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Sample records for c14 laves phase

  1. Development of C14 laves phase alloy for battery with good high-rate dischargeability; Koritsu hoden tokusei no sugureta denchiyo C14gata laves sogokin no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, H.; Wakao, S. [Tokai Univ., Tokyo (Japan); Mori, K. [Daido Steel Co. Ltd., Aichi (Japan)

    1998-07-05

    Authors have studied to develop Zr-Ti-V-Ni-Mn-Co(Fe,Mo) laves phase alloys for Ni-MH secondary batteries. The object of this study was to develop C14 laves phase alloys with good high-rate dischargeability. Alloys with enthalpy -triangleH for hydride formation in the range of 35 to 37 kJ/molH2 were designed using relations among the enthalpy, cell volume, and average atomic radius. The agreement between designed values and experimental results, and the differences of the enthalpy, cell volume and electrochemical characteristics, alloys with and without heat treatment, were studied. This paper describes first the principle of designing the alloys. Then the method of the experiment was explained The results and considerations were stated under the headings, i.e. Percentage of phase and cell volume, Enthalpy for hydride formation, Electrochemical characteristics of heat treated alloys and the same of as-cast alloys. 12 refs., 5 figs., 3 tabs.

  2. Correlation between crystal structure and electrochemical properties of C14 Laves-phase alloys

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    Nakano, H. [Tokai Univ., Shizuoka (Japan). Sch. of High-Technol. for Human Welfare; Wakao, S. [Tokai University, 3-10-22 Daita, Setagaya, Tokyo, 155 (Japan); Shimizu, T. [Daido Steel Co., Ltd., 2-30 Daido, Minami, Nagoya, 457 (Japan)

    1997-05-20

    By examining the relationships between the structure and the thermodynamic and electrochemical properties for Zr{sub 1-x}Ti{sub x}(V{sub 0.1}Mn{sub a}Ni{sub b}E{sub c}){sub {alpha}} (x=0.1-0.3, a=0.28-0.30, b=0.50-0.57, c=0.05-0.12, {alpha}=1.6-1.8, E=Co, Fe, Mo) alloy system with C14 type structure, the following results were obtained. The partial molar enthalpy for hydride formation decreases linearly with decreasing cell volume V{sub C14} of the C14 phase. This means that the hydride becomes unstable with decreasing V{sub C14}, as is the case for the C15 type structure. Both -{Delta}H and V{sub C14} decrease with decreasing average atomic radius of the alloy, and the correlation coefficient was sufficiently high for each value. The discharge capacity and dischargeability also depend on -{Delta}H and V{sub C14}. (orig.) 15 refs.

  3. The native point defects of ternary C14 Laves phase Mg2Cu3Si: Ab initio investigation

    Science.gov (United States)

    Shi, Xue-Feng; Yao, Xiao-Jing; Yang, Yan; Tang, Bi-Yu

    2017-10-01

    Nine possible native point defects in ternary C14 Laves phase Mg2Cu3Si are investigated from ab initio calculation based on density function theory. The two-dimensional phase diagram of chemical potentials is determined, and then defect formation energy is calculated. The energetic results show that CuSi and CuMg are more favorable over a broad range of chemical potentials. The formation enthalpies for defective Mg2Cu3Si also demonstrate the same stability. Local distortions around point defects increase from SiCu to SiMg, showing that the polyhedral symmetry and coordination number for constituent atoms will affect the structure of defects. The electronic structure shows the strong (Cu, Si)-Si covalent bonding, also indicates that the CuMg is favorable because the weak Mg-Cu bonding is replaced by the strong Cu-Cu bonding, whereas MgCu and MgSi are unfavorable because the strong Cu-Si bonding is replaced by the weak Mg-(Cu, Si) bonding.

  4. STRUCTURAL AND THERMAL PROPERTIES OF FE2(ZR,NB SYSTEM IN C15, C14 AND C36 LAVES PHASES: FIRST-PRINCIPLES STUDY

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    L RABAHI

    2015-06-01

    Full Text Available The pseudopotential method (PP, based on Density Functional Theory (DFT using the Generalized Gradient Approximation (GGA was applied to investigate the Fe2(Zr, Nb system within the three Laves phases structures: Cubic C15, Hexagonal C14 and C36. The effects of Nb concentration on structural, thermal and stability of the system were studied. The lattice parameters and bulk modulus of the three phases were predicted and showed a good agreement with the available experimental data. The rigidity of the Fe2Nb was higher than the Fe2Zr one for C15, C14 and C36. The energetic phase diagram of the systems was also established by determining the heat formation of the different phases. The obtained results showed that the Laves phases have close formation energies which suggests that the C15, C14 and C36 phases can co-exist at low-temperature. Finally, the temperature effect on the structural parameters, thermal expansions, heat capacities and Debye temperatures are determined from the non-equilibrium Gibbs functions and discussed accordingly.

  5. Structural, elastic and electronic properties of C14-type Al{sub 2}M (M=Mg, Ca, Sr and Ba) Laves phases

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    Lishi, Ma; Yonghua, Duan, E-mail: duanyh@kmust.edu.cn; Runyue, Li

    2017-02-15

    The structural and mechanical properties, Debye temperatures and anisotropic sound velocities of the Laves phases Al{sub 2}M (M=Mg, Ca, Sr and Ba) with C14-type structure were investigated using the first-principles corresponding calculations. The corresponding calculated structural parameters and formation enthalpies are in good agreement with the available theoretical values, and Al{sub 2}Ca has the best phase stability. The mechanical properties, including elastic constants, bulk modulus B, shear modulus G, Young’s modulus E, and Poisson ratio ν, were deduced within the Voigt-Reuss-Hill approximation. The brittleness and ductility were estimated by the values of Poisson ratio, B/G and Cauchy pressure. Moreover, the elastic anisotropy was investigated by calculating and discussing several anisotropy indexes. Finally, the electronic structures were used to illustrate the bonding characteristics of C14-Al{sub 2}M (M=Mg, Ca, Sr and Ba) phases.

  6. Reaction of hydrogen with the Laves phase (C14) TiCr{sub 1.78-x}Mn{sub x} compounds

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    Agresti, F. [Universita di Padova, Dipartimento di Ingegneria Meccanica, Settore Materiali and CNISM, via Marzolo 9, 35131 Padova (Italy); Lo Russo, S. [Universita di Padova, Dipartimento di Fisica and CNISM, via Marzolo 8, 35131 Padova (Italy); Maddalena, A.; Principi, G. [Universita di Padova, Dipartimento di Ingegneria Meccanica, Settore Materiali and CNISM, via Marzolo 9, 35131 Padova (Italy); Mazzolai, G. [Universita di Perugia, Dipartimento di Fisica, Via A. Pascoli 5, 06100 Perugia (Italy); Universita Telematica e-Campus, Via Isimbardi 10, Novedrate (Colombia) (Italy); Coluzzi, B.; Biscarini, A. [Universita di Perugia, Dipartimento di Fisica, Via A. Pascoli 5, 06100 Perugia (Italy); Mazzolai, F.M., E-mail: fabio.mazzolai@fisica.unipg.it [Universita di Perugia, Dipartimento di Fisica, Via A. Pascoli 5, 06100 Perugia (Italy); Tuissi, A. [Istituto per l' Energia e le Interfasi, CNR-IENI, C.so Promessi Sposi, 29, Lecco (Italy)

    2009-09-15

    The lattice constants a and c of the as cast hexagonal (C14) Laves phase TiCr{sub 1.78-x}Mn{sub x} (x = 0, 0.4, 0.6 and 0.8) have been measured by X-ray diffraction at room temperature as a function of the Mn content. It has been found that a decreases with increasing x while c remains almost unchanged. Being this alloy interesting as material for solid state hydrogen storage, pressure-composition isotherms have been traced on desorption mode for the H{sub 2} gas pressure and temperature varying from 10 to 0.01 MPa and from 209 to 307 K, respectively. From the temperature dependence of the plateau pressure the molar quantities {Delta}H-bar{sub H{sub 2}} and {Delta}S-bar{sub H{sub 2}} associated with the hydride decomposition have been determined as a function of the Mn content. With increasing x, both {Delta}H-bar{sub H{sub 2}} and {Delta}S-bar{sub H{sub 2}} progressively decrease, and the desorption pressure initially decreases (for x {<=} 0.4) then slightly increases. At the same time, the pseudo-plateaus become flatter.

  7. Point Defects in Binary Laves-Phase Alloys

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    Liaw, P.K.; Liu, C.T.; Pike, L.M.; Zhu, J.H.

    1999-01-11

    Point defects in the binary C15 NbCrQ and NbCoz, and C 14 NbFe2 systems on both sides of stoichiometry were studied by both bulk density and X-ray Iattiee parameter measurements. It was found that the vacancy concentrations in these systems after quenching from 1000"C are essentially zero. The constitutional defects on both sides of stoichiometry for these systems were found to be of the anti-site type in comparison with the model predictions. Thermal vacancies exhibiting a maximum at the stoichiometric composition were obtained in NbCr2 Laves phase alloys after quenching from 1400"C. However, there are essentially no thermal vacancies in NbFe2 alloys after quenching from 1300oC. Anti-site hardening was found on both sides of stoichiometry for all the tie Laves phase systems studied, while the thermal vacancies in NbCr2 alloys quenched from 1400'C were found to soften the Laves phase. The anti-site hardening of the Laves phases is similar to that of the B2 compounds and the thermal vacancy softening is unique to the Laves phase. Neither the anti-site defects nor the thermal vacancies affect the fracture toughness of the Laves phases significantly.

  8. Ferromagnetism in Laves-phase WFe2 nanoparticles

    Directory of Open Access Journals (Sweden)

    M. A. Koten

    2015-07-01

    Full Text Available While rare-earth based Laves phases are known to exhibit large magnetostriction, the magnetic properties of some binary Laves phases containing transition metals alone are not well known. This is because many of these compounds contain refractory elements that complicate melt processing due to high melting temperatures and extensive phase separation. Here, phase-pure WFe2 nanoclusters, with the hexagonal C14 Laves structure, were deposited via inert gas condensation, allowing for the first known measurement of ferromagnetism in this phase, with MS of 26.4 emu/g (346 emu/cm3 and a KU of 286 kerg/cm3, at 10 K, and a TC of 550 K.

  9. Electron concentration and phase stability in NbCr2-based Laves phase alloys

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    Zhu, J.H.; Liaw, P.K. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Liu, C.T. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-05-12

    Phase stability in NbCr{sub 2}-based transition-metal Laves phases was studied, based on the data reported for binary X-Cr, Nb-X, and ternary Nb-Cr-X phase diagrams. It was shown that when the atomic size ratios are kept identical, the average electron concentration factor, e/a, is the dominating factor in controlling the phase stability of NbCr{sub 2}-based transition-metal Laves phases. The e/a ratios for different Laves polytypes were determined as followed: with e/a < 5.76, the C15 structure is stabilized; at an e/a range of 5.88--7.53, the C14 structure is stabilized; with e/a > 7.65, the C15 structure is stabilized again. A further increase in the electron concentration factor (e/a > 8) leads to the disordering of the alloy. The electron concentration effect on the phase stability of Mg-based Laves phases and transition-metal A{sub 3}B intermetallic compounds is also reviewed and compared with the present observations in transition-metal Laves phases. In order to verify the e/a/phase stability relationship experimentally, additions of Cu (with e/a = 11) were selected to replace Cr in the NbCr{sub 2} Laves phase. Experimental results for the ternary Nb-Cr-Cu system are reported and discussed in terms of the correlation between the e/a ratio and phase stability in NbCr{sub 2}-based Laves phases. A new phase was found, which has an average composition of Nb-47Cr-3Cu. Within the solubility limit, the electron concentration and phase stability relationship is obeyed in the Nb-Cr-Cu system.

  10. Influence of initial thermomechanical treatment on high temperature properties of laves phase strengthened ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Talik, Michal

    2016-07-01

    The aim of this work was to design 17 wt%Cr Laves phase strengthened HiperFer (High performance Ferrite) steels and evaluate their properties. This class of steel is supposed to be used in Advanced Ultra Super Critical power plants. Such cycles exhibit higher efficiency and are environmentally friendly, but improved materials with high resistance to reside/steam oxidation and sufficient creep strength are required. The work focused on the characterization of creep properties of 17Cr2.5W0.5Nb0.25Si heat resistant steel. Small batches of steels with nominal compositions of 17Cr3W0.5Nb0.25Si and 17Cr3W0.9Nb0.25Si were used to analyze the influence of chemical composition on the precipitation behaviour in comparison to 17Cr2.5W0.5Nb0.25Si steel. Creep strength of HiperFer steels is ensured by ne dispersion of thermodynamically stable Laves phase particles, while maintaining high corrosion resistance by a relatively high chromium content. Design of HiperFer steels was accomplished by thermodynamic modeling (Thermocalc) with the main tasks of elimination of the unwelcome brittle (Fe,Cr)-σ phase and maximization of the content of the strengthening C14 Fe{sub 2}Nb type Laves phase particles. Long term annealing experiments of all HiperFer steels were performed at 650 C in order to evaluate the role of chemical composition and initial thermo-mechanical treatment state on precipitation behaviour. Laves phase particles formed quickly after few hours and the size of precipitates did not change significantly within 1,000 hours. The observed development of Laves phase particles was compared with thermodynamical calculations (TC-Prisma). The creep properties of 17Cr2.5W0.5Nb0.25Si steel in different initial thermo-mechanical treatment states were tested at 650 C. The influence of different cold rolling procedures, and heat treatments was investigated. Increased cold rolling deformation had a positive effect resulting not only from work hardening, but from the acceleration of

  11. Study of fatigue and fracture behavior of NbCr{sub 2}-based alloys and intermetallic materials: Phase stability in NbCr{sub 2} Laves phase alloys

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    Zhu, J.H.; Liaw, P.K. [Univ. of Tennessee, Knoxville, TN (United States); Liu, C.T. [Oak Ridge National Lab., TN (United States)

    1996-08-01

    Phase stability in NbCr{sub 2}-based transition-metal Laves phases is studied in this paper, using data from binary X-Cr, Nb-X, and ternary Nb-Cr-X phase diagrams. It was shown that when the atomic size ratios are kept identical, the average electron concentration factor (e/a = the average number of electrons per atom outside the closed shells of the component atoms) is the determinate factor in controlling the phase stability of NbCr{sub 2}-based transition-metal Laves phases. The e/a ratios for different Laves phase structures were determined as follows: with e/a < 5.76, the C15 structure is stabilized; at an e/a range of 5.88-7.53, the C14 structure is stabilized; with e/a > 7.65, the C15 structure was stabilized again. A further increase in the electron concentration factor (e/a > 8) leads to the disordering of the alloy. The electron concentration effect on the phase stability of transition-metal A{sub 3}B intermetallic compounds and Mg-based Laves phases is also reviewed and compared with the present observations in transition-metal Laves phases.

  12. Role of copper on Laves phase morphology in 9-12%Cr steels

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson; Liu, Fang

    2017-01-01

    In this work the Laves phase was found to appear in two different morphologies, namely granular shapes and in an elongated shape. No difference in crystallography could be detected between these morphologies. The Laves phase was only observed in its elongated form in Cu-containing steels, where i...

  13. Summary of workshop on high temperature materials based on Laves phases

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-08-01

    The Offices of Fossil Energy and Basic Energy Sciences of the Department of Energy jointly sponsored the Workshop on High Temperature Materials Based on Laves Phases in conjunction with the Tenth Annual Conference on Fossil Energy Materials held at the Radisson Summit Hill Hotel in Knoxville, Tennessee on May 14-16, 1996. The objective of this workshop was to review the current status and to address critical issues in the development of new-generation high-temperature structural materials based on Laves phases. The one-day workshop included two sessions of overview presentations and a session of discussion on critical scientific and technological issues. The Laves phases represent an abundant class of intermetallic alloys with possible high-temperature structural applications. Laves phases form at or near the AB{sub 2} composition, and there are over 360 binary Laves phases. The ability of these alloys to dissolve considerable amounts of ternary alloying additions provides over 900 combined binary and ternary Laves phases. Many Laves phases have unique properties which make them attractive for high-temperature structural use. At half their homologous temperature, they retain >0.85 of their ambient yield strength, which is higher than all other intermetallics. Many of the Laves phases also have high melting temperatures, excellent creep properties, reasonably low densities, and for alloys containing Cr, Al, Si or Be, good oxidation resistance. Despite these useful properties, the tendency for low-temperature brittleness has limited the potential application of this large class of alloys.

  14. Clean Grain Boundary Found in C14/Body-Center-Cubic Multi-Phase Metal Hydride Alloys

    OpenAIRE

    Hao-Ting Shen; Kwo-Hsiung Young; Tiejun Meng; Bendersky, Leonid A

    2016-01-01

    The grain boundaries of three Laves phase-related body-center-cubic (bcc) solid-solution, metal hydride (MH) alloys with different phase abundances were closely examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and more importantly, electron backscatter diffraction (EBSD) techniques. By using EBSD, we were able to identify the alignment of the crystallographic orientations of the three major phases in the alloys (C14, bcc, and B2 structures). This finding...

  15. Experimental determination of the thermodynamic properties of the Laves phases in the Cr–Fe–Nb system

    Energy Technology Data Exchange (ETDEWEB)

    Syutkin, E.A., E-mail: syutkin.e.a@mail.ru [Thermochemistry of Materials Scientific Research Centre, NUST MISIS, Leninsky prosp. 4, 119049 Moscow (Russian Federation); Jacob, A. [Forschungszentrum Juelich, IEK-2, 52425 Juelich (Germany); Schmetterer, C., E-mail: clemens.schmetterer@umsicht.fraunhofer.de [Forschungszentrum Juelich, IEK-2, 52425 Juelich (Germany); Khvan, A.V. [Thermochemistry of Materials Scientific Research Centre, NUST MISIS, Leninsky prosp. 4, 119049 Moscow (Russian Federation); Hallstedt, B. [Institute for Materials Applications in Mechanical Engineering, RWTH Aachen University, Augustinerbach 4, 52062 Aachen (Germany); Dinsdale, A.T. [Thermochemistry of Materials Scientific Research Centre, NUST MISIS, Leninsky prosp. 4, 119049 Moscow (Russian Federation)

    2016-01-20

    Highlights: • The Cr–Fe–Nb system was investigated using drop solution calorimetry. • The standard enthalpies of formation of the 8 Laves phases were measured. • Values of the enthalpies of formation from this work differ from previous studies. - Abstract: Standard enthalpies of formation, Δ{sub f}H, of the Laves-phases within their solid solutions along the Cr{sub 2}Nb–Fe{sub 2}Nb section were measured using drop solution calorimetry for the first time. The enthalpy values change linearly from −2.9 kJ mol{sup −1} atom{sup −1} for binary C15-Cr{sub 2}Nb to −13.6 kJ mol{sup −1} atom{sup −1} for C14-Fe{sub 2}Nb. The obtained values are compared with some earlier results on the binary compounds gathered mostly from ab initio calculations.

  16. Aging phenomena before the precipitation of the bulky Laves phase in Fe-10%Cr ferritic alloys

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    Miyahara, Kazuya; Hwang, J.H. [Nagoya Univ. (Japan); Shimoide, Yukio [Daido Inst. of Technology, Nagoya (Japan). Dept. of Mechanical Engineering

    1995-06-15

    The detailed study through microstructural observation on the initial stage of precipitation behavior of the Laves phase in the 9--12%Cr ferritic steels is slightly difficult, because the matrix phase is martensite containing a high number density of dislocations and, secondly, the similar size and shape of carbides are formed with the Laves phase during aging treatments. In the present research, the precipitation behavior of the Laves phase, particularly, focusing on an initial stage of it, was investigated using sample Fe-10%Cr ferritic alloys.

  17. Quantification of Laves Phase Particle Size in 9CrW Steel

    DEFF Research Database (Denmark)

    Korcakova, Leona; Hald, John; Somers, Marcel A.J.

    2001-01-01

    Tungsten-alloyed martensic 9Cr steels are applied for streamlines of advanced power plants because of their superior creep performance. Tungsten, as the main new alloying element, induces precipitation of intermetallic Laves phase during long-term exposure at service temperatures around 600 C....... The growth and coarsening of Laves phase was investigated for the martensitic 9CrW steel P92 after aging and after creep testing at 600 or 650 C for times up to 59,000 h. For measurement of the size of Laves phase particles, field emission gun scanning electron microscopy (FEGSEM) was used along with image...

  18. Clean Grain Boundary Found in C14/Body-Center-Cubic Multi-Phase Metal Hydride Alloys

    Directory of Open Access Journals (Sweden)

    Hao-Ting Shen

    2016-06-01

    Full Text Available The grain boundaries of three Laves phase-related body-center-cubic (bcc solid-solution, metal hydride (MH alloys with different phase abundances were closely examined by scanning electron microscopy (SEM, transmission electron microscopy (TEM, and more importantly, electron backscatter diffraction (EBSD techniques. By using EBSD, we were able to identify the alignment of the crystallographic orientations of the three major phases in the alloys (C14, bcc, and B2 structures. This finding confirms the presence of crystallographically sharp interfaces between neighboring phases, which is a basic assumption for synergetic effects in a multi-phase MH system.

  19. Structure and phase transformation in the giant-magnetostriction Laves-phase SmFe2

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaonan; Lin, Kun; Gao, Qilong; Zhu, He; Li, Qiang; Cao, Yili; Chen, Jun; Ren, Yang; Huang, Rongjin; Lapidus, Saul H.; Xing, Xianran

    2018-01-15

    As one class of the most important intermetallic compounds, the binary Laves-phase is well-known for their abundant magnetic properties. Samarium-iron alloy system, SmFe2, is a prototypical Laves compound that shows strong negative magnetostriction but relatively weak magnetocrystalline anisotropy. SmFe2 has been identified as a cubic Fd3̅m structure at room temperature, however, the cubic symmetry does not match the spontaneous magnetization along the [111]cubic direction. Here we studied the crystal structure of SmFe2 by high-resolution synchrotron X-ray powder diffraction and X-ray total scattering methods. SmFe2 is found to adopt a centrosymmetric trigonal R3̅m structure at room temperature, which transforms to an orthorhombic Imma structure at 200 K. This transition is in agreement with the changes of easy magnetization direction from [111]cubic to [110]cubic direction, and is further evidenced by the inflexion of thermal expansion behavior, the sharp decline of the magnetic susceptibility in the FC-ZFC curve, and the anomaly in the specific heat capacity measurement. The revised structure and phase transformation of SmFe2 could be useful to understand the magnetostriction and related physical properties of other RM2-type pseudo-cubic Laves-phase intermetallic compounds.

  20. Hydrogen diffusion in the Laves-phase compound TiCr{sub 1.78}

    Energy Technology Data Exchange (ETDEWEB)

    Mazzolai, G. [University of Perugia, Department of Physics, Via A. Pascoli 5, 06100 Perugia (Italy); Universita Telematica e-Campus, Via Isimbardi 10, Novedrate (Colombia) (Italy); Coluzzi, B.; Biscarini, A. [University of Perugia, Department of Physics, Via A. Pascoli 5, 06100 Perugia (Italy); Mazzolai, F.M., E-mail: fabio.mazzolai@fisica.unipg.it [University of Perugia, Department of Physics, Via A. Pascoli 5, 06100 Perugia (Italy); Tuissi, A. [Institute for Energy and Interphases, CNR-IENI, C.so Promessi Sposi, 29, Lecco (Italy); Agresti, F.; Principi, G. [University of Padua, Dept. of Mech. Eng., via Marzolo 8, 35131 Padua (Italy); Lo Russo, S. [University of Padua, Physics Dept., via Marzolo 8, 35131 Padua (Italy)

    2009-09-15

    The temperature dependence of the Young's modulus and of the internal friction (IF) has been investigated between 80 and 300 K at acoustical frequencies in the hexagonal (C14) Laves-phase TiCr{sub 1.78} charged with hydrogen. In this compound H occupies tetrahedral interstitial sites which are grouped in interlinked hexagons. A mechanical relaxation has been found at around 120 K (f = 5.4 kHz), which appears to be due to tunnelling transitions of delocalized H from one hexagon to the other. The rate of H absorption has been investigated at high temperature (660-1200 K) and the H diffusion coefficient has been derived from the pressure measurement as a function of time. A cumulative Arrhenius plot of IF and absorption diffusion data exhibits a non-exponential behaviour, which is due to a change in the diffusion mechanism from over-barrier hopping at high temperature to phonon-assisted tunnelling at low temperature.

  1. Investigations on the growth kinetics of Laves phase precipitates in 12% Cr creep-resistant steels: Experimental and DICTRA calculations

    Energy Technology Data Exchange (ETDEWEB)

    Prat, O. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Strasse 1, 40237 Duesseldorf (Germany)] [Universidad de Concepcion, Departamento de Ingenieria de Materiales, Edmundo Larenas 270, Concepcion (Chile); Garcia, J., E-mail: jose.garcia@helmholtz-berlin.de [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Rojas, D. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Strasse 1, 40237 Duesseldorf (Germany); Carrasco, C. [Universidad de Concepcion, Departamento de Ingenieria de Materiales, Edmundo Larenas 270, Concepcion (Chile); Inden, G. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Strasse 1, 40237 Duesseldorf (Germany)

    2010-10-15

    The growth kinetics of Laves phase precipitates (type Fe{sub 2}W) in the early stage of creep (650 deg. C for 10,000 h) in two 12% Cr ferrite-martensitic steels has been investigated. In one alloy the Laves phase formed on tempering, while in the second alloy the Laves phase precipitated during creep. Kinetic simulations were performed using the software DICTRA. The particle size of the Laves phase was measured on transmission electron microscopy samples. The equilibrium phase fraction of the Laves phase was reached in the first thousand hours. Simulations of particle growth showed good agreement with the experimental results. Competitive growth between M{sub 23}C{sub 6} and the Laves phase showed that M{sub 23}C{sub 6} carbides reached their equilibrium after 12 days, whereas the Laves phase reached equilibrium after 3 months. Simulations of the influence of the interfacial energy and addition of Co, Cu and Si on Laves phase precipitation are presented.

  2. Electronic structure and magnetic properties of selected lanthanide and actinide intermetallic Laves-phase alloys

    DEFF Research Database (Denmark)

    Eriksson, Olle; Johansson, Börje; Brooks, M. S. S.

    1989-01-01

    The electronic structure and magnetic properties of some yttrium and uranium Laves-phase pseudobinary alloys with 3d elements have been calculated. The calculations were done by simulating the electronic structure of the alloy by that of an ordered compound with the same stoichiometry. In general...

  3. Measuring laves phase particle size and thermodynamic calculating its growth and coarsening behavior in P92 steels

    DEFF Research Database (Denmark)

    Yao, Bing-Yin; Zhou, Rong-Can; Fan, Chang-Xin

    2010-01-01

    The growth of Laves phase particles in three kinds of P92 steels were investigated. Laves phase particles can be easily separated and distinguished from the matrix and other particles by atom number contrast using comparisons of the backscatter electrons (BSE) images and the secondary electrons (...... attained between measurements in SEM and modeling by DICTRA. Ostwald ripening should be used for the coarsening calculation of Laves phase in P92 steels for time longer than 20000 h and 50000 h at 650°C and 600°C, respectively. © 2010 Chin. Soc. for Elec. Eng....

  4. Computational thermodynamic investigations of growth and coarsening of laves phase precipitates in 12%Cr creep resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Prat, O.; Rojas, D. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany); Garcia, J.; Kaysser-Pyzalla, A.R. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Bochum Univ. (Germany)

    2010-07-01

    Precipitation phenomena in 12%Cr high alloyed steels have been investigated at creep conditions of 650 and 150 MPa up to 6.500 hours in two different alloys. Growth and coarsening of Laves phase was determined experimentally by measuring the size of Laves phase on crept samples using scanning transmission electron microscopy (STEM). The simulations were performed using the software DICTRA based on the assumption the local equilibrium at the moving phase interface. For equilibrium calculations, the Thermo-Calc software was used. The experimental results were compared with DICTRA simulations, showing good agreement. Both the quantitative metallographic measurements as well as the simulations indicate very low coarsening for Laves Phase. The influence of different elements such as Co, Si and Cu on coarsening for Laves phase was simulated. (orig.)

  5. Structural, electronic and elastic properties of REIr2 (RE=La and Ce) Laves phase compounds

    Science.gov (United States)

    Shrivastava, Deepika; Fatima, Bushra; Sanyal, Sankar P.

    2016-05-01

    REIr2 (RE = La and Ce) Laves phase intermetallic compounds were investigated with respect to their structural, electronic and elastic properties using full potential linearized augmented plane wave (FP-LAPW) method within generalized gradient approximation (GGA) as implemented in WIEN2k code. The ground state properties such as lattice constants (a0), bulk modulus (B), pressure derivative of bulk modulus (Bꞌ) and density of state at Fermi level N(EF) have been obtained by optimization method. The electronic structure (BS, TDOS and PDOS) reveals that these Laves phase compounds are metallic in nature. The calculated elastic constants indicate that these compounds are mechanically stable at ambient pressure and found to be ductile in nature.

  6. First principles total energy study of NbCr{sub 2} + V Laves phase ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Ormeci, A. [Koc Univ., Istanbul (Turkey); Chen, S.P.; Wills, J.M.; Albers, R.C. [Los Alamos National Lab., NM (United States)

    1999-04-01

    The C15 NbCr{sub 2} + V Laves phase ternary system is studied by using a first-principles, self-consistent, full-potential total energy method. Equilibrium lattice parameters, cohesive energies, density of states and formation energies of substitutional defects are calculated. Results of all these calculations show that in the C15 NbCr{sub 2} + V compounds, V atoms substitute Cr atoms only.

  7. Effect of Laves phase on the creep rupture properties of P92 steel

    Energy Technology Data Exchange (ETDEWEB)

    Maddi, Lakshmiprasad, E-mail: prasadmlp@gmail.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology, Nagpur 440010 (India); GMR Institute of Technology, GMR Nagar, Rajam 532127 (India); Deshmukh, G.S.; Ballal, A.R.; Peshwe, D.R.; Paretkar, R.K. [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology, Nagpur 440010 (India); Laha, K.; Mathew, M.D. [Mechanical Metallurgy Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

    2016-06-21

    Stress rupture tests of normalized and tempered P92 (9Cr–0.5Mo–1.8 W) steel were performed in the range of 135–215 MPa at 650 °C. Effect of tempering temperature in the range of 740–780 °C on the creep rupture life was investigated. Resulting rupture times varied from 100 to 3000 h, and creep rate by one order of magnitude. In the high stress regime, lower tempering temperature resulted in the highest rupture time due to initial high dislocation density and fine laths. However, at lower stresses, highest rupture time was observed for highest tempering temperature. Formation of Laves phase (Fe{sub 2}Mo, Fe{sub 2}W) adjacent to M{sub 23}C{sub 6} carbides was responsible for increase in rupture time. Back scattered electron imaging (BSE) in scanning electron microscopy (SEM) was used to identify Laves phases, and study their distribution. Reduction in dislocation density and coarsening of laves phase precipitates result in decrease in stress exponent value ‘n’ at higher test temperatures of 650 °C.

  8. The mechanical properties and the deformation microstructures of the C15 Laves phase Cr2Nb at high temperatures

    NARCIS (Netherlands)

    Kazantzis, A. V.; Aindow, M.; Jones, I. P.; Triantafyllidis, G. K.; De Hosson, J. Th. M.

    Compression tests between 1250 and 1550 degrees C and 10(-5) and 5 x 10(-3) s(-1) and transmission electron microscopy have been employed to investigate the high temperature mechanical properties and the deformation mechanisms of the C15 Cr2Nb Laves phase. The stress-peaks in the compression curves

  9. Two-stage pressure-induced Yb valence change in the hexagonal Laves phase YbAg2: Investigation by time differential perturbed angular γ -γ correlation spectroscopy method and density functional calculations

    Science.gov (United States)

    Tsvyashchenko, A. V.; Nikolaev, A. V.; Salamatin, D. A.; Velichkov, A.; Salamatin, A. V.; Novikov, A. P.; Fomicheva, L. N.; El'kin, F. S.; Bibikov, A. V.; Kozin, M. G.; Budzynski, M.

    2017-12-01

    We have studied the C14 hexagonal Laves phase of YbAg2 at normal conditions and under external pressure up to 19 GPa by the time-differential perturbed angular γ -γ correlation spectroscopy (TDPAC) using 111Cd probe nuclei. Under pressure the valence of Yb undergoes a two-stage transition from 2.8 to 3. The two-stage scenario is characterized by two distinct quadrupole frequencies of 111Cd probes in a silver sublattice, monotonically increasing with pressure and saturating at 8 and 16 GPa. Our experimental data are compared with the density functional studies of the electron band structure of YbAg2, whose results are used for discussion and interpretation of these experiments. We have found that there are two different electric field gradients at inequivalent silver sites and that 4 d states of silver participate in metal bonding, allowing for the formation of the hexagonal Laves phase.

  10. Fabrication of Colloidal Laves Phases via Hard Tetramers and Hard Spheres: Bulk Phase Diagram and Sedimentation Behavior

    Science.gov (United States)

    2017-01-01

    Colloidal photonic crystals display peculiar optical properties that make them particularly suitable for application in different fields. However, the low packing fraction of the targeted structures usually poses a real challenge in the fabrication stage. Here, we propose a route to colloidal photonic crystals via a binary mixture of hard tetramers and hard spheres. By combining theory and computer simulations, we calculate the phase diagram as well as the stacking diagram of the mixture and show that a colloidal analogue of the MgCu2 Laves phase—which can serve as a precursor of a photonic band-gap structure—is a thermodynamically stable phase in a large region of the phase diagram. Our findings show a relatively large coexistence region between the fluid and the Laves phase, which is potentially accessible by experiments. Furthermore, we determine the sedimentation behavior of the suggested mixture, by identifying several stacking sequences in the sediment. Our work uncovers a self-assembly path toward a photonic structure with a band gap in the visible region. PMID:28787126

  11. Effect of prior deformation on microstructural development and Laves phase precipitation in high-chromium stainless steel.

    Science.gov (United States)

    Hsiao, Z-W; Chen, D; Kuo, J-C; Lin, D-Y

    2017-04-01

    This study investigated the influence of deformation on precipitation behaviour and microstructure change during annealing. Here, the prior deformation of high-chromium stainless steel was tensile deformation of 3%, 6% and 10%, and the specimens were then annealed at 700˚C for 10 h. The specimens were subsequently analyzed using backscattered electron image and electron backscattering diffraction measurements with SEM. Compared with the deformation microstructure, the grains revealed no preferred orientation. The precipitates of TiN and NbC were formed homogenously in the grain interior and at grain boundaries after annealing. Fine Laves phase precipitates were observed in grains and along subgrain boundaries as the deformation increased. Furthermore, the volume fraction of Laves phase increased, but the average particle diameter of precipitate was reduced as the deformation increased. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  12. Structural, electronic and elastic properties of REIr{sub 2} (RE=La and Ce) Laves phase compounds

    Energy Technology Data Exchange (ETDEWEB)

    Shrivastava, Deepika, E-mail: deepika89shrivastava@gmail.com; Fatima, Bushra; Sanyal, Sankar P. [Department of Physics, Barkatullah University, Bhopal, 462026 (India)

    2016-05-23

    REIr{sub 2} (RE = La and Ce) Laves phase intermetallic compounds were investigated with respect to their structural, electronic and elastic properties using full potential linearized augmented plane wave (FP-LAPW) method within generalized gradient approximation (GGA) as implemented in WIEN2k code. The ground state properties such as lattice constants (a{sub 0}), bulk modulus (B), pressure derivative of bulk modulus (B′) and density of state at Fermi level N(E{sub F}) have been obtained by optimization method. The electronic structure (BS, TDOS and PDOS) reveals that these Laves phase compounds are metallic in nature. The calculated elastic constants indicate that these compounds are mechanically stable at ambient pressure and found to be ductile in nature.

  13. Deuterium ordering in Laves phase deuteride YFe2D4.2

    Energy Technology Data Exchange (ETDEWEB)

    Proffen, Thomas Ernst [Los Alamos National Laboratory; Ropka, Joanna [UNIV OF GENEVA; Cerny, Radovan [UNIV OF GENEVA; Paul - Boncour, V [CNRS

    2009-01-01

    The structure of Laves phase deuteride YFe{sub 2}D{sub 4.2} has been investigated by synchrotron and neutron (ToF) powder diffraction experiments between 60 K and 370 K. YFe{sub 2}D{sub 4.2} crystallizes below 323K in fully ordered monoclinic structure (s.g. Pc, Z = 8, a = 5.50663(4), b = 11.4823(1), c = 9.42919(6) {angstrom}, {beta} = 122.3314(5){sup o}, V = 503.765(3) {angstrom}{sup 3} at 290K) containing 4 yttrium, 8 iron and 18 deuterium atoms. Most of D-D distances are within the precision of the diffraction experiment longer than 2.1 {angstrom}, the shortest ones are of 1.96 {angstrom}. Seven iron atoms from eight are coordinated by deuterium in a trigonal bipyramid, similar to that in TiFeD{sub 1.95-2}. The eights iron atom is coordinated by deuterium in a tetrahedral configuration. The iron coordination by deuterium, and iron-deuterium distances points to the importance of the directional bonding between iron and deuterium atoms. The lowering of crystal symmetry due to deuterium ordering occurs at much higher temperature than magnetic order, and is therefore one of the parameters which are at the origin of magnetic transition at lower temperatures.

  14. Phase behavior and nanoscale structure of phospholipid membranes incorporated with acylated C-14-peptides

    DEFF Research Database (Denmark)

    Pedersen, T.B.; Kaasgaard, Thomas; Jensen, M.O.

    2005-01-01

    The thermotropic phase behavior and lateral structure of dipalmitoylphosphatidylcholine (DPPC) lipid bilayers containing an acylated peptide has been characterized by differential scanning calorimetry (DSC) on vesicles and atomic force microscopy (AFM) on mica-supported bilayers. The acylated...... gel phase DPPC bilayers, inserts preferentially into preexisting defect regions and has a noticeable influence on the organization of the surrounding lipids. The presence of the C-14-peptide gives rise to a laterally heterogeneous bilayer structure with coexisting lipid domains characterized by a 10...

  15. Site occupancy of transition elements in C15 NbCr2 laves phase: A first-principles study

    Directory of Open Access Journals (Sweden)

    Long Q.

    2017-01-01

    Full Text Available Using first-principles calculations, site occupancy behaviors of transition elements in C15 NbCr2 Laves phase are systematically investigated. Elements Y, Sc, Zr, Hf, Cd, Ta, Ti and Ag prefer to occupy the Nb site, and elements Zn, Pt, Re, Tc, Ir, V, Os, Rh, Ru, Ni, Co, Mn, Fe and Cu favor to occupy the Cr site; whereas elements Mo, W, Pd and Au have weak site preference for Cr or Nb site. The present calculations agree well with the available experimental and previously calculated results. It was found that the site occupancy behavior of transition elements in NbCr2 is mainly affected by the radii of transition elements. The present calculations also propose the correlation between the site preference energy and radii of transition elements.

  16. Heterogeneous Creep Deformations and Correlation to Microstructures in Fe-30Cr-3Al Alloys Strengthened by an Fe2Nb Laves Phase

    Science.gov (United States)

    Shassere, Benjamin; Yamamoto, Yukinori; Poplawsky, Jonathan; Guo, Wei; Babu, Sudarsanam Suresh

    2017-10-01

    A new Fe-Cr-Al (FCA) alloy system has been developed with good oxidation resistance and creep strength at high temperature. The alloy system is a candidate for use in future fossil-fueled power plants. The creep strength of these alloys at 973 K (700 °C) was found to be comparable with traditional 9 pct Cr ferritic-martensitic steels. A few FCA alloys with general composition of Fe-30Cr-3Al-.2Si- xNb ( x = 0, 1, or 2) with a ferrite matrix and Fe2Nb-type Laves precipitates were prepared. The detailed microstructural characterization of samples, before and after creep rupture testing, indicated precipitation of the Laves phase within the matrix, Laves phase at the grain boundaries, and a 0.5 to 1.5 μm wide precipitate-free zone (PFZ) parallel to all the grain boundaries. In these alloys, the areal fraction of grain boundary Laves phase and the width of the PFZ controlled the cavitation nucleation and eventual grain boundary ductile failure. A phenomenological model was used to compare the creep strain rates controlled by the effects of the particles on the dislocations within the grain and at grain boundaries. (The research sponsored by US-DOE, Office of Fossil Energy, the Crosscutting Research Program).

  17. Ternary rhombohedral Laves phases RE{sub 2}Rh{sub 3}Ga (RE = Y, La-Nd, Sm, Gd-Er)

    Energy Technology Data Exchange (ETDEWEB)

    Seidel, Stefan; Benndorf, Christopher; Heletta, Lukas; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Janka, Oliver [Oldenburg Univ. (Germany). Inst. fuer Chemie; Mausolf, Bernhard [RWTH Aachen (Germany). Inst. fuer Anorganische Chemie; Haarmann, Frank [RWTH Aachen (Germany). Inst. fuer Anorganische Chemie; Max-Planck-Institut fuer Chemische Physik fester Stoffe, Dresden (Germany); Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Sao Paulo Univ., Sao Carlos (Brazil). Inst. of Physics

    2017-06-01

    The ordered Laves phases RE{sub 2}Rh{sub 3}Ga (RE=Y, La-Nd, Sm, Gd-Er) were synthesized by arc-melting of the elements and subsequent annealing. The samples were characterized by powder X-ray diffraction (XRD). They crystallize with the rhombohedral Mg{sub 2}Ni{sub 3}Si type structure, space group R3m. Three structures were refined from single crystal X-ray diffractometer data: a=557.1(1), c=1183.1(2), wR2=0.0591, 159 F{sup 2} values, 10 variables for Y{sub 2}Rh{sub 3}Ga, a=562.5(2), c=1194.4(2) pm, wR2=0.0519, 206 F{sup 2} values, 11 variables for Ce{sub 2}Rh{sub 3}Ga and a=556.7(2), c=1184.1(3) pm, wR2=0.0396, 176 F{sup 2} values, 11 variables for Tb{sub 2}Rh{sub 3}Ga. The Rh{sub 3}Ga tetrahedra are condensed via common corners and the large cavities left by the network are filled by the rare earth atoms. The RE{sub 2}Rh{sub 3}Ga Laves phases crystallize with a translationengleiche subgroup of the cubic RERh{sub 2} Laves phases with MgCu{sub 2} type. Magnetic susceptibility measurements reveal Pauli paramagnetism for Y{sub 2}Rh{sub 3}Ga and La{sub 2}Rh{sub 3}Ga. Ce{sub 2}Rh{sub 3}Ga shows intermediate cerium valence while all other RE{sub 2}Rh{sub 3}Ga phases are Curie-Weiss paramagnets which order magnetically at low temperatures. The {sup 89}Y and {sup 71}Ga solid state nuclear magnetic resonance (NMR) spectra of the diamagnetic representative Y{sub 2}Rh{sub 3}Ga show well-defined single resonances in agreement with an ordered bulk phase. In comparison to the binary Laves phase YRh{sub 2} a strongly increased {sup 89}Y resonance frequency is observed owing to a higher s-electron spin density at the {sup 89}Y nuclei as proven by density of states (DOS) calculations.

  18. Collapse of the magnetic moment under pressure of AFe{sub 2} (A=Y, Zr, Lu and Hf) in the cubic Laves phase

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenxu, E-mail: xwzhang@uestc.edu.cn; Zhang, Wanli

    2016-04-15

    The electronic structures of four Laves phase iron compounds (e.g. YFe{sub 2}, ZrFe{sub 2}, LuFe{sub 2} and HfFe{sub 2}) have been calculated with a state-of-the-art full potential electronic structure code. Our theoretical work predicted that the magnetic moments collapse under hydrostatic pressure. This feature is found to be universal in these materials. Its electronic origin is provided by the sharp peaks in the density of states near the Fermi level. It is shown that a first order quantum phase transition can be expected under pressure in Y(Zr, or Lu)Fe{sub 2}, while a second order one in HfFe{sub 2}. The bonding characteristics are discussed to elucidate the equilibrium lattice constant variation. The large spontaneous volume magnetostriction gives one of the most important characteristics of these compounds. Invar anomalies in these compounds can be partly explained by the current work when the fast continuous magnetic moment decrease with the decrease of the lattice constant was properly considered. This work may be as a first insight into the rich world of quantum phase transition and Invar mechanism in these Laves phase compounds. - Highlights: • Magnetic moment of YFe{sub 2}, ZrFe{sub 2}, LuFe{sub 2} and HfFe{sub 2} collapses under pressure. • The transition in Y(Zr or Lu) Fe{sub 2} under pressure is first order. • The transition in HfFe{sub 2} under pressure is second order. • The Invar effects in the compounds can be put into the magnetostriction model.

  19. Hydrogenation Properties of Laves Phases LnMg2 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb).

    Science.gov (United States)

    Werwein, Anton; Maaß, Florian; Dorsch, Leonhard Y; Janka, Oliver; Pöttgen, Rainer; Hansen, Thomas C; Kimpton, Justin; Kohlmann, Holger

    2017-12-18

    The hydrogenation properties of Laves phases LnMg2 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb) were investigated by thermal analysis, X-ray, synchrotron, and neutron powder diffraction. At 14.0 MPa hydrogen gas pressure and 393 K, PrMg2 and NdMg2 take up hydrogen and form the colorless, ternary hydrides PrMg2H7 (P41212, a = 632.386(6) pm, c = 945.722(11) pm) and NdMg2H7 (P41212, a = 630.354(9) pm, c = 943.018(16) pm). The crystal structures were refined by the Rietveld method from neutron powder diffraction data on the deuterides (PrMg2D7, P41212, a = 630.56(2) pm, c = 943.27(3) pm; NdMg2D7, P41212, a = 628.15(2) pm, c = 940.32(3) pm) and shown to be isotypic to LaMg2D7. The LaMg2D7 type of hydrides decompose at 695 K (La), 684 K (Ce), 684 K (Pr), 672 K (Nd), and 639 K (Sm) to lanthanide hydrides and magnesium. The Laves phase EuMg2 forms a hydride EuMg2Hx of black color. Its crystal structure (P212121, a = 664.887(4) pm, b = 1136.993(7) pm, c = 1069.887(7) pm) is closely related to the hexagonal Laves phase (MgZn2 type) of the hydrogen-free parent intermetallic. GdMg2 and TbMg2 form hydrides GdMg2Hx with orthorhombic unit cells (a = 1282.7(4) pm, b = 572.5(2) pm, c = 881.7(2) pm) and TbMg2Hx (a = 617.8(3) pm, b = 1045.8(8) pm, c = 997.1(5) pm), presumably also with a distorted MgZn2 type of structure. CeMg2H7 and NdMg2H7 are paramagnetic with effective magnetic moments of 2.49(1) μB and 3.62(1) μB, respectively, in good agreement with the calculated magnetic moments of the free trivalent rare-earth cations (μcalc(Ce3+) = 2.54 μB; μcalc(Nd3+) = 3.62 μB).

  20. First-principles study of structural phase transition, electronic, elastic and thermodynamic properties of C15-type Laves phase TiCr2 under pressure

    Science.gov (United States)

    He, Li-Zhi; Zhu, Jun; Zhang, Lin

    2018-02-01

    Phase transition of TiCr2 in C15 (MgCu2), C36 (MgNi2), C14 (MgZn2) structures have been studied by using the projector augmented wave method. It is found that C15-type is the most stable structure, which agrees with the results of Chen et al. At 0 K, the phase boundary of C15 to C36 is 207.79 GPa, and the phase transition from C36 to C14 is 265.61 GPa. Both the transition pressures decrease with increasing temperature. Phonon dispersion and elastic constants are calculated and found that C15-type TiCr2 is mechanically stable according to the elastic stability criteria and phonon dispersion analysis. Moreover, the pressure and temperature dependence of the specific heat, Debye temperature and thermal expansion coefficient are discussed, among them our calculated Debye temperature is consistent with the report of A. sari et al., however, it is far from the results of B. Mayer et al. and Chen et al.

  1. Effect of Laves Phase on High-Temperature Deformation and Microstructure Evolution in an 18Cr-2Mo-0.5Nb Ferritic Stainless Steel

    Science.gov (United States)

    Ikeda, Ken-ichi; Yamoah, Nana Kwame Gyan; Reynolds, William T.; Hamada, Jun-ichi; Murayama, Mitsuhiro

    2015-08-01

    Niobium-containing ferritic stainless steels are finding new applications in automotive exhaust components because of their oxidation resistance, thermal fatigue resistance, and high-temperature strength. The mechanical behavior of Nb-containing ferritic steels at service temperatures of 973 K (700 °C) and higher results from the convolution of dynamic microstructural changes including precipitation, precipitate coarsening, strain hardening, recovery, and recrystallization. The relative contributions of these competing processes have yet to be clarified. In this study, the high-temperature flow strength of an 18Cr-2Mo-0.5Nb ferritic stainless steel (SUS 444) was correlated with microstructure under different strain and initial precipitate distributions to clarify the relative role of the strengthening and softening processes. High-temperature tensile tests at 1023 K (750 °C) of un-aged (initial microstructure is precipitate-free) and pre-aged (initial microstructure contains precipitates) samples were carried out and transmission electron microscopy was used to assess dislocation distributions and precipitate morphology. The difference in the stress-strain curves between un-aged and pre-aged samples was drastic; the yield strength of the un-aged sample was twice that of the pre-aged sample, and the un-aged sample exhibits a noticeable yield drop. Transmission electron microscopy revealed a Laves phase nucleated and grew during the high-temperature tensile test in the un-aged sample and the majority of the precipitates in the pre-aged sample were the same Laves phase. Furthermore, a strain effect on precipitate growth was recognized in un-aged and pre-aged conditions by comparing grip (no strain) and gage (strained) sections of tensile samples. The dominant strengthening contribution in un-aged samples is initially the precipitate shearing mechanism and it changes to Orowan strengthening beyond the ultimate tensile strength, whereas the dominant contribution in

  2. Characterization of α-Fe-Free Heteroepitaxial NdFe12- x Ti x Thin-Film Materials with a Novel Cubic Laves Fe2Ti Phase

    Science.gov (United States)

    Hadorn, Jason Paul; Hirayama, Yusuke; Ohkubo, Tadakatsu

    2018-01-01

    Thin films with compositions of NdFe12 and NdFe11Ti1 were fabricated on W-buffered MgO(001) substrates of varying roughness. In this study, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the films microstructurally, chemically, and crystallographically. This study revealed successful heteroepitaxial synthesis of the tetragonal NdFe12 and NdFe12- x Ti x phases in the Ti-free and Ti-containing films, respectively, both with surface-normal c-axis orientation. It also revealed the presence of other phases within the magnetic layer. The NdFe12 films contained many α-Fe particles, which preferentially precipitated at locally rough regions of the W-buffer interface. The NdFe11Ti1 film showed the ubiquitous presence of an Fe2Ti phase, which covered most of the buffer thereby preventing the formation of α-Fe. This phase was determined to have a novel Cu2Mg-type cubic Laves ( C15) crystal structure with fourfold interfacial symmetry, good coherency, and a low mismatch with the W-buffer, thus rendering itself as being an ideal interface for the heteroepitaxial synthesis of NdFe12- x Ti x crystals. It is proposed that successful application of a cubic Fe2Ti underlayer on W can contribute to the development of a fabrication strategy for NdFe12 thin films without the presence of soft magnetic α-Fe.

  3. Effects of spin-orbit coupling on the electron-phonon superconductivity in the cubic Laves-phase compounds CaIr2 and CaRh2

    Science.gov (United States)

    Tütüncü, H. M.; Uzunok, H. Y.; Karaca, Ertuǧrul; Arslan, E.; Srivastava, G. P.

    2017-10-01

    We report our ab initio pseudopotential results for the structural, electronic, vibrational, and electron-phonon interaction properties of the cubic Laves-phase compounds CaIr2 and CaRh2. While the spin-orbit coupling (SOC) does not result in any appreciable changes in structural parameters, it lifts the degeneracies of some bands near the Fermi level, albeit with a much smaller amount for CaRh2. The effect of SOC on the vibrational properties of both materials is considerable. The SOC results in a slight decrease in the electronic density of states near the Fermi level N (EF) and makes low-frequency phonon branches harder, and the electron-phonon coupling parameter λ is lowered from 1.43 to 1.05 for CaIr2 and from 1.17 to 0.96 for CaRh2. On the other hand, the logarithmically averaged phonon frequency ωln is enhanced from 79.60 to 100.97 K for CaIr2 and from 120.20 to 140.80 K for CaRh2 with the inclusion of SOC. Using the calculated values of λ and ωln, the superconducting critical temperature is determined to be 5.94 K (7.34 K without SOC) for CaIr2 and 6.97 K (9.08 K without SOC) for CaRh2. The superconducting critical-temperature values with SOC compare very well with corresponding experimental values of 5.80 and 6.40 K, indicating the importance of SOC for the physical properties of both materials.

  4. Patterning effects on magnetic reversal properties in epitaxial-grown Laves phase DyFe{sub 2}/YFe{sub 2} superlattice

    Energy Technology Data Exchange (ETDEWEB)

    Wang, K., E-mail: K.Wang@hqu.edu.cn [College of Information Science and Engineering, Huaqiao University, Xiamen city 361021 (China); Chen, R.F.; Chen, C.W. [College of Information Science and Engineering, Huaqiao University, Xiamen city 361021 (China); Ward, R.C.C. [Clarendon Laboratory, Oxford University, OX1 3PU (United Kingdom)

    2015-03-01

    A large-scale striped array with 7.5 µm width has been fabricated in an epitaxial (110) single crystal [20 Å DyFe{sub 2}/80 Å YFe{sub 2}]{sub 40} superlattice using a UV direct writing system. The [−112] direction perpendicular to the [1−11] easy axis of the YFe{sub 2} layers, which dominate the magnetic behavior in the soft-layer-rich sample, was chosen to be patterned. The reversal behavior of the patterned superlattice was investigated by magneto-optical Kerr effect (MOKE) measurements. Both the switching fields and the exchange springs in the superlattices were found to be significantly affected by the patterning. Pronounced change in the coercivity was observed with the field applied along the patterned [−112] direction due to a considerable induced anisotropy, which is estimated to be 2.1×10{sup 4} erg/cm{sup 3}. When the field is applied along the [1−11] direction a reduction of 9% in the irreversible switching field was presented. This agrees well with the ratio of 8% of the shape anisotropy to the value of the hard layers along the [1−11] direction. Nevertheless, the small bending field remains unaffected after patterning due to a strong Fe–Fe exchange field. - Highlights: • We investigate the magnetic reversal properties of patterned epitaxial-grown Laves phase single crystal DyFe{sub 2}/YFe{sub 2} superlattice. • We find both the switching fields and the exchange springs in the superlattices can be significantly affected by the patterning. • The bending field in the superlattice remains unaffected after patterning due to a strong Fe–Fe exchange field.

  5. Thermoelectric properties of TbFe{sub 2} and TbCo{sub 2} in C15- laves phase: Spin-polarized DFT+U approach

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, A.H., E-mail: maalidph@yahoo.co.uk [New Technologies - Research Centre, University of West Bohemia, Univerzitni 8, Pilsen 306 14 (Czech Republic); School of Material Engineering, University Malaysia Perlis, Kangar, Perlis 01007 (Malaysia)

    2017-01-15

    Thermoelectric properties of materials are intimately related to their electronic band structure. Combining first- and second-principles calculations, we have obtained the transport properties for the spin-up and spin-down electrons of the laves phase TbFe{sub 2} and TbCo{sub 2} compounds. The unique band structure feature and the density of states at Fermi level (E{sub F}) promote the E{sub F} to a point where carriers are in energetic proximity to these features. The non-zero density of states at E{sub F} for the spin-up (↑) and spin-down (↓) electrons leads to unusual transport properties because both the (↑) and (↓) densities contributes to the states at E{sub F}. The parabolic bands in the vicinity of E{sub F} enhance the carriers mobility and hence the transport properties of TbFe{sub 2} and TbCo{sub 2}. Calculations show that the spin-up/down transport coefficients are temperature-dependent. It has been found that TbCo{sub 2} possess larger Seebeck coefficient than that of TbFe{sub 2} and hence the power factor. The calculated Seebeck coefficient of TbCo{sub 2} agree well with the available experimental data. - Highlights: • The transport properties of TbFe{sub 2} and TbCo{sub 2} are obtained. • The non-zero density of states at E{sub F} leads to unusual transport properties. • Spin-up/down transport coefficients are temperature-dependent. • The calculated Seebeck coefficient of TbCo{sub 2} agree with the experimental data. • TbCo{sub 2} possesses larger Seebeck coefficient than that of TbFe{sub 2}.

  6. Twinned CsLn{sub 2}F{sub 7} compounds (Ln=Nd, Gd, Tb, Er, Yb). The role of a highly symmetrical cation lattice with an arrangement analogous to the Laves phase MgZn{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Friese, Karen [Forschungszentrum Juelich GmbH, Juelich (Germany). Juelich Centre for Neutron Science-2; Khaidukov, Nicholas [Kurnakov Institute of General and Inorganic Chemistry, Moscow (Russian Federation); Grzechnik, Andrzej [RWTH Aachen Univ. (Germany). Inst. for Crystallography

    2016-07-01

    The occurrence of twinning can often be related to higher symmetrical structures. Fluorides are frequently twinned due to their close relation to high symmetry structures like fluoride, tysonite or pyrochlores. The series of compounds CsLn{sub 2}F{sub 7} is no exception. We refined the structures of the twinned compounds with Ln=Nd, Gd, Tb, Er, Yb in space group P112{sub 1}/b. An analysis of the pseudosymmetry of the resulting structures shows a highly symmetrical cation partial structure with a cation distribution similar to the one in the hexagonal Laves phase MgZn{sub 2}. Several other compounds ALn{sub 2}F{sub 7}, which have been described in the literature, show a similar cation array. The diversity of different space groups which have been reported for ALn{sub 2}F{sub 7} compounds can be better understood using group-subgroup relationships assuming the hypothetical structure of the cation array with space group P6{sub 3}/mmc as aristotype. Furthermore, the twinning is easily understood on the basis of the lost symmetry operations in the symmetry reduction from point group 6/mmm, e.g. to 2/m in the case of the CsLn{sub 2}F{sub 7} compounds.

