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Sample records for delta nisub 3cb

  1. Effect of DC current polarization on the electrochemical behaviour of La{sub 2}NiO{sub 4+{delta}} and La{sub 3}Ni{sub 2}O{sub 7+{delta}}-based systems

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    Perez-Coll, D.; Aguadero, A.; Escudero, M.J. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Av. Complutense 22, 28040 Madrid (Spain); Daza, L. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Av. Complutense 22, 28040 Madrid (Spain); Instituto de Catalisis y Petroleoquimica (CSIC), C/ Marie Curie 2, Campus Cantoblanco, 28049 Madrid (Spain)

    2009-07-01

    The electrode performance of La{sub 2}NiO{sub 4} and La{sub 3}Ni{sub 2}O{sub 7} as cathode materials for solid oxide fuel cells (SOFC) was analyzed. The study was focused on the electrode polarization resistance of the interfaces formed by the cathodes with Ce{sub 0.8}Sm{sub 0.2}O{sub 2-{delta}} + 2%Co electrolyte. The study was extended to cathodes based on La{sub 2}NiO{sub 4}-Ce{sub 0.8}Sm{sub 0.2}O{sub 2-{delta}} composite and Pt to analyze the effect of changing the electronic and/or ionic transport properties on the electrode interface resistance. The electrode performance was studied in open circuit conditions and with DC current polarization. Important differences in the performance of the pure cathode materials were obtained as function of DC current flux. However, in La{sub 2}NiO{sub 4}-Ce{sub 0.8}Sm{sub 0.2}O{sub 2-{delta}} composite the DC current flux produces minor changes in the electrode polarization resistance. The aging process also affects the OCV electrode performance of cathodes based on Pt and pure ceramics, whereas the effect is practically invaluable in La{sub 2}NiO{sub 4}-Ce{sub 0.8}Sm{sub 0.2}O{sub 2-{delta}} composite. The electrode performance is higher for the composite cathode compared to pure ceramic electrodes for OCV or for low values of DC polarization. However, the important decrease in the interface resistance obtained for high values of DC current flux for La{sub 2}NiO{sub 4} and La{sub 3}Ni{sub 2}O{sub 7} cathodes increases their electrode performances to values close to those obtained in La{sub 2}NiO{sub 4}-Ce{sub 0.8}Sm{sub 0.2}O{sub 2-{delta}} composite. This retains the cathode overpotential with values as low as 140 mV at 750 C for values of current load of 530 mA cm{sup -2} for both pure and composite La{sub 2}NiO{sub 4}-based cathodes. The low cathode overpotential allows to estimate values of power density between 300 and 350 mW cm{sup -2} at 750 C for La{sub 2}NiO{sub 4}, La{sub 3}Ni{sub 2}O{sub 7} and La{sub 2}Ni

  2. Oxygen transport properties of La{sub 2}Ni{sub 1-x}Cu{sub x}O{sub 4+}{delta} mixed conducting oxides

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    Boehm, E.; Bassat, J.M.; Dordor, P.; Mauvy, F.; Grenier, J.C. [Institut de Chimie de la Matiere Condensee de Bordeaux - ICMCB-CNRS, 33 - Pessac (France); Steil, M.C. [Universite de Science et Technologie de Lille, Lab. de Cristallochimie et de Physicochimie du Solide UMR CNRS 8012, ENSCL, 59 - Villeneuve d' Ascq (France)

    2003-07-01

    Materials formulated La{sub 2}Ni{sub 1-x}Cu{sub x}O{sub 4+{delta}} (0 {<=} x {<=} 1) have been prepared and characterized using various techniques: a particular attention has been paid to their mixed conduction properties in view of application as SOFC cathode. These oxides show a good thermal stability in terms of oxygen over-stoichiometry and thermal expansion coefficient (TEC {approx}13 x 10{sup -6} K{sup -1}). In addition, they exhibit high electrical conductivity ({approx}100 S.cm{sup -1}) as well as high values of oxygen diffusion and surface exchange coefficients (D{sup *} and k) which have been determined using secondary ion mass spectroscopy (SIMS) of the {sup 18}O isotope. Highly dense ceramics have been prepared for these measurements, which has required a specific study of the densification of these materials. They exhibit D{sup *} and k coefficients one order of magnitude higher than those of the best perovskite materials. The pure nickelate seems to show the most promising properties for the oxygen reduction electro-catalysis. (authors)

  3. In situ high temperature neutron powder diffraction study of La{sub 2}Ni{sub 0.6}Cu{sub 0.4}O{sub 4+{delta}} in air: Correlation with the electrical behaviour

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    Aguadero, A.; Escudero, M.J. [Centro de Investigaciones Energeticas Mediambientales y Tecnologicas (CIEMAT), Av. Complutense 22, 28040 Madrid (Spain); Alonso, J.A. [Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, 28049 Madrid (Spain); Fernandez-Diaz, M.T. [Institute Laue-Langevin (ILL) 156X, F-38042 Grenoble Cedex 9 (France); Daza, L. [Centro de Investigaciones Energeticas Mediambientales y Tecnologicas (CIEMAT), Av. Complutense 22, 28040 Madrid (Spain); Instituto de Catalisis y Petroleoquimica (CSIC), Marie-Curie 2, Campus Cantoblanco, 28049 Madrid (Spain)

    2007-06-10

    The knowledge of the thermal evolution of the crystal structure of a cathode material across the usual working conditions in solid oxide fuel cells is essential to understand not only its transport properties but also its chemical and mechanical stability in the working environment. In this regard, high-resolution neutron powder diffraction (NPD) measurements have been performed in air from 25 to 900 C on O{sub 2}-treated (350 C/200 bar) La{sub 2}Ni{sub 0.6}Cu{sub 0.4}O{sub 4+{delta}}. The crystal structure was Rietveld-refined in the tetragonal F4/mmm space group along all the temperature range. The structural data have been correlated with the transport properties of this layered perovskite. The electrical conductivity of O{sub 2}-treated La{sub 2}Ni{sub 0.6}Cu{sub 0.4}O{sub 4+{delta}} exhibits a metal (high T)-to-semiconductor (low T) transition as a function of temperature, displaying a maximum value of 110 S cm{sup -1} at around 450 C. The largest conductivity corresponds, microscopically, to the shortest axial Ni-O2 distance (2.29(1) Aa), revealing a major anisotropic component for the electronic transport. We have also performed a durability test at 750 C for 560 h obtaining a very stable value for the electrical conductivity of 87 S cm{sup -1}. The thermal expansion coefficient was 12.8 x 10{sup -6} K{sup -1} very close to that of the usual SOFC electrolytes. These results exhibit La{sub 2}Ni{sub 0.6}Cu{sub 0.4}O{sub 4+{delta}} as a possible alternative cathode for IT-SOFC. (author)

  4. Evaluation of the La{sub 2}Ni{sub 1} {sub -} {sub x}Cu{sub x}O{sub 4} {sub +} {sub {delta}} system as SOFC cathode material with 8YSZ and LSGM as electrolytes

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    Aguadero, A.; Escudero, M.J. [Centro de Investigaciones Energeticas Mediambientales y Tecnologicas (CIEMAT), Av. Complutense 22, 28040 Madrid (Spain); Alonso, J.A. [Instituto de Ciencia de Materiales de Madrid (CSIC),C/Sor Juana Ines de la Cruz 3, Campus Cantoblanco, 28049 Madrid (Spain); Daza, L. [Centro de Investigaciones Energeticas Mediambientales y Tecnologicas (CIEMAT), Av. Complutense 22, 28040 Madrid (Spain); Instituto de Catalisis y Petroleoquimica,(CSIC), C/Marie Curie 2, Campus Cantoblanco, 28049 Madrid (Spain)

    2008-05-31

    Materials formulated as La{sub 2}Ni{sub 1} {sub -} {sub x}Cu{sub x}O{sub 4} {sub +} {sub {delta}} (0 {<=} x {<=} 1) have been synthesised to be evaluated as possible cathode materials in SOFCs. Their crystal structures have been investigated by high-resolution neutron powder diffraction at RT so as to map out the phase diagram. The thermal expansion coefficients have been determined to be in the range of 10.8-13.0 x 10{sup -} {sup 6} K{sup -} {sup 1}. Total conductivity values are as good as 87 S cm{sup -} {sup 1} at 580 C for x = 0.4. In order to assess the performance of each oxide as cathode material, ac impedance measurements were carried out on La{sub 2}Ni{sub 1} {sub -} {sub x}Cu{sub x}O{sub 4} {sub +} {sub {delta}}/electrolyte/La{sub 2}Ni{sub 1} {sub -} {sub x}Cu{sub x}O{sub 4} {sub +} {sub {delta}} symmetrical cells with either LSGM or 8YSZ as electrolyte material. For all the electrode compositions studied, the best specific resistance (ASR) values were obtained with LSGM as electrolyte. The better performance of x = 0.4 and 0.6 (ASR {proportional_to} 1 and ohm; cm{sup 2} at 850 C) compositions has been associated with the magnitude of the total conductivity and the matching of the TEC values of the cathodes with those of the electrolytes. (author)

  5. Thermodynamics of formation reactions of intermetallides Ni/sub 3/Ta and Ni/sub 2/Ta

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    Lyakishev, N.P.; Snitko, Yu.P.; Alekseev, V.I.; Levshin, G.A. (Tsentral' nyj Nauchno-Issledovatel' skij Inst. Chernoj Metallurgii, Moscow (USSR))

    1981-01-01

    Thermodynamical functions of the formation of Ni/sub 3/Ta and Ni/sub 2/Ta intermetallides are studied when investigating the electromotive force of the cell MoVertical BarTa/sub 2/O/sub 5/, Nisub(x)Tasub(y)Vertical Bar0.99ThOsub(2)i0.01 CaOVertical Bar Fe, Fesub(0.95)OVertical BarMo in the temperature range of 1173-1323 K. Thermodynamical functions of Ni/sub 3/Ta and Ni/sub 2/Ta formation are equal to: ..delta..Gsub(f)sup(0) (1273 K) 31.70 and 28.86; ..delta..Hsub(f)sup(0) (1173-1323 K) 27.88, 07.9 kcal/mol; ..delta..Ssub(f)sup(0) (1173-1323 K) 3,U and 0.75 cal/molxdegree, respectively.

  6. Neutron powder diffraction study of the influence of high oxygen pressure treatments on La{sub 2}NiO{sub 4+{delta}} and structural analysis of La{sub 2}Ni{sub 1-x}Cu{sub x}O{sub 4+{delta}} (0|x|1)

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    Aguadero, A.; Perez, M.; Daza, L. [CIEMAT, Av. Complutense 22, E-28040 Madrid (Spain); Alonso, J.A. [Instituto de Ciencia de Materiales de Madrid (CSIC), Campus Cantoblanco, E-28049 Madrid (Spain)

    2005-10-10

    Materials formulated La{sub 2}Ni{sub 1-x}Cu{sub x}O{sub 4+{delta}} (0|x|1) have been prepared by the nitrate-citrate route, having an orthorhombic K{sub 2}NiF{sub 4} structure with Fmmm (x=0) and Bmab (0.1|x|1) space groups. La{sub 2}NiO{sub 4+{delta}}, which resulted to be the compound with the highest capability to accommodate excess oxygen ({delta}=0.16), underwent heat treatments (873-1098K) under high oxygen pressure (200-250bar). This led to an increase of excess oxygen in the structure. Rietveld refinements on neutron powder diffraction data probe the excess of oxygen to be accommodated as interstitial defect at the atomic position (1/4, 1/4, z; z{approx}1/4), which requires the displacement of four neighbouring oxygen atoms from their normal positions. This result is in agreement with a non-stoichiometry model which induces the stabilization of oxygen vacancies in the perovskite layer of these materials. The defect concentration determined from Rietveld refinement agrees well with the data obtained from thermogravimetric analysis. Results obtained herein reveal heat treatment under high oxygen pressure (873K, 200bar) as a promising method to enhance transport properties in K{sub 2}NiF{sub 4}-type structures. (author)

  7. Influence of high oxygen pressure treatments on the conductivity of La{sub 2}Ni{sub 1-x}Cu{sub x}O{sub 4+{delta}} (0 {<=} X {<=} 1)

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    Aguadero, A.; Perez, M. [CIEMAT, Madrid (Spain); Alonso, J.A. [Campus Cantoblanco, Inst. de Ciencia de Materiales de Madrid, Madrid (Spain); Daza, L. [Campus Cantoblanco, Inst. de Catalisis y Petroleoquimica, Madrid (Spain)

    2005-07-01

    The system La{sub 2}Ni{sub 1-x}Cu{sub x}O{sub 4+{delta}} (0{<=}x{<=}1) has been prepared by nitrate-citrate route, having an orthorhombic K{sub 2}NiF{sub 4} structure with Fmmm (x=0) and Bmab (0.2{<=}x{<=}1) space groups. The crystal lattice of these type of compounds can be described as a stacking of perovskite layers alternating with LaO rock salt layers. The samples for x= 0, 0.2, 0.4, 0.6 and 1 underwent heat treatments (873-1098 K) under high oxygen pressure (200-250 bar), which led to an increase of excess oxygen in the structure. Rietveld refinements on neutron powder diffraction data were used to probe the excess oxygen to be accommodated as interstitial defect at the atomic position (1/4, 1/4, z; z{approx_equal}l/4); this incorporation requires the displacement of 4 neighbouring oxygen atoms from their normal positions. This result is in agreement with a non-stoichiometry model which induces the stabilization of oxygen vacancies in the perovskite layer of the structure. In these materials, ionic conductivity can be explained by the movement of interstitial and vacant defects in the LaO rock salt and perovskite layers, respectively. It is observed that, after oxygen treatments, there is an increase of the isotropic thermal factors associated to the oxygen atoms involved in the conduction mechanism. On the other hand, conductivity measurements by the four probe method showed samples to reach values up to 120 S/cm. This result is outstanding in view of application of these materials as SOFC cathodes. (au)

  8. Characterization and evaluation of La{sub 0.8} Sr{sub 0.2}Co{sub 0.8} Ni{sub 0.2}O{sub 3-{delta}} prepared by a polymer-assisted combustion synthesis as a cathode material for intermediate temperature solid oxide fuel cells

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    Chen, Jing; Liang, Fengli; Liu, Lina; Jian, Li [School of Materials Science and Engineering, State Key Laboratory of Material Processing and Die and Mould Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Jiang, San Ping [School of Mechanical and Aerospace Engineering, Nanyang Technological University (Singapore)

    2009-08-15

    A modified polymer-assisted combustion synthesis method is developed for preparation of La{sub 0.8}Sr{sub 0.2}Co{sub 0.8}Ni{sub 0.2}O{sub 3-{delta}} (LSCN) nano-sized cathode particles by using organic additives (glucose and acrylamide) and metal nitrates. The effect of the organic additives, pH value of starting solution and calcination temperature on the formation of the LSCN perovskite phase and microstructure of the powders is investigated. Chemical compatibility between the LSCN and Y{sub 2}O{sub 3} stabilized ZrO{sub 2} (YSZ) and Gd{sub 2}O{sub 3} doped CeO{sub 2} (GDC) is evaluated and electrochemical activity of LSCN cathode is evaluated. The prepared LSCN is chemically compatible with the YSZ only at temperatures below 850 C. The electrode area specific resistance (ASR) is 0.30 and 0.10 {omega} cm{sup 2} at 700 and 750 C, respectively. These results suggest that such prepared LSCN is a promising alternative cathode material for intermediate temperature SOFCs. (author)

  9. Ni{sub 3}Al aluminide alloys

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    Liu, C.T.

    1993-10-01

    This paper provides a brief review of the recent progress in research and development of Ni{sub 3}Al and its alloys. Emphasis has been placed on understanding low ductility and brittle fracture of Ni{sub 3}Al alloys at ambient and elevated temperatures. Recent studies have resulted in identifying both intrinsic and extrinsic factors governing the fracture behavior of Ni{sub 3}Al alloys. Parallel efforts on alloy design using physical metallurgy principles have led to properties for structural use. Industrial interest in these alloys is high, and examples of industrial involvement in processing and utilization of these alloys are briefly mentioned.

  10. Ni{sub 3}Al technology transfer

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    Sikka, V.K.; Viswanathan, S.; Santella, M.L. [Oak Ridge National Lab., TN (United States)] [and others

    1997-04-01

    Ductile Ni{sub 3}Al and Ni{sub 3}Al-based alloys have been identified for a range of applications. These applications require the use of material in a variety of product forms such as sheet, plate, bar, wire, tubing, piping, and castings. Although significant progress has been made in the melting, casting, and near-net-shape forming of nickel aluminides, some issues still remain. These include the need for: (1) high-strength castable composition for many applications that have been identified; (2) castability (mold type, fluidity, hot-shortness, porosity, etc.); (3) weld reparability of castings; and (4) workability of cast or powder metallurgy product to sheet, bar, and wire. The four issues listed above can be {open_quotes}show stoppers{close_quotes} for the commercial application of nickel aluminides. This report describes the work completed to address some of these issues during FY 1996.

  11. Ni{sub 3}Al technology transfer

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    Sikka, V.K.; Santella, M.L.; Alexander, D.J. [Oak Ridge National Laboratory, TN (United States)] [and others

    1995-05-01

    Ductile Ni{sub 3}Al and Ni{sub 3}Al-based alloys have been identified for a range of applications. These applications require the use of material in a variety of product forms such as sheet, plate, bar, tubing, piping, and castings. Although significant progress has been made in the melting, casting, and near-net-shape forming of nickel aluminides, some issues still remain. These include the need for (1)high-strength castable composition for turbochargers, furnace furniture, and hot-die applications; (2) castability (fluidity, hot-shortness, porosity, etc.); (3) weld reparability of castings; and (4) hot fabricability of cast ingots. All of the issues listed above can be {open_quotes}show stoppers{close_quotes} for the commercial application of nickel aluminides. This report describes work completed to address some of these issues during the fourth quarter of FY 1994.

  12. Stress-induced Curie temperature increase in the Fe{sub 64}Ni{sub 36} invar alloy

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    Gorria, Pedro; Martinez-Blanco, David; Blanco, Jesus A. [Departamento de Fisica, Universidad de Oviedo (Spain); Boada, Roberto; Chaboy, Jesus [ICMA and Departamento de Fisica de la Materia Condensada, CSIC - Universidad de Zaragoza (Spain); Fernandez-Martinez, Alejandro [LGIT, University of Grenoble and CNRS, Maison des Geosciences, Grenoble (France); Institut Laue-Langevin, Grenoble (France); Garbarino, Gaston; Castro, German R.; Mezouar, Mohamed [European Synchrotron Radiation Facility (ESRF), Grenoble (France); Smith, Ronald I. [ISIS Facility, RAL, Chilton, Didcot, Oxon (United Kingdom); Alonso, J.I.G. [Department of Physical and Analytical Chemistry, University of Oviedo (Spain); Hernando, Antonio [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, Madrid (Spain)

    2009-05-15

    Structural and magnetic changes on invar Fe{sub 64}Ni{sub 36} alloy (T{sub C}=500 K) produced by mechanical milling followed by heating up to 1073 K, were investigated by neutron diffraction, magnetization measurements, X-ray diffraction under high pressures and X-ray absorption at both Fe and Ni K-edges. We argue that the strain induced in the Fe{sub 64}Ni{sub 36} material after this treatment mainly affects the Fe sites due to the magnetovolume coupling, the most notorious feature being the increase of the Curie temperature ({delta}T{sub C}=70 K). (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Lattice structure transformation and change in surface hardness of Ni{sub 3}Nb and Ni{sub 3}Ta intermetallic compounds induced by energetic ion beam irradiation

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    Kojima, H., E-mail: sv110021@edu.osakafu-u.ac.jp [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Yoshizaki, H.; Kaneno, Y. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Semboshi, S. [Materials Research Institute (Kansai Center), Tohoku University, Sakai, Osaka 599-8531 (Japan); Hori, F. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Saitoh, Y. [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan); Okamoto, Y. [Quantum Beam Science Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Iwase, A. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan)

    2016-04-01

    Ni{sub 3}Nb and Ni{sub 3}Ta intermetallic compounds, which show the complicated lattice structures were irradiated with 16 MeV Au{sup 5+} ions at room temperature. The X-ray diffraction measurement revealed that the lattice structure of these intermetallic compounds changed from the ordered structures to the amorphous state by the ion irradiation. The irradiation-induced amorphization caused the increase in Vickers hardness. The result was compared with our previous results for Ni{sub 3}Al and Ni{sub 3}V, and was discussed in terms of the intrinsic lattice structures of the samples.

  14. Epitaxial Ni{sub 3}FeN thin films: A candidate for spintronic devices and magnetic sensors

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    Loloee, Reza [Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (United States)

    2012-07-15

    A new type of epitaxial ferromagnetic nitride (Ni{sub 3} Fe N = permalloy nitride = 'PyN') compound films were grown on Al{sub 2}O{sub 3}(1120) substrates using reactive triode magnetron sputtering. The results of electron back-scattering diffraction and x-ray diffraction techniques indicate a high quality epitaxial crystalline structure with growth normal of (100). Magnetization measurements of epitaxial PyN films revealed several unique results. (1) A textbook square hysteresis loop that suggest existence of single magnetic domain in these films. (2) A coercive field is tunable from a few mOe up to a few Oe by changing the film thickness. (3) A magnetization that switches (rotate) over a very small field range of {delta}H{sub C} {<=} 0.05 Oe, independent of the film thickness. This small {delta}H indicates a very large resistive sensitivity ({delta}R/{delta}H) of the epitaxial PyN. (4) The epitaxial PyN thermal cycling through several cycles between '2 and 800 K' (-271 Degree-Sign C to +527 Degree-Sign C) shows much less degradation only about 2-5% compared to 40% degradation of a simple Py film. Four-probe transport measurements give an anisotropic magnetoresistance of Almost-Equal-To 6%, sufficiently higher than other known ferromagnetic materials. These interesting properties are ideal for a variety of spintronic devices and magnetic sensors.

  15. Investigation of the magnetic properties of Ni{sub 0.7}Fe{sub 0.3}Ga{sub 2}S{sub 4}

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    Myoung, Bo Ra; Kim, Sam Jin; Kim, Chul Sung [Kookmin University, Seoul (Korea, Republic of)

    2010-03-15

    We have studied the magnetic properties of Ni{sub 0.7}Fe{sub 0.3}Ga{sub 2}S{sub 4} with Fe substituted at the Ni sites by using an X-ray diffractometer (XRD), a superconducting quantum interference device (SQUID)magnetometer, and a Moessbauer spectrometer. The polycrystalline sample of Ni{sub 0.7}Fe{sub 0.3}Ga{sub 2}S{sub 4} is found to be a single phase of the trigonal structure with a space group of P -3m1. The structural parameters of the sample are obtained by using a Reitveld refinement with lattice constants of a{sub 0} = 3.640 A and c{sub 0} = 12.020 A. The bond length between Fe and S ions is about 2.420 A, which suggests a short-range ordering with the frustration effect. From the Moessbauer spectra, the magnetic hyperfine field and the electric quadrupole interaction are estimated to be H{sub hf} = 124.2 kOe, and {Delta}E{sub Q} = 2.10 mm/s, respectively, at 4.2 K. The charge state of the Fe ions is ferrous (Fe{sup 2+}) from the value of the isomer shift, {delta} = 0.66 mm/s, at room temperature. The spin quantum number of Ni{sub 0.7}Fe{sub 0.3}Ga{sub 2}S{sub 4} is determined to be S = 3/2, while it is S = 1 for NiGa{sub 2}S{sub 4} and S = 2 for FeGa{sub 2}S{sub 4}. This indicates an increase an spin-orbital interactions with increasing Fe.

  16. Hydride stability and band structure of the components in the Pdsub(1-x)Msub(x) and LaNisub(5-x)Msub(x) systems

    Energy Technology Data Exchange (ETDEWEB)

    Bucur, R.V.; Lupu, D.

    1983-04-01

    The stability of the metal hydrides of Pdsub(1-x)Msub(x) (MidenticalAu, Ag, Pt, Ir, Rh, V, Cu and Ni) and LaNisub(5-x)Msub(x) (MidenticalPt, Pd, Ag, Fe, Cu, Co and Cr) systems depends strongly on the nature of the substituent M. The change ..delta..G in free energy on the formation or decomposition of the metal hydrides depends linearly on the average energy of the lowest band of the substituent (transition metal) and on its concentration x. This linear correlation can be expressed by the empirical equation ..delta..G=..delta..Gsub(A)+a(-)x where ..delta..Gsub(A) is the change in free energy on hydride formation (decomposition) in the pure metal or the intermetallic compound, a is a constant and is the average energy of the lowest band of the component able to bond hydrogen. The dependence of ..delta..G on the band structure of the components (transition metals) is discussed within the framework of the metal-hydrogen bonding mechanism in metal hydrides.

  17. Observational $\\Delta\

    CERN Document Server

    Hernández, Antonio García; Monteiro, Mário J P F G; Suárez, Juan Carlos; Reese, Daniel R; Pascual-Granado, Javier; Garrido, Rafael

    2015-01-01

    Delta Scuti ($\\delta$ Sct) stars are intermediate-mass pulsators, whose intrinsic oscillations have been studied for decades. However, modelling their pulsations remains a real theoretical challenge, thereby even hampering the precise determination of global stellar parameters. In this work, we used space photometry observations of eclipsing binaries with a $\\delta$ Sct component to obtain reliable physical parameters and oscillation frequencies. Using that information, we derived an observational scaling relation between the stellar mean density and a frequency pattern in the oscillation spectrum. This pattern is analogous to the solar-like large separation but in the low order regime. We also show that this relation is independent of the rotation rate. These findings open the possibility of accurately characterizing this type of pulsator and validate the frequency pattern as a new observable for $\\delta$ Sct stars.

  18. Ni{sub 4} and Ni{sub 3}Ga clusters as building units in Ca{sub 3}Ni{sub 4}Ga{sub 4} and Sr{sub 3}Ni{sub 3}□Ga{sub 4}

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    Seidel, Stefan; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2016-08-01

    The gallides Ca{sub 3}Ni{sub 4}Ga{sub 4} and Sr{sub 3}Ni{sub 3}Ga{sub 4} were synthesized from arc-melted Ni{sub x}Ga{sub y} precursor alloys and the respective alkaline earth metal in sealed niobium tubes in an induction furnace. Redetermination of the Ca{sub 3}Ni{sub 4}Ga{sub 4} structure from X-ray single crystal diffractometer data confirmed the X-ray powder data: Na{sub 3}Pt{sub 4}Ge{sub 4} type, I anti 43m, a=740.6(1) pm, wR2=0.0245, 169 F{sup 2} values, 9 variables. The nickel atoms build tetrahedral Ni{sub 4} clusters (256 pm Ni-Ni) that are end-on coordinated by gallium atoms (234 pm Ni-Ga). These [Ni{sub 4}Ga{sub 4}] units show a bcc packing and leave cavities Ca rate at Ga{sub 4}Ni{sub 4}Ga{sub 4} for the calcium atoms. Sr{sub 3}Ni{sub 3}Ga{sub 4} crystallizes with a new structure type: R3m, a=1039.8(2), c=698.2(1) pm, wR2=0.1048, 636 F{sup 2} values, 23 variables. The structure shows twinning by inversion with a domain ratio of 79/21. The structures of Sr{sub 3}Ni{sub 3}Ga{sub 4} and Ca{sub 3}Ni{sub 4}Ga{sub 4} are related by a group-subgroup scheme (R3m is a translationengleiche subgroup of I anti 43m). The 8c Ni and Ga subcell sites split into site 3a and 9b each. This allows formation of ordered Ni{sub 3}Ga tetrahedra (264 pm Ni-Ga) along with ordered gallium vacancies.

  19. Grain boundary structure in Ni{sub 3}Al

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, D. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Materials Engineering

    1996-08-01

    The multiplicity of possible grain boundary structures was studied for the ordered compound Ni{sub 3}Al. Two symmetrical tilt boundaries were chosen for the detailed study corresponding to {Sigma}=3 left angle 110 right angle {l_brace}112{r_brace} and {Sigma}=9 left angle 110 right angle {l_brace}114{r_brace}. These boundaries were investigated considering possible variations of the local chemical composition and environment using atomistic computer simulation with EAM interatomic potentials. Many different grain boundary structures were found having very similar energies for the same orientation of the two crystals and the grain boundary plane. Possible transformations among these structures may result from the interaction of the boundaries with dislocations or antiphase boundaries. The role of the multiplicity of structures and these transformations in the grain boundary mechanical properties is discussed. In this paper, we explore the role that different possible grain boundary structures play in intermetallic alloys. (orig.)

  20. Delta robot

    NARCIS (Netherlands)

    Herder, J.L.; Van der Wijk, V.

    2010-01-01

    The invention relates to a delta robot comprising a stationary base (2) and a movable platform (3) that is connected to the base with three chains of links (4,5,6), and comprising a balancing system incorporating at least one pantograph (7) for balancing the robot's center of mass, wherein the at le

  1. Delta robot

    NARCIS (Netherlands)

    Herder, J.L.; Van der Wijk, V.

    2010-01-01

    The invention relates to a delta robot comprising a stationary base (2) and a movable platform (3) that is connected to the base with three chains of links (4,5,6), and comprising a balancing system incorporating at least one pantograph (7) for balancing the robot's center of mass, wherein the at le

  2. Kinetic and thermodynamics studies on the decompositions of Ni{sub 3}C in different atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Leng Yonghua; Xie Lei; Liao Fuhui; Zheng Jie [Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Li Xingguo [Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); College of Engineering, Peking University, Beijing 100871 (China)], E-mail: xgli@pku.edu.cn

    2008-07-10

    The thermal decompositions (including TG and DSC) of nickel carbide were studied under different atmospheres of Ar, air and H{sub 2}. X-ray diffraction combined with element analysis indicated that nickel metal, together with solid amorphous carbon, was formed during Ni{sub 3}C decomposition in Ar atmosphere, accompanying mass invariant in this process. While in H{sub 2} atmosphere nickel metal was the only residual from reactions. The carbon component of nickel carbide reacted with H{sub 2} to form methane as the main volatile gases. Both the nickel and carbon components of Ni{sub 3}C reacted with O{sub 2} in the air to form their corresponding oxides. Moreover, we calculated the activation energy for the decomposition process and the molar enthalpy of formation of Ni{sub 3}C based on the thermal analysis.

  3. Commercialization status of Ni{sub 3}Al-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-12-31

    The Ni{sub 3}Al-based alloys have been under development at the Oak Ridge National Laboratory (ORNL) and other research institutions in the United States and around the world for the last ten years. The incremental developments of composition, melting process, casting methods, property data, corrosion data, weldability development, and prototype component testing under production-like operating conditions have pushed the ORNL-developed Ni{sub 3}Al-based alloys closer to commercialization. This paper will present the highlights of incremental technical developments along with the approach and current status of commercialization. It is concluded that cast components are the primary applications of Ni{sub 3}Al-based alloys, and applications range from heat-treating fixtures of forging dies. It is also concluded that the commercialization process is accelerated when technology is licensed to an organization that can produce the alloy, has component manufacturing capability, and is also a user.

  4. The crystal structures of Ni{sub 3+x}Sn{sub 4}Zn and Ni{sub 6+x}Sn{sub 8}Zn and their structural relations to Ni{sub 3+x}Sn{sub 4}, NiSn and Ni{sub 5−δ}ZnSn{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Schmetterer, Clemens, E-mail: clemens.schmetterer@univie.ac.at [University of Vienna, Dep. Inorganic Chemistry/Materials Chemistry, Währingerstraße 42, 1090 Wien (Austria); Effenberger, Herta Silvia [University of Vienna, Institut für Mineralogie und Kristallographie, Althanstrasse 14, 1090 Wien (Austria); Rajamohan, Divakar; Flandorfer, Hans [University of Vienna, Dep. Inorganic Chemistry/Materials Chemistry, Währingerstraße 42, 1090 Wien (Austria)

    2016-06-15

    The crystal structures of two new compounds were determined from single-crystal X-ray diffraction measurements: Ni{sub 3+x}Sn{sub 4}Zn, (x~1.35, a=7.110(2) Å, b=4.123(1) Å, c=10.346(3) Å, β=90.23(2)°, space group I2/m, Z=2. R1=0.025, wR2=0.059 for 748 unique reflections, 35 variable parameters) and Ni{sub 6+x}Sn{sub 8}Zn, x~1.35 (a=12.379(3) Å, b=4.095(1) Å, c=12.155(3) Å, β=116.25(3)°, space group C2/m, Z=2. R1=0.026, wR2=0.052 for 1346 unique reflections, 60 variable parameters). In addition, a structural refinement was performed for Ni{sub 3+x}Sn{sub 4}, x~0.13 (a=12.264(3) Å, b=4.066(1) Å, c=5.223(2) Å, β=104.85(3)°, space group C2/m, Z=2. R1=0.019, wR2=0.046 for 617 unique reflections, 29 variable parameters). The three compounds show pronounced similarities among each other as well as to the crystal structures of surrounding binary Ni–Sn and ternary Ni–Sn–Zn compounds. In particular, the two new compounds form a homologous series with Ni{sub 3+x}Sn{sub 4}, x~0.13. They contain “Ni{sub 4}Sn{sub 4}” and “Ni{sub 2}Sn{sub 4}” building blocks which by different interconnection build up the distinct structures. Topological relations with NiSn and Ni{sub 5−δ}Sn{sub 4}Zn, δ~0.25 are evident. - Graphical abstract: Projection of the structure of Ni{sub 6+x}ZnSn{sub 8}, x~1.35 and constituent building blocks. Display Omitted - Highlights: • The crystal structures of Ni{sub 6+x}Sn{sub 8}Zn and Ni{sub 3+x}Sn{sub 4}Zn were determined using single crystal XRD. • Topological relations to Ni–Sn and Ni–Sn–Zn compounds were established and discussed. • Common structural units were identified and their interconnection patterns described.

  5. The effect of pH on the corrosion behavior of intermetallic compounds Ni{sub 3}(Si,Ti) and Ni{sub 3}(Si,Ti) + 2Mo in sodium chloride solutions

    Energy Technology Data Exchange (ETDEWEB)

    Priyotomo, Gadang, E-mail: gada001@lipi.go.id; Nuraini, Lutviasari, E-mail: Lutviasari@gmail.com [Research Center for Metallurgy and Material, Indonesian Institute of Sciences, Kawasan PUSPIPTEK Gd.474, Setu, Tangerang Selatan, Banten 15314 (Indonesia); Kaneno, Yasuyuki, E-mail: kaneno@mtr.osakafu-u.ac.id [Department of Materials Science, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531 (Japan)

    2015-12-29

    The corrosion behavior of the intermetallic compounds, Ni{sub 3}(Si,Ti) (L1{sub 2}: single phase) and Ni{sub 3}(Si,Ti) + 2Mo (L1{sub 2} and (L12 + Ni{sub ss}) mixture region), has been investigated using an immersion test, electrochemical method and surface analytical method (SEM; scanning electron microscope and EDAX: Energy Dispersive X-ray) in 0.5 kmol/m{sup 3} NaCl solutions at various pH. The corrosion behavior of nickel alloy C-276 was studied under the same experimental conditions as a reference. It was found that the uniform attack was observed on Ni{sub 3}(Si,Ti) for the immersion test at lower pH, while the pitting attack was observed on this compound for this test at neutral solution. Furthermore, Ni{sub 3}(Si,Ti)+2Mo had the preferential dissolution of L1{sub 2} compared to (L1{sub 2} + Ni{sub ss}) mixture region at lower pH, while pitting attack occurred in (L1{sub 2} + Ni{sub ss}) mixture region at neutral solution. For both intermetallic compounds, the magnitude of pitting and uniform attack decrease with increasing pH of solutions. From the immersion test and polarization curves, the corrosion resistance of Ni{sub 3}(Si,Ti)+2Mo is lower than that of Ni{sub 3}(Si,Ti), while the nickel alloy C-276 is the highest one at various pH of solutions. On the other hand, in the lower pH of solutions, the corrosion resistance of tested materials decreased significantly compared to those in neutral and higher pH of solutions.

  6. Electronic circuits having NiAl and Ni.sub.3 Al substrates

    Energy Technology Data Exchange (ETDEWEB)

    Deevi, Seetharama C. (Midlothian, VA); Sikka, Vinod K. (Oak Ridge, TN)

    1999-01-01

    An electronic circuit component having improved mechanical properties and thermal conductivity comprises NiAl and/or Ni.sub.3 Al, upon which an alumina layer is formed prior to applying the conductive elements. Additional layers of copper-aluminum alloy or copper further improve mechanical strength and thermal conductivity.

  7. Electronic circuits having NiAl and Ni{sub 3}Al substrates

    Energy Technology Data Exchange (ETDEWEB)

    Deevi, S.C.; Sikka, V.K.

    1999-10-12

    An electronic circuit component having improved mechanical properties and thermal conductivity comprises NiAl and/or Ni{sub 3}Al, upon which an alumina layer is formed prior to applying the conductive elements. Additional layers of copper-aluminum alloy or copper further improve mechanical strength and thermal conductivity.

  8. Electronic circuits having NiAl and Ni.sub.3 Al substrates

    Science.gov (United States)

    Deevi, Seetharama C.; Sikka, Vinod K.

    1999-01-01

    An electronic circuit component having improved mechanical properties and thermal conductivity comprises NiAl and/or Ni.sub.3 Al, upon which an alumina layer is formed prior to applying the conductive elements. Additional layers of copper-aluminum alloy or copper further improve mechanical strength and thermal conductivity.

  9. Positron annihilation process in Ni/sub c/Cu/sub 1-c/ alloys

    Energy Technology Data Exchange (ETDEWEB)

    Szotek, Z.; Gyorffy, B.L.; Stocks, G.M.; Temmerman, W.M.

    1982-01-01

    New, accurate, calculations of the electron momentum distribution function for the Cu/sub 60/Ni/sub 40/ random solid solution are presented and the role played by the positron wavefunction in determining the Angular Correlation of the Annihilation Radiation (ACAR) is discussed in quantitative terms.

  10. Structural and electrical properties of Ni{sub 1-x}Mg{sub x}Fe{sub 2}O{sub 4} synthesized by citrate gel process

    Energy Technology Data Exchange (ETDEWEB)

    John Berchmans, L.; Kalai Selvan, R.; Selva Kumar, P.N.; Augustin, C.O. E-mail: caugustin@rediffmail.com

    2004-08-01

    The structural and electrical properties of magnesium-substituted nickel ferrite having the general formula of Ni{sub 1-x}Mg{sub x}Fe{sub 2}O{sub 4} (x=0, 0.3, 0.6, 0.9) has been studied as a function of magnesium ion concentration. The materials have been prepared by citrate gel process using metal nitrate salts as a cation precursors and citric acid as gelating agent. The powder X-ray diffraction pattern confirms fcc structure for the synthesized compound. The variation of lattice parameter and the tetrahedral radius increases with increase in Mg{sup 2+} ion concentration. The AC electrical parameters such as dielectric constant ({epsilon}') and loss tangent (tan {delta}) for all the systems have been studied as a function of frequency in the range 50 Hz to 10 kHz at room temperature. A maximum DC electrical conductivity of 3.3 S cm{sup -1} was obtained at a temperature of 1000 deg. C and a AC electrical conductivity of 10.94x10{sup -6}at 10 kHz was observed in the composition x=0.6 i.e. for Ni{sub 0.4}Mg{sub 0.6}Fe{sub 2}O{sub 4} compound which may be due to the maximum Fe{sup 2+} concentration in the octahedral sites. The dielectric constant follows the Maxwell's-Wagner interfacial polarization and the relaxation peaks were observed in the dielectric loss properties. The FTIR spectra show the characteristic peaks of ferrite sample. The morphological features were studied using scanning electron microscope.

  11. Mo{sub 2}NiB{sub 2}-type (Gd, Tb, Dy){sub 2}Ni{sub 2.35}Si{sub 0.65} and La{sub 2}Ni{sub 3}-type (Dy, Ho){sub 2}Ni{sub 2.5}Si{sub 0.5} compounds: Crystal structure and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Morozkin, A.V., E-mail: morozkin@tech.chem.msu.ru [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, Moscow 119992, GSP-2 (Russian Federation); Isnard, O. [CNRS, Insitut. Néel, 25 rue des Martyrs BP166, F-38042 Grenoble (France); Université Grenoble Alpes, Inst. Néel, F-38042 Grenoble (France); Nirmala, R. [Indian Institute of Technology Madras, Chennai 600 036 (India); Malik, S.K. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59082-970 (Brazil)

    2015-05-15

    The crystal structure of new Mo{sub 2}NiB{sub 2}-type (Gd, Tb, Dy){sub 2}Ni{sub 2.35}Si{sub 0.65} (Immm, No. 71, oI10) and La{sub 2}Ni{sub 3}-type (Dy, Ho){sub 2}Ni{sub 2.5}Si{sub 0.5} (Cmce No. 64, oC20) compounds has been established using powder X-ray diffraction studies. Magnetization measurements show that the Mo{sub 2}NiB{sub 2}-type Gd{sub 2}Ni{sub 2.35}Si{sub 0.65} undergoes a ferromagnetic transition at ~66 K, whereas isostructural Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} shows an antiferromagnetic transition at ~52 K and a field-induced metamagnetic transition at low temperatures. Neutron diffraction study shows that, in zero applied field, Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} exhibits c-axis antiferromagnetic order with propagation vector K=[1/2, 0, 1/2] below its magnetic ordering temperature and Tb magnetic moment reaches a value of 8.32(5) μ{sub B} at 2 K. The La{sub 2}Ni{sub 3}-type Dy{sub 2}Ni{sub 2.5}Si{sub 0.5} exhibits ferromagnetic like transition at ~42 K with coexisting antiferromagnetic interactions and field induced metamagnetic transition below ~17 K. The magnetocaloric effect of Gd{sub 2}Ni{sub 2.35}Si{sub 0.65}, Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} and Dy{sub 2}Ni{sub 2.5}Si{sub 0.5} is calculated in terms of isothermal magnetic entropy change and it reaches a maximum value of −14.3 J/kg K, −5.3 J/kg K and −10.3 J/kg K for a field change of 50 kOe near 66 K, 52 K and 42 K, respectively. Low temperature magnetic ordering with enhanced anisotropic effects in Tb{sub 2}Ni{sub 2.35}Si{sub 0.65} and Dy{sub 2}Ni{sub 2.35}Si{sub 0.65} is accompanied by a positive magnetocaloric effect with isothermal magnetic entropy changes of +12.8 J/kg K and ~+9.9 J/kg K, respectively at 7 K for a field change of 50 kOe. - Graphical abstract: The (Gd, Tb, Dy){sub 2}Ni{sub 2.35}Si{sub 0.65} supplement the series of Mo{sub 2}NiB{sub 2}-type rare earth compounds, whereas the (Dy, Ho){sub 2}Ni{sub 2.5}Si{sub 0.5} supplement the series of La{sub 2}Ni{sub 3}-type rare

  12. Delta III—an evolutionary delta growth

    Science.gov (United States)

    Arvesen, R. J.; Simpson, J. S.

    1996-03-01

    In order to remain competitive in the future and expand the McDonnell Douglas Aerospace market share, MDA has developed an expendable launch system strategy that devices cost-effective launch systems from the Delta II with a growth vehicle configuration called Delta III. The Delta III evolves from the Delta II launch system through development of a larger payload fairing (4-meter diameter), new cryogenically propelled upper stage, new first stage fuel tank, and larger strap-on solid rocket motors. We are developing the Delta III using Integrated Product Development Teams that capitalize on the experience base that has led us to a world record breaking mission success of 49 consecutive Delta II missions. The Delta III first-launch capability is currently planned for the spring of 1998 in support of our first spacecraft customer, Hughes Space and Communications International.

  13. Precipitation of coherent Ni{sub 2}(Cr, W) superlattice in an Ni–Cr–W superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Xiangyu; Hu, Rui, E-mail: rhu@nwpu.edu.cn; Zhang, Tiebang; Li, Jinshan; Yuan, Liang; Kong, Jintao

    2016-01-15

    It is demonstrated that a nanometer-sized Ni{sub 2}(Cr, W) superlattice with a Pt{sub 2}Mo-type structure can precipitate in an Ni–Cr–W alloy by means of a simple aging treatment at 550 °C. The dark-field image of short-range order domains has been found for the first time experimentally. The mechanism of short-range order to long-range order transformation has been revealed based on transmission electron microscopy result and static concentration waves theory and found to be continuous ordering. The randomness of the transformation of static concentration waves leads to equiprobable occurrence of the different variants. The transformation of short-range order to long-range order gives rise to the Pt{sub 2}Mo-type Ni{sub 2}(Cr, W) superlattice. The interfaces between Ni{sub 2}(Cr, W) and Ni-based matrix and the different variants of Ni{sub 2}(Cr, W) have been investigated by high resolution transmission electron microscopy. The results reveal that the interfaces between Ni{sub 2}(Cr, W) and surrounding matrix are coherent at the atomic scale. - Highlights: • The DF image of SRO cluster has been found for the first time experimentally. • The transformation of SRO to LRO gives rise to the Pt{sub 2}Mo-type Ni{sub 2}(Cr, W). • Variants of Ni{sub 2}(Cr, W) occur equiprobably. • The interfaces between Ni{sub 2}(Cr, W) and matrix are coherent at the atomic scale.

  14. The Delta 2 launcher

    Science.gov (United States)

    Ousley, Gilbert W., Sr.

    1991-12-01

    The utilization of the Delta 2 as the vehicle for launching Aristoteles into its near Sun synchronous orbit is addressed. Delta is NASA's most reliable launch vehicle and is well suited for placing the present Aristoteles spacecraft into a 400 m circular orbit. A summary of some of the Delta 2 flight parameters is presented. Diagrams of a typical Delta 2 two stage separation are included along with statistics on delta reliability and launch plans.

  15. Experimental evidence of temperature path independence in the polycrystalline alloy Ni{sub 3}Al

    Energy Technology Data Exchange (ETDEWEB)

    Webb, G.; Antolovich, S.D. [Washington State Univ., Pullman, WA (United States). School of Mechanical and Materials Engineering

    1995-10-01

    The results from a series of elevated temperature prestrain experiments on a hypostoichiometric polycrystalline Ni{sub 3}Al are presented. Experiments were conducted to examine the deformation characteristic of thermal reversibility or temperature path history independence (TPHI). Temperature path history independence was experimentally observed from prestraining experiments (also known as Cottrell-Stokes experiments) in which the specimen was deformed at different temperatures; the results were compared to those obtained from tests conducted at constant temperature. The purpose of such experiments was to macroscopically evaluate the effects of intrinsic dislocation mobility and dislocation substructure on deformation. These experiments provide a framework in which to evaluate fundamental characteristics of thermally activated deformation processes. The results for polycrystalline Ni{sub 3}Al alloys indicate that the mechanisms responsible for thermal strengthening is independent of prior deformation history. This observation implies that the mechanism of anomalous strengthening in such alloys is fully reversible and independent of the development of a dislocation substructure.

  16. Premartensite transition in Ni{sub 2}FeGa Heusler alloy

    Energy Technology Data Exchange (ETDEWEB)

    Nath, Hrusikesh, E-mail: hrushikesh.nath@gmail.com [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Department of Technology of Metals and Aviation Materials Science, Samara State Aerospace University, Samara 443086 (Russian Federation); Phanikumar, G., E-mail: gphani@iitm.ac.in [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036 (India)

    2015-04-15

    Martensitic phase transformation of Ni{sub 2}FeGa Heusler alloy was studied by differential scanning calorimetry. Atomic ordering induced in the austenite structure by quenching from high temperature plays a significant role on martensitic phase transformation. Higher magnetization and larger magneto-crystalline anisotropy of martensite phase than that of austenite phase are noticed. Tweed contrast regions observed in the transmission electron microscopy were correlated to premartensite phenomena. A shift in premartensitic transition temperature prior to martensitic transformation as measured by differential scanning calorimetry is being reported for the first time in this system. - Highlights: • Atomic ordering influences martensitic transformation in Ni{sub 2}FeGa Heusler alloy. • Observation of tweed contrast in TEM was correlated to premartensite phenomena. • For the first time the shift in premartensite peak was observed in DSC.

  17. Electrodeposition and characteristics of Ni{sub 80}Fe{sub 20}/Cu composite wires

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.P. [Department of Mechanical Engineering, National University of Singapore, Singapore 119260 (Singapore) and Division of Bioengineering, National University of Singapore, Singapore 119260 (Singapore)]. E-mail: mpelixp@nus.edu.sg; Seet, H.L. [Department of Mechanical Engineering, National University of Singapore, Singapore 119260 (Singapore); Fan, J. [Department of Mechanical Engineering, National University of Singapore, Singapore 119260 (Singapore); Yi, J.B. [Department of Mechanical Engineering, National University of Singapore, Singapore 119260 (Singapore)

    2006-09-15

    Electrodeposited Ni{sub 80}Fe{sub 20}/Cu composite wire has significant advantages over amorphous wire as sensing element for weak magnetic field sensors, such as orthogonal fluxgate sensors, due to its non-ferromagnetic and conductive core structure. In this study, the key processing parameters are investigated, including electrodeposition current density, duty cycle, electrolyte solution, pH value, applied magnetic field, effect of seeded layers, and post annealing.

  18. Microstructural characterisation of Ni{sub 75}Al{sub 25} and Ni{sub 31.5}Al{sub 68.5} powder particles produced by gas atomisation

    Energy Technology Data Exchange (ETDEWEB)

    García-Escorial, A., E-mail: age@cenim.csic.es [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Lieblich, M. [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain)

    2014-02-15

    Highlight: ► Successful production of gas atomised Ni75Al25 and Ni31.5Al68.5 powder particles. ► Characterization of the as-solidified microstructure of < 100 mm powder particles. ► Complementing work carried out in the by magnetic levitation and impulse atomization. -- Abstract: In this work the microstructures of gas atomised Ni{sub 75}Al{sub 25} and Ni{sub 31.5}Al{sub 68.5} at.% powder particles below 100 μm in size have been studied. The gas atomised Ni{sub 75}Al{sub 25} powder particles are mainly spherical. The solidification of this alloy is very fast, and its microstructure consists of a dendrite and lamellar structure of partially ordered γ-(Ni), γ′-Ni{sub 3}Al L1{sub 2} phase, and β-NiAl phase. The order increases with the powder particle size. The gas atomised Ni{sub 31.5}Al{sub 68.5} powder particles are also spherical in shape. The microstructure consists of Ni{sub 2}Al{sub 3} dendrites with interdendritic peritectic NiAl{sub 3} and eutectic NiAl{sub 3} + α-Al. The amount of the Ni{sub 2}Al{sub 3} increases as the cooling rate increases. NiAl phase is absent in the gas atomised Ni{sub 31.5}Al{sub 68.5} powder.

  19. High-performance Ni[sub 3]Al synthesized from composite powders

    Energy Technology Data Exchange (ETDEWEB)

    Chiou, W.C.; Hu, C.T. (National Tsing Hua Univ., Hsinchu (Taiwan, Province of China). Dept. of Materials Science and Engineering)

    1994-05-01

    Specimens of Ni[sub 3]Al + B of high density (>99.3 pct RD) and relatively large dimension have been synthesized from composite powders through processes of replacing plating and electroless Ni-B plating on Al powder, sintering, and thermal-mechanical treatment. The uniformly coated Ni layer over fine Al or Ni core particles constituting these coating/core composite powders has advantages such as better resistance to oxidation relative to pure Al powder, a greater green density as a compacted powder than prealloyed powder, the possibility of atomically added B to the material by careful choice of a suitable plating solution, and avoidance of the expensive powder metallurgy (PM) equipment such as a hot isostatic press (HIP), hot press (HP), etc. The final Ni[sub 3]Al + B product is made from Ni-B-Al and Ni-B-Ni mixed composite powders by means of traditional PM processes such as compacting, sintering, rolling, and annealing, and therefore, the dimensions of the product are not constrained by the capacity of an HIP or HP. The properties of Ni[sub 3]Al composite powder metallurgy (CPM) specimens tested at room temperature have been obtained, and comparison with previous reports is conducted. A tensile elongation of about 16 pct at room temperature was attained.

  20. Magnetoimpedance effect of FINEMET ribbons coated with Fe{sub 20}Ni{sub 80} permalloy film

    Energy Technology Data Exchange (ETDEWEB)

    Han, Y.; Li, X.; Lv, W.X.; Xie, W.H.; Zhao, Q.; Zhao, Z.J., E-mail: zjzhao@phy.ecnu.edu.cn

    2016-09-05

    To study the electromagnetic interaction mechanism between different soft magnetic materials, a series of specimen with different thickness Ni{sub 80}Fe{sub 20} film were deposited onto nanocrystalline Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 13.5}B{sub 9} ribbons by magnetron sputtering. X-ray diffraction revealed a slightly structural variation of the ribbons as thickness of the Ni{sub 80}Fe{sub 20} film ranging from 0 to 520 nm. The surface roughness of Ni{sub 80}Fe{sub 20} layer was investigated by Atomic Force Microscopy, showing no significant variation with different thickness of Ni{sub 80}Fe{sub 20} layer. The hysteresis loops and the coercivity value indicated the shift of anisotropy direction from parallel to normal to the surface as the Ni{sub 80}Fe{sub 20} thickness increased, thus influencing the magnetic exchange interaction. Compared to the bare Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 13.5}B{sub 9} ribbons, coating of Ni{sub 80}Fe{sub 20} films significantly enhanced the giant magnetoimpedance response of the ribbons. The 24% improved GMI ratio was achieved in the ribbon with 260 nm thick Ni{sub 80}Fe{sub 20} film. - Highlights: • The exist of electric/magnetic material around will affect magnetic properties. • GMI effect is a useful tool to study magnetic materials. • Exchange interaction exists between the FINEMT ribbon and peralloy film. • The exchange interaction may be varied by the film thickness. • The results was successfully discussed using Herzer models.

  1. Site preference of Hf dopant in Ni{sub 3}Al alloys: A perturbed angular correlation study

    Energy Technology Data Exchange (ETDEWEB)

    Ivanovski, V.N., E-mail: valiva@vin.bg.ac.rs [Laboratory of Nuclear and Plasma Physics, University of Belgrade, Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia); Cekić, B.; Umićević, A. [Laboratory of Nuclear and Plasma Physics, University of Belgrade, Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia); Barudžija, T. [Laboratory of Theoretical and Condensed Matter Physics, University of Belgrade, Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia); Schumacher, G. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Mađarević, I.; Koteski, V. [Laboratory of Nuclear and Plasma Physics, University of Belgrade, Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia)

    2015-02-15

    Highlights: • PAC revealed that Hf atoms substitute on the Al sites in the Ni{sub 3}Al alloy. • Hf dopants in Ni{sub 3}Al induced two tetragonal distortions inside the L1{sub 2} structure. • DFT calculations using the VASP, confirmed the site preference of Hf on the Al sites. - Abstract: Perturbed angular correlation measurements of the hyperfine interactions of the {sup 181}Ta probe in the polycrystalline intermetallic Ni{sub 3}Al doped with 0.5 and 5 at.% Hf were performed in the temperature range 78-1230 K. The observed local hyperfine fields at the {sup 181}Hf/{sup 181}Ta probe showed that Hf atoms are substituting on Al sites in the L1{sub 2} structure of Ni{sub 3}Al. The two minor electric quadrupole interactions that were found for each Ni{sub 3}Al alloy are discussed taking into account the L1{sub 2} cubic structure and its two tetragonal distortions: D0{sub 22} and L6{sub 0}. The presence of two tetragonal transformations of the parent cubic L1{sub 2} lattice in 0.5 at.% Hf and 5 at.% Hf doped Ni{sub 3}Al was revealed by X-ray diffraction. The ab initio calculations, performed with the projector augmented wave method correctly reproduce the experimental results and enable discussion on the structural and electronic properties of the polycrystalline alloys. The experimental and theoretical investigations showed that hafnium additions prefer aluminum sites in Ni{sub 3}Al.

  2. Delta Plaza kohvik = Delta Plaza cafe

    Index Scriptorium Estoniae

    2010-01-01

    Tallinnas Pärnu mnt 141 asuva kohviku Delta Plaza sisekujundusest. Sisearhitektid Tiiu Truus ja Marja Viltrop (Stuudio Truus OÜ). Tiiu Truusi tähtsamate tööde loetelu. Büroohoone Delta Plaza arhitektid Marika Lõoke ja Jüri Okas (AB J. Okas & M. Lõoke)

  3. Delta Plaza kohvik = Delta Plaza cafe

    Index Scriptorium Estoniae

    2010-01-01

    Tallinnas Pärnu mnt 141 asuva kohviku Delta Plaza sisekujundusest. Sisearhitektid Tiiu Truus ja Marja Viltrop (Stuudio Truus OÜ). Tiiu Truusi tähtsamate tööde loetelu. Büroohoone Delta Plaza arhitektid Marika Lõoke ja Jüri Okas (AB J. Okas & M. Lõoke)

  4. Interplay of structural instability and lattice dynamics in Ni{sub 2}MnAl shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mehaddene, T.

    2007-02-12

    The work presented here is devoted to investigate the interplay of lattice dynamics and structural instability in Ni{sub 2}MnAl shape memory alloys. Inelastic neutron scattering is used to get more insight on the dynamic precursors of structural instability in Ni{sub 2}MnAl. Differential Scanning Calorimetry was used to characterise the martensitic transition in Ni{sub 2}MnAl alloys. Effects of composition and heat treatments have been investigated. The measured martensitic transition temperature in Ni-Mn-Al alloys depends linearly on the valence electron concentration. Two single crystals with different compositions have been succesfully grown using the Czochralski technique. Acoustic and optical phonon modes have been measured at room temperature in the high symmetry directions of the cubic B2 phase. The force constants have been fitted to the measured data using the Born-von Karman model. The character of the phonon softening measured in Ni{sub 2}MnAl corresponds to the pattern of atomic displacements of the modulations 2M, 10M, 12M and 14M observed in bulk and thin-films of Ni{sub 2}MnAl. The effect of the composition on the lattice instability has been investigated by measuring normal modes of vibration in two different crystals, Ni{sub 51}Mn{sub 18}Al{sub 31} and Ni{sub 53}Mn{sub 22}Al{sub 25}, with e/a ratios of 7.29 and 7.59 respectively. The stabilisation of a single L2{sub 1} phase in Ni{sub 2}MnAl by annealing a Ni{sub 51}Mn{sub 18}Al{sub 31} single crystal at 673 K during 45 days has been attempted. Despite of the long-time annealing, a single L2{sub 1} phase could not be stabilised because of either a slow diffusion kinetics or the establishment of an equilibrium between the L2{sub 1} and the B2 phases. Phonon measurements of the TA{sub 2}[{xi}{xi}0] branch in the annealed sample revealed a substantial effect. The wiggle, associated with the anomalous softening, is still present but the degree of softening is smaller below 673 K and changes

  5. Temperature dependence of the EPR spectra for the Ni{sub 1-x}Co{sub x}Fe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    P, Silva; W, Braemer; F, Torres [Institute Venezolano de Investigaciones Cientificas, Centro de Fisica, Carretera Panamericana Km. 11, Aptdo. 20632 (Venezuela, Bolivarian Republic of); V, Sagredo; E, Perez, E-mail: silva@ivic.v [Universidad de Los Andes, Departamento de Fisica, Laboratorio de Magnetismo, Merida (Venezuela, Bolivarian Republic of)

    2010-01-01

    Electron Paramagnetic Resonance (EPR) was used to study, the temperature dependence, of the magnetic behavior of Ni{sub 1-x}Co{sub x}Fe{sub 2}O{sub 4} with 0.0 < x < 0.5, in the temperature range 80 < T < 700 K. Nanoparticles of sizes between 30 and 40 nm were obtained using the sol-gel method. The results show that the resonance field (H{sub R}) decrease while the linewidth (AH{sub PP}) increase, in the temperature range studied, when x is increased. The H{sub R} values for x = 0 are in agreement with a superparamagnetic phase in the temperature range studied, while for x = 0.2, H{sub R} and {Delta}H{sub PP} are in accordance with a ferri to superparamagnetic transition at T{approx}350 K, where T is related to the EPR blocking temperature of these samples. For sample with x = 0.5 this temperature is T{approx}470 K. These results are in good agreement with the magnetization and MOKE results. MOKE measurements as a function of temperature were made to corroborate EPR results.

  6. Hydrogen-induced phase transitions in RNi{sub 3} and RY{sub 2}Ni{sub 9} (R = La, Ce) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jing; Fang, Fang; Zheng, Shiyou; Zhu, Jian; Chen, Guorong; Sun, Dalin [Department of Materials Science, Fudan University, 220 Handan Road, Shanghai 200433 (China); Latroche, M.; Percheron-Guegan, A. [Chimie Metallurgique des Terres Rares, UMR 7182, ICMPE, CNRS, 2 rue Henri Dunant, Thiais Cedex 94320 (France)

    2007-10-11

    Structure stability of RNi{sub 3} and RY{sub 2}Ni{sub 9} (R = La, Ce) during cycling of hydrogen absorption/desorption was investigated by both solid-H{sub 2} reaction and electrochemical measurements, in order to understand the mechanism responsible for the poor reversibility, and to reveal the differences between RNi{sub 3} and RY{sub 2}Ni{sub 9} compounds. It has been found that, all of the cycled RNi{sub 3} and RY{sub 2}Ni{sub 9} were subject to partial amorphization. This hydrogen-induced amorphization (HIA) occurred immediately in LaNi{sub 3}, but proceeded gradually in CeNi{sub 3}, LaY{sub 2}Ni{sub 9} and CeY{sub 2}Ni{sub 9}. The HIA in these compounds is attributed to the RM{sub 2} subunits in their crystal structures. (author)

  7. Atomic ordering effect in Ni{sub 50}Mn{sub 37}Sn{sub 13} magnetocaloric ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Wu Dianzhen; Xue Sichuang [Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Frenzel, Jan; Eggeler, Gunther [Institute of Materials, Ruhr University Bochum, Bochum 44801 (Germany); Zhai Qijie [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Zheng Hongxing, E-mail: hxzheng@shu.edu.cn [Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China)

    2012-02-01

    Highlights: Black-Right-Pointing-Pointer High-performance Ni-Mn-Sn magnetocaloric materials are produced. Black-Right-Pointing-Pointer Ni{sub 50}Mn{sub 37}Sn{sub 13} demonstrates great potential for magnetic refrigeration applications. Black-Right-Pointing-Pointer A strong atomic order dependence is revealed in Ni{sub 50}Mn{sub 37}Sn{sub 13} materials. - Abstract: High-performance Ni{sub 50}Mn{sub 37}Sn{sub 13} magnetocaloric materials are produced using melt spinning technique in the present work and the atomic order dependence of phase transition behaviors and magnetic properties is established. The effective refrigeration capacity of the melt-spun ribbon annealed at 1273 K for 15 min reaches 95.27 J/kg for a magnetic field change of 18 kOe, demonstrating great potential for magnetic refrigeration applications near ambient temperature.

  8. Interlocked chiral/polar domain walls and large optical rotation in Ni{sub 3}TeO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xueyun; Huang, Fei-Ting [Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States); Yang, Junjie [Laboratory for Pohang Emergent Materials and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Oh, Yoon Seok [Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States); Department of Physics, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of); Cheong, Sang-Wook, E-mail: sangc@physics.rutgers.edu [Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States); Laboratory for Pohang Emergent Materials and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2015-07-01

    Chirality, i.e., handedness, pervades much of modern science from elementary particles, DNA-based biology to molecular chemistry; however, most of the chirality-relevant materials have been based on complex molecules. Here, we report inorganic single-crystalline Ni{sub 3}TeO{sub 6}, forming in a corundum-related R3 structure with both chirality and polarity. These chiral Ni{sub 3}TeO{sub 6} single crystals exhibit a large optical specific rotation (α)—1355° dm{sup −1} cm{sup 3} g{sup −1}. We demonstrate, for the first time, that in Ni{sub 3}TeO{sub 6}, chiral and polar domains form an intriguing domain pattern, resembling a radiation warning sign, which stems from interlocked chiral and polar domain walls through lowering of the wall energy.

  9. Effect of B and Cr on elastic strength and crystal structure of Ni{sub 3}Al alloys under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Raju, S.V., E-mail: sraju@fiu.edu [CeSMEC, Dept. of Mechanical Engr., Florida International University, Miami, FL 33172 (United States); Oni, A.A. [Department of Materials Science and Engr., North Carolina State University, Raleigh, NC 27695 (United States); Godwal, B.K. [Department of Earth and Planetary Sciences, University of California, Berkeley, CA 94720 (United States); Yan, J. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94730 (United States); Earth and Planetary Sciences Department, University of California, Santa Cruz, CA 95064 (United States); Drozd, V. [CeSMEC, Dept. of Mechanical Engr., Florida International University, Miami, FL 33172 (United States); Srinivasan, S. [Department of Materials Science and Engg., Iowa State University, Iowa, IA (United States); LeBeau, J.M. [Department of Materials Science and Engr., North Carolina State University, Raleigh, NC 27695 (United States); Rajan, K. [Department of Materials Science and Engg., Iowa State University, Iowa, IA (United States); Saxena, S.K. [CeSMEC, Dept. of Mechanical Engr., Florida International University, Miami, FL 33172 (United States)

    2015-01-15

    Highlights: • Ni{sub 3}Al, Ni{sub 3}Al:B and Ni-Al-Cr alloys were prepared by Bridgman-Stockburger technique. • Crystal structures confirmed by XRD and Electron microscopy studies. • Bulk modulus from XRD studies under pressure and Young’s modulus from nano-indentation were determined. • Combining the above results enabled shear modulus and Poisson’s ratio. • K/G ratio suggests that Ni{sub 3}Al doped with B (500 ppm) has the highest hardness with ductility. - Abstract: Samples of Ni{sub 3}Al, Ni{sub 3}Al:B and Ni–Al–Cr super alloys were prepared by directional solidification method and their effect of alloying with ternary elements on the mechanical properties was investigated. In-situ X-ray diffraction studies were carried out on undoped Ni{sub 3}Al, Ni{sub 3}Al:B with boron 500 ppm and Ni–Al–Cr with 7.5 at.% of chromium super alloys at high pressure using diamond anvil cell. The results indicate that micro-alloying with B forms γ′-phase (L1{sub 2} structure), similar to the pure Ni {sub 3}Al, while Ni–Al–Cr alloy consists of γ′ precipitates in a matrix of γ-phase (Ni-FCC structure). The crystal structure of all three alloys was stable up to 20 GPa. Micro alloying with boron increases bulk modulus of Ni{sub 3}Al by 8% whereas alloying with chromium has the opposite effect decreasing the modulus by 11% when compared to undoped alloy. Further, the elastic modulus and hardness of Ni{sub 3}Al, Ni{sub 3}Al:B and Ni–Al–Cr alloys were determined using the nano-indentation technique, in combination with compressibility data which enabled the estimation of shear modulus and Poisson’s ratio of these alloys.

  10. Investigation of mechanosynthesized Fe{sub 50}Ni{sub 40}Al{sub 10} powders

    Energy Technology Data Exchange (ETDEWEB)

    Hadef, F., E-mail: hadef77@yahoo.fr [Laboratoire de Recherche sur la Physico-Chimie des Surfaces et Interfaces, LRPCSI, Université 20 Août 1955, BP 26, Route d’El-Hadaiek, Skikda 21000 (Algeria); Otmani, A. [Laboratoire de Recherche sur la Physico-Chimie des Surfaces et Interfaces, LRPCSI, Université 20 Août 1955, BP 26, Route d’El-Hadaiek, Skikda 21000 (Algeria); Djekoun, A. [Laboratoire de Magnétisme et Spectroscopie des Solides, LM2S, Université Badji Mokhtar, BP 12, Annaba 23000 (Algeria); Grenèche, J.M. [LUNAM, Université du Maine, Institut des Molécules et Matériaux du Mans, UMR CNRS 6283, 72085 Le Mans (France)

    2013-10-15

    The synthesis of Fe{sub 50}Ni{sub 40}Al{sub 10} powder mixture has been performed in a high-energy planetary ball mill. The phase transformations and structural changes occurring during mechanical alloying were investigated by X-ray diffraction (XRD) and Mössbauer spectroscopy. XRD analysis and Rietveld method revealed the formation of a single nanocrystalline fcc γ-Ni(Fe,Al) solid solution with a lattice parameter close to a{sub γ-Ni(Fe,Al)}=0.3612 nm, after 4 h of milling. The final powder is characterized by an average crystallite size of 14 nm accompanied by the introduction of a lattice strain of order of 1.37%. These values are markedly higher than those reported for mechanically alloyed Fe{sub 50}Ni{sub 50} powders. It was found that the formation of the bcc phase, which coexisted with the fcc structure in the Fe–Ni phase diagram, was inhibited. However, mechanical alloying process gives rise to the Ni{sub 3}Al intermetallic phase, at the early stages of milling. Mössbauer spectroscopy showed that all powders exhibited a ferromagnetic behavior and no paramagnetic phase was detected. The addition of low aluminium content caused more broadening of hyperfine field distributions and lower magnetic field due to the diffusion of Al atoms into γ-FeNi lattice. - Highlights: • A nanocrystalline fcc γ-Ni(Fe,Al) solid solution is formed from Fe, Ni and Al powders. • Al addition engenders an increase in a, L and 〈σ{sup 2}〉{sup 1/2} of MA Fe–Ni based alloys. • Al addition causes more broadening of P(B{sub hf}) and lower B{sub hf}.

  11. Magnetism, microstructure and First Principles calculations of atomized and annealed Ni{sub 3}Al

    Energy Technology Data Exchange (ETDEWEB)

    García-Escorial, A., E-mail: age@cenim.csic.es [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Crespo, P.; Hernando, A. [Instituto de Magnetismo Aplicado, IMA-UCM, P.O. Box 155, 28230 Madrid (Spain); Lieblich, M. [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Marín, P.; Velasco, V. [Instituto de Magnetismo Aplicado, IMA-UCM, P.O. Box 155, 28230 Madrid (Spain); Ynduráin, F. [Dpto. de Física de la Materia Condensada, UAM, Cantoblanco, 28049 Madrid (Spain)

    2014-12-05

    Highlights: • The microstructure and order of as-atomized Ni{sub 3}Al powder change with annealing. • The change of the magnetic properties shows the influence of the chemical order. • First Principles calculations show the effect of the density of states to the order. - Abstract: In this work Ni{sub 3}Al powder particles obtained by atomization were characterized magnetically and microstructurally in as-atomized state and after annealing. Upon annealing the X-ray diffraction patterns show a noticeable increase of the signal of the ordered phase γ′-Ni{sub 3}Al, L1{sub 2}, phase and the microstructure evolves from a lamellar and dendrite to a large grain microstructure. The Curie temperature of the as-atomized powder particles is 85 K and decreases after annealing down to 50 K. First Principles calculations were carried out to correlate the experimental observations with local order of Ni and Al atoms and illustrate the importance of the local order in the density of states at the Fermi level, showing how the magnetic moment depends on the Ni and Al atomic position.

  12. Facile preparation of Ni{sub 2}P/ZnO core/shell composites by a chemical method and its photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shuling, E-mail: shulingliu@aliyun.com [Key Laboratory of Auxiliary Chemistry & Technology for Chemical Industry, Ministry of Education, Shaanxi University of Science & Technology, Xi’an, Shaanxi 710021 (China); College of Chemistry & Chemical Engineering, Shaanxi University of Science & Technology, Xi’an, Shaanxi 710021 (China); Ma, Lanbing; Zhang, Hongzhe; Ma, Chenlu [Key Laboratory of Auxiliary Chemistry & Technology for Chemical Industry, Ministry of Education, Shaanxi University of Science & Technology, Xi’an, Shaanxi 710021 (China); College of Chemistry & Chemical Engineering, Shaanxi University of Science & Technology, Xi’an, Shaanxi 710021 (China)

    2016-05-15

    Graphical abstract: The typical SEM images and the schematic illustration of photocatalytic mechanism of as-prepared Ni{sub 2}P/ZnO core/shell composites. - Highlights: • Ni{sub 2}P/ZnO composites have been synthesized via a facile chemical precipitation method. • The effect of the amount of Zn{sup 2+} has been discussed. • Ni{sub 2}P/ZnO composite exhibits an enhanced photocatalytic degradation activity. • A mechanism about the enhanced photocatalytic activity is proposed. - Abstract: Ni{sub 2}P/ZnO core/shell composites were fabricated basing on combining hydrothermal route with a facile chemical precipitation method. The characterization results show that the composites are comprised of the hexagonal Ni{sub 2}P microspheres and hexagonal ZnO nanoparticles. In which, ZnO nanoparticles coat on the surfaces of Ni{sub 2}P microspheres and some of them even assemble to worm-like structure. During the coating process, Zn{sup 2+} was absorbed on the surface of Ni{sub 2}P microspheres by electrostatic interaction and then formed ZnO shell. But excessive Zn{sup 2+} can affect the crystalline and formation of core-shell structure of Ni{sub 2}P/ZnO composites, so it is necessary to control the amount of Zn{sup 2+}. Choosing Methylene Blue (MB) as a typical organic dye, the as-prepared Ni{sub 2}P/ZnO core/shell composites show the enhanced photocatalytic degradation activity, which may be due to its better adsorption ability and the effective separation of photogenerated electron–hole pairs.

  13. Synthesis of murdochite-type Ni{sub 6}MnO{sub 8} with variable specific surface areas and the application in methane oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Taguchi, Hideki, E-mail: htaguchi@cc.okayama-u.ac.jp [The Graduate School of Natural Science and Technology (Science), Okayama University, 3-1-1 Tsushima-Naka, Kita-Ku, Okayama 700-8530 (Japan); Tahara, Shohei [The Graduate School of Natural Science and Technology (Science), Okayama University, 3-1-1 Tsushima-Naka, Kita-Ku, Okayama 700-8530 (Japan); Okumura, Mikoto; Hirota, Ken [Department of Molecular Chemistry and Biochemistry, Faculty of Science and Engineering, Doshisha University, Kyo-Tanabe 610-0321 (Japan)

    2014-07-01

    To synthesize a murdochite-type Ni{sub 6}MnO{sub 8} with variable specific surface areas, an oxalate precursor was calcined at 350–500 °C in flowing argon, and the calcined sample was heated to 600 °C in air. The lattice constant of the Ni{sub 6}MnO{sub 8} did not depend on the calcination temperature of the precursor, while the specific surface area decreased from 8.4 m{sup 2}/g to 2.6 m{sup 2}/g when increasing the calcination temperature of the precursor. The methane (CH{sub 4}) oxidation data indicated that the temperature corresponding to the 50% conversion (T{sub 50%}) of Ni{sub 6}MnO{sub 8} calcined at 350 °C or 400 °C was lower than that of all other Ni{sub 6}MnO{sub 8} specimens. However, the intrinsic conversion of Ni{sub 6}MnO{sub 8} calcined at 350 °C, which is defined as conversion per specific surface area, was half of that of all other Ni{sub 6}MnO{sub 8} specimens. The degree of crystallinity and catalytic performance of the Ni{sub 6}MnO{sub 8} calcined at 400 °C were high. - Graphical abstract: The conversion of CH{sub 4} into CO{sub 2} and H{sub 2}O on Ni{sub 6}MnO{sub 8}, which was heated at 600 °C in air after the calcination of the precursor at 350 °C, 400 °C, 450 °C, or 500 °C in flowing argon, was measured. Since the specific surface area was strongly affected by the calcination temperature of the precursor, intrinsic conversion (IC) was defined as conversion per the specific surface area. For comparison, the IC value on Ni{sub 6}MnO{sub 8} synthesized by the direct calcination of the precursor at 600 °C in air is plotted. - Highlights: • The oxalate precursor was calcined at 350–500 °C in flowing argon. • Murdochite-type Ni{sub 6}MnO{sub 8} was obtained by heating the calcined sample in air. • The specific surface area of Ni{sub 6}MnO{sub 8} varied with the calcination temperature. • The degree of crystallinity and catalysis of Ni{sub 6}MnO{sub 8} calcined at 400 °C were high.

  14. Delta hedging strategies comparison

    DEFF Research Database (Denmark)

    De Giovanni, Domenico; Ortobelli, S.; Rachev, S.T.

    2008-01-01

    In this paper we implement dynamic delta hedging strategies based on several option pricing models. We analyze different subordinated option pricing models and we examine delta hedging costs using ex-post daily prices of S&P 500. Furthermore, we compare the performance of each subordinated model ...

  15. Neutron powder thermo-diffraction in mechanically alloyed Fe{sub 64}Ni{sub 36} invar alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gorria, Pedro, E-mail: pgorria@uniovi.e [Departamento de Fisica, Universidad de Oviedo, Avda. Calvo Sotelo s/n, Oviedo 33007, Asturias (Spain); Martinez-Blanco, David [Unidad de Magnetometria, SCT' s, Universidad de Oviedo, Julian Claveria 8, 33006 Oviedo (Spain); Blanco, Jesus A. [Departamento de Fisica, Universidad de Oviedo, Avda. Calvo Sotelo s/n, Oviedo 33007, Asturias (Spain); Smith, Ronald I. [ISIS Facility, RAL, Chilton, Didcot, Oxon OX11 0QX (United Kingdom)

    2010-04-16

    Nanostructured Fe{sub 64}Ni{sub 36} alloy has been obtained using high-energy ball milling for 35 h of milling time, Fe{sub 64}Ni{sub 36} MA-35 h. The initial as-milled Fe{sub 64}Ni{sub 36} MA-35 h powders are inhomogeneous, showing a majority phase with a face-centred cubic (fcc) crystal structure [88(2)%] and a minority phase with body-centred cubic (bcc) crystal structure [7(2)%]. The evolution of the microstructure with temperature between 300 K and 1100 K has been followed by means of in situ neutron powder thermo-diffraction experiments. The room temperature values for the mean crystalline size and the mechanical-induced microstrain of the fcc phase in the as-milled sample are {approx}10 nm and {approx}0.7%, respectively. Moreover, after heating the Fe{sub 64}Ni{sub 36} MA-35 h powders up to 1100 K, an increase of around 65 K in the Curie temperature respect to that of the commercial coarse-grained alloy of the same composition is observed. The latter together with the observed temperature dependence of the lattice parameter suggests that the Fe{sub 64}Ni{sub 36} MA-35 h sample subjected to the heating process exhibits invar behaviour. On heating up to 1100 K thermal relaxation of the microstructure occurs giving rise to grain growth above 100 nm, nearly vanishing values for the maximum strain, and the transformation of the bcc phase into the fcc one above 800 K, being the latter stable in subsequent heating-cooling processes.

  16. Horizontal Symmetries $\\Delta(150)$ and $\\Delta(600)$

    CERN Document Server

    Lam, C S

    2013-01-01

    Using group theory of mixing to examine all finite subgroups of SU(3) with an order less than 512, we found recently that only the group $\\Delta(150)$ can give rise to a correct reactor angle $\\th_{13}$ of neutrino mixing without any free parameter. It predicts $\\sin^22\\th_{13}=0.11$ and a sub-maximal atmospheric angle with $\\sin^22\\th_{23}=0.94$, in good agreement with experiment. The solar angle $\\th_{12}$, the CP phase $\\d$, and the neutrino masses $m_i$ are left as free parameters. In this article we provide more details of this case, discuss possible gain and loss by introducing right-handed symmetries, and/or valons to construct dynamical models. A simple model is discussed where the solar angle agrees with experiment, and all its mixing parameters can be obtained from the group $\\Delta(600)$ by symmetry alone. The promotion of $\\Delta(150)$ to $\\Delta(600)$ is on the one hand analogous to the promotion of $S_3$ to $S_4$ in the presence of tribimaximal mixing, and on the other hand similar to the extens...

  17. On the width of N-Delta and Delta-Delta states

    CERN Document Server

    Niskanen, J A

    2016-01-01

    It is seen by a coupled-channel calculation that in the two-baryon N-Delta or Delta-Delta system the width of the state is greatly diminished due to the relative kinetic energy of the two baryons, since the internal energy of the particles, available for pionic decay, is smaller. A similar state dependent effect arises from the centrifugal barrier in N-Delta or Delta-Delta systems with non-zero orbital angular momentum. The double-Delta width can become even smaller than the free width of a single Delta. This has some bearing to the interpretation of the d'(2380) resonance recently discovered at COSY.

