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Sample records for c14 laves phase

  1. Ab initio study of C14 laves phases in Fe-based systems

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    Pavlu J.

    2012-01-01

    Full Text Available Structural properties and energetics of Fe-based C14 Laves phases at various compositions (i.e. Fe2Fe, Fe2X, X2Fe, X2X, where X stands for Si, Cr, Mo, W, Ta were investigated using the pseudopotential VASP (Vienna Ab initio Simulation Package code employing the PAW-PBE (Projector Augmented Wave - Perdew Burke-Ernzerhof pseudopotentials. Full relaxation was performed for all structures studied including the reference states of elemental constituents and the equilibrium structure parameters as well as bulk moduli were found. The structure parameters of experimentally found structures were very well reproduced by our calculations. It was also found that the lattice parameters and volumes of the unit cell decrease with increasing molar fraction of iron. Thermodynamic analysis shows that the Fe2X configurations of Laves phases are more stable than the X2Fe ones. Some of the X2Fe configurations are even unstable with respect to the weighted average of the Laves phases of elemental constituents. Our calculations predict the stability of Fe2Ta. On the other hand, Fe2Mo and Fe2W are slightly unstable (3.19 and 0.68 kJ.mol-1, respectively and hypothetical structures Fe2Cr and Fe2Si are found unstable as well.

  2. Observation of weak ferromagnetism in the C14 Laves phase of the (Fe{sub 1-x}Ni{sub x}){sub 2}Nb system

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    Paduani, C. [DF-UFSC, Florianopolis, CEP, SC (Brazil); Schaf, J. [IF-UFRGS, Porto Alegre, CEP, RS (Brazil); Persiano, A.I.C. [DF-ICEX-UFMG, Belo Horizonte, CEP, MG (Brazil); Raposo, M.T. [DCNAT-UFSJ, Sao Joao Del Rei, CEP, MG (Brazil); Ardisson, J.D. [CDTN, Belo Horizonte, CEP, MG (Brazil); Takeuchi, A.Y. [DF-UFES, Vitoria, CEP, ES (Brazil)

    2009-06-15

    In this work we report the observation of weak ferromagnetism in the hexagonal C14 Laves phase (s.g. P63/mmc) of the (Fe{sub 1-x}Ni{sub x}){sub 2}Nb system, which has been reported as nonmagnetic in the literature. A larger unit cell volume is observed as compared to Fe{sub 2}Nb. From low-temperature magnetization measurements it is found that the Ni substitution for Fe indeed leads to the onset of a weak ferromagnetic ordering in the C14 Laves phase of this pseudobinary system. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. 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.

  4. Structural, elastic and electronic properties of C14-type Al2M (M=Mg, Ca, Sr and Ba) Laves phases

    Science.gov (United States)

    Lishi, Ma; Yonghua, Duan; Runyue, Li

    2017-02-01

    The structural and mechanical properties, Debye temperatures and anisotropic sound velocities of the Laves phases Al2M (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 Al2Ca 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-Al2M (M=Mg, Ca, Sr and Ba) phases.

  5. Evidence of weak ferromagnetism in the C14 Laves phase (Fe{sub 1-x}Co{sub x}){sub 2}Nb system

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    Paduani, C. [DF-UFSC, Florianopolis, CEP 88040-900, SC (Brazil)], E-mail: paduani@fisica.ufsc.br; Schaf, J. [IF-UFRGS, Porto Alegre, CEP 91501-970, RS (Brazil); Persiano, A.I.C. [DF-ICEX-UFMG, Belo Horizonte, CP 702, 30161-970 MG (Brazil); Ardisson, J.D. [CDTN, Belo Horizonte, CEP 30123-970, MG (Brazil); Takeuchi, A.Y. [DF-UFES, Vitoria, CEP 29075-910, ES (Brazil); Raposo, M.T. [DCNAT-UFSJ, Sao Joao Del Rei, CEP 36300-000, MG (Brazil)

    2009-04-17

    In this work are studied the structure and magnetic properties of the (Fe{sub 1-x}Co{sub x}){sub 2}Nb alloys with X-ray diffraction and magnetization measurements. The results confirm the formation of the C14 Laves phase in the Co concentration range 0{<=}x{<=}0.55. The unit cell volume decreases with the increase of the cobalt concentration and is larger than in Fe{sub 2}Nb. Magnetization measurements indicate that this system is weakly ferromagnetic at low temperatures for x{<=}0.55. From the behavior of the M(T) curves a cluster-glass-like mechanism is predicted for this system below 50 K.

  6. First-principles calculations of the stability and hydrogen storage behavior of C14 Laves phase compound TiCrMn

    Science.gov (United States)

    Nong, Zhi-Sheng; Zhu, Jing-Chuan; Yang, Xia-Wei; Cao, Yong; Lai, Zhong-Hong; Liu, Yong; Sun, Wen

    2014-06-01

    The structural, elastic properties, electronic structure and hydrogen storage behavior of TiCrMn with a hexagonal C14 structure were investigated by the first-principles calculations within the frame work of DFT. The calculated lattice constants were consistent with the experimental values, and obtained cohesive energy and formation enthalpy showed TiCrMn is of the structural stability. These results also indicated that Mn atoms would optionally substitute on the Cr sites of TiCr2 phase to form the ternary intermetallic TiCrMn. The five independent elastic constants as well as polycrystalline elastic parameters (bulk modulus B, shear modulus G, Young's modulus E, Poisson's ratio ν and anisotropy value A) were calculated, and then the ductility and elastic anisotropy of TiCrMn were discussed in details. Furthermore, the electronic DOS and charge density distribution of TiCrMn were also calculated, which revealed the underlying mechanism of structural stability and chemical bonding. Finally, the binding energy of hydrogen in hydride TiCrMn(H3) was investigated, confirming the better hydrogen storage behavior of C14 Laves phase TiCrMn.

  7. Influence of the C14 Ti{sub 35.4}V{sub 32.3}Fe{sub 32.3} Laves phase on the hydrogenation properties of the body-centered cubic compound Ti{sub 24.5}V{sub 59.3}Fe{sub 16.2}

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    Gueguen, A.; Joubert, J.-M. [Institut de Chimie et des Materiaux de Paris Est (ICMPE), Chimie Metallurgique des Terres Rares, CNRS, UMR 7182, Thiais (France); Latroche, M., E-mail: michel.latroche@icmpe.cnrs.fr [Institut de Chimie et des Materiaux de Paris Est (ICMPE), Chimie Metallurgique des Terres Rares, CNRS, UMR 7182, Thiais (France)

    2011-02-10

    Research highlights: > Preparation and structural characterizations of multiphase materials made of a bcc matrix with nominal composition Ti{sub 24.5}V{sub 59.3}Fe{sub 16.2} and C14 Laves phase inclusions. > Study of the influence of the presence of C14 Laves phase on the hydrogen sorption properties of the bcc alloy Ti{sub 24.5}V{sub 59.3}Fe{sub 16.2}. > Influence of the annealing process on the structure and the hydrogenation properties of the bcc Ti{sub 24.5}V{sub 59.3}Fe{sub 16.2} phase. - Abstract: Bcc Ti{sub 24.5}V{sub 59.3}Fe{sub 16.2} alloys containing 10 and 30% of C14 Laves phase inclusions were prepared by induction melting followed by annealing at 1000 {sup o}C. X-ray powder diffraction and BSE microscopy confirmed the presence of the C14 Laves phase (average composition Ti{sub 35.4}V{sub 32.3}Fe{sub 32.3}) embedded in the bcc matrix. The two end members of the series, the C14 Laves phase and the bcc Ti{sub 24.5}V{sub 59.3}Fe{sub 16.2} alloy, have very different hydrogenation behaviors. The C14 Laves phase does not absorb as much hydrogen as does the bcc phase. No equilibrium plateau and little hysteresis between absorption and desorption were observed at 25 deg. C for the C14 Laves on the PCI curves whereas those of the bcc sample present one equilibrium plateau and significant hysteresis between absorption and desorption. As a result, the absorption capacity and the length of the equilibrium plateau of the multiphase alloys decrease with the C14 Laves phase content. The hydrogenation properties of an as-cast bcc Ti{sub 24.5}V{sub 59.3}Fe{sub 16.2} sample were also investigated: the kinetics of the first hydrogenation is found to be slower and the plateau pressures higher for the as-cast alloy than for the annealed sample.

  8. Ferromagnetism in Laves-phase WFe2 nanoparticles

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    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. Ferromagnetism in Laves-phase WFe{sub 2} nanoparticles

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    Koten, M. A.; Shield, J. E. [Department of Mechanical and Materials Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588-0526 (United States); Manchanda, P.; Balamurugan, B.; Skomski, R.; Sellmyer, D. J. [Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588-0299 (United States)

    2015-07-01

    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 WFe{sub 2} 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 M{sub S} of 26.4 emu/g (346 emu/cm{sup 3}) and a K{sub U} of 286 kerg/cm{sup 3}, at 10 K, and a T{sub C} of 550 K.

  10. Deformation of C15 Laves phase alloys

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    Chu, F.; Pope, D.P.

    1995-12-31

    Details of the structure and previous work on the deformation of C Laves phases are reviewed. The phase diagram of the Hf-V-Nb system, some metallurgical and physical properties, mechanical behavior, and the deformation mechanisms of HfV{sub 2}+Nb (CI5 HfV{sub 2}+Nb and V-rich bcc solution) are presented based on our previous work. Theoretical approaches to understanding the results of these studies are discussed.

  11. Synergistic effect between Laves phase and Zr-Ni phases in Zr(MnVNi)2 hydrogen storage alloys

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The effect of annealing treatment on the crystal structure and electrochemical properties of Zr (Mn0.25V0.20Ni0.55)2 and Zr(Mn0.05V0.40Ni0.55 )2 hydrogen storage alloys was investigated by means of XRDanalysis and electrochemical tests. The results of XRD analysis showed that the as-cast alloys consist of C15,C14 type Laves phase and Zr9Ni11 and ZrNi phases. The composition of alloys homogenized after annealing treatment. The C15 type Laves phase is still stable while the Zr9Ni11 and ZrNi phases decompose and C14 phase disappears partially. The final stable structure of the alloys was a mixture phase of C15 and C14 type Laves phases. The results of the electrochemical tests showed that the discharge capacity and the properties of activation as well as high-rate dischargeability are all decreased after annealing treatment. The exchange current density decreases in some degree too.

  12. Microstructure and mechanical properties of Cr-Ta-Si Laves phase-based alloys at elevated temperatures

    Science.gov (United States)

    Bhowmik, Ayan; Neumeier, Steffen; Barnard, Jon S.; Zenk, Christopher H.; Göken, Mathias; Rae, Catherine M. F.; Stone, Howard J.

    2014-12-01

    The microstructure and mechanical properties of a series of Cr-Cr2Ta-based alloys with nominal compositions (90-x)Cr-9Ta-xSi, where x = 4, 6, 10 and 14 at%, have been investigated. The alloys predominantly consisted of a microstructure of primary C14 Cr2Ta Laves phase dendrites and a eutectic intergrowth of an A2 Cr rich solid solution and the Laves phase. The Laves phase was seen to adopt the C14 polytype in all ternary alloys, with no evidence of transformation to the C15 polytype. Fine, solid-state precipitates of the Laves phase were also observed within the solid solution. At higher silicon contents, a third intermetallic phase, Cr3Si, with the A15 crystal structure, was also identified. The overall hardness of the alloys at room temperature increased with Si content and hence, the volume fraction of the Laves phase. Compression tests were conducted on samples of the alloys at 1000 and 1100 °C under a strain rate of 10-4 s-1 in air. Amongst the ternary alloys, the alloy with 14 at% Si showed the highest yield strength of ~440 MPa at 1000 °C and ~290 MPa at 1100 °C. The yield strength of the alloy with 6 at% Si was also found to reduce monotonically with increasing temperature from ambient to 1100 °C. Transmission electron microscopy of the post-compression microstructures revealed that deformation was primarily accommodated by the A2 Cr-rich solid solution, with a high density of dislocations in the phase compared to that in the intermetallic phase. Within the C14 Laves phase, deformation was seen to be mediated by the movement of a/3?-type synchro-Shockley partial dislocations, consistent with previous studies, bounding stacking faults on the basal plane.

  13. 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.

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

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    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.

  15. 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...

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

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    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.

  17. Formation of laves phase in a refractory austenitic steel due to long-term heating

    Science.gov (United States)

    Tarasenko, L. V.; Shal'kevich, A. B.

    2011-07-01

    Steels of the Fe - Cr - Ni -Mo - Nb - Al - C system are studied by methods of phase physicochemical analysis and electron microscopy with the aim to determine the causes of changes in mechanical properties after long-term heating at a temperature of 600 - 700°C. Grain-boundary formation of particles of a Laves phase is shown to cause decrease in the impact toughness and transformation of particles of γ'-phase under conditions of creep. The effect of alloying elements on the chemical composition of the multicomponent Laves phase is studied depending on the temperatures of hardening, aging, and subsequent heating. Concentration correspondence between the chemical composition of the austenite and the intermetallic tcp phase formed in aging is discovered. A computational scheme for predicting the possibility of formation of Laves phases in multicomponent alloys is suggested.

  18. 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.

  19. 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

    ) images in scanning electron microscope (SEM). The smaller Laves phase particle size results in higher creep strength and longer creep exposure time at the same conditions. DICTRA software was used to model the growth and coarsening behavior of Laves phase in the three P92 steels. Good agreements were......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 (SE...... 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....

  20. Cluster-based composition rule for Laves phase-related BCC solid solution hydrogen storage alloys

    Institute of Scientific and Technical Information of China (English)

    WANG Qing; CHEN Feng; WU Jiang; QIANG Jianbing; DONG Chuang; ZHANG Yao; XU Fen; SUN Lixian

    2006-01-01

    A new cluster line approach for the composition rule of Laves phase-related BCC solid solution hydrogen-storage alloys was presented. The cluster line in a ternary phase diagram refers to a straight composition line linking a specific binary cluster to the third element. In the Laves phase-related BCC solid solution alloy system such as Ti-Cr-V, Ti-Cr tends to form binary Cr2Ti Laves phase while Ti-V and Cr-V to form solid solutions. This Laves phase is characterized by a close-packing icosahedral cluster Cr7Ti6. A cluster line Cr7Ti6-V is then constructed in this system. Alloy rods with a diameter of 3 mm of compositions along this line were prepared by copper-mould suction method. The alloy structure is found to vary with the V contents. Furthermore, the P-C-T measurements indicate that the cluster-line (Cr7Ti6)1-xVx alloys have large hydrogen storage capacities.

  1. 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...

  2. Precipitation of Icosahedral Quasicrystalline Phase, R-phase and Laves Phase in Ferritic Alloys

    Institute of Scientific and Technical Information of China (English)

    Keisuke Yamamoto; Yoshisato Kimura; Yoshinao Mishima

    2004-01-01

    Ferritic heat resistant steels involving precipitation of intermetallic phases have drawn a growing interest for the enhancement of creep strength, while the brittleness of the intermetallic phases may lower the toughness of the alloy.Therefore, it is necessary to optimize the dispersion characteristics of the intermetallics phase through microstructural control to minimize the trade-off between the strength and toughness. The effects of α-Fe matrix substructures on the precipitation sequence, morphology, dispersion characteristics, and the stability of the intermetallic phases are investigated in Fe-Cr-W-Co-Si system. The precipitates of the Si-free Fe-10Cr-1.4W-4.5Co (at%) alloy aged at 873K are the R-phase but those of the Si-added Fe-10Cr-1.4W-4.5Co-0.3Si (at%) alloy are the icosahedral quasicrystalline phase. The precipitates in both the Si-free and Si-added alloys aged at 973K are the Laves phase. Matrix of the alloys is controlled by heat treatments as to provide three types of matrix substructures; ferrite, ferrite/martensite mixture and martensite. The hardening behavior of the alloys depends on the matrix substructures and is independent of the kinds of precipitates. In the alloys with ferrite matrix, the peak of hardness during aging at 873K shifts to longer aging time in comparison with that in the alloys with lath martensite matrix which contain numbers of nucleation sites.

  3. Mn Nanowhiskers of a Novel Hexagonal Phase Grown from Hydrogen Activated Laves Phase Alloys

    Institute of Scientific and Technical Information of China (English)

    WU Er-Dong; GUO Xiu-Mei

    2008-01-01

    With the aid of hydrogenation/dehydrogenation, nanorod whiskers of transition metal Mn can grow spontaneously from Zr,1-x Ti,x MnCr Laves phase alloys at room temperature. The finding introduces a distinguishingly different element into metal whisker family, and provides a potential technique for fabrication of one-dimensional metal nanostructures. Moreover, it is found that the segregated Mn in whiskers forms a novel hexagonal structure, which partially fulfills the long predicted allotropic form and adds more complexity to the structures of Mn.

  4. Magnetostriction of some rare earth-aluminum Laves phase compounds

    Science.gov (United States)

    Pourarian, F.; Wallace, W. E.

    1979-01-01

    Measurements of the linear and volume magnetostriction of RAl2 cubic Laves compounds in which R is one of the rare earth elements Gd, Dy, Ho or Er, at temperatures between 4.2 K and the Curie temperature of each compound, are reported. Magnetic fields up to 2.5 Tesla were applied, and magnetostriction was measured using standard strain gage techniques. Saturation magnetostrictions of 17 x 10 to the -6th, -1420 x 10 to the -6th, 60 x 10 to the -6th and -920 x 10 to the -6th are determined at 4.2 K for GdAl2, DyAl2, HoAl2 and ErAl2, respectively. Large forced magnetostriction is observed in GdAl2 above the saturation field and the strain temperature dependence shows a decrease in magnitude below 40 K. A linear dependence of magnetostriction on magnetic field was observed for DyAl2 above 40 K, and the observed temperature dependence is interpreted in terms of the lowest order single-ion magnetoelastic theory. An observed decrease in the magnitude of the strain of HoAl2 below 15 K is associated with a change of the easy direction of magnetization, while in the case of ErAl2, magnetostriction is observed to occur normally up to the Curie temperature. Large volume magnetostriction is obtained for all the compounds with the exception of GdAl2.