  7. Photo-Induced Phase Transitions to Liquid Crystal Phases: Influence of the Chain Length from C8E4 to C14E4

    Directory of Open Access Journals (Sweden)

    Simone Techert

    2009-09-01

    Full Text Available Photo-induced phase transitions are characterized by the transformation from phase A to phase B through the absorption of photons. We have investigated the mechanism of the photo-induced phase transitions of four different ternary systems CiE4/alkane (i with n = 8, 10, 12, 14; cyclohexane/H2O. We were interested in understanding the effect of chain length increase on the dynamics of transformation from the microemulsion phase to the liquid crystal phase. Applying light pump (pulse/x-ray probe (pulse techniques, we could demonstrate that entropy and diffusion control are the driving forces for the kind of phase transition investigated.

  8. Comparison of C14- and C15-Predomiated AB2 Metal Hydride Alloys for Electrochemical Applications

    Directory of Open Access Journals (Sweden)

    Kwo-Hsiung Young

    2017-07-01

    Full Text Available Herein, we present a comparison of the electrochemical hydrogen-storage characteristics of two state-of-art Laves phase-based metal hydride alloys (Zr21.5Ti12.0V10.0Cr7.5Mn8.1Co8.0Ni32.2Sn0.3Al0.4 vs. Zr25.0Ti6.5V3.9Mn22.2Fe3.8Ni38.0La0.3 prepared by induction melting and hydrogen decrepitation. The relatively high contents of lighter transition metals (V and Cr in the first composition results in an average electron density below the C14/C15 threshold ( e / a ~ 6.9 and produces a C14-predominated structure, while the average electron density of the second composition is above the C14/C15 threshold and results in a C15-predominated structure. From a combination of variations in composition, main phase structure, and degree of homogeneity, the C14-predominated alloy exhibits higher storage capacities (in both the gaseous phase and electrochemical environment, a slower activation, inferior high-rate discharge, and low-temperature performances, and a better cycle stability compared to the C15-predominated alloy. The superiority in high-rate dischargeability in the C15-predominated alloy is mainly due to its larger reactive surface area. Annealing of the C15-predominated alloy eliminates the ZrNi secondary phase completely and changes the composition of the La-containing secondary phase. While the former change sacrifices the synergetic effects, and degrades the hydrogen storage performance, the latter may contribute to the unchanged surface catalytic ability, even with a reduction in total volume of metallic nickel clusters embedded in the activated surface oxide layer. In general, the C14-predominated alloy is more suitable for high-capacity and long cycle life applications, and the C15-predominated alloy can be used in areas requiring easy activation, and better high-rate and low-temperature performances.

  9. New high pressure polymorph of the CaSi2 compound with Laves structure

    Science.gov (United States)

    Bouderba, Hichem; Beddiaf, Raouf

    2014-05-01

    In the present work, based on first-principles calculations, we show that it is possible to obtain a new high pressure polymorph of the CaSi2 compound with a Laves structure. It corresponds to the MgCu2-type (C15) which is one of the three most important Laves phases. We also show that the two other structures, MgNi2- and MgZn2-types are very competitive energetically and are possible candidates for finite temperature investigations.

  10. High-pressure high-temperature decomposition of CeCoGa to the Laves phases CeCo{sub 0.58}Ga{sub 1.42}, CeCo{sub 0.72}Ga{sub 1.28}, and CeCo{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Niehaus, Oliver; Rodewald, Ute C.; Heying, Birgit; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Heymann, Gunter; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie

    2016-07-01

    The monoclinic intermediate-valent gallide CeCoGa decomposes under high-pressure (HP) (9.5 GPa) high-temperature (HT) (1470 K) conditions into the Laves phases CeCo{sub 0.58}Ga{sub 1.42} (MgCu{sub 2} type), CeCo{sub 0.72}Ga{sub 1.28} (MgZn{sub 2} type; major product phase), and CeCo{sub 2} (MgCu{sub 2} type). The structures of the ternary Laves phases were refined from single crystal X-ray diffractometer data: Fd anti 3m, a=778.3(1) pm, wR2=0.0310, 63 F{sup 2} values, five variables for CeCo{sub 0.58(3)}Ga{sub 1.42(3)} and P6{sub 3}/mmc, a=547.24(5), c=858.76(7) pm, wR2=0.1009, 195 F{sup 2} values, 13 variables for CeCo{sub 0.72(1)}Ga{sub 1.28(1)}. Partial substitution of cobalt by gallium leads to a significant increase of the distances within the tetrahedral network: 253 pm Co-Co in CeCo{sub 2} as compared to 275 pm in CeCo{sub 0.58(3)}Ga{sub 1.42(3)} and 265-277 pm in CeCo{sub 0.72(1)}Ga{sub 1.28(1)}. The crystal chemical consequences are briefly discussed.

  11. Structural and magnetic studies on the new Laves phases RE(Co0.667Ga0.333)2 (RE = Gd, Tb, Dy, Ho, and Er). Magnetocaloric effect of Gd(Co0.667Ga0.333)2

    Science.gov (United States)

    Yuan, Fang; Greedan, John E.; Mozharivskyj, Yurij

    2017-11-01

    Several new MgZn2-type Laves phases with the P63/mmc symmetry and RE(Co0.667Ga0.333)2 stoichiometries (RE = Gd, Tb, Dy, Ho, and Er) were obtained by arc-melting and subsequent annealing. Single crystals with the MgZn2-type structure were extracted from the annealed RE(Co0.667Ga0.333)2 (RE = Gd, Tb, Dy, and Ho) alloys and Ga flux-grown Er(Co0.667Ga0.333)2 sample. Powder and single-crystal X-ray diffraction methods were used for the phase analysis and structural characterization. A decrease in the cell volume due to the lanthanide contraction is observed from Gd(Co0.667Ga0.333)2 to Er(Co0.667Ga0.333)2. RE atoms occupy the 4f site, while Co and Ga are in the 2a and 6h sites. Magnetic behavior of the hexagonal MgZn2-type RE(Co0.667Ga0.333)2 phases strongly depends on the RE. Apparent ferromagnetic transition is observed for RE = Gd, Tb, and Dy, while the other two phases (RE = Ho, and Er) seem to be ferrimagnetic. Magnetocaloric properties of the Gd(Co0.667Ga0.333)2 phase were measured; the small isothermal magnetic entropy change (ΔSiso) value of -4.94 J/kgK at 152 K and for a ΔH = 0-50 kOe field change suggests a conventional magnetocaloric effect.

  12. Study of fatigue and fracture behavior of NbCr{sub 2}-based alloys: Phase stability in Nb-Cr-Ni ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J.H.; Liaw, P.K. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Liu, C.T. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-12-01

    Phase stability in a ternary Nb-Cr-Ni Laves phase system was studied in this paper. Their previous study in NbCr{sub 2}-based transition-metal Laves phases has shown that the average electron concentration factor, e/a, is the dominating factor in controlling the phase stability of NbCr{sub 2}-based Laves phases when the atomic size ratios are kept identical. Since Ni has ten out-shell electrons, the substitution of Ni for Cr in NbCr{sub 2} will increase the average electron concentration of the alloy, thus leading to the change of the crystal structures from C15 to C14. In this paper, a number of pseudo-binary Nb(Cr,Ni){sub 2} alloys were prepared, and the crystal structures of the alloys after a long heat-treatment at 1000 C as a function of the Ni content were determined by the X-ray diffraction technique. The boundaries of the C15/C14 transition were determined and compared to their previous predictions. It was found that the electron concentration and phase stability correlation is obeyed in the Nb-Cr-Ni system. However, the e/a ratio corresponding to the C15/C14 phase transition was found to move to a higher value than the predicted one. The changes in the lattice constant, Vickers hardness and fracture toughness were also determined as a function of the Ni content, which were discussed in light of the phase stability difference of the alloys.

  13. Hwa-ba: forskerne vil ikke lave eksperimenter!?

    DEFF Research Database (Denmark)

    Hokland, Peter

    2016-01-01

    For over 40 år siden i 1975 blev en række videnskabelige selskaber enige om at indføre et midlertidigt stop for et bestemt type eksperimenter inden for den såkaldte rekombinante DNA teknologi. Den indebærer, at man kan lave om på vores gener på en måde, som vel kunne være til gavn for den enkelte...

  14. Effects of Nd-addition on the structural, hydrogen storage, and electrochemical properties of C14 metal hydride alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wong, D.F. [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Department of Chemical Engineering, Wayne State University, Detroit, MI 48202 (United States); Young, K., E-mail: kwo.young@basf.com [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Department of Chemical Engineering, Wayne State University, Detroit, MI 48202 (United States); Nei, J.; Wang, L. [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Ng, K.Y.S. [Department of Chemical Engineering, Wayne State University, Detroit, MI 48202 (United States)

    2015-10-25

    Nd-addition to the AB{sub 2}-based alloy Ti{sub 12}Zr{sub 22.8−x}V{sub 10}Cr{sub 7.5}Mn{sub 8.1}Co{sub 7.0}Ni{sub 32.2}Al{sub 0.4}Nd{sub x} is studied for its effects on the structure, gaseous-phase hydrogen storage, and electrochemical properties. This study follows a series of Cu, Mo, Fe, Y, Si, and La doping studies in similar AB{sub 2}-based alloys. Limited solubility of Nd in the main Laves phase promotes the formation of secondary phases (AB and Zr{sub 7}Ni{sub 10}) to provide catalytic effects and synergies for improved capacity and high-rate dischargeability (HRD) performance. The main C14 storage phase has smaller lattice constants and cell volumes, and these effects reduce the storage capacity at higher Nd levels. Different hydrogen absorption mechanisms can occur in these multi-component, multi-phase alloys depending on the interfaces of the phases, and they have effects on the alloy properties. Higher Nd-levels improve the HRD performance despite having lower bulk diffusion and surface exchange current. Magnetic susceptibility measurements indicate large percentage of larger metallic nickel clusters are present in the surface oxide of alloys with higher Nd-content, and AC impedance studies show very low charge-transfer resistance with high catalytic capability in the alloys. The −40 °C charge-transfer resistance of 8.9 Ω g in this Nd-series of alloys is the lowest measured out of the studies investigating doped AB{sub 2}-based MH alloys for improved low-temperature characteristics. The improvement in HRD and low-temperature performance appears to be related to the proportion of the highly catalytic NdNi-phase at the surface, which must offset the increased bulk diffusion resistance in the alloy. - Graphical abstract: Schematics of hydrogen flow and corresponding PCT isotherms in funneling mode. - Highlights: • Structural and hydrogen storage properties of Nd-substituted AB{sub 2} metal hydride are reported. • Nd contributes to the lowest

  15. Clipboard: Lymphohematopoietic licence: Sterol C-14 reductase ...

    Indian Academy of Sciences (India)

    Clipboard: Lymphohematopoietic licence: Sterol C-14 reductase activity of lamin B receptor (Lbr) is essential for neutrophil differentiation. Durgadas P Kasbekar. Volume 37 ... Keywords. Greenberg/HEM dysplasia; lymphohematopoietic progenitor cells; nuclear envelope; Pelger-Huët anomaly; promyelocyte differentiation ...

  16. Phase Stability in the Fe-Rich Fe-Cr-Ni-Zr Alloys

    Science.gov (United States)

    Chen, Tianyi; Yang, Ying; Tan, Lizhen

    2017-10-01

    Knowledge on phase stability in Fe-rich Fe-Cr-Ni-Zr alloys is needed for the development of Laves phase strengthened Fe-Cr-Ni-Zr ferritic alloys. These alloys show promising applications as new cladding materials of nuclear reactors due to enhanced high-temperature strength and resistance to creep and irradiation hardening. Phase stability in four Fe-rich Fe-Cr-Ni-Zr alloys was carefully investigated using scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction techniques. The samples were arc-melted and heat treated at 973.15 K (700 °C) for 1275 hours and 1273.15 K (1000 °C) for 336 hours. The experimental results showed extensive solubility of Ni in the intermetallic phases Fe23Zr6 and Fe2Zr_C15. Nickel stabilizes the Laves Fe2Zr_C15 structure more than the C36 and C14 structures. In addition to Fe23Zr6 and Fe2Zr_C15, Ni7Zr2 was found to be stable in samples with higher Ni content and lower annealing temperature. The Fe2Zr_C15 and Fe23Zr6 coexist with the body-centered cubic matrix phase in all samples regardless of compositions and temperatures.

  17. Last fra kornede materialer på begrænsningsvægge i lave lagerbygninger

    DEFF Research Database (Denmark)

    Møller, S.

    Rapporten indeholder forudsætninger og retningslinier for den statiske beregning af lave lagerbygninger, fx. plansiloer i landbruget. I to hovedkapitler gives data og formler til lastbestemmelse som grundlag for brudundersøgelse og deformationsundersøgelse, samt et eksempel på lastberegning....

  18. Capture reactions on C-14 in nonstandard big bang nucleosynthesis

    Science.gov (United States)

    Wiescher, Michael; Gorres, Joachim; Thielemann, Friedrich-Karl

    1990-01-01

    Nonstandard big bang nucleosynthesis leads to the production of C-14. The further reaction path depends on the depletion of C-14 by either photon, alpha, or neutron capture reactions. The nucleus C-14 is of particular importance in these scenarios because it forms a bottleneck for the production of heavier nuclei A greater than 14. The reaction rates of all three capture reactions at big bang conditions are discussed, and it is shown that the resulting reaction path, leading to the production of heavier elements, is dominated by the (p, gamma) and (n, gamma) rates, contrary to earlier suggestions.

  19. Cosmogenic Radionuclides in Hot Desert Chondrites with Low C-14 Activities: A Progress Report

    Science.gov (United States)

    Welten, Kees; Nishiizumi, Kunihiko; Caffee, Marc W.

    1999-01-01

    Terrestrial ages of meteorites from hot deserts provide an important tool to estimate meteorite fluxes to the Earth. Most desert meteorites have terrestrial ages less than 40 ky, but a few achondrites from the Sahara region were recently shown to have significantly higher ages, up to approx. 100 ky. In general, C-14 (half-life = 5730 y) is the most suited radionuclide to determine terrestrial ages for desert meteorites. However for meteorites with ages greater than 35 ky, the concentration of cosmogenic C-14 has decreased to a level at which it becomes difficult to distinguish between cosmogenic C-14 and terrestrial contamination. These meteorites may therefore be much older than 35 ky. We selected chondrites with low C-14 activities (less than or equal to 2 dpm/kg) for measurements of the concentrations of cosmogenic Cl-36 (half-life= 3.01 x 10 (exp 5) y) and Ca-41 (half-life= 1.04 x 10 (exp 5) y) in the metal phase. Since the ratio of Ca-14/Cl-36 in the metal phase of chondrites is relatively constant and well known, the measured ratio is a direct measure of the terrestrial age. A major problem is that most or sometimes all of the metal in these old "hot desert" meteorites has been oxidized to hydrated Fe-Ni-oxides. Therefore, we also measured the concentrations of Be-10, Al-26 and Cl-36 in the stony phase in order to constrain the terrestrial age as much as possible.

  20. Cosmogenic Radionuclides in Hot Desert Chondrites With Low C-14 Activities

    Science.gov (United States)

    Welten, K. C.; Nishiizumi, K.; Caffee, M. W.

    2000-01-01

    Terrestrial ages of meteorites from hot deserts provide an important tool to estimate meteorite fluxes to the Earth. Most desert meteorites have terrestrial ages less than 40 ky, but a few achondrites from the Sahara region were recently shown to have significantly higher ages, up to approx.100 ky. In general, C-14 (half-life = 5730 y) is the most suited radionuclide to determine terrestrial ages for desert meteorites. However for meteorites with ages >35 ky, the concentration of cosmogenic C-14 has decreased to a level at which it becomes difficult to distinguish between cosmogenic C-14 and terrestrial contamination. These meteorites may therefore be much older than 35 ky. We selected chondrites with low C-14 activities (less than or equal to 2 dpm/kg) for measurements of the concentrations of cosmogenic Cl-36 (half-life= 3.01 x 105 y) and Ca-41 (half-life= 1.04 x 105 y) in the metal phase. Since the ratio of Ca-41/Cl-36 in the metal phase of chondrites is relatively constant and well known, the measured ratio is a direct measure of the terrestrial age]. A major problem is that most or sometimes all. of the metal in these old "hot desert" meteorites has been oxidized to hydrated Fe-Ni-oxides. Therefore, we also measured the concentrations of Be-10, Al-26 and Cl-36 in the stony phase in order to constrain the terrestrial age as much as possible.

  1. Thr translocation of C-14-assimilates in Eragrostis curvula: an ...

    African Journals Online (AJOL)

    In intact plants C-14-assimilates were translocated from the treated leaf on the primary tiller to young leaves on that tiller, to secondary tillers, and also to the roots. Plants defoliated after labeling revealed movement of materials from the storage organs to all the new leaves. Here these materials were used as a respiratory ...

  2. C-14/I-29 Preservation and Hold Time Survey

    Energy Technology Data Exchange (ETDEWEB)

    Kitchen, S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-04-08

    Preservation and hold time of radionuclides must account for both nuclear half-lives and nonnuclear loss mechanisms, but variations in the latter are often neglected. Metals-based defaults are inappropriate for long-lived non-metals C-14 and I-129, which are vulnerable to chemical and biological volatilization. Non-acidification is already widely practiced for them. Recommended addition measures from radiological and chemical literature include glass containers where possible, water filtration where possible, headspace minimization, light shielding, cold (4°C) storage and unfiltered water hold time of 28 days. Soil hold time may need to be shortened when water-logged, excessively sandy, or still adjusting to significant new contamination.

  3. Electronic structure, cohesive, and magnetic properties of the actinide-iridium Laves phases

    DEFF Research Database (Denmark)

    Eriksson, O.; Johansson, B.; Brooks, M. S. S.

    1989-01-01

    The electronic structure of the isostructural AIr2 systems (A=Th, Pa, U, Np, Pu, and Am) has been obtained by means of the scalar relativistic and fully relativistic linear muffin-tin orbital techniques. Ground-state properties such as lattice constants and onset of magnetic order have been...

  4. Microstructure Evolution of Laves Phase Strengthened Ferritic Steels for High Temperature Applications

    OpenAIRE

    Lopez Barrilao, Jennifer

    2017-01-01

    The present investigation focuses on a new concept of high strength, high chromium (18-23 wt.%), fully ferritic steels on the technical basis of Crofer® 22 H for the application in high temperature energy conversion systems. Fully ferritic means, that these steels possess a ferritic matrix at any temperature below the melting point, i.e. no martensitic transformation occurs. During Crofer® 22 APU and Crofer® 22 H development, over 50 trial alloys with slight changes in chemical composition we...

  5. Amorphization of Laves-Phase Precipitates in Zircaloy-4 by Neutron Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Peters, H.R.; Taylor, D.F.; Yang, Walter J.S.

    1999-04-23

    Examination of corrosion coupons by transmission electron microscopy after their exposure in the Idaho Advanced Test Reactor (ATR) has broadened the Zircaloy-4 precipitate-amorphization database and validated a new kinetic model for previously unavailable values of temperature and fast-neutron flux. The model describes the amorphization of Zr(Fe,Cr){sub 2} intermetallic precipitates in zirconium alloys as a dynamic competition between radiation damage and thermal annealing that leaves some iron atoms available for flux-assisted diffusion to the zirconium matrix. It predicts the width of the amorphous zone as a function of neutron flux (E>1 MeV), temperature, and time. In its simplest form, the model treats the crystalline/amorphous and precipitate/matrix interfaces as parallel planes, and its accuracy decreases for small precipitates and high fluence as the amorphous-zone width approaches precipitate dimensions. The simplest form of the model also considers diffusion to be rate-determining. This is an accurate approximation for steady-state conditions or slow changes in flux and temperature, but inappropriate for the analysis of faster transients. The paper addresses several difficulties inherent in measuring amorphous-zone width, and utilizes the expanded database to evaluate the improvements in predictive accuracy available through both conversion of the model to spherical coordinates and extension of its time dependency.

  6. (CH4)-C-14 Measurements in Greenland Ice: Investigating Last Glacial Termination CH4 Sources

    DEFF Research Database (Denmark)

    Petrenko, V. V.; Smith, A. M.; Brook, E. J.

    2009-01-01

    The cause of a large increase of atmospheric methane concentration during the Younger Dryas-Preboreal abrupt climatic transition (similar to 11,600 years ago) has been the subject of much debate. The carbon-14 (C-14) content of methane ((CH4)-C-14) should distinguish between wetland and clathrate...... by direct cosmogenic C-14 production in ice. C-14 of CO was measured to better understand this process and correct the sample (CH4)-C-14. Corrected results suggest that wetland sources were likely responsible for the majority of the Younger Dryas-Preboreal CH4 rise....

  7. Studies of Nucleation and Growth, Specific Heat and Viscosity of Undercooled Melts of Quasicrystal and Polytetrahedral-Phase Forming Alloys

    Science.gov (United States)

    Kelton, K. F.; Gangopadhyay, Anup K.; Lee, G. W.; Hyers, Robert W.; Rathz, T. J.; Robinson, Michael B.; Rogers, Jan R.

    2003-01-01

    From extensive ground based work on the phase diagram and undercooling studies of Ti-Zr-Ni alloys, have clearly identified the composition of three different phases with progressively increasing polytetrahedral order such as, (Ti/Zr), the C14 Laves phase, and the i-phase, that nucleate directly from the undercooled liquid. The reduced undercooling decreases progressively with increasing polytetrahedral order in the solid, supporting Frank s hypothesis. A new facility for direct measurements of the structures and phase transitions in undercooled liquids (BESL) was developed and has provided direct proof of the primary nucleation of a metastable icosahedral phase in some Ti-Zr-Ni alloys. The first measurements of specific heat and viscosity in the undercooled liquid of this alloy system have been completed. Other than the importance of thermo-physical properties for modeling nucleation and growth processes in these materials, these studies have also revealed some interesting new results (such as a maximum of C(sup q, sub p) in the undercooled state). These ground-based results have clearly established the necessary background and the need for conducting benchmark nucleation experiments at the ISS on this alloy system.

  8. Electro-removal of H-3 and C-14 contained in scintillation liquid absorbed in soils type Phaeozem; Electrorremocion de H-3 y C-14 contenidos en liquido de centelleo absorbidos en suelos tipo Phaeozem

    Energy Technology Data Exchange (ETDEWEB)

    Valdovinos, V.; Bustos, E. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Parque Tecnologico Queretaro s/n, San Fandila, 76703 Pedro Escobedo, Queretaro (Mexico); Monroy G, F., E-mail: vvaldovinos@cideteq.mx [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2014-10-15

    This paper presents the results of electro-removal, an electrochemical treatment in soils contaminated with H-3 and C-14 contained in scintillation liquids absorbed in soils. For this purpose the best electrochemical conditions were used, which are: scintillation liquid Ultima Gold Xr, water (1:1) and 1 m A in the passage of current. The media were characterized before and after of applying the different potentials by various analytical techniques, such as: liquids by gas chromatography with a flame ionization detector, solids and liquids by Fourier transform infrared spectroscopy (Ftir) and electrodes by scanning electron microscopy with elemental analysis by energy-dispersive X-ray spectroscopy. Later standard samples with H-3 and C-14 were prepared and the electrochemical treatment was applied to previously established conditions. After electrochemical treatment the scintillation liquid characterization was performed by gas chromatography and a scintillation counter to see the disintegrations per minute. According to results of Ftir, soils show no deterioration and in the liquid phase the amount of water increases as the applied potential, due to oxidation-reduction reactions where happen modification or mineralization of organic molecules (H{sub 2}O and CO{sub 2} formation). In 4 h of treatment, removal percentages in the liquid phase, were: 53.6% of H-3 and 11.6% of C-14. (Author)

  9. METABOLISM OF d-RIBOSE-1-C14 AND C14-LABELED d-GLUCONATE IN AN ENZYME SYSTEM OF THE GENUS PROPIONIBACTERIUM

    Science.gov (United States)

    Stjernholm, Rune L.; Flanders, Frank

    1962-01-01

    Stjernholm, Rune L. (Western Reserve University, Cleveland, Ohio) and Frank Flanders. Metabolism of d-ribose-1-C14 and C14-labeled d-gluconate in an enzyme system of the genus Propionibacterium. J. Bacteriol. 84:563–568. 1962.—Ribose-1-C14 and potassium gluconate labeled in different positions were incubated with cell-free extracts of Propionibacterium shermanii. The resulting propionate, acetate, and succinate were isolated and the C14 distribution determined by degradation. It is proposed that the extensive randomization observed is caused by the conversion of the labeled substrates to fructose-6-phosphate via the transketolase-transaldolase sequence followed by the Embden-Meyerhof pathway, and that the triosephosphates produced by these metabolic routes are metabolized via pyruvate to succinate and propionate. PMID:13984204

  10. Fabrication of Colloidal Laves Phases via Hard Tetramers and Hard Spheres : Bulk Phase Diagram and Sedimentation Behavior

    NARCIS (Netherlands)

    Avvisati, Guido; Dasgupta, Tonnishtha|info:eu-repo/dai/nl/411964844; Dijkstra, Marjolein|info:eu-repo/dai/nl/123538807

    2017-01-01

    Colloidal photonic crystals display peculiar optical properties that make them particularly suitable for application in different fields. However, the low packing fraction of the targeted structures usually poses a real challenge in the fabrication stage. Here, we propose a route to colloidal

  11. Conversion of MX nitrides to Z-phase in a martensitic 12% Cr steel

    DEFF Research Database (Denmark)

    Cipolla, L.; Danielsen, Hilmar Kjartansson; Venditti, D.

    2010-01-01

    of Laves phase were avoided by keeping the C, W and Mo contents as low as possible. Transmission electron microscopy and X-ray diffraction analysis of extracted particles were used to follow the evolutions of phase composition, phase morphology and phase fraction, particularly of the precipitation of Z...

  12. Future needs and requirements for AMS C-14 standards and reference materials

    NARCIS (Netherlands)

    Scott, EM; Boaretto, E; Bryant, C; Cook, GT; Gulliksen, S; Harkness, DD; Heinemeier, J; McGee, E; Naysmith, P; Possnert, G; van der Plicht, H; van Strydonck, M; Cook, Gordon T.

    C-14 measurement uses a number of standards and reference materials with different properties. Historically the absolute calibration of C-14 measurement was tied to 1890 wood, through the 'primary' standard of NBS-OxI (produced by the National Bureau of Standards, now NIST - National Institute of

  13. Determination of the thermal neutron induced O-17(n,alpha) C-14 reaction cross section

    NARCIS (Netherlands)

    Wagemans, J; Wagemans, C; Bieber, R; Geltenbort, P

    1998-01-01

    The. O-17(n(th),alpha)C-14 reaction cross section was determined at the high flux reactor of the ILL in Grenoble relative to the known N-14(n(th),p)C-14 cross section. For the flux calibration measurements, N-14(2) from the air was used. The O-17(n,alpha) measurements were performed with several

  14. Segregation effects and phase developments during solidification of alloy 625

    DEFF Research Database (Denmark)

    Højerslev, Christian; Tiedje, Niels Skat; Hald, John

    2006-01-01

    contained gamma-phase, Laves phase and, if carbon was dissolved in the liquid, niobium rich carbides formed. Molybdenum and niobium showed strong tendencies to segregate. Their segregation was balanced by inverse segregation of nickel and iron. The chromium concentration remained almost constant in gamma...

  15. Spectral analysis of colour-quenched and chemically quenched C-14 samples; Estudio espectral de muestras de C-14 con extincion quimica y por color en centelleo liquido

    Energy Technology Data Exchange (ETDEWEB)

    Scott, P. E.; Grau, A.

    1987-07-01

    In this paper pairs of pulse height distribution curves, of C-14 samples, colour-quenched and chemically quenched was obtained. The possibility to choose a counting window in order to obtain the counting efficiency curves, for both type of quenching was studied. (Author) 7 refs.

  16. Polyethylene composites containing a phase change material having a C14 straight chain hydrocarbon

    Science.gov (United States)

    Salyer, Ival O.

    1987-01-01

    A composite useful in thermal energy storage, said composite being formed of a polyethylene matrix having a straight chain alkyl hydrocarbon incorporated therein, said polyethylene being crosslinked to such a degree that said polyethylene matrix is form stable and said polyethylene matrix is capable of absorbing at least 10% by weight of said straight chain alkyl hydrocarbon; the composite is useful in forming pellets or sheets having thermal energy storage characteristics.

  17. Syntheses of the C1-C14 and C15-C25 fragments of amphidinolide C.

    Science.gov (United States)

    Wu, Dimao; Forsyth, Craig J

    2013-03-15

    Divergent syntheses of the C1-C14 and C15-C25 fragments of amphidinolide C have been achieved. The synthesis of the C15-C25 fragment featured cobalt-catalyzed modified Mukaiyama aerobic alkenol cyclization and sulfur-directed regiocontrolled Wacker oxidation of an internal alkene. The C1-C14 fragment was established by alkenyllithium addition to an aldehyde followed by a challenging olefination of a highly inert C9 ketone.

  18. Algal C-14 and total carbon metabolisms 2. Experimental observations with the diatom Skeletonema costatum

    DEFF Research Database (Denmark)

    Williams, P.J.L.; Robinson, C.; Søndergaard, M.

    1996-01-01

    Three sets of comparisons of net and gross inorganic carbon assimilation and C-14 uptake were made with an axenic culture of Skeletonema costatum. The comparisons showed that in the physiological window studied (10-20% of the intrinsic generation time and gross photosynthesis/respiration ratios o...

  19. Effect of height of cut on translocation of C-14-labelled assimilates in ...

    African Journals Online (AJOL)

    A pot experiment was conducted in the glasshouse to determine the effect of three heights of cut on translocation of C-14-labelled assimilates in Eragrostis curvula cv. Ermelo. Autoradiographs revealed that to produce regrowth plants defoliated to a height of 7,5 cm did not draw on their reserves significantly and that both ...

  20. A chronology of the Scythian antiquities of Eurasia based on new archaeological and C-14 data

    NARCIS (Netherlands)

    Alekseev, A.Yu.; Bokovenko, N.A.; Boltrik, Yu.; Chugunov, K.A.; Cook, G.; Dergachev, V.A.; Kovalyukh, N.; Possnert, G.; Plicht, J. van der; Scott, E.M.; Sementsov, A.; Skripkin, V.; Vasiliev, S.; Zaitseva, G.

    2001-01-01

    The paper is compares the chronology of the monuments of the Scythian epoch located in the east and west of the Eurasian steppe zone on the basis of both archaeological and radiocarbon data. The lists of C-14 dates for the monuments located in different parts of Eurasia are presented according to

  1. Una fecha de C-14 para los campos de urnas de la meseta Oriental

    Directory of Open Access Journals (Sweden)

    María Luisa CERDEÑO

    2009-10-01

    Full Text Available En esta breve comunicación queremos valorar las posibilidades de aceptación que puede ofrecer la fecha de C-14 de 950 a.C. obtenida en el nivel inferior del yacimiento de La Coronilla (Molina de Aragón, Guadalajara, correspondiente a un asentamiento de Campos de Urnas de la zona1.

  2. GUA KETUK DI KAWASAN KARST PASIR PAWON KANDUNGAN BUDAYA DAN PERTANGGALAN C14 KETUK CAVE AT PASIR PAWON KARST AREA: CULTURES AND ITS C14 CHRONOLOGY

    Directory of Open Access Journals (Sweden)

    Lutfi Yondri

    2016-06-01

    ABSTRAK Gua Ketuk merupakan gugusan gua yang terdiri dari enam ruang gua. Gua ini terletak satu kawasan dengan Gua Pawon, termasuk dalam lingkungan karst Pasir Pawon. Pengumpulan data arkeologi di Gua Ketuk dilakukan dengan menerapkan metode survei dan ekskavasi. Berdasarkan hasil penelitian yang dilakukan dapat disimpulkan tidak semua ruang gua memiliki indikasi pernah dimanfaatkan sebagai tempat berkativitas oleh masyarakat masa lalu. Tingallan artefaktual antara lain ditemukan di Gua Ketuk Ruang 3, 4, dan Gua Ketuk Atas. Analisis pertanggalan karbon (C14 yang diambil dari sampel tanah dan stalaktit telah dilakukan pada Gua Ketuk Ruang 4 dengan hasil pertanggalan 1560 + 140 BP untuk sampel tanah, sementara itu dari stalaktit diperoleh pertanggalan sekitar 3260 + 120 BP. Dari pertanggalan tersebut dapat disimpulkan bahwa aktivitas manusia di gua tersebut jauh lebih kemudian dibandingkan dengan yang berlangsung di Gua Pawon dengan rentang pertanggalan antara 5660 + 180 BP sampai 9525 + 200 BP.   Kata Kunci: gua, tinggalan Budaya, analisis kronologi, umur karbon, hunian gua.

  3. Phase Transformation in Cast Superaustenitic Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Lee Phillips, Nathaniel Steven [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    Superaustenitic stainless steels constitute a group of Fe-based alloys that are compositionally balanced to have a purely austenitic matrix and exhibit favorable pitting and crevice corrosion resistant properties and mechanical strength. However, intermetallic precipitates such as sigma and Laves can form during casting or exposure to high-temperature processing, which degrade the corrosion and mechanical properties of the material. The goal of this study was to accurately characterize the solid-solid phase transformations seen in cast superaustenitic stainless steels. Heat treatments were performed to understand the time and temperature ranges for intermetallic phase formations in alloys CN3MN and CK3MCuN. Microstructures were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy and wavelength dispersive spectroscopy (EDS, WDS). The equilibrium microstructures, composed primarily of sigma and Laves within purely austenitic matrices, showed slow transformation kinetics. Factors that determine the extent of transformation, including diffusion, nucleation, and growth, are discussed.

  4. Synthesis of the c14-c25 subunit of bafilomycin A1.

    Science.gov (United States)

    Eustache, Florence; Dalko, Peter I; Cossy, Janine

    2003-12-26

    The enantioselective synthesis of the C14-C25 subunit of bafilomycin A1 was realized in a convergent route. The sequence involves two dynamic kinetic resolution steps of 2-alkyl 1,3-diketones that use optically active ruthenium complexes, an anti-selective reduction of a beta-hydroxyketone to control the C23 stereogenic center, and an aldol-type reaction under Evans' conditions, which sets the C17 and C18 stereogenic centers.

  5. Synthesis of the derivatives of 6-amino-uracil labelled with C-14

    Czech Academy of Sciences Publication Activity Database

    Elbert, Tomáš; Hezký, Petr; Jansa, Petr

    2016-01-01

    Roč. 59, č. 14 (2016), s. 615-618 ISSN 0362-4803. [International Isotope Symposium on the Synthesis and Applications of Isotopes and Isotopically Labelled Compounds /12./. Princeton, 07.06.2015-11.06.2015] R&D Projects: GA MŠk LG13002 Institutional support: RVO:61388963 Keywords : 6-amino-uracil derivatives * specific activity assay using NMR * [C-14]cyanoacetic acid Subject RIV: CC - Organic Chemistry Impact factor: 1.745, year: 2016

  6. The abundances of H-3 and C-14 in the solar wind. [measured by lunar soil analysis

    Science.gov (United States)

    Fireman, E. L.; Defelice, J.; Damico, J.

    1976-01-01

    Tritium is measured as a function of depth in a Surveyor 3 sample. The upper limit for solar-wind-implanted tritium gives a H-3/H-1 limit for the solar wind of 1 part in one hundred billion. The temperature release patterns of C-14 from lunar soils are measured. The C-14 release patterns from surface soils differ from a trench-bottom soil and give evidence for the presence of C-14 in the solar wind with a C-14/H-1 ratio of approximately 4 parts in one hundred billion. The implications of these radionuclide abundances in the solar wind are discussed.

  7. Anomalous compression behavior in a C15 Laves compound CeAl2 under high pressure

    Science.gov (United States)

    Tateno, Shota; Kishii, Nobuya; Ohashi, Masashi; Miyagawa, Hidenori; Oomi, Gendo; Satoh, Isamu; Miyajima, Nobuyoshi; Yagi, Takehiko

    2017-10-01

    Although there have been quite a number of discrepancies in the compression curves of CeAl2, such results come from the lattice compression at non-hydrostatic condition by solidification of pressure transmitting medium. We have carried out the powder X-ray diffraction measurement of CeAl2 under hydrostatic pressure with helium gas as pressure-transmitting medium which achieves the best hydrostatic conditions. Although no splitting of the peak is observed in the present diffraction pattern, it is found that a full width at half maximum is enhanced above 20 GPa for several Bragg reflections. Such behaviors suggest the existence of a new pressure-induced structural phase transition which is not observed in the previous reports under non-hydrostatic pressure.

  8. Wine ethanol C-14 as a tracer for fossil fuel CO2 emissions in Europe : Measurements and model comparison

    NARCIS (Netherlands)

    Palstra, Sanne W. L.; Karstens, Ute; Streurman, Harm-Jan; Meijer, Harro A. J.

    2008-01-01

    C-14 (radiocarbon) in atmospheric CO2 is the most direct tracer for the presence of fossil-fuel-derived CO2 (CO2-ff). We demonstrate the C-14 measurement of wine ethanol as a way to determine the relative regional atmospheric CO2-ff concentration compared to a background site ("regional CO2-ff

  9. Use of miniature C-14 counters in dating and authentication in the museum

    Energy Technology Data Exchange (ETDEWEB)

    Harbottle, G.; Sayre, E.V.; Stoenner, R.W.

    1983-01-01

    Curators often do not understand the basis for the C-14 method of age determination and its limitations. Purpose of this paper is to describe the underlying principles, and how these must influence the interpretation of the radiocarbon measurement of a museum specimen in terms of age. Several techniques for that measurement are described briefly, focussing on the miniature proportional counters that were developed for the Smithsonian Institution, and three museum problems are described which were attacked, and some interesting further research on museum objects that has been proposed. Finally some projections on the future applications of the different methods are made, in the context of museum work.

  10. Concise epoxide-based synthesis of the C14-C25 bafilomycin A(1) polypropionate chain.

    Science.gov (United States)

    Valentín, Elizabeth M; Mulero, Marlenne; Prieto, José A

    2012-04-25

    An efficient non-aldol convergent synthesis of the C14-C25 polyketide fragment of bafilomycin A(1) was completed in 16% overall yield and 8 steps in its longest linear sequence. This synthesis highlights the formation of the key fragments using a three-step sequence of epoxide cleavage, alkyne reduction, and epoxidation developed in our laboratory; starting from suitably protected enantiomeric epoxides of trans-2,3-epoxybutanol. This chemistry represents a quick asymmetric and diastereoselective construction of the polyketide chain of bafilomycin A(1), in which every stereogenic center was constructed using solely epoxide chemistry.

  11. Effective modern C++ 42 specific ways to improve your use of C++11 and C++14

    CERN Document Server

    Meyers, Scott

    2015-01-01

    At first glance, C++11 and C++14 are defined by the new features they introduce, e.g., auto type declarations, move semantics, lambda expressions, and concurrency support. Information on these features is easy to come by, but learning to apply them effectively (such that the resulting software is correct, efficient, maintainable, and portable) is more challenging. That’s the role of this book. It describes how to write effective software using C++11 and C++14, i.e., using modern C++. Topics include: * The pros and cons of uniform initialization, noexcept specifications, perfect forwarding, and smart pointer make functions. * The relationships among std::move, std::forward, rvalues references, and universal references. * The most effective forms of lambda capture. * How best practices in “old” C++ programming (i.e., C++98) require revision for modern C++. Effective Modern C++ follows the proven format of Scott Meyers’ earlier Effective books (Effective C++, More Effective C++, and Effective STL), but c...

  12. Cold Reversal on Kodiak Island, Alaska, Correlated with the European Younger Dryas by Using Variations of Atmospheric C-14 Content

    Science.gov (United States)

    Hajdas, Irka; Bonani, Georges; Boden, Per; Peteet, Dorothy M.; Mann, Daniel H.

    1999-01-01

    High-resolution AMS (accelerator-mass-spectrometer) radiocarbon dating was performed on late-glacial macrofossils in lake sediments from Kodiak Island, Alaska, and on shells in marine sediments from southwest Sweden. In both records, a dramatic drop in radiocarbon ages equivalent to a rise in the atmospheric C-14 by approximately 70%. coincides with the beginning of the cold period at 11000 yr B.P. (C-14 age). Thus our results show that a close correlation between climatic records around the globe is possible by using a global signature of changes in atmospheric C-14 content.

  13. Thermal Stability of Intermetallic Phases in Fe-rich Fe-Cr-Ni-Mo Alloys

    Science.gov (United States)

    Yang, Ying; Tan, Lizhen; Busby, Jeremy T.

    2015-09-01

    Understanding the thermal stability of intermetallic phases in Fe-rich Fe-Cr-Ni-Mo alloys is critical to alloy design and application of Mo-containing austenitic steels. Coupled with thermodynamic modeling, the thermal stability of intermetallic Chi and Laves phases in two Fe-Cr-Ni-Mo alloys was investigated at 1273 K, 1123 K, and 973 K (1000 °C, 850 °C, and 700 °C) for different annealing times. The morphologies, compositions, and crystal structures of the precipitates of the intermetallic phases were carefully examined by scanning electron microscopy, electron probe microanalysis, X-ray diffraction, and transmission electron microscopy. Two key findings resulted from this study. First, the Chi phase is stable at high temperature, and with the decreasing temperature it transforms into the Laves phase that is stable at low temperature. Secondly, Cr, Mo, and Ni are soluble in both the Chi and Laves phases, with the solubility of Mo playing a major role in the relative stability of the intermetallic phases. The thermodynamic models that were developed were then applied to evaluating the effect of Mo on the thermal stability of intermetallic phases in type 316 and NF709 stainless steels.

  14. Ingestion dose pathway parameters of H-3 and C-14 in Korea

    Energy Technology Data Exchange (ETDEWEB)

    Yang-Geun Chung; Gab-Bock Lee; Sun-Young Bang [Korea Electric Power Research Institute (Korea, Republic of); Seung-Ong Lee [Korea Hydro and Nuclear Power Cooperation (Korea, Republic of)

    2006-07-01

    Full text of publication follows: H-3 and C-14 are the main nuclides for public ingestion dose around nuclear power plants in Korea. Key parameters of H-3 and C-14 ingestion dose pathways are the fractions of moisture, hydrogen, and carbon in agricultural vegetation. In this study, representative values of the moisture, hydrogen, and carbon contents for categorized food groups were established. The food stuffs are classified into four groups such as grain, leafy vegetable, root vegetable, and fruit. Methods Weighting factors for individual food items were considered to calculate representative values of each food group using the 2001-2002 national dietary survey, published by the Ministry of Health and Welfare (MOHW). The weighting factor for individual food stuff was determined by the ratio of each food item to the total intake of each food group. Representative values of the moisture, hydrogen, and carbon contents for the four food groups were calculated using the annual weighting factor and the fractions of moisture, hydrogen, and carbon of individual food stuff based on the sixth revision of Food Composition Table published by the Rural Living Science Research Institute (RLSI). Results The weighting factor of rice in grain group was 95% on a yearly basis. Those of Chinese cabbage in leafy vegetable group and radish in root vegetable group were 58% and 52%, respectively. The fruit consumption varied with seasons. Annual weighting factors of apple, persimmon, water melon, and pear in fruit were 21%, 18%, 17%, and 15%, respectively. The respective fractions of moisture in grain, leafy vegetable, root vegetable, and fruit were 10.8%, 93.0%, 88.3%, and 88.0%: those of hydrogen were 5.6%, 0.4%, 0.7%, and 0.74%: those of carbon were 39.68%, 2.84%, 4.98%, and 5.23%. The hydrogen fraction of root vegetable was 75% larger than that of leafy vegetable. The values of moisture, hydrogen, and carbon contents in agricultural vegetation calculated from the Food Composition

  15. TL, OSL and C-14 dating results of the sediments and bricks from mummified nuns' grave

    Directory of Open Access Journals (Sweden)

    Diego R.G. Tudela

    2012-06-01

    Full Text Available This paper presents the results of TL and OSL dating of soil and fragments of bricks from a grave, which was occupied by two mummified nuns, found at "Luz" Monastery, located in the state of São Paulo, Brazil. The TL and OSL ages were compared to C-14 dating ones obtained from bone collagens of the mummies. The majority of the ages is related to the eighteenth century. The gamma-ray spectroscopy was used to evaluate natural radioisotope concentrations in the samples, and by using these concentrations the annual dose rates, from 3.0 to 5.3 Gy/kyr, were obtained. Neutron activation analysis was performed and the radioisotope contents results are in agreement with those obtained by gamma-ray spectroscopy. The contents of U, Th and Ce elements were higher than those found in usual sediments.Este artigo apresenta os resultados de datação por TL e OSL de solos, e fragmentos de tijolos de um túmulo, que foi ocupado por duas freiras mumificadas encontradas no Mosteiro da "Luz", localizado no Estado de São Paulo, Brasil. As idades encontradas por TL e OSL foram comparadas às obtidas a partir de C-14 dos colágenos contidos em amostras de osso das múmias. A maioria das idades obtidas são do século XVIII. A espectroscopia de radiação-gama foi utilizada para avaliar concentrações de radioisótopos naturais nas amostras e para calcular as taxas de dose anual que resultaram em 3,0 a 5,3 Gy/kano. As concentrações radioativas são próximas daquelas obtidas através de Análise por Ativação de Nêutrons. Os conteúdos de elementos U, Th e Ce são superiores aos encontrados na maioria dos sedimentos.

  16. Longterm storage of post-packaged bread by controlling spoilage pathogens using Lactobacillus fermentum C14 isolated from homemade curd.

    Directory of Open Access Journals (Sweden)

    Soma Barman

    Full Text Available One potent lactic acid bacterial strain C14 with strong antifungal activity was isolated from homemade curd. Based on morphological as well as biochemical characters and 16S rDNA sequence homology the strain was identified as Lactobacillus fermentum. It displayed a wide antimicrobial spectrum against both Gram-positive and Gram-negative pathogenic bacteria, and also against number of food spoilage, plant and human pathogenic fungi. The cell free supernatant (CFS of the strain C14 was also effective against the fungi tested. Inhibition of radial growth of Penicillium digitatum, Trichophyton rubrum and Mucor sp. was noticed in the presence of CFS of C14 even at low concentration (1%. More than 94.3 ± 1.6% and 91.5 ± 2.2% inhibition of conidial germination of P. digitatum and Mucor sp. were noticed in the presence of 10-fold-concentrated CFS of C14. Massive deformation of the fungal mycelia was observed by SEM studies, and losses of cellular proteins and DNA are also evident upon its treatment with C14. HPLC analysis revealed the presence of phenyl lactic acid, lactic acid along with some unidentified compounds in the antifungal extract. Challenge experiment showed immense potential of the strain C14 in preventing the spoilage of bread samples caused by Mucor sp. and Bacillus subtilis. The bread samples remained fresh upto 25 days even after inoculation with Mucor sp. (3.7 × 104 spores /ml and B. subtilis (4.6 × 104 CFU /ml. Along with the antifungal properties, the isolated lactic acid bacterial strain also showed very good antioxidant activities. Unchanged level of liver enzymes serum glutamic pyruvic transaminase and serum glutamic oxaloacetic transaminase in albino mice upon feeding with C14 also suggested non-toxic nature of the bacterial isolate.

  17. Chronology of last earthquake on Firouzkuh Fault using by C14

    Science.gov (United States)

    Nazari, H.; Ritz, J.-F.; Walker, R.; Alimohammadian, H.; Salamati, R.; Shahidi, A.; Patnaik, R.; Talebian, M.

    2009-04-01

    study during last 5 years on Firouzkuh fault (Nazari, 2006) reveal seismic activity of this area and the rate of movement in young event is about 2 mm/yr. The Firouzkuh fault is close to Firouzkuh, Damavand, Semnan and Tehran cities, therefore, gathering information about the geometry, mechanism and characteristics of activity of Firouzkuh active fault, will help us possible to prediction of fault activity and minimize the resulted damage. Therefore chronology of last event is quit important. In this paper to date the last seismic event in Firouzkuh fault. We have used C14 dating on human bones recovered from F2 trench, along with Quaternary sedimentology of young alluvium deposits of eastern Firouzkuh city. Paleoseismic analysis and C14 dating along the Firouzkuh left -Latural Strike-slip fault indicates the central Alborz has been witnessed large earthquakes during the late Holocene. Here we provide data from one of the two excavated trenches with 15 m length, 2m width and 4 m depth dug across the gauge zone in east Firouzkuh city, where we found some evidence for last paleoearthquake associated to seismic re-activity of Firouzkuh fault. The last seismic event is evidenced by cutting young superficial deposits and overlaid by alluvium deposits which yielded fragments of human bones. The generated C14 date from human bones, found at palaeoseismological trench (F2) on Firouzkuh fault, indicates an age of 1131-1187 B.P. year for alluvium deposits bearing these bones since from stratigraphical point view, this alluvium deposits (unit 4) are overlaid by faulted recent sediments (unit 1, and these recent sediments are cut due to recent activity of Firouzkuh fault, which are younger than human bone bearing alluvium, we may come to conclusion that the time event of this earth quake must be younger than obtained C14 date (1159 ± 28). In other hand since the human bones have been found in a place not similar to grave, we may assume that the body was on the surface at the time

  18. A role in immunity for Arabidopsis cysteine protease RD21, the ortholog of the tomato immune protease C14.

    Directory of Open Access Journals (Sweden)

    Takayuki Shindo

    Full Text Available Secreted papain-like Cys proteases are important players in plant immunity. We previously reported that the C14 protease of tomato is targeted by cystatin-like EPIC proteins that are secreted by the oomycete pathogen Phytophthora infestans (Pinf during infection. C14 has been under diversifying selection in wild potato species coevolving with Pinf and reduced C14 levels result in enhanced susceptibility for Pinf. Here, we investigated the role C14-EPIC-like interactions in the natural pathosystem of Arabidopsis with the oomycete pathogen Hyaloperonospora arabidopsidis (Hpa. In contrast to the Pinf-solanaceae pathosystem, the C14 orthologous protease of Arabidopsis, RD21, does not evolve under diversifying selection in Arabidopsis, and rd21 null mutants do not show phenotypes upon compatible and incompatible Hpa interactions, despite the evident lack of a major leaf protease. Hpa isolates express highly conserved EPIC-like proteins during infections, but it is unknown if these HpaEPICs can inhibit RD21 and one of these HpaEPICs even lacks the canonical cystatin motifs. The rd21 mutants are unaffected in compatible and incompatible interactions with Pseudomonas syringae pv. tomato, but are significantly more susceptible for the necrotrophic fungal pathogen Botrytis cinerea, demonstrating that RD21 provides immunity to a necrotrophic pathogen.

  19. High precision C-14 dating of Holocene peat deposits : A comparison of Bayesian calibration and wiggle-matching approaches

    NARCIS (Netherlands)

    Yeloff, Dan; Bennett, Keith D.; Mauquoy, Dmitri; Sillasoo, Ulle; van der Plicht, Johannes; van Geel, Bas; van Geel B., [No Value; Blaauw, Maarten

    The chronologies of five northern European ombrotrophic peat bogs subjected to a large ANIS C-14 dating effort (32-44 dates/site) are presented here. The results of Bayesian calibration (BCal) of dates with a prior assumption of chronological ordering were compared with a Bayesian wiggle-match

  20. Viscoelasticity moduli of aqueous C14EO8 solutions as studied by drop and bubble profile methods.

    Science.gov (United States)

    Fainerman, V B; Aksenenko, E V; Krägel, J; Miller, R

    2013-06-11

    The drop and bubble profile methods are used to study the viscoelasticity modulus of C14EO8 aqueous solutions within a wide concentration range. To determine the equilibrium concentration of the surfactant in the drop bulk, the correction is introduced for the surfactant losses caused by its adsorption on the drop surface. It is shown that with this correction the frequency dependencies of the viscoelasticity modulus measured by either of the two experimental techniques are almost the same. The theoretical model is used, which describes the surfactant dilational rheology assuming the diffusion-governed adsorption. The experimental data for C14EO8 solutions is described by the reorientation model that assumes the two states of surfactant molecules with different molar areas in the surface layer and the intrinsic compressibility of the molecules.

  1. Porous iron pellets for AMS C-14 analysis of small samples down to ultra-microscale size (10-25 mu gC)

    NARCIS (Netherlands)

    de Rooij, M.; van der Plicht, J.; Meijer, H. A. J.

    We developed the use of a porous iron pellet as a catalyst for AMS C-14 analysis of small samples down to ultra-microscale size (10-25 mu gC). It resulted in increased and more stable beam currents through our HVEE 4130 C-14 AMS system, which depend smoothly on the sample size. We find that both the

  2. Concise epoxide-based synthesis of the C14–C25 bafilomycin A1 polypropionate chain

    Science.gov (United States)

    Valentín, Elizabeth M; Mulero, Marlenne; Prieto, José A.

    2012-01-01

    An efficient non-aldol convergent synthesis of the C14–C25 polyketide fragment of bafilomycin A1 was completed in 16% overall yield and 8 steps in its longest linear sequence. This synthesis highlights the formation of the key fragments using a three-step sequence of epoxide cleavage, alkyne reduction, and epoxidation developed in our laboratory; starting from suitably protected enantiomeric epoxides of trans-2,3-epoxybutanol. This chemistry represents a quick asymmetric and diastereoselective construction of the polyketide chain of bafilomycin A1, in which every stereogenic center was constructed using solely epoxide chemistry. PMID:22500058

  3. Comparison of fusion cross sections for the 10B + 16O and 12C + 14N systems

    Science.gov (United States)

    del Campo, J. Gomez; Biggerstaff, J. A.; Dayras, R. A.; Shapira, D.; Snell, A. H.; Stelson, P. H.; Stokstad, R. G.

    1984-05-01

    The fusion cross sections for the 10B + 16O and 12C + 14N systems are compared for bombarding energies up to 18 MeV/nucleon. The energy spectra, angular distributions, and relative yields of the evaporation residues are analyzed in terms of simple kinematic considerations and Hauser-Feshbach calculations. Simultaneous determinations of mass, charge, and energy and two particle coincidence measurements at E14N=13 MeV/nucleon support the identification of evaporation residues based on inclusive measurements of Z and E alone. The gross characteristics of the residues are consistent with the main process being complete fusion followed by equilibrium decay. The excitation functions of the 10B + 16O and 12C + 14N systems show significant differences which cannot be explained in terms of simple macroscopic models. At the highest bombarding energies the fusion cross sections decrease as 1Ec.m. for both systems and are consistent with a maximum angular momentum limit of ~27ℏ.

  4. TL, OSL and C-14 dating results of the sediments and bricks from mummified nuns' grave

    Energy Technology Data Exchange (ETDEWEB)

    Tudela, Diego R.G.; Tatumi, Sonia H.; Yee, Marcio; Brito, Silvio L.M., E-mail: tatumi@fatecsp.br [Faculdades de Tecnologia de Sao Paulo (FATECs/CEETEPS/UNESP), Sao Paulo, SP (Brazil). Centro Estadual de Educacao Tecnologica Paula Souza; Morais, Jose L.; Morais, Daisy de; Piedade, Silvia C. [Universidade de Sao Paulo (USP), SP (Brazil). Museu de Arqueologia e Etnologia; Munita, Casimiro S.P.; Hazenfratz, Roberto [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2012-06-15

    This paper presents the results of TL and OSL dating of soil and fragments of bricks from a grave, which was occupied by two mummified nuns, found at 'Luz' Monastery, located in the state of Sao Paulo, Brazil. The TL and OSL ages were compared to C-14 dating ones obtained from bone collagens of the mummies. The majority of the ages is related to the eighteenth century. The gamma-ray spectroscopy was used to evaluate natural radioisotope concentrations in the samples, and by using these concentrations the annual dose rates, from 3.0 to 5.3 Gy/kyr, were obtained. Neutron activation analysis was performed and the radioisotope contents results are in agreement with those obtained by gamma-ray spectroscopy. The contents of U, Th and Ce elements were higher than those found in usual sediments. (author)

  5. Electronic absorption spectroscopy of matrix-isolated polycyclic aromatic hydrocarbon cations. II. The phenanthrene cation (C14H10+) and its 1-methyl derivative

    Science.gov (United States)

    Salama, F.; Joblin, C.; Allamandola, L. J.

    1994-01-01

    The ultraviolet, visible, and near infrared absorption spectra of phenanthrene (C14H10), 1-methylphenanthrene [(CH3)C14H9], and their radical ions [C14H10+; (CH3)C14H9+], formed by vacuum-ultraviolet irradiation, were measured in neon matrices at 4.2 K. The associated vibronic band systems and their spectroscopic assignments are discussed. The oscillator strengths were calculated for the phenanthrene ion and found lower than the theoretical predictions. This study presents the first spectroscopic data for phenanthrene and its methyl derivative trapped in a neon matrix where the perturbation of the isolated species by its environment is minimum; a condition crucial to astrophysical applications.

  6. Influence of Tungsten and Tantalum Content on Evolution of Secondary Phases in 9Cr RAFM Steels: An Experimental and Computational Study

    Science.gov (United States)

    Ravikirana; Mythili, R.; Saroja, S.

    2017-08-01

    This paper presents the results of a systematic study on the role of alloying elements W and Ta on the microstructural evolution in 9Cr-W-Ta-V-C Reduced Activation Ferritic/Martensitic steels during long-term thermal exposure in the temperature range of 773 K to 923 K (500 °C to 650 °C). The kinetics of evolution of secondary phases like M23C6, MX, and Laves phase crucially depend upon the W and Ta content of the steel in addition to temperature and time, which has been studied in detail using analytical transmission electron microscopy as well as predictive methods. The steel with 1 wt pct W and 0.06 wt pct Ta showed slow recovery below 873 K (600 °C) and no evidence for Laves phase at any temperature. Significant change in microstructure was observed after 10,000 hours of exposure at 923 K (650 °C), while recovery at short durations was retarded by nucleation of MX precipitates. Increase in both W and Ta content of the steel enhanced the tendency for the formation of Laves phase.

