because of their rather dispersive upper valence bands caused by the Sn-5s/O-2p anti-bonding hybridization. There are so far few known Sn(II) oxides being p-type conductive suitable for device applications. Here, we present via first-principles global optimization structure searches a material design study for a hitherto unexplored Sn(II)-based system, ternary alkaline-earth metal Sn(II) oxides in the stoichiometry of MSn2O3 (M = Mg, Ca, Sr, Ba). We identify two stable compounds of SrSn2O3 and BaSn2O3, which can bemore » stabilized by Sn-rich conditions in phase stability diagrams. Their structures follow the Zintl behaviour and consist of basic structural motifs of SnO3 tetrahedra. Unexpectedly they show distinct electronic properties with band gaps ranging from 1.90 (BaSn2O3) to 3.15 (SrSn2O3) eV, and hole effective masses ranging from 0.87 (BaSn2O3) to above 6.0 (SrSn2O3) m0. Further exploration of metastable phases indicates a wide tunability of electronic properties controlled by the details of the bonding between the basic structural motifs. Lastly, this suggests further exploration of alkaline-earth metal Sn(II) oxides for potential applications requiring good p-type conductivity such as transparent conductors and photovoltaic absorbers.« less

  9. Surface Charge Transfer Doping via Transition Metal Oxides for Efficient p-Type Doping of II-VI Nanostructures.

    PubMed

    Xia, Feifei; Shao, Zhibin; He, Yuanyuan; Wang, Rongbin; Wu, Xiaofeng; Jiang, Tianhao; Duhm, Steffen; Zhao, Jianwei; Lee, Shuit-Tong; Jie, Jiansheng

    2016-11-22

    Wide band gap II-VI nanostructures are important building blocks for new-generation electronic and optoelectronic devices. However, the difficulty of realizing p-type conductivity in these materials via conventional doping methods has severely handicapped the fabrication of p-n homojunctions and complementary circuits, which are the fundamental components for high-performance devices. Herein, by using first-principles density functional theory calculations, we demonstrated a simple yet efficient way to achieve controlled p-type doping on II-VI nanostructures via surface charge transfer doping (SCTD) using high work function transition metal oxides such as MoO3, WO3, CrO3, and V2O5 as dopants. Our calculations revealed that these oxides were capable of drawing electrons from II-VI nanostructures, leading to accumulation of positive charges (holes injection) in the II-VI nanostructures. As a result, Fermi levels of the II-VI nanostructures were shifted toward the valence band regions after surface modifications, along with the large enhancement of work functions. In situ ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy characterizations verified the significant interfacial charge transfer between II-VI nanostructures and surface dopants. Both theoretical calculations and electrical transfer measurements on the II-VI nanostructure-based field-effect transistors clearly showed the p-type conductivity of the nanostructures after surface modifications. Strikingly, II-VI nanowires could undergo semiconductor-to-metal transition by further increasing the SCTD level. SCTD offers the possibility to create a variety of electronic and optoelectronic devices from the II-VI nanostructures via realization of complementary doping.

  10. Factorial Kriging analysis and sources of heavy metals in soils of different land-use types in the Yangtze River Delta of Eastern China.

    PubMed

    Zhou, Jie; Feng, Ke; Li, Yinju; Zhou, Yang

    2016-08-01

    The objectives of this study are to analyse the pollution status and spatial correlation of soil heavy metals and identify natural and anthropogenic sources of these heavy metals at different spatial scales. Two hundred and twenty-four soil samples (0-20 cm) were collected and analysed for eight heavy metals (Cd, Hg, As, Cu, Pb, Cr, Zn and Ni) in soils of different land-use types in the Yangtze River Delta of Eastern China. The multivariate methods and factorial Kriging analysis were used to achieve the research objectives. The results indicated that the human and natural effects of different land-use types on the contents of soil heavy metals were different. The Cd, Hg, Cu, Pb and Zn in soils of industrial area were affected by human activities, and the pollution level of these heavy metals in this area was moderate. The Pb in soils of traffic area was affected by human activities, and eight heavy metals in soils of residential area and farmland area were affected by natural factor. The ecological risk status of eight heavy metals in soils of the whole study area was light. The heavy metals in soils showed three spatial scales (nugget effect, short range and long range). At the nugget effect and short range scales, the Cd, Hg, Cu, Pb and Zn in soils were affected by human and natural factors. At three spatial scales, the As, Cr and Ni in soils were affected by soil parent materials.

  11. Comparison of elastic properties of open-cell metallic biomaterials with different unit cell types.

    PubMed

    Hedayati, Reza; Sadighi, Mojtaba; Mohammadi-Aghdam, Mohammad; Hosseini-Toudeshky, Hossein

    2017-02-06

    Additive manufacturing techniques have made it possible to create open-cell porous structures with arbitrary micro-geometrical characteristics. Since a wide range of micro-geometrical features is available for making an implant, having a comprehensive knowledge of the mechanical response of cellular structures is very useful. In this study, finite element simulations have been carried out to investigate the effect of structure unit cell type (cube, rhombic dodecahedron, Kelvin, Weaire-Phelan, and diamond), cross-section type (circular, square, and triangular), strut length, and relative density on the Young's modulus, shear modulus, yield stress, shear yield stress, and Poisson's ratio of open-cell tessellated cellular structures. It was desired to see whether or not and to what extent each of the aforementioned parameters affect the mechanical properties of a porous structure. It was seen that the strut cross-section type does not have a considerable effect on the structure Young's modulus while its effect on the structure yield stress is significant. The strut length was not effective on the mechanical properties if the relative density was kept constant. It was also observed that the structure unit cell type and relative density have a considerable effect on the elastic properties. The highest and the lowest stiffness and strength belonged to the cube and diamond unit cell types, respectively. The rhombic dodecahedron structure with circular cross-section had a high yielding strength (second among all the cases) while its Young's modulus was relatively low. Therefore, it is the best choice for applications with low stiffness requirements, such as biomedical implants. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017.

  12. Exploration of mid-temperature alkali-metal-ion extraction route using PTFE (AEP): transformation of α-NaFeO2-type layered oxides into rutile-type binary oxides.

    PubMed

    Ozawa, Tadashi C; Sasaki, Takayoshi

    2012-07-02

    Alkali-metal-ion extraction reactions using poly(tetrafluoroethylene) (PTFE; AEP reactions) were performed on two kinds of α-NaFeO(2)-type layered compounds: Na(0.68)(Li(0.68/3)Ti(1-0.68/3))O(2) and K(0.70)(Li(0.70/3)Sn(1-0.70/3))O(2). At 400 °C in flowing argon, these layered compounds were reacted with PTFE. By these reactions, alkali-metal ions in the layered compounds were successfully extracted, and TiO(2) and SnO(2) with rutile-type structure were formed. The structural similarity between the alkali-metal-ion-extracted layered compounds and the binary metal oxide products in these unique alkali-metal-ion extraction reactions was interpreted in terms of their interatomic distance distribution by atomic pair distribution function analysis. The results of this study indicate that PTFE is an effective agent to extract alkali-metal ions from layered compounds, and AEP reaction is not limited to the previously reported γ-FeOOH-type layered titania K(0.8)(Li(0.27)Ti(1.73))O(4), but is also applicable to other layered titania and other non-titanium-based layered metal oxides. Therefore, it was clarified that AEP reactions are widely applicable routes to prepare various compounds, including those that are difficult to synthesize by other reactions.

  13. Investigation of heat and mass transfer process in metal hydride hydrogen storage reactors, suitable for a solar powered water pump system

    NASA Astrophysics Data System (ADS)

    Coldea, I.; Popeneciu, G.; Lupu, D.; Misan, I.; Blanita, G.; Ardelean, O.

    2012-02-01

    The paper analyzes heat and mass transfer process in metal hydride hydrogen storage systems as key element in the development of a solar powered pump system. Hydrogen storage and compression performance of the developed reactors are investigated according to the type of metal alloys, the metal hydride bed parameters and system operating conditions. To reach the desired goal, some metal hydride from groups AB5 and AB2 were synthesized and characterized using elements substitution for tailoring their properties: reversible hydrogen absorption capacity between the hydrogen absorption and desorption pressures at equilibrium at small temperature differences. For the designed hydrogen storage reactors, a new technical solution which combines the effective increase of the thermal conductivity of MH bed and good permeability to hydrogen gas circulation, was implemented and tested. The results permitted us to develop a heat engine with metal hydride, the main element of the functional model of a heat operated metal hydride based water pumping system using solar energy. This is a free energy system able to deliver water, at a convenience flow and pressure, in remote places without conventional energy access.

  14. Effect of reinforcement type and porosity on strength of metal matrix composite

    NASA Astrophysics Data System (ADS)

    Kulkarni, S. G.; Lal, Achchhe; Menghani, J. V.

    2016-05-01

    In the present work, experimental investigation and the numerical analysis are carried out for strength analysis of A356 alloy matrix composites reinforced with alumina, fly ash and hybrid particle composites. The combined strengthening effect of load bearing, Hall-Petch, Orowan, coefficient of thermal expansion mismatch and elastic modulus mismatch is studied for predicting accurate uniaxial stress-strain behavior of A356 based alloy matrix composite. The unit cell micromechanical approach and nine noded isoparametric finite element analysis (FEA) is used to investigate the yield failure load by considering material defect of porosity as fabrication errors in particulate composite. The Ramberg-Osgood approach is considered for the linear and nonlinear relationship between stress and strain of A356 based metal matrix composites containing different amounts of fly ash and alumina reinforcing particles. A numerical analysis of material porosity on the stress strain behavior of the composite is performed. The literature and experimental results exhibit the validity of this model and confirm the importance of the fly ash as the cheapest and low density reinforcement obtained as a waste by product in thermal power plants.

  15. Composition induced metal-insulator quantum phase transition in the Heusler type Fe2VAl

    NASA Astrophysics Data System (ADS)

    Naka, Takashi; Nikitin, Artem M.; Pan, Yu; de Visser, Anne; Nakane, Takayuki; Ishikawa, Fumihiro; Yamada, Yuh; Imai, Motoharu; Matsushita, Akiyuki

    2016-07-01

    We report the magnetism and transport properties of the Heusler compound Fe2+x V1-x Al at  -0.10  ⩽  x  ⩽  0.20 under pressure and a magnetic field. A metal-insulator quantum phase transition occurred at x  ≈  -0.05. Application of pressure or a magnetic field facilitated the emergence of finite zero-temperature conductivity σ 0 around the critical point, which scaled approximately according to the power law (P  -  P c ) γ . At x  ⩽  -0.05, a localized paramagnetic spin appeared, whereas above the ferromagnetic quantum critical point at x  ≈  0.05, itinerant ferromagnetism was established. At the quantum critical points at x  =  -0.05 and 0.05, the resistivity and specific heat exhibited singularities characteristic of a Griffiths phase appearing as an inhomogeneous electronic state.

  16. Kondo screening in two-dimensional p -type transition-metal dichalcogenides

    NASA Astrophysics Data System (ADS)

    Phillips, Michael; Aji, Vivek

    2017-02-01

    Systems with strong spin-orbit coupling support a number of new phases of matter and novel phenomena. This work focuses on the interplay of spin-orbit coupling and interactions in yielding correlated phenomena in two-dimensional transition-metal dichalcogenides. In particular we explore the physics of Kondo screening resulting from the lack of centrosymmetry, large spin splitting, and spin valley locking in hole-doped systems. The key ingredients are (i) valley-dependent spin-momentum locking perpendicular to the two-dimensional crystal, (ii) a single nondegenerate Fermi surface per valley, and (iii) nontrivial Berry curvature associated with the low-energy bands. The resulting Kondo resonance has a finite-triplet component and nontrivial momentum space structure which facilitates new approaches to both probing and manipulating the correlated state. Using a variational wave function and the numerical renormalization group approaches we study the nature of the Kondo resonance both in the absence and presence of circularly polarized light. The latter induces an imbalance in the population of the two valleys leading to novel magnetic phenomena in the correlated state.

  17. Chemical abundances in early B-type stars. 5: Metal abundances and LTE/NLTE comparison

    NASA Astrophysics Data System (ADS)

    Kilian, J.

    1994-02-01

    Chemical abundances of neon, magnesium, aluminum, sulfur, and iron are derived for a sample of 21 unevolved B-stars in the local field and nearby associations. While aluminum, sulfur, and iron are underabundant in nearly all stars, near solar abundances are found for magnesium and neon. In agreement with earlier results for carbon, nitrogen, oxygen, and silicon (Kilian 1992), the present results show no correlation with surface gravities or evolutionary states, which indicates that the metal abundances reflect the original composition of the interstellar medium. The results are supplemented by a comparison of local thermodynamic equilibrium (LTE) and non-LTE (NLTE) abundances for C, N, O, Si, Mg, and Al. In most cases the differences amount to +/- (0.1-0.2) dex, which slightly exceeds the estimated accuracy of the NLTE abundance determination. However, a clear temperature gradient is evident for most elements, which indicates systematic LTE abundance errors with a maximum amplitude of 0.4 dex between 21 000 K and 31 000 K.

  18. Complexation of Trivalent Metal Cations to Mannuronate Type Alginate Models from a Density Functional Study.

    PubMed

    Menakbi, Chemseddine; Quignard, Francoise; Mineva, Tzonka

    2016-04-21

    Complexation of alginate models, built of β-d-mannuronic units (M) linked by a 1-4 glycosidic bridge, to Al(3+), Sc(3+), Cr(3+), Fe(3+), Ga(3+), and La(3+) cations was studied by applying the quantum chemical density functional theory (DFT) based method. The binding modes and energies were obtained for complexes with one, two, and three truncated alginate chain(s). In all the hydrated structures a monodentate binding mode is established to be the energetically most favored with shorter M(3+)···O(COO(-)) bonds than M(3+)···O(OH) bonds. Coordination bond lengths are found to be specific to each cation and to depend very little on the water in the coordination sphere and on the number of saccharide units used to model an alginate chain. The binding energy tendency Fe(3+) ≈ Cr(3+) > Al(3+) ≈ Ga(3+) ≫ Sc(3+) ≥ La(3+) is not affected by the alginate models, the coordination to water molecules, and the number of chains. A significant covalent contribution that arises predominantly from a charge donation from the carboxylate oxygen to the metal cation was established from the orbital population analysis. An exothermic chain-chain association is predicted by the computed enthalpy variations. A comparison between the structural features of alginate complexation to trivalent and divalent cations is provided and discussed.

  19. P-type conductive amorphous oxides of transition metals from solution processing

    NASA Astrophysics Data System (ADS)

    Li, Jinwang; Kaneda, Toshihiko; Tokumitsu, Eisuke; Koyano, Mikio; Mitani, Tadaoki; Shimoda, Tatsuya

    2012-07-01

    We report a series of solution-processed p-type conductive amorphous Ln-M-O (a-Ln-M-O, where M = Ru, Ir, and Ln is a lanthanide element except Ce) having low resistivities (10-3 to 10-2 Ω cm). These oxides are thermally stable to a high degree, being amorphous up to 800 °C, and processable below 400 °C. Their film surfaces are smooth on the atomic scale, and the process allows patterning simply by direct imprinting without distortion of the pattern after annealing. These properties have high potential for use in printed electronics. The electron configurations of these oxides are apparently different from existing p-type oxides.

  20. Surface multiheme c-type cytochromes from Thermincola potens and implications for respiratory metal reduction by Gram-positive bacteria.

    PubMed

    Carlson, Hans K; Iavarone, Anthony T; Gorur, Amita; Yeo, Boon Siang; Tran, Rosalie; Melnyk, Ryan A; Mathies, Richard A; Auer, Manfred; Coates, John D

    2012-01-31

    Almost nothing is known about the mechanisms of dissimilatory metal reduction by Gram-positive bacteria, although they may be the dominant species in some environments. Thermincola potens strain JR was isolated from the anode of a microbial fuel cell inoculated with anaerobic digester sludge and operated at 55 °C. Preliminary characterization revealed that T. potens coupled acetate oxidation to the reduction of hydrous ferric oxides (HFO) or anthraquinone-2,6-disulfonate (AQDS), an analog of the redox active components of humic substances. The genome of T. potens was recently sequenced, and the abundance of multiheme c-type cytochromes (MHCs) is unusual for a Gram-positive bacterium. We present evidence from trypsin-shaving LC-MS/MS experiments and surface-enhanced Raman spectroscopy (SERS) that indicates the expression of a number of MHCs during T. potens growth on either HFO or AQDS, and that several MHCs are localized to the cell wall or cell surface. Furthermore, one of the MHCs can be extracted from cells with low pH or denaturants, suggesting a loose association with the cell wall or cell surface. Electron microscopy does not reveal an S-layer, and the precipitation of silver metal on the cell surface is inhibited by cyanide, supporting the involvement of surface-localized redox-active heme proteins in dissimilatory metal reduction. These results provide unique direct evidence for cell wall-associated cytochromes and support MHC involvement in conducting electrons across the cell envelope of a Gram-positive bacterium.

  1. Surface multiheme c-type cytochromes from Thermincola potens: Implications for dissimilatory metal reduction by Gram-positive bacteria

    NASA Astrophysics Data System (ADS)

    Carlson, H. K.; Iavarone, A. T.; Gorur, A.; Yeo, B. S.; Tran, R.; Melnyk, R. A.; Mathies, R. A.; Auer, M.; Coates, J. D.

    2011-12-01

    Almost nothing is known about the mechanisms of dissimilatory metal reduction by Gram-positive bacteria, although they have been shown to be the dominant species in some environments. Thermincola potens strain JR was isolated from the anode of a microbial fuel cell inoculated with anaerobic digester sludge and operated at 55 °C. Preliminary characterization revealed that T. potens coupled acetate oxidation to the reduction of hydrous ferric oxides (HFO) or the humic substances analog, anthraquinone-2,6-disulfonate (AQDS). The genome of T. potens was recently sequenced, and the abundance of multiheme c-type cytochromes (MHCs) is unusual for a Gram-positive bacterium. We present evidence from trypsin shaving LC-MS/MS experiments and surface-enhanced Raman spectroscopy (SERS) that indicates the expression of a number of MHCs during T. potens growth on either HFO or AQDS and that several MHCs are localized to the cell wall or cell surface of T. potens. Furthermore, one of the MHCs can be extracted from cells with low pH or denaturants suggesting a loose association with the cell wall or cell surface. Electron microscopy does not reveal an S-layer, and the precipitation of silver metal on the cell surface is inhibited by cyanide, supporting the involvement of surface-localized redox-active heme proteins in dissimilatory metal reduction. These results are the first direct evidence for cell-wall associated cytochromes and MHC involvement in conducting electrons across the cell envelope of a Gram-positive bacterium.

  2. Influence of substrate metal alloy type on the properties of hydroxyapatite coatings deposited using a novel ambient temperature deposition technique.

    PubMed

    Barry, J N; Cowley, A; McNally, P J; Dowling, D P

    2014-03-01

    Hydroxyapatite (HA) coatings are applied widely to enhance the level of osteointegration onto orthopedic implants. Atmospheric plasma spray (APS) is typically used for the deposition of these coatings; however, HA crystalline changes regularly occur during this high-thermal process. This article reports on the evaluation of a novel low-temperature (<47°C) HA deposition technique, called CoBlast, for the application of crystalline HA coatings. To-date, reports on the CoBlast technique have been limited to titanium alloy substrates. This study addresses the suitability of the CoBlast technique for the deposition of HA coatings on a number of alternative metal alloys utilized in the fabrication of orthopedic devices. In addition to titanium grade 5, both cobalt chromium and stainless steel 316 were investigated. In this study, HA coatings were deposited using both the CoBlast and the plasma sprayed techniques, and the resultant HA coating and substrate properties were evaluated and compared. The CoBlast-deposited HA coatings were found to present similar surface morphologies, interfacial properties, and composition irrespective of the substrate alloy type. Coating thickness however displayed some variation with the substrate alloy, ranging from 2.0 to 3.0 μm. This perhaps is associated with the electronegativity of the metal alloys. The APS-treated samples exhibited evidence of both coating, and significantly, substrate phase alterations for two metal alloys; titanium grade 5 and cobalt chrome. Conversely, the CoBlast-processed samples exhibited no phase changes in the substrates after depositions. The APS alterations were attributed to the brief, but high-intensity temperatures experienced during processing.

  3. Recent progress in high performance and reliable n-type transition metal oxide-based thin film transistors

    NASA Astrophysics Data System (ADS)

    Kwon, Jang Yeon; Kyeong Jeong, Jae

    2015-02-01

    This review gives an overview of the recent progress in vacuum-based n-type transition metal oxide (TMO) thin film transistors (TFTs). Several excellent review papers regarding metal oxide TFTs in terms of fundamental electron structure, device process and reliability have been published. In particular, the required field-effect mobility of TMO TFTs has been increasing rapidly to meet the demands of the ultra-high-resolution, large panel size and three dimensional visual effects as a megatrend of flat panel displays, such as liquid crystal displays, organic light emitting diodes and flexible displays. In this regard, the effects of the TMO composition on the performance of the resulting oxide TFTs has been reviewed, and classified into binary, ternary and quaternary composition systems. In addition, the new strategic approaches including zinc oxynitride materials, double channel structures, and composite structures have been proposed recently, and were not covered in detail in previous review papers. Special attention is given to the advanced device architecture of TMO TFTs, such as back-channel-etch and self-aligned coplanar structure, which is a key technology because of their advantages including low cost fabrication, high driving speed and unwanted visual artifact-free high quality imaging. The integration process and related issues, such as etching, post treatment, low ohmic contact and Cu interconnection, required for realizing these advanced architectures are also discussed.

  4. Single-step metal-organic vapor-phase diffusion for low-dark-current planar-type avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Jun, Dong-Hwan; Jeong, Hae Yong; Kim, Youngjo; Shin, Chan-Soo; Park, Kyung Ho; Park, Won-Kyu; Kim, Min-Su; Kim, Sangin; Han, Sang Wook; Moon, Sung

    2016-10-01

    In this paper, a p-type diffusion process based literally on single-step metal-organic vapor-phase diffusion (MOVPD) employing diethyl zinc as the diffusion source in combination with the recessetching technique is developed to improve the dark-current characteristics of planar-type avalanche photodiodes (APDs). The developed single-step MOVPD process exhibits on excellent linear relationship between the diffusion depth and the square root of the diffusion time, which mainly results from maintaining constant source diffusion. The single-step MOVPD process without any additional thermal activation process achieves a surface doping concentration of 1.9 × 1018 cm -3, which is sufficient to form ohmic contact. The measured diffusion profiles of the APDs clearly reveal the presence of a two-dimensional diffusion front formed by the recess-etched and guard-ring regions. The impact of this p-type diffusion process on the performance of the APD devices has also been demonstrated by exhibiting improved dark-current characteristics for the fabricated APDs.

  5. Type I collagen-mediated synthesis of noble metallic nanoparticles networks and the applications in Surface-Enhanced Raman Scattering and electrochemistry.

    PubMed

    Sun, Yujing; Sun, Lanlan; Zhang, Baohua; Xu, Fugang; Liu, Zhelin; Guo, Cunlan; Zhang, Yue; Li, Zhuang

    2009-08-15

    In this paper, we demonstrated an effective environmentally friendly synthesis route to prepare noble metallic (Au, Ag, Pt and Pd) nanoparticles (NPs) networks mediated by type I collagen in the absence of any seeds or surfactants. In the reactions, type I collagen served as stabilizing agent and assembly template for the synthesized metallic NPs. The hydrophobic interaction between collagen and mica interface as well as the hydrogen bonds between inter- and intra-collagen molecules play important roles in the formation of collagen-metallic NPs networks. The noble metallic NPs networks have many advantages in the applications of Surface-Enhanced Raman Scattering (SERS) and electrochemistry detection. Typically, the as-prepared Ag NPs networks reveal great Raman enhancement activity for 4-ATP, and can even be used to detect low concentration of DNA base, adenine, without any label step. Furthermore, the cyclic voltammograms showed Pt NPs networks have good electrocatalytic ability for the reduction of O(2).

  6. Hydrogen-terminated diamond vertical-type metal oxide semiconductor field-effect transistors with a trench gate

    NASA Astrophysics Data System (ADS)

    Inaba, Masafumi; Muta, Tsubasa; Kobayashi, Mikinori; Saito, Toshiki; Shibata, Masanobu; Matsumura, Daisuke; Kudo, Takuya; Hiraiwa, Atsushi; Kawarada, Hiroshi

    2016-07-01

    The hydrogen-terminated diamond surface (C-H diamond) has a two-dimensional hole gas (2DHG) layer independent of the crystal orientation. A 2DHG layer is ubiquitously formed on the C-H diamond surface covered by atomic-layer-deposited-Al2O3. Using Al2O3 as a gate oxide, C-H diamond metal oxide semiconductor field-effect transistors (MOSFETs) operate in a trench gate structure where the diamond side-wall acts as a channel. MOSFETs with a side-wall channel exhibit equivalent performance to the lateral C-H diamond MOSFET without a side-wall channel. Here, a vertical-type MOSFET with a drain on the bottom is demonstrated in diamond with channel current modulation by the gate and pinch off.

  7. Experimental and theoretical investigations of the electronic band structure of metal-organic frameworks of HKUST-1 type

    SciTech Connect

    Gu, Zhi-Gang; Heinke, Lars Wöll, Christof; Neumann, Tobias; Wenzel, Wolfgang; Li, Qiang; Fink, Karin; Gordan, Ovidiu D.; Zahn, Dietrich R. T.

    2015-11-02

    The electronic properties of metal-organic frameworks (MOFs) are increasingly attracting the attention due to potential applications in sensor techniques and (micro-) electronic engineering, for instance, as low-k-dielectric in semiconductor technology. Here, the band gap and the band structure of MOFs of type HKUST-1 are studied in detail by means of spectroscopic ellipsometry applied to thin surface-mounted MOF films and by means of quantum chemical calculations. The analysis of the density of states, the band structure, and the excitation spectrum reveal the importance of the empty Cu-3d orbitals for the electronic properties of HKUST-1. This study shows that, in contrast to common belief, even in the case of this fairly “simple” MOF, the excitation spectra cannot be explained by a superposition of “intra-unit” excitations within the individual building blocks. Instead, “inter-unit” excitations also have to be considered.

  8. Multistrip synthetic single-crystal-diamond photodiode based on a p-type/intrinsic/Schottky metal transverse configuration

    NASA Astrophysics Data System (ADS)

    Ciancaglioni, I.; Marinelli, Marco; Milani, E.; Prestopino, G.; Verona, C.; Verona-Rinati, G.; Angelone, M.; Pillon, M.; Dolbnya, I.; Sawhney, K.; Tartoni, N.

    2011-04-01

    A synthetic multistrip single-crystal-diamond detector based on a p-type/intrinsic diamond/Schottky metal transverse configuration, operating at zero-bias voltage, was developed. The device was characterized at the Diamond Light Source synchrotron in Harwell (UK) under monochromatic high-flux X-ray beams from 6 to 20 keV and a micro-focused 10 keV beam with a spot size of ~3 μm. No significant pixel-to-pixel variation of both spectral responsivity and time response, high spatial resolution and good signal uniformity along each strip were found, suggesting the tested device structure as a promising sensor for X-ray and UV radiation imaging.

  9. Drift region doping effects on characteristics and reliability of high-voltage n-type metal-oxide-semiconductor transistors

    NASA Astrophysics Data System (ADS)

    Chen, Jone F.; Chang, Chun-Po; Liu, Yu Ming; Tsai, Yan-Lin; Hsu, Hao-Tang; Chen, Chih-Yuan; Hwang, Hann-Ping

    2016-01-01

    In this study, off-state breakdown voltage (VBD) and hot-carrier-induced degradation in high-voltage n-type metal-oxide-semiconductor transistors with various BF2 implantation doses in the n- drift region are investigated. Results show that a higher BF2 implantation dose results in a higher VBD but leads to a greater hot-carrier-induced device degradation. Experimental data and technology computer-aided design simulations suggest that the higher VBD is due to the suppression of gate-induced drain current. On the other hand, the greater hot-carrier-induced device degradation can be explained by a lower net donor concentration and a different current-flow path, which is closer to the Si-SiO2 interface.

  10. On the metallicity dependence of the [Y/Mg]-age relation for solar-type stars

    NASA Astrophysics Data System (ADS)

    Feltzing, Sofia; Howes, Louise M.; McMillan, Paul J.; Stonkutė, Edita

    2017-02-01

    Several recent studies of solar twins in the solar neighbourhood have shown a tight correlation between various elemental abundances and age, in particular [Y/Mg]. If this relation is real and valid for other types of stars as well as elsewhere in the Galaxy, it would provide a very powerful tool to derive ages of stars without the need to resort to determining their masses (evolutionary stage) very precisely. The method would also likely work if the stellar parameters have relatively large errors. The studies presented in the recent literature span a narrow range of [Fe/H]. By studying a larger sample of solar neighbourhood dwarfs with a much larger range of [Fe/H], we find that the relation between [Y/Mg] and age depends on the [Fe/H] of the stars. Hence, it appears that the [Y/Mg]-age relation is unique to solar analogues.

  11. Theoretical study of inverted sandwich type complexes of 4d transition metal elements: interesting similarities to and differences from 3d transition metal complexes.

    PubMed

    Kurokawa, Yusaku I; Nakao, Yoshihide; Sakaki, Shigeyoshi

    2012-03-08

    Inverted sandwich type complexes (ISTCs) of 4d metals, (μ-η(6):η(6)-C(6)H(6))[M(DDP)](2) (DDPH = 2-{(2,6-diisopropylphenyl)amino}-4-{(2,6-diisopropylphenyl)imino}pent-2-ene; M = Y, Zr, Nb, Mo, and Tc), were investigated with density functional theory (DFT) and MRMP2 methods, where a model ligand AIP (AIPH = (Z)-1-amino-3-imino-prop-1-ene) was mainly employed. When going to Nb (group V) from Y (group III) in the periodic table, the spin multiplicity of the ground state increases in the order singlet, triplet, and quintet for M = Y, Zr, and Nb, respectively, like 3d ISTCs reported recently. This is interpreted with orbital diagram and number of d electrons. However, the spin multiplicity decreases to either singlet or triplet in ISTC of Mo (group VI) and to triplet in ISTC of Tc (group VII), where MRMP2 method is employed because the DFT method is not useful here. These spin multiplicities are much lower than the septet of ISTC of Cr and the nonet of that of Mn. When going from 3d to 4d, the position providing the maximum spin multiplicity shifts to group V from group VII. These differences arise from the size of the 4d orbital. Because of the larger size of the 4d orbital, the energy splitting between two d(δ) orbitals of M(AIP) and that between the d(δ) and d(π) orbitals are larger in the 4d complex than in the 3d complex. Thus, when occupation on the d(δ) orbital starts, the low spin state becomes ground state, which occurs at group VI. Hence, the ISTC of Nb (group V) exhibits the maximum spin multiplicity.

  12. Perovskite-type metal oxides exhibiting negligible grain boundary resistance to total electrical conductivity.

    PubMed

    Pannu, Tania; Pannu, Kanwar Gulsher Singh; Thangadurai, Venkataraman

    2011-01-17

    In this paper, we report the synthesis, structure and electrical properties of the perovskite-type AZn0.33+xNb0.67-xO3-δ (A = Sr or Ba; 0 ≤ x ≤ 0.08). The investigated compounds were prepared by employing the solid-state (ceramic) reaction using alkaline nitrates, zinc oxide, and niobium oxide at elevated temperatures in air. Powder X-ray diffraction (PXRD) showed the formation of disordered Zn and Nb at the B-sites of space group Pm3̅m with cubic structure and a lattice constant comparable to that of the literature. The AC impedance study showed mainly bulk contribution to the total electrical conductivity over the investigated frequency range of 0.01 Hz to 1 MHz in all the investigated atmospheres even at low temperatures, which is significantly different from that of the well-known perovskite-type B-site ordered BaCa0.33+xNb0.67-xO3-δ and the disordered acceptor-doped BaCeO3. The bulk dielectric constant determined at 500 and 700 °C in air was found to be in the range of 35-100. In air, the isothermal bulk dielectric constant seems to increase with an increasing Zn content, and a similar trend was observed for total electrical conductivity. In dry and wet H2, the electrical conductivity decreases with an increasing Zn content in AZn0.33+xNb0.67-xO3-δ, and the x = 0 member of the Ba compound exhibits the highest total conductivity of 7.2 × 10(-3) S cm(-1) in dry H2 at 800 °C. Both Sr and Ba compounds were found to be stable against the reaction with pure CO2 at 700 °C and H2O at 100 °C for a long period of time. SrZn0.33+xNb0.67-xO3-δ was found to be stable in 30 ppm H2S at 800 °C, while the corresponding Ba compound formed reaction products such as BaS (JCPDS Card 01-0757), BaS2 (JCPDS Card 21-0087), and BaS3 (JCPDS Card 03-0824).

  13. Thermophysical properties of perovskite type alkaline-earth metals and plutonium complex oxides

    NASA Astrophysics Data System (ADS)

    Tanaka, Kosuke; Sato, Isamu; Hirosawa, Takashi; Kurosaki, Ken; Muta, Hiroaki; Yamanaka, Shinsuke

    2012-03-01

    Polycrystalline specimens of strontium plutonate, SrPuO3, have been prepared by mixing the appropriate amounts of PuO2 and SrCO3 powders followed by reacting and sintering at 1600 K under the flowing gas atmosphere of dry-air. The sintered specimens had a single phase of orthorhombic perovskite structure and were crack-free. The elastic moduli of SrPuO3 were determined from the longitudinal and shear sound velocities. The Debye temperature was also determined from the sound velocities and lattice parameter measurements. The thermal conductivity of SrPuO3 was calculated from the measured density at room temperature, literature values of heat capacity, and thermal diffusivity measured by laser flash method in vacuum. Although the thermal conductivity of SrPuO3 slightly decreased with increasing temperature to 800 K, the range of change was extremely narrow and the temperature dependence did not completely follow the 1/T law. The thermal conductivity of SrPuO3 was lower than those of other perovskite type oxides.

  14. Metallicity In Narrow Line Regions Go High-Z Type-2 AGN

    NASA Astrophysics Data System (ADS)

    Mignoli, Marco; Feltre, A.; Bongiorno, A.; Gilli, R.; Calura, F.; Vanzella, E.; Bolzonella, M.; Comastri, A.; Vignali, C.; Brusa, M.; Cappelluti, N.

    2016-10-01

    The physics and demographics of high redshift obscured active galactic nuclei is still scarcely studied, and new samples of such objects, selected with different techniques, can provide useful insights into their physical nature. A sample of 90 narrow-line with 1.5< z < 3.0 was selected from the zCOSMOS-deep galaxy sample by detection of the high-ionization CIV 1549A emission line. The presence of this feature in a galaxy spectrum is indicative of nuclear activity, and the selection effectiveness has been also confirmed by ultraviolet emission line diagnostic diagrams. Taking advantage of the large amount of data available in the COSMOS field, the properties of the CIV-selected Type 2 AGN were analyzed, focusing on their host galaxies, X-ray emission, and UV emission line characteristics. Finally, the physical properties of the ionized gas in the Narrow Line Region have been investigated, combining the analysis of strong UV emission lines with the prediction from photoionization models.

  15. Unique failure behavior of metal/composite aircraft structural components under crash type loads

    NASA Technical Reports Server (NTRS)

    Carden, Huey D.

    1990-01-01

    Failure behavior results are presented on some of the crash dynamics research conducted with concepts of aircraft elements and substructure which have not necessarily been designed or optimized for energy absorption or crash loading considerations. To achieve desired new designs which incorporate improved energy absorption capabilities often requires an understanding of how more conventional designs behave under crash type loadings. Experimental and analytical data are presented which indicate some general trends in the failure behavior of a class of composite structures which include individual fuselage frames, skeleton subfloors with stringers and floor beams but without skin covering, and subfloors with skin added to the frame-stringer arrangement. Although the behavior is complex, a strong similarity in the static/dynamic failure behavior among these structures is illustrated through photographs of the experimental results and through analytical data of generic composite structural models. It is believed that the thread of similarity in behavior is telling the designer and dynamists a great deal about what to expect in the crash behavior of these structures and can guide designs for improving the energy absorption and crash behavior of such structures.

  16. Magnetism, f-electron localization and superconductivity in 122-type heavy-fermion metals.

    PubMed

    Steglich, F; Arndt, J; Stockert, O; Friedemann, S; Brando, M; Klingner, C; Krellner, C; Geibel, C; Wirth, S; Kirchner, S; Si, Q

    2012-07-25

    Both CeCu2Si2 and YbRh2Si2 crystallize in the tetragonal ThCr2Si2 crystal structure. Recent neutron-scattering results on normal-state CeCu2Si2 reveal a slowing down of the quasielastic response which complies with the scaling expected for a quantum critical point (QCP) of itinerant, i.e., three-dimensional spin-density-wave (SDW), type. This interpretation is in full agreement with the non-Fermi-liquid behavior observed in transport and thermodynamic measurements. The momentum dependence of the magnetic excitation spectrum reveals two branches of an overdamped dispersive mode whose coupling to the heavy charge carriers is strongly retarded. These overdamped spin fluctuations are considered to be the driving force for superconductivity in CeCu2Si2 (Tc = 600 mK). The weak antiferromagnet YbRh2Si2 (TN = 70 mK) exhibits a magnetic-field-induced QCP at BN = 0.06 T (B⊥c). There is no indication of superconductivity down to T = 10 mK. The magnetic QCP appears to concur with a breakdown of the Kondo effect. Doping-induced variations of the average unit-cell volume result in a detachment of the magnetic and electronic instabilities. A comparison of the properties of these isostructural compounds suggests that 3D SDW QCPs are favorable for unconventional superconductivity. The question whether a Kondo-breakdown QCP may also give rise to superconductivity, however, remains to be clarified.

  17. Syntheses and characterization of elpasolite-type ammonium alkali metal hexafluorometallates(III)

    SciTech Connect

    Mi Jinxiao Luo Shuming; Sun Huayu; Liu Xiaoxuan; Wei Zanbin

    2008-08-15

    Crystal structures of three fluorides (NH{sub 4}){sub 2}NaFeF{sub 6}, (Fe), (NH{sub 4}){sub 2}NaGaF{sub 6}, (Ga), and (NH{sub 4}){sub 2}NaCrF{sub 6}, (Cr), as well as a substituted compound [(NH{sub 4}){sub 1-x}K{sub x}]{sub 2}KAlF{sub 6} (x{approx}0.17), (Al), have been refined using single-crystal and powder X-ray diffraction techniques. All these four ammonium hexafluorides have a cubic elpasolite-type structure and crystallize in the space group Fm3-bar m with lattice constants a=8.483(3), 8.450 (3), 8.4472(2) and 8.724(3) A for compounds (Fe), (Ga), (Cr) and (Al), respectively. The effective ionic radius of the ammonium ion calculated from those compounds has a mean value of R=1.729 A for CN=12. An ultraviolet-visible absorption spectrum of (NH{sub 4}){sub 2}NaCrF{sub 6}, measured at room temperature, gives a crystal field (Dq=1575 cm{sup -1}) and Racah parameters (B=758 cm{sup -1} and C=3374 cm{sup -1}). Abnormal anisotropic thermal parameters of fluorine atoms have been observed in the compound (Al), and interpreted to arise from four strong hydrogen bonds (F...H-N) that are distributed in a square form around each fluorine atom. - Graphical abstract: Abnormal anisotropic thermal parameters of fluorine atoms have been observed in the compound [(NH{sub 4}){sub 1-x}K{sub x}]{sub 2}KAlF{sub 6} (x{approx}0.17), and interpreted to arise from four strong hydrogen bonds (F...H-N) that are distributed in a square form around each fluorine atom. The endmembers' phase transitions at low temperature are believed to be caused by them.

  18. An experimental study on fatigue performance of cryogenic metallic materials for IMO type B tank

    NASA Astrophysics Data System (ADS)

    Lee, Jin-Sung; You, Won-Hyo; Yoo, Chang-Hyuk; Kim, Kyung-Su; Kim, Yooil

    2013-12-01

    Three materials SUS304, 9% Ni steel and Al 5083-O alloy, which are considered possible candidate for International Maritime Organization (IMO) type B Cargo Containment System, were studied. Monotonic tensile, fatigue, fatigue crack growth rate and Crack Tip Opening Displacement tests were carried out at room, intermediate low (-100 °C) and cryogenic (-163 °C) temperatures. The initial yield and tensile strengths of all materials tended to increase with decreasing temperature, whereas the change in elastic modulus was not as remarkable. The largest and smallest improvement ratio of the initial yield strengths due to a temperature reduction were observed in the SUS304 and Al 5083- O alloy, respectively. The fatigue strengths of the three materials increased with decreasing temperature. The largest increase in fatigue strength was observed in the Al 5083-O alloy, whereas the 9% Ni steel sample showed the smallest increase. In the fatigue crack growth rate test, SUS304 and Al 5083-O alloy showed a decrease in the crack propagation rate, due to decrease in temperature, but no visible improvement in da/dN was observed in the case of 9% Ni steel. In the Crack Tip Opening Displacement (CTOD) test, CTOD values were converted to critical crack length for the comparison with different thickness specimens. The critical crack length tended to decrease in the case of SUS304 and increase for the Al 5083-O alloy with decreasing temperature. In case of 9% Ni steel, change of critical crack length was not observed due to temperature decrease. In addition, the changing material properties according to the temperature of the LNG tank were analyzed according to the international code for the construction and equipment of ships carrying liquefied gases in bulk (IGC code) and the rules of classifications.

  19. Hyperfine interactions in nanocrystallized NANOPERM-type metallic glass containing Mo

    NASA Astrophysics Data System (ADS)

    Cesnek, M.; Kubániová, D.; Kohout, J.; Křišťan, P.; Štěpánková, H.; Závěta, K.; Lančok, A.; Štefánik, M.; Miglierini, M.