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

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    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.

  6. Growth Kinetics of Laves Phase and Its Effect on Creep Rupture Behavior in 9Cr Heat Resistant Steel

    Institute of Scientific and Technical Information of China (English)

    Zhi-xin XIA; Chuan-yang WANG; Chen LEI; Yun-ting LAI; Yan-fen ZHAO; Lu ZHANG

    2016-01-01

    The effects of Laves phase formation and growth on creep rupture behaviors of P92 steel at 883 K were studied.The microstructural evolution was characterized using scanning electron microscopy and transmission elec-tron microscopy.Kinetic modeling was carried out using the software DICTRA.The results indicated Fe2 (W,Mo) Laves phase has formed during creep with 200 MPa applied stress at 883 K for 243 h.The experimental results showed a good agreement with thermodynamic calculations.The plastic deformation of laths is the main reason of creep rupture under the applied stress beyond 160 MPa,whereas,creep voids initiated by coarser Laves phase play an effective role in creep rupture under the applied stress lower than 160 MPa.Laves phase particles with the mean size of 243 nm lead to the change of creep rupture feature.Microstructures at the vicinity of fracture surface,the gage portion and the threaded ends of creep rupture specimens were also observed,indicating that creep tensile stress enhances the coarsening of Laves phase.

  7. Laves phase in alloy 718 fusion zone — microscopic and calorimetric studies

    Energy Technology Data Exchange (ETDEWEB)

    Manikandan, S.G.K., E-mail: nehakutty06@gmail.com [Indian Space Research Organization, India, (India); Sivakumar, D., E-mail: d_sivakumar@vssc.gov.in [Indian Space Research Organization, India, (India); Prasad Rao, K., E-mail: jyothipr@gmail.com [University of Utah, Salt Lake City, UT (United States); Kamaraj, M., E-mail: kamaraj@iitm.ac.in [Indian Institute of Technology Madras (India)

    2015-02-15

    Microstructural characterization of alloy 718 fusion zone welded with both solid solution and age hardenable filler metal has been done. The microsegregation and the aging response were studied by employing three levels of weld cooling rate. Gas Tungsten Arc welding process was used. The fusion zone of solid solution filler metal has been responding to the aging treatment due to the weld process conditions and weld metal chemistry. However the weld metal composition was modified due to the higher molybdenum (Mo) content in solid solution filler metal. The effect of this modification on the phase reaction temperatures was studied and the same was compared with the conventional filler metal. - Graphical abstract: Display Omitted - Highlights: • Interdendritic segregation has been controlled by weld cooling rate. • Laves phase formation has been studied with cooling rate and weld metal chemistry. • Aging response with solid solution filler metal has been demonstrated. • Reduction in Laves phase and alloying element segregation has been confirmed. • Reaction temperatures were found modified because of Mo addition.

  8. Laves-phase evolution during aging in 9Cr-1.8W-0.5Mo-VNb steel for USC power plants

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xue, E-mail: wangxue2011@whu.edu.cn [School of Power and Mechanics, Wuhan University, Wuhan 430072 (China); Xu, Qiang [School of Computing and Engineering, The University of Huddersfield, Huddersfield HD1 3DH, England (United Kingdom); Yu, Shu-min; Hu, Lei [School of Power and Mechanics, Wuhan University, Wuhan 430072 (China); Liu, Hong [DongFang Boiler Group Co.,Ltd., Zigong 643001 (China); Ren, Yao-yao [School of Power and Mechanics, Wuhan University, Wuhan 430072 (China)

    2015-08-01

    Long term precipitation and coarsening of Laves-phase in tungsten strengthened 9% Cr steel under thermal aging at 923 K was investigated and reported in this paper. It experimentally measured the evolution of mean particle size, the number density, the volume fraction of Laves-phase precipitates, the partition coefficients of W and Mo in the matrix, as well as the change of hardness. Its main conclusions were: 1) Laves-phase nucleates and grows rapidly on grain boundaries and lath boundaries within the first 1500 h of aging time; 2) The two stages characteristics and kinetics of Laves-phase nucleation and growth which were determined experimentally; 3) The coarsening of Laves-phase is much faster than that of M{sub 23}C{sub 6} carbides; 4) The precipitation of Laves-phase produces a pronounced matrix depletion of W and Mo atoms; and 5) The precipitated Laves-phase gives rise to weaker precipitation strengthening in comparison with M{sub 23}C{sub 6} carbides, and causes the loss of hardness due to the depletion of Mo and W from the solid solution. This paper contributes to the knowledge of kinetics of Laves-phase precipitation and coarsening, providing the essential information for comparative investigation of creep damage mechanisms. This paper also contributes to the understanding the creep damage broadly. - Highlights: • The characteristics of precipitation and coarsening of Laves-phase were determined. • The matrix depletion of W and Mo due to Laves-phase precipitation was quantified. • The effect of precipitated Laves-phase on the hardness was evaluated.

  9. Cd4Cu7As, the first representative of a fully ordered, orthorhombically distorted MgCu2 Laves phase.

    Science.gov (United States)

    Osters, Oliver; Nilges, Tom; Schöneich, Michael; Schmidt, Peer; Rothballer, Jan; Pielnhofer, Florian; Weihrich, Richard

    2012-08-06

    The ternary Laves phase Cd(4)Cu(7)As is the first intermetallic compound in the system Cu-Cd-As and a representative of a new substitution variant for Laves phases. It crystallizes orthorhombically in the space group Pnnm (No. 58) with lattice parameters a = 9.8833(7) Å; b = 7.1251(3) Å; c = 5.0895(4) Å. All sites are fully occupied within the standard deviations. The structure can be described as typical Laves phase, where Cu and As are forming vertex-linked tetrahedra and Cd adopts the structure motive of a distorted diamond network. Cd(4)Cu(7)As was prepared from stoichiometric mixtures of the elements in a solid state reaction at 1000 °C. Magnetic measurements are showing a Pauli paramagnetic behavior. During our systematical investigations within the ternary phase triangle Cd-Cu-As the cubic C15-type Laves phase Cd(4)Cu(6.9(1))As(1.1(1)) was structurally characterized. It crystallizes cubic in the space group Fd3m with lattice parameter a = 7.0779(8) Å. Typically for quasi-binary Laves phases Cu and As are both occupying the 16c site. Chemical bonding, charge transfer and atomic properties of Cd(4)Cu(7)As were analyzed by band structure, ELF, and AIM calculations. On the basis of the general formula for Laves phases AB(2), Cd is slightly positively charged forming the A substructure, whereas Cu and As represent the negatively charged B substructure in both cases. The crystal structure distortion is thus related to local effects caused by Arsenic that exhibits a larger atomic volume (18 Å(3) compared to 13 Å(3) for Cu) and higher ionicity in bonding.

  10. Study on the nucleation and growth of Laves phase in a 10% Cr martensite ferritic steel after long-term aging

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yuantao [Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Wang, Mingjia, E-mail: mingjiawangysu@126.com [Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Wang, Yan; Gu, Tao [Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Chen, Lei [National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University, Qinhuangdao 066004 (China); Zhou, Xuan; Ma, Qian; Liu, Yuming; Huang, Jing [Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2015-02-05

    Highlights: • Having used EBSD, SEM–BSE, and TEM techniques to investigate the nucleation and growth of Laves phase in the 10% Cr steel. • Most of Laves phases appear on grain boundaries with a misorientation angle of 40–60° and only a small amount of them at 3–10°. • Carbon atoms will segregate on the vicinity of phase interfaces between Laves phase and α-Fe during decomposition of M{sub 23}C{sub 6} carbides and formation of Laves phases. - Abstract: The nucleation and growth of Laves phase in a 10% Cr martensite ferritic steel after long-term aging have been investigated in this paper. Laves phase, (Fe, Cr){sub 2} (Mo, W), was observed after long-term (>750 h) aging at 650 °C. It is found that Laves phases prefer to locate at prior austenite grain boundaries and martensite lath boundaries, especially, most of them precipitate at grain boundaries with a misorientation angle of 40–60° and only a small amount of them at 3–10°. Moreover, the size of Laves phase at 40–60° grain boundaries is larger than that at 3–10° grain boundaries. In addition, some Laves phases are formed in the regions adjacent to M{sub 23}C{sub 6} particles, with increasing aging time they will gradually swallow the Cr-rich M{sub 23}C{sub 6} carbides in close vicinity, resulting in carbon atoms segregation on the vicinity of phase interfaces between Laves phase and α-Fe.

  11. Hydrogen storage properties of Laves phase Ti1-xZrx(Mn0.5 Cr0.5)2 alloys

    Institute of Scientific and Technical Information of China (English)

    GUO Xiumei; WU Erdong; WANG Sucheng

    2006-01-01

    The activation behaviors and hydrogen storage properties of the Laves phase Ti1-xZrx(Mn0.5Cr0.5)2(x=0,0.1,0.2,0.32,0.5) alloys were investigated by the pressure-composition-temperature (P-C-T) measurements. All the studied alloys show the single C14-type Laves phase structurebased on the XRD data. Except for the alloys with very low Zr content of x =0 and x =0.1, all these alloys can be fully activated. The P-C isotherms of the activated alloys show that, the introduction of Zr induces the decrease of the equilibrium pressures and the steeper plateaus. As the x increases, the maximum hydrogen absorption also increases, whereas the desorption of hydrogen decreases. These two effects result in a maximum reversible hydrogen storage capacity of H/M =3.03 for the alloy at x =0.32. Furthermore, the well-defined plateau associated with the smallest hysteresis also appears at x =0.32.

  12. Magnetic, magnetocaloric and magnetoresistive properties of cubic Laves phase HoAl2 single crystal.

    Science.gov (United States)

    Patra, M; Majumdar, S; Giri, S; Xiao, Y; Chatterji, T

    2014-01-29

    We report the magnetization (M) and magnetoresistance (MR) results of HoAl2 single crystals oriented along the ⟨100⟩ and ⟨110⟩ directions. Although HoAl2 has cubic Laves phase structure, a large anisotropy is observed in M and MR below the Curie temperature (TC). A satisfactory correlation between magnetic entropy change (ΔSM) and MR could be established along ⟨110⟩ and also ⟨100⟩, except for the temperature (T) region around which spin reorientation takes place. Large inverse magnetocaloric effect is observed at low T, which is associated with the spin reorientation process in the ⟨100⟩ direction. A theoretical model based on the Landau theory of phase transition can describe the T-variation of -ΔSM for T > TC.

  13. Quasielastic neutron scattering studies of H motion in Laves-phase compounds

    CERN Document Server

    Skripov, A V; Cook, J C; Udovic, T J; Hempelmann, R

    2002-01-01

    The results of our quasielastic neutron scattering measurements for a number of cubic Laves-phase hydrides AB sub 2 H sub x are consistent with the coexistence of two types of H motion: the fast localized jumps within the hexagons formed by interstitial g (A sub 2 B sub 2) sites and the slower hopping from one hexagon to another. The analysis of these results has revealed the relation between the hydrogen-hopping rates, the g-g distances, and the ratio of the metallic radii R sub A and R sub B of the elements A and B forming the AB sub 2 compound. We conclude that the behavior of the two frequency scales of H motion is determined mainly by R sub A /R sub B. A new type of localized H motion is predicted for compounds with R sub A /R sub B >1.35. (orig.)

  14. Precipitation of Laves phase Fe2Mo type in HSLA steel with copper addition and high content of molybdenum

    Directory of Open Access Journals (Sweden)

    S. Pytel

    2010-07-01

    Full Text Available The results of mechanical properties and microstructure of low-carbon copper bearing steel after quenching and tempering at temperaturerange of processing precipitation of particles rich in copper and particles intermetallic phase are presented in this paper. When content molybdenum increases in tempering temperature range from 550°C to 600°C that decrease of the impact energy measured at roomtemperature was observed. Microstructure analysis was conducted by transmission electron microscope (TEM and was disclosed theoccurrence of Fe2Mo Laves phase on crystallites boundaries of retained austenite. Observed sudden drop of ductility in higher-molybdenum content steels (1,88 % and 2,94 % should be connected with occurrence precipitation processes of the hard and brittle Laves phase in range of discussion tempering temperatures.

  15. 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.

  16. Ca{sub 2}Pd{sub 3}Ge, a new fully ordered ternary Laves phase structure

    Energy Technology Data Exchange (ETDEWEB)

    Doverbratt, Isa, E-mail: isa.doverbratt@polymat.lth.se [Centre for Analysis and Synthesis, Lund University, P.O. Box 124, 22100 Lund (Sweden); Ponou, Simeon; Lidin, Sven [Centre for Analysis and Synthesis, Lund University, P.O. Box 124, 22100 Lund (Sweden)

    2013-01-15

    The title compound, Ca{sub 2}Pd{sub 3}Ge, was prepared as a part of a systematic investigation of the Ca-Pd-Ge ternary phase diagram. The structure was determined and refined from single-crystal X-ray diffraction data. It is a new fully ordered ternary Laves phase with the space group R-3m, Z=3, a=5.6191 (5) A, c=12.1674 (7) A, wR{sub 2}=0.054 (all data) and is isostructural to Mg{sub 2}Ni{sub 3}Si (Noreus et al., 1985 [17]) but due to the larger size of all elements in Ca{sub 2}Pd{sub 3}Ge, the cell axes are approximately 10% longer. The compound may formally be considered as a Zintl compound, with [Pd{sub 3}Ge]{sup 4-} forming a poly-anionic network and divalent Ca cations located in truncated tetrahedral interstices. The electronic structure and chemical bonding of Ca{sub 2}Pd{sub 3}Ge is discussed in terms of LMTO band structure calculations and compared with CaPd{sub 2} (MgCu{sub 2}-type). - Graphical abstract: The title compound, Ca{sub 2}Pd{sub 3}Ge is a new fully ordered ternary Laves phase which may formally be considered as a Zintl compound, with [Pd{sub 3}Ge]{sup 4-} forming a poly-anionic network and divalent Ca cations located in truncated tetrahedral interstices. The structure is composed of Kagome net layers, consisting of Pd atoms only, which are stacked in an ABC sequence. Band structure calculations show that the Fermi level is located at a local minimum of the DOS (pseudo-gap) indicating that the charge is roughly optimized in the structure. Highlights: Black-Right-Pointing-Pointer Site specific segregation in a Laves phase that is also a Zintl phase. Black-Right-Pointing-Pointer Pseudo-gap at the Fermi level in a Laves phase. Black-Right-Pointing-Pointer Distorted Frank-Kasper polyhedron.

  17. Magnetism and magnetocaloric effect in multicomponent Laves-phase compounds: Study and comparative analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ćwik, J., E-mail: cwikjac@ml.pan.wroc.pl

    2014-01-15

    This paper presents a review and results of comparative study of the influence of Gd on some physical properties of (R{sub 0.9}R′{sub 0.1}){sub 1−x}Gd{sub x}Co{sub 2} solid solutions with R=Dy, Ho and R′=Er, Ho and x varied from 0.05 to 0.15. Powder X-ray diffraction analysis performed at room temperature revealed that all studied solid solutions solidify with the formation of a Laves-phase MgCu{sub 2}-type structure (space group Fd−3m). The magnetization behavior and the magnetic transition are analyzed in terms of the Landau theory. The studies of magnetic properties and heat capacity showed that a relatively small Gd addition significantly increases T{sub C} of the compounds. The maximum percentage increase in T{sub C}, namely, ∼43% was observed for (Ho{sub 0.9}Er{sub 0.1}){sub 1−x}Gd{sub x}Co{sub 2}. However, the highest temperature was noted for the (Dy{sub 0.9}Ho{sub 0.1}){sub 0.85}Gd{sub 0.15}Co{sub 2} solid solution; it is T{sub C}=183.4 K. Below the ordering temperature, all samples are ferrimagnetically ordered; at high temperatures, they are Curie–Weiss paramagnets. Moreover, a small Gd addition eliminates the field-induced magnetic transition near T{sub C} and, as consequence, transforms the nature of magnetic transition from the first- to second-order. The magnetocaloric effect has been estimated in terms of both isothermal magnetic entropy and adiabatic temperature changes. The highest adiabatic temperature change ΔT{sub ad}=3 K and highest isothermal entropy change ΔS{sub mag}=12.1 J/kg K were observed for (Ho{sub 0.9}Er{sub 0.1}){sub 0.95}Gd{sub 0.05}Co{sub 2} at ∼90 K in magnetic fields of 2 T and 3 T, respectively. A decrease in the entropy change has been observed with increasing Gd content in all studied samples. The smallest values of ΔS{sub mag} were observed for the (Dy{sub 0.9}Ho{sub 0.1}){sub 1−x}Gd{sub x}Co{sub 2} solid solutions. Under an external field change of from 0 to 3 T, the maximum entropy change for (Dy{sub 0

  18. Magnetic and structural properties of Sc(Fe1−xSix2 Laves phases studied by Mössbauer spectroscopy and neutron diffraction

    Directory of Open Access Journals (Sweden)

    Wiertel Marek

    2015-03-01

    Full Text Available The aim of the presented paper is to study an influence of replacement of Fe atoms by Si atoms in quasibinary Sc(Fe1−xSix2 Laves phases on their structural and magnetic properties. Powder X-ray diffraction (XRD and neutron diffraction (ND measurements carried out at different temperatures from 4.3 K up to about 700 K revealed that samples were single phase with cubic C15 structure for Si concentration x from 0.05 to 0.20 and hexagonal C14 structure for higher concentration. The results of 57Fe Mössbauer measurements showed that the Sc(Fe1−xSix2 compounds with x ≤ 0.30 are ferrimagnetic at 4.3 K. At temperature 80 K in the samples with x = 0.20 and 0.30, a magnetic cluster spin-glass state has been observed, as ferrimagnetic long-range order disappears. Such picture was supported by the results of ND measurements carried out at 8 K, which confirmed the lack of long-range order for x above 0.10 and an occurrence of hyperfine field distributions in the corresponding Mössbauer spectra. At room temperature, samples with x ≥ 0.20 became paramagnetic. A substitution of Si atoms for Fe ones leads to a decreasing of mean values of hyperfine magnetic fields in samples under investigation. From the neutron diffraction pattern analysis of Sc(Fe0.90Si0.102Fe magnetic moment was determined as to be equal to 1.5 μB at 8 K. Combining this result with a value of hyperfine magnetic field on 57Fe probes, the hyperfine coupling constant A in Sc(Fe0.90Cu0.102 phases is estimated at about 11.6 T/μB at 8 K.