  7. Comparison of the Quantitative Values of C-14 and C-13 UBT to Reflect the Presence and Degree of Ongoing Helicobacter pylori Infection

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Seok Tae; Kim, Dong Wook; Jeong, Hwan Jeong; Sohn, Myung Hee [Chonbuk National University Medical School, Jeonju (Korea, Republic of)

    2008-06-15

    A urea breath test (UBT) using C-14 or C-13 has been developed for identifying Helicobacter (H) pylori infection on the basis of urease production with release of labeled CO{sub 2}. We investigated if the C-14 and C-13 UBT have the difference to reflect the presence and degree of H. pylori infection detected by gastroduodenoscopic biopsies (GBx) in the same patients. Thirty eight patients (M:F=28:10, age 53.4{+-}13.0 yrs) with upper gastrointestinal symptoms such as indigestion, gastric fullness or pain consecutively underwent C-14 UBT, GBx and C-13 UBT within one week before medications. For the C-14 UBT, a single breath sample was collected at 10 minutes after ingestion of C-14 urea (37 KBq) capsule and counting was done in a liquid scintillation counter for 1 minute, and the results were classified as positive ({>=}200 dpm), intermediate (50{approx}199 dpm) or negative (<50 dpm). For the C-13 UBT, the results were classified as positive ({>=}2.5) or negative (<2.5). The results of GBx with Giemsa stain were graded 0 (normal) to 4 (diffuse) according to the distribution of H. pylori by the Wyatt method. We compared C-14 UBT and C-13 UBT results with GBx grade as a gold standard. The prevalence of H. pylori infection by GBx with Giemsa stain was 25/38 (65.8%). In the assessment of the presence of H. pylori infection, the C-14 UBT global performance yielded sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of 92.0%, 92.3%, 95.8%, 91.7% and 92.1%, respectively. However, the C-13 UBT had sensitivity, specificity, PPV, NPV and accuracy of 96.0%, 84.6%, 92.3%, 91.7% and 92.1%, respectively. The more significant correlation in C-14 than C-13 UBT (r=0.948 vs r=0.819, p<0.001) was found between the value of UBT and the grade of distribution of H. pylori infection. We conclude that the diagnostic performance between C-14 and C-13 UBT to detect H. pylori infection is not significantly different, but the value of C-14 UBT

  8. Raman spectra of organic compounds kladnoite (C6H4(CO)2NH) and hoelite (C14H8O2)--rare sublimation products crystallising on self-ignited coal heaps.

    Science.gov (United States)

    Jehlicka, J; Zácek, V; Edwards, H G M; Shcherbakova, E; Moroz, T

    2007-12-15

    As minerals, aromatic compounds occur very rarely in nature. Not more than 10 of such minerals are known and most of them were described in the coal deposits where they were formed as a result of coal bed fires or burning of coal waste heaps. Raman spectra of kladnoite C(6)H(4)(CO)(2)NH (natural phthalimide) and hoelite C(14)H(8)O(2), (natural 9,10-anthraquinone) display complex features. Raman microspectroscopy help to detect these phases non-destructively directly in the frame of rare samples. Investigated minerals are transformation products formed from gaseous phase originating in natural pyrolytical process occurring in the frame of coal heaps and coal series outcrops. It is recommended to include Raman spectroscopic characteristics of similar materials in databases for exobiological studies.

  9. The cationic lipid, diC14 amidine, extends the adjuvant properties of aluminum salts through a TLR-4- and caspase-1-independent mechanism.

    Science.gov (United States)

    Wilmar, Arnaud; Lonez, Caroline; Vermeersch, Marjorie; Andrianne, Mathieu; Pérez-Morga, David; Ruysschaert, Jean-Marie; Vandenbranden, Michel; Leo, Oberdan; Temmerman, Stéphane T

    2012-01-05

    Adjuvant efficiency is critical for inducing a protective and long-lasting immune response against weak immunogenic antigens. Discovered more than 70 years ago, aluminum salts remain the most widely used adjuvant in human vaccine. Prone to induce a strong humoral response, alum fails to drive a cell-mediated immunity, which is essential to fight against intracellular pathogens. Adjuvant systems that contain more than one component may represent an excellent alternative for completing the lack of T cell immunity associated with the injection of alum-based vaccine. In this work, we demonstrated that the adjuvant effects of alum strongly benefited from combining with a cationic lipid, the diC14 amidine. Indeed, we measured a significant improvement of alum-driven IL-1β release when human macrophages were co-cultured with a mixed suspension of alum and the diC14 amidine. Morphological analysis suggested that diC14 amidine improved the alum uptake by phagocytes. Furthermore, the addition of diC14 amidine to alum efficiently enhanced antigen processing and cross-presentation by antigen presenting cells. The biological relevance of these in vitro data was assessed by measuring the in vivo development of a cytotoxic activity and the enhanced synthesis of antigen-specific immunoglobulins after immunization with alum combined to diC14 amidine. Mechanistically, we demonstrated that diC14 amidine supported the alum adjuvanticity independently of the TLR-4 and caspase-1 agonist activities of the cationic lipid. Based on our findings, we conclude that diC14 amidine works synergistically with alum to achieve higher immune protection after vaccination. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Efficiency of Vanilla, Patchouli and Ylang Ylang Essential Oils Stabilized by Iron Oxide@C14 Nanostructures against Bacterial Adherence and Biofilms Formed by Staphylococcus aureus and Klebsiella pneumoniae Clinical Strains

    Directory of Open Access Journals (Sweden)

    Maxim Bilcu

    2014-11-01

    Full Text Available Biofilms formed by bacterial cells are associated with drastically enhanced resistance against most antimicrobial agents, contributing to the persistence and chronicization of the microbial infections and to therapy failure. The purpose of this study was to combine the unique properties of magnetic nanoparticles with the antimicrobial activity of three essential oils to obtain novel nanobiosystems that could be used as coatings for catheter pieces with an improved resistance to Staphylococcus aureus and Klebsiella pneumoniae clinical strains adherence and biofilm development. The essential oils of ylang ylang, patchouli and vanilla were stabilized by the interaction with iron oxide@C14 nanoparticles to be further used as coating agents for medical surfaces. Iron oxide@C14 was prepared by co-precipitation of Fe+2 and Fe+3 and myristic acid (C14 in basic medium. Vanilla essential oil loaded nanoparticles pelliculised on the catheter samples surface strongly inhibited both the initial adherence of S. aureus cells (quantified at 24 h and the development of the mature biofilm quantified at 48 h. Patchouli and ylang-ylang essential oils inhibited mostly the initial adherence phase of S. aureus biofilm development. In the case of K. pneumoniae, all tested nanosystems exhibited similar efficiency, being active mostly against the adherence K. pneumoniae cells to the tested catheter specimens. The new nanobiosystems based on vanilla, patchouli and ylang-ylang essential oils could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with anti-adherence and anti-biofilm properties.

  11. Efficiency of vanilla, patchouli and ylang ylang essential oils stabilized by iron oxide@C14 nanostructures against bacterial adherence and biofilms formed by Staphylococcus aureus and Klebsiella pneumoniae clinical strains.

    Science.gov (United States)

    Bilcu, Maxim; Grumezescu, Alexandru Mihai; Oprea, Alexandra Elena; Popescu, Roxana Cristina; Mogoșanu, George Dan; Hristu, Radu; Stanciu, George A; Mihailescu, Dan Florin; Lazar, Veronica; Bezirtzoglou, Eugenia; Chifiriuc, Mariana Carmen

    2014-11-04

    Biofilms formed by bacterial cells are associated with drastically enhanced resistance against most antimicrobial agents, contributing to the persistence and chronicization of the microbial infections and to therapy failure. The purpose of this study was to combine the unique properties of magnetic nanoparticles with the antimicrobial activity of three essential oils to obtain novel nanobiosystems that could be used as coatings for catheter pieces with an improved resistance to Staphylococcus aureus and Klebsiella pneumoniae clinical strains adherence and biofilm development. The essential oils of ylang ylang, patchouli and vanilla were stabilized by the interaction with iron oxide@C14 nanoparticles to be further used as coating agents for medical surfaces. Iron oxide@C14 was prepared by co-precipitation of Fe+2 and Fe+3 and myristic acid (C14) in basic medium. Vanilla essential oil loaded nanoparticles pelliculised on the catheter samples surface strongly inhibited both the initial adherence of S. aureus cells (quantified at 24 h) and the development of the mature biofilm quantified at 48 h. Patchouli and ylang-ylang essential oils inhibited mostly the initial adherence phase of S. aureus biofilm development. In the case of K. pneumoniae, all tested nanosystems exhibited similar efficiency, being active mostly against the adherence K. pneumoniae cells to the tested catheter specimens. The new nanobiosystems based on vanilla, patchouli and ylang-ylang essential oils could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with anti-adherence and anti-biofilm properties.

  12. Thermodynamic and structural study of the Zr-Ni-Cr ternary system (Zr<50 at%) and of its equilibria with hydrogen: electrochemical application; Etude thermodynamique et structurale du systeme ternaire Zr-Ni-Cr (Zr<50at%) et de ses equilibres avec l`hydrogene: application electrochimique

    Energy Technology Data Exchange (ETDEWEB)

    Joubert, J.M.

    1995-07-12

    In the frame of the research on intermetallic compounds for nickel-hydride battery application, attention is focused on AB{sub 2} alloys so called Laves phases. ZrCr{sub 2}, for example, exhibits a large hydrogen capacity but a too low hydride formation equilibrium pressure for practical application. Moreover, the electrolyte (concentrated potassium hydroxide) involves surface passivation through blocking electrochemical mechanisms. First, the study is devoted to the adjustment of the hydride thermodynamic properties regarded to electrochemical application. This was achieved on ZrCr{sub 2} by substitution of chromium by nickel. In a second part surface properties are modified by the precipitation of secondary phases in equilibrium with the Laves phase. The Zr-Ni-Cr phase diagram has been determined at 1000 deg C in the ZrCr{sub 2}-ZrNi-Ni-Cr region and has revealed large solubility of nickel in C14 and C15 Laves phases as well as equilibrium of these phases with three Zr-Ni intermetallic compounds. The knowledge of this diagram has allowed the synthesis of biphasic alloys where the Laves phase of constant composition is in equilibrium with a secondary phase at variable rate. The study of hydrogenation properties of Laves phases has shown the possibility of adjusting the equilibrium pressure of its hydrides to electrochemical application keeping high hydrogen capacity. The hydrogenation properties of secondary phases were also characterized. Finally, it appeared that secondary phases precipitation with increasing rate in the Laves phase matrix produces a spectacular increase of electrochemical capacities. Such an effect of hydrogen by the modification of the surface in contact with electrolyte and by the diffusion of hydrogen from electrolyte to the Laves through the secondary phase when present. (author)

  13. A transport and fate model of C-14 in a bay of the Baltic Sea at SFR. Today and in future

    Energy Technology Data Exchange (ETDEWEB)

    Kumblad, L. [Stockholm Univ. (Sweden). Dept. of Systems Ecology

    2001-06-01

    The environmental transport and fate of a hypothetical release of radioactive carbon-14 from SFR-1 (the final repository for radioactive operational waste) was investigated using an ecosystem modelling approach. The approach involved identification, quantification and dynamic modelling of the main flows and storages of carbon both in the physical environment and in the food web. Carbon-14 was in the model introduced into the food web via photosynthesising organisms. Contamination of the aquatic ecosystem above SFR-1 was then assessed assuming a release of 5.13 x 10{sup 7} Bq/year for 1,000 years. Modelling results were used to estimate steady-state C-14 concentrations in biota, exposure (Gy) of biota and dose (Sv) to humans consuming contaminated organisms both if the discharge occurred today (2000 AD)and if it occurred in the future (4000 AD). Since the modelled area is characterised by a fast water exchange, most of the discharged C-14 was flushed out of the system more or less immediately (99.8% and 98.4% at 2000 AD and 4000 AD, respectively). However, a small fraction of the discharge was assimilated by primary producers (0.18% and 2.11%), which enabled subsequent transfer of C-14 to organisms at higher trophic levels (e.g. fish, seals and humans). The exported C-14 from the area was diluted to very low concentrations in the large recipient outside. Estimated exposures were very low, and differed significantly among the studied biota (17.2 x 10{sup -12} to 2.3 x 10{sup -6} Gy). In general the highest exposures were observed in benthic plants and benthic grazers followed by fish and benthos. Humans consuming large quantities of locally produced food (e.g.fish, mussels and algae) will receive an exposure in case of C-14 contamination. Estimated doses to humans were approximately 10-100 nSv per year, which is significantly lower than restrictions by the authorities. The developed model was also used to evaluate implications of various assumptions concerning the

  14. Analyse de l’aléa « lave torrentielle » sur le cône de déjection du torrent du Rioulong (Hautes-Pyrénées) : une approche par scénarios

    OpenAIRE

    Dominique Laigle et Christophe Peteuil

    2010-01-01

    En France, plus de quatre mille communes seraient menacées par les laves torrentielles. Phénomènes difficilement prévisibles, la protection contre les risques qu’elles génèrent repose donc essentiellement sur des mesures de prévention. Il est donc essentiel de connaître l'intensité et la probabilité d'occurrence des écoulements sur un site donné. À partir du diagnostic réalisé sur un torrent des Hautes-Pyrénées, les auteurs nous présentent ici une méthode d'analyse par scénarios, permettant a...

  15. Reassessment of the C-13/C-12 and C-14/C-12 isotopic fractionation ratio and its impact on high-precision radiocarbon dating

    NARCIS (Netherlands)

    Fahrni, Simon M.; Southon, John R.; Santos, Guaciara M.; Palstra, Sanne W. L.; Meijer, Harro A. J.; Xu, Xiaomei

    2017-01-01

    The vast majority of radiocarbon measurement results (C-14/C-12 isotopic ratios or sample activities) are corrected for isotopic fractionation processes (measured as C-13/C-12 isotopic ratios) that occur in nature, in sample preparation and measurement. In 1954 Harmon Craig suggested a value of 2.0

  16. High-entropy alloys: Interrelations between electron concentration, phase composition, lattice parameter, and properties

    Science.gov (United States)

    Gorban', V. F.; Krapivka, N. A.; Firstov, S. A.

    2017-10-01

    An analysis of more than 200 high-entropy alloys (HEA) allowed us to find interrelations between the electron concentration, phase composition, lattice parameter, and properties of solid solutions with bcc and fcc crystal lattices. Main conditions for the appearance of high-entropy chemical compounds, such as Laves, σ, and μ phases were determined. The necessary condition for the formation of 100% high-entropy σ phase is the formation of σ phase in two-component alloys for different combinations of elements, which are components of the HEA, and the electron concentration should be 6.7-7.3 electrons per atom. To form a 100% high-entropy Laves phase, the following conditions should be fulfilled: the total negative enthalpy of mixing of alloy is about -7 kJ/mol and less; the difference between the atom sizes in a pair is more than 12%; the enthalpy of the mixing of two present elements is less than -30 kJ/mol; and the average electron concentration is 6-7 electrons per atom. It was shown that the ratios of lattice parameters of solid-solution HEA, which were experimentally determined, to the lattice parameter of the most refractory metal in the HEA determine the value of the modulus of elasticity.

  17. Solid-Contact pH Sensor without CO2 Interference with a Superhydrophobic PEDOT-C14 as Solid Contact: The Ultimate "Water Layer" Test.

    Science.gov (United States)

    Guzinski, Marcin; Jarvis, Jennifer M; D'Orazio, Paul; Izadyar, Anahita; Pendley, Bradford D; Lindner, Ernő

    2017-08-15

    The aim of this study was to find a conducting polymer-based solid contact (SC) for ion-selective electrodes (ISEs) that could become the ultimate, generally applicable SC, which in combination with all kinds of ion-selective membranes (ISMs) would match the performance characteristics of conventional ISEs. We present data collected with electrodes utilizing PEDOT-C14, a highly hydrophobic derivative of poly(3,4-ethylenedioxythiophene), PEDOT, as SC and compare its performance characteristics with PEDOT-based SC ISEs. PEDOT-C14 has not been used in SC ISEs previously. The PEDOT-C14-based solid contact (SC) ion-selective electrodes (ISEs) (H+, K+, and Na+) have outstanding performance characteristics (theoretical response slope, short equilibration time, excellent potential stability, etc.). Most importantly, PEDOT-C14-based SC pH sensors have no CO2 interference, an essential pH sensors property when aimed for whole-blood analysis. The superhydrophobic properties (water contact angle: 136 ± 5°) of the PEDOT-C14 SC prevent the detachment of the ion-selective membrane (ISM) from its SC and the accumulation of an aqueous film between the ISM and the SC. The accumulation of an aqueous film between the ISM and its SC has a detrimental effect on the sensor performance. Although there is a test for the presence of an undesirable water layer, if the conditions for this test are not selected properly, it does not provide an unambiguous answer. On the other hand, recording the potential drifts of SC electrodes with pH-sensitive membranes in samples with different CO2 levels can effectively prove the presence or absence of a water layer in a short time period.

  18. C14–22 n-Alkanes in Soil from the Freetown Layered Intrusion, Sierra Leone: Products of Pt Catalytic Breakdown of Natural Longer Chain n-Alkanes?

    Directory of Open Access Journals (Sweden)

    John F. W. Bowles

    2018-03-01

    Full Text Available Soil above a platinum-group element (PGE-bearing horizon within the Freetown Layered Intrusion, Sierra Leone, contains anomalous concentrations of n-alkanes (CnH2n+2 in the range C14 to C22 not readily attributable to an algal or lacustrine origin. Longer chain n-alkanes (C23 to C31 in the soil were derived from the breakdown of leaf litter beneath the closed canopy humid tropical forest. Spontaneous breakdown of the longer chain n-alkanes to form C14–22 n-alkanes without biogenic or abiogenic catalysts is unlikely as the n-alkanes are stable. In the Freetown soil, the catalytic properties of the PGE (Pt in particular may lower the temperature at which oxidation of the longer chain n-alkanes can occur. Reaction between these n-alkanes and Pt species, such as Pt2+(H2O2(OH2 and Pt4+(H2O2(OH4 can bend and twist the alkanes, and significantly lower the Heat of Formation. Microbial catalysis is a possibility. Since a direct organic geochemical source of the lighter n-alkanes has not yet been identified, this paper explores the theoretical potential for abiogenic Pt species catalysis as a mechanism of breakdown of the longer n-alkanes to form C14–22 alkanes. This novel mechanism could offer additional evidence for the presence of the PGE in solution, as predicted by soil geochemistry.

  19. In vitro antibacterial activity of meclofenamate metal complexes with Cd(II), Pb(II), Co(II), and Cu(II). Crystal structures of [Cd(C14H10NO2Cl2)2∙(CH3OH)]n and [Cu(C14H10NO2Cl2)2(C5H5N)2].

    Science.gov (United States)

    Palacios-Hernández, T; Höpfl, H; Sánchez-Salas, J L; González-Vergara, E; Pérez-Benítez, A; Quiroz-Alfaro, M A; Méndez-Rojas, M A

    2014-10-01

    The synthesis and characterization of five metal complexes derived from sodium meclofenamate (1) are reported: [Cd(C14H10NO2Cl2)2∙(CH3OH)]n∙nCH3OH (6), [Pb(C14H10NO2Cl2)2]n (7), [Co(C14H10NO2Cl2)]n (8), [Cu(C14H10NO2Cl2)]n (9), and [Cu(C14H10NO2Cl2)2(C5H5N)2] (10) (C14H10NO2Cl2=meclofenamate; C5H5N=pyridine). The characterization of the compounds was based on FTIR and UV-visible spectroscopy, mass spectrometry and, in the case of complexes 6 and 10, single crystal X-ray diffraction analysis. For compound 6, the structural analysis revealed a 1-D polymeric chain structure, in which pentagonal planar [Cd(RCOO)2(CH3OH)] units were linked through bridging carboxylate functions of the meclofenamate ligands. The overall coordination environment of the Cd(II) ions was seven-coordinate, since each carboxylate group exhibited a μ3-bridging coordination mode. On the other hand, for complex 10 a discrete mononuclear structure was observed, in which the six-coordinate copper(II) metal atoms were coordinated by two pyridine molecules and the carboxylate functions of two meclofenamate entities, in an anisobidentate coordination mode. The antibacterial activity of compounds 6-9 against four strains of Gram positive (Staphylococcus aureus and Bacillus subtilis) and Gram negative (Escherichia coli and Pseudomonas aeruginosa) bacteria was examined, finding that only complex 6 was active. Additionally, it was found that the Co(II) and Cu(II) complexes 8 and 9 showed peroxidase activity. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Compatibility of technologies with regulations in the waste management of H-3, I-129, C-14, and Kr-85. Part I. Initial information base

    Energy Technology Data Exchange (ETDEWEB)

    Trevorrow, L.E.; Vandegrift, G.F.; Kolba, V.M.; Steindler, M.J.

    1983-08-01

    This report summarizes the information base that was collected and reviewed in preparation for carrying out an analysis of the compatibility with regulations of waste management technologies for disposal of H-3, I-129, C-14, and Kr-85. Based on the review of this literature, summaries are presented here of waste-form characteristics, packaging, transportation, and disposal methods. Also discussed are regulations that might apply to all operations involved in disposal of the four nuclides, including the processing of irradiated fuel in a fuel reprocessing plant, packaging, storage, transport, and final disposal. The compliance assessment derived from this information is reported in a separate document. 309 references.

  1. Microstructure of Z-phase strengthened martensitic steels: Meeting the 650°C challenge

    DEFF Research Database (Denmark)

    Liu, Fang; Rashidi, Masoud; Hald, John

    2017-01-01

    content in the steels is the governing factor in this transformation. The impact toughness of some test alloys was rather low. This is attributed to the formation of a continuous W-rich film along prior austenite grain boundaries. Cu and C addition to the test alloys changed Laves phase morphology......We studied three series of Z-phase strengthened steels using scanning electron microscopy, transmission electron microscopy, and atom probe tomography to reveal the detailed microstructure of these steels. In particular, the phase transformation from M(C,N) to Z-phase (CrMN) was studied. Carbon...... to discrete precipitates and improved toughness dramatically. BN particles were found in some steels. Formation of BN is directly linked to the B concentration in the steels....

  2. Correlation factors for C-14, Cl-36, Ni-59, Ni-63, Mo-93, Tc-99, I-129 and Cs-135. In operational waste for SFR 1

    Energy Technology Data Exchange (ETDEWEB)

    Lindgren, Maria; Pettersson, Michael; Wiborgh, Marie (Kemakta AB, Stockholm (SE))

    2007-01-15

    The use of correlation factors is one possibility to estimate a reference radionuclide inventory for the purpose of safety assessment studies, when waste-type specific information is not at hand. The correlation factor approach requires that there is a correlation between the activity content of the difficult-to-measure nuclide and the key nuclide. A safety assessment of a future deep repository for low and intermediate level waste (SFL 3-5) was conducted during the second half of the 1990's. Within that project, correlation factors for estimating the inventory of radionuclides which are difficult to measure experimentally were developed. These factors have also partly been used to estimate a reference inventory for SFR 1. Based on a literature survey and recent reports published by SKB, it is concluded that new information is available making an update of some correlation factors relevant. For these radionuclides, reported data from estimations and measurements of radionuclide content and correlation factors in different types of radioactive wastes are summarised. The data is evaluated and updated correlation factors representative for fresh waste for eight radionuclides (C-14, Cl-36, Ni-59, Ni-63, Mo-93, Tc-99, I-129 and Cs-135) are suggested. New information from measurements in Swedish NPP has made it possible to define factors that are BWR and PWR specific for C-14, Ni-59 and Ni-63. The uncertainties in suggested data and the applicability of the correlation factors for estimates of the radionuclide content in operational waste are commented upon

  3. D-seco-Vitamin D analogs having reversed configurations at C-13 and C-14: Synthesis, docking studies and biological evaluation.

    Science.gov (United States)

    Szybinski, Marcin; Sokolowska, Katarzyna; Sicinski, Rafal R; Plum, Lori A; DeLuca, Hector F

    2017-10-01

    Prompted by results of molecular modeling performed on the seco-d-ring-vitamins D, we turned our attention to such analogs, having reversed configurations at C-13 and C-14, as the next goals of our studies on the structure-activity relationship for vitamin D compounds. First, we developed an efficient total synthesis of the "upper" C/seco-d-ring fragment with a 7-carbon side chain. Then, we coupled it with A-ring fragments using Sonogashira or Wittig-Horner protocol, providing the targeted D-seco analogs of 1α,25-dihydroxyvitamin D 3 and 1α,25-dihydroxy-19-norvitamin D 3 possessing a vinyl substituent at C-14 and a double bond between C-17 and C-20. The affinities of the synthesized vitamin D analogs to the full-length recombinant rat VDR were examined, as well as their differentiating and transcriptional activities. In these in vitro tests, they were significantly less active compared to 1α,25-(OH) 2 D 3 . Moreover, it was established that the analogs tested in vivo in rats showed no calcemic potency. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Characterization of oxidation products on a ZrFe{sub 2}-type laves intermetallic exposed to 200{degree}C steam.

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, D. P.; Dietz, N.; Finnegan, N.

    2000-11-20

    The release of radioactive elements from the stainless steel-15 wt% zirconium (SS-15Zr) metal waste form will be governed by the corrosion behavior of ZrFe{sub 2}-type intermetallics phases present in the alloy. In this article, oxidation products that formed on a ZrFe{sub 2}-type intermetallic sample exposed to 200 C steam were characterized by Auger Electron Spectroscopy (AES) and Transmission Electron Microscopy (TEM). The data revealed two oxide layers on the sample surface: an outer crystalline iron-oxide layer and an inner amorphous zirconium-rich layer believed to be zirconium oxide. Thermodynamic considerations indicate that the zirconium-rich layer formed first. The iron-oxide layer appears to have resulted from the diffusion of iron through the zirconium-rich layer to the oxide-vapor interface.

  5. Temperature effects on microalgal photosynthesis-light responses measured by O-2 production, pulse-amplitude-modulated fluorescence, and C-14 assimilation

    DEFF Research Database (Denmark)

    Hancke, Kasper; Hancke, Torunn B.; Olsen, Lasse M.

    2008-01-01

    Short-term temperature effects on photosynthesis were investigated by measuring O-2 production, PSII-fluorescence kinetics, and C-14-incorporation rates in monocultures of the marine phytoplankton species Prorocentrum minimum (Pavill.) J. Schiller (Dinophyceae), Prymnesium parvum f. patelliferum (J...... three approaches. The maximum photosynthetic rate (P-max(C)) was strongly stimulated by temperature, reached an optimum for Pro. minimum only (20 degrees C-25 degrees C), and showed a similar relative temperature response for the three applied methods, with Q(10) ranging from 1.7 to 3.5. The maximum...... light utilization coefficient (alpha(C)) was insensitive or decreased slightly with increasing temperature. Absolute rates of O-2 production were calculated from pulse-amplitude-modulated (PAM) fluorometry measurements in combination with biooptical determination of absorbed quanta in PSII...

  6. Paleo-Environment and C-14 Dating: The Key to the Depositional Age of the Tha Chang and Related Sand Pits, Northeastern Thailand

    Science.gov (United States)

    Putthapiban, P.; Zolensky, M.; Jull, T.; Demartino, M.; Salyapongse, S.

    2012-01-01

    Tha Chang sand pits, Nakhon Ratchasima Province and many other sand pits in the area adjacent to the Mun River are characterized by their fluviatile environment in association with mass wasting deposits, along the paleo-river channel and the flood plain of the Mun River. Sediments of these deposits are characterized by clasts of various rock types especially the resistant ones with frequent big tree trunks, logs and wood fragments in different sizes and various stages of transformation from moldering stage to lignification and petrification. Widespread pyritization of the lower horizon suggests strongly reducing environment during burial. The Tha Chang deposits have been received much attention from geoscientists especially paleontologist communities, as they contain fragments of some distinct vertebrate species such as Stegadon sp., hominoid primate, rhinoceros Aceratherium and others. Based on the associated mammal fauna and hominoid fossils, the late Miocene ( 9 - 6 Ma) was given for the time of deposition of this sand and gravel unit. Some other reports believed that sediments and materials of these sand and gravel quarries (pits) were deposited by high-energy flood pulses contemporaneous with the tektites forming event during mid-Pleistocene at c. 0.8 Ma. Interpretation from Palynostratigraphical study suggested that the lower horizon of Tha Chang sand pit was deposited during Pliocene/Pleistocene period and the upper horizons are Pleistoncene/Holocene. It is crystal clear that all the fluviatile sediments including tektites and almost all fossil fragments being deposited in these sand pits were, likely a multiple times reworked materials. Only some old bamboo trees, some old crowling trees and fossils grasses observed on the old river bank are considered in situ. C-14 dating of 5 old wood specimens from Tha Chang Sand Pits, 15 old wood specimens from Chumpuang Sand Pits and one sample of old pottery from a Chumpuang Sand Pit were carried out in the NSF

  7. 15N and 13C{14N} NMR investigation of the major nitrogen-containing segment in an aquatic fulvic acid: evidence for a hydantoin derivative.

    Science.gov (United States)

    Fang, Xiaowen; Mao, Jingdong; Cory, Rose M; McKnight, Diane M; Schmidt-Rohr, Klaus

    2011-12-01

    A nitrogen-rich segment in a fulvic acid (FA) from Pony Lake, a coastal pond in Antarctica, was investigated by (15)N and (13)C{(14)N} solid-state NMR techniques. As reported previously, the (13)C{(14)N} spectrum of C bonded to N exhibits a peak at 157 ppm that is assigned to an sp(2)-hybridized carbon bonded to at least two nitrogen atoms. This segment contains 48% of all N in the sample. (15)N NMR shows distinct signals, 20 ppm upfield and downfield from the typical peptide resonance; dipolar dephasing confirmed that they are due to protonated N. The well-resolved downfield peak, which accounts for 1/4 of the spectral area, cannot be assigned to aromatic heterocycles, such as purines, because the fraction of aromatic C bonded to N in this sample is very small. Analysis of (15)N chemical-shift trends and (15)N NMR of model compounds, such as arginine and its derivatives, excludes assignment to a guanidinium ion or to substituted guanidino groups. Similarly, ureido groups, -NH-CO-NH-, that are not bonded to a second C = O do not match the observed (15)N peaks in the FA, since both N resonate upfield from the peptide resonance. On the other hand, all chemical shifts are matched within the observed range by the -C(alkyl)-NH-CO-NH-CO-C structure found in two nonaromatic heterocycles, hydantoin and dihydrouracil. The five-membered hydantoin ring, which is found in the purine metabolite allantoin, provides a better match than the six-membered dihydrouracil ring. Regular uracil or thymine fails to produce adequate agreement with observed chemical shifts. Copyright © 2011 John Wiley & Sons, Ltd.

  8. Test of the suitability of ECOPATH/ECOSIM modelling software as a compliment to estimate flows of carbon, C-14 and radionuclides in the Oeregrundsgrepen area

    Energy Technology Data Exchange (ETDEWEB)

    Sandberg, Johannes [Stockholm Univ. (Sweden). Dept. of Systems Ecology

    2004-04-01

    In this study it was evaluated whether the ECOPATH with ECOSIM software could be used as a standard platform to facilitate for radioecologists to construct and study transport and accumulation of radionuclides in aquatic food webs. The evaluation was based upon: 1) a previously published food web model of carbon/carbon-14 flow for the Oeregrundsgrepen area, Baltic Sea, 2) a generic model, 3) an ECOSIM model and 4) an ECOTRACE model. The results presented clearly shows that there is great potential for a successful development of this scientific approach in the future. The original carbon flows and assumptions was easily incorporated into the ECOPATH with ECOSIM modelling environment. The carbon flows differed only negligible between the two models, except for the benthic flows, which was more accurately described in this study. Further, by using ECOPATH it was easily discovered that the growth efficiencies used in the original model was quite high, being 47% for most of the heterotrophs, which are high from an ecological point of view. However, that is probably due to differences in how the carbon flows have been estimated in the original versus the present study. It is likely, however that the carbon demand has been underestimated in the original model. The generic model was parameterised from data available through the software as well from the diets and assumptions used in the original carbon model. The use of these parameters resulted in carbon flows, which was between 0.7 to 11 times the flows estimated by the ECOPATH model. The difference was greatest for primary producers being 3.7 to 11 times the original flows. Thus, depending on the question one is addressing it was suggested that the use of generic parameters is best for making test models of carbon and radionuclide flows in ecosystems, where the data set for validation is limited. Finally, the ECOPATH and ECOSIM model was well suited to drive a C-14 flow model, such as ECOTRACER for each of the

  9. There is no mass spectrometry evidence that the C14 sample from the Shroud of Turin comes from a “medieval invisible mending”

    Energy Technology Data Exchange (ETDEWEB)

    Bella, Marco, E-mail: Marco.Bella@uniroma1.it [Department of Chemistry, Sapienza University of Roma, P.le Aldo Moro 5, 00185 Roma (Italy); Garlaschelli, Luigi [Department of Chemistry, University of Pavia, Via Taramelli 10, 27100 Pavia (Italy); Samperi, Roberto [Department of Chemistry, Sapienza University of Roma, P.le Aldo Moro 5, 00185 Roma (Italy)

    2015-10-10

    Highlights: • This editorial regards a paper published on Thermochimica Acta, 425 (2005) 189. • The author hypothesized a “medieval invisible mending” on the Shroud of Turin. • There is no evidence of such a “medieval invisible mending”. • The two mass spectra presented differ only by the presence of a contaminant. • When the peaks due to the contaminant are removed, the two mass spectra look alike. - Abstract: This is an editorial regarding a paper published on Thermochimica Acta (R.N. Rogers, Thermochimca Acta, 425 (2005) 189–194). A close-up analysis of the pyrolysis-mass spectra reported in the original paper reveals that the differences found between the samples coming from different parts of the Shroud are just due to the presence of a contaminant with a long aliphatic chain. Except for the presence of the contaminant, the two pyrolysis-mass spectra look alike rather than different. Therefore, the pseudoscientific theory stating that the C14 sample might come from a “medieval invisible mending” remains unsupported by evidences.

  10. Prevalence of Helicobacter Pylori Infection in School and Pre-School Aged Children with C-14 Urea Breath Test and the Association with Familial and Environmental Factors

    Directory of Open Access Journals (Sweden)

    Alev Çınar

    2015-06-01

    Full Text Available Objective: To investigate the prevalence of Helicobacter pylori (Hp infection in pre-school and school age children with C-14 urea breath test, and to explore its association with age and socioeconomic factors in Turkey. Methods: Hp infection status was determined by using Urea Breath Test (UBT. Patients who had previous gastric surgery, Hp eradication treatment or equivocal UBT results were excluded. A questionnaire was administered to elicit information on gender, age, ABO/Rh blood group type, presence of gastric disease in the family, domestic animal in the household, and treatment for idiopathic Iron Deficiency Anemia (IDA. Results: This retrospective study included 500 pediatric patients (179 boys, 321 girls, mean age 10.7±4.3 years of whom 62 (12.4% were aged ≤6 years and 438 (87.6% were aged 7 to 16 years. Helicobacter pylori (Hp was positive in 245 (49% cases. In the pre-school age group, 21/62 cases (34% had positive UBT while in the school age group 224/438 children (51% had positive UBT. A family history of dyspepsia and pet ownership were not associated with Hp positivity. Hp positive 76 (29.8% children were on IDA treatment but this was not statistically significant. Conclusion: The Hp infection positivity rate was 49% in the pediatric age study group. The positivity rate was significantly lower at preschool age than school age, and it increased with age. There was no association with gender, ABO/Rh blood groups, presence of domestic pets, IDA, or history of gastric disease in the family.

  11. Magnetic-field-induced orientational phase structure transition.

    Science.gov (United States)

    Dou, Yingying; Dong, Shuli; Hao, Jingcheng

    2014-02-11

    Magnetic field effect on the phase transition at high temperature (from 50 °C) inside the magnetic field has been found in C14G2 (N-tetradecyllactobionamide)/C12EO4 (tetraethylene glycol monododecyl ether)/D2O system. The phase was transited quickly from lamellar phase to isotropic phases [bottom, micellar phase (L1 phase) and top, sponge phase (L3 phase)] induced by a magnetic field, which was demonstrated by (2)H NMR and FF-TEM measurements. The isotropic phases induced by magnetic field were not stable, and the upper L3 phase can recover to lamellar phase after being restored in a 55 °C thermostat outside the magnetic field for about one month. During the mechanism study, the C12EO4 molecule was proved to be the dominant component for the phase transition induced by the magnetic field, while the C14G2 molecule was the auxiliary and just affected the transition speed. The breaking and rebuilding of hydrogen bonds could play an important role in the phase transition and recovering. Moreover, the surfactant concentration had an effect on the speed of phase transiting and phase recovering. These observations could provide an understanding of the phase transition and also the applications for the controlled drug delivery system of bilayer membranes driving, induced by the magnetic field.

  12. Intercomparison of Pb-210, Cs-137, Pu-239,240 and C-14-Based Chronologies of Recent Sediments - Problems and Challenges

    Science.gov (United States)

    Baskaran, M. M.

    2016-12-01

    Short-lived naturally-occurring Pb-210 and anthropogenically-delivered Cs-137 are the two most extensively utilized chronometers over the time scale of less than a decade to 60 (Cs-137) to 120 yrs (Pb-210) in a variety of environment including terrestrial and aqueous systems and glaciers. Despite all the advances in the field, still major issues, we confront several issues on the robustness of their applications in these environments. Those include: i) how does the temporal and spatial variations of Pb-210 input to an aqueous environment affect the Pb-210 chronology? ii) how well we are able to quantify the multiple source inputs (atmospheric fallout, watershed erosional input, production of Pb-210 from the decay of SGD-derived Rn-222 and Ra-226, etc); iii) How well are we able to sort out a number of processes that affect the vertical profiles of both Cs-137 and Pb-210 which include sediment mixing (biological and/or physical), sediment focusing/erosion due to bottom currents and transport of sediments in subsurface environment and post-depositional mobility of Cs-137 and Pb-210. In this presentation, the following case studies will be discussed: 1) where there is excellent as well non-agreement between Pb-210 and Cs-137-based chronologies; 2) agreement between Cs-137-based chronology with historical time-marker from Hg mining, while no chronology obtainable from Pb-210; 3) agreement between five different methods of dating in a reservoir; 4) evidence of Cs-137 diffusion in some of the sediment cores, but not in all cores in a small reservoir; and 5) evidence of long-term remineralization based on a comparison of C-14-based ages with those of Pb-210, Cs-137 and Pu-239,240-based methods. We also show evidence Cs-137 diffusion based on a set of laboratory-based diffusion experiments under different pore water chemical conditions. A brief discussion on time resolution and error estimation on ages will be discussed. The challenges in the field of `Anthropocene

  13. Phase transformations in a manganese-alloyed austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Jargelius-Pettersson, R.F.A. (Swedish Inst. for Metals Research, Stockholm (Sweden))

    1994-05-01

    The increasing demands placed on the corrosion resistance of stainless steels has led to the successive development of more highly alloyed materials. In this context nitrogen has shown considerable value as an alloying element but its use is restricted by a solubility limit of approximately 0.2 wt% in conventional austenitic stainless steel grades. Manganese increases the nitrogen solubility appreciably and for this reason there has also been an increased interest in its use as an alloying addition but numerous questions remain to be answered about the effect of both nitrogen and manganese on structural stability. Although much work has been published on the precipitation of secondary phases in CrNi(Mo) stainless steels, there is a relative paucity of information available on manganese-alloyed steels. Brandis et al. investigated precipitation in a 25Cr 17Ni 3Mo 6Mn 0.2Nb steel and found no manganese-enriched phases to occur. Sigma phase was the predominant intermetallic precipitate at low nitrogen contents while higher nitrogen contents retarded the onset of sigma phase precipitation but caused the appearance of chi phase. Boothby et al. investigated a 12Cr 11-35Ni (3Mo) steel in which the nickel was partially replaced by 20 or 30% manganese and found the precipitation of the intermetallic sigma, chi and Laves phases to be promoted by manganese, although again no manganese-enriched phases were observed. Fritscher demonstrated however the existence in the Fe-Cr-Ni system of a brittle ternary Y phase containing 30--60% manganese which was destabilized by nitrogen. The present work represents part of a study designed to gain greater understanding of the precipitation and sensitization behavior of highly alloyed austenitic stainless steels and concentrates on the influence of nitrogen additions up to 0.5wt% on precipitation of secondary phases in a 20Cr 18Ni 4.5Mo 10Mn steel.

  14. Dirac metal to topological metal transition at a structural phase change in Au2Pb and prediction of Z2 topology for the superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Schoop, Leslie M.; Xie, Lilia S.; Chen, Ru; Gibson, Quinn D.; Lapidus, Saul H.; Kimchi, Itamar; Hirschberger, Max; Haldolaarachchige, Neel; Ali, Mazhar N.; Belvin, Carina A.; Liang, Tian; Neaton, Jeffrey B.; Ong, N P; Vishwanath, Ashvin; Cava, R. J.

    2015-06-23

    Three-dimensionalDirac semimetals (DSMs) arematerials that have masslessDirac electrons and exhibit exotic physical properties. It has been suggested that structurally distorting a DSM can create a topological insulator but this has not yet been experimentally verified. Furthermore, Majorana fermions have been theoretically proposed to exist inmaterials that exhibit both superconductivity and topological surface states. Herewe showthat the cubic Laves phase Au2Pb has a bulk Dirac cone that is predicted to gap on cooling through a structural phase transition at 100 K. The low temperature phase can be assigned a Z(2) = -1 topological index, and this phase becomes superconducting below 1.2 K. These characteristics make Au2Pb a unique platform for studying the transition between bulk Dirac electrons and topological surface states as well as studying the interaction of superconductivity with topological surface states, combining many different properties of emergent materials-superconductivity, bulk Dirac electrons, and a topologically nontrivial Z(2) invariant.

  15. Solvothermal synthesis of discrete cages and extended networks comprising {Cr(III)3O(O2CR)3(oxime)3}2- (R = H, CH3, C(CH3)3, C14H9) building blocks

    DEFF Research Database (Denmark)

    Houton, Edel; Comar, Priyanka; Pitak, Mateusz B.

    2016-01-01

    The synthesis, structural and magnetic characterisation of a family of related Cr(iii) cages are reported. Each member comprises {Cr(iii)3O(O2CR1)3(R2-sao)3}2- (R1 = H, CH3, C(CH3)3, C14H9; R2 = Me, Ph, tBu, C10H8) triangles linked by Na+ cations, resulting in either the discrete complexes [H3O][...

  16. Inhibitory effect of juniperonic acid (Delta-5c,11c,14c,17c-20:4, omega-3) on bombesin-induced proliferation of Swiss 3T3 cells.

    Science.gov (United States)

    Morishige, Jun-ichi; Amano, Naoki; Hirano, Kaoru; Nishio, Hiroaki; Tanaka, Tamotsu; Satouchi, Kiyoshi

    2008-09-01

    Juniperonic acid (Delta-5c,11c,14c,17c-20:4, JA) is a polymethylene-interrupted (PMI) fatty acid that occurs in Biota orientalis. In this study, we found that JA has an antiproliferative activity. Swiss 3T3 cells were preloaded with fatty acids before stimulation with bombesin, a mitogenic neuropeptide, and proliferation of the cells was assessed by [(3)H]thymidine incorporation. Preloading of linoleic acid (Delta-9c,12c-18:2) significantly enhanced bombesin-induced proliferation. In contrast, preloading of eicosapentaenoic acid (Delta-5c,8c,11c,14c,17c-20:5, EPA) suppressed proliferation. Likewise, cells preloaded with JA showed a significantly curtailed response to bombesin. The antiproliferative potency of JA was equivalent to that of EPA. Sciadonic acid (Delta-5c,11c,14c-20:3), an omega-6 analogue of JA did not show antiproliferative activity, suggesting the importance of the omega-3 double bond rather than the PMI structure. The EPA-like activity of JA may be involved in the pharmaceutical activity of biota seeds, a psychoactive Chinese traditional medicine.

  17. (Nano-)mechanical properties of intermetallic phases in the Fe-Mo system at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Schroeders, Sebastian; Korte-Kerzel, Sandra [Institut fuer Metallkunde und Metallphysik, RWTH Aachen University (Germany)

    2015-07-01

    Topologically close packed (TCP) intermetallic phases which precipitate in nickel-base superalloys are suspected to cause a deterioration of the mechanical properties of the γ - γ* matrix. Although the existing intermetallics, namely Laves-, R-, sigma- and mue-phases are well understood in terms of their structure, their mechanical properties have still not been investigated in detail due to their size and pronounced brittleness. In order to investigate the plastic deformation behavior of these phases, but exclude the effect of complex phase composition in the first instance, the Fe-Mo system was chosen as a model system, where all phases are available as binary alloys. Using nanomechanical testing methods like nanoindentation and micropillar-compression, the experimental challenges of high brittleness and anisotropy encountered in conventional testing can be disregarded and plastic deformation can be achieved due to the confining pressure in nanoindentation and the reduction in specimen size in microcompression. This work aims to examine the mechanical properties such as elastic modulus, yield and flow stress of intermetallic Fe-Mo phases over a range of temperatures. To this end, tests were performed in vacuum. Based on this type of study it is envisaged to form a better understanding of the way hard TCP precipitates influence the performance of superalloys.

  18. Phase Evolution in and Creep Properties of Nb-Rich Nb-Si-Cr Eutectics

    Science.gov (United States)

    Gang, Florian; Kauffmann, Alexander; Heilmaier, Martin

    2017-10-01

    In this work, the Nb-rich ternary eutectic in the Nb-Si-Cr system has been experimentally determined to be Nb-10.9Si-28.4Cr (in at. pct). The eutectic is composed of three main phases: Nb solid solution (Nbss), β-Cr2Nb, and Nb9(Si,Cr)5. The ternary eutectic microstructure remains stable for several hundred hours at a temperature up to 1473 K (1200 °C). At 1573 K (1300 °C) and above, the silicide phase Nb9(Si,Cr)5 decomposes into α-Nb5Si3, Nbss, and β-Cr2Nb. Under creep conditions at 1473 K (1200 °C), the alloy deforms by dislocation creep while the major creep resistance is provided by the silicide matrix. If the silicide phase is fragmented and, thus, its matrix character is destroyed by prior heat treatment [e.g., at 1773 K (1500 °C) for 100 hours], creep is mainly controlled by the Laves phase β-Cr2Nb, resulting in increased minimum strain rates. Compared to state of the art Ni-based superalloys, the creep resistance of this three-phase eutectic alloy is significantly higher.

  19. Computational thermodynamics aided design of novel ferritic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chen, Tianyi [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tan, Lizhen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-06-30

    With the aid of computational thermodynamics, Ni was identified to suppress the liquidus temperature of Fe2Zr and four Fe-Cr-Ni-Zr alloys were designed to study the Ni effect on the phase stability of Fe2Zr laves_phase. These alloys were fabricated through traditional arc-metling, followed by annealing at 1000 C for 336 hours and 700 C for 1275 hours. The microstructure were examined and characterized by SEM BSE image, EDS compositional mapping and point scan, XRD and TEM analysis. The major results were summarized below: 1)For investigated alloys with 12wt% Cr, 3~6wt% Zr and 3~9 wt%Ni, the phases in equilibrium with the BCC phase are C15_Laves phase, Fe23Zr6 phase. The volume fraction of intermetallic phases increases with Ni and Zr contents. 2)Instead of (Fe,Cr)2Zr C14_Laves phase, Ni stabilizes the C15_Laves structure in Fe-Cr-Ni-Zr alloys by substituting Fe and Cr atoms with Ni atoms in the first sublattice. 3)Fe23Zr6, that is metastable in the Fe-Cr-Zr ternary, is also stabilized by Ni addition. 4)Ni7Zr2 phase was observed in samples with high Ni/Zr ratio. Extensive solubility of Fe was identified in the phase. The microstructural and composition results obtained from this study will be incorportated into the the Fe-Cr-Ni-Zr database. The current samples will be subjected to ion irradiaition to be compared with those results for Fe-Cr-Zr alloys. Additional alloys will be designed to form (Fe,Cr,Ni)2Zr nanoprecipitates for further studies.

  20. Dense superconducting phases of copper-bismuth at high pressure

    Science.gov (United States)

    Amsler, Maximilian; Wolverton, Chris

    2017-08-01

    Although copper and bismuth do not form any compounds at ambient conditions, two intermetallics, CuBi and Cu11Bi7 , were recently synthesized at high pressures. Here we report on the discovery of additional copper-bismuth phases at elevated pressures with high densities from ab initio calculations. In particular, a Cu2Bi compound is found to be thermodynamically stable at pressures above 59 GPa, crystallizing in the cubic Laves structure. In strong contrast to Cu11Bi7 and CuBi, cubic Cu2Bi does not exhibit any voids or channels. Since the bismuth lone pairs in cubic Cu2Bi are stereochemically inactive, the constituent elements can be closely packed and a high density of 10.52 g/cm3 at 0 GPa is achieved. The moderate electron-phonon coupling of λ =0.68 leads to a superconducting temperature of 2 K, which exceeds the values observed both in Cu11Bi7 and CuBi, as well as in elemental Cu and Bi.

  1. Composite hypo-hyper-d-intermetallic and interionic phases as supported interactive electrocatalysts.

    Science.gov (United States)

    Neophytides, S G; Murase, K; Zafeiratos, S; Papakonstantinou, G; Paloukis, F E; Krstajic, N V; Jaksic, M M

    2006-02-23

    Interactive, strong interbonding and highly electron conductive nonstoichiometric titanium suboxide catalytic supports, Magneli phases (Ti(n)O(2n-1), on average Ti(4)O(7)), have been used in the electrocatalysis of hydrogen (HELR) and oxygen (OELR) electrode reactions with remarkable consequences and advanced achievements. The theory of hypo-hyper-d-interelectronic bonding of transition metal ions and atoms has been employed for selective ordered grafting and shown to stay in the core of the strong metal-support interaction (SMSI) in heterogeneous catalysis and electrocatalysis, and thereby the substantial cause for the improved synergistic activity of composite (electro)catalysts. The same fundament has been the thermodynamic basis for the thermal production of symmetric intermetallic Laves type phases of nanostructured electrocatalysts, in particular the ones with higher oxophilic properties of hypo-d-elements. Remarkably advanced in electrocatalytic activity, highly monatomically dispersed deposits of Pt upon Magneli phases are shown to be unique and highly promising electrocatalysts for the cathodic oxygen reduction (ORR). Nanostructured Au upon a thin nanocrystalline film of anatase titania has been confirmed by X-ray photoelectron spectroscopy (XPS) as a typical classical paradigm of the SMSI, and at the same time affording the basis for gold with strained d-orbitals, as the reversible hydrogen electrode. Magneli phases have been shown to be the best electrocatalytic supports with unique properties both for low temperature PEM fuel cells (LT PEM FCs) with pronounced CO tolerance and water electrolysis in membrane type hydrogen generators.

  2. Morphotropic Phase Boundaries in Tb1-xDyxFe2 alloys

    Science.gov (United States)

    Bergstrom, Richard, Jr.

    Magnetostrictive alloys, materials that change in dimension under an applied magnetic field, are desired candidates for transducers. Unfortunately, common magnetostrictive metals, alloys, and oxides produce such small strains that they are not a viable option. In the early 1960's rare earths were found to possess extraordinary magnetostriction values at cryogenic temperatures. When alloyed with traditional transition metals they form a Laves phase compound of the form AB2. These Laves phase compounds have shown large magnetostriction values, up to 2500μepsilon in TbFe2. A major drawback to using these materials as transducers is their huge magnetocrystalline anisotropy constants, K1 and K2. However, it was found that TbFe2 and DyFe2 have opposing signs of K1 and K2. A pseudo-binary alloy, Tb1-xDyxFe2 (Terfenol-D) TDFx, was formed to decrease the total magnetocrystalline anisotropy. The anisotropy reached a room temperature minimum for TDF73. It is suspected that this minimum of the anisotropy is accompanied by a morphotropic phase boundary (MPB) at which the crystal structure changes from tetragonal to rhombohedral. Unraveling the nature of the temperature and composition dependence of the magnetic and crystalline properties along this MPB is the primary focus of this thesis. The structure of the TDF alloys was probed through macroscopic and microscopic techniques. The maximum in the DC magnetization at the transition temperature from tetragonal to rhombohedral broadens as the transition temperature is increased. This is attributed to decreasing anisotropy at increased temperature. Synchrotron and neutron powder diffraction are utilized to elucidate the microscopic changes in the structure and magnetism. Neutron powder diffraction results were somewhat inconclusive but were sufficient to produce magnetic moments that were invariant, within experimental error, across the transition region. Synchrotron powder diffraction was used to probe the structure at

  3. Microstructural characterization of second phases in X10CrMoVNb9-1 and 12CrMoWCuVNb steels after long steam exposure time at 550 C

    Energy Technology Data Exchange (ETDEWEB)

    Rodak, Kinga; Hernas, Adam [Silesian Univ. of Technology, Inst. of Materials Science, Katowice (Poland); Vodarek, Vlastimil [VSB-Technical Univ. of Ostrava (Czech Republic)

    2015-07-15

    Microstructural changes in high alloy (9-12% Cr) creep resistant martensitic X10CrMoVNb9-1 and 12CrMoW . CuVNb steels after 100 000 h of steam exposure at 550 C have been studied using scanning transmission electron microscopy. Precipitates were identified using electron diffraction patterns and energy dispersive X-ray spectroscopy analysis. After long time exposure, a significant coarsening of M{sub 23}C{sub 6} carbides, and intensive precipitation of the coarse Laves phase were observed. Moreover, in the 12CrMoW . CuVNb steel, a low amount of the modified Z-phase particles was detected. The microstructures of the X10Cr . MoVNb9-1 and 12CrMoWCuVNb steels after 100 000 h of exposure differ in several aspects.

  4. Phase Field

    Science.gov (United States)

    Koyama, Toshiyuki

    The term phase field has recently become known across many fields of materials science. The meaning of phase field is the spatial and temporal order parameter field defined in a continuum-diffused interface model. By using the phase field order parameters, many types of complex microstructure changes observed in materials science are described effectively. This methodology has been referred to as the phase field method, phase field simulation, phase field modeling, phase field approach, etc. In this chapter, the basic concept and theoretical background for the phase field approach is explained in Sects. 21.1 and 21.2. The overview of recent applications of the phase field method is demonstrated in Sects. 21.3 to 21.6.

  5. Microstructural evolution and creep of Fe-Al-Ta alloys

    Energy Technology Data Exchange (ETDEWEB)

    Prokopcakova, Petra; Svec, Martin [Technical University of Liberec (Czech Republic). Dept. of Material Science; Palm, Martin [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany). Structure and Nano-/Micromechanics of Materials

    2016-05-15

    The microstructural evolution in Fe-Al-Ta alloys containing 23 - 31 at.% Al and 1.5 - 2.2 at.% Ta has been studied in the temperature range 650 - 750 C by annealing for 1, 10, 100 and 1 000 h. The experiments confirm that in this temperature range the precipitation of the stable hexagonal C14 Laves phase is preceded by formation of coherent, metastable L2{sub 1} Heusler phase precipitates within the Fe-Al matrix. However, precipitates of C14 are observed after much shorter annealing times than previously assumed. Creep strength increases substantially with increasing Al content of the alloys because the solid solubility for Ta in the Fe-Al matrix increases with increasing Al content and solid-solution hardening contributes substantially to the observed high creep strength. It may therefore be that the microstructural changes during creep have no noticeable effect on creep strength.

  6. Can Early Life-Stages of the Marine Fish Sparus aurata be Useful for the Evaluation of the Toxicity of Linear Alkylbenzene Sulphonates Homologues (LAS C10-C14 and Commercial LAS?

    Directory of Open Access Journals (Sweden)

    M. Hampel

    2002-01-01

    Full Text Available Most commercial household cleaning agents and personal care products contain the anionic surfactant linear alkylbenzene sulphonates (LAS as the active compound. After their use they are discharged, theoretically after adequate wastewater treatment, into receiving waters finally reaching estuaries and coastal waters. Laboratory toxicity tests are useful tools in determining at which concentration a certain wastewater compound becomes hazardous for an existing group of organisms. Early life-stage toxicity tests include exposure during the most sensitive development period of the organism. In fish, this type of assay has shown to predict accurately maximum acceptable toxicant concentration (MATC values (comprised in the range defined by the NOEC and LOEC in fish early life-stage tests. For this reason, larvae of the seabream, Sparus aurata, were exposed to increasing concentrations of LAS homologues (C10-C14 and commercial LAS. Obtained LC50 values ranged between 0.1 and 3.0 mg l-1 and were compared with LC50 values of previous hatching experiments with the same species. Larvae proved to be more sensitive to LAS exposure of individual homologues than eggs, except in the case of commercial LAS. LC50 values can be directly employed to determine their potential risk in a concrete environment with known pollutant concentrations. Dividing the LC50 value with the found homologue concentration and extrapolating with certain security factors proposed by different environmental organisms, potentially hazardous pollutant concentrations may be detected. Average estuarine or coastal LAS concentrations are generally below toxicity limits for this kind of organism, considering that the average alkyl chain length of commercial LAS is 11.6 carbon atoms.

  7. Synthesis and structural characterization of (C 14 H 16 N 2) 3 (C 14 ...

    Indian Academy of Sciences (India)

    1 Mustapha Bencharif1. Laboratoire de Chimie des Matériaux Constantine, Université Constantine 1, 25000 Constantine, Algérie; Faculté de Technologie, Université 20 Août 1955, 21000 Skikda, Algérie ...

  8. Modelling Amazonian forest eddy covariance data: a comparison of big leaf versus sun/shade models for the C-14 tower at Manaus I. Canopy photosynthesis Modelagem de dados de covariância de fluxo turbulento na floresta amazônica: uma comparação entre os modelos "folha-grande" e "sol/sombra" para a torre C-14 em Manaus. I. Fotossíntese do dossel

    Directory of Open Access Journals (Sweden)

    Lina Mercado

    2006-03-01

    Full Text Available In this study, we concentrate on modelling gross primary productivity using two simple approaches to simulate canopy photosynthesis: "big leaf" and "sun/shade" models. Two approaches for calibration are used: scaling up of canopy photosynthetic parameters from the leaf to the canopy level and fitting canopy biochemistry to eddy covariance fluxes. Validation of the models is achieved by using eddy covariance data from the LBA site C14. Comparing the performance of both models we conclude that numerically (in terms of goodness of fit and qualitatively, (in terms of residual response to different environmental variables sun/shade does a better job. Compared to the sun/shade model, the big leaf model shows a lower goodness of fit and fails to respond to variations in the diffuse fraction, also having skewed responses to temperature and VPD. The separate treatment of sun and shade leaves in combination with the separation of the incoming light into direct beam and diffuse make sun/shade a strong modelling tool that catches more of the observed variability in canopy fluxes as measured by eddy covariance. In conclusion, the sun/shade approach is a relatively simple and effective tool for modelling photosynthetic carbon uptake that could be easily included in many terrestrial carbon models.Neste trabalho foi modelada a produtividade primária bruta através de duas técnicas simples para simular a fotossíntese no dossel: os modelos "folha-grande" e "sol/sombra". Para calibrar os modelos foram utilizados os parâmetros de fotossíntese da folha, estendidos à escala do dossel e um ajuste da bioquímica do dossel em relação à covariância de vórtices turbulentos. Os modelos foram validados com as medidas feitas através da técnica de covariância de vórtices turbulentos da estação C14 do projeto LBA. Ao comparar o desempenho de ambos os modelos, conclui-se que o modelo "sol/sombra" apresenta melhores resultados numericamente (do ponto de vista da

  9. Giver lave Ra-værdier bedre hygiejne?

    DEFF Research Database (Denmark)

    Gram, Lone; Bagge-Ravn, Dorthe; Kold, John

    2004-01-01

    Ifølge vore undersøgelser er der ingen grund til at ændre på den generelle anbefaling om, at Ra bør være mindre end 0,8 µm. Muligvis kan man dog i særlige tilfælde opnå hygiejnemæssige gevinster ved at bruge meget fine poleringer, dvs. Ra mindre end 0,8 µm.......Ifølge vore undersøgelser er der ingen grund til at ændre på den generelle anbefaling om, at Ra bør være mindre end 0,8 µm. Muligvis kan man dog i særlige tilfælde opnå hygiejnemæssige gevinster ved at bruge meget fine poleringer, dvs. Ra mindre end 0,8 µm....