    2016-12-01

    NANOPERM-type alloy with chemical composition Fe76Mo8CuB15 was studied by combination of 57Fe Mössbauer spectroscopy and 57Fe(10B, 11B) nuclear magnetic resonance in order to determine distribution of hyperfine magnetic fields and evolution of relative concentration of Fe-containing crystalline phases within the surface layer and the volume of the nanocrystallized ribbons with annealing temperature. Differential scanning calorimetry revealed two crystallization stages at T x1 ˜ 510 ∘C and T x2 ˜ 640 ∘C, connected to precipitation of α-Fe and Fe(Mo,B) nanocrystals, respectively. The amorphous and partially crystalline state was obtained by annealing at several temperatures in the range 510-650 ∘C. The combination of conversion electron (CEMS) and transmission Mössbauer spectrometry (TMS) showed that annealing induces crystallization starting from both surfaces of the ribbons. For the as-quenched sample, scanning electron microscopy (SEM) and CEMS revealed significant differences in the "air" and "wheel" sides of the ribbons, crystallites were preferentially formed at the latter. While SEM micrographs of annealed samples showed various mean diameters of the crystals at opposite sides of the ribbons, the amounts of crystalline volume derived from the CEMS spectra approximately equaled. Mössbauer spectra of annealed samples contained narrow sextet ascribed to crystalline α-Fe phase, three sextets with distribution of hyperfine field assigned to the interface regions of the nanocrystals and the contribution of the amorphous phases. In-field TMS performed at 4.2 K with magnetic moments aligned by external magnetic field enabled to properly determine in particular the contribution of the amorphous phases in the samples. Resulting distributions of the hyperfine fields were compared with 57Fe(10B, 11B) nuclear magnetic resonance (NMR) spectra.

  20. Method Of Bonding A Metal Connection To An Electrode Including A Core Having A Fiber Or Foam Type Structure For An Electrochemical Cell, An

    DOEpatents

    Loustau, Marie-Therese; Verhoog, Roelof; Precigout, Claude

    1996-09-24

    A method of bonding a metal connection to an electrode including a core having a fiber or foam-type structure for an electrochemical cell, in which method at least one metal strip is pressed against one edge of the core and is welded thereto under compression, wherein, at least in line with the region in which said strip is welded to the core, which is referred to as the "main core", a retaining core of a type analogous to that of the main core is disposed prior to the welding.

  1. Multistep soft chemistry method for valence reduction in transition metal oxides with triangular (CdI2-type) layers.

    PubMed

    Blakely, Colin K; Bruno, Shaun R; Poltavets, Viktor V

    2014-03-14

    Transition metal (M) oxides with MO2 triangular layers demonstrate a variety of physical properties depending on the metal oxidation states. In the known compounds, metal oxidation states are limited to either 3+ or mixed-valent 3+/4+. A multistep soft chemistry synthetic route for novel phases with M(2+/3+)O2 triangular layers is reported.

  2. Evolution of weld metals nanostructure and properties under irradiation and recovery annealing of VVER-type reactors

    NASA Astrophysics Data System (ADS)

    Gurovich, B.; Kuleshova, E.; Shtrombakh, Ya.; Fedotova, S.; Zabusov, O.; Prikhodko, K.; Zhurko, D.

    2013-03-01

    The results of VVER-440 steel Sv-10KhMFT and VVER-1000 steel SV-10KhGNMAA investigations by transmission electron microscopy, scanning electron microscopy, Auger-electron spectroscopy and mechanical tests are presented in this paper. The both types of weld metals with different content of impurities and alloying elements were studied after irradiations to fast neutron (E > 0.5 MeV) fluences in the wide range below and beyond the design values, after recovery annealing procedures and after re-irradiation following the annealing. The distinctive features of embrittlement kinetics of VVER-440 and VVER-1000 RPV weld metals conditioned by their chemical composition differences were investigated. It is shown that the main contribution into radiation strengthening within the design fluence can be attributed to radiation-induced precipitates, on reaching the design or beyond design values of fast neutron fluencies the main contribution into VVER-440 welds strengthening is made by radiation-induced dislocation loops, and in case of VVER-1000 welds - radiation-induced precipitates and grain-boundary phosphorous segregations. Recovery annealing of VVER-440 welds at 475 °C during 100 h causes irradiation-induced defects disappearance, transformation of copper enriched precipitates into bigger copper-rich precipitates with lower number density and leads to almost full recovery of mechanical properties followed by comparatively slow re-embrittlement rate. The recovery annealing temperature of VVER-1000 welds was higher - 565 °C during 100 h - to avoid temper brittleness. The annealing of VVER-1000 welds leads to almost full recovery of mechanical properties due to irradiation-induced defects disappearance and decrease in precipitates number density and grain-boundary segregation of phosphorus. The re-embrittlement rate of VVER-1000 weld during subsequent re-irradiation is at least not higher than the initial rate.

  3. Heavy Metal Presence in Two Different Types of Ice Cream: Artisanal Ice Cream (Italian Gelato) and Industrial Ice Cream.

    PubMed

    Conficoni, D; Alberghini, L; Bissacco, E; Ferioli, M; Giaccone, V

    2017-03-01

    Ice cream, a popular product worldwide, is usually a milk-based product with other types of ingredients (fruit, eggs, cocoa, dried fruit, additives, and others). Different materials are used to obtain the desired taste, texture, consistency, and appearance of the final product. This study surveyed ice cream products available in Italy for heavy metals (lead, cadmium, chromium, tin, and arsenic). The differences between artisanal and industrial ice cream were also investigated because of the importance in the Italian diet and the diffusion of this ready-to-eat food. Ice cream sampling was performed between October 2010 and February 2011 in the northeast of Italy. A total of 100 samples were randomly collected from different sources: 50 industrial samples produced by 19 different brands were collected in coffee bars and supermarkets; 50 artisanal ice cream samples were gathered at nine different artisanal ice cream shops. Ten wooden sticks of industrial ice cream were analyzed in parallel to the ice cream. All samples were negative for arsenic and mercury. None of the artisanal ice cream samples were positive for lead and tin; 18% of the industrial ice cream samples were positive. All positive lead samples were higher than the legal limit stated for milk (0.02 mg/kg). All industrial ice cream samples were negative for cadmium, but cadmium was present in 10% of the artisanal ice cream samples. Chromium was found in 26% of the artisanal and in 58% of the industrial ice cream samples. The heavy metals found in the wooden sticks were different from the corresponding ice cream, pointing out the lack of cross-contamination between the products. Considering the results and the amount of ice cream consumed during the year, contamination through ice cream is a low risk for the Italian population, even though there is need for further analysis.

  4. High dispersion spectroscopy of solar-type superflare stars. I. Temperature, surface gravity, metallicity, and vsin i

    NASA Astrophysics Data System (ADS)

    Notsu, Yuta; Honda, Satoshi; Maehara, Hiroyuki; Notsu, Shota; Shibayama, Takuya; Nogami, Daisaku; Shibata, Kazunari

    2015-06-01

    We conducted high-dispersion spectroscopic observations of 50 superflare stars with Subaru High Dispersion Spectrograph (HDS), and measured the stellar parameters of them. These 50 targets were selected from the solar-type (G-type main sequence) superflare stars that we had discovered from the Kepler photometric data. As a result of these spectroscopic observations, we found that more than half (34) of our 50 targets have no evidence of binary systems. We then estimated the effective temperature (Teff), surface gravity (log g), metallicity ([Fe/H]), and projected rotational velocity (vsin i) of these 34 superflare stars on the basis of our spectroscopic data. The accuracy of our estimations is higher than that of the Kepler Input Catalog (KIC) values, and the differences between our values and KIC values [(ΔTeff)rms ˜ 219 K, (Δlog g)rms ˜ 0.37 dex, and (Δ[Fe/H])rms ˜ 0.46 dex] are comparable to the large uncertainties and systematic differences of KIC values reported by the previous researchers. We confirmed that the estimated Teff and log g values of the 34 superflare stars are roughly in the range of solar-type stars. In particular, these parameters and the brightness variation period (P0) of nine of the stars are in the range of "Sun-like" stars (5600 ≤ Teff ≤ 6000 K, log g ≥ 4.0, and P0 > 10 d). Five of the 34 target stars are fast rotators (vsin i ≥ 10 km s-1), while 22 stars have relatively low vsin i values (vsin i < 5 km s-1). These results suggest that stars that have spectroscopic properties similar to the Sun can have superflares, and this supports the hypothesis that the Sun might cause a superflare.

  5. SN 2010ay is a Luminous and Broad-lined Type Ic Supernova within a Low-metallicity Host Galaxy

    NASA Technical Reports Server (NTRS)

    Sanders, N. E.; Soderberg, A. M.; Valenti, S.; Chomiuk, L.; Berger, E.; Smartt, S.; Hurley, K.; Barthelmy, S. D.; Chornock, R.; Foley, R. J.; Levesque, E. M.; Narayan, G.; Botticella, M. T.; Briggs, M. S.; Connaughton, V.; Terada, Y.; Gehrels, N.; Golenetskii, S.; Mazets, E.; Cline, T.; von Kienlin, A.; Boynton, W.; Chambers, K. C.; Grav, T.; Heasley, J. N.

    2011-01-01

    We report on our serendipitous pre-discovery detection and detailed follow-up of the broad-lined Type Ic supernova SN2010ay at z approx 0.067 imaged by the Pan-STARRS1 3pi survey just approx 4 days after explosion. Combining our photometric observations with those available in the literature, we estimate the explosion date and the peak luminosity of the SN, M(sub R) approximately equals 20.2 mag, significantly brighter than known GRB-SNe and one of the most luminous SNe Ibc ever discovered. We measure the photospheric expansion velocity of the explosion from our spectroscopic follow-up observations, v(sub ph) approximately equals 19.2 X 10 (exp 3) km/s at approx 40 days after explosion. In comparison with other broad-lined SNe, the characteristic velocity of SN2010ay is 2 - 5 X higher and similar to the measurements for GRB-SNe at comparable epochs. Moreover the velocity declines two times slower than other SNe Ic-BL and GRB-SNe. Assuming that the optical emission is powered by radioactive decay, the peak magnitude implies the synthesis of an unusually large mass of Ni-56, M(sub Ni) = 0.9(+0.1/-0.1) solar mass. Our modeling of the light-curve points to a total ejecta mass, M(sub ej) approx 4.7 Solar Mass, and total kinetic energy, E(sub K,51) approximately equals 11. Thus the ratio of M(sub Ni) to M(sub ej) is at least twice as large for SN2010ay than in GRB-SNe and may indicate an additional energy reservoir. We also measure the metallicity (log(O/H) + 12 = 8.19) of the explosion site within the host galaxy using a high S/N optical spectrum. Our abundance measurement places this SN in the low-metallicity regime populated by GRB-SNe, and approx 0.2(0.5) dex lower than that typically measured for the host environments of normal (broad-lined) Ic supernovae. Despite striking similarities to the recent GRB-SN100316D/2010bh, we show that gamma-ray observations rule out an associated GRB with E(sub gamma) approx < 6 X 10(exp 48) erg (25-150 keV). Similarly, our deep

  6. SN 2010ay Is a Luminous and Broad-Lined Type Ic Supernova Within a Low-Metallicity Host Galaxy

    NASA Technical Reports Server (NTRS)

    Sanders, N. E.; Soderberg, A. M.; Valenti, S.; Foley, R. J.; Chornock, R.; Chomiuk, L.; Berger, E.; Smartt, S.; Hurley, K.; Barthelmy, S. D.; Levesque, E. M.; Narayan, G.; Botticella, M. T.; Briggs, M. S.; Connaughton, V.; Terada, Y.; Gehrels, N.; Golenetskii, S.; Mazets, E.; Cline, T.; von Kienlin, A.; Boynton, W.; Chambers, K. C.; Grav, T.; Heasley, J. N.

    2012-01-01

    We report on our serendipitous pre-discovery detection and follow-up observations of the broad-lined Type Ic supernova (SN Ic) 2010ay at z = 0.067 imaged by the Pan-STARRS1 3pi survey just approximately 4 days after explosion. The supernova (SN) had a peak luminosity, MR approx. -20.2 mag, significantly more luminous than known GRB-SNe and one of the most luminous SNe Ib/c ever discovered. The absorption velocity of SN 2010ay is v Si (is) approx. 19×10(exp 3) km s-1 at approximately 40 days after explosion, 2-5 times higher than other broad-lined SNe and similar to the GRB-SN 2010bh at comparable epochs. Moreover, the velocity declines approximately 2 times slower than other SNe Ic-BL and GRB-SNe. Assuming that the optical emission is powered by radioactive decay, the peak magnitude implies the synthesis of an unusually large mass of 56Ni, MNi = 0.9 solar mass. Applying scaling relations to the light curve, we estimate a total ejecta mass, Mej (is) approx. 4.7 solar mass, and total kinetic energy, EK (is) approx. 11 × 10(exp 51) erg. The ratio of MNi to Mej is approximately 2 times as large for SN 2010ay as typical GRB-SNe and may suggest an additional energy reservoir. The metallicity (log(O/H)PP04 + 12 = 8.19) of the explosion site within the host galaxy places SN 2010ay in the low-metallicity regime populated by GRB-SNe, and (is) approximately 0.5(0.2) dex lower than that typically measured for the host environments of normal (broad-lined) SNe Ic. We constrain any gamma-ray emission with E(gamma) (is) approximately less than 6 × 10(exp 48) erg (25-150 keV), and our deep radio follow-up observations with the Expanded Very Large Array rule out relativistic ejecta with energy E (is) approximately greater than 10(exp 48) erg. We therefore rule out the association of a relativistic outflow like those that accompanied SN 1998bw and traditional long-duration gamma-ray bursts (GRBs), but we place less-stringent constraints on a weak afterglow like that seen from XRF

  7. Front Side Metallization of n- and p-Type, High-Efficiency, Single-Crystalline Si Solar Cells: Assessing the Temperature-Dependent Series Resistance

    NASA Astrophysics Data System (ADS)

    Willsch, Benjamin; Kumar, Praveen; Eibl, Oliver

    2016-06-01

    The series resistance of high-quality, single crystalline p-type and n-type solar cells was measured in a temperature range between 80 K and room temperature. Among one cell type ( n or p), cells were processed identically. Only the processing of the front side metallization was varied by using different processing conditions and screen printing pastes. High-efficiency n- ( η = 20.0%) and p-type ( η = 18.0%) cells yielded similar contact and series resistance and common features of the microstructure of the front side contact, i.e. a glass layer containing Ag colloids with typical diameters of 5-200 nm. Temperature-dependent current voltage curves ( I- V curves) were acquired and evaluated with respect to the series resistance by using two different methods yielding different results. On average the series resistance follows the trends of the contact resistance of the front side metallization determined at room temperature. Optimally processed cells yielded series resistances of less than 25 mΩ cm2 (method #1) both for n- and p-type cells. It could be shown that the series resistance reflected the processing conditions and paste properties and yielded similar temperature dependence for p- and n-type cells with small contact resistance. Therefore, the relevant current paths of high-efficiency n- and p-type cells appear to be similar in the front side metallization and include the glass layer which contains a high density of Ag colloids.

  8. The End of Amnesia: A New Method for Measuring the Metallicity of Type Ia Supernova Progenitors Using Manganese Lines in Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Badenes, Carles; Bravo, Eduardo; Hughes, John P.

    2008-06-01

    We propose a new method to measure the metallicity of Type Ia supernova progenitors using Mn and Cr lines in the X-ray spectra of young supernova remnants. We show that the Mn-to-Cr mass ratio in Type Ia supernova ejecta is tightly correlated with the initial metallicity of the progenitor, as determined by the neutron excess of the white dwarf material before thermonuclear runaway. We use this correlation, together with the flux of the Cr and Mn Kα X-ray lines in the Tycho supernova remnant recently detected by Suzaku, to derive a metallicity of log (Z) = - 1.32+ 0.67-0.33 for the progenitor of this supernova, which corresponds to log (Z/Z⊙) = 0.60+ 0.31-0.60 according to the latest determination of the solar metallicity by Asplund and coworkers. The uncertainty in the measurement is large, but metallicities much smaller than the solar value can be confidently discarded. We discuss the implications of this result for future research on Type Ia supernova progenitors.

  9. Kagome-type isostructural 3D-transition metal fluorosulfates with spin 3/2 and 1: synthesis, structure and characterization.

    PubMed

    Marri, Subba R; Kumar, Jitendra; Panyarat, Kitt; Horike, Satoshi; Behera, J N

    2016-11-28

    Two isostructural transition metal fluorosulfates based on Co and Ni metal ions with the molecular composition of [H3O][M(SO4)F] (where M = Co((II)) for 1 and Ni((II)) for 2) were synthesized under solvothermal conditions and structurally characterized by single crystal X-ray analysis. The materials were further characterized by complementary techniques like TGA, FTIR and PXRD. The 3D-crystal lattice consists of a kagome-type entity where sulfate groups replaced one of the metal nodes when compared with true kagome structures. Magnetic studies of the complexes were also performed which showed that the interactions at the metal center are antiferromagnetic in nature. The proton conductivity increases with the increase in humidity and was found to be 7.9 × 10(-6) S cm(-1) for 2 at RH = 98%.

  10. Integrating hydrogen generation and storage in a novel compact electrochemical system based on metal hydrides

    NASA Astrophysics Data System (ADS)

    Rangel, C. M.; Fernandes, V. R.; Slavkov, Y.; Bozukov, L.

    The development of efficient and reliable energy storage systems based on hydrogen technology represents a challenge to seasonal storage based on renewable hydrogen. State of the art renewable energy generation systems include separate units such as electrolyzer, hydrogen storage vessel and a fuel cell system for the conversion of H 2 back into electricity, when required. In this work, a novel electrochemical system has been developed which integrates hydrogen production, storage and compression in only one device, at relatively low cost and high efficiency. The developed prototype comprises a six-electrode cell assembly using an AB 5-type metal hydride and Ni plates as counter electrodes, in a 35-wt% KOH solution. Metal hydride electrodes with chemical composition LaNi 4.3Co 0.4Al 0.3 were prepared by high frequency vacuum melting followed by high temperature annealing. X-ray phase analysis showed typical hexagonal structure and no traces of other intermetallic compounds belonging to the La-Ni phase diagram. Thermodynamic study has been performed in a Sieverts type of apparatus produced by Labtech Int. During cycling, the charging/discharging process was studied in situ using a gas chromatograph from Agilent. It is anticipated that the device will be integrated as a combined hydrogen generator and storage unit in a stand-alone system associated to a 1-kW fuel cell.

  11. Evaluation of metal ion absorptive characteristics of three types of plastic sample bags used for pecipitation sampling

    USGS Publications Warehouse

    Good, A.B.; Schroder, L.J.

    1984-01-01

    Simulated precipitation samples containing 16 metal ions were prepared at 4 pH values. Absorptive characteristics of polypropylene, polyethylene, and polyester/polyolefin sacks were evaluated at pH 3.5, 4.0, 4.5, and 5.0. Simulated precipitation was in contact with the sacks for 17 days, and subsamples were removed for chemical analysis at 3, 7, 10, 14, and 17 days after initial contact. All three types of plastic sacks absorbed Fe throughout the entire pH range. Polypropylene and polyethylene absorbed Pb throughout the entire pH range; polyester/polyolefin sacks absorbed Pb at pH 4.0 or greater. All plastic sacks also absorbed Cu, Mo, and V at pH 4.5 and 5.0. Leaching the plastic sacks with 0.7 percent HNO3 did not result in 100 percent of Cu, Fe, Pb, and V. These sacks would be suitable collection vessels for Ba, Be, Ca, Cd, Co, Li, Mg, Mn, Na Sr and Zn in precipitation through the pH range of 3.5 to 5.0.

  12. Water splitting over new niobate photocatalysts with tungsten-bronze-type structure and effect of transition metal-doping.

    PubMed

    Miseki, Yugo; Kudo, Akihiko

    2011-02-18

    Photophysical properties and photocatalytic activities for water splitting over KM(2)Nb(5)O(15) (M = Sr and Ba) and K(2)LnNb(5)O(15) (Ln = La, Pr, Nd, and Sm) with tungsten bronze-type structure were investigated. Single phases of KM(2)Nb(5)O(15) and K(2)LnNb(5)O(15) were successfully prepared by solid-state reaction (SSR) method and polymerizable complex (PC) method. The band gaps of these niobates were estimated to be 3.1-3.5 eV. These metal oxides loaded with an activated NiO(x) cocatalyst showed photocatalytic activities for water splitting into H(2) and O(2) under UV irradiation. When K(2)LaNb(5)O(15) was doped by Rh ions, a new visible-light absorption band was observed around 400-500 nm in addition to the band gap absorption band of the K(2)LaNb(5)O(15) host. K(2)LaNb(5)O(15):Rh showed photocatalytic activities for H(2) or O(2) evolution from an aqueous solution containing a sacrificial reagent under visible-light irradiation.

  13. Supergiants and the Galactic metallicity gradient. II - Spectroscopic abundances for 64 distant F- to M-type supergiants

    NASA Astrophysics Data System (ADS)

    Luck, R. Earle; Bond, Howard E.

    1989-11-01

    The metallicity gradient in the Galactic disk from in situ stars with visual magnitude ranging from 6 to 10 is analyzed. Atmospheric parameters and detailed chemical abundances for 64 Population I supergiants of spectral types F through M and luminosity classes Ia through II have been determined. The derived Fe/H ratios ranging from -0.5 to + 0.7 show a mean value of +0.13 with an estimated uncertainty of + or - 0.2. A subset of 25 supergiants fainter than 7th magnitude lying in the direction of the Galactic center shows a Fe/H mean of +0.18 + or - 0.04, while a similar sample of 15 faint supergiants lying in the direction of the Galactic anticenter shows a lower Fe/H mean of +0.07 + or - 0.06. For a sample of bright supergiants analyzed by Luck and Lambert (1985), the mean abundance pattern for all 64 stars showed the following: deficient C and O along with enhancement of N, indicating mixing of CNO-cycled material to the stellar surfaces; an apparent Sr enhancement attributed to departures from LTE; and an essentially solar pattern of other chemical elements.

  14. Metal-insulator transition in 3d transition-metal oxides with ABO 3 and A 2BO 4 type structures

    NASA Astrophysics Data System (ADS)

    Eisaki, H.; Ido, T.; Magoshi, K.; Mochizuki, M.; Yamatsu, H.; Ito, T.; Uchida, S.

    1991-12-01

    3d transition-metal oxides with perovskite and K 2NiF 4 crystal structures, (La,Sr)VO 3, (La,Sr)FeO 3, (La,Sr)CoO 3, LaNiO 3 and (La,Sr) 2NiO 4 systems are investigated focusing on the effect of carrier doping performed by the A-site ion substitution. Both (La,Sr)VO 3 and (La,Sr)CoO 3 systems show an insulator to metal transition by Sr substitution, however, the magnetic behavior differs drastically. The mid-infrared structure induced by Sr substitution is observed in the optical spectra of (La,Sr) 2NiO 4 system. Relation between the behavior of metal-insulator transition and the variation of the electronic and/or spin structure in these systems is discussed in comparison with the high-T c copper oxides.

  15. [Flow of molten metal in denture base in horizontal centrifugal casting procedure. (Part 1) Flow, inflow volume and casting time of molten metal passing through single aprue into disk type mold (author's transl)].

    PubMed

    Okamura, H

    1976-01-01

    A pyrex glass plate was fitted at the bottom of casting ring, and disk type wax pattern (thickness. 0.43 mm) was put on the plate. Five types of sprueing were applied. Pure tin was casted using holizontal centrifugal casting machine. Flow of molten metal was filmed by the motor drive camera with the method of stroboscope. The results were summarized as follows. 1) When the sprue was attached at the center of the disk type mold vertically, moten metal flowed like a concentric circle at the early stage of casting. It was affected gradually by the direction of gravity and revolution, and it filled the mold from the lower part to the upper part. 2) When the sprue gate was attached to the side edge of the mold, and the sprue gate was placed to the forward and backward direction against the revolution direction, molten metal filled from lower part to the upper part. 3) When the sprue gate was placed against upper edge, molten metal flow was affected by the direction of gravity and revolution. When the sprue gate was placed against lower edge, molten metal filled quietry from the lower part to the upper part. 4) Inflow volume per unit time (inflow rate) was small at the early stage of casting. Inflow rate increased and became constant at the next stage. At the latter stage it became small again. 5) Inflow rate increased with the increase of area of sprue. 6) The time which was necessary to fill the volume of 1 cm (about 80% of the mold volume) became short with the increase of area of sprue. It was also influenced by the type of sprueing.

  16. A TiAlCu Metallization for ` n' Type CoSb_x Skutterudites with Improved Performance for High-Temperature Energy Harvesting Applications

    NASA Astrophysics Data System (ADS)

    Rao, Ashwin; Bosak, Gregg; Joshi, Binay; Keane, Jennifer; Nally, Luke; Peng, Adam; Perera, Susanthri; Waring, Alfred; Poudel, Bed

    2017-04-01

    The choice of the appropriate metallizing layer for high-temperature thermoelectric (TE) materials is a tricky task and poses varied challenges to researchers. In this work, a n type TiAl metallizing layer (90% Ti with 10% Al by weight with a copper foil) is proposed for a Yb_{0.2}Co4Sb_{12} skutterudite (SK) TE material coupled with a standard ` p type' SK base of Nd_{0.45}Ce_{0.45}Fe_{3.5}Co_{0.5}Sb_{12} with a 60:12:28% Fe:Ni:Cr metallizing layer. The n type and p type nanostructured SK powders are sintered at high temperatures and pressures in a DC hot press from which a TE device is assembled using diced, polished and property characterized TE legs (high figure of merit zT of 1.4 for n type and 1.2 for p type, respectively). The device is evaluated for functional degradation with repeated cycling to 500°C hot side (HS) and 50°C cold side (CS) temperatures in a specially designed high-vacuum test rig with key TE properties like peak power, open circuit voltage, and material internal resistance continuously recorded over each cycle. The device shows stable performance with <7% drop in TE harvested power over 2500 thermal cycles. With the industry benchmark for evaluating TE device performance being around 1000 thermal cycles (<10% drop in TE power over time), the study indicates stable performance of the n type TiAl metallizing layer over the device lifetime.

  17. Impact on global metal flows arising from the use of portable rechargeable batteries.

    PubMed

    Rydh, Carl Johan; Svärd, Bo

    2003-01-20

    The use of portable rechargeable battery cells and their effects on global metal flows were assessed or the following three cases: (1) the base case, which reflects the situation in 1999 of the global production of batteries; (2) the global production of portable nickel-cadmium batteries in 1999, assumed to be replaced by other battery types; and (3) assessment of the projected battery market in 2009. The study included the following battery technologies: nickel-cadmium (NiCd); nickel-metal hydride (NiMH) (AB(5), AB(2)); and lithium-based batteries (Li-ion: Co, Ni, Mn; Li-polymer: V). Based on the lithospheric extraction indicator (LEI), which is the ratio of anthropogenic to natural metal flows, and the significance of battery production related to global metal mining, the potential environmental impact of metals used in different battery types was evaluated. The LEIs and average metal demand for the battery market in 1999, expressed as a percentage of global mining output in 1999, were estimated to be as follows: Ni 5.6 (2.0%); Cd 4.4 (37%); Li 0.65 (3.8%); V 0.33 (6.5%); Co 0.18 (15%); Nd 0.18 (8.4%); La 0.10 (9.5%); Ce 0.083 (4.4%); and Pr 0.073 (9.4%). The use of Ni and Cd is of the greatest environmental interest, due to their high LEIs. In the case of complete replacement of portable NiCd batteries by NiMH or Li-based batteries, the LEI for Ni (5.6) would change by -0.1-0.5% and the LEI for Cd would decrease from 4.4 to 3.0 (-31%). Meanwhile, the mobilization of metals considered less hazardous than Cd (LEI 0 < 5) would increase less than 7%. Based on this assessment, the replacement of NiCd batteries would result in decreased environmental impact. To decrease the impact on global metal flows arising from the use of portable batteries the following points should be considered: (1) development of battery technologies should aim at high energy density and long service life; (2) metals with high natural occurrence should be used; and (3) metals from disused

  18. The impact of greenhouse vegetable farming duration and soil types on phytoavailability of heavy metals and their health risk in eastern China.

    PubMed

    Yang, Lanqin; Huang, Biao; Hu, Wenyou; Chen, Yong; Mao, Mingcui; Yao, Lipeng

    2014-05-01

    Heavy metal contamination in vegetables from greenhouse vegetable production (GVP) in China requires major attention. For GVP sustainability at a large regional level, 441 surface GVP soil and 132 corresponding greenhouse vegetable samples were collected from six typical GVP bases in eastern China to systematically evaluate the impact of GVP duration and soil types (Anthrosols and Cambosols) on phytoavailability of four major metals, Cd, Cu, Zn, and Pb, and their health risk. The results revealed high Cd accumulation in leaf vegetables grown in Anthrosols, which might pose potential health risk. Regardless of soil types in the study region, greenhouse farming lowered soil pH and enhanced metal availability with rising GVP duration, which might exacerbate Cd phytoavailability and vegetable Cd contamination as well as potential health risk. Also, increased GVP soil organic matter contents over time, found in some locations, affected crop-depending Cu and Zn uptakes. Furthermore, due to GVP, the annual decrease rate of soil pH and increase rates of soil available metal concentrations were generally much greater in Anthrosols than those in Cambosols, which contributed a lot to high Cd uptake by leaf vegetables grown in Anthrosols and their potential health risk. From sustainable GVP perspective, fertilization strategy with reduced frequency and rate is especially important and effective for abating soil and vegetable contamination by heavy metals under greenhouse farming.

  19. Annealing behaviors of vacancy-type defects near interfaces between metal contacts and GaN probed using a monoenergetic positron beam

    NASA Astrophysics Data System (ADS)

    Uedono, Akira; Fujishima, Tatsuya; Piedra, Daniel; Yoshihara, Nakaaki; Ishibashi, Shoji; Sumiya, Masatomo; Laboutin, Oleg; Johnson, Wayne; Palacios, Tomás

    2014-08-01

    Vacancy-type defects near interfaces between metal contacts and GaN grown on Si substrates by metal organic chemical vapor deposition have been studied using a monoenergetic positron beam. Measurements of Doppler broadening spectra of the annihilation radiation for Ti-deposited GaN showed that optically active vacancy-type defects were introduced below the Ti/GaN interface after annealing at 800 °C. Charge transition of those defects due to electron capture was observed and was found to correlate with a yellow band in the photoluminescence spectrum. The major defect species was identified as vacancy clusters such as three to five Ga-vacancies coupled with multiple nitrogen-vacancies. The annealing behaviors of vacancy-type defects in Ti-, Ni-, and Pt-deposited GaN were also examined.

  20. Annealing behaviors of vacancy-type defects near interfaces between metal contacts and GaN probed using a monoenergetic positron beam

    SciTech Connect

    Uedono, Akira Yoshihara, Nakaaki; Fujishima, Tatsuya; Piedra, Daniel; Palacios, Tomás; Ishibashi, Shoji; Sumiya, Masatomo; Laboutin, Oleg; Johnson, Wayne

    2014-08-04

    Vacancy-type defects near interfaces between metal contacts and GaN grown on Si substrates by metal organic chemical vapor deposition have been studied using a monoenergetic positron beam. Measurements of Doppler broadening spectra of the annihilation radiation for Ti-deposited GaN showed that optically active vacancy-type defects were introduced below the Ti/GaN interface after annealing at 800 °C. Charge transition of those defects due to electron capture was observed and was found to correlate with a yellow band in the photoluminescence spectrum. The major defect species was identified as vacancy clusters such as three to five Ga-vacancies coupled with multiple nitrogen-vacancies. The annealing behaviors of vacancy-type defects in Ti-, Ni-, and Pt-deposited GaN were also examined.

  1. High quality draft genome sequence of the heavy metal resistant bacterium Halomonas zincidurans type strain B6T

    PubMed Central

    2014-01-01

    Halomonas zincidurans strain B6T was isolated from a deep-sea heavy metal rich sediment from the South Atlantic Mid-Ocean Ridge. The strain showed significant resistance to heavy metals, especially to zinc. Here we describe the genome sequence and annotation, as well as the features, of the organism. The genome contains 3,325 protein-coding genes (2,848 with predicted functions), 61 tRNA genes and 6 rRNA genes. H. zincidurans strain B6T encodes 31 genes related to heavy metal resistance. And HGT may play an important role in its adaption to the heavy metal rich environment. H. zincidurans strain B6T may have potential applications in the bioremediation of heavy metal-contaminated environments. PMID:25945155

  2. Improved thermoelectric performance of p-type polycrystalline bismuth telluride via hydrothermal treatment with alkali metal salts

    NASA Astrophysics Data System (ADS)

    Su, Zhe

    The field of thermoelectric research has attracted a lot of interest in hope of helping address the energy crisis. In recent years, low-dimensional thermoelectric materials have been found promising and thus become a popular school of thought. However, the high complexity and cost for fabricating low-dimensional materials give rise to the attempt to further improve conventional bulk polycrystalline materials. Polycrystals are featured by numerous grain boundaries that can scatter heat-carrying phonons to significantly reduce the thermal conductivity kappa whereas at the same time can unfortunately deteriorate the electrical resistivity rho. Aiming at the dualism of the grain boundaries in determining the transport properties of polycrystalline materials, a novel concept of "grain boundary engineering" has been proposed in order to have a thermoelectrically favorable grain boundary. In this dissertation, a polycrystalline p-type Bi2Te 3 system has been intensively investigated in light of such a concept that was realized through a hydrothermal nano-coating treatment technique. P-type Bi0.4Sb1.6Te3 powder was hydrothermally treated with alkali metal salt XBH4 ( X = Na, K or Rb) solution. After the treatment, there formed an alkali-metal-containing surface layer of nanometers thick on the p-Bi2Te3 grains. The Na-treatment, leaving the Seebeck coefficient alpha almost untouched, lowered kappa the most while the Rb-treatment at the same time increased alpha slightly and decreased rho the most. Compared to the untreated sample, Na- and Rb-treatments improved the dimensionless figure of merit ZT by ˜ 30% due to the reduced kappa and ˜ 38% owing to the improved the power factor PF, respectively. The grain boundary phase provides a new avenue by which one can potentially decouple the otherwise inter-related alpha, rho and kappa within one thermoelectric material. The morphologic investigation showed this surface layer lacked crystallinity, if any, and was possibly an

  3. Expanded sodalite-type metal-organic frameworks: increased stability and H(2) adsorption through ligand-directed catenation.

    PubMed

    Dinca, Mircea; Dailly, Anne; Tsay, Charlene; Long, Jeffrey R

    2008-01-07

    The torsion between the central benzene ring and the outer aromatic rings in 1,3,5-tri-p-(tetrazol-5-yl)phenylbenzene (H3TPB-3tz) and the absence of such strain in 2,4,6-tri-p-(tetrazol-5-yl)phenyl-s-triazine (H3TPT-3tz) are shown to allow the selective synthesis of noncatenated and catenated versions of expanded sodalite-type metal-organic frameworks. The reaction of H3TPB-3tz with CuCl2.2H2O affords the noncatenated compound Cu3[(Cu4Cl)3(TPB-3tz)8]2.11CuCl2.8H2O.120DMF (2), while the reaction of H3TPT-3tz with MnCl2.4H2O or CuCl2.2H2O generates the catenated compounds Mn3[(Mn4Cl)3(TPT-3tz)8]2.25H2O.15CH3OH.95DMF (3) and Cu3[(Cu4Cl)3(TPT-3tz)8]2.xsolvent (4). Significantly, catenation helps to stabilize the framework toward collapse upon desolvation, leading to an increase in the surface area from 1120 to 1580 m2/g and an increase in the hydrogen storage capacity from 2.8 to 3.7 excess wt % at 77 K for 2 and 3, respectively. The total hydrogen uptake in desolvated 3 reaches 4.5 wt % and 37 g/L at 80 bar and 77 K, demonstrating that control of catenation can be an important factor in the generation of hydrogen storage materials.

  4. Ohmic contact on n- and p-type ion-implanted 4H-SiC with low-temperature metallization process for SiC MOSFETs

    NASA Astrophysics Data System (ADS)

    Shimizu, Haruka; Shima, Akio; Shimamoto, Yasuhiro; Iwamuro, Noriyuki

    2017-04-01

    The ohmic contact on n- and p-type SiC regions with the same contact metal is a key process in regard to creating high-performance MOSFETs and insulated gate bipolar transistors (IGBTs). The dependence of the contact resistance on n- and p-type SiC regions on ion species, dose, and implantation temperature was investigated. The results of such an investigation revealed that the amorphization of the SiC surface and the generation of 3C-SiC produce a low contact resistance without the need for a high-temperature metallization process. The contact resistances of 2.1 × 10‑6 Ω cm2 on the n-type SiC region and 1.3 × 10‑3 Ω cm2 on the p-type SiC region were obtained with high-dose ion implantation at room temperature on the n-type SiC region, high-dose ion implantation at high temperature on the p-type SiC region, and a titanium-based contact electrode. A SiC MOSFET was fabricated with the low-temperature ohmic contact process. The positive-bias gate leakage current markedly increased. It can be deduced that high-dose ion implantation at room temperature on the n-type SiC region degrades surface roughness on the N+ source region.

  5. Surface display of metal fixation motifs of bacterial P1-type ATPases specifically promotes biosorption of Pb(2+) by Saccharomyces cerevisiae.

    PubMed

    Kotrba, Pavel; Ruml, Tomas

    2010-04-01

    Biosorption of metal ions may take place by different passive metal-sequestering processes such as ion exchange, complexation, physical entrapment, and inorganic microprecipitation or by a combination of these. To improve the biosorption capacity of the potential yeast biosorbent, short metal-binding NP peptides (harboring the CXXEE metal fixation motif of the bacterial Pb(2+)-transporting P1-type ATPases) were efficiently displayed and covalently anchored to the cell wall of Saccharomyces cerevisiae. These were fusions to the carboxyl-terminal part of the sexual adhesion glycoprotein alpha-agglutinin (AGalpha1Cp). Compared to yeast cells displaying the anchoring domain only, those having a surface display of NP peptides multiplied their Pb(2+) biosorption capacity from solutions containing a 75 to 300 microM concentration of the metal ion up to 5-fold. The S-type Pb(2+) biosorption isotherms, plus the presence of electron-dense deposits (with an average size of 80 by 240 nm, observed by transmission electron microscopy) strongly suggested that the improved biosorption potential of NP-displaying cells is due to the onset of microprecipitation of Pb species on the modified cell wall. The power of an improved capacity for Pb biosorption was also retained by the isolated cell walls containing NP peptides. Their Pb(2+) biosorption property was insensitive to the presence of a 3-fold molar excess of either Cd(2+) or Zn(2+). These results suggest that the biosorption mechanism can be specifically upgraded with microprecipitation by the engineering of the biosorbent with an eligible metal-binding peptide.

  6. THE EFFECT OF SECOND-GENERATION POPULATIONS ON THE INTEGRATED COLORS OF METAL-RICH GLOBULAR CLUSTERS IN EARLY-TYPE GALAXIES

    SciTech Connect

    Chung, Chul; Lee, Sang-Yoon; Yoon, Suk-Jin; Lee, Young-Wook

    2013-05-20

    The mean color of globular clusters (GCs) in early-type galaxies is in general bluer than the integrated color of halo field stars in host galaxies. Metal-rich GCs often appear more associated with field stars than metal-poor GCs, yet show bluer colors than their host galaxy light. Motivated by the discovery of multiple stellar populations in Milky Way GCs, we present a new scenario in which the presence of second-generation (SG) stars in GCs is responsible for the color discrepancy between metal-rich GCs and field stars. The model assumes that the SG populations have an enhanced helium abundance as evidenced by observations, and it gives a good explanation of the bluer optical colors of metal-rich GCs than field stars as well as strong Balmer lines and blue UV colors of metal-rich GCs. Ours may be complementary to the recent scenario suggesting the difference in stellar mass functions (MFs) as an origin for the GC-to-star color offset. A quantitative comparison is given between the SG and MF models.

  7. Distribution patterns of metals contamination in sediments based on type regional development on the intertidal coastal zones of the Persian Gulf, Iran.

    PubMed

    Kazemi, Ali; Bakhtiari, Alireza Riyahi; Kheirabadi, Nabiallah; Barani, Hashm; Haidari, Behnam

    2012-01-01

    This study was performed to determine the variation of metals concentrations (Pb, Cd, Zn, and Cu) in surface sediments based on type region development from ten sites on the intertidal coastal zone of the Persian Gulf, Iran. The metals concentrations in surface sediments varied from 0.86 to 180.78 μg g(-1) for Pb, 0.61 to 6.48 μg g(-1) for Cd, 5.99 to 44.42 μg g(-1) for Zn, and 3.01 to 43.33 μg g(-1) for Cu. The quality of the sediments was evaluated based on sediment quality guidelines (effects range-low (ERL) and effects range-medium (ERM) indexes. Biological effects criteria suggest that metals concentrations in sediments were lower than ERM for all sites, but for some sites metals concentrations in sediments were higher than ERL. The present results support the concept that human activities in each region could be a major source of metals pollution input in the aquatic environment.

  8. INTEGRAL FIELD SPECTROSCOPY OF SUPERNOVA EXPLOSION SITES: CONSTRAINING THE MASS AND METALLICITY OF THE PROGENITORS. II. TYPE II-P AND II-L SUPERNOVAE

    SciTech Connect

    Kuncarayakti, Hanindyo; Maeda, Keiichi; Doi, Mamoru; Morokuma, Tomoki; Hashiba, Yasuhito; Aldering, Greg; Arimoto, Nobuo; Pereira, Rui

    2013-08-01

    Thirteen explosion sites of Type II-P and II-L supernovae (SNe) in nearby galaxies have been observed using integral field spectroscopy, enabling both spatial and spectral study of the explosion sites. We used the properties of the parent stellar population of the coeval SN progenitor star to derive its metallicity and initial mass. The spectrum of the parent stellar population yields estimates of metallicity via the strong-line method and age via a comparison with simple stellar population models. These metallicity and age parameters are adopted for the progenitor star. Age, or lifetime of the star, was used to derive the initial (zero-age main sequence) mass of the star using comparisons with stellar evolution models. With this technique, we were able to determine the metallicities and initial masses of the SN progenitors in our sample. Our results indicate that some Type II SN progenitors may have been stars with masses comparable to those of SN Ib/c progenitors.