  19. Moessbauer study of the cubic Laves phase intermetallic compound TmFe/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Bleaney, B.; Bowden, G.J.; Cadogan, J.M. (New South Wales Univ., Kensington (Australia). School of Physics); Day, R.K.; Dunlop, J.B. (Commonwealth Scientific and Industrial Research Organization, Lindfield (Australia). Div. of Applied Physics)

    1982-04-01

    The results of a /sup 169/Tm and /sup 57/Fe Moessbauer study of the cubic Laves compound TmFe/sub 2/ over the temperature range 1.3-550 K are presented and discussed. The new results are used, in conjunction with existing NMR, Moessbauer and magnetic anisotropy data for TmFe/sub 2/ and Tm metal, to deduce a value of Psub(4f) 536 +- 14 MHz for the saturation value of the first excited state of the /sup 169/Tm nucleus. Estimates are also given for the exchange field ..mu..sub(B)Bsub(ex)(T = O K)/ksub(B) = 153 +- 3 K acting on the Tm/sup 3 +/ ion in TmFe/sub 2/, the quadrupole moment of the I = 3/2 state of the /sup 169/Tm nucleus. Q = -1.36 +- 0.11 b, and the lattice contribution to the nuclear quadrupole interaction in Tm metal, Psub(c) = -54.8 +- 5 MHz (for Q = -1.20 +- 0.07 b) and Psub(c) = -61 +- 8 MHz (for Q = -1.36 +- 0.11 b). In addition estimates are given for the various transferred and parent hyperfine fields in TmFe.

  20. Effect of composition, microstructure and component thickness on the oxidation behaviour of laves phase strengthened interconnect steel for solid oxide fuel cells (SOFC)

    OpenAIRE

    2013-01-01

    The high-Cr, Laves phase strengthened ferritic steel, Crofer 22 H, has recently been proposed as construction material for interconnects in solid oxide fuel cells (SOFC). Aim of the present investigation was to get more insight in the details of SOFC relevant properties, mostly oxidation behaviour and oxide electronic conductivity, in simulated SOFC service environments as a function of temperature, with main emphasis on the most commonly used operating temperature 800°C. The present studies ...

  1. Influence of Tb on easy magnetization direction and magnetostriction of ferromagnetic Laves phase GdFe2 compounds

    Science.gov (United States)

    Murtaza, Adil; Yang, Sen; Zhou, Chao; Song, Xiaoping

    2016-09-01

    The crystal structure, magnetization, and spontaneous magnetostriction of ferromagnetic Laves phase GdFe2 compound have been investigated. High resolution synchrotron x-ray diffraction (XRD) analysis shows that GdFe2 has a lower cubic symmetry with easy magnetization direction (EMD) along [100] below Curie temperature TC. The replacement of Gd with a small amount of Tb changes the EMD to [111]. The Curie temperature decreases while the field dependence of the saturation magnetization (Ms) measured in temperature range 5-300 K varies with increasing Tb concentration. Coercivity Hc increases with increasing Tb concentration and decays exponentially as temperature increases. The anisotropy in GdFe2 is so weak that some of the rare-earth substitution plays an important role in determining the easy direction of magnetization in GdFe2. The calculated magnetostrictive constant λ100 shows a small value of 37×10-6. This value agrees well with experimental data 30×10-6. Under a relatively small magnetic field, GdFe2 exhibits a V-shaped positive magnetostriction curve. When the field is further increased, the crystal exhibits a negative magnetostriction curve. This phenomenon has been discussed in term of magnetic domain switching. Furthermore, magnetostriction increases with increasing Tb concentration. Our work leads to a simple and unified mesoscopic explanation for magnetostriction in ferromagnets. It may also provide insight for developing novel functional materials. Project supported by the National Basic Research Program of China (Grant No. 2012CB619401).

  2. Electronic band structures of AV{sub 2} (A = Ta, Ti, Hf and Nb) Laves phase compounds

    Energy Technology Data Exchange (ETDEWEB)

    Charifi, Z; Baaziz, H [Physics Department, Faculty of Science and Engineering, University of M' sila, 28000 M' sila (Algeria); Reshak, Ali Hussain [Institute of Physical Biology, South Bohemia University, Nove Hrady 37333 (Czech Republic)], E-mail: maalidph@yahoo.co.uk

    2009-01-14

    First-principles density functional calculations, using the all-electron full potential linearized augmented plane wave method, have been performed in order to investigate the structural and electronic properties for Laves phase AV{sub 2} (A = Ta, Ti, Hf and Nb) compounds. The generalized gradient approximation and the Engel-Vosko-generalized gradient approximation were used. Our calculations show that these compounds are metallic with more bands cutting the Fermi energy (E{sub F}) as we move from Nb to Ta, Hf and Ti, consistent with the increase in the values of the density of states at the Fermi level N(E{sub F}). N(E{sub F}) is controlled by the overlapping of V-p/d, A-d and A-p states around the Fermi energy. The ground state properties of these compounds, such as equilibrium lattice constant, are calculated and compared with the available literature. There is a strong/weak hybridization between the states, V-s states are strongly hybridized with A-s states below and above E{sub F}. Around the Fermi energy we notice that V-p shows strong hybridization with A-p states.

  3. Composition design for Laves phase-related body-centered cubic-V solid solution alloys with large hydrogen storage capacities.

    Science.gov (United States)

    Wang, H B; Wang, Q; Dong, C; Yuan, L; Xu, F; Sun, L X

    2008-03-19

    This paper analyzes the characteristics of alloy compositions with large hydrogen storage capacities in Laves phase-related body-centered cubic (bcc) solid solution alloy systems using the cluster line approach. Since a dense-packed icosahedral cluster A(6)B(7) characterizes the local structure of AB(2) Laves phases, in an A-B-C ternary system, such as Ti-Cr (Mn, Fe)-V, where A-B forms AB(2) Laves phases while A-C and B-C tend to form solid solutions, a cluster line A(6)B(7)-C is constructed by linking A(6)B(7) to C. The alloy compositions with large hydrogen storage capacities are generally located near this line and are approximately expressed with the cluster-plus-glue-atom model. The cluster line alloys (Ti(6)Cr(7))(100-x)V(x) (x = 2.5-70 at.%) exhibit different structures and hence different hydrogen storage capacities with increasing V content. The alloys (Ti(6)Cr(7))(95)V(5) and Ti(30)Cr(40)V(30) with bcc solid solution structure satisfy the cluster-plus-glue-atom model.

  4. Deuterium-Absorbing Behavior of Ti36Zr40Ni20Pd4 Alloy with Laves Phase%Laves相Ti36Zr40Ni20Pd4合金的吸氘行为

    Institute of Scientific and Technical Information of China (English)

    黄火根; 刘天伟; 陈亮; 张志

    2013-01-01

    The crystal structure and deuterium storage property of Ti36Zr40Ni20Pd4 alloy were investigated by means of X-ray diffraction and a gas-solid reaction system.Results show that before suction-casting,the alloy ingot grows into the MgZn2-typed C14 Laves phase with the coordination number of 14 and the lattice constant of a=0.5287nm,c=0.8610 nm.Through a simple activation treatment,the phase can load largely deuterium up to 10.96 mmol·D2/g·M (D2 represents the deuterium molecule and M the alloy).After one absorption-desorption cycle,the deuterium-uptake speed substantially improves,with the reaction constant reaching to 0.015 s-1.Incontrast to the Ti36Zr40Ni20Pd4 quasicrystal,the present Laves phase with the same composition can load deuterium with a lower rate but in a comparable volume,indicating its promise in storing hydrogen.%针对Ti36Zr40Ni20Pd4合金用X射线衍射仪和气固反应系统研究了其吸铸之前的晶体结构与吸氘特性.结果表明,吸铸前Ti36Zr40Ni20Pd4合金母锭形成了配位数为14的MgZn2结构的简单六方C14 Laves相,晶格常数a=0.5287 nm与c=0.8610 nm.简单活化后,该合金可在室温下大量吸氘,浓度达到10.96 mmol·D2/g·M(D2指氘分子,M指合金).经过一次吸放氘循环后,吸氘动力学显著提高,吸氘速率常数达到0.015 s-1.相对于成分相同的准晶相,Laves相Ti36Zr40Ni20Pd4合金吸氘较慢,但吸氘量相近,具有一定的储氢前景.

  5. Synthesis of Iron-Based Laves Phase Containing Praseodymium Magnetostrictive Materials

    Institute of Scientific and Technical Information of China (English)

    Liu Heyan; Dong Bin; Li Songtao; Meng Xiangxi; Gao Jianbo; Qu Jingping; Li Yangxian

    2007-01-01

    The synthesis and magnetostriction of PrxTb1-xFe2, PrxTb1-xFe2B0.2 and PrxTb1-x(Fe0.6Co0.4)2 alloys were investigated in this study. The addition of boron or cobalt atom in PrxTb1-xFe2 could effectively prevent the formation of non-cubic phases, and Pr concentration limit was successfully increased from 0.2 to 0.4. X-ray step scanning for the PrxTb1-xFe2B0.2 and PrxTb1-x(Fe0.6Co0.4)2 alloys showed that PrFe2 possessed a large spontaneous magnetostriction λ111.

  6. Fe-moment instability in Ti{sub 1-x}Sc{sub x}Fe{sub 2} Laves-phase compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ouladdiaf, B. [Institut Laue-Langevin, BP 156, 38042 GRENOBLE Cedex 09 (France); Deportes, J. [Lab. Louis Neel, CNRS, BP 166, 38042 GRENOBLE Cedex 09 (France); Saoudi, M. [Centre Universitaire de Guelma, GUELMA 24 000 (Algeria)

    2002-07-01

    The magnetic properties of the pseudo-binary Laves-phase compounds Ti{sub 1-x}Sc{sub x}Fe{sub 2} were investigated by means of magnetisation and high-resolution powder neutron diffraction techniques. For x<0.2 a transition from an antiferromagnetic state to a canted one with a ferromagnetic component in the basal plane is observed, while for 0.2

  7. Structure and hydrogen storage properties of the hexagonal Laves phase Sc(Al{sub 1-x}Ni{sub x}){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Sahlberg, Martin, E-mail: Martin.sahlberg@kemi.uu.se [Department of Chemistry, The Angstroem Laboratory, Uppsala University, Box 538, SE-751 21 Uppsala (Sweden); Angstroem, Jonas, E-mail: jonas.angstrom@kemi.uu.se [Department of Chemistry, The Angstroem Laboratory, Uppsala University, Box 538, SE-751 21 Uppsala (Sweden); Zlotea, Claudia, E-mail: claudia.zlotea@icmpe.cnrs.fr [Chimie Metallurgique des Terres Rares, Institut de Chimie et des Materiaux de Paris Est, UMR 7182, CNRS, 2-8 rue Henri Dunant, 94320 Thiais Cedex (France); Beran, Premysl, E-mail: pberan@ujf.cas.cz [Nuclear Physics Institute, Academy of Sciences of the Czech Republic, 25068 Rez (Czech Republic); Latroche, Michel, E-mail: michel.latroche@glvt-cnrs.fr [Chimie Metallurgique des Terres Rares, Institut de Chimie et des Materiaux de Paris Est, UMR 7182, CNRS, 2-8 rue Henri Dunant, 94320 Thiais Cedex (France); Pay Gomez, Cesar, E-mail: Cesar.paygomez@kemi.uu.se [Department of Chemistry, The Angstroem Laboratory, Uppsala University, Box 538, SE-751 21 Uppsala (Sweden)

    2012-12-15

    The crystal structures of hydrogenated and unhydrogenated Sc(Al{sub 1-x}Ni{sub x}){sub 2} Laves phases have been studied by combining several diffraction techniques and it is shown that hydrogen is situated interstitially in the A{sub 2}B{sub 2}-sites, which have the maximum number of scandium neighbours. The hydrogen absorption/desorption behaviour has also been investigated. It is shown that a solid solution of hydrogen forms in the mother compound. The hydrogen storage capacity exceeds 1.7 H/f.u. at 374 K, and the activation energy of hydrogen desorption was determined to 4.6 kJ/mol H{sub 2}. It is shown that these compounds share the same local coordination as Frank-Kasper-type approximants and quasicrystals, which opens up the possibility of finding many new hydride phases with these types of crystal structures. - Graphical abstract: The structure of ScNiAlDx, Sc atoms are shown in purple and Ni/Al atoms in blue and the iso-surfaces of deuterium in yellow. Revealed from refinements of neutron powder diffraction data. Highlights: Black-Right-Pointing-Pointer The crystal structure of ScNiAl and ScNiAlDx is reported. Black-Right-Pointing-Pointer We show the hydrogen storage properties of Sc(Al{sub 1-x}Ni{sub x}){sub 2}. Black-Right-Pointing-Pointer We discuss the possibility to store hydrogen in quasicrystals.

  8. Li{sub 12}Cu{sub 12.60}Al{sub 14.37}. A new ternary derivative of the binary Laves phases

    Energy Technology Data Exchange (ETDEWEB)

    Pavlyuk, Volodymyr [Ivan Franko Lviv National Univ. (Ukraine). Dept. of Inorganic Chemistry; Jan Dlugosz Univ., Czestochowa (Poland). Inst. of Chemistry, Environment Protection and Biotechnology; Dmytriv, Grygoriy; Tarasiuk, Ivan [Ivan Franko Lviv National Univ. (Ukraine). Dept. of Inorganic Chemistry; Chumak, Ihor [IFW Dresden (Germany); Ehrenberg, Helmut [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inorganic Chemistry

    2011-12-15

    New ternary dodecalithium dodecacopper tetradecaaluminium, Li{sub 12}Cu{sub 12.60}Al{sub 14.37} (trigonal, R anti 3m, hR39), crystallizes as a new structure type and belongs to the structural family that derives from binary Laves phases. The Li atoms are enclosed in 15- and 16-vertex and the Al3 atom in 14-vertex pseudo-Frank-Kasper polyhedra. The polyhedra around the statistical mixtures of (Cu,Al)1 and (Al,Cu)2 are distorted icosahedra. The electronic structure was calculated by the TB- LMTO-ASA (tight-binding linear muffin-tin orbital atomic spheres approximation) method. The electron localization function, which indicates bond formation, is mostly located at the Al atoms. Thus, Al-Al bonding is much stronger than Li-Al or Cu-Al bonding. This indicates that, besides metallic bonding which is dominant in this compound, weak covalent Al-Al interactions also exist. (orig.)

  9. 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.

  10. Ab initio study of structural stability and electronic properties of Ti{sub 1-x}Mg{sub x}Cr{sub 2} and TiMg{sub x}Cr{sub 2-x} laves phase

    Energy Technology Data Exchange (ETDEWEB)

    Sari, A., E-mail: sari.aouatef@yahoo.fr; Merad, G. [Unité de Recherché Matériaux et Energies Renouvelables. Division d’Etudes et de Prédiction des Matériaux. Université Abou Bekr Belkaid. Tlemcen. Algerie (Algeria)

    2015-03-30

    The structural stability and electronic properties of TiMgCr{sub 2} laves phase have been calculated and compared. It is found that Mg prefer to substitutes titanium than chromium. The values of entalpies of formation show that Ti{sub 1-x}Mg{sub x}Cr{sub 2} may exist for only one concentration x=0.125 and the more favorable alloy is Ti{sub 0.875}Mg{sub 0.125}Cr{sub 2}. For TiCr{sub 2}, the optimized structural parameters were in good agreement with experimental values, while for TiMgCr{sub 2}, there is not experimental data. The electronic densities of states (DOS) are given and the nature of bonds are also discussed.

  11. 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.

  12. 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.