  10. Venus Phasing.

    Science.gov (United States)

    Riddle, Bob

    1997-01-01

    Presents a science activity designed to introduce students to the geocentric and heliocentric models of the universe. Helps students discover why phase changes on Venus knocked Earth out of the center of the universe. (DKM)

  11. Study of the mechanical behavior of the hydride blister/rim structure in Zircaloy-4 using in-situ synchrotron X-ray diffraction

    Science.gov (United States)

    Lin, Jun-li; Han, Xiaochun; Heuser, Brent J.; Almer, Jonathan D.

    2016-04-01

    High-energy synchrotron X-ray diffraction was utilized to study the mechanical response of the f.c.c δ hydride phase, the intermetallic precipitation with hexagonal C14 lave phase and the α-Zr phase in the Zircaloy-4 materials with a hydride rim/blister structure near one surface of the material during in-situ uniaxial tension experiment at 200 °C. The f.c.c δ was the only hydride phase observed in the rim/blister structure. The conventional Rietveld refinement was applied to measure the macro-strain equivalent response of the three phases. Two regions were delineated in the applied load versus lattice strain measurement: a linear elastic strain region and region that exhibited load partitioning. Load partitioning was quantified by von Mises analysis. The three phases were observed to have similar elastic modulus at 200 °C.

  12. On the magnetic properties of pseudo-Laves phases RE{sub 1-y}Y{sub y}Ni{sub 4-x}Al{sub x}Mg with RE = La, Ce and Gd prepared by both melting and ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Couillaud, S.; Chevalier, B. [CNRS, Universite de Bordeaux, ICMCB, 87 Avenue du Docteur Albert Schweitzer, 33600 Pessac (France); Paul-Boncour, V. [ICMPE-CMTR, CNRS-UPEC, UMR 7182, 2-8 rue Henri Dunant, 94320 Thiais (France); Bobet, J.-L., E-mail: bobet@icmcb-bordeaux.cnrs.fr [CNRS, Universite de Bordeaux, ICMCB, 87 Avenue du Docteur Albert Schweitzer, 33600 Pessac (France)

    2012-06-05

    Highlights: Black-Right-Pointing-Pointer LaNi{sub 4}Mg did not exhibit any magnetic ordering but a paramagnetic behaviour. Black-Right-Pointing-Pointer All the compounds with Gd order ferromagnetically at a temperature ranging from 77 to 15 K. Black-Right-Pointing-Pointer Dilution of Gd atom by Y leads to a decrease of the Curie temperature below a critical number of Gd atoms. - Abstract: Magnetic properties of RE{sub 1-y}Y{sub y}Ni{sub 4-x}Al{sub x}Mg (RE = La, Ce and Gd) are reported. LaNi{sub 4}Mg displays a weak magnetization indicating that Ni is non magnetic as often observed in RENi{sub 2} compounds. The magnetization of CeNi{sub 4}Mg compounds shows a Curie Weiss behaviour with an effective paramagnetic moment {mu}{sub eff} = 2.2 {mu}{sub B}. The magnetization of Gd compounds is dominated by the contribution of Gd moment with a paramagnetic effective moment close to 7.7 {mu}{sub B}/Gd for all studied compounds. The Curie temperature, which is 75 K for GdNi{sub 2}, decreases almost linearly with the number of Gd neighbours when more than half Gd is replaced by Y. The decrease of crystallinity of GdNi{sub 4}Mg, which is monitored by ball milling and heat treatment, strongly influences the magnetic properties and a relationship between the transition temperature and the crystallites size is reported.

  13. Phase Vocoder

    Directory of Open Access Journals (Sweden)

    J.L. Flanagan

    2013-08-01

    Full Text Available A vocoder technique is described in which speech signals are represented by their short-time phase and amplitude spectra. A complete transmission system utilizing this approach is simulated on a digital computer. The encoding method leads to an economy in transmission bandwidth and to a means for time compression and expansion of speech signals.

  14. phase V

    International Development Research Centre (IDRC) Digital Library (Canada)

    Equinet : réappropriation des ressources aux fins de la santé - phase V. Le Réseau régional pour l'équité en santé en Afrique australe (Equinet) est constitué de professionnels, de chercheurs, de membres de la société civile et de responsables des politiques qui se sont réunis pour promouvoir l'équité en santé et la justice ...

  15. NiAl-based Polyphase in situ Composites in the NiAl-Ta-X (X = Cr, Mo, or V) Systems

    Science.gov (United States)

    Johnson, D. R.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.

    1995-01-01

    Polyphase in situ composites were generated by directional solidification of ternary eutectics. This work was performed to discover if a balance of properties could be produced by combining the NiAl-Laves phase and the NiAl-refractory metal phase eutectics. The systems investigated were the Ni-Al-Ta-X (X = Cr, Mo, or V) alloys. Ternary eutectics were found in each of these systems and the eutectic composition, temperature, and morphology were determined. The ternary eutectic systems examined were the NiAl-NiAlTa-(Mo, Ta), NiAl-(Cr, Al) NiTa-Cr, and the NiAl-NiAlTa-V systems. Each eutectic consists of NiAl, a C14 Laves phase, and a refractory metal phase. Directional solidification was performed by containerless processing techniques in a levitation zone refiner to minimize alloy contamination. Room temperature fracture toughness of these materials was determined by a four-point bend test. Preliminary creep behavior was determined by compression tests at elevated temperatures, 1100-l400 K. Of the ternary eutectics, the one in the NiAl-Ta-Cr system was found to be the most promising. The fracture toughness of the NiAl-(Cr, Al)NiTa-Cr eutectic was intermediate between the values of the NiAl-NiAlTa eutectic and the NiAl-Cr eutectic. The creep strength of this ternary eutectic was similar to or greater than that of the NiAl-Cr eutectic.

  16. Characteristics of radiation porosity and structural phase state of reactor austenitic 07C-16Cr-19Ni-2Mo-2Mn-Ti-Si-V-P-B Steel after neutron irradiation at a temperature of 440-600°C to damaging doses of 36-94 dpa

    Science.gov (United States)

    Portnykh, I. A.; Panchenko, V. L.

    2016-06-01

    The phase composition and the characteristics of vacancy voids in cold-worked steel 07C-16Cr-19Ni-2Mo-2Mn-Ti-Si-V-P-B (CW EK164-ID) after neutron irradiation at damaging doses of 36-94 dpa and temperatures of 440-600°C are investigated. In the entire range of damaging doses and temperatures, voids with different sizes are observed in the material. The maximum void size increases with irradiation temperature up to ~550°C, whereas their concentration decreases. At higher irradiation temperatures, almost no coarse voids are observed. The concentration of fine voids (to 10 nm in size) sharply increases with temperature from 440 to 480°C. Further increases in the temperature do not result in the noticeable concentration growth. In the irradiation temperature range of 440-515°C, second phases precipitate ( G phase, γ' phase, and complex fcc carbides). At higher irradiation temperatures, there are Laves-phase particles, fine second carbides of the MC type, and needle shape precipitates identified as phosphides in the material.

  17. New roles for icosahedral clusters in intermetallic phases: micelle-like segregation of Ca-Cd and Cu-Cd interactions in Ca10Cd27Cu2.

    Science.gov (United States)

    Hadler, Amelia B; Harris, Nicholas A; Fredrickson, Daniel C

    2013-11-20

    Despite significant progress in the structural characterization of the quasicrystalline state, the chemical origins of long- and short-range icosahedral order remain mysterious and a subject of debate. In this Article, we present the crystal structure of a new complex intermetallic phase, Ca10Cd27Cu2 (mC234.24), whose geometrical features offer clues to the driving forces underlying the icosahedral clusters that occur in Bergman-type quasicrystals. Ca10Cd27Cu2 adopts a C-centered monoclinic superstructure of the 1/1 Bergman approximant structure, in which [110] layers of Bergman clusters in the 1/1 structure are separated through the insertion of additional atoms (accompanied by substantial positional disorder). An examination of the coordination environments of Ca and Cu (in the ordered regions) reveals that the structure can be viewed as a combination of coordination polyhedra present in the nearest binary phases in the Ca-Cd-Cu compositional space. A notable feature is the separation of Ca-Cd and Cu-Cd interactions, with Bergman clusters emerging as Ca-Cd Friauf polyhedra (derived from the MgZn2-type CaCd2 phase) encapsulate a Cu-Cd icosahedron similar to those appearing in Cu2Cd5. DFT chemical pressure calculations on nearby binary phases point to the importance of this segregation of Ca-Cd and Cu-Cd interactions. The mismatch in atomic size between Cu and Cd leads to an inability to satisfy Ca-Cu and Ca-Cd interactions simultaneously in the Friauf polyhedra of the nearby Laves phase CaCd2. The relegation of the Cu atoms to icosahedra prevents this frustration while nucleating the formation of Bergman clusters.

  18. Investigation Of Temperature Dependent Characteristics Of ...

    African Journals Online (AJOL)

    The structure, magnetization and magnetostriction of Laves phase compound TbCo2 were investigated by temperature dependent high resolution neutron powder diffraction. The compound crystallizes in the cubic Laves phase C15 structure above its Curie temperature, TC and exhibits a rhombohedral distortion (space ...

  19. Phase contrast image synthesis

    DEFF Research Database (Denmark)

    Glückstad, J.

    1996-01-01

    A new method is presented for synthesizing arbitrary intensity patterns based on phase contrast imaging. The concept is grounded on an extension of the Zernike phase contrast method into the domain of full range [0; 2 pi] phase modulation. By controlling the average value of the input phase...... function and by choosing appropriate phase retardation at the phase contrast filter, a pure phase to intensity imaging is accomplished. The method presented is also directly applicable in dark field image synthesis....

  20. Thermal processing of diblock copolymer melts mimics metallurgy

    Science.gov (United States)

    Kim, Kyungtae; Schulze, Morgan W.; Arora, Akash; Lewis, Ronald M.; Hillmyer, Marc A.; Dorfman, Kevin D.; Bates, Frank S.

    2017-05-01

    Small-angle x-ray scattering experiments conducted with compositionally asymmetric low molar mass poly(isoprene)-b-poly(lactide) diblock copolymers reveal an extraordinary thermal history dependence. The development of distinct periodic crystalline or aperiodic quasicrystalline states depends on how specimens are cooled from the disordered state to temperatures below the order-disorder transition temperature. Whereas direct cooling leads to the formation of documented morphologies, rapidly quenched samples that are then heated from low temperature form the hexagonal C14 and cubic C15 Laves phases commonly found in metal alloys. Self-consistent mean-field theory calculations show that these, and other associated Frank-Kasper phases, have nearly degenerate free energies, suggesting that processing history drives the material into long-lived metastable states defined by self-assembled particles with discrete populations of volumes and polyhedral shapes.

  1. Phased arrays '85

    Science.gov (United States)

    Stiglitz, M. R.

    1985-11-01

    The conference Phased Arrays '85 was held in Bedford, MA, on October 15-18, 1985. It is pointed out that the 15 years between the 1970 and 1985 conferences dedicated to phased array antennas have seen many technological advances. Attention is given to the principle of operation, monolithic phased arrays, active arrays of monopole elements, scan compensated active element patterns, microstrip arrays, time delay technologies for phased array systems, ferrite materials for mm-wave phase shifters, phase-only optimization of phased array excitation by B-quadratic programming, a nearly frequency-independent sidelobe suppression technique for phased arrays, and active impedance effects in low sidelobe and ultrawideband phased arrays.

  2. Metastable phases and 'metastable' phase diagrams

    Science.gov (United States)

    Brazhkin, V. V.

    2006-10-01

    The work discusses the qualitative nature of phase transitions for metastable states of substances. The objects of the physics of condensed media are primarily the equilibrium states of substances with metastable phases viewed as an exception, while in chemistry the overwhelming majority of organic substances under investigation are metastable. It turns out that at normal pressure many simple molecular compounds based on light elements (these include: most hydrocarbons; nitrogen oxides, hydrates, and carbides; carbon oxide (CO); alcohols, glycerin) are metastable substances too, i.e. they do not match the Gibbs free energy minimum for a given atomic chemical composition. At moderate temperatures and pressures, the phase transitions for particular metastable phases are reversible throughout the entire experimentally accessible time period with the equilibrium thermodynamics laws obeyed. At sufficiently high pressures (1-10 GPa), most molecular phases irreversibly transform to more energy efficient polymerized phases. These transformations are not consistent with the equality of the Gibbs free energies between the phases before and after transition, i.e. they are not phase transitions in the 'classical' meaning. The resulting polymeric phases at normal pressure can exist at temperatures above the melting one for an initial metastable molecular phase. Striking examples of such polymers are polyethylene and a polymerized modification of CO. Many energy-intermediate polymeric phases can apparently be synthesized by the 'classical' chemistry techniques at normal pressure. At higher pressures (10-100 GPa) polymerized modifications transform to a mixture of simple stable phases.

  3. Phase equilibrium engineering

    CERN Document Server

    Brignole, Esteban Alberto

    2013-01-01

    Traditionally, the teaching of phase equilibria emphasizes the relationships between the thermodynamic variables of each phase in equilibrium rather than its engineering applications. This book changes the focus from the use of thermodynamics relationships to compute phase equilibria to the design and control of the phase conditions that a process needs. Phase Equilibrium Engineering presents a systematic study and application of phase equilibrium tools to the development of chemical processes. The thermodynamic modeling of mixtures for process development, synthesis, simulation, design and

  4. THE NEW GRONINGEN C-14 DATA-BASE

    NARCIS (Netherlands)

    VANDERPLICHT, J

    1992-01-01

    The Groningen Radiocarbon Data base has been operating on an Apple IIe PC until recently. Both software and hardware of this data base made exchange with other systems very difficult. Therefore, the data base has been transferred to an IBM AT compatible computer. A new program has been written in

  5. C-14 cycle in the hot zone around Chernobyl

    NARCIS (Netherlands)

    Kovaliukh, Nikolai N.; Skripkin, Vadim V.; Plicht, Johannes van der; Mook, W.G.; Plicht, J. van der; 074059653

    1998-01-01

    Radiocarbon from the Chernobyl accident was released mainly in two forms: fine dispersed reactor graphite, and carbon dioxide from burning graphite. The CO2 was partly assimilated by annual and perennial vegetation. Reactor graphite dispersed over a wide territory was taken up biochemically by

  6. CrowdPhase: crowdsourcing the phase problem

    Energy Technology Data Exchange (ETDEWEB)

    Jorda, Julien; Sawaya, Michael R. [Institute for Genomics and Proteomics, 611 Charles Young Drive East, Los Angeles, CA 90095 (United States); Yeates, Todd O., E-mail: yeates@mbi.ucla.edu [Institute for Genomics and Proteomics, 611 Charles Young Drive East, Los Angeles, CA 90095 (United States); Molecular Biology Institute, 611 Charles Young Drive East, Los Angeles, CA 90095 (United States); University of California, 611 Charles Young Drive East, Los Angeles, CA 90095 (United States)

    2014-06-01

    The idea of attacking the phase problem by crowdsourcing is introduced. Using an interactive, multi-player, web-based system, participants work simultaneously to select phase sets that correspond to better electron-density maps in order to solve low-resolution phasing problems. The human mind innately excels at some complex tasks that are difficult to solve using computers alone. For complex problems amenable to parallelization, strategies can be developed to exploit human intelligence in a collective form: such approaches are sometimes referred to as ‘crowdsourcing’. Here, a first attempt at a crowdsourced approach for low-resolution ab initio phasing in macromolecular crystallography is proposed. A collaborative online game named CrowdPhase was designed, which relies on a human-powered genetic algorithm, where players control the selection mechanism during the evolutionary process. The algorithm starts from a population of ‘individuals’, each with a random genetic makeup, in this case a map prepared from a random set of phases, and tries to cause the population to evolve towards individuals with better phases based on Darwinian survival of the fittest. Players apply their pattern-recognition capabilities to evaluate the electron-density maps generated from these sets of phases and to select the fittest individuals. A user-friendly interface, a training stage and a competitive scoring system foster a network of well trained players who can guide the genetic algorithm towards better solutions from generation to generation via gameplay. CrowdPhase was applied to two synthetic low-resolution phasing puzzles and it was shown that players could successfully obtain phase sets in the 30° phase error range and corresponding molecular envelopes showing agreement with the low-resolution models. The successful preliminary studies suggest that with further development the crowdsourcing approach could fill a gap in current crystallographic methods by making it

  7. Phased array observations with infield phasing

    Science.gov (United States)

    Kudale, Sanjay; Chengalur, Jayaram N.

    2017-10-01

    We present results from pulsar observations using the Giant Metrewave Radio Telescope (GMRT) as a phased array with infield phasing. The antennas were kept in phase throughout the observation by applying antenna based phase corrections derived from visibilities that were obtained in parallel with the phased array beam data, and which were flagged and calibrated in real time using a model for the continuum emission in the target field. We find that, as expected, the signal to noise ratio (SNR) does not degrade with time. In contrast observations in which the phasing is done only at the start of the observation show a clear degradation of the SNR with time. We find that this degradation is well fit by a function of the form SNR(τ ) = α + β e^{-(τ /τ 0)^{5/3}}, which corresponds to the case where the phase drifts are caused by Kolmogorov type turbulence in the ionosphere. We also present general formulae (i.e. including the effects of correlated sky noise, imperfect phasing and self noise) for the SNR and synthesized beam size for phased arrays (as well as corresponding formulae for incoherent arrays). These would be useful in planning observations with large array telescopes.

  8. Phase Field Approach

    Science.gov (United States)

    Koyama, Toshiyuki

    The term phase field has recently become known across many fields of materials science. The meaning of phase field is the spatial and temporal order parameter field defined in a continuum-diffused interface model. By using the phase field order parameters, many types of complex microstructure changes observed in materials science are described effectively. This methodology has been referred to as the phase field method, phase field simulation, phase field modeling, phase field approach, etc. In this chapter, the basic concept and theoretical background for the phase field approach is explained in Sects. 21.1 and 21.2. The overview of recent applications of the phase field method is demonstrated in Sects. 21.3 to 21.6.

  9. High temperature phase equilibria and phase diagrams

    CERN Document Server

    Kuo, Chu-Kun; Yan, Dong-Sheng

    2013-01-01

    High temperature phase equilibria studies play an increasingly important role in materials science and engineering. It is especially significant in the research into the properties of the material and the ways in which they can be improved. This is achieved by observing equilibrium and by examining the phase relationships at high temperature. The study of high temperature phase diagrams of nonmetallic systems began in the early 1900s when silica and mineral systems containing silica were focussed upon. Since then technical ceramics emerged and more emphasis has been placed on high temperature

  10. Therapy Provider Phase Information

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Therapy Provider Phase Information dataset is a tool for providers to search by their National Provider Identifier (NPI) number to determine their phase for...

  11. Digital quadrature phase detection

    Science.gov (United States)

    Smith, J.A.; Johnson, J.A.

    1992-05-26

    A system for detecting the phase of a frequency or phase modulated signal that includes digital quadrature sampling of the frequency or phase modulated signal at two times that are one quarter of a cycle of a reference signal apart, determination of the arctangent of the ratio of a first sampling of the frequency or phase modulated signal to the second sampling of the frequency or phase modulated signal, and a determination of quadrant in which the phase determination is increased by 2[pi] when the quadrant changes from the first quadrant to the fourth quadrant and decreased by 2[pi] when the quadrant changes from the fourth quadrant to the first quadrant whereby the absolute phase of the frequency or phase modulated signal can be determined using an arbitrary reference convention. 6 figs.

  12. Gas phase ion chemistry

    CERN Document Server

    Bowers, Michael T

    1979-01-01

    Gas Phase Ion Chemistry, Volume 2 covers the advances in gas phase ion chemistry. The book discusses the stabilities of positive ions from equilibrium gas-phase basicity measurements; the experimental methods used to determine molecular electron affinities, specifically photoelectron spectroscopy, photodetachment spectroscopy, charge transfer, and collisional ionization; and the gas-phase acidity scale. The text also describes the basis of the technique of chemical ionization mass spectrometry; the energetics and mechanisms of unimolecular reactions of positive ions; and the photodissociation

  13. Computation of Phase Equilibrium and Phase Envelopes

    DEFF Research Database (Denmark)

    Ritschel, Tobias Kasper Skovborg; Jørgensen, John Bagterp

    and 2) nonideal gases and liquids modeled with cubic equations of state. Next, we derive the equilibrium conditions for an isothermal-isobaric (constant temperature, constant pressure) vapor-liquid equilibrium process (PT flash), and we present a method for the computation of phase envelopes. We......In this technical report, we describe the computation of phase equilibrium and phase envelopes based on expressions for the fugacity coefficients. We derive those expressions from the residual Gibbs energy. We consider 1) ideal gases and liquids modeled with correlations from the DIPPR database...... formulate the involved equations in terms of the fugacity coefficients. We present expressions for the first-order derivatives. Such derivatives are necessary in computationally efficient gradient-based methods for solving the vapor-liquid equilibrium equations and for computing phase envelopes. Finally, we...

  14. Cubatic phase for tetrapods

    NARCIS (Netherlands)

    Blaak, R.; Mulder, B.M.; Frenkel, D.

    2004-01-01

    We investigate the phase behavior of tetrapods, hard nonconvex bodies formed by four rods connected under tetrahedral angles. We predict that, depending on the relative lengths of the rods these particles can form a uniaxial nematic phase, and more surprisingly they can exhibit a cubatic phase, a

  15. Differential Phase Detector for Precise Phase Alignment

    CERN Document Server

    Olexa, Jakub

    2016-01-01

    This paper presents a differential phase detector circuit, whose phase-to-voltage characteristic has an extremum when its two input signals are exactly in phase. In this condition all its digital signals are of 50 % duty cycle so that the circuit characteristic does not have a dead zone. This feature allows a precise indication of the zero-phase condition, which is independent of the detector power supply and the offset of its ADC readout. Such a detector is used for a phase alignment of two reference clock signals with frequency about 11 kHz in front-ends processing signals from beam position monitors of the Large Hadron Collider (LHC) at CERN. The detector output voltage is digitized with a 24-bit ADC at the rate of the reference signals. The resulting samples are processed in the front-end FPGA and transmitted to the control system using an Ethernet data stream. After a detailed description of the differential phase detector its performance is demonstrated with laboratory measurements. The results show tha...

  16. Geometric phases in physics

    CERN Document Server

    Shapere, Alfred D

    1989-01-01

    During the last few years, considerable interest has been focused on the phase that waves accumulate when the equations governing the waves vary slowly. The recent flurry of activity was set off by a paper by Michael Berry, where it was found that the adiabatic evolution of energy eigenfunctions in quantum mechanics contains a phase of geometric origin (now known as 'Berry's phase') in addition to the usual dynamical phase derived from Schrödinger's equation. This observation, though basically elementary, seems to be quite profound. Phases with similar mathematical origins have been identified

  17. Solution phase combinatorial chemistry.

    Science.gov (United States)

    Merritt, A T

    1998-06-01

    Combinatorial chemistry and parallel array synthesis techniques are now used extensively in the drug discovery process. Although published literature has been dominated by solid phase chemistry approaches, the use of solution phase techniques has also been widely explored. This review considers the advantages and disadvantages of choosing solution phase approaches in the various stages of drug discovery and optimisation, and assesses the practical issues related to these approaches. The uses of standard solution chemistry, the related liquid phase approach, and of supported materials to enhance solution phase chemistry are all illustrated by a comprehensive review of the published literature over the past three years.

  18. Single-Phase PLLs

    DEFF Research Database (Denmark)

    Golestan, Saeed; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2017-01-01

    Single-phase phase-locked loops (PLLs) are popular for the synchronization and control of single-phase gridconnected converters. They are also widely used for monitoring and diagnostic purposes in the power and energy areas. In recent years, a large number of single-phase PLLs with different stru......-PLLs). The members of each category are then described and their pros and cons are discussed. This work provides a deep insight into characteristics of different single-phase PLLs and, therefore, can be considered as a reference for researchers and engineers....

  19. Generalized phase contrast:

    DEFF Research Database (Denmark)

    Glückstad, Jesper; Palima, Darwin

    Generalized Phase Contrast elevates the phase contrast technique not only to improve phase imaging but also to cross over and interface with diverse and seemingly disparate fields of contemporary optics and photonics. This book presents a comprehensive introduction to the Generalized Phase Contrast...... (GPC) method including an overview of the range of current and potential applications of GPC in wavefront sensing and phase imaging, structured laser illumination and image projection, optical trapping and manipulation, and optical encryption and decryption. The GPC method goes further than...... the restrictive assumptions of conventional Zernike phase contrast analysis and achieves an expanded range of validity beyond weak phase perturbations. The generalized analysis yields design criteria for tuning experimental parameters to achieve optimal performance in terms of accuracy, fidelity and light...

  20. Generalized Phase Contrast

    CERN Document Server

    Glückstad, Jesper

    2009-01-01

    Generalized Phase Contrast elevates the phase contrast technique not only to improve phase imaging but also to cross over and interface with diverse and seemingly disparate fields of contemporary optics and photonics. This book presents a comprehensive introduction to the Generalized Phase Contrast (GPC) method including an overview of the range of current and potential applications of GPC in wavefront sensing and phase imaging, structured laser illumination and image projection, optical trapping and manipulation, and optical encryption and decryption. The GPC method goes further than the restrictive assumptions of conventional Zernike phase contrast analysis and achieves an expanded range of validity beyond weak phase perturbations. The generalized analysis yields design criteria for tuning experimental parameters to achieve optimal performance in terms of accuracy, fidelity and light efficiency. Optimization can address practical issues, such as finding an optimal spatial filter for the chosen application, ...

  1. Quantum phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Sachdev, S. [Yale University, New Haven, CT (United States)

    1999-04-01

    Phase transitions are normally associated with changes of temperature but a new type of transition - caused by quantum fluctuations near absolute zero - is possible, and can tell us more about the properties of a wide range of systems in condensed-matter physics. Nature abounds with phase transitions. The boiling and freezing of water are everyday examples of phase transitions, as are more exotic processes such as superconductivity and superfluidity. The universe itself is thought to have passed through several phase transitions as the high-temperature plasma formed by the big bang cooled to form the world as we know it today. Phase transitions are traditionally classified as first or second order. In first-order transitions the two phases co-exist at the transition temperature - e.g. ice and water at 0 deg., or water and steam at 100 deg. In second-order transitions the two phases do not co-exist. In the last decade, attention has focused on phase transitions that are qualitatively different from the examples noted above: these are quantum phase transitions and they occur only at the absolute zero of temperature. The transition takes place atthe ''quantum critical'' value of some other parameter such as pressure, composition or magnetic field strength. A quantum phase transition takes place when co-operative ordering of the system disappears, but this loss of order is driven solely by the quantum fluctuations demanded by Heisenberg's uncertainty principle. The physical properties of these quantum fluctuations are quite distinct from those of the thermal fluctuations responsible for traditional, finite-temperature phase transitions. In particular, the quantum system is described by a complex-valued wavefunction, and the dynamics of its phase near the quantum critical point requires novel theories that have no analogue in the traditional framework of phase transitions. In this article the author describes the history of quantum phase

  2. Phosphatidylcholine: cholesterol phase diagrams.

    Science.gov (United States)

    Thewalt, J L; Bloom, M

    1992-10-01

    Two mono-cis-unsaturated phosphatidylcholine (PC) lipid molecules, having very different gel-liquid crystalline phase transition temperatures as a consequence of the relative positions of the double bond, exhibit PC:cholesterol phase diagrams that are very similar to each other and to that obtained previously for a fully saturated PC:cholesterol mixture (Vist, M. R., and J. H. Davis. 1990. Biochemistry 29:451-464). This leads to the conjecture that PC:cholesterol membrane phase diagrams have a universal form which is relatively independent of the precise chemical structure of the PC molecule. One feature of this phase diagram is the observation over a wide temperature range of a fluid but highly conformationally ordered phase at bilayer concentrations of more than approximately 25 mol% cholesterol. This ;liquid ordered' phase is postulated to be the relevant physical state for many biological membranes, such as the plasma membrane of eukaryotic cells, that contain substantial amounts of cholesterol or equivalent sterols.

  3. Gymnastics in Phase Space

    Energy Technology Data Exchange (ETDEWEB)

    Chao, Alexander Wu; /SLAC

    2012-03-01

    As accelerator technology advances, the requirements on accelerator beam quality become increasingly demanding. Facing these new demands, the topic of phase space gymnastics is becoming a new focus of accelerator physics R&D. In a phase space gymnastics, the beam's phase space distribution is manipulated and precision tailored to meet the required beam qualities. On the other hand, all realization of such gymnastics will have to obey accelerator physics principles as well as technological limitations. Recent examples of phase space gymnastics include Emittance exchanges, Phase space exchanges, Emittance partitioning, Seeded FELs and Microbunched beams. The emittance related topics of this list are reviewed in this report. The accelerator physics basis, the optics design principles that provide these phase space manipulations, and the possible applications of these gymnastics, are discussed. This fascinating new field promises to be a powerful tool of the future.

  4. Cosmological phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Kolb, E.W. [Fermi National Accelerator Lab., Batavia, IL (United States)]|[Chicago Univ., IL (United States)

    1993-10-01

    If modern ideas about the role of spontaneous symmetry breaking in fundamental physics are correct, then the Universe should have undergone a series of phase transitions early in its history. The study of cosmological phase transitions has become an important aspect of early-Universe cosmology. In this lecture I review some very recent work on three aspects of phase transitions: the electroweak transition, texture, and axions.

  5. Phase Holograms In PMMA

    Science.gov (United States)

    Maker, Paul D.; Muller, Richard E.

    1994-01-01

    Complex, computer-generated phase holograms written in thin films of poly(methyl methacrylate) (PMMA) by process of electron-beam exposure followed by chemical development. Spatial variations of phase delay in holograms quasi-continuous, as distinquished from stepwise as in binary phase holograms made by integrated-circuit fabrication. Holograms more precise than binary holograms. Greater continuity and precision results in decreased scattering loss and increased imaging efficiency.

  6. Thermodynamically Stable Blue Phases

    Science.gov (United States)

    Castles, F.; Morris, S. M.; Terentjev, E. M.; Coles, H. J.

    2010-04-01

    We show theoretically that flexoelectricity stabilizes blue phases in chiral liquid crystals. Induced internal polarization reduces the elastic energy cost of splay and bend deformations surrounding singular lines in the director field. The energy of regions of double twist is unchanged. This in turn reduces the free energy of the blue phase with respect to that of the chiral nematic phase, leading to stability over a wider temperature range. The theory explains the discovery of large temperature range blue phases in highly flexoelectric “bimesogenic” and “bent-core” materials, and predicts how this range may be increased further.

  7. Modeling of liquid phases

    CERN Document Server

    Soustelle, Michel

    2015-01-01

    This book is part of a set of books which offers advanced students successive characterization tool phases, the study of all types of phase (liquid, gas and solid, pure or multi-component), process engineering, chemical and electrochemical equilibria, and the properties of surfaces and phases of small sizes. Macroscopic and microscopic models are in turn covered with a constant correlation between the two scales. Particular attention has been given to the rigor of mathematical developments. This second volume in the set is devoted to the study of liquid phases.

  8. Solid phase transformations II

    CERN Document Server

    Čermák, J

    2009-01-01

    This topical volume includes ten invited papers that cover selected areas of the field of solid phase transformations. The first two contributions represent a burgeoning branch; that of the computer simulation of physical phenomena. The following three articles deal with the thermodynamics of phase transformations as a basic theory for describing the phenomenology of phase changes in matter. The next paper describes the interconnections between structural stability and the electronic structure of phases. Two further articles are devoted to displacive transformations; a field where there are ma

  9. Dual phase evolution

    CERN Document Server

    Green, David G; Abbass, Hussein A

    2014-01-01

    This book explains how dual phase evolution operates in all these settings and provides a detailed treatment of the subject. The authors discuss the theoretical foundations for the theory, how it relates to other phase transition phenomena and its advantages in evolutionary computation and complex adaptive systems. The book provides methods and techniques to use this concept for problem solving. Dual phase evolution concerns systems that evolve via repeated phase shifts in the connectivity of their elements. It occurs in vast range of settings, including natural systems (species evolution, landscape ecology, geomorphology), socio-economic systems (social networks) and in artificial systems (annealing, evolutionary computing).

  10. Instantaneous phase shifting deflectometry.

    Science.gov (United States)

    Trumper, Isaac; Choi, Heejoo; Kim, Dae Wook

    2016-11-28

    An instantaneous phase shifting deflectometry measurement method is presented and implemented by measuring a time varying deformable mirror with an iPhone ® 6. The instantaneous method is based on multiplexing phase shifted fringe patterns with color, and decomposing them in x and y using Fourier techniques. Along with experimental data showing the capabilities of the instantaneous deflectometry system, a quantitative comparison with the Fourier transform profilometry method, which is a distinct phase measuring method from the phase shifting approach, is presented. Sources of error, nonlinear color-multiplexing induced error correction, and hardware limitations are discussed.

  11. Phase space and phase space transformations

    Energy Technology Data Exchange (ETDEWEB)

    Alefeld, B.

    1985-03-01

    For neutron scattering instrumentation Liouville's theorem plays a similar role as the second law of thermodynamics at least in the sense that from time to time 'ingenious' devices are discussed seriously, which are meant to increase the phase space density, these devices are analogous to a perpetuum mobile of the second kind.

  12. Syntheses and structures of the MOF-type series of metal 1,4,5,8,-naphthalenetetracarboxylates M 2(OH) 2[C 14O 8H 4] (Al, Ga, In) with infinite trans-connected M-OH-M chains (MIL-122)

    Science.gov (United States)

    Volkringer, Christophe; Loiseau, Thierry; Guillou, Nathalie; Férey, Gérard; Elkaïm, Erik

    2009-08-01

    Three new isostructural MOF-type compounds (named MIL-122) have been obtained from the hydrothermal reaction at 210 °C for 24 h of the 1,4,5,8-naphthalenetetracarboxylic acid with aluminum, gallium or indium source in water. The structures of the compounds M 2(OH) 2[C 14H 4O 8] (M = Al, Ga, In) have been solved ab initio from powder X-ray diffraction analysis using the synchrotron radiation (Soleil; station CRISTAL). The three-dimensional organic-inorganic framework exhibits infinite straight chains of metal-centered octahedra sharing trans corners linked to each other through the 1,4,5,8-naphthalenetetracarboxylate ligand. The cations Al, Ga or In, are coordinated by four oxygen atoms coming from the carboxyl groups and two bridging hydroxyl groups μ2-OH, located in trans position in the octahedral surrounding. The compounds characterized by thermogravimetric and thermodiffraction analyses are thermally stable up to 440, 460 and 380 °C, for Al, Ga and In, respectively. Crystal data: monoclinic cell; P2 1/ c (n°14); for MIL-122 (Al): a = 9.5174(2), b = 10.0706(1), c = 6.6465(2) Å, β = 91.2614(5)°, V = 636.878(2) Å 3, Z = 2; for MIL-122 (Ga): a = 9.6501(1), b = 10.0585(1), c = 6.75069(9) Å, β = 92.4786(9)°, V = 654.65(1) Å 3, Z = 2; for MIL-122 (In): a = 9.92359(5), b = 10.19765(7), c = 7.19357(4) Å, β = 727.034(8)°, V = 727.034(8)Å 3, Z = 2.

  13. Entropy Variation in the Two-dimensional Phase Transition of Anthracene Adsorbed at the Hg Electrode/Ethylene Glycol Solution Interface

    Directory of Open Access Journals (Sweden)

    Claudio Fontanesi

    2010-03-01

    Full Text Available The adsorption of anthracene (C14H10, at the mercury electrode/ethylene glycol (EG solution interface, is characterized by a low and almost constant capacity (about 8 μF cm−2 region (capacitive “pit” or “plateau” in capacity vs. potential curves, upon selection of suitable values of temperature, bulk concentration and applied potential values. This result is rationalized assuming the occurrence of a 2D phase transition between two distinct adsorbed phases: (i a “disordered” phase, characterized by a flat “parallel” disposition of the aromatic moiety on the electrode surface (ii an “ordered” phase, characterized by a “perpendicular” disposition of the aromatic moiety on the electrode surface. The experimental evidence is rationalized by considering the chemical potential as an explicit function of the “electric field/adsorbed molecule” interaction. Such a modelistic approach enables the determination of the relevant standard entropy variation.

  14. Three-Phase PLLs

    DEFF Research Database (Denmark)

    Golestan, Saeed; Guerrero, Josep M.; Vasquez, Juan C.

    2017-01-01

    A phase-locked loop (PLL) is a nonlinear negativefeedback control system that synchronizes its output in frequency as well as in phase with its input. PLLs are now widely used for the synchronization of power electronics-based converters and also for monitoring and control purposes in different...

  15. the intermediate phase

    African Journals Online (AJOL)

    Research methods. The empirical investigation was divided into two phases: developmental and implementation. Method in the developmental phase. The action plan for the design of a new multiple-choice measuring instrument, proposed by Nunnally and Bernstein (1994), was considered appropriate for this study. First ...

  16. Optical phase conjugation

    CERN Document Server

    Fisher, Robert A

    1983-01-01

    This book appears at a time of intense activity in optical phase conjugation. We chose not to await the maturation of the field, but instead to provide this material in time to be useful in its development. We have tried very hard to elucidate and interrelate the various nonlinear phenomena which can be used for optical phase conjugation.

  17. UPVG phase 2 report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-08-01

    The Utility PhotoVoltaic Group (UPVG), supported by member dues and a grant from the US Department of Energy, has as its mission the acceleration of the use of cost-effective small-scale and emerging large-scale applications of photovoltaics for the benefit of electric utilities and their customers. Formed in October, 1992, with the support of the American Public Power Association, Edison Electric Institute, and the National Rural Electric Cooperative Association, the UPVG currently has 90 members from all sectors of the electric utility industry. The UPVG`s efforts as conceived were divided into four phases: Phase 0--program plan; Phase 1--organization and strategy development; Phase 2--creating market assurance; and Phase 3--higher volume purchases. The Phase 0 effort developed the program plan and was completed early in 1993. The Phase 1 goal was to develop the necessary background information and analysis to lead to a decision as to which strategies could be undertaken by utilities to promote greater understanding of PV markets and achieve increased volumes of PV purchases. This report provides the details of the UPVG`s Phase 2 efforts to initiate TEAM-UP, its multiyear, 50-MW hardware initiative.

  18. Electrochemical and metallurgical characterization of ZrCr{sub 1-x}NiMo{sub x} AB{sub 2} metal hydride alloys

    Energy Technology Data Exchange (ETDEWEB)

    Erika, Teliz [Universidad de la República, Facultad de Ciencias, Laboratorio de Electroquímica Fundamental, Núcleo Interdisciplinario Ingeniería Electroquímica, Igua 4225, CP 11400 Montevideo (Uruguay); Ricardo, Faccio [Universidad de la República, Crystallography, Solid State and Materials Laboratory (Cryssmat-Lab), DETEMA, Centro NanoMat, Polo Tecnológico de Pando, Espacio Interdisciplinario, Facultad de Química, Montevideo (Uruguay); Fabricio, Ruiz [Consejo Nacional de Investigaciones Científicas y Técnicas , CONICET, Av. Rivadavia 1917, C1033AAJ Ciudad de Buenos Aires (Argentina); Centro Atómico Bariloche , Comisión Nacional de Energía Atómica (CAB-CNEA), Av. Bustillo 9500, CP 8400 S.C. de Bariloche, RN (Argentina); Fernando, Zinola [Universidad de la República, Facultad de Ciencias, Laboratorio de Electroquímica Fundamental, Núcleo Interdisciplinario Ingeniería Electroquímica, Igua 4225, CP 11400 Montevideo (Uruguay); and others

    2015-11-15

    The effects of partial replacement of chromium by molybdenum was studied on the structure and electrochemical kinetic properties of ZrCr{sub 1-x}NiMo{sub x}(x = 0.0, 0.3 and 0.6) metal hydride alloys. The arc-melting prepared alloys were metallurgically characterized by X-ray diffraction and energy dispersive spectroscopy microanalysis, which showed AB{sub 2} (with hexagonal C14 structure) and Zr{sub x}Ni{sub y} (Zr{sub 7}Ni{sub 10}, Zr{sub 9}Ni{sub 11}) phases. After a partial substitution of chromium by molybdenum, secondary phases monotonically increase with the C14 unit cell volume indicating that most of molybdenum atoms locate in the B-site. The alloys were electrochemically characterized using charge/discharge cycling, electrochemical impedance spectroscopy and rate capability experiments that allowed the determination of hydriding reaction kinetic parameters. The presence of molybdenum produces a positive effect for hydrogen diffusion in the alloy lattice, and ZrCr{sub 0.7}NiMo{sub 0.3} alloy depicts the better kinetics associated with a fast activation, lower charge transfer resistance and the best high rate discharge behavior. This fact would be related to a lower diffusion time constant and a bigger value of the product between exchange density current and surface active area. There is a trade-off in the amounts of secondary phase and Laves phases in order to improve the kinetic performance. - Highlights: • Metallurgical characterization evidences the presence of Zr{sub x}Ni{sub y} and C14 phases. • The partial replacement of Cr by Mo promotes the segregation of Zr{sub x}Ni{sub y} phase. • The incorporation of molybdenum improves the kinetics for the hydriding process. • Mo produces a decrease in the diffusion time constant.

  19. Quantum Phase Liquids-Fermionic Superfluid without Phase Coherence

    OpenAIRE

    Wu, Ya-Jie; Zhou, Jiang; Kou, Su-Peng

    2014-01-01

    We investigate the two dimensional generalized attractive Hubbard model in a bipartite lattice, and and a "quantum phase liquid" phase, in which the fermions are paired but don't have phase coherence at zero temperature, in analogy to quantum spin liquid phase. Then, two types of topological quantum phase liquids with a small external magnetic field-Z2 quantum phase liquids and chiral quantum phase liquids-are discussed.

  20. Phase transformation and diffusion

    CERN Document Server

    Kale, G B; Dey, G K

    2008-01-01

    Given that the basic purpose of all research in materials science and technology is to tailor the properties of materials to suit specific applications, phase transformations are the natural key to the fine-tuning of the structural, mechanical and corrosion properties. A basic understanding of the kinetics and mechanisms of phase transformation is therefore of vital importance. Apart from a few cases involving crystallographic martensitic transformations, all phase transformations are mediated by diffusion. Thus, proper control and understanding of the process of diffusion during nucleation, g

  1. Martensitic phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Petry, W.; Neuhaus, J. [Techn. Universitaet Muenchen, Physik Department E13, Munich (Germany)

    1996-11-01

    Many elements transform from a high temperature bcc phase to a more dense packed temperature phase. The great majority of these transitions are of 1st order, displacive and reconstructive. The lattice potentials which govern these martensitic transitions can be probed by inelastic neutron scattering, thereby answering fundamental questions like : Will the transition be announced by dynamical or static fluctuations? What are the trajectories for the displacements needed for the transformation? Does the vibrational entropy stabilize the high temperature phase? Are the unusual transport properties in these materials related to their ability to transform? (author) 17 figs., 1 tab., 46 refs.

  2. Elasticity of phase-Pi (Al3Si2O7(OH)3) - A hydrous aluminosilicate phase

    Science.gov (United States)

    Peng, Ye; Mookherjee, Mainak; Hermann, Andreas; Bajgain, Suraj; Liu, Songlin; Wunder, Bernd

    2017-08-01

    Phase-Pi (Al3Si2O7(OH)3) is an aluminosilicate hydrous mineral and is likely to be stable in hydrated sedimentary layers of subducting slabs. Phase-Pi is likely to be stable between the depths of 60 and 200 km and is likely to transport water into the Earth's interior. Here, we use first principles simulations based on density functional theory to explore the crystal structure at high-pressure, equation of state, and full elastic stiffness tensor as a function of pressure. We find that the pressure volume results could be described by a finite strain fit with V0 , K0 , and K0‧ being 310.3 Å3, 133 GPa, and 3.6 respectively. At zero pressure, the full elastic stiffness tensor shows significant anisotropy with the diagonal principal components C11 , C22 , and C33 being 235, 292, 266 GPa respectively, the diagonal shear C44 , C55 , and C66 being 86, 92, and 87 GPa respectively, and the off-diagonal stiffness C12 , C13 , C14 ,C15 , C16 , C23 , C24 , C25 , C26 , C34 , C35 , C36 , C45 , C46 , and C56 being 73, 78, 6, -30, 15, 61, 17, 2, 1, -13, -15, 6, 3, 1, and 3 GPa respectively. The zero pressure, shear modulus, G0 and its pressure derivative, G0 ‧ are 90 GPa and 1.9 respectively. Upon compression, hydrogen bonding in phase-Pi shows distinct behavior, with some hydrogen bonds weakening and others strengthening. The latter eventually undergo symmetrization, at pressure greater (>40 GPa) than the thermodynamic stability of phase-Pi. Full elastic constant tensors indicate that phase-Pi is very anisotropic with AVP ∼22.4% and AVS ∼23.7% at 0 GPa. Our results also indicate that the bulk sound velocity of phase-Pi is slower than that of the high-pressure hydrous aluminosilicate phase, topaz-OH.

  3. Phase transitions modern applications

    CERN Document Server

    Gitterman, Moshe

    2014-01-01

    This book provides a comprehensive review of the theory of phase transitions and its modern applications, based on the five pillars of the modern theory of phase transitions i.e. the Ising model, mean field, scaling, renormalization group and universality. This expanded second edition includes, along with a description of vortices and high temperature superconductivity, a discussion of phase transitions in chemical reaction and moving systems. The book covers a close connection between phase transitions and small world phenomena as well as scale-free systems such as the stock market and the Internet. Readership: Scientists working in different fields of physics, chemistry, biology and economics as well as teaching material for undergraduate and graduate courses.

  4. Now entering phase two...

    CERN Multimedia

    Katarina Anthony

    2012-01-01

    Building on the success of their feasibility phase, the CLIC test facility, CTF3, has just launched into a five-year project development phase. This will involve detailed performance optimisation studies, marking the project’s transition from pure research and development to prototyping and construction.   CLIC accelerator modules under construction at CERN. “With the feasibility phase now complete, we have established that CLIC can be built,” says Roberto Corsini, CLIC Collaboration spokesperson. “Now we want to be sure that it can provide the luminosity and energy performance needed. We will be looking at the engineering, performance and cost of a real CLIC machine also seeing if we can reduce it.” CTF3’s second phase will focus on selected performance-related research areas for further investigation. The largest of these involves the construction and testing of several authentic CLIC accelerator modules that are currently being ...

  5. Disordered adsorbate phases

    Science.gov (United States)

    Rys, Franz S.

    1985-04-01

    The occurrence of disordered phases at low temperatures in adsorbed monolayers, as shown recently in a domain wall model, is discussed, the main results are summarized and some relevant experimental systems are mentionned.

  6. Multipulse phase resetting curves

    OpenAIRE

    Krishnan, Giri P.; Bazhenov, Maxim; Pikovsky, Arkady

    2013-01-01

    In this paper, we introduce and study systematically, in terms of phase response curves, the effect of dual-pulse excitation on the dynamics of an autonomous oscillator. Specifically, we test the deviations from linear summation of phase advances resulting from two small perturbations. We analytically derive a correction term, which generally appears for oscillators whose intrinsic dimensionality is >1. The nonlinear correction term is found to be proportional to the square of the perturbatio...

  7. Kinetics of phase change

    Directory of Open Access Journals (Sweden)

    A.C. Faleiros

    2000-07-01

    Full Text Available The kinetic model for change of phases developed by M. Avrami at the end of the thirties has been used to describe the temporal behavior of phase changes. Until today this model is studied and adapted to include broader hypotheses. However, the mathematical format presented by M. Avrami is difficult to be understood by beginners. The purpose of this work is to clarify the mathematical treatment of Avrami's work, going straightforward to the arguments that led to his main results.

  8. RNA gets in phase.

    Science.gov (United States)

    Saha, Shambaditya; Hyman, Anthony A

    2017-08-07

    Several neurological disorders are linked to tandem nucleotide repeat expansion in the mutated gene. Jain and Vale (2017. Nature. https://doi.org/10.1038/nature22386) show that, above a pathological threshold repeat number, base pairing interactions drive phase separation of RNA into membrane-less gels, suggesting that RNA can scaffold the assembly of phase-separated compartments that sequester proteins/RNAs causing toxicity. © 2017 Saha and Hyman.

  9. Two phase sampling

    CERN Document Server

    Ahmad, Zahoor; Hanif, Muhammad

    2013-01-01

    The development of estimators of population parameters based on two-phase sampling schemes has seen a dramatic increase in the past decade. Various authors have developed estimators of population using either one or two auxiliary variables. The present volume is a comprehensive collection of estimators available in single and two phase sampling. The book covers estimators which utilize information on single, two and multiple auxiliary variables of both quantitative and qualitative nature. Th...

  10. Electron microscope phase enhancement

    Science.gov (United States)

    Jin, Jian; Glaeser, Robert M.

    2010-06-15

    A microfabricated electron phase shift element is used for modifying the phase characteristics of an electron beam passing though its center aperture, while not affecting the more divergent portion of an incident beam to selectively provide a ninety-degree phase shift to the unscattered beam in the back focal plan of the objective lens, in order to realize Zernike-type, in-focus phase contrast in an electron microscope. One application of the element is to increase the contrast of an electron microscope for viewing weakly scattering samples while in focus. Typical weakly scattering samples include biological samples such as macromolecules, or perhaps cells. Preliminary experimental images demonstrate that these devices do apply a ninety degree phase shift as expected. Electrostatic calculations have been used to determine that fringing fields in the region of the scattered electron beams will cause a negligible phase shift as long as the ratio of electrode length to the transverse feature-size aperture is about 5:1. Calculations are underway to determine the feasibility of aspect smaller aspect ratios of about 3:1 and about 2:1.

  11. Electroweak phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Gregory W. [Univ. of California, Berkeley, CA (United States)

    1991-09-16

    An analytic treatment of the one Higgs doublet, electroweak phase transition is given. The phase transition is first order, occurs by the nucleation of thin walled bubbles and completes at a temperature where the order parameter, <Φ>T is significantly smaller than it is when the origin becomes absolutely unstable. The rate of anomalous baryon number violation is an exponentially function of <Φ>T. In very minimal extensions of the standard model it is quite easy to increase <Φ>T so that anomalous baryon number violation is suppressed after completion of the phase transition. Hence baryogenesis at the electroweak phase transition is tenable in minimal of the standard model. In some cases additional phase transitions are possible. For a light Higgs boson, when the top quark mass is sufficiently large, the state where the Higgs field has a vacuum expectation value <Φ> = 246 GeV is not the true minimum of the Higgs potential. When this is the case, and when the top quark mass exceeds some critical value, thermal fluctuations in the early universe would have rendered the state <Φ> = 246 GeV unstable. The requirement that the state <Φ> = 246 GeV is sufficiently long lived constrains the masses of the Higgs boson and the top quark. Finally, we consider whether local phase transitions can be induced by heavy particles which act as seeds for deformations in the scalar field.

  12. Effect of tungsten addition on high-temperature properties and microstructure of alumina-forming austenitic heat-resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Min-Ho [Division of Materials Science and Engineering, Hanyang University, Seongdong-ku, Seoul 133-791 (Korea, Republic of); Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Moon, Joonoh; Kang, Jun-Yun; Ha, Heon-Young [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Choi, Baig Gyu [High Temperature Materials Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Lee, Tae-Ho [Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Lee, Changhee, E-mail: chlee@hanyang.ac.kr [Division of Materials Science and Engineering, Hanyang University, Seongdong-ku, Seoul 133-791 (Korea, Republic of)

    2015-10-28

    High-temperature tensile and creep properties of W-added Alumina-Forming austenitic (AFA{sub W}) heat-resistant steel were investigated as compared with AFA steel without W. High-temperature tensile properties of two steels were similar to each other, but creep lifetime of AFA{sub W} steel was increased. Microstructural examination using SEM and TEM revealed that creep rate rapidly decreased when Laves phase initially precipitated. This indicated that the precipitation of Laves phase played an important role in hardening of AFA steel. It is also found that AFA{sub W} steel exhibited finer and denser Laves phase compared with AFA steel, which is due to partial substitution of W for Mo. The finer and denser distribution of Laves phase contributed to improved creep properties of AFA{sub W} steel by enhancement in precipitation hardening.

  13. Influence of head group methylation on the phase behavior of lipid monolayers

    DEFF Research Database (Denmark)

    Brezesinski, G.; Bringezu, F.; Weidemann, G.

    1998-01-01

    Monolayers of racemic 1-(2-tetradecylhexadecanoyl)-2-O-hexadecyl-phospholipids 1(2C(14)-16:0)-2H-PE(CH3)(n), with n = 0, 1, 2 and 3, at the air/water interface are studied by film balance measurements, Brewster angle microscopy (BAM) and grazing incidence X-ray diffraction (GIXD). Although the area......-pressure isotherm of the 1(2C(16)-18:0)-2H-PE monolayer shows at 20 degrees C a plateau region which does not directly correspond to the transition from the NN tilted to the hexagonal phase with untilted molecules. BAM measurements show that the large differences between the molecular areas, derived from isotherm...

  14. Combustion 2000: Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    1999-11-01

    The goals of the program are to develop a coal-fired high performance power generation system (HIPPS) that is capable of: thermal efficiency (HHV) {ge} 47%; NOx, SOx, and particulates {le} 10% NSPS (New Source Performance Standard); coal providing {ge} 65% of heat input; all solid wastes benign; and cost of electricity {le} 90% of present plants. Phase 1, which began in 1992, focused on the analysis of various configurations of indirectly fired cycles and on technical assessments of alternative plant subsystems and components, including performance requirements, developmental status, design options, complexity and reliability, and capital and operating costs. Phase 1 also included preliminary R and D and the preparation of designs for HIPPS commercial plants approximately 300 MWe in size. This Phase, Phase 2, had as its initial objective the development of a complete design base for the construction and operation of a HIPPS prototype plant to be constructed in Phase 3. As part of a descoping initiative, the Phase 3 program has been eliminated and work related to the commercial plant design has been ended. The rescoped program retained a program of engineering research and development focusing on high temperature heat exchangers, e.g. HITAF development (Task 2); a rescoped Task 6 that is pertinent to Vision 21 objectives and focuses on advanced cycle analysis and optimization, integration of gas turbines into complex cycles, and repowering designs; and preparation of the Phase 2 Technical Report (Task 8). This rescoped program deleted all subsystem testing (Tasks 3, 4,and 5) and the development of a site-specific engineering design and test plan for the HIPPS prototype plant (Task 7). Work reported herein is from: Task 2.1 HITAF Combustors; Task 2.2 HITAF Air Heaters; and Task 6 HIPPS Commercial Plant Design Update.

  15. Single-phase to three-phase power conversion interface

    Science.gov (United States)

    Wu, Jinn-Chang; Wang, Yung-Shan; Jou, Hurng-Liahng; Lu, Wei-Tso

    2016-07-01

    This study proposes a single-phase to three-phase power conversion interface which converts the power from a single-phase utility to three-phase power for a three-phase load. The proposed single-phase to three-phase power conversion interface comprises a bridge-type switch set, a set of three-phase inductors, a transformer set and a set of three-phase capacitors. A current-mode control controls the switching of bridge-type switch set, to generate a set of nonzero-sequence (NZS) currents and a set of zero-sequence (ZS) currents. The transformer set is used to decouple the NZS currents and the ZS currents. The NZS currents are used to generate a high-quality three-phase voltage that supplies power to a three-phase load. The ZS currents flow to the single-phase utility so that the utility current is sinusoidal and in phase with the utility voltage. Accordingly, only a bridge-type switch set is used in the single-phase to three-phase power conversion interface to simply the power circuit. A prototype is developed and tested to verify the performance of the proposed single-phase to three-phase power conversion interface.

  16. Determination of individual homologues and total content of benzalkonium chloride by reversed-phase high-performance liquid chromatography using a short butyl column.

    Science.gov (United States)

    Liu, Fangzhu; Xiao, Kang Ping; Rustum, Abu M

    2009-01-01

    Benzalkonium chloride (a mixture of alkylbenzyldimethylammonium chlorides that usually contains C-10, C-12, C-14, and C-16 homologues), commonly known as BKC, is used as a bacteriostatic agent in many household, food, and drug products. In this paper, we report a simple, rapid, robust, and stability-indicating reversed-phase HPLC method using a short butyl (C4) column for the simultaneous determination of each individual homologue content, as well as the total concentration of individual homologues in commercial bulk raw material batches of BKC samples. The chromatographic separation was performed on a 5 cm ACE C4 column with mobile phase consisting of water, acetonitrile, and potassium chloride. Even though using a short column can potentially cause some challenges to resolving certain critical pairs of peaks, we have successfully separated all of the analyte peaks (including those from stressed, degraded products) on a short column using an optimal mobile phase.

  17. Acute-phase reactants

    Directory of Open Access Journals (Sweden)

    Harpreet Singh Grover

    2016-01-01

    Full Text Available The acute-phase response (APR is a prominent systemic reaction of the organism to local or systemic disturbances in its homeostasis caused by infection, tissue injury, trauma or surgery, or immunological disorders. The tissue macrophage is most commonly regarded as initiating the APR through direct stimulation and secretion of various cell communicating factors. Proinflammatory cytokines and mediators are significantly elevated with gingival inflammation and during the destructive phase of periodontitis. Cytokines appear to play a major role in the clinical symptoms and tissue destruction associated with progressing periodontitis. Many of these cytokines are derived from activated macrophages and can act both locally and distally to amplify cytokine production from other cell types. The host responses to periodontal disease and cardiovascular diseases were reflected by an increase in the acute-phase proteins (serum amyloid A and C-reactive protein.