  18. Superplasticity and cooperative grain boundary sliding in nanocrystalline Ni{sub 3}Al

    Energy Technology Data Exchange (ETDEWEB)

    Mara, N.A. [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)], E-mail: namara@lanl.gov; Sergueeva, A.V.; Mara, T.D. [Materials Science Division, University of California, Davis, One Shields Avenue, Davis, CA 95616 (United States); McFadden, S.X. [Sandia Laboratories, Livermore, CA 94550 (United States); Mukherjee, A.K. [Materials Science Division, University of California, Davis, One Shields Avenue, Davis, CA 95616 (United States)

    2007-08-15

    Cooperative grain boundary sliding (CGBS) has been shown to account for the majority of macroscopic strain seen in microcrystalline metallic systems undergoing superplastic deformation. While CGBS has been observed on the surface of microcrystalline samples deforming superplastically through the shifting of diamond scribe lines, there have been few transmission electron microscopy results showing such occurrences in the bulk of the material, or the details behind the micromechanism of CGBS. In this work, nanocrystalline Ni{sub 3}Al produced via high-pressure torsion is deformed superplastically in the electron microscope. High-temperature ({approx}700 deg. C) in situ tensile testing shows the nature of CGBS at the nanoscale through direct observation of this phenomenon.

  19. Observations of orientation dependent creep of Ni{sub 3}Al

    Energy Technology Data Exchange (ETDEWEB)

    Knobloch, C.; Glock, K.; Glatzel, U.

    1999-07-01

    The influence of crystal orientation on the high temperature creep behavior of Ni{sub 3}(Al Ti Ta) was investigated by tensile creep testing under a constant load at a temperature of 1,123K. The single crystals were oriented close to [001], [011], [111], [557] and [012]. The results show an increasing stationary creep rate from [111] over [011] to [001]. The evolution of the microstructure during creep deformation was studied, using transmission electron microscopy (TEM). Only few systems are active in the primary regime, whereas several slip systems operate in the secondary stage. habit planes of dislocation pairs separated by an antiphase boundary were examined and compared with anisotropic elastic calculations, explaining the good creep response of [111] oriented using crystals.

  20. Self-diffusion of Ni in the intermetallic compound Ni{sub 3}Al

    Energy Technology Data Exchange (ETDEWEB)

    Chen Guoxiang [School of Science, Xi' an Shiyou University, Xi' an 710065, Shaanxi (China)], E-mail: guoxchen@xsyu.edu.cn; Wang Doudou [Institute of Telecommunication Engineering of the Air Force Engineering University (AFEU1), Xi' an 710077, Shaanxi (China); Zhang Jianmin [College of Physics and Information Technology, Shaanxi Normal University, Changan South Road, Xi' an 710062, Shaanxi (China); Huo Hanping [School of Science, Xi' an Shiyou University, Xi' an 710065, Shaanxi (China); Xu Kewei [State-Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China)

    2008-10-01

    Combining molecular dynamic (MD) simulation with modified analytic embedded-atom method (MAEAM) potential, the defect formation, migration and activation energies of Ni self-diffusion in intermetallic compound Ni{sub 3}Al have been calculated for five diffusion mechanisms, nearest-neighbor (NN) jump, next-nearest-neighbor (NNN) jump, straight [0 1 0] six-jump cycle (6JC), bent [0 1 0] 6JC and two concerted jumps. The results show that the Ni self-diffusion is dominated by the NN jump since it requires essentially the lowest migration or activation energy (Q=2.511 eV) in the five diffusion mechanisms. This is consistent with the experimental results.

  1. Atomic-size effect on the microstructural properties of Ni{sub 2}FeGa

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Huairuo, E-mail: Huairuo.Zhang@nrc-cnrc.gc.ca [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); National Institute for Nanotechnology, Edmonton, 11421 Saskatchewan Drive, T6G 2M9 (Canada); Wu Guangheng [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2011-02-15

    The microstructural properties of melt-spun ribbon of the ferromagnetic shape-memory Heusler alloy Ni{sub 2}FeGa have been investigated by transmission electron microscopy. Two kinds of micromodulated structures, Fe-rich and Ga-rich, have been established. The Fe-rich micromodulated structure is formed by Fe atoms partially replacing Ga atoms on {l_brace}3 5 0{r_brace} planes in the L2{sub 1} structure. The Ga-rich micromodulated structure concerns Ga atoms partially replacing Fe atoms on {l_brace}3 + n, 5 + n, 0{r_brace}(n {>=} 0) planes. The Fe-rich and Ga-rich micromodulated structures originate from spinodal decomposition of the Fe and Ga compositions, which is closely related to the difference of atomic sizes of Ni, Fe and Ga.

  2. Structural and magnetic properties of Co{sub 50}Ni{sub 50} powder mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Loudjani, N., E-mail: loudjani_nadia@yahoo.fr [Laboratoire de Magnetisme et Spectroscopie des solides, Departement de Physique, Faculte des Sciences, Universite Badji Mokhtar, B.P. 12, 23000 Annaba (Algeria); Bensebaa, N.; Dekhil, L.; Alleg, S. [Laboratoire de Magnetisme et Spectroscopie des solides, Departement de Physique, Faculte des Sciences, Universite Badji Mokhtar, B.P. 12, 23000 Annaba (Algeria); Sunol, J.J. [Dep. de Fisica, Universitat de Girona, Campus Montilivi, Girona 17071 (Spain)

    2011-12-15

    In the present work, morphological, structural, thermal and magnetic properties of nanocrystalline Co{sub 50}Ni{sub 50} alloy prepared by high energy planetary ball milling have been studied by means of scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry. The coercivity and the saturation magnetization of alloyed powders were measured at room temperature by a vibration sample magnetization. Morphological observations indicated a narrow distribution in the particle and homogeneous shape form with mean average particle size around 130 {mu}m{sup 2}. The results show that an allotropic Co transformation hcp{yields}fcc occurs within the three first hours of milling and contrary to what expected, the Rietveld refinement method reveals the formation of two fcc solid solutions (SS): fcc Co(Ni) and Ni(Co) beside a small amount of the undissolved Co hcp. Thermal measurement, as a function of milling time was carried out to confirm the existence of the hcp phase and to estimate its amount. Magnetic measurement indicated that the 48 h milled powders with a steady state particles size have the highest saturation (105.3 emu/g) and the lowest coercivity (34.5 Oe). - Highlights: > By using the Rietveld refinement method we found that Co{sub 50}Ni{sub 50} alloy, milled for 48 h, contains two fcc solid solutions: fcc Co(Ni) and Ni(Co), beside a small amount of the undissolved Co hcp. DSC measurement as a function of milling time was carried out to confirm the existence of the hcp phase and to estimate its amount. > By means of imageJ we found the area distribution and not just the diameter distribution. > The coercivity is strongly related to the particles size distribution.

  3. Resistance to He{sup 2+} irradiation damage in metallic glass Ta{sub 38}Ni{sub 62}

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Wenjing [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024 (China); Mei, Xianxiu, E-mail: xxmei@dlut.edu.cn [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024 (China); Zhang, Xiaonan; Wang, Yingmin; Qiang, Jianbing [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024 (China); Sun, Jianrong [Institute of Modern Physics, The Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, Younian [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024 (China)

    2016-10-15

    Highlights: • Metallic glass Ta{sub 38}Ni{sub 62} irradiated by different fluence of He{sup 2+} remained amorphous. • The helium bubble layer appeared at the end of ion range 1.01 μm away from surface. • Helium bubbles were larger in the layer center and reduced to top and bottom sides. • No significant damage appeared in the surface of metallic glass Ta{sub 38}Ni{sub 62}. • Ta{sub 38}Ni{sub 62} better resisted to He{sup 2+} irradiation than W and V{sub 87.5}Cr{sub 4.17}Ti{sub 4.17}Nb{sub 4.17}. - Abstract: Metallic glass Ta{sub 38}Ni{sub 62} strips, metallic W, and V{sub 87.5}Cr{sub 4.17}Ti{sub 4.17}Nb{sub 4.17} alloy were irradiated using a 500 keV He{sup 2+} ion beam at different fluence to compare the metallic glass resistance to irradiation. Metallic glass Ta{sub 38}Ni{sub 62} remained amorphous at different He{sup 2+} irradiation fluence. Transmission electron microscopy analysis revealed the presence of helium bubbles at the end of the range of helium ions in the metallic glass. No significant damage resulted in the metallic glass surface, and the root mean square roughness increased nonlinearly with the increase in fluence. At 1 × 10{sup 18} ions/cm{sup 2}, metallic W appeared in larger sunken areas on the surface and V{sub 87.5}Cr{sub 4.17}Ti{sub 4.17}Nb{sub 4.17} alloy experienced multi-layer flaking. The metallic glass Ta{sub 38}Ni{sub 62} resistance to He{sup 2+} ion beam irradiation was better than that of metallic W, and that of the V{sub 87.5}Cr{sub 4.17}Ti{sub 4.17}Nb{sub 4.17} alloy was the poorest.

  4. geomorphology_delta

    Data.gov (United States)

    California Department of Resources — Surficial geology of the Delta area of California by Brian Atwater of the U.S. Geological Survey. Source maps are from the USGS publication MF-1401. This digital...

  5. Core-shell Ni{sub 0.5}TiOPO{sub 4}/C composites as anode materials in Li ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.J.; Zhang, Y. [Institute of New Energy Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Nankai University, Tianjin 300071 (China); Zhou, Z., E-mail: zhouzhen@nankai.edu.c [Institute of New Energy Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Nankai University, Tianjin 300071 (China); Wei, J.P. [Institute of New Energy Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Nankai University, Tianjin 300071 (China); Essehli, R. [SUBATECH, Unite Mixte de Recherche 6457, Ecole des mines de Nantes, CNRS/IN2P3, Universite de Nantes, BP 20722, 44307 Nantes cedex 3 France (France); Laboratory of Mineral Solid and Analytical Chemistry ' LMSAC' , Department of Chemistry, Faculty of Sciences, University Mohamed I, PO Box 624, 60000 Oujda (Morocco); Bali, B. El [Laboratory of Mineral Solid and Analytical Chemistry ' LMSAC' , Department of Chemistry, Faculty of Sciences, University Mohamed I, PO Box 624, 60000 Oujda (Morocco)

    2011-02-01

    Pristine Ni{sub 0.5}TiOPO{sub 4} was prepared via a traditional solid-state reaction, and then Ni{sub 0.5}TiOPO{sub 4}/C composites with core-shell nanostructures were synthesized by hydrothermally treating Ni{sub 0.5}TiOPO{sub 4} in glucose solution. X-ray diffraction patterns indicate that Ni{sub 0.5}TiOPO{sub 4}/C crystallizes in monoclinic P2{sub 1}/c space group. Scanning electron microscopy and transmission electron microscopy show that the small particles with different sizes are coated with uniform carbon film of {approx}3 nm in thickness. Raman spectroscopy also confirms the presence of carbon in the composites. Ni{sub 0.5}TiOPO{sub 4}/C composites presented a capacity of 276 mAh g{sup -1} after 30 cycles at the current density of 42.7 mA g{sup -1}, much higher than that of pristine Ni{sub 0.5}TiOPO{sub 4} (155 mAh g{sup -1}). The improved electrochemical performances can be attributed to the existence of carbon shell.

  6. Delta-Reliability

    OpenAIRE

    Eugster, P.; Guerraoui, R.; Kouznetsov, P.

    2001-01-01

    This paper presents a new, non-binary measure of the reliability of broadcast algorithms, called Delta-Reliability. This measure quantifies the reliability of practical broadcast algorithms that, on the one hand, were devised with some form of reliability in mind, but, on the other hand, are not considered reliable according to the ``traditional'' notion of broadcast reliability [HT94]. Our specification of Delta-Reliability suggests a further step towards bridging the gap between theory and...

  7. Structural and mechanical characterization of rapidly solidified Al{sub 95}Ni{sub 5} and Al{sub 93}Ni{sub 5}Mm{sub 2} alloys prepared by centrifugal atomization

    Energy Technology Data Exchange (ETDEWEB)

    Vojtech, D., E-mail: Dalibor.Vojtech@vscht.c [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Prusa, F.; Michalcova, A. [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic)

    2010-09-17

    Research highlights: {yields} Structure and properties of a rapidly solidified Al-Ni-Mm alloy with a relatively low Mm content. {yields} Comparison of slowly and rapidly solidified state. {yields} High hardness of the RS Al-Ni-Mm alloy, but low thermal stability. {yields} Chemical compositions of metastable primary phases in the RS Al-Ni-Mm alloy. - Abstract: Al{sub 95}Ni{sub 5} and Al{sub 93}Ni{sub 5}Mm{sub 2} (at.%) alloys were prepared by induction melting and centrifugal atomization. Both as-cast and rapidly solidified (RS) alloys were studied by various techniques, including light, scanning and transmission electron microscopy, energy dispersion spectrometry, differential scanning calorimetry and X-ray diffraction analysis. Room temperature hardness was measured for the rapidly solidified alloys, as well as after their long-term annealing at 400 {sup o}C. It is observed that the RS alloys are crystalline. The binary Al-Ni alloy consists of Al and Al{sub 3}Ni phases, while in the ternary Al-Ni-Mm alloy, there are Al dendrites supersaturated with Ni, Al{sub 3}Ni and non-equilibrium {alpha}Al{sub 11}(Mm,Ni){sub 3} phases. Average Al dendrite arm thickness is about 100 nm. Both supersaturated Al and {alpha}Al{sub 11}(Mm,Ni){sub 3} decompose upon heating at 300-450 {sup o}C. Room temperature hardness of the RS Al{sub 95}Ni{sub 5} and Al{sub 93}Ni{sub 5}Mm{sub 2} alloys are 150 and 300 HV, respectively. These values are discussed in relation to various hardening mechanisms. Thermal stability of both alloys is low, due a rapid structural coarsening and hardness reduction during annealing at 400 {sup o}C.

  8. Charge-transport in Josephson-junctions with ferromagnetic Ni{sub 3}Al-interlayer; Ladungstransport in Josephson-Kontakten mit ferromagnetischer Ni{sub 3}Al-Zwischenschicht

    Energy Technology Data Exchange (ETDEWEB)

    Born, F.

    2006-07-01

    The present dissertation reports on experimental studies about superconducting coupling through a thin Ni{sub 76}Al{sub 24} film. A new patterning process has been developed, which allows in combination with the wedge shaped deposition technique the in situ deposition of 20 single Nb/Al/Al{sub 2}O{sub 3}/Ni{sub 3}Al/Nb multilayers, each with its own well defined Ni{sub 3}Al thickness. Every single multilayer consists of 10 different sized Josephson junctions, showing a high reproducibility and scaling with its junction area. Up to six damped oscillations of the critical current density against F-layer thickness were observed, revealing three single 0-{pi}-transitions in the ground state of Josephson junctions. Contrary to former experimental studies, the exponential decay length is one magnitude larger than the oscillation period defining decay length. The theoretical predictions based on linearised Eilenberger equations results in excellent agreement of theory and experimental results. (orig.)

  9. Magnetocaloric properties of as-quenched Ni{sub 50.4}Mn{sub 34.9}In{sub 14.7} ferromagnetic shape memory alloy ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Llamazares, J.L. [Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICYT), San Luis Potosi, S.L.P. (Mexico); Garcia, C. [MIT, Department of Materials Science and Engineering, Massachusetts (United States); Hernando, B.; Prida, V.M. [Universidad de Oviedo, Departamento de Fisica, Facultad de Ciencias, Oviedo (Spain); Baldomir, D.; Serantes, D. [Universidade de Santiago de Compostela, Departamento de Fisica Aplicada, Facultad de Fisica, Santiago de Compostela (Spain); Gonzalez, J. [UPV, Departamento Fisica de Materiales, Facultad de Quimica, San Sebastian (Spain)

    2011-06-15

    The temperature dependences of magnetic entropy change and refrigerant capacity have been calculated for a maximum field change of {delta} H=30 kOe in as-quenched ribbons of the ferromagnetic shape memory alloy Ni{sub 50.4}Mn{sub 34.9}In{sub 14.7} around the structural reverse martensitic transformation and magnetic transition of austenite. The ribbons crystallize into a single-phase austenite with the L2{sub 1}-type crystal structure and Curie point of 284 K. At 262 K austenite starts its transformation into a 10-layered structurally modulated monoclinic martensite. The first- and second-order character of the structural and magnetic transitions was confirmed by the Arrott plot method. Despite the superior absolute value of the maximum magnetic entropy change obtained in the temperature interval where the reverse martensitic transformation occurs ({delta}S{sub M} {sup max}=7.2 Jkg{sup -1}K{sup -1}) with respect to that obtained around the ferromagnetic transition of austenite ({delta} S{sub M} {sup max}=2.6 Jkg{sup -1}K{sup -1}), the large average hysteretic losses due to the effect of the magnetic field on the phase transformation as well as the narrow thermal dependence of the magnetic entropy change make the temperature interval around the ferromagnetic transition of austenite of a higher effective refrigerant capacity (RC{sup magn}{sub eff}=95Jkg{sup -1} versus RC{sup struct}{sub eff}=60Jkg{sup -1}). (orig.)

  10. Atomic scale understanding of magnetic properties in Ni{sub 50}Fe{sub 35}Co{sub 15}

    Energy Technology Data Exchange (ETDEWEB)

    Herojit Singh, L.; Govindaraj, R., E-mail: govind@igcar.gov.in; Rajagopalan, S.; Amarendra, G. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603102 (India); Ravishankar, C. [Materials Technology Division, Indira Gandhi Centre for Atomic Research, Kalpakkam – 603102 (India)

    2016-02-15

    Mössbauer spectroscopic studies have been carried out at different temperatures across ferromagnetic to paramagnetic transition in Ni{sub 50}Fe{sub 35}Co{sub 15} and the evolution of hyperfine parameters such as centre shift and magnetic hyperfine fields with temperature has been studied. Mössbauer spectrum obtained at 300 K in Ni{sub 50}Fe{sub 35}Co{sub 15} exhibiting fcc crystal structure is a six line pattern with the mean value of the hyperfine field close to 33 Tesla. Ferromagnetic to paramagnetic transition has been observed to occur in this system around 895 K matching with that of magnetization results. Debye temperature of this nickel rich alloy is deduced to be around 470 K matching with that of Ni. Effect of prolonged annealing at 750 K on the magnetic property is also investigated with respect to the thermal stability of the alloy.

  11. Magnetic-field-induced strain in Ni{sub 2}MnGa melt-spun ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Algarabel, P.A. E-mail: algarabe@posta.unizar.es; Magen, C.; Morellon, L.; Ibarra, M.R.; Albertini, F.; Magnani, N.; Paoluzi, A.; Pareti, L.; Pasquale, M.; Besseghini, S

    2004-05-01

    Linear thermal expansion (300-350 K) and magnetostriction measurements in magnetic fields up to 15 kOe have been performed on a Ni{sub 2}MnGa melt-spun ribbon. The magnetic-field-induced strain has been studied on a field-cooling process through the martensitic transformation and shows a maximum as a function of the applied field. This previously unreported behaviour is discussed.

  12. Synthesis of ternary Ni{sub 1−x}Fe{sub x}S single crystalline nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Xiaoying [College of Physical Science and Technology, Xinjiang University, Urumqi 830046, Xinjiang (China); Zhang, Zhihua [Liaoning Key Materials Laboratory for Railway, School of Materials Science and Engineering, Dalian Jiaotong University, Dalian 116028 (China); Wu, Rong; Li, Jin [College of Physical Science and Technology, Xinjiang University, Urumqi 830046, Xinjiang (China); Jian, Jikang, E-mail: jikangjian@gmail.com [College of Physical Science and Technology, Xinjiang University, Urumqi 830046, Xinjiang (China)

    2014-12-05

    Highlights: • Ternary Ni{sub 1−x}Fe{sub x}S single-crystal nanorods were synthesized by a solvothermal technique. • Crystal structures, morphology and compositions of the ternary nanorods were characterized in details. • The band gaps of the Ni{sub 1−x}Fe{sub x}S nanorods were determined by optical absorption test. - Abstract: Single-crystalline Fe-doped NiS ternary nanorods with uniform morphology have been successfully synthesized in ethylenediamine solvent by a solvothermal technique using Ni, S and FeCl{sub 2}⋅4H{sub 2}O as starting materials. The phase, morphology, compositions and microstructure of the products have been characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The results show that the Ni{sub 1−x}Fe{sub x}S nanorods are well crystallized and the highest Fe doping concentration x is about 17.51%. The addition of Fe{sup 2+} ions can facilitate the one-dimensional growth and enlarge the band gaps of the nanorods.

  13. {\\delta}M Formalism

    CERN Document Server

    Talebian-Ashkezari, Alireza; Abolhasani, Ali Akbar

    2016-01-01

    We study the evolution of the "non-perturbative" metric perturbations in a Bianchi background in the long-wavelength limit. By applying the gradient expansion to the equations of motion we exhibit a generalized "Separate Universe" approach to the cosmological perturbation theory. Having found this consistent separate universe picture, we introduce the "{\\delta}M formalism" for calculating the evolution of the tensor perturbations in anisotropic inflation models in almost similar way as the so-called {\\delta}N formula for the super-horizon dynamics of the curvature perturbations. Likewise its ancestor, {\\delta}N formalism, this new method can substantially reduce the amount of calculations related to the evolution of the tensor modes.

  14. Ferromagnetic properties of Ni-rich Ni[sub 1-x]Nb[sub x] alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jesser, R. (IPCMS-GEMME, Inst. de Physique, 67 - Strasbourg (France)); Clad, R. (IPCMS-GEMME, Inst. de Physique, 67 - Strasbourg (France)); Schmerber, G. (IPCMS-GEMME, Inst. de Physique, 67 - Strasbourg (France))

    1993-06-01

    This paper investigates paramagnetic (T>>Tc) and ferromagnetic (T<Ni[sub 1-x]Nb[sub x] (crystalline and atomically disordered) fcc solid solutions with 0Ni[sub 1-x]Nb[sub x] alloys (as has been shown by other authors for other Ni-based alloys). (iii) The decrease in the absolute ferromagnetic moment [mu] (in [mu][sub B] per mean atom of alloy) with atomic (solute) Nb content x, is consistent with Friedel's virtual bound-state (Abstract Truncated)

  15. The Niger Delta Crisis

    African Journals Online (AJOL)

    chifaou.amzat

    2013-09-28

    Sep 28, 2013 ... lions de barils par jour à environ 1 million au plus fort de la crise du Delta ... (JTF) between 13 May 2009 and 4 October 2009 (the deadline for embrac- ..... He had just ended his welcome address as the occasion's chairman.

  16. Effect of amorphous Mg{sub 50}Ni{sub 50} on hydriding and dehydriding behavior of Mg{sub 2}Ni alloy

    Energy Technology Data Exchange (ETDEWEB)

    Guzman, D., E-mail: danny.guzman@uda.cl [Departamento de Ingenieria en Metalurgia, Facultad de Ingenieria, Universidad de Atacama y Centro Regional de Investigacion y Desarrollo Sustentable de Atacama (CRIDESAT), Av. Copayapu 485, Copiapo (Chile); Ordonez, S. [Departamento de Ingenieria Metalurgica, Facultad de Ingenieria, Universidad de Santiago de Chile, Av. Lib. Bernardo O' Higgins 3363, Santiago (Chile); Fernandez, J.F.; Sanchez, C. [Departamento de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco 28049, Madrid (Spain); Serafini, D. [Departamento de Fisica, Facultad de Ciencias, Universidad de Santiago de Chile and Center for Interdisciplinary Research in Materials, CIMAT, Av. Lib. Bernardo O' Higgins 3363, Santiago (Chile); Rojas, P.A. [Escuela de Ingenieria Mecanica, Facultad de Ingenieria, Av. Los Carrera 01567, Quilpue, Pontificia Universidad Catolica de Valparaiso, PUCV (Chile); Aguilar, C. [Departamento de Ingenieria Metalurgica y Materiales, Universidad Tecnica Federico Santa Maria, Av. Espana 1680, Valparaiso (Chile); Tapia, P. [Departamento de Ingenieria en Metalurgia, Facultad de Ingenieria, Universidad de Atacama, Av. Copayapu 485, Copiapo (Chile)

    2011-04-15

    Composite Mg{sub 2}Ni (25 wt.%) amorphous Mg{sub 50}Ni{sub 50} was prepared by mechanical milling starting with nanocrystalline Mg{sub 2}Ni and amorphous Mg{sub 50}Ni{sub 50} powders, by using a SPEX 8000 D mill. The morphological and microstructural characterization of the powders was performed via scanning electron microscopy and X-ray diffraction. The hydriding characterization of the composite was performed via a solid gas reaction method in a Sievert's-type apparatus at 363 K under an initial hydrogen pressure of 2 MPa. The dehydriding behavior was studied by differential thermogravimetry. On the basis of the results, it is possible to conclude that amorphous Mg{sub 50}Ni{sub 50} improved the hydriding and dehydriding kinetics of Mg{sub 2}Ni alloy upon cycling. A tentative rationalization of experimental observations is proposed. - Research Highlights: {yields} First study of the hydriding behavior of composite Mg{sub 2}Ni (25 wt.%) amorphous Mg{sub 50}Ni{sub 50}. {yields} Microstructural characterization of composite material using XRD and SEM was obtained. {yields} An improved effect of Mg{sub 50}Ni{sub 50} on the Mg{sub 2}Ni hydriding behavior was verified. {yields} The apparent activation energy for the hydrogen desorption of composite was obtained.

  17. Simulation of dislocations in ordered Ni{sub 3}Al by atomic stiffness matrix method

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Y.E.; Chaki, T.K. [State Univ. of New York, Buffalo, NY (United States). Dept. of Mechanical and Aerospace Engineering

    1996-12-31

    A simulation of structure and motion of edge dislocations in ordered Ni{sub 3}Al was performed by atomic stiffness matrix method. In this method the equilibrium positions of the atoms were obtained by solving a set of linear equations formed by a stiffness matrix, whose terms consisted of derivatives of the interaction potential of EAM (embedded atom method) type. The superpartial dislocations, separated by an antiphase boundary (APB) on (111), dissociated into Shockley partials with complex stacking faults (CSF) on (111) plane. The core structure, represented by the Burgers vector density distribution and iso-strain contours, changed under applied stresses as well as upon addition of boron. The separation between the superpartials changed with the addition of B and antisite Ni. As one Shockley partial moved out to the surface, a Shockley partial in the interior moved a large distance to join the lone one near the surface, leaving behind a long CSF strip. The decrease in the width of the APB upon addition of B and antisite Ni has been explained by a reduction of the strength of directional bonding between Ni and Al as well as by the dragging of B atmosphere by the superpartials.

  18. Simulation of dislocations in ordered Ni{sub 3}Al by atomic stiffness matrix method

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Y.E.; Chaki, T.K. [State Univ. of New York, Buffalo, NY (United States). Dept. of Mechanical and Aerospace Engineering

    1996-12-01

    A simulation of structure and motion of edge dislocations in ordered Ni{sub 3}Al was performed by atomic stiffness matrix method. In this method the equilibrium positions of the atoms were obtained by solving a set of linear equations formed by a stiffness matrix, whose terms consisted of derivatives of the interaction potential of EAM (embedded atom method) type. The superpartial dislocations, separated by an antiphase boundary (APB) on (111), dissociated into Shockley partials with complex stacking faults (CSF) on (111) plane. The core structure, represented by the Burgers vector density distribution and iso-strain contours, changed under applied stresses as well as upon addition of boron. The separation between the superpartials changed with the addition of B and antisite Ni. As one Shockley partial moved out to the surface, a Shockley partial in the interior moved a large distance to join the lone one near the surface, leaving behind a long CSF strip. The decrease in the width of the APB upon addition of B and antisite Ni has been explained by a reduction of the strength of direction bonding between Ni and Al as well as by the dragging of B atmosphere by the superpartials.

  19. Diffuse phase transition and magnetoelectric effect in (f) Co{sub 0.8}Ni{sub 0.2}Fe{sub 2}O{sub 4} + (1 - f) PMN-PT particulate composites

    Energy Technology Data Exchange (ETDEWEB)

    Sheikh, Arif D. [Novel Materials Research Laboratory, Department of Physics, University of Pune, Pune 411 007, MS (India); Mathe, V.L., E-mail: vlmathe@physics.unipune.ernet.in [Novel Materials Research Laboratory, Department of Physics, University of Pune, Pune 411 007, MS (India)

    2010-02-15

    Magnetoelectric (ME) materials have ability to convert magnetic energy into the electrical voltage and/or to converts electrical energy into the magnetic energy. The present studies comprise structural, dielectric and electrical properties of (f) Co{sub 0.8}Ni{sub 0.2}Fe{sub 2}O{sub 4} + (1 - f) Pb(Mg{sub 1/3}Nb{sub 2/3}){sub 0.67}Ti{sub 0.33}O{sub 3} composites. The presence of both the phases in the composites was confirmed using X-ray diffraction technique. The variations of dielectric constant and loss tangent were studied with frequency at room temperature as well as at higher temperature. Temperature dependent dielectric constant behaviour shows diffuse phase transition in ME composites. The diffuse phase transition can be well described by fitting the Lorentz-type relation ({epsilon}{sub A})/({epsilon}) =1+((T-T{sub A}){sup 2})/(2{delta}{sup 2}) . In the present case the diffusion is seen to be increases with increasing applied frequency. The dc electrical resistivity measurements were carried out in the temperature range of 300-923 K. Variation of ME voltage coefficient tracks the path of magnetostriction as a function of magnetic field. All the composites show peak behaviour in magnetic field dependent on ME voltage coefficient.

  20. Hydrides of CeNi/sub 5/, MmNi/sub 5/, Ca/sub 0/ /sub 2/(Ce/sub 0/ /sub 65/Mm/sub 0/ /sub 35/)/sub 0/ /sub 8/Ni/sub 5/, Ca/sub 0/ /sub 2/Ce/sub 0/ /sub 8/Ni/sub 5/, Ca/sub 0/ /sub 2/Mm/sub 0/ /sub 8/Ni/sub 5/, and mixed CeNi/sub 5//MmNi/sub 5/

    Energy Technology Data Exchange (ETDEWEB)

    Lakner, J.F.; Chow, T.S.

    1982-09-01

    Six intermetallic alloys (CeNi/sub 5/, MmNi/sub 5/, Ca/sub 0/ /sub 2/(Ce/sub 0/ /sub 65/Mm/sub 0/ /sub 35/)/sub 0/ /sub 8/Ni/sub 5/, Ca/sub 0/ /sub 2/Ce/sub 0/ /sub 8/Ni/sub 5/, Ca/sub 0/ /sub 2/Mm/sub 0/ /sub 8/Ni/sub 5/, and a mixed alloy, CeNi/sub 5//MmNi/sub 5/) were investigated with respect to their suitability to provide high hydrogen capacity and their potential for use in providing substantial hydrogen pressure at both low and high temperatures. A second phase of our investigation dealt with ball-milling and hydriding and dehydriding cycles to produce fine particles for use in hydride powder transfer studies. A summary of several Van't Hoff plots is also included for hydride-forming alloys.

  1. DELTAS: A new Global Delta Sustainability Initiative (Invited)

    Science.gov (United States)

    Foufoula-Georgiou, E.

    2013-12-01

    Deltas are economic and environmental hotspots, food baskets for many nations, home to a large part of the world population, and hosts of exceptional biodiversity and rich ecosystems. Deltas, being at the land-water interface, are international, regional, and local transport hubs, thus providing the basis for intense economic activities. Yet, deltas are deteriorating at an alarming rate as 'victims' of human actions (e.g. water and sediment reduction due to upstream basin development), climatic impacts (e.g. sea level rise and flooding from rivers and intense tropical storms), and local exploration (e.g. sand or aggregates, groundwater and hydrocarbon extraction). Although many efforts exist on individual deltas around the world, a comprehensive global delta sustainability initiative that promotes awareness, science integration, data and knowledge sharing, and development of decision support tools for an effective dialogue between scientists, managers and policy makers is lacking. Recently, the international scientific community proposed to establish the International Year of Deltas (IYD) to serve as the beginning of such a Global Delta Sustainability Initiative. The IYD was proposed as a year to: (1) increase awareness and attention to the value and vulnerability of deltas worldwide; (2) promote and enhance international and regional cooperation at the scientific, policy, and stakeholder level; and (3) serve as a launching pad for a 10-year committed effort to understand deltas as complex socio-ecological systems and ensure preparedness in protecting and restoring them in a rapidly changing environment. In this talk, the vision for such an international coordinated effort on delta sustainability will be presented as developed by a large number of international experts and recently funded through the Belmont Forum International Opportunities Fund. Participating countries include: U.S., France, Germany, U.K., India, Japan, Netherlands, Norway, Brazil, Bangladesh

  2. Synthesis of Nanocrystalline Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} by Aerosol Route and Its Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Singhal, Sonal [Indian Institute of Technology-Roorkee, Institute Instrumentation Centre (India); Garg, A. N. [Indian Institute of Technology-Roorkee, Department of Chemistry (India); Chandra, Kailash, E-mail: chandfuc@iitr.ernet.in [Indian Institute of Technology-Roorkee, Institute Instrumentation Centre (India)

    2004-12-15

    Nano-size particles of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} ferrite were prepared through aerosol route. The solutions of iron, nickel and zinc nitrates were mixed in stoichiometric proportion, passed through a pneumatic nebulizer, to get very fine mist (aerosols), and a furnace at {approx}600{sup o}C in air atmosphere. Through various events in succession, metal atoms form ferrite in air. The average particle size was found to be 16{+-}6 nm which increased to 80{+-}8 nm after annealing at 1000{sup o}C. The room-temperature magnetic moment of the sample as obtained and after annealing it at various temperatures indicate that the saturation magnetization increases from 1.80 to 72.8 emu/g, while remanent magnetization increases from 0.28 to 25.0 emu/g. Moessbauer spectrum of the sample at room temperature exhibited a doublet with {delta}(Fe)=0.33 mm s{sup -1} and {Delta}E{sub Q}=0.78 mm s{sup -1} suggesting superparamagnetic nature. However, after annealing at 1000{sup o}C this doublet got converted into two magnetic sextets with B=52.4 T and 49.0 T suggesting increase in particle size on annealing. These observations are in conformity with Transmission Electron Microscope (TEM) and X-Ray Diffraction (XRD) results that the particle size increases after annealing the sample at higher temperatures.

  3. Ab initio study of Fermi surface and dynamical properties of Ni{sub 2}XAl (X = Ti, V, Zr, Nb, Hf and Ta)

    Energy Technology Data Exchange (ETDEWEB)

    Sreenivasa Reddy, P.V.; Kanchana, V., E-mail: kanchana@iith.ac.in

    2014-12-15

    Highlights: • Electronic structure properties studied at ambient as well as under compression. • Mechanical properties are predicted for the first time. • Vibrational properties are studied at ambient as well as under compression. • Ni{sub 2}TiAl is found to have the lowest C{sub v}, S, and higher U, F{sub vib} and linear thermal expansion coefficient. • T{sub c} of Ni{sub 2}NbAl is calculated and a non-monotonic variation in the T{sub c} is observed under compression. - Abstract: A detailed study on the pressure and temperature effects on ternary Ni-based inter-metallic compounds Ni{sub 2}XAl (X = Ti, V, Zr, Nb, Hf and Ta) have been carried out using density functional theory. The calculated ground state properties are in good agreement with experiments for all the investigated compounds. The band structures and Fermi surface topology is found to be quite similar for all the compounds except for Ni{sub 2}NbAl, where we find an extra band to cross the Fermi level under compression resulting in a new electron pocket at X-point. Ni{sub 2}NbAl is found to be a superconductor with superconducting transition temperature of 3.1 K which agrees quite well with the experimental value and the calculated T{sub c} is found to vary non-monotonically under pressure. From the calculated phonon dispersion relation, we find all the investigated Ni-based Heusler compounds to be dynamically stable, until high pressure. The ductile nature of these compounds is confirmed from the calculated Cauchy’s pressure, Pugh’s ratio and Poisson’s ratio. In addition, the thermodynamic properties show Ni{sub 2}TiAl to have lower specific heat and entropy but higher internal energy and free energy among all the investigated compounds.

  4. Improvement in ductility of high strength polycrystalline Ni-rich Ni{sub 3}Al alloy produced by EB-PVD

    Energy Technology Data Exchange (ETDEWEB)

    Sun, J.Y.; Pei, Y.L.; Li, S.S.; Zhang, H.; Gong, S.K., E-mail: gongsk@buaa.edu.cn

    2014-11-25

    Highlights: • High strength and high ductility of polycrystalline Ni-rich Ni{sub 3}Al alloy sheets were produced. • The elongation could be enhanced from ∼0.5% to ∼14.6% by microstructural control. • The fracture strength (∼820 MPa) was enhanced by the precipitation strengthening. • This work provides a general processing for repairing the worn single crystal blades. - Abstract: A 300 μm Ni-rich Ni{sub 3}Al sheet was produced by electron beam physical vapor deposition (EB-PVD) and followed by different heat treatments to obtain fine γ′/γ two-phase structures with large elongation. Tensile testing was performed at room-temperature, and the corresponding mechanisms were investigated in detail. Results indicated that the as-deposited Ni{sub 3}Al alloy exhibited non-equilibrium directional columnar crystal, and transited to equiaxed crystal with uniformly distributed tough γ phase after heat treatment. Meanwhile, the fracture mechanism transited from brittleness to a mixture of ductility and brittleness modes. With an appropriate heat treatment, high strength (ultimate tensile strength obtained 828 MPa) and high ductility (elongation obtained 14.6%) Ni{sub 3}Al alloy has been achieved, which was due to the mesh network microstructure. A series of transmission electron microscope (TEM) characterizations confirmed that the increasing flow stress of Ni{sub 3}Al alloy was attributed to the cubical secondary γ′ phase precipitates (25–50 nm) within the γ phase. This work provides a potential strategy for repairing the worn tip of single crystal engine blades using Ni-rich Ni{sub 3}Al alloy by EB-PVD.

  5. TEM study of pseudo-twin in an off-stoichiometric Ni{sub 2}MnGa

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, Hidefumi [Department of Materials Science and Engineering, Graduate School of Engineering, Osaka University, 2-1, Yamada-oka, Suita, Osaka 565-0871 (Japan); Department of Mechanical and Systems Engineering, Faculty of Science and Technology, Ryukoku University, Yokotani 1-5, Seta Oe-cyo, Otsu, Shiga 520-2194 (Japan); Taguchi, Eiji [Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Fukuda, Takashi; Kakeshita, Tomoyuki [Department of Materials Science and Engineering, Graduate School of Engineering, Osaka University, 2-1, Yamada-oka, Suita, Osaka 565-0871 (Japan)

    2013-11-15

    Highlights: ► In Ni–Mn–Ga alloy which has transformation temperature around room temperature, it is difficult to observe in static by using transmission electron microscope. ► In a condition that the magnetic field in TEM hardly influences to the sample transformation, the TEM bright field micrograph of uniform texture in Ni{sub 55.5}Mn{sub 20.0}Ga{sub 24.5} (T{sub M} at 360 K) was captured along [0 1 0] and [1 1 1] direction. ► This texture was revealed that a twin-like banded structure composed of two orthorhombic lattice. ► The precisely measuring of angles subtended by diffraction spots on the [1 1 1] diffraction pattern revealed that two crystals which constructed a twin-like structure have different crystal structure in a microscopic region. -- Abstract: We have investigated twin-like microstructure of the martensite phase in a Ni{sub 55.5}Mn{sub 20.0}Ga{sub 24.5} (at.%) alloy by using transmission electron microscope (TEM). The bright field image of the martensite phase showed striped microstructure composed of two crystals. Assuming that both crystals have orthorhombic structures, we calculated the axial ratios c/a and b/a from the 1 1 1 diffraction patterns by using angles between reflections. As a result, we found that the axial ratios of one crystal are slightly different from those of the other crystal. This result implies that the twin-like (striped) microstructure of Ni{sub 55.5}Mn{sub 20.0}Ga{sub 24.5} is not true twin but is pseudo-twin.

  6. Processing and operating experience of Ni{sub 3}Al-based intermetallic alloy IC-221M

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; Santella, M.L. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Orth, J.E. [United Defense LP, Anniston, AL (United States)

    1997-12-01

    The cast Ni{sub 3}Al-based intermetallic alloy IC-221M is the most advanced in its commercial applications. This paper presents progress made for this alloy in the areas of: (1) composition optimization; (2) melting process development; (3) casting process; (4) mechanical properties; (5) welding process, weld repairs, and thermal aging response; and (6) applications. This paper also reviews the operating experience with several of the components. The projection for future growth in the applications of nickel aluminide is also discussed. (orig.) 22 refs.

  7. Magnetic sublattices in Np{sub 2}Co{sub 17} and Np{sub 2}Ni{sub 17}

    Energy Technology Data Exchange (ETDEWEB)

    Colineau, E., E-mail: eric.colineau@ec.europa.eu; Hen, A. [Institute for Transuranium Elements (ITU), European Commission, Joint Research Centre (JRC) (Germany); Sanchez, J.-P. [CEA, INAC-SPSMS (France); Griveau, J.-C.; Magnani, N.; Eloirdi, R. [Institute for Transuranium Elements (ITU), European Commission, Joint Research Centre (JRC) (Germany); Halevy, I. [Ben Gurion University, Nuclear Engineering Department (Israel); Gaczyński, P. [Institute for Transuranium Elements (ITU), European Commission, Joint Research Centre (JRC) (Germany); Orion, I. [Ben Gurion University, Nuclear Engineering Department (Israel); Shick, A. B. [Institute of Physics, ASCR (Czech Republic); Caciuffo, R. [Institute for Transuranium Elements (ITU), European Commission, Joint Research Centre (JRC) (Germany)

    2016-12-15

    Rare-earth-based compounds R{sub 2}T{sub 17} (R=Rare earth; T=Transition metal) have been extensively studied and developed for applications as permanent magnets. The actinide-based analogues, however, are much less documented and we report here about the magnetic properties of Np{sub 2}Co{sub 17} and Np{sub 2}Ni{sub 17}, as inferred from {sup 237}Np Mössbauer spectroscopy, the best resonance in actinides, and specific heat.

  8. Microstructure and low-temperature phase transition in Ni{sub 2}FeGa Heusler alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liu Libao [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China) and Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China) and Harbin Institute of Technology at Weihai, Weihai 264209 (China)]. E-mail: lbliu@blem.ac.cn; Fu Shiyou [Harbin Institute of Technology at Weihai, Weihai 264209 (China); Liu Zhuhong [Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Wu Guangheng [Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Sun Xiudong [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Li Jianqi [Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)

    2006-11-30

    The microstructure features and structural phase transition in the Ni{sub 2}FeGa alloy has been systematically investigated by means of transmission electron microscopy (TEM). A number of ordered states have been observed at room temperature; certain short-range orders are found to be in metastable states which are temperature sensitive and become invisible when annealed. In situ cooling TEM observations revealed evident structural changes along with the martensitic transition with T {sub c}{approx}145 K. Low-temperature microstructure domains, superstructures and variations of monoclinic distortion have been analyzed in detail.

  9. Orientation dependence of the yield stress and work-hardening rate of Ni{sub 3}Ge at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Starenchenko, V.A.; Kozlov, E.V. [Tomsk State University of Architecture and Building, Department of Physics, 634003 Tomsk, sq. Solyanaya 2 (Russian Federation); Solov' eva, Yu.V. [Tomsk State University of Architecture and Building, Department of Physics, 634003 Tomsk, sq. Solyanaya 2 (Russian Federation)], E-mail: j_sol@mail.ru; Abzaev, Yu.A.; Koneva, N.A. [Tomsk State University of Architecture and Building, Department of Physics, 634003 Tomsk, sq. Solyanaya 2 (Russian Federation)

    2008-06-15

    The orientation dependence of the yield stress anomaly of Ni{sub 3}Ge single crystals with the L1{sub 2} structure was investigated by compression. The measurements were carried out in the 4.2-1000 K temperature interval for three single crystal orientations, [0 0 1], [1-bar39] and [2-bar34]. The dislocation structure was studied by transmission electron microscopy. Quantitative measurements of different parameters of the dislocation structure were carried out. The total dislocation density, {rho}, was determined for different temperatures at various strains up to sample fracture. The temperature dependencies of the friction stress and the dislocation-dislocation interaction parameter were also obtained.

  10. The structure and surface energy of Ni{sub 80}Fe{sub 20} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yuan-Tsung, E-mail: ytchen@yuntech.edu.tw; Chen, Chin-Wu; Wu, Te-Ho

    2015-10-01

    Highlights: • X-ray diffraction patterns indicated NiFe thin films exhibited a face-centred cubic (FCC) structural. • NiFe films were more crystalline after postannealing treatment than they were after RT treatment. • NiFe films formed a contact angle of <90°, which indicated that the NiFe films were hydrophilic. • The surface energy was associated with the crystallinity of the thin films. • NiFe thin films exhibit low surface-energy characteristics that can produce a self-cleaning effect. - Abstract: In this study, NiFe thin films were deposited on a glass substrate at room temperature (RT) or postannealed at 150 and 250 °C for 1 h; the Ni{sub 80}Fe{sub 20} films were 300–1500 Å thick. The structure, surface energy, and average contact angle properties of the NiFe thin films were investigated. X-ray diffraction (XRD) results demonstrated that the NiFe thin films exhibited a face-centred cubic (FCC) structural state. The XRD results also revealed that the NiFe films were more crystalline after post-annealing treatment than they were after RT treatment alone, suggesting that the NiFe crystalline structure exhibited FCC (1 1 1) texturing. The NiFe films formed a contact angle of <90° with the test liquids water and diiodomethane, which indicated that the NiFe films were hydrophilic. The surface energy of the NiFe thin films decreased when post-annealing treatment was used and their thickness was increased from 60.4 to 47.9 mJ/mm{sup 2}, suggesting that the surface energy was associated with the crystallinity of the thin films. Therefore, these NiFe thin films exhibit low surface-energy characteristics that can produce a self-cleaning effect.

  11. Timelike gamma* N -> Delta form factors and Delta Dalitz decay

    CERN Document Server

    Ramalho, G

    2012-01-01

    We extend a covariant model, tested before in the spacelike region for the physical and lattice QCD regimes, to a calculation of the gamma* N -> Delta reaction in the timelike region, where the square of the transfered momentum, q^2, is positive (q^2>0). We estimate the Dalitz decay Delta -> Ne+e- and the Delta distribution mass distribution function. The results presented here can be used to simulate the NN -> NNe+e- reactions at moderate beam kinetic energies.

  12. Effect of pressure and high magnetic field on phase transitions and magnetic properties of Ni{sub 1.92}Mn{sub 1.56}Sn{sub 0.52} and Ni{sub 2}MnSn Heusler compounds

    Energy Technology Data Exchange (ETDEWEB)

    Kaštil, J., E-mail: kastil@fzu.cz [Institute of Physics AS CR v.v.i., Na Slovance 2, 182 21 Prague 8 (Czech Republic); Kamarád, J. [Institute of Physics AS CR v.v.i., Na Slovance 2, 182 21 Prague 8 (Czech Republic); Isnard, O. [Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France); Skourski, Y. [Hochfeld-Magnetlabor Dresden (HLD), HZ Dresden-Rossendorf, D-01314 Dresden (Germany); Míšek, M.; Arnold, Z. [Institute of Physics AS CR v.v.i., Na Slovance 2, 182 21 Prague 8 (Czech Republic)

    2015-11-25

    Complex study of magnetic, magnetocaloric and structural properties of the Ni{sub 2}MnSn and Ni{sub 1.92}Mn{sub 1.56}Sn{sub 0.52} compounds was performed. The stoichiometric single-crystal of Ni{sub 2}MnSn was prepared by Czochralski method. The remarkable pressure effect on the martensitic magnetization and the martensite-austenite transition temperature T{sub M–A} was observed in the Ni{sub 1.92}Mn{sub 1.56}Sn{sub 0.52} compound. The coefficient dT{sub M–A}/dp reached value of 18 K/GPa. The already low value of martensite magnetization of Ni{sub 1.92}Mn{sub 1.56}Sn{sub 0.52} was further substantially decreased by external pressure, in contrast with pressure almost insensitive magnetization of the stoichiometric Ni{sub 2}MnSn single-crystal. The pulse magnetic field of 58 T invoked the structural transition at temperature 180 K that is of about 100 K below T{sub M–A} of Ni{sub 1.92}Mn{sub 1.56}Sn{sub 0.52} at zero field. An anomalous increase of resistivity of the compound has been observed at temperature range below T{sub M–A}, however, it does not copy the sharp change of magnetization at T{sub M–A}. The obtained results indicate the important role of interatomic distances on the magnetic ordering and electronic structure of the studied Heusler alloys and are in agreement with the Jahn-Teller mechanism of the martensitic transition in these compounds. - Highlights: • Samples of Ni{sub 1.92}Mn{sub 1.56}Sn{sub 0.52} and single crystal of Ni{sub 2}MnSn compounds were prepared. • Significant decrease of magnetization of Ni{sub 1.92}Mn{sub 1.56}Sn{sub 0.52} by pressure, dlnM/dp = −18.7·10{sup −3}GPa{sup −1}. • Negligible pressure effect on magnetization of the Ni{sub 2}MnSn single-crystal. • Large increase of T{sub M–A} under pressure, dT{sub M–A}/dp = 18 K/GPa in the Ni{sub 1.92}Mn{sub 1.56}Sn{sub 0.52}. • High magnetoresistance and moderate MCE were measured on Ni{sub 1.92}Mn{sub 1.56}Sn{sub 0.52}.

  13. Microstructure characterization of ball-milled Ni{sub 50}Co{sub 50} alloy by Rietveld method

    Energy Technology Data Exchange (ETDEWEB)

    Loudjani, Nadia; Bensebaa, Nadia; Alleg, Safia; Djebbari, Chaffia [Laboratoire de Magnetisme et de Spectroscopie des Solides, Departement de Physique, Faculte des Sciences, Universite Badji Mokhtar, Annaba (Algeria); Greneche, Jean Marc [Laboratoire de Physique de l' Etat Condense - UMR 6087, Universite du Maine, Faculte des Sciences, Le Mans (France)

    2011-09-15

    A nanostructured Ni{sub 50}Co{sub 50} mixture was prepared by high-energy ball milling in a planetary ball mill (Frisch P7) under an argon atmosphere. Scanning electron microscopy and X-ray diffraction (XRD) have been used to study the morphology of the powder particles, microstructure, and structure evolution. Detailed analysis of the XRD patterns was performed by the MAUD program, which is based on the Rietveld method. It reveals the complete vanishing of the Co peaks after 3 h of milling, indicating the allotropic transformation of Co from hcp to fcc structure. The reciprocal dissolution of the elemental Ni and Co powders leads to the formation of a heterogeneous solid solution with two structures: fcc-Ni(Co) and fcc-Co(Ni) with relative fractions of about 76 and 20%, respectively, after 24 h of milling. Microstructural parameters such as lattice parameter, crystallite size, microstrains, dislocation density, and stacking faults have been deduced from the best Rietveld refinements. The formation kinetics of nanostructured Ni{sub 50}Co{sub 50} mixture can be described by a lower Avrami parameter, n, close to 0.34. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Inter-diffusion and its correlation with dynamical cross correlation in liquid Ce{sub 80}Ni{sub 20}

    Energy Technology Data Exchange (ETDEWEB)

    Hu, J.L.; Zhong, L.X.; Zhu, C.A.; Zhang, B. [Hefei University of Technology, School of Materials Science and Engineering and Anhui Provincial Key Lab of Functional Materials and Devices, Hefei (China)

    2017-03-15

    We reported the inter-diffusion coefficients in liquid Ce{sub 80}Ni{sub 20} measured by the sliding cell technique. Combined with the self-diffusion data of Ni measured by quasi-elastic neutron scattering in the literature, it was found that the relationship between inter-diffusion and self-diffusion in liquid Ce{sub 80}Ni{sub 20} was strongly deviated from the standard Darken equation with an abnormally small dynamical cross correlation factor S (the so called Manning factor) in a range of 0.6-0.8, less than unity in standard systems. Through the calculated distinct diffusion coefficient and its deviation from the standard one, it was discovered that the small S value was directly originated from enhanced distinct diffusion between Ce and Ni atoms and reduced distinct diffusion between Ni and Ni atoms. Because the inter-atomic interaction was not considered in the standard liquids, the present small S factor and intrinsic distinct diffusion coefficients were believed to be resulted from the chemical interaction between Ce and Ni in the liquid. The results provide new evidence of the dynamic cross correlation in liquid diffusion, and thus shed light on the understanding of the correlation between dynamics and structure in liquid alloys. (orig.)

  15. Microstructure evolution and hardness change in ordered Ni{sub 3}V intermetallic alloy by energetic ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, A.; Kaneno, Y. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Semboshi, S. [Kansai-Center, Institute for Materials Research, Tohoku University, Sakai, Osaka 599-8531 (Japan); Yoshizaki, H. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Saitoh, Y. [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency Takasaki, Gunma 370-1292 (Japan); Okamoto, Y. [Quantum Beam Science Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Iwase, A., E-mail: iwase@mtr.osakafu-u.ac.jp [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan)

    2014-11-01

    Ni{sub 3}V bulk intermetallic compounds with ordered D0{sub 22} structure were irradiated with 16 MeV Au ions at room temperature. The irradiation induced phase transformation was examined by means of the transmission electron microscope (TEM), the extended X-ray absorption fine structure measurement (EXAFS) and the X-ray diffraction (XRD). We also measured the Vickers hardness for unirradiated and irradiated specimens. The TEM observation shows that by the Au irradiation, the lamellar microstructures and the super lattice spot in diffraction pattern for the unirradiated specimen disappeared. This TEM result as well as the result of XRD and EXAFS measurements means that the intrinsic D0{sub 22} structure of Ni{sub 3}V changes into the A1 (fcc) structure which is the lattice structure just below the melting point in the thermal equilibrium phase diagram. The lattice structure change from D0{sub 22} to A1 (fcc) accompanies a remarkable decrease in Vickers microhardness. The change in crystal structure was discussed in terms of the thermal spike and the sequential atomic displacements induced by the energetic heavy ion irradiation.

  16. Angular dependence of ferromagnetic resonance in Tb-doped Ni{sub 80}Fe{sub 20} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Chen [Physics Department, Southeast University, Nanjing 211189 (China); Zhang, Dong [Physics Department, Southeast University, Nanjing 211189 (China); School of Physics Science and Information Engineering, Liaocheng University, Liaocheng 252059 (China); Wang, Yukun [Physics Department, Southeast University, Nanjing 211189 (China); Huang, Haibo [College of Material Science and Engineering, Southeast University, Nanjing 211189 (China); Zhai, Ya, E-mail: yazhai@seu.edu.cn [Physics Department, Southeast University, Nanjing 211189 (China); Zhai, Hongru [National Laboratory of Solid Microstructures, Nanjing University, Nanjing 210093 (China)

    2014-06-15

    Highlights: • The soft magnetic properties of Ni{sub 80}Fe{sub 20} films with Tb dopants up to 8.4% are kept. • The different mechanisms of FMR linewidth are separated and studied. • Magnetic anisotropy constants, Lande g factor, etc. are discussed quantitatively. • The Gilbert damping is increased by more than 50 times with 8.4% of Tb dopants. - Abstract: The mechanisms of angular dependence of ferromagnetic resonance (FMR) linewidth of dilute Tb doping in Ni{sub 80}Fe{sub 20} thin films are investigated by experimental approach and the theoretical fitting by considering the contributions from intrinsic spin–orbit coupling, two-magnon scattering and inhomogeneous broadening. It is shown that the damping coefficient α, by intrinsic contribution extracted from FMR linewidth, is increased by more than 50 times as the Tb concentration increases to 8.4%, indicating that the spin–orbit coupling of this system increases with the introduction of Tb impurities. The magnetic anisotropy constants K{sub 1} and K{sub 2} are obtained and show an increasing trend from negative to positive, which implies that the Tb dopants could enhance the perpendicular anisotropy.

  17. Crystal structure and magnetic properties of Dy{sub 11}Ni{sub 4}In{sub 9}

    Energy Technology Data Exchange (ETDEWEB)

    Tyvanchuk, Yu. [Analytical Chemistry Department, Ivan Franko National University of Lviv, Kyryla and Mephodiya 6, 79005 Lviv (Ukraine); Baran, S., E-mail: stanislaw.baran@uj.edu.pl [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30-059 Kraków (Poland); Duraj, R. [Institute of Physics, Technical University of Cracow, Podchorążych 1, PL-30-084 Kraków (Poland); Kalychak, Ya.M. [Analytical Chemistry Department, Ivan Franko National University of Lviv, Kyryla and Mephodiya 6, 79005 Lviv (Ukraine); Przewoźnik, J. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Department of Solid State Physics, al. Mickiewicza 30, 30-059 Kraków (Poland); Szytuła, A. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30-059 Kraków (Poland)

    2014-02-25

    Highlights: • Crystal structure of the new Dy{sub 11}Ni{sub 4}In{sub 9} rare earth intermetallic is reported. • The compound shows magnetic ordering below 86 K. • Isothermal magnetization curves indicate complex magnetic properties. -- Abstract: The work reports on the crystal structure and magnetic properties of Dy{sub 11}Ni{sub 4}In{sub 9}. The compound crystallizes in the orthorhombic Nd{sub 11}Pd{sub 4}In{sub 9}-type structure (space group Cmmm) with Dy atoms occupying five nonequivalent Wyckoff positions. Temperature dependences of specific heat as well as ac and dc magnetic susceptibility show a ferromagnetic-like ordering with T{sub C} = 86 K and additional magnetic transitions at lower temperatures. The fit to the reciprocal susceptibility data above 180 K, in a paramagnetic state, follows the Curie–Weiss law and provides μ{sub eff} = 10.86 μ{sub B}/Dy-atom (close to the theoretical value of 10.65 μ{sub B} for the free Dy{sup 3+} ion) and a positive paramagnetic Curie temperature θ{sub p} = 28 K. Ni atoms are most likely nonmagnetic. The existence of a hysteresis loop below T{sub C} indicates a change of magnetic properties. The coercivity field is large at low temperatures (50 kOe at 1.9 K) and decreases gradually with increasing temperature down to 0.01 kOe at 75 K.

  18. Magnetic properties of Fe{sub 20} Ni{sub 80} antidots: Pore size and array disorder

    Energy Technology Data Exchange (ETDEWEB)

    Palma, J.L., E-mail: juan.palma.s@usach.cl [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Gallardo, C. [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Spinu, L.; Vargas, J.M. [Advanced Material Research Institute (AMRI) and Department of Physics, University of New Orleans, New Orleans, LA 70148 (United States); Dorneles, L.S. [Departamento de Fisica, Universidade Federal de Santa Maria UFSM, Av. Roraima 1000, Camobi, Santa Maria, RS 97105-900 (Brazil); Denardin, J.C.; Escrig, J. [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avda. Ecuador 3493, 917-0124 Santiago (Chile)

    2013-10-15

    Magnetic properties of nanoscale Fe{sub 20}Ni{sub 80} antidot arrays with different hole sizes prepared on top of nanoporous alumina membranes have been studied by means of magnetometry and micromagnetic simulations. The results show a significant increase of the coercivity as well as a reduction of the remanence of the antidot arrays, as compared with their parent continuous film, which depends on the hole size introduced in the Fe{sub 20}Ni{sub 80} thin film. When the external field is applied parallel to the antidots, the reversal of magnetization is achieved by free-core vortex propagation, whereas when the external field is applied perpendicular to the antidots, the reversal occurs through a process other than the coherent rotation (a maze-like pattern). Besides, in-plane hysteresis loops varying the angle show that the degree of disorder in the sample breaks the expected hexagonal symmetry. - Highlights: • Magnetic properties are strongly influenced by the pore diameter of the samples. • Coercive fields for antidots are higher than the values for the continuous film. • Disorder breaks the hexagonal symmetry of the sample. • Each hole acts as a vortex nucleation point. • Antidots have unique properties that allow them to be used in applications.

  19. Delta II commercial space transportation

    Science.gov (United States)

    Meyers, J. F.

    1988-07-01

    Delta II is an upgraded variant of the Delta family of launch vehicles that has been in use by NASA since 1960. Among the design improvements incorporated by Delta II is a cryogenic-propellant second stage, a 2.89-m diameter satellite-protecting nose fairing, graphite/epoxy solid rocket motor cases, and 12:1 main engine expansion nozzle. The manufacturer/operator offers Delta II customers a dedicated, single satellite launch capability fully tailored to the given spacecraft's unique mission requirements.

  20. Selective leaching and surface properties of Ti{sub 50}Ni{sub 50−x}Cu{sub x} (x = 0–20 at.%) shape memory alloys for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Shih-Hang, E-mail: shchang@niu.edu.tw; Chiu, Wei-Chen

    2015-01-01

    Highlights: • TiNiCu alloys show higher leaching rates of Ni and Cu ions than those of TiNi alloys. • NiO and Cu{sub 2}O oxides caused a deterioration of the protection of passive TiO{sub 2} films. • Surface modifications are needed to avoid the toxicity risk caused by released ions. - Abstract: This study investigated the selective leaching and surface characteristics of Ti{sub 50}Ni{sub 50} and Ti{sub 50}Ni{sub 50−x}Cu{sub x} (x = 5, 10, and 20) shape memory alloys (SMAs) by employing inductively coupled plasma mass spectrometry, electrochemical tests, and X-ray photoelectron spectroscopy. The experimental results revealed that Ti{sub 50}Ni{sub 50−x}Cu{sub x} SMAs exhibited corrosion-resistance properties that were more favorable than those of Ti{sub 50}Ni{sub 50} SMAs, whereas the concentrations of the Ni and Cu ions selectively leached from Ti{sub 50}Ni{sub 50−x}Cu{sub x} SMAs were considerably higher than those of Ni and Cu ions selectively leached from Ti{sub 50}Ni{sub 50} SMAs. Ti{sub 50}Ni{sub 50−x}Cu{sub x} SMAs exhibited higher selective leaching rates of Ni and Cu ions than those of Ti{sub 50}Ni{sub 50} SMAs, because the NiO and Cu{sub 2}O oxides that formed on the surface caused a deterioration of the uniformity and protection of the passive TiO{sub 2} films. Although Ti{sub 50}Ni{sub 50−x}Cu{sub x} SMAs exhibited unique properties that are superior to those of TiNi binary SMAs in particular biomedical applications, appropriate surface modifications are necessary to avoid the risk of toxicity caused by the released Ni and Cu ions.

  1. Thermodynamic properties and solidification kinetics of intermetallic Ni{sub 7}Zr{sub 2} alloy investigated by electrostatic levitation technique and theoretical calculations

    Energy Technology Data Exchange (ETDEWEB)

    Li, L. H.; Hu, L.; Yang, S. J.; Wang, W. L.; Wei, B., E-mail: bbwei@nwpu.edu.cn [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China)

    2016-01-21

    The thermodynamic properties, including the density, volume expansion coefficient, ratio of specific heat to emissivity of intermetallic Ni{sub 7}Zr{sub 2} alloy, have been measured using the non-contact electrostatic levitation technique. These properties vary linearly with temperature at solid and liquid states, even down to the obtained maximum undercooling of 317 K. The enthalpy, glass transition, diffusion coefficient, shear viscosity, and surface tension were obtained by using molecular dynamics simulations. Ni{sub 7}Zr{sub 2} has a relatively poor glass forming ability, and the glass transition temperature is determined as 1026 K. The inter-diffusivity of Ni{sub 7}Zr{sub 2} alloy fitted by Vogel–Fulcher–Tammann law yields a fragility parameter of 8.49, which indicates the fragile nature of this alloy. Due to the competition of increased thermodynamic driving force and decreased atomic diffusion, the dendrite growth velocity of Ni{sub 7}Zr{sub 2} compound exhibits double-exponential relationship to the undercooling. The maximum growth velocity is predicted to be 0.45 m s{sup −1} at the undercooling of 335 K. Theoretical analysis reveals that the dendrite growth is a diffusion-controlled process and the atomic diffusion speed is only 2.0 m s{sup −1}.

  2. Electronic structure and magnetism in Ni{sub 0.0625}Zn{sub 0.9375}O: An ab initio study

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, Rafael Gonzalez [GFMC, Departamento de Fisica, Universidad del Norte, A. A. 1569, Barranquilla (Colombia) and GEMA, Departamento de Fisica, Universidad Nacional de Colombia, A. A. 5997, Bogota (Colombia)], E-mail: rgonzalezh@unal.edu.co; Perez, William Lopez [GFMC, Departamento de Fisica, Universidad del Norte, A. A. 1569, Barranquilla (Colombia); Jairo Arbey Rodriguez, M. [GEMA, Departamento de Fisica, Universidad Nacional de Colombia, A. A. 5997, Bogota (Colombia)], E-mail: jarodriguezm@unal.edu.co

    2009-09-15

    We carry out first principles spin polarized calculations in order to study the electronic structure and magnetism of Ni{sub 0.0625}Zn{sub 0.9375}O compound using density functional theory (DFT) within a plane-wave ultrasoft pseudopotential scheme. The electronic properties of Ni{sub x}Zn{sub 1-x}O at a concentration of 6.25% are analyzed using a 2x2x2 wurtzite ZnO supercell. We optimize the lattice constants of ZnO pure and Ni{sub 0.0625}Zn{sub 0.9375}O. We observe that if one Zn atom is substituted by one Ni atom in the wurtzite ZnO supercell, the lattice parameters decrease slightly some thousandths of angstrom. We also find a stable ferromagnetic state in Ni doped ZnO with a total magnetization of 2.04{mu}{sub B} per supercell. Using the optimized lattice parameters, we have calculated the band structure and density of states of Ni{sub 0.0625}Zn{sub 0.9375}O.

  3. Electric and magnetic properties of Al{sub 86}Ni{sub 8}R{sub 6} (R=Sm, Gd, Ho) alloys in liquid and amorphous states

    Energy Technology Data Exchange (ETDEWEB)

    Sidorov, V. [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Ural Federal University, Ekaterinburg (Russian Federation); Svec, P.; Svec, P.; Janickovic, D. [Institute of Physics SAS, Bratislava (Slovakia); Mikhailov, V. [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Sidorova, E. [Plekhanov Russian University of Economics, Moscow (Russian Federation); Son, L. [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Ural Federal University, Ekaterinburg (Russian Federation)

    2016-06-15

    Electrical resistivity and magnetic susceptibility of Al{sub 86}Ni{sub 8}Sm{sub 6}, Al{sub 86}Ni{sub 8}Gd{sub 6} and Al{sub 86}Ni{sub 8}Ho{sub 6} alloys are studied in a wide temperature range including amorphous, crystalline and liquid states. The negative value of resistivity temperature coefficient in amorphous ribbons is explained by the structural separation starting much before the beginning of their crystallization. The effective magnetic moments per Gd and Ho atoms are found to be essentially lower than for R{sup 3+} ions. The results are discussed in supposition of directed bonds between rare earth and aluminum atoms. - Highlights: • Electric and magnetic properties of Al{sub 86}Ni{sub 8}R{sub 6} alloys are studied experimentally. • The negative value of rtc in amorphous ribbons is explained. • The effective magnetic moments per Gd and Ho are found to be lower than for R{sup 3+} ions.

  4. Synthesis and properties of the Mg{sub 2}Ni{sub 0.5}Co{sub 0.5}H{sub 4.4} hydride

    Energy Technology Data Exchange (ETDEWEB)

    Verbovytskyy, Yu. [Physico-Mechanical Institute, NAS of Ukraine, 5 Naukova str., 79601 Lviv (Ukraine); Zhang, J.; Cuevas, F.; Paul-Boncour, V. [Institut de Chimie et des Materiaux de Paris Est, CMTR, UMR 7182, CNRS-UPEC, 2-8 rue H. Dunant, 94320 Thiais (France); Zavaliy, I., E-mail: zavaliy@ipm.lviv.ua [Physico-Mechanical Institute, NAS of Ukraine, 5 Naukova str., 79601 Lviv (Ukraine)

    2015-10-05

    Graphical abstract: Crystal structure of the Mg{sub 2}Ni{sub 0.5}Co{sub 0.5}H{sub 4.4} hydride. - Highlights: • Preparation of the Mg{sub 2}Ni{sub 0.5}Co{sub 0.5}H{sub 4.4} hydride by reactive ball milling. • Crystal structure determination by X-ray powder diffraction. • Electrochemical studies of the ball milled MH/Ni electrodes. - Abstract: The Mg{sub 2}Ni{sub 0.5}Co{sub 0.5}H{sub 4.4} hydride with a grain size of 16 nm was prepared by reactive ball milling. Its crystal structure was studied by X-ray powder diffraction. A tetragonal Mg{sub 2}CoH{sub 5} structure type was suggested for the obtained hydride. The decomposition temperature of the Mg{sub 2}Ni{sub 0.5}Co{sub 0.5}H{sub 4.4} phase was observed at 213 °C. Electrochemical measurements as negative electrode of Ni–MH battery were also performed. Significant improvements can be made by ball-milling the hydride with nickel powder.

  5. Phenotypic expressions of CCR5-Delta 32/Delta 32 homozygosity

    NARCIS (Netherlands)

    Nguyen, GT; Carrington, M; Beeler, JA; Dean, M; Aledort, LM; Blatt, PM; Cohen, AR; DiMichele, D; Eyster, ME; Kessler, CM; Konkle, B; Leissinger, C; Luban, N; O'Brien, SJ; Goedert, JJ; O'Brien, TR

    1999-01-01

    Objective: As blockade of CC-chemokine receptor 5 (CCR5) has been proposed as therapy for HIV-1, we examined whether the CCR5-Delta 32/Delta 32 homozygous genotype has phenotypic expressions other than those related to HIV-1. Design: Study subjects were white homosexual men or men with hemophilia

  6. Phenotypic expressions of CCR5-Delta 32/Delta 32 homozygosity

    NARCIS (Netherlands)

    Nguyen, GT; Carrington, M; Beeler, JA; Dean, M; Aledort, LM; Blatt, PM; Cohen, AR; DiMichele, D; Eyster, ME; Kessler, CM; Konkle, B; Leissinger, C; Luban, N; O'Brien, SJ; Goedert, JJ; O'Brien, TR

    1999-01-01

    Objective: As blockade of CC-chemokine receptor 5 (CCR5) has been proposed as therapy for HIV-1, we examined whether the CCR5-Delta 32/Delta 32 homozygous genotype has phenotypic expressions other than those related to HIV-1. Design: Study subjects were white homosexual men or men with hemophilia wh

  7. Peat compaction in deltas : implications for Holocene delta evolution

    NARCIS (Netherlands)

    van Asselen, S.|info:eu-repo/dai/nl/304838101

    2010-01-01

    Many deltas contain substantial amounts of peat, which is the most compressible soil type. Therefore, peat compaction potentially leads to high amounts of subsidence in deltas. The main objective of this research was to quantify subsidence due to peat compaction in Holocene fluvial-deltaic settings

  8. Phenotypic expressions of CCR5-Delta 32/Delta 32 homozygosity

    NARCIS (Netherlands)

    Nguyen, GT; Carrington, M; Beeler, JA; Dean, M; Aledort, LM; Blatt, PM; Cohen, AR; DiMichele, D; Eyster, ME; Kessler, CM; Konkle, B; Leissinger, C; Luban, N; O'Brien, SJ; Goedert, JJ; O'Brien, TR

    1999-01-01

    Objective: As blockade of CC-chemokine receptor 5 (CCR5) has been proposed as therapy for HIV-1, we examined whether the CCR5-Delta 32/Delta 32 homozygous genotype has phenotypic expressions other than those related to HIV-1. Design: Study subjects were white homosexual men or men with hemophilia wh

  9. Preparation of nickel and Ni{sub 3}Sn nanoparticles via extension of conventional citric acid and ethylene diamine tetraacetic acid mediated sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Li, Pingyun, E-mail: lpyljr@126.com; Deng, Guodong; Guo, Xiaode; Liu, Hongying; Jiang, Wei; Li, Fengsheng

    2016-05-25

    This work aims to extend the application field of sol–gel process from conventional oxides, carbides, sulfides to metallic nanocrystalline materials. Metallic ions were coordinated with chelating agents of citric acid (CA) and ethylene diamine tetraacetic acid (EDTA) in aqueous solution. Then the solutions were dried at 383 K, resulting in the formation of sol and gel. Heating treatments of dried gels were then carried out with protection of N{sub 2} atmosphere. Ni and Ni{sub 3}Sn alloy nanoparticles were obtained by this sol–gel method in the range of 623–823 K. The as-prepared Ni and Ni{sub 3}Sn alloy nanoparticles have average grain sizes of 15 and 30 nm, and have face-centred-cubic (fcc) crystalline phase. Our results provide new insight into the application of conventional sol–gel method. - Graphical abstract: Sol–gel method is conventionally applied to prepare oxides, carbides, and sulfides. In this work, the application field of sol–gel method is extended to metallic nanoparticles. By using citric acid (CA) and ethylene diamine tetraacetic acid (EDTA) mediated sol–gel method, metallic Ni (a and c) and Ni{sub 3}Sn (b and d) alloy nanoparticles can be prepared when the heating treatments are performed under N{sub 2} protecting atmosphere. The Ni and Ni{sub 3}Sn nanoparticles have face-centered-cubic (fcc) crystalline phase and ultrafine grain sizes. Diffraction peaks of (110) superstructure reflection plane of Ni{sub 3}Sn nanoparticles can also be observed in Figure b, which can be considered as direct evidence of formation of alloy crystalline phase by performing this sol–gel method. - Highlights: • Ni and Ni{sub 3}Sn alloy nanoparticles have been prepared by sol–gel processes. • Citric acid and ethylene diamine tetraacetic acid were applied as chelating agent. • Diffraction peak of superstructure reflection plane of Ni{sub 3}Sn was detected by XRD. • A novel strategy for preparation of alloy nanoparticles has been presented.

  10. Structural and electrical properties of nanostructured Ni{sub 0.25}Co{sub 0.75}MnP{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Dhaouadi, Hassouna, E-mail: dhaouadihassouna@yahoo.fr [Laboratoire des Matériaux Utiles, Institut National de Recherche et d’Analyse Physico-chimique Sidi-Thabet, 2020 Tunis (Tunisia); Kouass, Salah [Laboratoire des Matériaux Utiles, Institut National de Recherche et d’Analyse Physico-chimique Sidi-Thabet, 2020 Tunis (Tunisia); Jaouad, Najeh [Laboratoire Méthodes et Techniques d’Analyse, Institut National de Recherche et d’Analyse Physico-chimique Sidi-Thabet, 2020 Tunis (Tunisia); Ghodbane, Ouassim; Touati, Fathi [Laboratoire des Matériaux Utiles, Institut National de Recherche et d’Analyse Physico-chimique Sidi-Thabet, 2020 Tunis (Tunisia)

    2014-01-01

    Graphical abstract: - Highlights: • Nanostructured pyrophosphate Ni{sub 0.25}Co{sub 0.75}MnP{sub 2}O{sub 7} were synthesized and characterized by XRD and SEM. • The ac-conductivity at different values of temperature for Ni{sub 0.25}Co{sub 0.75}MnP{sub 2}O{sub 7} nanomaterials shows frequency independence in the lower frequency range. • Obvious improvements of the electrical conductivity and the electrochemical properties are achieved comparatively Mn{sub 2}P{sub 2}O{sub 7}. • The electrochemical behaviors of Ni{sub 0.25}Co{sub 0.75}MnP{sub 2}O{sub 7} were studied using cyclic voltammetry. - Abstract: The nanostructured pyrophosphate Ni{sub 0.25}Co{sub 0.75}MnP{sub 2}O{sub 7} was prepared. The synthesis technique was based on the hydrothermal method at 150 °C using poly-ethylene-glycol (PEG-10000) as surfactant with further calcination at 500 °C. A structural analysis of Ni{sub 0.25}Co{sub 0.75}MnP{sub 2}O{sub 7} compound was carried out by applying X-ray diffraction (XRD) and using the Rietveld method. Morphological characterizations were performed using a scanning electron microscope (SEM) and transmission electron microscopy (TEM). A comparative study of the electrical conductivity of Mn{sub 2}P{sub 2}O{sub 7} and Ni{sub 0.25}Co{sub 0.75}MnP{sub 2}O{sub 7} nanomaterials was carried out by impedance spectroscopy in the temperature range 500–680 °C. The activation energies for MnP{sub 2}O{sub 7} and Ni{sub 0.25}Co{sub 0.75}MnP{sub 2}O{sub 7} were 2.00 and 0.88 eV, respectively. Ni{sub 0.25}Co{sub 0.75}MnP{sub 2}O{sub 7} nanomaterial presents a good electric conductivity compared to Mn{sub 2}P{sub 2}O{sub 7}, due to the substitution effect. The improvement of the electronic and ionic conductivity makes the Ni{sub 0.25}Co{sub 0.75}MnP{sub 2}O{sub 7} nanomaterial possible electrode materials for rechargeable batteries. The electrochemical behaviors of Ni{sub 0.25}Co{sub 0.75}MnP{sub 2}O{sub 7} were studied using cyclic voltammetry.

  11. $\\Delta$-N Electromagnetic Transition

    CERN Document Server

    Loan, M

    1999-01-01

    The EM ratio for a free Delta electromagnetic transition is discussed within the frame work of nonrelativistic approach. Such an approach gives a good account of data for a free Delta but is less important for an intrinsically relativistic nuclear many body problem.

  12. Mida pakub Delta? / Teele Kurm

    Index Scriptorium Estoniae

    Kurm, Teele

    2011-01-01

    Politsei- ja Piirivalveamet võtab kasutusele ühise Siseministeeriumi infotehnoloogia- ja arenduskeskuse ning Webmedia AS koostööna loodud dokumendihaldussüsteemi Delta. Kust sai Delta oma nime? Projekti "Dokumendihaldussüsteemi juurutamine Siseministeeriumi haldusalas" eesmärgid

  13. Delta Electroproduction in 12-C

    Energy Technology Data Exchange (ETDEWEB)

    Steven McLauchlan

    2003-01-31

    The Delta-nucleus potential is a crucial element in the understanding of the nuclear system. Previous electroexcitation measurements in the delta region reported a Q2 dependence of the delta mass indicating that this potential is dependent on the momentum of the delta. Such a dependence is not observed for protons and neutrons in the nuclear medium. This thesis presents the experimental study of the electroexcitation of the delta resonance in 12C, performed using the high energy electron beam at the Thomas Jefferson National Accelerator Facility, and the near 4(pie) acceptance detector CLAS that enables the detection of the full reaction final state. Inclusive, semi inclusive, and exclusive cross sections were measured with an incident electron beam energy of 1.162GeV over the Q2 range 0.175-0.475 (GeV/c)2. A Q2 dependence of the delta mass was only observed in the exclusive measurements indicating that the delta-nucleus potential is affected by the momentum of the delta.

  14. Mida pakub Delta? / Teele Kurm

    Index Scriptorium Estoniae

    Kurm, Teele

    2011-01-01

    Politsei- ja Piirivalveamet võtab kasutusele ühise Siseministeeriumi infotehnoloogia- ja arenduskeskuse ning Webmedia AS koostööna loodud dokumendihaldussüsteemi Delta. Kust sai Delta oma nime? Projekti "Dokumendihaldussüsteemi juurutamine Siseministeeriumi haldusalas" eesmärgid

  15. Mackenzie River Delta, Canada

    Science.gov (United States)

    2007-01-01

    The Mackenzie River in the Northwest Territories, Canada, with its headstreams the Peace and Finley, is the longest river in North America at 4241 km, and drains an area of 1,805,000 square km. The large marshy delta provides habitat for migrating Snow Geese, Tundra Swans, Brant, and other waterfowl. The estuary is a calving area for Beluga whales. The Mackenzie (previously the Disappointment River) was named after Alexander Mackenzie who travelled the river while trying to reach the Pacific in 1789. The image was acquired on August 4, 2005, covers an area of 55.8 x 55.8 km, and is located at 68.6 degrees north latitude, 134.7 degrees west longitude. The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  16. DELTA 3D PRINTER

    Directory of Open Access Journals (Sweden)

    ȘOVĂILĂ Florin

    2016-07-01

    Full Text Available 3D printing is a very used process in industry, the generic name being “rapid prototyping”. The essential advantage of a 3D printer is that it allows the designers to produce a prototype in a very short time, which is tested and quickly remodeled, considerably reducing the required time to get from the prototype phase to the final product. At the same time, through this technique we can achieve components with very precise forms, complex pieces that, through classical methods, could have been accomplished only in a large amount of time. In this paper, there are presented the stages of a 3D model execution, also the physical achievement after of a Delta 3D printer after the model.