  13. Structural, magnetic and magnetostrictive properties of Laves-phase compounds Tb{sub x}Ho{sub 0.9−x}Nd{sub 0.1}Fe{sub 1.93} (0 ≤ x ≤ 0.40)

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Z.B. [Faculty of Materials Science and Chemical Engineering, and Department of Physics, Ningbo University, Ningbo 315211 (China); Liu, J.J., E-mail: liujinjun1@nbu.edu.cn [Faculty of Materials Science and Chemical Engineering, and Department of Physics, Ningbo University, Ningbo 315211 (China); Liu, X.Y.; Wang, J. [Faculty of Materials Science and Chemical Engineering, and Department of Physics, Ningbo University, Ningbo 315211 (China); Du, J. [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Si, P.Z. [Zhejiang Key Lab on Magnetic Materials, China Jiliang University, Hangzhou 310018 (China)

    2014-11-14

    The structural, magnetic and magnetostrictive properties of Tb{sub x}Ho{sub 0.9−x}Nd{sub 0.1}Fe{sub 1.93} (0 ≤ x ≤ 0.40) alloys have been investigated by means of X-ray diffraction (XRD), a vibrating sample magnetometer and a standard strain technique. Single Laves phase (Tb,Ho,Nd)Fe{sub 2} compounds with a cubic MgCu{sub 2}-type structure have been synthesized at equilibrium conditions with ambient pressure. The lattice parameter of the Laves phase increases linearly with increasing Tb content and obeys the linear Vegard's law. The easy magnetization direction (EMD) at room temperature rotates continuously from <100> for x = 0.10 to <111> for x = 0.25 through an intermediate direction <110> around x = 0.15, subjected to the anisotropy compensation between Tb{sup 3+} and Ho{sup 3+} ions. The splitting of (440) XRD peak accompanied by the spontaneous magnetostriction-induced rhombohedral distortion is observed for the compounds of x ≥ 0.2, and the spontaneous magnetostriction coefficient λ{sub 111} is found to increase with increasing Tb content. The analysis of XRD, EMD, magnetization and magnetostriction shows that the pseudobinary system Tb{sub x}Ho{sub 0.9−x}Nd{sub 0.1}Fe{sub 1.93} is an anisotropy compensation system and the compensation point is realized around x = 0.25. The Nd-containing Tb{sub 0.25}Ho{sub 0.65}Nd{sub 0.1}Fe{sub 1.93} Laves-phase compound has good magnetostrictive properties, that is, a large saturation magnetostriction (λ{sub S}∼585 ppm) and a low magnetocrystalline anisotropy at room temperature, which may make it technological interest for magnetostriction applications. - Highlights: • A single (Tb,Ho,Nd)Fe{sub 2} Laves phase with a cubic MgCu{sub 2}-type structure is formed. • Anisotropy compensation has been realized for the Tb{sub x}Ho{sub 0.9−x}Nd{sub 0.1}Fe{sub 1.93} alloys. • A large saturation magnetostriction (λ{sub S} ∼ 585 ppm) is obtained for x = 0.25.

  14. 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.

  15. The effect of hydrogen absorption on the structural, electronic and magnetic properties of the C15 Friauf-Laves phase compounds CeFe{sub 2}, CeRu{sub 2} and LaRu{sub 2} : an x-ray absorption spectroscopy (XAS) study

    Energy Technology Data Exchange (ETDEWEB)

    Chaboy, J.; Garcia, J. [CSIC-Univ., Zaragoza (Spain). Inst. de Ciencia de Materiales de Aragon ICMA; Marcelli, A. [INFN, Laboratori Nazionali di Frascati, Rome (Italy)

    1995-08-01

    An x-ray absorption spectroscopy (XAS) investigation of the structural changes occurred upon hydriding in the Friauf-Laves phase compounds CeFe{sub 2}, CeRu{sub 2}and LaRu{sub 2} compounds is presented. The analysis of the extended x-ray absorption spectroscopy (EXAFS) spectra at the L-edges of the rare-earth and at the Fe K-edge indicates that the hydrogenation process leads to the suppression of the long-range crystalline order in all the hydride derivates investigated, as well as the different influence of H{sub 2} in both the rare earth and transition metal sublattices. The correlation between the structural and magnetic changes induced by the hydrogen in the lost matrix is discussed in terms of the modification of the electronic properties, i.e., intermediate-valence of Ce, and of the hybridization between the transition metal and rare-earth.

  16. Some aspects of dimensionality and phase transitions of organic-inorganic hybrid perovskite ( n-C14H29NH3)2ZnCl4

    Science.gov (United States)

    Abdelkader, M. M.; Gamal, W. M.

    2017-03-01

    The differential scanning calorimetery and the differential thermal analysis thermograms were performed over a suitable wide range of temperatures on polycrystalline samples of the titled hybrid. Furthermore, the ac conductivity σ ac(ῳ, T) and the complex dielectric permittivity ɛ *(ῳ, T) as function of temperature 120 K < T < 400 K and some selected frequencies in the range 1 kHz ≤ f ≤ 100 kHz were measured and presented. The combination of the measured parameters confirms, without any doubt, the existence of a first-order reversible solid-solid structural phase transition from intercalation to non-intercalation, at T ≈ 368 K accompanied by a sudden increase of the interlayer spacing by ≈17.5%. The analysis of our data is based on the coordination complex and the dimensionality of the central metal halide arrangements, which, in our case, is isolated square [ZnCl4]-2 tetrahedral coordination and, hence, of zero-dimensionality (0D), but stabilized in a two-dimensional structure through charge-assisted hydrogen-bonding system. The zero-dimensionality results in a large charge density and, hence, of high efficiently packed compared with other hybrids of this series which are usually crystallized in two-dimensional (2D) corner-sharing [MCl6]-2. The rule of hydrogen bonding has been considered. The odd-even effects were given.

  17. High-temperature electrochemical performance and phase composition of Ti0.7Zr0.5V0.2Mn1.8-xNix hydrogen storage electrode alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The rapid development of electric vehicles demands the development of high performance nickel-metal hydride battery that is able to endure high temperature. The discharge properties of Ti0.7Zr0.5V0.2Mn1.8-xNix(x=0.4, 0.8, 1.1, 1.4, 1.7)hydrogen storage alloys was investigated and its phase composition was analyzed using X-ray diffraction. The results show that the cycling life was improved as the content of nickel increases. When x=0.4, 0.8, 1.1 and 1.4, the main phase is MgZn2 type C14 Laves phase and the second one is cubic TiNi phase. When x=1.7, the Laves phase structure disappears. EDAS analysis shows that the increase of nickel content is effective in suppressing the dissolution of vanadium component in alloys.

  18. Reporting C-14 activities and concentrations

    NARCIS (Netherlands)

    Mook, WG; van der Plicht, J

    1999-01-01

    Three modes of reporting C-14 activities are in use, in part analogous to the internationally accepted (IAEA) conventions for stable isotopes: (1) absolute activity, the specific activity of C-14 or the activity per gram of carbon; (2) activity ratio, the ratio between the absolute activities of a s

  19. 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.

  20. Phase Evolution of the AlxNbTiVZr (x = 0; 0.5; 1; 1.5 High Entropy Alloys

    Directory of Open Access Journals (Sweden)

    Nikita Y. Yurchenko

    2016-11-01

    Full Text Available AlxNbTiVZr (x = 0; 0.5; 1; 1.5 high entropy alloys were fabricated by vacuum arc melting and annealed at 1200 °C for 24 h. The NbTiVZr alloy had single body centered cubic (bcc solid solution phase after annealing at 1200 °C, while, in the Al-containing alloys, C14 Laves and Zr2Al-type phases are found. The alloys were subjected to annealing at 800 °C and 1000 °C. It was shown that annealing temperature (800 °C or 1000 °C weakly affected the produced phases but the Al content had pronounced effect on structure of the annealed alloys. The NbTiVZr alloy decomposed into bcc, Zr-rich hexagonal close-packed (hcp, and C15 Laves phases. In the Al0.5NbTiVZr alloy, the bcc matrix phase also decomposed into a mixture of bcc and C14 Laves phases. In the AlNbTiVZr alloy, annealing resulted in an increase of volume fraction of Zr2Al-type phase. Finally, in the Al1.5NbTiVZr alloy, formation of AlNb2-type phase was observed. The highest fraction of second phases appeared after annealing in the NbTiVZr alloy. It is demonstrated that the strong chemical affinity and high enthalpy of formation of intermetallic phases in Al-Zr atomic pair govern the intermetallic phase formation in the alloys at 1200 °C. Increase of volume fraction of second phases in the alloys due to annealing at 800 °C and 1000 °C is in proportion to the decrease of Zr concentration in the bcc matrix phase.

  1. Specific heat, differential susceptibility and electrical resistivity of PrX2 (X = Ir, Pt, Rh and Ru) laves phase compounds at temperatures 1.4 K < T < 40 K

    Science.gov (United States)

    van Dongen, J. C. M.; van der Linden, H. W. M.; Greidanus, F. J. A. M.; Nieuwenhuys, G. J.; Mydosh, J. A.; Buschow, K. H. J.

    1980-01-01

    Specific heat and differential susceptibility data of PrX 2 (X = Ir, Pt, Rh, and Ru) compounds reveal phase transitions at Tc = (11.2 ± 0.5) K, (7.7 ± 0.5) K, (7.9 ± 0.5) K and (33.9 ± 0.5) K for X = Ir, Pt, RhandRu, resp. The electrical resistivity drops markedly below Tc, and the dϱ/d T versus T curve is similar to that of the specific heat.

  2. Fiskere og fangeres indkomster i bygder er alarmerende lave

    DEFF Research Database (Denmark)

    Rasmussen, Rasmus Ole; Petersen, Carsten

    2006-01-01

    I et internationalt perspektiv er indkomsterne i Grønland stadig meget ulige fordelt – mere ulige end i USA og væsentlig mere ulige end i de øvrige nordiske lande. Samtidig er der nogle markante erhvervsmæssige og regionale forskelle, hvor indtægterne er alarmerende lave, ikke mindst for gruppen ...... fangere og fiskere i bygderne Udgivelsesdato: 23 februar...

  3. Microstructure and mechanical properties of laser melting deposited Ti2Ni3Si/NiTi Laves alloys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Two Ti2Ni3Si/NiTi Laves phase alloys with chemical compositions of Ni-39Ti-11 Si and Ni-42Ti-8Si (%, mole fraction, the same below), respectively, were fabricated by the laser melting deposition manufacturing process, aiming at studying the effect of Ti,Si contents on microstructure and mechanical properties of the alloys. The Ni-39Ti-llSi alloy consisting of Ti2Ni3Si primary dendrites and Ti2Ni3Si/NiTi eutectic matrix is a conventional hypereutectic Laves phase alloy while the Ni-42Ti-8Si alloy being made up of NiTi primary dendrites uniformly distributed in Ti2Ni3Si/NiTi eutectic is a new hypoeutectic alloy. Mechanical properties of the alloys were investigated by nano-indentation test. The results show that the decrease of Si and the increase of Ti contents change the microstructures of the alloys from hypereutectic to hypoeutectic, which influences the mechanical properties of the alloys remarkably. Corrosion behaviors of the alloys were also evaluated by potentiodynamic anodic polarization curves.

  4. Review of C-14 inventory for the SFR facility

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Graham; Merino, Joan; Kerrigan, Emma

    2002-08-01

    The Swedish Radiation Protection Authority (SSI) is currently reviewing SKB's continuing assessment for disposal of radioactive waste to the SFR facility at Forsmark. Among the wastes disposed are reactor operating wastes. Among the relevant radionuclides is C-14, which is relatively difficult to measure and to control because of its mobility. This report documents a review of the C-14 inventory material submitted by SKB for the SFR-facility, to determine its validity and comment on the appropriate assumptions for C-14 content of wastes due to be disposed of to the SFR. The review is based on information provided by SSI as well as other relevant international experience. Conclusions are drawn upon: the chemical form of the C-14 in the waste from BWRs and PWRs; the production rate of C-14 in BWRs and PWRs and quantification of the source term in the IEX waste; the distribution of the C-14 in the IEX waste from BWR between the resins used for treatment of the primary cooling water and the resins used for treatment of the condensate water; quantification of the uncertainties. A suggestion is made that the C-14 inventory could be better developed based upon a mass balance assessment of all the C-14 produced in reactors, and its ultimate fate in effluent and solid wastes, taking account of the reactor specific operational factors identified in the review as relevant to C-14 inventory assessment.

  5. 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.

  6. 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....

  7. Enhanced magnetoelastic effect in Laves (Tb,Dy)Fe2 alloys with the joint introduction of Pr and Nd

    Science.gov (United States)

    Song, X. H.; Liu, J. J.; Wei, S. H.; Zhu, X. Y.; Li, F.; Zhang, Z. R.; Si, P. Z.; Ren, W. J.

    2016-06-01

    The structural and magnetoelastic properties of (Tb0.3Dy0.7)1-x(Pr0.5Nd0.5)xFe1.93 (0 ≤ x ≤ 0.20) polycrystalline alloys have been investigated by means of X-ray diffraction (XRD), a vibrating sample magnetometer and a standard strain gauge technique. A single (Tb,Dy,Pr,Nd)Fe2 Laves phase with a cubic MgCu2-type structure is formed when x ≤ 0.12, while a small amount of impurities appear when x ≥ 0.15. The easy magnetization direction at room temperature is detected toward axis. The analysis of XRD, magnetization and magnetostriction shows that the Pr and Nd elements joint introduction into (Tb,Dy)Fe2 system can reduce the magnetocrystalline anisotropy and improve the magnetoelastic properties. The (Tb0.3Dy0.7)0.88(Pr0.5Nd0.5)0.12Fe1.93 alloy exhibits a high low-field magnetostriction λ a (~314 ppm/1 kOe), a large spontaneous magnetostriction coefficient λ 111 (~1710 ppm), a giant saturation magnetostriction λ S (~1060 ppm) and the low magnetocrystalline anisotropy at room temperature, and may make it a promising candidate for magnetostriction applications.

  8. 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.

  9. (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...... contributions to this increase. We present measurements of (CH4)-C-14 in glacial ice, targeting this transition, performed by using ice samples obtained from an ablation site in west Greenland. Measured (CH4)-C-14 values were higher than predicted under any scenario. Sample (CH4)-C-14 appears to be elevated...... 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....

  10. 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...... relativistic treatment....

  11. Hyperfine specific heats of PrX 2 ( X = Ir, Pt, Rh, Ru) laves phase compounds

    Science.gov (United States)

    Greidanus, F. J. A. M.; de Jongh, L. J.; Huiskamp, W. J.; Buschow, K. H. J.

    1980-01-01

    Specific heat data below 1 K for the C-15 compounds PrX 2 (X = Ir, Pt, Rh, Ru) reveal Schottky-type anomalies, ascribed to hyperfine interactions. Apparently the 4f-moments are magnetically ordered. The values deduced for these moments are only ≈ 70% of that for J = 4, indicating that the Pr 3+ moment is partially quenched by the crystal field.

  12. 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.

  13. 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)

  14. Linear C32H66 hydrocarbon in the mixed state with C10H22, C12H26, C14H30, C16H34 and C18H38: Comparison of strength of phases and role of tunnel-like defects

    Indian Academy of Sciences (India)

    P B Shashikanth; P B V Prasad

    2003-02-01

    Strengths of m, o and phases of linear dotriacontane hydrocarbon in mixed state with certain shorter chain length homologues (SMOLLENCs), estimated from powder XRD analysis, are compared. The results suggest strong evidence in favour of tunnel-like defects (TLIDs).

  15. Synthesis, magnetic properties and magnetostriction of Pr{sub 0.5}Nd{sub 0.5}(Fe{sub 1-x}Co{sub x}){sub 1.9} cubic Laves alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hu, C.C. [Department of Applied Physics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Shi, Y.G., E-mail: shiyangguang@gmail.com [Department of Applied Physics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Chen, Z.Y.; Shi, D.N. [Department of Applied Physics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Tang, S.L.; Du, Y.W. [National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2014-11-15

    Highlights: • Pr{sub 0.5}Nd{sub 0.5}(Fe{sub 1−x}Co{sub x}){sub 1.9} cubic Laves alloys were synthesized by high pressure annealing. • The saturation magnetization increases to a maximum of 103 emu/g at x=0.1. • The spin orientation phase diagram was constructed. • The Co concentration of magnetostriction peaks at x=0.1. - Abstract: The structure, magnetic properties and magnetostriction of polycrystalline Pr{sub 0.5}Nd{sub 0.5}(Fe{sub 1-x}Co{sub x}){sub 1.9} (0⩽x≤0.8) alloys were investigated. It is found that cubic Laves phase becomes the main phase only when the Co concentration is greater than 40 at.% under traditional vacuum annealed method. In contrast, the cubic Laves phase exists over the entire composition range studied in the samples annealed under high pressure. Both the lattice parameter and the Curie temperature decrease with the increasing Co concentration. The saturation magnetization increases into a maximum at x=0.1 and then decreases with further increase in x. The spin orientation phase diagram of Pr{sub 0.5}Nd{sub 0.5}(Fe{sub 1-x}Co{sub x}){sub 1.9} (0⩽x≤0.4) alloys is constructed to illustrate the arrangement for the easy magnetization direction and crystal structure. The magnetostriction of Pr{sub 0.5}Nd{sub 0.5}(Fe{sub 1-x}Co{sub x}){sub 1.9} alloys peaks at x=0.1. The Pr{sub 0.5}Nd{sub 0.5}(Fe{sub 0.9}Co{sub 0.1}){sub 1.9} alloy combines a high magnetostriction with low cost advantage, which may make it potential material for magnetostrictive application.

  16. 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.