  18. Phase coexistence in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Gulminelli, F

    2003-05-01

    In this work the general theory of first order phase transitions in finite systems is discussed, with a special emphasis to the conceptual problems linked to a thermodynamic description for small, short-lived systems de-exciting in the vacuum as nuclear samples coming from heavy ion collisions. After a short review of the general theory of phase transitions in the framework of information theory; we will present the different possible extensions to the field of finite systems. The concept of negative heat capacity, developed in the early seventies in the context of self-gravitating systems, will be reinterpreted in the general framework of convexity anomalies of thermo-statistical potentials. The connection with the distribution of the order parameter will lead us to a definition of first order phase transitions in finite systems based on topology anomalies of the event distribution in the space of observations. A careful study of the thermodynamic limit will provide a bridge with the standard theory of phase transitions and show that in a wide class of physical situations the different statistical ensembles are irreducibly inequivalent. In the second part of the paper we will apply the theoretical ideas developed in the first part to the possible observation of a liquid-to-gas-like phase transition in heavy ion collisions. The applicability of equilibrium concepts in a dynamical collisional process without boundary conditions will first be critically discussed. The observation of abnormally large partial energy fluctuations in carefully selected samples of collisions detected with the MULTICS-Miniball array will then be reported as a strong evidence of a first order phase transition with negative heat capacity in the nuclear equation of state. (author)

  19. Electroweak phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, G.W.

    1991-09-16

    An analytic treatment of the one Higgs doublet, electroweak phase transition is given. The phase transition is first order, occurs by the nucleation of thin walled bubbles and completes at a temperature where the order parameter, {l angle}{phi}{r angle}{sub T} is significantly smaller than it is when the origin becomes absolutely unstable. The rate of anomalous baryon number violation is an exponentially function of {l angle}{phi}{r angle}{sub T}. In very minimal extensions of the standard model it is quite easy to increase {l angle}{phi}{r angle}{sub T} so that anomalous baryon number violation is suppressed after completion of the phase transition. Hence baryogenesis at the electroweak phase transition is tenable in minimal of the standard model. In some cases additional phase transitions are possible. For a light Higgs boson, when the top quark mass is sufficiently large, the state where the Higgs field has a vacuum expectation value {l angle}{phi}{r angle} = 246 GeV is not the true minimum of the Higgs potential. When this is the case, and when the top quark mass exceeds some critical value, thermal fluctuations in the early universe would have rendered the state {l angle}{phi}{r angle} = 246 GeV unstable. The requirement that the state {l angle}{phi}{r angle} = 246 GeV is sufficiently long lived constrains the masses of the Higgs boson and the top quark. Finally, we consider whether local phase transitions can be induced by heavy particles which act as seeds for deformations in the scalar field.

  20. Understanding quantum phase transitions

    CERN Document Server

    Carr, Lincoln

    2010-01-01

    Quantum phase transitions (QPTs) offer wonderful examples of the radical macroscopic effects inherent in quantum physics: phase changes between different forms of matter driven by quantum rather than thermal fluctuations, typically at very low temperatures. QPTs provide new insight into outstanding problems such as high-temperature superconductivity and display fundamental aspects of quantum theory, such as strong correlations and entanglement. Over the last two decades, our understanding of QPTs has increased tremendously due to a plethora of experimental examples, powerful new numerical meth

  1. Solid phase transformations

    CERN Document Server

    Čermák, J

    2008-01-01

    This special-topic book, devoted to ""Solid Phase Transformations"" , covers a broad range of phenomena which are of importance in a number of technological processes. Most commercial alloys undergo thermal treatment after casting, with the aim of imparting desired compositions and/or optimal morphologies to the component phases. In spite of the fact that the topic has lain at the center of physical metallurgy for a long time, there are numerous aspects which are wide open to potential investigative breakthroughs. Materials with new structures also stimulate research in the field, as well as n

  2. Electronic phase transitions

    CERN Document Server

    Kopaev, YuV

    1992-01-01

    Electronic Phase Transitions deals with topics, which are presently at the forefront of scientific research in modern solid-state theory. Anderson localization, which has fundamental implications in many areas of solid-state physics as well as spin glasses, with its influence on quite different research activities such as neural networks, are two examples that are reviewed in this book. The ab initio statistical mechanics of structural phase transitions is another prime example, where the interplay and connection of two unrelated disciplines of solid-state theory - first principle ele

  3. Compressive Phase Contrast Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Maia, Filipe; MacDowell, Alastair; Marchesini, Stefano; Padmore, Howard A.; Parkinson, Dula Y.; Pien, Jack; Schirotzek, Andre; Yang, Chao

    2010-09-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. Interference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher contrast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).

  4. Phase Contrast Imaging

    DEFF Research Database (Denmark)

    1996-01-01

    The invention relates to a method and a system for synthesizing a prescribed intensity pattern based on phase contrast imaging that is not based on the assumption of prior art methods that the pahase shift phi is less than 1 radian. An improved method based on a simple imaging operation with a si......The invention relates to a method and a system for synthesizing a prescribed intensity pattern based on phase contrast imaging that is not based on the assumption of prior art methods that the pahase shift phi is less than 1 radian. An improved method based on a simple imaging operation...

  5. Gas phase ion chemistry

    CERN Document Server

    Bowers, Michael T

    1979-01-01

    Gas Phase Ion Chemistry, Volume 1 covers papers on the advances of gas phase ion chemistry. The book discusses the advances in flow tubes and the measurement of ion-molecule rate coefficients and product distributions; the ion chemistry of the earth's atmosphere; and the classical ion-molecule collision theory. The text also describes statistical methods in reaction dynamics; the state selection by photoion-photoelectron coincidence; and the effects of temperature and pressure in the kinetics of ion-molecule reactions. The energy distribution in the unimolecular decomposition of ions, as well

  6. Jeg anerkender den musikalske tradition - men jeg prøver ikke at lave musik

    DEFF Research Database (Denmark)

    Holmboe, Rasmus

    2013-01-01

    Interview med Jacob Kirkegaard i anledning af hans udgivelse: ”Conversion”. Det blev en samtale om reallyde, der bliver til instrumentallyde, om afvisningen af det subjektive udtryk, og om hvordan musikken i sidste ende ikke er komponistens men lytterens anliggende....

  7. Dynamic phase extraction in phase-shifted shearography

    Science.gov (United States)

    Hou, Yuanyuan; Xu, Jiancheng

    2016-03-01

    Phase-shifted shearography needs to extract dynamic phase of the measured object after loading, so an algorithm for dynamic phase extraction in phase-shifted shearography is proposed to analyze the speckle patterns with random phase shifts. By using correlation method, the fringe patterns with random phase shifts are obtained from the speckle patterns with random phase shifts. Then the dynamic phase distributions are extracted from one set of random phase-shifted fringe patterns by principle component analysis. The experimental results show that the extracted phases are accurate and efficient. The proposed method is non-iterative and has no strict requirement for the spatial-carrier frequency of fringe patterns, so it is suitable for dynamic shearing speckle interferometry.

  8. Solid Phase versus Solution Phase Synthesis of Heterocyclic Macrocycles

    OpenAIRE

    McAlpine, Shelli R.; Seong Jong Kim

    2013-01-01

    Comparing a solution phase route to a solid phase route in the synthesis of the cytotoxic natural product urukthapelstatin A (Ustat A) confirmed that a solid phase method is superior. The solution phase approach was tedious and involved cyclization of a ridged heterocyclic precursor, while solid phase allowed the rapid generation of a flexible linear peptide. Cyclization of the linear peptide was facile and subsequent generation of three oxazoles located within the structure of Ustat A proved...

  9. Theory of alloy phases

    Energy Technology Data Exchange (ETDEWEB)

    Watson, R.E.; Ehrenreich, H.; Bennett, L.H.

    1977-01-01

    Various non-thermodynamic approaches to understanding and predicting phase diagrams are explored from the viewpoint of solid-state physics. The review is intended to indicate the scope of activity and some of the progress which has been made. (GHT)

  10. Many Phases of Carbon

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 7; Issue 12. Many Phases of Carbon. B Gopalakrishnan S V Subramanyam. General Article Volume 7 Issue 12 December 2002 pp 10-19. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/007/12/0010-0019 ...

  11. Black hole Berry phase

    NARCIS (Netherlands)

    de Boer, J.; Papadodimas, K.; Verlinde, E.

    2009-01-01

    Supersymmetric black holes are characterized by a large number of degenerate ground states. We argue that these black holes, like other quantum mechanical systems with such a degeneracy, are subject to a phenomenon which is called the geometric or Berry’s phase: under adiabatic variations of the

  12. SKIPAL, Phase 2

    Science.gov (United States)

    2009-11-01

    Phase 2, SKIPAL incorporated the Spring Web MVC framework to facilitate future integration efforts with SKIWeb. Spring Web MVC is a web framework...based on the Model-View-Controller ( MVC ) design pattern. New events created in SKIWeb activate a database trigger that captures the id numbers of the

  13. diffusive phase separation

    Directory of Open Access Journals (Sweden)

    Nobuyuki Kenmochi

    1996-01-01

    w is constrained to have double obstacles σ*≤w≤σ* (i.e., σ* and σ* are the threshold values of w. The objective of this paper is to discuss the semigroup {S(t} associated with the phase separation model, and construct its global attractor.

  14. ALMIP Phase I Report

    DEFF Research Database (Denmark)

    Boone, Aaron; de Rosnay, Patricia; Beljaars, Anton

      This report describes the experimental setup and results of the Phase 1 (i.e. the Regional Scale) of the AMMA (African Monsoon Multidisciplinary Analysis) Land surface Model Intercomparison Project (ALMIP). It is part of the AMMA-EU (European Union) and API  (Action Programmée Interorganisme...

  15. Photoinduced phase transitions

    CERN Document Server

    Nasu, K

    2004-01-01

    A new class of insulating solids was recently discovered. Whenirradiated by a few visible photons, these solids give rise to amacroscopic excited domain that has new structural and electronicorders quite different from the starting ground state. This occurrenceis called "photoinduced phase transition", and this multi-authoredbook reviews recent theoretical and experimental studies of this newphenomenon.

  16. Gas-Phase Thermolyses

    DEFF Research Database (Denmark)

    Carlsen, Lars; Egsgaard, Helge

    1982-01-01

    The unimolecular gas-phase thermolyses of the four methyl and ethyl monothioacetates (5)–(8) have been studied by the flash vacuum thermolysis–field ionization mass spectrometry technique in the temperature range 883–1 404 K. The types of reactions verified were keten formation, thiono–thiolo rea...

  17. 78 FR 33911 - Phased Retirement

    Science.gov (United States)

    2013-06-05

    ... making an election of phased retirement, the procedures for electing phased retirement, the requirements... return to regular employment status, the effective date of the decision to end phased retirement, and... retirement contributions and Social Security old-age benefits, the phased retirement annuity equals (1) the...

  18. The Importance of Rare-Earth Additions in Zr-Based AB2 Metal Hydride Alloys

    Directory of Open Access Journals (Sweden)

    Kwo-Hsiung Young

    2016-07-01

    Full Text Available Effects of substitutions of rare earth (RE elements (Y, La, Ce, and Nd to the Zr-based AB2 multi-phase metal hydride (MH alloys on the structure, gaseous phase hydrogen storage (H-storage, and electrochemical properties were studied and compared. Solubilities of the RE atoms in the main Laves phases (C14 and C15 are very low, and therefore the main contributions of the RE additives are through the formation of the RENi phase and change in TiNi phase abundance. Both the RENi and TiNi phases are found to facilitate the bulk diffusion of hydrogen but impede the surface reaction. The former is very effective in improving the activation behaviors. −40 °C performances of the Ce-doped alloys are slightly better than the Nd-doped alloys but not as good as those of the La-doped alloys, which gained the improvement through a different mechanism. While the improvement in ultra-low-temperature performance of the Ce-containing alloys can be associated with a larger amount of metallic Ni-clusters embedded in the surface oxide, the improvement in the La-containing alloys originates from the clean alloy/oxide interface as shown in an earlier transmission electron microscopy study. Overall, the substitution of 1 at% Ce to partially replace Zr gives the best electrochemical performances (capacity, rate, and activation and is recommended for all the AB2 MH alloys for electrochemical applications.

  19. Phase estimation in optical interferometry

    CERN Document Server

    Rastogi, Pramod

    2014-01-01

    Phase Estimation in Optical Interferometry covers the essentials of phase-stepping algorithms used in interferometry and pseudointerferometric techniques. It presents the basic concepts and mathematics needed for understanding the phase estimation methods in use today. The first four chapters focus on phase retrieval from image transforms using a single frame. The next several chapters examine the local environment of a fringe pattern, give a broad picture of the phase estimation approach based on local polynomial phase modeling, cover temporal high-resolution phase evaluation methods, and pre

  20. Engineering Holographic Superconductor Phase Diagrams

    OpenAIRE

    Chen, Jiunn-Wei; Dai, Shou-Huang; Maity, Debaprasad; Zhang, Yun-Long

    2016-01-01

    We study how to engineer holographic models with features of a high temperature superconductor phase diagram. We introduce a field in the bulk which provides a tunable "doping" parameter in the boundary theory. By designing how this field changes the effective masses of other order parameter fields, desired phase diagrams can be engineered. We give examples of generating phase diagrams with phase boundaries similar to a superconducting dome and an anti-ferromagnetic phase by including two ord...

  1. Phase coexistence in nuclei

    Science.gov (United States)

    Gulminelli, F.

    2004-11-01

    In this work the general theory of first order phase transitions in finite systems is discussed, with a special emphasis to the conceptual problems linked to a thermodynamic description for small, short-lived systems de-exciting in the vacuum as nuclear samples coming from heavy ion collisions. After a short review of the general theory of phase transitions in the framework of information theory, we will present the different possible extensions to the field of finite systems. The concept of negative heat capacity, developed in the early seventies in the context of self-gravitating systems, will be reinterpreted in the general framework of convexity anomalies of thermostatistical potentials. The connection with the distribution of the order parameter will lead us to a definition of first order phase transitions in finite systems based on topology anomalies of the event distribution in the space of observations. A careful study of the thermodynamic limit will provide a bridge with the standard theory of phase transitions and show that in a wide class of physical situations the different statistical ensembles are irreducibly inequivalent. In the second part of the paper we will apply the theoretical ideas developed in the first part to the possible observation of a liquid-to-gas-like phase transition in heavy ion collisions. The applicability of equilibrium concepts in a dynamical collisional process without boundary conditions will first be critically discussed. The observation of abnormally large partial energy fluctuations in carefully selected samples of collisions detected with the MULTICS-Miniball and INDRA array will then be reported as a strong evidence of a first order phase transition with negative heat capacity in the nuclear equation of state. Coexistence de phase dans les noyaux Ce papier présente une revue de la théorie générale des transitions de phase du premier ordre dans les petits systèmes, avec une attention particulière aux probl

  2. Solid Phase versus Solution Phase Synthesis of Heterocyclic Macrocycles

    Directory of Open Access Journals (Sweden)

    Shelli R. McAlpine

    2013-01-01

    Full Text Available Comparing a solution phase route to a solid phase route in the synthesis of the cytotoxic natural product urukthapelstatin A (Ustat A confirmed that a solid phase method is superior. The solution phase approach was tedious and involved cyclization of a ridged heterocyclic precursor, while solid phase allowed the rapid generation of a flexible linear peptide. Cyclization of the linear peptide was facile and subsequent generation of three oxazoles located within the structure of Ustat A proved relatively straightforward. Given the ease with which the oxazole Ustat A precursor is formed via our solid phase approach, this route is amenable to rapid analog synthesis.

  3. Solid phase versus solution phase synthesis of heterocyclic macrocycles.

    Science.gov (United States)

    Kim, Seong Jong; McAlpine, Shelli R

    2013-01-16

    Comparing a solution phase route to a solid phase route in the synthesis of the cytotoxic natural product urukthapelstatin A (Ustat A) confirmed that a solid phase method is superior. The solution phase approach was tedious and involved cyclization of a ridged heterocyclic precursor, while solid phase allowed the rapid generation of a flexible linear peptide. Cyclization of the linear peptide was facile and subsequent generation of three oxazoles located within the structure of Ustat A proved relatively straightforward. Given the ease with which the oxazole Ustat A precursor is formed via our solid phase approach, this route is amenable to rapid analog synthesis.

  4. Phase Field Fracture Mechanics.

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Brett Anthony [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-11-01

    For this assignment, a newer technique of fracture mechanics using a phase field approach, will be examined and compared with experimental data for a bend test and a tension test. The software being used is Sierra Solid Mechanics, an implicit/explicit finite element code developed at Sandia National Labs in Albuquerque, New Mexico. The bend test experimental data was also obtained at Sandia Labs while the tension test data was found in a report online from Purdue University.

  5. Phases and phase transitions of S=1 bosons

    Indian Academy of Sciences (India)

    smukerjee

    Quantum phases and phase transitions of bosons. Subroto Mukerjee. Dept. of Physics & Centre for Quantum. Information and Quantum Computing (CQIQC). Indian Institute of Science, Bangalore. 77th annual meeting of the IAS, Nov. 20 2011, PRL Ahmedabad ...

  6. The Berry phase and the phase of the determinant

    Energy Technology Data Exchange (ETDEWEB)

    Braverman, Maxim [Department of Mathematics, Northeastern University, Boston, Massachusetts 02115 (United States)

    2014-04-15

    We show that under very general assumptions the adiabatic approximation of the phase of the zeta-regularized determinant of the imaginary-time Schrödinger operator with periodic Hamiltonian is equal to the Berry phase.

  7. Gold tetrahedra as building blocks in K3Au5Tr (Tr = In, Tl) and Rb2Au3Tl and in other compounds: a broad group of electron-poor intermetallic phases.

    Science.gov (United States)

    Li, Bin; Kim, Sung-Jin; Miller, Gordon J; Corbett, John D

    2009-07-20

    The alkali-metal gold trielides K(3)Au(5)Tr (Tr = In (I), Tl (II)) and Rb(2)Au(3)Tl (III) have been obtained directly from the elements, and their orthorhombic structures determined by single-crystal X-ray diffraction means (I/II: Imma, a = 5.562(1), 5.595(1); b = 19.645(4),19.706(4); c = 8.502(2), 8.430(2) A; Z = 4, respectively; III: Pmma, a = 5.660(1), b = 6.741(1), c = 9.045(2) A, Z = 4). These exhibit zigzag chains of Tr that link puckered sheets (I/II) or chains (III) of gold tetrahedra condensed through shared vertices. The segregation of Au and Tr components is striking relative to the evidently stronger and preferred Au-Tr bonding in neighboring gold- and alkali-metal-poorer triel phases. The close packing of K/Rb (A) about the gold tetrahedra gives each A and Au(4) component 7-10 and 10 neighbors of the other type, respectively. Tight-binding-linear-muffin-tin-orbital-atomic sphere approximation band structure calculations show that the title phases lie near or at electronic pseudogaps. The gold substructure is the dominant feature of the densities of states, with moderately broad 5d(10) features as favored by relativistic effects. Likewise, crystal orbital Hamilton population results indicate optimization of Au-Au bonding at the expense of the stronger heteroatomic Au-Tr interactions. Stabilization of these unusual structures appears to follow in part from the presence of numerous short and individually weak A-Au interactions, as manifested by appreciable mixing of s, p, and d valence orbitals on A into network bonding states, Au 5d in particular. These and related phases define a family of Au(4)-based phases with particularly low e/a values of 1.2 to approximately 2.3 (over all atoms, omitting Au 5d), closely related to the cubic Laves-type structures. The same region also contains Tr-richer tunnel and network structures with relatively fewer cations that also appear to be dominated by Au-Au and Au-Tr bonding.

  8. Atmospheric gas phase reactions

    Science.gov (United States)

    Platt, Ulrich

    This chapter introduces the underlying physicochemical principles and the relevance of atmospheric gas phase reactions. In particular, reaction orders, the concept of elementary reactions, definition of and factors determining reaction rates (kinetic theory of chemical reactions), and photochemical reactions are discussed. Sample applications of the pertinent reaction pathways in tropospheric chemistry are presented, particularly reactions involving free radicals (OH, NO3, halogen oxides) and their roles in the self-cleaning of the troposphere. The cycles of nitrogen and sulfur species as well as the principles of tropospheric ozone formation are introduced. Finally, the processes governing the stratospheric ozone layer (Chapman Cycle and extensions) are discussed.

  9. Gas-Phase Thermolyses

    DEFF Research Database (Denmark)

    Carlsen, Lars; Egsgaard, Helge

    1982-01-01

    The unimolecular gas-phase thermolyses of 1,2,3-oxadithiolan 2-oxide and thiiran 1-oxide have been studied by the flash vacuum thermolysis–field ionization mass spectrometry (f.v.t.–f.i.m.s.) technique in the temperature range from 1 043 to 1 404 K. The reactions are rationalized in terms...... of sulphoxide–sulphenate rearrangement and atomic oxygen, sulphur monoxide, and sulphur dioxide extrusions. Evidence is presented for the common intermediacy of 1,2-oxathietan from the thermolyses of both 1,2,3-oxadithiolan 2-oxide and thiiran 1-oxide....

  10. Two-Phase Accumulator

    Science.gov (United States)

    Kalb, Charles E.; Kosson, Robert L.; Alario, Joseph P.; Brown, Richard F.; Edlestein, Fred

    1990-01-01

    Two-phase accumulator maintains pressure and temperature in thermal-bus system within predetermined range during variations in heat load on system. Stores liquid and vapor ammonia. Exchanges liquid ammonia with condenser to adjust level of liquid in condenser. Prototype has capacity of 13 gallons (49 liters). Simple and highly reliable. Responds quickly, restoring pressure and temperature to proper values within minutes. Low in cost and requires little further development. Used to dispose of waste heat, such as that from electronic equipment or power-plant.

  11. Solid-phase microextraction

    DEFF Research Database (Denmark)

    Nilsson, Torben

    and organophosphate pesticides and triazine herbicides together with their metabolites in aqueous samples. SPME combined with gas chromatography proved to be a precise, accurate and sensitive technique for water analysis. Also SPME combined with high performance liquid chromatography was tested, and a method......The objective of this study has been to develop new analytical methods using the rapid, simple and solvent-free extraction technique solid-phase microextraction (SPME) for the quantitative analysis of organic pollutants at trace level in drinking water and environmental samples. The dynamics...

  12. Phase change memory

    CERN Document Server

    Qureshi, Moinuddin K

    2011-01-01

    As conventional memory technologies such as DRAM and Flash run into scaling challenges, architects and system designers are forced to look at alternative technologies for building future computer systems. This synthesis lecture begins by listing the requirements for a next generation memory technology and briefly surveys the landscape of novel non-volatile memories. Among these, Phase Change Memory (PCM) is emerging as a leading contender, and the authors discuss the material, device, and circuit advances underlying this exciting technology. The lecture then describes architectural solutions t

  13. Incommensurate phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Currat, R. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1996-11-01

    We review the characteristic aspects of modulated crystals from the point of view of inelastic neutron scattering. We discuss the phenomenological Landau theory of the normal-to-incommensurate displacive instability and its predictions concerning the fluctuation spectrum of the modulated phase. General results on the form of the normal-mode eigenvectors and on the inelastic scattering channels through which they couple to the probe are established using the superspace approach. We illustrate these results on a simple discrete model symmetry and we review available inelastic neutron scattering data on several displacively modulated compounds. (author) 21 figs., 73 refs.

  14. Geometric phase around exceptional points

    OpenAIRE

    Mailybaev, Alexei; Kirillov, Oleg; Seyranian, Alexander,

    2005-01-01

    A wave function picks up, in addition to the dynamic phase, the geometric (Berry) phase when traversing adiabatically a closed cycle in parameter space. We develop a general multidimensional theory of the geometric phase for (double) cycles around exceptional degeneracies in non-Hermitian Hamiltonians. We show that the geometric phase is exactly $\\pi$ for symmetric complex Hamiltonians of arbitrary dimension and for nonsymmetric non-Hermitian Hamiltonians of dimension 2. For nonsymmetric non-...

  15. Phase Referencing in Optical Interferometry

    OpenAIRE

    Filho, Mercedes E.; Garcia, Paulo; Duvert, Gilles; Duchene, Gaspard; Thiebaut, Eric; Young, John; Absil, Olivier; Berger, Jean-Phillipe; Beckert, Thomas; Hoenig, Sebastian; Schertl, Dieter; Weigelt, Gerd; Testi, Leonardo; Tatuli, Eric; Borkowski, Virginie

    2008-01-01

    One of the aims of next generation optical interferometric instrumentation is to be able to make use of information contained in the visibility phase to construct high dynamic range images. Radio and optical interferometry are at the two extremes of phase corruption by the atmosphere. While in radio it is possible to obtain calibrated phases for the science objects, in the optical this is currently not possible. Instead, optical interferometry has relied on closure phase techniques to produce...

  16. Topological phases of quantum matter

    Indian Academy of Sciences (India)

    Can think of a phase as a collection of particles with some properties which distinguish them from other phases. Earlier, phases were classified in terms of expectation values of `local' order parameters and broken symmetries -for example ferromagnets break rotational symmetry and have all spins pointing in one direction ...

  17. Geometric phase and quantum potential

    OpenAIRE

    Dandoloff, R.

    2002-01-01

    We show that the geometric phase of Levy-Leblond arises from a low of parallel transport for wave functions and point out that this phase belongs to a new class of geometric phases due to the presence of a quantum potential.

  18. Phase-change materials handbook

    Science.gov (United States)

    Hale, D. V.; Hoover, M. J.; Oneill, M. J.

    1972-01-01

    Handbook describes relationship between phase-change materials and more conventional thermal control techniques and discusses materials' space and terrestrial applications. Material properties of most promising phase-change materials and purposes and uses of metallic filler materials in phase-change material composites are provided.

  19. Phase strength and super lattices

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Powder XRD investigations on dotriacontane-decane and dotriacontane-decanol mixtures are made. Phase strength, phase separation and formation of superlattices are discussed. The role of tunnel-like defects is considered. Keywords. Hydrocarbons; mixtures; phase strength; tunnel-like defects; super lattices. 1.

  20. Phase-Field Modeling

    Science.gov (United States)

    Karma, Alain

    The phase-field method is a powerful simulation tool to describe xxx the complex evolution of interfaces in a wide range of contexts without explicitly tracking these interfaces. Its main application to date has been to problems in materials science where the evolution of interfaces and defects in the interior or on the surface of a material has a profound impact on its behavior [8]. A partial list of applications to date in this general area includes alloy solidification [5], where models combine elements of the first phase-field models of the solidification of pure materials [9, 32] and the Cahn-Hilliard equation (7), solid-state precipitation [66], stress-driven interfacial instabilities [29, 41, 58], microstructural evolution in polycrystalline materials [17, 31, 36, 60], crystal nucleation [16], surface growth [13, 25, 44], thin film patterning [34], ferroelectric materials [57], dislocation dynamics [22, 49, 52, 55], and fracture [3, 11, 27, 56]. Interface tracking is avoided by making interfaces spatially diffuse with the help of order parameters that vary smoothly in space. Evolution equations for these order parameters are derived variationally from a Lyapounov functional that represents the total free-energy of the system. This theoretical construct provides great flexibility to model simultaneously various physical processes on different length and time scales within a single self-consistent set of coupled partial differential equations.

  1. Phases of QCD

    Energy Technology Data Exchange (ETDEWEB)

    Roessner, Simon

    2009-04-09

    Quantum Chromodynamics (QCD) is the theory of the strong interaction within the Standard Model of elementary particles. Today's research in this area dedicates substantial resources to numeric solutions of the QCD field equations and experimental programs exploring the phases of QCD. This thesis proceeds along a complementary line - that of modelling QCD, with the aim of identifying its dominant degrees of freedom. This is possible by minimally coupling effective potentials for the Polyakov loop to Nambu-Jona-Lasinio models using temporal background fields to model chiral symmetry breaking respecting colour confinement. The fermion sign problem resulting from the minimal coupling is addressed in this work establishing a novel, systematically ordered approach. The modifications to the approximative order parameter of colour confinement, the Polyakov loop, are in direct connection with the fermion sign problem. Furthermore an effective coupling of quark densities of different flavours is induced. This mechanism, most likely also present in QCD, produces finite contributions to flavour off diagonal susceptibilities. Susceptibilities are amongst the most promising physical quantities for the experimental exploration of the phase transition at high temperatures and densities. (orig.)

  2. Phase-step retrieval for tunable phase-shifting algorithms

    Science.gov (United States)

    Ayubi, Gastón A.; Duarte, Ignacio; Perciante, César D.; Flores, Jorge L.; Ferrari, José A.

    2017-12-01

    Phase-shifting (PS) is a well-known technique for phase retrieval in interferometry, with applications in deflectometry and 3D-profiling, which requires a series of intensity measurements with certain phase-steps. Usually the phase-steps are evenly spaced, and its knowledge is crucial for the phase retrieval. In this work we present a method to extract the phase-step between consecutive interferograms. We test the proposed technique with images corrupted by additive noise. The results were compared with other known methods. We also present experimental results showing the performance of the method when spatial filters are applied to the interferograms and the effect that they have on their relative phase-steps.

  3. An analytical method for the determination of perfluorinated compounds in whole blood using acetonitrile and solid phase extraction methods.

    Science.gov (United States)

    Yeung, Leo W Y; Taniyasu, Sachi; Kannan, Kurunthachalam; Xu, Della Z Y; Guruge, Keerthi S; Lam, Paul K S; Yamashita, Nobuyoshi

    2009-06-19

    A method for the analysis of perfluorinated compounds (perfluoroalkyl sulfonates: C4, C6, C8, C10; perfluoroalkyl sulfinates: C6, C8, C10; perfluorooctanesulfonamide, N-ethyl perfluorooctanesulfonamide, N-ethyl perfluorooctanesulfonamidoacetate, perfluorocarboxylates: C4-C14; fluorotelomer carboxylate (7:3, 8:2) in whole blood using acetonitrile and OASIS WAX solid phase extraction (SPE) cartridge was developed. Separation of target compounds in two HPLC columns (ion exchange JJ50-2D and C18 Betasil columns) was examined. Matrix recoveries of the developed methods ranged from 70% to 120%. Separation of possible inferences such as taurodeoxycholic acid (TDC) was accomplished using an ion exchange JJ50-2D column, and this separation was validated using whole blood of different animals.

  4. Measuring phase with Stokes measurements

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2014-07-01

    Full Text Available ↔+U↕ei3ϕ 135° I13 * Measure in an orthogonal basis: & OR & 45°0° IR 135° IL * Adjust the phase between & by π/2 LCD PG Spatial light modulators allow us to alter the phase of an optical field Initial Beam Hologram... Final Beam We exploit the SLM’s diffraction inefficiency to independently control the phase between orthogonal polarization components Initial Beam LCD Final Beam 0 1 Independently control the phase between & * Adjust the phase between...

  5. Geometric phase shifting digital holography.

    Science.gov (United States)

    Jackin, Boaz Jessie; Narayanamurthy, C S; Yatagai, Toyohiko

    2016-06-01

    A new phase shifting digital holographic technique using a purely geometric phase in Michelson interferometric geometry is proposed. The geometric phase in the system does not depend upon either optical path length or wavelength, unlike dynamic phase. The amount of geometric phase generated is controllable through a rotating wave plate. The new approach has unique features and major advantages in holographic measurement of transparent and reflecting three-dimensional (3D) objects. Experimental results on surface shape measurement and imaging of 3D objects are presented using the proposed method.

  6. METHODOLOGICAL NOTES: Metastable phases, phase transformations, and phase diagrams in physics and chemistry

    Science.gov (United States)

    Brazhkin, Vadim V.

    2006-07-01

    Concepts of a 'phase' and a 'phase transition' are discussed for stable and metastable states of matter. While condensed matter physics primarily considers equilibrium states and treats metastable phases as exceptions, organic chemistry overwhelmingly deals with metastable states. It is emphasized that many simple light-element compounds — including most hydrocarbons; nitrogen oxides, hydrides, and carbides; carbon monoxide CO; alcohols and glycerin — are also metastable at normal pressure in the sense that they do not correspond to a minimum Gibbs free energy for a given chemical composition. At moderate temperatures and pressures, the phase transformations for these metastable phases are reversible with the fulfilment of all laws of equilibrium thermodynamics over the entire range of experimentally accessible times. At sufficiently high pressures (> 1-10 GPa), most of the metastable molecular phases irreversibly transform to lower-energy polymer phases, stable or metastable. These transitions do not correspond to the equality of the Gibbs free energy for the involved phases before and after the transition and so they are not first-order in the 'classical' sense. At normal pressure, the resulting polymer phases can exist at temperatures above the melting point of the original metastable molecular phase, as the examples of polyethylene and polymerized CO dramatically illustrate. As pressure is increased further to 20-50 GPa, the PV contribution to Gibbs free energy gives rise to stable high-density atomic phases. Many of the intermediate-energy polymer phases can likely be synthesized by methods of 'classical' chemistry at normal pressure.

  7. Selective dissolution in AlFeNb alloys

    Energy Technology Data Exchange (ETDEWEB)

    Drensler, Stefanie; Mardare, Cezarina Cela; Hassel, Achim Walter [Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University, Linz (Austria); Milenkovic, Srdjan [IMDEA Materials, Parque Cientifico de la Universidad Carlos III de Madrid, Avda. del mar Mediterraneo 22, 28918 Leganes (Spain)

    2012-05-15

    Three different AlFeNb alloys of various compositions were prepared by arc melting. X-ray diffraction (XRD) investigation of the melted samples proved the presence of two phases identified as a bcc {alpha}(Fe,Al) solid solution and a hexagonal C14 (Fe,Al){sub 2}Nb Laves phase. Subsequent electrochemical treatment allowed for a selective dealloying of the {alpha}(Fe,Al) or respective FeAl phase and resulted in releasing differently microstructured surfaces. These structures ranged from regular lamellar structures towards branched, fibrous structures. Scanning electron microscope (SEM) characterisation along with a local energy dispersive X-ray spectroscopic (EDX) analysis of the samples and atomic absorption spectrometry (AAS) analysis of the electrolyte revealed a preferential Fe dissolution and the passive nature of the Nb. The results demonstrate that the phases present in the alloys strongly depend on the production and heat treatment history of the sample. SEM micrograph of (A) Fe-15Al-10Nb and (B) Fe-26Al-4Nb after anodisation in 0.4 M borate buffer. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Phase vocoder and beyond

    Directory of Open Access Journals (Sweden)

    Marco Liuni

    2013-08-01

    Full Text Available For a broad range of sound transformations, quality is measured according to the common expectation about the result: if a male’s voice has to be changed in a female’s one, there exists a common reference for the perceptive evaluation of the result; the same holds if an instrumental sound has to be made longer, or shorter. Following the argument in Röbel, “Between Physics and Perception: Signal Models for High Level Audio Processing”, a fundamental requirement for these transformation algorithms is their need of signal models that are strongly linked to perceptually relevant physical properties of the sound source. This paper is a short survey about the phase vocoder technique, together with its extensions and improvements relying on appropriate sound models, which have led to high level audio processing algorithms.

  9. Options Study - Phase II

    Energy Technology Data Exchange (ETDEWEB)

    R. Wigeland; T. Taiwo; M. Todosow; W. Halsey; J. Gehin

    2010-09-01

    The Options Study has been conducted for the purpose of evaluating the potential of alternative integrated nuclear fuel cycle options to favorably address the issues associated with a continuing or expanding use of nuclear power in the United States. The study produced information that can be used to inform decisions identifying potential directions for research and development on such fuel cycle options. An integrated nuclear fuel cycle option is defined in this study as including all aspects of the entire nuclear fuel cycle, from obtaining natural resources for fuel to the ultimate disposal of used nuclear fuel (UNF) or radioactive wastes. Issues such as nuclear waste management, especially the increasing inventory of used nuclear fuel, the current uncertainty about used fuel disposal, and the risk of nuclear weapons proliferation have contributed to the reluctance to expand the use of nuclear power, even though it is recognized that nuclear power is a safe and reliable method of producing electricity. In this Options Study, current, evolutionary, and revolutionary nuclear energy options were all considered, including the use of uranium and thorium, and both once-through and recycle approaches. Available information has been collected and reviewed in order to evaluate the ability of an option to clearly address the challenges associated with the current implementation and potential expansion of commercial nuclear power in the United States. This Options Study is a comprehensive consideration and review of fuel cycle and technology options, including those for disposal, and is not constrained by any limitations that may be imposed by economics, technical maturity, past policy, or speculated future conditions. This Phase II report is intended to be used in conjunction with the Phase I report, and much information in that report is not repeated here, although some information has been updated to reflect recent developments. The focus in this Options Study was to

  10. Microstructure evolution in high strength steel for power plant application - Microscopy and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Korcakova, L.

    2002-08-01

    The aim of the work presented in this thesis was to characterise and model microstructure development of 9-12%Cr steels during creep exposure or isothermal ageing at elevated temperatures. 9-12%Cr steels alloyed with W and/or Mo are applied for high-temperature components in advanced fossil-fired power plants because of their superior creep performance. Addition of Mo and W induces precipitation of intermetallic Laves phase during long-term exposure at service temperatures around 600 deg C. The main part of the experimental work focuses on growth and coarsening of Laves phase in 9-12%Cr steels. Laves phase was investigated in three steels with different levels of Cr and W after creep testing or isothermal ageing at 600 deg C or 650 deg C up to 59,000 h. The steels chosen for the investigations were the well-established P92 and P122, which exhibited very stable creep behaviour and the test alloy FN5, which shows breakdown in creep properties during the first 10,000 h of creep exposure. A new scanning electron microscopy (SEM) method for quantification of Laves phase was developed. The method allows discrimination of Laves phase partides from M{sub 22}C{sub 6} carbides based on a difference in their atomic number contrast. The investigations showed that Laves phase in steel P92 and P122 precipitates during creep exposure or isothermal ageing. In steel FN5 two populations of Laves phase partides exist, where one is present after final heat treatment and the second develops during creep exposure. Laves phase in steel P122 was observed to grow faster than in steel P92 and FN5. The final size of Laves phase in steel P122 is smaller than in steel P92 and FN5. M{sub 23}C6 carbides and MX carbo-nitrides were investigated in a sample crept at 600 deg C for 59,000 h using energy filtered transmission electron microscopy (EFTEM). Both partide types were found to be very stable also after long exposure times. Furthermore, transmission electron microscopy (TEM) investigations of

  11. Microstructure evolution in high strength steel for power plant application: microscopy and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Korcakova, L.

    2002-08-01

    The aim of the work presented in this thesis was to characterise and model microstructure development of 9-12%Cr steels during creep exposure or isothermal ageing at elevated temperatures. 9-12%Cr steels alloyed with W and/or Mo are applied for high-temperature components in advanced fossil-fired power plants because of their superior creep performance. Addition of Mo and W induces precipitation of intermetallic Laves phase during long-term exposure at service temperatures around 600 deg. C. The main part of the experimental work focuses on growth and coarsening of Laves phase in 9-12%Cr steels. Laves phase was investigated in three steels with different levels of Cr and W after creep testing or isothermal ageing at 600 deg. C or 650 deg. C up to 59,000 h. The steels chosen for the investigations were the well-established P92 and P122, which exhibited very stable creep behaviour and the test alloy FN5, which shows breakdown in creep properties during the first 10,000 h of creep exposure. A new scanning electron microscopy (SEM) method for quantification of Laves phase was developed. The method allows discrimination of Laves phase particles from M{sub 23}C{sub 6} carbides based on a difference in their atomic number contrast. The investigations showed that Laves phase in steel P92 and P122 precipitates during creep exposure or isothermal ageing. In steel FN5 two populations of Laves phase particles exist, where one is present after final heat treatment and the second develops during creep exposure. Laves phase in steel P122 was observed to grow faster than in steel P92 and FN5. The final size of Laves phase in steel P122 is smaller than in steel P92 and FN5. M{sub 23}C{sub 6} carbides and MX carbo-nitrides were investigated in a sample crept at 600 deg. deg. for 59,000 h using energy filtered transmission electron microscopy (EFTEM). Both particle types were found to be very stable also after long exposure times. Furthermore, transmission electron microscopy (TEM

  12. Phase Detection aided Thermometry for Two-Phase Flow

    Science.gov (United States)

    Takeyama, Mao; Kunugi, Tomoaki; Kawara, Zensaku; Yokomine, Takehiko

    2017-11-01

    Since temperature and void fraction (or phase fraction) are important parameters to characterize and grasp multiphase flow behaviors, various methods have been developed and applied to. However, these multi-phase flow parameters cannot be measured at the same time and position because they need the individual sensor. A new thermometry to detect the phase for two-phase flow and simultaneously measure the liquid/gas temperature with a miniature thermocouple with high temporal-spatial resolutions is developed; this method was named as a phase detection aided thermometry (PDaT). The principle of PDaT is that a miniature (φ25 μm) thermocouple with 10 kHz of the sampling rate is used not only as a thermometer with the high temporal-spatial resolution, but also as an electrical conductance probe as a phase detector. The results of the proof of principle experiments will be presented.

  13. Composite phase-shifting algorithm for absolute phase measurement

    Science.gov (United States)

    Zhang, Song

    2012-11-01

    This paper presents a method to recover absolute phase by using only four images: three phase-shifted patterns and one stair pattern. The stair pattern is designed in such a way that the stair changes are perfectly aligned with the phase jumps, and thus absolute phase can be recovered by referring to the stair pattern. Due to system noises and camera and/or projector blurring, a computational framework is also proposed. Because this technique only requires four fringe images for absolute phase recovery, it has the merit of measurement speed. And since the absolute phase is obtained, this technique is suitable for measuring step-height objects. We have developed a digital fringe projection system to verify the performance of the proposed technique.

  14. Simple Fermionic Model of Deconfined Phases and Phase Transitions

    Science.gov (United States)

    Assaad, F. F.; Grover, Tarun

    2016-10-01

    Using quantum Monte Carlo simulations, we study a series of models of fermions coupled to quantum Ising spins on a square lattice with N flavors of fermions per site for N =1 , 2, and 3. The models have an extensive number of conserved quantities but are not integrable, and they have rather rich phase diagrams consisting of several exotic phases and phase transitions that lie beyond the Landau-Ginzburg paradigm. In particular, one of the prominent phases for N >1 corresponds to 2 N gapless Dirac fermions coupled to an emergent Z2 gauge field in its deconfined phase. However, unlike a conventional Z2 gauge theory, we do not impose "Gauss's Law" by hand; instead, it emerges because of spontaneous symmetry breaking. Correspondingly, unlike a conventional Z2 gauge theory in two spatial dimensions, our models have a finite-temperature phase transition associated with the melting of the order parameter that dynamically imposes the Gauss's law constraint at zero temperature. By tuning a parameter, the deconfined phase undergoes a transition into a short-range entangled phase, which corresponds to Néel antiferromagnet or superconductor for N =2 and a valence-bond solid for N =3 . Furthermore, for N =3 , the valence-bond solid further undergoes a transition to a Néel phase consistent with the deconfined quantum critical phenomenon studied earlier in the context of quantum magnets.

  15. Simple Fermionic Model of Deconfined Phases and Phase Transitions

    Directory of Open Access Journals (Sweden)

    F. F. Assaad

    2016-12-01

    Full Text Available Using quantum Monte Carlo simulations, we study a series of models of fermions coupled to quantum Ising spins on a square lattice with N flavors of fermions per site for N=1, 2, and 3. The models have an extensive number of conserved quantities but are not integrable, and they have rather rich phase diagrams consisting of several exotic phases and phase transitions that lie beyond the Landau-Ginzburg paradigm. In particular, one of the prominent phases for N>1 corresponds to 2N gapless Dirac fermions coupled to an emergent Z_{2} gauge field in its deconfined phase. However, unlike a conventional Z_{2} gauge theory, we do not impose “Gauss’s Law” by hand; instead, it emerges because of spontaneous symmetry breaking. Correspondingly, unlike a conventional Z_{2} gauge theory in two spatial dimensions, our models have a finite-temperature phase transition associated with the melting of the order parameter that dynamically imposes the Gauss’s law constraint at zero temperature. By tuning a parameter, the deconfined phase undergoes a transition into a short-range entangled phase, which corresponds to Néel antiferromagnet or superconductor for N=2 and a valence-bond solid for N=3. Furthermore, for N=3, the valence-bond solid further undergoes a transition to a Néel phase consistent with the deconfined quantum critical phenomenon studied earlier in the context of quantum magnets.

  16. Simulation of Mission Phases

    Science.gov (United States)

    Carlstrom, Nicholas Mercury

    2016-01-01

    This position with the Simulation and Graphics Branch (ER7) at Johnson Space Center (JSC) provided an introduction to vehicle hardware, mission planning, and simulation design. ER7 supports engineering analysis and flight crew training by providing high-fidelity, real-time graphical simulations in the Systems Engineering Simulator (SES) lab. The primary project assigned by NASA mentor and SES lab manager, Meghan Daley, was to develop a graphical simulation of the rendezvous, proximity operations, and docking (RPOD) phases of flight. The simulation is to include a generic crew/cargo transportation vehicle and a target object in low-Earth orbit (LEO). Various capsule, winged, and lifting body vehicles as well as historical RPOD methods were evaluated during the project analysis phase. JSC core mission to support the International Space Station (ISS), Commercial Crew Program (CCP), and Human Space Flight (HSF) influenced the project specifications. The simulation is characterized as a 30 meter +V Bar and/or -R Bar approach to the target object's docking station. The ISS was selected as the target object and the international Low Impact Docking System (iLIDS) was selected as the docking mechanism. The location of the target object's docking station corresponds with the RPOD methods identified. The simulation design focuses on Guidance, Navigation, and Control (GNC) system architecture models with station keeping and telemetry data processing capabilities. The optical and inertial sensors, reaction control system thrusters, and the docking mechanism selected were based on CCP vehicle manufacturer's current and proposed technologies. A significant amount of independent study and tutorial completion was required for this project. Multiple primary source materials were accessed using the NASA Technical Report Server (NTRS) and reference textbooks were borrowed from the JSC Main Library and International Space Station Library. The Trick Simulation Environment and User

  17. On the quantum phase problem

    Energy Technology Data Exchange (ETDEWEB)

    Vargas-MartInez, J M; Moya-Cessa, H [INAOE, Coordinacion de Optica, Apartado Postal 51 y 216, 72000 Puebla (Mexico)

    2004-03-01

    Based on the phase operator introduced by Turski we present a formalism for phase that passes Barnett-Pegg's acid test giving the correct phase variance for a number state. We show that this formalism is in fact the radially integrated Q-function formalism that is used to obtain phase properties. It is also shown that depending on the commutation relation used for phase and number, the phase fluctuations for a coherent state obtained from the integrated Q-function tend to the 1/2{rho}{sup 2} limit while for the Pegg-Barnett formalism they tend to 1/(4{rho}{sup 2}+3/{pi}{sup 2}) just like the fluctuations from the integrated Wigner function, where {rho} is the amplitude of the coherent state00.

  18. Phased Array Feeds

    Science.gov (United States)

    Fisher, J. Richard; Bradley, Richard F.; Brisken, Walter F.; Cotton, William D.; Emerson, Darrel T.; Kerr, Anthony R.; Lacasse, Richard J.; Morgan, Matthew A.; Napier, Peter J.; Norrod, Roger D.; Payne, John M.; Pospieszalski, Marian W.; Symmes, Arthur; Thompson, A. Richard; Webber, John C.

    2009-03-01

    This white paper offers cautionary observations about the planning and development of new, large radio astronomy instruments. Complexity is a strong cost driver so every effort should be made to assign differing science requirements to different instruments and probably different sites. The appeal of shared resources is generally not realized in practice and can often be counterproductive. Instrument optimization is much more difficult with longer lists of requirements, and the development process is longer and less efficient. More complex instruments are necessarily further behind the technology state of the art because of longer development times. Including technology R&D in the construction phase of projects is a growing trend that leads to higher risks, cost overruns, schedule delays, and project de-scoping. There are no technology breakthroughs just over the horizon that will suddenly bring down the cost of collecting area. Advances come largely through careful attention to detail in the adoption of new technology provided by industry and the commercial market. Radio astronomy instrumentation has a very bright future, but a vigorous long-term R&D program not tied directly to specific projects needs to be restored, fostered, and preserved.

  19. Liquid Phase Sintering

    Science.gov (United States)

    2004-01-01

    Industry spends billions of dollars each year on machine tools to manufacture products out of metal. This includes tools for cutting every kind of metal part from engine blocks to Shuttle main engine components. Cutting tool tips often break because of weak spots or defects in their composition. Based on a new concept called defect trapping, space offers a novel environment to study defect formation in molten metal materials as they solidify. After the return of these materials from space, researchers can evaluate the source of the defect and seek ways to eliminate them in products prepared on Earth. A widely used process for cutting tip manufacturing is liquid phase sintering. Compared to Earth-sintered samples which slump due to buoyancy induced by gravity, space samples are uniformly shaped and defects remain where they are formed. By studying metals sintered in space the US tool industry can potentially enhance its worldwide competitiveness. The Consortium for Materials Development in Space along with Wyle Labs, Teledyne Advanced Materials, and McDornell Douglas have conducted experiments in space.

  20. Phase change materials handbook

    Science.gov (United States)

    Hale, D. V.; Hoover, M. J.; Oneill, M. J.

    1971-01-01

    This handbook is intended to provide theory and data needed by the thermal design engineer to bridge the gap between research achievements and actual flight systems, within the limits of the current state of the art of phase change materials (PCM) technology. The relationship between PCM and more conventional thermal control techniques is described and numerous space and terrestrial applications of PCM are discussed. Material properties of the most promising PCMs are provided; the purposes and use of metallic filler materials in PCM composites are presented; and material compatibility considerations relevant to PCM design are included. The engineering considerations of PCM design are described, especially those pertaining to the thermodynamic and heat transfer phenomena peculiar to PCM design. Methods of obtaining data not currently available are presented. The special problems encountered in the space environment are described. Computational tools useful to the designer are discussed. In summary, each aspect of the PCM problem important to the design engineer is covered to the extent allowed by the scope of this effort and the state of the art.

  1. Modern windships. Phase 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-11-01

    Knud E. Hansen A/S (KEH) has, partly funded by the Energy Research Programme, (EFP-95) investigated in the possibilities of using windships for transportation of cargo on long routes, i.e. across the Atlantic or Pacific Ocean. The task was to peruse experiences from projects made during the past 30 years and then, based on new materials and design principle to make proposals to modern wind driven ships to transportation of cargo - especially bulk carriers. KEH has thus prepared a suggestion for a 50,000 DWT wind driven bulk carrier on these terms. The bulk carrier in question is a modern rig inspired by the classical lugger and junk sail with a total sail area of abt. 10,000 m{sup 2}. The hull of the ship has been developed in order to limit wave resistance and drifting. Project Windship has, in contrast to earlier tests and projects, designed a bulk carrier based on a complete evaluation of ecology, safety, economy and reasonable transportation speed. The research project shows that international sea transportation, with wind as the primary source of energy, does not seem to run up against any obstacles as regards safety. The economical analyses show that windship transportation, with today`s oil prices, will be about 10% higher compared to the diesel driven transportation. In the light of the positive results of the research project the steering committee recommends that phase II of project `Modern Windships` is carried out. (EG)

  2. Quantum phases of a qutrit

    Energy Technology Data Exchange (ETDEWEB)

    Klimov, Andrei B [Departamento de FIsica, Universidad de Guadalajara, Revolucion 1500, 44420 Guadalajara, Jalisco (Mexico); Sanchez-Soto, Luis L [Departamento de Optica, Facultad de FIsica, Universidad Complutense, 28040 Madrid (Spain); Guise, Hubert de [Department of Physics, Lakehead University, Thunder Bay, Ontario P7B 5E1 (Canada); Bjoerk, Gunnar [Department of Microelectronics and Information Technology, Royal Institute of Technology (KTH), Electrum 229, SE-164 40 Kista (Sweden)

    2004-04-02

    We consider various approaches to treat the phases of a qutrit. Although it is possible to represent qutrits in a convenient geometrical manner by resorting to a generalization of the Poincare sphere, we argue that the appropriate way of dealing with this problem is through phase operators associated with the algebra su(3). The rather unusual properties of these phases are caused by the small dimension of the system and are explored in detail. We also examine the positive operator-valued measures that can describe the qutrit phase properties.

  3. Diffraction phase and fluorescence microscopy.

    Science.gov (United States)

    Park, Yongkeun; Popescu, Gabriel; Badizadegan, Kamran; Dasari, Ramachandra R; Feld, Michael S

    2006-09-04

    We have developed diffraction phase and fluorescence (DPF) microscopy as a new technique for simultaneous quantitative phase imaging and epi-fluorescence investigation of live cells. The DPF instrument consists of an interference microscope, which is incorporated into a conventional inverted fluorescence microscope. The quantitative phase images are characterized by sub-nanometer optical path-length stability over periods from milliseconds to a cell lifetime. The potential of the technique for quantifying rapid nanoscale motions in live cells is demonstrated by experiments on red blood cells, while the composite phase-fluorescence imaging mode is exemplified with mitotic kidney cells.

  4. Phase transitions in operational risk.

    Science.gov (United States)

    Anand, Kartik; Kühn, Reimer

    2007-01-01

    In this paper we explore the functional correlation approach to operational risk. We consider networks with heterogeneous a priori conditional and unconditional failure probability. In the limit of sparse connectivity, self-consistent expressions for the dynamical evolution of order parameters are obtained. Under equilibrium conditions, expressions for the stationary states are also obtained. Consequences of the analytical theory developed are analyzed using phase diagrams. We find coexistence of operational and nonoperational phases, much as in liquid-gas systems. Such systems are susceptible to discontinuous phase transitions from the operational to nonoperational phase via catastrophic breakdown. We find this feature to be robust against variation of the microscopic modeling assumptions.

  5. Quantum optics in phase space

    CERN Document Server

    Schleich, W P; Mayr, E

    1998-01-01

    Quantum Optics in Phase Space provides a concise introduction to the rapidly moving field of quantum optics from the point of view of phase space. Modern in style and didactically skillful, Quantum Optics in Phase Space prepares students for their own research by presenting detailed derivations, many illustrations and a large set of workable problems at the end of each chapter. Often, the theoretical treatments are accompanied by the corresponding experiments. An exhaustive list of references provides a guide to the literature. Quantum Optics in Phase Space also serves advanced researchers as

  6. Phase error correction in wavefront curvature sensing via phase retrieval

    DEFF Research Database (Denmark)

    Almoro, Percival; Hanson, Steen Grüner

    2008-01-01

    Wavefront curvature sensing with phase error correction system is carried out using phase retrieval based on a partially-developed volume speckle field. Various wavefronts are reconstructed: planar, spherical, cylindrical, and a wavefront passing through the side of a bare optical fiber. Spurious...

  7. UAVSAR Phased Array Aperture

    Science.gov (United States)

    Chamberlain, Neil; Zawadzki, Mark; Sadowy, Greg; Oakes, Eric; Brown, Kyle; Hodges, Richard

    2009-01-01

    This paper describes the development of a patch antenna array for an L-band repeat-pass interferometric synthetic aperture radar (InSAR) instrument that is to be flown on an unmanned aerial vehicle (UAV). The antenna operates at a center frequency of 1.2575 GHz and with a bandwidth of 80 MHz, consistent with a number of radar instruments that JPL has previously flown. The antenna is designed to radiate orthogonal linear polarizations in order to facilitate fully-polarimetric measurements. Beam-pointing requirements for repeat-pass SAR interferometry necessitate electronic scanning in azimuth over a range of -20degrees in order to compensate for aircraft yaw. Beam-steering is accomplished by transmit/receive (T/R) modules and a beamforming network implemented in a stripline circuit board. This paper, while providing an overview of phased array architecture, focuses on the electromagnetic design of the antenna tiles and associated interconnects. An important aspect of the design of this antenna is that it has an amplitude taper of 10dB in the elevation direction. This is to reduce multipath reflections from the wing that would otherwise be detrimental to interferometric radar measurements. This taper is provided by coupling networks in the interconnect circuits as opposed to attenuating the output of the T/R modules. Details are given of material choices and fabrication techniques that meet the demanding environmental conditions that the antenna must operate in. Predicted array performance is reported in terms of co-polarized and crosspolarized far-field antenna patterns, and also in terms of active reflection coefficient.

  8. Multiphase flows with phase change

    Indian Academy of Sciences (India)

    Multiphase flows with phase change are ubiquitous in many industrial sectors ranging from energy and infra-structure to specialty chemicals and pharmaceuticals. My own interest in mul- tiphase flows with phase change started more than 15 years ago when I had initiated work on riser reactor for fluid catalytic cracking and ...

  9. Modulational instability of nematic phase

    Indian Academy of Sciences (India)

    2014-02-08

    Feb 8, 2014 ... Abstract. We numerically observe the effect of homogeneous magnetic field on the modulation- ally stable case of polar phase in F = 2 spinor Bose–Einstein condensates (BECs). Also we investigate the modulational instability of uniaxial and biaxial (BN) states of polar phase. Our observations show that ...

  10. Modulational instability of nematic phase

    Indian Academy of Sciences (India)

    2014-02-08

    Feb 8, 2014 ... We numerically observe the effect of homogeneous magnetic field on the modulationally stable case of polar phase in = 2 spinor Bose–Einstein condensates (BECs). Also we investigate the modulational instability of uniaxial and biaxial (BN) states of polar phase. Our observations show that the magnetic ...

  11. Stepped-impedance phase shifters

    CERN Document Server

    Faltin, L

    1977-01-01

    A coupled-line phase shifter can be decomposed in two lines of stepped characteristic impedances, interconnected by a 180 degrees hybrid. This network permits phase responses which cannot be realised with coupled lines. Practical simplifications are possible by omitting one of the two lines or by using a 90 degrees hybrid. (5 refs).

  12. Phase sensitive scanning optical microscope

    Energy Technology Data Exchange (ETDEWEB)

    Jungerman, R.L.; Hobbs, P.C.D.; Kino, G.S.

    1984-10-15

    An electronically scanned optical microscope which quantitatively measures amplitude and phase is described. The system is insenstive to mechanical vibrations. The phase infromation makes it possible to measure surface height variations with an accuracy of better than 100 A and can also be used to improve the lateral resolution.

  13. Phase diagrams for sonoluminescing bubbles

    NARCIS (Netherlands)

    Hilgenfeldt, Sascha; Lohse, Detlef; Brenner, Michael P.

    1996-01-01

    Sound driven gas bubbles in water can emit light pulses. This phenomenon is called sonoluminescence (SL). Two different phases of single bubble SL have been proposed: diffusively stable and diffusively unstable SL. We present phase diagrams in the gas concentration versus forcing pressure state

  14. A transmission line phase stabilizer

    Science.gov (United States)

    Lutes, G. F.