  9. Contribution of heavy metals to toxicity of coal combustion related fine particulate matter (PM2.5) in Caenorhabditis elegans with wild-type or susceptible genetic background.

    PubMed

    Sun, Lingmei; Wu, Quli; Liao, Kai; Yu, Peihang; Cui, Qiuhong; Rui, Qi; Wang, Dayong

    2016-02-01

    Contribution of chemical components in coal combustion related fine particulate matter (PM2.5) to its toxicity is largely unclear. We focused on heavy metals in PM2.5 to investigate their contribution to toxicity formation in Caenorhabditis elegans. Among 8 heavy metals examined (Fe, Zn, Pb, As, Cd, Cr, Cu, and Ni), Pb, Cr, and Cu potentially contributed to PM2.5 toxicity in wild-type nematodes. Combinational exposure to any two of these three heavy metals caused higher toxicity than exposure to Pb, Cr, or Cu alone. Toxicity from the combinational exposure to Pb, Cr, and Cu at the examined concentrations was higher than exposure to PM2.5 (100 mg/L). Moreover, mutation of sod-2 or sod-3 gene encoding Mn-SOD increased susceptibility in nematodes exposed to Fe, Zn, or Ni, although Fe, Zn, or Ni at the examined concentration did not lead to toxicity in wild-type nematodes. Our results highlight the potential contribution of heavy metals to PM2.5 toxicity in environmental organisms.

  10. Three new extended Preyssler-type polyoxometalates modified by transition metal-2,2 Prime -biimidazole complexes

    SciTech Connect

    Yang, Chun-Yue; Zhang, Lan-Cui; Wang, Zan-Jiao; Wang, Lin; Li, Xiao-Hui; Zhu, Zai-Ming

    2012-10-15

    Three extended Preyssler-type ({l_brace}P{sub 5}W{sub 30}{r_brace}) polyoxometalates modified by transition metal (TM)-2,2 Prime -biimidazole (abbreviated as H{sub 2}biim) complexes, namely [Mn(H{sub 2}biim){sub 3}]{sub 5}H{sub 2}[{l_brace}Mn(H{sub 2}biim){sub 2}(H{sub 2}O){r_brace} (NaP{sub 5}W{sub 30}O{sub 110})]{center_dot}39H{sub 2}O (1), [{l_brace}(H{sub 2}biim){sub 2}Zn({mu}-OH)Zn(H{sub 2}biim)({mu}-H{sub 2}biim)Zn(H{sub 2}biim)(H{sub 2}O){r_brace}{sub 2}H{sub 4}(NaP{sub 5}W{sub 30}O{sub 110})]{center_dot}22 H{sub 2}O (2), and {l_brace}(H{sub 4}biim){sub 18}NaH{sub 5}[({mu}-Fe(H{sub 3}biim)(H{sub 2}O){sub 3})({mu}-Fe(H{sub 2}O){sub 4})(NaP{sub 5}W{sub 30}O{sub 110}){sub 2}]{sub 2}{center_dot}78H{sub 2}O{r_brace}{sub n} (3) have been hydrothermally synthesized, and characterized by physicochemical and spectroscopic methods. Their catalytic activities have been investigated. 1 contains mono-supporting {l_brace}P{sub 5}W{sub 30}{r_brace} anions. In compound 2, a {l_brace}P{sub 5}W{sub 30}{r_brace} anion is bi-supported by two symmetrical chains constructed by trinuclear zinc complexes. Compound 3 is composed of infinite 1-D zigzag chains built up of {l_brace}P{sub 5}W{sub 30}{r_brace} polyoxoanions linked via [Fe(H{sub 2}O){sub 4}]{sup 3+} and [Fe(H{sub 3}biim)(H{sub 2}O){sub 3}]{sup 4+} fragments. H{sub 2}biim ligands adopt three coordination modes in the structure. All these compounds have 3-D supramolecular frameworks via extensive hydrogen-bonding interactions. - Graphical abstract: Three new extended Preyssler-type polyoxometalates modified by TM-2,2 Prime -biimidazole complexes are obtained, they display high thermal stabilities. Highlights: Black-Right-Pointing-Pointer Three new extended Preyssler-type polyoxometalates were hydrothermally synthesized. Black-Right-Pointing-Pointer An interesting trinuclear zinc-2,2 Prime -biimidazole-polyanion complex was obtained. Black-Right-Pointing-Pointer The huge {l_brace}P{sub 5}W{sub 30}{r_brace} clusters were

  11. Optimization of Metal Coverage on the Emitter in n-Type Interdigitated Back Contact Solar Cells Using a PC2D Simulation

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Chen, Chen; Jia, Rui; Janssen, G. J. M.; Zhang, Dai-Sheng; Xing, Zhao; Bronsveld, P. C. P.; Weeber, A. W.; Jin, Zhi; Liu, Xin-Yu

    2013-07-01

    In interdigitated back contact (IBC) solar cells, the metal-electrode coverage on a p-type emitter is optimized by a PC2D simulation. The result shows that the variation of the metal coverage ratio (MCR) will affect both the surface passivation and the electrode-contact properties for the p-type emitter in IBC solar cells. We find that when Rc ranges from 0.08 to 0.16Ω·cm2, the MCR is optimized with a value of 25% and 33%, resulting in a highest energy-conversion efficiency. The dependences of both Voc and fill factor on MCR are simulated in order to explore the mechanism of the IBC solar cells.

  12. Steady-state characteristics and transient response of MgZnO-based metal-semiconductor-metal solar-blind ultraviolet photodetector with three types of electrode structures.

    PubMed

    Wang, Ping; Zhen, Qinghong; Tang, Qing; Yang, Yintang; Guo, Lixin; Ding, Kai; Huang, Feng

    2013-07-29

    Detailed studies of MgZnO-based metal-semiconductor-metal (MSM) solar-blind ultraviolet photodetector with different electrode structures are performed. A two-dimensional physical model is established based on the Poisson's equation and time-dependent continuity equations, which is verified by our experimental data of conventional electrode MSM detector. The steady-state characteristics and transient response of semicircular and triangular electrode MSM detectors are also investigated by this model. Compared with the conventional electrode, semicircular and triangular electrode devices exhibit a substantial improvement on the photocurrent. At a bias of 10 V, the steady-state saturated photocurrents for semicircular and triangular electrode devices are 14.69 nA and 24.37 nA respectively, corresponding to a 20.5% and 100% increase over the conventional electrode detector. Meanwhile, the transient peak photocurrents reach 31.38 nA and 52.09 nA respectively, both of which are notably larger than that of conventional device.

  13. Y-configured metallic stent combined with 125I seed strands cavity brachytherapy for a patient with type IV Klatskin tumor

    PubMed Central

    Dechao, Jiao; Yanli, Wang; Zhen, Li

    2016-01-01

    We report a case in an inoperable patient with type IV Klatskin tumor treated by the use of a novel, two piece, Y-configured self-expandable metallic stent (SEMS) combined with two 125I seed strands via bilateral approach. The placement of the Y-shaped SEMS was successful and resulted in adequate biliary drainage. After 2 months of intraluminal brachytherapy (ILBT), both 125I seed strands and temporary drainage catheter were removed after patency of the expanded stents was confirmed by the cholangiogram. This technique was feasible and could be considered for the treatment of patients with Bismuth type IV Klatskin tumors. PMID:27648091

  14. Concentration of some heavy metals in rice types available in Shiraz market and human health risk assessment.

    PubMed

    Naseri, Mahmood; Vazirzadeh, Arya; Kazemi, Robabeh; Zaheri, Farnaz

    2015-05-15

    This investigation was conducted to survey the levels of some heavy metals such as cadmium, lead, chromium, nickel and cobalt in domestic cultivated and imported rice sold on the Shiraz - Iran markets. The potential human health risk assessment was conducted by considering estimated weekly intake (EWI) of toxic metals from eating rice and compared calculated values with provisional tolerable weekly intake (PTWI). The mean values for lead and cadmium in domestic cultivated and imported rice were considerably higher than allowable limits set by FAO/WHO. In combination of recent rice consumption data, the estimated weekly intakes of toxic element were calculated for Iranian population. EWI for cadmium, nickel, chromium through imported and domestic cultivated rice consumption was lower than the PTWI. The EWI for lead were considerably higher than other measured toxic metals. The highest mean level of EWI for lead was observed in some imported rice samples (25.76 μg/kg body weight).

  15. Investigation of trap properties in high-k/metal gate p-type metal-oxide-semiconductor field-effect-transistors with aluminum ion implantation using random telegraph noise analysis

    SciTech Connect

    Kao, Tsung-Hsien; Chang, Shoou-Jinn Fang, Yean-Kuen; Huang, Po-Chin; Wu, Chung-Yi; Wu, San-Lein

    2014-08-11

    In this study, the impact of aluminum ion implantation (Al I/I) on random telegraph noise (RTN) in high-k/metal gate (HK/MG) p-type metal-oxide-semiconductor field-effect-transistors (pMOSFETs) was investigated. The trap parameters of HK/MG pMOSFETs with Al I/I, such as trap energy level, capture time and emission time, activation energies for capture and emission, and trap location in the gate dielectric, were determined. The configuration coordinate diagram was also established. It was observed that the implanted Al could fill defects and form a thin Al{sub 2}O{sub 3} layer and thus increase the tunneling barrier height for holes. It was also observed that the trap position in the Al I/I samples was lower due to the Al I/I-induced dipole at the HfO{sub 2}/SiO{sub 2} interface.

  16. Synthesis and nanorod growth of n-type phthalocyanine on ultrathin metal films by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Koshiba, Yasuko; Nishimoto, Mihoko; Misawa, Asuka; Misaki, Masahiro; Ishida, Kenji

    2016-03-01

    The thermal behavior of 1,2,4,5-tetracyanobenzene (TCNB), the synthesis of metal-2,3,9,10,16,17,23,24-octacyanophthalocyanine-metal [MPc(CN)8-M] (M = Cu, Fe, Ni) complexes by the tetramerization of TCNB, and the growth of MPc(CN)8-M nanorods were investigated. By chemical vapor deposition (CVD) in vacuum, MPc(CN)8 molecules were synthesized and MPc(CN)8-M nanorods were formed on all substrates. Among them, CuPc(CN)8 molecules were synthesized in high yield, and CuPc(CN)8-Cu nanorods were deposited uniformly and in high density, with diameters and lengths of 70-110 and 200-700 nm, respectively. The differences in the growth of MPc(CN)8-M nanorods were mainly attributed to the stability of the MPc(CN)8-M complex, the oxidation of ultrathin metal films, and the diffusion of metal atoms. Additionally, the tetramerization of TCNB by CVD at atmospheric pressure was performed on ultrathin Cu films, and the synthesis of CuPc(CN)8 molecules was observed by in situ UV-vis spectroscopy. CVD under atmospheric pressure is also useful for the synthesis of CuPc(CN)8 molecules.

  17. Amino acid-type interactions of L-3,4-dihydroxyphenylalanine with transition metal ions: An experimental and theoretical investigation

    NASA Astrophysics Data System (ADS)

    Mandal, Shilpi; Das, Gunajyoti; Askari, Hassan

    2015-11-01

    This paper reports the synthesis of the Ni+2, Cu+2 and Zn+2 complexes of L-3,4-dihydroxyphenylalanine (L-dopa) using a solvent-free solid-state grinding procedure. The synthesized complexes are characterized by elemental, molar conductance, EDAX-SEM, TG/DTA, infrared, electronic absorption, fluorescence and XRD analyses; confirming a 1:2 metal-ligand stoichiometry of the complexes and involvement of the carboxyl and amino groups in complex formation. Phase-diagram and the kinetic parameters of the interactions between L-dopa and the metal ions are also explored. Molecular structures of the metal complexes are modeled within the framework of density functional theory in a vacuum and implicit aqueous environment using the most stable L-dopa conformers determined at the MP2/6-311++G(d,p) level. The gas and aqueous phase metal-binding affinities; theoretical IR and UV-vis spectral aspects; partial atomic charges; Wiberg bond indices; HOMO-LUMO energy gaps and dipole moments of the L-dopa conformers as well as their complexes are calculated and analyzed at B3LYP/6-311++G(d,p) level. The singlet state of the Ni(L-dopa)2 complex is found to be more favorable from thermodynamic perspectives as compared to the triplet state. Use of BHandHLYP and dispersion-corrected B3LYP (at DFT-D2 level) methods in conjugation with the 6-311++G(d,p) basis set affords us to accurately predict the binding affinity order of the three Lewis acids investigated, assess the influence of metal-aromatic π interactions on the thermodynamic stability of metalated L-dopa, and explore the effectiveness of the aforesaid methodologies in predicting a certain set of spectral and electronic properties of bioactive molecules. UV-vis titration and docking studies reveal that the metal complexes of L-dopa are able to bind to the surface of DNA.

  18. Effect of Heat Treatment on Low Temperature Toughness of Reduced Pressure Electron Beam Weld Metal of Type 316L Stainless Steel

    SciTech Connect

    Nakagawa, H.; Fujii, H.; Tamura, M.

    2006-03-31

    Austenitic stainless steels are considered to be the candidate materials for liquid hydrogen vessels and the related equipments, and those welding parts that require high toughness at cryogenic temperature. The authors have found that the weld metal of Type 316L stainless steel processed by reduced pressure electron beam (RPEB) welding has high toughness at cryogenic temperature, which is considered to be due to the single-pass welding process without reheating effect accompanied by multi-pass welding process.In this work, the effect of heat treatment on low temperature toughness of the RPEB weld metal of Type 316L was investigated by Charpy impact test at 77K. The absorbed energy decreased with higher temperature and longer holding time of heat treatment. The remarkable drop in the absorbed energy was found with heat treatment at 1073K for 2 hours, which is as low as that of conventional multi-pass weld metal such as tungsten inert gas welding. The observations of fracture surface and microstructure revealed that the decrease in the absorbed energy with heat treatment resulted from the precipitation of intermetallic compounds near delta-ferrite phase.

  19. Delayed-Type Hypersensitivity to Metals of Environmental Burden in Patients with Takotsubo Syndrome – Is There a Clinical Relevance?

    PubMed Central

    Manousek, Jan; Stejskal, Vera; Kubena, Petr; Jarkovsky, Jiri; Nemec, Petr; Lokaj, Petr; Dostalova, Ludmila; Zadakova, Andrea; Pavlusova, Marie; Benesova, Klara; Kala, Petr; Miklik, Roman; Spinar, Jindrich; Parenica, Jiri

    2016-01-01

    Objective Takotsubo syndrome (TS) is a heart condition characterised by a sudden transient left ventricular dysfunction; its pathophysiology is probably associated with elevated levels of catecholamines but the exact mechanism is not known as yet. Literature and clinical experience suggest that TS affects persons with various comorbidities. This pilot work aims to evaluate the frequency of comorbidities with potential pathological immune reactivity, and to evaluate the potential association between TS and hypersensitivity to metals assessed by LTT-MELISA®. Methodology, Results A total of 24 patients (23 women, 1 man) with a history of TS attack and 27 healthy controls were evaluated. Hypersensitivity was evaluated by a lymphocyte transformation test (LTT-MELISA®); a questionnaire of environmental burden was used to select evaluated metals. A total of 19 patients (79%) had at least one condition that might potentially be associated with pathological immune reactivity (autoimmune thyroid disease, drug allergy, bronchial asthma, cancer, contact dermatitis, rheumatoid arthritis). Hypersensitivity to metals was identified significantly more frequently in TS patients than in healthy controls (positive reaction to at least one metal was identified in 95.8% of TS patients and in 59.3% of controls; p = 0.003); the difference was statistically significant for mercury (45.8% and 14.8%, respectively; p = 0.029). Conclusion Our work shows that conditions with pathological immune reactivity occur frequently in TS patients, and our data suggest a possible association between TS and hypersensitivity to metals (mercury in particular) evaluated by LTT-MELISA®. We also suggest that apart from the triggering stress factor, potential existence of other serious conditions should be considered when taking medical history of TS patients. PMID:27824862

  20. Cloning and expression analysis of SKn-type dehydrin gene from bean in response to heavy metals.

    PubMed

    Zhang, Yuxiu; Li, Jinmei; Yu, Fei; Cong, Lin; Wang, Liyan; Burkard, Gérard; Chai, Tuanyao

    2006-03-01

    A heavy metal responsive gene PvSR3 (GenBank accession number U54703) encoding an acid dehydrin was isolated from a mercuric chloride-treated bean (Phaseolus vulgaris L.) leaf cDNA library by differential screening using cDNAs derived from treated and untreated plants. The PvSR3 cDNA is 981-bp long and has a 606-bp open-reading frame with a 202-residue-deduced amino acid sequence. The PvSR3 sequence contains two conserved repeats of the characteristic lysine-rich K segment (EKKGIMDKIKEKLPG) preceded by an 8-serine residue stretch, whereas the Y segment (DEYGNP) conserved motif is absent. The deduced protein has a calculated molecular weight of 23 kDa and an isoelectric point of 5.2. Sequence similarity and comparative analysis showed that PvSR3 shares 70 and 73% similarity with the dehydrin of poplar and pepper, respectively. Southern hybridizations indicated that PvSR3 was a low copy-number gene. Northern blot analysis revealed that PvSR3 mRNA was weakly detected in seedling leaves. However, the gene expression was strongly stimulated by heavy metals, such as mercury, cadmium, arsenic, and copper, whereas virus infection and salt had little effect on it. In contrast, PvSR3 was not responsive to drought or abscisic acid (ABA), and was downregulated by UV radiation. Furthermore, PvSR3 was upregulated by the exogenous signaling molecules, including salicylic acid (SA) and hydrogen peroxide (H2O2). It is suggested that PvSR3 is extremely related to heavy metal stress, and might play an important role in metal detoxification and resistance to the damage caused by heavy metals.

  1. Fabrication of a metal-oxide-semiconductor-type capacitive microtip array using SiO2 or HfO2 gate insulators

    NASA Astrophysics Data System (ADS)

    Kim, Kyung-Min; Choi, Byung Joon; Kim, Seong Keun; Hwang, Cheol Seong

    2004-11-01

    Capacitive tip arrays having a metal-insulator-semiconductor capacitor structure were fabricated using thermally oxidized SiO2 or atomic-layer-deposited HfO2 gate dielectric films for their application to scanning-probe-array-type memory devices. The SiO2 film showed a nonuniform thickness distribution over the flat and tip areas of the arrays owing to the different oxidation speeds of the flat and tip Si surfaces. This resulted in a smaller sensing margin of the device. However, the high-dielectric HfO2 film showed not only a higher capacitance value but also a more uniform growth behavior over the whole area, which would result in a better device performance. The capacitance-voltage characteristics of both devices coincide well with the simulation results based on conventional metal-insulator-semiconductor theories.

  2. Removal of toxic and alkali/alkaline earth metals during co-thermal treatment of two types of MSWI fly ashes in China.

    PubMed

    Yu, Jie; Qiao, Yu; Jin, Limei; Ma, Chuan; Paterson, Nigel; Sun, Lushi

    2015-12-01

    This study aims to vaporize heavy metals and alkali/alkaline earth metals from two different types of fly ashes by thermal treatment method. Fly ash from a fluidized bed incinerator (HK fly ash) was mixed with one from a grate incinerator (HS fly ash) in various proportions and thermally treated under different temperatures. The melting of HS fly ash was avoided when treated with HK fly ash. Alkali/alkaline earth metals in HS fly ash served as Cl-donors to promote the vaporization of heavy metals during thermal treatment. With temperature increasing from 800 to 900°C, significant amounts of Cl, Na and K were vaporized. Up to 1000°C in air, less than 3% of Cl and Na and less than 5% of K were retained in ash. Under all conditions, Cd can be vaporized effectively. The vaporization of Pb was mildly improved when treated with HS fly ash, while the effect became less pronounced above 900°C. Alkali/alkaline earth metals can promote Cu vaporization by forming copper chlorides. Comparatively, Zn vaporization was low and only slightly improved by HS fly ash. The low vaporization of Zn could be caused by the formation of Zn2SiO4, ZnFe2O4 and ZnAl2O4. Under all conditions, less than 20% of Cr was vaporized. In a reductive atmosphere, the vaporization of Cd and Pb were as high as that in oxidative atmosphere. However, the vaporization of Zn was accelerated and that of Cu was hindered because the formation of Zn2SiO4, ZnFe2O4 and ZnAl2O4 and copper chloride was depressed in reductive atmosphere.

  3. 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

  4. Electron dose distributions caused by the contact-type metallic eye shield: Studies using Monte Carlo and pencil beam algorithms

    SciTech Connect

    Kang, Sei-Kwon; Yoon, Jai-Woong; Hwang, Taejin; Park, Soah; Cheong, Kwang-Ho; Jin Han, Tae; Kim, Haeyoung; Lee, Me-Yeon; Ju Kim, Kyoung Bae, Hoonsik

    2015-10-01

    A metallic contact eye shield has sometimes been used for eyelid treatment, but dose distribution has never been reported for a patient case. This study aimed to show the shield-incorporated CT-based dose distribution using the Pinnacle system and Monte Carlo (MC) calculation for 3 patient cases. For the artifact-free CT scan, an acrylic shield machined as the same size as that of the tungsten shield was used. For the MC calculation, BEAMnrc and DOSXYZnrc were used for the 6-MeV electron beam of the Varian 21EX, in which information for the tungsten, stainless steel, and aluminum material for the eye shield was used. The same plan was generated on the Pinnacle system and both were compared. The use of the acrylic shield produced clear CT images, enabling delineation of the regions of interest, and yielded CT-based dose calculation for the metallic shield. Both the MC and the Pinnacle systems showed a similar dose distribution downstream of the eye shield, reflecting the blocking effect of the metallic eye shield. The major difference between the MC and the Pinnacle results was the target eyelid dose upstream of the shield such that the Pinnacle system underestimated the dose by 19 to 28% and 11 to 18% for the maximum and the mean doses, respectively. The pattern of dose difference between the MC and the Pinnacle systems was similar to that in the previous phantom study. In conclusion, the metallic eye shield was successfully incorporated into the CT-based planning, and the accurate dose calculation requires MC simulation.

  5. Strength of semiconductors, metals, and ceramics evaluated by a microscopic cleavage model with Morse-type and Lennard-Jones-type interaction

    SciTech Connect

    Hess, Peter

    2014-08-07

    An improved microscopic cleavage model, based on a Morse-type and Lennard-Jones-type interaction instead of the previously employed half-sine function, is used to determine the maximum cleavage strength for the brittle materials diamond, tungsten, molybdenum, silicon, GaAs, silica, and graphite. The results of both interaction potentials are in much better agreement with the theoretical strength values obtained by ab initio calculations for diamond, tungsten, molybdenum, and silicon than the previous model. Reasonable estimates of the intrinsic strength are presented for GaAs, silica, and graphite, where first principles values are not available.

  6. Strength and deformability of compressed concrete elements with various types of non-metallic fiber and rods reinforcement under static loading

    NASA Astrophysics Data System (ADS)

    Nevskii, A. V.; Baldin, I. V.; Kudyakov, K. L.

    2015-01-01

    Adoption of modern building materials based on non-metallic fibers and their application in concrete structures represent one of the important issues in construction industry. This paper presents results of investigation of several types of raw materials selected: basalt fiber, carbon fiber and composite fiber rods based on glass and carbon. Preliminary testing has shown the possibility of raw materials to be effectively used in compressed concrete elements. Experimental program to define strength and deformability of compressed concrete elements with non-metallic fiber reinforcement and rod composite reinforcement included design, manufacture and testing of several types of concrete samples with different types of fiber and longitudinal rod reinforcement. The samples were tested under compressive static load. The results demonstrated that fiber reinforcement of concrete allows increasing carrying capacity of compressed concrete elements and reducing their deformability. Using composite longitudinal reinforcement instead of steel longitudinal reinforcement in compressed concrete elements insignificantly influences bearing capacity. Combined use of composite rod reinforcement and fiber reinforcement in compressed concrete elements enables to achieve maximum strength and minimum deformability.

  7. High-output-power densities from molecular beam epitaxy grown n- and p-type PbTeSe-based thermoelectrics via improved contact metallization

    NASA Astrophysics Data System (ADS)

    Goodhue, W. G.; Reeder, R. E.; Vineis, C. J.; Calawa, S. D.; Dauplaise, H. M.; Vangala, S.; Walsh, M. P.; Harman, T. C.

    2012-05-01

    Electrical power densities of up to 33 W/cm2 and up to 12 W/cm2 were obtained for n-type and p-type PbTeSe-based stand-alone thermoelectric devices, respectively, at modest temperature gradients of ˜200 °C (Tcold = 25 °C). These large power densities were enabled by greatly improving electrical contact resistivities in the thermoelectric devices. Electrical contacts with contact resistivities as low as 3.9 × 10-6 Ω cm2 and 4.0 × 10-6 Ω cm2 for n- and p-type telluride-based- materials, respectively, were developed by investigating several metallization schemes and contact layer doping/alloy combinations, in conjunction with a novel contact application process. This process exposes heated semiconductor surfaces to an atomic hydrogen flux under high vacuum for surface cleaning (oxide and carbon removal), followed immediately by an in-situ electron-beam evaporation of the metal layers.

  8. High-output-power densities from molecular beam epitaxy grown n- and p-type PbTeSe-based thermoelectrics via improved contact metallization

    SciTech Connect

    Goodhue, W. G.; Reeder, R. E.; Vineis, C. J.; Calawa, S. D.; Walsh, M. P.; Harman, T. C.; Dauplaise, H. M.; Vangala, S.

    2012-05-15

    Electrical power densities of up to 33 W/cm{sup 2} and up to 12 W/cm{sup 2} were obtained for n-type and p-type PbTeSe-based stand-alone thermoelectric devices, respectively, at modest temperature gradients of {approx}200 deg. C (T{sub cold}= 25 deg. C). These large power densities were enabled by greatly improving electrical contact resistivities in the thermoelectric devices. Electrical contacts with contact resistivities as low as 3.9 x 10{sup -6}{Omega} cm{sup 2} and 4.0 x 10{sup -6}{Omega} cm{sup 2} for n- and p-type telluride-based- materials, respectively, were developed by investigating several metallization schemes and contact layer doping/alloy combinations, in conjunction with a novel contact application process. This process exposes heated semiconductor surfaces to an atomic hydrogen flux under high vacuum for surface cleaning (oxide and carbon removal), followed immediately by an in-situ electron-beam evaporation of the metal layers.

  9. Merging open metal sites and Lewis basic sites in a NbO-type metal-organic framework for improved C2H2/CH4 and CO2/CH4 separation.

    PubMed

    Song, Chengling; Hu, Jiayi; Ling, Yajing; Feng, Yunlong; Chen, De-Li; He, Yabing

    2015-09-07

    A new three-dimensional NbO-type porous metal-organic framework ZJNU-47 was synthesized via a solvothermal reaction of Cu(NO3)2·3H2O and a Lewis basic nitrogen donor site-rich tetracarboxylate, namely, 5,5'-(pyridazine-3,6-diyl)-diisophthalate, and the structure was characterized by single-crystal X-ray diffraction to be isostructural with NOTT-101. With the synergistic effect of open metal sites, Lewis basic sites and a suitable pore space, the MOF material ZJNU-47a after activation can take up a large amount of C2H2 and CO2. The gravimetric C2H2 uptake of 214 cm(3) (STP) g(-1) at room temperature and 1 atm is the highest among all reported MOFs to date, and the gravimetric CO2 uptake of 108 cm(3) (STP) g(-1) is also among the highest reported for MOFs. Compared to the isostructural MOF NOTT-101a, ZJNU-47a exhibits a significant increase in C2H2 and CO2 uptake and thus improved C2H2/CH4 and CO2/CH4 separations. Significantly, comprehensive DFT studies of C2H2 and CO2 adsorption have revealed that the open nitrogen donor sites are comparable and even superior to open metal sites regarding the adsorption sites. This work demonstrated that the simultaneous introduction of Lewis basic nitrogen donor sites and Lewis acidic metal sites into the framework is a promising approach to improve the gas sorption toward CO2 and C2H2 and thus to produce materials possessing enhanced C2H2/CH4 and CO2/CH4 separation performance.

  10. Anomalous output characteristic shift for the n-type lateral diffused metal-oxide-semiconductor transistor with floating P-top layer

    SciTech Connect

    Liu, Siyang; Zhang, Chunwei; Sun, Weifeng; Su, Wei; Wang, Shaorong; Ma, Shulang; Huang, Yu

    2014-04-14

    Anomalous output characteristic shift of the n-type lateral diffused metal-oxide-semiconductor transistor with floating P-top layer is investigated. It shows that the linear drain current has obvious decrease when the output characteristic of fresh device is measured for two consecutive times. The charge pumping experiments demonstrate that the decrease is not from hot-carrier degradation. The reduction of cross section area for the current flowing, which results from the squeezing of the depletion region surrounding the P-top layer, is responsible for the shift. Consequently, the current capability of this special device should be evaluated by the second measured output characteristic.

  11. Comparison of junctionless and inversion-mode p-type metal-oxide-semiconductor field-effect transistors in presence of hole-phonon interactions

    SciTech Connect

    Dib, E.; Carrillo-Nuñez, H.; Cavassilas, N.; Bescond, M.

    2016-01-28

    Junctionless transistors are being considered as one of the alternatives to conventional metal-oxide field-effect transistors. In this work, it is then presented a simulation study of silicon double-gated p-type junctionless transistors compared with its inversion-mode counterpart. The quantum transport problem is solved within the non-equilibrium Green's function formalism, whereas hole-phonon interactions are tackled by means of the self-consistent Born approximation. Our findings show that junctionless transistors should perform as good as a conventional transistor only for ultra-thin channels, with the disadvantage of requiring higher supply voltages in thicker channel configurations.

  12. Density-functional study of perovskite-type hydride LiNiH3 and its synthesis: Mechanism for formation of metallic perovskite

    NASA Astrophysics Data System (ADS)

    Takagi, Shigeyuki; Saitoh, Hiroyuki; Endo, Naruki; Sato, Ryutaro; Ikeshoji, Tamio; Matsuo, Motoaki; Miwa, Kazutoshi; Aoki, Katsutoshi; Orimo, Shin-ichi

    2013-03-01

    A metallic perovskite-type hydride LiNiH3 was synthesized based on first-principles prediction. We theoretically examined its electronic structure and found that half of the Ni-H derived antibonding states are occupied and that the modest thermodynamic stability depends on a delicate balance between (i) destabilization and (ii) alleviation of compression frustration in corner-sharing octahedra, both of which arise from occupation of antibonding states. Through density-functional analyses of the electronic structure and lattice instability extending over LiTH3 series (T = Fe, Co, Ni, and Cu), we showed that the balance is in fact reflected in their thermodynamic stability.

  13. Rapid and efficient treatment of wastewater with high-concentration heavy metals using a new type of hydrogel-based adsorption process.

    PubMed

    Zhou, Guiyin; Liu, Chengbin; Chu, Lin; Tang, Yanhong; Luo, Shenglian

    2016-11-01

    In this study, a new type of double-network hydrogel sorbent was developed to remove heavy metals in wastewater. The amino-functionalized Starch/PAA hydrogel (NH2-Starch/PAA) could be conducted in a wide pH and the adsorption process could rapidly achieve the equilibrium. The adsorption capacity got to 256.4mg/g for Cd(II). Resultantly, even though Cd(II) concentration was as high as 180mg/L, the Cd(II) could be entirely removed using 1g/L sorbent. Furthermore, the desirable mechanical durability of the adsorbent allowed easy separation and reusability. In the fixed-bed column experiments, the treatment volume of the effluent with a high Cd(II) concentration of 200mg/L reached 2400BV (27.1L) after eight times cycle. The NH2-Starch/PAA overcame the deficiency of conventional sorbents that could not effectively treat the wastewater with relatively high metal concentrations. This work provides a new insight into omnidirectional enhancement of sorbents for removing high-concentration heavy metals in wastewater.

  14. Metal-doped inorganic nanoparticles for multiplex detection of biomarkers by a sandwich-type ICP-MS immunoassay.

    PubMed

    Ko, Jung Aa; Lim, H B

    2016-09-28

    Metal-doped inorganic nanoparticles were synthesized for the multiplex detection of biomarkers by a sandwich-type inductively coupled plasma mass spectrometry (ICP-MS) immunoassay. The synthesized Cs-doped multicore magnetic nanoparticles (MMNPs) were used not only for magnetic extraction of targets but also for ratiometric measurement in ICP-MS. In addition, three different metal/dye-doped silica nanoparticles (SNPs) were synthesized as probes for multiplex detection: Y/RhBITC (rhodamine B isothiocyanate)-doped SNPs for CRP (cardiovascular disease), Cd/RhBITC-doped SNPs for AFP (tumor), and Au/5(6)-XRITC (X-rhodamine-5-(and-6)-isothiocyanate)-doped SNPs for NSE (heart disease). For quantification, the doped metals of SNPs were measured by ICP-MS and then the signal ratio to Cs of MMNPs was plotted with respect to the concentration of targets by a ratiometry. Limits of detection (LOD) of 0.35 ng/mL to 77 ng mL(-1) and recoveries of 83%-125% were obtained for serum samples spiked with the biomarkers. Since no sample treatment was necessary prior to the extraction, the proposed method provided short analysis time and convenience for the multiplex determination of biomarkers, which will be valuable for clinical application.

  15. Structure of Human J-type Co-chaperone HscB Reveals a Tetracysteine Metal-binding Domain*S⃞

    PubMed Central

    Bitto, Eduard; Bingman, Craig A.; Bittova, Lenka; Kondrashov, Dmitry A.; Bannen, Ryan M.; Fox, Brian G.; Markley, John L.; Phillips, George N.

    2008-01-01

    Iron-sulfur proteins play indispensable roles in a broad range of biochemical processes. The biogenesis of iron-sulfur proteins is a complex process that has become a subject of extensive research. The final step of iron-sulfur protein assembly involves transfer of an iron-sulfur cluster from a cluster-donor to a cluster-acceptor protein. This process is facilitated by a specialized chaperone system, which consists of a molecular chaperone from the Hsc70 family and a co-chaperone of the J-domain family. The 3.0Å crystal structure of a human mitochondrial J-type co-chaperone HscB revealed an L-shaped protein that resembles Escherichia coli HscB. The important difference between the two homologs is the presence of an auxiliary metal-binding domain at the N terminus of human HscB that coordinates a metal via the tetracysteine consensus motif CWXCX9–13FCXXCXXXQ. The domain is found in HscB homologs from animals and plants as well as in magnetotactic bacteria. The metal-binding site of the domain is structurally similar to that of rubredoxin and several zinc finger proteins containing rubredoxin-like knuckles. The normal mode analysis of HscB revealed that this L-shaped protein preferentially undergoes a scissors-like motion that correlates well with the conformational changes of human HscB observed in the crystals. PMID:18713742

  16. Preparation, structures and antimicrobial activity of four different type metal complexes on the base of diethanolamine and o-nitrobenzoic acid

    NASA Astrophysics Data System (ADS)

    Ibragimov, A. B.; Ashurov, J. M.; Ibragimov, B. T.; Zakirov, B. S.

    2017-01-01

    Crystallization under identical conditions from aqueous ethanol solutions of diethanolamine (DEA), o-nitrobenzoic acid (ONBA) and definite metal salt yields 4 different type metal complexes and one organic salt - the monoligand complex of Zn(II) with DEA (1), monoligand complex of Cu(II) with ONBA (2), mixed-ligand complex of Ni(II) with DEA and ONBA (3), supramolecular complex between monoligand complex molecule of Zn(II) with DEA and ONBA (4) and DEA+·ONBA- salt (5). In 1 two meridionally distributed DEA molecules are coordinated by a tridentate mode, 2 is a binuclear copper complex with 4 ONBA molecules which are bidentately coordinated through carboxylate groups. In 3 two DEA and two ONBA molecules are coordinated by bidentate and monodentate fashions, respectively. The compound 4 consists of a complex molecule with two facial distributed tridentate DEA molecules and ONBA ones in an outer sphere. Hence, in coordination compounds 1 and 4 Zn-complex ions with two tridentately coordinated DEA molecules are found in different isomeric forms of which a mer-distribution is recorded for the first time. The maximal enhancement of the ligands antimicrobial activity is observed for the mixed-ligand metal complex. The Zn-complex with mer-distributed ligand molecules demonstrated more antimicrobial activity in contrast to fac-isomer.

  17. Independent metal-thiolate cluster formation in C-terminal Cys-rich region of a rice type 1 metallothionein isoform.

    PubMed

    Malekzadeh, Rahim; Shahpiri, Azar

    2017-03-01

    In this study we examined the independent self assembly of metal-binding in C-terminal Cys- rich region of a type 1 metallothionein (MT) isoform from rice (OsMTI-1b). To this end the N-terminal of OsMTI-1b (C-OsMTI-1b) was heterologously expressed in Escherichia coli as fusion protein with glutathione-S-transferase (GST). As compared with control (The E. coli cells containing pET41a without gene), transgenic E. coli cells expressing GST-C-OsMTI-1b accumulated more Ni(2+), Cd(2+), and Zn(2+) from culture medium and showed increased tolerance against these metals. The recombinant GST-C-OsMTI-1b was purified using affinity chromatography. According to in vitro assays the protein GST-C-OsMTI-1b was able to form complexes with Ni(2+), Cd(2+) and Zn(2+). These results demonstrate the formation of independent metal-thiolate cluster at C-terminal Cys-rich region of OsMTI-1b without participation of N-terminal Cys-rich region.

  18. A New Type of Metal-Binding Site in Cobalt- And Zinc-Containing Adenylate Kinases Isolated From Sulfate-Reducers D. Gigas And D. Desulfuricans ATCC 27774

    SciTech Connect

    Gavel, O.Y.; Bursakov, S.A.; Rocco, G.Di; Trincao, J.; Pickering, I.J.; George, G.N.; Calvete, J.J.; Brondino, C.; Pereira, A.S.; Lampreia, J.; Tavares, P.; Moura, J.J.G.; Moura, I.

    2009-05-18

    Adenylate kinase (AK) mediates the reversible transfer of phosphate groups between the adenylate nucleotides and contributes to the maintenance of their constant cellular level, necessary for energy metabolism and nucleic acid synthesis. The AK were purified from crude extracts of two sulfate-reducing bacteria (SRB), Desulfovibrio (D.) gigas NCIB 9332 and Desulfovibrio desulfuricans ATCC 27774, and biochemically and spectroscopically characterized in the native and fully cobalt- or zinc-substituted forms. These are the first reported adenylate kinases that bind either zinc or cobalt and are related to the subgroup of metal-containing AK found, in most cases, in Gram-positive bacteria. The electronic absorption spectrum is consistent with tetrahedral coordinated cobalt, predominantly via sulfur ligands, and is supported by EPR. The involvement of three cysteines in cobalt or zinc coordination was confirmed by chemical methods. Extended X-ray absorption fine structure (EXAFS) indicate that cobalt or zinc are bound by three cysteine residues and one histidine in the metal-binding site of the 'LID' domain. The sequence {sup 129}Cys-X{sub 5}-His-X{sub 15}-Cys-X{sub 2}-Cys of the AK from D. gigas is involved in metal coordination and represents a new type of binding motif that differs from other known zinc-binding sites of AK. Cobalt and zinc play a structural role in stabilizing the LID domain.

  19. Characterization of neutron induced damage effect in several types of metallic multilayer nanocomposites based on Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Chen, Feida; Tang, Xiaobin; Yang, Yahui; Huang, Hai; Liu, Jian; Chen, Da

    2015-09-01

    Metallic multilayer nanocomposites are known to have excellent interface self-healing performance when it comes to repairing irradiation damages, thus showing promise as structural materials for advanced nuclear power systems. The present study investigated the neutron irradiation displacement damage rate, spectra of the primary knocked-on atoms (PKAs) produced in the cascade collision, and the H/He ratio in four kinds of metallic multilayer nanocomposites (Cu/Nb, Ag/V, Fe/W, and Ti/Ta) versus neutrons' energy. Results suggest that the three neutron induced damage effects in all multilayer systems increased with the increasing of incident neutrons' energy. For fission reactor environment (1 MeV), multilayer's displacement damage rate is 5-10 × 1022 dpa/(n/cm2) and the mean PKAs energy is about 16 keV, without any noteworthy H/He produced. Fe/W multilayer seems very suitable among these four systems. For fusion reactor environment (14 MeV), the dominant damage effect varies in different multilayer systems. Fe/W multilayer has the lowest displacement damage under the same neutron flux but its gaseous transmutation production is the highest. Considering the displacement damage and transmutation, the irradiation resistance of Ag/V and Ti/Ta systems seems much greater than those of the other two.

  20. Ab initio study of electronic structure, elastic and optical properties of anti-perovskite type alkali metal oxyhalides

    NASA Astrophysics Data System (ADS)

    Ramanna, J.; Yedukondalu, N.; Ramesh Babu, K.; Vaitheeswaran, G.

    2013-06-01

    We report the structural, elastic, electronic, and optical properties of antiperovskite alkali metal oxyhalides Na3OCl, Na3OBr, and K3OBr using two different density functional methods within generalized gradient approximation (GGA). Plane wave pseudo potential (PW-PP) method has been used to calculate the ground state structural and elastic properties while the electronic structure and optical properties are calculated explicitly using full potential-linearized augmented plane wave (FP-LAPW) method. The calculated ground state properties of the investigated compounds agree quite well with the available experimental data. The predicted elastic constants using both PW-PP and FP-LAPW methods are in good accord with each other and show that the materials are mechanically stable. The low values of the elastic moduli indicate that these materials are soft in nature. The bulk properties such as shear moduli, Young's moduli, and Poisson's ratio are derived from the calculated elastic constants. Tran-Blaha modified Becke-Johnson (TB-mBJ) potential improves the band gaps over GGA and Engel-Vosko GGA. The computed TB-mBJ electronic band structure reveals that these materials are direct band gap insulators. The complex dielectric function of the metal oxyhalide compounds have been calculated and the observed prominent peaks are analyzed through the TB-mBJ electronic structures. By using the knowledge of complex dielectric function other important optical properties including absorption, reflectivity, refractive index and loss function have been obtained as a function of energy.