    2004-01-01

    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 St

  17. Absorption, Distribution, Excretion, and Pharmacokinetics of C14-Pyronaridine Tetraphosphate in Male and Female Sprague-Dawley Rats

    Directory of Open Access Journals (Sweden)

    Sang Hyun Park

    2010-01-01

    Full Text Available The main objective of this investigation was to determine the absorption, distribution, excretion, and pharmacokinetics of the antimalarial drug pyronaridine tetraphosphate (PNDP in Sprague-Dawley rats. Following oral administration of a single dose (10 mg/Kg of C14-PNDP, it was observed that the drug was readily absorbed from the small intestine within 1 hour following oral administration and was widely distributed in most of the tissues investigated as determined from the observed radioactivity in the tissues. The peak value of the drug in the blood was reached at around 8 hours postadministration, and radioactivity was detected in most of the tissues from 4 hours onwards. C14-PNDP showed a poor permeability across the blood-brain barrier, and the absorption, distribution, and excretion of C14-PNDP were found to be gender-independent as both male and female rats showed a similar pattern of radioactivity. Excretion of the drug was predominantly through the urine with a peak excretion post 24 hours of administration. A small amount of the drug was also excreted in the feces and also in the breath. It was found that the Cmax, AUC (0-inf, and Tmax values were similar to those observed in the Phase II clinical trials of pyronaridine/artesunate (Pyramax conducted in Uganda.

  18. Synthesis and magnetostrictive properties of Pr1−xDyx(Fe0.8Co0.21.93 cubic Laves compounds

    Directory of Open Access Journals (Sweden)

    Y. G. Shi

    2016-05-01

    Full Text Available The structure, magnetic properties and magnetostriction of high-pressure synthesized Pr1−xDyx(Fe0.8Co0.21.93 compounds were investigated. These compounds, which could not be readily synthesized under ambient pressure, exhibit single cubic Laves phase owing to the effects of high-pressure annealing. The Curie temperature increases with increasing x, indicating that 3d-4f coupling becomes stronger with the increase of Dy concentration. The saturation magnetization decreases with increasing x, which can be ascribed to the competition of sublattice magnetization. The easy magnetization direction of the compound lies along with x ≤ 0.05 while lies along when x ≥ 0.10. Meanwhile, the low-field magnetostriction λ∥ − λ⊥ of the compound system peaks at x = 0.05 and then decreases with increasing x, which reveals that the composition anisotropy compensation between Pr3+ and Dy3+ might be realized in Pr1−xDyx(Fe0.8Co0.21.93 system. Pr0.95Dy0.05(Fe0.8Co0.21.93 compound combines a large low-field magnetostriction (648 ppm at 3 kOe and the merits of low-cost raw materials, which may make it a potential material for magnetostrictive application.

  19. 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.

  20. Synthesis and structural characterization of (C14H16N2)3 (C14H17N2)2 [-Mo8 O26

    Indian Academy of Sciences (India)

    Ikram Zebiri; Sihem Boufas; Salima Mosbah; Leïla Bencharif; Mustapha Bencharif

    2015-10-01

    A novel polyoxomolybdate (C14H16N2)3 (C14H17N2)2 [-Mo8 O26] (1) has been synthesized from hydrothermal reaction of tolidine and molybdenum trioxide in water and characterized by its IR and UV spectra, 1H NMR, cyclic voltammetry and single crystal X-ray diffraction. Compound 1 crystallizes in the triclinic crystal system, space group P$\\bar{ı}$, with the crystal cell parameters of =11.5360 Å, =11.6080 Å, =15.2520 Å, =72.50° , =79.46° , =86.91° , =1915.00 Å3 and =1. The asymmetric unit of the crystal structure of (C14H16N2)3 (C14H17N2)2 [-Mo8 O26] contains -octamolybdate [-Mo8 O26]4− anions, two tolidine molecules and shows the presence of monoprotonated tolidine cations. One tolidine molecule and a -Mo8 O26 polyanions species lie across crystallographic inversion centres while the two tolidine molecules occupy general sites.

  1. Design, total synthesis, and evaluation of C13-C14 cyclopropane analogues of (+)-discodermolide.

    Science.gov (United States)

    Smith, Amos B; Xian, Ming; Liu, Fenghua

    2005-10-13

    [structure: see text] The design, total synthesis, and biological evaluation of two C13-C14-cyclopropyl analogues [(+)-1 and (+)-2] of (+)-discodermolide have been achieved. Key features of the syntheses include highly stereoselective, hydroxyl-directed cyclopropanations of vinyl iodides and higher order cuprate-mediated cross-coupling reactions between cyclopropyl iodides and alkyl iodides. Biological evaluation revealed that neither orientation of the cyclopropyl methylene completely substitutes for the C14 methyl found in (+)-discodermolide (3).

  2. Microbial Substrate Usage Indicated by C-14 Contents of Phospholipid Fatty Acids From Soil Organic Matter

    Science.gov (United States)

    Rethemeyer, J.; Nadeau, M. J.; Grootes, P. M.; Kramer, C.; Gleixner, G.

    2004-05-01

    Phospholipid fatty acids (PLFA's) are generally associated with viable (bacterial) cell membranes. They are thought to be short-lived under normal soil conditions. We compare the C-14 levels in PLFA's obtained from soil samples from the,clean" experimental site at Rotthalmünster (Germany) with those from the agricultural research station at Halle (Germany), where the soil is contaminated with,old" carbon from lignite mining and industry. The most abundant PLFA's were isolated via preparative capillary gas chromatography of their methyl-esters at the Max-Planck Institute, Jena, and their C-14 concentration was determined via accelerator mass spectrometry at the Leibniz-Labor, Kiel. The C-14 levels of three mono-unsaturated fatty acids (n-C17:1, n-C18:1 (and n-C16:1)) are not statistically significant different from those of the contemporaneous atmosphere, indicating these fatty acids were derived from fresh plant material. C-14 levels significantly above those of the atmosphere in three saturated fatty acids (i/a-C15:0, n-C16:0 and cy-C18:0) from the surface soil of Rotthalmünster must derive from carbon fixed from the atmosphere several years earlier, when levels of bomb-C-14, remaining from the atmospheric nuclear weapons tests, especially of the early 1960's, were still higher. Lower C-14 levels in the same compounds from the Halle surface soil indicate the incorporation of "old" contaminant carbon. A below- atmospheric C-14 concentration in n-C18:0 in Rotthalmünster surface soil may reflect the partial incorporation of carbon from older, pre-bomb times. The C-14 concentrations show these PLFA's were synthesized predominantly from recent to sub-recent photosynthetic compounds, while the significant differences in C-14 concentration, observed between the PLFA's, indicate their production from soil organic matter fractions of different (recent) age and C-14 content. The Halle results show "old" carbon may be incorporated into PLFA's and thus reenter the soil

  3. High-accuracy C-14 measurements for atmospheric CO2 samples by AMS

    NARCIS (Netherlands)

    Meijer, H.A.J.; Pertuisot, M.H.; van der Plicht, J.

    2006-01-01

    In this paper, we investigate how to achieve high-accuracy radiocarbon measurements by accelerator mass spectrometry (ANIS) and present measurement series (performed on archived CO2) of (CO2)-C-14 between 1985 and 1991 for Point Barrow (Alaska) and the South Pole. We report in detail the measurement

  4. 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

    of 2-3), C-14 uptake into the particulate plus the dissolved fractions approximated to net photosynthesis. Rate constants derived from the chemically determined changes were used to parameterize models that accounted for the respiration of photosynthetic products and for the recycling of respiratory CO...

  5. The early history of Moscow : C-14 dates from Red Square

    NARCIS (Netherlands)

    Alexandrovskiy, AL; Van Der Plicht, J; Krenke, N; Chichagova, O; Kovaliukh, N; Sulerzhitsky, LD; Mook, W.G.

    1998-01-01

    For the first time, a series of C-14 dates has been obtained for samples from the archaeological excavations in Red Square, the historical center of Moscow. The remains of burned dwellings from the bottom of the cultural layer were dated as well as dispersed charcoal from the underlying plough soil.

  6. A tree-ring and C-14 chronology of the key Sayan-Altai monuments

    NARCIS (Netherlands)

    Zaitseva, GI; Vasiliev, SS; Marsadolov, LS; Van der Plicht, J; Sementsov, AA; Dergachev, VA; Lebedeva, LM

    1998-01-01

    We present a radiocarbon chronology of key Sayan-Altai monuments from the Scythian period, based on a statistical analysis of dates produced in the 1980s and now supplemented with new dates. These new C-14 dates were produced for samples from the Tuekta-1 barrows (burial mounds) and were measured bo

  7. Dosimetry and reproducibility of a capsule-based C-14 urea breath test

    Energy Technology Data Exchange (ETDEWEB)

    Combs, M.J.; Stubbs, J.B.; Buck, D.A. [Univ. of Virginia, Charlottesville, VA (United States)]|[Oak Ridge Inst. for Science and Education, TN (United States)] [and others

    1995-05-01

    The aims of this study were (1) to determine the excretion of the C-14 and associated radiation dose and (2) to examine the reproducibility of a commercial C-14 urea breath test for H.pylori diagnosis. Tests were performed on twenty consenting volunteers (13M, 7F, 24-48 yr). Breath samples containing 1 mmol CO{sub 2} were obtained at 0,5,10,15,20,25,30 min. and 1,2,3,4,5,6,12, 24 hrs following administration of the 37kBq C-14 urea test capsule. A 24 hr urine collection was performed with each voiding collected separately. A repeat breath test was performed 24 hr after the first. H. pylori positive (HP+) was defined as a 15 minute breath sample >=50 dpm. Total urine excretion was obtained directly. Breath excretion was modeled by estimating the area under the excretion curve and using a constant factor of 884 mmol CO{sub 2}/ hr. Urine and breath excretion data in HP+ and H. pylori-negative (HP-) volunteers were pooled and fit to a monoexponential function thus estimating the cumulative urinary excretion of unmetabolized urea. Previously reported biokinetic models of C-14 urea and bicarbonate were used to estimate radiation doses form each compound. Weighted sums were calculated for each dose estimate using each group`s excretion fraction distribution. Both HP+ and HP- volunteers excreted an average of 73% of the C-14 over the first 24 hr. HP+ excretion was evenly divided between breath (34%) and urine (38%). HP-excretion is almost solely by the urinary pathway. The maximum dose for HP= was to the red marrow (0.0033 mGy) and a maximum of 0.0054 mGy to the urinary bladder wall for HP-. There was no difference between 15 inch breath samples on the two days (t-test, p>0.6). The minimum HP+ result at 15 inch was 270 dpm and the maximum HP- result at 15 inch was 18 dpm, indicating great separation between HP+ and HP- results. This study verifies previous dose estimates using C-14 excretion data. The test is sensitive and reproducible with a low radiation dose.

  8. C-14 content of ten meteorites measured by tandem accelerator mass spectrometry

    Science.gov (United States)

    Brown, R. M.; Andrews, H. R.; Ball, G. C.; Burn, N.; Imahori, Y.; Milton, J. C. D.; Fireman, E. L.

    1984-01-01

    Measurements of C-14 in three North American and seven Antarctic meteorites show in most cases that this cosmogenic isotope, which is tightly bound, was separated from absorbed atmospheric radiocarbon by stepwise heating extractions. The present upper limit to age determination by the accelerator method varies from 50,000 to 70,000 years, depending on the mass and carbon content of the sample. The natural limit caused by cosmic ray production of C-14 in silicate rocks at 2000 m elevation is estimated to be 55,000 + or - 5000 years. An estimation is also made of the 'weathering ages' of the Antarctic meteorites from the specific activity of loosely bound CO2 which is thought to be absorbed from the terrestrial atmosphere. Accelerator measurements are found to agree with previous low level counting measurements, but are more sensitive and precise.

  9. Synthesis and antibacterial activity of pleuromutilin derivatives with novel C(14) side chain

    Institute of Scientific and Technical Information of China (English)

    Li Qiang Fu; Chen Yu Ling; Xing Sheng Guo; Hui Li He; Yu She Yang

    2012-01-01

    In order to find novel antibacterial agents with superior antibacterial activity and overcoming multidrug resistance,a series of pleuromutilin derivatives with novel C(14) side chain were synthesized and evaluated for their in vitro antibacterial activities.The results of antibacterial acticities indicated that most of the derivatives showed potent activities against Gram-positive organisms.In particular,compound 10d exhibited the most potent inhibitory activity compared with pleuromutilin and linezoid,emerged as potential molecule for further investigation.

  10. The C$^{14}$N/C$^{15}$N Ratio in Diffuse Molecular Clouds

    CERN Document Server

    Ritchey, Adam M; Lambert, David L

    2015-01-01

    We report the first detection of C$^{15}$N in diffuse molecular gas from a detailed examination of CN absorption lines in archival VLT/UVES spectra of stars probing local diffuse clouds. Absorption from the C$^{15}$N isotopologue is confidently detected (at $\\gtrsim4\\sigma$) in three out of the four directions studied and appears as a very weak feature between the main $^{12}$CN and $^{13}$CN absorption components. Column densities for each CN isotopologue are determined through profile fitting, after accounting for weak additional line-of-sight components of $^{12}$CN, which are seen in the absorption profiles of CH and CH$^+$ as well. The weighted mean value of C$^{14}$N/C$^{15}$N for the three sight lines with detections of C$^{15}$N is $274\\pm18$. Since the diffuse molecular clouds toward our target stars have relatively high gas kinetic temperatures and relatively low visual extinctions, their C$^{14}$N/C$^{15}$N ratios should not be affected by chemical fractionation. The mean C$^{14}$N/C$^{15}$N ratio ...

  11. First-principles investigation of mechanical and electronic properties of LaAg5 Laves phase under pressure

    Institute of Scientific and Technical Information of China (English)

    高恩强; 黄福祥; 陈志谦; 王兰兰; 张照超

    2016-01-01

    The effects of applied pressure on the structural, mechanical, and electronic properties of LaAg5 compound were investi-gated employing the first-principles method based on the density functional theory. The mechanical results demonstrated that bulk modulus, shear modulus and Young’s modulus presented the linearly increasing dependences on the external pressure; theB/G and Poisson’s ratio indicated that LaAg5 compound was a ductile material with central forces in interatomic under pressure from 0 to 40 GPa; the universal anisotropic index was performed to investigate the elastic anisotropic of LaAg5. Additionally, the pressure de-pendence of the density of states and Mulliken charge were also discussed. The bonding characterization in LaAg5 was composed of metallic, covalent and ionic. The metallic component was derived from free-electron transferring from Ag-s and Ag-d to Ag-p, and from La-s to La-d. The ionic component was due to the charge movement from La to Ag. The covalent was owing to Ag-p-La-d bonding hybridization and Ag-s-Ag-p in the Ag atomic chains. The covalent and ionic bonds were stronger under pressure but there was no significant change in metallic nature.

  12. Study of the C-14-contamination potential of C-impurities in CuO and Fe

    NARCIS (Netherlands)

    Vandeputte, K; Moens, L; Dams, R; van der Plicht, Johannes

    1998-01-01

    The carbon concentration in CuO and iron was determined by isolating C. The values were in agreement with results reported in other studies. Contaminating carbon from CuO and Fe was transformed to AMS targets and measured for C-14. C-traces in CuO were shown to be the major contribution to the C-14

  13. Studies directed toward the total synthesis of discodermolide: asymmetric synthesis of the C1-C14 fragment.

    Science.gov (United States)

    Arefolov, Alexander; Panek, James S

    2002-07-11

    [structure: see text] A convergent and stereoselective assembly of the C1-C14 subunit of marine natural product (+)-discodermolide has been completed. The approach employs chiral allylsilane bond construction methodology to establish four of the eight stereogenic centers. Key fragment coupling is achieved via an efficient stereoselective acetate aldol reaction between C1-C6 and C7-C14 subunits.

  14. 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.

  15. 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.

  16. 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...

  17. 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...

  18. The C14(n,γ) cross section between 10 keV and 1 MeV

    Science.gov (United States)

    Reifarth, R.; Heil, M.; Forssén, C.; Besserer, U.; Couture, A.; Dababneh, S.; Dörr, L.; Görres, J.; Haight, R. C.; Käppeler, F.; Mengoni, A.; O'Brien, S.; Patronis, N.; Plag, R.; Rundberg, R. S.; Wiescher, M.; Wilhelmy, J. B.

    2008-01-01

    The neutron capture cross section of C14 is of relevance for several nucleosynthesis scenarios such as inhomogeneous Big Bang models, neutron induced CNO cycles, and neutrino driven wind models for the r process. The C14(n,γ) reaction is also important for the validation of the Coulomb dissociation method, where the (n,γ) cross section can be indirectly obtained via the time-reversed process. So far, the example of C14 is the only case with neutrons where both, direct measurement and indirect Coulomb dissociation, have been applied. Unfortunately, the interpretation is obscured by discrepancies between several experiments and theory. Therefore, we report on new direct measurements of the C14(n,γ) reaction with neutron energies ranging from 20 to 800 keV.

  19. Can the C-14 urea breath test reflect the extent and degree of ongoing helicobacter pylori infection

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Seok Tae; Sohn, Myung Hee; Lee, Seung Ok; Lee, Soo Taik; Jeong, Myung Ja [Chonbuk National Univ., Chonju (Korea, Republic of)

    2001-02-01

    The C-14 urea breath test (C-14 UBT) is the most specific noninvasive method to detect Helicobacter (H) pylori infection. We investigated if the C-14 UBT can reflect the presence and degree of H. pylori detected by gastroduodenoscopic biopsies (GBx). One hundred fifty patients (M:F=83:67,age 48.6{+-}11.2 yrs) underwent C-14 UBT, rapid urease test (CLO test) and GBx on the same day. For the C-14 UBT, a single breath sample was collected at 10 minutes after ingestion of C-14 urea (137 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). The results of CLO tests were classified as positive or negative according to color change. The results of GBx on 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 results with GBx grade as a gold standard. 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 92.5%, 88.4%, 97.1%, 88.4% and 91.3%, respectively. However, the CLO test had sensitivity, specificity, PPV, NPV and accuracy of 83.2%, 81.4%, 91.8%, 81.4% and 82.7%, respectively. The quantitative values of the C-14 UBT were 45 {+-} 27 dpm in grade 0, 707 {+-}584 dpm in grade 1, 1558{+-}584 dpm in grade 2, 1851{+-}604 dpm in grade 3, and 2719 {+-} 892 dpm in grade 4. A significant correlation (r=0.848, p<0.01) was found between C-14 UBT and the grade of distribution of H. pylori infection on GBx with giemsa stain. We conclude that the C-14 UBT is a highly accurate, simple and noninvasive method for the diagnosis of ongoing H. pylori infection and reflects the degree of bacterial distribution.