    1979-01-01

    To meet the phase stability requirements of certain experiments performed with the Deep Space Network, transmission lines carrying reference signals must be stabilized to reduce changes in their electrical length due to mechanical movement or changes in ambient temperature. A transmission line phase stabilizer being developed at JPL to perform this function is described.

  15. Phase-sensitive flow cytometer

    Energy Technology Data Exchange (ETDEWEB)

    Steinkamp, J.A.

    1992-12-31

    This report describes phase-sensitive flow cytometer (FCM) which provides additional FCM capability to use the fluorescence lifetime of one or more fluorochromes bound to single cells to provide additional information regarding the cells. The resulting fluorescence emission can be resolved into individual fluorescence signals if two fluorochromes are present or can be converted directly to a decay lifetime from a single fluorochrome. The excitation light for the fluorochromes is modulated to produce an amplitude modulated fluorescence pulse as the fluorochrome is excited in the FCM. The modulation signal also forms a reference signal that is phase-shifted a selected amount for subsequent mixing with the output modulated fluorescence intensity signal in phase-sensitive detection circuitry. The output from the phase-sensitive circuitry is then an individual resolved fluorochrome signal or a single fluorochrome decay lifetime, depending on the applied phase shifts.

  16. Solid phase protein chemical synthesis.

    Science.gov (United States)

    Raibaut, Laurent; El Mahdi, Ouafâa; Melnyk, Oleg

    2015-01-01

    The chemical synthesis of peptides or small proteins is often an important step in many research projects and has stimulated the development of numerous chemical methodologies. The aim of this review is to give a substantial overview of the solid phase methods developed for the production or purification of polypeptides. The solid phase peptide synthesis (SPPS) technique has facilitated considerably the access to short peptides (peptides have stimulated the development of solid phase covalent or non-covalent capture purification methods. The power of the native chemical ligation (NCL) reaction for protein synthesis in aqueous solution has also been adapted to the solid phase by the combination of novel linker technologies, cysteine protection strategies and thioester or N,S-acyl shift thioester surrogate chemistries. This review details pioneering studies and the most recent publications related to the solid phase chemical synthesis of large peptides and proteins.

  17. Quantitative phase imaging using grating-based quadrature phase interferometer

    Science.gov (United States)

    Wu, Jigang; Yaqoob, Zahid; Heng, Xin; Cui, Xiquan; Yang, Changhuei

    2007-02-01

    In this paper, we report the use of holographic gratings, which act as the free-space equivalent of the 3x3 fiber-optic coupler, to perform full field phase imaging. By recording two harmonically-related gratings in the same holographic plate, we are able to obtain nontrivial phase shift between different output ports of the gratings-based Mach-Zehnder interferometer. The phase difference can be adjusted by changing the relative phase of the recording beams when recording the hologram. We have built a Mach-Zehnder interferometer using harmonically-related holographic gratings with 600 and 1200 lines/mm spacing. Two CCD cameras at the output ports of the gratings-based Mach-Zehnder interferometer are used to record the full-field quadrature interferograms, which are subsequently processed to reconstruct the phase image. The imaging system has ~12X magnification with ~420μmx315μm field-of-view. To demonstrate the capability of our system, we have successfully performed phase imaging of a pure phase object and a paramecium caudatum.

  18. On the solid–liquid phase diagrams of binary mixtures of even saturated fatty alcohols: Systems exhibiting peritectic reaction

    Energy Technology Data Exchange (ETDEWEB)

    Carareto, Natália D.D. [EXTRAE, Department of Food Engineering, Food Engineering Faculty, University of Campinas, UNICAMP, CEP 13083-862 Campinas, SP (Brazil); Santos, Adenílson O. dos [Social Sciences, Health and Technology Center, University of Maranhão, UFMA, CEP 65900-410 Imperatriz, MA (Brazil); Rolemberg, Marlus P. [Institute of Science and Technology, University of Alfenas, UNIFAL, Rodovia José AurélioVilela, CEP 37715400 Poços de Caldas, MG (Brazil); Cardoso, Lisandro P. [Institute of Physics GlebWataghin, University of Campinas, UNICAMP, C.P. 6165, CEP 13083-970 Campinas, SP (Brazil); Costa, Mariana C. [School of Applied Science, University of Campinas, UNICAMP, CEP 13484-350 Limeira, SP (Brazil); Meirelles, Antonio J.A., E-mail: tomze@fea.unicamp.br [EXTRAE, Department of Food Engineering, Food Engineering Faculty, University of Campinas, UNICAMP, CEP 13083-862 Campinas, SP (Brazil)

    2014-08-10

    Highlights: • SLE of binary mixtures of saturated fatty alcohols was studied. • Experimental data were obtained using DSC and stepscan DSC. • Microscopy and X-ray diffraction used as complementary techniques. • Systems presented eutectic, peritectic and metatectic points. - Abstract: The solid–liquid phase diagrams of the following binary mixtures of even saturated fatty alcohols are reported in the literature for the first time: 1-octanol (C8OH) + 1-decanol (C10OH), 1-decanol + 1-dodecanol (C12OH), 1-dodecanol + 1-hexadecanol (C16OH) and 1-tetradecanol (C14OH) + 1-octadecanol (C18OH). The phase diagrams were obtained by differential scanning calorimetry (DSC) using a linear heating rate of 1 K min{sup −1} and further investigated by using a stepscan DSC method. X-ray diffraction (XRD) and polarized light microscopy were also used to complement the characterization of the phase diagrams which have shown a complex global behavior, presenting not only peritectic and eutectic reactions, but also the metatectic reaction and partial immiscibility on solid state.

  19. Phase Noise and Phase Modulation in Optical Coherence Tomography

    Science.gov (United States)

    Parrein, Pascale; Meier, Joachim

    2004-05-01

    The signal in optical coherence tomography is often modulated either in phase or by use of the Doppler modulation generated by a depth-scanning mechanism. The effect of each type of modulation on the signal's amplitude is evaluated. The advantages of each type of modulation in terms of immunity to phase noise and penetration depth are discussed in relation to two envelope detection schemes, i.e., lock-in detection and rms-to-dc conversion. Phase noise due to drifts and demodulation instabilities causes distortion of the signal envelope and can be responsible in part for the speckle appearance of the image.

  20. Gas hydrate phase equilibria measurement techniques and phase rule considerations

    Energy Technology Data Exchange (ETDEWEB)

    Beltran, Juan G. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, ON (Canada); Bruusgaard, Hallvard [Department of Chemical Engineering, McGill University, Montreal, QC (Canada); Servio, Phillip, E-mail: phillip.servio@mcgill.ca [Department of Chemical Engineering, McGill University, Montreal, QC (Canada)

    2012-01-15

    Highlights: > Inconsistencies found in hydrate literature. > Clarification to the number of variables needed to satisfy and justify equilibrium data. > Application of phase rule to mixed hydrate systems. > Thermodynamically consistent format to present data. - Abstract: A brief review of the Gibbs phase rule for non-reacting systems and its correct application to clathrate hydrates is presented. Clarification is provided for a common mistake found in hydrate phase-equilibria literature, whereby initial compositions are used as intensive variables to satisfy the Gibbs phase rule instead of the equilibrium values. The system of (methane + carbon dioxide + water) under (hydrate + liquid + vapor) equilibrium is used as a case study to illustrate key points and suggestions to improve experimental techniques are proposed.

  1. Anisotropies of in-phase, out-of-phase,\

    Czech Academy of Sciences Publication Activity Database

    Hrouda, F.; Chadima, Martin; Ježek, J.; Kadlec, Jaroslav

    2018-01-01

    Roč. 62 (2018) ISSN 0039-3169 Institutional support: RVO:67985530 ; RVO:67985831 Keywords : anisotropy * out-of-phase susceptibility * frequency-dependent susceptibility Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.764, year: 2016

  2. Equilibrium Statistical Physics Phases of Matter and Phase Transitions

    CERN Document Server

    Baus, Marc

    2008-01-01

    This is a textbook which gradually introduces the student to the statistical mechanical study of the different phases of matter and to the phase transitions between them. Throughout, only simple models of both ordinary and soft matter are used but these are studied in full detail. The subject is developed in a pedagogical manner, starting from the basics, going from the simple ideal systems to the interacting systems, and ending with the more modern topics. The latter include the renormalisation group approach to critical phenomena, the density functional theory of interfaces, the topological defects of nematic liquid crystals and the kinematic aspects of the phase transformation process. This textbook provides the student with a complete overview, intentionally at an introductory level, of the theory of phase transitions. References include suggestions for more detailed treatments and four appendices supply overviews of the mathematical tools employed in the text.

  3. Phase Noise Tolerant QPSK Receiver Using Phase Sensitive Wavelength Conversion

    DEFF Research Database (Denmark)

    Da Ros, Francesco; Xu, Jing; Lei, Lei

    2013-01-01

    A novel QPSK receiver based on a phase noise reduction pre-stage exploiting PSA in a HNLF and balanced detection is presented. Receiver sensitivity improvement over a conventional balanced receiver is demonstrated.......A novel QPSK receiver based on a phase noise reduction pre-stage exploiting PSA in a HNLF and balanced detection is presented. Receiver sensitivity improvement over a conventional balanced receiver is demonstrated....

  4. Phase Behavior and Implications for Travel time Observables (PHASE 2)

    Science.gov (United States)

    2015-09-30

    Phase behavior and implications for travel - time observables (PHASE-2) Emmanuel Skarsoulis Foundation for Research and Technology Hellas...perturbation behavior of travel time observables due to sound-speed perturbations. OBJECTIVES The objective is to study the behavior of the wave-theoretic...for this work came from the results of previous studies, supported by ONR, suggesting that the perturbation behavior of different travel - time

  5. Pulse Dispersion in Phased Arrays

    Directory of Open Access Journals (Sweden)

    Randy L. Haupt

    2017-01-01

    Full Text Available Phased array antennas cause pulse dispersion when receiving or transmitting wideband signals, because phase shifting the signals does not align the pulse envelopes from the elements. This paper presents two forms of pulse dispersion that occur in a phased array antenna. The first results from the separation distance between the transmit and receive antennas and impacts the definition of far field in the time domain. The second is a function of beam scanning and array size. Time delay units placed at the element and/or subarrays limit the pulse dispersion.

  6. Fundamentals of ultrasonic phased arrays

    CERN Document Server

    Schmerr, Lester W

    2014-01-01

    This book describes in detail the physical and mathematical foundations of ultrasonic phased array measurements.?The book uses linear systems theory to develop a comprehensive model of the signals and images that can be formed with phased arrays. Engineers working in the field of ultrasonic nondestructive evaluation (NDE) will find in this approach a wealth of information on how to design, optimize and interpret ultrasonic inspections with phased arrays. The fundamentals and models described in the book will also be of significant interest to other fields, including the medical ultrasound and

  7. SNMR pulse sequence phase cycling

    Science.gov (United States)

    Walsh, David O; Grunewald, Elliot D

    2013-11-12

    Technologies applicable to SNMR pulse sequence phase cycling are disclosed, including SNMR acquisition apparatus and methods, SNMR processing apparatus and methods, and combinations thereof. SNMR acquisition may include transmitting two or more SNMR pulse sequences and applying a phase shift to a pulse in at least one of the pulse sequences, according to any of a variety cycling techniques. SNMR processing may include combining SNMR from a plurality of pulse sequences comprising pulses of different phases, so that desired signals are preserved and indesired signals are canceled.

  8. TEM characterization of microstructure evolution of 12%Cr heat resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Rojas, D.; Prat, O.; Sauthoff, G. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany); Garcia, J. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Kaysser-Pyzalla, A.R. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Bochum Univ. (Germany)

    2010-07-01

    A detailed characterization of the microstructure evolution of 12%Cr heat resistant steels at different creep times (100 MPa / 650 C / 8000 h) were carried out by scanning transmission electron microscopy (STEM). The results of the microstructure analysis are correlated with the mechanical properties in order to investigate the influence of different precipitates (especially M{sub 23}C{sub 6}) on the creep strength of the alloys. Precipitation of Laves phase and Z-phase was observed after several hours creep time. Very few Z-phase of the type Cr(V,Ta)N nucleating from existing (V,Ta)(C,N) was observed. Both alloys show growth and coarsening of Laves phase, meanwhile the MX carbonitrides present a very slow growth and coarsening rate. Alloys containing Laves phase, MX and M{sub 23}C{sub 6} precipitates show best creep properties. (orig.)

  9. Design and characterization of microstructure evolution during creep of 12% Cr heat resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Rojas, D. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Str. 1, 40237 Duesseldorf (Germany); Garcia, J., E-mail: jose.garcia@helmholtz-berlin.de [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Prat, O. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Str. 1, 40237 Duesseldorf (Germany); Carrasco, C. [Universidad de Concepcion, Departamento de Ingenieria de Materiales, Edmundo Larenas 270, Concepcion (Chile); Sauthoff, G. [Max Planck Institute fuer Eisenforschung GmbH, Max Planck Str. 1, 40237 Duesseldorf (Germany); Kaysser-Pyzalla, A.R. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Ruhr Universitaet Bochum, Universitaetstr. 150 IA2, 44780 Bochum (Germany)

    2010-06-25

    12% Cr heat resistant steels with a fine dispersion of nano precipitates were designed supported by thermodynamic modeling. A detailed characterization of the microstructure evolution at different creep times (100 MPa/650 deg. C/8000 h) was carried out by scanning transmission electron microscopy (STEM). The results of the microstructure analysis are correlated with the mechanical properties in order to investigate the influence of different precipitates (especially M{sub 23}C{sub 6}) on the creep strength of the alloys. Precipitation of Laves phase and Z-phase was observed after several hours creep time. Very few Z-phase of the type Cr(V,Ta)N nucleating from existing (V,Ta)(C,N) was observed. Both alloys show growth and coarsening of Laves phase, meanwhile the MX carbonitrides present a very slow growth and coarsening rate. Alloys containing Laves phase, MX and M{sub 23}C{sub 6} precipitates show best creep properties.

  10. Phase Coexistence in Insect Swarms

    Science.gov (United States)

    Sinhuber, Michael; Ouellette, Nicholas T.

    2017-10-01

    Animal aggregations are visually striking, and as such are popular examples of collective behavior in the natural world. Quantitatively demonstrating the collective nature of such groups, however, remains surprisingly difficult. Inspired by thermodynamics, we applied topological data analysis to laboratory insect swarms and found evidence for emergent, material-like states. We show that the swarms consist of a core "condensed" phase surrounded by a dilute "vapor" phase. These two phases coexist in equilibrium, and maintain their distinct macroscopic properties even though individual insects pass freely between them. We further define a pressure and chemical potential to describe these phases, extending theories of active matter to aggregations of macroscopic animals and laying the groundwork for a thermodynamic description of collective animal groups.

  11. Weak Coupling Phases future directions

    CERN Document Server

    Rosner, Jonathan L.

    2003-01-01

    Recent results obtained from B decays on the phases of weak couplings described by the Cabibbo-Kobayashi-Maskawa (CKM) matrix are discussed, with particular emphasis on $\\alpha$ and $\\gamma = \\pi - \\beta - \\alpha$.

  12. SGA Phase 2 Assessed Reaches

    Data.gov (United States)

    Vermont Center for Geographic Information — The stream geomorphic assessment (SGA) is a physical assessment competed by geomorphologists to determine the condition and sensitivity of a stream. The Phase 2 SGA...

  13. SGA Phase 1 Assessed Reaches

    Data.gov (United States)

    Vermont Center for Geographic Information — The stream geomorphic assessment (SGA) is a physical assessment competed by geomorphologists to determine the condition and sensitivity of a stream. The Phase 1 SGA...

  14. Liquid Phase Equilibria for Habitability

    Science.gov (United States)

    Tan, S. P.

    2017-11-01

    The existence of liquid phase, which amplifies habitability, can be predicted using an equation of state from atmospheric composition, pressure, and temperature. If solid is also present, density inversion that keeps liquid from freezing is examined.

  15. Fly Photoreceptors Encode Phase Congruency.

    Directory of Open Access Journals (Sweden)

    Uwe Friederich

    Full Text Available More than five decades ago it was postulated that sensory neurons detect and selectively enhance behaviourally relevant features of natural signals. Although we now know that sensory neurons are tuned to efficiently encode natural stimuli, until now it was not clear what statistical features of the stimuli they encode and how. Here we reverse-engineer the neural code of Drosophila photoreceptors and show for the first time that photoreceptors exploit nonlinear dynamics to selectively enhance and encode phase-related features of temporal stimuli, such as local phase congruency, which are invariant to changes in illumination and contrast. We demonstrate that to mitigate for the inherent sensitivity to noise of the local phase congruency measure, the nonlinear coding mechanisms of the fly photoreceptors are tuned to suppress random phase signals, which explains why photoreceptor responses to naturalistic stimuli are significantly different from their responses to white noise stimuli.

  16. CLIC Drive Beam Phase Stabilisation

    CERN Document Server

    Gerbershagen, Alexander; Schulte, Daniel

    The thesis presents phase stability studies for the Compact Linear Collider (CLIC) and focuses in particular on CLIC Drive Beam longitudinal phase stabilisation. This topic constitutes one of the main feasibility challenges for CLIC construction and is an essential component of the current CLIC stabilisation campaign. The studies are divided into two large interrelated sections: the simulation studies for the CLIC Drive Beam stability, and measurements, data analysis and simulations of the CLIC Test Facility (CTF3) Drive Beam phase errors. A dedicated software tool has been developed for a step-by-step analysis of the error propagation through the CLIC Drive Beam. It uses realistic RF potential and beam loading amplitude functions for the Drive and Main Beam accelerating structures, complete models of the recombination scheme and compressor chicane as well as of further CLIC Drive Beam modules. The tool has been tested extensively and its functionality has been verified. The phase error propagation at CLIC h...

  17. Non-equilibrium phase transitions

    CERN Document Server

    Henkel, Malte; Lübeck, Sven

    2009-01-01

    This book describes two main classes of non-equilibrium phase-transitions: (a) static and dynamics of transitions into an absorbing state, and (b) dynamical scaling in far-from-equilibrium relaxation behaviour and ageing. The first volume begins with an introductory chapter which recalls the main concepts of phase-transitions, set for the convenience of the reader in an equilibrium context. The extension to non-equilibrium systems is made by using directed percolation as the main paradigm of absorbing phase transitions and in view of the richness of the known results an entire chapter is devoted to it, including a discussion of recent experimental results. Scaling theories and a large set of both numerical and analytical methods for the study of non-equilibrium phase transitions are thoroughly discussed. The techniques used for directed percolation are then extended to other universality classes and many important results on model parameters are provided for easy reference.

  18. Phase holograms in polymethyl methacrylate

    Science.gov (United States)

    Maker, P. D.; Muller, R. E.

    1992-01-01

    A procedure is described for the fabrication of complex computer-generated phase holograms in polymethyl methacrylate (PMMA) by means of partial-exposure e-beam lithography and subsequent carefully controlled partial development. Following the development, the pattern appears (rendered in relief) in the PMMA, which then acts as the phase-delay medium. The devices fabricated were designed with 16 equal phase steps per retardation cycle, were up to 3 mm square, and consisted of up to 10 millions of 0.3-2.0-micron square pixels. Data files were up to 60 Mb-long, and the exposure times ranged to several hours. A Fresnel phase lens was fabricated with a diffraction-limited optical performance of 83-percent efficiency.

  19. Multiobjective Optimization and Phase Transitions

    CERN Document Server

    Seoane, Luís F

    2015-01-01

    Many complex systems obey to optimality conditions that are usually not simple. Conflicting traits often interact making a Multi Objective Optimization (MOO) approach necessary. Recent MOO research on complex systems report about the Pareto front (optimal designs implementing the best trade-off) in a qualitative manner. Meanwhile, research on traditional Simple Objective Optimization (SOO) often finds phase transitions and critical points. We summarize a robust framework that accounts for phase transitions located through SOO techniques and indicates what MOO features resolutely lead to phase transitions. These appear determined by the shape of the Pareto front, which at the same time is deeply related to the thermodynamic Gibbs surface. Indeed, thermodynamics can be written as an MOO from where its phase transitions can be parsimoniously derived; suggesting that the similarities between transitions in MOO-SOO and Statistical Mechanics go beyond mere coincidence.

  20. The Generalised Phase Contrast Method

    DEFF Research Database (Denmark)

    Glückstad, Jesper

    An analytic framework and a complete description for the design and optimisation of on-axis centred spatially filtering common path systems are presented. The Generalised Phase Contrast method is derived and introduced as the common denominator for these systems basically extending Zernike......’s original phase contrast scheme into a much wider range of operation and application. It is demonstrated that the Generalised Phase Contrast method can be successfully applied to the interpretation and subsequent optimisation of a number of different, commonly applied spatially filtering architectures...... designs and parameter settings. Finally, a number of original applications facilitated by the parallel light-beam encoding of the Generalised Phase Contrast method are briefly outlined. These include among others, wavefront sensing and generation, advanced usercontrolled optical micro...

  1. APPARATUS FOR LIQUID PHASE EXTRACTION

    Science.gov (United States)

    Hicks, T.R.; Lehman, H.R.; Rubin, B.

    1958-09-16

    operation is described. It comprises a tubular colunm having upper and lower enlarged terminal portions, and a constricted central section containing fluid dispersal packing. Pulsing means are coupled to the upper portion of the column. The inlet for the less dense phase is located above the inlet for the denser phase and both are positioned so that liquids enter the constricted packingfilled central section. The apparatos also includes an interfacing level control, and means fer sensing the level of the interface actuate apparatus for controlling the rate of flow of input or discharge. The outlet for the less dense phase is located in the upper packing free portion of the colunm and that of the denser phase in the lower portion.

  2. Gas-phase chemical dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Weston, R.E. Jr.; Sears, T.J.; Preses, J.M. [Brookhaven National Laboratory, Upton, NY (United States)

    1993-12-01

    Research in this program is directed towards the spectroscopy of small free radicals and reactive molecules and the state-to-state dynamics of gas phase collision, energy transfer, and photodissociation phenomena. Work on several systems is summarized here.

  3. Liquid-phase combinatorial synthesis.

    OpenAIRE

    Han, H; Wolfe, M M; Brenner, S; Janda, K D

    1995-01-01

    A concept termed liquid-phase combinatorial synthesis (LPCS) is described. The central feature of this methodology is that it combines the advantages that classic organic synthesis in solution offers with those that solid-phase synthesis can provide, through the application of a linear homogeneous polymer. To validate this concept two libraries were prepared, one of peptide and the second of nonpeptide origin. The peptide-based library was synthesized by a recursive deconvolution strategy [Er...

  4. Gait phase varies over velocities.

    Science.gov (United States)

    Liu, Yancheng; Lu, Kun; Yan, Songhua; Sun, Ming; Lester, D Kevin; Zhang, Kuan

    2014-02-01

    We sought to characterize the percent (PT) of the phases of a gait cycle (GC) as velocity changes to establish norms for pathological gait characteristics with higher resolution technology. Ninety five healthy subjects (49 males and 46 females with age 34.9 ± 11.8 yrs, body weight 64.0 ± 11.7 kg and BMI 23.5 ± 3.6) were enrolled and walked comfortably on a 10-m walkway at self-selected slower, normal, and faster velocities. Walking was recorded with a high speed camera (250 frames per second) and the eight phases of a GC were determined by examination of individual frames for each subject. The correlation coefficients between the mean PT of the phases of the three velocities gaits and PT defined by previous publications were all greater than 0.99. The correlation coefficient between velocity and PT of gait phases is -0.83 for loading response (LR), -0.75 for mid stance (MSt), and -0.84 for pre-swing (PSw). While the PT of the phases of three velocities from this study are highly correlated with PT described by Dr. Jacquenlin Perry decades ago, actual PT of each phase varied amongst these individuals with the largest coefficient variation of 24.31% for IC with slower velocity. From slower to faster walk, the mean PT of MSt diminished from 35.30% to 25.33%. High resolution recording revealed ambiguity of some gait phase definitions, and these data may benefit GC characterization of normal and pathological gait in clinical practice. The study results indicate that one should consider individual variations and walking velocity when evaluating gaits of subjects using standard gait phase classification. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Interfacial phase-change memory.

    Science.gov (United States)

    Simpson, R E; Fons, P; Kolobov, A V; Fukaya, T; Krbal, M; Yagi, T; Tominaga, J

    2011-07-03

    Phase-change memory technology relies on the electrical and optical properties of certain materials changing substantially when the atomic structure of the material is altered by heating or some other excitation process. For example, switching the composite Ge(2)Sb(2)Te(5) (GST) alloy from its covalently bonded amorphous phase to its resonantly bonded metastable cubic crystalline phase decreases the resistivity by three orders of magnitude, and also increases reflectivity across the visible spectrum. Moreover, phase-change memory based on GST is scalable, and is therefore a candidate to replace Flash memory for non-volatile data storage applications. The energy needed to switch between the two phases depends on the intrinsic properties of the phase-change material and the device architecture; this energy is usually supplied by laser or electrical pulses. The switching energy for GST can be reduced by limiting the movement of the atoms to a single dimension, thus substantially reducing the entropic losses associated with the phase-change process. In particular, aligning the c-axis of a hexagonal Sb(2)Te(3) layer and the 〈111〉 direction of a cubic GeTe layer in a superlattice structure creates a material in which Ge atoms can switch between octahedral sites and lower-coordination sites at the interface of the superlattice layers. Here we demonstrate GeTe/Sb(2)Te(3) interfacial phase-change memory (IPCM) data storage devices with reduced switching energies, improved write-erase cycle lifetimes and faster switching speeds.

  6. Phase difference of arrival geolocation

    Science.gov (United States)

    Mason, John J.; Romero, Louis (

    2017-05-16

    Geolocation is performed by receiving, at a plurality of non-earthbound platforms each moving in a known manner within a spatial coordinate system, a radio frequency (RF) signal transmitted from a transmitter at an unknown location on earth within the spatial coordinate system. For each of the platforms, a phase change of the received frequency carrier is measured over the same duration of time. The measured phase changes are combined to determine the transmitter location.

  7. Griffiths phase and temporal effects in phase separated manganites

    Energy Technology Data Exchange (ETDEWEB)

    Krivoruchko, V.N., E-mail: krivoruc@krivoruc.fti.ac.donetsk.ua; Marchenko, M.A.

    2016-08-15

    Phenomenological description of relaxation phenomena in magnetic and transport properties of perovskite manganites has been presented. The approach is based on generalization of some hypotheses appropriate to the Preisach picture of magnetization process for half-metallic ferromagnets and on an assumption that in doped manganites the phase separated state exists near the magnetic ordering temperature. For systems with the percolation type of a ferromagnet–paramagnet transition, distinctive features in relaxation of magnetization and resistivity have been found. The relaxation is shown to be most pronounced near the transition temperature, and to be an approximately logarithmic function of time. The theoretical results replicate a broad spectrum of behavior observed experimentally on time dependence of magnetization and resistivity of CMR systems and allow a direct comparison with available experimental data. We propose an additional experimental test to distinguish between the percolation scenario of magnetic and transport transitions in doped manganites, and the ferromagnetic polaron picture. In particular, an anomalously slow relaxation to zero of the order parameter can be considered as a key feature of the Griffiths-like phase transition in doped manganites. It is also shown that a system with the Griffiths-like state will exhibit nonequilibrium aging and rejuvenation phenomena, which in many aspects resemble that of a spin glass. We hope that experimental observation of a set of time decay properties will provide a settlement of apparently conflicting results obtained for different characteristics of phase-separated manganites. - Graphical abstract: Temperature dependence of the FC and ZFC magnetization response upon warming in magnetic field at different sweeping rates: (a) a system with the conventional (second order) ferromagnet–paramagnet phase transition and (b) a system with the Griffiths-like phase above the magnetic ordering temperature

  8. Learning phase transitions by confusion

    Science.gov (United States)

    van Nieuwenburg, Evert P. L.; Liu, Ye-Hua; Huber, Sebastian D.

    2017-02-01

    Classifying phases of matter is key to our understanding of many problems in physics. For quantum-mechanical systems in particular, the task can be daunting due to the exponentially large Hilbert space. With modern computing power and access to ever-larger data sets, classification problems are now routinely solved using machine-learning techniques. Here, we propose a neural-network approach to finding phase transitions, based on the performance of a neural network after it is trained with data that are deliberately labelled incorrectly. We demonstrate the success of this method on the topological phase transition in the Kitaev chain, the thermal phase transition in the classical Ising model, and the many-body-localization transition in a disordered quantum spin chain. Our method does not depend on order parameters, knowledge of the topological content of the phases, or any other specifics of the transition at hand. It therefore paves the way to the development of a generic tool for identifying unexplored phase transitions.

  9. Phases and phase transitions in the algebraic microscopic shell model

    Directory of Open Access Journals (Sweden)

    Georgieva A. I.

    2016-01-01

    Full Text Available We explore the dynamical symmetries of the shell model number conserving algebra, which define three types of pairing and quadrupole phases, with the aim to obtain the prevailing phase or phase transition for the real nuclear systems in a single shell. This is achieved by establishing a correspondence between each of the pairing bases with the Elliott’s SU(3 basis that describes collective rotation of nuclear systems. This allows for a complete classification of the basis states of different number of particles in all the limiting cases. The probability distribution of the SU(3 basis states within theirs corresponding pairing states is also obtained. The relative strengths of dynamically symmetric quadrupole-quadrupole interaction in respect to the isoscalar, isovector and total pairing interactions define a control parameter, which estimates the importance of each term of the Hamiltonian in the correct reproduction of the experimental data for the considered nuclei.

  10. Dynamic Modeling of Phase Crossings in Two-Phase Flow

    DEFF Research Database (Denmark)

    Madsen, Søren; Veje, Christian; Willatzen, Morten

    2012-01-01

    Two-phase flow and heat transfer, such as boiling and condensing flows, are complicated physical phenomena that generally prohibit an exact solution and even pose severe challenges for numerical approaches. If numerical solution time is also an issue the challenge increases even further. We present...... of the variables and are usually very slow to evaluate. To overcome these challenges, we use an interpolation scheme with local refinement. The simulations show that the method handles crossing of the saturation lines for both liquid to two-phase and two-phase to gas regions. Furthermore, a novel result obtained...... in this work, the method is stable towards dynamic transitions of the inlet/outlet boundaries across the saturation lines. Results for these cases are presented along with a numerical demonstration of conservation of mass under dynamically varying boundary conditions. Finally we present results...

  11. Phase Correction for GPS Antenna with Nonunique Phase Center

    Science.gov (United States)

    Fink, Patrick W.; Dobbins, Justin

    2005-01-01

    A method of determining the position and attitude of a body equipped with a Global Positioning System (GPS) receiver includes an accounting for the location of the nonunique phase center of a distributed or wraparound GPS antenna. The method applies, more specifically, to the case in which (1) the GPS receiver utilizes measurements of the phases of GPS carrier signals in its position and attitude computations and (2) the body is axisymmetric (e.g., spherical or round cylindrical) and wrapped at its equator with a single- or multiple-element antenna, the radiation pattern of which is also axisymmetric with the same axis of symmetry as that of the body.

  12. Phases of cannibal dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Farina, Marco [New High Energy Theory Center, Department of Physics, Rutgers University,136 Frelinghuisen Road, Piscataway, NJ 08854 (United States); Pappadopulo, Duccio; Ruderman, Joshua T.; Trevisan, Gabriele [Center for Cosmology and Particle Physics, Department of Physics, New York University,New York, NY 10003 (United States)

    2016-12-13

    A hidden sector with a mass gap undergoes an epoch of cannibalism if number changing interactions are active when the temperature drops below the mass of the lightest hidden particle. During cannibalism, the hidden sector temperature decreases only logarithmically with the scale factor. We consider the possibility that dark matter resides in a hidden sector that underwent cannibalism, and has relic density set by the freeze-out of two-to-two annihilations. We identify three novel phases, depending on the behavior of the hidden sector when dark matter freezes out. During the cannibal phase, dark matter annihilations decouple while the hidden sector is cannibalizing. During the chemical phase, only two-to-two interactions are active and the total number of hidden particles is conserved. During the one way phase, the dark matter annihilation products decay out of equilibrium, suppressing the production of dark matter from inverse annihilations. We map out the distinct phenomenology of each phase, which includes a boosted dark matter annihilation rate, new relativistic degrees of freedom, warm dark matter, and observable distortions to the spectrum of the cosmic microwave background.

  13. Phases of cannibal dark matter

    Science.gov (United States)

    Farina, Marco; Pappadopulo, Duccio; Ruderman, Joshua T.; Trevisan, Gabriele

    2016-12-01

    A hidden sector with a mass gap undergoes an epoch of cannibalism if number changing interactions are active when the temperature drops below the mass of the lightest hidden particle. During cannibalism, the hidden sector temperature decreases only logarithmically with the scale factor. We consider the possibility that dark matter resides in a hidden sector that underwent cannibalism, and has relic density set by the freeze-out of two-to-two annihilations. We identify three novel phases, depending on the behavior of the hidden sector when dark matter freezes out. During the cannibal phase, dark matter annihilations decouple while the hidden sector is cannibalizing. During the chemical phase, only two-to-two interactions are active and the total number of hidden particles is conserved. During the one way phase, the dark matter annihilation products decay out of equilibrium, suppressing the production of dark matter from inverse annihilations. We map out the distinct phenomenology of each phase, which includes a boosted dark matter annihilation rate, new relativistic degrees of freedom, warm dark matter, and observable distortions to the spectrum of the cosmic microwave background.

  14. CERN openlab enters fifth phase

    CERN Multimedia

    Andrew Purcell

    2015-01-01

    CERN openlab is a unique public-private partnership between CERN and leading ICT companies. At the start of this year, openlab officially entered its fifth phase, which will run until the end of 2017. For the first time in its history, it has extended beyond the CERN community to include other major European and international research laboratories.   Founded in 2001 to develop the innovative ICT systems needed to cope with the unprecedented computing challenges of the LHC, CERN openlab unites science and industry at the cutting edge of research and innovation. In a white paper published last year, CERN openlab set out the main ICT challenges it will tackle during its fifth phase, namely data acquisition, computing platforms, data storage architectures, computer management and provisioning, networks and connectivity, and data analytics. As it enters its fifth phase, CERN openlab is expanding to include other research laboratories. "Today, research centres in other disciplines are also st...

  15. Topological Phases in Graphene Nanoribbons

    Science.gov (United States)

    Cao, Ting; Zhao, Fangzhou; Louie, Steven G.

    Using first-principles and model Hamiltonian calculations, we find that the band structures of various graphene nanoribbons give rise to interesting quantized Zak phases, depending on ribbon shape, width and edge termination. The Zak phase, an invariant of the occupied bands of the graphene nanoribbon, identifies the topological phase of the system and dictates the number of end states through the bulk-boundary correspondence. We moreover show that it can be modified by introducing an array of appropriate dopant atoms in the graphene nanoribbons. We demonstrate the origin of these findings, and connect our results to experimental measurements. This work is supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, and by the National Science Foundation. Computational resources have been provided by NERSC at LBNL.

  16. Dispersive Readout of Adiabatic Phases

    Science.gov (United States)

    Kohler, Sigmund

    2017-11-01

    We propose a protocol for the measurement of adiabatic phases of periodically driven quantum systems coupled to an open cavity that enables dispersive readout. It turns out that the cavity transmission exhibits peaks at frequencies determined by a resonance condition that involves the dynamical and the geometric phase. Since these phases scale differently with the driving frequency, one can determine them by fitting the peak positions to the theoretically expected behavior. For the derivation of the resonance condition and for a numerical study, we develop a Floquet theory for the dispersive readout of ac driven quantum systems. The feasibility is demonstrated for two test cases that generalize Landau-Zener-Stückelberg-Majorana interference to two-parameter driving.

  17. Phase diagrams for surface alloys

    DEFF Research Database (Denmark)

    Christensen, Asbjørn; Ruban, Andrei; Stoltze, Per

    1997-01-01

    of the heat of segregation from the bulk and the sign of the excess interactions between the atoms in the surface (the surface mixing energy). We also consider the more complicated cases a with ordered surface phases, nonpseudomorphic overlayers, second layer segregation, and multilayers. The discussion......We discuss surface alloy phases and their stability based on surface phase diagrams constructed from the surface energy as a function of the surface composition. We show that in the simplest cases of pseudomorphic overlayers there are four generic classes of systems, characterized by the sign...... is based on density-functional calculations using the coherent-potential approximation and on effective-medium theory. We give self-consistent density-functional results for the segregation energy and surface mixing energy for all combinations of the transition and noble metals. Finally we discuss...

  18. Geometric Phase and Quantum Phase Transition in the Lipkin-Meshkov-Glick model

    OpenAIRE

    Cui, H. T.; Li, K.; Yi, X. X.

    2006-01-01

    The relation between the geometric phase and quantum phase transition has been discussed in the Lipkin-Meshkov-Glick model. Our calculation shows the ability of geometric phase of the ground state to mark quantum phase transition in this model. The possibility of the geometric phase or its derivatives as the universal order parameter of characterizing quantum phase transitions has been also discussed.

  19. C14. Um caso de polimiosite, fibrose pulmonar e cancro do pulmão

    Directory of Open Access Journals (Sweden)

    Carlos Lopes

    2003-11-01

    Full Text Available Os autores apresentam o caso clínico de um doente do sexo masculino, de 67 anos, fumador (50 UMA. Trabalhou na marinha durante 30 anos, onde esteve exposto a fibras de asbestos.Aparentemente estável até aos 62 anos, altura em que refere início de quadro clínico de dispneia de esforço, de agravamento progressivo. Um ano depois episódio de febre, tosse produtiva e mialgias.Ao exame objectivo eram evidentes hipocratismo digital e fervores subcrepitantes em ambas as bases, na auscultação torácica.Os aspectos vizualizados na TC Torácica eram compatíveis com Pneumonia Intersticial Usual e o lavado broncoalveolar excluiu outras doenças.O estudo da função respiratória mostrou um síndrome restritivo com diminuição da capacidade de difusão do CO.Foi administrada terapêutica com Deflazacort, acetilcisteína e azatioprina. Devido a agravamento clínico e funcional, azatioprina foi substituída por ciclofosfamida. Dois anos depois foi iniciada terapêutica com Interferão Gamma 1b, com melhoria clínica e funcional, durante um ano.Foi então feito o diagnóstico de Polimiosite e recebeu terapêutica com imunoglobulina.Doze meses depois foi internado com quadro clínico de febre intermitente, tosse seca, dispneia de esforço de agravamento progressivo e mialgias. A TC Torácica revelou pulmão em favo e bronquiectasias. No lobo inferior esquerdo foi detectado um nódulo periférico. O doente foi submetido a biópsia aspirativa transtorácica, o padrão imunohistoquímico do tecido revelou Cancro do Pulmão de Pequenas Células. No estadiamento foram identificadas adenopatias hilares e mediastínicas e múltiplas metástases hepáticas. Apenas foi efectuada uma administração de quimioterapia (carboplatinum e etoposido, sem qualquer tipo de resposta. O doente faleceu duas semanas depois.Está documentada a associação de Polimiosite com várias Neoplasias, neste caso clínico, o doente desenvolveu fibrose pulmonar antes de ter sido feito o diagnóstico de Polimiosite, e só alguns anos depois foi diagnosticado Cancro do Pulmão de Pequenas Células. : The authors present the case of a 67 year-old man with a 50-pack-year history of cigarette smoking. He had been in the navy for 30 years where he was exposed to asbestos fibbers.He had been asymptomatic until the age of 62, when he started to experience increasing exertional dyspnoea. One year later he had an episode of fever, productive cough and myalgias. Digital clubbing was noticed and bibasilar crackles were present on chest auscultation.Thoracic CT scan obtained at that time, were compatible with Usual Interstitial Pneumonia and bronchoalveolar lavage excluded other diseases. Pulmonary function studies: restriction and decreased DLco.Deflazacort, acetylcysteine and azathioprine were administered. Azathioprine was then switched to cyclophosphamide because of clinical and functional deterioration. Two years later he began Interferon Gamma 1b, with clinical and functional improvement lasting one year.He was then diagnosed Polymyositis and received Immunoglobulin.Twelve months later he was admitted to the hospital with intermittent fever, non productive cough, worsening exertional dyspnoea and myalgias. The Thoracic scan showed honeycombing and bronchiectasis. In the left inferior lobe there was a peripheral nodule. The patient was submitted to a Thansthoracic Needle Biopsy, the tissue immunocytochemistry pattern revealed Small Cell Lung Cancer. In the staging procedures there were positive mediastinal and hilar nodes and multiple hepatic metastases.Only one administration of chemotherapy was performed with carboplatinum and etoposide, without response. Unfortunately the patient died a fortnight later.Polymyositis has been associated with a variety of malignancies, in this case, the patient developed pulmonary fibrosis previously to the diagnosis of Polymyositis, and only several years later Small Cell Lung cancer was diagnosed. Palavras-chave: Fibrose Pulmonar, Polimiosite, Cancro do Pulmão de Pequenas Células, Key-words: Pulmonary Fibrosis, Polymyositis

  20. Modelling H-3 and C-14 transfer to farm animals and their products

    Energy Technology Data Exchange (ETDEWEB)

    Galeriu, D; Melintescu, A; Beresford, N; Crout, N; Peterson, R; Takeda, H

    2006-06-23

    The radionuclides {sup 14}C and {sup 3}H may both be released from nuclear facilities. These radionuclides differ from most others in that they are isotopes of macro-elements which form the basis of animal tissues, feed and, in the case of {sup 3}H, water. There are few published values describing the transfer of {sup 3}H and {sup 14}C from feed to animal derived food products. Approaches are described which enable the prediction of {sup 14}C and {sup 3}H transfer parameter values from readily available information on the stable H or C concentration of animal feeds, tissues and milk, water turnover rates, and feed intakes and digestibilities. It is recommended that the concentration ratio between feed and animal product activity concentrations be used as it is less variable than the transfer coefficient (ratio between radionuclide activity concentration in animal milk or tissue to the daily intake of a radionuclide).

  1. Les Campaniformes Pyreneo-Languedociens Premiers Résultats au C 14

    Directory of Open Access Journals (Sweden)

    Jean GUILAINE

    2009-10-01

    Full Text Available La civilisation des gobelets campaniformes a posé aux préhistoriens, dès son individualisation même, des problèmes de géographie et de diffusion ainsi que des questions de caractère chronologique. C'est essentiellement le mérite des auteurs ibériques d'avoir montré que cette culture s'était fractionnée en ensembles géographiques relativement distincts (P. Bosch-Gimpera, A. del Castillo. Les auteurs anglo-saxons, pour leur part, ont surtout mis l'accent sur les variantes typologiques, en essayant de décortiquer la famille campaniforme en horizons stylistiquement et chronologiquement bien différenciés. Au terme d'une longue tradition (marquée par les travaux de A. Goetze, P. Reinecke, J. Abercromby, V. G. Childe, H. N. Savory, etc., se trouve une série de belles synthèses dont les plus remarquables sont celles de E. Sangmeister (1951, J. D. Van der Waals et W. Glasbergen (1955, D. L. Clarke (1970. De nombreux préhistoriens se sont par ailleurs penchés sur les problèmes de diffusion et diverses thèses ont été émises: théorie de l'origine sud-ibérique (Schmidt, Bosch- Gimpera, Del Castillo; théorie de la genèse centro-européenne (J. et E. Neustupny; thèse, plus complexe, de Sangmeister mettant en jeu divers relais à partir de Liberie et un important phénomène de reflux depuis l'Europe moyenne en direction de la Péninsule (théorie fortement discutée par la suite par son auteur même; enfin, tout récemment, hypothèse de D. L. Clarke sur la formation de cette civilisation dans le Midi de la France, plus particulièrement dans la région bordant le Golfe du Lion.

  2. http://revistas.udistrital.edu.co/ojs/index.php/c14/article/view/10993

    Directory of Open Access Journals (Sweden)

    José Daniel Santibáñez Vásquez

    2016-01-01

    Full Text Available El Llanero Solitario ha sido uno de los personajes más emblemáticos de la cultura estadounidense. Su paso por la radio, televisión, cine y cómics marcó toda una época en la que los vaqueros eran héroes nacionales. Uno de los medios que tuvo mayor aceptación por parte del público fue el de la tira cómica o comic strip, que se publicaba diariamente. Escrita por Cary Bates e ilustrado por Russ Heath, esta tira logró llevar a muchos lectores a acompañar al Llanero Solitario y a Tonto en sus aventuras. Se trata de una obra de gran calidad narrativa y visual, en la que Russ Heath expone su talento como dibujante y su capacidad para ordenar, de manera inteligente, cada elemento gráfico del cómic.

  3. Synthesis and structural characterization of (C14H16N2)3 ...

    Indian Academy of Sciences (India)

    Polyoxometalates (POMs) have attracted considerable attention due to potential applications in a variety of fields, including catalysis, analytic chemistry, medicine ... was transferred to a 23 mL sealed Teflon-lined reactor and heated at 140◦C for 24 h. After cooling the auto- clave to room temperature for 48 h, yellow-green ...

  4. Contributions of C14 to the understanding of Carpetano mortuary practice in Central Spain

    Directory of Open Access Journals (Sweden)

    Pereira Sieso, Juan

    2003-12-01

    Full Text Available Radiocarbon dates at the Iron Age cemetery of Palomar de Pintado, Spain, have given new information about the origins and development of the Carpetana culture in the centre of the Iberian Peninsula. Seven samples of charred bones from eight tombs have shown a complete sequence throughout the first millenium BC.

    Se presentan en este trabajo los resultados de una serie de análisis de C-l4 realizados sobre huesos quemados procedentes de siete tumbas a partir de los cuales se pretende fijar el ámbito cronológico y fases de desarrollo de la necrópolis de Palomar de Pintado (Toledo en el I milenio AC.

  5. Load structure seismites in the Dead Sea Area, Israel : Chronological benchmarking with C-14 dating

    NARCIS (Netherlands)

    Bowman, D; Bruins, HJ; van der Plicht, J; Boaretto, E.; Bruins, Hendrik J.; Carmi, I.

    2001-01-01

    The Dead Sea is a terminal lake located in the seismically active zone of the Syro-African Rift Valley. The water level of the Dead Sea has been receding dramatically during the last decades, resulting in significant entrenchment of wadis towards its shores. Exposed sections in fan deltas reveal

  6. Adsorptive Separation and Sequestration of Krypton, I and C14 on Diamond Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Tushar [Univ. of Missouri, Columbia, MO (United States); Loyalka, Sudarsha [Univ. of Missouri, Columbia, MO (United States); Prelas, Mark [Univ. of Missouri, Columbia, MO (United States); Viswanath, Dabir [Univ. of Missouri, Columbia, MO (United States)

    2015-03-31

    The objective of this research proposal was to address the separation and sequestration of Kr and I from each other using nano-sized diamond particles and retaining these in diamond until they decay to the background level or can be used as a byproduct. Following removal of Kr and I, an adsorbent will be used to adsorb and store CO2 from the CO2 rich stream. A Field Enhanced Diffusion with Optical Activation (FEDOA-a large scale process that takes advantage of thermal, electrical, and optical activation to enhance the diffusion of an element into diamond structure) was used to load Kr and I on micron or nano sized particles having a larger relative surface area. The diamond particles can be further increased by doping it with boron followed by irradiation in a neutron flux. Previous studies showed that the hydrogen storage capacity could be increased significantly by using boron-doped irradiated diamond particles. Diamond powders were irradiated for a longer time by placing them in a quartz tube. The surface area was measured using a Quantachrome Autosorb system. No significant increase in the surface area was observed. Total surface area was about 1.7 m2/g. This suggests the existence of very minimal pores. Interestingly it showed hysteresis upon desorption. A reason for this may be strong interaction between the surface and the nitrogen molecules. Adsorption runs at higher temperatures did not show any adsorption of krypton on diamond. Use of a GC with HID detector to determine the adsorption capacity from the breakthrough curves was attempted, but experimental difficulties were encountered.

  7. C14ORF179 encoding IFT43 is mutated in Sensenbrenner syndrome

    NARCIS (Netherlands)

    Arts, H.H.; Bongers, M.H.F.; Mans, D.A.; Beersum, S.E.C. van; Oud, M.M.; Bolat, E.; Spruijt, L.; Cornelissen, E.A.M.; Schuurs-Hoeijmakers, J.H.M.; Leeuw, N. de; Cormier-Daire, V.; Brunner, H.G.; Knoers, N.V.A.M.; Roepman, R.

    2011-01-01

    BACKGROUND: Sensenbrenner syndrome is a heterogeneous ciliopathy that is characterised by skeletal and ectodermal anomalies, accompanied by chronic renal failure, heart defects, liver fibrosis and other features. OBJECTIVE: To identify an additional causative gene in Sensenbrenner syndrome. METHODS:

  8. Spectroscopic study of tetradecyltrimethylammonium bromide Pt-C14TAB nanoparticles: Structure and Stability

    Energy Technology Data Exchange (ETDEWEB)

    Borodko, Y.; Jones, L.; Frei, H.; Somorjai, G.

    2009-01-09

    The vibrational spectra of platinum nanoparticles (12 nm) capped with tetradecyltrimethylammonium bromide, C{sub 14}TAB, were investigated by Fourier transform infrared (FTIR) spectroscopy. We have shown that the thermal decay of Pt-C{sub 14}TAB nanoparticles in N{sub 2}, H{sub 2} and O{sub 2} atmospheres leads to the release of hydrocarbon chain of surfactant and the formation of strongly bonded layer of ammonium cations on the platinum surface. The platinum atoms accessible to CO chemisorptions were not reducible by hydrogen in the temperature ranging from 30 C to 200 C. A FTIR spectrum of C{sub 14}TAB adsorbed on Pt nanoparticles dramatically perturbed as compared with pure C{sub 14}TAB. New intense and broad bands centered at 1450 cm{sup -1} and 760 cm{sup -1} are making their appearance in Pt-C{sub 14}TAB. It may be speculated, that new bands are result of coupling between conducting electrons of Pt and molecular vibrations of adsorbed C{sub 14}TAB and as a consequence specific vibrational modes of ammonium cation transformed into electron-vibrational modes.

  9. Study of Second Phase Particles and Fe content in Zr Alloys Using the Advanced Photon Source at Argonne

    Energy Technology Data Exchange (ETDEWEB)

    Arthur T. Motta

    2001-11-07

    We have conducted a study of second phase particles and matrix alloying element concentrations in zirconium alloys using synchrotron radiation from the Advanced Photon Source (APS) at Argonne National Laboratory. The high flux of synchrotron radiation delivered at the 2BM beamline compared to conventional x-ray generators, enables the detection of very small precipitate volume fractions. We detected the standard C14 hcp Zr(Cr,Fe)2 precipitates, (the stable second phase in Zircaloy-4) in the bulk material at a cumulative annealing parameter as low as 10-20 h, and we followed the kinetics of precipitation and growth as a function of the cumulative annealing parameter (CAP) in the range 10-22 (quench) to 10-16 h. In addition, the unique combination of spatial resolution and elemental sensitivity of the 2ID-D/E microbeam line at the Advanced Photon Source at Argonne (APS) allows study of the alloying element concentrations at ppm levels in an area as small as 0.2 mm. We used x-ray fluorescence induced by this sub-micron x-ray beam to determine the concentration of these alloying elements in the matrix as a function of alloy type and thermal history. We discuss these results and the potential of synchrotron radiation-based techniques for studying zirconium alloys.

  10. Qualitative behaviour of incompressible two-phase flows with phase ...

    Indian Academy of Sciences (India)

    Jan Prüss

    2017-11-07

    Nov 7, 2017 ... with phase transitions is considered mathematically. The model is based on first ... is constant, i.e we consider the isothermal case. ν designates the outer normal of 1, V the normal velocity of (t), ... and ψ1,ψ2 be the given Helmholtz free energies, which are constants in the isothermal, incompressible case.

  11. Phase behaviour and phase separation kinetics measurement using acoustic arrays

    Science.gov (United States)

    Khammar, M.; Shaw, J. M.

    2011-10-01

    Speed of sound and acoustic wave attenuation are sensitive to fluid phase composition and to the presence of liquid-liquid interfaces. In this work, the use of an acoustic array comprising 64 elements as a non-intrusive sensor for liquid-liquid interface, phase separation kinetics measurement in bulk fluids, and local composition measurement in porous media is illustrated. Three benchmark examples: the phase behaviour of methanol + mixed hexanes and methanol + heptane mixtures at 25.0 °C and 1 bar, and Athabasca bitumen + heptane in a synthetic silica porous medium at 22.5 °C and 1 bar, illustrate the accuracy of liquid-liquid interface and potential research and industrial applications of the technique. Liquid-liquid interfaces can be detected independently using both speed of sound and acoustic wave attenuation measurements. The precision of the interface location measurement is 300 μm. As complete scans can be performed at a rate of 1 Hz, phase separation kinetics and diffusion of liquids within porous media are readily tracked. The technique is expected to find application where the fluids or porous media are opaque to visible light and where other imaging techniques are not readily applied, or are too costly. A current limitation is that the acoustic probes must be cooled to less than 315 K in order for them to operate.

  12. Solid-phase sequencing on the gas-phase sequencer.

    Science.gov (United States)

    Sarin, V K; Kim, Y; Fox, J L

    1986-05-01

    Automated Edman degradation has been successfully used for determining the primary structure of numerous peptides and proteins. Quantitative solid-phase Edman degradation has great potential use for amino acid sequence analysis of synthetic peptides assembled on resin support by the Merrifield procedure. We report here the combined use of a modified gas-phase sequencer program and our improved reversed-phase HPLC analysis for PTH-amino acids to carry out the sequence analysis on synthesized peptide resins. This approach is far more sensitive than using glass beads on the conventional solid-phase sequencer. The peptide was assembled on copoly (styrene-1% divinylbenzene) resin beads at an initial substitution of 0.54 mmol/g. On a routine basis, 10-15 resin beads are used, and a repetitive yield of 94% is obtained: as few as 4 beads can be successfully sequenced. The HPLC PTH-amino acid analysis is sensitive down to subpicomole quantities. This procedure offers a sensitive and rapid analytical tool for checking the purity of peptides as they are being assembled on solid support.

  13. Topological phases and phase transitions in magnets and ice

    NARCIS (Netherlands)

    Keesman, R.

    2017-01-01

    The main focus of this Thesis is the behaviour of two-dimensional materials, namely (anti)-ferromagnetic materials in the first two chapters, which show topological phases, and energetic square ice in the third and fourth chapter. The magnetic materials are of interest in part due to foreseen

  14. About Phase: Synthetic Aperture Radar and the Phase Retrieval

    Science.gov (United States)

    2014-03-01

    known lower bound. To evaluate this bound, first note that Milgram [77] constructs an embedding of CPn into R4n−α(n)+1, establishing the importance...Phys. Chem. 59 (2008) 387–410. 77. R. J. Milgram , Immersing projective spaces, Ann. Math. 85 (1967) 473–482. 78. R. P. Millane, Phase retrieval in

  15. Phase diagrams and crystal growth

    Science.gov (United States)

    Venkrbec, Jan

    1980-04-01

    Phase diagrams are briefly treated as generalized property-composition relationships, with respect to crystal technology optimization. The treatment is based on mutual interaction of three systems related to semiconductors: (a) the semiconducting material systems, (b0 the data bank, (c) the system of crystallization methods. A model is proposed enabling optimatization on the path from application requirements to the desired material. Further, several examples of the selection as to the composition of LED and laser diode material are given. Some of molten-solution-zone methods are being successfully introduced for this purpose. Common features of these methods, the application of phase diagrams, and their pecularities compared with other crystallization methods are illustrated by schematic diagrams and by examples. LPE methods, particularly the steady-state LPE methods such as Woodall's ISM and Nishizawa's TDM-CVP, and the CAM-S (Crystallization Method Providing Composition Autocontrol in Situ) have been chosen as examples. Another approach of exploiting phase diagrams for optimal material selection and for determination of growth condition before experimentation through a simple calculation is presented on InP-GaP solid solutions. Ternary phase diagrams are visualized in space through calculation and constructions based on the corresponding thermodynamic models and anaglyphs. These make it easy to observe and qualitatively analyze the crystallization of every composition. Phase diagrams can be also used as a powerful tool for the deduction of new crystallization methods. Eutectic crystallization is an example of such an approach where a modified molten-solution-zone method can give a sandwich structure with an abrupt concentration change. The concentration of a component can range from 0 to 100% in the different solid phases.

  16. Scrutinizing the pion condensed phase

    Energy Technology Data Exchange (ETDEWEB)

    Carignano, Stefano; Mammarella, Andrea; Mannarelli, Massimo [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Lepori, Luca [Universita di Padova, Dipartimento di Fisica e Astronomia, Padova (Italy); Universita dell' Aquila, Dipartimento di Scienze Fisiche e Chimiche, Coppito-L' Aquila (Italy); Pagliaroli, Giulia [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Gran Sasso Science Institute, L' Aquila (Italy)

    2017-02-15

    When the isospin chemical potential exceeds the pion mass, charged pions condense in the zero-momentum state forming a superfluid. Chiral perturbation theory provides a very powerful tool for studying this phase. However, the formalism that is usually employed in this context does not clarify various aspects of the condensation mechanism and makes the identification of the soft modes problematic. We re-examine the pion condensed phase using different approaches within the chiral perturbation theory framework. As a first step, we perform a low-density expansion of the chiral Lagrangian valid close to the onset of the Bose-Einstein condensation. We obtain an effective theory that can be mapped to a Gross-Pitaevskii Lagrangian in which, remarkably, all the coefficients depend on the isospin chemical potential. The low-density expansion becomes unreliable deep in the pion condensed phase. For this reason, we develop an alternative field expansion deriving a low-energy Lagrangian analog to that of quantum magnets. By integrating out the ''radial'' fluctuations we obtain a soft Lagrangian in terms of the Nambu-Goldstone bosons arising from the breaking of the pion number symmetry. Finally, we test the robustness of the second-order transition between the normal and the pion condensed phase when next-to-leading-order chiral corrections are included. We determine the range of parameters for turning the second-order phase transition into a first-order one, finding that the currently accepted values of these corrections are unlikely to change the order of the phase transition. (orig.)