  1. INTEGRAL FIELD SPECTROSCOPY OF SUPERNOVA EXPLOSION SITES: CONSTRAINING THE MASS AND METALLICITY OF THE PROGENITORS. I. TYPE Ib AND Ic SUPERNOVAE

    SciTech Connect

    Kuncarayakti, Hanindyo; Maeda, Keiichi; Doi, Mamoru; Morokuma, Tomoki; Hashiba, Yasuhito; Aldering, Greg; Arimoto, Nobuo; Pereira, Rui

    2013-08-01

    Integral field spectroscopy of 11 Type Ib/Ic supernova (SN Ib/Ic) explosion sites in nearby galaxies has been obtained using UH88/SNIFS and Gemini-N/GMOS. The use of integral field spectroscopy enables us to obtain both spatial and spectral information about the explosion site, enabling the identification of the parent stellar population of the SN progenitor star. The spectrum of the parent population provides metallicity determination via strong-line method and age estimation obtained via comparison with simple stellar population models. We adopt this information as the metallicity and age of the SN progenitor, under the assumption that it was coeval with the parent stellar population. The age of the star corresponds to its lifetime, which in turn gives the estimate of its initial mass. With this method we were able to determine both the metallicity and initial (zero-age main sequence) mass of the progenitor stars of SNe Ib and Ic. We found that on average SN Ic explosion sites are more metal-rich and younger than SN Ib sites. The initial mass of the progenitors derived from parent stellar population age suggests that SN Ic has more massive progenitors than SN Ib. In addition, we also found indication that some of our SN progenitors are less massive than {approx}25 M{sub Sun }, indicating that they may have been stars in a close binary system that have lost their outer envelope via binary interactions to produce SNe Ib/Ic, instead of single Wolf-Rayet stars. These findings support the current suggestions that both binary and single progenitor channels are in effect in producing SNe Ib/Ic. This work also demonstrates the power of integral field spectroscopy in investigating SN environments and active star-forming regions.

  2. Selective Conversion from p-Type to n-Type of Printed Bottom-Gate Carbon Nanotube Thin-Film Transistors and Application in Complementary Metal-Oxide-Semiconductor Inverters.

    PubMed

    Xu, Qiqi; Zhao, Jianwen; Pecunia, Vincenzo; Xu, Wenya; Zhou, Chunshan; Dou, Junyan; Gu, Weibing; Lin, Jian; Mo, Lixin; Zhao, Yanfei; Cui, Zheng

    2017-04-12

    The fabrication of printed high-performance and environmentally stable n-type single-walled carbon nanotube (SWCNT) transistors and their integration into complementary (i.e., complementary metal-oxide-semiconductor, CMOS) circuits are widely recognized as key to achieving the full potential of carbon nanotube electronics. Here, we report a simple, efficient, and robust method to convert the polarity of SWCNT thin-film transistors (TFTs) using cheap and readily available ethanolamine as an electron doping agent. Printed p-type bottom-gate SWCNT TFTs can be selectively converted into n-type by deposition of ethanolamine inks on the transistor active region via aerosol jet printing. Resulted n-type TFTs show excellent electrical properties with an on/off ratio of 10(6), effective mobility up to 30 cm(2) V(-1) s(-1), small hysteresis, and small subthreshold swing (90-140 mV dec(-1)), which are superior compared to the original p-type SWCNT devices. The n-type SWCNT TFTs also show good stability in air, and any deterioration of performance due to shelf storage can be fully recovered by a short low-temperature annealing. The easy polarity conversion process allows construction of CMOS circuitry. As an example, CMOS inverters were fabricated using printed p-type and n-type TFTs and exhibited a large noise margin (50 and 103% of 1/2 Vdd = 1 V) and a voltage gain as high as 30 (at Vdd = 1 V). Additionally, the CMOS inverters show full rail-to-rail output voltage swing and low power dissipation (0.1 μW at Vdd = 1 V). The new method paves the way to construct fully functional complex CMOS circuitry by printed TFTs.

  3. A Novel n-Type Organosilane-Metal Ion Hybrid of Rhodamine B and Copper Cation for Low-Temperature Thermoelectric Materials.

    PubMed

    Bertram, John R; Penn, Aubrey; Nee, Matthew J; Rathnayake, Hemali

    2017-03-29

    An n-type organosilane-metal ion hybrid of Rhodamine B-silane and copper cation (Cu-RBS) was investigated as a low-temperature thermoelectric material. Computational analysis revealed the most likely localized binding site of Cu(2+) was to the Rhodamine B core and provided predictions of molecular orbitals and electrostatic potentials upon complexation. The concentration-dependent optical absorption and emission spectra confirmed the effective metal-ligand charge transfer from Cu(2+) to the xanthene core of RBS, indicating the potential for improved electrical properties for the complex relative to RBS. The electrical conductivity and Seebeck thermoelectric (TE) behavior were evaluated and compared with its precursor complex of Rhodamine B and copper cation. While a moderately high electrical conductivity of 4.38 S m(-1) was obtained for the Cu-RBS complex, the relatively low Seebeck coefficient of -26.2 μV/K resulted in a low TE power factor. However, compared to other organic doped materials, these results were promising toward developing n-type thermoelectric materials with no doping agents. Both phase segregation and thin film heterogeneity remain to be optimized; thus, the balance between Cu(2+) domains and RBS domain phases will likely yield higher Seebeck coefficients and improved power factors.

  4. Metal-nonmetal transition in the sphalerite-type solid solution [ZnSnSb{sub 2}]{sub 1-x}[2(InSb)]{sub x}

    SciTech Connect

    Tenga, Andreas; Javier Garcia-Garcia, F.; Wu, Yang; Newman, N.; Haeussermann, Ulrich

    2009-06-15

    Samples of the solid solution [ZnSnSb{sub 2}]{sub 1-x}[2(InSb)]{sub x} have been prepared over the whole range of composition by tin flux synthesis. The lattice parameter of the sphalerite-type average structure varies linearly between that of the end members ZnSnSb{sub 2} and InSb, a=6.2849(2) and 6.4776(15), respectively. Electron diffraction shows different kinds of structured diffuse scattering for Zn and In rich samples, respectively. The former is attributed to compositional short range ordering, the latter to thermally excited phonon modes. A metal-nonmetal transition takes place between the compositions x=0.8 and x=0.9. - Graphical abstract: Alloys of the sphalerite-type solid solution [ZnSnSb{sub 2}]{sub 1-x}[2(InSb)]{sub x} can be prepared over the whole range of composition by Sn flux synthesis. A metal-nonmetal transition takes place between the compositions x=0.8 and x=0.9.

  5. Behavior of W and WSi(x) Contact Metallization on n- and p- Type GaN

    SciTech Connect

    Abernathy, C.R.; Cao, X.A.; Cole, M.W.; Eizenberg, M.; Lothian, J.R.; Pearton, S.J.; Ren, F.; Shul, R.J.; Zeitouny, A.; Zolper, J.C.

    1999-01-05

    Sputter-deposited W-based contacts on p-GaN (N{sub A} {approximately} 10{sup 18} cm{sup {minus}3}) display non-ohmic behavior independent of annealing temperature when measured at 25 C. The transition to ohmic behavior occurs above {approximately} 250 C as more of the acceptors become ionized. The optimum annealing temperature is {approximately} 700 C under these conditions. These contacts are much more thermally stable than the conventional Ni/Au metallization, which shows a severely degraded morphology even at 700 C. W-based contacts may be ohmic as-deposited on very heavily doped n-GaN, and the specific contact resistance improves with annealing up to {approximately} 900 C.

  6. Friedel-Crafts-Type Intermolecular C-H Silylation of Electron-Rich Arenes Initiated by Base-Metal Salts.

    PubMed

    Yin, Qin; Klare, Hendrik F T; Oestreich, Martin

    2016-02-24

    An electrophilic aromatic substitution (SE Ar) with a catalytically generated silicon electrophile is reported. Essentially any commercially available base-metal salt acts as an initiator/catalyst when activated with NaBAr(F)4. The thus-generated Lewis acid then promotes the SE Ar of electron-rich arenes with hydrosilanes but not halosilanes. This new C-H silylation was optimized for FeCl2/NaBAr(F)4, affording good yields at catalyst loadings as low as 0.5 mol %. The procedure is exceedingly straightforward and comes close to typical Friedel-Crafts methods, where no added base is needed to absorb the released protons.

  7. VARIATIONS OF MID- AND FAR-INFRARED LUMINOSITIES AMONG EARLY-TYPE GALAXIES: RELATION TO STELLAR METALLICITY AND COLD DUST

    SciTech Connect

    Mathews, William G.; Brighenti, Fabrizio

    2013-05-01

    The Hubble morphological sequence from early to late galaxies corresponds to an increasing rate of specific star formation. The Hubble sequence also follows a banana-shaped correlation between 24 and 70 {mu}m luminosities, both normalized with the K-band luminosity. We show that this correlation is significantly tightened if galaxies with central active galactic nucleus (AGN) emission are removed, but the cosmic scatter of elliptical galaxies in both 24 and 70 {mu}m luminosities remains significant along the correlation. We find that the 24 {mu}m variation among ellipticals correlates with stellar metallicity, reflecting emission from hot dust in winds from asymptotic giant branch stars of varying metallicity. Infrared surface brightness variations in elliptical galaxies indicate that the K - 24 color profile is U-shaped for reasons that are unclear. In some elliptical galaxies, cold interstellar dust emitting at 70 and 160 {mu}m may arise from recent gas-rich mergers. However, we argue that most of the large range of 70 {mu}m luminosity in elliptical galaxies is due to dust transported from galactic cores by feedback events in (currently IR-quiet) AGNs. Cooler dusty gas naturally accumulates in the cores of elliptical galaxies due to dust-cooled local stellar mass loss and may accrete onto the central black hole, releasing energy. AGN-heated gas can transport dust in cores 5-10 kpc out into the hot gas atmospheres where it radiates extended 70 {mu}m emission but is eventually destroyed by sputtering. This, and some modest star formation, defines a cycle of dust creation and destruction. Elliptical galaxies evidently undergo large transient excursions in the banana plot in times comparable to the sputtering time or AGN duty cycle, 10 Myr. Normally regarded as passive, elliptical galaxies are the most active galaxies in the IR color-color correlation.

  8. High-Entropy Metal Diborides: A New Class of High-Entropy Materials and a New Type of Ultrahigh Temperature Ceramics

    PubMed Central

    Gild, Joshua; Zhang, Yuanyao; Harrington, Tyler; Jiang, Sicong; Hu, Tao; Quinn, Matthew C.; Mellor, William M.; Zhou, Naixie; Vecchio, Kenneth; Luo, Jian

    2016-01-01

    Seven equimolar, five-component, metal diborides were fabricated via high-energy ball milling and spark plasma sintering. Six of them, including (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2, (Hf0.2Zr0.2Mo0.2Nb0.2Ti0.2)B2, (Hf0.2Mo0.2Ta0.2Nb0.2Ti0.2)B2, (Mo0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, and (Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2)B2, possess virtually one solid-solution boride phase of the hexagonal AlB2 structure. Revised Hume-Rothery size-difference factors are used to rationalize the formation of high-entropy solid solutions in these metal diborides. Greater than 92% of the theoretical densities have been generally achieved with largely uniform compositions from nanoscale to microscale. Aberration-corrected scanning transmission electron microscopy (AC STEM), with high-angle annular dark-field and annular bright-field (HAADF and ABF) imaging and nanoscale compositional mapping, has been conducted to confirm the formation of 2-D high-entropy metal layers, separated by rigid 2-D boron nets, without any detectable layered segregation along the c-axis. These materials represent a new type of ultra-high temperature ceramics (UHTCs) as well as a new class of high-entropy materials, which not only exemplify the first high-entropy non-oxide ceramics (borides) fabricated but also possess a unique non-cubic (hexagonal) and layered (quasi-2D) high-entropy crystal structure that markedly differs from all those reported in prior studies. Initial property assessments show that both the hardness and the oxidation resistance of these high-entropy metal diborides are generally higher/better than the average performances of five individual metal diborides made by identical fabrication processing. PMID:27897255

  9. High-Entropy Metal Diborides: A New Class of High-Entropy Materials and a New Type of Ultrahigh Temperature Ceramics

    NASA Astrophysics Data System (ADS)

    Gild, Joshua; Zhang, Yuanyao; Harrington, Tyler; Jiang, Sicong; Hu, Tao; Quinn, Matthew C.; Mellor, William M.; Zhou, Naixie; Vecchio, Kenneth; Luo, Jian

    2016-11-01

    Seven equimolar, five-component, metal diborides were fabricated via high-energy ball milling and spark plasma sintering. Six of them, including (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2, (Hf0.2Zr0.2Mo0.2Nb0.2Ti0.2)B2, (Hf0.2Mo0.2Ta0.2Nb0.2Ti0.2)B2, (Mo0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, and (Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2)B2, possess virtually one solid-solution boride phase of the hexagonal AlB2 structure. Revised Hume-Rothery size-difference factors are used to rationalize the formation of high-entropy solid solutions in these metal diborides. Greater than 92% of the theoretical densities have been generally achieved with largely uniform compositions from nanoscale to microscale. Aberration-corrected scanning transmission electron microscopy (AC STEM), with high-angle annular dark-field and annular bright-field (HAADF and ABF) imaging and nanoscale compositional mapping, has been conducted to confirm the formation of 2-D high-entropy metal layers, separated by rigid 2-D boron nets, without any detectable layered segregation along the c-axis. These materials represent a new type of ultra-high temperature ceramics (UHTCs) as well as a new class of high-entropy materials, which not only exemplify the first high-entropy non-oxide ceramics (borides) fabricated but also possess a unique non-cubic (hexagonal) and layered (quasi-2D) high-entropy crystal structure that markedly differs from all those reported in prior studies. Initial property assessments show that both the hardness and the oxidation resistance of these high-entropy metal diborides are generally higher/better than the average performances of five individual metal diborides made by identical fabrication processing.

  10. Block of current through T-type calcium channels by trivalent metal cations and nickel in neural rat and human cells.

    PubMed

    Mlinar, B; Enyeart, J J

    1993-09-01

    1. The effects of the trivalent cations yttrium (Y3+), lanthanum (La3+), cerium (Ce3+), neodymium (Nd3+), gadolinium (Gd3+), holmium (Ho3+), erbium (Er3+), ytterbium (Yb3+) and the divalent cation nickel (Ni2+) on the T-type voltage gated calcium channel (VGCC) were characterized by the whole-cell patch clamp technique using rat and human thyroid C cell lines. 2. All the metal cations (M3+) studied, blocked current through T-type VGCC (IT) in a concentration-dependent manner. Smaller trivalents were the best T-channel antagonists and potency varied inversely with ionic radii for the larger M3+ ions. Estimation of half-maximal blocking concentrations (IC50s) for IT carried by 10 mM Ca2+ resulted in the following potency sequence: Ho3+ (IC50 = 0.107 microM) approximately Y3+ (0.117) approximately Yb3+ (0.124) > or = Er3+ (0.153) > Gd3+ (0.267) > Nd3+ (0.429) > Ce3+ (0.728) > La3+ (1.015) > Ni2+ (5.65). 3. Tail current measurements and conditioning protocols were used to study the influence of membrane voltage on the potency of these antagonists. Block of IT by Ni2+, Y3+, La3+ and the lanthanides was voltage independent in the range from -200 to +80 mV. In addition, the antagonists did not affect macroscopic inactivation and deactivation of T-type VGCC. 4. Increasing the extracellular Ca2+ concentration reduced the potency of IT block by Ho3+, indicative of competitive antagonism between this blocker and the permeant ion for a binding site. 5. The results suggest that the mechanism of metal cation block of T-type VGCC is occlusion of the channel pore by the antagonist binding to a Ca2+/M3+ binding site, located out of the membrane electric field. 6. Block of T-type VGCC by Y3+, lanthanides and La3+ differ from the inhibition of high voltage-activated VGCC block in several respects: smaller cations are more potent IT antagonists; block is voltage independent and the antagonists do not permeate T-type channels. These differences suggest corresponding structural

  11. The electrical and structural properties of n-type InAs nanowires grown from metal-organic precursors.

    PubMed

    Thelander, C; Dick, K A; Borgström, M T; Fröberg, L E; Caroff, P; Nilsson, H A; Samuelson, L

    2010-05-21

    The electrical and structural properties of 111B-oriented InAs nanowires grown using metal-organic precursors have been studied. On the basis of electrical measurements it was found that the trends in carbon incorporation are similar to those observed in the layer growth, where an increased As/In precursor ratio and growth temperature result in a decrease in carbon-related impurities. Our results also show that the effect of non-intentional carbon doping is weaker in InAs nanowires compared to bulk, which may be explained by lower carbon incorporation in the nanowire core. We determine that differences in crystal quality, here quantified as the stacking fault density, are not the primary cause for variations in resistivity of the material studied. The effects of some n-dopant precursors (S, Se, Si, Sn) on InAs nanowire morphology, crystal structure and resistivity were also investigated. All precursors result in n-doped nanowires, but high precursor flows of Si and Sn also lead to enhanced radial overgrowth. Use of the Se precursor increases the stacking fault density in wurtzite nanowires, ultimately at high flows leading to a zinc blende crystal structure with strong overgrowth and very low resistivity.

  12. Two-phase quasi-equilibrium in β-type Ti-based bulk metallic glass composites.

    PubMed

    Zhang, L; Pauly, S; Tang, M Q; Eckert, J; Zhang, H F

    2016-01-12

    The microstructural evolution of cast Ti/Zr-based bulk metallic glass composites (BMGCs) containing β-Ti still remains ambiguous. This is why to date the strategies and alloys suitable for producing such BMGCs with precisely controllable volume fractions and crystallite sizes are still rather limited. In this work, a Ti-based BMGC containing β-Ti was developed in the Ti-Zr-Cu-Co-Be system. The glassy matrix of this BMGC possesses an exceptional glass-forming ability and as a consequence, the volume fractions as well as the composition of the β-Ti dendrites remain constant over a wide range of cooling rates. This finding can be explained in terms of a two-phase quasi-equilibrium between the supercooled liquid and β-Ti, which the system attains on cooling. The two-phase quasi-equilibrium allows predicting the crystalline and glassy volume fractions by means of the lever rule and we succeeded in reproducing these values by slight variations in the alloy composition at a fixed cooling rate. The two-phase quasi-equilibrium could be of critical importance for understanding and designing the microstructures of BMGCs containing the β-phase. Its implications on the nucleation and growth of the crystalline phase are elaborated.

  13. VizieR Online Data Catalog: Effective temperature of metal-poor A-type stars (Kinman+, 2002)

    NASA Astrophysics Data System (ADS)

    Kinman, T.; Castelli, F.

    2002-07-01

    Effective temperatures (Teff) can be determined from (V- (V-H)0 and (V-K)0 colours that are derived from 2MASS magnitudes. This gives another way to estimate the Teff of faint blue halo stars (V<~15) whose temperatures are now usually deduced from (BV)0_. Transformations (adapted from Carpenter, 2001AJ....121.2851C) are used to change colours derived from the 2MASS data to the Johnson system. Teff is then derived from these colours using an updated Kurucz model. Tables are given to derive Teff as a function of (V-J)0, (V-H)0 and (V-K)0 for a variety of metallicities and suitable for blue horizontal branch and main sequence stars. The temperatures obtained in this way are compared with those in the recent literature for various stars with 5<=V<=15 and Teff in the range 6500 to 9500K; systematic differences are ~100K. An exception is the sample of BHB stars observed by Wilhelm et al. (1999, Cat. ) whose Teff are significantly cooler than those we derive by an amount that increases with increasing temperature. Description: (2 data files).

  14. Two-phase quasi-equilibrium in β-type Ti-based bulk metallic glass composites

    PubMed Central

    Zhang, L.; Pauly, S.; Tang, M. Q.; Eckert, J.; Zhang, H. F.

    2016-01-01

    The microstructural evolution of cast Ti/Zr-based bulk metallic glass composites (BMGCs) containing β-Ti still remains ambiguous. This is why to date the strategies and alloys suitable for producing such BMGCs with precisely controllable volume fractions and crystallite sizes are still rather limited. In this work, a Ti-based BMGC containing β-Ti was developed in the Ti-Zr-Cu-Co-Be system. The glassy matrix of this BMGC possesses an exceptional glass-forming ability and as a consequence, the volume fractions as well as the composition of the β-Ti dendrites remain constant over a wide range of cooling rates. This finding can be explained in terms of a two-phase quasi-equilibrium between the supercooled liquid and β-Ti, which the system attains on cooling. The two-phase quasi-equilibrium allows predicting the crystalline and glassy volume fractions by means of the lever rule and we succeeded in reproducing these values by slight variations in the alloy composition at a fixed cooling rate. The two-phase quasi-equilibrium could be of critical importance for understanding and designing the microstructures of BMGCs containing the β-phase. Its implications on the nucleation and growth of the crystalline phase are elaborated. PMID:26754315

  15. Methane conversion in surface- and volume-type dielectric barrier discharges generated in the presence of metal-mesh electrodes

    NASA Astrophysics Data System (ADS)

    Kobayashi, Kazunobu; Kulinich, S. A.; Ito, Tsuyohito

    2014-09-01

    Methane gas conversion was studied in customized flow-type reactors with different dielectric barrier discharge generated in Ar-CH4-O2 gas mixtures. Different reactor geometries (with either volume or surface-type discharges) and different electrode materials were compared, and gas temperatures during methane conversion processes were evaluated. The discharge was generated by applying either a conventional sinusoid or nanosecond-pulsed voltage. The methane conversion rate was as high as ˜99% with the total gas flow rate of 15 sccm, while the temperatures did not exceed 450 K. No significant effect of electrode material (stainless steel, aluminum, or CuO coated copper) was found, confirming that the conversion temperatures were much lower than those required for activity of typical catalysts. The reactor geometry, flow rate, and oxygen amount could be used to govern both the methane conversion rate and the fractions of components in the final product.

  16. Zinc and Other Metals Deficiencies and Risk of Type 1 Diabetes: An Ecological Study in the High Risk Sardinia Island

    PubMed Central

    Sanna, Alessandro; Pretti, Salvatore; Marcello, Alberto; Mannu, Carla; Targhetta, Clara; Bruno, Graziella; Songini, Marco

    2015-01-01

    Background Type 1 diabetes incidence presents a decreasing gradient in Europe from the Nordic countries to the Mediterranean ones. Exception to this gradient is represented by Sardinia, the second largest Mediterranean island whose population shows the highest incidence in Europe, after Finland. The genetic features of this population have created a fertile ground for the epidemic of the disease, however, as well as being strikingly high, the incidence rate has suddenly presented a continuous increase from the ‘50s, not explainable by accumulation of new genetic variants. Several environmental factors have been taken into account, possibly interacting with the genetic/epigenetic scenario, but there are no strong evidences to date. Methods The present study investigated the hypothesis that geochemical elements could create permissive environmental conditions for autoimmune diabetes. An ecological analysis was performed to test possible correlations between the values of eight elements in stream sediments and type 1 diabetes incidence rate in Sardinia. Results Analyses revealed negative associations between elements, such as Co, Cr, Cu, Mn, Ni, Zn, and type 1 diabetes incidence. Conclusions The results suggest a possible protective role of some elements against the onset of the disease. PMID:26559814

  17. 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)

  18. Supramolecular motifs in s-block metal-bound sulfonated monoazo dyes, part 1: structural class controlled by cation type and modulated by sulfonate aryl ring position.

    PubMed

    Kennedy, Alan R; Kirkhouse, Jennifer B A; McCarney, Karen M; Puissegur, Olivier; Smith, W Ewen; Staunton, Edward; Teat, Simon J; Cherryman, Julian C; James, Rachel

    2004-09-20

    The solid-state structures of 43 Li, Na, K, Rb, Mg, Ca and Ba salts of para- and meta-sulfonated azo dyes have been examined and can be categorised into three structural classes. All form alternating organic and inorganic layers, however, the nature of the coordination network that forms these layers differs from class to class. The class of structure formed was found to be primarily governed by metal type, but can also be influenced by the nature and position of the organic substituents. Thus, for the para-sulfonated azo dyes, Mg compounds form solvent-separated ion-pair solids; Ca, Ba and Li compounds form simple coordination networks based on metal-sulfonate bonding; and Na, K and Rb compounds form more complex, higher dimensional coordination networks. Compounds of meta-sulfonated azo dyes follow a similar pattern, but here, Ca species may also form solvent-separated ion-pair solids. Significantly, this first attempt to classify such dyestuffs using the principles of supramolecular chemistry succeeds not only for the simple dyes used here as model compounds, but also for more complex molecules, similar to modern colourants.

  19. Fabrication of a Core-Shell-Type Photocatalyst via Photodeposition of Group IV and V Transition Metal Oxyhydroxides: An Effective Surface Modification Method for Overall Water Splitting.

    PubMed

    Takata, Tsuyoshi; Pan, Chengsi; Nakabayashi, Mamiko; Shibata, Naoya; Domen, Kazunari

    2015-08-05

    The design of optimal surface structures for photocatalysts is a key to efficient overall water splitting into H2 and O2. A unique surface modification method was devised for a photocatalyst to effectively promote overall water splitting. Photodeposition of amorphous oxyhydroxides of group IV and V transition metals (Ti, Nb, Ta) over a semiconductor photocatalyst from corresponding water-soluble metal peroxide complexes was examined. In this method, amorphous oxyhydroxide covered the whole surface of the photocatalyst particles, creating a core-shell structure. The water splitting behavior of the novel core-shell-type photocatalyst in relation to the permeation behavior of the coating layer was investigated in detail. Overall water splitting proceeded successfully after the photodeposition, owing to the prevention of the reverse reaction. The photodeposited oxyhydroxide layers were found to function as molecular sieves, selectively filtering reactant and product molecules. By exploiting the selective permeability of the coating layer, redox reactions on the photocatalyst surface could be suitably controlled, which resulted in successful overall water splitting.

  20. An anti CuO2-type metal hydride square net structure in Ln2M2As2H(x) (Ln=La or Sm, M=Ti, V, Cr, or Mn).

    PubMed

    Mizoguchi, Hiroshi; Park, SangWon; Hiraka, Haruhiro; Ikeda, Kazutaka; Otomo, Toshiya; Hosono, Hideo

    2015-03-02

    Using a high pressure technique and the strong donating nature of H(-), a new series of tetragonal La2Fe2Se2O3-type layered mixed-anion arsenides, Ln2M2As2H(x), was synthesized (Ln=La or Sm, M=Ti, V, Cr, or Mn; x≈3). In these compounds, an unusual M2H square net, which has anti CuO2 square net structures accompanying two As(3-) ions, is sandwiched by (LaH)2 fluorite layers. Notably, strong metal-metal bonding with a distance of 2.80 Å was confirmed in La2Ti2As2H2.3, which has metallic properties. In fact, these compounds are situated near the boundary between salt-like ionic hydrides and transition-metal hydrides with metallic characters.

  1. Investigation of Stress Memorization Process on Low-Frequency Noise Performance for Strained Si n-Type Metal-Oxide-Semiconductor Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Kuo, Cheng-Wen; Wu, San-Lein; Lin, Hau-Yu; Huang, Yao-Tsung; Chang, Shoou-Jinn; Hong, De-Gong; Wu, Chung-Yi; Cheng, Yao-Chin; Cheng, Osbert

    2011-04-01

    The use of low-frequency (1/f) noise to evaluate low-cost stress-memorization technique (SMT) induced-stress in n-type metal-oxide-semiconductor field-effect transistors has been investigated. As compared to device without SMT process, the comparable 1/f noise level obtained for strained Si devices with the low-cost SMT process indicates that adding the low-cost SMT process will not affect the Si/SiO2 interface quality. Moreover, through observing experiment result and Hooge's parameter αH, the mechanism of 1/f noise in the both devices can be properly interpreted by the carrier number fluctuations correlated mobility fluctuations (unified model).

  2. Linking land-use type and stream water quality using spatial data of fecal indicator bacteria and heavy metals in the Yeongsan river basin.

    PubMed

    Kang, Joo-Hyon; Lee, Seung Won; Cho, Kyung Hwa; Ki, Seo Jin; Cha, Sung Min; Kim, Joon Ha

    2010-07-01

    This study reveals land-use factors that explain stream water quality during wet and dry weather conditions in a large river basin using two different linear models-multiple linear regression (MLR) models and constrained least squares (CLS) models. Six land-use types and three topographical parameters (size, slope, and permeability) of the watershed were incorporated into the models as explanatory variables. The suggested models were then demonstrated using a digitized elevation map in conjunction with the land-use and the measured concentration data for Escherichia coli (EC), Enterococci bacteria (ENT), and six heavy metal species collected monthly during 2007-2008 at 50 monitoring sites in the Yeongsan Watershed, Korea. The results showed that the MLR models can be a powerful tool for predicting the average concentrations of pollutants in stream water (the Nash-Sutcliffe (NS) model efficiency coefficients ranged from 0.67 to 0.95). On the other hand, the CLS models, with moderately good prediction performance (the NS coefficients ranged 0.28-0.85), were more suitable for quantifying contributions of respective land-uses to the stream water quality. The CLS models suggested that industrial and urban land-uses are major contributors to the stream concentrations of EC and ENT, whereas agricultural, industrial, and mining areas were significant sources of many heavy metal species. In addition, the slope, size, and permeability of the watershed were found to be important factors determining the extent of the contribution from each land-use type to the stream water quality. The models proposed in this paper can be considered useful tools for developing land cover guidelines and for prioritizing locations for implementing management practices to maintain stream water quality standard in a large river basin.

  3. An antibody raised against a pathogenic serpin variant induces mutant-like behaviour in the wild-type protein

    PubMed Central

    Irving, James A.; Miranda, Elena; Haq, Imran; Perez, Juan; Kotov, Vadim R.; Faull, Sarah V.; Motamedi-Shad, Neda; Lomas, David A.

    2015-01-01

    A monoclonal antibody (mAb) that binds to a transient intermediate may act as a catalyst for the corresponding reaction; here we show this principle can extend on a macro molecular scale to the induction of mutant-like oligomerization in a wild-type protein. Using the common pathogenic E342K (Z) variant of α1-antitrypsin as antigen–whose native state is susceptible to the formation of a proto-oligomeric intermediate–we have produced a mAb (5E3) that increases the rate of oligomerization of the wild-type (M) variant. Employing ELISA, gel shift, thermal stability and FRET time-course experiments, we show that mAb5E3 does not bind to the native state of α1-antitrypsin, but recognizes a cryptic epitope in the vicinity of the post-helix A loop and strand 4C that is revealed upon transition to the polymerization intermediate, and which persists in the ensuing oligomer. This epitope is not shared by loop-inserted monomeric conformations. We show the increased amenity to polymerization by either the pathogenic E342K mutation or the binding of mAb5E3 occurs without affecting the energetic barrier to polymerization. As mAb5E3 also does not alter the relative stability of the monomer to intermediate, it acts in a manner similar to the E342K mutant, by facilitating the conformational interchange between these two states. PMID:25738741

  4. Synthesis and characterization of carbon dioxide and boiling water stable proton conducting double perovskite-type metal oxides

    NASA Astrophysics Data System (ADS)

    Bhella, Surinderjit Singh; Thangadurai, Venkataraman

    In this paper, we report the synthesis, chemical stability and electrical properties of three new Ta-substituted double perovskite-type Ba 2Ca 2/3Nb 4/3O 6 (BCN). The powder X-ray diffraction (PXRD) confirms the formation of double perovskite-like structure Ba 2(Ca 0.75Nb 0.59Ta 0.66)O 6- δ, Ba 2(Ca 0.75Nb 0.66Ta 0.59)O 6- δ and Ba 2(Ca 0.79Nb 0.66Ta 0.55)O 6- δ. The PXRD of CO 2 treated (800 °C; 7 days) and water boiled (7 days) samples remain the same as the as-prepared samples, suggesting a long-term structural stability against the chemical reaction. The electrical conductivity of the investigated perovskites was found to vary in different atmospheres (air, dry N 2, wet N 2, H 2 and D 2O + N 2). The AC impedance investigations show bulk, grain-boundary and electrode contributions in the frequency range of 0.01 Hz to 7 MHz. Below 600 °C, the bulk conductivity in wet H 2 and wet N 2 was higher than in air, dry H 2 and dry N 2. However, an opposite trend was observed at high temperatures, which may be ascribed to p-type electronic conduction. The electrical conductivity of the investigated perovskites was decreased in D 2O + N 2 compared to that of H 2O + N 2 atmosphere. This clearly shows that the investigated Ta-doped BCN compounds exhibit proton conduction in wet atmosphere which was found to be consistent with water uptake. The water uptake was further confirmed by thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) characterization. Among the samples investigated, Ba 2(Ca 0.79Nb 0.66Ta 0.55)O 6- δ shows the highest proton conductivity of 4.8 × 10 -4 S cm -1 (at 1 MHz) at 400 °C in wet (3% H 2O) N 2 or H 2, which is about an order of magnitude higher than the recently reported 1% Ca-doped LaNbO 4 at the same atmosphere and at 10 kHz.

  5. Theoretical comparison of Si, Ge, and GaAs ultrathin p-type double-gate metal oxide semiconductor transistors

    NASA Astrophysics Data System (ADS)

    Dib, Elias; Bescond, Marc; Cavassilas, Nicolas; Michelini, Fabienne; Raymond, Laurent; Lannoo, Michel

    2013-08-01

    Based on a self-consistent multi-band quantum transport code including hole-phonon scattering, we compare current characteristics of Si, Ge, and GaAs p-type double-gate transistors. Electronic properties are analyzed as a function of (i) transport orientation, (ii) channel material, and (iii) gate length. We first show that ⟨100⟩-oriented devices offer better characteristics than their ⟨110⟩-counterparts independently of the material choice. Our results also point out that the weaker impact of scattering in Ge produces better electrical performances in long devices, while the moderate tunneling effect makes Si more advantageous in ultimately scaled transistors. Moreover, GaAs-based devices are less advantageous for shorter lengths and do not offer a high enough ON current for longer gate lengths. According to our simulations, the performance switching between Si and Ge occurs for a gate length of 12 nm. The conclusions of the study invite then to consider ⟨100⟩-oriented double-gate devices with Si for gate length shorter than 12 nm and Ge otherwise.

  6. Robotic gas metal arc welding of small diameter saddle type joints using multi-stripe structured light

    NASA Astrophysics Data System (ADS)

    Bonser, Gary R.; Parker, Graham A.

    1999-11-01

    Single-stripe structured light sensors are widely used in conjunction with arc welding robots for seam-tracking purposes. The interaction of the projected light with the weld joint and component surfaces produces characteristic line shapes with feature points that can be recognized at high speed by an underlying vision system. Unfortunately they are suitable only for the major classes of weld joint typically encountered within industry--long, straight, or gently curving fillet or butt joints. We present a multistripe structured light sensor that detects and measures the position of the saddle type weld joint formed by two small (< 50-mm)-diameter intersecting tubes. The underlying image processing algorithms detect the weld feature points from each stripe along with four calibration points to generate the entire weld path in the robot workcell base coordinate system before welding commences. The system is validated within an existing welding application; detecting 93% of the weld feature points within +/- 0.4 mm when used on 30-mm-diam tubes.

  7. Acute-Onset Type 1 Diabetes that Developed During the Administration of Olanzapine

    PubMed Central

    Iwaku, Kenji; Otuka, Fumiko; Taniyama, Matsuo

    2017-01-01

    The patient was 32-year-old man, who received olanzapine for schizophrenia and developed polyuria and thirst without drinking soft-drinks after 4 months. Five months after the initiation of treatment, he developed diabetic ketoacidosis (blood glucose: 490 mg/dL, HbA1c: 15.5%). He was diagnosed with type 1 diabetes (glutamic acid decarboxylase (GAD)-Ab: 5.6 U/mL, IA-2 Ab: 5.9 U/mL, fasting C-peptide: 0.12 ng/mL) and was put on intensive insulin therapy. At four months after the onset of 1A diabetes, he experienced a honeymoon phase that was sustained until the 40th month of treatment. We hypothesize that the administration of olanzapine to a patient with pre-type 1A diabetes induced marked hyperglycemia and accelerated the onset of type 1A diabetes. PMID:28154279

  8. Use of ion chromatography for the determination of selected metals in blood serum of patients with type 2 diabetes.

    PubMed

    Błazewicz, Anna; Orlicz-Szczesna, Grazyna; Prystupa, Andrzej; Szczesny, Piotr

    2010-01-01

    Ion chromatography followed by microwave-induced acid digestion was used to evaluate the serum levels of Fe(3+), Cu(2+), Ni(2+), Zn(2+), and Mn(2+) in patients with diagnosed type 2 diabetes and in healthy controls. Recoveries ranged from 98.0% to 102% for Fe(3+), from 89.9% to 100% for Cu(2+), from 87.9% to 102% for Zn(2+), and from 89.6% to 102% for Mn(2+) were determined by examining samples spiked with various amounts of all the studied ions. The time of mineralization longer than 28 min did not affect the assay values. Precision was assessed at four unique concentrations in replicates of six, on four separate occasions. RSD was determined to be 1.16% for Fe(3+), 5.20% for Cu(2+), 2.8% for Zn(2+), and 3.75% for Mn(2+). The accuracy results (values of RSD) were as follows: 5.16% for Fe(3+), 6.35% for Cu(2+), 4.9% for Zn(2+), and 7.23% for Mn(2+). The statistical analysis confirmed that mean concentrations of Fe(3+) and Zn(2+) did not differ significantly from analogous values in the control group. Patients who additionally suffered from hypertension had higher copper concentrations compared with diabetic patients. For diabetics the presence of Mn(2+) was not stated (LOD values amounting to 0.006 microg/mL). Ni(2+) was not detectable for either the studied group or the control group (LOD=0.006 microg/mL).

  9. 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.

  10. A new type of DNA "light-switch": a dual photochemical sensor and metalating agent for duplex and G-quadruplex DNA.

    PubMed

    Wachter, Erin; Howerton, Brock S; Hall, Emily C; Parkin, Sean; Glazer, Edith C

    2014-01-11

    Ru(bpy)2dppz, a well studied "light-switch" metal complex, transforms into a photochemical "light-switch" and DNA damaging agent by incorporating structural strain. This distorted compound is photoreactive and ejects a ligand upon binding duplex and G-quadruplex DNA, producing a reactive metal center that metalates the DNA.

  11. Monitoring Bacteroides spp. markers, nutrients, metals and Escherichia coli in soil and leachate after land application of three types of municipal biosolids.

    PubMed

    McCall, Crystal A; Jordan, Katerina S; Habash, Marc B; Dunfield, Kari E

    2015-03-01

    A lysimeter-based field study was done to monitor the transfer of culturable Escherichia coli, general (ALLBAC), human (Hf183) and swine (PIG-BAC-1) specific 16S rRNA Bacteroides spp. markers, nutrients and metals through soils and leachate over time following land application of a CP1/Class A as well as two CP2/Class B municipal biosolids (MBs). Hf183 markers were detected up to six days following application in soils receiving dewatered and liquid MBs, but not in leachate, suggesting their use in source tracking is better suited for recent pollution events. The CP2/Class B biosolids and swine manure contributed the highest microbial load with E. coli loads (between 2.5 and 3.7 log CFU (100 mL)(-1)) being greater than North American concentration recommendations for safe recreational water. ALLBAC persisted in soils and leachate receiving all treatments and was detected prior to amendment application demonstrating its unsuitability for identifying the presence of fecal pollution. A significant increase in NO₃-N (for Lystek and dewatered MBs) and total-P (for dewatered and liquid MBs) in leachate was observed in plots receiving the CP1/Class A and CP2/Class B type MBs which exceeded North American guidelines, suggesting impact to surface water. Metal (As, Cd, Cr, Co, Cu, Pb, Mo, Ni, Se, Zn and Hg) transfer was negligible in soil and leachate samples receiving all treatments. This study is one of the first to examine the fate of E. coli and Bacteroides spp. markers in situ following the land application of MBs where surface runoff does not apply.

  12. THE SUPERNOVA DELAY TIME DISTRIBUTION IN GALAXY CLUSTERS AND IMPLICATIONS FOR TYPE-Ia PROGENITORS AND METAL ENRICHMENT

    SciTech Connect

    Maoz, Dan; Sharon, Keren; Avishay Gal-Yam

    2010-10-20

    Knowledge of the supernova (SN) delay time distribution (DTD)-the SN rate versus time that would follow a hypothetical brief burst of star formation-can shed light on SN progenitors and physics, as well as on the timescales of chemical enrichment in different environments. We compile recent measurements of the Type-Ia SN (SN Ia) rate in galaxy clusters at redshifts from z = 0 out to z = 1.45, just 2 Gyr after cluster star formation at z {approx} 3. We review the plausible range for the observed total iron-to-stellar mass ratio in clusters, based on the latest data and analyses, and use it to constrain the time-integrated number of SN Ia events in clusters. With these data, we recover the DTD of SNe Ia in cluster environments. The DTD is sharply peaked at the shortest time-delay interval we probe, 0Gyr < t < 2.2 Gyr, with a low tail out to delays of {approx}10 Gyr, and is remarkably consistent with several recent DTD reconstructions based on different methods, applied to different environments. We test DTD models from the literature, requiring that they simultaneously reproduce the observed cluster SN rates and the observed iron-to-stellar mass ratios. A parameterized power-law DTD of the form t {sup -1.2{+-}0.3} from t = 400 Myr to a Hubble time can satisfy both constraints. Shallower power laws such as t {sup -1/2} cannot, assuming a single DTD, and a single star formation burst (either brief or extended) at high z. This implies that 50%-85% of SNe Ia explode within 1 Gyr of star formation. DTDs from double-degenerate (DD) models, which generically have {approx}t {sup -1} shapes over a wide range of timescales, match the data, but only if their predictions are scaled up by factors of 5-10. Single-degenerate (SD) DTDs always give poor fits to the data, due to a lack of delayed SNe and overall low numbers of SNe. The observations can also be reproduced with a combination of two SN Ia populations-a prompt SD population of SNe Ia that explodes within a few Gyr of star

  13. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: A Peak in Density Dependence of Electron Spin Relaxation Time in n-Type Bulk GaAs in the Metallic Regime

    NASA Astrophysics Data System (ADS)

    Shen, Ka

    2009-06-01

    We demonstrate that the peak in the density dependence of electron spin relaxation time in n-type bulk GaAs in the metallic regime predicted by Jiang and Wu [Phys. Rev. B 79 (2009) 125206] has been realized experimentally in the latest work [arXiv:0902.0270] by Krauß et al.