  17. Microstructure of epitaxial thin films of the ferromagnetic shape memory alloy Ni{sub 2}MnGa

    Energy Technology Data Exchange (ETDEWEB)

    Eichhorn, Tobias

    2011-12-09

    This work is concerned with the preparation and detailed characterization of epitaxial thin films of the Heusler compound Ni{sub 2}MnGa. This multiferroic compound is of both technological and scientific interest due to the outstanding magnetic shape memory (MSM) behavior. Huge magnetic-field-induced strains up to 10 % have been observed for single crystals close to a Ni{sub 2}MnGa composition. The effect is based on a redistribution of crystallographic twin variants of tetragonal or orthorhombic symmetry. Under the driving force of the external magnetic field twin boundaries can move through the crystal, which largely affects the macroscopic shape. The unique combination of large reversible strain, high switching frequency and high work output makes the alloy a promising actuator material. Since the MSM effect results from an intrinsic mechanism, MSM devices possess great potential for implementation in microsystems, e.g. microfluidics. So far significant strains, in response to an external magnetic field, have been observed for bulk single crystals and foams solely. In order to take advantage of the effect in applications concepts for miniaturization are needed. The rather direct approach, based on epitaxial thin films, is explored in the course of this work. This involves sample preparation under optimized deposition parameters and fabrication of freestanding single-crystalline films. Different methods to achieve freestanding microstructures such as bridges and cantilevers are presented. The complex crystal structure is extensively studied by means of X-ray diffraction. Thus, the different crystallographic twin variants that are of great importance for the MSM effect are identified. In combination with microscopy the twinning architecture for films of different crystallographic orientation is clarified. Intrinsic blocking effects in samples of (100) orientation are explained on basis of the variant configuration. In contrast, a promising twinning microstructure

  18. Anti-phase boundaries and magnetic domain structures in Ni{sub 2}MnGa-type Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Venkateswaran, S.P. [Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Nuhfer, N.T. [Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); De Graef, M. [Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States)]. E-mail: degraef@cmu.edu

    2007-05-15

    The microstructure and magnetic domain structure of austenitic Heusler Ni{sub 2}MnGa are investigated as a function of heat treatment to study the interplay of anti-phase boundaries and magnetic domain walls. Conventional electron microscopy observations on arc-melted polycrystalline samples show that anti-phase boundaries in this system are invisible for standard two-beam imaging conditions, due to the large extinction distance of the Heusler superlattice reflections. Lorentz Fresnel and Foucault observations on quenched samples reveal a wavy magnetic domain morphology, reminiscent of curved anti-phase boundaries. A close inspection of the domain images indicates that the anti-phase boundaries have a magnetization state different from that of the matrix. Fresnel image simulations for a simple magnetization model are in good agreement with the observations. Magnetic coercivity measurements show a decrease in coercivity with annealing, which correlates with the microscopy observations of reduced anti-phase boundary density for annealed samples.

  19. Martensitic transformation in rapidly solidified Heusler Ni{sub 49}Mn{sub 39}Sn{sub 12} ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Zheng Hongxing, E-mail: hxzheng@shu.edu.cn [Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Wu Dianzhen; Xue Sichuang [Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China); Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Frenzel, Jan; Eggeler, Gunther [Institute of Materials, Ruhr University Bochum, Bochum 44801 (Germany); Zhai Qijie [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China)

    2011-08-15

    In the present work, the microstructure evolution and kinetics of the martensitic transformation are investigated in as-spun and annealed ribbons of Heusler Ni{sub 49}Mn{sub 39}Sn{sub 12} using electron microscopy, X-ray diffraction and differential scanning calorimetry. Both ribbons undergo a reversible martensitic transformation during thermal cycling and the low-temperature martensite is confirmed to be a modulated four-layered orthorhombic (4O) structure through in situ cooling transmission electronic microscopy investigation. The annealing effect on the martensitic transformation behavior is discussed from the viewpoints of electron concentration, Mn-Mn interatomic distance, atomic order degree and grain size. A strong cooling-rate dependence of phase transition kinetics is found and the mechanism is analyzed. The satisfactory reproducibility obtained during thermal cycling test of this alloy ribbons offers great potential for practical applications.

  20. Width dependent transition of quantized spin-wave modes in Ni{sub 80}Fe{sub 20} square nanorings

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Chandrima; Saha, Susmita; Barman, Saswati; Barman, Anjan, E-mail: abarman@bose.res.in [Thematic Unit of Excellence on Nanodevice Technology, Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Rousseau, Olivier [CEMS-RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Otani, YoshiChika [CEMS-RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

    2014-10-28

    We investigated optically induced ultrafast magnetization dynamics in square shaped Ni{sub 80}Fe{sub 20} nanorings with varying ring width. Rich spin-wave spectra are observed whose frequencies showed a strong dependence on the ring width. Micromagnetic simulations showed different types of spin-wave modes, which are quantized upto very high quantization number. In the case of widest ring, the spin-wave mode spectrum shows quantized modes along the applied field direction, which is similar to the mode spectrum of an antidot array. As the ring width decreases, additional quantization in the azimuthal direction appears causing mixed modes. In the narrowest ring, the spin-waves exhibit quantization solely in azimuthal direction. The different quantization is attributed to the variation in the internal field distribution for different ring width as obtained from micromagnetic analysis and supported by magnetic force microscopy.

  1. Suppression of spin pumping between Ni{sub 80}Fe{sub 20} and Cu by a graphene interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Gannett, Will; Keller, Mark W., E-mail: mark.keller@nist.gov; Nembach, Hans T.; Silva, Thomas J.; Chiaramonti, Ann N. [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States)

    2015-06-07

    We compare ferromagnetic resonance measurements of Permalloy Ni{sub 80}Fe{sub 20} (Py) films sputtered onto Cu(111) films with and without a graphene (Gr) interlayer grown by chemical vapor deposition before Py deposition. A two-angle sputtering method ensured that neither Gr nor Py was degraded by the sample preparation process. We find the expected damping enhancement from spin pumping for the Py/Cu case and no detectable enhancement for the Py/Gr/Cu case. Since damping is sensitive to effects other than spin pumping, we used magnetometry to verify that differences in Py magnetostatic properties are not responsible for the difference in damping. We attribute the suppression of spin pumping in Py/Gr/Cu to the large contact resistance of the Gr/Cu interface.

  2. Size dependence of spin-wave modes in Ni{sub 80}Fe{sub 20} nanodisks

    Energy Technology Data Exchange (ETDEWEB)

    Lupo, P.; Kumar, D.; Adeyeye, A. O., E-mail: eleaao@nus.edu.sg [Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576 (Singapore)

    2015-07-15

    We investigate the radial and azimuthal spin-wave (SW) resonance modes in permalloy (Py: Ni{sub 80}Fe{sub 20}) disks at zero external magnetic field, as function of disk diameter and thickness, using broadband ferromagnetic resonance spectroscopy. We observed, from both experimental and micromagnetic simulation results that the number of SW absorption peaks increases with disk diameter. Numerically calculated SW mode profiles revealed a characteristic minimum size, which does not scale proportionately with the increasing disk diameter. We show that higher order modes could thus be avoided with an appropriate choice of the disk diameter (smaller than the minimum mode size). Moreover, based on the mode profiles, the existence of azimuthal SW modes with even number of crests or troughs can be ruled out. These results could be useful in enhancing our fundamental understanding as well as engineering of new magnonic devices.

  3. WORLD DELTAS AND THEIR EVOLUTION

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    In August 1998, an international symposium on the world deltas was held in New Orleans, Louisiana, USA. This symposium attracted discussion about more than 25 deltas from around the world with emphasis placed on those that are most densely populated and impacted by humans. Keynote papers printed details about the physical, biological, engineering and socioeconomic aspects of six deltas including the Mississippi, Nile, Ganges-Brahmaputra, Rhine-Meuse, Changjiang and Po. The main purpose of this symposium was to inform scientists, engineers and decision-makers about information that is currently available and to provide them a basis for working in such environments.

  4. Dynamical Casimir effect with $\\delta-\\delta^{\\prime}$ mirrors

    CERN Document Server

    Silva, Jeferson Danilo L; Alves, Danilo T

    2016-01-01

    We calculate the spectrum and the total rate of created particles for a real massless scalar field in $1+1$ dimensions, in the presence of a partially transparent moving mirror simulated by a Dirac $\\delta-\\delta^{\\prime}$ point interaction. We show that, strikingly, a partially reflecting mirror can produce a larger number of particles in comparison with a perfectly reflecting one. In the limit of a perfect mirror, our formulas recover those found in the literature for the Robin boundary condition.

  5. Large magnetic entropy change and relative cooling power in the rare earth intermetallic HoCo{sub 0.25}Ni{sub 1.75} compound

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, Rajib [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India); Nirmala, R., E-mail: nirmala@physics.iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 600 036 (India); Arout Chelvane, J. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Malik, S.K. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59082 -970 (Brazil)

    2015-11-01

    Magnetic and magnetocaloric properties of cubic Laves phase rare earth intermetallic HoCo{sub 0.25}Ni{sub 1.75} compound have been investigated. Magnetization measurements show that HoCo{sub 0.25}Ni{sub 1.75} orders ferromagnetically at 22 K (T{sub C}). The magnetization vs field (M–μ{sub 0}H) isotherm at 2 K shows negligible hysteresis. The isothermal magnetic entropy change (ΔS{sub m}) is calculated from the measured M–µ{sub 0}H data near T{sub C.} The maximum value of ΔS{sub m}, ΔS{sub m}{sup max}, is about −18.9 J/kg-K at T{sub C} for a field change of 5 T with a refrigerant capacity of 572 J/kg. The material exhibits large ΔS{sub m}{sup max} of −9.4 J/kg-K even for a low field change of 2 T. Universal master curve is constructed by rescaling ΔS{sub m} vs T curves for various fields to confirm the second order nature of the magnetic transition at T{sub C}. Large ΔS{sub m}{sup max} value, wide temperature span of cooling and high relative cooling power make HoCo{sub 0.25}Ni{sub 1.75} a potential magnetic refrigerant for low temperature applications such as hydrogen liquefaction. - Highlights: • A large magnetocaloric effect is observed in Laves phase HoCo{sub 0.25}Ni{sub 1.75} compound. • The isothermal magnetic entropy change ΔS{sub m} vs T of HoCo{sub 0.25}Ni{sub 1.75} is broad near T{sub C}. • The magnetization vs field isotherms have negligible hysteresis. • A large relative cooling power is realized in HoCo{sub 0.25}Ni{sub 1.75}. • Universal master curve is constructed by rescaling ΔS{sub m} vs T data.

  6. Magnetic, thermal and electronic properties of Ce{sub 11}Ni{sub 4}In{sub 9} and CeNi{sub 9}In{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Szytuła, A., E-mail: andrzej.szytula@uj.edu.pl [Marian Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Kraków (Poland); Baran, S.; Penc, B. [Marian Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Kraków (Poland); Przewoźnik, J. [Department of Solid State Physics, Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków (Poland); Winiarski, A. [August Chełkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Tyvanchuk, Yu.; Kalychak, Ya.M. [Department of Analytical Chemistry, Ivan Franko National University of Lviv, Kyryla and Mephodiya 6, 79005 Lviv (Ukraine)

    2014-03-15

    Highlights: • Basis on the X-ray data the crystal structure of Ce{sub 11}Ni{sub 4}In{sub 9} and CeNi{sub 9}In{sub 2} compounds determined. • In Ce{sub 11}Ni{sub 4}In{sub 9} the Ce magnetic moments order at low temperatures, where in CeNi{sub 9}In{sub 2} not detected localized moment. • Magnetic and specific heat data of Ce{sub 11}Ni{sub 4}In{sub 9} indicate two phase transitions at 5 and 16.5 K. • XPS spectra indicate for both compounds sizable hybridization of the Ce4f electrons with conduction band. • For CeNi{sub 9}In{sub 2} the existence of Ce3d{sup 9}4f{sup 0} configuration indicates the mixed-valence state. -- Abstract: Crystal structure, magnetic, thermal and electronic properties of Ce{sub 11}Ni{sub 4}In{sub 9} and CeNi{sub 9}In{sub 2} compounds were investigated by means of X-ray diffraction, magnetic, calorimetric and X-ray photoelectron spectroscopy measurements. Ce{sub 11}Ni{sub 4}In{sub 9} crystallizes in the orthorhombic Nd{sub 11}Pd{sub 4}In{sub 9}-type structure (space group Cmmm) while CeNi{sub 9}In{sub 2} crystallizes in the YNi{sub 9}In{sub 2}-type structure (space group P4/mbm) (in which Ce atoms occupy only one Wyckoff position). Magnetic and specific heat measurements indicate that in Ce{sub 11}Ni{sub 4}In{sub 9} the Ce magnetic moment orders below 16.5 K, while in CeNi{sub 9}In{sub 2} it does not carry a localized moment. Our data indicate that Ni atoms are likely non-magnetic in both compounds. The XPS spectra of the valence band and the core-level are reported. The contributions to the density of states at E{sub F} are dominated by the Ni3d states. The XPS Ce3d data indicate sizable hybridization of the Ce-4f electrons with conduction band for both compounds. The existence in CeNi{sub 9}In{sub 2} of Ce3d{sup 9}4f{sup 0} configuration indicates a mixed-valence system. The core-level Ni2p{sub 3/2} spectra indicate incomplete Ni3d band filling in this compound.

  7. The thermodynamic, electronic and magnetic properties of Ni{sub 2}MnX (X=Ge, Sn, Sb) Heusler alloys: a quasi-hormonic Debye model and first principles study

    Energy Technology Data Exchange (ETDEWEB)

    Li Jia, E-mail: jiali@hebut.edu.cn [School of Science, Hebei University of Technology, Tianjin 300130 (China); Zhang Zhidong; Sun Yubao; Zhang Jian; Zhou Guoxiang [School of Science, Hebei University of Technology, Tianjin 300130 (China); Luo Hongzhi; Liu Guodong [School of Material Sciences and Engineering, Hebei University of Technology, Tianjin 300130 (China)

    2013-01-15

    The thermodynamic, electronic and magnetic properties of Ni{sub 2}MnX (X=Ge, Sn, Sb) Heusler alloys are investigated using the quasi-hormonic Debye model and the first principles calculation based on the density-functional-theory. The calculated results of the temperature dependent bulk modulus, coefficient of thermal expansion and the P-V relation for Ni{sub 2}MnX (X=Ge, Sn, Sb) indicate that the bonding strength becomes stronger along the sequence of Ni{sub 2}MnSb{yields}Ni{sub 2}MnSn{yields}Ni{sub 2}MnGe. The slower change trend of temperature dependent heat capacity of Ni{sub 2}MnGe than that of Ni{sub 2}MnSn and Ni{sub 2}MnSb stems from the larger contribution of electronic heat capacity and smaller contribution of lattice heat capacity compared to the other two alloys. The ferromagnetic coupling order between the Ni and Mn is confirmed by our first principles calculations. The total moments in one primitive cell for the three alloys are all about 4.0 {mu}{sub B} which are mainly carried by Mn atom with about 3.5 {mu}{sub B} as can be seen from the magnetization density distribution.

  8. PARAMETRIC DESIGN OF DELTA ROBOT

    Directory of Open Access Journals (Sweden)

    Mert Gürgen

    2016-09-01

    Full Text Available This article describes a sophisticated determination and presentation of a workspace volume for a delta robot, with consideration of its kinematic behavior. With the help of theoretical equations, optimization is performed with the aid of the stiffness and dexterity analysis. Theoretical substructure is coded in Matlab and three-dimensional (3D data for delta robot are developed in computer-aided design (CAD environment. In later stages of the project, both 3D and theoretical data are linked together and thus, with the changing design parameter of the robot itself, the Solidworks CAD output adapts and regenerates output with a new set of parameters. To achieve an optimum workspace volume with predefined parameters, a different set of robot parameters are iterated through design optimization in Matlab, and the delta robot design is finalized and illustrated in the 3D CAD environment, Solidworks. This study provides a technical solution to accomplish a generic delta robot with optimized workspace volume.

  9. Coprecipitation of nickel zinc malonate: A facile and reproducible synthesis route for Ni{sub 1−x}Zn{sub x}O nanoparticles and Ni{sub 1−x}Zn{sub x}O/ZnO nanocomposites via pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Lontio Fomekong, Roussin, E-mail: lonforou@yahoo.fr [Inorganic Chemistry Department, University of Yaoundé I, B.P. 812, Yaoundé (Cameroon); Institut de la Matière Condensée et des Nanosciences, Université Catholique de Louvain, Croix du Sud 1, 1348 Louvain-La-Neuve (Belgium); Kenfack Tsobnang, Patrice [Inorganic Chemistry Department, University of Yaoundé I, B.P. 812, Yaoundé (Cameroon); Magnin, Delphine; Hermans, Sophie; Delcorte, Arnaud [Institut de la Matière Condensée et des Nanosciences, Université Catholique de Louvain, Croix du Sud 1, 1348 Louvain-La-Neuve (Belgium); Lambi Ngolui, John [Chemistry Department, Higher Teacher Training College, University of Yaoundé I, B.P. 47, Yaoundé (Cameroon)

    2015-10-15

    Nanoparticles of Ni{sub 1−x}Zn{sub x}O and Ni{sub 1−x}Zn{sub x}O/ZnO, which can be good candidates for selective gas sensors, were successfully obtained via a two-step synthetic route, in which the nickel zinc malonate precursor was first synthesized by co-precipitation from an aqueous solution, followed by pyrolysis in air at a relatively low temperature (~500 °C). The precursor was characterized by ICP-AES, FTIR and TG and the results indicate the molecular structure of the precursor to be compatible with Ni{sub 1−x}Zn{sub x}(OOCCH{sub 2}COO)·2H{sub 2}O. The decomposition product, characterized using various techniques (FTIR, XRD, ToF-SIMS, SEM, TEM and XPS), was established to be a doped nickel oxide (Ni{sub 1−x}Zn{sub x}O for 0.01≤x≤0.1) and a composite material (Ni{sub 1−x}Zn{sub x}O/ZnO for 0.2≤x≤0.5). To elucidate the form in which the Zn is present in the NiO structure, three analytical techniques were employed: ToF-SIMS, XRD and XPS. While ToF SIMS provided a direct evidence of the presence of Zn in the NiO crystal structure, XRD showed that Zn actually substitutes Ni in the structure and XPS is a bit more specific by indicating that the Zn is present in the form of Zn{sup 2+} ions. - Highlights: • Coprecipitation synthesis of nickel zinc malonate single bath precursor was achieved. • The as synthesized precursors are an homogeneous mixture of nickel and zinc malonate. • XRD, ToF-SIMS, XPS, SEM and TEM was used to characterized decomposition products. • Ni{sub 1−x}Zn{sub x}O nanoparticles (0.01≤x≤0.1) formed after pyrolysis (~500 °C) of precursor. • Ni{sub 1−x}Zn{sub x}O/ZnO nanocomposite (0.2≤x≤0.5) formed after pyrolysis at 500 °C of precursor.

  10. Nickel-stabilized hexagonal (Cu, Ni){sub 6}Sn{sub 5} in Sn-Cu-Ni lead-free solder alloys

    Energy Technology Data Exchange (ETDEWEB)

    Nogita, Kazuhiro [Materials Engineering, University of Queensland, Brisbane, QLD 4072 (Australia)], E-mail: k.nogita@uq.edu.au; Nishimura, Tetsuro [Nihon Superior Co., Ltd., NS Building, Suita 564-0063 (Japan)

    2008-07-15

    Cu{sub 6}Sn{sub 5} is an important intermetallic compound (IMC) in lead-free solder alloys. Cu{sub 6}Sn{sub 5} exists in two crystal structures with an allotropic transformation from monoclinic {eta}'-Cu{sub 6}Sn{sub 5} at temperatures lower than 186 deg. C to hexagonal {eta}-Cu{sub 6}Sn{sub 5}. A detailed analysis by transmission electron microscopy (TEM) in Sn-0.7 wt.% Cu-0.06 wt.% Ni reveals that when the Ni content in (Cu, Ni){sub 6}Sn{sub 5} is {approx}9 at.% Ni, the hexagonal allotrope of (Cu, Ni){sub 6}Sn{sub 5} becomes stable at room temperature.

  11. The effect of the substitution of Cu for Mn on magnetic and magnetocaloric properties of Ni{sub 50}Mn{sub 34}In{sub 16}

    Energy Technology Data Exchange (ETDEWEB)

    Kaya, M. [Department of Engineering Physics, Faculty of Engineering, Ankara University, 06100 Besevler, Ankara (Turkey); Yildirim, S. [Nanotechnology and Nanomedicine Division, Hacettepe University, Ankara 06800 (Turkey); Yüzüak, E. [Department of Engineering Physics, Faculty of Engineering, Ankara University, 06100 Besevler, Ankara (Turkey); Department of Nanotechnology Engineering, Faculty of Engineering, Recep Tayyip Erdogan University, 53100 Rize (Turkey); Dincer, I., E-mail: idincer@eng.ankara.edu.tr [Department of Engineering Physics, Faculty of Engineering, Ankara University, 06100 Besevler, Ankara (Turkey); Ellialtioglu, R. [Department of Engineering Physics, Faculty of Engineering Hacettepe University, Ankara 06800 (Turkey); Elerman, Y. [Department of Engineering Physics, Faculty of Engineering, Ankara University, 06100 Besevler, Ankara (Turkey)

    2014-11-15

    The influence of Cu substitution for Mn on magnetic and magnetocaloric properties has been investigated in Ni{sub 50}Mn{sub 34−x}Cu{sub x}In{sub 16} (x=1.3 and 1.6) Heusler alloys by using calorimetric and magnetic measurements. The temperature dependent magnetization measurements and calorimetric studies indicate that martensitic transition temperatures shift to higher temperatures with increasing valence electron concentrations, e/a. The isothermal magnetization curves around the martensitic transition temperatures show a typical metamagnetic behavior. Associated with that, large positive values of magnetic entropy changes around structural transition region were determined by using the Maxwell and Clausius–Clapeyron relations. The maximum magnetic entropy change values were found to be 25.2 and 5.7 J kg{sup −1} K{sup −1} for Ni{sub 50}Mn{sub 34−x}Cu{sub x}In{sub 16} (x=1.3 and 1.6) alloys by Maxwell relation in a magnetic field change of 2 T. In order to understand the limit can be reached for, the magnetic entropy change values recalculated by Clausius–Clapeyron relation. Obtained maximum entropy change values are 22.8 and 16.3 J kg{sup −1} K{sup −1} for Ni{sub 50}Mn{sub 34−x}Cu{sub x}In{sub 16} (x=1.3 and 1.6) alloys by Clausius–Clapeyron relation. - Highlights: • Ni{sub 50}Mn{sub 34−x}Cu{sub x}In{sub 16} alloys are prepared by an arc-melting method. • Structural properties are characterized by XRD, DSC and SEM. • Magnetic entropy change values are estimated by Maxwell and Clausius–Clapeyron equations.

  12. On the LiCo{sub 2/3}Ni{sub 1/6}Mn{sub 1/6}O{sub 2} positive electrode material

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoud, Abdelfattah [ECME, FST Marrakech, University Cadi Ayyad, BP549, Av. A. Khattabi, Marrakech (Morocco); Saadoune, Ismael, E-mail: saadoune1@yahoo.f [ECME, FST Marrakech, University Cadi Ayyad, BP549, Av. A. Khattabi, Marrakech (Morocco); Amarilla, Jose Manuel [Instituto de Ciencias de Materiales de Madrid, CSIC, c/Sor Juana Ines de la Cruz, 3, Cantoblanco, 28049 Madrid (Spain); Hakkou, Rachid [ECME, FST Marrakech, University Cadi Ayyad, BP549, Av. A. Khattabi, Marrakech (Morocco)

    2011-04-15

    Research highlights: LiCo{sub 2/3}Ni{sub 1/6}Mn{sub 1/6}O{sub 2} layered oxide, prepared by the combustion method, consists of particles with homogenous distribution. Rietveld refinement shows that the crystal structure of this cathode material presents no Li/Ni mixing. The best cycling performances were recorded when the upper cut off is fixed at 4.5 V corresponding to a solid solution domain. - Abstract: LiCo{sub 2/3}Ni{sub 1/6}Mn{sub 1/6}O{sub 2} layered oxide was synthesized by the combustion method that led to a crystalline phase with good homogeneity and low particles size. The structural properties of the prepared positive electrode material were investigated by performing XRD Rietveld refinement. Practically no Li/Ni mixing was detected evidencing that the studied compound adopts almost an ideal {alpha}-NaFeO{sub 2} type structure. The Li||LiCo{sub 2/3}Ni{sub 1/6}Mn{sub 1/6}O{sub 2} cell showed a discharge capacity of 199 mAh g{sup -1} when cycled in the 2.7-4.6 V potential range while the best cycling performances were recorded when the upper cut off is fixed at 4.5 V. Structural changes in Li{sub x}Co{sub 2/3}Ni{sub 1/6}Mn{sub 1/6}O{sub 2} with lithium electrochemical de-intercalation were studied using X-ray diffraction. This study clearly shows the existence of a solid solution domain in the 0.1 < x < 1.0 composition range while for x = 0.1, a new phase appears explaining the decrease of the electrochemical performance when the cell is cycled at high upper cut off voltage.

  13. Electrochemical behavior of Ni{sub x}W{sub 1-x} materials as catalyst for hydrogen evolution reaction in alkaline media

    Energy Technology Data Exchange (ETDEWEB)

    Oliver-Tolentino, Miguel A. [UPIBI-IPN, Departamento de Ciencias Basicas, Av. Acueducto s/n, Barrio La Laguna, Col. Ticoman, Mexico D.F. 07340 (Mexico); Arce-Estrada, Elsa M. [ESIQIE-IPN Departamento de Ingenieria en Metalurgia y Materiales, UPALM, UPALM, Mexico D.F. 07738 (Mexico); Cortes-Escobedo, Claudia A. [Centro de Investigacion e Innovacion Tecnologica del IPN, Cda. Cecati s/n, Col. Sta. Catarina, CP 02250 Azcapotzalco D.F. (Mexico); Bolarin-Miro, Ana M.; Sanchez-De Jesus, Felix [Area Academica de Ciencias de la Tierra y Materiales, Universidad Autonoma del Estado de Hidalgo, CU, Carr. Pachuca-Tulancingo Km. 4.5, Mineral de la Reforma, CP 42184 Hidalgo (Mexico); Gonzalez-Huerta, Rosa de G. [ESIQIE-IPN, Departamento de Ingenieria Quimica - Laboratorio de Electroquimica y Corrosion, Edif. Z-5 3er piso, UPALM, Mexico D.F. 07738 (Mexico); Manzo-Robledo, Arturo, E-mail: amanzor@ipn.mx [ESIQIE-IPN, Departamento de Ingenieria Quimica - Laboratorio de Electroquimica y Corrosion, Edif. Z-5 3er piso, UPALM, Mexico D.F. 07738 (Mexico)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer The electrochemical techniques used in this study elucidated the Ni-W surface state. Black-Right-Pointing-Pointer The Ni-W materials were effective for the hydrogen evolution reaction. Black-Right-Pointing-Pointer The prepared alloys exhibited higher catalytic activity than their precursors. Black-Right-Pointing-Pointer The preparation method is relatively simple and effective procedure. - Abstract: In the present work, results of electrochemical evaluation, as well as morphological and structural characterization of Ni{sub x}W{sub 1-x} materials with x = 0.77, 0.64, 0.4, 0.19 and 0.07 processed by means of high energy ball milling from high purity powders are presented. Also, the electrocatalytic performance on the hydrogen evolution reaction (HER) of the Ni{sub x}W{sub 1-x} materials evaluated by linear polarization and cyclic voltammetry techniques in alkaline media at room temperature is discussed. The structural and morphological characterization of the as-prepared materials was carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results indicated a small-particle clusters and solid solution formation. According to the kinetics parameters the best electrocatalytic activity was observed at Ni{sub 64}W{sub 36}.

  14. Large inverse magnetocaloric effect and magnetoresistance in nickel rich Ni{sub 52}Mn{sub 34}Sn{sub 14} Heusler alloy

    Energy Technology Data Exchange (ETDEWEB)

    Pal, D., E-mail: deba.phy@gmail.com [S.N. Bose National Center for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098, West Bengal (India); Kandi Raj College, Kandi 742137, West Bengal (India); Ghosh, A.; Mandal, K. [S.N. Bose National Center for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098, West Bengal (India)

    2014-06-01

    Nickel rich Ni{sub 52}Mn{sub 34}Sn{sub 14} Heusler alloy was prepared by arc melting and subsequent homogenization by annealing. Existence of first order magneto-structural transition (FOMST) was confirmed by various measurements. In comparison to conventional Ni{sub 50−x}Mn{sub 36+x}Sn{sub 14} alloys, a larger magnetic entropy change (∆S{sub M}≈8 J/kg K using Maxwell's thermodynamic equation and ∆S{sub M}≈18 J/kg K using Clasius–Clapeyron equation) and large negative magnetoresistance (MR≈−30%) were observed in the vicinity of martensitic transition temperature due to a change of 3 T and 8 T magnetic fields respectively. Effect of excess Ni content was discussed by considering other nearer compositions as reported by other researchers. Irreversibility in FOMST due to kinetic arrest was also studied from MR vs magnetic fields curves taken at a single temperature in two different initial phases. The exchange bias behavior in this alloy was studied by various magnetic measurements. - Highlights: • Large magnetocaloric effect was observed in Ni-rich Ni{sub 52}Mn{sub 34}Sn{sub 14} Heusler alloy. • A large negative magnetoresistance was observed near the structural transition. • We investigated the exchange bias behavior in this alloy. • The resistivity shows irreversibility due to field cycling.

  15. Martensitic transformation in Ni-rich Ni{sub 55}Mn{sub 25}In{sub 20} Heusler alloy: Experiment and first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Yu, S.Y., E-mail: syyu@sdu.edu.cn; Hu, S.J.; Kang, S.S.; Gu, A.J.

    2015-06-05

    Highlights: • Ni{sub 55}Mn{sub 25}In{sub 20} ribbons with ordered L2{sub 1} structure were prepared. • A martensitic transformation has been observed in Ni{sub 55}Mn{sub 25}In{sub 20}. • A large MR up to 17% is observed. • The cubic structure becomes unstable by partial substitution of In with Ni. • The driving force of the martensitic transformation is discussed. - Abstract: A martensitic transformation has been observed in Ni-rich Ni{sub 55}Mn{sub 25}In{sub 20} Heusler alloy and been theoretically investigated by first-principles calculations. The samples are prepared by the melt-spun method and the ribbons show an ordered L2{sub 1} structure at room temperature. Magnetization and electrical resistance measurements show that a martensitic transformation occurs at about 156 K, with both phases exhibiting ferromagnetic ordering. A negative magnetoresistance of 17% is observed at a magnetic field of 50 kOe due to the magnetic field induced reverse martensitic transformation. Electronic structure calculations indicate that the 3d states of Ni occupied in In site strongly hybridize with the Ni: 3d states. Such hybridization plays an important role in driving the martensitic transformation.

  16. Effect of aging on phase transformation and magnetic properties of Mn{sub 53}Ni{sub 25}Ga{sub 22} ferromagnetic shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Dong, G.F., E-mail: dgfu0451@sina.com [Dalian University of Technology, College of Physics and Optoelectronic Engineering, Dalian 116024 (China); National Key Laboratory Precision Hot Processing of Metals, School of Materials Science and Engineering, Harbin Institute of Technology, P.O. Box 405, Harbin 150001 (China); Gao, Z.Y.; Sui, J.H.; Cai, W. [Department of Physics, Dalian University, Dalian 116622 (China)

    2015-01-15

    The Mn{sub 53}Ni{sub 25}Ga{sub 22} ferromagnetic shape memory alloy has been aged at various temperatures for 3 h, and the martensitic transformation and magnetic properties have been investigated by differential scanning calorimetry (DSC) and the Physical Property Measurements System (PPMS, Quantum Design). The results show that precipitation has an obvious effect on martensitic transformation temperatures, Curie temperatures and saturation magnetization. Aging greatly affects transformation temperatures due to modified composition of the matrix. Martensitic transformation temperature, Curie temperatures first decreased and then increased with increase of aging temperature, reaching their minimum values at the aging temperature of 773 K. The saturation magnetizations first rapidly increase and then rapidly decrease with increase of aging temperature, reaching the maximum value at 773 K. It can be concluded that appropriate ageing treatment can enhance the saturation magnetization of Mn{sub 53}Ni{sub 25}Ga{sub 22} alloy. - Highlights: • Precipitation has an obvious effect on martensitic transformation and magnetic properties. • Amount of γ precipitate first increases and then decreases with increasing ageing temperature. • Transformation temperatures first decrease and then increase with increasing aging temperature. • Appropriate ageing treatment can enhance the saturation magnetization of Mn{sub 53}Ni{sub 25}Ga{sub 22} alloy.

  17. Evolution of shear bands, free volume, and structure in room temperature rolled Pd{sub 40}Ni{sub 40}P{sub 20} bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yuanli; Shi, Bo; Ma, Zhikun; Li, Jiangong, E-mail: lijg@lzu.edu.cn

    2015-01-19

    The evolution of the shear band, free volume, and structure in room temperature rolled Pd{sub 40}Ni{sub 40}P{sub 20} bulk metallic glass was investigated. It was found that the average shear band density increases monotonously with increasing strain. For the room temperature rolled Pd{sub 40}Ni{sub 40}P{sub 20} bulk metallic glass with a strain of 99%, a high density of shear bands with an average spacing of 31 nm was observed. The absolute free volume content was determined based on the free volume model and found to increase monotonously with increasing strain. The free volume content in the room temperature rolled Pd{sub 40}Ni{sub 40}P{sub 20} bulk metallic glass with a strain of 99% is 34% higher than its as-cast counterpart. Neither phase separation nor crystallization occurs in all the deformed samples. The coordination number of the first coordination shell decreases and the degree of disorder of atomic arrangement increases with increasing strain.

  18. Preparation and characterization of reactively sintered Ni{sub 3}Al-hBN-Ag composite coating on Ni-based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Shitang [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate School, Chinese Academy of Sciences, Beijing 100039 (China); Zhou Jiansong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Guo Baogang [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate School, Chinese Academy of Sciences, Beijing 100039 (China); Zhou Huidi [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Pu Yuping [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Central Iron and Steel Research Institute, Beijing 100081 (China); Chen Jianmin [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)], E-mail: chenjm@lzb.ac.cn

    2009-04-03

    Ni{sub 3}Al-hBN-Ag intermetallic matrix composite coating was prepared on Ni-based superalloy by reactive sintering. The crystalline phase and microstructure of the coating were examined by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The results showed that the hBN particles pretreated by electroless nickel plating and hot-dip aluminizing and Ag particles with a size of several micrometers were homogeneously dispersed in the Ni{sub 3}Al matrix, and the composite coating had strong interfacial bonding with a fine and dense microstructure. During the reactive sintering, an exothermic reaction between Ni and Al associated with a transient liquid phase occurred, leading to in situ synthesis of the densified Ni{sub 3}Al matrix in the coating with a high tensile strength of more than 70 MPa. The high-temperature tribological properties evaluated on a ball-on-disc test rig showed that the coating possessed self-lubricating properties from room temperature to 800 deg. C due to a synergetic lubricating action of Ag and hBN.

  19. Structure, energetic and phase transition of multi shell icosahedral bimetallic nanostructures: A molecular dynamics study of Ni{sub m}Pd{sub n} (n + m = 55 and 147)

    Energy Technology Data Exchange (ETDEWEB)

    Hewage, Jinasena W., E-mail: jinasena@chem.ruh.ac.lk

    2015-01-15

    Structure, energetic and thermodynamic properties of multi shell icosahedral bimetallic nickel–palladium nanostructures with the size of 55 and 147 atoms were studied by using the molecular dynamics simulations and the microcanonical ensemble version of multiple histogram method. In 55 atoms icosahedra, two core–shell motifs, Ni{sub 13}Pd{sub 42} and Pd{sub 13}Ni{sub 42} with their isomers Pd{sub 13}(Pd{sub 29}Ni{sub 13}) and Ni{sub 13}(Ni{sub 29}Pd{sub 13}) were considered. Similarly in 147 atoms icosahedra, all mutations corresponding to the occupations of either nickel atoms or palladium atoms in the core, inner shell or outer shell and their isomers generated by interchanging thirteen core atoms with thirteen atoms of the other type in the inner and outer shells were considered. It is found that the nickel-core clusters are more stable than the palladium-core clusters and cohesive energy increases with the nickel composition. Phase transition of each cluster was studied by means of constant volume heat capacity. The trend in variation of melting temperature is opposite to the energy trend and special increase in melting points was observed for nickel-core isomers compared to the palladium-core isomers. Helmholtz free energy change with temperature for shell to core interchange of thirteen atoms revealed the thermodynamic stability of the formation of Ni{sub core}Pd{sub shell} structures and the surface segregation of palladium. - Highlights: • Nanostructures of Ni{sub m}Pd{sub n} clusters for m + n = 55 and 147 have been studied. • Structures favor the formation of nickel-core surrounded by palladium atoms. • In general, it appears the increase of cohesive energy with the nickel composition. • Calculated thermodynamic parameters confirm the energetic results. • Results show also the palladium segregation on the surface.

  20. Student Difficulties with the Dirac Delta Function

    CERN Document Server

    Wilcox, Bethany R

    2014-01-01

    The Dirac delta function is a standard mathematical tool used in multiple topical areas in the undergraduate physics curriculum. While Dirac delta functions are usually introduced in order to simplify a problem mathematically, students often struggle to manipulate and interpret them. To better understand student difficulties with the delta function at the upper-division level, we examined responses to traditional exam questions and conducted think-aloud interviews. Our analysis was guided by an analytical framework that focuses on how students activate, construct, execute, and reflect on the Dirac delta function in physics. Here, we focus on student difficulties using the delta function to express charge distributions in the context of junior-level electrostatics. Challenges included: invoking the delta function spontaneously, constructing two- and three-dimensional delta functions, integrating novel delta function expressions, and recognizing that the delta function can have units.

  1. {Delta}I = 3/2 and {Delta}S = 2 Hyperon decays in chiral perturbation theory

    Energy Technology Data Exchange (ETDEWEB)

    He, X.G. [University of Melbourne, Parkville, VIC (Australia). School of Physics; Valencia, G. [Iowa State University, Ames, Iowa (United States). Department of Physics and Astronomy

    1997-05-01

    We study the| {Delta}I| = 3/2 and |{Delta}S| = 2 amplitudes for hyperon decays of the form B {yields} B`{pi} at lowest order in chiral perturbation theory. At this order, the {Delta}I = 3/2 amplitudes depend on only one constant. We extract the value of this constant from experiment and find a reasonable description of these processes within experimental errors. The same constant determines the {Delta}S = 2 transitions which, in the standard model, are too small to be observed. We find that new physics with parity odd {Delta}S = 2 interactions can produce observable rates in hyperon decays while evading the bounds from K{sup 0} - K-bar{sup 0} mixing. (authors) 10 refs., 3 tabs.

  2. Cyclic deformation of NI/sub 3/(Al,Nb) single crystals at ambient and elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Bonda, N.R.

    1985-01-01

    Cyclic tests were performed on Ni/sub 3/(Al,Nb) (..gamma..' phase) single crystals by using a servo-hydraulic machine under fully reversed plastic strain control at a frequency of 0.1-0.2 Hz at room temperature, 400/sup 0/C and 700/sup 0/C. Since the monotonic behavior is orientation dependent, three orientations were studied. Asymmetry in tensile and compressive stresses was observed in the cyclic hardening curves of specimens tested at these temperatures and they were discussed with regard to the model suggested by Paider et al for monotonic behavior. The stress levels in the cyclic stress-strain curves (CSSC) at room temperature depended on orientation and cyclic history. No CSSCs were established at 400/sup 0/C and 700/sup 0/C. The deformation in cyclic tests at small plastic strain amplitudes was found to be different from that in monotonic tests in the microplastic regions in which the deformation is believed to be carried by a small density of edge dislocations. But in cyclic deformation, to and from motion of dislocations trap the edge dislocations into dipoles and therefore screw dislocations will be forced to participate in the deformation. Cracks on the surfaces of specimens tested at room temperature and 400/sup 0/C were found to be of stage I type, whereas at 700/sup 0/C, they were of stage II type.

  3. La{sub 3}Ir{sub 2} with rhombohedral Er{sub 3}Ni{sub 2}-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, Konrad; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2014-10-15

    La{sub 3}Ir{sub 2} is formed upon reaction of the elements at 1273 K in a sealed silica ampoule. The structure was refined from single-crystal X-ray diffractometer data: Er{sub 3}Ni{sub 2}-type structure, R anti 3, a = 895.26(2), c = 1713.01(5) pm, wR = 0.0578, 766 F{sup 2} values, 25 variables. The structure is composed of two simple basic building units: slightly distorted La1 rate at La3{sub 6}La2{sub 2} cubes resembling the tungsten structure and Ir{sub 2} rate at La1{sub 1}La2{sub 2}La3{sub 5} units with an AlB{sub 2}-related coordination (298 pm Ir-Ir in the dumb-bell). Each cube is coordinated by six of the AlB{sub 2} units. The relationship with the U{sub 3}Si{sub 2}-type structure is discussed.

  4. Investigation of magnetic and electrical transport properties of Dy{sub 2}Ni{sub 2}Sn

    Energy Technology Data Exchange (ETDEWEB)

    Karmakar, S.K.; Giri, S.; Majumdar, S., E-mail: sspsm2@iacs.res.in

    2014-12-15

    The magnetic and transport properties of the ternary rare-earth compound Dy{sub 2}Ni{sub 2}Sn are reported. The compound undergoes a long range antiferromagnetic ordering below T{sub N}=43 K with a collinear structure. A second transition is observed below about T{sub t}=28 K, where spin canting takes place. We find clear thermal hysteresis in our magnetization data between 20 and 45 K, indicating the first order nature of the magnetic transitions occurring at T{sub N} and T{sub t}. Clear signature of metamagnetism is observed in the canted antiferromagnetic phase. The change in entropy on the application of magnetic field (magnetocaloric effect) was calculated from the isothermal magnetization data and it shows negative and positive peaks at T{sub N} and T{sub t} respectively. The thermal variation of resistivity shows clear peak like signature near T{sub N}, which gets suppressed under applied magnetic field resulting negative magnetoresistance. The low temperature resistivity (below T{sub t}) can be well fitted with the model available for spin dependent s–f scattering in antiferromagnetic system having well localized moments. The data also indicate short range correlations well above the antiferromagnetic transition point, which might be related to the two dimensional spin–spin correlations in this layered compound. - Highlights: • Field induced magnetic transition. • Positive and negative magnetocaloric effect. • Large negative magnetoresistance. • Short range magnetic correlation well above Neel temperature.

  5. Anisotropic magneto-resistance in Ni{sub 80}Fe{sub 20} antidot arrays with different lattice configurations

    Energy Technology Data Exchange (ETDEWEB)

    Coïsson, Marco, E-mail: m.coisson@inrim.it [INRIM, Electromagnetics Division, Strada delle Cacce 91, 10135 Torino (Italy); Manzin, Alessandra [INRIM, Electromagnetics Division, Strada delle Cacce 91, 10135 Torino (Italy); Barrera, Gabriele [INRIM, Electromagnetics Division, Strada delle Cacce 91, 10135 Torino (Italy); Università degli Studi di Torino, Dipartimento di Chimica, via P. Giuria 7, 10125 Torino (Italy); Celegato, Federica; Enrico, Emanuele; Tiberto, Paola; Vinai, Franco [INRIM, Electromagnetics Division, Strada delle Cacce 91, 10135 Torino (Italy)

    2014-10-15

    Highlights: • Detailed study of the magnetisation processes in antidot lattices. • Combined magnetic (MFM), magneto-transport (AMR) and numerical investigations. • Accounting for the experimentally observed differences in AMR signal amplitude in longitudinal and transverse configurations through numerical simulations. - Abstract: Ni{sub 80}Fe{sub 20} antidot arrays having different lattice geometrical properties and irregularities were prepared via electron beam lithography and self-assembling of polystyrene nanospheres. All the samples were experimentally characterised by magnetic force microscopy and room-temperature magneto-resistance measurements in different configurations. The analysis, supported by micromagnetic simulations, has been focused on the effect of lattice geometry on the magneto-resistance behaviour of these systems. The detailed investigation through micromagnetic simulations of the magnetic domain configuration as a function of the applied field allows a complete understanding of the qualitative and quantitative difference of anisotropic magneto-resistance properties that have been measured in samples with different lattice geometries and in different measurement configurations.

  6. Degradation behavior of Ni{sub 3}Al plasma-sprayed boiler tube steels in an energy generation system

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, B.S.; Prakash, S. [GZS, Bathinda (India). College of Engineering

    2005-06-01

    Boiler steels, namely, low-C steel, ASTM-SA210-Grade A1 (GrA1), 1Cr-0.5Mo steel, ASTM-SA213-T-11 (T11) and 2.25Cr-1Mo steel, ASTM-SA213-T-22 (T22) were plasma sprayed with Ni3Al. The alloy powder was prepared by mixing Ni and Al in the stoichiometric ratio of 3 to 1. The Ni-22Cr-10Al-1Y alloy powder was used as a bond coat, with a 150{mu} m thick layer sprayed onto the surface before applying the 200{mu}m coating of Ni{sub 3}Al. Exposure studies have been performed in the platen superheater zone of a coal-fired boiler at around 755{sup o}C for 10 cycles, each of 100 h duration. The protection to the base steel was minimal for the three steels. Scale spallation and the formation of a porous and nonadherent NiO scale were probably the main reasons for the lack of protection. In the case of T22-coated steel, cracks in the coatings have been observed after the first 100 h exposure cycle.

  7. Effect of temperature on the ferromagnetic resonance of Ni{sub 50}Fe{sub 50} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Diaz de Sihues, M. [Departamento de Fisica, Facultad de Ciencias, Universidad del Zulia, Apartado. Postal 526, Maracaibo 4001, Zulia (Venezuela); Silva, P.J. [Laboratorio de Fisica de la Materia Condensada, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas (IVIC), Carretera Panamericana Km. 11, Apartado 21827, Caracas 1020-A (Venezuela); Fermin, J.R. [Departamento de Fisica, Facultad de Ciencias, Universidad del Zulia, Apartado. Postal 526, Maracaibo 4001, Zulia (Venezuela)]. E-mail: fermin@luz.ve

    2004-12-31

    We report on the effect of temperature on the ferromagnetic resonance (FMR) spectra of Ni{sub 50}Fe{sub 50} thin films sputtered on Si (001) wafers. The FMR field and linewidth were studied as a function of the ferromagnetic layer thickness t, and temperature T. The data are interpreted in the framework of a phenomenological model that includes in- and out-of-plane uniaxial anisotropy fields. The main effect of temperature on the magnetic properties of these films is to increase the in-plane uniaxial anisotropy and to induce a surface anisotropy that pushes the magnetization out-of-plane. The temperature dependence of the resonance field is explained assuming the magnetic anisotropies varying as m{sup 3}, where m=M(T)/M(0) is a reduce magnetization and M(T) follows the law (1-CTe{sup -E/KT}), where E{proportional_to} T{sub C} is the energy gap of the spin wave spectrum, and T{sub C} being the Curie temperature. The resonance field as a function of temperature shows a transition temperature separating two different ferromagnetic regimes. At lower temperatures a new magnetic transition is observed in thinner films. The temperature dependence of the FMR linewidth departs from that expected in other transition metal structures at very low temperatures. This behavior is unique and may be associated with interface and surface effects.

  8. The crystal structure and phase transitions of the magnetic shape memory compound Ni{sub 2}MnGa

    Energy Technology Data Exchange (ETDEWEB)

    Brown, P J [Physics Department, Loughborough University, Leicestershire (United Kingdom); Crangle, J [Department of Physics, University of Sheffield, Sheffield (United Kingdom); Kanomata, T [Faculty of Engineering, Tohuku Gakuin University, Tadajo 985-8537 (Japan); Matsumoto, M [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Neumann, K-U [Physics Department, Loughborough University, Leicestershire (United Kingdom); Ouladdiaf, B [Institut Laue-Langevin, BP 156, 38042 Grenoble (France); Ziebeck, K R A [Physics Department, Loughborough University, Leicestershire (United Kingdom)

    2002-11-04

    High resolution neutron powder diffraction and single crystal measurements on the ferromagnetic shape memory compound Ni{sub 2}MnGa have been carried out. They enabled the sequence of transformations which take place when the unstressed, stoichiometric compound is cooled from 400 to 20 K to be established. For the first time the crystallographic structure of each of the phases which occur has been determined. At 400 K the compound has the cubic L2{sub 1} structure, and orders ferromagnetically at T{sub C} {approx} 365 K. On cooling below {approx} 260 K a super-structure, characterized by tripling of the repeat in one of the (110){sub cubic} directions, forms. This phase, known as the pre-martensitic phase, persists down to the structural phase transition at T{sub M} {approx} 200 K and can be described by an orthorhombic unit cell with lattice parameters a{sub ortho} = 1/{radical}2a{sub cubic}, b{sub ortho} = 3/{radical}2a{sub cubic}, c{sub ortho} = a{sub cubic} and space group Pnnm. Below T{sub M} the compound has a related orthorhombic super-cell with b{sub ortho} {approx} 7/{radical}2a{sub cubic}, which can be described within the same space group. The new modulation appears abruptly at T{sub M} and remains stable down to at least 20 K.

  9. Reactive versus anticipative adaptive management of Deltas: The Sacramento-San Joaquin Delta and the Rhine-Meuse Delta compared

    NARCIS (Netherlands)

    Vlieg, T.J.; Zandvoort, M.

    2013-01-01

    In this paper Californian Adaptive Management (AM) and Dutch Adaptive Delta Management (ADM) are compared. The concepts are introduced in a policy context to deal with prevailing types of uncertainty in water management in the Californian Sacramento-San Joaquin Delta and the Dutch Rhine-Meuse Delta

  10. Facts About Delta Pi Epsilon

    Science.gov (United States)

    Delta Pi Epsilon Journal, 1976

    1976-01-01

    The article discusses the purpose and structure of Delta Pi Epsilon and the general qualifications for membership. Service projects and publications, research awards, timely facts, the year of each chapter's origination, national presidents, and executive secretaries for the last 40 years are listed. (BP)

  11. Hydrological and Climatic Significance of Martian Deltas

    Science.gov (United States)

    Di Achille, G.; Vaz, D. A.

    2017-10-01

    We a) review the geomorphology, sedimentology, and mineralogy of the martian deltas record and b) present the results of a quantitative study of the hydrology and sedimentology of martian deltas using modified version of terrestrial model Sedflux.

  12. Yellow River Delta Faces a Historic Opportunity

    Institute of Scientific and Technical Information of China (English)

    Li Zhen

    2010-01-01

    @@ China's State Council has endorsed the Development Plan of an Efficient Eco-Economic Zone at Yellow River Delta. The plan is meant to create a more ecologically sustainable economic zone along the river delta.

  13. Yellow River Delta Faces a Historic Opportunity

    Institute of Scientific and Technical Information of China (English)

    Li Zhen

    2011-01-01

    @@ China's State Council has endorsed the Development Plan of an Efficient Eco-Economic Zone at Yellow River Delta.The plan is meant to create a more ecologically sustainable economic zone along the river delta.

  14. On the modelling of river delta formation

    NARCIS (Netherlands)

    Geleynse, N.

    2013-01-01

    This thesis presents approaches to the modelling of river delta formation. In particular, it provides results of numerical stratigraphic-morphodynamic modelling of river delta formation under various environmental forcings.

  15. Adaptive delta management: Roots and branches

    NARCIS (Netherlands)

    Timmermans, J.S.; Haasnoot, M.; Hermans, L.M.; Kwakkel, J.H.; Rutten, M.M.; Thissen, W.A.H.

    2015-01-01

    Deltas are generally recognized as vulnerable to climate change and therefore a salient topic in adaptation science. Deltas are also highly dynamic systems viewed from physical (erosion, sedimentation, subsidence), social (demographic), economic (trade), infrastructures (transport, energy, metropoli

  16. Delta Vegetation and Land Use [ds292

    Data.gov (United States)

    California Department of Resources — Vegetation and land use are mapped for the approximately 725,000 acres constituting the Legal Delta portion of the Sacramento and San Joaquin River Delta area....

  17. Limited junctional diversity of V delta 5-J delta 1 rearrangement in multiple sclerosis patients.

    Science.gov (United States)

    Nowak, J S; Michałowska-Wender, G; Januszkiewicz, D; Wender, M

    1997-01-01

    T-cell receptor (TCR) delta gene repertoire, as assessed by V delta-J delta rearrangements, has been analyzed in nine multiple sclerosis (MS) cases and in 30 healthy individuals by seminested PCR technique. Among the V delta-J delta junctional diversities studied, the most striking result has been observed in V delta 5-J delta 1 rearrangement. The detection of repeated V delta 5-J delta 1 nucleotide sequences in all analyzed clones from seven out of nine patients studied proved the monoclonal nature of gamma delta T-cells with V delta 5-J delta 1 rearrangement. The clonal nature of this rearrangement proved by PAGE and sequencing analysis may suggest an antigen-driven expansion of gamma delta T cells and argues for a significant role of gamma delta T-cells with V delta 5-J delta 1 rearrangement in MS pathogenesis. However, it cannot be excluded that clonal expansion of these lymphocytes may represent secondary change to central nervous system damage.

  18. Reflections on Development Strategy of Pearl River Delta: In Comparison with Yangtze River Delta

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>1. A comparison between Pearl River Delta and Yangtze River Delta 1.1 Basic conditions 1.1.1 Location, area and scope Located in the southeast of Guangdong Province, the Pearl River Delta (PRD) as an economic zone is a compound delta

  19. Inverse magnetocaloric effect in Mn{sub 2}NiGa and Mn{sub 1.75}Ni{sub 1.25}Ga magnetic shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Sanjay, E-mail: sanju8419@gmail.com; Barman, S. R. [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452001 (India); Esakki Muthu, S.; Arumugam, S. [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli 620024 (India); Senyshyn, A. [Forschungsneutronenquelle Heinz Maier-Leibnitz FRM-II, Technische Universität München, Lichtenbergstrasse 1, 85747 Garching b. München (Germany); Rajput, P. [European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38000 Grenoble (France); Suard, E. [Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9 (France)

    2014-02-03

    Inverse magnetocaloric effect is demonstrated in Mn{sub 2}NiGa and Mn{sub 1.75}Ni{sub 1.25}Ga magnetic shape memory alloys. The entropy change at the martensite transition is larger in Mn{sub 1.75}Ni{sub 1.25}Ga, and it increases linearly with magnetic field in both the specimens. Existence of inverse magnetocaloric effect is consistent with the observation that magnetization in the martensite phase is smaller than the austenite phase. Although the Mn content is smaller in Mn{sub 1.75}Ni{sub 1.25}Ga, from neutron diffraction, we show that the origin of inverse magnetocaloric effect is the antiferromagnetic interaction between the Mn atoms occupying inequivalent sites.

  20. Study of 0.9 BaTiO{sub 3}-0.1 Ni{sub x}Zn{sub 1-x}Fe{sub 2}O{sub 4} magneto-electric composite ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Upadhyay, Sanjay Kumar; Reddy, V. Raghavnedra [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001 (India)

    2013-03-21

    Magnetic, ferroelectric, and magneto-electric studies are reported on 0.9 BaTiO{sub 3}-0.1 Ni{sub x}Zn{sub 1-x}Fe{sub 2}O{sub 4} (x = 0 to 1.0 at 0.2). The bi-phase nature of the prepared composites is confirmed by the x-ray diffraction measurements. The simultaneous presence of room temperature ferroelectric and magnetic orderings is confirmed by measuring the room temperature P-E and M-H loops of the prepared composites. The magneto-electric behavior is found maximum for the composite consisting of Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} as magnetic phase, which is explained on the basis of the magnetostrictive behavior of Ni{sub x}Zn{sub 1-x}Fe{sub 2}O{sub 4} phase.

  1. A solid solution series of atacamite type Ni{sub 2x}Mg{sub 2−2x}Cl(OH){sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Bette, Sebastian [TU Bergakademie Freiberg, Institute of Inorganic Chemistry, Leipziger Strasse 29, Freiberg 09596 (Germany); Dinnebier, Robert E. [Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart 70569 (Germany); Röder, Christian [TU Bergakademie Freiberg, Institute of Theoretical Physics, Leipziger Strasse 23, Freiberg 09596 (Germany); Freyer, Daniela, E-mail: daniela.freyer@chemie.tu-freiberg.de [TU Bergakademie Freiberg, Institute of Inorganic Chemistry, Leipziger Strasse 29, Freiberg 09596 (Germany)

    2015-08-15

    For the first time a complete solid solution series Ni{sub 2x}Mg{sub 2−2x}Cl(OH){sub 3} of an atacamite type alkaline main group metal chloride, Mg{sub 2}Cl(OH){sub 3}, and a transition group metal chloride, Ni{sub 2}Cl(OH){sub 3}, was prepared and characterized by chemical and thermal analysis as well as by Raman and IR spectroscopy, and high resolution laboratory X-ray powder diffraction. All members of the solid solution series crystallize in space group Pnam (62). The main building units of these crystal structures are distorted, edge-linked Ni/MgO{sub 4}Cl{sub 2} and Ni/MgO{sub 5}Cl octahedra. The distribution of Ni{sup 2+}- and Mg{sup 2+}-ions among these two metal-sites within the solid solution series is discussed in detail. The crystallization of the solid solution phases occurs via an intermediate solid solution series, (Ni/Mg)Cl{sub 2x}(OH){sub 2−2x}, with variable Cl: OH ratio up to the 1:3 ratio according to the formula Ni{sub 2x}Mg{sub 2−2x} Cl(OH){sub 3}. For one isolated intermediate solid solution member, Ni{sub 0.70}Mg{sub 0.30}Cl{sub 0.58}(OH){sub 1.42}, the formation and crystal structure is presented as well. - Graphical abstract: For the first time a complete solid solution series, Ni{sub 2x}Mg{sub 2−2x} Cl(OH){sub 3}, was synthesized and characterized. Structure solution by revealed that Ni{sup 2+} prefers to occupy the Jahn–Teller-like distorted hole, out of two available cation sites. Substitution of Ni{sup 2+} by Mg{sup 2+} in atacamite type Ni{sub 2}Cl(OH){sub 3} results in systematic band shifts in Raman and IR spectra as well as in systematic changes in thermal properties. The α-polymorphs M{sub 2}Cl(OH){sub 3} with M=Mg{sup 2+}, Ni{sup 2+} and other divalent transition metal ions, as described in literature, were identified as separate compounds. - Highlights: • First synthesis of solid solution series between main and transition metal chloride. • Ni{sup 2+} prefers to occupy Jahn–Teller-like distorted octahedral holes

  2. What is $\\Delta m^2_{ee}$ ?

    CERN Document Server

    Parke, Stephen

    2016-01-01

    The current short baseline reactor experiments, Daya Bay and RENO (Double Chooz) have measured (or are capable of measuring) an effective $\\Delta m^2$ associated with the atmospheric oscillation scale of 0.5 km/MeV in electron anti-neutrino disappearance. In this paper, I compare and contrast the different definitions of such an effective $\\Delta m^2$ and argue that the simple, L/E independent, definition given by $\\Delta m^2_{ee} \\equiv \\cos^2 \\theta_{12} \\Delta m^2_{31}+ \\sin^2 \\theta_{12} \\Delta m^2_{32}$, i.e. "the $\

  3. Study on mechanism of soft magnetic properties for high-frequency application in Ni{sub 75}Fe{sub 25}-SiO{sub 2} granular films

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Shihui; Yang, Xiaolin; Xi, Li; Kou, Xiaoming; Yao, Dongsheng; Li, Binsheng; Wang, Xinwei [Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Youn Kim, Kwang [Advanced Metals Research Center, Korea Institute of Science and Technology, 39-1 Hawolgok-dong Seungbuk-gu, Seoul 136-791 (Korea)

    2005-08-01

    Excellent soft magnetic properties have been achieved in a wide metal volume fraction (x) range for as-deposited (Ni{sub 75}Fe{sub 25}){sub x}-(SiO{sub 2}){sub (1-x)} granular films fabricated by magnetron sputtering. With x changes from 0.81 to 0.52, the films exhibit small coercivity (H{sub c}) not exceeding 5 Oe and high electrical resistivity {rho}. The minimum H{sub c} value of 87.6 A m{sup -1} was obtained for the sample of x=0.81. At the frequency lower than 550 MHz, the real part {mu}' of complex permeability keeps about 170 and the image part {mu}{sup ''} is less than 26. Especially, for the film with very low x (=0.52), besides the low H{sub c} ({proportional_to}3 Oe), very high {rho} over 1.18 x 10{sup 4} {mu}{omega} cm has been obtained. A combined study of TEM and XRD indicates that the samples consist of Ni{sub 75}Fe{sub 25} particles uniformly embedded in insulating SiO{sub 2} matrix. The excellent soft magnetic property is ascribed to the exchange coupling among magnetic particles due to the long exchange length of Ni{sub 75}Fe{sub 25}. The investigation of the Henkel plot evidences the existence of this intergranular interaction. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Arrays of nanostructured antidot in Ni{sub 80}Fe{sub 20} magnetic thin films by photolithography of polystyrene nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Tiberto, Paola, E-mail: tiberto@inrim.it [INRIM, Electromagnetism Dept., Torino (Italy); Boarino, Luca; Celegato, Federica; Barrera, Gabriele; De Leo, Natascia; Coisson, Marco; Vinai, Franco [INRIM, Electromagnetism Dept., Torino (Italy); Allia, Paolo [INRIM, Electromagnetism Dept., Torino (Italy); DISMIC, Politecnico di Torino (Italy)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Arrays of antidot in Ni{sub 80}Fe{sub 20} thin films by photolithography of polystyrene nanospheres. Black-Right-Pointing-Pointer Well-ordered Antidot arrays on a large scale. Black-Right-Pointing-Pointer Novel method exploiting optical lithography with enhanced spatial resolution. Black-Right-Pointing-Pointer We report on the presence of an anisotropic magnetoresistance signal. - Abstract: Ordered nanostructures consisting in arrays of nanopores and nanoholes in magnetic thin films have been the subject of intensive research. In this work, a novel multi-step lithography process based on self-assembling of polystyrene nanospheres is proposed to pattern arrays of nanoholes on a Ni{sub 80}Fe{sub 20} thin film. Such a method allows antidot patterns to be fabricated on a wider area with respect to the standard sequential lithography. A polymeric mask is created by depositing a layer of polystyrene nanospheres on a photoresist subsequently exposed to a mercury lamp. The novelty in the procedure lies in exploiting low-cost and fast, non-sequential optical lithography with enhanced spatial resolution. Arrays of holes having mean size ranging in the interval of 250-280 nm depending on the experimental conditions have been prepared in Ni{sub 80}Fe{sub 20} films of different thickness (between 20 and 60 nm). Sample morphology has been checked by scanning electron microscopy. Magnetic and magnetotransport properties have been measured as a function of temperature on films of different thickness. An anisotropic magnetoresistance effect has been observed in all patterned films independent on the film thickness. This result, similar to the ones reported for patterned nanostructure obtained with conventional lithography techniques, confirms the potential of the proposed technique.

  5. Structure, microstructure and magnetic properties of Ni{sub 75}Fe{sub 25} films elaborated by evaporation from nanostructured powder

    Energy Technology Data Exchange (ETDEWEB)

    Kaibi, A., E-mail: kaibi_amel@yahoo.fr [Laboratory of Materials Physics (LPM), Faculty of Physics, USTHB, BP 32 El Alia, Algiers (Algeria); Guittoum, A. [Nuclear Research Centre of Algiers, 02 Bd Frantz Fanon, BP 399, Algiers (Algeria); Öksüzoğlu, R.M.; Yağci, A.M. [University of Anadolu, Faculty of Engineering, Department of Materials Sciences and Engineering, İkiEylül Campus, 26555 Eskişehir (Turkey); Boudissa, M. [ENMC Laboratory, Physics Department, University of Sétif, 19000 (Algeria); Kechouane, M. [Laboratory of Materials Physics (LPM), Faculty of Physics, USTHB, BP 32 El Alia, Algiers (Algeria)

    2015-09-30

    Highlights: • Ni{sub 75}Fe{sub 25} permalloy (Py) thin films with different thicknesses were deposited by vacuum evaporation from nanocrystalline powder onto Si(1 1 1) substrate. • The texture was found to change with increasing thickness. • The existence of nanosized grains with a uniform distribution has been observed. • The existence of a uniaxial magnetic anisotropy with an easy axis parallel to the film plane has been evidenced. • The coercive field was found to decrease with increasing thickness. - Abstract: We report on the structural, microstructural and magnetic properties of Ni{sub 75}Fe{sub 25} permalloy (Py) thin films. Py thin films with different thicknesses were deposited by vacuum evaporation from nanocrystalline powder onto Si (11) substrate. The thickness varies from 16 nm to 250 nm. From grazing X-ray diffraction patterns (GIXRD), we have shown the presence of a strong 〈200〉 texture for the lowest thickness (16 nm). For the 52 nm and 84 nm thick samples, a strong 〈111〉 preferred orientation is developed. However, for higher thicknesses, a polycrystalline structure is present. From the Scanning Electron Microscopy observations (SEM), we have shown that the surface seems to be very dense with many fine grains. The analysis of EDX spectra revealed that the sample composition is close to the starting Ni{sub 75}Fe{sub 25} powder. A more accurate investigation of the morphology was performed with the atomic force microscopy (AFM). We have shown the existence of nanosized grains with a uniform distribution. The mean diameter of the grains increases from 27 nm to 40 nm when the thickness increases. From magnetic measurements, we have shown the existence of a uniaxial magnetic anisotropy with an easy axis parallel to the film plane. The coercive field, H{sub C} was found to decrease with increasing thickness.

  6. Decoration of carbon nanotubes with magnetic Ni{sub 1-x}Co{sub x}Fe{sub 2}O{sub 4} nanoparticles by microemulsion method

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Syed Tajammul, E-mail: dr_tajammul@yahoo.ca [National Centre for Physics, Quaid-e-Azam University Campus, Islamabad 44000 (Pakistan); Gilani, Syeda Rubina [Department of Chemistry, University of Engineering and Technology, Lahore (Pakistan); Ali, Syed Danish [National Centre for Physics, Quaid-e-Azam University Campus, Islamabad 44000 (Pakistan); Department of Chemistry, University of Engineering and Technology, Lahore (Pakistan); Safdar Bhatti, Humaira [National Centre for Physics, Quaid-e-Azam University Campus, Islamabad 44000 (Pakistan)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer The novel Ni{sub 1-x}Co{sub x}Fe{sub 2}O{sub 4}/CNTs nanocomposites were synthesized. Black-Right-Pointing-Pointer A simple microemulsion method was first time used for the synthesis of nanocomposites. Black-Right-Pointing-Pointer Carbon nanotubes were coated with large quantity of magnetic nanoparticles. Black-Right-Pointing-Pointer Ferrite/CNTs nanocomposites show ferromagnetic behavior at room temperature. Black-Right-Pointing-Pointer Ferrite/CNTs nanocomposites have many applications in nanoscience and technology. - Abstract: In this study, magnetic monodisperse ferrite Ni{sub 1-x}Co{sub x}Fe{sub 2}O{sub 4} (x = 0.2, 0.4, 0.5, 0.6 and 0.8) nanoparticles have been successfully deposited on the side wall of the carbon nanotubes by a simple, effective and reproducible microemulsion method. The structure, composition and size of the as prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Rutherford backscattering spectroscopy (RBS) and scanning electron microscopy (SEM). Vibrating sample magnetometer was used to investigate magnetic properties of prepared samples. Results indicated that a large number of high purity magnetic ferrite nanoparticles of size about 15-25 nm were decorated uniformly on the surface of carbon nanotubes. Magnetic measurements showed that all the CNTs decorated with ferrite nanoparticles show ferromagnetic behavior at room temperature and can be easily manipulated by an external magnetic field. The maximum saturation magnetization value of the Ni{sub 1-x}Co{sub x}Fe{sub 2}O{sub 4}/CNTs nanocomposites reached 44.21 emu/g. These magnetic ferrite/CNTs nanocomposites have many potential applications ranging from biomedical field to electromagnetic devices.

  7. Microstructural characterization of rapidly solidified Cu{sub 50}Zr{sub 40}Ni{sub 5}Ti{sub 5} amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kursun, Celal, E-mail: celalkursun@ksu.edu.tr [Department of Physics, Faculty of Art and Sciences, Kahramanmaras Sutcu Imam University, Kahramanmaras 46100 (Turkey); Gögebakan, Musa [Department of Physics, Faculty of Art and Sciences, Kahramanmaras Sutcu Imam University, Kahramanmaras 46100 (Turkey); Gencer, Yucel [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze, 41400 Kocaeli (Turkey)

    2015-09-15

    The amorphous Cu{sub 50}Zr{sub 40}Ni{sub 5}Ti{sub 5} alloy was produced by melt-spinning at wheel speeds of 35, 38 and 41 m s{sup −1}. The resulting melt-spun ribbons were characterised using X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDX), differential scanning calorimetry (DSC) and Vickers microhardness (HV) tester. The XRD and SEM results revealed that the rapidly solidified ribbons have a fully amorphous structure. After partial or fully crystallisation of Cu{sub 50}Zr{sub 40}Ni{sub 5}Ti{sub 5} ribbons upon annealing, the microstructure had uneven and irregularly shaped features with the existence of Cu{sub 10}Zr{sub 7}, Cu{sub 8}Zr{sub 3}, CuZr and FCC-Cu phases while as quenched ribbons had featureless microstructure. The SEM-EDX analysis confirmed compositional homogeneity of the Cu{sub 50}Zr{sub 40}Ni{sub 5}Ti{sub 5} alloy ribbon. According to DSC results, the amorphous ribbons exhibited distinct glass transition temperature (T{sub g}) and wide supercooled liquid region (ΔT{sub x} = T{sub x} − T{sub g}) before crystallization. Accordingly, T{sub g} and ΔT{sub x} are around 409–414 °C and 37–54 °C, respectively. The microhardness of the as-quenched ribbons was about 522 HV while it decreased with increasing annealing temperature and had a value of 463 HV for 725 °C.

  8. [delta-Aminolevulinate dehydratase deficiency].

    Science.gov (United States)

    Fujita, H; Ishida, N; Akagi, R

    1995-06-01

    delta-Aminolevulinate dehydratase (ALAD: E. C. 4.2.1.24), the second enzyme in the heme biosynthetic pathway, condenses two moles of delta-aminolevulinic acid to form porphobilinogen. ALAD deficiency is well known to develop signs and symptoms of typical hepatic porphyria, and classified into three categories as follows: (i) ALAD porphyria, a genetic defect of the enzyme, (ii) tyrosinemia type I, a genetic defect of fumarylacetoacetase in the tyrosine catabolic pathway, producing succinylacetone (a potent inhibitor of ALAD), and (iii) ALAD inhibition by environmental hazards, such as lead, trichloroethylene, and styrene. In the present article, we will describe molecular and biochemical mechanisms to cause the enzyme defect to discuss the significance of ALAD defect on human health.

  9. Periodicity in Delta-modulated feedback control

    Institute of Scientific and Technical Information of China (English)

    Xiaohua XIA; Guanrong CHEN; Rudong GAI; Alan S. I. ZINOBER

    2008-01-01

    The Delta-modulated feedback control of a linear system introduces nonlinearity into the system through switchings between two input values. It has been found that Delta-modulation gives rise to periodic orbits. The existence of periodic points of all orders of Sigma-Delta modulation with "leaky" integration is completely characterized by some interesting groups of polynomials with "sign" coefficients. The results are naturally generalized to Sigma-Delta modulations with multiple delays, Delta-modulations in the "downlink", unbalanced Delta-modulations and systems with two-level quantized feedback. Further extensions relate to the existence of periodic points arising from Delta-modulated feedback control of a stable linear system in an arbitrary direction, for which some necessary and sufficient conditions are given.

  10. Entendiendo Delta desde las Humanidades

    OpenAIRE

    José Calvo Tello

    2016-01-01

    Stylometry is one of the research areas in greater development within Digital Humanities. However, few studies have worked until recently with texts in Spanish and even less so from Spanish-speaking countries. The aim of this paper is to present in Spanish, and without prior statistical knowledge from the reader, one of the main methods used in stylometry, the measure of textual distance Burrows’ Delta. This paper explains this measure using a very small corpus of proverbs and then checks the...

  11. Effects of antidot shape on the spin wave spectra of two-dimensional Ni{sub 80}Fe{sub 20} antidot lattices

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Ruma; Laha, Pinaki; Das, Kaustuv; Saha, Susmita; Barman, Saswati; Raychaudhuri, A. K.; Barman, Anjan, E-mail: abarman@bose.res.in [Thematic Unit of Excellence on Nanodevice Technology, Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India)

    2013-12-23

    We show that the optically induced spin wave spectra of nanoscale Ni{sub 80}Fe{sub 20} (permalloy) antidot lattices can be tuned by changing the antidot shape. The spin wave spectra also show an anisotropy with the variation of the in-plane bias field orientation. Analyses show this is due to various quantized and extended modes, whose nature changes with the antidot shape and bias field orientation as a result of the variation of the internal magnetic field profile. The observed variation and anisotropy in the spin waves with the internal and external parameters are important for their applications in magnonic devices.

  12. Effect of the milling energy on the production and thermal stability of amorphous Mg{sub 50}Ni{sub 50}

    Energy Technology Data Exchange (ETDEWEB)

    Guzman, D. [Departamento de Ingenieria Metalurgica, Facultad de Ingenieria, Universidad de Santiago de Chile, Av. Lib. Bernardo O' Higgins 3363, Santiago (Chile); Ordonez, S. [Departamento de Ingenieria Metalurgica, Facultad de Ingenieria, Universidad de Santiago de Chile, Av. Lib. Bernardo O' Higgins 3363, Santiago (Chile)], E-mail: sordonez@usach.cl; Serafini, D. [Departamento de Fisica, Facultad de Ciencias, Universidad de Santiago de Chile and Center for Interdisciplinary Research in Materials, CIMAT, Av. Lib. Bernardo O' Higgins 3363, Santiago (Chile); Rojas, P. [Instituto de Fisica, Facultad de Ciencias Basicas y Matematicas, Pontificia Universidad Catolica de Valparaiso, Av. Brasil 2950, Valparaiso (Chile); Bustos, O. [Departamento de Ingenieria Metalurgica, Facultad de Ingenieria, Universidad de Santiago de Chile, Av. Lib. Bernardo O' Higgins 3363, Santiago (Chile)

    2009-03-05

    The effect of milling energy on the amorphisation process and subsequent thermal crystallization of Mg{sub 50}Ni{sub 50} was investigated. The amorphous Mg{sub 50}Ni{sub 50} was produced using a planetary mill (medium energy) with a ball to material weight ratio of 13:1, and a SPEX mill (high energy) with a ball to material weight ratio of 20:1. The results obtained by means of X-ray diffraction showed that it is possible to obtain an amorphous Mg{sub 50}Ni{sub 50} alloy, through both milling processes, starting of Ni powders and Mg turnings. However, the amorphisation process requires more time in the planetary mill (80-90 h) than in the SPEX mill (15-20 h), due to the difference in energy level and milling mechanism between these mills. The phase evolution during the amorphisation process is practically independent of the mill energy. In this way, it was observed that the mill conditions promoted an extensive refinement of the microstructure during the first hours of milling. The defects produced during this time led to the amorphisation of part of the system. This amorphous precursor suffers a mechanically induced crystallization into Mg{sub 2}Ni, which is subsequently destabilized into amorphous Mg{sub 50}Ni{sub 50}. Based on the results obtained, it is proposed that the formation of amorphous precursor during mechanical milling of Mg and Ni is a characteristic of the Mg-Ni system, over a wide composition range, rather than of a particular composition. In relation to the thermal crystallization of the amorphous produced, the results of the differential thermal analysis applied to the amorphous samples showed that the formation enthalpy for both amorphous is the same, however, the amorphous produced in a planetary mill presented higher crystallization temperatures and apparent activation energies than the amorphous produced in a SPEX mill. The last behavior would be related with iron contamination coming from the erosion of the milling media. Finally, it is

  13. Coexistence of Kondo and spin-glass behaviour in Ce{sub 4}Y{sub 3}Ni{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Trovarelli, O. [Centro Atomico Bariloche, Comision Nacional de Energia Atomica, 8400 S.C. de Bariloche (Argentina); Sereni, J.G. [Centro Atomico Bariloche, Comision Nacional de Energia Atomica, 8400 S.C. de Bariloche (Argentina); Schmerber, G. [Institut de Physique et Chimie des Materiaux de Strasbourg, Groupe d`Etude des Materiaux Metallique, 23 rue du Loess, 67037 Strasbourg (France); Kappler, J.P. [Institut de Physique et Chimie des Materiaux de Strasbourg, Groupe d`Etude des Materiaux Metallique, 23 rue du Loess, 67037 Strasbourg (France)

    1995-02-09

    Magnetic susceptibility {chi} and specific heat C{sub P} measurements on Ce{sub 4}Y{sub 3}Ni{sub 3} are presented. The temperature of the maximum of {chi}{sub ac}(T) and C{sub P}(T) shifts with frequency and applied field respectively, as expected for a spin glass (SG) system. The C{sub P} (T{yields}0) dependence corresponds to that of an anisotropic SG. According to the entropy gain two Ce atoms are involved in the SG contribution and two exhibit Kondo effect. ((orig.)).

  14. Specific heat measurements on amorphous and nanocrystalline Al{sub 88}Y{sub 5}Ni{sub 5}Co{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Blazquez, J.S.; Millan, M.; Conde, C.F. [Dpto. Fisica de la Materia Condensada, ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065, 41080, Sevilla (Spain); Conde, A. [Dpto. Fisica de la Materia Condensada, ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065, 41080, Sevilla (Spain)], E-mail: conde@us.es; Latuch, J.; Kulik, T. [Faculty of Materials Science and Engineering, Warsaw University of Technology, ul. Woloska 141, 02-507, Warsaw (Poland)

    2009-06-10

    Specific heat at constant pressure, C{sub P}, was measured on amorphous and nanocrystalline Al{sub 88}Y{sub 5}Ni{sub 5}Co{sub 2} alloys from differential scanning calorimetry experiments. Linear behavior of C{sub P} versus temperature from 323 to 423 K is explained by conduction electrons contribution and dilatation correction factor. Results indicate that the Fermi energy increases as nanocrystallization progresses, although the estimated values are clearly lower than those found for crystalline Al.