  17. Phase diagram of boron crystals

    Science.gov (United States)

    Shirai, Koun

    2017-05-01

    The current status of study on the phase diagram of boron is given from the theoretical viewpoint. Boron is the last elemental crystal whose phase diagram is missing. In the last decade, several new structures of boron allotropes were found, while some were disproven. Presently, even the number of allotropes of boron is uncertain. A simple reason for this is that there are many and complicated structures, and some are minimally different from the others. A theoretical study thus requires very high accuracy. The difficulty, however, is not merely a technical difficulty of computational scale. The physics involved is quite different from what is obtained by band theory, which is the most successful theory of solids. It is only recent that a fundamental problem of metal/insulator has been solved. We come to know that the interrelationships between nonstoichiometry, partially occupied sites, and the balance of intra/inter-icosahedral bonding, which were considered to be uncorrelated properties, inevitably determine the relative stability of various structures. The configuration of the defects in boron crystals is not capricious but there is some correlation among the defects. Many problems were solved on this ground, and contributed to the creation of the phase diagram. However, there are still many unsolved problems and some newly arose. In particular, for the tetragonal phase, sharp discrepancies are present in both experiment and theory. Thus, the problem of tetragonal phase is described in more detail. From the viewpoint of material research, the phase diagram provides the basis for searching new materials. State-of-the-art methods of structural prediction have stimulated researchers’ interest.

  18. Imaging of surface wave phase velocities from array phase observations

    Science.gov (United States)

    Weidle, Christian; Maupin, Valerie

    2010-05-01

    While temporary deployments some 10 years ago were largely based on short-period seismometers, the availability of broadband instruments in instrument pools increased strongly in recent years and as such modern temporary deployments for passive seismological recordings often consist to a large extent, if not exclusively, of broadband instruments. This opens for new analysis approaches as the broadband seismic wavefield is obtained at a relatively high spatial sampling relative to the wavelength. In an attempt to infer surface wave phase velocity anomalies beneath Southern Norway based on data from a temporary network of 41 broadband instruments, we present a new approach to overcome the limitations of two-station phase measurements (on the great circle with the source) and instead exploit the two-dimensional nature of the wavefield by taking into account phase measurements at all stations of the array from a single event. This is based on the assumption that the wavefield is at least piecewise linear within the study region. By triangulation of the network region and linear estimation of the phase gradient in each triangle we get without further a priori assumptions a coarse image of the phase velocity variations within our network. The image can be significantly refined for a single event recording by stacking multiple images based on arbitrary subsets of the available data. Phase velocity anomalies measured from single event recordings can be biased and blurred by non-plane arriving wavefield, reflections and diffractions of heterogeneities. Therefore, by averaging over velocity fields from different events with varying backazimuths, artefacts are reduced and the recovered image significantly improved. Another way to improve the recovered structures is to take into account the spatial variation of the amplitude field. However, while the phase between two neighboring stations may be (at least close to) linear, the amplitude may not, hence estimation of the second

  19. Phase conjugation of acoustic beams

    Science.gov (United States)

    Bunkin, F. V.; Vlasov, D. V.; Kravtsov, Iu. A.

    The paper presents a classification of methods for the phase conjugation (PC) of wave fields of various physical natures on the basis of such nonliner interactions as stimulated scattering, and three- and four-wave interactions. Among the latter, attention is given to holographic (volume and surface) and parametric PC schemes, permitting PC with amplification. The possibility of developing phase-conjugated devices using acoustic PC devices on the basis of various nonlinear effects is considered. Experimental results pertaining to the PC of sound fields are presented, and possible applications of acoustic PC devices are indicated.

  20. Broadband phased-arrays antennas

    Science.gov (United States)

    Mansky, L.

    1984-09-01

    The actual jamming-to-signal ratio achieved in an electronic countermeasures (ECM) system depends on the effective radiated power (ERP) directed toward the radar by the ECM system. The required ERP may be obtained in a phase-steered array using a variety of transmit-subsystem hardware configurations. Here, tradeoff criteria to aid in the selection of an optimal architecture are discussed. Such selection is based on minimizing the array size, backscattering cross selection, and overall system complexity. Functional elements of typical phased arrays and their principal components are descried.

  1. Solid-phase peptide synthesis

    DEFF Research Database (Denmark)

    Jensen, Knud Jørgen

    2013-01-01

    This chapter provides an introduction to and overview of peptide chemistry with a focus on solid-phase peptide synthesis. The background, the most common reagents, and some mechanisms are presented. This chapter also points to the different chapters and puts them into perspective.......This chapter provides an introduction to and overview of peptide chemistry with a focus on solid-phase peptide synthesis. The background, the most common reagents, and some mechanisms are presented. This chapter also points to the different chapters and puts them into perspective....

  2. Phase out of incandescent lamps

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2010-07-01

    Since early 2007 almost all OECD and many non-OECD governments have announced policies aimed at phasing-out incandescent lighting within their jurisdictions. This study considers the implications of these policy developments in terms of demand for regulatory compliant lamps and the capacity and motivation of the lamp industry to produce efficient lighting products in sufficient volume to meet future demand. To assess these issues, it reviews the historic international screw-based lamp market, describes the status of international phase-out policies and presents projections of anticipated market responses to regulatory requirements to determine future demand for CFLs.

  3. Moment Distributions of Phase Type

    DEFF Research Database (Denmark)

    Bladt, Mogens; Nielsen, Bo Friis

    In this paper we prove that the class of distributions on the positive reals with a rational Laplace transform, also known as matrix-exponential distributions, is closed under formation of moment distributions. In particular, the results are hence valid for the well known class of phase-type dist......In this paper we prove that the class of distributions on the positive reals with a rational Laplace transform, also known as matrix-exponential distributions, is closed under formation of moment distributions. In particular, the results are hence valid for the well known class of phase...

  4. Holographically Encoded Volume Phase Masks

    Science.gov (United States)

    2015-07-13

    optics ,” Nat. Photonics 4, 188–193 (2010). 26. H. Kogelnik, “Coupled wave theory for thick volume holograms ,” Bell System Tech. J. 45(9), 2909–2944...phase masks Marc SeGall, Ivan Divliansky,* Clémence Jollivet, Axel Schülzgen, and Leonid B. Glebov University of Central Florida, College of Optics and...satisfying the Bragg condition of the hologram . Moreover, this approach enables the capability to encode and multiplex several phase masks into a single

  5. Phase coarsening in multicomponent systems.

    Science.gov (United States)

    Wang, K G; Wang, Gabriel Q

    2017-02-01

    A theory for phase coarsening in multicomponent systems is developed in which both the multicomponent thermodynamic effect and kinetic effect from a nonzero volume fraction are considered. In contrast to previous theory, a diffusion screening zone for a coarsening particle due to nonzero volume fraction is introduced. The evolution equation for phase coarsening in multicomponent systems is derived in a rigorous way in the framework of the maximum rate of dissipation with the constraints of mass and energy conservation. Existing previous relations are recovered and generalized. Some findings such as the relationship between the maximum particle size and volume fraction and particle size distribution in multicomponent systems are discovered.

  6. Small Business Innovation Research GRC Phase I, Phase II, and Post-Phase II Opportunity Assessment for 2015

    Science.gov (United States)

    Nguyen, Hung D.; Steele, Gynelle C.

    2016-01-01

    This report outlines the 2015 Small Business Innovation Research/Small Business Technology Transfer (SBIR/STTR) Phase I, Phase II, and Post-Phase II opportunity contract award results associated with NASA's Aeronautics Research Mission Directorate (ARMD), Human Exploration and Operations Mission Directorate (HEOMD), Science Mission Directorate (SMD), and Space Technology Mission Directorate (STMD) for NASA Glenn Research Center. The report also highlights the number of Phase I, Phase II, and Post-Phase II contracts awarded by mission directorate. The 2015 Phase I contract awards to companies in Ohio and their corresponding technologies are also discussed.

  7. GPC and quantitative phase imaging

    DEFF Research Database (Denmark)

    Palima, Darwin; Banas, Andrew Rafael; Villangca, Mark Jayson

    2016-01-01

    shaper followed by the potential of GPC for biomedical and multispectral applications where we experimentally demonstrate the active light shaping of a supercontinuum laser over most of the visible wavelength range. Finally, we discuss how GPC can be advantageously applied for Quantitative Phase Imaging...

  8. Crichton's phase-shift ambiguity

    NARCIS (Netherlands)

    Atkinson, D.; Johnson, P.W.; Mehta, N.; Roo, M. de

    1973-01-01

    A re-examination of the SPD phase-shift ambiguity is made with a view to understanding certain singular features of the elastic unitarity constraint. An explicit solution of Crichton's equations is presented, and certain features of this solution are displayed graphically. In particular, it is shown

  9. Multiple solid-phase microextraction

    NARCIS (Netherlands)

    Koster, EHM; de Jong, GJ

    2000-01-01

    Theoretical aspects of multiple solid-phase microextraction are described and the principle is illustrated with the extraction of lidocaine from aqueous solutions. With multiple extraction under non-equilibrium conditions considerably less time is required in order to obtain an extraction yield that

  10. Phase transformations in metallic glasses

    DEFF Research Database (Denmark)

    Jiang, Jianzhong

    2003-01-01

    Recent development of grain-size effect on phase transformations induced by pressure is reported. A thermodynamic theory is presented and three components: the ratio of volume collapses, the surface energy differences, and the internal energy differences, governing the change of transition pressu...

  11. Phase diagram of Hertzian spheres

    NARCIS (Netherlands)

    Pàmies, J.C.; Cacciuto, A.; Frenkel, D.

    2009-01-01

    We report the phase diagram of interpenetrating Hertzian spheres. The Hertz potential is purely repulsive, bounded at zero separation, and decreases monotonically as a power law with exponent 5/2, vanishing at the overlapping threshold. This simple functional describes the elastic interaction of

  12. Magnetic anisotropy of ferrosmectic phases

    Science.gov (United States)

    Ponsinet, Virginie; Fabre, Pascale; Veyssié, Madeleine; Cabanel, Régis

    1994-10-01

    A new anisotropic magnetic fluid, called ferrosmectic, is obtained when using a colloidal suspension of submicronic magnetic particles (ferrofluid), as a component in a smectic phase of fluid membranes. These lamellar phases present specific magnetic properties. The anisotropy of their magnetic susceptilities as a function of particles concentration is studied and interpreted : a microscopic mechanism involving a steric hindrance between particles and membranes is used to understand the experimental results. Un nouveau fluide magnétique anisotrope, appelé ferrosmectique, est obtenu lorsque nous utilisons un ferrofluide, c'est-à-dire une suspension colloïdale de particules magnétiques de taille inférieure au micron, comme composant dans la fabrication d'une phase smectique de membranes fluides. Ces phases adoptent des comportements spécifiques sous champ magnétique, et nous présentons ici une étude de l'anisotropie de leur susceptibilité magnétique en fonction de la concentration en particules. Nous interprétons les résultats obtenus par un mécanisme microscopique basé sur l'existence d'une gêne stérique entre membranes et particules.

  13. Quantum mechanics in phase space

    DEFF Research Database (Denmark)

    Hansen, Frank

    1984-01-01

    A reformulation of quantum mechanics for a finite system is given using twisted multiplication of functions on phase space and Tomita's theory of generalized Hilbert algebras. Quantization of a classical observable h is achieved when the twisted exponential Exp0(-h) is defined as a tempered...

  14. Bacterial Stationary-Phase Evolution

    Directory of Open Access Journals (Sweden)

    Ana Butorac

    2011-01-01

    Full Text Available Metagenomics and advances in molecular biology methods have enhanced knowledge of microbial evolution, metabolism, functions, their interactions with other organisms and their environment. The ability to persist and adapt to changes in their environment is a common lifestyle of 1 % of the known culturable bacteria. Studies in the variety of species have identified an incredible diversity of bacterial lifespan. The holy grail of molecular biology is to understand the integrated genetic and metabolic patterns of prokaryotic organisms like the enteric bacterium Escherichia coli. The usual description of E. coli life cycle comprises four phases: lag, logarithmic, stationary, and death phase, omitting their persistence and evolution during prolonged stationary phase. During prolonged stationary/starvation period, in batch bacterial culture, selected mutants with increased fitness express growth advantage in stationary phase (GASP, which enables them to grow and displace the parent cells as the majority population. The analyses of growth competition of Gram-negative and/or Gram-positive mixed bacterial cultures showed that GASP phenomenon can result in four GASP phenotypes: strong, moderate, weak or abortive. Bacterial stress responses to starvation include functions that can increase genetic variability and produce transient mutator state, which is important for adaptive evolution.

  15. Advances phase-lock techniques

    CERN Document Server

    Crawford, James A

    2008-01-01

    From cellphones to micrprocessors, to GPS navigation, phase-lock techniques are utilized in most all modern electronic devices. This high-level book takes a systems-level perspective, rather than circuit-level, which differentiates it from other books in the field.

  16. Phase transitions in finite systems

    Energy Technology Data Exchange (ETDEWEB)

    Chomaz, Ph. [Grand Accelerateur National d' Ions Lourds (GANIL), DSM-CEA / IN2P3-CNRS, 14 - Caen (France); Gulminelli, F. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire

    2002-07-01

    In this series of lectures we will first review the general theory of phase transition in the framework of information theory and briefly address some of the well known mean field solutions of three dimensional problems. The theory of phase transitions in finite systems will then be discussed, with a special emphasis to the conceptual problems linked to a thermodynamical description for small, short-lived, open systems as metal clusters and data samples coming from nuclear collisions. The concept of negative heat capacity developed in the early seventies in the context of self-gravitating systems will be reinterpreted in the general framework of convexity anomalies of thermo-statistical potentials. The connection with the distribution of the order parameter will lead us to a definition of first order phase transitions in finite systems based on topology anomalies of the event distribution in the space of observations. Finally a careful study of the thermodynamical limit will provide a bridge with the standard theory of phase transitions and show that in a wide class of physical situations the different statistical ensembles are irreducibly inequivalent. (authors)

  17. Phase and birefringence aberration correction

    Science.gov (United States)

    Bowers, M.; Hankla, A.

    1996-07-09

    A Brillouin enhanced four wave mixing phase conjugate mirror corrects phase aberrations of a coherent electromagnetic beam and birefringence induced upon that beam. The stimulated Brillouin scattering (SBS) phase conjugation technique is augmented to include Brillouin enhanced four wave mixing (BEFWM). A seed beam is generated by a main oscillator which arrives at the phase conjugate cell before the signal beams in order to initiate the Brillouin effect. The signal beam which is being amplified through the amplifier chain is split into two perpendicularly polarized beams. One of the two beams is chosen to be the same polarization as some component of the seed beam, the other orthogonal to the first. The polarization of the orthogonal beam is then rotated 90{degree} such that it is parallel to the other signal beam. The three beams are then focused into cell containing a medium capable of Brillouin excitation. The two signal beams are focused such that they cross the seed beam path before their respective beam waists in order to achieve BEFWM or the two signal beams are focused to a point or points contained within the focused cone angle of the seed beam to achieve seeded SBS, and thus negate the effects of all birefringent and material aberrations in the system. 5 figs.

  18. Liquid phase chromatography on microchips

    DEFF Research Database (Denmark)

    Kutter, Jörg Peter

    2012-01-01

    explosive development of, in particular, chromatographic separation systems on microchips, has, however, slowed down in recent years. This review takes a closer, critical look at how liquid phase chromatography has been implemented in miniaturized formats over the past several years, what is important...

  19. Super-resolution Phase Tomography

    KAUST Repository

    Depeursinge, Christian

    2013-04-21

    Digital Holographic Microscopy (DHM) yields reconstructed complex wavefields. It allows synthesizing the aperture of a virtual microscope up to 2π, offering super-resolution phase images. Live images of micro-organisms and neurons with resolution less than 100 nm are presented.

  20. Symmetry structure and phase transitions

    Indian Academy of Sciences (India)

    ... symmetry structure at finite density and temperature in the presence of external magnetic field and gravity, a situation relevant in the early Universe and in the core of compact stars. We then investigate the dynamical evolution of phase transition in the expanding early Universe and possible formation of quark nuggets and ...

  1. Three-Phase Power Factor Controller

    Science.gov (United States)

    Nola, F. J.

    1982-01-01

    Three-Phase Power-Factor Controller develops a control signal for each motor winding. As motor loading decreases, rms value of applied voltage is decreased by feedback-control circuit. Power consumption is therefore lower than in unregulated operation. Controller employs phase detector for each of three phases of delta-connected induction motor. Phase-difference sum is basis for control.

  2. Mechanical and tribological properties of newly developed Tribaloy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Xu, W. [Department of Mechanical and Aerospace Engineering, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, K1S 5B6 (Canada); Liu, R. [Department of Mechanical and Aerospace Engineering, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, K1S 5B6 (Canada)], E-Mail: rliu@mae.carleton.ca; Patnaik, P.C. [Institute for Aerospace Research, National Research Council of Canada, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6 (Canada); Yao, M.X. [Deloro Stellite Inc., P.O. Box 5300, Belleville, Ontario, K8N 5C4 (Canada); Wu, X.J. [Institute for Aerospace Research, National Research Council of Canada, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6 (Canada)

    2007-04-15

    Outstanding combination of mechanical, wear and corrosion performance has been achieved in Laves intermetallic materials, termed Tribaloy alloys. In these two-phase alloys the solid solution provides high mechanical strength and fracture toughness while the Laves intermetallic phase offers excellent wear resistance. However, conventional Tribaloy alloys usually have low tensile strength and fracture toughness compared with ductile materials due to the large volume fraction of Laves phase, which has limited their application in many cases. The present research is aimed at developing advanced Tribaloy alloys with increasing ductility. Two new cobalt base alloys were developed in this research. The specimens were fabricated with a centrifugal casting technique. The material characterization was performed using the differential scanning calorimetry (DSC), scanning electron microscope (SEM), indentation and ball-on-disc tribological techniques.

  3. Thermal aging modeling and validation on the Mo containing Fe-Cr-Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tan, Lizhen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Busby, Jeremy T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-04-01

    Thermodynamics of intermetallic phases in Fe-rich Fe-Cr-Ni-Mo alloys is critical knowledge to understand thermal aging effect on the phase stability of Mo-containing austenitic steels, which subsequently facilitates alloy design/improvement and degradation mitigation of these materials for reactor applications. Among the intermetallic phases, Chi (χ), Laves, and Sigma (σ) are often of concern because of their tendency to cause embrittlement of the materials. The focus of this study is thermal stability of the Chi and Laves phases as they were less studied compared to the Sigma phase. Coupled with thermodynamic modeling, thermal stability of intermetallic phases in Mo containing Fe-Cr-Ni alloys was investigated at 1000, 850 and 700 C for different annealing times. The morphologies, compositions and crystal structures of the precipitates of the intermetallic phases were carefully examined by scanning electron microscopy, electron probe microanalysis, X-ray diffraction, and transmission electron microscopy. Three key findings resulted from this study. First, the Chi phase is stable at high temperature, and with decreasing temperature it transforms into the Laves phase that is stable at low temperature. Secondly, Cr, Mo, Ni are soluble in both the Chi and Laves phases, with the solubility of Mo playing a major role in the relative stability of the intermetallic phases. Thirdly, in situ transformation from Chi phase to Laves phase was directly observed, which increased the local strain field, generated dislocations in the intermetallic phases, and altered the precipitate phase orientation relationship with the austenitic matrix. The thermodynamic models that were developed and validated were then applied to evaluating the effect of Mo on the thermal stability of intermetallic phases in type 316 and NF709 stainless steels.

  4. Measurement of Phase Dependent Impedance for 3-phase Diode Rectifier

    DEFF Research Database (Denmark)

    Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth

    2016-01-01

    to provide an optimized solution for better power quality. However, the phase dependent impedance, which is driven by both switching instant variation and frequency coupling between ac and dc network, has not been treated in the design of passive filter or harmonic compensator design for power electronics...... are still widely used in AC-DC applications because of their cost effectiveness and reliability. However, these topologies generate harmonic problems in their network due to their switching instant variation caused by the frequency and phase of grid voltage. Hence, a lot of solutions have been proposed...... with results from time-domain simulations and results from an analytical model developed in the Harmonic State-Space (HSS)....

  5. Phase transformations in intermetallic phases in zirconium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Filippov, V. P., E-mail: vpfilippov@mephi.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation); Kirichenko, V. G. [Kharkiv National Karazin University (Ukraine); Salomasov, V. A. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation); Khasanov, A. M. [University of North Carolina – Asheville, Chemistry Department (United States)

    2017-11-15

    Phase change was analyzed in intermetallic compounds of zirconium alloys (Zr – 1.03 at.% Fe; Zr – 0.51 at.% Fe; Zr – 0.51 at.% Fe – M(M = Nb, Sn). Mössbauer spectroscopy on {sup 57}Fe nuclei in backscattering geometry with the registration of the internal conversion electrons and XRD were used. Four types of iron bearing intermetallic compounds with Nb were detected. A relationship was found between the growth process of intermetallic inclusions and segregation of these phases. The growth kinetics of inclusions possibly is not controlled by bulk diffusion, and a lower value of the iron atom’s activation energy of migration can be attributed to the existence of enhanced diffusion paths and interface boundaries.

  6. Phase transformations in intermetallic phases in zirconium alloys

    Science.gov (United States)

    Filippov, V. P.; Kirichenko, V. G.; Salomasov, V. A.; Khasanov, A. M.

    2017-11-01

    Phase change was analyzed in intermetallic compounds of zirconium alloys (Zr - 1.03 at.% Fe; Zr - 0.51 at.% Fe; Zr - 0.51 at.% Fe - M(M = Nb, Sn). Mössbauer spectroscopy on 57Fe nuclei in backscattering geometry with the registration of the internal conversion electrons and XRD were used. Four types of iron bearing intermetallic compounds with Nb were detected. A relationship was found between the growth process of intermetallic inclusions and segregation of these phases. The growth kinetics of inclusions possibly is not controlled by bulk diffusion, and a lower value of the iron atom's activation energy of migration can be attributed to the existence of enhanced diffusion paths and interface boundaries.

  7. Fourier Phase Domain Steganography: Phase Bin Encoding Via Interpolation

    Science.gov (United States)

    Rivas, Edward

    2007-04-01

    In recent years there has been an increased interest in audio steganography and watermarking. This is due primarily to two reasons. First, an acute need to improve our national security capabilities in light of terrorist and criminal activity has driven new ideas and experimentation. Secondly, the explosive proliferation of digital media has forced the music industry to rethink how they will protect their intellectual property. Various techniques have been implemented but the phase domain remains a fertile ground for improvement due to the relative robustness to many types of distortion and immunity to the Human Auditory System. A new method for embedding data in the phase domain of the Discrete Fourier Transform of an audio signal is proposed. Focus is given to robustness and low perceptibility, while maintaining a relatively high capacity rate of up to 172 bits/s.

  8. Phase Analysis of Fringe Pattern In Shearography

    Science.gov (United States)

    Yusof, M. Y.; Abdullah, W. S. Wan

    2008-05-01

    This paper discusses the phase analysis of interference pattern from coherent light Nd:YAG 532 nm laser source. The Twyman-Green Interferometer set-up is used for generating the fringe pattern in the phase calibration. The piezoelectric transducer (PZT) is used to achieve the required phase shift of the fringe pattern. It was found that the system required 8.8 volts of out-put DC voltage to shift 2π radians phase. The accuracy of optical phase measurement of the interference pattern is analyzed by wrapped phases of three-phase stepping and four-phase stepping procedures. Comparison of the experimental phase measurement data and the theoretical phase calculations are also highlighted.

  9. Mapping of phase singularities with spiral phase contrast microscopy.

    Science.gov (United States)

    Steiger, Ruth; Bernet, Stefan; Ritsch-Marte, Monika

    2013-07-15

    In spiral phase contrast (SPC) microscopy the edge-enhancement is typically independent of the helicity of the phase vortex filter. Here we show that for layered specimens containing screw-dislocations, as are e.g. present in mica or some crystallized organic substances, the intensity distribution in the filtered image acquires a dependence on the rotational direction of the filter. This allows one to map the distribution of phase singularities in the topography of the sample, by taking the intensity difference between two images recorded with opposite handedness. For the demonstration of this feature in a microscopy set-up, we encode the vortex filter as a binary off-axis hologram displayed on a spatial light modulator (SLM) placed in a Fourier plane. Using a binary grating, the diffraction efficiencies for the plus and minus first diffraction orders are equal, giving rise to two image waves which travel in different directions and are Fourier filtered with opposite helicity. The corresponding two images can be recorded simultaneously in two separate regions of the camera chip. This enables mapping of dislocations in the sample in a single camera exposure, as was demonstrated for various transparent samples.

  10. Creep strength and microstructural evolution of 9-12% Cr heat resistant steels during creep exposure at 600 C and 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Mendez Martin, Francisca [Graz Univ. of Technology (Austria). Inst. for Materials Science and Welding; Panait, Clara Gabriela [MINES ParisTech, UMR CNRS, Evry (France). Centre des Materiaux; V et M France CEV, Aulnoye-Aymeries (France); Bendick, Walter [Salzgitter Mannesmann Forschung GmbH (SZMF), Duisburg (DE)] (and others)

    2010-07-01

    9-12% Cr heat resistant steels are used for applications at high temperatures and pressures in steam power plants. 12% Cr steels show higher creep strength and higher corrosion resistance compared to 9% Cr steels for short term creep exposure. However, the higher creep strength of 12 %Cr steels drops increasingly after 10,000-20,000 h of creep. This is probably due to a microstructural instability such as the precipitation of new phases (e.g. Laves phases and Z-phases), the growth of the precipitates and the recovery of the matrix. 9% Cr and 12% Cr tempered martensitic steels that have been creep tested for times up to 50,000 h at 600 C and 650 C were investigated using Transmission Electron Microscopy (TEM) on extractive replicas and thin foils together with Backscatter Scanning Electron Microscopy (BSE-SEM) to better understand the different creep behaviour of the two different steels. A significant precipitation of Laves phase and low amounts of Z-phase was observed in the 9% Cr steels after long-term creep exposure. The size distribution of Laves phases was measured by image analysis of SEM-BSE images. In the 12% Cr steel two new phases were identified, Laves phase and Z-phase after almost 30,000 h of creep test. The quantification of the different precipitated phases was studied. (orig.)

  11. Geometric Phase and Classical-Quantum Correspondence

    OpenAIRE

    Satija, Indubala I.; Balakrishnan, Radha

    2004-01-01

    We study the geometric phase factors underlying the classical and the corresponding quantum dynamics of a driven nonlinear oscillator exhibiting chaotic dynamics. For the classical problem, we compute the geometric phase factors associated with the phase space trajectories using Frenet-Serret formulation. For the corresponding quantum problem, the geometric phase associated with the time evolution of the wave function is computed. Our studies suggest that the classical geometric phase may be ...

  12. Parameters of superfine interactions in Laves ScFe sub 2 alloy with hexagonal MnZn sub 2 structure

    CERN Document Server

    Pokatilov, V S

    2001-01-01

    The superfine fields, amplification coefficients and quadrupole splitting on the sup 4 sup 5 Sc nuclei in the ScFe sub 2 , Sc sub 0 sub . sub 9 sub 5 Fe sub 2 sub . sub 0 sub 5 and ScFe sub 1 sub . sub 9 sub 7 Al sub 0 sub . sub 0 sub 3 alloys are measured at the room temperature and 77 K through the method of the nuclear magnetic resonance (NMR). The NMR spectra peculiarities are studied and the superfine field shifts on the sup 4 sup 5 Sc nuclei in the considered alloys by appearance of the Fe atoms at the Sc atoms places and the Al atoms at the Fe atoms places in the Sc atoms nearest coordination sphere are determined. It is established that the electron quadrupole splitting in the considered alloys does not depend on the technology of obtaining the samples, on insignificant deviations from the alloy stoichiometric composition or on the minor additions of the Al atoms

  13. "Jeg bliver sådan helt nervøs, hvis det var en mand, der skulle lave det"

    DEFF Research Database (Denmark)

    Grosen, Sidsel Lond; Holt, Helle; Hvid, Helge Søndergaard

    2010-01-01

    dokumentafdelingen er der tydeligvis et samspil mellem forestillinger om køn og arbejde. For at forstå og give mening til dette samspil trækker kvinderne på historisk indlejrede kønsstereotypier, som fx at kvinder primært er omsorgsydere, at kvinder er gode til at multitaske, og at kvinder kan lide rutinearbejde....

  14. Phase synchronization in railway timetables

    Science.gov (United States)

    Fretter, C.; Krumov, L.; Weihe, K.; Müller-Hannemann, M.; Hütt, M.-T.

    2010-09-01

    Timetable construction belongs to the most important optimization problems in public transport. Finding optimal or near-optimal timetables under the subsidiary conditions of minimizing travel times and other criteria is a targeted contribution to the functioning of public transport. In addition to efficiency (given, e.g., by minimal average travel times), a significant feature of a timetable is its robustness against delay propagation. Here we study the balance of efficiency and robustness in long-distance railway timetables (in particular the current long-distance railway timetable in Germany) from the perspective of synchronization, exploiting the fact that a major part of the trains run nearly periodically. We find that synchronization is highest at intermediate-sized stations. We argue that this synchronization perspective opens a new avenue towards an understanding of railway timetables by representing them as spatio-temporal phase patterns. Robustness and efficiency can then be viewed as properties of this phase pattern.

  15. Quantitative phase imaging of arthropods

    Science.gov (United States)

    Sridharan, Shamira; Katz, Aron; Soto-Adames, Felipe; Popescu, Gabriel

    2015-01-01

    Abstract. Classification of arthropods is performed by characterization of fine features such as setae and cuticles. An unstained whole arthropod specimen mounted on a slide can be preserved for many decades, but is difficult to study since current methods require sample manipulation or tedious image processing. Spatial light interference microscopy (SLIM) is a quantitative phase imaging (QPI) technique that is an add-on module to a commercial phase contrast microscope. We use SLIM to image a whole organism springtail Ceratophysella denticulata mounted on a slide. This is the first time, to our knowledge, that an entire organism has been imaged using QPI. We also demonstrate the ability of SLIM to image fine structures in addition to providing quantitative data that cannot be obtained by traditional bright field microscopy. PMID:26334858

  16. Chaotic eigenfunctions in phase space

    CERN Document Server

    Nonnenmacher, S

    1997-01-01

    We study individual eigenstates of quantized area-preserving maps on the 2-torus which are classically chaotic. In order to analyze their semiclassical behavior, we use the Bargmann-Husimi representations for quantum states, as well as their stellar parametrization, which encodes states through a minimal set of points in phase space (the constellation of zeros of the Husimi density). We rigorously prove that a semiclassical uniform distribution of Husimi densities on the torus entails a similar equidistribution for the corresponding constellations. We deduce from this property a universal behavior for the phase patterns of chaotic Bargmann eigenfunctions, which reminds of the WKB approximation for eigenstates of integrable systems (though in a weaker sense). In order to obtain more precise information on ``chaotic eigenconstellations", we then model their properties by ensembles of random states, generalizing former results on the 2-sphere to the torus geometry. This approach yields statistical predictions fo...

  17. Fiber bundle phase conjugate mirror

    Science.gov (United States)

    Ward, Benjamin G.

    2012-05-01

    An improved method and apparatus for passively conjugating the phases of a distorted wavefronts resulting from optical phase mismatch between elements of a fiber laser array are disclosed. A method for passively conjugating a distorted wavefront comprises the steps of: multiplexing a plurality of probe fibers and a bundle pump fiber in a fiber bundle array; passing the multiplexed output from the fiber bundle array through a collimating lens and into one portion of a non-linear medium; passing the output from a pump collection fiber through a focusing lens and into another portion of the non-linear medium so that the output from the pump collection fiber mixes with the multiplexed output from the fiber bundle; adjusting one or more degrees of freedom of one or more of the fiber bundle array, the collimating lens, the focusing lens, the non-linear medium, or the pump collection fiber to produce a standing wave in the non-linear medium.

  18. Electroweak phase transition recent results

    CERN Document Server

    Csikor, Ferenc

    2000-01-01

    Recent results of four-dimensional (4d) lattice simulations on the finite temperature electroweak phase transition (EWPT) are discussed. The phase transition is of first order in the SU(2)-Higgs model below the end point Higgs mass 66.5$\\pm$1.4 GeV. For larger masses a rapid cross-over appears. This result completely agrees with the results of the dimensional reduction approach. Including the full Standard Model (SM) perturbatively the end point is at 72.1$\\pm$1.4 GeV. Combined with recent LEP Higgs mass lower bounds, this excludes any EWPT in the SM. A one-loop calculation of the static potential makes possible a precise comparison of the lattice and perturbative results. Recent 4d lattice studies of the Minimal Supersymmetric SM (MSSM) are also mentioned.

  19. Three-phase Photovoltaic Systems

    DEFF Research Database (Denmark)

    Kerekes, Tamas; Sera, Dezso; Máthé, Lászlo

    2015-01-01

    Photovoltaic technology has experienced unprecedented growth in the last two decades, transforming from mainly off-grid niche generation to a major renewable energy technology, reaching approximately 180 GW of capacity worldwide at the end of 2014. Large photovoltaic power plants interfacing...... the grid through a three-phase power electronic converter are now well on the way to becoming a major player in the power system in many countries. Therefore, this article gives an overview of photovoltaic systems with a focus on three-phase applications, presenting these both from a hardware point of view......, detailing the different photovoltaic inverter structures and topologies as well as discussing the different control layers within a grid-connected photovoltaic plant. Modulation schemes for various photovoltaic inverter topologies, grid synchronization, current control, active and reactive power control...

  20. Automatic Deconvolution And Phase Retrieval

    Science.gov (United States)

    Bates, R. H.; Lane, R. G.

    1988-01-01

    The close relationship between Fourier phase retrieval and blind deconvolution is discussed. In this paper we show how advances made in phase retrieval can be successfully applied to solving problems requiring blind deconvolution. Firstly we describe how Fienup's iterative algorithms can be used as the first stage in a deconvolution strategy. In contrast to earlier direct techniques, which all appear to be very susceptible to noise, the deconvolution algorithm presented herein is capable of image recovery in the presence of appreciable noise. Secondly we discuss an extension to our zero-and-add technique which incorporates the greatly increased informational content in the zeros of multi-dimensional, as opposed to one-dimensional, images. It appears that the concept of zero-sheets can be invoked to improve the robustness of zero-and-add.

  1. Agent review phase one report.

    Energy Technology Data Exchange (ETDEWEB)

    Zubelewicz, Alex Tadeusz; Davis, Christopher Edward; Bauer, Travis LaDell

    2009-12-01

    This report summarizes the findings for phase one of the agent review and discusses the review methods and results. The phase one review identified a short list of agent systems that would prove most useful in the service architecture of an information management, analysis, and retrieval system. Reviewers evaluated open-source and commercial multi-agent systems and scored them based upon viability, uniqueness, ease of development, ease of deployment, and ease of integration with other products. Based on these criteria, reviewers identified the ten most appropriate systems. The report also mentions several systems that reviewers deemed noteworthy for the ideas they implement, even if those systems are not the best choices for information management purposes.

  2. Phase Aberrations in Diffraction Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Marchesini, S; Chapman, H N; Barty, A; Howells, M R; Spence, J H; Cui, C; Weierstall, U; Minor, A M

    2005-09-29

    In coherent X-ray diffraction microscopy the diffraction pattern generated by a sample illuminated with coherent x-rays is recorded, and a computer algorithm recovers the unmeasured phases to synthesize an image. By avoiding the use of a lens the resolution is limited, in principle, only by the largest scattering angles recorded. However, the imaging task is shifted from the experiment to the computer, and the algorithm's ability to recover meaningful images in the presence of noise and limited prior knowledge may produce aberrations in the reconstructed image. We analyze the low order aberrations produced by our phase retrieval algorithms. We present two methods to improve the accuracy and stability of reconstructions.

  3. Brain Performance versus Phase Transitions.

    Science.gov (United States)

    Torres, Joaquín J; Marro, J

    2015-07-20

    We here illustrate how a well-founded study of the brain may originate in assuming analogies with phase-transition phenomena. Analyzing to what extent a weak signal endures in noisy environments, we identify the underlying mechanisms, and it results a description of how the excitability associated to (non-equilibrium) phase changes and criticality optimizes the processing of the signal. Our setting is a network of integrate-and-fire nodes in which connections are heterogeneous with rapid time-varying intensities mimicking fatigue and potentiation. Emergence then becomes quite robust against wiring topology modification--in fact, we considered from a fully connected network to the Homo sapiens connectome--showing the essential role of synaptic flickering on computations. We also suggest how to experimentally disclose significant changes during actual brain operation.

  4. Phase Equilibria in the Fe-Mo-Ti Ternary System at 1173 K (900 °C) and 1023 K (750 °C)

    Science.gov (United States)

    Knowles, A. J.; Jones, N. G.; Jones, C. N.; Stone, H. J.

    2017-09-01

    Alloys with fine-scale eutectic microstructures comprising Ti-based A2 and TiFe B2 phases have been shown to have excellent mechanical properties. In this study, the potential of alloys with further refined A2-B2 microstructures formed through solid-state precipitation has been explored by analyzing a series of six alloys within the Fe-Mo-Ti ternary system. Partial isothermal sections of this system at 1173 K (900 °C) and 1023 K (750 °C) were constructed, from which the ternary solubility limits of the A2 (Ti, Mo), B2 TiFe, D85 Fe7Mo6, and C14 Fe2Ti phases were determined. With these data, the change in solubility of Fe in the A2 phase with temperature, which provides the driving force for precipitation of B2 TiFe, was determined and used to predict the maximum potential volume fraction of B2 TiFe precipitates that may be formed in an A2 (Ti, Mo) matrix.

  5. Phase variations in Bifidobacterium animalis.

    Science.gov (United States)

    Biavati, B; Crociani, F; Mattarelli, P; Scardovi, V

    1992-07-01

    Strains isolated from rabbit, chicken, and rat feces and from sewage and fermented milk products, all identified as Bifidobacterium animalis, were found to show phase variations in colony appearance and in cellular morphology. The rate of transition in a switching system from opaque to transparent colonies and vice versa was determined. Differences in protein components and in penicillin-binding proteins (PBPs) of the cells from different colony types are shown.

  6. Phase exposure-dependent exchange

    Science.gov (United States)

    Ginn, T. R.; Schreyer, L. G.; Zamani, K.

    2017-01-01

    Solutes and suspended material often experience delays during exchange between phases one of which may be moving. Consequently transport often exhibits combined effects of advection/dispersion, and delays associated with exchange between phases. Such processes are ubiquitous and include transport in porous/fractured media, watersheds, rivers, forest canopies, urban infrastructure systems, and networks. Upscaling approaches often treat the transport and delay mechanisms together, yielding macroscopic "anomalous transport" models. When interaction with the immobile phase is responsible for the delays, it is not the transport that is anomalous, but the lack of it, due to delays. We model such exchanges with a simple generalization of first-order kinetics completely independent of transport. Specifically, we introduce a remobilization rate coefficient that depends on the time in immobile phase. Memory-function formulations of exchange (with or without transport) can be cast in this framework, and can represent practically all time-nonlocal mass balance models including multirate mass transfer and its equivalent counterparts in the continuous time random walk and time-fractional advection dispersion formalisms, as well as equilibrium exchange. Our model can address delayed single-/multievent remobilizations as in delay-differential equations and periodic remobilizations that may be useful in sediment transport modeling. It is also possible to link delay mechanisms with transport if so desired, or to superpose an additional source of nonlocality through the transport operator. This approach allows for mechanistic characterization of the mass transfer process with measurable parameters, and the full set of processes representable by these generalized kinetics is a new open question.

  7. Symmetry structure and phase transitions

    Indian Academy of Sciences (India)

    2 µ2(σ2 +π2) + 1. 4λ(σ2 +π2)2. (2). For µ2. 0 chiral symmetry is spontaneously broken. Theσ field can be used to represent the quark condensate, the order parameter for chiral phase transition and the pions are the. Goldstone bosons. At the tree level the sigma, pion and the quark masses are given by m2 σ =3λσ2 cl µ2; m2.

  8. Impulsive Phase Transport. Chapter 3,

    Science.gov (United States)

    1988-03-30

    with extensive UV coordinated through the SMY (Svestka, Rust, and Dryer line spectroscopy. Contemporarily though not simultane- 1982). Ground support...calculations of the production of the non- the best job of explaining the wide variety of impulsive-phase thermal red shifted La line by capture processes on...slow if the injection occurred over many sub-resolution elements down. Second. there is strong local heating produced near (a "’ pepper -pot" scenario

  9. Quantum Shuttle in Phase Space

    DEFF Research Database (Denmark)

    Novotny, Tomas; Donarini, Andrea; Jauho, Antti-Pekka

    2003-01-01

    Abstract: We present a quantum theory of the shuttle instability in electronic transport through a nanostructure with a mechanical degree of freedom. A phase space formulation in terms of the Wigner function allows us to identify a crossover from the tunneling to the shuttling regime, thus...... extending the previously found classical results to the quantum domain. Further, a new dynamical regime is discovered, where the shuttling is driven exclusively by the quantum noise....

  10. The Bi-Phase Nozzle.

    Science.gov (United States)

    1981-09-01

    is the key element in the Bi-phase engine concept. While initially it may appear that the design of the nozzle profile is quite straight forward...the optimum nozzle profile has an elongated throat region, that the required shape is insensitive to drop diameter and nozzle length, and that the...theinlet (1/3 of the over- all length). The nozzle is constructed by "sandwiching" two inch thick machined aluminum nozzle profile plates between h

  11. Final Report: Sensorpedia Phase 3

    Energy Technology Data Exchange (ETDEWEB)

    Gorman, Bryan L [ORNL; Resseguie, David R [ORNL

    2011-02-01

    This report is a summary of the Oak Ridge National Laboratory s (ORNL s) Phase 3 development of Sensorpedia, a sensor information sharing platform. Sensorpedia is ORNL s Wikipedia for Sensors. The overall goal of Sensorpedia is to enable global scale sensor information sharing for scientific research, national security and defense, public health and safety, emergency preparedness and response, and general community awareness and outreach.

  12. QCD Phase Transitions, Volume 15

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, T.; Shuryak, E.

    1999-03-20

    The title of the workshop, ''The QCD Phase Transitions'', in fact happened to be too narrow for its real contents. It would be more accurate to say that it was devoted to different phases of QCD and QCD-related gauge theories, with strong emphasis on discussion of the underlying non-perturbative mechanisms which manifest themselves as all those phases. Before we go to specifics, let us emphasize one important aspect of the present status of non-perturbative Quantum Field Theory in general. It remains true that its studies do not get attention proportional to the intellectual challenge they deserve, and that the theorists working on it remain very fragmented. The efforts to create Theory of Everything including Quantum Gravity have attracted the lion share of attention and young talent. Nevertheless, in the last few years there was also a tremendous progress and even some shift of attention toward emphasis on the unity of non-perturbative phenomena. For example, we have seen some efforts to connect the lessons from recent progress in Supersymmetric theories with that in QCD, as derived from phenomenology and lattice. Another example is Maldacena conjecture and related development, which connect three things together, string theory, super-gravity and the (N=4) supersymmetric gauge theory. Although the progress mentioned is remarkable by itself, if we would listen to each other more we may have chance to strengthen the field and reach better understanding of the spectacular non-perturbative physics.

  13. Phase change material storage heater

    Science.gov (United States)

    Goswami, D. Yogi; Hsieh, Chung K.; Jotshi, Chand K.; Klausner, James F.

    1997-01-01

    A storage heater for storing heat and for heating a fluid, such as water, has an enclosure defining a chamber therein. The chamber has a lower portion and an upper portion with a heating element being disposed within the enclosure. A tube through which the fluid flows has an inlet and an outlet, both being disposed outside of the enclosure, and has a portion interconnecting the inlet and the outlet that passes through the enclosure. A densely packed bed of phase change material pellets is disposed within the enclosure and is surrounded by a viscous liquid, such as propylene glycol. The viscous liquid is in thermal communication with the heating element, the phase change material pellets, and the tube and transfers heat from the heating element to the pellets and from the pellets to the tube. The viscous fluid has a viscosity so that the frictional pressure drop of the fluid in contact with the phase change material pellets substantially reduces vertical thermal convection in the fluid. As the fluid flows through the tube heat is transferred from the viscous liquid to the fluid flowing through the tube, thereby heating the fluid.

  14. CERN openlab enters new phase

    CERN Document Server

    Katarina Anthony

    2012-01-01

    The newest phase of CERN’s openlab framework was inaugurated this week during a meeting of the openlab partners. This phase will last three years and will bring together existing openlab partners and a new contributor: Huawei.   Group picture taken at the first CERN openlab IV annual Board of Sponsors meeting, in the presence of the CERN Director-General, the partners and the openlab team members. © Fons Rademakers (CERN Photo Club). Eleven years ago, the creation of the CERN openlab created a long-term link between industrial partners and the Organization. Its framework has allowed industry to carry out large-scale IT research and development in an open atmosphere – an “Open Lab”, if you will. For CERN, openlab has contributed to giving the computing centre and, more broadly, the LHC community, the opportunity to ensure that the next generation of services and products is suitable to their needs. Now entering its fourth phase, openlab will ...

  15. Phase diagram of ammonium nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Dunuwille, Mihindra; Yoo, Choong-Shik, E-mail: csyoo@wsu.edu [Department of Chemistry and Institute for Shock Physics, Washington State University, Pullman, Washington 99164 (United States)

    2013-12-07

    Ammonium Nitrate (AN) is a fertilizer, yet becomes an explosive upon a small addition of chemical impurities. The origin of enhanced chemical sensitivity in impure AN (or AN mixtures) is not well understood, posing significant safety issues in using AN even today. To remedy the situation, we have carried out an extensive study to investigate the phase stability of AN and its mixtures with hexane (ANFO–AN mixed with fuel oil) and Aluminum (Ammonal) at high pressures and temperatures, using diamond anvil cells (DAC) and micro-Raman spectroscopy. The results indicate that pure AN decomposes to N{sub 2}, N{sub 2}O, and H{sub 2}O at the onset of the melt, whereas the mixtures, ANFO and Ammonal, decompose at substantially lower temperatures. The present results also confirm the recently proposed phase IV-IV{sup ′} transition above 17 GPa and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400°C.

  16. Metastable Phases in Ice Clouds

    Science.gov (United States)

    Weiss, Fabian; Baloh, Philipp; Kubel, Frank; Hoelzel, Markus; Parker, Stewart; Grothe, Hinrich

    2014-05-01

    Polar Stratospheric Clouds and Cirrus Clouds contain both, pure water ice and phases of nitric acid hydrates. Preferentially for the latter, the thermodynamically stable phases have intensively been investigated in the past (e.g. nitric acid trihydrate, beta-NAT). As shown by Peter et al. [1] the water activity inside clouds is higher than expected, which might be explained by the presence of metastable stable phases (e.g. cubic ice). However, also metastable nitric acid hydrates might be important due to the inherent non-equilibrium freezing conditions in the upper atmosphere. The delta ice theory of Gao et al. [2] presents a model approach to solve this problem by involving both metastable ice and NAT as well. So it is of high interest to investigate the metastable phase of NAT (i.e. alpha-NAT), the structure of which was unknown up to the presence. In our laboratory a production procedure for metastable alpha-NAT has been developed, which gives access to neutron diffraction and X-ray diffraction measurements, where sample quantities of several Gramm are required. The diffraction techniques were used to solve the unknown crystalline structure of metastable alpha-NAT, which in turn allows the calculation of the vibrational spectra, which have also been recorded by us in the past. Rerefences [1] Peter, T., C. Marcolli, P. Spichtinger, T. Corti, M. B. Baker, and T. Koop. When dry air is too humid. Science, 314:1399-1402, 2006. [2] Gao, R., P. Popp, D. Fahey, T. Marcy, R. L. Herman, E. Weinstock, D. Baumgardener, T. Garrett, K. Rosenlof, T. Thompson, T. P. Bui, B. Ridley, S. C. Wofsy, O. B. Toon, M. Tolbert, B. Kärcher, Th. Peter, P. K. Hudson, A. Weinheimer, and A. Heymsfield. Evidence That Nitric Acid Increases Relative Humidity in Low-Temperature Cirrus Clouds, Science, 303:516-520, 2004. [3] Tizek, H., E. Knözinger, and H. Grothe. Formation and phase distribution of nitric acid hydrates in the mole fraction range xHNO3<0.25: A combined XRD and IR study, PCCP, 6

  17. Phases definition in marketing export process

    Directory of Open Access Journals (Sweden)

    Rajković Dragan

    2004-01-01

    Full Text Available The result of export marketing process depends on its five phases. The first phase-revision of export capacities, inner view on advantages and defects of company concerning export possibilities. The second phase-identification of export strategy market penetration. The forth phase-preparing for the marketing campaign (action. The fifth phase-carrying out the above mentioned activities. This study shows the structure and contents of the mentioned phases. At the end, export marketing analyzed DPV is given as the example.

  18. Phase and structural transformations in magnetorheological suspensions

    Science.gov (United States)

    Iskakova, L. Yu.; Romanchuk, A. P.; Zubarev, A. Yu.

    2006-07-01

    Particle condensation in magnetorheological suspensions (MRS) under external magnetic field is studied theoretically. It is shown that the bulk condensation of particles into dense phases is preceded by the formation of fairly long chain aggregates. Phase transition occurs as a condensation of such chains due to their magnetic interaction. In thin layers of MRS, placed into the normal magnetic field, scenario of the phase transition differs essentially from that in infinite volumes of these systems. Equilibrium state of the system after the phase transition corresponds to the formation of ensemble of discrete domains of the dense phase rather than to separation into two massive phases as it takes place in infinite media.

  19. Spiral phase contrast imaging in microscopy.

    Science.gov (United States)

    Fürhapter, Severin; Jesacher, Alexander; Bernet, Stefan; Ritsch-Marte, Monika

    2005-02-07

    We demonstrate an optical method for edge contrast enhancement in light microscopy. The method is based on holographic Fourier plane filtering of the microscopic image with a spiral phase element (also called vortex phase or helical phase filter) displayed as an off-axis hologram at a computer controlled high resolution spatial light modulator (SLM) in the optical imaging pathway. The phase hologram imprints a helical phase term of the form exp(i phi) on the diffracted light field in its Fourier plane. In the image plane, this results in a strong and isotropic edge contrast enhancement for both amplitude and phase objects.

  20. Stochastic Kuramoto oscillators with discrete phase states

    Science.gov (United States)

    Jörg, David J.

    2017-09-01

    We present a generalization of the Kuramoto phase oscillator model in which phases advance in discrete phase increments through Poisson processes, rendering both intrinsic oscillations and coupling inherently stochastic. We study the effects of phase discretization on the synchronization and precision properties of the coupled system both analytically and numerically. Remarkably, many key observables such as the steady-state synchrony and the quality of oscillations show distinct extrema while converging to the classical Kuramoto model in the limit of a continuous phase. The phase-discretized model provides a general framework for coupled oscillations in a Markov chain setting.

  1. Investigation on Long-term Creep Rupture Properties and Microstructure Stability of Fe-Ni based Alloy Ni-23Cr-7W at 700°C

    DEFF Research Database (Denmark)

    Tokairin, Tsuyoshi; Dahl, Kristian Vinter; Danielsen, Hilmar Kjartansson

    2013-01-01

    Long-term creep rupture properties and microstructural stability of Fe–Ni based alloy Ni–23Cr–7W (HR6W, ASME Code Case 2684) were experimentally investigated. Crept specimens at 700 °C for durations up to 37,667 h were chosen, the microstructure evolution during creep was characterized. Besides...... for the main strengthening precipitate, Laves phase. The alloy was proven to have good microstructural stability without observable coarsening of strengthening precipitates during long-term creep up to around 37,667 h. It was also verified that the growth kinetics of Laves phase can be well described...

  2. Analysis of PTA hardfacing with CoCrWC and CoCrMoSi alloys

    OpenAIRE

    Adriano Scheid; Ana Sofia Clímaco Monteiro de Oliveira

    2013-01-01

    CoCrWC alloys are widely used to protect components that operate under wear and high temperature environments. Enhanced performance has been achieved with the CoCrMoSi alloys but processing this alloy system is still a challenge due to the presence of the brittle Laves phase, particularly when welding is involved. This work evaluated Plasma Transferred Arc coatings processed with the Co-based alloy CoMoCrSi - Tribaloy T400, reinforced with Laves phase, comparing its weldability to the CoCrWC ...

  3. Thermodynamic and kinetic modelling: creep resistant materials

    DEFF Research Database (Denmark)

    Hald, John; Korcakova, L.; Danielsen, Hilmar Kjartansson

    2008-01-01

    The use of thermodynamic and kinetic modelling of microstructure evolution in materials exposed to high temperatures in power plants is demonstrated with two examples. Precipitate stability in martensitic 9–12%Cr steels is modelled including equilibrium phase stability, growth of Laves phase...

  4. Hydrogen absorption/desorption characteristics of room temperature ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The present communication deals with the hydrogen storage characteristics of C15 laves phase. ZrMn2–xNix system tailored within the x values of 1\\25 to 1\\50. Drastic variations in thermodynamics of the hydride phase is observed for any little changes of concentration x within this narrow range. The most prom-.

  5. Light scattering near phase transitions

    CERN Document Server

    Cummins, HZ

    1983-01-01

    Since the development of the laser in the early 1960's, light scattering has played an increasingly crucial role in the investigation of many types of phase transitions and the published work in this field is now widely dispersed in a large number of books and journals.A comprehensive overview of contemporary theoretical and experimental research in this field is presented here. The reviews are written by authors who have actively contributed to the developments that have taken place in both Eastern and Western countries.

  6. Phase transitions and critical phenomena

    CERN Document Server

    Domb, Cyril

    2001-01-01

    The field of phase transitions and critical phenomena continues to be active in research, producing a steady stream of interesting and fruitful results. It has moved into a central place in condensed matter studies.Statistical physics, and more specifically, the theory of transitions between states of matter, more or less defines what we know about 'everyday' matter and its transformations.The major aim of this serial is to provide review articles that can serve as standard references for research workers in the field, and for graduate students and others wishing to obtain reliable in

  7. Phased Arrays 1985 Symposium - Proceedings

    Science.gov (United States)

    1985-08-01

    diameter to approximately 80-100 mm (3-4 inches) using liquid encapsulated Czochralski growth techniques [22]. Semi- insulating InP wafers are limited...34 \\ .185 , gi vingc the phase shiftr, a size of .240" x .185". Test of the inividual bits ’ro’w Ibreadboard wafers yielded the .elluwinq results. Fniase...collect unevenly at grain boundaries and to produce explosive grain growth . This grain growth may produce rather large macropores of such a size as to be

  8. Passive longitudinal phase space linearizer

    Directory of Open Access Journals (Sweden)

    P. Craievich

    2010-03-01

    Full Text Available We report on the possibility to passively linearize the bunch compression process in electron linacs for the next generation x-ray free electron lasers. This can be done by using the monopole wakefields in a dielectric-lined waveguide. The optimum longitudinal voltage loss over the length of the bunch is calculated in order to compensate both the second-order rf time curvature and the second-order momentum compaction terms. Thus, the longitudinal phase space after the compression process is linearized up to a fourth-order term introduced by the convolution between the bunch and the monopole wake function.

  9. Solid phase microextraction field kit

    Science.gov (United States)

    Nunes, Peter J.; Andresen, Brian D.

    2005-08-16

    A field kit for the collection, isolation and concentration of trace amounts of high explosives (HE), biological weapons (BW) and chemical weapons (CW) residues in air, soil, vegetation, swipe, and liquid samples. The field kit includes a number of Solid Phase Microextraction (SPME) fiber and syringe assemblies in a hermetically sealed transportation container or tubes which includes a sampling port, a number of extra SPME fiber and syringe assemblies, the fiber and syringe assemblies including a protective cap for the fiber, and an extractor for the protective cap, along with other items including spare parts, protective glove, and an instruction manual, all located in an airtight container.

  10. Reliability in the design phase

    Energy Technology Data Exchange (ETDEWEB)

    Siahpush, A.S.; Hills, S.W.; Pham, H. (EG and G Idaho, Inc., Idaho Falls, ID (United States)); Majumdar, D. (USDOE Idaho Field Office, Idaho Falls, ID (United States))

    1991-12-01

    A study was performed to determine the common methods and tools that are available to calculated or predict a system's reliability. A literature review and software survey are included. The desired product of this developmental work is a tool for the system designer to use in the early design phase so that the final design will achieve the desired system reliability without lengthy testing and rework. Three computer programs were written which provide the first attempt at fulfilling this need. The programs are described and a case study is presented for each one. This is a continuing effort which will be furthered in FY-1992. 10 refs.

  11. Reliability in the design phase

    Energy Technology Data Exchange (ETDEWEB)

    Siahpush, A.S.; Hills, S.W.; Pham, H. [EG and G Idaho, Inc., Idaho Falls, ID (United States); Majumdar, D. [USDOE Idaho Field Office, Idaho Falls, ID (United States)

    1991-12-01

    A study was performed to determine the common methods and tools that are available to calculated or predict a system`s reliability. A literature review and software survey are included. The desired product of this developmental work is a tool for the system designer to use in the early design phase so that the final design will achieve the desired system reliability without lengthy testing and rework. Three computer programs were written which provide the first attempt at fulfilling this need. The programs are described and a case study is presented for each one. This is a continuing effort which will be furthered in FY-1992. 10 refs.

  12. Experimental Blade Research - phase 2

    DEFF Research Database (Denmark)

    Eder, Martin Alexander; Branner, Kim; Berring, Peter

    This report is a summary of the results obtained in the project: Experimental Blade Research – phase 2 (EBR2). The project was supported by the Danish Energy Authority through the 2010 Energy Technology Development and Demonstration Program (EUDP 2010-II) and has journal no. 64011-0006. The project...... has been running from spring 2011 to the end of 2014. Being a summary report, this report only contains a collection of the research topics and the major results. For more details, see the publications listed at the end of this report....

  13. Phase Change Fabrics Control Temperature

    Science.gov (United States)

    2009-01-01

    Originally featured in Spinoff in 1997, Outlast Technologies Inc. (formerly Gateway Technologies Inc.) has built its entire product line on microencapsulated phase change materials, developed in Small Business Innovation Research (SBIR) contracts with Johnson Space Center after initial development for the U.S. Air Force. The Boulder, Colorado-based company acquired the exclusive patent rights and now integrates these materials into textiles or onto finished apparel, providing temperature regulation in bedding materials and a full line of apparel for both ordinary and extreme conditions.

  14. Phase transitions and critical phenomena

    CERN Document Server

    Domb, Cyril

    2000-01-01

    The field of phase transitions and critical phenomena continues to be active in research, producing a steady stream of interesting and fruitful results. No longer an area of specialist interest, it has acquired a central focus in condensed matter studies. The major aim of this serial is to provide review articles that can serve as standard references for research workers in the field, and for graduate students and others wishing to obtain reliable information on important recent developments.The two review articles in this volume complement each other in a remarkable way. Both deal with what m

  15. Gibbs measures and phase transitions

    CERN Document Server

    Georgii, Hans-Otto

    2011-01-01

    From a review of the first edition: ""This book […] covers in depth a broad range of topics in the mathematical theory of phase transition in statistical mechanics. […] It is in fact one of the author's stated aims that this comprehensive monograph should serve both as an introductory text and as a reference for the expert."" (F. Papangelou, Zentralblatt MATH) The second edition has been extended by a new section on large deviations and some comments on the more recent developments in the area.