  14. Two Keggin-type heteropolytungstates with transition metal as a central atom: Crystal structure and magnetic study with 2D-IR correlation spectroscopy

    SciTech Connect

    Chai, Feng; Chen, YiPing; You, ZhuChai; Xia, ZeMin; Ge, SuZhi; Sun, YanQiong; Huang, BiHua

    2013-06-01

    Two Keggin-type heteropolytungstates, [Co(phen)₃]₃[CoW₁₂O₄₀]·9H₂O 1 (phen=1,10-phenanthroline) and [Fe(phen)₃]₂[FeW₁₂O₄₀]·H₃O·H₂O 2, have been synthesized via the hydrothermal technique and characterized by single crystal X-ray diffraction analyses, IR, XPS, TG analysis, UV–DRS, XRD, thermal-dependent and magnetic-dependent 2D-COS IR (two-dimensional infrared correlation spectroscopy). Crystal structure analysis reveals that the polyanions in compound 1 are linked into 3D supramolecule through hydrogen bonding interactions between lattice water molecules and terminal oxygen atoms of polyanion units, and [Co(phen)₃]²⁺ cations distributed in the polyanion framework with many hydrogen bonding interactions. The XPS spectra indicate that all the Co atoms in 1 are +2 oxidation state, the Fe atoms in 2 existing with +2 and +3 mixed oxidation states. - Graphical abstract: The magnetic-dependent synchronous 2D correlation IR spectra of 1 (a), 2 (b) over 0–50 mT in the range of 600–1000 cm⁻¹, the obvious response indicate two Keggin polyanions skeleton susceptible to applied magnetic field. Highlights: • Two Keggin-type heteropolytungstates with transition metal as a central atom has been obtained. • Compound 1 forms into 3D supramolecular architecture through hydrogen bonding between water molecules and polyanions. • Magnetic-dependent 2D-IR correlation spectroscopy was introduced to discuss the magnetism of polyoxometalate.

  15. Rare-earth-transition-metal organic-inorganic hybrids based on Keggin-type polyoxometalates and pyrazine-2,3-dicarboxylate.

    PubMed

    Zhang, Shaowei; Zhao, Junwei; Ma, Pengtao; Niu, Jingyang; Wang, Jingping

    2012-05-01

    Five rare-earth-transition-metal (RE-TM) heterometal organic-inorganic hybrids based on Keggin-type silicotungstates and mixed ligands H2pzda (pzda=pyrazine-2,3-dicarboxylate) and en (en=ethylenediamine) (enH2)[Cu(en)2(H2O)]2{[Cu(en)2][Cu(en)2(H2O)][(α-SiW11 O39)RE(H2O)(pzda)]}2·n H2O (n≈4; RE=YIII (1), DyIII (2), YbIII (3), and LuIII (4)) and [Cu(en)2(H2O)]2{[Cu(en)2]2[Cu(pzda)2][(α-H2SiW11O39)Ce(H2O)]2}·n H2O (5; n≈8) have been hydrothermally synthesized and structurally characterized. Compounds 1-5 all contain the dimeric mono-RE substituted Keggin [RE(α-SiW11O39)]210- subunits linked by H2pzda ligands. Interestingly, 1-4 exhibit discrete structures, in which the H2pzda ligand acts as a tetradentate ligand to bind the RE and Cu cations, whereas 5 displays a 1D double-chain architecture, in which the H2pzda ligand adopts a new pentadentate mode to connect the Ce and Cu cations. To our knowledge, 1-5 represent the first monovacant Keggin-type silicotungstates containing both RE-TM heterometals and mixed ligands. The luminescence of 2 is derived from the combination of the DyIII cations and H2pzda ligands, whereas the luminescence properties of 1 and 3-5 are attributable to the H2pzda ligands.

  16. New rht-Type Metal-Organic Frameworks Decorated with Acylamide Groups for Efficient Carbon Dioxide Capture and Chemical Fixation from Raw Power Plant Flue Gas.

    PubMed

    Guo, Xiangyang; Zhou, Zhen; Chen, Cong; Bai, Junfeng; He, Cheng; Duan, Chunying

    2016-11-23

    The combination of carbon dioxide capture and chemical fixation in a one-pot process is attractive for both chemists and governments. The cycloaddition of carbon dioxide with epoxides to produce cyclic carbonates is an atomic economical reaction without any side products. By incorporating acylamide to enhance the binding affinity toward CO2, new rht-type metal-organic frameworks (MOFs) with (3, 28) and (3, 24) connected units were constructed. Zn-NTTA with two types of dinuclear paddlewheel building blocks-{Zn2(OOC(-))4} and {Zn2(OOC(-))3}. The high uptake of CO2 (115.6 cm(3)·g(-1)) and selectivity over N2 (30:1) at 273 K indicated that these MOFs are excellent candidates for postcombustion CO2 isolation and capture. The MOFs feature high catalytic activity, rapid dynamics of transformation and excellent stability with turnover number (TON) values up to 110 000 per paddlewheel unit after 5 × 6 rounds of recyclability, demonstrating that they are promising heterogeneous catalysts for CO2 cyclo-addition to value-added cyclic carbonates. The cycloaddition of epoxides with wet gases demonstrated that the catalyst activity was not affected by moisture, and the indices of the PXRD patterns of the bulk samples filtered from the catalytic reaction revealed that the crystallinities were maintained. The combination of the selective capture and catalytic transformation in one-pot enables the use of a negative-cost feedstock-raw power plant flue gas without any separation and purification-revealing the broad prospects of such MOFs for practical CO2 fixation in industry.

  17. The Effect of Transition-Metal Addition on the Non-Equilibrium E.M.F.-TYPE SnO2 Gas Sensor

    NASA Astrophysics Data System (ADS)

    Joo, Jong Hoon; Choi, Gyeong Man

    Solid-oxide electrolytes develop electrical potential when their two opposite electrodes are exposed to the different oxygen potential. When an electrolyte is exposed to the same ambient gas, a potential may develop due to the different catalytic behavior of two electrodes to ambient gas. Such a sensor is called as a non-equilibrium e.m.f.-type sensor or mixed potential sensor. In this study, to improve the sensitivity of the sensor to reducing gases (CO, H2), transition metal oxide (T.M.O.) was added to one of two SnO2 electrodes of the sensor. T.M.O. addition was expected to change the catalytic behavior of the electrode and to change e.m.f. values. The Co addition increased the e.m.f. of working electrode (T.M.O.-added SnO2) in air, implying the enhanced oxygen adsorption. Fe addition showed the reverse effect. The addition of T.M.O. to SnO2 was also effective in changing the e.m.f. values in H2 balanced by air. Fe and Ni addition exhibited decreased e.m.f. in H2 from that in air. Thus, Fe and Ni addition improved the catalytic activity for H2 oxidation. On the other hand, the catalytic activity for H2 oxidation was suppressed by Co addition. However, no appreciable change in CO sensitivity was obtained with the T.M.O. addition.

  18. Hayabusa2 Sample Catcher and Container: Metal-Seal System for Vacuum Encapsulation of Returned Samples with Volatiles and Organic Compounds Recovered from C-Type Asteroid Ryugu

    NASA Astrophysics Data System (ADS)

    Okazaki, Ryuji; Sawada, Hirotaka; Yamanouchi, Shinji; Tachibana, Shogo; Miura, Yayoi N.; Sakamoto, Kanako; Takano, Yoshinori; Abe, Masanao; Itoh, Shoichi; Yamada, Keita; Yabuta, Hikaru; Okamoto, Chisato; Yano, Hajime; Noguchi, Takaaki; Nakamura, Tomoki; Nagao, Keisuke

    2016-10-01

    The spacecraft Hayabusa2 was launched on December 3, 2014, to collect and return samples from a C-type asteroid, 162173 Ryugu (provisional designation, 1999 JU3). It is expected that the samples collected contain organic matter and water-bearing minerals and have key information to elucidate the origin and history of the Solar System and the evolution of bio-related organics prior to delivery to the early Earth. In order to obtain samples with volatile species without terrestrial contamination, based on lessons learned from the Hayabusa mission, the sample catcher and container of Hayabusa2 were refined from those used in Hayabusa. The improvements include (1) a mirror finish of the inner wall surface of the sample catcher and the container, (2) adoption of an aluminum metal sealing system, and (3) addition of a gas-sampling interface for gas collection and evacuation. The former two improvements were made to limit contamination of the samples by terrestrial atmosphere below 1 Pa after the container is sealed. The gas-sampling interface will be used to promptly collect volatile species released from the samples in the sample container after sealing of the container. These improvements maintain the value of the returned samples.

  19. Hopping conduction in p-type MoS{sub 2} near the critical regime of the metal-insulator transition

    SciTech Connect

    Park, Tae-Eon; Jang, Chaun E-mail: presto@kist.re.kr; Suh, Joonki; Wu, Junqiao; Seo, Dongjea; Park, Joonsuk; Lin, Der-Yuh; Huang, Ying-Sheng; Choi, Heon-Jin; Chang, Joonyeon E-mail: presto@kist.re.kr

    2015-11-30

    We report on temperature-dependent charge and magneto transport of chemically doped MoS{sub 2}, p-type molybdenum disulfide degenerately doped with niobium (MoS{sub 2}:Nb). The temperature dependence of the electrical resistivity is characterized by a power law, ρ(T) ∼ T{sup −0.25}, which indicates that the system resides within the critical regime of the metal-insulator (M-I) transition. By applying high magnetic field (∼7 T), we observed a 20% increase in the resistivity at 2 K. The positive magnetoresistance shows that charge transport in this system is governed by the Mott-like three-dimensional variable range hopping (VRH) at low temperatures. According to relationship between magnetic-field and temperature dependencies of VRH resistivity, we extracted a characteristic localization length of 19.8 nm for MoS{sub 2}:Nb on the insulating side of the M-I transition.

  20. Experimental Study of Floating-Gate-Type Metal-Oxide-Semiconductor Capacitors with Nanosize Triangular Cross-Sectional Tunnel Areas for Low Operating Voltage Flash Memory Application

    NASA Astrophysics Data System (ADS)

    Liu, Yongxun; Guo, Ruofeng; Kamei, Takahiro; Matsukawa, Takashi; Endo, Kazuhiko; O'uchi, Shinichi; Tsukada, Junichi; Yamauchi, Hiromi; Ishikawa, Yuki; Hayashida, Tetsuro; Sakamoto, Kunihiro; Ogura, Atsushi; Masahara, Meishoku

    2012-06-01

    The floating-gate (FG)-type metal-oxide-semiconductor (MOS) capacitors with planar (planar-MOS) and three-dimensional (3D) nanosize triangular cross-sectional tunnel areas (3D-MOS) have successfully been fabricated by introducing rapid thermal oxidation (RTO) and postdeposition annealing (PDA), and their electrical characteristics between the control gate (CG) and FG have been systematically compared. It was experimentally found in both planar- and 3D-MOS capacitors that the uniform and higher breakdown voltages are obtained by introducing RTO owing to the high-quality thermal oxide formation on the surface and etched edge regions of the n+ polycrystalline silicon (poly-Si) FG, and the leakage current is highly suppressed after PDA owing to the improved quality of the tetraethylorthosilicate (TEOS) silicon dioxide (SiO2) between CG and FG. Moreover, a lower breakdown voltage between CG and FG was obtained in the fabricated 3D-MOS capacitors as compared with that of planar-MOS capacitors thanks to the enhanced local electric field at the tips of triangular tunnel areas. The developed nanosize triangular cross-sectional tunnel area is useful for the fabrication of low operating voltage flash memories.

  1. Fabrication of low-cost beta-type Ti-Mn alloys for biomedical applications by metal injection molding process and their mechanical properties.

    PubMed

    Santos, Pedro Fernandes; Niinomi, Mitsuo; Liu, Huihong; Cho, Ken; Nakai, Masaaki; Itoh, Yoshinori; Narushima, Takayuki; Ikeda, Masahiko

    2016-06-01

    Titanium and its alloys are suitable for biomedical applications owing to their good mechanical properties and biocompatibility. Beta-type Ti-Mn alloys (8-17 mass% Mn) were fabricated by metal injection molding (MIM) as a potential low cost material for use in biomedical applications. The microstructures and mechanical properties of the alloys were evaluated. For up to 13 mass% Mn, the tensile strength (1162-938MPa) and hardness (308-294HV) of the MIM fabricated alloys are comparable to those of Ti-Mn alloys fabricated by cold crucible levitation melting. Ti-9Mn exhibits the best balance of ultimate tensile strength (1046MPa) and elongation (4.7%) among the tested alloys, and has a Young's modulus of 89GPa. The observed low elongation of the alloys is attributed to the combined effects of high oxygen content, with the presence of interconnected pores and titanium carbides, the formation of which is due to carbon pickup during the debinding process. The elongation and tensile strength of the alloys decrease with increasing Mn content. The Ti-Mn alloys show good compressive properties, with Ti-17Mn showing a compressive 0.2% proof stress of 1034MPa, and a compressive strain of 50%.

  2. Ab initio calculations on elastic properties in L12 structure Al3X and X3Al-type (X=transition or main group metal) intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Tian, T.; Wang, X. F.; Li, W.

    2013-03-01

    As high-temperature structural materials, L12 intermetallic compounds have attracted the strong interest from both fundamental and industrial aspects. Understanding of elastic property is a basis for the complete investigations of mechanical behavior of L12 alloys. In an effort to explore the electronic origin of elastic properties of L12 intermetallics, we have performed a systematic study on elastic constants for single crystals, and Young's modulus, shear modulus, bulk modulus and Poisson's ratio for poly-crystals of 22 known Al3X and X3Al-type (X=transition or main group metal) intermetallics using the ab initio calculations. Based on the calculations of elastic constants and extreme (both positive and negative) Poisson's ratios, we found a pronounced correlation between the extreme Poisson's ratio and the elastic anisotropy, i.e., approximate 40% of the investigated L12 intermetallics exhibit intrinsic auxetic behavior. Furthermore, based on the distribution of bonding charge densities, we revealed that the ductility and extreme Poisson's ratios were attributable to the directionality of bonds of these alloys. Our findings provide a new method to predict mechanical behavior of intermetallics.

  3. Ospdr9, which encodes a PDR-type ABC transporter, is induced by heavy metals, hypoxic stress and redox perturbations in rice roots.

    PubMed

    Moons, Ann

    2003-10-23

    Little is known about the role of pleiotropic drug resistance (PDR)-type ATP-binding (ABC) proteins in plant responses to environmental stresses. We characterised ospdr9, which encodes a rice ABC protein with a reverse (ABC-TMS(6))(2) configuration. Polyethylene glycol and the heavy metals Cd (20 microM) and Zn (30 microM) rapidly and markedly induced ospdr9 in roots of rice seedlings. Hypoxic stress also induced ospdr9 in rice roots, salt stress induced ospdr9 at low levels but cold and heat shock had no effect. The plant growth regulator jasmonic acid, the auxin alpha-naphthalene acetic acid and the cytokinin 6-benzylaminopurine triggered ospdr9 expression. The antioxidants dithiothreitol and ascorbic acid rapidly and markedly induced ospdr9 in rice roots; the strong oxidant hydrogen peroxide also induced ospdr9 but at three times lower levels. The results suggested that redox changes may be involved in the abiotic stress response regulation of ospdr9 in rice roots.

  4. Synthesis, water adsorption, and proton conductivity of solid-solution-type metal-organic frameworks Al(OH)(bdc-OH)(x)(bdc-NH2)(1-x).

    PubMed

    Yamada, Teppei; Shirai, Yuki; Kitagawa, Hiroshi

    2014-05-01

    Mixed-ligand metal-organic frameworks Al(bdc-OH)(x)(bdc-NH2)(1-x) (H2bdc-NH2 = aminoterepthalic acid, H2bdc-OH = hydroxyterephthalic acid) were synthesized and their water adsorption behavior and proton conductivity were investigated. All obtained compounds were isostructural to MIL-53 (MIL = Materials of Institut Lavoisier) according to XRD measurements under ambient humidity conditions, and were also found to be single phase across the whole mixing ratio from the XRD measurements under humidified conditions. This result clearly shows that all compounds are a solid-solution-type mixture of ligands. MIL-53-NH2 adsorbs one water molecule per formula with humidification whereas MIL-53-OH adsorbs five water molecules. The mixing ratio of the ligands in Al(OH)(bdc-OH)(x)(bdc-NH2)(1-x) affected the gate-opening pressure for water adsorption and total water uptake. Proton conductivity of these compounds largely depends on the adsorbed amount of water, which indicates that the proton conductivity of these compounds depends strongly on the hydrogen-bond network of the conducting media.

  5. Control of Subthreshold Characteristics of Narrow-Channel Silicon-on-Insulator n-Type Metal-Oxide-Semiconductor Transistor with Additional Side Gate Electrodes

    NASA Astrophysics Data System (ADS)

    Okuyama, Kiyoshi; Yoshikawa, Koji; Sunami, Hideo

    2007-04-01

    A silicon-on-insulator (SOI) n-type metal-oxide-semiconductor (MOS) transistor with additional side gate electrodes is fabricated and its subthreshold characteristics are discussed. Since its device structure provides independent biasing to gates, flexible device-characteristic control for the respective device is expected. The key fabrication process is the formation of transistor gates. Additional side gate electrodes are formed by reactive ion etching (RIE) with a SiO2-covered top gate as an etching mask. Subthreshold characteristics are improved by negative side-gate biasing. In addition, the side-gate voltage VSG required to decrease off-leakage current by one decade is around 100 mV. Since the sidewall oxide thickness is chosen to be 5 nm, which is the same as the top-oxide thickness, rather sensitive subthreshold-characteristic control compared with that of biasing through a thick buried-oxide layer is achieved in response to performance requirement. In the viewpoint of stand-by-power suppression, these provide a certain controllability to a circuit operation.

  6. Lead free CH3NH3SnI3 perovskite thin-film with p-type semiconducting nature and metal-like conductivity

    NASA Astrophysics Data System (ADS)

    Iefanova, Anastasiia; Adhikari, Nirmal; Dubey, Ashish; Khatiwada, Devendra; Qiao, Qiquan

    2016-08-01

    Lead free CH3NH3SnI3 perovskite thin film was prepared by low temperature solution processing and characterized using current sensing atomic force microscopy (CS-AFM). Analysis of electrical, optical, and optoelectrical properties reveals unique p-type semiconducting nature and metal like conductivity of this material. CH3NH3SnI3 film also showed a strong absorption in visible and near infrared spectrum with absorption onset of 1.3 eV. X-ray Diffraction analysis and scanning electron microscopy (SEM) confirmed a structure of this compound and uniform film formation. The morphology, film uniformity, light harvesting and electrical properties strongly depend on preparation method and precursor solution. CH3NH3SnI3 films prepared based on dimethylformamide (DMF) showed higher crystallinity and light harvesting capability compared to the film based on combination of dimethyl sulfoxide (DMSO) with gamma-butyrolactone (GBL). Local photocurrent mapping analysis showed that CH3NH3SnI3 can be used as an active layer and have a potential to fabricate lead free photovoltaic devices.

  7. High-throughput aided synthesis of the porous metal-organic framework-type aluminum pyromellitate, MIL-121, with extra carboxylic acid functionalization.

    PubMed

    Volkringer, Christophe; Loiseau, Thierry; Guillou, Nathalie; Férey, Gérard; Haouas, Mohamed; Taulelle, Francis; Elkaim, Erik; Stock, Norbert

    2010-11-01

    A new porous metal-organic framework (MOF)-type aluminum pyromellitate (MIL-121 or Al(OH)[H(2)btec]·(guest), (guest = H(2)O, H(4)btec = pyromellitic acid) has been isolated by using a high-throughput synthesis method under hydrothermal conditions. Its structure was determined from powder X-ray diffraction analysis using synchrotron radiation (Soleil, France) and exhibits a network closely related to that of the MIL-53 series. It is a three-dimensional (3D) framework containing one-dimensional (1D) channels delimited by infinite trans-connected aluminum-centered octahedra AlO(4)(OH)(2) linked through the pyromellitate ligand. Here the organic ligand acts as tetradendate linker via two of the carboxylate groups. The two others remain non-bonded in their protonated form, and this constitutes a rare case of the occurrence of both bonding and non-bonding organic functionalities of the MOF family. The non-coordinated -COOH groups points toward the channels to get them an open form configuration. Within the tunnels are located unreacted pyromellitic acid and water species, which are evacuated upon heating, and a porous MIL-121 phase is obtained with a Brunauer-Emmett-Teller (BET) surface area of 162 m(2) g(-1). MIL-121 has been characterized by IR, thermogravimetry (TG) analyses, and solid state NMR spectroscopy employing a couple of two-dimensional (2D) techniques such as (1)H-(1)H SQ-DQ BABA, (1)H-(1)H SQ-SQ RFDR, (27)Al{(1)H} CPHETCOR and (27)Al MQMAS.

  8. The age-mass-metallicity-activity relation for solar-type stars: comparisons with asteroseismology and the NGC 188 open cluster

    NASA Astrophysics Data System (ADS)

    Lorenzo-Oliveira, D.; Porto de Mello, G. F.; Schiavon, R. P.

    2016-10-01

    Context. The Mount Wilson Ca ii index log(R'_HK) is the accepted standard metric of calibration for the chromospheric activity versus age relation for FGK stars. Recent results claim its inability to discern activity levels, and thus ages, for stars older than ~2 Gyr, which would severely hamper its application to date disk stars older than the Sun. Aims: We present a new activity-age calibration of the Mt. Wilson index that explicitly takes mass and [Fe/H] biases into account; these biases are implicit in samples of stars selected to have precise ages, which have so far not been appreciated. Methods: We show that these selection biases tend to blur the activity-age relation for large age ranges. We calibrate the Mt. Wilson index for a sample of field FGK stars with precise ages, covering a wide range of mass and [Fe/H] , augmented with data from the Pleiades, Hyades, M 67 clusters, and the Ursa Major moving group. Results: We further test the calibration with extensive new Gemini/GMOS log ()R'HK) data of the old, solar [Fe/H] clusters, M 67 and NGC 188. The observed NGC 188 activity level is clearly lower than M 67. We correctly recover the isochronal age of both clusters and establish the viability of deriving usable chromospheric ages for solar-type stars up to at least ~6 Gyr, where average errors are ~0.14 dex provided that we explicitly account for the mass and [Fe/H] dimensions. We test our calibration against asteroseismological ages, finding excellent correlation (ρ = + 0.89). We show that our calibration improves the chromospheric age determination for a wide range of ages, masses, and metallicities in comparison to previous age-activity relations.

  9. Half-metallic fully compensated ferrimagnetism in C1b-type half Heusler compounds Mn2Si1-xGex

    NASA Astrophysics Data System (ADS)

    Zhang, Y. J.; Liu, Z. H.; Liu, G. D.; Ma, X. Q.

    2015-08-01

    First-principles electronic structure calculations have been performed for the 18-valence electrons compounds Mn2Si1-xGex(x=0, 0.25, 0.5, 0.75, 1). The results suggest that Mn2Si1-xGex compounds in C1b structure are half-metallic fully compensated ferrimagnets. Furthermore, the size of the half-metallic band gap, the position of the Fermi level, and the magnetic moment of Mn atoms can be manipulated by changing x from 0 to 1 without destroying the half-metallic fully compensated ferrimagnetic property.

  10. Metallated metal-organic frameworks

    DOEpatents

    Bury, Wojciech; Farha, Omar K.; Hupp, Joseph T.; Mondloch, Joseph E.

    2017-02-07

    Porous metal-organic frameworks (MOFs) and metallated porous MOFs are provided. Also provided are methods of metallating porous MOFs using atomic layer deposition and methods of using the metallated MOFs as catalysts and in remediation applications.

  11. Theoretical investigation of the structure and nature of the interaction in metal-alkane σ-complexes of the type [M(CO) 5(C 2H 6)] (M = Cr, Mo, and W)

    NASA Astrophysics Data System (ADS)

    Da Silva, Júlio C. S.; De Almeida, Wagner B.; Rocha, Willian R.

    2009-11-01

    Density Functional Theory calculations were carried out to study the structure, energetics of the interactions and nature of the bonds in the metal-alkane σ-complexes of the type M(CO) 5(C 2H 6) M = Cr, Mo, and W. Only the η 1 coordination mode through hydrogen is obtained. The vibrational frequencies showed that upon coordination the ν(C-H) asym mode has an important red shift of 273 cm -1 and thus may be an important mode to characterize and follow the alkane coordination to the metallic fragment. TD-DFT calculations of the electronic transitions show that the coordination of the alkane affects drastically the metal to ligand charge transfer (MLCT) band of the metallic fragment, showing a blue shift of 163 nm. The computed AIM local properties ( ρ( r), ∇2(ρ), G( r), V( r) and H( r)) in conjunction with the Morokuma energy decomposition analysis (EDA) and also comparisons with the water dimer, suggest that this metal-alkane interaction may also be viewed as an unconventional hydrogen bond, with significant charge transfer and polarization contribution.

  12. Magnesium substitutions in rare-earth metal germanides with the Gd5Si4 type. Synthesis, structure determination and magnetic properties of RE5-xMgxGe4 (RE=Gd-Tm, Lu and Y)

    SciTech Connect

    Sarrao, J L; Thompson, Joe D; Tobash, P H; Bobev, S

    2009-01-01

    A series of magnesium-substituted rare-earth metal germanides with a general formula RE{sub 5-x}Mg{sub x}Ge{sub 4} (x {approx} 1.0-2.3; RE =Gd-Tm, Lu, Y) have been synthesized by high-temperature reactions and structurally characterized by single-crystal X-ray diffraction. These compounds crystallize with the common Gd{sub 5}Si{sub 4} type in the orthorhombic space group Pnma (No. 62; Z =4; Pearson's code oP36) and do not appear to undergo temperature-induced crystallographic phase transitions down to 120 K. Replacing rare-earth metal atoms with Mg, up to nearly 45 % at., reduces the valence electron count and is clearly expressed in the subtle changes of the Ge-Ge and metal-metal bonding. Magnetization measurements as a function of the temperature and the applied field reveal complex magnetic structures at cryogenic temperatures, and Curie-Weiss paramagnetic behavior at higher temperatures. The observed local moment magnetism is consistent with RE+ ground states in all cases. In the magnetically ordered phases, the magnetization cannot reach saturation in fields up to 50 kOe. The structural trends across the series and the variations of hte magnetic properties as a function of the Mg content are also discussed. KEYWORDS: Rare-earth intermetallics, germanides, crystal structure,Gd{sub 5}Si{sub 4} type.

  13. A Hydrophobic Metal-Organic Framework Based on Cubane-Type [Co4 (μ3 -F)3 (μ3 -SO4 )](3+) Clusters for Gas Storage and Adsorption Selectivity of Benzene over Cyclohexane.

    PubMed

    Zhang, Lei; Yang, Wenbin; Wu, Xiao-Yuan; Lu, Can-Zhong; Chen, Wen-Zhe

    2016-08-01

    Hydrophobic metal-organic frameworks (MOFs) not only have high water stability, but also exhibit high adsorption capacity towards organic molecules, in particular hydrocarbons. Herein we report a rare metal fluoride organic framework MFOF-1 with high hydrophobicity, which is constructed from unprecedented fluoride- and sulfate-bridged cubane-type tetranuclear cobalt clusters. MFOF-1 consists of three types of polyhedral cages with face-sharing configurations, and possesses a novel (3,9)-connected 3D+3D→3D self-interpenetrating array or the rare pyr topology. MFOF-1 shows high thermal stability and high stability in water and even acid/base aqueous solutions, and exhibits rather high H2 and CO2 storage capacities at ambient pressure. Remarkably, MFOF-1 shows little adsorption of water but considerably high uptakes of methanol, n-hexane, cyclohexane, and benzene, and exhibits a certain degree of adsorption selectivity of benzene over cyclohexane.

  14. Transition metal-free one-pot synthesis of fused 1,4-thiazepin-5(4H)-ones and theoretical study of the S-N type smiles rearrangement process.

    PubMed

    Yang, Bingchuan; Tan, Xiaochen; Guo, Ruiying; Chen, Shunwei; Zhang, Zeyuan; Chu, Xianglong; Xie, Caixia; Zhang, Dongju; Ma, Chen

    2014-09-05

    A series of 1,4-thiazepin-5(4H)-one derivatives were synthesized via a transition metal-free one-pot Smiles rearrangement process at room temperature. Regioselective seven-membered heterocycles were constructed in good to excellent yields. To gain an in-depth understanding of the S-N type Smiles rearrangement mechanism, a theoretical study was also performed by quantum chemistry calculations.

  15. The Metal-Rich Universe

    NASA Astrophysics Data System (ADS)

    Israelian, Garik; Meynet, Georges

    2012-10-01

    Preface; Part I. Abundances in the Galaxy: Field Stars: 1. Metal-rich stars and stellar populations: A brief history and new results; 2. The metal-rich nature of stars with planets; 3. Solar chemical peculiarities; 4. Kinematics of metal-rich stars with and without planets; 5. Elemental abundance trends in the metal-rich thin and thick disks; 6. Metal-rich massive stars - how metal-rich are they?; 7. Hercules stream stars and the metal-rich thick disk; 8. Abundance survey of the galactic thick disk; Part II. Abundances in the Galaxy: Galactic Stars in Clusters, Bulges and Centre: 9. Galactic open clusters with super solar metallicities; 10. Old and very metal-rich open clusters in the BOCCE project; 11. Massive stars vs. nebular abundances in the Orion nebula; 12. Abundance surveys of metal-rich bulge stars; 13. Metal abundances in the galactic center; 14. Light elements in the galactic bulge; 15. Metallicity and ages of selected G-K giants; Part III. Observations - Abundances in Extragalactic Contexts: 16. Stellar abundances of early-type galaxies and galactic spheroids: Evidence for metal-rich stars; 17. Measuring chemical abundances in extragalactic metal-rich HII regions; 18. On the maximum oxygen abundance in metal-rich spiral galaxies; 19. Starbursts and their contribution to metal enrichment; 20. High metallicities at high redshifts; 21. Evolution of dust and elemental abundances in quasar DLAs and GRB afterglows as a function of cosmic time; 22. Dust, metals and diffuse interstellar bands in damped Lyman Alpha systems; 23. Tracing metallicities in the Universe with the James Webb Space Telescope; Part IV. Stellar Populations and Mass Functions: 24. The stellar initial mass function of metal-rich populations; 25. IMF effects on the metallicity and colour evolution of disk galaxies; 26. The metallicity of circumnuclear star forming regions; 27. The stellar population of bulges; 28. The metallicity distribution of the stars in elliptical galaxies; 29. Wolf

  16. Investigation of porous Ni-based metal-organic frameworks containing paddle-wheel type inorganic building units via high-throughput methods.

    PubMed

    Maniam, Palanikumar; Stock, Norbert

    2011-06-06

    In the search of Ni based metal-organic frameworks (MOFs) containing paddle-wheel type building units, three chemical systems Ni(2+)/H(n)L/base/solvent with H(n)L = H(3)BTC (1,3,5-benzenetricarboxylic acid), H(3)BTB (4,4',4'',-benzene-1,3,5-triyl-tris(benzoic acid)), and H(2)BDC (terephthalic acid) were investigated using high-throughput (HT) methods. In addition to the conventional heating, for the first time HT microwave assisted synthesis of MOFs was carried out. Six new compounds were discovered, and their fields of formation were established. In the first system, H(3)BTC was employed and a comprehensive HT-screening of compositional and process parameters was conducted. The synthesis condition for the Ni paddle-wheel unit was determined and two compounds [Ni(3)(BTC)(2)(Me(2)NH)(3)]·(DMF)(4)(H(2)O)(4) (1a) and [Ni(6)(BTC)(2)(DMF)(6)(HCOO)(6)] (1b) were discovered (Me(2)NH = dimethylamine, DMF = dimethylformamide). In the second system, the use of the extended tritopic linker H(3)BTB and the synthesis conditions for the paddle-wheel units led to the porous MOF, [Ni(3)(BTB)(2)(2-MeIm)(1.5)(H(2)O)(1.5)]·(DMF)(9)(H(2)O)(6.5) (2), (2-MeIm = 2-methylimidazole). This compound shows a selective adsorption of H(2)O and H(2) with a strong hysteresis. In the third system, H(2)BDC was used, and the base (DABCO) was incorporated as a bridging ligand into all structures. Thus, two pillared layered porous MOFs [Ni(2)(BDC)(2)(DABCO)]·(DMF)(4)(H(2)O)(1.5) (3a) and [Ni(2)(BDC)(2)(DABCO)]·(DMF)(4)(H(2)O)(4) (3b) as well as a layered compound [Ni(BDC)(DABCO)]·(DMF)(1.5)(H(2)O)(2) (3c) were isolated. The 3a and 3b polymorphs of the [Ni(2)(BDC)(2)(DABCO)] framework can be selectively synthesized. The combination of microwave assisted heating, low overall concentration, stirring of the reaction mixtures, and an excess of DABCO yields a highly crystalline pure phase of 3b. The fields of formation of all compounds were established, and scale-up was successfully performed for 1b, 2

  17. Analysis of temperature dependent current-conduction mechanisms in Au/TiO2/n-4H-SiC (metal/insulator/semiconductor) type Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Alialy, S.; Altındal, Ş.; Tanrıkulu, E. E.; Yıldız, D. E.

    2014-08-01

    In order to determine the effective current-conduction mechanisms in Au/TiO2/n-4H-SiC (metal-insulator semiconductor) type Schottky barrier diodes (SBDs), their current-voltage (I-V) measurements were carried out in the temperature range of 200-380 K. Some electrical parameters, such as ideality factor (n), zero-bias barrier height (BH) (ΦBo), series and shunt resistances (Rs, Rsh), were obtained as 5.09, 0.81 eV, 37.43 Ω, and 435 kΩ at 200 K and 2.68, 0.95 eV, 5.99 Ω, and 73 kΩ at 380 K, respectively. The energy density distribution profile of surface states (Nss) was extracted from the forward-bias I-V data by taking into account voltage dependent of the ideality factor (nV), effective BH (Φe), and Rs for 200, 300, and 380 K. The Ln(I) vs V plots are completely parallel in the intermediate bias voltages, which may be well explained by field emission (FE) mechanism for each temperature. On the other hand, the high value of n cannot be explained with this mechanism. Therefore, to explain the change in BH and n with temperature, ΦBo vs q/2kT plot was drawn to obtain an evidence of a Gaussian distribution (GD) of the BHs and thus the mean value of BH (Φ¯Bo) and standard deviation (σso) values were found from this plot as 1.396 eV and 0.176 V, respectively. The Φ¯Bo and Richardson constant (A*) values were found as 1.393 eV and 145.5 A.cm-2 K-2 using modified Ln(Io/T2)-(q2σs2/2k2T2) vs q/kT plot, respectively. It is clear that all of the obtained main electrical parameters were found as a strong function of temperature. These results indicated that the current conduction mechanism in Au/TiO2/n-4 H-SiC (SBD) well obey the FE and GD mechanism rather than other mechanisms.

  18. Statistical mechanics of light elements at high pressure. IV - A model free energy for the metallic phase. [for Jovian type planet interiors

    NASA Technical Reports Server (NTRS)

    Dewitt, H. E.; Hubbard, W. B.

    1976-01-01

    A large quantity of data on the thermodynamic properties of hydrogen-helium metallic liquids have been obtained in extended computer calculations in which a Monte Carlo code essentially identical to that described by Hubbard (1972) was used. A model free energy for metallic hydrogen with a relatively small mass fraction of helium is discussed, taking into account the definition of variables, a procedure for choosing the free energy, values for the fitting parameters, and the evaluation of the entropy constants. Possibilities concerning a use of the obtained data in studies of the interiors of the outer planets are briefly considered.

  19. Peroxotitanates for biodelivery of metals.

    PubMed

    Wataha, John C; Hobbs, David T; Lockwood, Petra E; Davis, Ryan R; Elvington, Mark C; Lewis, Jill B; Messer, Regina L W

    2009-11-01

    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 APTs 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 and then measured cellular mitochondrial activity (SDH-MTT method) to assess the biological impact of the metal-APT materials versus 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 APTs are plausible solid-phase delivery agents of metals or metal compounds to some types of cells for potential therapeutic effect.

  20. 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.

  1. Metals Sector

    EPA Pesticide Factsheets

    Find environmental regulatory information about the metals sector (NAICS 331 & 332), including NESHAPs for metal coatings, effluent guidelines for metal products, combustion compliance assistance, and information about foundry sand recycling.

  2. R3Au(6+x)Al26T (R = Ca, Sr, Eu, Yb; T = early transition metal): a large family of compounds with a stuffed BaHg11 structure type grown from aluminum flux.

    PubMed

    Latturner, Susan E; Bilc, Daniel; Mahanti, S D; Kanatzidis, Mercouri G

    2009-02-16

    A collection of new quaternary intermetallic compounds with a cubic, stuffed BaHg(11) structure type has been synthesized by the combination of a divalent rare earth or alkaline earth metal R, an early transition metal T, and gold in an excess of molten aluminum. Structural characterization of these R(3)Au(6+x)Al(26)T compounds by powder and single crystal X-ray diffraction indicates that the unit cell varies with the radii of the early transition metal T and the rare earth/alkaline earth R as expected. The element T (where T = group 4, 5, 6, and 7 element) appears to be responsible for the stabilization of up to 43 different members of the R(3)Au(6+x)Al(26)T family of compounds. Varying amounts of disorder and trends in partial occupancies of the Au stuffed site--the site that is vacant in the parent compound BaHg(11)--are also indicated by the diffraction studies of this family of compounds. Magnetic susceptibility data reveals that the transition metal atoms in these materials do not possess local magnetic moments. For the magnetic rare earth containing materials, the europium compounds undergo a ferromagnetic transition at 10 K, and the ytterbium analogues show mixed valent behavior. Band structure calculations also support a mixed valent state for Yb in these compounds.

  3. Millimeter Wave Metal-Insulator-Metal Detector/Mixer Diode.

    DTIC Science & Technology

    1983-12-01

    AO-A138 391 MILLIMETER WAVE METAL-INSULATOR- METAL DETECTOR /MIXER 1/1 DIODE(VI NORTH CAROLIN A AGRICULTURAL A NO TECHNI CA L STATE UNIV GREENSRO. C TV...163-A I V AFWAL-TR-83-1179 MILLIMETER WAVE METAL-INSULATOR- METAL DETECTOR /MIXER DIODE CHUNG YU NORTH CAROLINA A&T STATE UNIVERSITY GREENSBORO, NORTH...TITLE (ad subsorle.I S. TYPE CrjflT&PEO OER MILLIMETER WAVE May, 1981--July, 1983 METAL-INSULATOR- METAL DETECTOR /MIXER G. PERFORMING ORG. REPORT

  4. 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.

  5. First-principles study on magnetism and half-metallicity in bulk and various (001) surfaces of Heusler alloy Zr2VSn with Hg2CuTi-type structure

    NASA Astrophysics Data System (ADS)

    Deng, Zun-Yi; Zhang, Jian-Min

    2016-07-01

    Structural, electronic and magnetic properties in the bulk and five different (001) surfaces (ZrV-, ZrSn-, VV-, ZrZr- and SnSn-terminations) of Zr2 VSn Heusler alloy with Hg2 CuTi -type structure are studied by using first-principles calculations based on density-functional theory. The bulk Zr2 VSn Heusler alloy is ferrimagnetic half-metallicity with equilibrium lattice constant 6.815 Å and total magnetic moment -1.000 μB / f.u . , following the Slater-Pauling rule μt =Zt - 18 . The atoms on different surface layers exhibit different displacements, electronic and magnetic properties. All five (001) surfaces lose the half-metallicity and are not usable in spintronics devices.

  6. Effect of metal ions on radical type and proton-coupled electron transfer channel: sigma-radical vs pi-radical and sigma-channel vs pi-channel in the imide units.

    PubMed

    Chen, Xiaohua; Xing, Dianxiang; Zhang, Liang; Cukier, Robert I; Bu, Yuxiang

    2009-12-01

    The mechanism of proton transfer (PT)/electron transfer (ET) in imide units, and its regulation by hydrated metal ions, was explored theoretically using density functional theory in a representative model (a nearly planar and cisoid complex between uracil and its N(3)-dehydrogenated radical, UU). In UU (sigma-radical), PT/ET normally occurs via a seven-center, cyclic proton-coupled sigma-electron sigma-channel transfer (PC(sigma)E(sigma)T) mechanism (3.8 kcal/mol barrier height) with a N(3)-->N(3') PT and an O(4)-->O(4') ET. Binding of hydrated metal ions to the dioxygen sites (O(2)/O(2') or/and O(4)/O(4')) of UU may significantly affect its PT/ET cooperative reactivity by changing the radical type (sigma-radical <--> pi-radical) and ET channel (sigma-channel <--> pi-channel), leading to different mechanisms, ranging from PC(sigma)E(sigma)T, to proton-coupled pi-electron sigma-channel transfer (PC(pi)E(sigma)T) to proton-coupled pi-electron pi-channel transfer (PC(pi)E(pi)T). This change originates from an alteration of the ordering of the UU moiety SOMO/HDMO (the singly occupied molecular orbital and the highest doubly occupied molecular orbital), induced by binding of the hydrated metal ions. It is a consequence of three associated factors: the asymmetric reactant structure, electron cloud redistribution, and fixing role of metal ions to structural backbone. The findings regarding the modulation of the PT/ET pathway via hydrated metal ions may provide valuable information for a greater understanding of PT/ET cooperative mechanisms, and an alternative way for designing imide-based molecular devices, such as molecular switches and molecular wires.