  15. Nanoporous alumina formed by self-organized two-step anodization of Ni{sub 3}Al intermetallic alloy in citric acid

    Energy Technology Data Exchange (ETDEWEB)

    Stepniowski, Wojciech J., E-mail: wstepniowski@wat.edu.pl [Department of Advanced Materials and Technology, Faculty of New Technologies and Chemistry, Military University of Technology, Kaliskiego 2 Str., 00-908 Warszawa (Poland); Cieslak, Grzegorz; Norek, Malgorzata; Karczewski, Krzysztof; Michalska-Domanska, Marta; Zasada, Dariusz; Polkowski, Wojciech; Jozwik, Pawel; Bojar, Zbigniew [Department of Advanced Materials and Technology, Faculty of New Technologies and Chemistry, Military University of Technology, Kaliskiego 2 Str., 00-908 Warszawa (Poland)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer Anodic porous alumina was formed by Ni{sub 3}Al intermetallic alloy anodization. Black-Right-Pointing-Pointer The anodizations were conducted in 0.3 M citric acid. Black-Right-Pointing-Pointer Nanopores geometry depends on anodizing voltage. Black-Right-Pointing-Pointer No barrier layer was formed during anodization. - Abstract: Formation of the nanoporous alumina on the surface of Ni{sub 3}Al intermetallic alloy has been studied in details and compared with anodization of aluminum. Successful self-organized anodization of this alloy was performed in 0.3 M citric acid at voltages ranging from 2.0 to 12.0 V using a typical two-electrode cell. Current density records revealed different mechanism of the porous oxide growth when compared to the mechanism pertinent for the anodization of aluminum. Electrochemical impedance spectroscopy experiments confirmed the differences in anodic oxide growth. Surface and cross-sections of the Ni{sub 3}Al intermetallic alloy with anodic oxide were observed with field-emission scanning electron microscope and characterized with appropriate software. Nanoporous oxide growth rate was estimated from cross-sectional FE-SEM images. The lowest growth rate of 0.14 {mu}m/h was found for the anodization at 0 Degree-Sign C and 2.0 V. The highest one - 2.29 {mu}m/h - was noticed for 10.0 V and 30 Degree-Sign C. Pore diameter was ranging from 18.9 nm (2.0 V, 0 Degree-Sign C) to 32.0 nm (12.0 V, 0 Degree-Sign C). Interpore distance of the nanoporous alumina was ranging from 56.6 nm (2.0 V, 0 Degree-Sign C) to 177.9 nm (12.0 V, 30 Degree-Sign C). Pore density (number of pore occupying given area) was decreasing with anodizing voltage increase from 394.5 pores/{mu}m{sup 2} (2.0 V, 0 Degree-Sign C) to 94.9 pores/{mu}m{sup 2} (12.0 V, 0 Degree-Sign C). All the geometrical features of the anodic alumina formed by two-step self-organized anodization of Ni{sub 3}Al intermetallic alloy are depending on the

  16. Tunable spin wave dynamics in two-dimensional Ni{sub 80}Fe{sub 20} nanodot lattices by varying dot shape

    Energy Technology Data Exchange (ETDEWEB)

    Mahato, Bipul Kumar; Rana, Bivas; Kumar, Dheeraj; Barman, Saswati; Barman, Anjan, E-mail: abarman@bose.res.in [Thematic Unit of Excellence on Nanodevice Technology, Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Sugimoto, Satoshi [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Otani, YoshiChika [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); CEMS-RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

    2014-07-07

    We demonstrate tunable spin wave spectrum in two-dimensional Ni{sub 80}Fe{sub 20} nanodot lattices by varying dot shape. A single collective mode in elliptical dot lattices transforms into three distinct modes for the half-elliptical, rectangular, and diamond dot lattices, albeit with different peak frequencies and intensities. A drastic change is observed for the triangular dots, where eight modes covering a broad band are observed. Using micromagnetic simulations, we characterized the modes as different localized, extended, and quantized modes, whose frequencies and spatial profiles are determined by a combination of internal field profiles within the nanodots and the stray magnetic field within the lattice.

  17. Theoretical study of the electronic properties and exchange coupling in a Ni{sub 4} cubane like single-molecule magnet

    Energy Technology Data Exchange (ETDEWEB)

    Venegas-Yazigi, Diego [Centro para la Investigacion Interdisciplinaria Avanzada en Ciencias de los Materiales (CIMAT), Facultad de Ciencias Quimicas y Farmaceuticas, Universidad de Chile, Casilla 233, Independencia, Santiago (Chile)]. E-mail: dvy@uchile.cl; Cano, Joan [Departament de Quimica Inorganica and Centre de Recerca en Quimica Teorica Universitat de Barcelona, Diagonal 647, 08028 Barcelona (Spain); Ruiz, Eliseo [Departament de Quimica Inorganica and Centre de Recerca en Quimica Teorica Universitat de Barcelona, Diagonal 647, 08028 Barcelona (Spain); Alvarez, Santiago [Departament de Quimica Inorganica and Centre de Recerca en Quimica Teorica Universitat de Barcelona, Diagonal 647, 08028 Barcelona (Spain)

    2006-10-01

    Density functional theory (DFT) calculations on the tetranuclear Ni(II) complex [Ni{sub 4}(C{sub 5}H{sub 11}O{sub 3}){sub 4} (CH{sub 3}CN){sub 4}](NO{sub 3}){sub 4}.1.33NaNO{sub 3}, have been made in order to explain the exchange magnetic phenomenon. Two ferromagnetic exchange coupling constants were found (J{sub 1}=+13.27cm{sup -1} and J{sub 2}=+12.86cm{sup -1}) and these values are close to each other and consistent with the structural parameters of the complex.

  18. Magnetization and magnetotransport properties of Cu{sub 60}Fe{sub 20}Ni{sub 20} systems exhibiting magnetic frustration on the nanometer scale

    Energy Technology Data Exchange (ETDEWEB)

    Baricco, M.; Bosco, E.; Coisson, M. E-mail: coisson@ien.it; Rizzi, P.; Selvaggini, V.; Tiberto, P

    2003-05-01

    Magnetization and magnetoresistance of as quenched and joule-heated samples of the ternary alloy Cu{sub 60}Fe{sub 20}Ni{sub 20} have been measured at room temperature. Magnetic measurements have been performed up to 700 K. All studied samples display magnetic frustration on the nanometer scale; the size of the magnetically correlated regions can be estimated by properly combining magnetization and resistance data. Annealing promotes the magnetoresistive effect by enhancing the agreement between size of magnetically correlated regions and electron mean free path. The magnetic behaviour of the strongly annealed samples shows the evolution from a still dominant magnetic frustration to the first appearance of hysteretic features.

  19. Low temperature study of mechanically alloyed Fe{sub 67.5}Ni{sub 32.5} Invar sample

    Energy Technology Data Exchange (ETDEWEB)

    Valenzuela, J.L. [Departamento de Física, Universidad del Valle, A. A. 25360, Cali (Colombia); Valderruten, J.F. [Departamento de Ingeniería, Universidad Cooperativa de Colombia, Bucaramanga (Colombia); Pérez Alcázar, G.A., E-mail: gpgeperez@gmail.com [Departamento de Física, Universidad del Valle, A. A. 25360, Cali (Colombia); Colorado, H.D. [Departamento de Física, Universidad del Valle, A. A. 25360, Cali (Colombia); Romero, J.J. [Instituto de Microelectrónica de Madrid, CNM, CSIC, C/Isaac Newton 8, Tres Cantos, 28760 Madrid (Spain); González, J.M. [Unidad Asociada ICMM-IMA, Apdo. 155, Las Rozas, 28230 Madrid (Spain); Greneche, J.M. [LUNAM, Université du Maine, Institut des Molécules et Matériaux du Mans, UMR CNRS 6283, 72085 Le Mans, Cedex 9 (France); Marco, J.F. [Instituto de Química-Física ' ' Rocasolano' ' , CSIC, C/Serrano 119, 28006 Madrid (Spain)

    2015-07-01

    The study at low temperatures of powder of the Invar alloy, Fe{sub 67.5}Ni{sub 32.5}, produced by mechanical alloying, shows that the sample presents two structural phases, the Fe–Ni BCC and the Fe–Ni FCC. The {sup 57}Fe Mössbauer spectra obtained in this sample at different temperatures were fitted considering two hyperfine magnetic field distributions. The first one having the larger mean field and only one peak (at ca. 35 T, varying with T), is associated with the BCC phase, and the second one, presenting several broad peaks (distributed between 10 and 35 T), is associated to the FCC phase. A singlet, which is associated to low spin Fe sites of the FCC phase, was also considered. The mean hyperfine magnetic field of the BCC phase increases monotonically as temperature decreases, while that of the FCC phase presents an anomaly near 75 K. The real part of the ac magnetic susceptibility temperature scans presents a peak whose position increases from 31 to 39 K, when the ac field frequency increases from 100 to 5000 Hz. These results permit to associate the detected anomaly to the occurrence of a reentrant spin glass transition. - Highlights: • XRD detect the BCC and FCC nanocrystalline phases in the Invar Fe{sub 67.5}Si{sub 32.5}. • Mössbauer spectra were fitted with two HMFDs and a singlet. • The MHMF and the isomer shift of the FCC structure present a kink near 61 K. • Magnetic susceptibility proved that this anomaly corresponds to a RSG- F transition. • The Invar composition of the MA Fe{sub 67.5}Si{sub 32.5} alloy presents the frustration phenomena.

  20. Challenges, Approaches and Experiences from Asian Deltas and the Rhine-Meuse Delta : Regional Training Workshop on Delta Planning and Management

    NARCIS (Netherlands)

    Wosten, J.H.M.; Douven, W.; Long Phi, H.; Fida Abdullah Khan, M.

    2013-01-01

    River delta's, like the Mekong Delta (Vietnam), Ganges-Brahmaputra Delta (Bangladesh), Ayeyarwady Delta (Myanmar), Nile (Egypt) and Ciliwung Delta (Indonesia) are developing rapidly and are characterised by large-scale urbanisation and industrialization processes. They are facing serious planning ch

  1. Deformation characteristics of {delta} phase in the delta-processed Inconel 718 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H.Y., E-mail: haiyanzhang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Zhang, S.H., E-mail: shzhang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Cheng, M. [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Li, Z.X. [Beijing Institute of Aeronautica1 Materials, Beijing 100095 (China)

    2010-01-15

    The hot working characteristics of {delta} phase in the delta-processed Inconel 718 alloy during isothermal compression deformation at temperature of 950 deg. C and strain rate of 0.005 s{sup -1}, were studied by using optical microscope, scanning electron microscope and quantitative X-ray diffraction technique. The results showed that the dissolution of plate-like {delta} phase and the precipitation of spherical {delta} phase particles coexisted during the deformation, and the content of {delta} phase decreased from 7.05 wt.% to 5.14 wt.%. As a result of deformation breakage and dissolution breakage, the plate-like {delta} phase was spheroidized and transferred to spherical {delta} phase particles. In the center with largest strain, the plate-like {delta} phase disappeared and spherical {delta} phase appeared in the interior of grains and grain boundaries.

  2. Migration in Deltas: An Integrated Analysis

    Science.gov (United States)

    Nicholls, Robert J.; Hutton, Craig W.; Lazar, Attila; Adger, W. Neil; Allan, Andrew; Arto, Inaki; Vincent, Katharine; Rahman, Munsur; Salehin, Mashfiqus; Sugata, Hazra; Ghosh, Tuhin; Codjoe, Sam; Appeaning-Addo, Kwasi

    2017-04-01

    Deltas and low-lying coastal regions have long been perceived as vulnerable to global sea-level rise, with the potential for mass displacement of exposed populations. The assumption of mass displacement of populations in deltas requires a comprehensive reassessment in the light of present and future migration in deltas, including the potential role of adaptation to influence these decisions. At present, deltas are subject to multiple drivers of environmental change and often have high population densities as they are accessible and productive ecosystems. Climate change, catchment management, subsidence and land cover change drive environmental change across all deltas. Populations in deltas are also highly mobile, with significant urbanization trends and the growth of large cities and mega-cities within or adjacent to deltas across Asia and Africa. Such migration is driven primarily by economic opportunity, yet environmental change in general, and climate change in particular, are likely to play an increasing direct and indirect role in future migration trends. The policy challenges centre on the role of migration within regional adaptation strategies to climate change; the protection of vulnerable populations; and the future of urban settlements within deltas. This paper reviews current knowledge on migration and adaptation to environmental change to discern specific issues pertinent to delta regions. It develops a new integrated methodology to assess present and future migration in deltas using the Volta delta in Ghana, Mahanadi delta in India and Ganges-Brahmaputra-Meghna delta across India and Bangladesh. The integrated method focuses on: biophysical changes and spatial distribution of vulnerability; demographic changes and migration decision-making using multiple methods and data; macro-economic trends and scenarios in the deltas; and the policies and governance structures that constrain and enable adaptation. The analysis is facilitated by a range of

  3. Casimir force between $\\delta-\\delta^{\\prime}$ mirrors transparent at high frequencies

    CERN Document Server

    Braga, Alessandra N; Alves, Danilo T

    2016-01-01

    We investigate, in the context of a real massless scalar field in $1+1$ dimensions, models of partially reflecting mirrors simulated by Dirac $\\delta-\\delta^{\\prime}$ point interactions. In the literature, these models do not exhibit full transparency at high frequencies. In order to provide a more realistic feature for these models, we propose a modified $\\delta-\\delta^{\\prime}$ point interaction that enables to achieve full transparency in the limit of high frequencies. Taking this modified $\\delta-\\delta^{\\prime}$ model into account, we investigate the Casimir force, comparing our results with those found in the literature.

  4. Evolving deltas: Conceptualising coevolution with engineered interventions

    Science.gov (United States)

    Welch, Amy; Nicholls, Robert; Lazar, Attila

    2017-04-01

    Mid to low latitude deltas have been populated for thousands of years due to their fertile soil and coastal location. This has led to an alteration in the land cover of deltas to primary agriculture and dense rural settlements and more recently, major cities and megacities have developed on or adjacent to many deltas. Deltas may be prosperous in terms of their outputs and services; however, they are also susceptible to many hazards due to their location and low-lying nature. Hazards include storm surges, fluvial flooding and erosion of both coastal and riverine areas, as well as subsidence, relative sea-level rise and pollution. This can have severe impacts on the delta, its population and its services. Therefore engineered interventions have been used for some time to protect the population and the valuable land from the consequences of hazards. Coevolution can be described as a feedback loop between nature and humans: each has an effect on how the other behaves and hence this inter-dependence interaction continues. Therefore the natural evolution of the delta interacts with engineered interventions, such as promoting accelerated subsidence over time, necessitating further adaptation. The deltaic landscape and associated livelihoods are thus the result of this co-evolution process between natural delta processes and engineered interventions. This presentation will identify and discuss various drivers and consequences of large scale engineered interventions, comparing and contrasting the management approaches taken in five populated deltas (Ganges-Brahmaputra-Meghna, Yangtze, Rhine-Meuse-Scheldt, Mekong and Nile). The type of engineered intervention and management approaches had a direct effect on the coevolution of deltas, with each of the deltas being at different stages in terms of extent of coevolution. A qualitative timeline of the typical steps of coevolution between the human system and the delta system of the studied deltas was produced. The major

  5. Revealing the nature of magnetic phases in the semi-Heusler alloy Cu{sub 0.85}Ni{sub 0.15}MnSb

    Energy Technology Data Exchange (ETDEWEB)

    Halder, Madhumita, E-mail: mhalder@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Suresh, K.G., E-mail: suresh@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Mukadam, M.D. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Yusuf, S.M., E-mail: smyusuf@barc.gov.in [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2015-01-15

    We report the magnetic, magnetocaloric, and magnetotransport properties of the semi-Heusler alloy Cu{sub 0.85}Ni{sub 0.15}MnSb, which exhibits coexistence of antiferromagnetic (AFM) and ferromagnetic (FM) phases. A broad magnetic phase transition is evident from the temperature variations of magnetization, heat capacity, and isothermal magnetic entropy change. This is due to the presence of both AFM and FM phases at low temperatures. The variation of electrical resistivity with temperature shows three distinct regions of magnetic phases. The magnetoresistance (MR) results also show the presence of AFM and FM phases at temperatures below 45 K, and a FM phase at temperature above 45 K. Though there is no signature of a spin-glass state at low temperatures, various results point towards the presence of short-range magnetic correlations at low temperatures. - Highlights: • Magnetic, magnetocaloric, and magnetotransport properties of Cu{sub 0.85}Ni{sub 0.15}MnSb have been investigated. • Coexistence of antiferromagnetic and ferromagnetic phases at low temperature. • Resistivity and magnetoresistance with temperature shows three distinct regions of magnetic phases. • Presence of short-range magnetic correlations at low temperatures.

  6. A macroscopic constitutive model of temperature-induced phase transition of polycrystalline Ni{sub 2}MnGa by directional solidification

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yuping, E-mail: zhuyuping@126.com; Gu, Yunling; Liu, Hongguang

    2015-02-25

    Directional solidification technology has been widely used to improve the properties of polycrystalline Ni{sub 2}MnGa materials. Mechanical training can adjust the internal organizational structures of the materials, reduce the stress of twin boundaries motion, and then result in larger strain at lower outfield levels. In this paper, we test the microscopic structure of Ni{sub 2}MnGa polycrystalline ferromagnetic shape memory alloy produced by directional solidification and compress it along two axes successively for mechanical training. The influences of pre-compressive stresses on the temperature-induced strains are analyzed. The macroscopic mechanical behaviors show anisotropy. According to the generating mechanism of the macroscopic strain, a three-dimensional constitutive model is established. Based on thermodynamic method, the kinetic equations of the martensitic transformation and inverse transformation are presented considering the driving force and energy dissipation. The prediction curves of temperature-induce strains along two different directions are investigated. And the results coincide well with the experiment data. It well explains the macroscopic anisotropy mechanical behaviors and fits for using in engineering.

  7. Spin-glass-like behavior and negative thermal expansion in antiperovskite Mn{sub 3}Ni{sub 1−x}Cu{sub x}N compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Lei [Center for Condensed Matter and Materials Physics, Department of Physics, Beihang University, 100191 Beijing (China); Univ. Grenoble Alpes, Inst NEEL, F-38000 Grenoble (France); CNRS, Inst NEEL, F-38000 Grenoble (France); Wang, Cong, E-mail: congwang@buaa.edu.cn; Sun, Ying [Center for Condensed Matter and Materials Physics, Department of Physics, Beihang University, 100191 Beijing (China); Colin, Claire V. [Univ. Grenoble Alpes, Inst NEEL, F-38000 Grenoble (France); CNRS, Inst NEEL, F-38000 Grenoble (France); Chu, Lihua [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, School of Renewable Energy, North China Electric Power University, Beijing 102206 (China)

    2015-06-07

    The Cu-doping effect on the lattice and magnetic properties in Mn{sub 3}Ni{sub 1−x}Cu{sub x}N (x = 0, 0.3, 0.5, 0.7, 1.0) was extensively investigated. We observed that the Cu-doping at the Ni site complicated the magnetic ground states, which induced the competition of antiferromagnetic and ferromagnetic interactions. Spin-glass-like behavior, arising from possible site-randomness and competing interactions of magnetism, was observed in compounds with x = 0.3, 0.5, and 0.7, and typically discussed by means of the measurement of ac magnetic susceptibility for x = 0.7. The negative thermal expansion (NTE) behavior, due to the magnetic ordering transition, was observed in Mn{sub 3}Ni{sub 1−x}Cu{sub x}N compounds using variable temperature x-ray diffraction. It reveals that the introduction of Cu effectively broadens the temperature range displaying negative thermal expansion. The relationship between the local lattice distortion and the competing magnetic ground states might play an important role in broadening the NTE temperature range in this antiperovskite compound.

  8. An electrochemical study of the effect of Li on the corrosion behavior of Ni{sub 3}Al intermetallic alloy in molten (Li + K) carbonate

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Rodriguez, J.G. [Universidad Autonoma del Estado de Morelos, CIICAp, Av. Universidad 1001, Col. Chamilpa, 62209 Cuernavaca, Mor. (Mexico); Centro de Investigacion en Materiales Avanzados. S.C. Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chih. (Mexico)], E-mail: ggonzalez@uaem.mx; Mejia, E. [Universidad Autonoma del Estado de Morelos, CIICAp, Av. Universidad 1001, Col. Chamilpa, 62209 Cuernavaca, Mor. (Mexico); Lucio-Garcia, M.A. [Centro de Investigacion en Materiales Avanzados. S.C. Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chih. (Mexico); Salinas-Bravo, V.M.; Porcayo-Calderon, J. [Instituto de Inv. Electricas, Gerencia de Procesos Termicos, Reforma 108, Temixco, Mor. (Mexico); Martinez-Villafane, A. [Centro de Investigacion en Materiales Avanzados. S.C. Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chih. (Mexico)

    2009-08-15

    A study of the effect of lithium content (1, 3 and 5 wt.%) and heat treatment (400 deg. C during 144 h) on the corrosion behavior of Ni{sub 3}Al alloy has been carried out in a 62 mol.%Li{sub 2}CO{sub 3}-38 mol.%K{sub 2}CO{sub 3} mixture at 650 deg. C using electrochemical techniques. Employed electrochemical techniques included potentiodynamic polarization curves, linear polarization resistance, LPR, electrochemical impedance spectroscopy, EIS, and electrochemical noise, measurements EN. Results have shown that the alloys exhibited an active-passive behavior regardless of the heat treatment. For alloys without heat treatment, the most corrosion resistant was the Ni{sub 3}Al base alloy, but when they were heat treated, the most corrosion resistant was the alloy containing 3%Li. EIS results showed that for short immersion tests, the corrosion process was under diffusion control, but for longer exposure times, the presence of a protective scale was evident. All the alloys were highly susceptible to a localized type of corrosion according to EN measurements and supported by SEM micrographs.

  9. A visible-light-driven photocatalytic activity of vanadate garnet AgCa{sub 2}Ni{sub 2}V{sub 3}O{sub 12} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yuting; Chen, Luyang; Li, Yuze; Huang, Yanlin [Soochow University, College of Chemistry, Chemical Engineering and Materials Science (China); Cheng, Han; Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Pukyong National University, Department of Physics and Interdisciplinary Program of Biomedical, Mechanical and Electrical Engineering (Korea, Republic of)

    2015-10-15

    A visible-light-driven photocatalyst of nanosized vanadate garnet AgCa{sub 2}Ni{sub 2}V{sub 3}O{sub 12} was prepared by a modified Pechini method. The nanoparticles were characterized with the measurements such as X-ray powder diffraction (XRD) and structural refinements, scanning electron microscope (SEM), and UV–visible (UV–Vis) absorption spectrum. The sample has an efficient absorption in the UV–Vis light region with a narrow band-gap energy of 2.16 eV and an indirect allowed electronic transition. Besides, the photocatalysis of AgCa{sub 2}Ni{sub 2}V{sub 3}O{sub 12} nanoparticles was evaluated by photo-degradation of methylene blue under visible-light irradiation, which shows excellent photocatalytic activity. The effective photocatalytic activity was discussed on the base of the garnet crystal structure such as the activated optical centers of Ni–O octahedron and V–O tetrahedral, highly distorted Ag–O dodecahedra, and long V–V distance in the lattices.

  10. New NASICON-type Li{sub 2}Ni{sub 2}(MoO{sub 4}){sub 3} as a positive electrode material for rechargeable lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Prabaharan, S.R.S.; Michael, M.S. [Lithium Battery Technology Group, Faculty of Engineering, Center for Smart Systems and Innovation, Multimedia University, Jalan Multimedia, 63100 Cyberjaya (Malaysia); Fauzi, A. [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Begam, K.M. [Electrical, Automation and Computer Section, Universiti Kuala Lumpur-Malaysia France Institute, 43650 Bandar Baru Bangi (Malaysia)

    2004-07-30

    A new lithiated NASICON-type polyanion material, Li{sub 2}Ni{sub 2}(MoO{sub 4}){sub 3} was synthesized for the first time by means of a low temperature approach involving glycine as a mild combustion agent. The synthesized product, Li{sub 2}Ni{sub 2}(MoO{sub 4}){sub 3}, was found to crystallize in an orthorhombic structure (space group Pmcn) with cell parameters a=10.424(4) A, b=17.525(1) A and c=5.074(3) A. The electronic state of each element present in the new material was confirmed by X-ray photoelectron spectroscopic (XPS) analysis. The metals content present in the new material was analyzed using inductively coupled plasma emission spectroscopy (ICP-AES). Fiber-like submicrometre grains were evident from scanning electron microscopy (SEM) analysis of the annealed powders. The electrochemical performance of the new material was examined in a half-cell configuration against lithium metal employing a conventional Li{sup +} non-aqueous electrolyte. Slow scan cyclic voltammetry (SSCV) revealed the electrochemical reversibility of the material between the potential window of 4.9 V (charge cutoff) and 1.5 V (discharge cutoff). Reversible extraction/insertion of Li{sup +} from and into the framework structure delivered a reversible capacity of =115 mA h/g (4.9-1.5-V window) after the first charge/discharge cycle.

  11. Delta hepatitis agent: structural and antigenic properties of the delta-associated particle.

    Science.gov (United States)

    Bonino, F; Hoyer, B; Shih, J W; Rizzetto, M; Purcell, R H; Gerin, J L

    1984-01-01

    Delta agent (delta) was serially passaged to a second and third hepatitis B surface antigen (HBsAg) carrier chimpanzee, using as inoculum the peak delta antigen (delta Ag) serum of an animal previously infected with human serum. The characteristics of serially transmitted delta Ag were similar to those described in first-passage animals. It was consistently detected before the development of anti-delta, in association with a 35- to 37-nm subpopulation of HBsAg particles and a unique low-molecular-weight (5.5 X 10(5)) RNA. RNase susceptibility of the delta-associated RNA and release of delta Ag activity upon treatment of delta-associated particles with detergent revealed that this particle is organized into a virion-like form with the RNA and delta Ag as internal components within a coat of HBsAg. Surface determinants of the delta-associated particle other than HBsAg were not detected by radioimmunoprecipitation experiments, using sera of humans and chimpanzees convalescent from delta hepatitis. The HBsAg-associated particle is the "candidate agent" of delta hepatitis. Images PMID:6698598

  12. The Niger Delta Amnesty Program

    Directory of Open Access Journals (Sweden)

    Benjamin A. Okonofua

    2016-06-01

    Full Text Available The armed conflict between militias and government forces in Nigeria’s Niger Delta region has spanned for more than two decades, defying all solutions. A disarmament, demobilization, and reintegration (DDR program was established in August 2015 in effort to end the violence and has remained in place. It is a radically different approach from past approaches that displayed zero tolerance to all political challenges to oil production or the allocation of oil profits. The approach appeared to be immediately successful in that it forced a ceasefire, engaged militants in planned programs to rehabilitate and reintegrate them into civilian society, and opened up the oil wells (many of which had been shut due to the crisis with the effect of increasing government revenue, which depends 85% on oil exports. Yet, few studies have attempted to understand the dynamics within the country that are responsible for the design and implementation of this broad policy shift or to understand whether and how the current initiative is able to end the conflict and institute peace beyond the short term. This study, therefore, is important because it provides a critical perspective that anticipates and explains emerging issues with the Niger Delta Amnesty Program, which have implications for DDR adaptation and implementation all over the world. Ultimately, the research demonstrates how the DDR program both transforms the Niger Delta conflict and becomes embroiled in intense contestations not only about the mechanism for transforming the targeted population but also whether and how the program incorporates women who are being deprioritized by the program.

  13. Analysis and Synthesis of Delta Operator Systems

    CERN Document Server

    Yang, Hongjiu; Shi, Peng; Zhao, Ling

    2012-01-01

    This book is devoted to analysis and design on delta operator systems. When sampling is fast, a dynamical system will become difficult to control, which can be seen in wide real world applications. Delta operator approach is very effective to deal with fast sampling systems. Moreover, it is easy to observe and analyze the control effect with different sampling periods in delta operator systems. The framework of this book has been carefully constructed for delta operator systems to handle sliding mode control, time delays, filter design, finite frequency and networked control. These problems indeed are especially important and significant in automation and control systems design. Through the clear framework of the book, readers can easily go through the learning process on delta operator systems via a precise and comfortable learning sequence. Following this enjoyable trail, readers will come out knowing how to use delta operator approach to deal with control problems under fast sampling case. This book should...

  14. Delta Clipper - Design for supportability

    Science.gov (United States)

    Smiljanic, Ray R.; Conrad, Charles; Spaulding, Ed; Gisburne, Don

    1993-07-01

    The 'Delta Clipper' Single Stage Rocket Technology (SSRT) currently under development in the DC-X program will implement reliability-centered maintenance and support, involving on-equipment/off-equipment two-level maintenance, a logistics and spares pipeline, and a minimization of 'blue suit' skill-level personnel. Attention is given to the range of SSRT features that are to be validated via the DC-X test program; these prominently involve LRUs replaceability and accessibility, standardization and interchangeability, and 'aircraft-like' automated data collection.

  15. Climate change and the Delta

    Science.gov (United States)

    Dettinger, Michael; Anderson, Jamie; Anderson, Michael L.; Brown, Larry R.; Cayan, Daniel; Maurer, Edwin P.

    2016-01-01

    Anthropogenic climate change amounts to a rapidly approaching, “new” stressor in the Sacramento–San Joaquin Delta system. In response to California’s extreme natural hydroclimatic variability, complex water-management systems have been developed, even as the Delta’s natural ecosystems have been largely devastated. Climate change is projected to challenge these management and ecological systems in different ways that are characterized by different levels of uncertainty. For example, there is high certainty that climate will warm by about 2°C more (than late-20th-century averages) by mid-century and about 4°C by end of century, if greenhouse-gas emissions continue their current rates of acceleration. Future precipitation changes are much less certain, with as many climate models projecting wetter conditions as drier. However, the same projections agree that precipitation will be more intense when storms do arrive, even as more dry days will separate storms. Warmer temperatures will likely enhance evaporative demands and raise water temperatures. Consequently, climate change is projected to yield both more extreme flood risks and greater drought risks. Sea level rise (SLR) during the 20th century was about 22cm, and is projected to increase by at least 3-fold this century. SLR together with land subsidence threatens the Delta with greater vulnerabilities to inundation and salinity intrusion. Effects on the Delta ecosystem that are traceable to warming include SLR, reduced snowpack, earlier snowmelt and larger storm-driven streamflows, warmer and longer summers, warmer summer water temperatures, and water-quality changes. These changes and their uncertainties will challenge the operations of water projects and uses throughout the Delta’s watershed and delivery areas. Although the effects of climate change on Delta ecosystems may be profound, the end results are difficult to predict, except that native species will fare worse than invaders. Successful

  16. From Natural to Design River Deltas

    Science.gov (United States)

    Giosan, Liviu

    2016-04-01

    Productive and biologically diverse, deltaic lowlands attracted humans since prehistory and may have spurred the emergence of the first urban civilizations. Deltas continued to be an important nexus for economic development across the world and are currently home for over half a billion people. But recently, under the double whammy of sea level rise and inland sediment capture behind dams, they have become the most threatened coastal landscape. Here I will address several deceptively simple questions to sketch some unexpected answers using example deltas from across the world from the Arctic to the Tropics, from the Danube to the Indus, Mississippi to Godavari and Krishna, Mackenzie to Yukon. What is a river delta? What is natural and what is not in a river delta? Are the geological and human histories of a delta important for its current management? Is maintaining a delta the same to building a new one? Can we design better deltas than Nature? These answers help us see clearly that survival of deltas in the next century depends on human intervention and is neither assured nor simple to address or universally applicable. Empirical observations on the hydrology, geology, biology and biochemistry of deltas are significantly lagging behind modeling capabilities endangering the applicability of numerical-based reconstruction solutions and need to be ramped up significantly and rapidly across the world.

  17. Charged current weak electroproduction of $\\Delta$ resonance

    CERN Document Server

    Alvarez-Ruso, L; Vacas, M J V

    1998-01-01

    We study the weak production of $\\Delta$ (i.e. $e^{-} + p \\to \\Delta^{0}+ energy range corresponding to the Mainz and TJNAF electron accelerators. The differential cross sections $\\sigma(\\theta)$ are found to be of the order of $ 10^{-39}$ cm$^2$/sr, over a range of angles which increases with energy. The possibility of observing these reactions with the high luminosities available at these accelerators, and studying the weak N-$\\Delta$ transition form factors through these reactions is discussed. The production cross section of N$^*(1440)$ in the kinematic region of $\\Delta$ production is also estimated and found to be small.

  18. Delta Semantics Defined By Petri Nets

    DEFF Research Database (Denmark)

    Jensen, Kurt; Kyng, Morten; Madsen, Ole Lehrmann

    This report is identical to an earlier version of May 1978 except that Chapter 5 has been revised. A new paper: "A Petri Net Definition of a System Description Language", DAIMI, April 1979, 20 pages, extends the Petri net model to include a data state representing the program variables. Delta...... and the possibility of using predicates to specify state changes. In this paper a formal semantics for Delta is defined and analysed using Petri nets. Petri nets was chosen because the ideas behind Petri nets and Delta concide on several points. A number of proposals for changes in Delta, which resulted from...

  19. SNC 80 and related delta opioid agonists.

    Science.gov (United States)

    Calderon, S N; Coop, A

    2004-01-01

    The discovery of the selective delta (delta) opioid agonists SNC 80 and BW373U86, which possess a diarylmethylpiperazine structure unique among opioids, was a major advance in the field of delta-opioid ligands. Much research has been performed to uncover the structure-activity relationships (SAR) of this class of ligands and also to compare the diarylmethylpiperazines with the traditional morphinan-based delta opioids. This review focuses on the development of the SAR of this unique series of ligands, and discusses questions which remain unanswered.

  20. $\\Delta$ decay in nuclear medium

    CERN Document Server

    Jain, B K; Kundu, Bijoy

    1996-01-01

    Proton-nucleus collisions, where the beam proton gets excited to the delta resonance and then decays to p\\pi ^+, either inside or outside the nuclear medium, are studied. Cross-sections for various kinematics for the (p,p' \\pi ^+) reaction between 500 MeV and 1 GeV beam energy are calculated to see the effects of the nuclear medium on the propagation and decay of the resonance. The cross-sections studied include proton energy spectra in coincidence with the pion, four momentum transfer distributions, and the invariant p\\pi^+ mass distributions. We find that the effect of the nuclear medium on these cross-sections mainly reduces their magnitudes. Comparing these cross-sections with those considering the decay of the delta outside the nucleus only, we further find that at 500 MeV the two sets of cross-sections have large differences, while by 1 GeV the differences between them become much smaller.

  1. Ab initio calculations of martensitic phase behavior in Ni{sub 2}FeGa magnetic shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Soykan, C. [Department of Physics, Pamukkale University, Denizli, TR 20020 (Turkey); Özdemir Kart, S., E-mail: ozsev@pau.edu.tr [Department of Physics, Pamukkale University, Denizli, TR 20020 (Turkey); Sevik, C. [Department of Mechanical Engineering, Anadolu University, Eskişehir, TR 26470 (Turkey); Çağın, T. [Department of Material Science and Engineering, Texas A and M University, Texas, TX 77843-3003 (United States)

    2014-10-25

    Highlights: • L2{sub 1}, NM and 5M phases have the energy minimum at a = 5.76 Å, c/a = 1.33 and c/a = 0.99. • Decrement in moment of Ni and increment in that of Fe reflect electrons transfer. • Differences in minority DOS over MT lead to stabilize the final structure. • C' taking small value in L2{sub 1} leads to elastic instability in MT. - Abstract: A series of spin polarized energy calculations based on density functional theory (DFT) have been carried out to investigate the structural, magnetic, electronic and mechanical properties of Ni{sub 2}FeGa magnetic shape memory alloys (MSMA’s) in the austenitic and martensitic structures. We report that L2{sub 1} austenitic phase is metastable at a = 5.76 Å, the NM tetragonal and 5M monoclinic martensitic structures are stable at c/a = 1.33 and c/a = 0.99, respectively. That the electron removes from Ni to Fe site during phase transformation to martensite is confirmed by the increment in the magnetic moment of Ni, while decrement in that of Fe. The analysis of the partial density of states show that some distinguishable differences in the minority spin states occur upon martensitic phase transformation, such as, the replacement of the Fe states (e{sub g} and t{sub 2g}) above Fermi level by only Fe-t{sub 2g} states during L2{sub 1}-5M transformation and the splitting of Fe-t{sub 2g} states near Fermi level during 5M-NM transformation (through 7M). These changes lower the energy of the system, indicating that the final structure becomes stable. The soft tetragonal shear constant C′ of the austenitic phase designates the ease of the phase transition into martensitic phase. It is shown that the results calculated in this study are in good agreement with the previous calculations and the available experiments.

  2. Electrochemical hydrogen-storage properties of La{sub 0.78}Mg{sub 0.22}Ni{sub 2.67}Mn{sub 0.11}Al{sub 0.11}Co{sub 0.52}-M1Ni{sub 3.5}Co{sub 0.6}Mn{sub 0.4}Al{sub 0.}-5 composites

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Hongxia, E-mail: hhxhunan@126.com [Key Lab of New Processing Technology for Nonferrous Metals and Materials Ministry of Education, Guilin University of Technology, Guilin (China); Li, Guohui [Guangxi Scientific Experiment Center of Mining, Metallurgy and Environment, College of Chemistry and Bioengineering, Guilin University of Technology, Guilin (China); Zhuang, Shuxin [School of Material Science and engineering, Xiamen University of Technology, Xiamen (China)

    2013-07-15

    For improving the electrochemical properties of nonstoichiometric AB{sub 3} -type La{sub 0.7}8Mg{sub 0.22}Ni{sub 2.67}Mn{sub 0.11}Al{sub 0.11}Co{sub 0.52} alloy as negative electrode of Ni-MH battery, its related composites La{sub 0.78}Mg{sub 0.22}Ni{sub 2.67}Mn{sub 0.11}Al{sub 0.11}Co{sub 0.52}-x wt.% M1Ni{sub 3.5}Co{sub 0.6}Mn{sub 0.4}Al{sub 0.5} (x = 0, 10, 20, 30) were prepared. Analysis by X-ray diffractometry (XRD) revealed that the composites consist mainly of LaNi{sub 5} and La{sub 2}Ni{sub 7} phases. Despite the small decrease in the maximum discharge capacity, the cycle performance was significantly enhanced. Linear polarization (LP), anodic polarization (AP) and potential step discharge experiments revealed that the electrochemical kinetics increases first and then decreases with increasing x. (author)

  3. Comparative assessment of the vulnerability and resilience of deltas : extended version with 14 deltas : synthesis report

    NARCIS (Netherlands)

    Bucx, T.; Driel, van W.F.; Boer, de H.; Graas, S.; Langenberg, V.; Marchand, M.; Guchte, van de C.

    2014-01-01

    Worldwide, deltas host dense populations and are important centres of agricultural and industrial production, and economic activity. Many deltas are areas of great ecological importance as well, featuring wetlands of high and unique biodiversity. Deltas are vulnerable to changes by natural forces an

  4. $\\Delta I=4$ and $\\Delta I=8$ bifurcations in rotational bands of diatomic molecules

    CERN Document Server

    Bonatsos, Dennis; Lalazissis, G A; Drenska, S B; Minkov, N; Raychev, P P; Roussev, R P; Bonatsos, Dennis

    1996-01-01

    It is shown that the recently observed $\\Delta I=4$ bifurcation seen in superdeformed nuclear bands is also occurring in rotational bands of diatomic molecules. In addition, signs of a $\\Delta I=8$ bifurcation, of the same order of magnitude as the $\\Delta I=4$ one, are observed both in superdeformed nuclear bands and rotational bands of diatomic molecules.

  5. INFLUENCE OF THE DELTA-DELTA-MESON COUPLING ON NUCLEON AND DELTA PROPERTIES IN NUCLEAR-MATTER

    NARCIS (Netherlands)

    DEJONG, F; MALFLIET, R

    1994-01-01

    We introduce a scalar and a vector DELTADELTA-meson vertex in the relativistic Dirac-Brueckner model for nuclear matter and investigate the consequences. We find small effects on the effective nucleon properties. The effects in the DELTA sector are more profound, although the DELTA is still effectiv

  6. Synthesis and characterization of the NiFe{sub 2}O{sub 4}/Ni{sub 3}Fe nanocomposite powder and compacts obtained by mechanical milling and spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Marinca, T.F.; Neamţu, B.V.; Popa, F.; Tarţa, V.F. [Materials Sciences and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641 Cluj-Napoca (Romania); Pascuta, P. [Physics and Chemistry Department, Technical University of Cluj-Napoca, 103-105 Muncii Avenue, 400641 Cluj-Napoca (Romania); Takacs, A.F. [Faculty of Physics, Babeş-Bolyai University, 1 Mihail Kogălniceanu, 400084 Cluj-Napoca (Romania); Chicinaş, I., E-mail: Ionel.Chicinas@stm.utcluj.ro [Materials Sciences and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641 Cluj-Napoca (Romania)

    2013-11-15

    Nanocomposite powder and compacts of NiFe{sub 2}O{sub 4}/Ni{sub 3}Fe type were synthesized using mechanical milling and spark plasma sintering (SPS) techniques. The samples have been investigated by X-ray diffraction (XRD), laser particles size analysis, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDX). The nanocomposite powder was obtained by mechanical milling in a high planetary ball mill of nanocrystalline NiFe{sub 2}O{sub 4} and nanocrystalline Ni{sub 3}Fe powders. The nanocomposite powder consists from Ni{sub 3}Fe particles covered at the surface with a layer of NiFe{sub 2}O{sub 4} fine particles and NiFe{sub 2}O{sub 4} particles. The nanocomposite particles have the median diameter d{sub 50} of 1.6 μm. The sintering in 400–600 °C temperature range preserve the nanocomposite phases but lead to a high porosity. The nanocomposite compacts consist in Ni{sub 3}Fe clusters surrounded by NiFe{sub 2}O{sub 4}. A sintering temperature of 800 °C leads to a good density for the nanocomposite compacts and to the new phase formation. The new phase is a wustite type (Fe{sub 1−x}Ni{sub x}O) and is formed at the metal/ceramic interface. A change in the Ni/Fe ratio, in the spinel structure, was evidenced during sintering. Sintering at a temperature of 800 °C, leads to the formation of a mixed iron–nickel ferrite with a very small amount of nickel, Ni{sub 1−x}Fe{sub x}Fe{sub 2}O{sub 4}.

  7. Structural and Mössbauer spectroscopy characterization of bulk and nanostructured TiFe{sub 0.5} Ni{sub 0.5}/graphite compounds and their hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Martínez, M. A. R., E-mail: fisicorodriguez@gmail.com; André-Filho, J.; Félix, L. L.; Coaquira, J. A. H.; Garg, V. K.; Oliveira, A. C. [Universidade de Brasília, Instituto de Física, Núcleo de Física Aplicada (Brazil); Mestnik-Filho, J. [Instituto de Pesquisas energéticas e Nucleares, IPEN-CNEN/SP (Brazil)

    2015-06-15

    The structural and hyperfine properties of bulk TiFe{sub 0.5}Ni{sub 0.5} intermetallic and ball-milled TiFe{sub 0.5}Ni{sub 0.5}/graphite compounds and their hydrides have been studied. The bulk and nanostructured TiFe{sub 0.5}Ni{sub 0.5} compounds crystallize in the cubic crystal structure of CsCl (B2). After hydrogenation, the formation of hydrogen-poor phase (∝-phase) and hydride phase (β-phase) have been determined for the bulk compound. However, the formation of the ∝-phase and the hydrogen-richest phase (γ-phase) and other secondary phases have been determined for the ball-milled TiFe{sub 0.5}Ni{sub 0.5}/graphite sample. It has been determined that the ball-milled TiFe{sub 0.5}Ni{sub 0.5}/graphite sample presents a large amount of the γ-phase which indicates that the presence of graphite nearby nanostructured intermetallic grains enhances the absorption of hydrogen. Mossbauer results are consistent with the structural results. Meanwhile, no significant changes in the isomer shift (IS) value has been determined for the α-phase with respect to the intermetallic compound, a strong increase in the IS value has been determined for the β- and γ-phases with respect to the ∝-phase. That increase indicates a decrease of the s-electron density at the Fe nuclei due to the charge transfer from the metal to the nearby hydrogen atoms.

  8. X-ray photoelectron spectroscopy and magnetism of AlDyNi, AlDyNi{sub 4} and AlDy{sub 3}Ni{sub 8} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Rednic, V; Coldea, M; Rednic, L; Pascut, L G; Pintea, S [Babes-Bolyai University, Faculty of Physics, 1 Mihail Kogalniceanu, 400084 Cluj-Napoca (Romania); Aldea, N [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania); Neumann, M, E-mail: vasile.rednic@itim-cj.r [University of Osnabrueck, Fachbereich Physik, 49069 Osnabrueck (Germany)

    2009-08-01

    The electronic and magnetic properties of AlDyNi, AlDyNi{sub 4} and AlDy{sub 3}Ni{sub 8} are studied using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), static and dynamic magnetic measurements. The three compounds AlDyNi, AlDyNi{sub 4} and AlDy{sub 3}Ni{sub 8} are single phases and crystallize in the Fe{sub 2}P, CaCu{sub 5} and CeNi{sub 3} structure types, respectively. All the investigated compounds order ferromagnetically below the corresponding Curie temperatures. The Curie temperature and the magnetic moments are 25 K and 6 {mu}{sub B}/f.u. for AlDyNi, 14 K and 6.9 {mu}{sub B}/f.u. for AlDyNi{sub 4} and 22K and 19.2 {mu}{sub B}/f.u. for AlDy{sub 3}Ni{sub 8}. At high temperature the magnetic susceptibility obey the Curie-Weiss law. The paramagnetic Curie temperature and the effective magnetic moments are 30K and 10.88 {mu}{sub B}/f.u. for AlDyNi, 28 K and 10.94 {mu}{sub B}/f.u. for AlDyNi{sub 4} and 18 K and 18.33 {mu}{sub B}/f.u. for AlDy{sub 3}Ni{sub 8}. XPS valence band and Ni 2p spectra indicated the presence of small magnetic moment on Ni sites in AlDy{sub 3}Ni{sub 8} and AlDyNi{sub 4}, and a complete filling of Ni 3d band in AlDyNi.

  9. Electromagnetic excitation of the Delta(1232) resonance

    Energy Technology Data Exchange (ETDEWEB)

    V. Pascalutsa; M. Vanderhaeghen; Shin Nan Yang

    2006-09-05

    We review the description of the lowest-energy nucleon excitation--the Delta(1232)-resonance. Much of the recent effort has been focused on the precision measurements of the nucleon to Delta transition by means of electromagnetic probes. We review the results of those measurements and confront them with the state-of-the-art calculations based on chiral effective-field theories (EFT), lattice QCD, and QCD-inspired models. Some of the theoretical approaches are reviewed in detail. In particular, we describe the chiral EFT of QCD in the energy domain of the Delta-resonance, and its applications to the electromagnetic nucleon-to-Delta transition (gamma N Delta). We also describe the recent dynamical and unitary-isobar models of pion electroproduction which are extensively used in the extraction of the gamma* N Delta form factors from experiment. Furthermore, we discuss the link of the gamma* N Delta form factors to generalized parton distributions (GPDs), as well as the predictions of perturbative QCD for these transition form factors. The present status of understanding the Delta-resonance properties and the nature of its excitation is summarized.

  10. Structure and replication of hepatitis delta virus

    African Journals Online (AJOL)

    STORAGESEVER

    2008-12-29

    Dec 29, 2008 ... Unidade de Biologia Molecular, Centro de Malária e outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, ... molecules of both delta antigens (Ryu et al., 1993). This ..... Glenn JS, Watson JA, Havel CM, White JO (1992). ... HDV RNA encoding the large delta antigen cannot replicate. J. Gen.

  11. Generalised CP and $\\Delta (96)$ Family Symmetry

    CERN Document Server

    Ding, Gui-Jun

    2014-01-01

    We perform a comprehensive study of the $\\Delta (96)$ family symmetry combined with the generalised CP symmetry $H_{\\rm{CP}}$. We investigate the lepton mixing parameters which can be obtained from the original symmetry $\\Delta (96)\\rtimes H_{\\rm{CP}}$ breaking to different remnant symmetries in the neutrino and charged lepton sectors, namely $G_{\

  12. Delta Blues Scholarship and Imperialist Nostalgia.

    Science.gov (United States)

    Nye, William P.

    When Delta blues are considered to be "folk music," the genre is inextricably tied to the neocolonial, sharecropping system of cotton production characteristic of the Mississippi Delta region between the Civil War and World War II. "Imperialist nostalgia," then, arises in accounts which pay primary and positive tribute to blues…

  13. The delta opioid receptor tool box.

    Science.gov (United States)

    Vicente-Sanchez, Ana; Segura, Laura; Pradhan, Amynah A

    2016-12-03

    In recent years, the delta opioid receptor has attracted increasing interest as a target for the treatment of chronic pain and emotional disorders. Due to their therapeutic potential, numerous tools have been developed to study the delta opioid receptor from both a molecular and a functional perspective. This review summarizes the most commonly available tools, with an emphasis on their use and limitations. Here, we describe (1) the cell-based assays used to study the delta opioid receptor. (2) The features of several delta opioid receptor ligands, including peptide and non-peptide drugs. (3) The existing approaches to detect delta opioid receptors in fixed tissue, and debates that surround these techniques. (4) Behavioral assays used to study the in vivo effects of delta opioid receptor agonists; including locomotor stimulation and convulsions that are induced by some ligands, but not others. (5) The characterization of genetically modified mice used specifically to study the delta opioid receptor. Overall, this review aims to provide a guideline for the use of these tools with the final goal of increasing our understanding of delta opioid receptor physiology.

  14. Ion irradiation induced effects and magnetization reversal mechanism in (Ni{sub 80}Fe{sub 20}){sub 1−x}Co{sub x} nanowires and nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Naeem, E-mail: naeem.ahmad@iiu.edu.pk [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences (CAS), Beijing 100090 (China); Spintronics Laboratory, Department of Physics, Faculty of Basic and Applied Sciences (FBAS), International Islamic University H-10, Islamabad 44000 (Pakistan); Iqbal, Javed [Laboratory of Nanoscience and Technology, Department of Physics, International Islamic University, H-10, Islamabad,Pakistan (Pakistan); Chen, J.Y. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences (CAS), Beijing 100090 (China); Hussain, Asim [Spintronics Laboratory, Department of Physics, Faculty of Basic and Applied Sciences (FBAS), International Islamic University H-10, Islamabad 44000 (Pakistan); Shi, D.W.; Han, X.F. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences (CAS), Beijing 100090 (China)

    2015-03-15

    The effect of Co on the ferromagnetic characteristics of the Ni{sub 80}Fe{sub 20} nanocylinders having zero magnetostriction and soft magnetic nature is an interesting field of research. The (Ni{sub 80}Fe{sub 20}){sub 1−x}Co{sub x} nanocylinders have been prepared by electrodeposition into commercially available anodized aluminum oxide (AAO) nanoporous templates. The analysis of magnetization reversal from the angular dependence of coercivity has been studied in detail. This angular dependence of coercivity has shown a transition from curling to nucleation mode as a function of field angle for all (Ni{sub 80}Fe{sub 20}){sub 1−x}Co{sub x} nanocylinders depending upon the critical angle. The shape anisotropy, dipole–dipole interactions, surface effects and magnetocrystalline anisotropy have been found to play an effective role for the spontaneous magnetization in nanowires and nanotubes. It has been interestingly observed that the magnetostatic interactions or dipole–dipole interactions are dominant in nanocylinders regardless of its geometry. Furthermore, the prepared samples have been irradiated with He{sup 2+} ions (energy E=2 MeV, fluence=10{sup 14} ions/cm{sup 2} and ion current=16 nA) at room temperature using a 5-UDH-2pelletron tandem accelerator. The irradiations have created defects and these defects have induced changes in magnetization as a result an increase in coercivity as function of the ion fluences is observed. Such kind of behavior in coercivity enhancement and magnetization reduction can also be attributed to the stress relaxation and percolation in nonuniform states of ferromagnetic alloys, respectively. - Highlights: • We have prepared the ferromagnetic NiFeCo nanowires and nanotubes into anodized aluminum oxide templates (AAO) by electrodeposition method. • We have studied the magnetization reversal mechanism from the angle dependent coercivity measured by a hysteresis loop. • The ion irradiation effects on these nanostructures

  15. Entendiendo Delta desde las Humanidades

    Directory of Open Access Journals (Sweden)

    José Calvo Tello

    2016-05-01

    Full Text Available Stylometry is one of the research areas in greater development within Digital Humanities. However, few studies have worked until recently with texts in Spanish and even less so from Spanish-speaking countries. The aim of this paper is to present in Spanish, and without prior statistical knowledge from the reader, one of the main methods used in stylometry, the measure of textual distance Burrows’ Delta. This paper explains this measure using a very small corpus of proverbs and then checks the results in a corpus of Spanish novels. Both data and Python scripts are available to the community through GitHub, commented step by step so that you can play and visualize each step.

  16. Jiaxing: Delicacy of the Yangtze River Delta

    Institute of Scientific and Technical Information of China (English)

    WUXINYI; WANGNAN

    2004-01-01

    THE yangtze River Delta,where the Yangtzc River crosses China's east coast,has one of the country's most dynamic economies.In 1976Jcan Gottmann.a french geographer,called shanghai and its neighboring Yangtze River Delta the world's "sixth largest megalopolis." The Yangtze River Delta has 15 cities. Its territory accounts for one percent of China's total, 5.8 percent of hthe population, and 19.5 percent of the national GDP.In terms of both aggregate economy and growth speed, the Delta currently leads China and could likely be the "enginc" of the world's future economic growth. Located at the juncition of Shanghai Jiangsu and Zhejiang, Jiaxing City holds a central economic belt. It is within 100 kilometers of Shanghai, Hangzhou and Suzhou. In 200 and 2003, Jiaxing's GDP growth rate was first in Zhejiang Province and second among the 1.5 Delta cities.

  17. Differentiation of Boc-protected alpha,delta-/delta,alpha- and beta,delta-/delta,beta-hybrid peptide positional isomers by electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Raju, G; Ramesh, V; Srinivas, R; Sharma, G V M; Shoban Babu, B

    2010-06-01

    Two new series of Boc-N-alpha,delta-/delta,alpha- and beta,delta-/delta,beta-hybrid peptides containing repeats of L-Ala-delta(5)-Caa/delta(5)-Caa-L-Ala and beta(3)-Caa-delta(5)-Caa/delta(5)-Caa-beta(3)-Caa (L-Ala = L-alanine, Caa = C-linked carbo amino acid derived from D-xylose) have been differentiated by both positive and negative ion electrospray ionization (ESI) ion trap tandem mass spectrometry (MS/MS). MS(n) spectra of protonated isomeric peptides produce characteristic fragmentation involving the peptide backbone, the Boc-group, and the side chain. The dipeptide positional isomers are differentiated by the collision-induced dissociation (CID) of the protonated peptides. The loss of 2-methylprop-1-ene is more pronounced for Boc-NH-L-Ala-delta-Caa-OCH(3) (1), whereas it is totally absent for its positional isomer Boc-NH-delta-Caa-L-Ala-OCH(3) (7), instead it shows significant loss of t-butanol. On the other hand, second isomeric pair shows significant loss of t-butanol and loss of acetone for Boc-NH-delta-Caa-beta-Caa-OCH(3) (18), whereas these are insignificant for its positional isomer Boc-NH-beta-Caa-delta-Caa-OCH(3) (13). The tetra- and hexapeptide positional isomers also show significant differences in MS(2) and MS(3) CID spectra. It is observed that 'b' ions are abundant when oxazolone structures are formed through five-membered cyclic transition state and cyclization process for larger 'b' ions led to its insignificant abundance. However, b(1)(+) ion is formed in case of delta,alpha-dipeptide that may have a six-membered substituted piperidone ion structure. Furthermore, ESI negative ion MS/MS has also been found to be useful for differentiating these isomeric peptide acids. Thus, the results of MS/MS of pairs of di-, tetra-, and hexapeptide positional isomers provide peptide sequencing information and distinguish the positional isomers.

  18. Effect of cooling method on the electrochemical performance of layered-spinel composite cathode Li{sub 1.1}Ni{sub 0.25}Mn{sub 0.75}O{sub 2.3}

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yunjian [School of Material Science and Technology, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Wang, Qiliang; Gao, Yanyong [School of Material Science and Technology, Jiangsu University, Zhenjiang 212013 (China); Pan, Jun [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Su, Mingru, E-mail: lyjian122331@163.com [School of Material Science and Technology, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Hai, Bin; Zhu, Guangyan; Liu, Sanbing [Chery Science Research Institute, Chery Automobile Co., Ltd, Wuhu 241006 (China)

    2015-10-15

    Layered-spinel composite cathode material Li{sub 1.1}Ni{sub 0.25}Mn{sub 0.75}O{sub 2.3} has been synthesized and cooled by different methods (naturally cooled within the furnace and cooled in liquid nitrogen). The effect of cooling methods on physical and electrochemical properties are discussed using the characterizations of X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), charge/discharge, cyclic and rate tests. The layered-spinel composite structure has been detected in Li{sub 1.1}Ni{sub 0.25}Mn{sub 0.75}O{sub 2.3} electrodes from the XRD patterns and TEM images. XPS results show that the content of Mn{sup 3+} in the Li{sub 1.1}Ni{sub 0.25}Mn{sub 0.75}O{sub 2.3} cooled in liquid nitrogen is more than that of Li{sub 1.1}Ni{sub 0.25}Mn{sub 0.75}O{sub 2.3} cooled with furnace. The electrochemical performance results show that the Li{sub 1.1}Ni{sub 0.25}Mn{sub 0.75}O{sub 2.3} cooled in liquid nitrogen has higher initial discharge capacity, coulomb efficiency, better cyclic and rate performance compared with Li{sub 1.1}Ni{sub 0.25}Mn{sub 0.75}O{sub 2.3} cooled with furnace. EIS results show that the charge transfer resistance (R{sub ct}) of Li{sub 1.1}Ni{sub 0.25}Mn{sub 0.75}O{sub 2.3} cooled in liquid nitrogen is lower than that of Li{sub 1.1}Ni{sub 0.25}Mn{sub 0.75}O{sub 2.3} cooled with furnace. The improved cyclic and rate performances of Li{sub 1.1}Ni{sub 0.25}Mn{sub 0.75}O{sub 2.3} cooled in liquid nitrogen cathode are attributed to the lower R{sub ct} and more content of Mn{sup 3+}. - Graphical abstract: Layered-spinel composite cathode material Li{sub 1.1}Ni{sub 0.25}Mn{sub 0.75}O{sub 2.3} have been synthesized and cooled by different methods (naturally cooled within the furnace (‘a’) and cooled in liquid nitrogen (‘b’)). Compared with cooled with furnace (‘a’), the Li{sub 1.1}Ni{sub 0.25}Mn{sub 0.75}O{sub 2

  19. Magnetic and magnetocaloric properties of martensitic Ni{sub 2}Mn{sub 1.4}Sn{sub 0.6} Heusler alloy

    Energy Technology Data Exchange (ETDEWEB)

    Chernenko, Volodymyr A., E-mail: vladimir_chernenko@ehu.es [Universidad del Pais Vasco, Dept. Electricidad y Electronica, PO Box 644, Bilbao 48080 (Spain); Ikerbasque, Basque Foundation for Science, Bilbao 48011 (Spain); Barandiaran, Jose M. [Universidad del Pais Vasco, Dept. Electricidad y Electronica, PO Box 644, Bilbao 48080 (Spain); Rodriguez Fernandez, Jesus; Rojas, Daniel P. [CITIMAC, Fac. Ciencias, Univ. Cantabria, Santander 39005 (Spain); Gutierrez, Jon; Lazpita, Patricia [Universidad del Pais Vasco, Dept. Electricidad y Electronica, PO Box 644, Bilbao 48080 (Spain); Orue, Inaki [SGiker, Vicerrectorado de Inv. UPV/EHU, Sarriena s/n, Leioa 48940 (Spain)

    2012-10-15

    The evolutions of magnetic properties at low temperatures and the influence of magnetic field on the temperature dependence of specific heat in martensitic Ni{sub 2}Mn{sub 1.4}Sn{sub 0.6} Heusler alloy are studied. The frequency-dependent blocking temperature and considerable exchange bias below it are measured in the martensitic phase. From the analysis of the specific heat curves under magnetic field, a large inverse magnetocaloric effect manifested as the magnetic field induced rise of isothermal magnetic entropy and/or magnetic field induced adiabatic temperature decrease in the vicinity of the reverse magnetostructural transformation and a significant value of the conventional magnetocaloric effect at the Curie temperature are obtained. The Debye temperature and electronic coefficient equal to {Theta}{sub D}=310{+-}2 K and {gamma}= 16.6{+-}0.3 mJ/K{sup 2}mol, respectively, do not depend on the magnetic field.

  20. Genetic design and characterization of novel ultra-high-strength stainless steels strengthened by Ni{sub 3}Ti intermetallic nanoprecipitates

    Energy Technology Data Exchange (ETDEWEB)

    Xu, W., E-mail: w.xu@m2i.nl [Materials Innovation Institute M2i, Kluyverweg 1, 2629 HS, Delft (Netherlands)] [Novel Aerospace Materials (NovAM) Group, Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft (Netherlands); Rivera-Diaz-del-Castillo, P.E.J. [Novel Aerospace Materials (NovAM) Group, Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft (Netherlands); Wang, W.; Yang, K. [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Bliznuk, V.; Kestens, L.A.I. [Department of Materials Science and Engineering, Ghent University, Technologiepark 903, B 9052 Gent (Belgium); Zwaag, S. van der [Novel Aerospace Materials (NovAM) Group, Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft (Netherlands)

    2010-06-15

    A general computational alloy design approach based on thermodynamic and physical metallurgical principles, and coupled with a genetic optimization scheme, is presented. The method is applied to the design of new ultra-high-strength maraging stainless steels strengthened by Ni{sub 3}Ti intermetallics. In the first design round, the alloy composition is optimized on the basis of precipitate formation at a fixed ageing temperature without considering other steps in the heat treatment. In the second round, the alloy is redesigned, applying an integrated model which allows for the simultaneous optimization of alloy composition and the ageing temperature as well as the prior austenitization temperature. The experimental characterizations of prototype alloys clearly demonstrate that alloys designed by the proposed approach achieve the desired microstructures.

  1. Spark-plasma-sintering magnetic field assisted compaction of Co{sub 80}Ni{sub 20} nanowires for anisotropic ferromagnetic bulk materials

    Energy Technology Data Exchange (ETDEWEB)

    Ouar, Nassima; Schoenstein, Frédéric; Mercone, Silvana; Farhat, Samir; Jouini, Noureddine [Laboratoire des Sciences des Procédés et des Matériaux, CNRS, LSPM—UPR 3407, Université Paris 13, Sorbonne-Paris-Cité, 99 Avenue J.-B. Clément, 93430 Villetaneuse (France); Villeroy, Benjamin [Institut de Chimie et des Matériaux Paris Est, CNRS, ICMPE—UMR 7182, Equipe de Chimie Métallurgique des Terres Rares, 2-8 rue Henri Dunant, 94320 Thiais Cedex (France); Leridon, Brigitte [Laboratoire de Physique et d’Étude des Matériaux, LPEM, ESPCI-ParisTech, CNRS, UPMC, 10 rue Vauquelin, F-75231 Paris Cedex 5 (France)

    2013-10-28

    We developed a two-step process showing the way for sintering anisotropic nanostructured bulk ferromagnetic materials. A new reactor has been optimized allowing the synthesis of several grams per batch of nanopowders via a polyol soft chemistry route. The feasibility of the scale-up has been successfully demonstrated for Co{sub 80}Ni{sub 20} nanowires and a massic yield of ∼97% was obtained. The thus obtained nanowires show an average diameter of ∼6 nm and a length of ∼270 nm. A new bottom-up strategy allowed us to compact the powder into a bulk nanostructured system. We used a spark-plasma-sintering technique under uniaxial compression and low temperature assisted by a permanent magnetic field of 1 T. A macroscopic pellet of partially aligned nanowire arrays has been easily obtained. This showed optimized coercive properties along the direction of the magnetic field applied during compaction (i.e., the nanowires' direction)

  2. Improved plasticity by electropulsing in a Zr{sub 62}Al{sub 19}Ni{sub 19} bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J L; Lu, J X; Shek, C H, E-mail: apchshek@cityu.edu.h [Department of physics and materials science, City University of Hong Kong (Hong Kong)

    2009-01-01

    The present work reported the application of electropulsing technique (EPT) for improving plasticity of a Zr{sub 62}Al{sub 19}Ni{sub 19} bulk metallic glass. After the elecropulsing with a small current of 5A, no obvious crystallization was observed in X-ray diffraction (XRD) patterns. Results of differential scanning calorimetry (DSC) measurements indicated that the glass transition temperature was reduced from 698K to 691K. Room-temperature uniaxial compression tests revealed that the treated BMG showed larger plastic deformation up to 6%, compared with less than 2% plasticity of untreated sample, at a 1x10{sup -4} s{sup -1} strain rate. SEM observation showed that the sample after electropulsing treatment show significant difference in the distribution of shear bands from that of the untreated one.

  3. Multiferroic Ni{sub 3}V{sub 2}O{sub 8} measured in THz range at low temperatures and in high magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Langenbach, Malte; Hissen, Tobias; Thirunavukkuarasu, Komalavalli; Schmitz, Holger; Hemberger, Joachim; Grueninger, Markus [II. Physikalisches Institut, Universitaet zu Koeln (Germany); Camara Mayorga, Ivan; Guesten, Rolf [Max-Planck-Institut fuer Radioastronomie, Bonn (Germany)

    2013-07-01

    THz spectroscopy in high magnetic fields is an important technique to probe materials with strong magneto-electric coupling. Here, we discuss the Kagome-staircase compound Ni{sub 3}V{sub 2}O{sub 8}. The triangle-based lattice gives rise to a frustration of the short-range antiferromagnetic couplings. This causes a rich variety of magnetic and structural phases at low temperatures. Below T{sub N}=9.8 K, a incommensurate phase with collinear sinusoidal spin structure is established. This phase is followed by a cycloidal spin structure which is accompanied by the onset of ferroelectricity. Finally, below 3.9 K, the structure changes to a commensurate canted antiferromagnetic phase. We report on elementary excitations in the THz range observed between 2 K and 50 K in fields up to 8 T.

  4. Magnetic enhancement and coding in mechanosynthesized Ni{sub 0.3}Zn{sub 0.7}Fe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Majumder, S. [Department of Physics, Jadavpur University, Kolkata-700032 (India); Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata-700064 (India); Dey, S.; Kumar, S., E-mail: kumars@phys.jdvu.ac.in [Department of Physics, Jadavpur University, Kolkata-700032 (India); Dasgupta, P.; Poddar, A.; Banerjee, S. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata-700064 (India)

    2015-06-24

    The nanosized Ni{sub 0.3}Zn{sub 0.7}Fe{sub 2}O{sub 4} (∼ 15 nm) has been synthesized by high energy ball milling of the bulk powder sample. The sample has been characterized by powder x-ray diffraction, field emission and transmission electron microscopic and dc magnetic measurement techniques. The dc magnetic measurement on the sample indicates that the sample exhibit enhancement of magnetization compared to its counterparts synthesized by chemical methods. Moreover, the system stores the memory of either decrease or increase of magnetic field enabling a magnetic coding of “0” and “1” which can be profitably used in magnetic storage and sensing devices.

  5. Exchange bias behavior in Ni{sub 50.0}Mn{sub 35.5} In{sub 14.5} ribbons annealed at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, T. [Dept. de Fisica, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain); Sato Turtelli, R.; Groessinger, R. [Institut fur Festkoerperphysik, Technische Universitaet Wien, Wiedner Hauptstr. 8-10, 1040 Vienna (Austria); Sanchez, M.L.; Santos, J.D.; Rosa, W.O.; Prida, V.M. [Dept. de Fisica, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain); Escoda, Ll.; Sunol, J.J. [Campus de Montilivi, Universidad de Girona, edifici PII, Lluis Santalo s/n. 17003 Girona (Spain); Koledov, V. [Kotelnikov Institute of Radio Engineering and Electronics, RAS, Moscow 125009 (Russian Federation); Hernando, B., E-mail: grande@uniovi.es [Dept. de Fisica, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain)

    2012-10-15

    Heusler alloy Ni{sub 50.0}Mn{sub 35.5}In{sub 14.5} ribbons were prepared by melt-spinning technique. Several short time annealings were carried out in order to enhance the exchange bias effect in this alloy ribbon. The magnetic transition temperature increases with the annealing, compared to the as-spun sample, however no significant differences in respective Curie temperatures were observed for austenite and martensite phases in such annealed samples. Exchange bias effect is observed at low temperatures for all samples and practically vanishes at 60 K for the as-spun sample, whereas for the annealed ribbons it vanishes at 100 K.

  6. Cation distribution in Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} using X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, A. K., E-mail: akyadav@barc.gov.in; Jha, S. N.; Bhattacharyya, D.; Sahoo, N. K. [Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai - 400094 (India); Jadhav, J.; Biswas, S. [Department of Physics, The LNM Institute of Information Technology, Jaipur-302031 (India)

    2014-04-24

    Spinel ferrite samples of Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} (for x=0.2, 0.4, 0.5, 0.6 and 0.8) nanoparticles prepared by a novel chemical synthesis method have been characterized by X-ray Absorption Spectroscopy (XAS) technique to investigate the distribution of cations in the unit cell. XANES region clearly shows that as Ni concentration increases, the pre-edge feature, which is a characteristic of tetrahedral coordination of Fe, is enhanced. A quantitative determination of the relative occupancy of iron cation in the octahedral and tetrahedral sites of the spinel structure was obtained from EXAFS data analysis. It has been found that as atomic fraction of Ni is increased from 0.2 to 0.8, Fe occupancy at tetrahedral to octahedral sites is increased from 13:87 and to 39:61.

  7. Suppression of the ferromagnetic order in the Heusler alloy Ni{sub 50}Mn{sub 35}In{sub 15} by hydrostatic pressure

    Energy Technology Data Exchange (ETDEWEB)

    Salazar Mejía, C., E-mail: Catalina.Salazar@cpfs.mpg.de; Mydeen, K.; Naumov, P.; Medvedev, S. A.; Wang, C.; Schwarz, U.; Felser, C.; Nicklas, M., E-mail: nicklas@cpfs.mpg.de [Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden (Germany); Hanfland, M. [ESRF, BP220, 38043 Grenoble (France); Nayak, A. K. [Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden (Germany); Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Germany)

    2016-06-27

    We report on the effect of hydrostatic pressure on the magnetic and structural properties of the shape-memory Heusler alloy Ni{sub 50}Mn{sub 35}In{sub 15}. Magnetization and x-ray diffraction experiments were performed at hydrostatic pressures up to 5 GPa using diamond anvil cells. Pressure stabilizes the martensitic phase, shifting the martensitic transition to higher temperatures, and suppresses the ferromagnetic austenitic phase. Above 3 GPa, where the martensitic-transition temperature approaches the Curie temperature in the austenite, the magnetization shows no longer indications of ferromagnetic ordering. We further find an extended temperature region with a mixture of martensite and austenite phases, which directly relates to the magnetic properties.

  8. Workability of the supercooled liquid in the Zr{sub 65}Al{sub 10}Ni{sub 10}Cu{sub 15} bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Y.; Shibata, T.; Inoue, A.; Masumoto, T. [Tohoku Univ., Sendai (Japan). Inst. for Materials Research

    1997-12-19

    The workability of the supercooled liquid in metallic glass has been examined through the extrusion of a Zr{sub 6.5}Al{sub 10}Ni{sub 10}Cu{sub 15} at.% bulk glassy alloy with a wide supercooled liquid region. The metallic glass exhibited superplastic-like deformation behavior at high strain rates, resulting in an excellent workability. The working throughout a wide range of extrusion conditions was compatible with retaining the glass phase and the original strength. The extrusion maps and the expression between extrusion temperature, pressure and ram-speed have been established. Moreover, the features of working such as the Barus effect and the advantage of a small stepwise increase in strain rate have been revealed.

  9. Tuning exchange bias through zero field cooling from different remanent states above blocking temperature in Ni{sub 50}Mn{sub 36}Sb{sub 14} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, R.L. [Faculty of Physics and Electronic Technology, Hubei University, Wuhan 430062 (China); Department of Physics, Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701 (China); Xu, L.S.; Xiao, H.B.; Xu, L.F.; Yang, C.P. [Faculty of Physics and Electronic Technology, Hubei University, Wuhan 430062 (China); Sun, Z.G. [State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Marchenkov, V.V. [Institute of Metal Physics, Ekaterinburg 620041 (Russian Federation); Huang, J.C.A. [Department of Physics, Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701 (China)

    2012-11-15

    Changing remanent states above blocking temperature (T{sub B}) in Ni{sub 50}Mn{sub 36}Sb{sub 14} alloy has been proven to be an effective way of tuning the value and sign of exchange bias (EB) field. The hysteresis loops at 5 K exhibit double shifted shape, indicating that there are two opposite EB signs resulting from an imprint of domain pattern of ferromagnetic (FM) regions into anti-ferromagetic (AFM) ones during cooling. All the results demonstrate that the interfacial spin configuration plays a crucial role on the origin of EB, while the high cooling field not only induces a single FM domain state above T{sub B} but also tunes the fractions of FM and AFM interactions through martensitic transition. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Influence of different organic fertilizers on quality parameters and the delta(15)N, delta(13)C, delta(2)H, delta(34)S, and delta(18)O values of orange fruit (Citrus sinensis L. Osbeck).

    Science.gov (United States)

    Rapisarda, Paolo; Camin, Federica; Fabroni, Simona; Perini, Matteo; Torrisi, Biagio; Intrigliolo, Francesco

    2010-03-24

    To investigate the influence of different types of fertilizers on quality parameters, N-containing compounds, and the delta(15)N, delta(13)C, delta(2)H, delta (34)S, and delta(18)O values of citrus fruit, a study was performed on the orange fruit cv. 'Valencia late' (Citrus sinensis L. Osbeck), which was harvested in four plots (three organic and one conventional) located on the same farm. The results demonstrated that different types of organic fertilizers containing the same amount of nitrogen did not effect important changes in orange fruit quality parameters. The levels of total N and N-containing compounds such as synephrine in fruit juice were not statistically different among the different treatments. The delta(15)N values of orange fruit grown under fertilizer derived from animal origin as well as from vegetable compost were statistically higher than those grown with mineral fertilizer. Therefore, delta(15)N values can be used as an indicator of citrus fertilization management (organic or conventional), because even when applied organic fertilizers are of different origins, the natural abundance of (15)N in organic citrus fruit remains higher than in conventional ones. These treatments also did not effect differences in the delta(13)C, delta(2)H, delta(34)S, and delta(18)O values of fruit.

  11. Long term simulation of point defect cluster size distributions from atomic displacement cascades in Fe{sub 70}Cr{sub 20}Ni{sub 10}

    Energy Technology Data Exchange (ETDEWEB)

    Souidi, A., E-mail: aek_souidi@yahoo.fr [Université Dr. Tahar Moulay de Saida, Faculté des Sciences, Département de physique, En-nasr BP138, Saida 20000 (Algeria); Hou, M. [Université Libre de Bruxelles, Faculté des Sciences, CP 223, Bd du Triomphe, B-1050 Bruxelles (Belgium); Becquart, C.S. [Unité Matériaux et Transformations (UMET), UMR 8207 Université Lille-1, F-59655 Villeneuve d’Ascq Cédex (France); Domain, C. [EDF-R& D Département MMC, Les renardières, F-77818 Moret sur Loing Cédex (France); De Backer, A. [CCFE, Culham Centre for Fusion Energy, Abingdon (United Kingdom)

    2015-06-01

    We have used an Object Kinetic Monte Carlo (OKMC) model to simulate the long term evolution of the primary damage in Fe{sub 70}Cr{sub 20}Ni{sub 10} alloys. The mean number of Frenkel pairs created by different Primary Knocked on Atoms (PKA) was estimated by Molecular Dynamics using a ternary EAM potential developed in the framework of the PERFORM-60 European project. This number was then used to obtain the vacancy–interstitial recombination distance required in the calculation of displacement cascades in the Binary Collision Approximation (BCA) with code MARLOWE (Robinson, 1989). The BCA cascades have been generated in the 10–100 keV range with the MARLOWE code and two different screened Coulomb potentials, namely, the Molière approximation to the Thomas–Fermi potential and the so-called “Universal” potential by Ziegler, Biersack and Littmark (ZBL). These cascades have been used as input to the OKMC code LAKIMOCA (Domain et al., 2004), with a set of parameters for describing the mobility of point defect clusters based on ab initio calculations and experimental data. The cluster size distributions have been estimated for irradiation doses of 0.1 and 1 dpa, and a dose rate of 10{sup −7} dpa/s at 600 K. We demonstrate that, like in the case of BCC iron, cluster size distributions in the long term are independent of the cascade energy and that the recursive cascade model suggested for BCC iron in Souidi et al. (2011) also applies to FCC Fe{sub 70}Cr{sub 20}Ni{sub 10.} The results also show that the influence of the BCA potential is sizeable but the qualitative correspondence in the predicted long term evolution is excellent.

  12. Magnetoimpedance studies on laser and microwave annealed Fe{sub 66}Ni{sub 7}si{sub 7}B{sub 20} ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Kotagiri, Ganesh [Advanced Magnetic Materials Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Ramarao, S.D. [Microwave Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Markandeyulu, G., E-mail: mark@iitm.ac.in [Advanced Magnetic Materials Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

    2015-05-15

    Magnetoimpedance (MI) has been investigated in the laser and microwave annealed Fe{sub 66}Ni{sub 7}Si{sub 7}B{sub 20} ribbons. The largest MI [(MI){sub m}] values of the ribbons annealed using laser with energies of 150, 200 and 250 mJ/pulse (mJp) are 25% (at 7 MHz), 30% (at 5 MHz) and 21% (at 7 MHz) respectively. The effect of domain wall pinning on MI was observed as field insensitive regions in the MI profiles in the ribbon annealed using 150 mJp energy. Flower shaped grains in amorphous matrix in the ribbon annealed with 200 mJp energy are responsible for highest (MI){sub m} due to the least anisotropy. In the ribbons annealed for 40, 45 and 50 min at 400 °C using microwaves, (MI){sub m} values are 35% (at 5 MHz), 46% (at 6 MHz) and 29% (at 7 MHz) respectively. The large DC conductivity and the least anisotropy (smallest H{sub k} values) in the ribbon microwave annealed for 45 min at 400 °C resulted in (MI){sub m} reaching its highest value in the ribbons investigated. - Highlights: • Magnetoimpedance studied on Fe{sub 66}Ni{sub 7}Si{sub 7}B{sub 20} ribbons annealed using laser/microwaves. • Domain wall pinning observed in the ribbon annealed with 150 mJ/pulse of laser. • Flower shaped grains observed in the ribbon annealed with 200 mJ/pulse of laser. • Large magnetoimpedance and least anisotropy observed in the above ribbon. • Microwave annealed ribbons exhibited conductivity-magnetoimpedance correlation.

  13. Phase diagram and magnetocaloric effects in Ni{sub 1-x}Cr{sub x}MnGe{sub 1.05}

    Energy Technology Data Exchange (ETDEWEB)

    Aryal, Anil, E-mail: aryalanil@siu.edu; Quetz, Abdiel; Pandey, Sudip; Eubank, Michael; Dubenko, Igor; Ali, Naushad [Department of Physics, Southern Illinois University, Carbondale, Illinois 62901 (United States); Samanta, Tapas; Stadler, Shane [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)

    2015-05-07

    The structural and magnetic properties of the Ni{sub 1−x}Cr{sub x}MnGe{sub 1.05} system (for x = 0, 0.035, 0.070, 0.105) have been studied by x-ray diffraction (XRD), differential scanning calorimetry (DSC), and magnetization measurements. A change in crystal structure from orthorhombic to hexagonal was observed in the XRD data at chromium concentrations of x = 0.035, 0.070, and 0.105. The values of the cell parameters and volume of the unit cell for orthorhombic and hexagonal phase were determined. It was found that the partial substitution of Cr for Ni in Ni{sub 1−x}Cr{sub x}MnGe{sub 1.05} results in a first order magnetostructural transition from antiferromagnetic to ferromagnetic (FM) at T{sub M} = 132 K for x = 0.105. A FM to paramagnetic second order transition has been observed at T{sub C} = 204 K. A magnetic entropy change of |ΔS{sub M}| = 4.5 J/kg K for ΔH = 5 T was observed in the vicinity of T{sub C} and T{sub M} for x = 0.105. The values of the latent heat (L = 2.2 J/g) and corresponding total entropy changes (ΔS{sub T} = 16 J/kg K) have been determined from DSC measurements. A concentration-dependent phase diagram of transition temperatures has been constructed using the magnetic and DSC data.