  20. 46 CFR 154.1860 - Integral tanks: Cargo colder than −10 °C (14 °F).

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Integral tanks: Cargo colder than â10 °C (14 °F). 154.1860 Section 154.1860 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK....1860 Integral tanks: Cargo colder than −10 °C (14 °F). The master shall ensure that an integral...

  1. 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.

  2. 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

  3. Processus préparant la construction et l’érosion des deltas de lave formés par les coulées du volcan Kilauea (Pu‘u ‘O‘o-Kupaianaha, Hawaï)

    OpenAIRE

    Marie, Guillaume

    2008-01-01

    La genèse des deltas de lave, formes construites lorsque des coulées de lave atteignent l’océan, est précédée d’une étape initiale durant laquelle un soubassement de débris hydroclastiques s’édifie progressivement. Les coulées de lave construisent sur cette assise une étroite banquette subaérienne, limitée par l’ancienne falaise, qui est soumise dans le même temps à l’érosion côtière. Le rôle des coups de boutoir des vagues sur une roche fortement diaclasée est mis en avant, notamment dans l’...

  4. Magnetic frustration and instability in Dy{sub 1-x}La{sub x}Mn{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Ouladdiaf, B. [Institut Laue-Langevin, BP 156, 38042, Grenoble Cedex 9 (France); Ballou, R. [Laboratoire de Magnetisme Louis Neel , CNRS, BP 166, 38042, Grenoble Cedex 9 (France); Deportes, J. [Laboratoire de Magnetisme Louis Neel , CNRS, BP 166, 38042, Grenoble Cedex 9 (France); Lelievre-Berna, E. [Laboratoire de Magnetisme Louis Neel , CNRS, BP 166, 38042, Grenoble Cedex 9 (France)

    1995-02-09

    A structural dimorphism exists in the Dy{sub 1-x}La{sub x}Mn{sub 2} (0.05{<=}x{<=}0.25) compounds. When the C15 Laves phase is stabilized, no evidence for a long range order is found although the magnetovolume effect is observed at 34 K. When the C14 Laves phase is stabilized, an antiferromagnetic order sets in below 38 K without any magnetovolume effect. ((orig.)).

  5. 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.

  6. Phase diagram determination and thermodynamic modeling of the Cu-Mg-Si system

    Directory of Open Access Journals (Sweden)

    Zhao J.

    2016-01-01

    Full Text Available 13 ternary Cu-Mg-Si alloys were prepared by means of the powder metallurgy method. Phase equilibria at 500 and 700 oC of the Cu-Mg-Si system were determined using X-ray diffraction analysis (XRD. The existence of 3 ternary compounds in this system was verified: CuMgSi_Sigma (Cu16Mg6Si7, Tau (Cu3Mg2Si, and Laves ((Cu0.8Si0.22(Mg0.88Cu0.12. A thermodynamic modeling for the Cu-Mg-Si system was then conducted on the basis of the experimental data obtained in this work and those critically reviewed from the literature. The complex phase relationship between Laves phase and other phases has been successfully modeled in this work. Comparisons between the calculated and the measured phase diagrams show that most of the experimental data can be reproduced by the presently obtained thermodynamic parameters.

  7. The synthetic cationic lipid diC14 activates a sector of the Arabidopsis defence network requiring endogenous signalling components.

    Science.gov (United States)

    Cambiagno, Damián Alejandro; Lonez, Caroline; Ruysschaert, Jean-Marie; Alvarez, María Elena

    2015-12-01

    Natural and synthetic elicitors have contributed significantly to the study of plant immunity. Pathogen-derived proteins and carbohydrates that bind to immune receptors, allow the fine dissection of certain defence pathways. Lipids of a different nature that act as defence elicitors, have also been studied, but their specific effects have been less well characterized, and their receptors have not been identified. In animal cells, nanoliposomes of the synthetic cationic lipid 3-tetradecylamino-tert-butyl-N-tetradecylpropionamidine (diC14) activate the TLR4-dependent immune cascade. Here, we have investigated whether this lipid induces Arabidopsis defence responses. At the local level, diC14 activated early and late defence gene markers (FRK1, WRKY29, ICS1 and PR1), acting in a dose-dependent manner. This lipid induced the salicylic acid (SA)-dependent, but not jasmonic acid (JA)-dependent, pathway and protected plants against Pseudomonas syringae pv. tomato (Pst), but not Botrytis cinerea. diC14 was not toxic to plant or pathogen, and potentiated pathogen-induced callose deposition. At the systemic level, diC14 induced PR1 expression and conferred resistance against Pst. diC14-induced defence responses required the signalling protein EDS1, but not NDR1. Curiously, the lipid-induced defence gene expression was lower in the fls2/efr/cerk1 triple mutant, but still unchanged in the single mutants. The amidine headgroup and chain length were important for its activity. Given the robustness of the responses triggered by diC14, its specific action on a defence pathway and the requirement for well-known defence components, this synthetic lipid is emerging as a useful tool to investigate the initial events involved in plant innate immunity.

  8. Short synthesis of the C1-C14 stretch of discodermolide from building blocks prepared by asymmetric catalysis.

    Science.gov (United States)

    Cao, Huanyan; Parker, Kathlyn A

    2008-04-01

    A convergent and stereoselective synthesis of the C1-C14 stretch of (+)-discodermolide demonstrates the utility of the "asymmetric catalysis approach" to complex polypropionates. The preparation of this complex synthon requires 15 steps in the longest linear sequence and 19 steps total from inexpensive materials.

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

    OpenAIRE

    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 diastereoselectiv...

  10. AMS C-14 chronology of woolly mammoth (Mammuthus primigenius Blum.) remains from the Shestakovo upper paleolithic site, western Siberia : Timing of human-mammoth interaction

    NARCIS (Netherlands)

    Zenin, VN; van der Plicht, J; Orlova, LA; Kuzmin, YV

    2000-01-01

    We present a series of AMS C-14 dates from the upper paleolithic site of Shestakovo, southwestern Siberia. The C-14 ages range between 21 and 26 ka BP, corresponding to the so-called Sartan Glacial and Karginian Interglacial in Siberia. The majority of dates are from woolly mammoth bones, obtained f

  11. Identification of Site of Morphine Action in Pregnant Wistar Rat Placenta Tissue: A C14-Morphine Study

    Directory of Open Access Journals (Sweden)

    Leila Dehghani

    2012-01-01

    Full Text Available Objective: In previous studies it has been emphasized that the site of morphine action may be either in the embryo or the placenta. In the present study, we attempt to identify the site of morphine action on the fetal section of Wistar rat placenta by using C14-morphine.Materials and Methods: In this study (experimental, female Wistar rats (weights: 170-200 g were mated with male rats and their coupling times recorded. Experimental groups received daily doses of 0.05 mg/ml of C14-morphine in their drinking water. On the 9th and14th embryonic days, the pregnant rats were anesthetized and the placenta and uterus surgically removed. Placentas were fixed in 10% formalin for two weeks, then processed, sectioned in 5 μm and 25 μm thicknesses, and fixed on glass slides for further evaluation. The 25 μm sections were delivered to black and white film for three days. Films were processed and evaluated with a digital inverse microscope for possible radiological impression. The 5 μm sections were processed for hematoxylin and eosin (H&E staining, and evaluated by light microscope and MOTIC software.Results: Our results indicated that the site of action of C14-morphine was possibly located on the blood plexus of the fetal portion of the placenta. In addition, oral morphine consumption was shown to inhibit fetal and maternal placental development in the experimental groups.Conclusion: We conclude that morphine’s effectiveness on the reduction of embryo growth and development may be via its effects on the blood plexus of the fetal section of the placenta.

  12. A stereoselective synthesis of the C(3)-C(13) and C(14)-C(24) fragments of macrolactin A

    Institute of Scientific and Technical Information of China (English)

    李树坤; 徐睿; 肖相树; 白东鲁

    2000-01-01

    Synthetic studies towards the C(3)-C(13) and C(14)-C(24) segments (3, 4) of the potent antiviral and antitumor compound macrolactin A (1)are presented. Compound 3 was constructed via a convergent and facile apprroach, exploiting Wittig olefination to generate the sensitive E, Z-diene moiety. Compound 4 was synthesized fr om the chiral-pool derived sulfone 39a via an α-alkylation-desulfonation reaction sequence.Cu(Ⅱ)-catalyzed coupling of a Grignard reagent with an allylic bromide and Julia olefination were also investigated for the preparation of compound 4.

  13. 11-year cycle solar modulation of cosmic ray intensity inferred from C-14 content variation in dated tree rings

    Science.gov (United States)

    Fan, C. Y.; Chen, T. M.; Yun, S. X.; Dai, K. M.

    1983-01-01

    A liquid scintillation-photomultiplier tube counter system was used to measure the Delta-C-14 values of 60 tree rings, dating from 1866 to 1925, that were taken from a white spruce grown in Canada at 68 deg N, 130 deg W. A 10-percent variation is found which is anticorrelated with sunspot numbers, although the amplitude of the variation is 2-3 times higher than expected in trees grown at lower latitudes. A large dip in the data at about 1875 suggests an anomalously large modulation of cosmic ray intensity during the 1867-1878 AD solar cycle, which was the most active of the 19th century.

  14. Shell Model Description of the C14 Dating β Decay with Brown-Rho-Scaled NN Interactions

    Science.gov (United States)

    Holt, J. W.; Brown, G. E.; Kuo, T. T. S.; Holt, J. D.; Machleidt, R.

    2008-02-01

    We present shell model calculations for the beta decay of C14 to the N14 ground state, treating the states of the A=14 multiplet as two 0p holes in an O16 core. We employ low-momentum nucleon-nucleon (NN) interactions derived from the realistic Bonn-B potential and find that the Gamow-Teller (GT) matrix element is too large to describe the known lifetime. By using a modified version of this potential that incorporates the effects of Brown-Rho scaling medium modifications, we find that the GT matrix element vanishes for a nuclear density around 85% that of nuclear matter. We find that the splitting between the (Jπ,T)=(1+,0) and (Jπ,T)=(0+,1) states in N14 is improved using the medium-modified Bonn-B potential and that the transition strengths from excited states of C14 to the N14 ground state are compatible with recent experiments.

  15. Low-Energy Grazing Ion-Scattering From Alkali-Halide Surfaces: A Novel Approach To C-14 Detection

    Science.gov (United States)

    Meyer, F. W.; Galutschek, E.; Hotchkis, M.

    2009-03-01

    Carbon-14 labeled compounds are widely used in the pharmaceutical industry, e.g., as tracers to determine the fate of these compounds in vivo. Conventional accelerator mass spectrometry (AMS) is one approach that offers sufficiently high sensitivity to avoid radiological waste and contamination issues in such studies, but requires large, expensive facilities that are usually not solely dedicated to this task. At the ORNL Multicharged Ion Research Facility (MIRF) we are exploring a small size, low cost alternative to AMS for biomedical 14C tracer studies that utilizes ECR-ion-source-generated keV-energy-range multicharged C beams grazingly incident on an alkali halide target, where efficient negative ion production by multiple electron capture takes place. By using C ion charge states of +3 or higher, the molecular isobar interference at mass 14, e.g. 12CH2 and 13CH, is eliminated. The negatively charged ions in the beam scattered from the alkali halide surface are separated from other scattered charge states by two large acceptance (˜15 msr) stages of electrostatic analysis. The N-14 isobar interference is thus removed, since N does not support a stable negative ion. Initial results for C-14 detection obtained using C-14 enriched CO2 from ANSTO will be described.

  16. Accelerated molecular evolution of insect orthologues of ERG28/C14orf1: a link with ecdysteroid metabolism?

    Indian Academy of Sciences (India)

    Reiner A. Veitia; Laurence D. Hurst

    2001-04-01

    We have analysed the evolution of ERG28/C14orf1, a gene coding for a protein involved in sterol biosynthesis. While primary sequence of the protein is well conserved in all organisms able to synthesize sterols de novo, strong divergence is noticed in insects, which are cholesterol auxotrophs. In spite of this virtual acceleration, our analysis suggests that the insect orthologues are evolving today at rates similar to those of the remaining members of the family. A plausible way to explain this acceleration and subsequent stabilization is that Erg28 plays a role in at least two different pathways. Discontinuation of the cholesterogenesis pathway in insects allowed the protein to evolve as much as the function in the other pathway was not compromised.

  17. 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)

  18. Magnetism and electronic structure for RMn{sub 2} (R=Y and lanthanoids) with the cubic Laves phase (C15) structure

    Energy Technology Data Exchange (ETDEWEB)

    Terao, Kiyosi E-mail: terk005@gipac.shinshu-u.ac.jp; Yamada, Hideji

    2004-05-01

    Ab initio calculations for the electronic structure are carried out by means of LMTO-ASA with and without the GGA correction. The observed antiferromagnetic state with complicated spin configuration has slightly higher energy than that with the layered spin configuration near the observed volume and slightly lower than that for larger volume. In ferromagnetic configuration, Mn moment shows complicated dependence on volume and magnetic field.

  19. 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

  20. 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

    2014-01-01

    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.

  1. 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.

  2. hCLE/C14orf166 associates with DDX1-HSPC117-FAM98B in a novel transcription-dependent shuttling RNA-transporting complex.

    Directory of Open Access Journals (Sweden)

    Alicia Pérez-González

    Full Text Available hCLE/C14orf166 is a nuclear and cytoplasmic protein that interacts with the RNAP II, modulates nuclear RNA metabolism and is present in cytoplasmic RNA granules involved in localized translation. Here we have studied whether hCLE shares common interactors in the nucleus and the cytosol, which could shed light on its participation in the sequential phases of RNA metabolism. Nuclear and cytoplasmic purified hCLE-associated factors were identified and proteins involved in mRNA metabolism, motor-related proteins, cytoskeletal and translation-related factors were found. Purified hCLE complexes also contain RNAs and as expected some hCLE-interacting proteins (DDX1, HSPC117, FAM98B were found both in the nucleus and the cytoplasm. Moreover, endogenous hCLE fractionates in protein complexes together with DDX1, HSPC117 and FAM98B and silencing of hCLE down-regulates their nuclear and cytosolic accumulation levels. Using a photoactivatable hCLE-GFP protein, nuclear import and export of hCLE was observed indicating that hCLE is a shuttling protein. Interestingly, hCLE nuclear import required active transcription, as did the import of DDX1, HSPC117 and FAM98B proteins. The data indicate that hCLE probably as a complex with DDX1, HSPC117 and FAM98B shuttles between the nucleus and the cytoplasm transporting RNAs suggesting that this complex has a prominent role on nuclear and cytoplasmic RNA fate.

  3. Syntheses and Structures of Two New Coordination Polymers:[Cu(C14H9O4)(C14H10O4)(C12H12N2)2] and [Ag(C14H9O4)(C13H14N2)]·0.5 H2O

    Institute of Scientific and Technical Information of China (English)

    傅志勇; 胡胜民; 杜文新; 张建军; 项生昌; 吴新涛

    2004-01-01

    Under hydrothermal conditions, two new ribbon-like structures, [Cu(C14H9O4)-analysis revealed that these structures were constructed by mixed ligands. The coordination polymer forms the basic architecture while the weak interactions extend the framework into a secondary structure. The whole structures of them are governed by collaboration of the strong and weak interactions. Compound 1 crystallizes in monoclinic, space group C2/c with a = 17.0485(3), b =1 1.0558(3), c = 22.7623(4) A, β = 102.465(1)°, V = 4189.2(2) A3, Z = 4, Mr = 915.44, Dc = 1.451g/mL, F(000) = 1900 andμ(MoKα) = 0.587 cm-1. The final R and wR are 0.0030 and 0.1022,respectively for 3037 observed reflections with I > 2σ(I). Compound 2 crystallizes in monoclinic,space group P21/c with a = 11.5963(4), b = 11.7004(5), c = 17.1254(5) A,β = 95.620(1)°, V =2312.4(1) A3, Z = 4, Mr = 556.35, Dc = 1.598 g/mL, F(000) = 1132 andμ(MoKα) = 0.912 cm-1The final R and wR are 0.0431 and 0.1050, respectively for 2629 observed reflections with I > 2σ(I).

  4. 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

  5. Characterization of phases in the Fe-Nb system

    Science.gov (United States)

    Raposo, M. T.; Ardisson, J. D.; Persiano, A. I. C.; Mansur, R. A.

    1994-12-01

    The Fe-Nb system was investigated by means of X-ray diffraction and Mössbauer spectroscopy (at 300 and 77 K), in the range from 1 to 66.7 at%. We have found that the limit of solubility of Fe in Nb at 1100°C is between 3 and 4 at% Fe, and observed the coexistence of the Nb solid solution (Nbss) phase and Fe21Nb19 in the range from 4 to 40 at% Fe. The Mössbauer parameters of all the single phases are reported. The lattice parameters of Nbss phase present no significant variation with the Nb content. The X-ray pattern for the Fe21Nb19 phase could not be solved. The Laves phase Fe2Nb presents Mössbauer and X-ray parameters that agree with the literature.