  7. INVESTIGATION OF ZrxLa1-xOy NANOCRYSTALLITES IN METAL-HIGH-k OXIDE-SILICON-TYPE NONVOLATILE MEMORY DEVICES

    NASA Astrophysics Data System (ADS)

    Bahari, Ali; Gholipur, Reza

    2012-12-01

    To investigate characterization of ZrxLa1-xOy nanocrystallites as a buffer oxide in forming the metal-oxide-semiconductor field effect transistors (MOSFETs) structure, we synthesized ZrxLa1-xOy nanocrystallites by sol-gel method. Moreover, from the solution prepared, thin films on silicon wafer substrates have been realized by "dip-coating" with a pulling out speed of 5 cm min-1. The structure, morphology, electrical properties of thin film was examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM) techniques. Electrical property characterization was performed with metal-oxide-semiconductor (MOS) structures through capacitance-voltage (C-V) and current density-voltage (J-V) measurements. The leakage current density was below 1.0 ×10-6A/cm2 at 1 MV/cm.

  8. Half-metallic ferromagnetism in chalcopyrite type compounds ZnMX{sub 2} (M=Sc, V, Mn, Fe; X = P, As)

    SciTech Connect

    Vijayalakshmi, D.; Kalpana, G. E-mail: g-kalpa@annauniv.edu

    2015-06-24

    Electronic structure and magnetic properties of ZnMX{sub 2} (M=Sc, V, Mn and Fe; X= As and P) compounds in body centred tetragonal chalcopyrite structure have been investigated using first-principles calculations based on density functional theory (DFT) within the local spin density approximation (LSDA). The spin-polarized electronic band structure and density of states of all these compounds show that the spin-up electrons have metallic and the spin-down electrons have a semiconducting gap and the magnetic moment mainly originates from the strong spin polarization of 3d states of transition metal (M=Sc, V, Mn and Fe) atoms and p-like states of anion X (P and As) atoms.

  9. Two zeolite-type frameworks in one metal-organic framework with Zn24 @Zn104 cube-in-sodalite architecture.

    PubMed

    Bu, Fei; Lin, Qipu; Zhai, Quanguo; Wang, Le; Wu, Tao; Zheng, Shou-Tian; Bu, Xianhui; Feng, Pingyun

    2012-08-20

    Two in one: A metal-organic framework obtained from three different inorganic building blocks (tetrameric Zn(4) O, trimeric Zn(3) OH, and monomeric Zn) posseses a nested cage-in-cage and framework-in-framework architecture. 24 Zn(4) O tetramers and eight Zn monomers form a sodalite cage into which a cubic cage made from eight Zn(3) (OH) trimers is nestled. Eight monomeric Zn(2+) centers interconnect these two cages.

  10. Cross-plane electronic and thermal transport properties of p-type La0.67Sr0.33MnO3/LaMnO3 perovskite oxide metal/semiconductor superlattices

    NASA Astrophysics Data System (ADS)

    Jha, Pankaj; Sands, Timothy D.; Cassels, Laura; Jackson, Philip; Favaloro, Tela; Kirk, Benjamin; Zide, Joshua; Xu, Xianfan; Shakouri, Ali

    2012-09-01

    Lanthanum strontium manganate (La0.67Sr0.33MnO3, i.e., LSMO)/lanthanum manganate (LaMnO3, i.e., LMO) perovskite oxide metal/semiconductor superlattices were investigated as a potential p-type thermoelectric material. Growth was performed using pulsed laser deposition to achieve epitaxial LSMO (metal)/LMO (p-type semiconductor) superlattices on (100)-strontium titanate (STO) substrates. The magnitude of the in-plane Seebeck coefficient of LSMO thin films (<20 μV/K) is consistent with metallic behavior, while LMO thin films were p-type with a room temperature Seebeck coefficient of 140 μV/K. Thermal conductivity measurements via the photo-acoustic (PA) technique showed that LSMO/LMO superlattices exhibit a room temperature cross-plane thermal conductivity (0.89 W/m.K) that is significantly lower than the thermal conductivity of individual thin films of either LSMO (1.60 W/m.K) or LMO (1.29 W/m.K). The lower thermal conductivity of LSMO/LMO superlattices may help overcome one of the major limitations of oxides as thermoelectrics. In addition to a low cross-plane thermal conductivity, a high ZT requires a high power factor (S2σ). Cross-plane electrical transport measurements were carried out on cylindrical pillars etched in LSMO/LMO superlattices via inductively coupled plasma reactive ion etching. Cross-plane electrical resistivity data for LSMO/LMO superlattices showed a magnetic phase transition temperature (TP) or metal-semiconductor transition at ˜330 K, which is ˜80 K higher than the TP observed for in-plane resistivity of LSMO, LMO, or LSMO/LMO thin films. The room temperature cross-plane resistivity (ρc) was found to be greater than the in-plane resistivity by about three orders of magnitude. The magnitude and temperature dependence of the cross-plane conductivity of LSMO/LMO superlattices suggests the presence of a barrier with the effective barrier height of ˜300 meV. Although the magnitude of the cross-plane power factor is too low for thermoelectric

  11. Electrode Plate For An Eletrlchemical Cell And Having A Metal Foam Type Support, And A Method Of Obtaining Such An Electrode

    DOEpatents

    Verhoog, Roelof; Precigout, Claude; Stewart, Donald

    1996-05-21

    The electrode plate includes an active portion that is pasted with active material, and a plate head that is made up of three layers of compressed metal foam comprising: a non-pasted portion of height G of the support of the electrode plate; and two strips of non-pasted metal foam of height R on either side of the non-pasted portion of height G of the support and also extending for an overlap height h.sub.2 over the pasted portion of the support. The plate head includes a zone of reduced thickness including a portion that is maximally compressed, and a transitional portion between said maximally compressed portion and the remainder of the electrode which is of thickness e.sub.2. A portion of said plate head forms a connection tab. The method of obtaining the electrode consists in simultaneously rolling all three layers of metal foam in the plate head, and then in cutting matter away from the plates so as to obtain respective connection tabs.

  12. Metal pad instabilities in liquid metal batteries

    NASA Astrophysics Data System (ADS)

    Zikanov, Oleg

    2016-11-01

    Strong variations between the electrical conductivities of electrolyte and metal layers in a liquid metal battery indicate the possibility of 'metal pad' instabilities. Deformations of the electrolyte-metal interfaces cause strong perturbations of electric currents, which, hypothetically, can generate Lorentz forces enhancing the deformations. We investigate this possibility using two models: a mechanical analogy and a two-dimensional linearized approximation. It is found that the battery is prone to instabilities of two types. One is similar to the sloshing-wave instability observed in the Hall-Héroult aluminum reduction cells. Another is new and related to the interactions of current perturbations with the azimuthal magnetic field induced by the base current. Financial support was provided by the U.S. National Science Foundation (Grant CBET 1435269).

  13. Draft Genome Sequences for Two Metal-Reducing Pelosinus fermentans Strains Isolated from a Cr(VI) Contaminated Site and for Type Strain R7

    SciTech Connect

    Brown, Steven D; Podar, Mircea; Klingeman, Dawn Marie; Johnson, Courtney M; Yang, Zamin Koo; Utturkar, Sagar M; Land, Miriam L; Mosher, Jennifer J; Hurt, Jr., Richard Ashley; Phelps, Tommy Joe; Palumbo, Anthony Vito; Arkin, Adam; Hazen, Terry C; Elias, Dwayne A

    2012-01-01

    Pelosinus fermentans 16S rRNA gene sequences have been reported from diverse geographical sites since the recent isolation of the type strain. We present the genome sequence of the P. fermentans type strain R7 (DSM 17108) and genome sequences for two new strains with different abilities to reduce iron, chromate, and uranium.

  14. [Environmental effects of applying heavy metal-containing municipal sewage sludge on wheat-rice rotation system on different types of soil].

    PubMed

    Ren, Jing; Cheng, Miao-Miao; Li, Rui; Liu, Ling; Wu, Long-Hua; Liu, Hong-Yan; Luo, Yong-Ming

    2012-02-01

    A pot experiment with the yellow soil and limestone soil from Guizhou province, and paddy soil from Zhejiang Province was conducted to study the impacts of applying municipal sewage sludge containing different concentrations of heavy metals on the wheat and rice growth and their Zn and Cd absorption. The risks of the crop heavy metals pollution caused by the application of the same sludge differed with tested soils. On the yellow soil and paddy soil, applying the sludge containing high concentration heavy metals induced higher pollution risks to the crops. Applying the sludge 1.6% in dry mass and containing 1789 mg x kg(-1) of Zn and 8.47 mg x kg(-1) of Cd to yellow soil made the Zn and Cd concentrations in wheat grains reached 109 and 0.08 mg x kg(-1), and after the second time application of the same dosage of this sludge after rice planting, the Zn and Cd concentrations in brown rice reached 52.0 and 0.54 mg x kg(-1), respectively. However, applying the sludge to calcareous soil had no pollution risk to the edible parts of wheat and rice. Soil NH4OAc-extractable Zn was the main factor affecting the Zn concentration in wheat grain and brown rice, but soil NH4OAc-extractable Cd had less effect on the Cd concentration in wheat grain and brown nce. Applying the sludge containing high concentration Zn and Cd to the three soils made the concentrations of total Zn and Cd in the soils increased significantly, and after the first time and the second time of the application, the total Zn concentration in the soils all exceeded the 2nd level of the national soil environmental quality standards.

  15. Assessing and Mapping Spatial Associations among Oral Cancer Mortality Rates, Concentrations of Heavy Metals in Soil, and Land Use Types Based on Multiple Scale Data

    PubMed Central

    Lin, Wei-Chih; Lin, Yu-Pin; Wang, Yung-Chieh; Chang, Tsun-Kuo; Chiang, Li-Chi

    2014-01-01

    In this study, a deconvolution procedure was used to create a variogram of oral cancer (OC) rates. Based on the variogram, area-to-point (ATP) Poisson kriging and p-field simulation were used to downscale and simulate, respectively, the OC rate data for Taiwan from the district scale to a 1 km × 1 km grid scale. Local cluster analysis (LCA) of OC mortality rates was then performed to identify OC mortality rate hot spots based on the downscaled and the p-field-simulated OC mortality maps. The relationship between OC mortality and land use was studied by overlapping the maps of the downscaled OC mortality, the LCA results, and the land uses. One thousand simulations were performed to quantify local and spatial uncertainties in the LCA to identify OC mortality hot spots. The scatter plots and Spearman’s rank correlation yielded the relationship between OC mortality and concentrations of the seven metals in the 1 km cell grid. The correlation analysis results for the 1 km scale revealed a weak correlation between OC mortality rate and concentrations of the seven studied heavy metals in soil. Accordingly, the heavy metal concentrations in soil are not major determinants of OC mortality rates at the 1 km scale at which soils were sampled. The LCA statistical results for local indicator of spatial association (LISA) revealed that the sites with high probability of high-high (high value surrounded by high values) OC mortality at the 1 km grid scale were clustered in southern, eastern, and mid-western Taiwan. The number of such sites was also significantly higher on agricultural land and in urban regions than on land with other uses. The proposed approach can be used to downscale and evaluate uncertainty in mortality data from a coarse scale to a fine scale at which useful additional information can be obtained for assessing and managing land use and risk. PMID:24566045

  16. A novel type of matrix for surface-assisted laser desorption-ionization mass spectrometric detection of biomolecules using metal-organic frameworks.

    PubMed

    Fu, Chien-Ping; Lirio, Stephen; Liu, Wan-Ling; Lin, Chia-Her; Huang, Hsi-Ya

    2015-08-12

    A 3D metal-organic framework (MOF) nanomaterial as matrix for surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) and tandem mass spectrometry (MS/MS) was developed for the analysis of complex biomolecules. Unlike other nanoparticle matrices, this MOF nanomaterial does not need chemical modification prior to use. An exceptional signal reproducibility as well as very low background interferences in analyzing mono-/di-saccharides, peptides and complex starch digests demonstrate its high potential for biomolecule assays, especially for small molecules.

  17. Preparation of metallic californium

    SciTech Connect

    Radchenko, V.M.; Seleznev, A.G.; Droznik, R.R.; Iebedeva, L.S.; Ryabinin, M.A.; Shushakov, V.D.; Vasil'ev, V.Ya.; Ermishev, V.T.

    1987-03-01

    A sample of metallic californium-249 with a mass of 710 ..mu..g was obtained in the form of a layer with a thickness of 2.4 +/- 0.3 ..mu..m on a quartz support. The overall yield of the vaporized metal was 84% of the starting amount of californium, and the yield of the metal on the support was 46%. It was established that metallic californium has a double hexagonal close-packed (hcp) structure of the ..cap alpha..-La type with the following parameters: a = 0.3380 +/- 0.0002, c = 1.1025 +/- 0.0002, c/2a = 1.631 +/- 0.001 nm, metallic radius 0.1689 +/- 0.0002 nm, and x-ray density 15.18 +/- 0.02 g/cm/sup 3/.

  18. Ultralow Contact Resistivity for a Metal/p-Type Silicon Interface by High-Concentration Germanium and Boron Doping Combined with Low-Temperature Annealing

    NASA Astrophysics Data System (ADS)

    Murakoshi, Atsushi; Iwase, Masao; Niiyama, Hiromi; Koike, Mitsuo; Suguro, Kyoichi

    2013-07-01

    A contact resistivity of 6.9×10-9 Ω.cm2 has been obtained in an AlSi (1 wt %)-Cu (0.5 wt %) alloy/silicon system by using heavy-dose ion implantations of germanium and boron combined with low-temperature annealing. The analysis of the combined state showed that B12 cluster was incorporated and the supersaturation activation layer was formed into the region where germanium separated. Separated germanium is expected to have high interface state density. It is considered that this interface state density also has a Fermi level, and in order to reduce the difference from the Fermi level of the substrate, the charge moves to interface state density from the substrate. As a result, it is not based on a metallic material but a work function becomes small because pinning by which a Fermi level is fixed to interface state density occurs owing to the substrate/metal interface. It is considered to be attributable to the existence of a Ge-rich layer formed by low-temperature annealing, and a supersaturation activation layer that lowers contact resistance was formed.

  19. Properties of the quaternary half-metal-type Heusler alloy Co{sub 2}Mn{sub 1-x}Fe{sub x}Si

    SciTech Connect

    Balke, Benjamin; Fecher, Gerhard H.; Kandpal, Hem C.; Felser, Claudia; Kobayashi, Keisuke; Ikenaga, Eiji; Kim, Jung-Jin; Ueda, Shigenori

    2006-09-01

    This paper reports on the bulk properties of the quaternary Heusler alloy Co{sub 2}Mn{sub 1-x}Fe{sub x}Si with the Fe concentration x=0,1/2,1. All samples, which were prepared by arc melting, exhibit L2{sub 1} long-range order over the complete range of Fe concentration. The structural and magnetic properties of the Co{sub 2}Mn{sub 1-x}Fe{sub x}Si Heusler alloys were investigated by means of x-ray diffraction, high- and low-temperature magnetometry, Moessbauer spectroscopy, and differential scanning calorimetry. The electronic structure was explored by means of high-energy photoemission spectroscopy at about 8 keV photon energy. This ensures true bulk sensitivity of the measurements. The magnetization of the Fe-doped Heusler alloys is in agreement with the values of the magnetic moments expected for a Slater-Pauling-like behavior of half-metallic ferromagnets. The experimental findings are discussed on the basis of self-consistent calculations of the electronic and magnetic structure. To achieve good agreement with experiment, the calculations indicate that on-site electron-electron correlation must be taken into account, even at low Fe concentration. The present investigation focuses on searching for the quaternary compound where the half-metallic behavior is stable against outside influences. Overall, the results suggest that the best candidate may be found at an iron concentration of about 50%.

  20. 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.

  1. A combined metal-halide/metal flux synthetic route towards type-I clathrates: crystal structures and thermoelectric properties of A8Al8Si38 (A = K, Rb, and Cs).

    PubMed

    Baran, Volodymyr; Senyshyn, Anatoliy; Karttunen, Antti J; Fischer, Andreas; Scherer, Wolfgang; Raudaschl-Sieber, Gabriele; Fässler, Thomas F

    2014-11-10

    Single-phase samples of the compounds K8Al8Si38 (1), Rb8Al8Si38 (2), and Cs7.9Al7.9Si38.1 (3) were obtained with high crystallinity and in good quantities by using a novel flux method with two different flux materials, such as Al and the respective alkali-metal halide salt (KBr, RbCl, and CsCl). This approach facilitates the removal of the product mixture from the container and also allows convenient extraction of the flux media due to the good solubility of the halide salts in water. The products were analyzed by means of single-crystal X-ray structure determination, powder X-ray and neutron diffraction experiments, (27)Al-MAS NMR spectroscopy measurements, quantum chemical calculations, as well as magnetic and transport measurements (thermal conductivity, electrical resistivity, and Seebeck coefficient). Due to the excellent quality of the neutron diffraction data, the difference between the nuclear scattering factors of silicon and aluminum atoms was sufficient to refine their mixed occupancy at specific sites. The role of variable-range hopping for the interpretation of the resistivity and the Seebeck coefficient is discussed.

  2. Gated Channels and Selectivity Tuning of CO2 over N2 Sorption by Post-Synthetic Modification of a UiO-66-Type Metal-Organic Framework.

    PubMed

    Kronast, Alexander; Eckstein, Sebastian; Altenbuchner, Peter T; Hindelang, Konrad; Vagin, Sergei I; Rieger, Bernhard

    2016-08-26

    The highly porous and stable metal-organic framework (MOF) UiO-66 was altered using post-synthetic modifications (PSMs). Prefunctionalization allowed the introduction of carbon double bonds into the framework through a four-step synthesis from 2-bromo-1,4-benzenedicarboxylic acid; the organic linker 2-allyl-1,4-benzenedicarboxylic acid was obtained. The corresponding functionalized MOF (UiO-66-allyl) served as a platform for further PSMs. From UiO-66-allyl, epoxy, dibromide, thioether, diamine, and amino alcohol functionalities were synthesized. The abilities of these compounds to adsorb CO2 and N2 were compared, which revealed the structure-selectivity correlations. All synthesized MOFs showed profound thermal stability together with an increased ability for selective CO2 uptake and molecular gate functionalities at low temperatures.

  3. Experimental investigations of a partial Ru-O bond during the metal-ligand bifunctional addition in Noyori-type enantioselective ketone hydrogenation.

    PubMed

    Takebayashi, Satoshi; Dabral, Nupur; Miskolzie, Mark; Bergens, Steven H

    2011-06-29

    The transition state for the metal-ligand bifunctional addition step in Noyori's enantioselective ketone hydrogenation was investigated using intramolecular trapping experiments. The bifunctional addition between the Ru dihydride trans-[Ru((R)-BINAP)(H)(2)((R,R)-dpen)] and the hydroxy ketone 4-HOCH(2)C(6)H(4)(CO)CH(3) at -80 °C exclusively formed the corresponding secondary ruthenium alkoxide trans-[Ru((R)-BINAP)(H)(4-HOCH(2)C(6)H(4)CH(CH(3))O)((R,R)-dpen)]. Combined with the results of control experiments, this observation provides strong evidence for the formation of a partial Ru-O bond in the transition state.

  4. 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)

  5. Silicone metalization

    SciTech Connect

    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.

  6. Silicone metalization

    SciTech Connect

    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.

  7. High-velocity-oxidation performance of metal-chromium-aluminum (MCrAl), cermet, and modified aluminide coatings on IN-100 and type VIA alloys at 1093 C

    NASA Technical Reports Server (NTRS)

    Deadmore, D. L.

    1974-01-01

    Cermet, MCrAl, and modified aluminide types of coatings applied to IN-100 and NASA-TRW-VIA alloy specimens were cyclically oxidation tested in a high velocity (Mach 1) gas flame at 1093 C. Several coating compositions of each type were evaluated for oxidation resistance. The modified aluminide coating, Pt-Al, applied to alloy 6A proved to be the best, providing oxidation protection to approximately 750 hours based on weight change measurements. The second best, a CoCrAlY coating applied to 6A, provided protection to 450 hours. The third best was a cermet + aluminide coating on 6A with a protection time to 385 hours.

  8. Metal-bearing Aerosols of Industrial Origin from Multiple Sources in South Phoenix, Arizona: Separating Similar Particle Types with Minor Element Differences Using Automated SEM Analysis of Large Populations of Particles

    NASA Astrophysics Data System (ADS)

    Anderson, J.; Hua, X.

    2009-12-01

    Particulate pollution, especially PM10, in the Greater Phoenix (Maricopa County) airshed is a long-standing problem. While much of the PM10 can be ascribed to soil dust entrained by human activity (e.g., sand and gravel mining and other construction-support activities both directly and indirectly), south-central and southwest Phoenix have a significant number of industrial sources of metal-bearing particles. Many of these particles are dominated compositionally by Fe but have minor elements such as Cu, Ba, Mn, Cr, Ni and others which can be statistically mutually exclusive when large populations are looked at with automated Scanning Electron Microscopy (SEM). Bulk aerosol chemical analysis of high-volume samples shows the presence of these elements, including the dominance of Fe at times, but there are far more potential sources than can ever by deduced by principal component analysis of the bulk sample data. Because of the potential toxic nature of these industrial particles, about which there is considerable community concern, identifying the multiple sources is a key step in mitigating the pollution. Also present in these industrial aerosols are mostly submicron particles containing Sr, Sb, V, Cd, and other elements in various combinations. While analyzing the minor element content of submicron particles, some of which are beam-sensitive, pushes the limits of automated SEM techniques, this is the only way to examine large, statistically significant particle populations in many samples on an individual-particle basis. The elemental associations in these unusual metal-bearing particles tend to be the key to source identification. Particle morphology is also important in separating particle types from different sources in these populations. For instance, one of major sources of Fe-dominant particles in southwest Phoenix is a scrap metal operation that uses a “mega-shredder”. This mega-shredder generates enough heat to melt some of the metal and produce roughly

  9. High gas storage capacities and stepwise adsorption in a UiO type metal-organic framework incorporating Lewis basic bipyridyl sites.

    PubMed

    Li, Liangjun; Tang, Sifu; Wang, Chao; Lv, Xiaoxia; Jiang, Min; Wu, Huaizhi; Zhao, Xuebo

    2014-03-04

    A UiO type MOF with Lewis basic bipyridyl sites was synthesized and structurally characterized. After being activated by Soxhlet-extraction, this MOF exhibits high storage capacities for H2, CH4 and CO2, and shows unusual stepwise adsorption for liquid CO2 and solvents, indicating a sequential filling mechanism on different adsorption sites.

  10. Residual and intentional n-type doping of ZnO thin films grown by metal-organic vapor phase epitaxy on sapphire and ZnO substrates

    NASA Astrophysics Data System (ADS)

    Brochen, Stéphane; Lafossas, Matthieu; Robin, Ivan-Christophe; Ferret, Pierre; Gemain, Frédérique; Pernot, Julien; Feuillet, Guy

    2014-03-01

    ZnO epilayers usually exhibit high n-type residual doping which is one of the reasons behind the difficulties to dope this material p-type. In this work, we aimed at determining the nature of the involved impurities and their potential role as dopant in ZnO thin films grown by metalorganic vapor phase epitaxy (MOVPE) on sapphire and ZnO substrates. In both cases, secondary ion mass spectroscopy (SIMS) measurements give evidence for a strong diffusion of impurities from the substrate to the epilayer, especially for silicon and aluminum. In the case of samples grown on sapphire substrates, aluminum follows Fick's diffusion law on a wide growth temperature range (800-1000°C). Thus, the saturation solubility and the diffusion coefficient of aluminum in ZnO single crystals have been determined. Furthermore, the comparison between SIMS impurity and effective dopant concentrations determined by capacitance-voltage measurements highlights, on one hand a substitutional mechanism for aluminum diffusion, and on the other hand that silicon acts as a donor in ZnO and not as an amphoteric impurity. In addition, photoluminescence spectra exhibit excitonic recombinations at the same energy for aluminum and silicon, indicating that silicon behaves as an hydrogenic donor in ZnO. Based on these experimental observations, ZnO thin films with a controlled n-type doping in the 1016-1019cm-3 range have been carried out. These results show that MOVPE growth is fully compatible with the achievement of highly Al-doped n-type thin films, but also with the growth of materials with low residual doping, which is a crucial parameter to address ZnO p-type doping issues.

  11. 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.

  12. Elaboration and characterization of solid materials of types zeolite NaA and faujasite NaY exchanged by zinc metallic ions Zn2+

    NASA Astrophysics Data System (ADS)

    Nibou, D.; Amokrane, S.; Mekatel, H.; Lebaili, N.

    2009-11-01

    The present work deals with the elaborated of NaA and faujasite NaY solid materials according to a hydrothermal crystallization of amorphous gels composed of solutions of silicon, aluminum and sodium. The process elaboration has been achieved in autoclaves made of steel lined in Teflon under different operating conditions of temperature of heating, time of contact and stirring. After crystallization, the samples were characterized by different techniques such as X ray diffraction, scanning electronic microscopy, infrared spectroscopy, thermal analysis, and chemical analysis. Pure solid materials NaA and NaY zeolites were obtained and were impregnated by (Zn2+) ions by ion exchange process. The effects of various parameters such as initial metal concentration, pH, solid-liquid ratio (R) and temperature on the exchange percentage are studied. The equilibrium isotherms of zinc ions sorption are also evaluated using Langmuir and Freundlich models. Thermodynamic parameters, i.e. enthalpy of adsorption ΔHads∘, entropy change ΔSads∘ and Gibbs free energy ΔGads∘ for the sorption of zinc ions on NaA and NaY zeolites were examined.

  13. Acoustic phonon assisted free-carrier optical absorption in an n-type monolayer MoS{sub 2} and other transition-metal dichalcogenides

    SciTech Connect

    Bhargavi, K. S.; Patil, Sukanya; Kubakaddi, S. S.

    2015-07-28

    The theory of free-carrier absorption (FCA) is given for monolayers of transition-metal dichalcogenides, particularly for molybdenum disulphide (MoS{sub 2}), when carriers are scattered by phonons. Explicit expressions for the absorption coefficient α are obtained and discussed for acoustic phonon scattering via screened deformation potential and piezoelectric coupling taking polarization of the radiation in the plane of the layer. It is found that α monotonously decreases with the increasing photon frequency Ω, increases with the increasing temperature T, and linearly depends on two-dimensional electron concentration n{sub s}. Effect of screening, which is ignored in all the earlier FCA studies, is found to reduce α significantly, attributing to the larger effective mass of the electrons. Results are also obtained in the classical and quantum limit giving the power laws α ∼ Ω{sup −2} and T. Comparison of the results is made with those in bulk semiconductors and semiconductor quantum wells.

  14. Non-LTE line formation of Fe in late-type stars - III. 3D non-LTE analysis of metal-poor stars

    NASA Astrophysics Data System (ADS)

    Amarsi, A. M.; Lind, K.; Asplund, M.; Barklem, P. S.; Collet, R.

    2016-12-01

    As one of the most important elements in astronomy, iron abundance determinations need to be as accurate as possible. We investigate the accuracy of spectroscopic iron abundance analyses using archetypal metal-poor stars. We perform detailed 3D non-LTE radiative transfer calculations based on 3D hydrodynamic STAGGER model atmospheres, and employ a new model atom that includes new quantum-mechanical neutral hydrogen collisional rate coefficients. With the exception of the red giant HD122563, we find that the 3D non-LTE models achieve Fe I/Fe II excitation and ionization balance as well as not having any trends with equivalent width to within modelling uncertainties of 0.05 dex, all without having to invoke any microturbulent broadening; for HD122563 we predict that the current best parallax-based surface gravity is overestimated by 0.5 dex. Using a 3D non-LTE analysis, we infer iron abundances from the 3D model atmospheres that are roughly 0.1 dex higher than corresponding abundances from 1D MARCS model atmospheres; these differences go in the same direction as the non-LTE effects themselves. We make available grids of departure coefficients, equivalent widths and abundance corrections, calculated on 1D MARCS model atmospheres and horizontally and temporally averaged 3D STAGGER model atmospheres.

  15. Rare-earth metal allyl and hydrido complexes supported by an (NNNN)-type macrocyclic ligand: synthesis, structure, and reactivity toward biomass-derived furanics.

    PubMed

    Abinet, Elise; Martin, Daniel; Standfuss, Sabine; Kulinna, Heiko; Spaniol, Thomas P; Okuda, Jun

    2011-12-23

    The preparation and characterization of a series of neutral rare-earth metal complexes [Ln(Me(3)TACD)(η(3)-C(3)H(5))(2)] (Ln=Y, La, Ce, Pr, Nd, Sm) supported by the 1,4,7-trimethyl-1,4,7,10-tetraazacyclododecane anion (Me(3)TACD(-)) are reported. Upon treatment of the neutral allyl complexes [Ln(Me(3)TACD)(η(3)-C(3)H(5))(2)] with Brønsted acids, monocationic allyl complexes [Ln(Me(3)TACD)(η(3)-C(3)H(5))(thf)(2)][B(C(6)X(5))(4)] (Ln=La, Ce, Nd, X=H, F) were isolated and characterized. Hydrogenolysis gave the hydride complexes [Ln(Me(3)TACD)H(2)](n) (Ln=Y, n=3; La, n=4; Sm). X-ray crystallography showed the lanthanum hydride to be tetranuclear. Reactivity studies of [Ln(Me(3)TACD)R(2)](n) (R=η(3)-C(3)H(5), n=0; R=H, n=3,4) towards furan derivatives includes hydrosilylation and deoxygenation under ring-opening conditions.

  16. On the Metal Aversion of LGRBs

    NASA Astrophysics Data System (ADS)

    Graham, John; Fruchter, A.; Levesque, E.; L., K.; J., B.; Levan, A.; Tanvir, N.; Patel, S.; Aldering, G.; Perlmutter, S.; Misra, K.; Huang, K.; Reichart, D.; Nysewander, M.

    2012-01-01

    We discuss recent observations of several high metallicity LGRBs hosts. We then compare the entire population of LGRB hosts with measured metallicities to the hosts of Type II and broad-lined Type Ic SNe as well as the star-forming SDSS galaxy population using several methods of analysis. We argue that even though a few LGRBs do lie in fairly metal rich hosts, the general population of LGRB hosts is surprisingly metal poor, and that metallicity must be an important factor in the formation of LGRBs. Finally we conclude with a discussion of the potential importance and practicality of obtaining spatiality resolved metallicity measurement of LGRB host galaxies.

  17. Retention of heavy metal ions on comb-type hydrogels based on acrylic acid and 4-vinylpyridine, synthesized by gamma radiation

    NASA Astrophysics Data System (ADS)

    González-Gómez, Roberto; Ortega, Alejandra; Lazo, Luz M.; Burillo, Guillermina

    2014-09-01

    Two novel comb-type hydrogels based on pH-sensitive monomers (acrylic acid (AAc) and 4-vinylpyridine (4VP) were synthesized by gamma radiation. The systems were as follows: a) comb-type hydrogels of an AAc network followed by grafting of 4VP ((net-PAAc)-g-4VP) and b) comb-type hydrogels of an AAc network grafted onto polypropylene (PP) followed by grafting of 4VP (net-(PP-g-AAc)-g-4VP). The equilibrium isotherms and kinetics were evaluated for copper and zinc ions in aqueous solutions. The Zn(II) retention obtained was 480 mg g-1 and 1086 mg g-1 for (net-PAAc)-g-4VP and net-(PP-g-AAc)-g-4VP, respectively. At concentrations as low as ppm, retention efficiencies of approximately 90% were achieved for Cu(II) on (net-PAAc)-g-4VP and for Zn(II) on net-(PP-g-AAc)-g-4VP. Desorption of the hydrogels was also studied, and the results indicated that they can be used repeatedly in aqueous solutions. For both systems, the adsorption of Cu(II) and Zn(II) obeyed the Freundlich model, indicating heterogeneous sorption, and the retention process occurred by chemisorption. The sorption process follows a pseudo-second-order model.

  18. Development of casting investment preventing blackening of noble metal alloys Part 2. Application of developed investment for type 4 gold alloy.

    PubMed

    Nakai, Akira; Kakuta, Kiyoshi; Goto, Shin-ichi; Kato, Katuma; Yara, Atushi; Ogura, Hideo

    2003-09-01

    The objective of this study was to evaluate the efficacy of the developed investment for the prevention of blackening of a cast Type 4 gold and to analyze the oxides on its surface in relation to the blackening of the alloy. The experimental investments were prepared using a gypsum-bonded investment in which boron (B) or aluminum (Al) was added as a reducing agent. A Type 4 gold alloy was cast into the mold made of the prepared investment. The effect of the additives was evaluated from the color difference (deltaE*) between the as-cast surface and the polished surface of the cast specimen. B and Al were effective to prevent the blackening of a Type 4 gold alloy and the color of the as-cast surface approached that of the polished surface with increasing B and Al content. The prevention of the blackening of the gold alloy can be achieved by restraining the formation of CuO.

  19. Metal-rich phosphides RE{sub 5}Ir{sub 19}P{sub 12} with Sc{sub 5}Co{sub 19}P{sub 12} type structure

    SciTech Connect

    Pfannenschmidt, Ulrike; Rodewald, Ute Ch.; Hoffmann, Rolf-Dieter; Poettgen, Rainer

    2011-10-15

    The iridium-rich phosphides RE{sub 5}Ir{sub 19}P{sub 12} (RE=Sc, Y, La-Nd, Sm-Lu) with Sc{sub 5}Co{sub 19}P{sub 12} type structure, space group P62-bar m were synthesized by solid state reactions of the elements in tantalum crucibles. Well shaped single crystals were obtained in bismuth fluxes. All phosphides were characterized on the basis of X-ray powder data. The structures of RE{sub 5}Ir{sub 19}P{sub 12} with RE=Sc, La, Ce, Dy, Er, Tm, and Yb were refined from single crystal diffractometer data. The complex structure of these phosphides can be described by an intergrowth of simpler ThCr{sub 2}Si{sub 2} and SrPtSb related slabs. Striking structural motifs of the RE{sub 5}Ir{sub 19}P{sub 12} structures are slightly distorted tricapped trigonal prisms of the metal atoms around the phosphorus atoms. The iridium and phosphorus atoms build up three-dimensional [Ir{sub 19}P{sub 12}] polyanionic networks (230-286 pm Ir-P and 282-296 pm Ir-Ir in La{sub 5}Ir{sub 19}P{sub 12}) which leave cavities of coordination numbers 16 and 15 for the rare earth atoms. - Graphical Abstract: The intergrowth structure La{sub 5}Ir{sub 19}P{sub 12}. Highlights: > Metal flux syntheses of intermetallic compounds. > Synthesis and structure of new phosphides RE{sub 5}Ir{sub 19}P{sub 12}. > Crystal chemistry of metal-rich phosphides. > Description of the RE{sub 5}Ir{sub 19}P{sub 12} structure as an intergrowth variant.

  20. 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.

  1. Making metallic berkelium

    SciTech Connect

    Radchenko, V.M.; Seleznev, A.G.; Ryabinin, M.A.; Lebedeva, L.S.; Droznik, R.R.; Shushakov, V.D.; Stupin, V.A.; Vasil'ev, V.Ya.

    1988-05-01

    Metallic /sup 249/Bk, mass 740 /mu/g, has been made as a film on a tantalum substrate by reducing the oxide with thorium. The evaporated-metal yield was 85%, while the yield on the substrate was 72%. The metal has a double hexagonal close-packed structure of /alpha/-La type, parameters a = (0.3412 /plus minus/ 0.0002) nm, c = (1.1060 /plus minus/ 0.0006) nm, c/2a = 1.621 /plus minus/ 0.002. The metallic radius is 0.1702 /plus minus/ 0.0001 nm, x-ray density 14.86 /plus minus/ 0.03 g/cm/sup 3/. The oxidation under various conditions has been examined.

  2. A new type of strong metal-support interaction and the production of H2 through the transformation of water on Pt/CeO2(111) and Pt/CeO(x)/TiO2(110) catalysts.

    PubMed

    Bruix, Albert; Rodriguez, José A; Ramírez, Pedro J; Senanayake, Sanjaya D; Evans, Jaime; Park, Joon B; Stacchiola, Dario; Liu, Ping; Hrbek, Jan; Illas, Francesc

    2012-05-30

    The electronic properties of Pt nanoparticles deposited on CeO(2)(111) and CeO(x)/TiO(2)(110) model catalysts have been examined using valence photoemission experiments and density functional theory (DFT) calculations. The valence photoemission and DFT results point to a new type of "strong metal-support interaction" that produces large electronic perturbations for small Pt particles in contact with ceria and significantly enhances the ability of the admetal to dissociate the O-H bonds in water. When going from Pt(111) to Pt(8)/CeO(2)(111), the dissociation of water becomes a very exothermic process. The ceria-supported Pt(8) appears as a fluxional system that can change geometry and charge distribution to accommodate adsorbates better. In comparison with other water-gas shift (WGS) catalysts [Cu(111), Pt(111), Cu/CeO(2)(111), and Au/CeO(2)(111)], the Pt/CeO(2)(111) surface has the unique property that the admetal is able to dissociate water in an efficient way. Furthermore, for the codeposition of Pt and CeO(x) nanoparticles on TiO(2)(110), we have found a transfer of O from the ceria to Pt that opens new paths for the WGS process and makes the mixed-metal oxide an extremely active catalyst for the production of hydrogen.

  3. A computational insight into a metal mediated pathway for the ring-opening polymerization (ROP) of lactides by an ionic {(NHC)2Ag}(+)X(-) (X = halide) type N-heterocyclic carbene (NHC) complex.

    PubMed

    Stephen, Raji; Sunoj, Raghavan B; Ghosh, Prasenjit

    2011-10-21

    A metal mediated coordination-insertion pathway for the ring-opening polymerization (ROP) of L-lactide by an ionic {(NHC)(2)Ag}(+)X(-) (X = halide) type silver complex of N-heterocyclic carbene (NHC) has been investigated using the density functional theory (DFT) method. A clear insight into the lactide insertion process could be obtained by modeling two consecutive monomer addition steps with the first one mimicking chain initiation with the second representing a propagation step. In particular, in each of the cycles, the reaction initiates with the formation of a lactide coordinated species, [1+LL] and [2+LL] that transforms into a metal bound cyclic lactide intermediate, I([1+LL]→2) and I([2+LL]→3), which subsequently ring opens to give the lactide inserted products, 2 and 3. The estimated overall activation barrier for the initiation step is 42.0 kcal mol(-1) while the same for the propagation step is 31.5 kcal mol(-1). Studies on higher monomer insertions showed a decrease in the relative product energies as anticipated for an addition polymerization pathway.

  4. Half-metallic and magnetic properties of full-Heusler alloys Zr2CrZ (Z=Ga, In) with Hg2CuTi-type structure: A first-principles study

    NASA Astrophysics Data System (ADS)

    Deng, Zun-Yi; Zhang, Jian-Min

    2016-01-01

    The half-metallic and magnetic properties of Heusler alloys Zr2 CrZ (Z=Ga, In) with Hg2 CuTi -type structure have been investigated by using the first-principles projector augmented wave (PAW) potential within the generalized gradient approximation (GGA). The equilibrium lattice constants are 6.635 and 6.875 Å for Zr2 CrGa and Zr2 CrIn, respectively. Under compression and expansion deformations within lattice constant ranges of 6.515-7.100 and 6.371-7.126 Å for Zr2 CrGa and Zr2 CrIn, respectively, the Zr2 CrZ (Z=Ga, In) maintain a half-metallic nature with a fixed total magnetic moment of -1 μB / f.u ., following the Slater-Pauling rule μt = Zt - 18, but the absolute values of the local magnetic moments on Zr and Cr atoms increase with increasing lattice constant.

  5. Nanostructured surface morphology of ZnO grown on p-type GaN and Si by metal organic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Hung, S. C.; Huang, P. J.; Chan, C. E.; Uen, W. Y.; Ren, F.; Pearton, S. J.; Yang, T. N.; Chiang, C. C.; Lan, S. M.; Chi, G. C.

    2008-12-01

    The surface morphology of ZnO grown on p-GaN templates and p-Si (1 1 1) substrates at various temperatures by metal organic chemical vapor deposition (MOCVD) in a vertical reactor at atmospheric pressure is reported. A low temperature ZnO buffer was deposited initially at 200 °C for 15 min as a nucleation layer. Epitaxial ZnO was grown at 500 °C, 550 °C, 600 °C for 40 min, respectively. Uniformly distributed and well-aligned ZnO nanorods with diameter in the range 80-120 nm and length ˜0.7 μm were observed for deposition on p-GaN template. By contrast, the morphology of ZnO epilayers grown on p-Si (1 1 1) transitioned from 2D to 3D with increasing growth temperature. X-ray diffraction (XRD) spectra showed all the ZnO epilayers had the hexagonal wurtzite structure but different preferred orientation. PL spectra showed only free-exciton emission at 378 nm (˜3.28 eV) with a full width at half maximum of 13 nm without defect-related green emission in the epitaxial ZnO grown at 550 °C and 600 °C. The epitaxial ZnO layers grown on p-GaN and p-Si at the same temperature have similar PL spectra. The PL measurement also exhibits strong exciton-related emission without defect peak, which showed that the ZnO nanostructures grown at 550 °C and 600 °C have good optical properties with excellent crystal quality.

  6. Phosphorus and boron diffusion paths in polycrystalline silicon gate of a trench-type three-dimensional metal-oxide-semiconductor field effect transistor investigated by atom probe tomography

    SciTech Connect

    Han, Bin Takamizawa, Hisashi Shimizu, Yasuo; Inoue, Koji; Nagai, Yasuyoshi; Yano, Fumiko; Kunimune, Yorinobu; Inoue, Masao; Nishida, Akio

    2015-07-13

    The dopant (P and B) diffusion path in n- and p-types polycrystalline-Si gates of trench-type three-dimensional (3D) metal-oxide-semiconductor field-effect transistors (MOSFETs) were investigated using atom probe tomography, based on the annealing time dependence of the dopant distribution at 900 °C. Remarkable differences were observed between P and B diffusion behavior. In the initial stage of diffusion, P atoms diffuse into deeper regions from the implanted region along grain boundaries in the n-type polycrystalline-Si gate. With longer annealing times, segregation of P on the grain boundaries was observed; however, few P atoms were observed within the large grains or on the gate/gate oxide interface distant from grain boundaries. These results indicate that P atoms diffuse along grain boundaries much faster than through the bulk or along the gate/gate oxide interface. On the other hand, in the p-type polycrystalline-Si gate, segregation of B was observed only at the initial stage of diffusion. After further annealing, the B atoms became uniformly distributed, and no clear segregation of B was observed. Therefore, B atoms diffuse not only along the grain boundary but also through the bulk. Furthermore, B atoms diffused deeper than P atoms along the grain boundaries under the same annealing conditions. This information on the diffusion behavior of P and B is essential for optimizing annealing conditions in order to control the P and B distributions in the polycrystalline-Si gates of trench-type 3D MOSFETs.