  14. Synthesis and functional properties of the Ni{sub 1-x}Mn{sub x}Fe{sub 2}O{sub 4} ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Airimioaei, M. [Faculty of Chemistry, Al. I. Cuza University, Iasi 700506 (Romania); Ciomaga, C.E., E-mail: cristina.ciomaga@uaic.ro [Faculty of Physics, Al. I. Cuza University, Iasi 700506 (Romania); Apostolescu, N. [Faculty of Chemical Engineering and Environmental Protection, Gheorghe Asachi Technical University of Iasi, 700050 (Romania); Leontie, L. [Faculty of Physics, Al. I. Cuza University, Iasi 700506 (Romania); Iordan, A.R. [Faculty of Chemistry, Al. I. Cuza University, Iasi 700506 (Romania); Mitoseriu, L., E-mail: lmtsr@uaic.ro [Faculty of Physics, Al. I. Cuza University, Iasi 700506 (Romania); Palamaru, M.N. [Faculty of Chemistry, Al. I. Cuza University, Iasi 700506 (Romania)

    2011-08-04

    Highlights: > The Ni{sub 1-x}Mn{sub x}Fe{sub 2}O{sub 4} ferrite ceramics were obtained by gel-combustion method. > By Mn addition a decreasing of crystallite size was obtained. > The magnetic and dielectric properties revealed relatively high values of permeability and low values of dielectric permittivity in the range kHz-MHz, which made the ferrite as promising materials for microelectronic applications. - Abstract: Nanocrystalline Ni{sub 1-x}Mn{sub x}Fe{sub 2}O{sub 4} (x = 0; 0.17; 0.34; 0.5) ferrite powders were successfully synthesized using the sol-gel combustion method, by using nitrates as cations source and citric acid (C{sub 6}H{sub 8}O{sub 7}) as combustion/chelating agent. The reaction advancement was observed by means of IR absorption spectroscopy, by monitoring two characteristic bands for the spinel compounds at about 600 cm{sup -1} and 400 cm{sup -1}, respectively. The as-synthesized powders were characterized by IR spectroscopy, X-ray diffraction (XRD) and scanning electronic microscopy (SEM). The magnetic study shows that the saturation magnetization decreases with increasing the Mn addition, as result of the particle size reduction. The dielectric properties were measured as a function of frequency in the range of 10 Hz to 1 MHz. The real part of permittivity has values of {approx}88 at 1 kHz and {approx}7 at 1 Hz for x = 0. An increasing dielectric permittivity with increasing the amount of Mn is observed. For all the investigated compositions, both the real and imaginary parts of permittivity decrease with frequency.

  15. Large exchange bias in polycrystalline ribbons of Ni{sub 56}Mn{sub 21}Al{sub 22}Si{sub 1}

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Rohit; Ingale, Babita [Magnetics and Advanced Ceramics Laboratory, Physics Department, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Varga, Lajos K. [Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, P.O.B. 49, H-1525 Budapest (Hungary); Khovaylo, Vladimir V. [National University of Science and Technology MISiS, Moscow 119049 (Russian Federation); ITMO University, St. Petersburg 197101 (Russian Federation); Taskaev, S. [National University of Science and Technology MISiS, Moscow 119049 (Russian Federation); Chatterjee, Ratnamala, E-mail: ratnamalac@gmail.com [Magnetics and Advanced Ceramics Laboratory, Physics Department, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India)

    2015-11-15

    Large exchange bias (EB) effect is demonstrated in a Ni{sub 56}Mn{sub 21}Al{sub 22}Si{sub 1} polycrystalline ribbon that shows spin-glass behaviour below 68 K and superparamagnetic (SPM) behaviour above this temperature. The average magnetic moment μ of the SPM clusters is estimated to be considerably smaller than that reported for other Heusler alloy systems that demonstrate spin glass behaviour and EB effect. The M–H loops measured in field-cooled (FC) conditions show significant asymmetry that is observed to be strongly field and temperature dependant. The maximum EB field (H{sub EB} ~2.6 kOe at 20 kOe and 2 K) is much larger than that reported for any metallic alloy system with conventional EB effect. The dependence of H{sub EB} on temperature shows an exponential decrease. An approach towards enhancement of the EB effect in this conventional EB system can be realized via manipulation of SPM or superferromagnetic (SFM) cluster size with variation of cooling magnetic field. - Highlights: • Ni{sub 56}Mn{sub 21}Al{sub 22}Si{sub 1} shows an orthorhombic 14M structure at room temperature. • Spin glass behavior is observed below 68 K and superparamagnetic (SPM) above 60 K. • Martensitic transformation temperatures are observed above 300 K. • Large exchange bias (H{sub EB}) ~2.6 kOe is observed for cooling field (H{sub CF}) of 20 kOe. • Large H{sub EB} is a consequence of a strong dependence of the SPM cluster size on H{sub CF}.

  16. Identifying hazards associated with lava deltas

    Science.gov (United States)

    Poland, Michael P.; Orr, Tim R.

    2014-01-01

    Lava deltas, formed where lava enters the ocean and builds a shelf of new land extending from the coastline, represent a significant local hazard, especially on populated ocean island volcanoes. Such structures are unstable and prone to collapse—events that are often accompanied by small explosions that can deposit boulders and cobbles hundreds of meters inland. Explosions that coincide with collapses of the East Lae ‘Apuki lava delta at Kīlauea Volcano, Hawai‘i, during 2005–2007 followed an evolutionary progression mirroring that of the delta itself. A collapse that occurred when the lava–ocean entry was active was associated with a blast of lithic blocks and dispersal of spatter and fine, glassy tephra. Shortly after delta growth ceased, a collapse exposed hot rock to cold ocean water, resulting in an explosion composed entirely of lithic blocks and lapilli. Further collapse of the delta after several months of inactivity, by which time it had cooled significantly, resulted in no recognizable explosion deposit. Seaward displacement and subsidence of the coastline immediately inland of the delta was measured by both satellite and ground-based sensors and occurred at rates of several centimeters per month even after the lava–ocean entry had ceased. The anomalous deformation ended only after complete collapse of the delta. Monitoring of ground deformation may therefore provide an indication of the potential for delta collapse, while the hazard associated with collapse can be inferred from the level of activity, or the time since the last activity, on the delta.

  17. Al{sub 15}Ge{sub 4}Ni{sub 3}: A new intergrowth structure with Cu{sub 3}Au- and CaF{sub 2}-type building blocks

    Energy Technology Data Exchange (ETDEWEB)

    Reichmann, Thomas L.; Jandl, Isabella [Department of Inorganic Chemistry (Materials Chemistry), University of Vienna, Währinger Straße 42, 1090 Wien (Austria); Effenberger, Herta S. [Department of Mineralogy and Crystallography, University of Vienna, Althanstraße 14, 1090 Wien (Austria); Herzig, Peter [Department of Physical Chemistry, University of Vienna, Währinger Straße 42, 1090 Wien (Austria); Richter, Klaus W., E-mail: klaus.richter@univie.ac.at [Department of Inorganic Chemistry (Materials Chemistry), University of Vienna, Währinger Straße 42, 1090 Wien (Austria)

    2015-05-15

    The new ternary compound Al{sub 15}Ge{sub 4}Ni{sub 3} (τ{sub 2} in the system Al–Ge–Ni) was synthesized in single crystalline form by a special annealing procedure from samples located in the three phase fields [L+Al+τ{sub 2}] and [L+Ge+τ{sub 2}]. The crystal structure of Al{sub 15}Ge{sub 4}Ni{sub 3} was determined by single-crystal X-ray diffraction. The compound crystallizes in a new structure type in space group I4-bar3m, Pearson Symbol cI88, cubic lattice parameter a=11.405(1) Å. Phase diagram investigations indicate stoichiometric composition without considerable homogeneity range; τ{sub 2} melts peritectically at T=444 °C. The crystal structure of Al{sub 15}Ge{sub 4}Ni{sub 3} shows a unique combination of simple Cu{sub 3}Au- and CaF{sub 2}-type building blocks: a three dimensional network of CaF{sub 2}-type units, formed by Ni and Al atoms, is interspaced by clusters (Al{sub 6}Ge{sub 8}) resembling unit cells of the Cu{sub 3}Au-type. Both structural motifs are connected by Al–Ge bonds. The ground state energy of the compound was obtained by DFT calculations and the densities of states were analyzed in detail. In addition, electron density maps were calculated in four different sections through the unit cell using the full potential linearized augmented plane-wave (FLAPW) method. The bonding situation in Al{sub 15}Ge{sub 4}Ni{sub 3} was discussed combining results from electronic calculations with the analysis of the coordination of atoms. - Graphical abstract: The new compound Al{sub 15}Ge{sub 4}Ni{sub 3} shows a unique combination of simple Cu{sub 3}Au- and CaF{sub 2}-type building blocks. - Highlights: • The crystal structure of Al{sub 15}Ge{sub 4}Ni{sub 3} (space group I4-bar3m) was determined. • It shows a unique combination of CaF{sub 2}- and Cu{sub 3}Au-type building blocks. • Electronic (DFT) calculations were performed to gain insight to chemical bonding.

  18. Delta Electroproduction in 12-C

    Energy Technology Data Exchange (ETDEWEB)

    McLauchlan, Steven [Univ. of Glasgow, Scotland (United Kingdom)

    2003-01-01

    The Δ-nucleus potential is a crucial element in the understanding of the nuclear system. Previous electroexcitation measurements in the delta region reported a Q2 dependence of the Δ mass indicating that this potential is dependent on the momentum of the Δ. Such a dependence is not observed for protons and neutrons in the nuclear medium. This thesis presents the experimental study of the electroexcitation of the Δ resonance in 12C, performed using the high energy electron beam at the Thomas Jefferson National Accelerator Facility, and the near 4π acceptance detector CLAS that enables the detection of the full reaction final state. Inclusive, semi inclusive, and exclusive cross sections were measured with an incident electron beam energy of 1.162GeV over the Q2 range 0.175-0.475 (GeV/c)2. A Q2 dependence of the Δ mass was only observed in the exclusive measurements indicating that the Δ-nucleus potential is affected by the momentum of the Δ.

  19. Novel diazabicycloalkane delta opioid agonists.

    Science.gov (United States)

    Loriga, Giovanni; Lazzari, Paolo; Manca, Ilaria; Ruiu, Stefania; Falzoi, Matteo; Murineddu, Gabriele; Bottazzi, Mirko Emilio Heiner; Pinna, Giovanni; Pinna, Gérard Aimè

    2015-09-01

    Here we report the investigation of diazabicycloalkane cores as potential new scaffolds for the development of novel analogues of the previously reported diazatricyclodecane selective delta (δ) opioid agonists, as conformationally constrained homologues of the reference δ agonist (+)-4-[(αR)-α((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethylbenzamide (SNC80). In particular, we have simplified the diazatricyclodecane motif of δ opioid agonist prototype 1a with bridged bicyclic cores. 3,6-diazabicyclo[3.1.1]heptane, 3,8-diazabicyclo[3.2.1]octane, 3,9-diazabicyclo[3.3.1]nonane, 3,9-diazabicyclo[4.2.1]nonane, and 3,10-diazabicyclo[4.3.1]decane were adopted as core motifs of the novel derivatives. The compounds were synthesized and biologically assayed as racemic (3-5) or diastereoisomeric (6,7) mixtures. All the novel compounds 3-7 showed δ agonism behaviour and remarkable affinity to δ receptors. Amongst the novel derivatives, 3,8-diazabicyclo[3.2.1]octane based compound 4 evidenced improved δ affinity and selectivity relative to SNC80. Published by Elsevier Ltd.

  20. Damped Oscillator with Delta-Kicked Frequency

    Science.gov (United States)

    Manko, O. V.

    1996-01-01

    Exact solutions of the Schrodinger equation for quantum damped oscillator subject to frequency delta-kick describing squeezed states are obtained. The cases of strong, intermediate, and weak damping are investigated.

  1. Delta-nucleus dynamics: proceedings of symposium

    Energy Technology Data Exchange (ETDEWEB)

    Lee, T.S.H.; Geesaman, D.F.; Schiffer, J.P. (eds.)

    1983-10-01

    The appreciation of the role in nuclear physics of the first excited state of the nucleon, the delta ..delta..(1232), has grown rapidly in the past decade. The delta resonance dominates nuclear reactions induced by intermediate energy pions, nucleons, and electromagnetic probes. It is also the most important non-nucleonic degree of freedom needed to resolve many fundamental problems encountered in the study of low-energy nuclear phenomena. Clearly, a new phase of nuclear physics has emerged and conventional thinking must be extended to account for this new dimension of nuclear dynamics. The most challenging problem we are facing is how a unified theory can be developed to describe ..delta..-nucleus dynamics at all energies. In exploring this new direction, it is important to have direct discussions among researchers with different viewpoints. Separate entries were prepared for the 49 papers presented. (WHK)

  2. in the Niger Delta of Nigeria

    African Journals Online (AJOL)

    suggestions as policy options for the resolution of the armed conflict in the. Niger Delta ... indiscriminate use of lethal weapons by local militias, the cumulative effect of which is the ... of many 'child' soldiers in local conflicts or wars nowadays.

  3. Contemporary depositional environments of the Omo delta.

    Science.gov (United States)

    Butzer, K W

    1970-05-02

    Geomorphological and sedimentological studies of depositional environments of the modern Omo River delta and floodplain are essential to an understanding of the Pliocene to Pleistocene Mursi, Nkalabong and Kibish Formations of the Lower Omo Basin (southwestern Ethiopia).

  4. Legal Delta Boundary, 2001, DWR [ds586

    Data.gov (United States)

    California Department of Resources — The original topographic maps containing the drawn delta border were scanned from the Department of Water Resources. Images were registered to 1:24,000 USGS DRG's in...

  5. Cackling Canada goose nesting populations, Yukon Delta

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Number of potential territories, number of cackling Canada Goose nests, and percent occupancy of available territories from CCG plots on the Yukon Delta National...

  6. Water quality in the Okavango Delta

    African Journals Online (AJOL)

    2010-03-12

    Mar 12, 2010 ... water and sediments in the Okavango Delta published between 2000 and 2010. Despite the shortage ... Their interactions with light, water, dissolved nutrients and suspended solids ...... temporal remote sensing. Int. J. Remote ...

  7. California Black Rail - Central Delta [ds17

    Data.gov (United States)

    California Department of Resources — Results of taped-call black rail surveys of in-stream habitat within certain waterways in the central Sacramento / San Joaquin Delta during 1992 and 1993. TIME...

  8. Propagator for the double delta potential

    Energy Technology Data Exchange (ETDEWEB)

    Cacciari, Ilaria [Istituto di Fisica Applicata ' Nello Carrara' , CNR, via Madonna del Piano 10, 50019 Sesto Fiorentino, Florence (Italy); Moretti, Paolo [Istituto dei Sistemi Complessi, CNR, Sezione di Firenze, via Madonna del Piano 10, 50019 Sesto Fiorentino, Florence (Italy)]. E-mail: paolo.moretti@isc.cnr.it

    2006-12-04

    The propagator for the double delta potential is calculated starting from the integral form of the Schroedinger equation. A compact expression of its Laplace transform is found, that can be explicitly inverted in some limiting cases.

  9. The Atchafalaya River Delta. Report 4. Generic Analysis of Delta Development.

    Science.gov (United States)

    1984-01-01

    contemporaneously with delta growth (Donaldson, Martin , and Kanes 1970). The average rate of contour advancement has been ap- proximately 12 m/yr. Assuming the...Donaldson, Martin , ’, and Kanes 1970) shows that the delta has transgressed over 60 m. Average rates of deterioration are reported to be 2.75 m/yr...after 1965 ( Keown , Dardeau, and Causey 1980). Coarse sediment not reaching the delta is precisely the material needed for subaerial land. Third, the

  10. Optimized $\\delta$ expansion for relativistic nuclear models

    CERN Document Server

    Krein, G I; Peres-Menezes, D; Nielsen, M; Pinto, M B

    1998-01-01

    The optimized $\\delta$-expansion is a nonperturbative approach for field theoretic models which combines the techniques of perturbation theory and the variational principle. This technique is discussed in the $\\lambda \\phi^4$ model and then implemented in the Walecka model for the equation of state of nuclear matter. The results obtained with the $\\delta$ expansion are compared with those obtained with the traditional mean field, relativistic Hartree and Hartree-Fock approximations.

  11. Migration in Vulnerable Deltas: A Research Strategy

    Science.gov (United States)

    Hutton, C.; Nicholls, R. J.; Allan, A.

    2015-12-01

    C. Hutton1, & R. J. Nicholls1, , 1 University of Southampton, University Road, Southampton, Hampshire, United Kingdom, SO17 1BJ. cwh@geodata. soton.ac.ukAbstractGlobally, deltas contain 500 million people and with rising sea levels often linked to large number of forced migrants are expected in the coming century. However, migration is already a major process in deltas, such as the growth of major cities such as Dhaka and Kolkata. Climate and environmental change interacts with a range of catchment and delta level drivers, which encompass a nexus of sea-level rise, storms, freshwater and sediment supply from the catchment, land degradation, subsidence, agricultural loss and socio-economic stresses. DECCMA (Deltas, Vulnerability and Climate Change: Migration and Adaptation/CARRIA) is investigating migration in the Ganges-Brahmaputra-Meghna (GBM), Mahanadi and Volta Deltas, including the influence of climate change. The research will explore migration from a range of perspectives including governance and stakeholder analysis, demographic analysis, household surveys of sending and receiving areas, macro-economic analysis, and hazards and hotspot analysis both historically and into the future. Migration under climate change will depend on other adaptation in the deltas and this will be examined. Collectively, integrated analysis will be developed to examine migration, other adaptation and development pathways with a particular focus on the implications for the poorest. This will require the development of input scenarios, including expert-derived exogenous scenarios (e.g., climate change) and endogenous scenarios of the delta developed in a participatory manner. This applied research will facilitate decision support methods for the development of deltas under climate change, with a focus on migration and other adaptation strategies.

  12. Stellar delta matter with delta-meson coupling constants constrained by QCD sum rule

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Antonio Ferreira da [Secretaria de Educacao, Cultura e Desportos do Estado de Roraima (SECD/RR), Boa Vista, RR (Brazil); Oliveira, Jose Carlos Teixeira de [Universidade Federal de Roraima (UFRR), Boa Vista, RR (Brazil); Rodrigues, Hilario [Centro Federal de Educacao Tecnologica (CEFET-RJ), Rio de Janeiro, RJ (Brazil); Duarte, Sergio Barbosa [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Chiapparini, Marcelo [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil)

    2010-07-01

    The considerable presence of delta-resonances (30% of baryonic population) in the dense phase of relativistic heavy ion collisions leads to a great interest in the study of the delta matter formation in the deep interior of compact stars. In the present work we determine the equation of state and the population of baryons and leptons and discuss the effects of the baryon-meson coupling constants to the formation of delta matter in the stellar medium. We use the non-linear Walecka model consisting of the octet of baryons of spin 1=2 (n, p, {Lambda}{sup 0}, {Sigma}{sup -}, {Sigma}{sup 0}, {Sigma}{sup +}, {Xi}{sup -}, {Xi}{sup 0}) and baryonic resonances of spin 3=2, represented by the delta resonances ({Delta}{sup -}, ({Delta}{sup 0}, ({Delta}{sup +}, ({Delta}{sup ++}) and {Omega}{sup -}, in the baryonic sector. In the leptonic sector we consider the electrons and muons. The coupling constants between the hyperons {Lambda}, {Sigma}, and {Xi} and the mesons {omega} and {rho} are fixed by using SU(6) symmetry, while the hyperons-{sigma} coupling constants are constrained by the consistence of the hypernuclear potential in the nuclear matter with hypernuclear data. In addition, we use the finite density QCD sum rule to determine the possible values of delta-meson coupling constants. (author)

  13. delta(13)C and delta(2)H isotope ratios in amphetamine synthesized from benzaldehyde and nitroethane.

    Science.gov (United States)

    Collins, Michael; Salouros, Helen; Cawley, Adam T; Robertson, James; Heagney, Aaron C; Arenas-Queralt, Andrea

    2010-06-15

    Previous work in these laboratories and by Butzenlechner et al. and Culp et al. has demonstrated that the delta(2)H isotope value of industrial benzaldehyde produced by the catalytic oxidation of toluene is profoundly positive, usually in the range +300 per thousand to +500 per thousand. Synthetic routes leading to amphetamine, methylamphetamine or their precursors and commencing with such benzaldehyde may be expected to exhibit unusually positive delta(2)H values. Results are presented for delta(13)C and delta(2)H isotope values of 1-phenyl-2-nitropropene synthesized from an industrial source of benzaldehyde, having a positive delta(2)H isotope value, by a Knoevenagel condensation with nitroethane. Results are also presented for delta(13)C and delta(2)H isotope values for amphetamine prepared from the resulting 1-phenyl-2-nitropropene. The values obtained were compared with delta(13)C and delta(2)H isotope values obtained for an amphetamine sample prepared using a synthetic route that did not involve benzaldehyde. Finally, results are presented for samples of benzaldehyde, 1-phenyl-2-nitropropene and amphetamine that had been seized at a clandestine amphetamine laboratory.

  14. Controlled synthesis and microwave absorption properties of Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}/PANI composite via an in-situ polymerization process

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Min [Department of Applied Chemistry, College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211100 (China); Ji, Guangbin, E-mail: gbji@nuaa.edu.cn [Department of Applied Chemistry, College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211100 (China); Zhang, Baoshan, E-mail: bszhang@nju.edu.cn [School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Tang, Dongming; Yang, Yi [School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Du, Youwei [Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-03-01

    The binary composites of conducting polyaniline (PANI) and nickle zinc ferrite were synthesized by an in-situ polymerization process, and the electromagnetic absorption properties of the composites were also investigated. The FT-IR spectra present the peaks of PANI (1562, 1481, 1301, 1109, and 799 cm{sup −1}) and the bonds of NiZn ferrite (579 and 390 cm{sup −1}), indicating the existence of both NiZn ferrite particles and PANI in the composites. With the increasing ratio of nickle zinc ferrite, the composites distributes in irregular compared with pure PANI and Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}. The TG curves of the pure PANI and PANI/Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4} composites with different molar ratios clearly show the increase percentage of the ferrite in the composites. Furthermore, we found that the excellent electromagnetic absorption properties and wide absorption bandwidth can be achieved by adjusting proper molar ratios Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4} to PANI. The maximum reflection loss of Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}/PANI can reach to −41 dB at 12.8 GHz and the bandwidth exceeding −10 dB can reach to 5 GHz with the absorber thickness of 2.6 mm at the molar ratio of 1:2. This can be attributed to the enhancing magnetic loss and the better impedance matching. Therefore, Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}/PANI ferrite composites can become a new kind of candidate in the field of the microwave absorbing. - Highlights: • Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}/PANI possesses the enhanced dielectric properties when compared with pure Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}. • The absorbing bandwidth of Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}/PANI is wider than pure Ni{sub 0.6}Zn{sub 0.4}Fe{sub 2}O{sub 4}. • The maximum R{sub L} can reach −41 dB at 12.8 GHz and the bandwidth exceeding −10 dB was 5 GHz with the absorber thickness of 2.6 mm.

  15. Modification of surface hardness for dual two-phase Ni{sub 3}Al–Ni{sub 3}V intermetallic compound by using energetic ion beam and subsequent thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Yoshizaki, H., E-mail: su110040@edu.osakafu-u.ac.jp [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Hashimoto, A.; Kaneno, Y. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Semboshi, S. [Kansai-Center, Institute for Materials Research, Tohoku University, Sakai, Osaka 599-8531 (Japan); Saitoh, Y. [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan); Okamoto, Y. [Quantum Beam Science Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Iwase, A. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan)

    2015-02-15

    Dual two-phase Ni{sub 3}Al–Ni{sub 3}V intermetallic compound with the ordered structure was irradiated with 16 MeV Au{sup 5+} ions at room temperature. The observation by a transmission electron microscope has revealed that the lattice structure of this intermetallic compound changes from the ordered structure to the disordered A1 (fcc) structure by the ion irradiation, which accompanies a remarkable decrease in the surface hardness. The annealing treatment at elevated temperatures for the irradiated specimen induces the recovery of surface hardness. The present experimental result shows that the combination of energetic ion irradiation and the thermal treatment could be a means of modification for the workability of dual two-phase Ni{sub 3}Al–Ni{sub 3}V intermetallic compound.

  16. Improved polycrystalline Ni{sub 54}Mn{sub 16}Fe{sub 9}Ga{sub 21} high-temperature shape memory alloy by γ phase distributing along grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shuiyuan; Zhang, Fan; Zhang, Kaixin; Huang, Yangyang; Wang, Cuiping; Liu, Xingjun [Xiamen Univ. (China). Fujian Key Laboratory of Materials Genome

    2016-09-15

    In this study, the shape recovery and mechanical properties of Ni{sub 54}Mn{sub 16}Fe{sub 9}Ga{sub 21} high-temperature shape memory alloy are improved simultaneously. This results from the low, about 4.4%, volume fraction of γ phase being almost completely distributed along grain boundaries. The recovery strain gradually increases with the increase in residual strain with a shape recovery rate of above 68%, up to a maximum value of 5.3%. The compressive fracture strain of Ni{sub 54}Mn{sub 16}Fe{sub 9}Ga{sub 21} alloy is about 35%. The results further reveal that when applying a high compression deformation two types of cracks form and propagate either within martensite grains (type I) or along the boundaries between martensite phase and γ phase (type II) in the present two-phase alloy.

  17. Ferroelectric, piezoelectric, pyroelectric studies on BaTi{sub 0.95}(Ni{sub 1/3}Nb{sub 2/3}){sub 0.05}O{sub 3} ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Boujelben, F; Bouzid, H; Bahri, F; Maalej, A; Khemakhem, H; Simon, A; Maglione, M, E-mail: faizaboujelben@yahoo.fr

    2010-11-15

    The main objective of this paper is to study dielectric, ferroelectric, pyroelectric and piezoelectric proprieties of BaTi{sub 0.95}(Ni{sub 1/3}Nb{sub 2/3}){sub 0.05}O{sub 3}. From dielectric experiments, a single ferroelectric transition temperature of about 300K was found. The ferroelectric hysteresis loops were recorded versus temperature evidencing a saturation polarisation of about 4{mu}C/cm{sup 2} and a coercive field of 0.97kV/cm at the lowest temperature. The most promising result for BaTi{sub 0.95}(Ni{sub 1/3}Nb{sub 2/3}){sub 0.05}O{sub 3} is its effective piezoelectric coefficient d{sub 31}which reaches 55pCN{sup -1} at room temperature.

  18. In situ studies of temperature-dependent behaviour and crystallisation of Ni{sub 36.5}Pd{sub 36.5}P{sub 27} metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Kaban, I., E-mail: i.kaban@ifw-dresden.de [IFW Dresden, Institute for Complex Materials, P.O. Box 270116, 01171 Dresden (Germany); TU Dresden, Institute of Materials Science, 01062 Dresden (Germany); Khalouk, K.; Gasser, F.; Gasser, J.-G. [Université de Lorraine, Institut de Chimie, Physique et Matériaux, Laboratoire de Chimie et Physique Approches Multiéchelles des Milieux Complexes LCP-A2MC, 1 boulevard Arago, 57078 cedex 3 Metz (France); Bednarčik, J. [DESY Photon Science, Notkestraße 85, 22607 Hamburg (Germany); Shuleshova, O.; Okulov, I.; Gemming, T.; Mattern, N. [IFW Dresden, Institute for Complex Materials, P.O. Box 270116, 01171 Dresden (Germany); Eckert, J. [IFW Dresden, Institute for Complex Materials, P.O. Box 270116, 01171 Dresden (Germany); TU Dresden, Institute of Materials Science, 01062 Dresden (Germany)

    2014-12-05

    Highlights: • Electronic transport properties and structure of Ni{sub 36.5}Pd{sub 36.5}P{sub 27} glass were studied. • Resistivity and thermopower are discussed in the frame of the extended Ziman theory. • Structural changes in MGs can be controlled by in situ measurement of resistivity. - Abstract: The temperature dependences of electrical resistivity, absolute thermoelectric power as well as structural changes in Ni{sub 36.5}Pd{sub 36.5}P{sub 27} metallic glass have been measured and analyzed. A very good agreement between the phase transition temperatures determined using different techniques has been established. In situ measurement of electrical resistivity is suggested as a method to control the phase formation and microstructure upon heat treatment of metallic glasses.

  19. Combined phase-field and MD simulations of diffusion drop and ordering at [Ni{sub x}Zr{sub 1-x}]{sub liquid}-Zr{sub crystal} interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Guerdane, M.; Wendler, F.; Nestler, B. [Institute of Materials and Processes, Karlsruhe University of Applied Sciences (Germany)

    2010-07-01

    We combine phase-field (PF) modeling and molecular dynamics (MD) simulations to show that the velocity of the solidification front in a two-phase [Ni{sub x}Zr{sub 1-x}]{sub liquid}-Zr{sub crystal} structure is strongly affected by the drop of the liquid diffusion when approaching the solid-liquid interface. The latter is defined through a suitable order parameter that distinguishes between crystalline and liquid atomic environment. The diffusion drop near the interface is attributed to the pronounced short range order inherent to the Ni{sub x}Zr{sub 1-x} melt. The system transforms into a massive lateral ordering in the vicinity of the Zr crystalline wall. Our combined PF-MD analysis points out the shortcoming of the standard interpolation procedure, usually applied in constructing the phase dependent diffusivity, to describe the confinement effect caused by the crystalline wall at low temperatures.

  20. Substitutional effect on structural and dielectric properties of Ni{sub 1−x}A{sub x}Fe{sub 2}O{sub 4} (A = Mg, Zn) mixed spinel ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Varshney, Dinesh, E-mail: vdinesh33@rediffmail.com; Verma, Kavita

    2013-06-15

    The Ni{sub 1−x}A{sub x}Fe{sub 2}O{sub 4} (A = Zn, Mg; x = 0.0, 0.5) ferrites synthesized by chemical co-precipitation method. X-ray diffraction and Raman spectroscopy reveals that all the ferrite samples are in single-phase cubic spinel structure with Fd3m space group. The lattice parameter enhances with Mg and Zn substitution. Raman spectroscopy identifies a doublet like nature of A{sub 1g} mode for all the three ferrites. A blue shift in Mg doped ferrite and a red shift in Zn doped ferrite has been observed as compared to parent NiFe{sub 2}O{sub 4}. Frequency dependent dielectric response confirms the dielectric polarization and electrical conduction mechanism. The minimum value of loss tangent (∼0.03) at 5 KHz suggests that Ni{sub 1−x}A{sub x}Fe{sub 2}O{sub 4} is effective material for microwave application. The activation energy for NiFe{sub 2}O{sub 4}, Ni{sub 0.5}Mg{sub 0.5}Fe{sub 2}O{sub 4} and Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} are found to be 0.28 eV, 0.29 eV and 0.31 eV, respectively. - Highlights: • Doping of Mg{sup 2+} and Zn{sup 2+}effect the structural and dielectric properties. • Cell parameter increases with Mg and Zn doping. • Raman spectra reveal a doublet like feature for A{sub 1g} mode in all the samples. • Minimum loss (∼0.03) makes present system useful in microwave applications. • Impedance spectra revels the insulating behavior of all the samples.

  1. Controlled synthesis and magnetic properties of monodisperse Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}/MWCNT nanocomposites via microwave-assisted polyol process

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Huaqiang, E-mail: wuhuaq@mail.ahnu.edu.cn [College of Chemistry and Materials Science, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, Wuhu 241000 (China); Zhang, Ning; Mao, Li; Li, Tingting; Xia, Lingling [College of Chemistry and Materials Science, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, Wuhu 241000 (China)

    2013-03-25

    Highlights: ► Microwave-assisted polyol preparation of monodisperse Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}/MWCNT nanocomposites. ► The composition can be controlled through adjusting the atomic ratios of nickel and zinc salts. ► Ms reaches maximum for x = 0.5. Hc is low and thus exhibits superparamagnetic. -- Abstract: Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}/MWCNT nanocomposites (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1) with controllable composition have been successfully synthesized via microwave-assisted polyol process using triethylene glycol solution (TREG) as solvent. Experimental results demonstrated that monodisperse face-centered cubical Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} nanoparticles with average size (6 nm) had been attached on the MWCNTs. The composition of ferrite nanoparticles can be controlled through adjusting the atomic ratios of the nickel and zinc salts in the mixed nitrate solution. The magnetic properties of nanocomposites with different Zn contents were measured by vibrating sample magnetometer (VSM). The saturation magnetization (Ms) of Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}/MWCNT nanocomposites gradually increases when the x is less than 0.5 while decreases when the x is larger than 0.5. Ms reached maximum value when the x is 0.5. The coercivity (Hc) of nanocomposites is low at room temperature, which exhibits characteristic of superparamagnetic.

  2. Far infrared near normal specular reflectivity of Ni{sub x}(SiO{sub 2}){sub 1-x} (x = 1.0, 0.84, 0.75, 0.61, 0.54, 0.28) granular films

    Energy Technology Data Exchange (ETDEWEB)

    Massa, Nestor E., E-mail: neemmassa@gmail.co [Laboratorio Nacional de Investigacion y Servicios en Espectroscopia Optica-CEQUINOR, Universidad Nacional de La Plata, C.C. 962, 1900 La Plata (Argentina); Denardin, Juliano C., E-mail: jdenardin@usach.c [Departamento de Fisica, Universidad de Santiago de Chile, Av. Ecuador 3493, Santiago (Chile); Socolovsky, Leandro M., E-mail: leandrosocolovsky@gmail.co [Instituto de Tecnologias y Ciencias de la Ingenieria, Universidad de Buenos Aires, Av. Paseo Colon 850, Buenos Aires (Argentina); Knobel, Marcelo, E-mail: knobel@ifi.unicamp.b [Instituto de Fisica, ' Gleb Wataghin' , Universidade Estadual de Campinas, 13083-970 Campinas, SP (Brazil); Cruz, Fernando P. de la, E-mail: fpdelacruz@yahoo.com.a [Laboratorio Nacional de Investigacion y Servicios en Espectroscopia Optica-CEQUINOR, Universidad Nacional de La Plata, C.C. 962, 1900 La Plata (Argentina); Zhang Xixiang, E-mail: phxxz@ust.h [Research and Development, King Abdullah University of Science and Technology (KAUST), Thuwal (Saudi Arabia)

    2010-04-16

    One of the current issues at the basis of the understanding of novel materials is the degree of the role played by spatial inhomogeneities due to subtle phase separations. To clarify this picture here we compare the plain glass network response of transition metal granular films with different metal fractions against what is known for conducting oxides. Films for Ni{sub x}(SiO{sub 2}){sub 1-x} (x = 1.0, 0.84, 0.75, 0.61, 0.54, 0.28) were studied by temperature dependent far infrared measurements. While for pure Ni the spectrum shows a flat high reflectivity, those for x {approx} 0.84 and {approx}0.75 have a Drude component, vibrational modes mostly carrier screened, and a long tail that extents toward near infrared. This is associated with hopping electron conductivity and strong electron-phonon interactions. The relative reduction of the number of carriers in Ni{sub 0.75}(SiO{sub 2}){sub 0.25} allows less screened phonon bands on the top of a continuum and a wide and overdamped oscillator at mid-infrared frequencies. Ni{sub 0.54}(SiO{sub 2}){sub 0.46} and Ni{sub 0.28}(SiO{sub 2}){sub 0.72} have well defined vibrational bands and a sharp threshold at {approx}1450 cm{sup -1}. It is most remarkable that a distinctive resonant peak at {approx}1250 cm{sup -1} found for p-polarized angle dependent specular reflectivity. It originates in an electron cloud traced to electrons that are not able to overcome the metal-dielectric interface that, beating against the positive background, generates the electric dipole. Overall, we conclude that the spectra are analogous to those regularly found in conducting oxides where with a suitable percolating network polarons are formed.

  3. Magnetocaloric properties and exchange bias effect in Al for Sn substituted Ni{sub 48}Mn{sub 39.5}Sn{sub 12.5} Heusler alloy ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Czaja, Paweł, E-mail: p.czaja@imim.pl [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Str., 30-059 Krakow (Poland); Maziarz, Wojciech [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Str., 30-059 Krakow (Poland); Przewoźnik, Janusz; Kapusta, Czesław [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Department of Solid State Physics, Al. Mickiewicza 30, 30-059 Krakow (Poland); Hawelek, Lukasz [Institute of Non Ferrous Metals, 5 Sowinskiego Str., Gliwice 44-100 (Poland); Chrobak, Artur [A. Chelkowski Institute of Physics, University of Silesia, 4 Uniwersytecka Str., Katowice 40-007 (Poland); Drzymała, Piotr [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Str., 30-059 Krakow (Poland); Fitta, Magdalena [The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 152 Radzikowskiego Str., 31-342 Krakow (Poland); Kolano-Burian, Aleksandra [Institute of Non Ferrous Metals, 5 Sowinskiego Str., Gliwice 44-100 (Poland)

    2014-05-01

    The influence of Al substitution for Sn on magnetocaloric properties and exchange bias behavior in Ni{sub 48}Mn{sub 39.5}Sn{sub 12.5−x}Al{sub x} (x=0, 1, 2, 3) melt spun ribbons have been investigated. All the studied ribbons undergo a martensitic and reverse transformation. At low temperature martensite region, below 100 K, the alloys exhibit exchange bias effect, which appears to enhance with the increase of Al concentration. The loop shift difference (ΔH{sub E}) of up to 7960 A m{sup −1} is recorded between the ribbon containing no Al and the ribbon with x=3. The presence of exchange bias behavior in these samples is attributed to the coexistence of antiferromagnetic and ferromagnetic exchange interactions. The magnetic entropy change and refrigerant capacity are evaluated for the ribbons studied around both the structural and magnetic transformations under the applied magnetic field induction of 2 T. The maximum entropy change around the magnetic transition and around the structural transition is reported for the Ni{sub 48}Mn{sub 39.5}Sn{sub 12.5} ribbon, and the entropy values amount to 1.8 and 7.8 J kg{sup −1} K{sup −1}, respectively. - Highlights: • Ni{sub 48}Mn{sub 39.5}Sn{sub 12.5−x}Al{sub x} (x=0, 1, 2, 3) melt spun ribbons are found to show exchange bias (EB) effect. • The Al for Sn substitution appears to enhance EB. • Around A{sub s} the magnetic field induces the RMT giving rise to the inverse MCE. • The highest ΔS{sub M} at H= 2 T is observed for the Ni{sub 48}Mn{sub 39.5}Sn{sub 12.5} ribbon.

  4. The Okavango: Whose Delta is it?

    Science.gov (United States)

    Magole, Lapologang; Magole, Lefatshe Innocent

    The Okavango Delta is amongst the largest Ramsar sites ( http://www.ramsar.org/sitelist.pdf) in the world and an important wetland for community livelihoods, conservation and tourism in Botswana. Over the years, the utilization of the delta has shifted from communal use to state control, with an increased use for conservation and tourism. This increased use for conservation and tourism has manifested in the physical expansion of the conservation area - Moremi Game Reserve and the formation of Wildlife Management Areas (WMAs) around the reserve, whose primary land use is wildlife utilization. The expansion of the conservation area has translated into several practical matters, including expansion of the area for non-hunting activities or photographic areas. The livelihoods of local communities of the Okavango delta who depended on fishing, hunter-gathering, livestock rearing, rain-fed agriculture and flood recession farming have been negatively affected by the expansion of conservation and tourism in the delta. The livelihoods alternatives in the form of Community Based Natural Resource Management (CBNRM) and tourism have not provided substitutes for the people as the communities are still reliant on the same old livelihood sources as in the past, albeit within smaller and restricted areas. This paper explores the ownership of the natural resources within the Okavango Delta. It asks and attempts to answer the following questions: Who owns and controls the use of the land? Who has access to other resources there in? Who makes the decisions on how the delta resources should be managed and used? Who benefits from the delta resources? We argue firstly that ownership of the delta as defined by legal parameters and demonstrated in natural resource management practice is vested on government. Secondly, government, after assuming ownership of the delta continues to sell its stake to the international community, at the expense of local ownership and access to resources. We

  5. Finite size effect on Ni doped nanocrystalline Ni{sub x}Zn{sub 1-x}Fe{sub 2}O{sub 4} (0.1 {<=} x {<=} 0.5)

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Ashok; Singh, Annveer [National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 12 (India); Yadav, M.S. [Department of Physics, Kurukshetra University Kurukshetra, Haryana (India); Arora, Manju [National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 12 (India); Pant, R.P., E-mail: rppant@nplindia.or [National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 12 (India)

    2010-11-30

    Nanocrystalline nickel ferrite with different concentration of Ni and Zn (Ni{sub x}Zn{sub 1-x}Fe{sub 2}O{sub 4} where x = 0.1, 0.3, 0.5) were synthesized using chemical co-precipitation method. The effect of doping ion concentration on physical properties like crystalline phase, crystallite size, particle size, and saturation magnetization are investigated. The X-ray diffraction pattern confirms the synthesis of single crystalline Ni{sub x}Zn{sub 1-x}Fe{sub 2}O{sub 4} nanoparticles. The lattice parameter decreases with increase Ni content resulting in reduction of lattice strain. HRTEM images revealed that the as-prepared nanoparticles were crystalline with particle size distribution in 10-30 nm range. The saturation magnetization show the superparamagnetic nature of sample for x = 0.1 and x = 0.3 whereas for x = 0.5, the material is ferromagnetic. The saturation magnetization value is 23.95 emu/gm for Ni{sub 0.1}Zn{sub 0.9}Fe{sub 2}O{sub 4} sample and it increases with increase in Ni content.

  6. Resistance switching characteristics of core–shell γ-Fe{sub 2}O{sub 3}/Ni{sub 2}O{sub 3} nanoparticles in HfSiO matrix

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Guangdong [Guizhou Institute of Technology, Guiyang 550003 (China); Wu, Bo, E-mail: fqwubo@zync.edu.cn [Institute of Theoretical Physics, Zunyi Normal College, Zunyi 563002 (China); School of Marine Science and Technology, Northwestern Polytechnical University, Xian 710072 (China); Liu, Xiaoqin; Li, Zhiling; Zhang, Shuangju [Guizhou Institute of Technology, Guiyang 550003 (China); Zhou, Ankun [Kunming Institute of Botany, Chineses Academy Sciences, Kunming 650201 (China); Yang, Xiude [Institute of Theoretical Physics, Zunyi Normal College, Zunyi 563002 (China)

    2016-09-05

    Core–shell γ-Fe{sub 2}O{sub 3}/Ni{sub 2}O{sub 3} nanoparticles are synthesized by chemical co-precipitation method. Resistive switching memory behaviors, which have resistance ON/OFF ratio of ∼10{sup 2} and excellent retention property, are observed in the Au/HfSiO/γ-Fe{sub 2}O{sub 3}/Ni{sub 2}O{sub 3}/HfSiO/Pt structure. Space charge limited current (SCLC) mechanism, which is supported by the fitting current–voltage results, is employed to know the resistive switching memory effects. The transportation of Oxygen vacancy Vo{sup 2+}, oxygen ion O{sup 2−}, recombination of oxygen atom and drive of external electric field are responsible for the ON or OFF states observed in device. - Highlights: • Bipolar resistance switching effects are detected in core–shell of γ-Fe{sub 2}O{sub 3}@Ni{sub 2}O{sub 3}. • The Ohimc conduction and space-charge-limited current play an important role in Low/High field. • Rapture of filament assisted by Vo{sup 2+}, O{sup 2−} and O{sub 2} recombination is responsible for switching. • Resistance switching memory highlights excellent retention properties after stress 100 cycles.

  7. Impact of sea-level rise in a Mediteranean delta: The Ebro delta cast

    NARCIS (Netherlands)

    Sánchez-Arcilla, A.; Stive, M.D.F.; Jiménez, J.A.; García, M.A.

    1993-01-01

    In anticipation of a comprehensive, multidisciplinary study on the impact of climatic change on the Ebro Delta preliminary results are here presented of the response of the outer delta coast to present and future relative sea-level rise. Due to the absence of observations and predictions of regional

  8. Final State Interactions and Delta S=-1, Delta C=\\pm 1 B--decays

    CERN Document Server

    Fayyazuddin, A

    2002-01-01

    The final state interactions (FSI) in Delta S=-1, Delta C=\\pm 1, decays of B-meson are discussed. The rescattering corrections are found to be of order of 15-20%. The strong interaction phase shifts are estimated and their effects on CP-asymmetry are discussed.

  9. A model for the Delta(1600) resonance and gamma N -> Delta(1600) transition

    CERN Document Server

    Ramalho, G

    2010-01-01

    A covariant spectator constituent quark model is applied to study the gamma N -> Delta(1600) transition. Two processes are important in the transition: a photon couples to the individual quarks of the Delta(1600) core (quark core), and a photon couples to the intermediate pion-baryon states (pion cloud). While the quark core contributions are estimated assuming Delta(1600) as the first radial excitation of Delta(1232), the pion cloud contributions are estimated based on an analogy with the gamma N -> Delta(1232) transition. To estimate the pion cloud contributions in the gamma N -> Delta(1600) transition, we include the relevant intermediate states, pi-N, pi-Delta, pi-N(1440) and pi-Delta(1600). Dependence on the four-momentum transfer squared, Q2, is predicted for the magnetic dipole transition form factor, GM*(Q2), as well as the helicity amplitudes, A_1/2(Q2) and A_3/2(Q2). The results at Q2=0 are compared with the existing data.

  10. A model for the Delta(1600) resonance and gamma N -> Delta(1600) transition

    Energy Technology Data Exchange (ETDEWEB)

    G. Ramalho, K. Tsushima

    2010-10-01

    A covariant spectator constituent quark model is applied to study the gamma N -> Delta(1600) transition. Two processes are important in the transition: a photon couples to the individual quarks of the Delta(1600) core (quark core), and a photon couples to the intermediate pion-baryon states (pion cloud). While the quark core contributions are estimated assuming Delta(1600) as the first radial excitation of Delta(1232), the pion cloud contributions are estimated based on an analogy with the gamma N -> Delta(1232) transition. To estimate the pion cloud contributions in the gamma N -> Delta(1600) transition, we include the relevant intermediate states, pi-N, pi-Delta, pi-N(1440) and pi-Delta(1600). Dependence on the four-momentum transfer squared, Q2, is predicted for the magnetic dipole transition form factor, GM*(Q2), as well as the helicity amplitudes, A_1/2(Q2) and A_3/2(Q2). The results at Q2=0 are compared with the existing data.

  11. Impact of sea-level rise in a Mediteranean delta: The Ebro delta cast

    NARCIS (Netherlands)

    Sánchez-Arcilla, A.; Stive, M.D.F.; Jiménez, J.A.; García, M.A.

    1993-01-01

    In anticipation of a comprehensive, multidisciplinary study on the impact of climatic change on the Ebro Delta preliminary results are here presented of the response of the outer delta coast to present and future relative sea-level rise. Due to the absence of observations and predictions of regional

  12. The Enabling Delta Life Initiative - Global Programme of Action on Deltas - Programme description

    NARCIS (Netherlands)

    Driel, van W.F.; Skyllerstedt, S.; Wosten, J.H.M.

    2014-01-01

    Being ‘hotspots’ of human activity with generally high population densities, deltas are vulnerable to changes induced by a range of driving forces, both natural and anthropogenic. In addition to already existing challenges, uncertainty of the possible impacts of climate change, low lying deltas arou

  13. Houtman Abrolhos Isotope (delta 18O, delta 13C) Data for 1795 to 1994

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — DESCRIPTION: VARIABLES AND UNITS: Column #1: core depth in mm Column #2: delta C-13 vs V-PDB Column #3: delta O-18 vs V-PDB Column #4: assigned date in years A.D....

  14. \\Delta Y/ \\Delta Z from the analysis of local K dwarfs

    CERN Document Server

    Gennaro, Mario; Degl'Innocenti, Scilla

    2010-01-01

    The stellar helium-to-metal enrichment ratio, \\Delta Y/\\Delta Z, is a widely studied astrophysical quantity. However, its value is still not precisely constrained. This paper is focused on the study of the main sources of uncertainty which affect the \\Delta Y/\\Delta Z derived from the analysis of the low-main sequence (MS) stars in the solar neighborhood. The possibility to infer the value of \\Delta Y/\\Delta Z from the study of low-MS stars relies on the dependence of the stellar luminosity and effective temperature on the initial Y and Z. The \\Delta Y/\\Delta Z ratio is obtained by comparing the magnitude difference between the observed stars and a reference theoretical zero age main sequence (ZAMS) with the related theoretical magnitude differences computed from a new set of stellar models with up-to-date input physics and a fine grid of chemical compositions. A Monte Carlo approach has been used to evaluate the impact on the result of different sources of uncertainty, i.e. observational errors, evolutionary...

  15. Holocene delta plain development in the Song Hong (Red River) delta, Vietnam

    Science.gov (United States)

    Funabiki, Ayako; Haruyama, Shigeko; Quy, Nguyen Van; Hai, Pham Van; Thai, Dinh Hung

    2007-05-01

    Holocene delta plain development was investigated based on three sediment cores analyzed in detail from the Song Hong (Red River) delta plain in Vietnam. Two cores (DA and PD) from the western delta plain showed both the landward limit of the transgressive estuarine system in the valley incised during the last glacial maximum and floodplain evolution since the middle Holocene. On the other hand, a core (TL) from the eastern delta plain revealed a Pleistocene terrace buried under the deltaic sediments and a slow accumulation rate compared with that in the west. At 8 cal ky BP, the shoreline migrated very close to the present Hanoi city area, and the sedimentary environment changed to tidal flat or salt marsh. Hanoi city marks the northern limit of shoreline transgression. The mangrove swamp expanded from 8 to 5 cal ky BP to the landward limit of the delta plain. Subsequently, the shoreline migrated seaward as a result of delta progradation and sea-level lowering. From 5 cal ky BP, the emerged area evolved into a floodplain and natural levees formed along the abandoned river channels on the western delta plain, but at 2 cal ky, archeological sites indicate that the Holocene terrace in the eastern delta plain was still inundated.

  16. MODIFICATION OF DELTA FOR CHOOSER OPTIONS

    Directory of Open Access Journals (Sweden)

    Marek Ďurica

    2015-09-01

    Full Text Available Correctly used financial derivatives can help investors increase their expected returns and minimize their exposure to risk. To ensure the specific needs of investors, a large number of different types of non-standard exotic options is used. Chooser option is one of them. It is an option that gives its holder the right to choose at some predetermined future time whether the option will be a standard call or put with predetermined strike price and maturity time. Although the chooser options are more expensive than standard European-style options, in many cases they are a more suitable instrument for investors in hedging their portfolio value. For an effective use of the chooser option as a hedging instrument, it is necessary to check the values of the Greek parameters delta and gamma for the options. Especially, if the value of the parameter gamma is too large, hedging of the portfolio value using only parameter delta is insufficient and brings high transaction costs because the portfolio has to be reviewed relatively often. Therefore, in this article, a modification of delta-hedging as well as using the value of parameter gamma is suggested. Error of the delta modification is analyzed and compared with the error of widely used parameter delta. Typical patterns for the modified hedging parameter variation with various time to choose time for chooser options are also presented in this article.

  17. Notched delta, phenotype, and Angelman syndrome.

    Science.gov (United States)

    Korff, Christian M; Kelley, Kent R; Nordli, Douglas R

    2005-08-01

    The notched delta pattern is one of the characteristic EEG features found in Angelman syndrome patients. The purpose of this study was to evaluate the possibility of using the notched delta pattern as a detection tool for Angelman syndrome patients by analyzing its frequency in a tertiary care pediatric center, its specificity for Angelman syndrome, and the age at which it was observed. The authors performed a retrospective review of the video-EEG recordings of all the patients who had either the notched delta pattern or a phenotype consistent with Angelman syndrome. The notched delta was observed in 1.1% of all the EEGs performed. Its specificity for Angelman syndrome was evaluated at 38%. The youngest age at which it was noted was 14 months. The results indicate that the notched delta pattern is relatively rare, but more frequent than expected, and is easily recognizable. The pattern was observed not only in Angelman syndrome patients, but also in children with a spectrum of conditions wider than reported. It is a powerful detection tool for Angelman syndrome when correlated to a suggestive phenotype, and the association of these features should raise suspicion for Angelman syndrome in both infants and adults.

  18. Tracking Nile Delta vulnerability to Holocene change.

    Directory of Open Access Journals (Sweden)

    Nick Marriner

    Full Text Available Understanding deltaic resilience in the face of Holocene climate change and human impacts is an important challenge for the earth sciences in characterizing the full range of present and future wetland responses to global warming. Here, we report an 8000-year mass balance record from the Nile Delta to reconstruct when and how this sedimentary basin has responded to past hydrological shifts. In a global Holocene context, the long-term decrease in Nile Delta accretion rates is consistent with insolation-driven changes in the 'monsoon pacemaker', attested throughout the mid-latitude tropics. Following the early to mid-Holocene growth of the Nile's deltaic plain, sediment losses and pronounced erosion are first recorded after ~4000 years ago, the corollaries of falling sediment supply and an intensification of anthropogenic impacts from the Pharaonic period onwards. Against the backcloth of the Saharan 'depeopling', reduced river flow underpinned by a weakening of monsoonal precipitation appears to have been particularly conducive to the expansion of human activities on the delta by exposing productive floodplain lands for occupation and irrigation agriculture. The reconstruction suggests that the Nile Delta has a particularly long history of vulnerability to extreme events (e.g. floods and storms and sea-level rise, although the present sediment-starved system does not have a direct Holocene analogue. This study highlights the importance of the world's deltas as sensitive archives to investigate Holocene geosystem responses to climate change, risks and hazards, and societal interaction.

  19. QCD in the {delta}-regime

    Energy Technology Data Exchange (ETDEWEB)

    Bietenholz, W. [Universidad Nacional Autonoma de Mexico, Mexico City (Mexico). Inst. de Ciencias Nucleares; Cundy, N. [Seoul National Univ. (Korea, Republic of). Lattice Gauge Theory Research Center; Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Horsley, R.; Zanotti, J.M. [Edinburgh Univ. (United Kingdom). School of Physics; Nakamura, Y. [Tsukuba Univ., Ibaraki (Japan). Center for Computational Sciences; Pleiter, D. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Div.; Schierholz, G. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2011-03-15

    The {delta}-regime of QCD is characterised by light quarks in a small spatial box, but a large extent in (Euclidean) time. In this setting a specific variant of chiral perturbation theory - the {delta}-expansion - applies, based on a quantum mechanical treatment of the quasi onedimensional system. In particular, for vanishing quark masses one obtains a residual pion mass M{sup R}{sub {pi}}, which has been computed to the third order in the {delta}-expansion. A comparison with numerical measurements of this residual mass allows for a new determination of some Low Energy Constants, which appear in the chiral Lagrangian. We first review the attempts to simulate 2-flavour QCD directly in the {delta}-regime. This is very tedious, but results compatible with the predictions for M{sup R}{sub {pi}} have been obtained. Then we show that an extrapolation of pion masses measured in a larger volume towards the {delta}-regime leads to good agreement with the theoretical predictions. From those results, we also extract a value for the (controversial) sub-leading Low Energy Constant anti l{sub 3}. (orig.)

  20. Structural phase transitions in the Ti{sub 45}Zr{sub 38}Ni{sub 17−x}Fe{sub x} nano-alloys and their deuterides

    Energy Technology Data Exchange (ETDEWEB)

    Rusinek, D.; Czub, J.; Niewolski, J. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Mickiewicza 30, 30-059 Kraków (Poland); Gondek, Ł., E-mail: lgondek@agh.edu.pl [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Mickiewicza 30, 30-059 Kraków (Poland); Gajewska, M. [AGH University of Science and Technology, Academic Centre for Materials and Nanotechnology, Mickiewicza 30, 30-059 Kraków (Poland); Takasaki, A. [Department of Engineering Science and Mechanics, Shibaura Institute of Technology, Toyosu, Kotoku, Tokyo 135-8548 (Japan); Hoser, A. [Helmholtz Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Żywczak, A. [AGH University of Science and Technology, Academic Centre for Materials and Nanotechnology, Mickiewicza 30, 30-059 Kraków (Poland)

    2015-10-15

    The mechanically alloyed Ti–Zr–Ni materials are extensively studied due to their promising properties concerning biomedical, electronic or hydrogen related applications (for example the gaseous hydrogen storage and the MNiH batteries). In this paper we address the very crucial issue of the structural properties and transformations of the amorphous and quasicrystalline Ti{sub 45}Zr{sub 38}Ni{sub 17−x}Fe{sub x} (x = 0, 4, 8) and their hydrides. According to the neutron diffraction results, the transformation of the amorphous Ti{sub 45}Zr{sub 38}Ni{sub 17} phase into the icosahedral quasicrystalline state (the i-phase) is quasi-continuous and starts at the relatively low temperature of 300 °C. At 500 °C the i-phase is well-developed. At higher temperatures the i-phase transforms into the approximant w-phase and eventually into the cubic phase (the c-phase). Interestingly, the deuterided i-phase exhibits completely different thermal evolution. Namely, this phase decomposes into the simple intermetallic compounds above 625 °C. What is worth-mentioning is that the release of deuterium is strictly related to that structural decomposition. The possibility of hydrogenation of the amorphous Ti{sub 45}Zr{sub 38}Ni{sub 17−x}Fe{sub x} phases with maintaining the amorphous nature of the alloys is the other extremely important field of our interest. We established a processing route to meet our goal. Finally, we show that introducing deuterium triggers an exciting phase transition from the deuterided amorphous phase into the unknown before, partially disordered, quasicrystalline-like phase (the glassy quasicrystal) without releasing of deuterium. - Highlights: • Formation and evolution of the quasicrystalline Ti{sub 45}Zr{sub 38}Ni{sub 17} phase is evidenced. • Fully deuterided Ti{sub 45}Zr{sub 38}Ni{sub 17−x}Fe{sub x} alloys, that remained amorphous, were obtained. • The deuterium atoms are likely the equivalent constituent of the amorphous alloys. • Glassy

  1. Reversible hydrogen storage in the Ni-rich pseudo-binary Mg{sub 6}Pd{sub 0.25}Ni{sub 0.75} intermetallic compound: Reaction pathway, thermodynamic and kinetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Ponthieu, M. [Dpto. Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, 28049 Madrid (Spain); ICMPE/CNRS-UPEC UMR 7182, 2-8 rue Henri Dunant, 94320 Thiais (France); Fernandez, J.F., E-mail: josefrancisco.fernandez@uam.es [Dpto. Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Cuevas, F. [ICMPE/CNRS-UPEC UMR 7182, 2-8 rue Henri Dunant, 94320 Thiais (France); Ares, J.R.; Leardini, F.; Bodega, J.; Sanchez, C. [Dpto. Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, 28049 Madrid (Spain)

    2013-01-25

    Highlights: Black-Right-Pointing-Pointer Mg{sub 6.2}Pd{sub 0.25}Ni{sub 0.65} reversibly absorbs 5.6 wt.% H in a two plateau pressure PCI. Black-Right-Pointing-Pointer The ternary phase depletes in Mg and Ni at low hydrogen pressure to form Mg{sub 2}Ni. Black-Right-Pointing-Pointer Reaction pathway of hydrogenation has been determined. Black-Right-Pointing-Pointer Enthalpy of the high pressure plateau is less negative than the one of pure Mg. Black-Right-Pointing-Pointer Low activation energy for desorption has been found for highly hydrided material. - Abstract: To improve the hydrogen storage properties of Mg{sub 6}Pd and to reduce its cost, Pd has been partly substituted by Ni at the solubility limit of the Mg{sub 6}(Pd,Ni) {rho}-phase. The attained composition is Mg{sub 6.2}Pd{sub 0.25}Ni{sub 0.65} as determined by Energy Dispersive X-Ray (EDX) and X-Ray Diffraction (XRD). Hydrogenation of this compound has been investigated by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM-EDX), Pressure-Composition-Isotherms (PCI) and thermal desorption analysis. On absorption, it decomposes in two steps as evidenced by two distinct plateau pressures. At low pressure, a partial segregation of Mg and Ni out of the pseudo-binary Mg{sub 6.2}Pd{sub 0.25}Ni{sub 0.65} {rho}-phase occurs leading to the formation of MgH{sub 2}, Mg{sub 2}Ni and Mg{sub 6}Pd{sub 0.7}Ni{sub 0.3} phases. At high pressure, the Mg{sub 6}Pd{sub 0.7}Ni{sub 0.3} phase disproportionates into MgH{sub 2}, Mg{sub 2}NiH{sub 4}, MgPd and Mg{sub 5}Pd{sub 2} phases. The hydrogenation reaction is reversible providing a hydrogen capacity of 5.6 wt.% H. The reaction enthalpy of the high pressure plateau is less negative than for pure Mg. Furthermore, the activation energy for H-desorption exhibits a dramatic decrease for hydrogen contents above 4 wt.% H, i.e. after the alloy disproportionation.

  2. A study on the origin of room temperature ferromagnetism in Ni{sub 1−x}Gd{sub x}O nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gokul, B. [PG and Research Department of Physics, Kongunadu Arts and Science College (Autonomous), Coimbatore 641029 (India); Saravanan, P. [Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad 500058 (India); Vinod, V.T.P.; Černík, Miroslav [Institute for Nanomaterials, Advanced Technologies and Innovation, Department of Natural Sciences, Technical University of Liberec, Studentská 1402/2, Liberec 1, 461 17 Czech Republic (Czech Republic); Sathyamoorthy, R., E-mail: rsathya59@gmail.com [PG and Research Department of Physics, Kongunadu Arts and Science College (Autonomous), Coimbatore 641029 (India)

    2015-11-15

    We herein report the existence of room temperature (RT) ferromagnetism (FM) in Gd-doped NiO nanoparticles prepared by hydrothermal process. The Gd-content in Ni{sub 1−x}Gd{sub x}O was varied from 0.01 to 0.1 and the resultant structural and magnetic properties due to Gd-doping were studied using X-ray diffraction (XRD), transmission electron microscopy (TEM), micro- Raman spectroscopy and vibrating sample magnetometer (VSM). The composition analysis and charge state were obtained from energy dispersive x-ray spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS), respectively. Both pure and Gd-doped NiO nanoparticles retained face centered cubic crystal structure. Formation of any secondary phases or metallic clusters related to pure Gd or Ni is not evident in the as-synthesized samples. TEM analysis revealed that the particles are spherical with sizes in the range of 8−18 nm. Micro-Raman spectra showed increase in Ni-vacancies with increase of Gd-concentration. XPS spectra of Gd-doped NiO revealed a shift in binding energy compared to the pure NiO, implies the replacement of Gd atoms in Ni-vacancies. Interesting RT-FM behavior is observed for the Gd concentrations of 7 and 10%; while the pure NiO and the other lower concentrations of Gd-doping demonstrated paramagnetic nature. The observed RT-FM can be attributed to the Ni vacancies induced by the doping of Gd{sup 3+} ions and this fact is explained on the basis of bound magnetic polaron model. - Highlights: • Gd-doped NiO nanoparticles of size 8−18 nm were synthesized by hydrothermal method. • Structural, magnetic and electronic properties were strongly affected by Gd-doping. • RT ferromagnetism was observed for the 7 and 10% Gd-doped NiO nanoparticles. • Maximum coercivity of 203 Oe was obtained for the Ni{sub 0.90}Gd{sub 0.10}O nanoparticles. • The origin of ferromagnetism in Gd-doped NiO is explained using BMP model.

  3. Interactions among mu- and delta-opioid receptors, especially putative delta1- and delta2-opioid receptors, promote dopamine release in the nucleus accumbens.

    NARCIS (Netherlands)

    Hirose, N.; Murakawa, K.; Takada, K.; Oi, Y.; Suzuki, T.; Nagase, H.; Cools, A.R.; Koshikawa, N.

    2005-01-01

    The effect of interactions among mu- and delta-opioid receptors, especially the putative delta(1)- and delta(2)-opioid receptors, in the nucleus accumbens on accumbal dopamine release was investigated in awake rats by in vivo brain microdialysis. In agreement with previous studies, perfusion of the

  4. Hydraulic engineering in the social-ecological delta: understanding the interplay between social, ecological, and technological systems in the Dutch delta by means of “delta trajectories”

    NARCIS (Netherlands)

    Staveren, van M.F.; Tatenhove, van J.P.M.

    2016-01-01

    Several of the world's largest deltas have recently been conceptualized as social-ecological delta systems. Although such conceptualizations are valuable in emphasizing complex interaction between social actors and ecological processes in deltas, they do not go into specific dynamics that surround t

  5. Interactions among mu- and delta-opioid receptors, especially putative delta1- and delta2-opioid receptors, promote dopamine release in the nucleus accumbens.

    NARCIS (Netherlands)

    Hirose, N.; Murakawa, K.; Takada, K.; Oi, Y.; Suzuki, T.; Nagase, H.; Cools, A.R.; Koshikawa, N.

    2005-01-01

    The effect of interactions among mu- and delta-opioid receptors, especially the putative delta(1)- and delta(2)-opioid receptors, in the nucleus accumbens on accumbal dopamine release was investigated in awake rats by in vivo brain microdialysis. In agreement with previous studies, perfusion of the

  6. El plan del delta - Holanda

    Directory of Open Access Journals (Sweden)

    Editorial, Equipo

    1963-09-01

    Full Text Available Holland is very poor in land resources. Hence its development has been directed towards intensive industrialization and maximum agricultural exploitation. The western part of the country is below sea level and is occupied by 65 percent of the population. Originally the coast consisted of a number of islands, estuaries and slight elevations. Man has transformed this coastline, first making a number of artificial lakes, or polders, and then converting these into fertile districts. These projects protect the soil by means of dykes, which require careful conservation, but even so violent floods are not infrequent. One of the difficult problems involved in this vast enterprise is the complex system of water supply, lines of communication and flow of the rivers into the sea along the estuary zone. This zone is on the south west, and to protect it a National Commission has been set up. After careful study, it was decided that the best defense against the violence of the sea would consist in closing off the inroads of the sea into the continental coastline. The set of hydraulic projects which constitutes this plan for the improvement of the sea defences will take 25 years to fulfil. The general project is highly ambitious and includes both maritime, road and structural works, in which there is a variety of stonework constructions. This paper describes, in brief outline, the main contents of the 11 headings into which the general construction project has been subdivided. In addition, this is supplemented with information on the projects which are already initiated and on the constructional procedure that is being adopted. Of these latter projects, the Nabla bridge is of particular interest. It is situated on the delta. It is made in prestressed concrete, and consists of 17 spans, of 60 length each. This enormous structure, in addition to its great length, and supporting a 22.8 ms wide roadway, is subjected to the tremendous forces 11» of the sea on one

  7. Microstructure and transformation behavior of Ni{sub 24.7}Ti{sub 50.3}Pd{sub 25} high temperature shape-memory alloy with Sc micro-addition

    Energy Technology Data Exchange (ETDEWEB)

    Ramaiah, K.V., E-mail: kvramaiah@nal.res.in [Materials Science Division, CSIR-National Aerospace Laboratories, Bangalore 560 017 (India); Saikrishna, C.N. [Materials Science Division, CSIR-National Aerospace Laboratories, Bangalore 560 017 (India); Gouthama [Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur 208 016 (India); Bhaumik, S.K. [Materials Science Division, CSIR-National Aerospace Laboratories, Bangalore 560 017 (India)

    2015-08-15

    NiTiPd shape-memory alloys (SMAs) are potential functional materials for use as solid-state actuators in the temperature range 100–250 °C. The present study investigates the effect of 1.0 at.% Sc micro-addition to Ni{sub 24.7}Ti{sub 50.3}Pd{sub 25} alloy, Sc replacing either Ti or Ni. Results show that all the three alloys studied have stable transformation behavior on stress-free thermal cycling and hence, are suitable for cyclic actuation applications. However, the addition of Sc to NiTiPd alloy leads to decrease of transformation temperatures, the magnitude of decrease being greater for the alloy with Sc replacing Ni. The martensite finish (M{sub f}) temperature of 181 °C for the NiTiPd alloy decreased to 139 °C for Sc replacing Ti and 83 °C for Sc replacing Ni. Also, the indentation modulus of NiTiPdSc (Sc replacing Ni) alloy is found to be significantly low compared to the other alloys. Analysis indicates that the observed differences in the alloy properties are related to the solubility of Sc in the NiTiPd matrix. While the quaternary NiTiPdSc alloy, Sc replacing Ti, has a single phase microstructure, the alloy with Sc replacing Ni shows the presence of Sc-rich and TiPd-type second phases in the microstructure. TEM examination revealed that the TiPd-type phase has a distinct rod-like morphology (30–50 nm) arranged in a grid-like structure. The transformation and indentation behavior of the alloys is elucidated using thermodynamic calculations of frictional energy and an electronic structure based analysis. - Highlights: • TEM of Ni{sub 23.7}Ti{sub 50.3}Pd{sub 25}Sc{sub 1} showed distinct grid of TiPd-type phase nanorods < 50 nm. • Stress-free thermal cycling of all the three alloys showed stable transformation behavior. • Ni{sub 24.7}Ti{sub 49.3}Pd{sub 25}Sc{sub 1} and Ni{sub 23.7}Ti{sub 50.3}Pd{sub 25}Sc{sub 1} showed single and multiphase structures. • Sc micro-addition (1 at.%) to Ni{sub 24.7}Ti{sub 50.3}Pd{sub 25} alloy decreased TTs

  8. Characterization of Ni{sub 5}3.5-Fe{sub 1}9.5-Ga{sub 2}7 Ni{sub 5}3.5 ferromagnetic shape memory alloy produced by powder metallurgy; Caracterizacion de la aleacion Ni{sub 5}3.5-Fe{sub 1}9.5-Ga{sub 2}7 con memoria de forma ferromagnetica producida por metalurgia de polvos

    Energy Technology Data Exchange (ETDEWEB)

    Olmos, L.; Alvarado-Hernandez, F.; Omar Jimenez, H.; Vergara-Hernandez, J.; Arroyo Albiter, M.; Ochoa-Gamboa, R. A.

    2015-07-01

    The main drawback of ferromagnetic shape memory alloys fabricated through casting methods are its brittleness. In order to overcome this disadvantage, powder metallurgy is an ideal technique for the consolidation of many engineering parts. This paper is focused on the study of the milling and sintering effects of metallic powders over the evolution of the crystalline phases responsibly for the shape memory effect of these materials. To achieve this objective, ferromagnetic shape memory alloy powders (Ni{sub 5}3.5-Fe{sub 1}9.5-Ga{sub 2}7) were prepared from a cast ingot by mechanical milling at two different times of 30 and 60 minutes. The evolution of the phases was investigated through high temperature X-ray diffraction (HTXRD), whereas sintering was analyzed with dilatometry tests. X-ray studies showed that four different phases can be present depending on the particle size and temperature at which the heat treatment was performed. Coarser powders showed a B2 structure along with a γ phase while the finer showed a L21 structure when treated below 1173 K. Furthermore, finer powders had a modulated M14 martensitic structure after sintering at temperatures above 1273 K. The sintering of powders was slow and a mass diffusion mechanism was not clearly observed. (Author)

  9. NATO-3C/Delta launch

    Science.gov (United States)

    1978-01-01

    NATO-3C, the third in a series of NATO defense-related communication satellites, is scheduled to be launched on a delta vehicle from the Eastern Test Range no earlier than November 15, 1978. NATO-3A and -3B were successfully launched by Delta vehicles in April 1976 and January 1977, respectively. The NATO-3C spacecraft will be capable of transmitting voice, data, facsimile, and telex messages among military ground stations. The launch vehicle for the NATO-3C mission will be the Delta 2914 configuration. The launch vehicle is to place the spacecraft in a synchronous transfer orbit. The spacecraft Apogee Kick motor is to be fired at fifth transfer orbit apogee to circularize its orbit at geosynchronous altitude of 35,900 km(22,260 miles) above the equator over the Atlantic Ocean somewhere between 45 and 50 degrees W longitude.

  10. Liquefaction potential of Nile delta, Egypt

    Science.gov (United States)

    Fergany, Elsayed; Omar, Khaled

    2017-06-01

    Understanding how sedimentary basins respond to seismic-wave energy generated by earthquake events is a significant concern for seismic-hazard estimation and risk analysis. The main goal of this study is assessing the vulnerability index, Kg, as an indicator for liquefaction potential sites in the Nile delta basin based on the microtremor measurements. Horizontal to Vertical spectral ratio analyses (HVSR) of ambient noise data, which was conducted in 2006 at 120 sites covering the Nile delta from south to north were reprocessed using Geopsy software. HVSR factors of amplification, A, and fundamental frequency, F, were calculated and Kg was estimated for each measurement. The Kg value varies widely from south toward north delta and the potential liquefaction places were estimated. The higher vulnerability indices are associated with sites located in southern part of the Nile delta and close to the branches of Nile River. The HVSR factors were correlated with geologic setting of the Nile delta and show good correlations with the sediment thickness and subsurface stratigraphic boundaries. However, we note that sites located in areas that have greatest percentage of sand also yielded relatively high Kg values with respect to sites in areas where clay is abundant. We concluded that any earthquake with ground acceleration more than 50 gal at hard rock can cause a perceived deformation of sandy sediments and liquefaction can take place in the weak zones of Kg ≥ 20. The worst potential liquefaction zones (Kg > 30) are frequently joined to the Damietta and Rosetta Nile River branches and south Delta where relatively coarser sand exists. The HVSR technique is a very sensitive tool for lithological stratigraphy variations in two dimensions and varying liquefaction susceptibility.

  11. Effect of W additions on the structural and magnetic properties of Ni{sub 50}Ti{sub 50−x}W{sub x} and Ti{sub 50}Ni{sub 50−x}W{sub x} systems obtained by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Jara, Angelica; Arjona, Jose David; Bautista, Pedro; Gonzalez, Gema, E-mail: gemagonz@ivic.gob.ve

    2014-12-05

    Highlights: • W additions strongly affect the magnetic and structural properties of Ni-Ti. • The saturation magnetization and magnetic remanence decreases with W addition. • W additions induces amophization of Ni-Ti. - Abstract: The effect of tungsten (W{sub x}) additions (x = 0.5, 1.0, 1.5 and 2.0 at.%), on the structural and magnetic properties of the binary systems Ni{sub 50}Ti{sub 50−x} and Ti{sub 50}Ni{sub 50−x} obtained by mechanical alloying was studied. The elementary powders were milled in a Spex 8000 horizontal mill, under N{sub 2} atmosphere, for 5 and 20 h. After 20 h of milling a homogenous microstructure was observed, particularly for small W additions. For this milling time a mixed of nanocrystalline and amorphous structure was obtained. As W concentration increases (1, 1.5 and 2 at.%), in both systems, the presence of small β-W reflections and the presence of very small peaks corresponding to the formation of an incipient new phase, identified as a NiTi(W) solid solution was observed, especially evident for 2 at.%W. The saturation magnetization and magnetic remanence decreases with the addition of W down to a minimum value at 1.5 at.%W, for both systems. The samples were characterized by SEM, EDS, XRD and magnetic measurements by VSM. The structural and magnetic behavior for both ternary alloys was very similar with the W additions.

  12. All optical binary delta-sigma modulator

    Science.gov (United States)

    Sayeh, Mohammad R.; Siahmakoun, Azad

    2005-09-01

    This paper describes a novel A/D converter called "Binary Delta-Sigma Modulator" (BDSM) which operates only with nonnegative signal with positive feedback and binary threshold. This important modification to the conventional delta-sigma modulator makes the high-speed (>100GHz) all-optical implementation possible. It has also the capability to modify its own sampling frequency as well as its input dynamic range. This adaptive feature helps designers to optimize the system performance under highly noisy environment and also manage the power consumption of the A/D converters.

  13. Measurement of the Muon Decay Parameter delta

    CERN Document Server

    Gaponenko, A N; Davydov, Yu I; Depommier, P; Doornbos, J; Faszer, W; Fujiwara, M C; Gagliardi, C A; Gill, D R; Green, P; Gumplinger, P; Hasinoff, M D; Henderson, R S; Hu, J; Jamieson, B; Kitching, P; Koetke, D D; Krushinsky, A A; Lachin, Yu Yu; MacDonald, J A; MacDonald, R P; Marshall, G M; Mathie, E L; Miasoedov, L V; Mischke, R E; Musser, J R; Nord, P M; Nozar, M; Olchanski, K; Olin, A; Openshaw, R; Porcelli, T A; Poutissou, J M; Poutissou, R; Quraan, M A; Rodning, N L; Selivanov, V; Sheffer, G; Shin, B; Sobratee, F; Stanislaus, T D S; Tacik, R; Torokhov, V D; Tribble, R E; Vasilev, M A; Wright, D H

    2004-01-01

    The muon decay parameter delta has been measured by the TWIST collaboration. We find delta = 0.74964 +- 0.00066(stat.) +- 0.00112(syst.), consistent with the Standard Model value of 3/4. This result implies that the product Pmuxi of the muon polarization in pion decay, Pmu, and the muon decay parameter xi falls within the 90% confidence interval 0.9960 < Pmuxi < xi < 1.0040. It also has implications for left-right-symmetric and other extensions of the Standard Model.

  14. Flood Inundation Modelling in Data Sparse Deltas

    Science.gov (United States)

    Hawker, Laurence; Bates, Paul; Neal, Jeffrey

    2017-04-01

    An estimated 7% of global population currently live in deltas, and this number is increasing over time. This has resulted in numerous human induced impacts on deltas ranging from subsidence, upstream sediment trapping and coastal erosion amongst others. These threats have already impacted on flood dynamics in deltas and could intensify in line with human activities. However, the myriad of threats creates a large number of potential scenarios that need to be evaluated. Therefore, to assess the impacts of these scenarios, a pre-requisite is a flood inundation model that is both computationally efficient and flexible in its setup so it can be applied in data-sparse settings. An intermediate scale, which compromises between the computational speed of a global model and the detail of a case specific bespoke model, was chosen to achieve this. To this end, we have developed an intermediate scale flood inundation model at a resolution of 540m of the Mekong Delta, built with freely available data, using the LISFLOOD-FP hydrodynamic model. The purpose of this is to answer the following questions: 1) How much detail is required to accurately simulate flooding in the Mekong Delta? , 2) What characteristics of deltas are most important to include in flood inundation models? Models were run using a vegetation removed SRTM DEM and a hind-casting of tidal heights as a downstream boundary. Results indicate the importance of vegetation removal in the DEM for inundation extent and the sensitivity of water level to roughness coefficients. The propagation of the tidal signal was found to be sensitive to bathymetry, both within the river channel and offshore, yet data availability for this is poor, meaning the modeller has to be careful in his or her choice of bathymetry interpolation Supplementing global river channel data with more localised data demonstrated minor improvements in results suggesting detailed channel information is not always needed to produce good results. It is

  15. DNA polymerase III accessory proteins. I. holA and holB encoding delta and delta'.

    Science.gov (United States)

    Dong, Z; Onrust, R; Skangalis, M; O'Donnell, M

    1993-06-05

    The genes encoding the delta and delta' subunits of the 10-subunit Escherichia coli replicase, DNA polymerase III holoenzyme, have been identified and sequenced. The holA gene encoding delta is located downstream of rlpB at 15.2 min and predicts a 38.7 kda protein. The holB gene encoding delta' is located at 24.3 min and predicts a 36.9-kDa protein. Hence the delta and delta' subunits are unrelated proteins encoded by separate genes. The genes have been used to express and purify delta and delta' in quantity. The predicted amino acid sequence of delta' is homologous to the sequences of the tau and gamma subunits revealing a large amount of structural redundancy within the holoenzyme.

  16. Heat Kernel Estimate for $\\Delta+\\Delta^{\\alpha/2}$ in $C^{1,1}$ open sets

    CERN Document Server

    Chen, Zhen-Qing; Song, Renming

    2010-01-01

    We consider a family of pseudo differential operators $\\{\\Delta+ a^\\alpha \\Delta^{\\alpha/2}; a\\in (0, 1]\\}$ on $\\bR^d$ for every $d\\geq 1$ that evolves continuously from $\\Delta$ to $\\Delta + \\Delta^{\\alpha/2}$, where $\\alpha \\in (0, 2)$. It gives rise to a family of L\\'evy processes $\\{X^a, a\\in (0, 1]\\}$ in $\\bR^d$, where $X^a$ is the sum of a Brownian motion and an independent symmetric $\\alpha$-stable process with weight $a$. We establish sharp two-sided estimates for the heat kernel of $\\Delta + a^{\\alpha} \\Delta^{\\alpha/2}$ with zero exterior condition in a family of open subsets, including bounded $C^{1, 1}$ (possibly disconnected) open sets. This heat kernel is also the transition density of the sum of a Brownian motion and an independent symmetric $\\alpha$-stable process with weight $a$ in such open sets. Our result is the first sharp two-sided estimates for the transition density of a Markov process with both diffusion and jump components in open sets. Moreover, our result is uniform in $a$ in the s...