  6. Initial study on Z-phase strengthened 9-12% Cr steels by atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Fang; Andren, Hans-Olof [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Applied Physics

    2010-07-01

    The microstructure of two different types of Z-phase strengthened experimental steels, CrNbN-based or CrTaN-based, was investigated. Both steels underwent aging at 650 C for relatively short period of time, 24 hours or 1005 hours. Atom probe tomography was used to study the chemical composition of the matrix and precipitates, and the size and number density of the small precipitates. Both steels contain Laves phase at prior austenite grain boundaries and martensitic lath boundaries. The CrTaN-based steel was found more promising due to its finer and more densely distributed precipitates after 1005 hour aging. (orig.)

  7. 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)

  8. Genes encoding chimeras of Neurospora crassa erg-3 and human TM7SF2 proteins fail to complement Neurospora and yeast sterol C-14 reductase mutants

    Indian Academy of Sciences (India)

    A Prakash; Durgadas P Kasbekar

    2002-03-01

    The human gene TM7SF2 encodes a polypeptide (SR-1) with high sequence similarity to sterol C-14 reductase, a key sterol biosynthetic enzyme in fungi, plants and mammals. In Neurospora and yeast this enzyme is encoded by the erg-3 and erg24 genes respectively. In an effort to demonstrate sterol C-14 reductase activity for SR-1 we constructed six recombinant genes coding for chimeras of the Neurospora erg-3 and SR-1 protein sequences and tested them for complementation of the Neurospora erg-3 mutant. To our surprise, all the chimeras failed to complement erg-3. A few of the chimeric proteins were also tested against the yeast erg24 mutant, but again there was no complementation. We discuss some reasons that might account for these unexpected findings.

  9. Experimental-study of the interactions between a natural C-14 radiolabeled sediment and a deposit-feeding bivalve : Abra alba

    OpenAIRE

    Amouroux, Jm; Gremare, A.; Cahet, G.

    1991-01-01

    Changes of radioactivity in a natural C-14 labelled sediment were monitored over a 120-hour period in the presence and in the absence of the deposit-feeding bivalve Abra alba. In both cases, the sediment showed great instability during the first ten hours of the experiment. The consequences of this result on the experimental protocol used for the study of the interactions between natural sediments and deposit-feeders are discussed. In controls, the instability is produced by an initial decrea...

  10. 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.

  11. 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

  12. Status quo of the storage of C-14 containing waste from German high-temperature and research reactors and the strategy for their future storage; Status quo der Lagerung C-14-haltiger Abfaelle aus deutschen Hochtemperatur- und Forschungsreaktoren und Strategie zu deren kuenftigen Endlagerung. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Doerr, S.; Bollingerfehr, W.; Filbert, W.

    2014-12-15

    The German research reactors and the high-temperature reactors (AVR, THTR 300) used graphite as reflector and/or moderator materials. Due to the activation of these materials there exists a significant amount of C-14, H-3 and Co-60.The project included the assessment of the respective amount of materials from all facilities, the legal framework for interim storage, transport and final disposal.

  13. First principles prediction of a new high-pressure phase and transport properties of Mg2Si

    Science.gov (United States)

    Kessair, S.; Arbouche, O.; Amara, K.; Benallou, Y.; Azzaz, Y.; Zemouli, M.; Bekki, M.; Ameri, M.; Bouazza, B. S.

    2016-12-01

    We have investigated the structural properties of seven different structure types of Mg2Si which include the cubic CaF2, orthorhombic PbCl2, hexagonal Ni2In, tetragonal Al2Cu, Laves phase (cubic MgCu2), hexagonal MgZn2 and dihexagonal MgNi2 type of structures, using a full potential linearized augmented plane wave method as implemented in WIEN2k within the framework of density functional theory. The exchange-correlation potential is treated by the new form of generalized gradient approximation (GGA-PBEsol). In total energy calculations it is clearly seen that cubic CaF2-type structure is stable at ambient conditions, and it undergoes a first-order phase transition to orthorhombic PbCl2-type, then to the hexagonal Ni2In-type structure and finally to the cubic Laves phase MgCu2-type. A new structure type is predicted to be stable at high pressure. Moreover, we intend to combine the electronic structure calculations performed by mean of generalized gradient approximation and modified Becke-Johnson potential with Boltzmann transport theory as incorporated in BoltzTraP code to interpret and predict the thermoelectric performance of each stable phase as a function of the chemical potential at various temperatures. We find a high thermoelectric thermopower values in cubic CaF2-type structure that could promise an excellent candidate for potential thermoelectric applications.

  14. 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

  15. Properties of Zr-Ti-V-Mn-Ni hydride alloy

    Institute of Scientific and Technical Information of China (English)

    文明芬; 翟玉春; 王新海; 陈廉

    2002-01-01

    Six kinds of Zr-based hydride alloy were designed. XRD analyses show that the main phase of Zr1-xTix-(NiCoMnV)2.1 alloy is Laves C15 when x is between 0 and 0.5,but the more the content of Ti, the more the Laves C14 phases. The amount of Laves C14 can be up to the amount of Laves C15 after substituted V and Fe by V-Fe alloy in Zr0.6-Ti0.4(NiCoMnVFeCr)1.7 alloy. The electrochemical measurements show that the discharge capacity of Zr0.9Ti0.1-(NiCoMnV)2.1 electrode is about 340mA * h/g at 60mA/g, but with increasing the amount of Ti, the discharge capacity of alloy electrode abruptly decreases; at 300mA/g current density, its Kr can be up to 91%. The discharge capacity of Zr0.6-Ti0.4-(NiCoMn(V-Fe)Cr)1.62 alloy electrode is about 200mA * h/g at first cycle, the maximum capacity is more than that of the electrode with pure V, and about 315mA * h/g.

  16. 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

  17. Titanium carbide, nitride and carbonitrides: a 13C, 14N, 15N and 47,49Ti solid-state nuclear magnetic resonance study.

    Science.gov (United States)

    MacKenzie, K J; Meinhold, R H; McGavin, D G; Ripmeester, J A; Moudrakovski, I

    1995-05-01

    The first 47,49Ti, 13C, 14N and 15N solid-state nuclear magnetic resonance (NMR) spectra of titanium carbide, nitride and a series of cubic carbonitrides have been obtained under both static and magic-angle spinning (MAS) conditions. The 15N samples were isotopically enriched by gas-solid exchange at 1000 degrees C in a closed system. The Ti spectra of the carbide and nitride are sharp, reflecting the well defined cubic symmetry of these compounds, but become considerably broadened in the carbonitride series, with the spectra being approximately the sum of TiC and TiN together with some small electric field gradient (EFG) effects. The resonance positions and widths of all the NMR spectra change as carbon is progressively replaced by nitrogen. A relationship is observed between the 13C chemical shift and the nitrogen content of the carbonitrides, suggesting a possible NMR method for estimating the composition of these compounds. Although electron paramagnetic resonance (EPR) spectra of all these compounds show typically metallic behaviour, the NMR spectra show few effects attributable to conduction electrons, probably due to the lack of s-orbital contributions to the conduction band.

  18. Rapid responses of C14 clone of Eucalyptus globulus to root drought stress: Time-course of hormonal and physiological signaling.

    Science.gov (United States)

    Granda, Víctor; Cuesta, Candela; Alvarez, Rubén; Ordás, Ricardo; Centeno, María Luz; Rodríguez, Ana; Majada, Juan Pedro; Fernández, Belén; Feito, Isabel

    2011-05-01

    The responses of juvenile plants of forest crops to drought stress are a key stage in the survival of forest populations. In this work, a suitable experimental system to study the early drought resistance mechanisms and signaling in a drought-tolerant clone (C14) of Eucalyptus globulus Labill is proposed. This system, using hydroponic culture and an osmotic agent, polyethylene glycol 8000, was demonstrated to induce severe stress in the root area, affecting the responses of the plantlets at the aerial level. These responses were very fast, beginning only 3h after the induction of stress, and the results highlight the roles of xylematic abscisic acid (ABA) and pH changes over other signals, such as cytokinins, as early chemical signals in rapid water stress. The relationship between these chemical factors, ABA and pH, and the physiological and water parameters observed were significant, supporting their proposed principal role. This work aids our understanding of underlying responses to hydrological limitations of forest crops, and provides valuable information for further physiological and molecular studies of water stress in this and other tree species.

  19. Ternary mixtures of alkyltriphenylphosphonium bromides (C12TPB, C14TPB and C16TPB) in aqueous medium: their interfacial, bulk and fluorescence quenching behaviour

    Indian Academy of Sciences (India)

    Gargi Basu Ray; Soumen Ghosh; Satya P Moulik

    2010-03-01

    The self-aggregation behaviour of ternary mixtures of alkyl (C$_{12}^{-}$, C$_{14}^{-}$ and C$_{16}^{-}$) triphenylphosphonium bromides was studied by conductometry and tensiometry. The pure surfactants showed two Critical Micellar Concentrations (CMCs) by conductometry, but their ternary mixtures produce single CMC both by conductometry and tensiometry. The CMC values determined were found to be lower than that obtained from Clint equation suggesting synergistic interaction among the monomers within the micelles. Their bulk properties, like fraction of counterions bound to the micelles and free energy of micellization were evaluated. Interfacial parameters, like surface excess, minimum head group area of monomer and free energy of adsorption were also assessed. Interfacial adsorption was found to be more spontaneous than micellization. The head group area per monomer in ternary systems was larger than pure systems due to stronger electrostatic repulsion among the charged head groups. The values of the packing parameters supported the pure as well as ternary micelles to be spherical. The TPB surfactants efficiently quenched pyrene fluorescence; the performances of the homologues in this respect were assessed.

  20. Synthesis and Structural Characterization of Two Molybdenum—phosphate Cluster Compounds:(C14N14H63)Na(H2Mo6P4O31)2·8H2O and (C14N14H63)Na(H2Mo6P4O31)2·5H2O

    Institute of Scientific and Technical Information of China (English)

    温福山; 陈伟; 等

    2002-01-01

    (C14N14H63)Na(H2Mo6P4O31)2·8H2O with amine-separatecd sodium molybdenumphosphate clusters and (C14N14H63)Na(H2Mo6P4O31)2·5H2O (2) with H-bonded cluster layers were synthesized from hydrothermal systems.Compound 1 crystal-lizes in the triclinic space group P-↑1 with a=1.27445(2) nm,b=1.37183(3)nm,c=1.41515(3) nm,α=100.497(1)°,β=109.064(1)° and γ=115.498(1)°,Whereas compound 2 has a monoclinic space group P21/n with a=1.3418(5)nm,b=2.7787(12)nm,c=2.0314(10)nm and β=96.571(14)° There exist protonated ethylenediamine cations and H2O molecules between adjacent clusters,connecting the clusters through H-bonds.

  1. 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.

  2. Crystal structures and phase stability in pseudobinary CaAl 2-xZn x

    Science.gov (United States)

    Söderberg, Karin; Boström, Magnus; Kubota, Yoshiki; Nishimatsu, Takeshi; Niewa, Rainer; Häussermann, Ulrich; Grin, Yuri; Terasaki, Osamu

    2006-08-01

    Samples in the pseudobinary system CaAl 2-xZn x ( 0⩽x⩽2) were synthesised from the elements. Three different structure types, the C15 and C36 Laves phase structures and the KHg 2 (CeCu 2) structure, were observed. The structures and homogeneity ranges of the underlying phases were investigated by electron microscopy and thermal analysis as well as X-ray powder diffraction. The stability ranges for the different structure types were found to be 0⩽x⩽0.18, 0.28⩽x⩽0.68 and 0.93⩽x⩽2 for the C15, C36 and KHg 2 structure types, respectively.

  3. Orientation relationships between icosahedral clusters in hexagonal MgZn2 and monoclinic Mg4Zn7 phases in Mg-Zn(-Y) alloys

    Science.gov (United States)

    Rosalie, Julian M.; Somekawa, Hidetoshi; Singh, Alok; Mukai, Toshiji

    2011-07-01

    Intermetallic precipitates formed in heat-treated and aged Mg-Zn and Mg-Zn-Y alloys have been investigated via electron microscopy. Coarse spheroidal precipitates formed on deformation twin boundaries contained domains belonging to either the MgZn2 hexagonal Laves phase or the monoclinic Mg4Zn7 phase. Both phases are structurally related to the quasi-crystalline phase formed in Mg-Zn-Y alloys, containing icosahedrally coordinated zinc atoms arranged as a series of broad rhombohedral units. This rhombohedral arrangement was also visible in intragranular precipitates where local regions with the structures of hexagonal MgZn2 and Mg4Zn7 were found. The orientation adopted by the MgZn2 and Mg4Zn7 phases in twin-boundary and intragranular precipitates was such that the icosahedral clusters were aligned similarly. These results highlight the close structural similarities between the precipitates of the Mg-Zn-Y alloy system.

  4. Unusual phase behavior of decane-dodecane mixtures confined in SBA-15: Size effect on binary phase diagram

    Institute of Scientific and Technical Information of China (English)

    Hai Rong Pei; Xiao Yan; Xiao Zheng Lan

    2012-01-01

    Phase behavior of normal decane-dodecane (n-C10H22-C12H26,C10-C12) system confined in SBA-15 (Santa Barbara Amorphous,pore diameters 3.8,7.8,and 17.2 nm) has been studied by using differential scanning calorimetry.It has been found solid-liquid phase diagram of the C 10-C12/SBA-15 system is composed of a straight line (3.8 nm),a curve (7.8 nm) and a loop line (17.2 nm).The growth of the phase diagram clearly shows the size effect on phase behavior of binary alkanes.Phase behavior has been compared among the systems C10H22-C12H26/SBA-15,C12H26-C14H30/SBA-15 and C14H30-C16H34/SBA-15.

  5. The influence of theMycobacterium tuberculosis(MTB)-specific peptides E6, E7 and C14 on the monocyte-macrophage polarization%结核特异性多肽E6、E7和C14对单核-巨噬细胞亚型极化的影响

    Institute of Scientific and Technical Information of China (English)

    申东梅; 方毅敏; 申雁鸣; 刘国标; 姚亚男; 赖小敏

    2016-01-01

    Objective To explore the influence ofMycobacterium tuberculosis(MTB)-specific peptide to monocyte-macrophage polarization by utilizing flow cytometry to investigate the expression of CD14/CD16/CD163 of the cells. Methods The expressions of M1 (CD14+CD16+)/M2 (CD14+CD163+) of the monocytes (THP-1, and the monocytes from the hydrothorax and peripherial blood from tuberculosis (TB) patients) were detected by flow cytometry with 3 MTB-specific peptides as stimulants at the different time. Results The positive percentages of CD16/CD163 of THP-1 cell line treated with the MTB peptide E6 at the times 24 + 0 h, 24 +24 h, 24 + 48 h, and 24 + 72 h were 16.85%/13.78%, 19.59%/15.68%, 18.14%/14.19%, 13.61%/11.47%, respectively. The MTB peptide E7 exerted effect similar to E6, but the MTB peptide C14 showed a less effect. After treated with E6 at 19 h, the positive percentages of CD14+CD16+of the monocytes of hydrothorax from 2 TB patients were 1.66% (No. 1 patient) and 4.37% (No. 2 patient), as well as CD14+CD163+were 1.76% (No. 1 patient) and 2.82% (No. 2 patient). The difference between the two types of cells was not very remarkable, but the difference seemed to be significant when added another detection mark CD86 to CD14+CD16+, and CD206 to CD14+CD163+, respectively. E7 and C14 had the similar corresponding effects on the polarization of monocytes of hydrothorax and peripherial blood as observed at THP-1 cell line. Conclusion 3 MTB-specific peptides, especially E6 and E7, can mainly induce THP-1 and the monocytes of hydrothorax and peripherial blood from TB patients towards the M1 macrophage polarization.%目的:运用流式细胞术检测单核-巨噬细胞极化亚型 M1(CD14+CD16+)及 M2(CD14+CD163+),探讨结核特异性多肽对单核-巨噬细胞极化分型的影响。方法以3种结核特异性多肽 E6、E7和 C14作为刺激物,刺激人急性白血病单核细胞株(THP-1细胞)、结核病患者胸水单个核细胞及外周血单个核细胞

  6. First-Principles Point Defect Models for Zr7Ni10 and Zr2Ni7 Phases

    Directory of Open Access Journals (Sweden)

    Diana F. Wong

    2016-06-01

    Full Text Available Synergetic effects in multi-phased AB2 Laves-phase-based metal hydride (MH alloys enable the access of high hydrogen storage secondary phases, despite the lower absorption/desorption kinetics found in nickel/metal hydride (Ni/MH batteries. Alloy design strategies to further tune the electrochemical properties of these secondary phases include the use of additives and processing techniques to manipulate the chemical nature and the microstructure of these materials. It is also of particular interest to observe the engineering of constitutional point defects and how they may affect electrochemical properties and performance. The Zr7Ni10 phase appears particularly prone to point defects, and we use density functional theory (DFT calculations coupled with a statistical mechanics model to study the theoretical point defects. The Zr2Ni7 phase appears less prone to point defects, and we use the Zr2Ni7 point defect model, as well as experimental lattice parameters, with Zr7Ni10 phases from X-ray diffraction (XRD as points of comparison. The point defect models indicate that anti-site defects tend to form in the Zr7Ni10 phase, and that these defects form more easily in the Zr7Ni10 phase than the Zr2Ni7 phase, as expected.

  7. 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.