  7. Fabrication and characterization of inverted organic solar cells using shuttle cock-type metal phthalocyanine and PCBM:P3HT

    SciTech Connect

    Suzuki, Atsushi Furukawa, Ryo Akiyama, Tsuyoshi Oku, Takeo

    2015-02-27

    Inverted organic solar cells using shuttle cock-type phthalocyanine, semiconducting polymer and fullerenes were fabricated and characterized. Photovoltaic and optical properties of the solar cells with inverted structures were investigated by optical absorption, current density-voltage characteristics. The photovoltaic properties of the tandem organic solar cell using titanyl phthalocyanine, vanadyl phthalocyanine, poly(3-hexylthiophene) (P3HT) and [6, 6]-phenyl C{sub 61}-butyric acid methyl ester (PCBM) were improved. Effect of annealing and solvent treatment on surface morphologies of the active layer was investigated. The photovoltaic mechanisms, energy levels and band gap of active layers were discussed for improvement of the photovoltaic performance.

  8. Electron microscopy of X7R and Y5V type barium titanate multilayer ceramic capacitors with noble and base metal electrodes

    NASA Astrophysics Data System (ADS)

    Feng, Qiquan

    Two types of multilayer ceramic capacitors (MLCCs), Y5V with Ni electrodes and X7R with Ag/Pd electrodes, were characterized by transmission electron microscopy (TEM) and showed quite different microstructures which determined their dielectric behaviors. In X7R-type MLCCs, core-shell structures were observed. The flat dielectric constant-temperature curves obtained from these materials can be interpreted in terms of the internal stress states in individual grains. The stress states were observed using weak beam dark field (WBDF) microscopy. The strain contours observed were formed by distorted crystal planes and were dependent on the stress state of the crystal instead of crystal symmetry. The stress distribution in individual grains was determined by both the thickness ratio of shell and core and the geometrical relationship of the core and the shell. (111) lamella twins and dislocation loops in the paraelectric phases of BaTiO3 doped with Bi2O3 were analyzed by TEM under two-beam conditions. Y5V-type MLCCs based on re-oxidized Ba(Ti 0.88,Zr0.12)O3 (BTZ) materials exhibited frequency relaxation effects. Multi-domain structures coexisting in one grain were observed at dynamical diffraction conditions. Uneven distribution of internal stress and coexistence of multi-phases and multi-domains in individual grains were considered to be responsible for the frequency relaxor behavior observed in these materials. The compatibility of electrodes and dielectrics in cofired MLCCs with both Ni and Ag/Pd electrodes was characterized by TEM using tripod polished samples. NiO lamellae and P-rich intermediate layers were found in highly accelerated life tested (HALT) MLCCs with Ni electrodes. It is believed that Mn ions were reduced by the Ni electrodes, as P-rich and Mn-rich segregated layers were observed in the virginal non-life tested MLCCs. No silver diffusion was found in either the BaTiO3 based perovskite lattices or the flux phases in air-fired X7R type MLCCs.

  9. Tinv Scaling and Gate Leakage Reduction for n-Type Metal Oxide Semiconductor Field Effect Transistor with HfSix/HfO2 Gate Stack by Interfacial Layer Formation Using Ozone-Water-Last Treatment

    NASA Astrophysics Data System (ADS)

    Oshiyama, Itaru; Tai, Kaori; Hirano, Tomoyuki; Yamaguchi, Shinpei; Tanaka, Kazuaki; Hagimoto, Yoshiya; Uemura, Takayuki; Ando, Takashi; Watanabe, Koji; Yamamoto, Ryo; Kanda, Saori; Wang, Junli; Tateshita, Yasushi; Wakabayashi, Hitoshi; Tagawa, Yukio; Tsukamoto, Masanori; Iwamoto, Hayato; Saito, Masaki; Oshima, Masaharu; Toyoda, Satoshi; Nagashima, Naoki; Kadomura, Shingo

    2008-04-01

    In this paper, we demonstrate a wet treatment for the HfSix/HfO2 gate stack of n-type metal oxide semiconductor field effect transistor (nMOSFET) fabricated by a gate-last process in order to scale down the electrical thickness at inversion state Tinv value and reduce the gate leakage Jg. As a result, we succeeded in scaling down Tinv to 1.41 nm without mobility or Jg degradation by ozone-water-last treatment. We found that a high-density interfacial layer (IFL) is formed owing to the ozone-water-last treatment, and Hf diffusion to the IFL is suppressed, which was analyzed by high-resolution angle-resolved spectroscopy.

  10. Inkjet-printed flexible organic thin-film thermoelectric devices based on p- and n-type poly(metal 1,1,2,2-ethenetetrathiolate)s/polymer composites through ball-milling

    PubMed Central

    Jiao, Fei; Di, Chong-an; Sun, Yimeng; Sheng, Peng; Xu, Wei; Zhu, Daoben

    2014-01-01

    In this article, we put forward a simple method for the synthesis of thermoelectric (TE) composite materials. Both n- and p-type composites were obtained by ball-milling the insoluble and infusible metal coordination polymers with other polymer solutions. The particle size, film morphology and composition were characterized by dynamic light scattering, scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. The TE properties of the drop-cast composite film were measured at different temperatures. An inkjet-printed flexible device was fabricated and the output voltage and short-circuit current at various hot-side temperatures (Thot) and temperature gradients (ΔT) were tested. The composite material not only highly maintained the TE properties of the pristine material but also greatly improved its processability. This method can be extended to other insoluble and infusible TE materials for solution-processed flexible TE devices. PMID:24615147

  11. Trimethylsilyl-Substituted Hydroxycyclopentadienyl Ruthenium Hydrides as Benchmarks to Probe Ligand and Metal Effects on the Reactivity of Shvo Type Complexes.

    PubMed

    Casey, Charles P; Guan, Hairong

    2012-01-01

    The bis(trimethylsilyl)-substituted hydroxycyclopentadienyl ruthenium hydride [2,5-(SiMe(3))(2)-3,4-(CH(2)OCH(2))(η(5)-C(4)COH)]Ru(CO)(2)H (10) is an efficient catalyst for hydrogenation of aldehydes and ketones. Because 10 transfers hydrogen rapidly to aldehydes and ketones and because it does not form an inactive bridging hydride during reaction, hydrogenation of aldehydes and ketones can be performed at room temperature under relatively low hydrogen pressure (3 atm); this is a significant improvement compared with previously developed Shvo type catalysts. Kinetic and (2)H NMR spectroscopic studies of the stoichiometric reduction of aldehydes and ketones by 10 established a two-step process for the hydrogen transfer: (1) rapid and reversible hydrogen bond formation between OH of 10 and the oxygen of the aldehyde or ketone, (2) followed by slow transfer of both proton and hydride from 10 to the aldehyde or ketone. The stoichiometric and catalytic activities of complex 10 are compared to those of other Shvo type ruthenium hydrides and related iron hydrides.

  12. Thermoelectric and mechanical properties on misch metal filled p-type skutterudites Mm{sub 0.9}Fe{sub 4−x}Co{sub x}Sb{sub 12}

    SciTech Connect

    Dahal, Tulashi; Jie, Qing; Dahal, Keshab; Lan, Yucheng; Ren, Zhifeng E-mail: zren@uh.edu; Gahlawat, Sonika; White, Kenneth E-mail: zren@uh.edu

    2015-02-07

    Most of the recent work focused on improving the dimensionless figure-of-merit, ZT, of p-type skutterudites uses one or two fillers to tune the electrical and thermal properties. Considering the fact that the different fillers with varying atomic mass and ionic radii can vibrate with different amplitudes to scatter phonons of different mean free paths, we synthesized misch metal filled p-type skutterudites Mm{sub 0.9}Fe{sub 4−x}Co{sub x}Sb{sub 12} (where Mm is La{sub 0.25}Ce{sub 0.5}Pr{sub 0.05}Nd{sub 0.15}Fe{sub 0.03}, called misch metal). The samples were synthesized by hot pressing nano-powder made by ball milling the annealed ingot of Mm{sub 0.9}Fe{sub 4−x}Co{sub x}Sb{sub 12} with varying concentration of cobalt, x. By tuning the Fe/Co ratio, we achieved a thermal conductivity of ∼2 W m{sup −1} K{sup −1} at room temperature and ∼2.3 W m{sup −1} K{sup −1} at about 530 °C and a power factor of ∼30 μW cm{sup −1} K{sup −2} at about 425 °C in Mm{sub 0.9}Fe{sub 3.1}Co{sub 0.9}Sb{sub 12}, leading to a peak ZT ∼1.1 at about 425 °C. The nano-indentation experiment reveals that hardness and elastic modulus of the material is about 4.2 GPa and 116 GPa, respectively.

  13. Failure Engineered Heavy Metal Penetrators

    DTIC Science & Technology

    1992-12-01

    ARMY RESEARCH LABORATORY Failure Engineered Heavy Metal Penetrators, Phase I, SBIR ARL-CR-5· R. Cavalieri, W. Tiarn, and D. Nicholson prepared...REPORT DATE S. REPORT TYPE AND DATES COVERED December 1992 Final Report-1/1/92 - 7/31/92 4. TITLE AND SUBTITLE FAILURE ENGINEERED HEAVY METAL PENETRATORS

  14. Eu(III) luminescence and tryptophan fluorescence spectroscopy as a tool for understanding interactions between hen egg white lysozyme and metal-substituted Keggin type polyoxometalates.

    PubMed

    Goovaerts, Vincent; Stroobants, Karen; Absillis, Gregory; Parac-Vogt, Tatjana N

    2015-09-01

    The interaction between the lacunary Keggin K7PW11O39, the Eu(III)-substituted Keggin K4EuPW11O39 (Eu-Keggin) and the Ce(IV)-substituted Keggin [Me2NH2]10[Ce(PW11O39)2] (Ce-Keggin) polyoxometalates (POMs), and the proteins hen egg white lysozyme (HEWL) and the structurally homologous α-lactalbumin (α-LA) was studied by steady state and time-resolved Eu(III) luminescence and tryptophan (Trp) fluorescence spectroscopy. The excitation spectrum of Eu-Keggin at lower concentrations ([Eu-Keggin]<100 μM) is dominated by a ligand-to-metal charge transfer band (291 nm). For higher concentrations ([Eu-Keggin]>250 μM) the (5)L6←(7)F0 transition becomes the most intense peak. In the absence of protein, the number of coordinated water molecules to the Eu(III) centre of Eu-Keggin is 4, indicating a 1:1 Eu(III):POM species. In the presence of phosphate buffer this number linearly decreases from 4 to 2 upon increasing phosphate buffer concentration. Upon addition of HEWL, there are no coordinated water molecules, suggesting interaction between Eu-Keggin and the protein surface. In addition, this interaction results in a more than threefold increase of the hypersensitive (5)D0→(7)F2 transition for the Eu-Keggin/HEWL mixture. The calculated association constant amounted to 2.2×10(2) M(-1) for the Eu-Keggin/HEWL complex. Tryptophan fluorescence quenching studies were performed and the quenching constants were calculated to be 9.1×10(4) M(-1), 4×10(4) M(-1) and 4.1×10(5) M(-1) for the lacunary Keggin/HEWL, the Eu-Keggin/HEWL and the Ce-Keggin/HEWL complexes, respectively. The number of bound POM molecules to HEWL was 1.04 for the lacunary Keggin POM, and 1.0 for Eu-Keggin, indicating the formation of a 1:1 POM/HEWL complex. The value of 1.38 for Ce-Keggin might indicate a transition from 1:1 to 1:2 interaction.

  15. Thin films of mixed metal compounds

    DOEpatents

    Mickelsen, R.A.; Chen, W.S.

    1985-06-11

    Disclosed is a thin film heterojunction solar cell, said heterojunction comprising a p-type I-III-IV[sub 2] chalcopyrite substrate and an overlying layer of an n-type ternary mixed metal compound wherein said ternary mixed metal compound is applied to said substrate by introducing the vapor of a first metal compound to a vessel containing said substrate from a first vapor source while simultaneously introducing a vapor of a second metal compound from a second vapor source of said vessel, said first and second metals comprising the metal components of said mixed metal compound; independently controlling the vaporization rate of said first and second vapor sources; reducing the mean free path between vapor particles in said vessel, said gas being present in an amount sufficient to induce homogeneity of said vapor mixture; and depositing said mixed metal compound on said substrate in the form of a uniform composition polycrystalline mixed metal compound. 5 figs.

  16. Metal detector system

    NASA Technical Reports Server (NTRS)

    Lee, R. D.

    1970-01-01

    Signal voltage resulting from the disturbance of an electromagnetic field within the volume of a sensitive area is compared with a reference ac voltage for polarity information, which identifies the material. System output amplitude and polarity indicate approximate size and type of metal, respectively.

  17. Metal-Ceramic Seals.

    DTIC Science & Technology

    1979-10-01

    reliability and very low thermal barriers and rf losses when compared to the classical Mo-Mn metallization. Three types of rf windows were fabricated...found to be excellent if cusil is used as brazing alloy, and extremely low thermal barriers have been measured. The use of Au/Cu brazing alloys

  18. Synthesis, characterization and evaluation of the suppression of insulin resistance in Type-II diabetes mellitus animals by treatment with metal complex

    PubMed Central

    Phanse, Mohini A.; Patil, Manohar J.; Abbulu, Konde

    2015-01-01

    The present study is characterized toward thespesone isolation from Thespesia populnea (Malvaceae). Subsequently it was modified and characterized to study its effect on diabetes related symptoms. The complex is administered to diabetes induced mice with the doses of 5, 10 and 20 mg/kg, p.o. and the effect of complex on the level of body weight, lipid profile and blood glucose was studied after 22 days. The results have indicated that diabetic mice show a significant (p < 0.01) decrease in the level of serum triglyceride, plasma glucose and increase in body weight. Hence the present investigation reveals that newly synthesized complex is useful in the management of Type-II diabetes mellitus because of its ability to reduce insulin resistance. PMID:27081369

  19. Synthesis and structural characterization of Lindqvist type mixed-metal cluster anion [V2W4O19]4- in discrete and coordination polymer compounds

    NASA Astrophysics Data System (ADS)

    Yerra, Sridevi; Amanchi, Srinivasa Rao; Das, Samar K.

    2014-03-01

    Two vanadium substituted Lindqvist type tungsten heteropolyanion containing compounds with molecular formulae [HMTAH]2[H2V2W4O19]·4H2O (1) and [Na2(H2O)4]n[H2V2W4O19]n·2nHMTA·2nH2O (2) have been synthesized, where HMTA is hexamethylenetetramine. Compound 1 is a discrete compound, whereas, compound 2 is a coordination polymer. Compounds 1-2 are characterized by routine elemental analyses, FT-IR spectroscopy, electronic absorption spectral analyses, thermogravimetric studies and single crystal X-ray crystallography. The presence of vanadium in the cluster anion is confirmed by 51V NMR spectroscopy, EDS and ICP analyses. The crystal structures of compounds 1 and 2 are refined in orthorhombic space group Immm and monoclinic space group C2/c respectively.

  20. 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.

  1. Metal Detectors.

    ERIC Educational Resources Information Center

    Harrington-Lueker, Donna

    1992-01-01

    Schools that count on metal detectors to stem the flow of weapons into the schools create a false sense of security. Recommendations include investing in personnel rather than hardware, cultivating the confidence of law-abiding students, and enforcing discipline. Metal detectors can be quite effective at afterschool events. (MLF)

  2. Promoting oxygen vacancy formation and p-type conductivity in SrTiO3via alkali metal doping: a first principles study.

    PubMed

    Triggiani, Leonardo; Muñoz-García, Ana B; Agostiano, Angela; Pavone, Michele

    2016-10-19

    Strontium titanate (SrTiO3, STO) is a prototypical perovskite oxide, widely exploited in many technological applications, from catalysis to energy conversion devices. In the context of solid-oxide fuel cells, STO has been recently applied as an epitaxial substrate for nano-sized layers of mixed ion-electron conductive catalysts with enhanced electrochemical performances. To extend the applications of such heterogeneous nano-cathodes in real devices, also the STO support should be active for both electron transport and oxide diffusion. To this end, we explored using first-principles calculations the strategy of doping of STO at the Sr site with sodium and potassium. These two ions fit in the perovskite structure and induce holes in the STO valence band, so as to obtain the desired p-type electronic conduction. At the same time, the doping with alkali ions also promotes the formation of oxygen vacancies in STO, a prerequisite for effective oxide diffusion. Analysis of electron density rearrangements upon defect formation allows relating the favorable vacancy formation energies to an improved electronic delocalization over the oxide sub-lattice, as observed in closely related materials (e.g. Sr2Fe1.5Mo0.5O6). Overall, our results suggest the alkali-doped STO as a new potential substrate material in nanoscale heterogeneous electrodes for solid oxide electrochemical cells.

  3. Mechanistic Investigation into Olefin Epoxidation with H2O2 Catalyzed by Aqua‐Coordinated Sandwich‐Type Polyoxometalates: Role of the Noble Metal and Active Oxygen Position

    PubMed Central

    Ci, Chenggang; Liu, Hongsheng

    2016-01-01

    Abstract Aqua‐coordinated sandwich‐type polyoxometalates (POMs), {[WZnTM2(H2O)2](ZnW9O34)2}n− (TM=RhIII, PdII, and PtII), catalyze olefin epoxidation with hydrogen peroxide and have been well established, and they present an advance toward the utilization of olefins. To elucidate the epoxidation mechanism, we systematically performed density functional calculations. The reaction proceeds through a two‐step mechanism: activation of H2O2 and oxygen transfer. The aqua‐coordinated complexes show two distinct H2O2 activation pathways: “two‐step” and “concerted”. The concerted processes are more facile and proceed with similar and rate‐determining energy barriers at the Rh‐, Pd‐, and Pt‐containing transition states, which agrees well with the experimental results. Next, the resulting TM−OH−(μ‐OOH) intermediate transfers an O atom to olefin to form an epoxide. The higher reactivity of the Rh‐containing POM is attributed to more interactions between the Rh and hydroperoxo unit. We also calculated all active oxygen positions to locate the most favorable pathway. The higher reactivity of the two‐metal‐bonded oxygen position is predominantly ascribed to its lower stereoscopic hindrance. Furthermore, the presence of one and two explicit water solvent molecules significantly reduces the energy barriers, making these sandwich POMs very efficient for the olefin epoxidation with H2O2. PMID:27777840

  4. The tribology of metal-on-metal total hip replacements.

    PubMed

    Scholes, S C; Unsworth, A

    2006-02-01

    Total hip surgery is an effective way of alleviating the pain and discomfort caused by diseased or damaged joints. However, in the majority of cases, these joints have a finite life. The main reason for failure is osteolysis (bone resorption). It is well documented that an important cause of osteolysis, and therefore the subsequent loosening and failure of conventional metal- or ceramic-on-ultra-high molecular weight polyethylene joints, is the body's immunological response to the polyethylene wear particles. To avoid this, interest has been renewed in metal-on-metal joints. The intention of this paper is to review the studies that have taken place within different laboratories to determine the tribological performance of new-generation metal-on-metal total hip replacements. These types of joint offer a potential solution to enhance the longevity of prosthetic hip systems; however, problems may arise owing to the effects of metal ion release, which are, as yet, not fully understood.

  5. The complex metal-rich boride Ti{sub 1+x}Rh{sub 2-x+y}Ir{sub 3-y}B{sub 3} (x=0.68, y=1.06) with a new structure type containing B{sub 4} zigzag fragments: Synthesis, crystal chemistry and theoretical calculations

    SciTech Connect

    Goerens, Christian; Fokwa, Boniface P.T.

    2012-08-15

    Polycrystalline samples and single crystals of the new complex boride Ti{sub 1+x}Rh{sub 2-x+y}Ir{sub 3-y}B{sub 3} (x=0.68; y=1.06) were synthesized by arc-melting the elements in a water-cooled copper crucible under an argon atmosphere and characterized by X-Ray diffraction as well as EDX measurements. The crystal structure was refined on the basis of single crystal data. The new phase, which represents a new structure type containing trans zigzag B{sub 4} fragments as well as isolated boron atoms crystallizes in the orthorhombic space group Pbam (Nr. 55) with the lattice parameters a=8.620(1) A, b=14.995(2) A and c=3.234(1) A. First-principles density functional theory calculations using the Vienna ab-initio simulation package (VASP) were performed on an appropriate structural model (using a supercell approach) and the experimental crystallographic data could be reproduced accurately. Based on this model, the density of states and crystal orbital Hamilton population (for bonding analysis) were calculated, using the linear muffin-tin orbital atomic sphere approximation (LMTO-ASA) method. According to these calculations, this metal-rich compound should be metallic, as expected. Furthermore, very strong boron-boron interactions are observed in the trans zigzag B{sub 4} fragment, which induce a clear differentiation of two types of metal-boron contacts with different strength. The observed three-dimensional metal-metal interaction is in good agreement with the predicted metallic behavior. - graphical abstract: The structure of Ti{sub 1.68(2)}Rh{sub 2.38(6)}Ir{sub 1.94(4)} B{sub 3}, a new structure type containing planar trans zigzag B{sub 4} units, is another example which illustrates the tendency of metal-rich borides to form B-B bonds with increasing boron content. Beside the B{sub 4} fragment it exhibits one-dimensional chains of titanium atoms and hold one-dimensional strings of face-sharing empty tetrahedral and square pyramidal clusters (see figure). Highlights

  6. Hydrothermal Synthesis and Characterization of Novel Brackebuschite-Type Transition Metal Vanadates: Ba2M(VO4)2(OH), M = V(3+), Mn(3+), and Fe(3+), with Interesting Jahn-Teller and Spin-Liquid Behavior.

    PubMed

    Sanjeewa, Liurukara D; McGuire, Michael A; Garlea, Vasile O; Hu, Longyu; Chumanov, George; McMillen, Colin D; Kolis, Joseph W

    2015-07-20

    A new series of transition metal vanadates, namely, Ba2M(VO4)2(OH) (M = V(3+), Mn(3+), and Fe(3+)), was synthesized as large single crystals hydrothermally in 5 M NaOH solution at 580 °C and 1 kbar. This new series of compounds is structurally reminiscent of the brackebuschite mineral type. The structure of Ba2V(VO4)2(OH) is monoclinic in space group P21/m, a = 7.8783(2) Å, b = 6.1369(1) Å, c = 9.1836(2) Å, β = 113.07(3)°, V = 408.51(2) Å(3). The other structures are similar and consist of one-dimensional trans edge-shared distorted octahedral chains running along the b-axis. The vanadate groups bridge across edges of their tetrahedra. Structural analysis of the Ba2Mn(VO4)2(OH) analogue yielded a new understanding of the Jahn-Teller effect in this structure type. Raman and infrared spectra were investigated to observe the fundamental vanadate and hydroxide vibrational modes. Single-crystal temperature-dependent magnetic studies on Ba2V(VO4)2(OH) reveal a broad feature over a wide temperature range with maximum at ∼100 K indicating that an energy gap could exist between the antiferromagnetic singlet ground state and excited triplet states, making it potentially of interest for quantum magnetism studies.

  7. Hydrothermal Synthesis and Characterization of Novel Brackebuschite-Type Transition Metal Vanadates: Ba 2 M(VO 4 ) 2 (OH), M = V 3+ , Mn 3+ , and Fe 3+ , with Interesting Jahn–Teller and Spin-Liquid Behavior

    DOE PAGES

    Sanjeewa, Liurukara D.; McGuire, Michael A.; Garlea, Vasile O.; ...

    2015-07-08

    In a new series of transition metal vanadates, namely, Ba2M(VO4)2(OH) (M = V3+, Mn3+, and Fe3+), was synthesized as large single crystals hydrothermally in 5 M NaOH solution at 580 °C and 1 kbar. This new series of compounds is structurally reminiscent of the brackebuschite mineral type. The structure of Ba2V(VO4)2(OH) is monoclinic in space group P21/m, a = 7.8783(2) Å, b = 6.1369(1) Å, c = 9.1836(2) Å, β = 113.07(3)°, V = 408.51(2) Å3. Moreover, the other structures are similar and consist of one-dimensional trans edge-shared distorted octahedral chains running along the b-axis. The vanadate groups bridge acrossmore » edges of their tetrahedra. Structural analysis of the Ba2Mn(VO4)2(OH) analogue yielded a new understanding of the Jahn–Teller effect in this structure type. Raman and infrared spectra were investigated to observe the fundamental vanadate and hydroxide vibrational modes. Finally, single-crystal temperature-dependent magnetic studies on Ba2V(VO4)2(OH) reveal a broad feature over a wide temperature range with maximum at ~100 K indicating that an energy gap could exist between the antiferromagnetic singlet ground state and excited triplet states, making it potentially of interest for quantum magnetism studies.« less

  8. Self-consistent simulations of a von Kármán type dynamo in a spherical domain with metallic walls.

    PubMed

    Guervilly, Céline; Brummell, Nicholas H

    2012-10-01

    We have performed numerical simulations of boundary-driven dynamos using a three-dimensional nonlinear magnetohydrodynamical model in a spherical shell geometry. A conducting fluid of magnetic Prandtl number Pm=0.01 is driven into motion by the counter-rotation of the two hemispheric walls. The resulting flow is of von Kármán type, consisting of a layer of zonal velocity close to the outer wall and a secondary meridional circulation. Above a certain forcing threshold, the mean flow is unstable to non-axisymmetric motions within an equatorial belt. For fixed forcing above this threshold, we have studied the dynamo properties of this flow. The presence of a conducting outer wall is essential to the existence of a dynamo at these parameters. We have therefore studied the effect of changing the material parameters of the wall (magnetic permeability, electrical conductivity, and thickness) on the dynamo. In common with previous studies, we find that dynamos are obtained only when either the conductivity or the permeability is sufficiently large. However, we find that the effect of these two parameters on the dynamo process are different and can even compete to the detriment of the dynamo. Our self-consistent approach allow us to analyze in detail the dynamo feedback loop. The dynamos we obtain are typically dominated by an axisymmetric toroidal magnetic field and an axial dipole component. We show that the ability of the outer shear layer to produce a strong toroidal field depends critically on the presence of a conducting outer wall, which shields the fluid from the vacuum outside. The generation of the axisymmetric poloidal field, on the other hand, occurs in the equatorial belt and does not depend on the wall properties.

  9. Metal-matrix composites: Status and prospects

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Applications of metal matrix composites for air frames and jet engine components are discussed. The current state of the art in primary and secondary fabrication is presented. The present and projected costs were analyzed to determine the cost effectiveness of metal matrix composites. The various types of metal matrix composites and their characteristics are described.

  10. Catalysis Without Precious Metals

    SciTech Connect

    Bullock, R. Morris

    2010-11-01

    Written for chemists in industry and academia, this ready reference and handbook summarizes recent progress in the development of new catalysts that do not require precious metals. The research thus presented points the way to how new catalysts may ultimately supplant the use of precious metals in some types of reactions, while highlighting the remaining challenges. This material is based upon work supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences.

  11. Metallic Adhesion and Bonding

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Smith, J. R.; Rose, J. H.

    1984-01-01

    Although metallic adhesion has played a central part in much tribological speculation, few quantitative theoretical calculations are available. This is in part because of the difficulties involved in such calculations and in part because the theoretical physics community is not particularly involved with tribology. The calculations currently involved in metallic adhesion are summarized and shown that these can be generalized into a scaled universal relationship. Relationships exist to other types of covalent bonding, such as cohesive, chemisorptive, and molecular bonding. A simple relationship between surface energy and cohesive energy is offered.

  12. CheckMyMetal: a macromolecular metal-binding validation tool

    PubMed Central

    Porebski, Przemyslaw J.

    2017-01-01

    Metals are essential in many biological processes, and metal ions are modeled in roughly 40% of the macromolecular structures in the Protein Data Bank (PDB). However, a significant fraction of these structures contain poorly modeled metal-binding sites. CheckMyMetal (CMM) is an easy-to-use metal-binding site validation server for macromolecules that is freely available at http://csgid.org/csgid/metal_sites. The CMM server can detect incorrect metal assignments as well as geometrical and other irregularities in the metal-binding sites. Guidelines for metal-site modeling and validation in macromolecules are illustrated by several practical examples grouped by the type of metal. These examples show CMM users (and crystallographers in general) problems they may encounter during the modeling of a specific metal ion. PMID:28291757

  13. CheckMyMetal: a macromolecular metal-binding validation tool.

    PubMed

    Zheng, Heping; Cooper, David R; Porebski, Przemyslaw J; Shabalin, Ivan G; Handing, Katarzyna B; Minor, Wladek

    2017-03-01

    Metals are essential in many biological processes, and metal ions are modeled in roughly 40% of the macromolecular structures in the Protein Data Bank (PDB). However, a significant fraction of these structures contain poorly modeled metal-binding sites. CheckMyMetal (CMM) is an easy-to-use metal-binding site validation server for macromolecules that is freely available at http://csgid.org/csgid/metal_sites. The CMM server can detect incorrect metal assignments as well as geometrical and other irregularities in the metal-binding sites. Guidelines for metal-site modeling and validation in macromolecules are illustrated by several practical examples grouped by the type of metal. These examples show CMM users (and crystallographers in general) problems they may encounter during the modeling of a specific metal ion.

  14. 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.

  15. Transition metals

    PubMed Central

    Rodrigo-Moreno, Ana; Poschenrieder, Charlotte; Shabala, Sergey

    2013-01-01

    Transition metals such as Iron (Fe) and Copper (Cu) are essential for plant cell development. At the same time, due their capability to generate hydroxyl radicals they can be potentially toxic to plant metabolism. Recent works on hydroxyl-radical activation of ion transporters suggest that hydroxyl radicals generated by transition metals could play an important role in plant growth and adaptation to imbalanced environments. In this mini-review, the relation between transition metals uptake and utilization and oxidative stress-activated ion transport in plant cells is analyzed, and a new model depicting both apoplastic and cytosolic mode of ROS signaling to plasma membrane transporters is suggested. PMID:23333964

  16. The Physical Properties and Effective Temperature Scale of O-Type Stars as a Function of Metallicity. II. Analysis of 20 More Magellanic Cloud Stars and Results from the Complete Sample

    NASA Astrophysics Data System (ADS)

    Massey, Philip; Puls, Joachim; Pauldrach, A. W. A.; Bresolin, Fabio; Kudritzki, Rolf P.; Simon, Theodore

    2005-07-01

    In order to determine the physical properties of the hottest and most luminous stars and understand how these properties change as a function of metallicity, we have analyzed HST/UV and high-S/N optical spectra of an additional 20 Magellanic Cloud stars, doubling the sample presented in the first paper in this series. Our analysis uses non-LTE line-blanketed models that include spherical extension and the hydrodynamics of the stellar wind. In addition, our data set includes FUSE observations of O VI and HST near-UV He I and He II lines to test for consistency of our derived stellar properties for a few stars. The results from the complete sample are as follows: (1) We present an effective temperature scale for O stars as a function of metallicity. We find that the SMC O3-7 dwarfs are 4000 K hotter than Galactic stars of the same spectral type. The difference is in the sense expected due to the decreased significance of line blanketing and wind blanketing at the lower metallicities that characterize the SMC. The temperature difference between the SMC and Milky Way O dwarfs decreases with decreasing temperature, becoming negligible by spectral type B0, in accord with the decreased effects of stellar winds at lower temperatures and luminosities. The temperatures of the LMC stars appear to be intermediate between that of the Milky Way and SMC, as expected based on their metallicities. Supergiants show a similar effect but are roughly 3000-4000 K cooler than dwarfs for early O stars, also with a negligible difference by B0. The giants appear to have the same effective temperature scale as dwarfs, consistent with there being little difference in the surface gravities. When we compare our scale to other recent modeling efforts, we find good agreement with some CMFGEN results, while other CMFGEN studies are discordant, although there are few individual stars in common. WM-BASIC modeling by others has resulted in significantly cooler effective temperatures than what we find

  17. Possibility of combining ferroelectricity and Rashba-like spin splitting in monolayers of the 1 T -type transition-metal dichalcogenides M X2 (M = Mo ,W ;X =S ,Se ,Te )

    NASA Astrophysics Data System (ADS)

    Bruyer, Emilie; Di Sante, Domenico; Barone, Paolo; Stroppa, Alessandro; Whangbo, Myung-Hwan; Picozzi, Silvia

    2016-11-01

    First-principles calculations were carried out to explore the possible coupling between spin-polarized electronic states and ferroelectric polarization in monolayers of transition-metal dichalcogenides M X2 (M =Mo ,W ;X =S ,Se ,Te ) with distorted octahedrally coordinated 1 T structures. For d2 metal ions, two competing metal clustering effects can take place, where metal ions are arranged in trimers or zigzag chains. Among these, the former structural distortion comes along with an improper ferroelectric phase which persists in the monolayer limit. Switchable Rashba-like spin-polarization features are predicted in the trimerized polytype, which can be permanently tuned by acting on its ferroelectric properties. The polar trimerized structure is found to be stable for 1 T -MoS2 only, while the nonpolar polytype with zigzag metal clustering is predicted to stabilize for other transition-metal dichalcogenides with d2 metal ions.

  18. 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.

  19. Calcium substitution in rare-earth metal germanides with the hexagonal Mn{sub 5}Si{sub 3} structure type. structural characterization of the extended series RE{sub 5–x}Ca{sub x}Ge{sub 3} (RE=Rare-earth metal)

    SciTech Connect

    Suen, Nian-Tzu; Broda, Matthew; Bobev, Svilen

    2014-09-15

    Reported are the synthesis and the structural characterization of an extended family of rare-earth metal–germanides with a general formula RE{sub 5–x}Ca{sub x}Ge{sub 3} (RE=Y, Ce–Nd, Sm, Gd–Tm and Lu; x<2). All twelve phases are isotypic, crystallizing with the Mn{sub 5}Si{sub 3} structure type (Pearson index hP16, hexagonal space group P6{sub 3}/mcm); they are the Ca-substituted variants of the corresponding RE{sub 5}Ge{sub 3} binaries. Across the series, despite some small variations in the Ca-uptake, the unit cell volumes decrease monotonically, following the lanthanide contraction. Temperature dependent DC magnetization measurements reveal paramagnetic behavior in the high temperature range, and the obtained effective moments are consistent with free-ion RE{sup 3+} ground state, as expected from prior studies of the binary RE{sub 5}Ge{sub 3} phases. The onset of magnetic ordering is observed in the low temperature range, and complex magnetic interactions (ferromagnetic/ferrimagnetic) can be inferred, different from the binary phases RE{sub 5}Ge{sub 3}, which are known as antiferromagnetic. In order to understand the role of Ca in the bonding, the electronic structures of the La{sub 5}Ge{sub 3} and the hypothetical compounds La{sub 2}Ca{sub 3}Ge{sub 3} and La{sub 3}Ca{sub 2}Ge{sub 3} with ordered metal atoms are compared and discussed. - Graphical abstract: The family of rare-earth metal–calcium–germanides with the general formula RE{sub 5–x}Ca{sub x}Ge{sub 3} (RE=Y, Ce–Nd, Sm, Gd–Tm and Lu) crystallize in the hexagonal space group P6{sub 3}/mcm (No. 193, Pearson symbol hP16) with a structure that is a variant of the Mn{sub 5}Si{sub 3} structure type. - Highlights: • The newly synthesized RE{sub 5–x}Ca{sub x}Ge{sub 3} (RE=Y, Ce–Nd, Sm, Gd–Tm and Lu) constitute an extended family. • The structure is a substitution variant of the hexagonal Mn{sub 5}Si{sub 3} structure type. • Ca-uptake is the highest in the early members, and

  20. 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.

  1. Metals--Endangered Resources.

    ERIC Educational Resources Information Center

    Crowder, William W.

    1979-01-01

    Suggests activities for elementary teachers to use in teaching about metals and their use. Specific areas addressed include: history of metals, metal use, consumption statistics, beauty of metals, sources of metals, conservation, and other projects. (JMB)

  2. Blood typing

    MedlinePlus

    ... ABO blood typing; Blood group; Anemia - immune hemolytic blood type; ABO blood type; A blood type; AB blood type; O blood type ... The 2 steps above can accurately determine your blood type. Rh typing uses a method similar to ABO ...

  3. Measurement of n-type Dry Thermally Oxidized 6H-SiC Metal-oxide Semiconductor Diodes by Quasistatic and High-Frequency Capacitance Versus Voltage and Capacitance Transient Techniques

    NASA Technical Reports Server (NTRS)

    Neudeck, P.; Kang, S.; Petit, J.; Tabib-Azar, M.

    1994-01-01

    Dry-oxidized n-type 6H-SiC metal-oxide-semiconductor capacitors are investigated using quasistatic capacitance versus voltage (C-V), high-frequency C-V, and pulsed high-frequency capacitance transient (C-t) analysis over the temperature range from 297 to 573 K. The quasistatic C - V characteristics presented are the first reported for 6H-SiC MOS capacitors, and exhibit startling nonidealities due to nonequilibrium conditions that arise from the fact that the recombination/generation process in 6H-SiC is extraordinarily slow even at the highest measurement temperature employed. The high-frequency dark C-V characteristics all showed deep depletion with no observable hysteresis. The recovery of the high-frequency capacitance from deep depletion to inversion was used to characterize the minority-carrier generation process as a function of temperature. Zerbst analysis conducted on the resulting C-t transients, which were longer than 1000 s at 573 K, showed a generation lifetime thermal activation energy of 0.49 eV.

  4. O3-type layered transition metal oxide Na(NiCoFeTi)1/4O2 as a high rate and long cycle life cathode material for sodium ion batteries

    SciTech Connect

    Yue, Ji -Li; Yang, Xiao -Qing; Zhou, Yong -Ning; Yu, Xiqian; Bak, Seong -Min; Fu, Zheng -Wen

    2015-10-09

    High rate capability and long cycle life are challenging goals for the development of room temperature sodium-ion batteries. Here we report a new single phase quaternary O3-type layer-structured transition metal oxide Na(NiCoFeTi)1/4O2 synthesized by a simple solid-state reaction as a new cathode material for sodium-ion batteries. It can deliver a reversible capacity of 90.6 mA h g–1 at a rate as high as 20C. At 5C, 75.0% of the initial specific capacity can be retained after 400 cycles with a capacity-decay rate of 0.07% per cycle, demonstrating a superior long-term cyclability at high current density. X-ray diffraction and absorption characterization revealed reversible phase transformations and electronic structural changes during the Na+ deintercalation/intercalation process. Ni, Co and Fe ions contribute to charge compensation during charge and discharge. Although Ti ions do not contribute to the charge transfer, they play a very important role in stabilizing the structure during charge and discharge by suppressing the Fe migration. Additionally, Ti substitution can also smooth the charge–discharge plateaus effectively, which provides a potential advantage for the commercialization of this material for room temperature sodium-ion batteries.

  5. O3-type layered transition metal oxide Na(NiCoFeTi)1/4O2 as a high rate and long cycle life cathode material for sodium ion batteries

    DOE PAGES

    Yue, Ji -Li; Yang, Xiao -Qing; Zhou, Yong -Ning; ...

    2015-10-09

    High rate capability and long cycle life are challenging goals for the development of room temperature sodium-ion batteries. Here we report a new single phase quaternary O3-type layer-structured transition metal oxide Na(NiCoFeTi)1/4O2 synthesized by a simple solid-state reaction as a new cathode material for sodium-ion batteries. It can deliver a reversible capacity of 90.6 mA h g–1 at a rate as high as 20C. At 5C, 75.0% of the initial specific capacity can be retained after 400 cycles with a capacity-decay rate of 0.07% per cycle, demonstrating a superior long-term cyclability at high current density. X-ray diffraction and absorption characterizationmore » revealed reversible phase transformations and electronic structural changes during the Na+ deintercalation/intercalation process. Ni, Co and Fe ions contribute to charge compensation during charge and discharge. Although Ti ions do not contribute to the charge transfer, they play a very important role in stabilizing the structure during charge and discharge by suppressing the Fe migration. Additionally, Ti substitution can also smooth the charge–discharge plateaus effectively, which provides a potential advantage for the commercialization of this material for room temperature sodium-ion batteries.« less

  6. Emissions of metals and polychlorinated dibenzo(p)dioxins and furans (PCDD/Fs) from Portland cement manufacturing plants: inter-kiln variability and dependence on fuel-types.

    PubMed

    Zemba, Stephen; Ames, Michael; Green, Laura; Botelho, Maria João; Gossman, David; Linkov, Igor; Palma-Oliveira, José

    2011-09-15

    Emissions from Portland cement manufacturing facilities may increase health risks in nearby populations and are thus subject to stringent regulations. Direct testing of pollutant concentrations in exhaust gases provides the best basis for assessing the extent of these risks. However, these tests (i) are often conducted under stressed, rather than typical, operating conditions, (ii) may be limited in number and duration, and (iii) may be influenced by specific fuel-types and attributes of individual kilns. We report here on the results of more than 150 emissions-tests conducted of two kilns at a Portland cement manufacturing plant in Portugal. The tests measured various regulated metals and polychlorinated dibenzo(p)dioxins and furans (PCDD/Fs). Stack-gas concentrations of pollutants were found to be highly variable, with standard deviations on the order of mean values. Emission rates of many pollutants were higher when coal was used as the main kiln fuel (instead of petroleum coke). Use of various supplemental fuels, however, had little effect on stack emissions, and few statistically significant differences were observed when hazardous waste was included in the fuel mix. Significant differences in emissions for some pollutants were observed between the two kilns despite their similar designs and uses of similar fuels. All measured values were found to be within applicable regulatory limits.