  17. Abraham Reef Stable Isotope Data (delta 13C, delta 18O, delta 14C) for 1635-1957

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Site: Abraham Reef, 22ó 06'S, 153ó 00'E, Porites australiensus, Radiocarbon (delta 14C) and Stable Isotope (del 18O and del 13C) results from bi-annual samples from...

  18. Effects of a high magnetic field on structure evolution and properties of the molecular beam vapor deposited Fe{sub 60}Ni{sub 40} nanoparticles thin films

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Yongze [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Wang, Qiang, E-mail: wangq@mail.neu.edu.cn [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Li, Guojian; Du, Jiaojiao [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Wang, Xiaoguang [Huaxun Vacuum Technology Limited Company, Shenyang 110168 (China); He, Jicheng [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China)

    2014-12-15

    The Fe{sub 60}Ni{sub 40} (in atomic %) nanoparticles (NPs) thin films with 90 nm thickness were prepared on 25 and 400 °C quartz substrates by using the molecular beam vapor deposition (MBVD) method under a 6 T high magnetic field (HMF). The effects of a HMF on the structure evolution and properties of Fe–Ni thin films were studied by using X-ray diffraction, atomic force microscopy, transmission electron microscopy, vibrating sample magnetometer and four-point probe method. The results show that the crystallinity of thin films is enhanced by a 6 T HMF, and a 6 T HMF changes phase composition of thin films on 25 °C substrate. It is found that the nanoparticle size decreases; the nanoparticle size distribution becomes narrow, and the root mean square (rms) roughness of thin films decreases under a 6 T HMF relative to that without HMF. These lead to the decrease of coercive force, and the increase of in-plane remanence ratio under a 6 T HMF.

  19. Table-like magnetocaloric effect in Gd{sub 56}Ni{sub 15}Al{sub 27}Zr{sub 2} alloy and its field independence feature

    Energy Technology Data Exchange (ETDEWEB)

    Agurgo Balfour, E.; Ma, Z.; Fu, H., E-mail: fuhao@uestc.edu.cn, E-mail: rockingsandstorm@163.com; Wang, L.; Luo, Y. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Hadimani, R. L.; Jiles, D. C. [Department of Electrical and Computer Engineering, Iowa State University, Ames, Iowa 50011 (United States); Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011 (United States); Wang, S. F., E-mail: fuhao@uestc.edu.cn, E-mail: rockingsandstorm@163.com [North Electronic Device Research Institute, Beijing 100141 (China)

    2015-09-28

    In order to obtain “table-like” magnetocaloric effect (MCE), multiple-phase Gd{sub 56}Ni{sub 15}Al{sub 27}Zr{sub 2} alloy was prepared by arc-melting followed by suck-casting method. Powder x-ray diffraction and calorimetric measurements reveal that the sample contains both glassy and crystalline phases. The fraction of the glassy phase is about 62%, estimated from the heat enthalpy of the crystallization. The crystalline phases, Gd{sub 2}Al and GdNiAl further broadened the relatively wider magnetic entropy change (−ΔS{sub M}) peak of the amorphous phase, which resulted in the table-like MCE over a maximum temperature range of 52.5 K to 77.5 K. The plateau feature of the MCE was found to be nearly independent of the applied magnetic field from 3 T to 5 T. The maximum −ΔS{sub M} value of the MCE platforms is 6.0 J/kg K under applied magnetic field change of 5 T. Below 3 T, the field independence of the table-like feature disappears. The relatively large constant values of −ΔS{sub M} for the respective applied magnetic fields have promising applications in magnetic refrigeration using regenerative Ericsson cycle.

  20. Magnetic field dependence of electrical resistivity and thermopower in Ni{sub 50}Mn{sub 37}Sn{sub 13} ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Maheswar Repaka, D. V.; Chen, X.; Ramanujan, R. V., E-mail: ramanujan@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, 639798 (Singapore); Mahendiran, R., E-mail: phyrm@nus.edu.sg [Department of Physics, Faculty of Science, National University of Singapore, 117551 (Singapore)

    2015-09-15

    We report magnetization, magnetoresistance (MR) and magnetothermopower (MTEP) of melt spun Ni{sub 50}Mn{sub 37}Sn{sub 13} ribbons which exhibit an austentite to martensite phase transition at a temperature (T{sub M}) ≈ 294 K. Upon cooling from 400 K, dc-resistivity and thermopower show abrupt changes at T{sub M}, indicating a change in the electronic density of states. The thermopower is negative from 400 K down to 10 K. Application of a magnetic field of μ{sub 0}H = 5 T decreases T{sub M} by 5 K and induces large negative MR (-23%) but positive MTEP (9%) near T{sub M}. While the MR is appreciable from T{sub M} down to 10 K, MTEP is significant only below 60 K (MR = -2.5% and MTEP = +300% at 10 K). The magnetic field dependence of resistivity and thermopower show either reversible or irreversible behavior near T{sub M}, depending on whether the sample is zero-field cooled or field-cooled, which indicates that the electronic band structure near T{sub M} is magnetic history dependent.

  1. Large magnetic entropy change and magnetoresistance in a Ni{sub 41}Co{sub 9}Mn{sub 40}Sn{sub 10} magnetic shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Huang, L. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, No. 30 Xueyuan Rd, Haidian District, Beijing 100083 (China); School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Cong, D.Y., E-mail: dycong@ustb.edu.cn [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, No. 30 Xueyuan Rd, Haidian District, Beijing 100083 (China); Ma, L. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Nie, Z.H. [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Wang, M.G. [College of Sciences, Northeastern University, Shenyang 110819 (China); Wang, Z.L. [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Suo, H.L. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Ren, Y. [X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Wang, Y.D., E-mail: ydwang@ustb.edu.cn [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, No. 30 Xueyuan Rd, Haidian District, Beijing 100083 (China)

    2015-10-25

    A polycrystalline Ni{sub 41}Co{sub 9}Mn{sub 40}Sn{sub 10} (at. %) magnetic shape memory alloy was prepared by arc melting and characterized mainly by magnetic measurements, in-situ high-energy X-ray diffraction (HEXRD), and mechanical testing. A large magnetoresistance of 53.8% (under 5 T) and a large magnetic entropy change of 31.9 J/(kg K) (under 5 T) were simultaneously achieved. Both of these values are among the highest values reported so far in Ni–Mn–Sn-based Heusler alloys. The large magnetic entropy change, closely related to the structural entropy change, is attributed to the large unit cell volume change across martensitic transformation as revealed by our in-situ HEXRD experiment. Furthermore, good compressive properties were also obtained. The combination of large magnetoresistance, large magnetic entropy change, and good compressive properties, as well as low cost makes this alloy a promising candidate for multifunctional applications. - Highlights: • A large magnetoresistance of 53.8% under 5 T was obtained. • A large magnetic entropy change (ΔS{sub m}) of 31.9 J/(kg K) under 5 T was achieved. • A large unit cell volume change (ΔV) across phase transformation was revealed. • The large ΔS{sub m} obtained is closely related to the large ΔV across transformation. • Good compressive properties were obtained.

  2. Calorimetric and magnetic study for Ni{sub 50}Mn{sub 36}In{sub 14} and relative cooling power in paramagnetic inverse magnetocaloric systems

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jing-Han, E-mail: jhchen@tamu.edu [Department of Physics and Astronomy, Texas A and M University, College Station, Texas 77843 (United States); Bruno, Nickolaus M. [Department of Mechanical Engineering, Texas A and M University, College Station, Texas 77843 (United States); Karaman, Ibrahim [Department of Mechanical Engineering, Texas A and M University, College Station, Texas 77843 (United States); Department of Materials Science and Engineering, Texas A and M University, College Station, Texas 77843 (United States); Huang, Yujin; Li, Jianguo [School of Materials Science and Engineering, Shanghai Jiaotong University, Shanghai 200240 (China); Ross, Joseph H. [Department of Physics and Astronomy, Texas A and M University, College Station, Texas 77843 (United States); Department of Materials Science and Engineering, Texas A and M University, College Station, Texas 77843 (United States)

    2014-11-28

    The non-stoichiometric Heusler alloy Ni{sub 50}Mn{sub 36}In{sub 14} undergoes a martensitic phase transformation in the vicinity of 345 K, with the high temperature austenite phase exhibiting paramagnetic rather than ferromagnetic behavior, as shown in similar alloys with lower-temperature transformations. Suitably prepared samples are shown to exhibit a sharp transformation, a relatively small thermal hysteresis, and a large field-induced entropy change. We analyzed the magnetocaloric behavior both through magnetization and direct field-dependent calorimetry measurements. For measurements passing through the first-order transformation, an improved method for heat-pulse relaxation calorimetry was designed. The results provide a firm basis for the analytic evaluation of field-induced entropy changes in related materials. An analysis of the relative cooling power (RCP), based on the integrated field-induced entropy change and magnetizing behavior of the Mn spin system with ferromagnetic correlations, shows that a significant RCP may be obtained in these materials by tuning the magnetic and structural transformation temperatures through minor compositional changes or local order changes.

  3. Corrosion and oxidation properties of the refractory (Ni{sub 8}Nb{sub 5}){sub 99.8}Sb{sub 0.2} bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Lu, J; Zhang, J; Shek, C, E-mail: junxialu2@student.cityu.edu.h [Department of Physics and Materials Science, City University of Hong Kong (Hong Kong)

    2009-01-01

    Bulk metallic glass (BMG) with high corrosion resistance and high oxidation resistance was synthesized in the Ni-Nb-Sb system with the diameter of 3mm. The glass transition temperature (T{sub g}), the reduced glass transition temperature (T{sub rg}=T{sub g}/T{sub l}) and supercooled liquid span (DELTAT{sub x}) are 873K, 0.59 and 54K, respectively. These thermal data indicate that this kind of Ni-based glass can maintain its stable amorphous state and resist crystallization in a rather wide temperature region. Electrochemical measurements indicate that it shows high corrosion resistance in aggressive hydrochloric acid solution with 1N and 6N concentration, respectively, at room temperature. Surface forms stable passive film and presents low current density. The oxidation kinetics follows a parabolic rate law at 853K. The x-ray diffraction pattern showed that the oxide layer is composed of Nb{sub 2}O{sub 5}, Ni{sub 3}Nb and metallic Ni. The oxide surface morphologies showed that a layer of compact oxide film formed, which shows no obvious grain boundary.

  4. Structural and magnetic characterization of co-precipitated Ni{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Srinivas, Ch., E-mail: srinivas.chintoju75@gmail.com [Department of Physics, Sasi Institute of Technology and Engineering, Tadepalligudem 534101 (India); Tirupanyam, B.V. [Department of Physics, Government College (Autonomous), Rajamahendravaram 533103 (India); Meena, S.S.; Yusuf, S.M. [Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400085 (India); Babu, Ch. Seshu [Department of Physics, Sasi Institute of Technology and Engineering, Tadepalligudem 534101 (India); Ramakrishna, K.S. [Department of Physics, Srinivasa Institute of Engineering and Technology, Amalapuram 533222 (India); Potukuchi, D.M. [Department of Physics, University College of Engineering, Jawaharlal Nehru Technological University, Kakinada 533003 (India); Sastry, D.L., E-mail: dl_sastry@rediffmail.com [Department of Physics, Andhra University, Visakhapatnam 530003 (India)

    2016-06-01

    A series of Ni{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} (x=0.5, 0.6 and 0.7) ferrite nanoparticles have been synthesized using a co-precipitation technique, in order to understand the doping effect of nickel on their structural and magnetic properties. XRD and FTIR studies reveal the formation of spinel phase of ferrite samples. Substitution of nickel has promoted the growth of crystallite size (D), resulting the decrease of lattice strain (η). It was also observed that the lattice parameter (a) increases with the increase of Ni{sup 2+} ion concentration. All particles exhibit superparamagnetism at room temperature. The hyperfine interaction increases with the increase of nickel substitution, which can be assumed to the decrease of core–shell interactions present in the nanoparticles. The Mössbauer studies witness the existence of Fe{sup 3+} ions and absence of Fe{sup 2+} ions in the present systems. These superparamagnetic nanoparticles are supposed to be potential candidates for biomedical applications. The results are interpreted in terms of microstructure, cation redistribution and possible core–shell interactions. - Highlights: • Thermodynamic solubility of Ni{sup 2+} in zinc ferrite influences the crystallite sizes. • At room temperature the ferrite systems exhibit superparamagnetism. • Core–shell model was exactly suited to explain magnetic behavior. • Core–shell interactions decrease with increase in Ni{sup 2+} ion concentration.

  5. Production of Ni{sub 100-x-y}Mn{sub x}Ga{sub y} magnetic shape memory alloys by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Hatchard, T D; Thorne, J S; Dunlap, R A [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, B3H 3J5 (Canada); Farrell, S P [Defence R and D Canada-Atlantic, PO Box 1012, 9 Grove Street, Dartmouth, Nova Scotia, B2Y 3Z7 (Canada)], E-mail: hatchard@dal.ca

    2008-11-05

    Powdered samples of a variety of compositions of the off-stoichiometric magnetic shape memory alloy Ni{sub 2}MnGa have been prepared by mechanical alloying from elemental precursors. As-milled powders are highly disordered and show very weak ferromagnetic order. Annealing produces a well-ordered L2{sub 1} Heusler phase with high saturation magnetization. Annealing results in a consistent loss of Ga of about 1-4 at.% (of total sample composition). Structural and magnetic properties of a range of compositions have been measured and are reported in the present work. A magnetically oriented metal-polymer composite has been prepared by mixing the powdered sample in epoxy and curing under an externally applied magnetic field. The magnetic anisotropy energy of the composite sample has been measured and found to be about 20% of the value expected for a single crystal of similar composition. Possibilities for increasing the magnetic anisotropy of metal-polymer composites are discussed. Results are discussed in terms of the effects of structural and chemical order on the resulting magnetic properties in the context of a model based on indirect exchange interactions.

  6. High-pressure study of Ti{sub 50}Ni{sub 25}Fe{sub 25} powder produced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, A. S. [Departamento de Engenharia Mecânica, Universidade Federal de Santa Catarina, CP 476 Florianópolis, Santa Catarina 88040-900 (Brazil); Rovani, P. R. [Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul 91501-970 (Brazil); Lima, J. C. de, E-mail: joao.cardoso.lima@ufsc.br [Departamento de Física, Universidade Federal de Santa Catarina, CP 476 Florianópolis, 88040-900 Santa Catarina (Brazil); Pereira, A. S. [Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul 91501-970 (Brazil); Departamento de Materiais, Escola de Engenharia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul 91501-970 (Brazil)

    2015-02-21

    A nanostructured Ti{sub 50}Ni{sub 25}Fe{sub 25} phase (B2) was formed by mechanical alloying and its structural stability was studied as a function of pressure. The changes were followed by X-ray diffraction. The B2 phase was observed up to 7 GPa; for larger pressures, the B2 phase transformed into a trigonal/hexagonal phase (B19) that was observed up to the highest pressure used (18 GPa). Besides B2 and B19, elemental Ni or a SS-(Fe,Ni) and FeNi{sub 3} were observed. With decompression, the B2 phase was recovered. Using in situ angle-dispersive X-ray diffraction patterns, the single line method was applied to obtain the apparent crystallite size and the microstrain for both the B2 and the B19 phases as a function of the applied pressure. Values of the bulk modulus for the B2, B19, elemental Ni or SS-(Fe,Ni) and FeNi{sub 3} phases were obtained by fitting the pressure dependence of the volume to a Birch–Murnaghan equation of state (BMEOS)

  7. Correlation between dynamic slowing down and local icosahedral ordering in undercooled liquid Al{sub 80}Ni{sub 20} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Jakse, N.; Pasturel, A. [Sciences et Ingénierie des Matériaux et Procédés, UMR CNRS 5266, Grenoble Université Alpes, BP 75, 38402 Saint-Martin d’Hères Cedex (France)

    2015-08-28

    We use ab initio molecular dynamics simulations to study the correlation between the local ordering and the dynamic properties of liquid Al{sub 80}Ni{sub 20} alloy upon cooling. Our results evidence a huge increase of local icosahedral ordering (ISRO) in the undercooled regime which is more developed around Ni than Al atoms. We show that ISRO has a strong impact on self-diffusion coefficients of both species and is at the origin of their crossover from Arrhenius to non-Arrhenius behavior around a crossover temperature T{sub X} = 1000 K, located in the undercooled region. We also clearly identify that this temperature corresponds to the development of dynamic heterogeneities and to the breakdown of the Stokes-Einstein relation. At temperatures below this crossover, we find that the behavior of the diffusion and relaxation dynamics is mostly incompatible with predictions of the mode-coupling theory. Finally, an analysis of the van Hove function indicates that the crossover temperature T{sub X} marks the onset of a change in the diffusion mechanism from a normal flow to an activated process with hopping. From these results, the glass-forming ability of the alloy is discussed.

  8. Magnetic transitions driven by temperature in surface oxidized Co{sub 0.10}Ni{sub 0.90}/Cu(001) ultrathin films

    Energy Technology Data Exchange (ETDEWEB)

    Shih, Ying-Ta; Shen, Wen-He; Lee, Kuo-Long; Pan, Wei, E-mail: weipane@gmail.com [Department of Physics, National Chung Cheng University, Min-Hsiung, Chia-Yi 621, Taiwan (China)

    2014-01-15

    The magnetization of Co{sub 0.10}Ni{sub 0.90}/Cu(001) films before and after surface oxidization at 300 K is presented. Before the oxidization, the magnetization of the films in the thickness of 11 to 20 monolayers (ML) is in the in-plane direction at the temperature ranging from 140 K to 300 K. After the oxidization, the magnetizations of the films are in the in-plane direction at the temperature above 200 K, but transit to magnetization demolishment, in-plane-and-out-of-plane co-existence, spin reorientation transition, and coercivity enhancement, for films of 11, 12, 13, and above 15 ML, respectively. The blocking temperature of this film is also 200 K, which implies the transitions might be driven by the ordering of the antiferromagnetic surface oxides. The various magnetizations provide a model system for manipulating the magnetization direction, as well as a spin valve device by combination of the oxidized films.

  9. Weak ferromagnetism and temperature dependent dielectric properties of Zn{sub 0.9}Ni{sub 0.1}O diluted magnetic semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Raju [Department of Electrical and Electronic Engineering, Shahjalal University of Science and Technology, Sylhet 3114 (Bangladesh); Department of Applied Physics, Electronics and Communication Engineering, University of Dhaka, Dhaka 1000 (Bangladesh); Moslehuddin, A.S.M.; Mahmood, Zahid Hasan [Department of Applied Physics, Electronics and Communication Engineering, University of Dhaka, Dhaka 1000 (Bangladesh); Hossain, A.K.M. Akther, E-mail: akmhossain@phy.buet.ac.bd [Department of Physics, Bangladesh University of Engineering and Technology, Dhaka 1000 (Bangladesh)

    2015-03-15

    Highlights: • Single phase wurtzite structure was confirmed from XRD analysis. • Weak ferromagnetic behaviour at room temperature. • Pure semiconducting properties confirmed from temperature dependent conductivity. • Smaller dielectric properties at higher frequency. • Possible potential application in high frequency spintronic devices. - Abstract: In this study the room temperature ferromagnetic behaviour and dielectric properties of ZnO based diluted magnetic semiconductor (DMS) have been investigated using nominal chemical composition Zn{sub 0.9}Ni{sub 0.1}O. The X-ray diffraction analysis confirmed formation of single phase hexagonal wurtzite structure. An increase in grain size with increasing sintering temperature was observed from scanning electron microscopy. Field dependent DC magnetization values indicated dominant paramagnetic ordering along with a slight ferromagnetic behaviour at room temperature. Frequency dependent complex initial permeability showed some positive values around 12 at room temperature. In dielectric measurement, an increasing trend of complex permittivity, loss tangent and ac conductivity with increasing temperature were observed. The temperature dependent dispersion curves of dielectric properties revealed clear relaxation at higher temperature. Frequency dependent ac conductivity was found to increase with frequency whereas complex permittivity and loss tangent showed an opposite trend.

  10. Magnetic properties of Ni{sub 40+x}Mn{sub 39−x}Sn{sub 21} (x = 0, 2, 4, 6 and 8 at.%) Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lázpita, P., E-mail: patricia.lazpita@ehu.es [BCMaterials and UPV/EHU, Bilbao (Spain); Barandiarán, J.M. [BCMaterials and UPV/EHU, Bilbao (Spain); Chernenko, V.A. [BCMaterials and UPV/EHU, Bilbao (Spain); Ikerbasque, Basque Foundation for Science, Bilbao (Spain); Valle García, B. [UPV/EHU, EUITI Bilbao, Dpto. Ing. Minera, Metalurgia y Ciencia de los Materiales, Bilbao (Spain); Díaz Tajada, E. [UPV/EHU, ETS Náutica y Máquinas Navales, Dpto. Ing. Minera, Metalurgia y Ciencia de los Materiales, Portugalete (Spain); Lograsso, T. [Division of Materials Science and Engineering, Ames Laboratory, Ames, IA (United States); Department of Materials Science and Engineering, Iowa State University, Ames, IA (United States); Schlagel, D.L. [Division of Materials Science and Engineering, Ames Laboratory, Ames, IA (United States)

    2014-05-01

    Highlights: • Curie temperature versus e/a dependence shows broad maximum in NiMnSn alloys. • Magnetic moment versus e/a < 7.75 dependence was determined. • The localized magnetic moment model is compatible with the magnetic moment evolution. • The values of the magnetic moments indicate an almost full atomic order. - Abstract: The low electron concentration region (e/a < 7.75) of the magnetic phase diagram of the off-stoichiometric Ni–Mn–Sn Heusler alloys was investigated in detail by DSC and magnetization measurements of the Ni{sub 40+x}Mn{sub 39−x}Sn{sub 21}(x = 0, 2, 4, 6 and 8 at.%) alloys. The alloys show a stable austenitic phase without any martensitic transformation down to 5 K even after heat treatment. The Curie temperature exhibits a broad maximum over a large composition range. The evolution of the magnetic moment with the electron concentration fits the data of previous studies and confirms the peak-like dependence in the extended range of e/a values predicted by ab initio calculations. The explored part of the moment versus e/a curve can be explained in terms of a localized magnetic moment model and full atomic order in the alloys.

  11. Experimental explanation of the formation mechanism of surface mound-structures by femtosecond laser on polycrystalline Ni{sub 60}Nb{sub 40}

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Edwin; Wang, Meiyu; Lucis, Michael J.; Gogos, George; Shield, Jeffrey E. [Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States); Tsubaki, Alfred; Zuhlke, Craig A.; Bell, Ryan; Anderson, Troy P.; Alexander, Dennis R. [Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States)

    2016-01-18

    Femtosecond laser surface processing (FLSP) is an emerging technique for creating functionalized surfaces with specialized properties, such as broadband optical absorption or superhydrophobicity/superhydrophilicity. It has been demonstrated in the past that FLSP can be used to form two distinct classes of mound-like, self-organized micro/nanostructures on the surfaces of various metals. Here, the formation mechanisms of below surface growth (BSG) and above surface growth (ASG) mounds on polycrystalline Ni{sub 60}Nb{sub 40} are studied. Cross-sectional imaging of these mounds by focused ion beam milling and subsequent scanning electron microscopy revealed evidence of the unique formation processes for each class of microstructure. BSG-mound formation during FLSP did not alter the microstructure of the base material, indicating preferential valley ablation as the primary formation mechanism. For ASG-mounds, the microstructure at the peaks of the mounds was clearly different from the base material. Transmission electron microscopy revealed that hydrodynamic melting of the surface occurred during FLSP under ASG-mound forming conditions. Thus, there is a clear difference in the formation mechanisms of ASG- and BSG-mounds during FLSP.

  12. Tunable spin wave spectra in two-dimensional Ni{sub 80}Fe{sub 20} antidot lattices with varying lattice symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, R.; Barman, S.; Saha, S.; Barman, A., E-mail: abarman@bose.res.in [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India); Otani, Y. [CEMS-RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

    2015-08-07

    Ferromagnetic antidot lattices are important systems for magnetic data storage and magnonic devices, and understanding their magnetization dynamics by varying their structural parameters is an important problems in magnetism. Here, we investigate the variation in spin wave spectrum in two-dimensional nanoscale Ni{sub 80}Fe{sub 20} antidot lattices with lattice symmetry. By varying the bias magnetic field values in a broadband ferromagnetic resonance spectrometer, we observed a stark variation in the spin wave spectrum with the variation of lattice symmetry. The simulated mode profiles showed further difference in the spatial nature of the modes between different lattices. While for square and rectangular lattices extended modes are observed in addition to standing spin wave modes, all modes in the hexagonal, honeycomb, and octagonal lattices are either localized or standing waves. In addition, the honeycomb and octagonal lattices showed two different types of modes confined within the honeycomb (octagonal) units and between two such consecutive units. Simulated internal magnetic fields confirm the origin of such a wide variation in the frequency and spatial nature of the spin wave modes. The tunability of spin waves with the variation of lattice symmetry is important for the design of future magnetic data storage and magnonic devices.

  13. Synthesize and microstructure characterization of Ni{sub 43}Mn{sub 41}Co{sub 5}Sn{sub 11} Heusler alloy

    Energy Technology Data Exchange (ETDEWEB)

    Elwindari, Nastiti; Manaf, Azwar, E-mail: azwar@ui.ac.id [Physics Department, Faculty of Science, Universitas Indonesia, Depok 16424 (Indonesia)

    2016-06-17

    The ferromagnetic heusler alloys are promising materials in many technical applications due to their multifunctional properties such as shape memory effect, magnetocaloric effect, giant magnetoresistance, etc. In this work, synthesize and characterization of polycrystalline Ni{sub 43}Mn{sub 41}Co{sub 5}Sn{sub 11} (NMCS) alloy are reported. Alloy preparation was conducted by melting the constitute elements under an innert Argon (Ar) atmosphere in a vacuum mini arc-melting furnace. Homogenization of the microstructure of the as-cast ingot was obtained after annealing process at 750°C for 48 hours. It is shown that the dendrites structure has changed to equaixed grains morphology after homogenization. Microstructure characteristics of material by x-ray diffraction revealed that the alloy has a L{sub 21}-type cubic crystal structure as the main phase at room temperature. In order to induce the shape anisotropy, a forging treatment was applied to show the shape orientation of material. Various enhancements of magnetic properties in a longitudinal direction were observed at various degree of anisotropy. The microstructure changes of as-cast NMCS and effects of homogenization treatments as studied by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) are discussed in details.

  14. Mössbauer study of alloy Fe{sub 67.5}Ni{sub 32.5}, prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Benitez Rodríguez, Edson Daniel, E-mail: edbenitezr@ut.edu.co; Bustos Rodríguez, Humberto; Oyola Lozano, Dagoberto; Rojas Martínez, Yebrail Antonio [University of Tolima, Department of Physics (Colombia); Pérez Alcázar, German Antonio [University of Valle, Department of Physics (Colombia)

    2015-06-15

    We present the study of effect of the particle size on the structural and magnetic properties of the Fe{sub 67.5}Ni{sub 32.5} alloy, prepared by mechanical alloying (MA). After milling the powders during 10 hours they were separated by sieving using different meshes. The refinement of the X-ray patterns showed the coexistence of the BCC (Body Centered Cubic) and the FCC (Face Centered Cubic) phases in all samples with lattice parameters and crystallite sizes independent of the mean particle size. However, big particles presented bigger volumetric fraction of BCC grains. The Mossbauer spectra were fitted with a broad sextet corresponding to the ferromagnetic BCC phase, a hyperfine magnetic field distribution and a broad singlet which correspond to the ferromagnetic and paramagnetic sites of the FCC phase, respectively. Hysteresis loops showed a magnetically, soft behavior for all the samples, however, the saturation magnetization values are smaller for the original powder and for the powders with small, mean, particle size due to the dipolar magnetic interaction and the smaller mean magnetic moment, respectively. These effects were proved by Henkel plots that were made to the samples.

  15. Speculation of equilibrium pressure of Ti{sub 36}Zr{sub 40}Ni{sub 20}Pd{sub 4} icosahedral quasicrystal

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Huogen; Chen, Liang [China Academy of Engineering Physics, P.O. Box 919-71, Mianyang 621900, Sichuan Province (China)

    2015-08-17

    Ti-Zr-Ni quasicrystals have been demonstrated to store a large number of hydrogen atoms, which implies strong potential application in hydrogen energy field for them. However, the desorption of hydrogen atoms in the quasicrystals is quite difficult, with the indication of high desorption temperature and slow desorption rate. The shortage limits their use in the field to a large extent. But this kind of quasicrystals might be used in nuclear fusion energy field, because tritium as a coral fuel for nuclear fusion needs tight storage. However, equilibrium pressure at room temperature of Ti-Zr-Ni quasicrystals, important for their application in fusion energy field, has not been clear yet. In this work, we designed a gas-solid reaction system with the pressure resolution of 10{sup −8}Pa and carried out hydrogen desorption investigation at different temperatures on Ti{sub 36}Zr{sub 40}Ni{sub 20}Pd{sub 4} icosahedral quasicrystal. Based on three Pressure-Composition-Temperature desorption curves, we speculate according to Van’t Hoff theory about hydrogen storage that its equilibrium pressure at room temperature could be at the magnitude of 10{sup −6}Pa, displaying good stability of hydrogen in the quasicrystal and also implying application prospects in fusion energy field for quasicrystals of this type.

  16. High-power fiber laser welding and its application to metallic glass Zr{sub 55}Al{sub 10}Ni{sub 5}Cu{sub 30}

    Energy Technology Data Exchange (ETDEWEB)

    Kawahito, Yousuke [Joining and Welding Research Institute, Osaka University (JWRI), 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)], E-mail: kawahito@jwri.osaka-u.ac.jp; Terajima, Takeshi [Joining and Welding Research Institute, Osaka University (JWRI), 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kimura, Hisamich [Institute for Materials Research, Tohoku University (Japan); Kuroda, Toshio; Nakata, Kazuhiro; Katayama, Seiji [Joining and Welding Research Institute, Osaka University (JWRI), 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Inoue, Akihisa [Institute for Materials Research, Tohoku University (Japan)

    2008-02-25

    Fiber laser has been receiving attention due to its advantages of high-power and high-beam quality to produce narrow and deep penetration welds at high-welding speeds. Therefore, fiber laser welding is expected to apply to the joining of metallic glass which has unique properties such as high-mechanical strength or small solidification shrinkage, because extremely rapid quenching for the laser weldment or heat-affected zone (HAZ) is possible to remain amorphous. In this research, fiber laser welding was first performed with the objective of obtaining a fundamental knowledge of weld property produced in bead-on-plate welding for common marital such as Type 304 stainless steel with 6 kW fiber laser beams of several peak power densities. Deeply penetrated weld beads with narrow widths were produced with small spots of tightly focused laser beams and full-penetration welds in 8 mm thick plate could be obtained at the high-welding speed of 4.5 m/min. Subsequently, the tightly focused 2.5 kW fiber laser beam was applied to 72 m/min ultra-high-speed welding for metallic glass Zr{sub 55}Al{sub 10}Ni{sub 5}Cu{sub 30} in order to keep amorphous metals. Consequently, the weldment and HAZ remained desirably amorphous at ultra-high-welding speed with a tightly focused fiber laser beam.

  17. The microscopic structure of $\\pi NN$, $\\pi N\\Delta$ and $\\pi\\Delta\\Delta$ vertices in a hybrid constituent quark model

    CERN Document Server

    Jung, Ju-Hyun

    2016-01-01

    We present a microscopic description of the strong $\\pi NN$, $\\pi N\\Delta$ and $\\pi\\Delta\\Delta$ vertices. Our starting point is a constituent-quark model supplemented by an additional $3q\\pi$ non-valence component. In the spirit of chiral constituent-quark models, quarks are allowed to emit and reabsorb a pion. This multichannel system is treated in a relativistically invariant way within the framework of point-form quantum mechanics. Starting with a common $SU(6)$ spin-flavor-symmetric wave function for $N$ and $\\Delta$, we calculate the strength of the $\\pi NN$, $\\pi N\\Delta$ and $\\pi\\Delta\\Delta$ couplings and the corresponding vertex form factors. Our results are in accordance with phenomenological fits of these quantities that have been obtained within purely hadronic multichannel models for baryon resonances.

  18. Reduced complexity MASH delta-sigma modulator

    OpenAIRE

    Ye, Zhipeng; Kennedy, Michael Peter

    2007-01-01

    A reduced complexity digital multi-stage noise shaping (MASH) delta-sigma modulator for fractional-N frequency synthesizer applications is proposed. A long word is used for the first modulator in a MASH structure; the sequence length is maximized by setting the least significant bit of the input to 1; shorter words are used in subsequent stages. Experimental results confirm simulations

  19. Strong decays of nucleon and $\\Delta$ resonances

    CERN Document Server

    Bijker, R

    1996-01-01

    We study the strong couplings of the nucleon and delta resonances in a collective model. In the ensuing algebraic treatment we derive closed expressions for decay widths which are used to analyze the experimental data for strong decays into the pion and eta channels.

  20. How stable is the Mississippi Delta?

    NARCIS (Netherlands)

    Törnqvist, T.E.; Bick, S.J.; van der Borg, K.; de Jong, A.F.M.

    2006-01-01

    Large deltas are commonly believed to exhibit rapid rates of tectonic subsidence, largely due to sediment loading of the lithosphere. As a result, deltaic plains are prone to accelerated relative sea-level rise, coastal erosion, and wetland loss. Hurricane Katrina's devastation testifies to the seve

  1. Design of Low Power Sigma Delta ADC

    Directory of Open Access Journals (Sweden)

    Mohammed Arifuddin Sohel

    2012-08-01

    Full Text Available A Low power discrete time sigma delta ADC consisting of a second order sigma delta modulator and third order Cascaded Integrated Comb (CIC filter is proposed. The second order modulator is designed to work at a signal band of 20 K Hz at an oversampling ratio of 64 with a sampling frequency of 2.56 MHz. It achieves a signal to noise ratio of 85.2dB and a resolution of 14 bits. The CIC digital filter is designed to implement a decimation factor of 64, operating at a maximum sampling frequency of 2.56 MHz. A second order sigma delta modulator is implemented in 0.18 micron CMOS technology using full custom design and the third order digital CIC decimation filter is implemented in verilog HDL. The complete Sigma Delta ADC, consisting of analog block of second order modulator and digital block of decimator consumes a total power 1.96mW.

  2. Design of Low Power Sigma Delta ADC

    Directory of Open Access Journals (Sweden)

    Mohammed Arifuddin Sohel

    2012-09-01

    Full Text Available A Low power discrete time sigma delta ADC consisting of a second order sigma delta modulator and third order Cascaded Integrated Comb (CIC filter is proposed. The second order modulator is designed to work at a signal band of 20K Hz at an oversampling ratio of 64 with a sampling frequency of 2.56 MHz. It achieves a signal to noise ratio of 85.2dB and a resolution of 14 bits. The CIC digital filter is designed to implement a decimation factor of 64, operating at a maximum sampling frequency of 2.56 MHz. A second order sigma delta modulator is implemented in 0.18micron CMOS technology using full custom design and the third order digital CIC decimation filter is implemented in verilog HDL. The complete Sigma Delta ADC, consisting of analog block of second order modulator and digital block of decimator consumes a total power 1.96mW.

  3. The Niger Delta Avengers, Autonomous Ethnic Clans and Common ...

    African Journals Online (AJOL)

    Nneka Umera-Okeke

    The situation in Niger Delta region has remained an unanswered research question. When oil was discovered .... From the foregone analysis, the greed factor is sufficient to explain the crisis in Niger. Delta given the ..... homeless. The sizeable ...

  4. Habitat Management Plan for Delta and Breton National Wildlife Refuges

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Delta and Breton NWRs Habitat Management Plan provides a long-term vision and specific guidance on managing habitats for the resources of concern at Delta and...

  5. $\\delta-\\delta^\\prime$ generalized Robin boundary conditions and quantum vacuum fluctuations

    CERN Document Server

    Munoz-Castaneda, J M

    2014-01-01

    The effects induced by the quantum vacuum fluctuations of one massless real scalar field on a configuration of two partially transparent plates are investigated. The physical properties of the infinitely thin plates are simulated by means of Dirac-$\\delta-\\delta^\\prime$ point interactions. It is shown that the distortion caused on the fluctuations by this external background gives rise to a generalization of Robin boundary conditions. The $T$-operator for potentials concentrated on points with non defined parity is computed with total generality. The quantum vacuum interaction energy between the two plates is computed using the $TGTG$ formula to find positive, negative, and zero Casimir energies. The parity properties of the $\\delta-\\delta^\\prime$ potential allow repulsive quantum vacuum force between identical plates.

  6. Delta-Bar-Delta and directed random search algorithms to study capacitor banks switching overvoltages

    Directory of Open Access Journals (Sweden)

    Sadeghkhani Iman

    2012-01-01

    Full Text Available This paper introduces an approach to analyse transient overvoltages during capacitor banks switching based on artificial neural networks (ANN. Three learning algorithms, delta-bar-delta (DBD, extended delta-bar-delta (EDBD and directed random search (DRS were used to train the ANNs. The ANN training is based on equivalent parameters of the network and therefore, a trained ANN is applicable to every studied system. The developed ANN is trained with extensive simulated results and tested for typical cases. The new algorithms are presented and demonstrated for a partial 39-bus New England test system. The simulated results show the proposed technique can accurately estimate the peak values of switching overvoltages.

  7. Delta Delta Excitation in Proton-Proton Induced pi0pi0 Production

    CERN Document Server

    Skorodko, T; Bogoslawsky, D; Calen, H; Clement, H; Doroshkevich, E; Demiroers, L; Ekstroem, C; Fransson, K; Gustafsson, L; Hoistad, B; Ivanov, G; Jacewicz, M; Jiganov, E; Johansson, T; Khakimova, O; Keleta, S; Koch, I; Kren, F; Kullander, S; Kupsc, A; Marciniewski, P; Meier, R; Morosov, B; Pauly, C; Petren, H; Petukhov, Y; Povtorejko, A; Ruber, R J M Y; Schoenning, K; Scobel, W; Shwartz, B; Stepaniak, J; Thoerngren-Engblom, P; Tikhomirov, V; Wagner, G J; Wolke, M; Yamamoto, A; Zabierowski, J; Zlomanczuk, J

    2010-01-01

    Exclusive measurements of the $pp \\to pp\\pi^0\\pi^0$ reaction have been performed at CELSIUS/WASA at energies from threshold up to $T_p$ = 1.3 GeV. Total and differential cross sections have been obtained. Here we concentrate on energies $T_p \\ge$ 1 GeV, where the $\\Delta\\Delta$ excitation becomes the leading process. No evidence is found for a significant ABC effect beyond that given by the conventional $t$-channel $\\Delta\\Delta$ excitation. This holds also for the double-pionic fusion to the quasibound $^2$He. The data are compared to model predictions, which are based on both pion and $\\rho$ exchange. Total and differential cross sections are at variance with these predictions and call for a profound modification of the $\\rho$-exchange. A phenomenological modification allowing only a small $\\rho$ exchange contribution leads to a quantitative description of the data.

  8. {Delta}{Delta} excitation in proton-proton induced {pi}{sup 0{pi}0} production

    Energy Technology Data Exchange (ETDEWEB)

    Skorodko, T.; Bashkanov, M. [Physikalisches Institut der Universitaet Tuebingen, D-72076 Tuebingen (Germany); Bogoslawsky, D. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Calen, H. [The Svedberg Laboratory, Uppsala (Sweden); Clement, H., E-mail: Clement@pit.physik.uni-tuebingen.d [Physikalisches Institut der Universitaet Tuebingen, D-72076 Tuebingen (Germany); Doroshkevich, E. [Physikalisches Institut der Universitaet Tuebingen, D-72076 Tuebingen (Germany); Demiroers, L. [Hamburg University, Hamburg (Germany); Ekstroem, C.; Fransson, K. [The Svedberg Laboratory, Uppsala (Sweden); Gustafsson, L.; Hoeistad, B. [Uppsala University, Uppsala (Sweden); Ivanov, G. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Jacewicz, M. [Uppsala University, Uppsala (Sweden); Jiganov, E. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Johansson, T. [Uppsala University, Uppsala (Sweden); Khakimova, O. [Physikalisches Institut der Universitaet Tuebingen, D-72076 Tuebingen (Germany); Keleta, S.; Koch, I. [Uppsala University, Uppsala (Sweden); Kren, F. [Physikalisches Institut der Universitaet Tuebingen, D-72076 Tuebingen (Germany); Kullander, S. [Uppsala University, Uppsala (Sweden)

    2011-01-10

    Exclusive measurements of the pp{yields}pp{pi}{sup 0{pi}0} reaction have been performed at CELSIUS/WASA at energies from threshold up to T{sub p}=1.3 GeV. Total and differential cross sections have been obtained. Here we concentrate on energies T{sub p{>=}}1 GeV, where the {Delta}{Delta} excitation becomes the leading process. No evidence is found for a significant ABC effect beyond that given by the conventional t-channel {Delta}{Delta} excitation. This holds also for the double-pionic fusion to the quasibound {sup 2}He. The data are compared to model predictions, which are based on both {pi}- and {rho}-exchange. Total and differential cross sections are at variance with these predictions and call for a profound modification of the {rho}-exchange. A phenomenological modification allowing only a small {rho}-exchange contribution leads to a quantitative description of the data.

  9. A delta-catenin signaling pathway leading to dendritic protrusions.

    Science.gov (United States)

    Abu-Elneel, Kawther; Ochiishi, Tomoyo; Medina, Miguel; Remedi, Monica; Gastaldi, Laura; Caceres, Alfredo; Kosik, Kenneth S

    2008-11-21

    Delta-catenin is a synaptic adherens junction protein pivotally positioned to serve as a signaling sensor and integrator. Expression of delta-catenin induces filopodia-like protrusions in neurons. Here we show that the small GTPases of the Rho family act coordinately as downstream effectors of delta-catenin. A dominant negative Rac prevented delta-catenin-induced protrusions, and Cdc42 activity was dramatically increased by delta-catenin expression. A kinase dead LIMK (LIM kinase) and a mutant Cofilin also prevented delta-catenin-induced protrusions. To link the effects of delta-catenin to a physiological pathway, we noted that (S)-3,5-dihydroxyphenylglycine (DHPG) activation of metabotropic glutamate receptors induced dendritic protrusions that are very similar to those induced by delta-catenin. Furthermore, delta-catenin RNA-mediated interference can block the induction of dendritic protrusions by DHPG. Interestingly, DHPG dissociated PSD-95 and N-cadherin from the delta-catenin complex, increased the association of delta-catenin with Cortactin, and induced the phosphorylation of delta-catenin within the sites that bind to these protein partners.

  10. Morphodynamics of a cyclic prograding delta: the Red River, Vietnam

    NARCIS (Netherlands)

    Maren, D.S. van

    2004-01-01

    River deltas are inhabited by over 60% of the world population, and are, consequently, of paramount agricultural and economical importance. They constitute unique wetland envi ronments which gives river deltas ecological importance as well. Additionally, many deltas contain large accumulations of oi

  11. 78 FR 45592 - DeltaPoint Capital IV, LP;

    Science.gov (United States)

    2013-07-29

    ... ADMINISTRATION DeltaPoint Capital IV, LP; Notice Seeking Exemption Under Section 312 of the Small Business Investment Act, Conflicts of Interest Notice is hereby given that DeltaPoint Capital IV, L.P., 45 East Avenue... Business Administration (``SBA'') Rules and Regulations (13 CFR 107.730). DeltaPoint Capital IV,...

  12. Comparative assessment of the vulnerability and resilience of 10 deltas : work document

    NARCIS (Netherlands)

    Bucx, T.; Marchand, M.; Makaske, B.; Guchte, van de C.

    2010-01-01

    Background information about: Nile delta (Egypt), Incomati delta (Mozambique), Ganges-Brahmaputra-Meghna (Bangladesh), Yangtze (China), Ciliwung (Indonesia), Mekong (Vietnam), Rhine-Meuse (The Netherlands), Danube (Romania), California Bay-Delta, Mississippi River Delta (USA)

  13. Evidence for a parity doublet Delta(1920)P33 and Delta(1940)D33 from gammap-->ppi;{0}eta.

    Science.gov (United States)

    Horn, I; Anisovich, A V; Anton, G; Bantes, R; Bartholomy, O; Beck, R; Beloglazov, Yu; Bogendörfer, R; Castelijns, R; Crede, V; Ehmanns, A; Ernst, J; Fabry, I; Flemming, H; Fösel, A; Fuchs, M; Funke, Chr; Gothe, R; Gridnev, A; Gutz, E; Höffgen, St; Hössl, J; Junkersfeld, J; Kalinowsky, H; Klein, F; Klempt, E; Koch, H; Konrad, M; Kopf, B; Krusche, B; Langheinrich, J; Löhner, H; Lopatin, I; Lotz, J; Matthäy, H; Menze, D; Messchendorp, J; Metag, V; Nikonov, V A; Novinski, D; Ostrick, M; van Pee, H; Sarantsev, A V; Schmidt, C; Schmieden, H; Schoch, B; Suft, G; Sumachev, V; Szczepanek, T; Thoma, U; Walther, D; Weinheimer, Chr

    2008-11-14

    Evidence is reported for the existence of a parity doublet of Delta resonances with total angular momentum J=3/2 from photoproduction of the ppi;{0}eta final state. The two parity partners Delta(1920)P33 and Delta(1940)D33 make significant contributions to the reaction. Cascades of resonances into Delta(1232)eta, N(1535)pi, and Na0(980) are clearly observed.

  14. Phase transition and magnetocaloric effect of Ni{sub 50}Mn{sub 29}Ga{sub 21−x}Tb{sub x} (0 ⩽ x ⩽ 1) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yuye; Wang, Jingmin, E-mail: jingmin@buaa.edu.cn; Hua, Hui; Jiang, Chengbao; Xu, Huibin

    2015-05-25

    Highlights: • Effect of Tb addition on phase transition temperatures of Ni{sub 50}Mn{sub 29}Ga{sub 21} were clarified. • Coupled magneto-structural transition were observed in Ni{sub 50}Mn{sub 29}Ga{sub 21}Tb{sub 0.2} alloy. • Large magnetocaloric effect was monitored from the magneto-structural transition. - Abstract: Ni{sub 50}Mn{sub 29}Ga{sub 21−x}Tb{sub x} (0 ⩽ x ⩽ 1) alloys were studied with the microstructure, phase transition, and magnetocaloric effect. Dual-phase microstructure containing the martensite matrix and Tb-rich precipitations were formed. The martensitic transformation was observed over the whole composition range, with the transformation temperature T{sub M} significantly increased by the addition of terbium. The magnetic transition temperatures of the austenite and martensite, i.e. T{sub C}{sup A} and T{sub C}{sup M}, were monitored for 0 ⩽ x ⩽ 0.16 and 0.27 ⩽ x ⩽ 1, respectively. Both T{sub C}{sup A} and T{sub C}{sup M} were slightly decreased by the addition of terbium. For 0.16 ⩽ x ⩽ 0.27 the martensitic transformation was coincided with the magnetic transition in case of T{sub M} = T{sub C}, giving rise to the coupled magneto-structural transition from ferromagnetic martensite to paramagnetic austenite. Sizable magnetic entropy change was induced by magnetic field in the vicinity of the coupled magneto-structural transition.

  15. The e/a-constant Hume-Rothery phases in an As-cast Zr{sub 65}Al{sub 7.5}Ni{sub 10}Cu{sub 17.5} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Shek, C.H. [City Univ. of Hong Kong, Kowloon (Hong Kong). Dept. of Physics and Materials Science; Wang, Y.M. [City Univ. of Hong Kong, Kowloon (Hong Kong). Dept. of Physics and Materials Science; Dalian Univ. of Technology (China). Dept. of Materials Engineering; Dong, C. [Dalian Univ. of Technology (China). Dept. of Materials Engineering

    2000-10-31

    The microstructure of an as-cast Zr{sub 65}Al{sub 7.5}Ni{sub 10}Cu{sub 17.5} ingot was studied by TEM and XRD analysis. Apart from the amorphous phase, five crystalline phases were identified, namely, face-centered cubic cF (0.5273 nm), body-centered tetragonal tI-Zr{sub 67.0}Al{sub 1.7}Ni{sub 8.4}Cu{sub 22.9} (0.3216, 1.1120 nm), hexagonal hP{sup 1}-Zr{sub 65.4}Al{sub 11.7}Ni{sub 11.6}Cu{sub 11.3} phase (0.8175, 0.3337 nm), hexagonal phase hP{sup 2} (0.8175, 0.3337 nm), and orthorhombic oP (0.8210, 1.3187, 0.3315 nm). The latter two phases are superstructures of hP{sup 1}. Compared with the nominal sample composition, the tI phase is rich in Cu but poor in Al, the hP{sup 1}, hP{sup 2} and oP phases are to the contrary. All the phases, including the amorphous phase, are Hume-Rothery phases having nearly the same valence electron concentration. Therefore the amorphous phase is strongly related with its related crystalline phases in electronic structure. This should constitute an empirical criterion for high glass forming ability, i.e. the compositions of the amorphous alloy and its crystalline counterparts should be near a constant valence electron concentration 'surface' in the quaternary Zr-Al-Ni-Cu phase diagram. (orig.)

  16. Nanostructure investigation of magnetic nanomaterial Ni{sub 0.5}Zn{sub 0.3}Cu{sub 0.2}Fe{sub 2}O{sub 4} synthesized by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Pransisco, Prengki, E-mail: prengkipransisco@gmail.com [Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Badan Lingkungan Hidup Derah Kabupaten Empat Lawang South of Sumatera (Indonesia); Shafie, Afza, E-mail: afza@petronas.com.my; Guan, Beh Hoe, E-mail: beh.hoeguan@petronas.com.my [Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2015-07-22

    Magnetic nanomaterial Ni{sub 0.5}Zn{sub 0.3}Cu{sub 0.2}Fe{sub 2}O{sub 4} was successfully prepared by using sol-gel method. Heat treatment on material is always giving defect on properties of material. This paper investigates the effect of heat treatment on nanostructure of magnetic nanomaterial Ni{sub 0.5}Zn{sub 0.3}Cu{sub 0.2}Fe{sub 2}O{sub 4}. According to thermo gravimetric analysis (TGA) that after 600°C there is no more weight loss detected and it was decided as minimum calcination temperature. Intensity, crystallite size, structure, lattice parameter and d-spacing of the material were investigated by using X-ray diffraction (XRD). High resolution transmission electron microscope (HRTEM) was used to examine nanostructure, nanosize, shape and distribution particle of magnetic material Ni{sub 0.5}Zn{sub 0.3}Cu{sub 0.2}Fe{sub 2}O{sub 4} and variable pressure field emission scanning electron microscope (VP-FESEM) was used to investigate the surface morphology and topography of the material. The XRD result shows single-phase cubic spinel structure with average crystallite size in the range of 25.6-95.9 nm, the value of the intensity of the material was increased with increasing temperature, and followed by lattice parameter was increased with increasing calcination temperature, value of d-spacing was relatively decreased with accompanied increasing temperature. From HRTEM result the distribution of particles was tend to be agglomerates with particle size of 7.8-17.68 nm. VP-FESEM result shows that grain size of the material increases with increasing calcination temperature and the surface morphology shows that the material is in hexagonal shape and it was also proved by mapping result which showing the presence each of constituents inside the compound.

  17. Microstructure and mechanical behavior of a novel Co{sub 20}Ni{sub 20}Fe{sub 20}Al{sub 20}Ti{sub 20} alloy fabricated by mechanical alloying and spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Zhiqiang, E-mail: kopyhit@163.com [School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou, Guangdong 510640 (China); Department of Chemical Engineering and Materials Science, University of California at Davis, Davis, CA 95616 (United States); Chen, Weiping [School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou, Guangdong 510640 (China); Wen, Haiming [Characterization Department, Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Morgan, Sam [Department of Chemical Engineering and Materials Science, University of California at Davis, Davis, CA 95616 (United States); Chen, Fei [State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Zheng, Baolong; Zhou, Yizhang [Department of Chemical Engineering and Materials Science, University of California at Davis, Davis, CA 95616 (United States); Zhang, Lianmeng [State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Lavernia, Enrique J., E-mail: lavernia@uci.edu [Department of Chemical Engineering and Materials Science, University of California at Davis, Davis, CA 95616 (United States); Department of Chemical Engineering and Materials Science, University of California, Irvine, Irvine, CA, 92697 (United States)

    2015-09-17

    A novel equiatomic Co{sub 20}Ni{sub 20}Fe{sub 20}Al{sub 20}Ti{sub 20} (at%) alloy was designed and synthesized to study the effect of high atomic concentrations of Al and Ti elements on the microstructure, phase composition and mechanical behavior of high-entropy alloys (HEAs) fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). Following the MA process, the Co{sub 20}Ni{sub 20}Fe{sub 20}Al{sub 20}Ti{sub 20} alloy was composed of a primary body-centered cubic (BCC) supersaturated solid solution and a face-centered cubic (FCC) supersaturated solid solution. However, following SPS, a primary FCC solid-solution phase, a BCC solid-solution phase and a trace amount of Al{sub 3}Ti intermetallics were observed. Transmission electron microscopy (TEM) results confirmed the presence of the FCC solid-solution phase, the BCC (B2-type) solid-solution phase and Al{sub 3}Ti intermetallics in the bulk alloy. The FCC and B2-type phases are ultrafine-grained, and Al{sub 3}Ti intermetallics is nano/ultrafine-grained. Our results suggest that consideration of a single existing empirical design criterion is inadequate to explain phase formation in the Co{sub 20}Ni{sub 20}Fe{sub 20}Al{sub 20}Ti{sub 20} alloy. Solid-solution strengthening, grain-boundary strengthening, twin-boundary strengthening, the presence of the strong B2-type BCC phase, and precipitate strengthening due to the presence of a trace amount of Al{sub 3}Ti are responsible for the ultra-high compressive strength of ~2988 MPa and hardness of ~704 Hv. The strain-to-failure of ~5.8% with visible ductility is dominated by the FCC solid-solution phase.

  18. 78 FR 22911 - Delta Air Lines, Inc., Reservation Sales and Customer Care Call Center, Seatac, WA; Delta Air...

    Science.gov (United States)

    2013-04-17

    ... Employment and Training Administration Delta Air Lines, Inc., Reservation Sales and Customer Care Call Center, Seatac, WA; Delta Air Lines, Inc., Reservation Sales and Customer Care Call Center, Sioux City, IA... workers and former workers of Delta Air Lines, Inc., Reservation Sales and Customer Care Call...

  19. Improved electrochemical properties of Li{sub 1.2}Ni{sub 0.18}Mn{sub 0.59}Co{sub 0.03}O{sub 2} by surface modification with LiCoPO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Liu Bing; Zhang Qian; He Shici [Institute of Chemical Power Sources, Soochow University, No. 688, Moye Road, Suzhou, 215006 (China); Sato, Yuichi [Department of Applied Chemistry, Faculty of Engineering, Kanagawa University, 3-27-1 Rokkakubashi, Kanagawa-ku, Yokohama 221-8686 (Japan); Zheng Junwei [Institute of Chemical Power Sources, Soochow University, No. 688, Moye Road, Suzhou, 215006 (China); Li Decheng, E-mail: lidecheng@suda.edu.cn [Institute of Chemical Power Sources, Soochow University, No. 688, Moye Road, Suzhou, 215006 (China)

    2011-07-30

    Highlights: > Li[Li{sub 0.2}Ni{sub 0.18}Mn{sub 0.59}Co{sub 0.03}]O{sub 2} was prepared by Spray dry method. > Li[Li{sub 0.2}Ni{sub 0.18}Mn{sub 0.59}Co{sub 0.03}]O{sub 2} was modified with LiCoPO{sub 4} by Co-precipitation. > LiCoPO{sub 4} particles are about 20 nm and could not form a uniform thin layer. > LiCoPO{sub 4} modification upgrades the cycleability of Li[Li{sub 0.2}Ni{sub 0.18}Mn{sub 0.59}Co{sub 0.03}]O{sub 2}. > LiCoPO{sub 4} modification improves the rate capability of Li[Li{sub 0.2}Ni{sub 0.18}Mn{sub 0.59}Co{sub 0.03}]O{sub 2}. - Abstract: Lithium-rich nickel-manganese-cobalt oxide, Li{sub 1.2}Ni{sub 0.18}Mn{sub 0.59}Co{sub 0.03}O{sub 2}, prepared by spray-dry process, exhibits rapid capacity fade and poor rate capability. The surface of Li{sub 1.2}Ni{sub 0.18}Mn{sub 0.59}Co{sub 0.03}O{sub 2} can be modified with LiCoPO{sub 4} through co-precipitation method in order to improve its electrochemical properties. The resultant LiCoPO{sub 4} particles are in nano-scale and accumulate on the surface of the Li{sub 1.2}Ni{sub 0.18}Mn{sub 0.59}Co{sub 0.03}O{sub 2} particles. The surface modification by LiCoPO{sub 4} is shown to significantly improve both the cyclic performance and the rate capability of Li{sub 1.2}Ni{sub 0.18}Mn{sub 0.59}Co{sub 0.03}O{sub 2}.

  20. Growth and structure of K{sub 2}Ni{sub x}Co{sub (1–x)}(SO{sub 4}){sub 2} · 6H{sub 2}O single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Vasilyeva, N. A., E-mail: Natalie5590@mail.ru; Sorokina, N. I.; Antipin, A. M.; Verin, I. A.; Voloshin, A. E. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2016-01-15

    Single crystals of the K{sub 2}Ni{sub x}Co{sub (1–x)}(SO{sub 4}){sub 2} · 6H{sub 2}O composition are grown by spontaneous flux crystallization. More exact chemical formulas of the single crystals are determined based on the diffraction data as K{sub 2}Co(SO{sub 4}){sub 2} · 6H{sub 2}O (I), K{sub 2}(Co{sub 0.657}Ni{sub 0.343})(SO{sub 4}){sub 2} · 6H{sub 2}O (II), K{sub 2}(Co{sub 0.226}Ni{sub 0.774})(SO{sub 4}){sub 2} · 6H{sub 2}O (III), K{sub 2}(Co{sub 0.216}Ni{sub 0.784})(SO{sub 4}){sub 2} · 6H{sub 2}O (IV), and K{sub 2}Ni(SO{sub 4}){sub 2} · 6H{sub 2}O (V). The substitution of nickel atoms for cobalt atoms in structure I results in a shortening of all (Co,Ni)–O interatomic distances. With increasing Ni concentration, the (Co,Ni)–O2 distance shortens to a lesser degree than the (Co,Ni)–O1 and (Co,Ni)–O3 distances and, as a consequence, the distortion of (Co,Ni)O{sub 6} octahedra decreases. NiO{sub 6} polyhedra are less distorted than CoO{sub 6} octahedra. The analysis of difference syntheses of electron density shows that the number of uninterpretable peaks on the maps of mixed crystals II, III, and IV, as well as on the map of K{sub 2}Co(SO{sub 4}){sub 2} · 6H{sub 2}O, is larger with respect to those of structure K{sub 2}Ni(SO{sub 4}){sub 2} · 6H{sub 2}O.

  1. Effect of sand blasting on structural, thermal, and mechanical properties of Zr{sub 58.3}Cu{sub 18.8}Al{sub 14.6}Ni{sub 8.3} bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Tariq, Naeem ul Haq; Awais, Hasan Bin; Naeem, Muhammad; Shahid, Rub Nawaz [Pakistan Institute of Engineering and Applied Sciences, Islamabad (Pakistan). Dept. of Metallurgy and Materials Engineering; Akhter, Javaid Iqbal [Pakistan Institute of Nuclear Science and Technology, Islamabad (Pakistan). Physics Div.

    2012-07-15

    In the present work sand-blasting-induced structural, thermal, and mechanical effects were studied in Zr{sub 58.3}Cu{sub 18.8}Al{sub 14.6}Ni{sub 8.3} bulk metallic glass. It was observed that sand blasting favors disordering of the atomic configuration, formation of free volume and evolution of multiple intersecting shear bands. As a result, considerable compressive plasticity was achieved in sand-blasted samples. It was also observed that in order to superimpose the effect of prestraining and extra free volume for improving compressive plasticity, there exists a limit to both parameters. (orig.)

  2. Aging phenomena in Cu{sub 0.1}Ni{sub 0.8}Co{sub 0.2}Mn{sub 1.9}O{sub 4} NTC ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Shpotyuk, O.; Vakiv, M.; Mrooz, O. [Scientific Research Co. ' ' Carat' ' , Lviv (Ukraine); Hadzaman, I. [Scientific Research Co. ' ' Carat' ' , Lviv (Ukraine); Drohobych State Pedagogical Univ., Drohobych (Ukraine); Plewa, J.; Uphoff, H.; Altenburg, H. [Fachhochschule Muenster, Steinfurt (Germany)

    2002-07-01

    Aging effects in Cu{sub 0.1}Ni{sub 0.8}Co{sub 0.2}Mn{sub 1.9}O{sub 4} NTC ceramics were studied for the first time by electrical and microstructural measurements. The increase in resistivity induced by aging tests at 125 and 170 C during 1000 h was observed. The changes of the electrical properties of the investigated NTC thermistors were explained, using the results of ceramics microstructural characterization, thermogravimetry, optical and electron microscopy techniques. (orig.)

  3. Dendritic microstructure in the metallic glass matrix composite Zr{sub 56}Ti{sub 14}Nb{sub 5}Cu{sub 7}Ni{sub 6}Be{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Y.-L. [IV. Physikalisches Institut der Georg-August-Universitaet Goettingen, Friedrich-Hund-Platz 1, D-37077 Goettingen (Germany); Bracchi, A. [IV. Physikalisches Institut der Georg-August-Universitaet Goettingen, Friedrich-Hund-Platz 1, D-37077 Goettingen (Germany)]. E-mail: abracch@gwdg.de; Niermann, T. [IV. Physikalisches Institut der Georg-August-Universitaet Goettingen, Friedrich-Hund-Platz 1, D-37077 Goettingen (Germany); Seibt, M. [IV. Physikalisches Institut der Georg-August-Universitaet Goettingen, Friedrich-Hund-Platz 1, D-37077 Goettingen (Germany); Danilov, D. [Applied Research Center, Karlsruhe University of Applied Sciences, Moltkestrasse 30, D-76133 Karlsruhe (Germany); Nestler, B. [Applied Research Center, Karlsruhe University of Applied Sciences, Moltkestrasse 30, D-76133 Karlsruhe (Germany); Schneider, S. [IV. Physikalisches Institut der Georg-August-Universitaet Goettingen, Friedrich-Hund-Platz 1, D-37077 Goettingen (Germany)

    2005-07-15

    The microstructure and the chemical composition of an in situ formed dendritic body-centered cubic phase in the bulk Zr{sub 56}Ti{sub 14}Nb{sub 5}Cu{sub 7}Ni{sub 6}Be{sub 12} composite were studied by high-resolution and analytical transmission electron microscopy. The distribution of all elements (Zr, Ti, Nb, Cu, Ni, Be) was experimentally determined in the bulk phases (matrix and dendrites) and in the dendrite/matrix interface, and the results were compared with numerically simulated composition profiles obtained by multi-component phase-field simulations.

  4. The influence of chemical disorder enhancement on the martensitic transformation of the Ni{sub 50}Mn{sub 36}Sn{sub 14} Heusler-type alloy

    Energy Technology Data Exchange (ETDEWEB)

    Passamani, E.C., E-mail: edson@cce.ufes.br [Departamento de Fisica, Universidade Federal do Espirito Santo, 29075-910 Vitoria, ES (Brazil); Nascimento, V.P.; Larica, C.; Takeuchi, A.Y. [Departamento de Fisica, Universidade Federal do Espirito Santo, 29075-910 Vitoria, ES (Brazil); Alves, A.L.; Proveti, J.R. [Departamento de Ciencias Matematicas e Naturais, Universidade Federal do Espirito Santo, 29932-540, Sao Mateus, ES (Brazil); Pereira, M.C. [Instituto de Ciencia e Tecnologia, Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM), 39803-371 Teofilo Otoni, Minas Gerais (Brazil); Fabris, J.D. [Departamento de Quimica, UFVJM, 39100-000 Diamantina, Minas Gerais (Brazil)

    2011-07-28

    Highlights: > Chemical disorder affects martensitic transformation in Ni-Mn-Sn Heusler alloys. > Martensitic transition temperature depends on the L21-ferromagnetic fraction. > Grain boundaries induce drastic reduction of magnetization in milled Heusler alloys. > Magnetic properties of the milled Ni50Mn36Sn14 alloy get better after annealing. - Abstract: The effect of chemical disorder over the martensitic phase transformation of the Ni{sub 50}Mn{sub 36}Sn{sub 14} Heusler-type alloy was systematically investigated by performing X-ray diffractometry (DRX), DC magnetization and {sup 57}Fe-doping and {sup 119}Sn-Moessbauer spectroscopy measurements. DRX patterns are characteristics of a L2{sub 1}-type chemically disordered structure, where the presence of this disorder was first evaluated by analyzing the relative intensity of the (1 1 1) DRX reflection, which varies in the case of Fe-doped and practically disappears for the milled samples. In consequence, the magnetic properties of Fe-doped well-milled samples related to the martensitic phase transformation change substantially. 300 K {sup 57}Fe-Moessbauer spectroscopy data suggest that the changes in the magnetic properties related to the martensitic transformation are intrinsically correlated to the ferromagnetic and paramagnetic fractions, which are respectively associated with Fe atoms replacing Mn- and Sn-sites. In the case of milled samples, the drastic reduction of alloy magnetization was explained by the increase of the number of Mn atoms in the shell regions, which have a reduced magnetic moment comparatively to those in the grain cores. The magnetization change and the temperature transition in the martensitic transformation are governed by the grain core. The initial magnetic properties and martensitic transformation can be recovered by a subsequent annealing on the milled sample.

  5. Microstructure and precipitates in annealed Co{sub 38}Ni{sub 33}Al{sub 29} ferromagnetic shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Lu, J.B., E-mail: jblu10@gmail.com [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Shi, H. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Sedlakova-Ignacova, S. [Department of Functional Materials, Institute of Physics ASCR v.v.i., Na Slovance 2, Prague 8 CZ-182 21 (Czech Republic); Espinoza, R. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Kopeček, J.; Sittner, P. [Department of Functional Materials, Institute of Physics ASCR v.v.i., Na Slovance 2, Prague 8 CZ-182 21 (Czech Republic); Bártová, B. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); CIME and LSME, École Polytechnique Fédérale de Lausanne, Station 12, Lausanne CH-1015 (Switzerland); Schryvers, D. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2013-09-25

    Highlights: •Micron-sized non-twinned, single and triple twinned precipitates characterized. •Precipitates and austenite matrix fit K–S orientation relationship. •The precipitates are Co-rich and Al- and Ni-deficient with respect to matrix. •The twinned precipitates have a plate-like shape. •The non-twinned precipitates have an often bent lath-like shape. -- Abstract: Transmission electron microscopy was performed to investigate the microstructure and precipitates in the annealed Co{sub 38}Ni{sub 33}Al{sub 29} ferromagnetic shape memory alloy. Apart from the dendritic secondary phase in the austenite matrix, micron-sized (up to 100 μm) fcc-based precipitates with partial γ′ L1{sub 2} ordering and containing none, one or three {1 1 1}{sub p} parallel twin planes were found. The orientation relationship between the precipitates and matrix was found to be Kurdjumov–Sachs. STEM–EDX analysis indicates that twinned and non-twinned precipitates are Co-rich and Al- and Ni-deficient with respect to the matrix and with a lower Co/Al ratio for the latter. The 3D morphologies of precipitates were reconstructed with focused ion beam/scanning electron microscope dual-beam slice-and-view imaging, showing that the single {1 1 1}{sub p} plane twinned precipitates have a plate-like shape while the non-twinned precipitates are lath-like and often bent.

  6. Microwave absorption properties of lightweight absorber based on Fe{sub 50}Ni{sub 50}-coated poly(acrylonitrile) microspheres and reduced graphene oxide composites

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Bin [School of Material Science And Engineering, Wuhan University of Technology, Wuhan 430070 (China); Wang, Jun, E-mail: wgdfrp@whut.edu.cn [School of Material Science And Engineering, Wuhan University of Technology, Wuhan 430070 (China); Wang, Junpeng; Huo, Siqi [School of Material Science And Engineering, Wuhan University of Technology, Wuhan 430070 (China); Zhang, Bin [School of Science, Wuhan University of Technology, Wuhan 430070 (China); Tang, Yushan [School of Material Science And Engineering, Wuhan University of Technology, Wuhan 430070 (China)

    2016-09-01

    In this paper, we proposed a facile method to obtain the lightweight composites consisting of surface modified Fe{sub 50}Ni{sub 50}-coated poly(acrylonitrile) microspheres (PANS@SMF), reduced graphene oxide (RGO) and epoxy resin. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM) and vector network analyzer (VNA). Impedance matching condition and electromagnetic wave attenuation characteristic were used for the reflection loss (RL) performance of the composites. Compared with pure PANS@SMF and RGO composites, the −10 dB absorption bandwidth and the minimum RL of the hybrid composites were enhanced. The bandwidth less than −10 dB was almost 4.5 GHz in the range of 10 GHz to 14.5 GHz, with a matching thickness of 2.5 mm. The density of the hybrid composites was in the range of 0.25–0.34 g/cm{sup 3}. Therefore, the hybrid composite can be considered as a potential lightweight microwave absorber. - Highlights: • PANS@SMF – RGO epoxy composite was fabricated by a facile method. • The absorption bandwidth less than −10 dB can reach up to 4.5 GHz with layer thickness of 2.5 mm. • The density of the composites is in the range of 0.25–0.34 g/cm{sup 3} and can be considered as a lightweight microwave absorber.

  7. Dynamic and rate-dependent yielding behavior of Co{sub 0.9}Ni{sub 0.1} microcluster based magnetorheological fluids

    Energy Technology Data Exchange (ETDEWEB)

    Arief, Injamamul; Mukhopadhyay, P.K., E-mail: pkm@bose.res.in

    2016-01-01

    In this paper we performed steady shear and oscillatory magnetorheological (MR) studies in magnetic fluids containing CoNi sub-micron sized clusters of 450 nm in diameter. Such Co-rich nanoclusters were synthesized by conventional homogeneous nucleation without any external surfactant or reducing agent in liquid polyol at elevated temperature. The x-ray diffraction, energy dispersive x-ray analysis, scanning and transmission electron microscopy studies were done for analyzing the sample composition and morphology. Two variants of fluid samples were prepared by dispersing 15 vol% and 20 vol% of CoNi powders in castor oil. Room temperature steady magnetoshear studies indicate viscoplastic behavior with stronger dependence of static yield stress on magnetization than a dipolar coupling that was operational in the dynamic yield stress. Magnetosweep measurements at constant shear rate showed interesting viscous relaxation at high magnetic fields. We also explored dynamical elastic behavior through oscillatory magnetorheological studies under both strain sweep and frequency sweep modes, and showed glass transition like phenomenon occurring in them above critical shear amplitudes. - Highlights: • A typical polymer/surfactant free polyol reduction method was used to synthesize large-scale Co{sub 0.9}Ni{sub 0.1} nanoclusters. • Room temperature rate-dependent magnetorheology of CoNi-nanoclusters based MR fluids revealed viscoplastic behavior. • Magnetic fields were replaced by powder particle magnetization (M) for better yield stress scaling. • In addition to previously reported M{sup 2}-dependence, higher order relations (~M{sup 3}) were also noted for static yield stress. • An interesting viscous relaxation phenomenon occurred at higher magnetic fields.

  8. STM-Induced Void Formation at the Al{sub 2}O{sub 3}/Ni{sub 3}Al(111) Interface

    Energy Technology Data Exchange (ETDEWEB)

    Magtoto, N.P.; Niu, C.; Anzaldura, M.; Kelber, J.A.; Jennison, D.R.

    2000-09-21

    Under UHV conditions at 300 K, the applied electric field and/or resulting current from an STM tip creates nanoscale voids at the interface between an epitaxial, 7.0 {angstrom} thick Al{sub 2}O{sub 3} film and a Ni{sub 3}Al(111) substrate. This phenomenon is independent of tip polarity. Constant current (1 nA) images obtained at +0.1 V bias and +2.0 bias voltage (sample positive) reveal that voids are within the metal at the interface and, when small, are capped by the oxide film. Void size increases with time of exposure. The rate of void growth increases with applied bias/field and tunneling current, and increases significantly for field strengths >5 MV/cm, well below the dielectric breakdown threshold of 12 {+-} 1 MV/cm. Slower rates of void growth are, however, observed at lower applied field strengths. Continued growth of voids, to {approximately}30 {angstrom} deep and {approximately}500 {angstrom} wide, leads to the eventual failure of the oxide overlayer. Density Functional Theory calculations suggest a reduction-oxidation (REDOX) mechanism: interracial metal atoms are oxidized via transport into the oxide, while oxide surface Al cations are reduced to admetal species which rapidly diffuse away. This is found to be exothermic in model calculations, regardless of the details of the oxide film structure; thus, the barriers to void formation are kinetic rather than thermodynamic. We discuss our results in terms of mechanisms for the localized pitting corrosion of aluminum, as our results suggest nanovoid formation requires just electric field and current, which are ubiquitous in environmental conditions.

  9. In situ spectroscopic characterization of Ni>1-xZnx/ZnO catalysts and their selectivity for acetylene semihydrogenation in excess ethylene

    Energy Technology Data Exchange (ETDEWEB)

    Spanjers, Charles S.; Sim, Richard S.; Sturgis, Nicholas P.; Kabius, Bernd; Rioux, Robert M. (Penn State)

    2015-10-30

    The structures of ZnO-supported Ni catalysts were explored with in situ X-ray absorption spectroscopy, temperature-programmed reduction, X-ray diffraction, high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy, and electron energy loss spectroscopy. Calcination of nickel nitrate on a nanoparticulate ZnO support at 450 °C results in the formation of Zn-doped NiO (ca. N₀̣̣₈₅ Zn₀̣̣₁₅O) nanoparticles with the rock salt crystal structure. Subsequent in situ reduction monitored by X-ray absorption near-edge structure (XANES) at the Ni K edge reveals a direct transformation of the Zn-doped NiO nanoparticles to a face-centered cubic alloy, Ni>1-xZnx, at ~400 °C with x increasing with increasing temperature. Both in situ XANES and ex situ HRTEM provide evidence for intermetallic β₁-NiZn formation at ~550 °C. In comparison to a Ni/SiO₂ catalyst, Ni/ZnO necessitates a higher temperature for the reduction of NiII to Ni⁰, which highlights the strong interaction between Ni and the ZnO support. The catalytic activity for acetylene removal from an ethylene feed stream is decreased by a factor of 20 on Ni/ZnO in comparison to Ni/SiO₂. The decrease in catalytic activity of Ni/ZnO is accompanied by a reduced absolute selectivity to ethylene. H–D exchange measurements demonstrate a reduced ability of Ni/ZnO to dissociate hydrogen in comparison to Ni/SiO₂.These results of the catalytic experiments suggest that the catalytic properties are controlled, in part, by the zinc oxide support and stress the importance of reporting absolute ethylene selectivity for the catalytic semihydrogenation of acetylene in excess ethylene.

  10. Spectral factorization using the delta operator

    DEFF Research Database (Denmark)

    Rostgaard, Morten; Poulsen, Niels Kjølstad; Ravn, Ole

    1994-01-01

    In recent years many papers have been published abouth the gamma-operator, mostly caused by the better numerical properties and the rapprochement between continuous and discrete time. A major problem within the LQG-design of a delta-based input-output relation has been how to spectral-factorize i......In recent years many papers have been published abouth the gamma-operator, mostly caused by the better numerical properties and the rapprochement between continuous and discrete time. A major problem within the LQG-design of a delta-based input-output relation has been how to spectral......-factorize in an efficient way. The discrete-time method of Kuccera will not be applied since numerical word-length characteristics will be poor for fast sampling rates. In this paper a new approach is considered. A new gamma-operator (Tustin operator) is introduced, in order to make an iterative and numerical stable...

  11. Nucleon and Delta structure in continuum QCD

    Science.gov (United States)

    Cloet, Ian

    2014-03-01

    Quantum Chromodynamics (QCD) is the only known example in nature of a fundamental quantum field theory that is innately non-perturbative. Solving QCD will have profound implications for our understanding of the natural world, for example, it will explain how light quarks and massless gluons bind together to form the observed mesons and baryons; hence explaining the origin of more than 98% of the mass in the visible universe. Given the challenges posed by QCD, it is insufficient to study hadron ground-states alone if one seeks a solution; in this regard the delta plays a special role as the lightest baryon resonance. I will discuss recent progress using continuum QCD approaches to the study of nucleon and delta properties, with a focus on insights gained by the calculation (and measurement) of their electromagnetic form factors.

  12. Pluviometric anomaly in the Llobregat Delta

    Directory of Open Access Journals (Sweden)

    J. Mazón

    2009-01-01

    Full Text Available The data from surface automatic weather stations show that in the area of the Llobregat delta (northeast of the Iberian Peninsula we can observe greater precipitation than in nearby inland areas (Ordal, Collserola, Garraf, than on the other side of a massif located on the coast (Garraf and than on the northern coast. This distribution of the precipitation could be explained by the formation of a nocturnal surface cold front in the Llobregat delta. In order to analyze in-depth the physical mechanisms that can influence the formation of this front (topography, sea and drainage winds, two rain episodes in the area were simulated with the MM5 mesoscale model, reproducing satisfactorily the physical mechanisms that favor the appearance of the front.

  13. On regularizations of the Dirac delta distribution

    Science.gov (United States)

    Hosseini, Bamdad; Nigam, Nilima; Stockie, John M.

    2016-01-01

    In this article we consider regularizations of the Dirac delta distribution with applications to prototypical elliptic and hyperbolic partial differential equations (PDEs). We study the convergence of a sequence of distributions SH to a singular term S as a parameter H (associated with the support size of SH) shrinks to zero. We characterize this convergence in both the weak-* topology of distributions and a weighted Sobolev norm. These notions motivate a framework for constructing regularizations of the delta distribution that includes a large class of existing methods in the literature. This framework allows different regularizations to be compared. The convergence of solutions of PDEs with these regularized source terms is then studied in various topologies such as pointwise convergence on a deleted neighborhood and weighted Sobolev norms. We also examine the lack of symmetry in tensor product regularizations and effects of dissipative error in hyperbolic problems.

  14. Matrix multiplication on the Intel Touchstone Delta

    Energy Technology Data Exchange (ETDEWEB)

    Huss-Lederman, S.; Jacobson, E.M.; Tsao, A. [Supercomputing Research Center, Bowie, MD (United States); Zhang, G. [CONVEX Computer Corp., Richardson, TX (United States)

    1993-12-31

    Matrix multiplication is a key primitive in block matrix algorithms such as those found in LAPACK. We present results from our study of matrix multiplication algorithms on the Intel Touchstone Delta, a distributed memory message-passing architecture with a two-dimensional mesh topology. We obtain an implementation that uses communication primitives highly suited to the Delta and exploits the single node assembly-coded matrix multiplication. Our algorithm is completely general, able to deal with arbitrary mesh aspect ratios and matrix dimensions, and has achieved parallel efficiency of 86% with overall peak performance in excess of 8 Gflops on 256 nodes for an 8800 {times} 8800 matrix. We describe our algorithm design and implementation, and present performance results that demonstrate scalability and robust behavior over varying mesh topologies.