  16. QPSK regeneration without active phase-locking

    DEFF Research Database (Denmark)

    Kjøller, Niels-Kristian; Da Ros, Francesco; Røge, Kasper Meldgaard

    2016-01-01

    QPSK regeneration without active phase stabilization is investigated in numerical simulations. We propose an improved scheme for phase-locking free QPSK regeneration showing significant improvements in the error vector magnitude of the signal....

  17. Quantitative phase measurements using optical quadrature microscopy.

    Science.gov (United States)

    Rockward, Willie S; Thomas, Anthony L; Zhao, Bing; Dimarzio, Charles A

    2008-04-01

    Imaging of phase or optical path length is becoming more important with the development of better imaging systems, computational algorithms, faster computers, and a greater interest in the imaging of transparent objects. Early phase imaging involved qualitative imaging of phase gradients. New computational algorithms can be used to extract some quantitative phase imaging from these techniques. In contrast, new hardware has enabled full-field quantitative phase imaging on a practical and cost-effective scale. We explore a quantitative comparison between two techniques for imaging phase. In the first technique, phase is recovered from a pair of differential interference contrast images, and in the second technique, phase is measured pixel-by-pixel interferometrically. It is shown, experimentally, that the overall results are similar, but each technique has its own advantages and disadvantages.

  18. Phase-field model of eutectic growth

    Energy Technology Data Exchange (ETDEWEB)

    Karma, A. (Physics Department, Northeastern University, Boston, Massachusetts 02115 (United States))

    1994-03-01

    A phase-field model which describes the solidification of a binary eutectic alloy with a simple symmetric phase diagram is introduced and the sharp-interface limit of this model is explored both analytically and numerically.

  19. PAN Localization - phase II | IDRC - International Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Outputs. Reports. Phase II - Research Synthesis Phase - 1st May 2010 to 31st March 2012. Papers. Outcome mapping learning community : newsletter no. 2, 2009. Journal articles. Maria Ng conferred medal by Cambodian government ...

  20. Phase sorting wave-particle correlator

    Science.gov (United States)

    Kletzing, C. A.; LaBelle, J.; Bounds, S. R.; Dolan, J.; Kaeppler, S. R.; Dombrowski, M.

    2017-02-01

    Wave-particle correlations, particularly of Langmuir waves and electrons, have been the subject of significant interest extending back to the 1970s. Often, these correlations have been simply observing modulation of the electrons at the plasma frequency with no phase resolution. The first phase-resolving correlators were developed at UC Berkeley in the late 1980s and reported by Ergun in the early 1990s. A design is presented which further improves on phase resolution in correlations of Langmuir waves and electrons with phase resolution of 22.5°. In this technique, a phase-locked loop (PLL) is used to lock onto the wave and subdivide the phase. Electrons are sorted on-the-fly as they arrive into the phase bins. Discussed are details of accurate timing, testing, and calibration of this system as well as results from rocket flights in which statistically significant phase correlations have been observed.

  1. The Relative Phase Asynchronization between Sunspot Numbers ...

    Indian Academy of Sciences (India)

    /fulltext/joaa/032/03/0401-0409 ... which means that phase difference also existed between the two hemispheres. Moreover, the phase difference between the two hemispheres exhibits a periodical behaviour. Our results seem to support the ...

  2. Purification of biomaterials by phase partitioning

    Science.gov (United States)

    Harris, J. M.

    1984-01-01

    A technique which is particularly suited to microgravity environments and which is potentially more powerful than electrophoresis is phase partitioning. Phase partitioning is purification by partitioning between the two immiscible aqueous layers formed by solution of the polymers poly(ethylene glycol) and dextran in water. This technique proved to be very useful for separations in one-g but is limited for cells because the cells are more dense than the phase solutions thus tend to sediment to the bottom of the container before reaching equilibrium with the preferred phase. There are three phases to work in this area: synthesis of new polymers for affinity phase partitioning; development of automated apparatus for ground-based separations; and design of apparatus for performing simple phase partitioning space experiments, including examination of mechanisms for separating phases in the absence of gravity.

  3. Low Cost Phased Array Antenna System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — JEM Engineering proved the technical feasibility of the FlexScan array?a very low-cost, highly-efficient, wideband phased array antenna?in Phase I, and stands ready...

  4. Lipid Bilayers: Clusters, Domains and Phases

    OpenAIRE

    Ackerman, David G.; Feigenson, Gerald W.

    2015-01-01

    In this chapter we discuss the complex mixing behavior of plasma membrane lipids. To do so, we first introduce the plasma membrane and membrane mixtures often used to model its complexity. We then discuss the nature of lipid phase behavior in bilayers and the distinction between these phases and other manifestations of nonrandom mixing found in one-phase mixtures, such as clusters, micelles, and microemulsions. Finally, we demonstrate the applicability of Gibbs phase diagrams to the study of ...

  5. Phase-vanishing halolactonization of neat substrates

    OpenAIRE

    Windmon, Nicole; Dragojlovic, Veljko

    2008-01-01

    Summary Phase-vanishing reactions are triphasic reactions which involve a reagent, a liquid perfluoroalkane as a phase screen and a substrate. The perfluoroalkane does not dissolve any of the reactants and is used to separate them. Halolactonization of neat substrates under phase-vanishing conditions avoids use of both solvents and basic reaction conditions. Both γ,δ-alkenoic acids as well as the corresponding methyl esters are suitable substrates for phase-vanishing halolactonizations. The r...

  6. Phase equilibria basic principles, applications, experimental techniques

    CERN Document Server

    Reisman, Arnold

    2013-01-01

    Phase Equilibria: Basic Principles, Applications, Experimental Techniques presents an analytical treatment in the study of the theories and principles of phase equilibria. The book is organized to afford a deep and thorough understanding of such subjects as the method of species model systems; condensed phase-vapor phase equilibria and vapor transport reactions; zone refining techniques; and nonstoichiometry. Physicists, physical chemists, engineers, and materials scientists will find the book a good reference material.

  7. Four Phase Methodology for Developing Secure Software

    OpenAIRE

    Carlos Gonzalez-Flores; Ernesto Liñan-García

    2016-01-01

    A simple and robust approach for developing secure software. A Four Phase methodology consists in developing the non-secure software in phase one, and for the next three phases, one phase for each of the secure developing types (i.e. self-protected software, secure code transformation, and the secure shield). Our methodology requires first the determination and understanding of the type of security level needed for the software. The methodology proposes the use of several teams to accomplish ...

  8. Signature of Topological Phases in Zitterbewegung

    KAUST Repository

    Ghosh, Sumit

    2016-09-02

    We have studied the Zitterbewegung effect on an infinite two-dimensional sheet with honeycomb lattice. By tuning the perpendicular electric field and the magnetization of the sheet, it can enter different topological phases. We have shown that the phase and magnitude of Zitterbewegung effect, i.e., the jittering motion of electron wavepackets, correlates with the various topological phases. The topological phase diagram can be reconstructed by analyzing these features. Our findings are applicable to materials like silicene, germanene, stanene, etc.

  9. Origins of Kerr phase and orientational phase in polymer-dispersed liquid crystal

    Science.gov (United States)

    Chang, Chia-Ming; Lin, Yi-Hsin; Reshetnyak, Victor; Park, Chui Ho; Manda, Ramesh; Lee, Seung Hee

    2017-08-01

    The anisotropic properties of nematic liquid crystals result in polarization dependency which leads to requirement of at least a polarizer in liquid crystal photonic devices. To develop polarizer free phase modulation, Kerr effect is one of the path. The phase modulation in polymer dispersed liquid crystals (PDLCs) is shown to have two parts: Kerr phase, which is the optical phase modulation linearly proportional to a square of electric field, and orientational phase. However, many puzzles are still under investigation: the origins of Kerr phase, the relation between Kerr phase and orientational phase, and how two-steps of electro-optical (EO) response relates to Kerr phase and orientational phase. We investigated the origins of Kerr phase and orientational phase in PDLC and their connection to two-step EO response. In our study, the Kerr phase is a result of LC orientation in the center of LC droplets. The orientational phase attribute to orientation of LC molecules near LC-polymer interfaces. The two phase in PDLC samples are adjustable depending on droplet size. We also found that two-steps EO response existing in small droplet (<33 nm) is related to Kerr phase and orientational phase. A modified PDLC model related to the Kerr phase and orientational phase is also proposed. Besides the conventional features of PDLC, such as polarization independent optical phase shift and response time independent of cell gap, we believe the Kerr phase and orientational phase with different response times ( msec) in PDLC pave a way for designing versatile photonic devices with pure optical phase modulation.

  10. Phase contrast STEM for thin samples: Integrated differential phase contrast

    Energy Technology Data Exchange (ETDEWEB)

    Lazić, Ivan, E-mail: ivan.lazic@fei.com; Bosch, Eric G.T.; Lazar, Sorin

    2016-01-15

    It has been known since the 1970s that the movement of the center of mass (COM) of a convergent beam electron diffraction (CBED) pattern is linearly related to the (projected) electrical field in the sample. We re-derive a contrast transfer function (CTF) for a scanning transmission electron microscopy (STEM) imaging technique based on this movement from the point of view of image formation and continue by performing a two-dimensional integration on the two images based on the two components of the COM movement. The resulting integrated COM (iCOM) STEM technique yields a scalar image that is linear in the phase shift caused by the sample and therefore also in the local (projected) electrostatic potential field of a thin sample. We confirm that the differential phase contrast (DPC) STEM technique using a segmented detector with 4 quadrants (4Q) yields a good approximation for the COM movement. Performing a two-dimensional integration, just as for the COM, we obtain an integrated DPC (iDPC) image which is approximately linear in the phase of the sample. Beside deriving the CTFs of iCOM and iDPC, we clearly point out the objects of the two corresponding imaging techniques, and highlight the differences to objects corresponding to COM-, DPC-, and (HA) ADF-STEM. The theory is validated with simulations and we present first experimental results of the iDPC-STEM technique showing its capability for imaging both light and heavy elements with atomic resolution and a good signal to noise ratio (SNR). - Highlights: • First DPC-based atomic resolution images of potential and charge density are obtained. • This is enabled by integration and differentiation of 2D DPC signals, respectively. • Integrated DPC (iDPC) based on 4 quadrant imaging is compared to iCOM imaging. • Noise analysis and comparison with standard STEM imaging modes is provided. • iDPC allows direct imaging of light (C, N, O …) and heavy (Ga, Au …) atoms together.

  11. Phase-contrast scanning transmission electron microscopy.

    Science.gov (United States)

    Minoda, Hiroki; Tamai, Takayuki; Iijima, Hirofumi; Hosokawa, Fumio; Kondo, Yukihito

    2015-06-01

    This report introduces the first results obtained using phase-contrast scanning transmission electron microscopy (P-STEM). A carbon-film phase plate (PP) with a small center hole is placed in the condenser aperture plane so that a phase shift is introduced in the incident electron waves except those passing through the center hole. A cosine-type phase-contrast transfer function emerges when the phase-shifted scattered waves interfere with the non-phase-shifted unscattered waves, which passed through the center hole before incidence onto the specimen. The phase contrast resulting in P-STEM is optically identical to that in phase-contrast transmission electron microscopy that is used to provide high contrast for weak phase objects. Therefore, the use of PPs can enhance the phase contrast of the STEM images of specimens in principle. The phase shift resulting from the PP, whose thickness corresponds to a phase shift of π, has been confirmed using interference fringes displayed in the Ronchigram of a silicon single crystal specimen. The interference fringes were found to abruptly shift at the edge of the PP hole by π. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. Plane wave imaging using phased array

    NARCIS (Netherlands)

    Volker, A.W.F.

    2014-01-01

    Phased arrays are often used for rapid inspections. Phased arrays can be used to synthesize different wave fronts. For imaging, focused wave fronts are frequently used. In order to build an image, the phased array has to be fired multiple times at the same location. Alternatively, different data

  13. Centrifuge workers study. Phase II, completion report

    Energy Technology Data Exchange (ETDEWEB)

    Wooten, H.D.

    1994-09-01

    Phase II of the Centrifuge Workers Study was a follow-up to the Phase I efforts. The Phase I results had indicated a higher risk than expected among centrifuge workers for developing bladder cancer when compared with the risk in the general population for developing this same type of cancer. However, no specific agent could be identified as the causative agent for these bladder cancers. As the Phase II Report states, Phase I had been limited to workers who had the greatest potential for exposure to substances used in the centrifuge process. Phase II was designed to expand the survey to evaluate the health of all employees who had ever worked in Centrifuge Program Departments 1330-1339 but who had not been interviewed in Phase I. Employees in analytical laboratories and maintenance departments who provided support services for the Centrifuge Program were also included in Phase II. In December 1989, the Oak Ridge Associated Universities (ORAU), now known as Oak Ridge Institute for Science and Education (ORISE), was contracted to conduct a follow-up study (Phase II). Phase H of the Centrifuge Workers Study expanded the survey to include all former centrifuge workers who were not included in Phase I. ORISE was chosen because they had performed the Phase I tasks and summarized the corresponding survey data therefrom.

  14. Compact, common path quantitative phase microscopic techniques ...

    Indian Academy of Sciences (India)

    2014-01-05

    Jan 5, 2014 ... Quantitative phase contrast techniques, which directly provide informa- tion about the phase of the object wavefront, can be used to quantitatively image the object under investigation. Typically, interferometric techniques are used for quantitative phase imaging. 2. Digital holographic microscopy. Holograms ...

  15. Nonequilibrium modeling of three-phase distillation

    NARCIS (Netherlands)

    Higler, A.P.; Chande, R.; Taylor, R.; Baur, R.; Krishna, R.

    2004-01-01

    A nonequilibrium (NEQ) model for a complete three-phase distillation in tray columns is described. The model consists of a set of mass and energy balances for each of the three possible phases present. Mass and heat transfer between these phases is modeled using the Maxwell–Stefan equations.

  16. Solid phase syntheses of oligoureas

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, K.; Linthicum, D.S.; Russell, D.H.; Shin, H.; Shitangkoon, A.; Totani, R.; Zhang, A.J.; Ibarzo, J. [Texas A& M Univ., College Station, TX (United States)

    1997-02-19

    Isocyanates 7 were formed from monoprotected diamines 3 or 6, which in turn can be easily prepared from commercially available N-BOC- or N-FMOC-protected amino acid derivatives. Isocyanates 7, formed in situ, could be coupled directly to a solid support functionalized with amine groups or to amino acids anchored on resins using CH{sub 2}Cl{sub 2} as solvent and an 11 h coupling time at 25 {degree}C. Such couplings afforded peptidomimetics with an N-phthaloyl group at the N-terminus. The optimal conditions identified for removal of the N-phthaloyl group were to use 60% hydrazine in DMF for 1-3 h. Several sequences of amino acids coupled to ureas (`peptidic ureas`) and of sequential urea units (`oligoureas`) were prepared via solid phase syntheses and isolated by HPLC. Partition coefficients were measured for two of these peptidomimetics, and their water solubilities were found to be similar to the corresponding peptides. A small library of 160 analogues of the YGGFL-amide sequence was prepared via Houghten`s tea bag methodology. This library was tested for binding to the anti-{beta}-endorphin monoclonal antibody. Overall, this paper describes methodology for solid phase syntheses of oligourea derivatives with side chains corresponding to some of the protein amino acids. The chemistry involved is ideal for high-throughput syntheses and screening operations. 51 refs., 3 figs., 2 tabs.

  17. SARCOPENIA: DESIGNING PHASE IIB TRIALS

    Science.gov (United States)

    CHUMLEA, WM.C.; CESARI, M.; EVANS, W.J.; FERRUCCI, L.; FIELDING, R.A.; PAHOR, M.; STUDENSKI, S.; VELLAS, B.

    2012-01-01

    Sarcopenia is the age-related involuntary loss of skeletal muscle mass and functionality that can lead to the development of disability, frailty and increased health care costs. The development of interventions aimed at preventing and/or treating sarcopenia is complex, requiring the adoption of assumptions and standards that are not well established scientifically or clinically. A number of investigators and clinicians (both from academia and industry) met in Rome (Italy) in 2009 to develop a consensus definition of sarcopenia. Subsequently, in Albuquerque (New Mexico, USA) in 2010, the same group met again to consider the complex issues necessary for designing Phase II clinical trials for sarcopenia. Current clinical trial data indicate that fat-free mass (FFM) parameters are responsive to physical activity/nutritional treatment modalities over short time periods, but pharmacological trials of sarcopenia have yet to show significant efficacy. In order to conduct a clinical trial within a reasonable time frame, groups that model or display accelerated aging and loss of FFM are necessary. Few studies have used acceptable designs for testing treatment effects, sample sizes or primary outcomes that could provide interpretable findings or effects across studies. Dual energy x ray absorptiometry (DXA) is the measure of choice for assessing FFM, but sufficient time is needed for changes to be detected accurately and reliably. A tool set that would allow clinical, basic and epidemiological research on sarcopenia to advance rapidly toward diagnosis and treatment phases should be those reflecting function and strength. PMID:21623466

  18. Synthesis in the liquid phase

    Energy Technology Data Exchange (ETDEWEB)

    1943-03-11

    Justification is presented for an I.G. Farben patent on synthesis of hydrocarbons from carbon monoxide and hydrogen in the liquid phase. Tracing the history of the process, the report notes that Pier worked out the basic patent in 1928. Duftschmid of Farben/Oppau subsequently worked out a variation of the process using for the fluid medium a synthesis product consisting mainly of products vaporizing in the reaction. The process used fixed-bed catalysts. Ruhrchemie A.G. objected to this patent on grounds that the process was already known. Meanwhile, Michael of Farben/Ludwigshafen devised another variation using mainly a finely distributed sintered catalyst and very fast stirring. The process required a high boiling, practically non-volatile liquid phase to keep the finely distributed catalyst in motion in the liquid during the reaction. A good distribution of carbon monoxide, hydrogen, and catalyst was obtained by having the gases enter either through a filter plate or by a rapid stirring of the liquid. The report concludes that since Michael's process was not for fixed catalysts, it was in no way dependent on the Duftschmid process or on Oppau's patent rights. A detailed chronology of work on the processes is included.

  19. Phase-exchange thermoacoustic engine

    Science.gov (United States)

    Offner, Avshalom; Meir, Avishai; Ramon, Guy Z.; WET Lab Team

    2017-11-01

    Phase-exchange thermoacoustic engines are reliable machines holding great promise in converting heat from low grade heat sources to mechanical or electrical power. In these engines the working fluid is a gas mixture containing one condensable component, decreasing the temperature difference required for ignition and steady state operation. Our experimental setup consists of a vertical acoustic resonator containing a mixture of air-water vapor. Water evaporates near the heat source, condenses at the heat sink and is drawn back down by gravity and capillary forces where it re-evaporates, sustaining a steady state closed thermodynamic cycle. We investigated the stability limit, namely the critical point at which temperature difference in the engine enables onset of self-excited oscillations, and the steady state of the engine. A simple theoretical model was derived, describing mechanisms of irreversible entropy generation and production of acoustic power in such engines. This model captures the essence in the differences between regular and phase-exchange thermoacoustic engines, and shows good agreement with experimental results of stability limit. Steady state results reveal not only a dramatic decrease in temperature difference, but also an increase in engine performances. The authors acknowledge the support from the Nancy and Stephen Grand Technion Energy Program (GTEP).

  20. Galois conjugates of topological phases

    Science.gov (United States)

    Freedman, M. H.; Gukelberger, J.; Hastings, M. B.; Trebst, S.; Troyer, M.; Wang, Z.

    2012-01-01

    Galois conjugation relates unitary conformal field theories and topological quantum field theories (TQFTs) to their nonunitary counterparts. Here we investigate Galois conjugates of quantum double models, such as the Levin-Wen model. While these Galois-conjugated Hamiltonians are typically non-Hermitian, we find that their ground-state wave functions still obey a generalized version of the usual code property (local operators do not act on the ground-state manifold) and hence enjoy a generalized topological protection. The key question addressed in this paper is whether such nonunitary topological phases can also appear as the ground states of Hermitian Hamiltonians. Specific attempts at constructing Hermitian Hamiltonians with these ground states lead to a loss of the code property and topological protection of the degenerate ground states. Beyond this, we rigorously prove that no local change of basis can transform the ground states of the Galois-conjugated doubled Fibonacci theory into the ground states of a topological model whose Hermitian Hamiltonian satisfies Lieb-Robinson bounds. These include all gapped local or quasilocal Hamiltonians. A similar statement holds for many other nonunitary TQFTs. One consequence is that these nonunitary TQFTs do not describe physical realizations of topological phases. In particular, this implies that the “Gaffnian” wave function can not be the ground state of a gapped fractional quantum Hall state.

  1. Theory of the liquid phase

    Energy Technology Data Exchange (ETDEWEB)

    Rank, V.

    1944-01-31

    This report discussed the regularities in the behavior of the liquid phase and illustrated these with a few examples and also discussed a method of testing of hydrogenation behavior of coals. A table was given that contained examples of the behavior of different coals in the liquid phase for the purpose of production of oils of different composition. All tests had been run at 600 atm with iron catalysts, a normal gas throughput, and with about a 50% paste. The remaining independent variables were the temperature, the throughput, and the composition of the pasting oils. When these three requirements were fixed, the conversion of a given coal, yield, composition of the oils produced, gasification, and asphalt production would be definite for a fixed method of working up the residue. Results would vary from coal to coal. As a general rule, the Ruhr coal seemed better suited to gasoline and middle oil production than the Upper Silesian coal. The recycling of oils in a closed cycle was not necessarily the best means to determine the particular method best suited to a given coal because of the possibility of superimposed effects that could obscure the issue. The use of B-bombs with a standard pasting oil was basically more correct in spite of the disadvantages of using a non-continuous process. 2 tables.

  2. Symmetric Topological Phases and Tensor Network States

    Science.gov (United States)

    Jiang, Shenghan

    Classification and simulation of quantum phases are one of main themes in condensed matter physics. Quantum phases can be distinguished by their symmetrical and topological properties. The interplay between symmetry and topology in condensed matter physics often leads to exotic quantum phases and rich phase diagrams. Famous examples include quantum Hall phases, spin liquids and topological insulators. In this thesis, I present our works toward a more systematically understanding of symmetric topological quantum phases in bosonic systems. In the absence of global symmetries, gapped quantum phases are characterized by topological orders. Topological orders in 2+1D are well studied, while a systematically understanding of topological orders in 3+1D is still lacking. By studying a family of exact solvable models, we find at least some topological orders in 3+1D can be distinguished by braiding phases of loop excitations. In the presence of both global symmetries and topological orders, the interplay between them leads to new phases termed as symmetry enriched topological (SET) phases. We develop a framework to classify a large class of SET phases using tensor networks. For each tensor class, we can write down generic variational wavefunctions. We apply our method to study gapped spin liquids on the kagome lattice, which can be viewed as SET phases of on-site symmetries as well as lattice symmetries. In the absence of topological order, symmetry could protect different topological phases, which are often referred to as symmetry protected topological (SPT) phases. We present systematic constructions of tensor network wavefunctions for bosonic symmetry protected topological (SPT) phases respecting both onsite and spatial symmetries.

  3. The Impact of Donor-Acceptor Phase Separation on the Charge Carrier Dynamics in pBTTT:PCBM Photovoltaic Blends

    KAUST Repository

    Gehrig, Dominik W.

    2015-04-07

    The effect of donor–acceptor phase separation, controlled by the donor–acceptor mixing ratio, on the charge generation and recombination dynamics in pBTTT-C14:PC70BM bulk heterojunction photovoltaic blends is presented. Transient absorption (TA) spectroscopy spanning the dynamic range from pico- to microseconds in the visible and near-infrared spectral regions reveals that in a 1:1 blend exciton dissociation is ultrafast; however, charges cannot entirely escape their mutual Coulomb attraction and thus predominantly recombine geminately on a sub-ns timescale. In contrast, a polymer:fullerene mixing ratio of 1:4 facilitates the formation of spatially separated, that is free, charges and reduces substantially the fraction of geminate charge recombination, in turn leading to much more efficient photovoltaic devices. This illustrates that spatially extended donor or acceptor domains are required for the separation of charges on an ultrafast timescale (<100 fs), indicating that they are not only important for efficient charge transport and extraction, but also critically influence the initial stages of free charge carrier formation.

  4. The impact of donor-acceptor phase separation on the charge carrier dynamics in pBTTT:PCBM photovoltaic blends.

    Science.gov (United States)

    Gehrig, Dominik W; Howard, Ian A; Sweetnam, Sean; Burke, Timothy M; McGehee, Michael D; Laquai, Frédéric

    2015-06-01

    The effect of donor-acceptor phase separation, controlled by the donor-acceptor mixing ratio, on the charge generation and recombination dynamics in pBTTT-C14:PC70 BM bulk heterojunction photovoltaic blends is presented. Transient absorption (TA) spectroscopy spanning the dynamic range from pico- to microseconds in the visible and near-infrared spectral regions reveals that in a 1:1 blend exciton dissociation is ultrafast; however, charges cannot entirely escape their mutual Coulomb attraction and thus predominantly recombine geminately on a sub-ns timescale. In contrast, a polymer:fullerene mixing ratio of 1:4 facilitates the formation of spatially separated, that is free, charges and reduces substantially the fraction of geminate charge recombination, in turn leading to much more efficient photovoltaic devices. This illustrates that spatially extended donor or acceptor domains are required for the separation of charges on an ultrafast timescale (<100 fs), indicating that they are not only important for efficient charge transport and extraction, but also critically influence the initial stages of free charge carrier formation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Complex phase dynamics in coupled bursters

    DEFF Research Database (Denmark)

    Postnov, D.E.; Sosnovtseva, Olga; Malova, S.Y.

    2003-01-01

    The phenomenon of phase multistability in the synchronization of two coupled oscillatory systems typically arises when the systems individually display complex wave forms associated, for instance, with the presence of subharmonic components. Alternatively, phase multistability can be caused...... by variations of the phase velocity along the orbit of the individual oscillator. Focusing on the mechanisms underlying the appearance of phase multistability, the paper examines a variety of phase-locked patterns in the bursting behavior of a model of coupled pancreatic cells. In particular, we show how...... the number of spikes per train and the proximity of a neighboring equilibrium point can influence the formation of coexisting regimes....

  6. Lipid bilayers: clusters, domains and phases.

    Science.gov (United States)

    Ackerman, David G; Feigenson, Gerald W

    2015-01-01

    In the present chapter we discuss the complex mixing behaviour of plasma membrane lipids. To do so, we first introduce the plasma membrane and membrane mixtures often used to model its complexity. We then discuss the nature of lipid phase behaviour in bilayers and the distinction between these phases and other manifestations of non-random mixing found in one-phase mixtures, such as clusters, micelles and microemulsions. Finally, we demonstrate the applicability of Gibbs phase diagrams to the study of increasingly complex model membrane systems, with a focus on phase coexistence, morphology and their implications for the cell plasma membrane.

  7. Geometric phase morphology of Jones matrices.

    Science.gov (United States)

    Lopez-Mago, Dorilian; Canales-Benavides, Arturo; Hernandez-Aranda, Raul I; Gutiérrez-Vega, Julio C

    2017-07-15

    We demonstrate an innovative technique based on the Pancharatnam-Berry phase that can be used to determine whether an optical system characterized by a Jones matrix is homogeneous or inhomogeneous, containing orthogonal or nonorthogonal eigenpolarizations, respectively. Homogeneous systems have a symmetric geometric phase morphology showing line dislocations and sets of polarization states with an equal geometric phase. In contrast, the morphology of inhomogeneous systems exhibits phase singularities, where the Pancharatnam-Berry phase is undetermined. The results show an alternative to extract polarization properties such as diattenuation and retardance, and can be used to study the transformation of space-variant polarized beams.

  8. Fidelity analysis of topological quantum phase transitions

    Science.gov (United States)

    Abasto, Damian F.; Hamma, Alioscia; Zanardi, Paolo

    2008-07-01

    We apply the fidelity metric approach to analyze two recently introduced models that exhibit a quantum phase transition to a topologically ordered phase. These quantum models have a known connection to classical statistical mechanical models; we exploit this mapping to obtain the scaling of the fidelity metric tensor near criticality. The topological phase transitions manifest themselves in divergences of the fidelity metric across the phase boundaries. These results provide evidence that the fidelity approach is a valuable tool to investigate novel phases lacking a clear characterization in terms of local order parameters.

  9. Electric field controlled emulsion phase contactor

    Science.gov (United States)

    Scott, Timothy C.

    1995-01-01

    A system for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity.

  10. Quenching Phase Separation by Vapor Deposition Polymerization

    Science.gov (United States)

    Tao, Ran; Anthamatten, Mitchell

    2015-03-01

    Initiated chemical vapor deposition (iCVD) is a solventless, free radical technique predominately used to deposit homogeneous films of linear and crosslinked polymers directly from gas phase feeds. We report a template-free method to fabricate continuous-phase porous polymer films by simultaneous phase separation during iCVD. Phase separation during film growth is achieved by condensing an inert porogen, along with initiator, monomer, and crosslinker. When the vapor mixture transports to the cooled substrate, phase separation occurs along with polymerization and crosslinking, which quench the state of phase separation. The kinetics of spontaneously phase separation can be qualitatively understood on the basis of Cahn-Hilliard theory. A series of films were grown by varying monomer and porogen's degree of saturation. Deposited films were studied by electron microscopy and spectroscopic techniques.

  11. Fourier phase microscopy with white light.

    Science.gov (United States)

    Bhaduri, Basanta; Tangella, Krishnarao; Popescu, Gabriel

    2013-01-01

    Laser-based Fourier phase microscopy (FPM) works on the principle of decomposition of an image field in two spatial components that can be controllably shifted in phase with respect to each other. However, due to the coherent illumination, the contrast in phase images is degraded by speckles. In this paper we present FPM with spatially coherent white light (wFPM), which offers high spatial phase sensitivity due to the low temporal coherence and high temporal phase stability due to common path geometry. Further, by using a fast spatial light modulator (SLM) and a fast scientific-grade complementary metal oxide semiconductor (sCMOS) camera, we report imaging at a maximum rate of 12.5 quantitative phase frames per second with 5.5 mega pixels image size. We illustrate the utility of wFPM as a contrast enhancement as well as dynamic phase measurement method by imaging section of benign colonic glands and red blood cell membrane fluctuation.

  12. Multiple topological phases in phononic crystals

    KAUST Repository

    Chen, Zeguo

    2017-11-20

    We report a new topological phononic crystal in a ring-waveguide acoustic system. In the previous reports on topological phononic crystals, there are two types of topological phases: quantum Hall phase and quantum spin Hall phase. A key point in achieving quantum Hall insulator is to break the time-reversal (TR) symmetry, and for quantum spin Hall insulator, the construction of pseudo-spin is necessary. We build such pseudo-spin states under particular crystalline symmetry (C-6v) and then break the degeneracy of the pseudo-spin states by introducing airflow to the ring. We study the topology evolution by changing both the geometric parameters of the unit cell and the strength of the applied airflow. We find that the system exhibits three phases: quantum spin Hall phase, conventional insulator phase and a new quantum anomalous Hall phase.

  13. Nontrivial Phase Coupling in Polariton Multiplets

    Directory of Open Access Journals (Sweden)

    H. Ohadi

    2016-08-01

    Full Text Available We investigate the phase coupling between spatially separated polariton condensates under nonresonant optical pulsed excitation. In the simple case of two condensates, we observe phase locking either in symmetric or antisymmetric states. We demonstrate that the coupling symmetry depends both on the separation distance and outflow velocity from the condensates. We interpret the observations through stimulated relaxation of polaritons to the phase configuration with the highest occupation. We derive an analytic criterion for the phase locking of a pair-polariton condensate and extend it to polariton multiplets. In the case of three condensates, we predict theoretically and observe experimentally either in-phase locking or the appearance of phase winding with phase differences of ±2π/3 between neighbors. The latter state corresponds to a vortex of winding number ±1 across the three polariton condensates.

  14. Phase Transformation Dynamics in Porous Battery Electrodes

    CERN Document Server

    Ferguson, Todd R

    2014-01-01

    Porous electrodes composed of multiphase active materials are widely used in Li-ion batteries, but their dynamics are poorly understood. Two-phase models are largely empirical, and no models exist for three or more phases. Using a modified porous electrode theory based on non-equilibrium thermodynamics, we show that experimental phase behavior can be accurately predicted from free energy models, without artificially placing phase boundaries or fitting the open circuit voltage. First, we simulate lithium intercalation in porous iron phosphate, a popular two-phase cathode, and show that the zero-current voltage gap, sloping voltage plateau and under-estimated exchange currents all result from size-dependent nucleation and mosaic instability. Next, we simulate porous graphite, the standard anode with three stable phases, and reproduce experimentally observed fronts of color-changing phase transformations. These results provide a framework for physics-based design and control for electrochemical systems with comp...

  15. The eigenvalue problem in phase space.

    Science.gov (United States)

    Cohen, Leon

    2017-07-27

    We formulate the standard quantum mechanical eigenvalue problem in quantum phase space. The equation obtained involves the c-function that corresponds to the quantum operator. We use the Wigner distribution for the phase space function. We argue that the phase space eigenvalue equation obtained has, in addition to the proper solutions, improper solutions. That is, solutions for which no wave function exists which could generate the distribution. We discuss the conditions for ascertaining whether a position momentum function is a proper phase space distribution. We call these conditions psi-representability conditions, and show that if these conditions are imposed, one extracts the correct phase space eigenfunctions. We also derive the phase space eigenvalue equation for arbitrary phase space distributions functions. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  16. Regeneration of phase unlocked serial multiplexed DPSK signals in a single phase sensitive amplifier

    DEFF Research Database (Denmark)

    Guan, Pengyu; Da Ros, Francesco; Kjøller, Niels-Kristian

    2017-01-01

    We demonstrate phase-regeneration of phase unlocked OTDM-DPSK serial signals in a single phase sensitive amplifier through optical cross-phase modulation. The BER of an 8×10 Gbit/s OTDM-DPSK signal is improved by 2 orders of magnitude....

  17. Three-Phase and Six-Phase AC at the Lab Bench

    Science.gov (United States)

    Caplan, George M.

    2009-01-01

    Utility companies generate three-phase electric power, which consists of three sinusoidal voltages with phase angles of 0 degrees, 120 degrees, and 240 degrees. The ac generators described in most introductory textbooks are single-phase generators, so physics students are not likely to learn about three-phase power. I have developed a simple way…

  18. Monolithic phased arrays - Recent advances

    Science.gov (United States)

    Kinzel, Joseph A.

    1991-07-01

    Advances in monolithic phased array technology defined as a solid state array based on GaAs monolithic microwave integrated circuits are reviewed focusing on analytical and experimental work to improve array performance and reliability while reducing the cost. Monolithic array technology is equally applicable to communications and radar systems. In radar applications both transmit and receive functions at the elemental level require a transmit/receive module's physical size to be compatible with 1/2 wave length element spacing. For communication applications, separate aperture are used for transmit and receive to ensure sufficient isolation for full duplex operation. Radar transmitter chains are capable of operating with a saturated power output stage which helps to increase efficiency and minimize DC power. Communication systems place severe linearity constraints on the transmitters and receivers which requires the power amplifier to operate in an ultra-linear fashion.

  19. VESTA Project: Phase 0 report

    Science.gov (United States)

    Perret, A.

    1986-01-01

    This report presents the results of technical studies conducted at CNES/PMF/APS between October 1984 and September 1985 on the VESTA project. These preliminary studies were conducted to establish mission feasibility in terms ofthe trajectory and the scientific objectives, and to determine the type of interfaces which will be required with the Soviets and to measure the magnitude of French participation. A joint French-Soviet report recommends that the project enter phase A, and was approved by CNES and INTERCOSMOS in September, 1985. The mission analysis is made for a mid-1991 launch, and a development schedule for an end-1992 launch is suggested. The decision to postpone the mission was made during the course of the study.

  20. Phase I Final Scientific Report

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Xijia [National Energy Technology Lab. (NETL), Albany, OR (United States); Fetvedt, Jeremy [National Energy Technology Lab. (NETL), Albany, OR (United States); Dimmig, Walker [National Energy Technology Lab. (NETL), Albany, OR (United States)

    2017-10-15

    This Final Scientific Report addresses the accomplishments achieved during Phase I of DE- FE0023985, Coal Syngas Combustor Development for Supercritical CO2 Power Cycles. The primary objective of the project was to develop a coal syngas-fueled combustor design for use with high-pressure, high-temperature, oxy-fuel, supercritical CO2 power cycles, with particular focus given to the conditions required by the Allam Cycle. The primary goals, from the Statement of Project Objectives, were to develop: (1) a conceptual design of a syngas-fueled combustor-turbine block for a 300MWe high-pressure, oxy-fuel, sCO2 power plant; (2) the preliminary design of a 5MWt test combustor; and (3) the definition of a combustor test program. Accomplishments for each of these goals are discussed in this report.

  1. Omnidirectional antenna having constant phase

    Energy Technology Data Exchange (ETDEWEB)

    Sena, Matthew

    2017-04-04

    Various technologies presented herein relate to constructing and/or operating an antenna having an omnidirectional electrical field of constant phase. The antenna comprises an upper plate made up of multiple conductive rings, a lower ground-plane plate, a plurality of grounding posts, a conical feed, and a radio frequency (RF) feed connector. The upper plate has a multi-ring configuration comprising a large outer ring and several smaller rings of equal size located within the outer ring. The large outer ring and the four smaller rings have the same cross-section. The grounding posts ground the upper plate to the lower plate while maintaining a required spacing/parallelism therebetween.

  2. Phase 2 reentry in man

    DEFF Research Database (Denmark)

    Thomsen, P.E.B.; Jørgensen, R.M.; Kanters, J.K.

    2005-01-01

    phase 2 reentry, demonstrated in animal experiments to initiate ventricular extrasystoles, ventricular tachycardia, and ventricular fibrillation, also plays a role in humans. METHODS We examined 18 patients with ventricular extrasystoles and/or ventricular tachycardia by signal averaging of the ECG...... patients undergoing radiofrequency ablation. Eight of the 11 patients had right ventricular outflow tract extrasystoles. RESULTS In six of the seven patients in group A, we demonstrated significant ST-elevation and/or T-wave changes in the sinus beat preceding ventricular extrasystoles compared...... mu V, range 0-1,700) and T-wave changes in the sinus beat prior to ventricular ectopy. In addition, J-point elevation was demonstrated in several cases. In total, significant changes were demonstrated in 15 of the 18 patients studied (83%). CONCLUSION J-point elevation, ST-elevation, and T-wave...

  3. Phase 2 reentry in man

    DEFF Research Database (Denmark)

    Bloch Thomsen, Poul Erik; Joergensen, Rikke Moerch; Kanters, Jørgen Kim

    2005-01-01

    whether phase 2 reentry, demonstrated in animal experiments to initiate ventricular extrasystoles, ventricular tachycardia, and ventricular fibrillation, also plays a role in humans. METHODS: We examined 18 patients with ventricular extrasystoles and/or ventricular tachycardia by signal averaging...... of 11 patients undergoing radiofrequency ablation. Eight of the 11 patients had right ventricular outflow tract extrasystoles. RESULTS: In six of the seven patients in group A, we demonstrated significant ST-elevation and/or T-wave changes in the sinus beat preceding ventricular extrasystoles compared...... muV, range 0-1,700) and T-wave changes in the sinus beat prior to ventricular ectopy. In addition, J-point elevation was demonstrated in several cases. In total, significant changes were demonstrated in 15 of the 18 patients studied (83%). CONCLUSION: J-point elevation, ST-elevation, and T-wave...

  4. Phase transitions in Ising Chains?

    Science.gov (United States)

    Mancini, Ferdinando

    2009-12-01

    An open question in the study of the spin-1/2 Ising model is the solution of the two-dimensional case in the presence of a magnetic field. A possible answer is based on the study of L-coupled linear chains in the limit of large L. Results reported in the literature show that a dimensional crossover from the one to the two dimensional model does not exist. However, what happens if one considers open boundary conditions (BC)? In this article I show that, for an appropriate choice of the BC, a system of L-chains exhibits a ferromagnetic order characterized by a critical temperature which, for zero magnetic field, tends to the Onsager's one as L increases. It is then possible to study the phase diagram in the (h, T) plane and obtain a solution for finite magnetic field.

  5. TEVATRON Phase 1, February, 1980

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    1980-02-01

    This report describes the "Tevatron Phase 1 project at the Fermi National Accelerator Laboratory. The project follows research and development efforts and the earlier Energy Saver project. The Research and Development work has led to the development and fabrication of superconducting· accelerator magnets and installation of a test string of magnets in A sector of the Main-Ring tunnel. The Energy Saver project, authorized in FY79 and now in progress, includes construction of a complete ring of superconducting magnets and their installation in the Main-Ring tunnel. The project includes refrigeration and rf equipment adequate for sustained operation of the ring at a peak energy of 500 GeV, making use of the existing experimental areas....

  6. Polymers in phase change materials

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, M.C.; Brites, M.J.; Alexandre, J.H. [National Lab. for Energy and Geology, Lisbon (Portugal)

    2010-07-01

    Phase Change Materials (PCMs) which are the core of latent heat thermal energy storage systems are currently an area of investigation of increasing interest. Several substances differing in physical and chemical characteristics as well as in thermal behavior have been studied as PCMS{sup 1-3}. In order to meet the requisites of particular systems, auxiliary materials are often used with specific functions. This bibliographic survey shows that polymeric materials have been proposed either as the PCM itself in solid-liquid or solid-solid transitions or to perform auxiliary functions of shape stabilisation and microencapsulation for solid-liquid PCMs. The PCMs have an operating temperature ranging from around 0 C (for the system water/polyacrilamid) to around 127 C (for crosslinked HDPE). (orig.)

  7. Two phase titanium aluminide alloy

    Energy Technology Data Exchange (ETDEWEB)

    Deevi, Seetharama C. (Midlothian, VA); Liu, C. T. (Oak Ridge, TN)

    2001-01-01

    A two-phase titanic aluminide alloy having a lamellar microstructure with little intercolony structures. The alloy can include fine particles such as boride particles at colony boundaries and/or grain boundary equiaxed structures. The alloy can include alloying additions such as .ltoreq.10 at % W, Nb and/or Mo. The alloy can be free of Cr, V, Mn, Cu and/or Ni and can include, in atomic %, 45 to 55% Ti, 40 to 50% Al, 1 to 5% Nb, 0.3 to 2% W, up to 1% Mo and 0.1 to 0.3% B. In weight %, the alloy can include 57 to 60% Ti, 30 to 32% Al, 4 to 9% Nb, up to 2% Mo, 2 to 8% W and 0.02 to 0.08% B.

  8. Compression-induced phase transition of GaN bulk from wurtzite phase to five-fold coordination hexagonal phase

    Science.gov (United States)

    Qian, Yu; Shang, Fulin; Wan, Qiang; Yan, Yabin

    2017-09-01

    The phase transformation of GaN bulk from the Wurtzite phase (WZ) to the hexagonal phase (HX) is studied by molecular dynamics simulation. The mechanical response and atomic structural evolution of transition are analyzed in detail. In addition, the loading rate effect on the phase transition is determined, that is, the phase transition ratio declines with a decrease of the strain rate. The WZ GaN bulk completely transforms into the HX phase in the case of compression at an ultrahigh strain rate. However, at a relatively slower strain rate, the HX phase of GaN partly nucleates and the untransformed regions are proved to be elastic deformed regions. Combined with an energy analysis, two atomic movement modes are recognized as the inducements for the phase transition and formation of elastic deformed regions. The first mode, which is responsible for the formation of elastic deformed regions, is an atomic sliding motion along the c {0001} planes. The second mode is a radial stretching atomic motion. The radial stretching motion, which requires a lot of energy, induces the WZ-HX phase transition. Moreover, the phase transition is affected drastically by the rise of temperature.

  9. Machine Phase Fullerene Nanotechnology: 1996

    Science.gov (United States)

    Globus, Al; Chancellor, Marisa K. (Technical Monitor)

    1997-01-01

    NASA has used exotic materials for spacecraft and experimental aircraft to good effect for many decades. In spite of many advances, transportation to space still costs about $10,000 per pound. Drexler has proposed a hypothetical nanotechnology based on diamond and investigated the properties of such molecular systems. These studies and others suggest enormous potential for aerospace systems. Unfortunately, methods to realize diamonoid nanotechnology are at best highly speculative. Recent computational efforts at NASA Ames Research Center and computation and experiment elsewhere suggest that a nanotechnology of machine phase functionalized fullerenes may be synthetically relatively accessible and of great aerospace interest. Machine phase materials are (hypothetical) materials consisting entirely or in large part of microscopic machines. In a sense, most living matter fits this definition. To begin investigation of fullerene nanotechnology, we used molecular dynamics to study the properties of carbon nanotube based gears and gear/shaft configurations. Experiments on C60 and quantum calculations suggest that benzyne may react with carbon nanotubes to form gear teeth. Han has computationally demonstrated that molecular gears fashioned from (14,0) single-walled carbon nanotubes and benzyne teeth should operate well at 50-100 gigahertz. Results suggest that rotation can be converted to rotating or linear motion, and linear motion may be converted into rotation. Preliminary results suggest that these mechanical systems can be cooled by a helium atmosphere. Furthermore, Deepak has successfully simulated using helical electric fields generated by a laser to power fullerene gears once a positive and negative charge have been added to form a dipole. Even with mechanical motion, cooling, and power; creating a viable nanotechnology requires support structures, computer control, a system architecture, a variety of components, and some approach to manufacture. Additional

  10. A Novel Phase-Locking-Free Phase Sensitive Amplifier based Regenerator

    DEFF Research Database (Denmark)

    Kjøller, Niels-Kristian; Røge, Kasper Meldgaard; Guan, Pengyu

    2016-01-01

    We propose a scheme for phase regeneration of optical binary phase-shift keying (BPSK) data signals based on phase sensitive amplification without active phase-locking. A delay interferometer (DI) is used to convert a BPSK signal impaired by noise to an amplitude modulated signal followed by cross......-locked pumps. As a result, active phase-stabilization is avoided. A proof-of-principle experiment is carried out with a dual-pump degenerate phase sensitive amplifier (PSA), demonstrating regeneration for a 10 Gb/s non-return-to-zero differential BPSK (NRZ-DPSK) data signal degraded by a sinusoidal phase...

  11. Microstructural evolution of delta ferrite in SAVE12 steel under heat treatment and short-term creep

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shengzhi, E-mail: lishengzhi@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Eliniyaz, Zumrat; Zhang, Lanting; Sun, Feng [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Shen, Yinzhong [School of Nuclear Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Shan, Aidang, E-mail: adshan@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2012-11-15

    This research focused on the formation and microstructural evolution of delta ferrite phase in SAVE12 steel. The formation of delta ferrite was due to the high content of ferrite forming alloy elements such as Cr, W, and Ta. This was interpreted through either JMatPro-4.1 computer program or Cr{sub eq} calculations. Delta ferrite was found in bamboo-like shape and contained large amount of MX phase. It was surrounded by Laves phases before creep or aging treatment. Annealing treatments were performed under temperatures from 1050 Degree-Sign C to 1100 Degree-Sign C and various time periods to study its dissolution kinetics. The result showed that most of the delta ferrite can be dissolved by annealing in single phase austenitic region. Dissolution process of delta ferrite may largely depend on dissolution kinetic factors, rather than on thermodynamic factors. Precipitation behavior during short-term (1100 h) creep was investigated at temperature of 600 Degree-Sign C under a stress of 180 MPa. The results demonstrated that delta ferrite became preferential nucleation sites for Laves phase at the early stage of creep. Laves phase on the boundary around delta ferrite showed relatively slower growth and coarsening rate than that inside delta ferrite. - Highlights: Black-Right-Pointing-Pointer Delta ferrite is systematically studied under heat treatment and short-term creep. Black-Right-Pointing-Pointer Delta ferrite contains large number of MX phase and is surrounded by Laves phases before creep or aging treatment. Black-Right-Pointing-Pointer Formation of delta ferrite is interpreted by theoretical and empirical methods. Black-Right-Pointing-Pointer Most of the delta ferrite is dissolved by annealing in single phase austenitic region. Black-Right-Pointing-Pointer Delta ferrite becomes preferential nucleation sites for Laves phase at the early stage of creep.

  12. Symmetry protected topological phases in spin-1 ladders and their phase transitions

    OpenAIRE

    Chen, Ji-Yao; Liu, Zheng-Xin

    2015-01-01

    We study two-legged spin-1 ladder systems with $D_2\\times \\sigma$ symmetry group, where $D_2$ is discrete spin rotational symmetry and $\\sigma$ means interchain reflection symmetry. The system has one trivial phase and seven nontrivial symmetry protected topological (SPT) phases. We construct Hamiltonians to realize all of these SPT phases and study the phase transitions between them. Our numerical results indicate that there is no direct continuous transition between any two SPT phases we st...

  13. Effect of Specific Energy Input on Microstructure and Mechanical Properties of Nickel-Base Intermetallic Alloy Deposited by Laser Cladding

    Science.gov (United States)

    Awasthi, Reena; Kumar, Santosh; Chandra, Kamlesh; Vishwanadh, B.; Kishore, R.; Viswanadham, C. S.; Srivastava, D.; Dey, G. K.

    2012-12-01

    This article describes the microstructural features and mechanical properties of nickel-base intermetallic alloy laser-clad layers on stainless steel-316 L substrate, with specific attention on the effect of laser-specific energy input (defined as the energy required per unit of the clad mass, kJ/g) on the microstructure and properties of the clad layer, keeping the other laser-cladding parameters same. Defect-free clad layers were observed, in which various solidified zones could be distinguished: planar crystallization near the substrate/clad interface, followed by cellular and dendritic morphology towards the surface of the clad layer. The clad layers were characterized by the presence of a hard molybdenum-rich hexagonal close-packed (hcp) intermetallic Laves phase dispersed in a relatively softer face-centered cubic (fcc) gamma solid solution or a fine lamellar eutectic phase mixture of an intermetallic Laves phase and gamma solid solution. The microstructure and properties of the clad layers showed a strong correlation with the laser-specific energy input. As the specific energy input increased, the dilution of the clad layer increased and the microstructure changed from a hypereutectic structure (with a compact dispersion of characteristic primary hard intermetallic Laves phase in eutectic phase mixture) to near eutectic or hypoeutectic structure (with reduced fraction of primary hard intermetallic Laves phase) with a corresponding decrease in the clad layer hardness.

  14. Microanalysis of two creep resistant 9-12% chromium steels

    Energy Technology Data Exchange (ETDEWEB)

    Haettestrand, M.; Schwind, M.; Andren, H.-O. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Physics

    1998-07-15

    The ferritic chromium steels P122 and P92 have been investigated using APFIM and TEM. The two steels are similar in composition with the exception of an addition of copper to P122, allowing a higher chromium content. The investigated materials were tempered at 770 C and isothermally aged at 600 C for times ranging from 0 to 10000 h. The matrix and precipitates of type M{sub 23}C{sub 6}, MX and Laves phase have been analysed with APFIM. Steel P122 contains 0.9% copper and it was found that the matrix concentration of copper drops during ageing from 0.4% to an equilibrium level at 0.1%, which is in good agreement with previous thermodynamical calculations. No copper was found in M{sub 23}C{sub 6}, MX or Laves phase. Copper instead forms a separate phase. This phase was identified by TEM. During ageing the amount of tungsten in the matrix drops due to formation of Laves phase. This process is faster in steel P122 compared with steel P92, indicating an accelerating effect of copper on the nucleation of Laves phase. In both steels, enhanced concentrations of boron were found inside M{sub 23}C{sub 6} carbides. Phosphorous was found to segregate to a very narrow region at the carbide/matrix interface. (orig.) 18 refs.

  15. Path-independent phase unwrapping using phase gradient and total-variation (TV) denoising.

    Science.gov (United States)

    Huang, Howard Y H; Tian, L; Zhang, Z; Liu, Y; Chen, Z; Barbastathis, G

    2012-06-18

    Phase unwrapping is a challenging task for interferometry based techniques in the presence of noise. The majority of existing phase unwrapping techniques are path-following methods, which explicitly or implicitly define an intelligent path and integrate phase difference along the path to mitigate the effect of erroneous pixels. In this paper, a path-independent unwrapping method is proposed where the unwrapped phase gradient is determined from the wrapped phase and subsequently denoised by a TV minimization based method. Unlike the wrapped phase map where 2π phase jumps are present, the gradient of the unwrapped phase map is smooth and slowly-varying at noise-free areas. On the other hand, the noise is greatly amplified by the differentiation process, which makes it easier to separate from the smooth phase gradient. Thus an approximate unwrapped phase can be obtained by integrating the denoised phase gradient. The final unwrapped phase map is subsequently determined by adding the first few modes of the unwrapped phase. The proposed method is most suitable for unwrapping phase maps without abrupt phase changes. Its capability has been demonstrated both numerically and by experimental data from shearography and electronic speckle pattern interferometry (ESPI).

  16. Phase imaging in brain using SWIFT

    Science.gov (United States)

    Lehto, Lauri Juhani; Garwood, Michael; Gröhn, Olli; Corum, Curtis Andrew

    2015-03-01

    The majority of MRI phase imaging is based on gradient recalled echo (GRE) sequences. This work studies phase contrast behavior due to small off-resonance frequency offsets in brain using SWIFT, a FID-based sequence with nearly zero acquisition delay. 1D simulations and a phantom study were conducted to describe the behavior of phase accumulation in SWIFT. Imaging experiments of known brain phase contrast properties were conducted in a perfused rat brain comparing GRE and SWIFT. Additionally, a human brain sample was imaged. It is demonstrated how SWIFT phase is orientation dependent and correlates well with GRE, linking SWIFT phase to similar off-resonance sources as GRE. The acquisition time is shown to be analogous to TE for phase accumulation time. Using experiments with and without a magnetization transfer preparation, the likely effect of myelin water pool contribution is seen as a phase increase for all acquisition times. Due to the phase accumulation during acquisition, SWIFT phase contrast can be sensitized to small frequency differences between white and gray matter using low acquisition bandwidths.

  17. Stereo 3D spatial phase diagrams

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Jinwu, E-mail: kangjw@tsinghua.edu.cn; Liu, Baicheng, E-mail: liubc@tsinghua.edu.cn

    2016-07-15

    Phase diagrams serve as the fundamental guidance in materials science and engineering. Binary P-T-X (pressure–temperature–composition) and multi-component phase diagrams are of complex spatial geometry, which brings difficulty for understanding. The authors constructed 3D stereo binary P-T-X, typical ternary and some quaternary phase diagrams. A phase diagram construction algorithm based on the calculated phase reaction data in PandaT was developed. And the 3D stereo phase diagram of Al-Cu-Mg ternary system is presented. These phase diagrams can be illustrated by wireframe, surface, solid or their mixture, isotherms and isopleths can be generated. All of these can be displayed by the three typical display ways: electronic shutter, polarization and anaglyph (for example red-cyan glasses). Especially, they can be printed out with 3D stereo effect on paper, and watched by the aid of anaglyph glasses, which makes 3D stereo book of phase diagrams come to reality. Compared with the traditional illustration way, the front of phase diagrams protrude from the screen and the back stretches far behind of the screen under 3D stereo display, the spatial structure can be clearly and immediately perceived. These 3D stereo phase diagrams are useful in teaching and research. - Highlights: • Stereo 3D phase diagram database was constructed, including binary P-T-X, ternary, some quaternary and real ternary systems. • The phase diagrams can be watched by active shutter or polarized or anaglyph glasses. • The print phase diagrams retains 3D stereo effect which can be achieved by the aid of anaglyph glasses.

  18. Phase shifter for antenna beam steering

    Energy Technology Data Exchange (ETDEWEB)

    Jindal, Ravi, E-mail: rjindal21@gmail.com [Master’s(MS) in System Electronics and General Electrical, Ecole Polytechnique of university of Nantes France, IETR, Nantes (France); Razban, Tchanguiz, E-mail: tchanguiz.razban-haghighi@univ-nantes.fr [Electronics and Telecommunication Institute of Rennes (IETR-UMR 6164), Ecole Polytechnique of university of Nantes France, IETR, Nantes (France)

    2016-03-09

    Wide band Array Antenna operates in Ku-band (10.7-12.7 GHz) frequency composed of N×N radiating elements. This antenna aims at the reception of television satellite signals. The goal of this research is to provide better possibility of electronic beam control instead of manual or mechanical control, and design compact and low cost phase shifters to be inserted in the feeding network of this antenna. The electronic control of the phase shifter will allow the control of beam steering. The emphasis of this project will be done at the beginning on the design of a good phase shifter in Ku band. The aim of this research is to define, simulate, release and measure a continuous phase shifter. Better reflection loss, low transmission loss, low Cost of array antennas, large range of phase-shifter, phase flatness and bandwidth will be achieved by providing better gain.

  19. Phase conjugate Michelson interferometer for optical logic

    Science.gov (United States)

    Khoury, Jed

    2017-05-01

    The interference theory is developed for of the phase conjugate Michelson interferometer in which its ordinary mirrors are replaced by a single externally pumped phase conjugate mirror. According to the theory, it was found that for an interferometer with two equal arms, the path length difference depends solely on the initial alignment of the two input beams, and the vertical alignment readout. Small vertical misalignments in the readout beam by mrad causes a huge change in the phase difference in the phase between the two interferometer arms beam. The phase difference is proportional to the interferometer arm lengths. The overlap between the phase conjugate beams is not affected by the interferometer beam alignment. The interferometer is proposed for nondestructive testing and the design all optical logic and associated fuzzy logic for ultrafast optical pattern recognition.

  20. Phases of Kaluza-Klein Black Holes

    DEFF Research Database (Denmark)

    Harmark, Troels; Obers, N. A.

    2005-01-01

    We review the latest progress in understanding the phase structure of static and neutral Kaluza-Klein black holes, i.e. static and neutral solutions of pure gravity with an event horizon that asymptote to a d-dimensional Minkowski-space times a circle. We start by reviewing the (mu,n) phase diagram...... and the split-up of the phase structure into solutions with an internal SO(d-1) symmetry and solutions with Kaluza-Klein bubbles. We then discuss the uniform black string, non-uniform black string and localized black hole phases, and how those three phases are connected, involving issues such as classical...... instability and horizon-topology changing transitions. Finally, we review the bubble-black hole sequences, their place in the phase structure and interesting aspects such as the continuously infinite non-uniqueness of solutions for a given mass and relative tension....