  7. Ultra-low temperature radio-frequency performance of partially depleted silicon-on-insulator n-type metal-oxide-semiconductor field-effect transistors with tunnel diode body contact structures

    NASA Astrophysics Data System (ADS)

    Lu, Kai; Chen, Jing; Huang, Yuping; Liu, Jun; Luo, Jiexin; Wang, Xi

    2016-11-01

    Radio-frequency (RF) characteristics under ultra-low temperature of multi-finger partially depleted silicon-on-insulator (PD SOI) n-type metal-oxide-semiconductor field-effect transistors (nMOSFETs) with tunnel diode body-contact (TDBC) structure and T-gate body-contact (TB) structure are investigated in this paper. When operating at 77 K, TDBC device suppresses floating-body effect (FBE) as well as the TB device. For TB device and TDBC device, cut-off frequency (f T) improves as the temperature decreases to liquid-helium temperature (77 K) while that of the maximum oscillation frequency (f MAX) is opposite due to the decrease of the unilateral power gain. While operating under 77 K, f T and f MAX of TDBC device reach to 125 GHz and 77 GHz, representing 8% and 15% improvements compared with those of TB device, respectively, which is mainly due to the lower parasitic resistances and capacitances. The results indicate that TDBC SOI MOSFETs could be considered as promising candidates for analog and RF applications over a wide range of temperatures and there is immense potential for the development of RF CMOS integrated circuits for cryogenic applications.

  8. Memory and negative-resistance effects in a strained metal-gate high-k n-type field-effect-transistor from 375 K down to 77 K

    NASA Astrophysics Data System (ADS)

    Gutiérrez-D, E. A.; Vega-G, V. H.; García-R, P. J.; Huerta-G, O. V.

    2016-12-01

    We introduce an experimental alternative way of looking into the charging and discharging mechanism inside a high-k stacked oxide of a metal-gate strained n-type Field-Effect-Transistor (nFET). This alternative way reproduces a memory and negative resistance effect by biasing the nFET device in a non-conventional way. This is achieved by forward-biasing the drain-bulk junction and by setting the gate electrode in a high-impedance mode. The produced negative resistance effect (NRE) has a controllable peak-to-valley current ratio (PVCR) that goes from about 3.0 up to a value of 5.5 at room temperature. The PVCR increases up to 8.35 at T = 225 K and reduces to 2.84 at T = 375 K in a linear trend. The memory effect is observed when the drain-bulk junction voltage is swept from low to high values and back from high to low values. From low to high forward drain-bulk bias the NRE shows up and vanishes when coming back from high to low forward drain-bulk bias. The NRE and memory effects are attributed to a coupled-gate oxide charging/discharging mechanism with an induced bipolar transistor action in the channel of the FET.

  9. Electrochemical behavior of the 316L steel type in a marine culture of microalgae (Porphyridium purpureum) under the 12/12 h photoperiod and effect of different working electrode exposure conditions on the biofilm-metal interface.

    PubMed

    Djemai-Zoghlache, Yamina; Isambert, Arsène; Belhaneche-Bensemra, Naima

    2011-12-01

    The industrial crops of microalgae use processes calling upon the presence of parts of metal nature such as steel 316L type. The goal of this study is to test the electrochemical behavior of this material in a marine culture of microalgae. Porphyridium purpureum was used under a photoperiod of alternation darkness/light 12/12 h, in order to apprehend the problems of biocorrosion involved in the biofouling. The evolution of the free potential of corrosion, according to the position of the samples and for different surface roughness, observations of the surface quality under the electron microscope with sweeping were carried out. The results showed that, overall, the strain P. purpureum does not have a corrosive effect on the 316L. The free potential of corrosion lies between -0.307 and -0.005 V(SCE). The adhesion of the cells seems stronger on the interface air/solid of the half-plunged sample with surface grit polished 1,000, confirmed by the presence of biofilm on the air part. The photoperiod acts on the evolution of the generated free potential of corrosion of the one 24-h period oscillation. Furthermore, the samples plunged horizontally lead to a stabilizing effect on the potential of free corrosion.

  10. 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.

  11. 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.

  12. Sputter metalization of Wolter type optical elements

    NASA Technical Reports Server (NTRS)

    Ledger, A. M.

    1977-01-01

    An analytical task showed that the coating thickness distribution for both internal and external optical elements coated using either electron beam or sputter sources can be made uniform and will not affect the surface figure of coated elements. Also, sputtered samples of nickel, molybdenum, iridium and ruthenium deposited onto both hot and cold substrates showed excellent adhesion.

  13. Wick-Type Liquid-Metal Combustion

    DTIC Science & Technology

    1989-10-01

    3 II. THEORETICAL CONSIDERATION ........................................................... 4 2.1 Thermodynamic Properties of Li 2...Description ai correlation coefficients, Eqs. 2-4 A spontaneous emission rate c speed of light Cp specific heat D binary diffusion coefficient E...ofg Li and SF6, thermochemical properties of reactants and products were identified and the transport process was modeled.I 2.1 Thermodynamic

  14. Wick-Type Liquid-Metal Combustion

    DTIC Science & Technology

    1991-05-01

    Properties of Li2 S .......................................................... 4 2.2 Flow Analysis... light Cp specific heat D binary diffusion coefficient E energy f dimensionless stream function, Eq. 12 F Boltzmann fraction g acceleration of gravity gi...the gas phase. To model the wick combustion of Li and SF 6 , thermochemical properties of reactants and products were identified and the transport

  15. 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.

  16. Method of joining metals of significantly different expansion rates

    NASA Technical Reports Server (NTRS)

    Caler, W.; La Salle, F.; Traylor, J.

    1971-01-01

    To join a refractory metal to a dissimilar high-temperature metal, braze a section of high elasticity, high ductility metal /such as columbium or columbium alloy/ between the metals to be joined, using a fork-type joint to hold the braze and transition member in place during expansion.

  17. 49 CFR 178.705 - Standards for metal IBCs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Standards for metal IBCs. 178.705 Section 178.705... Standards § 178.705 Standards for metal IBCs. (a) The provisions in this section apply to metal IBCs intended to contain liquids and solids. Metal IBC types are designated: (1) 11A, 11B, 11N for solids...

  18. 49 CFR 178.705 - Standards for metal IBCs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Standards for metal IBCs. 178.705 Section 178.705... Standards § 178.705 Standards for metal IBCs. (a) The provisions in this section apply to metal IBCs intended to contain liquids and solids. Metal IBC types are designated: (1) 11A, 11B, 11N for solids...

  19. 49 CFR 178.705 - Standards for metal IBCs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Standards for metal IBCs. 178.705 Section 178.705... Standards § 178.705 Standards for metal IBCs. (a) The provisions in this section apply to metal IBCs intended to contain liquids and solids. Metal IBC types are designated: (1) 11A, 11B, 11N for solids...

  20. 49 CFR 178.705 - Standards for metal IBCs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Standards for metal IBCs. 178.705 Section 178.705... Standards § 178.705 Standards for metal IBCs. (a) The provisions in this section apply to metal IBCs intended to contain liquids and solids. Metal IBC types are designated: (1) 11A, 11B, 11N for solids...

  1. 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.

  2. Corrosion of refractory metals in liquid metal and gaseous environments

    SciTech Connect

    DiStefano, J.R.

    1991-01-01

    In general, refractory metals and alloys are very compatible with liquid or boiling alkali metals. However, corrosion resistance of niobium and tantalum requires maintaining low oxygen in the system. When the refractory metal contains a strong oxide former (Zr, Hf), additional oxygen in the solid metal can be tolerated if it is tied up as a stable oxide (ZrO{sub 2}, HfO{sub 2}). In sodium or potassium systems, oxygen in either the liquid metal or refractory metal can contribute to reduced corrosion resistance. The mechanical properties of refractory metals are very sensitive to interstitial elements such as oxygen, nitrogen, hydrogen, and carbon. Oxidation in air or other oxidizing environments is rapid above 300 to 400{degree}C, and some type of protection must be provided (vacuum, inert gas, coating) if refractory metals are to be used at high temperatures. Oxidation of niobium and tantalum alloys is more complex than for molybdenum and tungsten due to the formation of different oxide phases that exhibit differing degrees of protectiveness. At low to intermediate temperatures niobium and tantalum also react with hydrogen environments, and embrittlement has been reported both from hydride formation as well as from solid solution effects. At high temperatures niobium and tantalum react with nitrogen or carbon to form very stable compounds while the nitrides and carbides of molybdenum and tungsten are considerably less stable. 10 refs., 10 figs.

  3. 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.

  4. Metallic Hydrogen

    NASA Astrophysics Data System (ADS)

    Silvera, Isaac F.; Dias, Ranga; Noked, Ori; Salamat, Ashkan; Zaghoo, Mohamed

    2017-04-01

    One of the great challenges in condensed matter physics has been to produce metallic hydrogen (MH) in the laboratory. There are two approaches: solid molecular hydrogen can be compressed to high density at extreme pressures of order 5-6 megabars. The transition to MH should take place at low temperatures and is expected to occur as a structural first-order phase transition with dissociation of molecules into atoms, rather than the closing of a gap. A second approach is to produce dense molecular hydrogen at pressures of order 1-2 megabars and heat the sample. With increasing temperature, it was predicted that molecular hydrogen first melts and then dissociates to atomic metallic liquid hydrogen as a first-order phase transition. We have observed this liquid-liquid phase transition to metallic hydrogen, also called the plasma phase transition. In low-temperature studies, we have pressurized HD to over 3 megabars and observed two new phases. Molecular hydrogen has been pressurized to 4.2 megabars. A new phase transition has been observed at 3.55 megabars, but it is not yet metallic.

  5. 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,

  6. 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.

  7. 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.

  8. Fiberoptic metal detector capable of profile detection.

    PubMed

    Hua, Wei-Shu; Hooks, Joshua R; Erwin, Nicholas A; Wu, Wen-Jong; Wang, Wei-Chih

    2011-03-31

    The purpose of this paper is to develop a novel ferromagnetic polymeric metal detector system by using a fiber-optic Mach-Zehnder interferometer with a newly developed ferromagnetic polymer as the magnetostrictive sensing device. This ferromagnetic polymeric metal detector system is simple to fabricate, small in size, and resistant to RF interference (which is common in typical electromagnetic type metal detectors). Metal detection is made possible by disrupting the magnetic flux density present on the magnetostrictive sensor. This paper discusses the magnetic properties of the ferromagnetic polymers. In addition, the preliminary results of successful sensing of different geometrical metal shapes will be discussed.

  9. Fiberoptic metal detector capable of profile detection

    NASA Astrophysics Data System (ADS)

    Hua, Wei-Shu; Hooks, Joshua R.; Erwin, Nicholas A.; Wu, Wen-Jong; Wang, Wei-Chih

    2011-04-01

    The purpose of this paper is to develop a novel ferromagnetic polymeric metal detector system by using a fiber-optic Mach-Zehnder interferometer with a newly developed ferromagnetic polymer as the magnetostrictive sensing device. This ferromagnetic polymeric metal detector system is simple to fabricate, small in size, and resistant to RF interference (which is common in typical electromagnetic type metal detectors). Metal detection is made possible by disrupting the magnetic flux density present on the magnetostrictive sensor. This paper discusses the magnetic properties of the ferromagnetic polymers. In addition, the preliminary results of successful sensing of different geometrical metal shapes will be discussed.

  10. Fiberoptic metal detector capable of profile detection

    PubMed Central

    Hua, Wei-Shu; Hooks, Joshua R.; Erwin, Nicholas A.; Wu, Wen-Jong; Wang, Wei-Chih

    2011-01-01

    The purpose of this paper is to develop a novel ferromagnetic polymeric metal detector system by using a fiber-optic Mach-Zehnder interferometer with a newly developed ferromagnetic polymer as the magnetostrictive sensing device. This ferromagnetic polymeric metal detector system is simple to fabricate, small in size, and resistant to RF interference (which is common in typical electromagnetic type metal detectors). Metal detection is made possible by disrupting the magnetic flux density present on the magnetostrictive sensor. This paper discusses the magnetic properties of the ferromagnetic polymers. In addition, the preliminary results of successful sensing of different geometrical metal shapes will be discussed. PMID:24357903

  11. Comparing the Clinical Outcomes between Drug Eluting Stents and Bare Metal Stents in Patients with Insulin-Treated Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of 10 Randomized Controlled Trials

    PubMed Central

    Bundhun, Pravesh Kumar; Bhurtu, Akash; Soogund, Mohammad Zafooruddin Sani; Long, Man-Yun

    2016-01-01

    Background Several studies have shown Drug Eluting Stents (DES) to be better compared to Bare Metal Stents (BMS) in patients with type 2 Diabetes Mellitus (T2DM). Since, the adverse clinical outcomes in patients with Insulin-Treated Type 2 Diabetes Mellitus (ITDM) implanted with DES and BMS have not been previously studied, we aim to compare the clinical outcomes in similar patients with cardiovascular diseases, treated with DES and BMS. Methods Randomized Controlled Trials (RCTs) comparing patients treated with DES and BMS were searched from PubMed and EMBASE databases. Outcome data for the patients with ITDM were carefully extracted. Major Adverse Cardiac Events (MACEs), mortality, Target Vessel Revascularization (TVR), Target Lesion Revascularization (TLR), Myocardial Infarction (MI) and Stent Thrombosis (ST) were considered as the clinical endpoints for this analysis. Odds ratios (OR) with 95% confidence intervals (CIs) were calculated and the pooled analyses were performed with RevMan 5.3 software. Results Ten RCTs consisting of 830 patients with ITDM (477 patients in the DES group and 353 patients in the BMS group) from a total number of 9,141 patients were included in this analysis. During a follow-up period from one month to one year, MACEs were not increased with the use of DES in these patients with ITDM. At 9 months, MACEs were significantly lower in the DES group with OR: 0.40, 95% CI: 0.23–0.72; P = 0.002 with no increase in mortality. TVR and TLR also favored the DES group with OR: 0.44, 95% CI: 0.22–0.88, P = 0.02 and OR: 0.28, 95% CI: 0.14–0.53; P = 0.0001 respectively at 9 months, and OR: 0.46, 95% CI: 0.23–0.94, P = 0.03 and OR: 0.28, 95% CI: 0.14–0.55; P = 0.0003 respectively at one year. Results for MI, and ST were not statistically significant. Conclusion Compared to BMS, DES were associated with a significantly lower rate of repeated revascularization, without any increase in MACEs or mortality in these patients with ITDM during a

  12. 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.

  13. Metal oxide chemistry in solution: the early transition metal polyoxoanions.

    PubMed

    Day, V W; Klemperer, W G

    1985-05-03

    Many of the early transition elements form large polynuclear metal-oxygen anions containing up to 200 atoms or more. Although these polyoxoanions have been investigated for more than a century, detailed studies of structure and reactivity were not possible until the development of modern x-ray crystallographic and nuclear magnetic resonance spectroscopic techniques. Systematic studies of small polyoxoanions in inert, aprotic solvents have clarified many of the principles governing their structure and reactivity, and also have made possible the preparation of entirely new types of covalent derivatives such as CH(2)Mo(4)O(15)H(3-), C(5)H(5)TiMo(5)O(18)(3-), and (OC)(3)Mn(Nb(2)W(4)O(19))(3-). Since most early transition metal polyoxoanions have structures based on close-packed oxygen arrays containing interstitial metal centers, their chemistry offers a rare opportunity to study chemical transformations in detail on well-defined metal oxide surfaces.

  14. METHOD OF PRODUCING DENSE CONSOLIDATED METALLIC REGULUS

    DOEpatents

    Magel, T.T.

    1959-08-11

    A methcd is presented for reducing dense metal compositions while simultaneously separating impurities from the reduced dense metal and casting the reduced parified dense metal, such as uranium, into well consolidated metal ingots. The reduction is accomplished by heating the dense metallic salt in the presence of a reducing agent, such as an alkali metal or alkaline earth metal in a bomb type reacting chamber, while applying centrifugal force on the reacting materials. Separation of the metal from the impurities is accomplished essentially by the incorporation of a constricted passageway at the vertex of a conical reacting chamber which is in direct communication with a collecting chamber. When a centrifugal force is applled to the molten metal and slag from the reduction in a direction collinear with the axis of the constricted passage, the dense molten metal is forced therethrough while the less dense slag is retained within the reaction chamber, resulting in a simultaneous separation of the reduced molten metal from the slag and a compacting of the reduced metal in a homogeneous mass.

  15. 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.

  16. 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.

  17. Metal matrix composite structural panel construction

    NASA Technical Reports Server (NTRS)

    Mcwithey, R. R.; Royster, D. M. (Inventor); Bales, T. T.

    1983-01-01

    Lightweight capped honeycomb stiffeners for use in fabricating metal or metal/matrix exterior structural panels on aerospace type vehicles and the process for fabricating same are disclosed. The stiffener stringers are formed in sheets, cut to the desired width and length and brazed in spaced relationship to a skin with the honeycomb material serving directly as the required lightweight stiffeners and not requiring separate metal encasement for the exposed honeycomb cells.

  18. Highly efficient one-dimensional ZnO nanowire-based dye-sensitized solar cell using a metal-free, D-π-A-type, carbazole derivative with more than 5% power conversion.

    PubMed

    Barpuzary, Dipankar; Patra, Anindya S; Vaghasiya, Jayraj V; Solanki, Bharat G; Soni, Saurabh S; Qureshi, Mohammad

    2014-08-13

    Hydrothermally grown one-dimensional ZnO nanowire (1D ZnO NW) and a newly synthesized metal-free, D-π-A type, carbazole dye (SK1) sensitizer-based photovoltaic device with a power conversion efficiency (PCE) of more than 5% have been demonstrated by employing the cobalt tris(2,2'-bipyridyl) redox shuttle. A short-circuit current density (Jsc) of ∼12.0 mA/cm(2), an open-circuit voltage (Voc) of ∼719 mV, and a fill factor (FF) of ∼65% have been afforded by the 1D ZnO NW-based dye-sensitized solar cell (DSSC) incorporating [Co(bpy)3](3+/2+) complex as the one-electron redox mediator. In contrast, the identical DSSC with traditional I3(-)/I(-) electrolyte has shown a Jsc ≈ 12.2 mA/cm(2), a Voc ≈ 629 mV, and a FF ≈ 62%, yielding a PCE of ∼4.7%. The persuasive role of the inherent superior electron transport property of 1D ZnO NWs in enhancing the device efficiency is evidenced from the impoverished performance of the DSSCs with photoanodes fabricated using ZnO nanoparticles (NPs). The DSSCs having ZnO NP-based photoanodes have achieved the PCEs of ∼3.6% and ∼3.2% using cobalt- and iodine-based redox electrolytes, respectively. The electronic interactions between the SK1 sensitizer and ZnO (NWs and NPs) to induce the photogenerated charge transfer from SK1 to the conduction band (CB) of ZnO are evidenced from the significant quenching of photoluminescence and exciton lifetime decay of SK1, when it is anchored onto the ZnO architectures. The energetics of the SK1 dye molecule are estimated by combining the spectroscopic and electrochemical techniques. The electronic distributions of SK1 dye molecule in its HOMO and LUMO energy levels are interpreted using density functional theory (DFT)-based calculations. The electron donor-π linker-acceptor (D-π-A) configuration of SK1 dye provides an intramolecular charge transfer within the molecule, prompting the electron migration from the carbazole donor to cyanoacrylic acceptor moiety via the oligo

  19. Solution processed metal oxide thin film hole transport layers for high performance organic solar cells

    DOEpatents

    Steirer, K. Xerxes; Berry, Joseph J.; Chesin, Jordan P.; Lloyd, Matthew T.; Widjonarko, Nicodemus Edwin; Miedaner, Alexander; Curtis, Calvin J.; Ginley, David S.; Olson, Dana C.

    2017-01-10

    A method for the application of solution processed metal oxide hole transport layers in organic photovoltaic devices and related organic electronics devices is disclosed. The metal oxide may be derived from a metal-organic precursor enabling solution processing of an amorphous, p-type metal oxide. An organic photovoltaic device having solution processed, metal oxide, thin-film hole transport layer.

  20. 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.

  1. 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.

  2. Empirical modeling of heavy metal extraction by EDDS from single-metal and multi-metal contaminated soils.

    PubMed

    Yip, Theo C M; Tsang, Daniel C W; Ng, Kelvin T W; Lo, Irene M C

    2009-01-01

    The effectiveness of using biodegradable EDDS (S,S-ethylenediaminedisuccinic acid) for metal extraction has drawn increasing attention in recent years. In this study, an empirical model, which utilized the initial metal distribution in soils and a set of parameter values independently determined from sequential extraction, was developed for estimating the time-dependent heavy metal extraction by EDDS from single-metal and multi-metal contaminated soils. The model simulation provided a satisfactory description of the experimental results of the 7-d extraction kinetics of Cu, Zn, and Pb in both artificially contaminated and field-contaminated soils. Thus, independent and prior assessment of extraction efficiency would be available to facilitate the engineering applications of EDDS. Furthermore, a simple empirical equation using the initial metal distribution was also proposed to estimate the extraction efficiency at equilibrium. It was found that, for the same type of soils, higher extraction efficiency was achieved in multi-metal contaminated soils than in single-metal contaminated soils. The differences were 4-9%, 9-16%, and 21-31% for Cu, Zn, and Pb, respectively, probably due to the larger proportion of exchangeable and carbonate fractions of sorbed Zn and Pb in multi-metal contaminated soils. EDDS-promoted mineral dissolution, on the other hand, was more significant in multi-metal contaminated soils as a result of the higher EDDS concentration applied to the soils of higher total metal content.

  3. p-i-n/n-i-p type planar hybrid structure of highly efficient perovskite solar cells towards improved air stability: synthetic strategies and the role of p-type hole transport layer (HTL) and n-type electron transport layer (ETL) metal oxides.

    PubMed

    Mali, Sawanta S; Hong, Chang Kook

    2016-05-19

    There has been fast recent progress in perovskite solar cells (PSCs) towards low cost photovoltaic technology. Organometal mixed halide (MAPbX or FAPbX) perovskites are the most promising light absorbing material sandwiched between the electron transport layer (ETL) and hole transport layer (HTL). These two layers play a critical role in boosting the power conversion efficiency (PCE) and maintaining air stability. However, the device stability is a serious issue in regular as well as p-i-n inverted type perovskite solar cells. This mini-review briefly outlines the state-of-art of p-i-n/n-i-p type planar hybrid perovskite solar cells using MAPbX/FAPbX perovskite absorbing layers. Later, we will focus on recent trends, progress and further opportunities in exploring the air stable hybrid planar structure PSCs.

  4. p-i-n/n-i-p type planar hybrid structure of highly efficient perovskite solar cells towards improved air stability: synthetic strategies and the role of p-type hole transport layer (HTL) and n-type electron transport layer (ETL) metal oxides

    NASA Astrophysics Data System (ADS)

    Mali, Sawanta S.; Hong, Chang Kook

    2016-05-01

    There has been fast recent progress in perovskite solar cells (PSCs) towards low cost photovoltaic technology. Organometal mixed halide (MAPbX or FAPbX) perovskites are the most promising light absorbing material sandwiched between the electron transport layer (ETL) and hole transport layer (HTL). These two layers play a critical role in boosting the power conversion efficiency (PCE) and maintaining air stability. However, the device stability is a serious issue in regular as well as p-i-n inverted type perovskite solar cells. This mini-review briefly outlines the state-of-art of p-i-n/n-i-p type planar hybrid perovskite solar cells using MAPbX/FAPbX perovskite absorbing layers. Later, we will focus on recent trends, progress and further opportunities in exploring the air stable hybrid planar structure PSCs.

  5. Toxicity of heavy metals and metal-containing nanoparticles on plants.

    PubMed

    Mustafa, Ghazala; Komatsu, Setsuko

    2016-08-01

    Plants are under the continual threat of changing climatic conditions that are associated with various types of abiotic stresses. In particular, heavy metal contamination is a major environmental concern that restricts plant growth. Plants absorb heavy metals along with essential elements from the soil and have evolved different strategies to cope with the accumulation of heavy metals. The use of proteomic techniques is an effective approach to investigate and identify the biological mechanisms and pathways affected by heavy metals and metal-containing nanoparticles. The present review focuses on recent advances and summarizes the results from proteomic studies aimed at understanding the response mechanisms of plants under heavy metal and metal-containing nanoparticle stress. Transport of heavy metal ions is regulated through the cell wall and plasma membrane and then sequestered in the vacuole. In addition, the role of different metal chelators involved in the detoxification and sequestration of heavy metals is critically reviewed, and changes in protein profiles of plants exposed to metal-containing nanoparticles are discussed in detail. Finally, strategies for gaining new insights into plant tolerance mechanisms to heavy metal and metal-containing nanoparticle stress are presented. This article is part of a Special Issue entitled: Plant Proteomics--a bridge between fundamental processes and crop production, edited by Dr. Hans-Peter Mock.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Impact of metals on the biodegradation of organic pollutants.

    PubMed Central

    Sandrin, Todd R; Maier, Raina M

    2003-01-01

    Forty percent of hazardous waste sites in the United States are co-contaminated with organic and metal pollutants. Data from both aerobic and anaerobic systems demonstrate that biodegradation of the organic component can be reduced by metal toxicity. Metal bioavailability, determined primarily by medium composition/soil type and pH, governs the extent to which metals affect biodegradation. Failure to consider bioavailability rather than total metal likely accounts for much of the enormous variability among reports of inhibitory concentrations of metals. Metals appear to affect organic biodegradation through impacting both the physiology and ecology of organic degrading microorganisms. Recent approaches to increasing organic biodegradation in the presence of metals involve reduction of metal bioavailability and include the use of metal-resistant bacteria, treatment additives, and clay minerals. The addition of divalent cations and adjustment of pH are additional strategies currently under investigation. PMID:12826480

  12. The chemical form of metallic debris in tissues surrounding metal-on-metal hips with unexplained failure.

    PubMed

    Hart, Alister J; Quinn, Paul D; Sampson, Barry; Sandison, Ann; Atkinson, Kirk D; Skinner, John A; Powell, Jonathan J; Mosselmans, J Fred W

    2010-11-01

    Implant-derived material from metal-on-metal (MOM) hip arthroplasties may be responsible for an unexplained tissue inflammatory response. The chemical form of the metal species in the tissues is predominantly chromium (Cr), but the currently used techniques have not been able to determine whether this is Cr(III) phosphate or Cr(III) oxide. The analytical challenge must overcome the fact that the metal in the tissues is at a relatively low concentration and tissue preparation or the microscopy beam used can affect the results. Microfocus X-ray spectroscopy using a synchrotron beam is useful in addressing both these issues. Using this technique we compared tissue from failed MOM hips with: (1) tissue from metal-on-polyethylene (MOP) hips; (2) chemical standards; (3) metal discs cut from MOM hips. The most abundant implant-related species in all MOM hip tissues contained Cr. Comparison with standards revealed the chemical form was Cr(III) phosphate, which did not vary with manufacturer type (four types analysed) or level of blood metal ions. Cobalt (Co) and molybdenum (Mo) were occasionally present in areas of high Cr. Co was normally found in a metallic state in the tissue, while Mo was found in an oxidized state. The variety of metallic species may have arisen from corrosion, wear or a combination of both. No evidence of Cr(VI) was seen in the tissues examined.

  13. Bulk photoemission from metal films and nanoparticles

    SciTech Connect

    Ikhsanov, R Sh; Babicheva, V E; Protsenko, I E; Uskov, A V; Guzhva, M E

    2015-01-31

    Internal emission of photoelectrons from metal films and nanoparticles (nanowires and nanospheres) into a semiconductor matrix is studied theoretically by taking into account the jump of the effective electron mass at the metal – semiconductor interface and the cooling effect of hot electrons due to electron – electron collisions in the metal. The internal quantum efficiency of photoemission for the film and nanoparticles of two types (nanospheres and nanowires) is calculated. It is shown that the reduction of the effective mass of the electron during its transition from metal to semiconductor may lead to a significant (orders of magnitude and higher) decrease in the internal quantum efficiency of bulk photoemission. (nanostructures)

  14. Metal-phosphate binders

    DOEpatents

    Howe, Beth Ann [Lewistown, IL; Chaps-Cabrera, Jesus Guadalupe [Coahuila, MX

    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.

  15. The Effect of Metal Oxide on Nanoparticles from Thermite Reactions

    ERIC Educational Resources Information Center

    Moore, Lewis Ryan

    2006-01-01

    The purpose of this research was to determine how metal oxide used in a thermite reaction can impact the production of nanoparticles. The results showed the presence of nanoparticles (less than 1 micron in diameter) of at least one type produced by each metal oxide. The typical particles were metallic spheres, which ranged from 300 nanometers in…

  16. CORROSION RESISTANT JACKETED METAL BODY

    DOEpatents

    Brugmann, E.W.

    1958-08-26

    Jacketed metal bodies of the type used as fuel elements for nuclear reactors, which contain an internal elongated body of fissionable material jacketed in a corrosion resistant metal are described. The ends of the internal bodies are provided with screw threads having a tapered outer end. The jacket material overlaps the ends and extends into the tapered section of the screw threaded opening. Screw caps with a mating tapered section are screwed into the ends of the body to compress the jacket material in the tapered sections to provtde an effective seal against corrosive gases and liquids.

  17. Strategic metal deposits of the Arctic Zone

    NASA Astrophysics Data System (ADS)

    Bortnikov, N. S.; Lobanov, K. V.; Volkov, A. V.; Galyamov, A. L.; Vikent'ev, I. V.; Tarasov, N. N.; Distler, V. V.; Lalomov, A. V.; Aristov, V. V.; Murashov, K. Yu.; Chizhova, I. A.; Chefranov, R. M.

    2015-11-01

    Mineral commodities rank high in the economies of Arctic countries, and the status of mineral resources and the dynamics of their development are of great importance. The growing tendency to develop strategic metal resources in the Circumarctic Zone is outlined in a global perspective. The Russian Arctic Zone is the leading purveyor of these metals to domestic and foreign markets. The comparative analysis of tendencies in development of strategic metal resources of the Arctic Zone in Russia and other countries is crucial for the elaboration of trends of geological exploration and research engineering. This paper provides insight into the development of Arctic strategic metal resources in global perspective. It is shown that the mineral resource potential of the Arctic circumpolar metallogenic belt is primarily controlled by large and unique deposits of nonferrous, noble, and rare metals. The prospective types of economic strategic metal deposits in the Russian Arctic Zone are shown.

  18. Safe disposal of metal values in slag

    SciTech Connect

    Halpin, P.T.; Zarur, G.L.

    1982-10-26

    The method of safely disposing of sludge containing metal values capable of displaying toxic ecological properties includes the steps of deriving from an organic or inorganic sludge an intermediate product such as a dewatered sludge or an incinerated ash, and adding this intermediate product to a metal smelting step of a type producing a slag such that most of the metal values become encapsulated in the slag. Some precious metal values may be recovered with the metal being smelted, and may be subsequently separated therefrom by appropriate metal winning steps. The sludge product brings to the smelting process certain additives needed therein such as silica and phosphates for the slag, alumina and magnesium to lower the viscosity of the molten slag, and organic matter serving as reducing agents.

  19. Spectral types for early-type stars observed by Skylab

    NASA Technical Reports Server (NTRS)

    Roman, N. G.

    1978-01-01

    MK spectral types are presented for 246 early-type stars observed with the S-019 ultraviolet stellar astronomy experiment on Skylab. K-line types are also given where applicable, and various peculiar stars are identified. The peculiar stars include five silicon stars, a shell star, a helium-rich star, a silicon-strontium star, a chromium-europium star, and two marginal metallic-line stars.

  20. 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.

  1. 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.

  2. 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.

  3. On the Metal Ion Selectivity of Oxoacid Extractants

    SciTech Connect

    Hay, Benjamin; Chagnes, Alexandre; Cote, Gerard

    2013-01-01

    Relationships between metal chelate stability, ligand basicity, and metal ion acidity are reviewed and the general applicability is illustrated by linear correlations between aqueous stability constants and ligand pKa values for 35 metals with 26 ligands. The results confirm that most individual ligands of this type exhibit a stability ordering that correlates with the Lewis acidity of the metal ion. It is concluded that the general metal ion selectivity exhibited by liquid-liquid oxoacid extractants such as carboxylic acids, -diketones, and alkylphosphoric acids reflects the intrinsic affinity of the metal ion for the negative oxygen donor ligand.

  4. Aircraft Metal Skin Repair and Honeycomb Structure Repair; Sheet Metal Work 3: 9857.02.

    ERIC Educational Resources Information Center

    Dade County Public Schools, Miami, FL.

    The course helps students determine types of repairs, compute repair sizes, and complete the repair through surface protection. Course content includes goals, specific objectives, protection of metals, repairs to metal skin, and honeycomb structure repair. A bibliography and post-test are appended. A prerequisite for this course is mastery of the…

  5. Blood Types

    MedlinePlus

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Blood Types KidsHealth > For Teens > Blood Types Print A A ... or straight hair instead of curly. ...Make Eight Blood Types The different markers that can be found in ...

  6. Light metals 1989

    SciTech Connect

    Campbell, P.G.

    1989-01-01

    This volume contains a cross section of the most important developments in the light metals field. The papers detail the latest solutions to problems in alumina and bauxite; carbon technology; cast shop technology; reduction technology; and reactive metals. Nearly every important company and research facility in the aluminum industry is represented. Light Metals 1989 is a reference for anyone in light metals technology.

  7. 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.

  8. 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.

  9. Single Wall Nanotube Type-Specific Functionalization and Separation

    NASA Technical Reports Server (NTRS)

    Boul, Peter; Nikolaev, Pavel; Sosa, Edward; Arepalli, Sivaram; Yowell, Leonard

    2008-01-01

    Metallic single-wall carbon nanotubes were selectively solubilized in THF and separated from semiconducting nanotubes. Once separated, the functionalized metallic tubes were de-functionalized to restore their metallic band structure. Absorption and Raman spectroscopy of the enriched samples support conclusions of the enrichment of nanotube samples by metallic type. A scalable method for enriching nanotube conductive type has been developed. Raman and UV-Vis data indicate SWCNT reaction with dodecylbenzenediazonium results in metallic enrichment. It is expected that further refinement of this techniques will lead to more dramatic separations of types and diameters.

  10. Cellular partitioning of nanoparticulate versus dissolved metals in marine phytoplankton.

    PubMed

    Bielmyer-Fraser, Gretchen K; Jarvis, Tayler A; Lenihan, Hunter S; Miller, Robert J

    2014-11-18

    Discharges of metal oxide nanoparticles into aquatic environments are increasing with their use in society, thereby increasing exposure risk for aquatic organisms. Separating the impacts of nanoparticle from dissolved metal pollution is critical for assessing the environmental risks of the rapidly growing nanomaterial industry, especially in terms of ecosystem effects. Metal oxides negatively affect several species of marine phytoplankton, which are responsible for most marine primary production. Whether such toxicity is generally due to nanoparticles or exposure to dissolved metals liberated from particles is uncertain. The type and severity of toxicity depends in part on whether phytoplankton cells take up and accumulate primarily nanoparticles or dissolved metal ions. We compared the responses of the marine diatom, Thalassiosira weissflogii, exposed to ZnO, AgO, and CuO nanoparticles with the responses of T. weissflogii cells exposed to the dissolved metals ZnCl2, AgNO3, and CuCl2 for 7 d. Cellular metal accumulation, metal distribution, and algal population growth were measured to elucidate differences in exposure to the different forms of metal. Concentration-dependent metal accumulation and reduced population growth were observed in T. weissflogii exposed to nanometal oxides, as well as dissolved metals. Significant effects on population growth were observed at the lowest concentrations tested for all metals, with similar toxicity for both dissolved and nanoparticulate metals. Cellular metal distribution, however, markedly differed between T. weissflogii exposed to nanometal oxides versus those exposed to dissolved metals. Metal concentrations were highest in the algal cell wall when cells were exposed to metal oxide nanoparticles, whereas algae exposed to dissolved metals had higher proportions of metal in the organelle and endoplasmic reticulum fractions. These results have implications for marine plankton communities as well as higher trophic levels, since

  11. Influence of sulfhydryl sites on metal binding by bacteria

    NASA Astrophysics Data System (ADS)

    Nell, Ryan M.; Fein, Jeremy B.

    2017-02-01

    The role of sulfhydryl sites within bacterial cell envelopes is still unknown, but the sites may control the fate and bioavailability of metals. Organic sulfhydryl compounds are important complexing ligands in aqueous systems and they can influence metal speciation in natural waters. Though representing only approximately 5-10% of the total available binding sites on bacterial surfaces, sulfhydryl sites exhibit high binding affinities for some metals. Due to the potential importance of bacterial sulfhydryl sites in natural systems, metal-bacterial sulfhydryl site binding constants must be determined in order to construct accurate models of the fate and distribution of metals in these systems. To date, only Cd-sulfhydryl binding has been quantified. In this study, the thermodynamic stabilities of Mn-, Co-, Ni-, Zn-, Sr- and Pb-sulfhydryl bacterial cell envelope complexes were determined for the bacterial species Shewanella oneidensis MR-1. Metal adsorption experiments were conducted as a function of both pH, ranging from 5.0 to 7.0, and metal loading, from 0.5 to 40.0 μmol/g (wet weight) bacteria, in batch experiments in order to determine if metal-sulfhydryl binding occurs. Initially, the data were used to calculate the value of the stability constants for the important metal-sulfhydryl bacterial complexes for each metal-loading condition studied, assuming a single binding reaction for the dominant metal-binding site type under the pH conditions of the experiments. For most of the metals that we studied, these calculated stability constant values increased significantly with decreasing metal loading, strongly suggesting that our initial assumption was not valid and that more than one type of binding occurs at the assumed binding site. We then modeled each dataset with two distinct site types with identical acidity constants: one site with a high metal-site stability constant value, which we take to represent metal-sulfhydryl binding and which dominates under low

  12. Metal content of earthworms in sludge-amended soils: uptake and loss

    SciTech Connect

    Neuhauser, E.F.; Malecki, M.R.; Cukic, Z.V.

    1985-11-01

    The widespread practice of landspreading of sludge has raised concern about increasing concentrations of potentially toxic metals in soils, with the possibility of these metals adversely impacting terrestrial and aquatic ecosystems. Earthworms, as one of the largest components of the soil biota, are useful indicators of potentially toxic soil metal concentrations. The study describes the metal content of five metals (Cd, Cu, Ni, Pb, and Zn) in one earthworm species, Allolobophora tuberculata, as a function of varying soil metal concentrations in the same soil type and the ability of the earthworms to bioconcentrate the five metals. The rate of uptake of the five metals in earthworms with initially low concentrations of metals placed in a soil with high metal concentrations was evaluated for a 112 day period. The rate of loss of the five metals in earthworms with initially high metal concentrations placed in soil with low metal concentrations was also examined.

  13. 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.

  14. Metals and metal derivatives in medicine.

    PubMed

    Colotti, Gianni; Ilari, Andrea; Boffi, Alberto; Morea, Veronica

    2013-02-01

    Several chemical elements are required by living organisms in addition to the four elements carbon, hydrogen, nitrogen and oxygen usually present in common organic molecules. Many metals (e.g. sodium, potassium, magnesium, calcium, iron, zinc, copper, manganese, chromium, molybdenum and selenium) are known to be required for normal biological functions in humans. Disorders of metal homeostasis and of metal bioavailability, or toxicity caused by metal excess, are responsible for a large number of human diseases. Metals are also extensively used in medicine as therapeutic and/or diagnostic agents. In the past 5000 years, metals such as arsenic, gold and iron have been used to treat a variety of human diseases. Nowadays, an ever-increasing number of metal-based drugs is available. These contain a broad spectrum of metals, many of which are not among those essential for humans, able to target proteins and/or DNA. This mini-review describes metal-containing compounds targeting DNA or proteins currently in use, or designed to be used, as therapeutics against cancer, arthritis, parasitic and other diseases, with a special focus on the available information, often provided by X-ray studies, about their mechanism of action at a molecular level. In addition, an overview of metal complexes used for diagnosing diseases is presented.

  15. Critical fields of liquid superconducting metallic hydrogen

    NASA Technical Reports Server (NTRS)

    Jaffe, J.; Ashcroft, N. W.

    1983-01-01

    Liquid metallic hydrogen, in a fully dissociated state, is predicted at certain densities to pass from dirty to clean and from type II to type I superconducting behavior as temperature is lowered. Previously announced in STAR as N82-29374

  16. Metal electrode for amorphous silicon solar cells

    DOEpatents

    Williams, Richard

    1983-01-01

    An amorphous silicon solar cell having an N-type region wherein the contact to the N-type region is composed of a material having a work function of about 3.7 electron volts or less. Suitable materials include strontium, barium and magnesium and rare earth metals such as gadolinium and yttrium.

  17. 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.

  18. 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.

  19. Metal-carbon nanostructures

    SciTech Connect

    Puretzky, A.A.; Hettich, R.L.; Jin, Changming; Haufler, R.E.; Compton, R.N.; Tuinman, A.A.

    1993-12-31

    Ultrafine particles formed by XeCl laser photolysis of M(CO){sub 6}, M = V, Cr, Mo, and W, have been analyzed by Fourier transform mass spectrometry and other techniques. Novel metal carbide clusters, (MoC{sub 4}){sub n}, n = 1 {minus} 4 and (WC{sub 4}){sub m}, m = 1 {minus} 8, were detected and studied. The material produced by photolysis of V(CO){sub 6} shows a series of vanadium-oxygen clusters, V{sub x}O{sub 2x+2}, x = 2 {minus} 10. No clusters of any type were detected in the photolysis product of Cr(CO){sub 6}. Structures based on the experimental evidence are proposed and discussed in light of their chemical reactivity.

  20. Magnetic antenna using metallic glass

    NASA Technical Reports Server (NTRS)

    Desch, Michael D. (Inventor); Farrell, William M. (Inventor); Houser, Jeffrey G. (Inventor)

    1996-01-01

    A lightweight search-coil antenna or sensor assembly for detecting magnetic fields and including a multi-turn electromagnetic induction coil wound on a spool type coil form through which is inserted an elongated coil loading member comprised of metallic glass material wrapped around a dielectric rod. The dielectric rod consists of a plastic or a wooden dowel having a length which is relatively larger than its thickness so as to provide a large length-to-diameter ratio. A tri-axial configuration includes a housing in which is located three substantially identical mutually orthogonal electromagnetic induction coil assemblies of the type described above wherein each of the assemblies include an electromagnetic coil wound on a dielectric spool with an elongated metallic glass coil loading member projecting therethrough.