  15. Clostridium perfringens Delta-Toxin Induces Rapid Cell Necrosis.

    Directory of Open Access Journals (Sweden)

    Soshi Seike

    Full Text Available Clostridium perfringens delta-toxin is a β-pore-forming toxin and a putative pathogenic agent of C. perfringens types B and C. However, the mechanism of cytotoxicity of delta-toxin remains unclear. Here, we investigated the mechanisms of cell death induced by delta-toxin in five cell lines (A549, A431, MDCK, Vero, and Caco-2. All cell lines were susceptible to delta-toxin. The toxin caused rapid ATP depletion and swelling of the cells. Delta-toxin bound and formed oligomers predominantly in plasma membrane lipid rafts. Destruction of the lipid rafts with methyl β-cyclodextrin inhibited delta-toxin-induced cytotoxicity and ATP depletion. Delta-toxin caused the release of carboxyfluorescein from sphingomyelin-cholesterol liposomes and formed oligomers; toxin binding to the liposomes declined with decreasing cholesterol content in the liposomes. Flow cytometric assays with annexin V and propidium iodide revealed that delta-toxin treatment induced an elevation in the population of annexin V-negative and propidium iodide-positive cells. Delta-toxin did not cause the fragmentation of DNA or caspase-3 activation. Furthermore, delta-toxin caused damage to mitochondrial membrane permeability and cytochrome c release. In the present study, we demonstrate that delta-toxin produces cytotoxic activity through necrosis.

  16. Strain rate dependence of the flow stress and work hardening of single crystals of Ni{sub 3}(Al,Hf)B

    Energy Technology Data Exchange (ETDEWEB)

    Ezz, S.S.; Sun, Y.Q.; Hirsch, P.B. [Univ. of Oxford (United Kingdom). Dept. of Materials

    1995-07-01

    The strain rate sensitivity {beta} of the flow stress {tau} is associated with work hardening and {beta} = ({delta}{tau}/{delta}ln {dot {var_epsilon}}) is proportional to the work hardening increment {tau}{sub h} = {tau} {minus} {tau}{sub y}, where {tau}{sub y} is the strain rate independent yield stress. The temperature dependence of {beta}/{tau}{sub h} reflects changes in the rate controlling mechanism. At intermediate and high temperatures, the hardening correlates with the density of [{bar 1}01] dislocations on (010). The nature of the local obstacles at room temperature is not established.

  17. Elastic and transition form factors of the \\Delta(1232)

    CERN Document Server

    Segovia, Jorge; Cloët, Ian C; Roberts, Craig D; Schmidt, Sebastian M; Wan, Shaolong

    2013-01-01

    Predictions obtained with a confining, symmetry-preserving treatment of a vector-vector contact interaction at leading-order in a widely used truncation of QCD's Dyson-Schwinger equations are presented for \\Delta and \\Omega baryon elastic form factors and the \\gamma N -> \\Delta transition form factors. This simple framework produces results that are practically indistinguishable from the best otherwise available, an outcome which highlights that the key to describing many features of baryons and unifying them with the properties of mesons is a veracious expression of dynamical chiral symmetry breaking in the hadron bound-state problem. The following specific results are of particular interest. The \\Delta elastic form factors are very sensitive to m_\\Delta. Hence, given that the parameters which define extant simulations of lattice-regularised QCD produce \\Delta-resonance masses that are very large, the form factors obtained therewith are a poor guide to properties of the \\Delta(1232). Considering the \\Delta-b...

  18. [Quantitative relationship between molecular structure of polychlorinated biphenyls (PCBs) and enthalpy change (deltaH), entropy change (deltaS') in chromatographic process].

    Science.gov (United States)

    Zhang, Qing; Dai, Chaozheng

    2005-09-01

    The relationship between the rule of chromatographic retention value and molecular structure is an important part in the research of chromatographic thermodynamics. The topological index structural parameter JG and the topological index adjoining parameter LJ are put forward. Parameter J(G) describes the correlation of quantity and position of chlorine atoms in polychlorinated biphenyl (PCB) molecules. Parameter L(J) describes the ortho-position correlation of chlorine atoms in PCB molecules. The relational expression between the PCB molecular structures and their enthalpy change (deltaH), entropy change (deltaS') in chromatographic process was discovered. The values of enthalpy change and entropy change for about 140 kinds of polychlorinated biphenyls in chromatographic process on three stationary phases, DB-1, DB-5 and DB-1701, were determined. In comparison with deltaH and deltaS' of the experimental data those calculated from the relational expression had the average relative deviations for deltaH and deltaS' are 0.56% -0.97% and 0.55% - 1.06%, respectively.

  19. Performance evaluation of photonic Sigma Delta ADCS

    OpenAIRE

    Tan, Yean Wee

    2010-01-01

    Approved for public release; distribution is unlimited The integration of photonic and electronic components to realize a photonic sigma delta ADC is considered in this thesis. The integration process was broken up into steps. First, the performance of a pair of dual-port Mach-Zehnder interferometers (MZI) modulating a train of narrow high-speed laser pulses from a mode-locked laser was investigated. Various parameters like the half-wave voltage (V) and insertion loss were verified. Nex...

  20. Delta Greenbriar - Atlanta – (EE. UU.

    Directory of Open Access Journals (Sweden)

    Heery, George

    1975-05-01

    Full Text Available «Delta Greenbriar» is a corporate centre for the Delta air line company. The complex comprises four buildings containing: 1 the installations for flight simulation; 2 the air training base; 3 the control centre for flights and communications; 4 the department for tickets and reservations. They consist of one of two storeys. The lower ones can be extended both horizontally as well as vertically, whereas the other ones can only be enlarged in horizontal direction. The unit has been designed like a university campus, with patios, inner gardens and exterior corridors which apart from connecting the various buildings with each other also provide a close contact between the office premises and the park.El «Delta Greenbriar» es un centro corporativo para la compañía de líneas aéreas Delta. El complejo está constituido por cuatro edificios, que alojan: 1 las instalaciones para la simulación de vuelo; 2 la base de entrenamiento aéreo; 3 el centro de control de vuelo y comunicaciones; 4 el departamento de reservas y venta de billetes. Constan de una o dos plantas, pudiéndose ampliar los más bajos tanto horizontal como verticalmente, mientras que los otros sólo pueden aumentarse en sentido horizontal. El conjunto se ha diseñado como un campus universitario, con patios, ajardinamiento interior y corredores exteriores que, además de enlazar los distintos edificios entre sí, ponen en estrecha relación los espacios de oficinas con el parque.

  1. Probing Delta structure with pion electromagnetic production

    CERN Document Server

    Yang, S N; Yang, Shin Nan

    2003-01-01

    The Dubna-Mainz-Taipei dynamical model for pion electromagnetic production, which can describe well the existing data from threshold up to 1 GeV photon lab energy, is presented and used to analyze the recent precision data in the $\\Delta$ region. We find that, within our model, the bare Delta is almost spherical while the physical Delta is oblate. The deformation is almost saturated by the pion cloud effects. We further find that up to Q^2 = 4.0 (GeV/c)^2, the extracted helicity amplitude A_{3/2} and A_{1/2} remain comparable with each other, implying that hadronic helicity is not conserved at this range of Q^2. The ratio E_{1+}/M_{1+} obtained show, starting from a small and negative value at the real photon point, a clear tendency to cross zero, and to become positive with increasing Q^2. This is a possible indication of a very slow approach toward the pQCD region. Finally, we find that the bare helicity amplitude A_{1/2} and S_{1/2}, but not A_{3/2}, starts exhibiting the scaling behavior at about Q^2 \\ge ...

  2. Evolution of Modern Yellow River Delta Coast

    Institute of Scientific and Technical Information of China (English)

    尹延鸿; 周永青; 丁东

    2004-01-01

    This paper deals with the development and evolution of modem Yellow River delta and the erosion or deposition rates of its different sections. In June, 1996,Yellow Rivers terminal course was artificially turned eastwards to empty into the sea and then the 11th lobe of the modern Yellow River delta began to form. This course change may mark the beginning of the 3rd subdelta formation. As a result of that, the Yellow River delta advances towards east by north with the 1st, 2nd and 3rd subdeltas arranged in succession. Coast zone in the deltaic area is divided into 7 different sections according to their different erosion or deposition rates: the relatively stable section from Dakou River to Shunjiang Stream, the weakly retreating section from Shun jiang Stream to the Tiaohe River mouth, the strongly retreating section from the Tiaohe River mouth to the station 106, the artificially stable section due to stone dam protection from the station 106 to Gudong Oilfield, the strong deposition section from Gudong Oilfield to Dawenliu Haipu, the weakly deposition section from Dawenliu Haipu to the Zimai Stream mouth, and the stable section from the Zimai Stream mouth to the Jiaolai River mouth. It is predicted that the erosion and deposition situations of the sections will nearly remain the same in 10 years, but the retreating and silting-up rates will tend to become slower gradually. Human activities have an evident influence on the changes of the coastline.

  3. GLOBAL CHARM OF THE CHANGJIANG RIVER DELTA

    Institute of Scientific and Technical Information of China (English)

    CHEN Shu-peng; ZHOU Cheng-hu; CHEN Qiu-xiao

    2003-01-01

    Based on the theory of geo-economy, under the new situation of global economy, information network and China's entry into WTO, also with the holding of APEC (in 2001) and the International Exposition in the near future, the Changjiang (Yangtze) River Delta is striding toward the spectacular international multi-polar situation and becomes one of core regions with high-speed development. Facing the ocean and world all along, leading the progressive tides of the age and scintillating the splendor of the nation, she does advance with time. Through a long period of irrigation projects construction and intensive operation of lands in previous agricultural society, the artificial wetland ecosystem with a positive cycle had ever been formed in this region. At present, environmental pollution and urban expansion resulted from post-industrialization are being rectified. The delta will be the paradigm of industrial and agricultural modernization along the sustainable development road. With the rapid development of urbanization,she has been one of the regions with the highest density population and high urbanization level. Taking the Changjiang River estuary and the Hangzhou Bay as two parts, she is continuously strengthening and adjusting her interiorstructure, expanding mothball space and constructing the oriental modern "logistics center" to link the whole world. The butterfly-style urban system of the Changjiang River Delta is flying, probably engendering earthshaking "butterfly effect".

  4. Delta: Data Reduction for Integrated Application Workflows.

    Energy Technology Data Exchange (ETDEWEB)

    Lofstead, Gerald Fredrick [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jean-Baptiste, Gregory [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Oldfield, Ron A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-06-01

    Integrated Application Workflows (IAWs) run multiple simulation workflow components con- currently on an HPC resource connecting these components using compute area resources and compensating for any performance or data processing rate mismatches. These IAWs require high frequency and high volume data transfers between compute nodes and staging area nodes during the lifetime of a large parallel computation. The available network band- width between the two areas may not be enough to efficiently support the data movement. As the processing power available to compute resources increases, the requirements for this data transfer will become more difficult to satisfy and perhaps will not be satisfiable at all since network capabilities are not expanding at a comparable rate. Furthermore, energy consumption in HPC environments is expected to grow by an order of magnitude as exas- cale systems become a reality. The energy cost of moving large amounts of data frequently will contribute to this issue. It is necessary to reduce the volume of data without reducing the quality of data when it is being processed and analyzed. Delta resolves the issue by addressing the lifetime data transfer operations. Delta removes subsequent identical copies of already transmitted data during transfers and restores those copies once the data has reached the destination. Delta is able to identify duplicated information and determine the most space efficient way to represent it. Initial tests show about 50% reduction in data movement while maintaining the same data quality and transmission frequency.

  5. Modelling repeatedly flaring delta-sunspots

    CERN Document Server

    Chatterjee, Piyali; Carlsson, Mats

    2016-01-01

    Active regions (AR) appearing on the surface of the Sun are classified into $\\alpha$, $\\beta$, $\\gamma$, and $\\delta$ by the rules of the Mount Wilson Observatory, California on the basis of their topological complexity. Amongst these, the $\\delta$-sunspots are known to be super-active and produce the most X-ray flares. Here, we present results from a simulation of the Sun by mimicking the upper layers and the corona, but starting at a more primitive stage than any earlier treatment. We find that this initial state consisting of only a thin sub-photospheric magnetic sheet breaks into multiple flux-tubes which evolve into a colliding-merging system of spots of opposite polarity upon surface emergence, similar to those often seen on the Sun. The simulation goes on to produce many exotic $\\delta$-sunspot associated phenomena: repeated flaring in the range of typical solar flare energy release and ejective helical flux ropes with embedded cool-dense plasma filaments resembling solar coronal mass ejections.

  6. Understanding delta-sigma data converters

    CERN Document Server

    Pavan, Shanti; Temes, Gabor C

    2017-01-01

    This new edition introduces novel analysis and design techniques for delta-sigma (ΔΣ) converters in physical and conceptual terms, and includes new chapters that explore developments in the field over the last decade. This book explains the principles and operation of delta-sigma analog-to-digital converters (ADCs) in physical and conceptual terms in accordance with the most recent developments in the field. The interest of ΔΣ converter designers has shifted significantly over the past decade, due to many new applications for data converters at the far ends of the frequency spectrum. Continuous-time delta-sigma A/D converters with GHz clocks, of both lowpass and bandpass types, are required for wireless applications. At the other extreme, multiplexed ADCs with very narrow (sometimes 10 Hz wide) signal bandwidths, but very high accuracy are needed in the interfaces of biomedical and environmental sensors. To reflect the changing eeds of designers, the second edition includes significant new material on bo...

  7. Adaptive Delta Management: cultural aspects of dealing with uncertainty

    Science.gov (United States)

    Timmermans, Jos; Haasnoot, Marjolijn; Hermans, Leon; Kwakkel, Jan

    2016-04-01

    Deltas are generally recognized as vulnerable to climate change and therefore a salient topic in adaptation science. Deltas are also highly dynamic systems viewed from physical (erosion, sedimentation, subsidence), social (demographic), economic (trade), infrastructures (transport, energy, metropolization) and cultural (multi-ethnic) perspectives. This multi-faceted dynamic character of delta areas warrants the emergence of a branch of applied adaptation science, Adaptive Delta Management, which explicitly focuses on climate adaptation of such highly dynamic and deeply uncertain systems. The application of Adaptive Delta Management in the Dutch Delta Program and its active international dissemination by Dutch professionals results in the rapid dissemination of Adaptive Delta Management to deltas worldwide. This global dissemination raises concerns among professionals in delta management on its applicability in deltas with cultural conditions and historical developments quite different from those found in the Netherlands and the United Kingdom where the practices now labelled as Adaptive Delta Management first emerged. This research develops an approach and gives a first analysis of the interaction between the characteristics of different approaches in Adaptive Delta Management and their alignment with the cultural conditions encountered in various delta's globally. In this analysis, first different management theories underlying approaches to Adaptive Delta Management as encountered in both scientific and professional publications are identified and characterized on three dimensions: The characteristics dimensions used are: orientation on today, orientation on the future, and decision making (Timmermans, 2015). The different underlying management theories encountered are policy analysis, strategic management, transition management, and adaptive management. These four management theories underlying different approaches in Adaptive Delta Management are connected to

  8. On the determination of low-energy constants for {delta}S=1 transitions

    Energy Technology Data Exchange (ETDEWEB)

    Giusti, L.; Pena, C. [European Organization for Nuclear Research, Geneva (Switzerland); Hernandez, P. [Dpto. Fisica Teorica and IFIC, Edificio Institutos Investigacion, Valencia (Spain); Laine, M. [Bielefeld Univ. (Germany). Fakultaet fuer Physik; Wennekers, J.; Wittig, H. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2005-10-01

    We present our preliminary results for three-point correlation functions involving the operators entering the {delta}S=1 effective Hamiltonian with an active charm quark, obtained using overlap fermions in the quenched approximation. This is the first computation carried out for valence quark masses small enough so as to permit a matching to Quenched Chiral Perturbation Theory in the {epsilon}-regime. The commonly observed large statistical fluctuations are tamed by means of low-mode averaging techniques, combined with restrictions to individual topological sectors. We also discuss the matching of the resulting hadronic matrix elements to the effective low-energy constants for {delta}S=1 transitions. This involves (a) finite-volume corrections which can be evaluated at NLO in Quenched Chiral Perturbation Theory, and (b) the short-distance renormalization of the relevant four-quark operators in discretizations based on the overlap operator. We discuss perturbative estimates for the renormalization factors and possible strategies for their non-perturbative evaluation. Our results can be used to isolate the long-distance contributions to the {delta}I=1/2 rule, coming from physics effects around the intrinsic QCD scale. (orig.)

  9. Structure and magnetoresistance of a Ni{sub 79.7}Fe{sub 14.0}Co{sub 2.8}Zr{sub 2.0}Cu{sub 1.5} thin film

    Energy Technology Data Exchange (ETDEWEB)

    Varyukhin, V. N.; Izotov, A. I.; Moroz, T. T., E-mail: ftimoroz@mail.ru; Shkuratov, B. E. [National Academy of Sciences of Ukraine, Galkin Institute for Physics and Engineering (Ukraine)

    2013-01-15

    The structure and magnetoresistance R of thin films based on Ni{sub 80}Fe{sub 20} permalloy doped with Co, Zr, and Cu have been examined by X-ray diffraction analysis and resistance measurement. The films have been obtained by ion plasma sputtering on oxidized silicon, fused quartz, and glass ceramic cold substrates. It has been shown that the structure of a film in the initial state is a mixture of solid solutions based on two phases: Ni(fcc) particles with a size of L Almost-Equal-To 8 nm and (Zr{sub 0.67}Ni{sub 0.22}O{sub 0.11}){gamma} particles with a size of L Almost-Equal-To 12 nm. The R(H) dependences on the strength and direction of the magnetic field H have been obtained at room temperature for film samples in the initial state and after isothermal annealing at 653 K for 1 h. According to R(H) dependences and X-ray diffraction analysis, films in the initial state are assumingly in a superparamagnetic state, whereas they exhibit ferromagnetic properties after isothermal annealing.

  10. Synthesis, characterization, and photoactivity of InTaO{sub 4} and In{sub 0.9}Ni{sub 0.1}TaO{sub 4} thin films prepared by electron evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Rico, V. J.; Frutos, F.; Yubero, F.; Espinos, J. P.; Gonzales-Elipe, A. R. [Instituto de Ciencia de Materiales de Sevilla, CSIC/Universidad de Sevilla, Avda. Americo Vespucio 49, 41092 Sevilla (Spain); Departamento de Fisica Aplicada I, Universidad de Sevilla, Avenida Reina Mercedes s/n, 41012 Sevilla (Spain); Instituto de Ciencia de Materiales de Sevilla, CSIC/Universidad de Sevilla, Avda. Americo Vespucio 49, 41092 Sevilla (Spain)

    2010-01-15

    InTaO{sub 4} and In{sub 0.9}Ni{sub 0.1}TaO{sub 4} thin films have been prepared by electron evaporation of successive layers of the single oxide components and posterior annealing at T>800 deg. C. The annealed thin films presented the monoclinic crystallographic structure typical of these mixed oxides. The electrical and optical behaviors of the films, assessed by C-V measurements, surface conductivity as a function of temperature, and UV-vis absorption spectroscopy, indicate that these oxides are wide band gap semiconductors with a variable dielectric constant depending on the annealing conditions. By reflection electron energy loss spectroscopy some electronic states have been found in the gap at an energy that is compatible with the activation energy deduced from the conductivity versus 1/T plots for these oxides. The photoactivity of these materials has been assessed by looking to the evolution of the wetting contact angle as a function of the irradiation time. All the films became superhydrophilic when irradiated with UV light, while the In{sub 0.9}Ni{sub 0.1}TaO{sub 4} thin films also presented a small partial decrease in wetting angle when irradiated with visible photons.

  11. Structural, microstructural and magnetic properties of amorphous/nanocrystalline Ni{sub 63}Fe{sub 13}Mo{sub 4}Nb{sub 20} powders prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Karimi, L., E-mail: leilakarimi@iauahvaz.ac.ir [Materials Science and Engineering Department, Islamic Azad University of Ahvaz, Ahvaz (Iran, Islamic Republic of); Shokrollahi, H. [Materials Science and Engineering Department, Shiraz University of Technology, 71555-313, Shiraz (Iran, Islamic Republic of)

    2011-06-09

    Highlights: > The amorphous/nanocrystalline Ni{sub 63}Fe{sub 13}Mo{sub 4}Nb{sub 20} magnetic powders were prepared by mechanical alloying. > The saturation magnetization decreases and the coercivity increases as a result of the electronic interactions and the grain size reduction. > The use of amorphous alloy is due to the lower magnetic losses and higher electrical resistivity compared with other magnetic material - Abstract: This paper focuses on the magnetic, structural and microstructural studies of amorphous/nanocrystalline Ni{sub 63}Fe{sub 13}Mo{sub 4}Nb{sub 20} powders prepared by mechanical alloying. The ball-milling of Ni, Fe, Mo and Nb powders leads to alloying the element powders, the nanocrystalline and an amorphization matrix with Mo element up to 120 h followed by the strain and thermal-induced nucleation of a single nanocrystalline Ni-based phase from the amorphous matrix at 190 h. The results showed that the saturation magnetization decreases as a result of the electronic interactions between magnetic and non-magnetic elements and finally increases by the partial crystallization of the amorphous matrix. The coercive force increases as the milling time increases and finally decreases due to sub-grains formation.

  12. Influence of milling time on the structural, microstructural and magnetic properties of mechanically alloyed Ni{sub 58}Fe{sub 12}Zr{sub 10}Hf{sub 10}B{sub 10} nanostructured/amorphous powders

    Energy Technology Data Exchange (ETDEWEB)

    Besmel, R., E-mail: r.besmel@iauahvaz.ac.ir [Materials Science and Engineering Department, Islamic Azad University Ahvaz Branch, Ahvaz (Iran, Islamic Republic of); Ghaffari, M. [School of Electrical and Electronic Engineering, Sensor and Actuator Laboratory II, BLK S2.1, B6-02, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Shokrollahi, H., E-mail: shokrollahi@sutech.ac.ir [Electroceramics Group, Materials Science and Engineering Department, Shiraz University of Technology, 71555-313, Shiraz (Iran, Islamic Republic of); Chitsazan, B.; Karimi, L. [Materials Science and Engineering Department, Islamic Azad University Ahvaz Branch, Ahvaz (Iran, Islamic Republic of)

    2011-11-15

    This paper investigates structural, microstructural and magnetic properties of amorphous/nanocrystalline Ni{sub 58}Fe{sub 12}Zr{sub 10}Hf{sub 10}B{sub 10} powders prepared by high energy milling. Ball milling of Ni, Fe, Zr, Hf and B leads to alloying of the element powders at 120 h. The results show that at 190 h the amorphous content is at the highest level and the grain size is about 2 nm. The magnetic measurements reveal that the coercivity and the saturation magnetization reach about 20 Oe and 30 emu/g at 190 h and become approximately 5 Oe and 40 emu/g after a suitable heat treatment, respectively. - Highlights: > We investigated the influence of milling time on the structural and magnetic properties of mechanically alloyed Ni{sub 58}Fe{sub 12}Zr{sub 10}Hf{sub 10}B{sub 10} nanostructured/amorphous powders. > Results showed that at 190 h the amorphous content is at the highest level and the grain size is about 2 nm. > By obtaining the amorphous structure and applying a suitable heat treatment the magnetic properties were improved.

  13. The e/a factor governing the formation and stability of (Zr{sub 76}Ni{sub 24}){sub 1-x}Al{sub x} bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.M.; Shek, C.H.; Qiang, J.B.; Wong, C.H.; Chen, W.R.; Dong, C

    2003-06-15

    In the present paper (Zr{sub 76}Ni{sub 24}){sub 1-x}Al{sub x} alloys were prepared to investigate the influence of e/a, electron number per atom, on their glass-forming abilities. The bulk metallic glasses (BMGs) obtained in this alloy series have an e/a span from 1.37 to 1.53. Their thermal stability increases with the e/a ratios. The largest thermal stability is found at Zr{sub 60}Al{sub 21}Ni{sub 19} with the highest possible e/a=1.53. These BMGs manifest negative temperature coefficients of resistivity and a nearly linear T-dependence of resistivity within the temperature span 80-293 K. The validity of the Nagel-Tauc conjecture, 2k{sub f}{approx}k{sub p} for the stabilities of these BMGs is discussed. The e/a-based rule is a promising way to locate glass-forming compositions in the Zr-based multi-component alloy systems.

  14. The effect of high temperature plastic deformation on the thermal stability and microstructure of Zr{sub 55}Cu{sub 30}Ni{sub 5}Al{sub 10} bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Liu, L. [State Key Lab of Die and Mould Technology, Huazhong University of Science and Technology, 430074 Wuhan (China)], E-Mail: lliu2000@public.wh.hb.cn; Chen, Q. [State Key Lab of Die and Mould Technology, Huazhong University of Science and Technology, 430074 Wuhan (China); Chan, K.C. [Department of Industrial and Systems Engineering, Hong Kong Polytechnic University, Hong Kong (China); Wang, J.F. [State Key Lab of Die and Mould Technology, Huazhong University of Science and Technology, 430074 Wuhan (China); Pang, G.K.H. [Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong (China)

    2007-03-25

    The plastic deformation of Zr{sub 55}Cu{sub 30}Al{sub 10}Ni{sub 5} (numbers indicate at.%) bulk metallic glass (BMG) was conducted in the supercooled liquid region under uniaxial tension with various strain rates ranging from 8.3 x 10{sup -4} to 2 x 10{sup -2} s{sup -1}. It was found that the deformation behavior of the BMG is strongly dependent on strain rate. Thermal and structural investigations revealed that the plastic deformation reduced the thermal stability of Zr{sub 55}Cu{sub 30}Al{sub 10}Ni{sub 5} BMG and promoted crystallization or reordering of the amorphous structure. To clarify the correlation between strain and structure of the BMG, the sample that was deformed at a high strain rate and exhibited significant necking was selected for a detailed investigation of its structure in different parts (e.g., the tip, middle and end parts) by conventional and high-resolution transmission electron microscopy. It was found that a band crystalline structure with a strongly crystallographic orientation was formed at the tip part, while inhomogeneous nanocrystallization occurred in the middle parts, and the amorphous structure remained almost unchanged in the end part. The different structures observed in different parts of the deformed sample are attributed to the inhomogeneous deformation of the BMG at high strain rates.

  15. High-magnetic-field phase transitions and H–T phase diagram of the Kagome-staircase compound Ni{sub 3}V{sub 2}O{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Z.Q.; Yang, M.; Wang, H.W.; Guo, Q.; Liu, Y.J. [Wuhan National High Magnetic Field Center (WHMFC), Huazhong University of Science and Technology, Wuhan 430074 (China); Han, X.T., E-mail: xthan@mail.hust.edu.cn [Wuhan National High Magnetic Field Center (WHMFC), Huazhong University of Science and Technology, Wuhan 430074 (China); Han, Y.B. [Wuhan National High Magnetic Field Center (WHMFC), Huazhong University of Science and Technology, Wuhan 430074 (China); Wang, J.F., E-mail: jfwang@mail.hust.edu.cn [Wuhan National High Magnetic Field Center (WHMFC), Huazhong University of Science and Technology, Wuhan 430074 (China); He, Z.Z. [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Kindo, K. [The Institute for Solid State Physics (ISSP), The University of Tokyo, Chiba 277-8581 (Japan)

    2015-05-15

    High-field magnetization and specific heat of the Kagome staircase compound Ni{sub 3}V{sub 2}O{sub 8} have been measured in magnetic fields H applied along the b and the c axes. The magnetization data shows magnetic transitions above 10 T for H//b; while no additional transition is probed for H//c. The resulting H–T phase diagram for H//b is extended to magnetic fields higher than previously reported and explores a different high-field phase. The experimental data of the magnetization and the specific heat also suggest the existence of multiple phases inside this high-field phase. These results indicate that this compound is a more complex spin system than previously studied. - Highlights: • Magnetic phase boundaries of Ni{sub 3}V{sub 2}O{sub 8} are extended to magnetic fields higher than previously reported. • A complete H–T phase diagram for H//b is constructed. • A novel high-field phase is explored.

  16. Size dependent magnetic and magneto-optical properties of Ni{sub 0.2}Zn{sub 0.8}Fe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Li, Oksana A., E-mail: log85@mail.ru [Department of Applied Physics, National Pingtung University, Pingtung 90003, Taiwan (China); Siberian Federal University, Krasnoyarsk 660041 (Russian Federation); Lin, Chun-Rong, E-mail: crlin@mail.nptu.edu.tw [Department of Applied Physics, National Pingtung University, Pingtung 90003, Taiwan (China); Chen, Hung-Yi; Hsu, Hua-Shu [Department of Applied Physics, National Pingtung University, Pingtung 90003, Taiwan (China); Shih, Kun-Yauh [Department of Applied Chemistry, National Pingtung University, Pingtung 90003, Taiwan (China); Edelman, Irina S. [L.V. Kirensky Institute of Physics, SB RAS, Krasnoyarsk 660036 (Russian Federation); Wu, Kai-Wun; Tseng, Yaw-Teng [Department of Applied Physics, National Pingtung University, Pingtung 90003, Taiwan (China); Ovchinnikov, Sergey G. [Siberian Federal University, Krasnoyarsk 660041 (Russian Federation); L.V. Kirensky Institute of Physics, SB RAS, Krasnoyarsk 660036 (Russian Federation); Lee, Jiann-Shing [Department of Applied Physics, National Pingtung University, Pingtung 90003, Taiwan (China)

    2016-06-15

    Ni{sub 0.2}Zn{sub 0.8}Fe{sub 2}O{sub 4} spinel nanoparticles have been synthesized by combustion method. Average particles size varies from 15.5 to 50.0 nm depending on annealing temperature. Correlations between particles size and magnetic and magneto-optical properties are investigated. Magnetization dependences on temperature and external magnetic field correspond to the sum of paramagnetic and superparamagnetic response. Critical size of single-domain transition is found to be 15.9 nm. Magnetic circular dichroism (MCD) studies of nickel zinc spinel are presented here for the first time. The features in magnetic circular dichroism spectrum are assigned to the one-ion d–d transitions in Fe{sup 3+} and Ni{sup 2+} ions, as well to the intersublattice and intervalence charge transfer transitions. The MCD spectrum rearrangement was revealed with the change of the nanoparticles size. - Highlights: • Ni{sub 0.2}Zn{sub 0.8}Fe{sub 2}O{sub 4} nanoparticles were synthesized by combustion method. • Structure and magnetic properties are studied. • Magnetic circular dichroism (MCD) of nickel zinc spinel was measured for the first time. • The MCD spectrum rearrangement was revealed with the change of the nanoparticles size.

  17. Electrochemical properties of Ti{sub 49}Zr{sub 26}Ni{sub 25−x}Pd{sub x} (x = 0–6) quasicrystal electrodes produced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Ariga, Youhei [Shibaura Institute of Technology, Department of Engineering Science and Mechanics, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548 (Japan); Takasaki, Akito, E-mail: takasaki@sic.shibaura-it.ac.jp [Shibaura Institute of Technology, Department of Engineering Science and Mechanics, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548 (Japan); Kimijima, Tsubasa [Shibaura Institute of Technology, Department of Engineering Science and Mechanics, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548 (Japan); Świerczek, Konrad [AGH University of Science and Technology, Faculty of Energy and Fuels, al. Mickiewicza, 30, 30-059 Kraków (Poland)

    2015-10-05

    Highlights: • Formation of icosahedral quasicrystal phase in Ti–Zr–Ni–Pd powders after MA and annealing. • The maximum discharge capacity achieved was 220 mA h/g. • The powder surface turned rough and exhibited various finer pores after hydrogen cycling. - Abstract: Elemental powders consisted of chemical composition of Ti{sub 49}Zr{sub 26}Ni{sub 25−x}Pd{sub x} (x = 0, 1, 3, 6) were mechanically alloyed and annealed subsequently, and the discharge performance of the electrodes was measured by a three-electrode cell at room temperature. The annealing after mechanical alloying caused a formation of the icosahedral quasicrystal phase with a Ti{sub 2}Ni type crystal, C14 Laves and α-Ti/Zr phases. The quasilattice constant increased with increasing amount of Pd substituted for Ni up to 3 at.% due to difference in atomic radius between Pd and Ni. The maximum discharge capacity achieved was about 220 mA h/g from a (Ti{sub 49}Zr{sub 26}Ni{sub 22}Pd{sub 3}) electrode at the first discharge process.

  18. Milling time and BPR dependence on permeability and losses of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} synthesized via mechanical alloying process

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, Ismayadi, E-mail: kayzen@gmail.co [Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Hashim, Mansor; Amin Matori, Khamirul [Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Physics Department, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Alias, Rosidah [Telekom Research and Development Sdn. Bhd., Telekom Research and Development Innovation Centre, Lingkaran Teknokrat Timur, 63000 Cyberjaya, Selangor (Malaysia); Hassan, Jumiah [Physics Department, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2011-06-15

    Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} has been synthesized using mechanical alloying method with two variables (milling time and ball-to-powder weight ratio (BPR)) were varied in order to study its effect on the magnetic properties of the material. The effects of these two variables were studied using XRD, SEM, TEM and later by impedance analyzer with the frequency range from 1 MHz to 1.8 GHz. The results obtained however show that there are no significant trends to relate the milling time and BPR with the permeability and losses of the material studied. After being sintered at 1150 {sup o}C, all the effects of alloying process seem to diminish. - Research highlights: We studied the effects of BPR and milling time on permeability of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}. The effects were studied using XRD, SEM, TEM and impedance analyzer. No relationship between the milling time and BPR with the permeability and losses. The alloying effects are eliminated after sintering. The magnetic properties of these samples are influenced by the sintering process.

  19. Correlation between phonon anomaly along [211] and the Fermi surface nesting features with associated electron-phonon interactions in Ni{sub 2}FeGa: A first principles study

    Energy Technology Data Exchange (ETDEWEB)

    Chabungbam, Satyananda; Sahariah, Munima B., E-mail: munima@iasst.gov.in

    2015-10-25

    First principles calculation reaffirms the presence of phonon anomaly along [211] direction in Ni{sub 2}FeGa shape memory alloy supporting the experimental findings of J. Q. Li et al. Fermi surface scans have been performed in both austenite and martensite phase to see the possible Fermi nesting features in this alloy. The magnitude of observed Fermi surface nesting vectors in (211) plane exactly match the phonon anomaly wavevectors along [211] direction. Electron-phonon calculation in the austenite phase shows that there is significant electron-phonon coupling in this alloy which might arise out of the lattice coupling between lower acoustic modes and higher optical modes combined with the observed strong Fermi nesting features in the system. - Highlights: • Transverse acoustic (TA{sub 2}) modes show anomaly along [211] direction in Ni{sub 2}FeGa. • The phonon anomaly wavevector has been correlated with the Fermi nesting vectors. • Electron-phonon coupling calculation shows significant coupling in this system. • Max. el-ph coupling occurs in transition frequencies from acoustic to optical modes.

  20. Effect of vanadium substitution for zirconium on the glass forming ability and mechanical properties of a Zr{sub 65}Cu{sub 17.5}Ni{sub 10}Al{sub 7.5} bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Khademian, Nima, E-mail: nkhademian@gmail.com [Department of Mechanics, Islamshahr Branch, Islamic Azad University (IAU), Tehran (Iran, Islamic Republic of); Gholamipour, Reza [Iranian Research Organization for Science and Technology (IROST), Tehran (Iran, Islamic Republic of); Shahri, Farzad; Tamizifar, Morteza [Faculty of Engineering and High-Tech., Iran University of Industries and Mines (IUIM), Tehran (Iran, Islamic Republic of)

    2013-01-05

    Highlights: Black-Right-Pointing-Pointer The addition of V is effective for a decrease in GFA of Zr-based BMGs. Black-Right-Pointing-Pointer Mechanical properties of Zr-based BMGs are enhanced largely due to V addition. Black-Right-Pointing-Pointer Correlations among the elastic moduli, fracture strength, Vicker's hardness and glass transition for Zr-based BMGs. Black-Right-Pointing-Pointer Critical resolved shear stress ({tau}) of the Zr{sub 65-x}Cu{sub 17.5}Ni{sub 10}Al{sub 7.5}V{sub x} alloys decreases with the increase of V content. - Abstract: Effect of vanadium on the thermal and mechanical properties of the Zr{sub 65}Cu{sub 17.5}Ni{sub 10}Al{sub 7.5} bulk metallic glass has been studied. The vanadium substitution for zirconium in the bulk metallic glass leads to the decrease of the glass forming ability in constant cooling rate; as well as co-precipitation of Zr{sub 2}Ni and Zr{sub 2}Cu crystalline phases in amorphous matrix. The size of the crystallites are about 20-50 nm in amorphous matrix and they act as a barrier against of rapid propagation of shear bands. In fact, the nanocrystalline phases in amorphous matrix cause the increase of the strain and the quasi-static compression strength about 58% and 20%, respectively.

  1. Analysis, testing, and evaluation of faulted and unfaulted Wye, Delta, and open Delta connected electromechanical actuators

    Science.gov (United States)

    Nehl, T. W.; Demerdash, N. A.

    1983-07-01

    Mathematical models capable of simulating the transient, steady state, and faulted performance characteristics of various brushless dc machine-PSA (power switching assembly) configurations were developed. These systems are intended for possible future use as primemovers in EMAs (electromechanical actuators) for flight control applications. These machine-PSA configurations include wye, delta, and open-delta connected systems. The research performed under this contract was initially broken down into the following six tasks: development of mathematical models for various machine-PSA configurations; experimental validation of the model for failure modes; experimental validation of the mathematical model for shorted turn-failure modes; tradeoff study; and documentation of results and methodology.

  2. Electromagnetic attenuation analysis of Ni{sub 0.4}Zn{sub 0.6}Fe{sub 2O4} obtained by citrate precursor method; Analise da atenuacao de radiacao eletromagnetica de Ni{sub 0.4}Zn{sub 0.6}Fe{sub 2O4} obtido pelo metodo de citrato precursor

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, K. [Centro Tecnico Aeroespacial (CTA-IAE), Sao Jose dos Campos, SP (Brazil). Inst. de Atividades Espaciais. Div. Materiais; Moura, A.E.G.; Nasar, R.S.; Nasar, M.C. [Universidade Federal do Rio Grande do Norte (UFRN), Natal (Brazil). Dept. de Quimica; Pereira, J.J. [Universidade de Taubate, SP (Brazil)

    2010-07-01

    In this work, two types of synthesized Ni{sub 0,4}Zn{sub 0,6}Fe{sub 2}O{sub 4} by citrate precursor method. The first type was calcined at 350 deg C for 3.5 h, and the second, after calcination, it was subjected to heat treatment at 600 deg C for 2h in argon atmosphere. Both types were analyzed by X-ray diffraction (XRD) and equipment waveguide. The data were investigated by Rietveld refinement method and showed the NiZn ferrite phase with crystallite size of 12.2 +- 0.1 nm (350 deg C) and 166.7 +- 3.6 nm (600 deg C). The heat treatment also influenced the values of electric permittivity and magnetic permeability, and attenuation of electromagnetic radiation in the frequency range in microwave (8-12 GHz). The sample treated attenuates more and allows its application with thinner, making it attractive its use as absorber material in this frequency range. (author)

  3. Evaluation of the structure and microstructure of Ni{sub x}Mg{sub 1-x}O oxides obtained by co-precipitation; Evaluacion de la estructura y microestructura de oxidos de Ni{sub x}Mg{sub 1-x}O obtenidos por co-precipitacion

    Energy Technology Data Exchange (ETDEWEB)

    Martinez L, G.; Kryshtab, T. [IPN, Escuela Superior de Fisica y Matematicas, Departamento de Fisica, Av. Instituto Politecnico Nacional s/n, Edif. 9, 07738 Mexico D. F. (Mexico); Hesiquio G, M. [IPN, Escuela Superior de Ingenieria Quimica e Industrias Extractivas, Av. Instituto Politecnico Nacional s/n, Edif. 6, 07738 Mexico D. F. (Mexico); Kryvko, A., E-mail: marloz7@yahoo.com.mx [IPN, Escuela Superior de Ingenieria Mecanica y Electrica, Departamento de Sistemas, Av. Instituto Politecnico Nacional s/n, Edif. Z-4, 07738 Mexico D. F. (Mexico)

    2013-06-01

    Ni{sub x}Mg{sub 1-x}O oxides were prepared by thermal treatment at temperatures of 400, 600 and 800 C from a hydrotalcite-like precursor obtained by co-precipitation at constant ph. The oxides obtained were characterized by X-ray diffraction methods. From the obtained results we concluded that the oxides calcined at temperatures of 400, and 600 C are unstable that means that there exists the effect of memory and with a time they return to the precursor. Presence of Ni in Mg oxide provides stability of the compounds thermally treated at 800 C. In order to analyze the structure and microstructure, the reflections 111, 200 and 220 were used. The positions of the maxima of the diffraction peaks are shifted with respect to the simulated ones for Mg O and Ni O. This result reveals that in solid solutions studied compressive strains or vacation are present. The parameters of the microstructure (coherent domain size and micro deformations) were evaluated. The coherent domain size was found to be in the range of 8 - 10 nm and the presence of residual strains of micro deformation can be associated with the existence of extended defects. (Author)

  4. Crystal structures and magnetic properties of iron (III)-based phosphates: Na{sub 4}NiFe(PO{sub 4}){sub 3} and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Essehli, Rachid, E-mail: rachid_essehli@yahoo.fr [Laboratory of Mineral Solid and Analytical Chemistry ' LCSMA' , Department of Chemistry, Faculty of Sciences, University Mohamed I, Po. Box 717, 60000 Oujda (Morocco); Bali, Brahim El [Laboratory of Mineral Solid and Analytical Chemistry ' LCSMA' , Department of Chemistry, Faculty of Sciences, University Mohamed I, Po. Box 717, 60000 Oujda (Morocco); Benmokhtar, Said [LCMS, Laboratoire de Chimie des Materiaux Solides, Departement de chimie, Faculte des Sciences Ben M' SIK, Casablanca (Morocco); Bouziane, Khalid [Physics Department, College of Science, Sultan Qaboos University, PO Box 36, Postal Code 123 Al Khod, Sultanate of Oman (Oman); Manoun, Bouchaib [Laboratoire de Physico-Chimie des Materiaux, Departement de Chimie, FST Errachidia, University Moulay Ismail, B.P. 509 Boutalamine, Errachidia (Morocco); Abdalslam, Mouner Ahmed [Materials Science, Technical University Darmstadt, Darmstadt (Germany); Ehrenberg, Helmut [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany)

    2011-01-28

    Graphical abstract: A perspective view of the Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3} structure along the [0 0 1] direction. Both compounds seem to exibit antiferromagnetic interactions between magnetic entities at low temperature. Display Omitted Research highlights: > Nasicon and Alluaudite compounds, Iron(III)-based phosphates, Crystal structures of Na{sub 4}NiFe(PO{sub 4}){sub 3} and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3}. > Magnetism behaviours of Na{sub 4}NiFe(PO{sub 4}){sub 3} and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3}. > Antiferromagnetism interactions. > Mossbauer spectroscopy. - Abstract: Crystal structures from two new phosphates Na{sub 4}NiFe(PO{sub 4}){sub 3} (I) and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3} (II) have been determined by single crystal X-ray diffraction analysis. Compound (I) crystallizes in a rhombohedral system (S. G: R-3c, Z = 6, a = 8.7350(9) A, c = 21.643(4) A, R{sub 1} = 0.041, wR{sub 2}=0.120). Compound (II) crystallizes in a monoclinic system (S. G: C2/c, Z = 4, a = 11.729(7) A, b = 12.433(5) A, c = 6.431(2) A, {beta} = 113.66(4){sup o}, R{sub 1} = 0.043, wR{sub 2}=0.111). The three-dimensional structure of (I) is closely related to the Nasicon structural type, consisting of corner sharing [(Ni/Fe)O{sub 6}] octahedra and [PO{sub 4}] tetrahedra forming [NiFe(PO{sub 4}){sub 3}]{sup 4+} units which align in chains along the c-axis. The Na{sup +} cations fill up trigonal antiprismatic sites within these chains. The crystal structure of (II) belongs to the alluaudite type. Its open framework results from [Ni{sub 2}O{sub 10}] units of edge-sharing [NiO{sub 6}] octahedra, which alternate with [FeO{sub 6}] octahedra that form infinite chains. Coordination of these chains yields two distinct tunnels in which site Na{sup +}. The magnetization data of compound (I) reveal antiferromagnetic (AFM) interactions by the onset of deviations from a Curie-Weiss behaviour at low temperature as confirmed by Moessbauer measurements performed at 4.2 K. The

  5. Tidal river dynamics: Implications for deltas

    Science.gov (United States)

    Hoitink, A. J. F.; Jay, D. A.

    2016-03-01

    Tidal rivers are a vital and little studied nexus between physical oceanography and hydrology. It is only in the last few decades that substantial research efforts have been focused on the interactions of river discharge with tidal waves and storm surges into regions beyond the limit of salinity intrusion, a realm that can extend inland hundreds of kilometers. One key phenomenon resulting from this interaction is the emergence of large fortnightly tides, which are forced long waves with amplitudes that may increase beyond the point where astronomical tides have become extinct. These can be larger than the linear tide itself at more landward locations, and they greatly influence tidal river water levels and wetland inundation. Exploration of the spectral redistribution and attenuation of tidal energy in rivers has led to new appreciation of a wide range of consequences for fluvial and coastal sedimentology, delta evolution, wetland conservation, and salinity intrusion under the influence of sea level rise and delta subsidence. Modern research aims at unifying traditional harmonic tidal analysis, nonparametric regression techniques, and the existing understanding of tidal hydrodynamics to better predict and model tidal river dynamics both in single-thread channels and in branching channel networks. In this context, this review summarizes results from field observations and modeling studies set in tidal river environments as diverse as the Amazon in Brazil, the Columbia, Fraser and Saint Lawrence in North America, the Yangtze and Pearl in China, and the Berau and Mahakam in Indonesia. A description of state-of-the-art methods for a comprehensive analysis of water levels, wave propagation, discharges, and inundation extent in tidal rivers is provided. Implications for lowland river deltas are also discussed in terms of sedimentary deposits, channel bifurcation, avulsion, and salinity intrusion, addressing contemporary research challenges.

  6. THE RURAL TOURISM IN DANUBE DELTA

    Directory of Open Access Journals (Sweden)

    Ionica SOARE

    2014-06-01

    Full Text Available Purpose - the purpose of this paper is to evaluate the rural areas has market size and forecast its development as an economic activity. The present paper aims at analyzing the rural areas has in Danube Delta. In an enviable BAs which have responsibility for their particular isolated, such as the Danube Delta and the Danube that used, fishing and rural areas has the main activities that provide jobs and income sources for local populations. Design/methodology/approach - A survey was administered to customers’ rural hostel accommodation in Danube Delta. Descriptive statistics method was mainly adopted to calculate the mean with standard deviation of entry assumes variable, and to examine the different levels of consumers' awareness. The index values of product familiarity, the ratio between entries assumes product's familiarity value and the average value. Findings - the research results show hash has rural consumers have different perception and accomplished through behaviour. The information channels of brand hash mainly from friends, relatives and neighbours, so word of mouth spreading is very important for a brand. Women show a higher sensitivity in health and are currently operating the propensity than referred to follow the recommendations for nutrition. Research limitations/implications - This item is intended to synthesize developments and challenges," on June 13th rural market growth has. The results of this paper should be considered tentatively until has also features replicated by larger has rural consumers. Originality/value - members of rural areas has consumer's behavior would improve marketing and the development of rural areas has products, in order to reduce consumer confusion.

  7. Delta Shell: Integrated Modeling by Example

    Science.gov (United States)

    Donchyts, G.; Jagers, B.; Baart, F.; Geer, P. V.

    2011-12-01

    We present the integrated modeling environment Delta Shell. It supports the full workflow of integrated environmental modeling: setup, configuration, simulation, analysis and reporting of results. Many components of the environment can be reused independently, allowing development of scientific, geospatial and other applications focused on data analysis, editing, visualization and storage. One of the unique features is that the Delta Shell environment integrates models from many different fields, such as hydrodynamics, hydrology, morphology, ecology, water quality, geospatial and decision support systems. This integration is possible due to flexible general data types, lightweight model coupling framework, the plugin system and the inclusion of a number of high quality open source components. Here we will use the open source morphological model XBeach as an example showing how to integrate models into the Delta Shell environment. Integration of XBeach adds a graphical interface which can be used to make testing coastal safety for complicated coastal areas easier. By using this example, we give an overview of the modeling framework and its possibilities. To increase the usability, the model is integrated with a coastal profile data set covering the whole coast of the Netherlands. This gives the end user a system to easily use the model for scanning the safety of the Dutch coast. The reuse of the components of the environment individually or combined is encouraged. They are available as separate components and have minimal or no dependencies on other components. This includes libraries to work with scientific multidimensional data, geospatial data (in particular geospatial coverages: values of some quantities defined on a spatial domain), editors, visualisation of time-dependent data and the modeling framework (projects, data linking, workflow management, model integration). Most components and the XBeach example are available as open source.

  8. Upper-division student difficulties with the Dirac delta function

    CERN Document Server

    Wilcox, Bethany R

    2015-01-01

    The Dirac delta function is a standard mathematical tool that appears repeatedly in the undergraduate physics curriculum in multiple topical areas including electrostatics, and quantum mechanics. While Dirac delta functions are often introduced in order to simplify a problem mathematically, students still struggle to manipulate and interpret them. To characterize student difficulties with the delta function at the upper-division level, we examined students' responses to traditional exam questions and a standardized conceptual assessment, and conducted think-aloud interviews. Our analysis was guided by an analytical framework that focuses on how students activate, construct, execute, and reflect on the Dirac delta function in the context of problem solving in physics. Here, we focus on student difficulties using the delta function to express charge distributions in the context of junior-level electrostatics. Common challenges included: invoking the delta function spontaneously, translating a description of a c...

  9. Compositeness of the Delta(1232) resonance in pi N scattering

    CERN Document Server

    Sekihara, Takayasu; Yamagata-Sekihara, Junko; Yasui, Shigehiro

    2015-01-01

    We evaluate the $\\pi N$ compositeness of the $\\Delta (1232)$ resonance so as to clarify the internal structure of $\\Delta (1232)$ in terms of the $\\pi N$ component. Here the compositeness is defined as contributions from two-body wave functions to the normalization of the total wave function and is extracted from the $\\pi N$ scattering amplitude. In this study we employ the chiral unitary approach with the interaction up to the next-to-leading order plus a bare $\\Delta$ term in chiral perturbation theory and describe $\\Delta (1232)$ in an elastic $\\pi N$ scattering. Fitting the $\\pi N$ scattering amplitude to the solution of the partial wave analysis, we obtain a large real part of the $\\pi N$ compositeness for $\\Delta (1232)$ comparable to unity and non-negligible imaginary part as well, with which we reconfirm the result in the previous study on the $\\pi N$ compositeness for $\\Delta (1232)$.

  10. Monitoring the Polarimetric Variability of \\delta\\ Scorpii

    CERN Document Server

    Bednarski, Daniel

    2012-01-01

    The Be star \\delta\\ Scorpii is an interesting binary system, whose primary companion created a circumstellar disk after the periastron passage of the secondary in 2000, being since then classified as Be. This work presents the results of a long-term monitoring of this star in broad-band imaging polarimetry. The observational data collected since 2006 in the Pico dos Dias Observatory (Brazil) show a variable polarization that seems to correlate with the photometric light curve. From this data we see that the disk density varied since 2006; furthermore, the data suggests that there was some disturbance of the disk during the last periastron passage in July, 2011.

  11. Error Minimization of Polynomial Approximation of Delta

    Indian Academy of Sciences (India)

    Islam Sana; Sadiq Muhammad; Qureshi Muhammad Shahid

    2008-09-01

    The difference between Universal time (UT) and Dynamical time (TD), known as Delta ( ) is tabulated for the first day of each year in the Astronomical Almanac. During the last four centuries it is found that there are large differences between its values for two consecutive years. Polynomial approximations have been developed to obtain the values of for any time of a year for the period AD 1620 to AD 2000 (Meeu 2000) as no dynamical theories describe the variations in . In this work, a new set of polynomials for is obtained for the period AD 1620 to AD 2007 that is found to produce better results compared to previous attempts.

  12. International Financial Centers Delta in China

    Institute of Scientific and Technical Information of China (English)

    Emily Yu

    2009-01-01

    @@ It has called a lot of attention tnat China should build a pattern of International Financial Centers Delta:Make Beijing the centre of International Finance Management and Cooperation,working as the management and cooperation base and headquarter for China's participation in the iriternational Financial competition;Make Shanghai the centre of International Finance Market.working as the main battlefield of China's participation in international financial competition;Make Hong Kong the centre of Intemational Finance Open and Innovation,working as the frontier of China's participation in international financial competition.

  13. Hepatitis Delta Virus: A Peculiar Virus

    OpenAIRE

    Carolina Alves; Cristina Branco; Celso Cunha

    2013-01-01

    The hepatitis delta virus (HDV) is distributed worldwide and related to the most severe form of viral hepatitis. HDV is a satellite RNA virus dependent on hepatitis B surface antigens to assemble its envelope and thus form new virions and propagate infection. HDV has a small 1.7 Kb genome making it the smallest known human virus. This deceivingly simple virus has unique biological features and many aspects of its life cycle remain elusive. The present review endeavors to gather the available ...

  14. Stratigraphy and Evolution of Delta Channel Deposits, Jezero Crater, Mars

    Science.gov (United States)

    Goudge, T. A.; Mohrig, D.; Cardenas, B. T.; Hughes, C. M.; Fassett, C. I.

    2017-01-01

    The Jezero impact crater hosted an open-basin lake that was active during the valley network forming era on early Mars. This basin contains a well exposed delta deposit at the mouth of the western inlet valley. The fluvial stratigraphy of this deposit provides a record of the channels that built the delta over time. Here we describe observations of the stratigraphy of the channel deposits of the Jezero western delta to help reconstruct its evolution.

  15. Delta Doping High Purity CCDs and CMOS for LSST

    Science.gov (United States)

    Blacksberg, Jordana; Nikzad, Shouleh; Hoenk, Michael; Elliott, S. Tom; Bebek, Chris; Holland, Steve; Kolbe, Bill

    2006-01-01

    A viewgraph presentation describing delta doping high purity CCD's and CMOS for LSST is shown. The topics include: 1) Overview of JPL s versatile back-surface process for CCDs and CMOS; 2) Application to SNAP and ORION missions; 3) Delta doping as a back-surface electrode for fully depleted LBNL CCDs; 4) Delta doping high purity CCDs for SNAP and ORION; 5) JPL CMP thinning process development; and 6) Antireflection coating process development.

  16. Delta Plaza kohvik = The Delta Plaza Café / Margit Mutso

    Index Scriptorium Estoniae

    Mutso, Margit, 1966-

    2010-01-01

    Tallinnas Pärnu mnt. 141 asuva kohviku Delta Plaza sisekujundusest. Sisearhitektid Tiiu Truus ja Marja Viltrop (Stuudio Truus OÜ). Hoone arhitektid Jüri Okas ja Marika Lõoke (AB J. Okas & M. Lõoke). Žürii liikme Mait Summataveti arvamus kohvikust

  17. Global Heat Kernel Estimates for $\\Delta+\\Delta^{\\alpha/2}$ in Half-space-like domains

    CERN Document Server

    Chen, Zhen-Qing; Song, Renming

    2011-01-01

    Suppose that $d\\ge 1$ and $\\alpha\\in (0, 2)$. In this paper, by using probabilistic methods, we establish sharp two-sided pointwise estimates for the Dirichlet heat kernels of $\\{\\Delta+ a^\\alpha \\Delta^{\\alpha/2}; \\ a\\in (0, 1]\\}$ on half-space-like $C^{1, 1}$ domains in ${\\mathbb R}^d$ for all time $t>0$. The large time estimates for half-space-like domains are very different from those for bounded domains. Our estimates are uniform in $a \\in (0, 1]$ in the sense that the constants in the estimates are independent of $a\\in (0, 1]$. Thus it yields the Dirichlet heat kernel estimates for Brownian motion in half-space-like domains by taking $a\\to 0$. Integrating the heat kernel estimates in time $t$, we obtain uniform sharp two-sided estimates for the Green functions of $\\{\\Delta+ a^\\alpha \\Delta^{\\alpha/2}; \\ a\\in (0, 1]\\}$ in half-space-like $C^{1, 1}$ domains in ${\\mathbb R}^d$.

  18. Delta Plaza kohvik = The Delta Plaza Café / Margit Mutso

    Index Scriptorium Estoniae

    Mutso, Margit, 1966-

    2010-01-01

    Tallinnas Pärnu mnt. 141 asuva kohviku Delta Plaza sisekujundusest. Sisearhitektid Tiiu Truus ja Marja Viltrop (Stuudio Truus OÜ). Hoone arhitektid Jüri Okas ja Marika Lõoke (AB J. Okas & M. Lõoke). Žürii liikme Mait Summataveti arvamus kohvikust

  19. Hydraulic Geometry of a tidally influenced delta channel network: the Mahakam Delta, East Kalimantan, Indonesia

    Science.gov (United States)

    Sassi, M.; Hoitink, A.; de Brye, B.; Deleersnijder, E.

    2011-12-01

    Hydraulic Geometry (HG) refers to relations between the characteristics of channels in a network, including mean depth, width, and bed slope, and the discharge conveyed by the channel during bank-full conditions. HG relations are of fundamental importance to water management in channel networks, and they bear an interesting relation with geomorphology. River delta channel networks typically scale according to HG relations such as log(A) ~ p*log(Q), where A is channel cross sectional area, Q water discharge, and the exponent p is in between 0.8 and 1.2. In tidal networks, the tidal prism or tidal discharge can be used, instead of a discharge with a constant frequency of occurrence. In the tidal case, the exponent often shows the same range of variation. Tidal rivers are intrinsically complex, as tidal propagation is influenced by river discharge and vice-versa. Consequently, channel geometry in tidally influenced river deltas may show a mixed scaling behavior of river and tidal channel networks, as the channel forming discharges may both be of river and tidal origin. In tidal regions, the tidal dynamics may lead to a cyclic variation in water discharge distribution at bifurcations, readily affecting HG relations. We present results from the Mahakam delta channel network in Indonesia, a tide-river dominated delta which has been prograding for 60 km over the last 5000 years. Bathymetric surveys were conducted over the distributary network and connected tidal channels. Based on a geomorphic analysis of the present distributary network, we show that channel geometry of the fluvial distributary network scales with bifurcation order. The bifurcation order does not feature a clear relation with bifurcate branch length or bifurcate width ratio, as in the case of river deltas. HG relations of the area of selected cross-sections are well represented by the tidal prism or by the river discharge, when scaled with the bifurcation order. Numerical simulations show that river

  20. QCD corrections to inclusive $\\Delta S=1,2$ transitions

    OpenAIRE

    Jamin, Matthias

    1994-01-01

    The talk summarises a calculation of the two-point functions for $\\Delta S=1$ current-current and QCD-penguin operators, as well as for the $\\Delta S=2$ operator, at the next-to-leading order. The size of the gluonic corrections to current-current operators is large, providing a qualitative understanding of the observed enhancement in $\\Delta I=1/2$ transitions. In the $\\Delta S=2$ sector the QCD corrections are quite moderate ($\\approx -20\\%$). This work has been done in collaboration with A...

  1. [A study of 158 cases of acute delta hepatitis].

    Science.gov (United States)

    Castro, A; Buti, M; Esteban, R; Jardí, R; Allende, H; Roget, M; Rodríguez-Frías, F; Guardia, J

    1990-09-22

    We have prospectively studied 158 cases of acute hepatitis delta observed during the last 7 years in a general hospital. Among them 136 were male and 22 female. The mean age was 22.7 years with a range between 16 and 61 years. The epidemiologic factors were drug addiction by parenteral route in 145 cases (92%), sexual transmission in 5 (3%), post transfusional in 2 (1%) and unknown in 6 (4%). With respect to the delta type infection, 105 cases (66%) were coinfections with type B and delta, and 53 patients had a type delta superinfection (34%). The clinical course was a fulminant hepatitis in three cases (two cases of coinfection B and delta an one case of delta superinfection), and an acute benign hepatitis in 155 patients. The follow-up of 118 patients revealed that 96% of coinfections by type B and delta evolved to the chronicity showing findings of active chronic hepatitis or hepatic cirrhosis. It should be noted that in 4 cases of superinfection delta type (11%) the HBsAg was negative after several months of positivity. In these patients the level of transaminases normalized and the hepatic histology evidenced alterations of chronic active hepatitis (2 cases) and hepatic cirrhosis (2 cases) without identification of tissular delta antigen.

  2. A global analysis of human habitation on river deltas

    Science.gov (United States)

    Edmonds, Douglas; Caldwell, Rebecca; Baumgardner, Sarah; Paola, Chris; Roy, Samapriya; Nelson, Amelia; Nienhuis, Jaap

    2017-04-01

    River deltas are ideal sites for human habitation because of their fertile floodplains, easy access to the ocean, and abundant land. But anthropogenic and natural processes are causing deltas to sink, which increases the probability of coastal flooding and human exposure to risk. The full extent of the risk posed to humans is unclear because the number of people living on river deltas is unknown. Towards this end we mapped the locations and areas of all deltas in the world (n= 1813). Using Google Earth we identified all river mouths (≥ 50 m wide) on marine coastlines that are also connected to an upstream catchment. Rivers that split into two or more active or relict distributary channels, end in a depositional protrusion from the shoreline, or do both, are defined as deltas. The depositional protrusion and distributary channel network define the geomorphic area of each delta. We mark the position of the delta apex at the first bifurcation, or for a single channel delta at the intersection of the regional shoreline and the main channel. We mark three lateral extents, one on either side of the main channel at the maximum displacement of the depositional protrusion or the distributary network, and one on the most basinward position of the delta. We define delta area as the convex hull around these extent points and the delta apex. For each delta area polygon we extract elevation from the Shuttle Radar Topography Mission dataset and population count in years 2000, 2005, 2010, 2015, and 2020 from Gridded Population of the World, version 4. In total, deltas cover 0.56% of the total area of the world yet contain 4.1% of the world's population. The population on deltas has grown from 237 million in 2000 to projected values of 322 million in 2020. Deltaic population is growing at 1.59% per year, which outpaces the world growth rate of 1.11%. Additionally, population density is increasing with time from 322 people per km2 in year 2000 to projected values of 422 people per

  3. Superconducting bandpass delta-sigma modulator

    Science.gov (United States)

    Bulzacchelli, J. F.; Lee, H.-S.; Misewich, J. A.; Ketchen, M. B.

    1999-11-01

    Bandpass delta-sigma modulators digitize narrowband signals with high dynamic range and linearity. The required sampling rate is only a few times higher than the centre frequency of the input. This paper presents a superconducting bandpass delta-sigma modulator for direct analogue-to-digital conversion of RF signals in the GHz range. The input signal is capacitively coupled to one end of a microstrip transmission line, and a single flux quantum balanced comparator quantizes the current flowing out of the other end. Quantization noise is suppressed at the quarter-wave resonance of the transmission line (about 2 GHz in our design). Circuit performance at a 20 GHz sampling rate has been studied with several long JSIM simulations. Full-scale (FS) input sensitivity is 20 mV (rms), and in-band noise is -53 dBFS and -57 dBFS over bandwidths of 39 MHz and 19.5 MHz, respectively. In-band intermodulation distortion is better than -69 dBFS.

  4. Superconducting bandpass delta-sigma modulator

    Energy Technology Data Exchange (ETDEWEB)

    Bulzacchelli, J.F.; Lee, H.-S. [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Misewich, J.A.; Ketchen, M.B. [IBM Research Division, T. J. Watson Research Center, Yorktown Heights, NY 10598 (United States)

    1999-11-01

    Bandpass delta-sigma modulators digitize narrowband signals with high dynamic range and linearity. The required sampling rate is only a few times higher than the centre frequency of the input. This paper presents a superconducting bandpass delta-sigma modulator for direct analogue-to-digital conversion of RF signals in the GHz range. The input signal is capacitively coupled to one end of a microstrip transmission line, and a single flux quantum balanced comparator quantizes the current flowing out of the other end. Quantization noise is suppressed at the quarter-wave resonance of the transmission line (about 2 GHz in our design). Circuit performance at a 20 GHz sampling rate has been studied with several long JSIM simulations. Full-scale (FS) input sensitivity is 20 mV (rms), and in-band noise is -53 dBFS and -57 dBFS over bandwidths of 39 MHz and 19.5 MHz, respectively. In-band intermodulation distortion is better than -69 dBFS. (author)

  5. Catalyzing action towards the sustainability of deltas: deltas as integrated socio-ecological systems and sentinels of regional and global change

    Science.gov (United States)

    Foufoula-Georgiou, E.; Tessler, Z. D.; Brondizio, E.; Overeem, I.; Renaud, F.; Sebesvari, Z.; Nicholls, R. J.; Anthony, E.

    2016-12-01

    Deltas are highly dynamic and productive environments: they are food baskets of the world, home to biodiverse and rich ecosystems, and they play a central role in food and water security. However, they are becoming increasingly vulnerable to risks arising from human activities, land subsidence, regional water management, global sea-level rise, and climate extremes. Our Belmont Forum DELTAS project (BF-DELTAS: Catalyzing actions towards delta sustainability) encompasses an international network of interdisciplinary research collaborators with focal areas in the Mekong, Ganges Brahmaputra, and the Amazon deltas. The project is organized around five main modules: (1) developing an analytical framework for assessing delta vulnerability and scenarios of change (Delta-SRES), (2) developing an open-acess, science-based integrative modeling framework for risk assessment and decision support (Delta-RADS), (3) developing tools to support quantitative mapping of the bio-physical and socio-economic environments of deltas and consolidate bio-physical and social data within shared data repositories (Delta-DAT), (4) developing Global Delta Vulnerability Indices (Delta-GDVI) that capture current and projected scenarios for major deltas around the world , and (5) collaborating with regional stakeholders to put the science, modeling, and data into action (Delta-ACT). In this talk, a research summary will be presented on three research domains around which significant collaborative work was developed: advancing biophysical classification of deltas, understanding deltas as coupled socio-ecological systems, and analyzing and informing social and environmental vulnerabilities in delta regions.

  6. delta13C and delta18O trends across overstory environments in whole foliage and cellulose of three Pinus species.

    Science.gov (United States)

    Powers, Matthew D; Pregitzer, Kurt S; Palik, Brian J

    2008-09-01

    Stable isotope ratios of carbon (delta(13)C) and oxygen (delta(18)O) are increasingly used to investigate environmental influences on plant physiology. Cellulose is often isolated for isotopic studies, but some authors have questioned the value of this process. We studied trends in delta(13)C and delta(18)O of whole foliage and holocellulose from seedlings of three Pinus species across three overstory environments to evaluate the benefits of holocellulose extraction in the context of a traditional ecological experiment. Both tissue types showed increasing delta(13)C from closed-canopy controls to thinned plots to 0.3 ha canopy gaps, and no change in delta(18)O between overstory environments. delta(13)C of P. resinosa and P. strobus was greater than delta(13)C of P. banksiana in whole foliage and holocellulose samples, and there were no differences in delta(18)O associated with species in either tissue type. Our results suggest whole foliage and holocellulose provide similar information about isotopic trends across broad environmental gradients and between species, but holocellulose may be better suited for studying differences in stable isotope composition between multiple species across several treatments.

  7. Multidecadal Fluvial Sediment Fluxes to Deltas under Environmental Change Scenarios

    Science.gov (United States)

    Dunn, Frances; Darby, Stephen; Nicholls, Robert

    2016-04-01

    Sediment delivery is vital to sustain delta environments on which over half a billion people live worldwide. Due to factors such as subsidence and sea level rise, deltas sink relative to sea level if sediment is not delivered to and retained on their surfaces. Deltas which sink relative to sea level experience flooding, land degradation and loss, which endangers anthropogenic activities and populations. The future of fluvial sediment fluxes, a key mechanism for sediment delivery to deltas, is uncertain due to complex environmental changes which are predicted to occur over the coming decades. This research investigates fluvial sediment fluxes under environmental changes in order to assess the sustainability of delta environments under potential future scenarios up to 2100. Global datasets of climate change, reservoir construction, and population and GDP as proxies for anthropogenic influence through land use changes are used to drive the catchment numerical model WBMsed, which is being used to investigate the effects of these environmental changes on fluvial sediment delivery. This process produces fluvial sediment fluxes under multiple future scenarios which will be used to assess the future sustainability of a selection of 8 vulnerable deltas, although the approach can be applied to deltas worldwide. By modelling potential future scenarios of fluvial sediment flux, this research contributes to the prognosis for delta environments. The future scenarios will inform management at multiple temporal scales, and indicate the potential consequences for deltas of various anthropogenic activities. This research will both forewarn managers of potentially unsustainable deltas and indicate those anthropogenic activities which encourage or hinder the creation of sustainable delta environments.

  8. Refinement in the structural and magnetic properties of Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} and its application as laser micro-propellant using ablation confinement

    Energy Technology Data Exchange (ETDEWEB)

    Raza Ahmad, Muhammad, E-mail: mrazaahmad@gmail.com [Centre for Advanced Studies in Physics (CASP), GC University, Lahore, Punjab (Pakistan); Jamil, Yasir, E-mail: yasirjamil@yahoo.com [Department of Physics, University of Agriculture, Faisalabad, Punjab (Pakistan); Tabasuum, Ayesha [Department of Physics, University of Agriculture, Faisalabad, Punjab (Pakistan); Hussain, Tousif [Centre for Advanced Studies in Physics (CASP), GC University, Lahore, Punjab (Pakistan)

    2015-06-15

    The transition metal-substituted cobalt ferrite nanoparticles Co{sub 0.5}X{sub 0.5}Fe{sub 2}O{sub 4} (with X=Cu, Zn, Mn and Ni) exhibit a wide range of properties that result in their application in low loss magnetic core materials, vertical recording heads, antenna rods, memory elements, ferrofluids, biomedical applications, sensors and laser propulsion. Keeping in view its importance we investigated for the first time the structural and magnetic properties of the Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} samples that were subsequently subjected to thermal treatments for different time durations. The average crystallite sizes of the synthesized samples were found in the range of 24–46 nm. The values of the saturation magnetization and coercivity varied from 25.7 to 31.2 emu/g and 523.59 to 927.62 O{sub e}, respectively. The XRD patterns showed that increase in thermal treatment time resulted in the refinement of the structure whereas the SEM micrographs depicted a uniform particle size distribution of the synthesized material. We also explored the application of the synthesized material as a micro-thruster. It was found that the confinement of the laser induced plasma of Co{sub 0.5}×{sub 0.5}Fe{sub 2}O{sub 4} led to an increase in the value of coupling coefficient from the range of 5.747×10{sup −5}–7.0644×10{sup −5} N-s/J for unconfined to that of 1.41×10{sup −4}–2.68×10{sup −4}N-s/J for confined plasma corresponding to the Nd:YAG laser fluencies of 4×10{sup 9} J/m{sup 2}–6×10{sup 9} J/m{sup 2}. - Highlights: • Thermal treatment modifies the properties of Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4}. • Change in magnetic properties with increase in calcination time. • Confinement increases the laser propulsion parameters of Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4}.

  9. Structural and microwave absorption properties of Ni{sub (1-x)}Co{sub (x)}Fe{sub 2}O{sub 4} (0.0 {<=} x {<=} 0.5) nanoferrites synthesized via co-precipitation route

    Energy Technology Data Exchange (ETDEWEB)

    Maqsood, Asghari, E-mail: tpl.qau@usa.net [Thermal Transport Laboratory, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12 Islamabad (Pakistan); Khan, Kishwar, E-mail: kishwar.nust@gmail.com [Thermal Transport Laboratory, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), H-12 Islamabad (Pakistan)

    2011-02-17

    Research highlights: > Nanocrystalline Ni-Co was prepared by co-precipitation method. > The structural morphology was carried out using scanning electron microscope. > The complex relative permittivity ({epsilon}{sub r}) and complex relative permeability ({mu}{sub r}) were measured in the frequency range of 1 MHz to 3 GHz. > The variation of complex relative permittivity ({epsilon}{sub r}) as a function of frequency is explained in accordance with Maxwell-Wagner model and Koop's phenomenological theory. > Effect of frequency and cobalt concentration on permeability are reported. > The reflectivity (R) of nanoferrites is also calculated. > Results indicated that Ni{sub 1-x}Co{sub x}Fe{sub 2}O{sub 4} nanoparticles have excellent microwave absorbing properties, magneto-dielectric properties and have a great potential for military use. - Abstract: Ni-Co nanoferrites show excellent magneto-dielectric properties and these materials can be used to miniaturize the size of the high frequency devices which is the order of the day. Nanocrystalline Ni-Co ferrites having general formula Ni{sub 1-x}Co{sub x}Fe{sub 2}O{sub 4} (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) were prepared by co-precipitation method. The structural morphology of the prepared samples was carried out using scanning electron microscopy. The results showed the spherical shaped nanoparticles varying in the range of 16-40 nm. The complex relative permittivity ({epsilon}{sub r}) and complex relative permeability ({mu}{sub r}) were measured using vector network analyzer for all the samples in the frequency range of 1 MHz to 3 GHz. The variation of complex relative permittivity ({epsilon}{sub r}) as a function of frequency is explained in accordance with Maxwell-Wagner model and Koop's phenomenological theory. The effect of frequency and cobalt concentration on permeability are reported. The reflectivity (R) of nanoferrites is also calculated. The value of minimum reflection loss (RL) is about -18 dB at 2

  10. Dependence of magnetic properties and microstructure of mechanically alloyed Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} on soaking time

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, Ismayadi, E-mail: kayzen@gmail.com [Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Hashim, Mansor; Amin Matori, Khamirul [Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Physics Department, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Alias, Rosidah [Telekom Research and Development Sdn. Bhd., Telekom Research and Development Innovation Centre, Lingkaran Teknokrat Timur, 63000 Cyberjaya, Selangor (Malaysia); Hassan, Jumiah [Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Physics Department, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2012-08-15

    Possible soaking-time effects on the magnetic and microstructural properties of polycrystalline samples of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} have been studied. Nanosize powder produced by mechanical alloying was sintered at 800 Degree-Sign C with various soaking times. All samples showed the signature peak of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} even with one hour of soaking time. The size distributions show a slow growth of microstructural evolution related to density, porosity and also to the magnetic hysteresis loops. Within these distributions it is observed that the formation of multi-domains is not possible and probably there are the regions of superparamagnetic and single-domain grains. From the permeability studies, it is believed that the rise of the magnetic moment on the B sites give rise to the total saturation magnetization with increase of soaking time. The hysteresis loop of one-hour soaking time showed paramagnetic behavior dominating while longer soaking times showed ferromagnetic behavior starting to dominate. The coercivity was observed to increase with soaking time, signaling the increase of the anisotropy fields which was attributed to the shape anisotropy and also to the magnetocrystalline anisotropy. By correlating the morphology, phase analysis, permeability and hysteresis loops results, it is believed that there was an increase in number of crystalline-growth regions which together formed a total mass of mixed superparamagnetic and ferromagnetic grains with the latter starting to dominate the samples. - Highlights: Black-Right-Pointing-Pointer Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} samples sintered at relatively low temperature (800 Degree-Sign C). Black-Right-Pointing-Pointer The degree of crystallinity depends on the soaking time. Black-Right-Pointing-Pointer Correlation between morphology, phase analysis, permeability and hysteresis loops. Black-Right-Pointing-Pointer Increase in crystalline-growth formed a mixed of super- and

  11. Effect of Cu substitution for Ni on microstructural evolution and hydrogen storage properties of the Mg{sub 77}Ni{sub 20−x}Cu{sub x}La{sub 3} (x = 0, 5, 10 at%) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Yujie; Zhang, Bao; Wu, Ying, E-mail: yingwu2000@hotmail.com

    2015-10-05

    Highlights: • The lattice parameters of Mg{sub 2}Ni phase increase with Cu substituting for Ni. • The Mg–Ni–Cu–La alloys keep high hydrogen storage capacities of about 4.2 wt%. • The hydride formation enthalpy of Mg{sub 2}(Ni + Cu)–H{sub 2} is greatly reduced. - Abstract: The effect of Cu-substitution on the microstructures and hydrogen storage thermodynamic properties of Mg{sub 77}Ni{sub 20−x}Cu{sub x}La{sub 3} (x = 0, 5, 10 at%) alloys prepared by vacuum induction melting has been studied. XRD result shows that the samples consist of Mg, Mg{sub 2}Ni and LaMg{sub 12} phases. With Cu substituting for Ni, the structures of all phases do not change except for a slight increase in lattice parameters of Mg{sub 2}Ni phase. The P–C-isotherms of the Mg-based alloys have two distinct hydrogen absorption/desorption plateaus, which correspond to the Mg–H{sub 2} system and the Mg{sub 2}(Ni + Cu)–H{sub 2} system, respectively. The hydrogen storage capacities of Mg{sub 77}Ni{sub 20−x}Cu{sub x}La{sub 3} (x = 0, 5, 10 at%) alloys are 4.18 wt%, 4.20 wt% and 4.51 wt%, respectively. In the hydrogenated samples, these alloys consist of MgH{sub 2}, monoclinic Mg{sub 2}NiH{sub 4}, orthorhombic Mg{sub 2}NiH{sub 4}, LaH{sub 3} as well as MgCu{sub 2}. The presence of MgCu{sub 2} indicates the reaction of Mg{sub 2}Cu with hydrogen. The hydride formation enthalpy of alloys were calculated by the van’t Hoff equation. With the addition of Cu, the thermodynamic property is greatly improved, and the formation enthalpy values decrease to −51.02, −33.71 from −56.05 kJ mol{sup −1} H{sub 2} for the Mg{sub 2}(Ni + Cu)–H{sub 2} plateaus of Mg{sub 77}Ni{sub 20−x}Cu{sub x}La{sub 3} (x = 0, 5, 10 at%) alloys, respectively.

  12. Delta-doping in diffusion studies

    Science.gov (United States)

    Bénière, François; Chaplain, René; Gauneau, Marcel; Reddy, Viswanatha; Régrény, André

    1993-12-01

    The δ-doping where the dopant is confined on the length-scale of the lattice constant provides perfectly ideal conditions to study the atomic transport processes. We have studied MBE-grown GaAs samples δ-doped with Si and Al layers. Long time diffusion anneals have been performed in the temperature range 550 800 °C. The distribution profiles are examined by SIMS-profiling. We obtain Si diffusion coefficients in good agreement with the other recent studies using different techniques (rapid thermal annealing, capacitance-voltage profiling, sandwiched diffusion source). This contrasts with the earlier measurements based on diffusion of implanted dopants which were much more widely spread. We conclude that the more accurate data allowed with the δ-doping show that the diffusion coefficient is an intrinsic parameter provided that the amount of dopant and the dislocation density are kept sufficiently small. Le dopage-delta, où le dopant est confiné à l'échelle du paramètre du réseau, fournit les conditions parfaitement idéales pour étudier les processus de transport atomique. Nous avons étudié des échantillons de GaAs obtenus par épitaxie par jet moléculaire dopés par des couches-delta de Si et Al. Des traitements de diffusion de longue durée ont été réalisés dans l'intervalle de température 550 à 800°C. Les profils de distribution sont examinés par spectrométrie d'émission d'ions secondaires. Nous obtenons des coefficients de diffusion de Si en bon accord avec les autres études récentes utilisant des techniques différentes (traitement thermique ultrarapide, profil de distribution par la méthode capacité-voltage, diffusion d'une couche “ sandwich ”). Ceci diffère des mesures antérieures qui, basées sur la diffusion de dopants implantés, étaient beaucoup plus dispersées. Nous concluons que les données plus précises rendues possibles par le dopage-delta montrent que le coefficient de diffusion est un paramètre intrinsèque

  13. A NOTE ON DELTA-PERTURBATION EXPANSION METHOD

    Institute of Scientific and Technical Information of China (English)

    何吉欢

    2002-01-01

    The Delta-perturbation expansion method, a kind of new perturbation technique depending upon an artificial parameter Delta was studied. The study reveals that the method exits some advantages, but also exits some limitations. To overcome the limitations, the socalled linearized perturbation method proposed by HE Ji-huan can be powerfully applied.

  14. Automatisierte VHDL-Code-Generierung eines Delta-Sigma Modulators

    Science.gov (United States)

    Spilka, R.; Ostermann, T.

    2006-09-01

    Im vorliegenden Beitrag wird eine automatische Generierung des VHDL-Codes eines Delta-Sigma Modulators präsentiert. Die Koeffizientenmultiplikation wird hierbei durch Bit-Serielle-Addition durchgeführt. Mit Hilfe zweier neuer Matlab Funktionen wird der Systementwurf durch die bekannte Delta-Sigma Toolbox von R. Schreier erweitert und direkt synthesefähiger VHDL Code erzeugt.

  15. A BRITE view on delta Scuti and gamma Doradus stars

    CERN Document Server

    Zwintz, Konstanze

    2016-01-01

    BRITE-Constellation has obtained data for a few delta Scuti and gamma Doradus type stars. A short overview of the pulsational content found in five stars - beta Cassiopeiae, epsilon Cephei, M Velorum, beta Pictoris and QW Puppis - is given and the potential of BRITE-Constellation observations of delta Scuti and gamma Doradus pulsators is discussed.

  16. Terahertz radiation from delta-doped GaAs

    DEFF Research Database (Denmark)

    Birkedal, Dan; Hansen, Ole; Sørensen, Claus Birger;

    1994-01-01

    Terahertz pulse emission from four different delta-doped molecular beam epitaxially grown GaAs samples is studied. We observe a decrease of the emitted THz pulse amplitude as the distance of the delta-doped layer from the surface is increased, and a change in polarity of the THz pulses as compared...

  17. Women in Leadership Roles in Phi Delta Kappa.

    Science.gov (United States)

    Harder, Martha B.; And Others

    The professional and personal characteristics of the men and women in Phi Delta Kappa who hold the top elected positions in local chapters were compared, and the perceptions of these leaders of the impact of allowing women to be members of Phi Delta Kappa were assessed. A 43-item questionnaire was developed and mailed to 1,340 chapter presidents…

  18. Downstream hydraulic geometry of a tidally influenced river delta

    NARCIS (Netherlands)

    Sassi, M.G.; Hoitink, A.J.F.; Brye, de B.; Deleersnijder, E.

    2012-01-01

    Channel geometry in tidally influenced river deltas can show a mixed scaling behavior between that of river and tidal channel networks, as the channel forming discharge is both of river and tidal origin. We present a method of analysis to quantify the tidal signature on delta morphology, by extendin

  19. Towards a Comprehensive Framework for Adaptive Delta Management

    NARCIS (Netherlands)

    Marchand, M.; Ludwig, F.

    2014-01-01

    Deltas are dynamic landforms at the boundary of land and sea, involving intricate mazes of rivers and small waterways, wetlands, estuaries and coastal barrier islands. They are home to over half a billion people. Deltas are also home to rich ecosystems, such as mangroves and marshes. They are

  20. Delta's paradise: a challenge for lan[d]scape architects

    NARCIS (Netherlands)

    Boekhorst, te J.K.M.; Toorn, van den M.W.M.

    1996-01-01

    Paradise as a metaphor has always played an important role in art. This is definitely true for the art of garden design, but paradise is also a metaphor that can be used for the landscape. Some of the most interesting landscapes are found in deltas. Deltas are rich in natural and economic potential.

  1. Towards a Comprehensive Framework for Adaptive Delta Management

    NARCIS (Netherlands)

    Marchand, M.; Ludwig, F.

    2014-01-01

    Deltas are dynamic landforms at the boundary of land and sea, involving intricate mazes of rivers and small waterways, wetlands, estuaries and coastal barrier islands. They are home to over half a billion people. Deltas are also home to rich ecosystems, such as mangroves and marshes. They are econom

  2. An annotated list of Fishes from the Niger Delta

    NARCIS (Netherlands)

    Boeseman, M.

    1963-01-01

    At the end of November 1960, the Leiden Museum received an interesting collection of animals, mostly fishes, from the Niger delta. All specimens were collected by Mr. H. J. G. Beets, at the time employed by Shell B.P. — Delta Investigations, during the period May to August 1960, and in the region

  3. Delta's paradise: a challenge for lan[d]scape architects

    NARCIS (Netherlands)

    te Boekhorst, J.K.M.; Toorn, van den M.W.M.

    1996-01-01

    Paradise as a metaphor has always played an important role in art. This is definitely true for the art of garden design, but paradise is also a metaphor that can be used for the landscape. Some of the most interesting landscapes are found in deltas. Deltas are rich in natural and economic potential.

  4. Emerging leadership from communities in the Lower Mississippi Delta (LMD)

    Science.gov (United States)

    The Delta NIRI (Nutrition Intervention Research Initiative) team has conducted several research studies in the Lower Mississippi Delta (LMD) region employing the community-based participatory research (CBPR) model. Our collaborative work in the LMD focuses on interventions conducted in each of our c...

  5. Spatio-temporal distributions of delta18O, delta D and salinity in the Arabian Sea: Identifying processes and controls

    Digital Repository Service at National Institute of Oceanography (India)

    Deshpande, R.D.; Muraleedharan, P.M.; Singh, R.L.; Kumar, B.; Rao, M.S.; Dave, M.; Sivakumar, K.U.; Gupta, S.K.

    of these parameters. From the distributions of delta18O and salinity (S), and the relationships between delta18OdeltaD and delta18O–S, the following inferences have been drawn: (1) there is a broad correspondence between...

  6. 78 FR 21491 - DeltaPoint Capital IV, L.P., DeltaPoint Capital IV (New York), L.P.; Notice Seeking Exemption...

    Science.gov (United States)

    2013-04-10

    ... ADMINISTRATION DeltaPoint Capital IV, L.P., DeltaPoint Capital IV (New York), L.P.; Notice Seeking Exemption Under Section 312 of the Small Business Investment Act, Conflicts of Interest Notice is hereby given that DeltaPoint Capital IV, L.P. and DeltaPoint Capital IV (New York), L.P., 45 East Avenue, 6th...

  7. The Concentration Dependence of the (Delta)s Term in the Gibbs Free Energy Function: Application to Reversible Reactions in Biochemistry

    Science.gov (United States)

    Gary, Ronald K.

    2004-01-01

    The concentration dependence of (delta)S term in the Gibbs free energy function is described in relation to its application to reversible reactions in biochemistry. An intuitive and non-mathematical argument for the concentration dependence of the (delta)S term in the Gibbs free energy equation is derived and the applicability of the equation to…

  8. Surface Delta Interaction and g factors

    CERN Document Server

    Yu, Xiaofei

    2015-01-01

    Using an attractive surface delta interaction we obtain wave functions for 2 neutrons (or neutron holes) in the model space of 2 orbits (l=4, j=7/2) and (l=2, j=5/2). If we take the single particle energies to be degenerate we find that the g factors for I=2, 4 and 6 are all the same -namely the orbital g factor of the single nucleon. For a free neutron this quantity zero all 2particle or 2 hole g factors are equal to zero as well.. Only the orbital part of the g -factors contribute - the spin part cancels out. We then consider the effects of introducing a single energy splititng between the 2 orbits.

  9. Historical floods in the Dutch Rhine Delta

    Directory of Open Access Journals (Sweden)

    R. Glaser

    2003-01-01

    Full Text Available Historical records provide direct information about the climatic impact on society. Especially great natural disasters such as river floods have been for long attracting the attention of humankind. Time series for flood development on the Rhine branches Waal, Nederrijn/Lek and IJssel in the Dutch Rhine Delta are presented in this paper. In the case of the Waal it is even possible to compare historical flood frequencies based on documentary data with the recent development reconstructed from standardized instrumental measurements. In brief, we will also discuss various parameters concerning the structure of the flood series and the "human dimension" of natural disaster, i.e. the vulnerability of society when facing natural disasters.

  10. Head orientation prediction: delta quaternions versus quaternions.

    Science.gov (United States)

    Himberg, Henry; Motai, Yuichi

    2009-12-01

    Display lag in simulation environments with helmet-mounted displays causes a loss of immersion that degrades the value of virtual/augmented reality training simulators. Simulators use predictive tracking to compensate for display lag, preparing display updates based on the anticipated head motion. This paper proposes a new method for predicting head orientation using a delta quaternion (DQ)-based extended Kalman filter (EKF) and compares the performance to a quaternion EKF. The proposed framework operates on the change in quaternion between consecutive data frames (the DQ), which avoids the heavy computational burden of the quaternion motion equation. Head velocity is estimated from the DQ by an EKF and then used to predict future head orientation. We have tested the new framework with captured head motion data and compared it with the computationally expensive quaternion filter. Experimental results indicate that the proposed DQ method provides the accuracy of the quaternion method without the heavy computational burden.

  11. Spectral factorization using the delta operator

    DEFF Research Database (Denmark)

    Rostgaard, Morten; Poulsen, Niels Kjølstad; Ravn, Ole

    1994-01-01

    In recent years many papers have been published abouth the gamma-operator, mostly caused by the better numerical properties and the rapprochement between continuous and discrete time. A major problem within the LQG-design of a delta-based input-output relation has been how to spectral......-factorize in an efficient way. The discrete-time method of Kuccera will not be applied since numerical word-length characteristics will be poor for fast sampling rates. In this paper a new approach is considered. A new gamma-operator (Tustin operator) is introduced, in order to make an iterative and numerical stable...... solution to the spectral factorization problem. The key idea is to use the gamma-operator resembled by its behavior to the differential operator....

  12. Delta-excitations and the three-nucleon force

    CERN Document Server

    Epelbaum, E; Meißner, Ulf-G

    2007-01-01

    We study the three-nucleon force in chiral effective field theory with explicit Delta-resonance degrees of freedom. We show that up to next-to-next-to-leading order, the only contribution to the isospin symmetric three-nucleon force involving the spin-3/2 degrees of freedom is given by the two-pion-exchange diagram with an intermediate delta, frequently called the Fujita-Miyazawa force. We also analyze the leading isospin-breaking corrections due to the delta. For that, we give the first analysis of the delta quartet mass splittings in chiral effective field theory. The charge-symmetry breaking three-nucleon force due to an intermediate delta excitation is small, of the order of a few keV.

  13. Automatic Detection of Magnetic delta in Sunspot Groups

    CERN Document Server

    Padinhatteeri, Sreejith; Bloomfield, D Shaun; Gallagher, Peter T

    2015-01-01

    Large and magnetically complex sunspot groups are known to be associated with flares. To date, the Mount Wilson scheme has been used to classify sunspot groups based on their morphological and magnetic properties. The most flare prolific class, the delta sunspot-group, is characterised by opposite polarity umbrae within a common penumbra, separated by less than 2 degrees. In this article, we present a new system, called the Solar Monitor Active Region Tracker - Delta Finder (SMART-DF), that can be used to automatically detect and classify magnetic deltas in near-realtime. Using continuum images and magnetograms from the Helioseismic and Magnetic Imager (HMI) onboard NASA's Solar Dynamics Observatory (SDO), we first estimate distances between opposite polarity umbrae. Opposite polarity pairs having distances of less that 2 degrees are then identified, and if these pairs are found to share a common penumbra, they are identified as a magnetic delta configuration. The algorithm was compared to manual delta detect...

  14. Effects of isovector scalar $\\delta$-meson on hypernuclei

    CERN Document Server

    Ikram, M; Biswal, S K; Patra, S K

    2014-01-01

    We analyze the effects of $\\delta-$ meson on hypernuclei within the frame-work of relativistic mean field theory. The $\\delta-$ meson is included into the Lagrangian for hypernuclei. The extra nucleon-meson coupling ($g_\\delta$) affects the every piece of physical observables, like binding energy, radii and single particle energy of hypernuclei. The lambda mean field potential is investigated which is consistent with other predictions. Flipping of single particle energy levels are observed with the strength of $g_\\delta$ in the considered hypernuclei as well as normal nuclei. The spin-orbit potentials are observed for considered hypernuclei and the effect of $g_\\delta$ on spin-orbit potentials is also analyzed. The calculated single-$\\Lambda$ binding energies ($B_\\Lambda$) are quite agreeable with the experimental data.

  15. Isolation of Delta9-THCA-A from hemp and analytical aspects concerning the determination of Delta9-THC in cannabis products.

    Science.gov (United States)

    Dussy, Franz E; Hamberg, Cornelia; Luginbühl, Marco; Schwerzmann, Thomas; Briellmann, Thomas A

    2005-04-20

    A simple procedure based on a common silica gel column chromatography for the isolation of Delta9-tetrahydrocannabinolic acid A (Delta9-THCA-A) from hemp in a multi-milligram scale is presented. Further, the decarboxylation reaction of Delta9-THCA-A to the toxicologically active Delta9-tetrahydrocannabinol (Delta9-THC) at different analytical and under-smoking conditions is investigated. Maximal conversion in an optimised analytical equipment yields about 70% Delta9-THC. In the simulation of the smoking process, only about 30 % of the spiked substance could be recovered as Delta9-THC.

  16. Multimode delta-E effect magnetic field sensors with adapted electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Zabel, Sebastian; Fichtner, Simon; Kirchhof, Christine; Quandt, Eckhard; Faupel, Franz, E-mail: ff@tf.uni-kiel.de [Faculty of Engineering, Institute for Materials Science, Kiel University, Kaiserstraße 2, 24143 Kiel (Germany); Reermann, Jens; Schmidt, Gerhard [Faculty of Engineering, Institute for Electrical Engineering, Kiel University, Kaiserstraße 2, 24143 Kiel (Germany); Wagner, Bernhard [Fraunhofer Institute for Silicon Technology ISIT, Fraunhoferstraße 1, 25524 Itzehoe (Germany)

    2016-05-30

    We present an analytical and experimental study on low-noise piezoelectric thin film resonators that utilize the delta-E effect of a magnetostrictive layer to measure magnetic fields at low frequencies. Calculations from a physical model of the electromechanical resonator enable electrode designs to efficiently operate in the first and second transversal bending modes. As predicted by our calculations, the adapted electrode design improves the sensitivity by a factor of 6 and reduces the dynamic range of the sensor output by 16 dB, which significantly eases the requirements on readout electronics. Magnetic measurements show a bandwidth of 100 Hz at a noise level of about 100 pTHz{sup −0.5}.

  17. Multimode delta-E effect magnetic field sensors with adapted electrodes

    Science.gov (United States)

    Zabel, Sebastian; Reermann, Jens; Fichtner, Simon; Kirchhof, Christine; Quandt, Eckhard; Wagner, Bernhard; Schmidt, Gerhard; Faupel, Franz

    2016-05-01

    We present an analytical and experimental study on low-noise piezoelectric thin film resonators that utilize the delta-E effect of a magnetostrictive layer to measure magnetic fields at low frequencies. Calculations from a physical model of the electromechanical resonator enable electrode designs to efficiently operate in the first and second transversal bending modes. As predicted by our calculations, the adapted electrode design improves the sensitivity by a factor of 6 and reduces the dynamic range of the sensor output by 16 dB, which significantly eases the requirements on readout electronics. Magnetic measurements show a bandwidth of 100 Hz at a noise level of about 100 pTHz-0.5.

  18. Dependence of {delta}E effect on internal stresses in nickel: Experimental results by laser interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Chicharro, J.M. [Dept. de Mecanica Aplicada e Ingenieria de Proyectos, E.T.S.I. Industriales, Universidad de Castilla-La Mancha, Avd. Camilo Jose Cela s/n, 13071 Ciudad Real (Spain)]. E-mail: josemanuel.chicharro@uclm.es; Bayon, A. [Dept. de Fisica Aplicada a los Recursos Naturales, E.T.S.I. Minas, Universidad Politecnica de Madrid, c/Rios Rosas, 21, 28003 Madrid (Spain); Salazar, F. [Dept. de Fisica Aplicada a los Recursos Naturales, E.T.S.I. Minas, Universidad Politecnica de Madrid, c/Rios Rosas, 21, 28003 Madrid (Spain)

    2006-02-15

    The speckle heterodyne interferometry is applied to the study of the dependence of Young's modulus on both the magnetic field and the internal stresses in a soft ferromagnetic material. Young's modulus is determined from the first natural longitudinal frequency of a slender magnetic rod positioned within a solenoid. Vibration of the sample is detected by an optical heterodyne system with a wide bandwidth. The samples are heated to above the Curie point and then cooled at several rates in order to induce different internal stresses. The study refers to nickel rods 10mm in diameter and 110mm in length. The grain sizes of the samples are also determined and related to changes in {delta}E.

  19. Studies on the metabolism of the Delta9-tetrahydrocannabinol precursor Delta9-tetrahydrocannabinolic acid A (Delta9-THCA-A) in rat using LC-MS/MS, LC-QTOF MS and GC-MS techniques.

    Science.gov (United States)

    Jung, Julia; Meyer, Markus R; Maurer, Hans H; Neusüss, Christian; Weinmann, Wolfgang; Auwärter, Volker

    2009-10-01

    In Cannabis sativa, Delta9-Tetrahydrocannabinolic acid-A (Delta9-THCA-A) is the non-psychoactive precursor of Delta9-tetrahydrocannabinol (Delta9-THC). In fresh plant material, about 90% of the total Delta9-THC is available as Delta9-THCA-A. When heated (smoked or baked), Delta9-THCA-A is only partially converted to Delta9-THC and therefore, Delta9-THCA-A can be detected in serum and urine of cannabis consumers. The aim of the presented study was to identify the metabolites of Delta9-THCA-A and to examine particularly whether oral intake of Delta9-THCA-A leads to in vivo formation of Delta9-THC in a rat model. After oral application of pure Delta9-THCA-A to rats (15 mg/kg body mass), urine samples were collected and metabolites were isolated and identified by liquid chromatography-mass spectrometry (LC-MS), liquid chromatography-tandem mass spectrometry (LC-MS/MS) and high resolution LC-MS using time of flight-mass spectrometry (TOF-MS) for accurate mass measurement. For detection of Delta9-THC and its metabolites, urine extracts were analyzed by gas chromatography-mass spectrometry (GC-MS). The identified metabolites show that Delta9-THCA-A undergoes a hydroxylation in position 11 to 11-hydroxy-Delta9-tetrahydrocannabinolic acid-A (11-OH-Delta9-THCA-A), which is further oxidized via the intermediate aldehyde 11-oxo-Delta9-THCA-A to 11-nor-9-carboxy-Delta9-tetrahydrocannabinolic acid-A (Delta9-THCA-A-COOH). Glucuronides of the parent compound and both main metabolites were identified in the rat urine as well. Furthermore, Delta9-THCA-A undergoes hydroxylation in position 8 to 8-alpha- and 8-beta-hydroxy-Delta9-tetrahydrocannabinolic acid-A, respectively, (8alpha-Hydroxy-Delta9-THCA-A and 8beta-Hydroxy-Delta9-THCA-A, respectively) followed by dehydration. Both monohydroxylated metabolites were further oxidized to their bishydroxylated forms. Several glucuronidation conjugates of these metabolites were identified. In vivo conversion of Delta9-THCA-A to Delta9-THC was

  20. Extensive junctional diversity of rearranged human T cell receptor delta genes.

    Science.gov (United States)

    Hata, S; Satyanarayana, K; Devlin, P; Band, H; McLean, J; Strominger, J L; Brenner, M B; Krangel, M S

    1988-06-10

    The human T cell receptor delta (TCR delta) gene encodes one component of the TCR gamma delta-CD3 complex found on subsets of peripheral blood and thymic T cells. Human TCR delta diversity was estimated by characterizing rearrangements in TCR gamma delta cell lines and determining the structures of complementary DNA clones representing functional and nonfunctional transcripts in these cell lines. One V delta segment and one J delta segment were identified in all functional transcripts, although a distinct J delta segment was identified in a truncated transcript. Further, one D delta element was identified, and evidence for the use of an additional D delta element was obtained. Thus human TCR delta genes appear to use a limited number of germline elements. However, the apparent use of two D delta elements in tandem coupled with imprecise joining and extensive incorporation of N nucleotides generates unprecedented variability in the junctional region.

  1. Potency of Mahakam Delta in East Kalimantan, Indonesia

    Directory of Open Access Journals (Sweden)

    Zairin Zain

    2014-04-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE Mahakam Delta is not only utilized for fishery activities but also for several industrial purposes such as coal and oil mining, shipping and timber. The objective of this paper is to provide information in term of the potency of Mahakam Delta located in East Kalimantan province, Indonesia. The study was conducted in Mahakam Delta, East Kalimantan Province, Indonesia. Participatory rural appraisal is a group of methods to collect information in a participatory fashion from rural communities. The method employed in this research was descriptive analysis describing the environmental potency found in Mahakam Delta. Massive conversion of mangrove forest particularly Nypa (Nypa fruticans area into pond has driven conflict among related stakeholders on the utilization of natural resource and land which subsequently impacts on the fish and shrimp source regeneration, loss of ecological functions of mangrove forest for feeding, nursery and spawning ground of fish and other organisms. Besides of fisheries, oil and gas activity also exists in Mahakam Delta. Mahakam Delta is regarded as important area due to the largest producer of oil and gas mining. Thus, oil and gas industry is the most reliable sector that contributes to the economic development of Kutai Kartanegara district. As a resource provider, Mahakam Delta ecosystem provides various resources for livelihoods. As a life-support service provider, Mahakam Delta ecosystem provides habitat and ideal environment to support variety of living kinds. As a convenience provider, Mahakam Delta ecosystem provides unique and interesting recreation site. As a protector from natural disaster, Mahakam Delta ecosystem is able to protect human kinds from natural disaster threatening coastal area.

  2. Sustainable Growth in Urbanised Delta Areas: the Opportunities of a Geographical Approach to the Pearl River Delta

    NARCIS (Netherlands)

    Van Rens, G.; Nillisen, A.L.; Schamhart, C.; Lugt, N.

    2006-01-01

    The attractions of delta areas have boomed economies and founded major cities, but the threats of the adjacent water have persisted and natural resources have declined. The objective to facilitate sustainable urban growth in delta areas can only be met by a simultaneous approach of all the stakehold

  3. Preservation potential of the Last Interglacial lower Rhine delta relative to the Holocene Rhine-Meuse delta

    NARCIS (Netherlands)

    Peeters, J.; Martinius, A.W.; Cohen, K.M.; Middelkoop, H.; Stouthamer, E.

    2013-01-01

    In order to improve our insights in the sequence stratigraphic and architectural development of lower deltaic hydrocarbon reservoirs we study the Last Interglacial Rhine delta (MIS-5), and compare it to its well investigated counterpart, the Holocene (MIS-1) Rhine- Meuse delta (Berendsen & Stouthame

  4. The effect of Fe addition on the transformation temperatures, lattice parameter and magnetization saturation of Ni{sub 52.5-X}Mn{sub 23}Ga{sub 24.5}Fe{sub X} ferromagnetic shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Soto-Parra, D.E.; Alvarado-Hernandez, F.; Ayala, O.; Ochoa-Gamboa, R.A. [Centro de Investigacion en Materiales Avanzados S.C. Miguel de Cervantes 120, Complejo industrial Chihuahua, 31109 Chihuahua (Mexico); Flores-Zuniga, H. [Centro de Investigacion en Materiales Avanzados S.C. Miguel de Cervantes 120, Complejo industrial Chihuahua, 31109 Chihuahua (Mexico)], E-mail: horacio.flores@cimav.edu.mx; Rios-Jara, D. [Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la Presa San Jose 2055, Col. Lomas 4a seccion, 78216 San Luis Potosi, S.L.P. (Mexico)

    2008-09-22

    The effect of Fe addition on martensitic transformation temperatures, Curie temperature (T{sub C}), lattice parameters and magnetization saturation was studied in Ni{sub 52.5-X}Mn{sub 23}Ga{sub 24.5}Fe{sub X} alloys fabricated by arc-melting furnace. The characterizations were performed by DSC, X-ray diffraction and magnetometry. Fe replacing Ni sites leads to an increment on lattice parameter and on the magnetization saturation of the austenitic phase at room temperature. Also, T{sub C} increases from 370 K up to 400 K and remains constant for X {>=} 3.1 at.% Fe. In contrast, martensitic transformation temperatures decrease with Fe substituting Ni.

  5. Time domain transients investigation on the lithium rich cathode material Li[Li{sub 0.2}Ni{sub 0.2}Mn{sub 0.6}]O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Lingxia; Zheng, Weidong; Xu, Xiaoping; Shui, Miao, E-mail: shuimiao@nbu.edu.cn; Cheng, Liangliang; Shu, Jie; Yang, Tianci; Feng, Lin; Ren, Yuanlong

    2013-12-15

    Time domain transients to current step of multiple current densities were calculated to evaluate the polarization and fractional contribution of lithium rich cathode material Li[Li{sub 0.2}Ni{sub 0.2}Mn{sub 0.6}]O{sub 2} based on the equivalent circuit determined from the electrochemical impedance spectrum. The calculated data matched the experimental profiles well. The contributions of the individual circuit elements, like charge transfer reaction, lithium transportation across the SEI film and solid-state lithium diffusion process, were successfully differentiated and the importance of each element was fully assessed. The results told us that they should be equally paid attention to and minimized by the optimized preparation method and cell design.

  6. TEM study of the cooling rate dependent crystallization behavior of (Zr{sub 65}Al{sub 10}Ni{sub 10}Cu{sub 15}){sub 98}Nb{sub 2} metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yingmin, E-mail: apwangym@dlut.edu.c [School of Materials Science and Engineering, Dalian University of Technology, No. 2 Lingggong Road, Ganjingzi District, Dalian, Liaoning 116024 (China); Shek, Chan Hung [Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR (China); Wang, Qing; Qiang, Jianbing; Dong, Chuang [School of Materials Science and Engineering, Dalian University of Technology, No. 2 Lingggong Road, Ganjingzi District, Dalian, Liaoning 116024 (China)

    2010-08-15

    The crystallization of (Zr{sub 65}Al{sub 10}Ni{sub 10}Cu{sub 15}){sub 98}Nb{sub 2} metallic glasses has been studied using transmission electron microscopy (TEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The ribbon glass and bulk metallic glass (BMG) of this alloy exhibit different crystallization behaviors. For ribbon glass in the first stage crystallization, icosahedral quasicrystal (I-phase) precipitated together with the {eta}-Zr{sub 2}Ni (a = 1.226 nm) phase. The BMG alloy transforms into the I-phase and two coherently coexisted phases, namely, the Al{sub 2}Zr{sub 3} phase and an unknown primitive cubic phase (a = 0.76 nm) in this stage. The experimental evidence indicates that the liquid cooling rate for sample preparation has a significant effect on its crystallization behavior of this alloy glass.

  7. Corrosion behavior of glassy Ni{sub 55}Co{sub 5}Nb{sub 2}Ti{sub 1}Zr{sub 1} alloy in 1 N HCl solution studied by potentiostatic polarization and XPS

    Energy Technology Data Exchange (ETDEWEB)

    Pang Shujie [Department of Physics and Materials Science, City University of Hong Kong, Hong Kong (China); Department of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China); Shek Chanhung [Department of Physics and Materials Science, City University of Hong Kong, Hong Kong (China)]. E-mail: apchshek@cityu.edu.hk; Zhang Tao [Department of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China); Asami, Katsuhiko [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Inoue, Akihisa [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2006-03-15

    Corrosion resistance of glassy Ni{sub 55}Co{sub 5}Nb{sub 2}Ti{sub 1}Zr{sub 1} (at.%) alloy in 1 N HCl solution was investigated with respect to the electrochemical behavior and the compositions of the passive film and the underlying alloy surface just below the passive film. The potentiostatic polarization curve indicated that the alloy was spontaneously passivated with a low passive current density of the order of 10{sup -3} A m{sup -2}. The quantitative X-ray photo-electron spectroscopy (XPS) analysis revealed that the thickness of the surface film increased linearly with an anodizing ratio of 1.5 nm V{sup -1}. The high corrosion resistance of the glassy alloy was due to the formation of niobium, titanium and zirconium-enriched passive film. The growth mechanism of the passive films is also discussed.

  8. The effect of internal and external stress on two-way shape-memory behaviour in Co{sub 49}Ni{sub 21.6}Ga{sub 29.4} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Liu, G D; Dai, X F; Luo, H Z; Liu, H Y; Meng, F B; Li, Y; Yu, X [School of Material Sciences and Engineering, Hebei University of Technology, Tianjin 300130 (China); Chen, J L; Wu, G H [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)

    2011-02-02

    The effect of the internal stress on the two-way shape memory in Co{sub 49}Ni{sub 21.6}Ga{sub 29.4} single crystals has been investigated. We found that the internal stress generated natively by the solidifying process works as a tensile force along the growth direction. Applying different compressive pre-stresses along the [0 0 1] direction, the shape-memory strain can be continuously changed from +1.0% to -2.3%. In the [1 1 0] direction, the strain monotonically increases from -2.0% to -4.0% due to a strong detwinning produced by the consistent effect of the external and internal stresses.

  9. Effect of heat treatment on structural and Mössbauer spectroscopic properties of coprecipitated Mn{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Srinivas, Ch.; Babu, Ch. Seshu [Department of physics, Sasi Institute of Technology and Engineering, Tadepalligudem-534101 (India); Tirupanyam, B. V. [Department of physics, Government Arts College (Autonomous), Rajahmundry-533401 (India); Meena, S. S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai-4000085 (India); Sastry, D. L., E-mail: dl-sastry@gmail.com [Department of physics, Andhra University, Visakhapatnam-530003 (India)

    2015-06-24

    Results obtained in a systamatic study by X-ray diffraction and Mösssbauer spectroscopy on the structural and magnetic properties on Mn{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} ferrite nanoparticles heat treated at 200 °C, 500 °C and 800 °C are reported. Average crystallite sizes are estimated to be in the range (2.6nm – 12.8nm). It is observed that crystallite sizes increase with increase in sintering temperature and random variation in lattice parameter was observed. At relatively low sintering temperatures the samples exhibit superparamagnetism and complete ferrite phase was observed at higher heat treatment.

  10. Activation volume in heterogeneous deformation of Mg{sub 65}Cu{sub 12.5}Ni{sub 12.5}(Ce{sub 75}La{sub 25}){sub 10} metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Thurieau, Nicolas; Perrière, Loïc; Laurent-Brocq, Mathilde [ICMPE, CNRS-UPEC, 2 rue Henri Dunant 94320 Thiais, Cedex (France); Champion, Yannick, E-mail: yannick.champion@simap.grenoble-inp.fr [Univ. Grenoble Alpes, SIMAP, F-38000 Grenoble (France); CNRS, SIMAP, F-38000 Grenoble (France)

    2015-11-28

    Depth variation at constant load in instrumented nano-indentation was used to measure activation volume controlling shear band formation in the Mg{sub 65}Cu{sub 12.5}Ni{sub 12.5}(Ce{sub 75}La{sub 25}){sub 10} metallic glass. A series of measurements revealed a large scattering of the data spanning from 100 Å{sup 3} to 800 Å{sup 3}. The distribution of values, which is not following a normal one, may be attributed to the atomic structure of metallic glasses with the absence of long range order, leading to different volume fraction of shear bands for independent experiments. Activation volume is analyzed considering the variation of shear band volume fraction leading to a unique value of a true activation volume. An interpretation for the distribution of values is proposed.

  11. In-situ X-ray diffraction studies of the phase transformations and structural states of B2, R and B19′ phases in Ti{sub 49.5}Ni{sub 50.5} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ostapenko, Marina G., E-mail: artifakt@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Meisner, Ludmila L., E-mail: llm@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation); Lotkov, Aleksandr I., E-mail: lotkov@ispms.tsc.ru; Gudimova, Ekaterina Y., E-mail: egu@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Zakharova, Margarita A., E-mail: tibiboreth@gmail.com [National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    The martensitic transformation, Debye–Waller factor, mean-square atomic displacements and the coefficient of thermal expansion on cooling of the Ti{sub 49.5}Ni{sub 50.5} shape memory alloy were examined using in-situ X-ray diffraction. It was revealed B2→R (T{sub R} ≡ T = 273 ± 10 K) along with B2→B19’ (M{sub s} ≡ T = 273 ± 10 K) transitions occur. It was found that Debye–Waller factor and mean-square displacement of B2 phase undergo significant increase as functions of temperature when phase transition B2→R and B2→B19’ take place. The analysis of the thermal expansion coefficient of the B2 phase indicates that the value of a increases almost linearly while cooling.

  12. Yafet-Kittel-type magnetic ordering in Ni{sub 0.35}Zn{sub 0.65}Fe{sub 2}O{sub 4} ferrite detected by magnetosensitive microwave absorption measurements

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, G., E-mail: memodin@yahoo.co [Departamento de Materiales Metalicos y Ceramicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, Coyoacan, DF 04510 Mexico (Mexico); Montiel, H.; Barron, J.F. [Departamento de Tecnociencias, Centro de Ciencias Aplicadas y Desarrollo Tecnologico de la Universidad Nacional Autonoma de Mexico, Mexico, DF 04510 (Mexico); Gutierrez, M.P. [Universidad Anahuac, Mexico Norte, Mexico DF (Mexico); Zamorano, R. [Departamento de Fisica, ESFM-IPN, U. P. Adolfo Lopez Mateos Edificio 9, Av. Instituto Politecnico Nacional S/N, Col. San Pedro Zacatenco, 07738 DF (Mexico)

    2010-02-15

    Magnetosensitive microwave absorption measurements of polycrystalline ferrite Ni{sub 0.35}Zn{sub 0.65}Fe{sub 2}O{sub 4} was carried out at 9.4 GHz (X-band) as a function of temperature. Temperature dependence of the total linewidth (DELTAH{sub pp}) deduced from the resonance spectra showed the passage through the Curie point (T{sub c}approx430 K). Additionally, the plot DELTAH{sub pp} vs. T also indicated the existence of another magnetic phase transition at approx240 K, which can be associated with a Yafet-Kittel-type canting of the magnetic moments. Low-field microwave absorption (LFMA) and the magnetically modulated microwave absorption spectroscopy (MAMMAS) were used to give a further knowledge on this material. For low temperature, these techniques give evidence of a Yafet-Kittel-type canting of the magnetic moments.

  13. A new pseudo-binary Mg{sub 6}Ni{sub 0.5}Pd{sub 0.5} intermetallic compound stabilised by Pd for hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, J.F., E-mail: josefrancisco.fernandez@uam.e [Dpto. Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Cuevas, F. [CMTR/ICMPE/CNRS, 2-8 rue Henri Dunant, 94320 THIAIS Cedex (France); Leardini, F.; Bodega, J.; Ares, J.R. [Dpto. Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Garces, G.; Perez, P. [Centro Nacional de Investigaciones Metalurgicas, CSIC, Av. Gregorio del Amo 8, 28040 Madrid (Spain); Sanchez, C. [Dpto. Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, 28049 Madrid (Spain)

    2010-04-16

    The structural properties and chemical composition of a new pseudo-binary intermetallic compound Mg{sub 6.01}Ni{sub 0.43}Pd{sub 0.53} stabilised by Pd have been studied by X-ray Powder Diffraction and Scanning Electron Microscope coupled to Energy Dispersive X-ray analysis. The intermetallic compound is isomorphous to Mg{sub 6}Pd (Cubic system, F-43m space group) with a lattice parameter of 20.1373 A. The Mg atoms occupy the same atomic position than in Mg{sub 6}Pd while the Ni and Pd atoms share the 16e sites. The solubility limit of Ni in Mg{sub 6}Pd extents, at least, up to 11 wt%. The compound is stable up to melting which takes place at 800 K.

  14. Ab initio study of the compound-energy modeling of multisublattice structures: The (hP6) Ni{sub 2}In-type intermetallics of the Ni–In–Sn system

    Energy Technology Data Exchange (ETDEWEB)

    Ramos de Debiaggi, S., E-mail: susana.ramos@fain.uncoma.edu.ar [Facultad de Ingeniería, Universidad Nacional del Comahue, Buenos Aires 1400, 8300 Neuquén (Argentina); Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas – CONICET-UNCo (Argentina); González Lemus, N.V. [Facultad de Ingeniería, Universidad Nacional del Comahue, Buenos Aires 1400, 8300 Neuquén (Argentina); Deluque Toro, C. [Grupo de Nuevos Materiales, Universidad de la Guajira, Riohacha (Colombia); Fernández Guillermet, A. [CONICET - Instituto Balseiro, Centro Atómico Bariloche, Avda. Bustillo 9500, 8400 Bariloche (Argentina)

    2015-01-15

    Highlights: • A DFT study of the compounds involved in CALPHAD modeling of the Ni–In–Sn (hP6) phase. • Several three-sublattice compounds of Ni, In, Sn and vacancies are studied ab initio. • Structural, cohesive and thermodynamic properties and the electronic DOS are reported. • Trends in calculated properties are correlated with changes in electronic structure. • A picture of the chemical bonding trends for these s-p/d type compounds is discussed. - Abstract: The thermodynamic modeling of non-stoichiometric, multisublattice intermetallic phases using the Compound-Energy Formalism (CEF) involves the determination of parameters representing the Gibbs energy (G{sub m}) of binary compounds, the so-called “end-member compounds” (EMCs), which are often metastable or hypothetical. In current CALPHAD (i.e., “Calculation of Phase Diagrams”) work, these quantities are treated as free parameters to be determined by searching for the best fit to the available information in the optimization procedure. The general purpose of this paper is to propose a theoretical approach to the study of the EMCs which makes use of density-functional-theory (DFT) ab initio calculations. The present method is applied to the EMCs involved in the CEF modeling of the non-stoichiometric (hP6) Ni{sub 2}In-structure type phase of the Ni–In and Ni–In–Sn systems using the three-sublattice models (Ni){sub 1}(Ni,Va){sub 1}(In,Ni){sub 1} and (Ni,Va){sub 1}(Ni,Va){sub 1}(In,Ni,Sn){sub 1}, respectively. By means of systematic ab initio projected augmented waves (PAW) calculations using the VASP code we study the EMCs involved in the CEF formulations of the G{sub m} for this phase in the binary and the ternary systems. Specifically, we study the twelve EMCs corresponding to the following sublattice occupations: (Ni){sub 1}(Ni){sub 1}(In){sub 1}, which is usually described as Ni:Ni:In (i.e., a compound with formula “Ni{sub 2}In”), Ni:Ni:Ni (i.e., “Ni{sub 3}”), Ni:Ni:Sn (

  15. Magnetoimpedance studies on urine treated Co{sub 66}Ni{sub 7}Si{sub 7}B{sub 20} ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Kotagiri, Ganesh [Advanced Magnetic Materials Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Markandeyulu, G., E-mail: mark@iitm.ac.in [Advanced Magnetic Materials Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Doble, Mukesh; Nandakumar, V. [Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600036 (India)

    2015-11-15

    Magnetoimpedance (MI) response of Co{sub 66}Ni{sub 7}Si{sub 7}B{sub 20} ribbons treated with artificial urine with protein bovine serum albumin (BSA), artificial urine without protein BSA and healthy male urine was studied as a function of time of incubation. The maximum MI [(MI){sub m}] values of the ribbons treated with artificial urine without protein (RTAU) after 3 h, 6 h, 12 h and 24 h of incubation are 30% (at 4 MHz), 15% (at 5 MHz), 14% (at 10 MHz) and 8% (at 13 MHz) respectively. On the other hand, the respective (MI){sub m} values of the ribbons treated with artificial urine with protein (RTAUP) are 33% (at 4 MHz), 25% (at 5 MHz), 20% (at 8 MHz) and 15% (12 MHz). However (MI){sub m} values of the ribbons treated with healthy male urine (RTHMU) after 4 h, 5 h, 10 h and 15 h of incubation are 71% (at 3 MHz), 57% (at 3 MHz), 25% (at 6 MHz) and 25% (at 5 MHz), respectively. The saturation magnetization (M{sub s}) values of RTAU after 3 h, 6 h, 12 h and 24 h of incubation are 71 emu/g, 65 emu/g, 63 emu/g and 60 emu/g respectively whereas, the respective M{sub s} values of RTAUP are 73 emu/g, 69 emu/g, 67 emu/g and 64 emu/g. The M{sub s} values of RTHMU after 4 h, 5 h, 10 h and 15 h of incubation are 96 emu/g, 90 emu/g, 75 emu/g and 75 emu/g respectively. The decrease in M{sub s} and (MI){sub m} values in RTAU and RTAUP compared to as-quenched ribbon is related to the amounts of various elements etched out from the ribbons and increased surface roughness. The M{sub s} and (MI){sub m} values of RTHMU are seen to have increased after 4 h and 5 h of incubation, due to strain relaxation through removal of strain developed during rapid quenching of the ribbons. On the other hand, the M{sub s} and (MI){sub m} values of RTHMU after 10 h and 15 h have decreased due to deterioration of the surface of the ribbons and thus, increase in magnetic (surface) anisotropy. The decrease in (MI){sub m} and M{sub S} of RTAU with the time of incubation are more rapid compared to that

  16. Effects of sintering process on the structural, magnetic and thermal properties of Ni{sub 0.92}Ca{sub 0.08}Fe{sub 2}O{sub 4} nanoferrite

    Energy Technology Data Exchange (ETDEWEB)

    Abosheiasha, H.F., E-mail: Hatem_Fouad@f-eng.tanta.edu.eg; Assar, S.T.

    2014-12-15

    Nanoparticles of Ni{sub 0.92}Ca{sub 0.08}Fe{sub 2}O{sub 4} ferrite was prepared by the citrate precursor method. The effect of sintering temperature and sintering time on the structural, magnetic, and thermal properties of the prepared samples were investigated by using x-ray diffraction (XRD) and transmission electron microscope (TEM), vibrating sample magnetometer (VSM), and photoacoustic (PA) technique, respectively. The grain size of the sintered samples estimated from the XRD and the TEM results inform that the increase in the particle size is more announced by increasing the sintering temperature than increasing the sintering time. The unexpected decrease of the saturation magnetization of the sintered samples is ascribed to the dominant effect of the cation distribution which is affected by the sintering process. The cation distribution of the present samples was obtained from the analysis of the magnetization measurements and XRD data. The increase of measured density and the decrease of porosity of the sintered samples as a result of the grain growth have the obvious effect of increasing their thermal diffusivity. - Highlights: • Nanoferrite of Ni{sub 0.92}Ca{sub 0.08}Fe{sub 2}O{sub 4} has been prepared by citrate precursor method. • Effect of sintering temperature and time on various properties of the sintered samples is studied. • The XRD patterns reveal that the sintered samples at higher than 400 °C have single phase structure. • Abnormal effect of both sintering temperature and time on saturation magnetization is explained. • The increase of thermal diffusivity with increasing sintering temperature and time is discussed.

  17. Influencia del tratamiento isotérmico en la intercara de los intermetálicos Ni>3Al como refuerzo de un compuesto de matriz de aluminio obtenido por pulvimetalurgia

    Directory of Open Access Journals (Sweden)

    Ferrer, C.

    1998-05-01

    Full Text Available The improvement of the mechanical properties of aluminium MMCs reinforced with Ni>3Al particles is based on the continuity of the matrix-particle interface as well as on the strength of these particles. This work deals with the influence of different heat treatments on the evolution of new phases in that interface. Samples were prepared following a powder metallurgy route with a final stage of extrusion. Several heat treatments encompassing a broad group of temperatures and times were applied, producing different phases around the primary particles. Samples were analysed via optical and scanning electron microscopy with energy dispersive X ray analysis. Microhardness tests were also conducted on the different phases generated.

    La mejora de las propiedades mecánicas de los composites de aluminio reforzados con partículas de Ni>3Al se debe a la continuidad de la unión entre las partículas de refuerzo y la matriz, así como a la resistencia de las primeras. En este trabajo, se analiza la influencia que diferentes tratamientos térmicos tienen en la evolución de nuevas fases en la intercara matriz-partícula. Las muestras se prepararon por vía pulvimetalúrgica con una etapa de extrusión final. Se realizaron diferentes tratamientos térmicos abarcando un amplio espectro de temperaturas y tiempos, que dieron lugar al desarrollo de distintas fases alrededor de las partículas iniciales. Las muestras se analizaron mediante técnicas de microscopía óptica y electrónica de barrido con análisis de elementos por rayos X. Así mismo, se realizaron ensayos de microdureza en las distintas fases generadas.

  18. Lattice instability during the martensitic transformation in the high temperature shape memory alloy Zr(Cu{sub 0.5}Co{sub 0.25}Ni{sub 0.25})

    Energy Technology Data Exchange (ETDEWEB)

    Azeem, M.A. [Dept. Materials, Royal School of Mines, Imperial College, Prince Consort Road, South Kensington, London SW7 2BP (United Kingdom); Manchester X-ray Imaging Facility, University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell, Oxfordshire OX11 0FA (United Kingdom); Dye, D., E-mail: david.dye@imperial.ac.uk [Dept. Materials, Royal School of Mines, Imperial College, Prince Consort Road, South Kensington, London SW7 2BP (United Kingdom)

    2015-01-05

    Highlights: • A novel intermetallic SMA actuator based on ZrCu, nominally Zr(Cu{sub 0.5}Co{sub 0.25}Ni{sub 0.25}) is examined. • Synchrotron X-ray diffraction is used to examine the thermal transformation behaviour. • Large deviations in the lattice parameters are observed in the vicinity of transformation. • Very high actuation temperatures can be obtained, in excess of 290 °C for the martensite finish on cooling. - Abstract: The martensitic transformation on thermal cycling of the polycrystalline Zr(Cu{sub 0.5}Co{sub 0.25}Ni{sub 0.25}) high temperature shape memory alloy was examined using in situ synchrotron X-ray diffraction. A single step B2 ↔ B19{sup ′} transformation was observed with a thermal hysteresis of 161 °C and a martensite finish temperature of 294 °C. Large anisotropic lattice constrictions and dilations, up to 1.3%, were observed during the course of transformation in the B19{sup ′} martensite, but corresponding changes in the B2 austenite were not observed. The coefficients of thermal expansion in both phases were found to be quite large, 33×10{sup -6}°C{sup -1} in B2 and 39, 88 and 29 × 10{sup −6} °C{sup −1} for a{sub B19{sup ′}}, b{sub B19{sup ′}} and c{sub B19{sup ′}} respectively. Possible mechanisms governing the transformation behaviour are discussed.

  19. The effect of temperature on the structure and magnetic properties of Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} spinel nanoferrite

    Energy Technology Data Exchange (ETDEWEB)

    Abdallah, Hafiz M.I., E-mail: hafizspin@gmail.com; Moyo, Thomas; Ngema, Nokwanda

    2015-11-15

    Nanocrystalline Co{sub 0.5}Ni{sub 05}Fe{sub 2}O{sub 4} ferrite with average crystallite size of 7.6 nm and lattice constant of 0.8372 nm was synthesized via a glycol-thermal process. The structure parameters and morphology of the as-synthesized sample and annealed samples were characterized by XRD, EDX, FTIR, HRSEM and HRTEM. The hyperfine interactions, iron distribution on the tetrahedral and octahedral sites for the as-synthesized sample and samples annealed at 500 °C were deduced by Mössbauer spectroscopy measurements at 300 K. The magnetization measurements for the as-synthesized and annealed samples (300–900 °C) were obtained by a vibrating sample magnetometer on a cryogen free measurement system at different isothermal temperatures (4–300 K) in external applied magnetic fields of ±5 T. The temperature dependence of the magnetic properties such as coercive field, saturation magnetization, remanent magnetization and squareness of hysteresis loops were investigated. The sample transformed from single-domain to multi-domain configuration at particle size of about 31 nm. At 300 K, the sample annealed at 700 °C exhibits a maximum coercivity. The as-prepared sample shows a substantial increase in coercivity from 0.182 kOe at 300 K to 6.018 kOe at 4 K. - Highlights: • Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} nanoparticle ferrite was produced via a glycol-thermal. • XRD,EDX, SEM, TEM, FTIR, CFM-VSM techniques were applied to the study. • The results indicate a soft and hard magnetic behavior of the sample. • Coercivity and magnetization follow the Kneller's and Bloch's laws. • Sample transformed from single- to multi-domain magnetic structure.

  20. Surface-induced clustering in vapor deposited Co{sub 1{minus}x}Pt{sub x} and Ni{sub 1{minus}x}Pt{sub x} films (abstract)

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, A.L.; Rooney, P.W.; Tran, M.Q.; Hellman, F. [Department of Physics, University of California--San Diego, La Jolla, California 92093-0350 (United States)

    1997-04-01

    We have depostied (100), (110), and (111) oriented single-crystal and polycrystalline Co{sub 1{minus}x}Pt{sub x} (x=0.65, 0.75, 0.80) and polycrystalline Ni{sub 1{minus}x}Pt{sub x} (x=0.25, 0.50) films over a range of growth temperatures from {minus}50 to 800{degree}C. Previous work on CoPt{sub 3} films had demonstrated the correlation between Co clustering and perpendicular magnetic anisotropy. These observations motivated a model in which Co atoms cluster on the growing surface; this clustering is trapped by succeeding layers for growth temperatures below 400{degree}C, the lower limit of bulk atomic mobility. The (110) oriented samples show clustering and anisotropy identical to the (100) and (11) oriented samples despite the sign change of the surface segregation in the (110) orientation. The Ni{endash}Pt alloy system is similar to Co{endash}Pt in structure, lattice constant, and the polarizability of Pt. We have deposited Ni{sub 3}Pt films; these films have significant clustering of the magnetic species which drops off rapidly after the onset of bulk mobility at 400{degree}C. No perpendicular magnetic anisotropy is found in these films, even though interface magnetic anisotropy values in Ni/Pt multilayers have been reported as having up to 1/4 the value of Co/Pt interfaces. Finally, in order to explore whether surface clustering is a kinetic or equilibrium effect, we have varied the deposition rate of CoPt{sub 3} over three orders of magnitude at temperatures below 400{degree}C. We found no dependence of clustering or anisotropy on the deposition rate, suggesting that the clustering is not kinetically limited but is a surface equilibrium effect. {copyright} {ital 1997 American Institute of Physics.}

  1. Thermoelectric properties of composites made of Ni{sub 0.05}Mo{sub 3}Sb{sub 5.4}Te{sub 1.6} and fullerene

    Energy Technology Data Exchange (ETDEWEB)

    Nandihalli, Nagaraj [Department of Chemistry, University of Waterloo, Waterloo, ON, Canada N2L 3G1 (Canada); Lahwal, Ali; Thompson, Daniel; Holgate, Tim C.; Tritt, Terry M. [Department of Physics and Astronomy, Clemson University, Clemson, SC, USA 29634 (United States); Dassylva-Raymond, Véronique; Kiss, László I. [Département des sciences appliqués, Université du Québec à Chicoutimi, Chicoutimi, QC, Canada G7H 2B1 (Canada); Sellier, Elisabeth [CREMEM, Université de Bordeaux, F-33405 Talence (France); Gorsse, Stéphane [CNRS, Universite de Bordeaux, ICMCB, F-33600 Pessac (France); Kleinke, Holger, E-mail: kleinke@uwaterloo.ca [Department of Chemistry, University of Waterloo, Waterloo, ON, Canada N2L 3G1 (Canada)

    2013-07-15

    About 18 g of Ni{sub 0.05}Mo{sub 3}Sb{sub 5.4}Te{sub 1.6} were prepared by heating the elements in the stoichiometric ratio at 1000 K. The product was divided into four parts, and then C{sub 60} was added to three of these four parts at 1, 2, and 3 mass%, respectively. Each part was hot-pressed at 150 MPa and 923 K. The sample with 1% C{sub 60} was characterized via a Rietveld refinement and TEM analyses. Measurements of the three thermoelectric key properties revealed that the Seebeck coefficient barely depends on the carbon amount added, while both the electrical and the thermal conductivity decrease with increasing amount of carbon. Depending on the amount of C{sub 60} used and on the temperature, the thermoelectric performance was either enhanced or decreased, depending on whether the electrical conductivity decreased less or more than the thermal conductivity. At the highest temperature measured, all carbon-containing samples performed better than the unmodified bulk sample, namely up to 14%. These improvements are within the error margin, however. - Graphical abstract: Figure-of-merit of various Ni{sub 0.05}Mo{sub 3}Sb{sub 5.4}Te{sub 1.6}/C composites. - Highlights: • Composites of Mo{sub 3}(Sb,Te){sub 7} materials with C{sub 60} were synthesized and characterized. • The carbon additions form amorphous nanoparticles with sizes of the order of 50 nm. • The Seebeck effect remains basically unaffected from the carbon additions. • Electrical and thermal conductivity decrease differently with increasing carbon content. • The figure-of-merit was slightly improved, most noteworthy at higher temperatures.

  2. Magnetic structure of the kagome mixed compound (Co{sub 0.5}Ni{sub 0.5}){sub 3}V{sub 2}O{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Qureshi, N; Fuess, H [Institute for Materials Science, University of Technology, D-64287 Darmstadt (Germany); Ehrenberg, H [Institute for Complex Materials, IFW Dresden, D-01069 Dresden (Germany); Ouladdiaf, B; RodrIguez-Carvajal, J; Hansen, T C [Institut Max von Laue-Paul Langevin, 38042 Grenoble Cedex 9 (France); Wolf, Th; Meingast, C; Zhang, Q; Knafo, W; Loehneysen, H v [Research Center Karlsruhe, Institute of Solid State Physics, D-76021 Karlsruhe (Germany)], E-mail: navidq@st.tu-darmstadt.de

    2008-06-11

    We report the magnetic structure of (Co{sub 0.5}Ni{sub 0.5}){sub 3}V{sub 2}O{sub 8} (CNVO) deduced by single crystal neutron diffraction. This compound exhibits features which differ from that of its parent compounds, which are absolutely collinear along the a axis for Co{sub 3}V{sub 2}O{sub 8} (CVO) or exhibit magnetic moments predominantly in the a-b plane with small components along c in the case of Ni{sub 3}V{sub 2}O{sub 8} (NVO). The averaged magnetic moments of the statistically distributed Ni{sup 2+} and Co{sup 2+} ions in CNVO are oriented in the a-c plane and form loops of quasiferromagnetically coupled spins. These loops are connected along the a axis and separated along the c axis by cross-tie spins forming a quasiferromagnetic wave with the upper part of the respective neighbouring loops. The magnetic moments are sinusoidally modulated by the propagation vector k = (0.49,0,0) with an average amplitude of 1.59(1) {mu}{sub B} for a magnetic ion on a cross-tie site and 1.60(1) {mu}{sub B} for the spine site. In addition to neutron diffraction, specific heat and magnetization data, which confirm that the only magnetic phase transition above 1.8 K is the onset of antiferromagnetic order at T{sub N} = 7.4(1) K, are presented.

  3. Microstructural and mechanical properties analysis of an aluminium matrix composite reinforced with the amorphous alloy Al{sub 87.5}Ni{sub 4}Sm{sub 8.5} consolidated by hot extrusion; Propriedades mecanicas e microestruturais de um composito com matrix de aluminio e reforco amorfo de Al{sub 87.5}Ni{sub 4}Sm{sub 8.5} consolidado por extrusao a quente por extrusao a quente

    Energy Technology Data Exchange (ETDEWEB)

    Aliaga, L.C.R.; Bolfarini, C.; Kiminami, C.S.; Botta, W.J. [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais; Peres, M.M., E-mail: peresmm@yahoo.com.b [Universidade Federal de Itajuba (UNIFEI), Itabira, MG (Brazil)

    2010-07-01

    The aim of this work is the microstructure and the mechanical properties analysis of an aluminium matrix composite reinforced with the Al{sub 87.5}Ni{sub 4}Sm{sub 8.5} amorphous alloy. The amorphous alloy was produced by melt-spinning and fragmented in powder particles by milling. Pure aluminium power was moistured with amorphous powder in a proportion of 80:20 (% weight) and processed by milling using 350 rpm during 30 minutes for the generation of a homogeneous composite powder. This product was consolidated by extrusion at 235 deg C, ram speed of 2mm/min and extrusion ratio of 7/1, generating a compact and cylindrical bar with 3 mm of width. The result sample was characterized by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC) and by X-Ray Diffraction (XRD). Microhardness and compression tests show an improvement on the mechanical properties. (author)

  4. The fluvial evolution of the Holocene Nile Delta

    Science.gov (United States)

    Pennington, B. T.; Sturt, F.; Wilson, P.; Rowland, J.; Brown, A. G.

    2017-08-01

    The evolution of the Nile Delta, the largest delta system in the Mediterranean Sea, has both high palaeoenvironmental and archaeological significance. A dynamic model of the landscape evolution of this delta system is presented for the period c.8000-4500 cal BP. Analysis of sedimentary data and chronostratigraphic information contained within 1640 borehole records has allowed for a redefinition of the internal stratigraphy of the Holocene delta, and the construction of a four-dimensional landscape model for the delta's evolution through time. The mid-Holocene environmental evolution is characterised by a transition from an earlier set of spatially varied landscapes dominated by swampy marshland, to better-drained, more uniform floodplain environments. Archaeologically important Pleistocene inliers in the form of sandy hills protruding above the delta plain surface (known as ;turtlebacks;), also became smaller as the delta plain continued to aggrade, while the shoreline and coastal zone prograded north. These changes were forced by a decrease in the rate of relative sea-level rise under high rates of sediment-supply. This dynamic environmental evolution needs to be integrated within any discussion of the contemporary developments in the social sphere, which culminated in the emergence of the Ancient Egyptian State c.5050 cal BP.

  5. Hot deformation behavior of delta-processed superalloy 718

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y., E-mail: wangyanhit@yahoo.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); School of Aeronautics and Astronautics, Central South University, Changsha 410083 (China); Shao, W.Z.; Zhen, L.; Zhang, B.Y. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2011-03-25

    Research highlights: {yields} The peak stress for hot deformation can be described by the Z parameter. {yields} The grain size of DRX was inversely proportional to the Z parameter. {yields} The dissolution of {delta} phases was greatly accelerated under hot deformation. {yields}The {delta} phase stimulated nucleation can serve as the main DRX mechanism. - Abstract: Flow stress behavior and microstructures during hot compression of delta-processed superalloy 718 at temperatures from 950 to 1100 deg. C with strain rates of 10{sup -3} to 1 s{sup -1} were investigated by optical microscopy (OM), electron backscatter diffraction (EBSD) technique and transmission electron microscopy (TEM). The relationship between the peak stress and the deformation conditions can be expressed by a hyperbolic-sine type equation. The activation energy for the delta-processed superalloy 718 is determined to be 467 kJ/mol. The change of the dominant deformation mechanisms leads to the decrease of stress exponent and the increase of activation energy with increasing temperature. The dynamically recrystallized grain size is inversely proportional to the Zener-Hollomon (Z) parameter. It is found that the dissolution rate of {delta} phases under hot deformation conditions is much faster than that under static conditions. Dislocation, vacancy and curvature play important roles in the dissolution of {delta} phases. The main nucleation mechanisms of dynamic recrystallization (DRX) for the delta-processed superalloy 718 include the bulging of original grain boundaries and the {delta} phase stimulated DRX nucleation, which is closely related to the dissolution behavior of {delta} phases under certain deformation conditions.

  6. Primary production in the Delta: Then and now

    Science.gov (United States)

    Cloern, James E.; Robinson, April; Richey, Amy; Grenier, Letitia; Grossinger, Robin; Boyer, Katharyn E.; Burau, Jon; Canuel, Elizabeth A.; DeGeorge, John F.; Drexler, Judith Z.; Enright, Chris; Howe, Emily R.; Kneib, Ronald; Mueller-Solger, Anke; Naiman, Robert J.; Pinckney, James L.; Safran, Samuel M.; Schoellhamer, David H.; Simenstad, Charles A.

    2016-01-01

    To evaluate the role of restoration in the recovery of the Delta ecosystem, we need to have clear targets and performance measures that directly assess ecosystem function. Primary production is a crucial ecosystem process, which directly limits the quality and quantity of food available for secondary consumers such as invertebrates and fish. The Delta has a low rate of primary production, but it is unclear whether this was always the case. Recent analyses from the Historical Ecology Team and Delta Landscapes Project provide quantitative comparisons of the areal extent of 14 habitat types in the modern Delta versus the historical Delta (pre-1850). Here we describe an approach for using these metrics of land use change to: (1) produce the first quantitative estimates of how Delta primary production and the relative contributions from five different producer groups have been altered by large-scale drainage and conversion to agriculture; (2) convert these production estimates into a common currency so the contributions of each producer group reflect their food quality and efficiency of transfer to consumers; and (3) use simple models to discover how tidal exchange between marshes and open water influences primary production and its consumption. Application of this approach could inform Delta management in two ways. First, it would provide a quantitative estimate of how large-scale conversion to agriculture has altered the Delta's capacity to produce food for native biota. Second, it would provide restoration practitioners with a new approach—based on ecosystem function—to evaluate the success of restoration projects and gauge the trajectory of ecological recovery in the Delta region.

  7. Holocene evolution of the western Orinoco Delta, Venezuela

    Science.gov (United States)

    Aslan, A.; White, W.A.; Warne, A.G.; Guevara, E.H.

    2003-01-01

    The pristine nature of the Orinoco Delta of eastern Venezuela provides unique opportunities to study the geologic processes and environments of a major tropical delta. Remote-sensing images, shallow cores, and radiocarbon-dating of organic remains form the basis for describing deltaic environments and interpreting the Holocene history of the delta. The Orinoco Delta can be subdivided into two major sectors. The southeast sector is dominated by the Rio Grande-the principal distributary-and complex networks of anastomosing fluvial and tidal channels. The abundance of siliciclastic deposits suggests that fluvial processes such as over-bank flooding strongly influence this part of the delta. In contrast, the northwest sector is represented by few major distributaries, and overbank sedimentation is less widespread relative to the southeast sector. Peat is abundant and occurs in herbaceous and forested swamps that are individually up to 200 km2 in area. Northwest-directed littoral currents transport large volumes of suspended sediment and produce prominent mudcapes along the northwest coast. Mapping of surface sediments, vegetation, and major landforms identified four principal geomorphic systems within the western delta plain: (1) distributary channels, (2) interdistributary flood basins, (3) fluvial-marine transitional environments, and (4) marine-influenced coastal environments. Coring and radiocarbon dating of deltaic deposits show that the northern delta shoreline has prograded 20-30 km during the late Holocene sea-level highstand. Progradation has been accomplished by a combination of distributary avulsion and mudcape progradation. This style of deltaic progradation differs markedly from other deltas such as the Mississippi where distributary avulsion leads to coastal land loss, rather than shoreline progradation. The key difference is that the Orinoco Delta coastal zone receives prodigious amounts of sediment from northwest-moving littoral currents that transport

  8. Regional pole assignment for uncertain delta-operator systems

    Institute of Scientific and Technical Information of China (English)

    Man LIU; Yuanwei JING; Siying ZHANG

    2004-01-01

    The pole assignment in a specified disk by state feedback for uncertain delta-operator systems is studied.By making use of algebra Riccati equations,a sufficient and necessary condition of pole assignment for a kind of parameter uncertain delta-operator system in a specified disk by state feedback is presented.And the design method of state feedback controller is also developed.The proposed method can unify some previous related results of continuous and discrete time systems into the delta framework.The efficiency of the design method is illustrated by a numerical example.

  9. Electromagnetic form factors of the Delta with D-waves

    CERN Document Server

    Ramalho, G; Gross, Franz

    2010-01-01

    The electromagnetic form factors of the Delta baryon are evaluated within the framework of a covariant spectator quark model, where S and D-states are included in the $\\Delta$ wave function. We predict all the four Delta multipole form factors: the electric charge GE0, the magnetic dipole GM1, the electric quadrupole GE2 and the magnetic octupole GM3. We compare our predictions with other theoretical calculations. Our results are compatible with the available experimental data and recent lattice QCD data.

  10. Late quaternary evolution of the Orinoco Delta, Venezuela

    Science.gov (United States)

    Warne, A.G.; Guevara, E.H.; Aslan, A.

    2002-01-01

    The modern Orinoco Delta is the latest of a series of stacked deltas that have infilled the Eastern Venezuelan Basin (EVB) since the Oligocene. During the late Pleistocene sea-level lowstand (20,000 to 16,000 yrs BP), bedrock control points at the position of the present delta apex prevented the river channel from incising as deeply as many other major river systems. Shallow seismic data indicate that the late Pleistocene Orinoco incised into the present continental shelf, where it formed a braided-river complex that transported sediment to a series of shelf-edge deltas. As sea level rose from 16,000 to 9,500 yrs BP, the Orinoco shoreline shifted rapidly landward, causing shallow-marine waves and currents to form a widespread transgressive sand unit. Decelerating sea-level rise and a warmer, wetter climate during the early Holocene (9,500 to 6,000 yrs BP) induced delta development within the relatively quiet-water environment of the EVB embayment. Sea level approached its present stand in the middle Holocene (6,000 to 3,000 yrs BP), and the Orinoco coast prograded, broadening the delta plain and infilling the EVB embayment. Significant quantities of Amazon sediment began to be transported to the Orinoco coast by littoral currents. Continued progradation in the late Holocene caused the constriction at Boca de Serpientes to alter nearshore and shelf hydrodynamics and subdivide the submarine delta into two distinct areas: the Atlantic shelf and the Gulf of Paria. The increased influence of littoral currents along the coast promoted mudcape development. Because most of the water and sediment were transported across the delta plain through the Rio Grande distributary in the southern delta, much of the central and northwestern delta plain became sediment starved, promoting widespread accumulation of peat deposits. Human impacts on the delta are mostly associated with the Volca??n Dam on Can??o Manamo. However, human activities have had relatively little effect on the

  11. On generalized {delta}-semiclosed sets in topological spaces

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Han [Division of Mathematical Sciences, Pukyong National University, Pusan 608-737 (Korea, Republic of)]. E-mail: jihpark@pknu.ac.kr; Song, Dae Seob [Division of Mathematical Sciences, Pukyong National University, Pusan 608-737 (Korea, Republic of); Saadati, Reza [Department of Mathematics, and Computer Science, Amirkabir University of Technology, 424 Hafez Avenue, Tehran 15914 (Iran, Islamic Republic of) and Department of Mathematics, Amol Islamic Azad University, Amol 46176-54553 (Iran, Islamic Republic of)]. E-mail: rsaadati@eml.cc

    2007-08-15

    The aim of this paper is to introduce the class of g{delta}s-closed sets and obtain the characterizations of T {sub 3/4} space due to Dontchev and Ganster [Dontchev J, Ganster M. On {delta}-generalized closed set and T {sub 3/4}-spaces. Mem Fac Sci Kochi Univ Ser A (Math) 1996;17:15-31]. We also introduce the notion of g{delta}s-continuity and investigate the relationships between it and other types of continuity.

  12. Is there a self-organization principle of river deltas?

    Science.gov (United States)

    Tejedor, Alejandro; Longjas, Anthony; Foufoula-Georgiou, Efi

    2017-04-01

    River deltas are known to possess a complex topological and flux-partitioning structure which has recently been quantified using spectral graph theory [Tejedor et al., 2015a,b]. By analysis of real and simulated deltas it has also been shown that there is promise in formalizing relationships between this topo-dynamic delta structure and the underlying delta forming processes [e.g., Tejedor et al., 2016]. The question we pose here is whether there exists a first order organizational principle behind the self-organization of river deltas and whether this principle can be unraveled from the co-evolving topo-dynamic structure encoded in the delta planform. To answer this question, we introduce a new metric, the nonlocal Entropy Rate (nER) that captures the information content of a delta network in terms of the degree of uncertainty in delivering fluxes from any point of the network to the shoreline. We hypothesize that if the "guiding principle" of undisturbed deltas is to efficiently and robustly build land by increasing the diversity of their flux pathways over the delta plane, then they would exhibit maximum nonlocal Entropy Rate at states at which geometry and flux dynamics are at equilibrium. At the same time, their nER would be non-optimal at transient states, such as before and after major avulsions during which topology and dynamics adjust to each other to reach a new equilibrium state. We will present our results for field and simulated deltas, which confirm this hypothesis and open up new ways of thinking about self-organization, complexity and robustness in river deltas. One particular connection of interest might have important implications since entropy rate and resilience are related by the fluctuation theorem [Demetrius and Manke, 2005], and therefore our results suggest that deltas might in fact self-organize to maximize their resilience to structural and dynamic perturbations. References: Tejedor, A., A. Longjas, I. Zaliapin, and E. Foufoula

  13. Monte Carlo simulations of the stability of delta-Pu

    CERN Document Server

    Landa, A; Ruban, A

    2003-01-01

    The transition temperature (T sub c) for delta-Pu has been calculated for the first time. A Monte Carlo method is employed for this purpose and the effective cluster interactions are obtained from first-principles calculations incorporated with the Connolly-Williams and generalized perturbation methods. It is found that at T sub c approx 548 K, delta-Pu undergoes transformation from a disordered magnetic state to a structure with an antiferromagnetic spin alignment that is mechanically unstable with respect to tetragonal distortion. The calculated transition temperature is in good agreement with the temperature measured at the gamma -> delta transition (593 K). (letter to the editor)

  14. Genomic organization of the human T-cell antigen-receptor alpha/delta locus.

    Science.gov (United States)

    Satyanarayana, K; Hata, S; Devlin, P; Roncarolo, M G; De Vries, J E; Spits, H; Strominger, J L; Krangel, M S

    1988-11-01

    Two clusters of overlapping cosmid clones comprising about 100 kilobases (kb) at the human T-cell antigen-receptor alpha/delta locus were isolated from a genomic library. The structure of the germ-line V delta 1 variable gene segment was determined. V delta 1 is located 8.5 kb downstream of the V alpha 13.1 gene segment, and both V segments are arranged in the same transcriptional orientation. The V alpha 17.1 segment is located between V delta 1 and the D delta, J delta, C delta region (containing the diversity, joining, and constant gene segments). Thus, V delta and V alpha segments are interspersed along the chromosome. The germ-line organization of the D delta 2, J delta 1, and J delta 2 segments was determined. Linkage of C delta to the J alpha region was established by identification of J alpha segments within 20 kb downstream of C delta. The organization of the locus was also analyzed by field-inversion gel electrophoresis. The unrearranged V delta 1 and D delta, J delta, C delta regions are quite distant from each other, apparently separated by a minimum of 175-180 kb.

  15. Expression profiling of peroxisome proliferator-activated receptor-delta (PPAR-delta) in mouse tissues using tissue microarray.

    Science.gov (United States)

    Higashiyama, Hiroyuki; Billin, Andrew N; Okamoto, Yuji; Kinoshita, Mine; Asano, Satoshi

    2007-05-01

    Peroxisome proliferator-activated receptor-delta (PPAR-delta) is known as a transcription factor involved in the regulation of fatty acid oxidation and mitochondrial biogenesis in several tissues, such as skeletal muscle, liver and adipose tissues. In this study, to elucidate systemic physiological functions of PPAR-delta, we examined the tissue distribution and localization of PPAR-delta in adult mouse tissues using tissue microarray (TMA)-based immunohistochemistry. PPAR-delta positive signals were observed on variety of tissues/cells in multiple systems including cardiovascular, urinary, respiratory, digestive, endocrine, nervous, hematopoietic, immune, musculoskeletal, sensory and reproductive organ systems. In these organs, PPAR-delta immunoreactivity was generally localized on the nucleus, although cytoplasmic localization was observed on several cell types including neurons in the nervous system and cells of the islet of Langerhans. These expression profiling data implicate various physiological roles of PPAR-delta in multiple organ systems. TMA-based immunohistochemistry enables to profile comprehensive protein localization and distribution in a high-throughput manner.

  16. Sharecropping Contract Experience in Delta State, Nigeria

    Institute of Scientific and Technical Information of China (English)

    Albert Ukaro Ofuoku

    2015-01-01

    Sharecropping has been an age long practice from ancient times. Some scholars saw the practice as being exploitative of the tenants, yet it is still being practiced. The reasons behind it continual practice need to be unveiled. This study was therefore conducted to examine the sharecropping contract experience in Delta State, Nigeria. The landlords decided to practice sharecropping as a result of emigration of their household members, farm size and cost of labours, some of them gave age and their primary occupation as factors for their decisions to opt for sharecropping arrangement. The yields were shared on the basis of 60% for the landlord to 40% for the tenant. The landlords provided all the equipment and inputs, while the tenant's carried out all the farm operations. They faced the constraints of stress, but were able to cope with them, because of hospitals and health centres nearby. The result of the test of hypothesis confirmed the reasons given for deciding on sharecropping arrangement. It was concluded that sharecropping was not exploitative. It was recommended that the practice of sharecropping should be encouraged and not diversified into other sources of livelihood should do so.

  17. The DELTA 181 lithium thionyl chloride battery

    Science.gov (United States)

    Sullivan, Ralph M.; Brown, Lawrence E.; Leigh, A. P.

    In 1986, the Johns Hopkins University/Applied Physics Laboratory (JHU/APL) undertook the development of a sensor module for the DELTA 181 spacecraft, a low earth orbit (LEO) mission of less than two months duration. A large lithium thionyl chloride battery was developed as the spacecraft's primary power source, the first known such use for this technology. The exceptionally high energy density of the lithium thionyl chloride cell was the primary driver for its use, resulting in a completed battery with a specific energy density of 120 Wh/lb. Safety requirements became the primary driver shaping all aspects of the power system design and development due to concerns about the potential hazards of this relatively new, high-energy technology. However, the program was completed without incident. The spacecraft was launched on February 8, 1988, from Kennedy Space Center (KSC) with over 60,000 Wh of battery energy. It reentered on April 2, 1988, still operating after 55 days, providing a successful, practical, and visible demonstration of the use of this technology for spacecraft applications.

  18. Delta Haptic Device as a nanomanipulator

    Science.gov (United States)

    Grange, Sebastien; Conti, Francois; Helmer, Patrick; Rouiller, Patrice; Baur, Charles

    2001-10-01

    At the EPFL, we have developed a force-feedback device and control architecture for high-end research and industrial applications. The Delta Haptic Device (DHD) consists of a 6 degrees-of-freedom (DOF) mecatronic device driven by a PC. Several experiments have been carried out in the fields of manipulation and simulation to assess the dramatic improvement haptic information brings to manipulation. This system is particularly well suited for scaled manipulation such as micro-, nano- and biomanipulation. Not only can it perform geometric and force scaling, but it can also include fairly complex physical models into the control loop to assist manipulation and enhance human understanding of the environment. To demonstrate this ability, we are currently interfacing our DHD with an atomic force microscope (AFM). In a first stage, we will be able to feel in real-time the topology of a given sample while visualizing it in 3D. The aim of the project is to make manipulation of carbon nanotubes possible by including physical models of such nanotubes behavior into the control loop, thus allowing humans to control complex structures. In this paper, we give a brief description of our device and present preliminary results of its interfacing with the AFM.

  19. Delta Morphodynamics Matters! Ecosystem Services, Poverty and Morphodynamic Change in the Ganges-Brahmaputra Mega-Delta

    Science.gov (United States)

    Nicholls, R. J.; Adger, N.; Allan, A.; Darby, S. E.; Hutton, C.; Matthews, Z.; Rahman, M.; Whitehead, P. G.; Wolf, J.

    2013-12-01

    The world's deltas are probably the most vulnerable type of coastal environment, and they face multiple stresses in the coming decades. These stresses include, amongst others, local drivers due to land subsidence, population growth and urbanisation within the deltas, regional drivers due to changes in catchment management (e.g. upstream land use and dam construction), as well as global climate change impacts such as sea-level rise. At the same time, the ecosystem services of river deltas support high population densities, with around 14% of the global population inhabiting deltas. A large proportion of these people experience extremes of poverty and they are therefore severely exposed to vulnerability from environmental and ecological stress and degradation. In areas close to or below the poverty boundary, both subsistence and cash elements of the economy tend to rely disproportionately heavily on ecosystem services which underpin livelihoods. Therefore, to sustainably manage delta environments they must be viewed as complex social-environmental systems where change is only partially driven by physical drivers such as sea level rise and climate change, and human-induced development activities are also critical. Here we outline a new conceptual framework for the development of methods to understand and characterise the key drivers of change in ecosystem services that affect the environment and economic status of populous deltas, focusing specifically on the Ganges-Brahmaputra-Meghna (GBM) mega-delta. The GBM delta is characterised by densely populated coastal lowlands with significant poverty, with livelihoods supported to a large extent by natural ecosystems such as the Sunderbahns (the largest mangrove forest in the world). However, the GBM delta is under severe development pressure due to many growing cities. At present the importance of ecosystems services to poverty and livelihoods is poorly understood. This is due to due to the complexity of interactions

  20. EAARL Coastal Topography--Pearl River Delta 2008: First Surface

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A first surface elevation map (also known as a Digital Elevation Model, or DEM) of the Pearl River Delta in Louisiana and Mississippi was produced from remotely...

  1. EAARL Coastal Topography--Pearl River Delta 2008: Bare Earth

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A bare earth elevation map (also known as a Digital Elevation Model, or DEM) of the Pearl River Delta in Louisiana and Mississippi was produced from remotely sensed,...

  2. GPC Using a Delta-Domain Emulator-Based Approach

    DEFF Research Database (Denmark)

    Lauritsen, Morten Bach; Jensen, Morten Rostgaard; Poulsen, Niels Kjølstad

    1997-01-01

    This paper describes new approaches to generalized predictive control formulated in the delta (delta) domain. A new delta-domain version of the continuous-time emulator-based predictor is presented. It is shown to contain the optimal discrete-time predictor based on incomplete information...... as a special case. Usually, a good estimate is obtained in a much longer range of samples than obtained by the optimal predictor of the same complexity. This is particularly advantageous at fast sampling rates where a `conventional' predictor is bound to become very computationally demanding. Two controllers...... are considered: one having a well-defined limit as the sampling period tends to zero, the other being a close approximation to the conventional discrete-time GPC. Both algorithms are discrete in nature and well-suited for adaptive control. The fact that delta-domain models are used does not introduce...

  3. Yukon Delta National Wildlife Refuge : Narrative Report : Calendar Year 1990

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Yukon Delta National Wildlife Refuge outlines Refuge accomplishments during the 1990 calendar year. The report begins with a summary...

  4. Delta- Sigma Modulator with Signal Dependant Feedback Gain

    National Research Council Canada - National Science Library

    K.Diwakar; V.Vinoth Kumar

    2015-01-01

    Higher order Delta-Sigma Modulator (DSM) is basically an unstable system. The approximate conditions for stability cannot be used for the design of a DSM for industrial applications where risk is involved...

  5. A High Performance Delta-Sigma Modulator for Neurosensing

    National Research Council Canada - National Science Library

    Xu, Jian; Zhao, Menglian; Wu, Xiaobo; Islam, Md Kafiul; Yang, Zhi

    2015-01-01

    ... to achieve and would require excessive circuit area and power for implementation. In this paper, we present a high performance Delta-Sigma modulator along with several design techniques and enabling blocks to reduce circuit area and power...

  6. An integrated delta-sigma based IIR filter

    Science.gov (United States)

    Au, Dennis Kin-Wah

    Delta-sigma based infinite impulse response (IIR) filters are a recently developed circuit technique for efficiently realizing IIR filters operating directly on oversampled delta-sigma modulated signals. The design and single-chip implementation of a fifth-order delta-sigma based IIR filter are described. The filter coefficients are fully programmable and with the use of a structure that is inherently scaled for dynamic range, good filter performance is maintained over a wide variety of transfer functions. To eliminate multi-bit multiplications, five second-order digital delta-sigma modulators were used and dynamic range improvement was obtained through the use of multi-bit quantizers in these modulators. The filter was implemented as a very large scale integration chip using 1.2 micron complementary metal oxide semiconductor technology, occupying an area of 4,355 by 5,962 square microns. Simulations indicate that the clock range should operate up to 45 MHz.

  7. Yukon Delta National Wildlife Refuge coastal survey, final report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Aerial surveys were conducted along the coastline of the Yukon Delta National Wildlife Refuge to determine the distribution and abundance of waterfowl and...

  8. Alternative Interpretation for the Eberswalde Delta, Holden NE Crater, Mars

    Science.gov (United States)

    Fedo, C. M.; Finkelstein, D. B.; Moersch, J. E.

    2008-03-01

    Examination of HiRISE images from the Eberswalde Delta reveal that it is hard to identify sedimentologic and stratigraphic components of a fluvio-deltaic system, leaving open alternative interpretations for the origin of the strata and geomorphpology.

  9. Linear delta expansion technique for the solution of anharmonic oscillations

    Indian Academy of Sciences (India)

    P K Bera; J Datta

    2007-01-01

    The linear delta expansion technique has been developed for solving the differential equation of motion for symmetric and asymmetric anharmonic oscillators. We have also demonstrated the sophistication and simplicity of this new perturbation technique.

  10. Lead analysis of waterfowl from Yukon Delta NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — In 1995, WAES received funds from the Yukon Delta Ecosystem Team to analyze livers of waterfowl, other than spectacled eiders, for lead concentrations. Nineteen...