  8. Phase Structure and High-Temperature Mechanical Properties of Two-Phase Fe-25Al- xZr Alloys Compared to Three-Phase Fe-30Al- xZr Alloys

    Science.gov (United States)

    Kejzlar, Pavel; Kratochvíl, Petr; Král, Robert; Vodičková, Věra

    2014-01-01

    The structure and high-temperature mechanical properties of Fe-30 at. pct Al and Fe-25 at. pct Al alloys with various Zr contents are compared. The scanning electron microscope images in chemical contrast mode (R-BSE) as well as EDS, EBSD, and X-ray diffraction were used to determine the structure and phase composition. The as-cast alloys (both Fe-30Al and Fe-25Al) were observed to be two-phase DO3/B2 + Laves phase λ 1 (Fe,Al)2Zr alloys with typical fine lamellar eutectic areas. During the heat treatment of the Fe-25Al alloys, their structure transformed from a DO3/B2 matrix with fine lamellar eutectic into λ 1 globular particles situated in a DO3/B2 matrix. The same structure of Fe-30Al alloys decomposed into three phases: λ 1 and τ 1 Zr(Fe,Al)12 particles in a DO3/B2 matrix. The hardening in both groups of alloys (Fe-25Al and Fe-30Al) due to the presence of Zr-containing λ 1 and τ 1 phases is compared.

  9. The Cr–Fe–Nb ternary system: Experimental isothermal sections at 700 °C, 1050 °C and 1350 °C

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, Aurélie, E-mail: a.jacob@fz-juelich.de [Forschungszentrum Juelich, IEK-2, 52425 Juelich (Germany); Schmetterer, Clemens [Forschungszentrum Juelich, IEK-2, 52425 Juelich (Germany); Fraunhofer-UMSICHT, 92237 Sulzbach-Rosenberg (Germany); Grüner, Daniel; Wessel, Egbert [Forschungszentrum Juelich, IEK-2, 52425 Juelich (Germany); Hallstedt, Bengt [Institute for Materials Applications in Mechanical Engineering, RWTH Aachen University, Augustinerbach 4, 52062 Aachen (Germany); Singheiser, Lorenz [Forschungszentrum Juelich, IEK-2, 52425 Juelich (Germany)

    2015-11-05

    The Cr–Fe–Nb system is an important constituent system in the development of Laves-phase reinforced steels. It contains two Laves-phase polytypes, i.e. C14–Fe{sub 2}Nb and C15–Cr{sub 2}Nb. While the first forms a substantial ternary solid solution with Cr, the latter only shows a limited solubility for Fe. The phase equilibria in the Cr–Fe–Nb system are shown in three isothermal sections at 700, 1050 and 1350 °C. Scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM/EDX), X-ray diffraction (XRD) and electron back scatter diffraction (EBSD) were used to determine the phase equilibria from which the isothermal sections were constructed. - Highlights: • Determination of Phase Equilibria in the Cr–Fe–Nb system at 700, 1050 and 1350 °C. • Isothermal sections at 700, 1050 and 1350 °C were established. • Homogeneity range of Laves phases were determined. • Solubility of Fe and Cr and lattice parameter evolution in the ternary phases were determined.

  10. La variante Oliana-Peramola (Alt Urgell – Cataluña) de la carretera C-14: un ejemplo de diseño de un auténtico eje estructurador del espacio local y vertebrador del territorio

    OpenAIRE

    2010-01-01

    La carretera C-14 une Lleida con la Seu d’Urgell siguiendo el valle del rio Segre y canaliza una buena parte del tráfico con origen y destino en el principado de Andorra. Desde hace años esta carretera es objeto de obras de mejora que tienen como objetivo reducir la sinuosidad de su trazado y evitar la circulación por el centro de núcleos urbanos. El territorio ocupado por Oliana y Peramola ha sido objeto de numerosas agresiones en los últimos cincuenta años, como consecuencia de la constr...

  11. Phases and Phase Transitions

    Science.gov (United States)

    Gitterman, Moshe

    2014-09-01

    In discussing phase transitions, the first thing that we have to do is to define a phase. This is a concept from thermodynamics and statistical mechanics, where a phase is defined as a homogeneous system. As a simple example, let us consider instant coffee. This consists of coffee powder dissolved in water, and after stirring it we have a homogeneous mixture, i.e., a single phase. If we add to a cup of coffee a spoonful of sugar and stir it well, we still have a single phase -- sweet coffee. However, if we add ten spoonfuls of sugar, then the contents of the cup will no longer be homogeneous, but rather a mixture of two homogeneous systems or phases, sweet liquid coffee on top and coffee-flavored wet sugar at the bottom...

  12. 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.

  13. Phase relations and hydrogenation behavior of (La1-xMgx)3Al alloys

    Institute of Scientific and Technical Information of China (English)

    LIU Yujie; ZHANG Qing'an

    2007-01-01

    The crystal structures and hydrogenation behavior of (La1-xMgx)3Al (x = 0.1, 0.2, 0.3, and 0.4) alloys were investigated.It was found that the alloys with x = 0.1 and 0.2 consist of La(Mg,Al),La,and a novel phase. The novel phase was determined as La2Al.It is shown that the amount of La2Al decreases as the Mg content increases. When x increases to 0.3,only La(Mg,Al) and a small amount of La2Al exist.When x is 0.4, La2Al phase disappears and the alloy contains both La(Mg,Al) and La(Al,Mg)2 Laves phase.The (La0.9Mg0.1)3Al and (La0.7Mg0.3)3Al alloys can be decomposed into LaH3,MgH2,and La2Al5 by the absorption of hydrogen at 473 K.

  14. The HVEE C-14 system at Groningen

    NARCIS (Netherlands)

    Gottdang, Andreas; Mous, Dirk J.W.; Plicht, Johannes van der

    1995-01-01

    Since May 1994, a new-generation accelerator mass spectrometer (AMS) has been fully operational at the Centre for Isotope Research in Groningen, The Netherlands, The fully automated and high-throughput accelerator mass spectrometry (AMS) system, manufactured by High Voltage Engineering Europa (HVEE)

  15. C14H19RuSe

    Science.gov (United States)

    Mikhova, B. M.

    This document is part of Subvolume D5 `Chemical Shifts and Coupling Constants for Carbon-13. Part 5: Organometallic Compounds' of Volume 35 `Nuclear Magnetic Resonance Data' of Landolt-Börnstein Group III: `Condensed Matter'.

  16. 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.

  17. Enhancement of cerium and hydrogen storage property of a low-cost Ti-V based BCC alloy prepared by commercial ferrovanadium

    Institute of Scientific and Technical Information of China (English)

    米菁; 吕芳; 刘晓鹏; 蒋利军; 李志念; 王树茂

    2010-01-01

    Based on the analysis of XRD, SEM, P-C-isotherm measurements and absorption kinetics simulation, it was indicated that Ce addition was an effective way to inhibit the formation of C14 Laves phase, improve flatness of the plateau, increase hydrogen diffusion rate and enlarge hydrogen storage capacity. The hydrogenation capacity of Ti27.25Cr28.05V37.25Fe7.45Ce1.0 alloy prepared by commercial ferrovanadium was 3.56 wt.% measured at 298 K. The dehydrogenation capacity was 2.25 wt.% and 2.54 wt.% measured at 343...

  18. Fe-15Ni-13Cr austenitic stainless steels for fission and fusion reactor applications - Part II: Effects of minor elements on precipitate phase stability during thermal aging

    Science.gov (United States)

    Lee, E. H.; Mansur, L. K.

    2000-01-01

    The precipitate phase stability in Fe-15Ni-13Cr base austenitic alloys was investigated as a function of minor alloying additions after thermally aging at 600°C and 675°C for times ranging from 24 h to one year. Seven major precipitate phases were found in aged specimens, including M 23C 6, Laves, Eta (η), TiO, NbC, MC, and M 2P. The types and amounts of precipitate phases varied with alloying element additions, aging temperature, and aging time. By analyzing the composition of each individual particle, it was possible to determine the essential constituent elements for each phase. From this information, a strategy to promote or suppress certain precipitate phases was developed. Among the seven phases, the most desirable precipitate phases were considered to be MC and M 2P, because these particles form on a fine scale with a high number density and, therefore, can serve as effective gas atom trap sites under irradiation.

  19. Effect of Deleterious Phases on Corrosion Resistance of Duplex Stainless Steel (2205

    Directory of Open Access Journals (Sweden)

    AbdulKadar M. Godil

    2013-07-01

    Full Text Available Duplex stainless steel is a Ferritic(BCC-Austenitic(FCC steel, covers the advantages of both Austenitic and Ferritic Stainless steels. They having good mechanical and corrosion resistance properties are widely used in many industries like chemical plants, refineries for critical equipments such as pressure vessels, heatexchangers, water heaters. Major problem occurs with duplex steels when they are worked or heated above about temperature of 280°C. Detrimental phases like Sigma, Chi, Laves and Alpha prime form when the Duplex steels are treated above this temperature and they retard the properties of Duplex stainless steels. They also cause embrittlement above temperature of 475°C called “475°C embrittlement”. During welding of duplex steels, Secondary austenite also forms, which is also one of the harmful phases in duplex steels. Among all of these phases, Sigma (σ is extremely harmful to the corrosion resistance of steel. Due to these limitations duplexgrades are not used above certain temperature ranges. In this experimental work a plate of duplex grade 2205 in hot worked condition was procured from TCR Advanced Engineering Pvt. Ltd., GIDC, Vadodara. Initially chemical composition of the plate was checked with emission spectrometer, tensile test and hardness tests werecarried out for comparing with the standard data. As there was no Sigma phase detected when tested with ASTM 930 in the received sample, Sigma phase was intentionally produced by giving heat treatment in the range of 700-850°C. Sigma phases were quantified with ASTM 930 practice A, by electrolytic etching with 40% NaOH. The effect of Sigma phase on corrosion resistance was measured by ASTM G48. The pitting corrosion resistance was evaluated in terms of average pit depth and overall corrosion rate.

  20. Moon Phases

    Science.gov (United States)

    Riddle, Bob

    2010-01-01

    When teaching Moon phases, the focus seems to be on the sequence of Moon phases and, in some grade levels, how Moon phases occur. Either focus can sometimes be a challenge, especially without the use of models and observations of the Moon. In this month's column, the author describes some of the lessons that he uses to teach the phases of the Moon…

  1. 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.

  2. Spatial and temporal variability in air concentrations of short-chain (C10-C13) and medium-chain (C14-C17) chlorinated n-alkanes measured in the U.K. atmosphere.

    Science.gov (United States)

    Barber, Jonathan L; Sweetman, Andy J; Thomas, Gareth O; Braekevelt, Eric; Stern, Gary A; Jones, Kevin C

    2005-06-15

    Two studies were carried out on short-chain (C10-C13) and medium-chain (C14-C17) polychlorinated n-alkanes (sPCAs and mPCAs) in U.K. air samples. The first study entailed taking 20 24-h air samples with a pair of Hi-Vol air samplers at the Hazelrigg field station, near Lancaster University. These samples were carefully selected to coincide with times when air masses were predicted to have a fairly constant back trajectory for 24 h and to give a broad spectrum of different origins. The second study was a spatial survey of PCAs in the air at 20 outdoor sites in northern England and four indoor locations in Lancaster, using polyurethane foam (PUF) disk passive air samplers. Levels of the sPCAs in the Hi-Vol samples ranged from <185 to 3430 pg m(-3) (average 1130 pg m(-3)) and were higher than those previously measured at this site in 1997. Levels of the mPCAs ranged from <811 to 14500 pg m(-3) (average 3040 pg m(-3)); that is, they were higher than sPCAs. Both sPCA and mPCA air concentrations are of the same order of magnitude as PAH at this site. Back trajectory analysis showed that the history of the air mass in the 48 h prior to sampling had an important effect on the concentrations observed, with overland samples having higher levels than oceanic, implying that the U.K. is probably responsible for most of the PCAs measured in the U.K. atmosphere. Amounts of both sPCAs and mPCAs in the passive air samples followed a rural-urban gradient. PCAs appear to be released from multiple sources around the country, as a result of the diffusive, open industrial and construction use of the technical mixtures.

  3. 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.

  4. Using C-14 and C-14 - Be-10 for Terrestrial Ages of Desert Meteorites

    Science.gov (United States)

    Jull, A. J. T.; Bland, P. A.; Klandrud, S. E.; McHargue, L. R.; Bevan, A. W. R.; Kring, D. A.; Wlotzka, F.

    2000-01-01

    The arid regions of the world appear to be great storage locations for meteorites, where they can survive for long periods of time in such environments. Large numbers of meteorites have been recovered from diverse areas of and and semi-arid regions of North Africa, Arabia, North America and Western Australia. The cold desert of Antarctica is a further storehouse of meteorites. One of the first recognized areas for collections of meteorites was Roosevelt County, New Mexico. The Nullarbor region of Australia and the northern Sahara Desert in Africa are also prolific sources of meteorites.

  5. Quantitative phase analysis from powder diffraction using de Rietveld method in hydrogen storage alloys based on TiCr

    Science.gov (United States)

    Martinez, A.; Bellon, D.; Reina, L.

    2016-08-01

    Hydrogen storage is one of the important steps in the implementation of the hydrogen economy; metal hydrides are a promising way to achieve this goal. We present in this work the use of Rietveld analysis to characterize structurally TiCr-based alloys that are able to store hydrogen. TiCruV09, TiCrL1V0.45Nb0.45, TiCr1.1V0.2 Nb0.8, TiCr1.1Nb0.9 alloys were synthesized in an arc furnace under argon atmosphere. The analysis of phases was developed by X-Ray Diffraction (XRD) for further refinement of both the two lattice parameters and the percentage of the phases. Our results confirmed that a structure bcc, mostly combined with a small percentage of Laves phases, leads to obtain important properties in this area. Rietveld analysis was performed by the Fullprof program and this program allows us to obtain the different structural parameters.

  6. 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.

  7. 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....

  8. Improvement of hydrogen sorption properties of compounds based on Vanadium “bcc” alloys by mean of intergranular phase development

    Energy Technology Data Exchange (ETDEWEB)

    Planté, D., E-mail: damien.plante@grenoble.cnrs.fr [Institut Néel CNRS et Université Joseph Fourier, BP 166, 38042 Grenoble Cedex 9 (France); Raufast, C.; Miraglia, S. [Institut Néel CNRS et Université Joseph Fourier, BP 166, 38042 Grenoble Cedex 9 (France); Rango, P. de [Institut Néel CNRS et Université Joseph Fourier, BP 166, 38042 Grenoble Cedex 9 (France); CRETA, CNRS, BP166, 38042 Grenoble Cedex 9 (France); Fruchart, D. [Institut Néel CNRS et Université Joseph Fourier, BP 166, 38042 Grenoble Cedex 9 (France)

    2013-12-15

    Highlights: •Decrease of “bcc” pseudo cell with the increase of amount of additive. •Additive phase improve activation kinetics. •Chromium in the “bcc” matrix decreases the lattice parameter and destabilizes hydride formation/dissociation. •Lower working temperatures could be obtain. -- Abstract: Body centered cubic structure (“bcc”) type alloys based on Vanadium [1] reveal promising characteristics for mobile applications. These disordered solid solutions have particular metal/hydride equilibrium and some regulation aspects have leaded us to pay special attention to this type of material [2]. Compounds based on Vanadium-rich solid solution have been elaborated in order to destabilize γ hydride phase (corresponding to the face centered cubic (“fcc”) structure of VH{sub 2}). Addition of Ni and Zr-rich Laves phase as a secondary phase results in the development of a particular microstructure composed of a principal “bcc” matrix rounded by intergranular activating phase. This results in a facilitated and faster activation of these compounds. The present study shows that some constituting species of the secondary phase have diffused in the main matrix and therefore have modified the thermodynamic of hydride. In fact, chromium diffusion into the “bcc” matrix destabilizes hydride. It is correlated to the lower stability of chromium hydride compared to Vanadium hydride. The enthalpic terms of each sample have been measured (assuming standard entropy of 130 J mol{sup −1} K{sup −1}). The equilibrium metal/hydride can be easily switched in order to adapt it to a mobile hydride tank and obtain low working temperature in regard to the potential use.

  9. Phase transitions

    CERN Document Server

    Solé, Ricard V

    2011-01-01

    Phase transitions--changes between different states of organization in a complex system--have long helped to explain physics concepts, such as why water freezes into a solid or boils to become a gas. How might phase transitions shed light on important problems in biological and ecological complex systems? Exploring the origins and implications of sudden changes in nature and society, Phase Transitions examines different dynamical behaviors in a broad range of complex systems. Using a compelling set of examples, from gene networks and ant colonies to human language and the degradation o

  10. EXAFS and XRD investigation of crystal structure in Cr doped YMn 2 deuterides

    Science.gov (United States)

    Klepka, M. T.; Wolska, A.; Lawniczak-Jablonska, K.; Filipek, S. M.; Sato, R.; Paul-Boncour, V.; Marchuk, I.

    2011-10-01

    Among the number of novel hydrides synthesized recently under high hydrogen pressure from various Laves phases, very specific ones are RMn 2H 6 (where R=Y, Er, Ho, Dy and Gd) with space group Fm-3m. These hydrides (or deuterides) can be formed independently on the initial structure (C14 or C15) of their parent RMn 2 compounds. Surprisingly, in contrast to hydrides/deuterides derived so far from the Laves phases, RMn 2H 6 compounds are not interstitial but are complex compounds. In order to understand better the role played by Mn in formation of the specific RMn 2D 6 deuterides we tested the possibility of manganese substitution by chromium, the element preceding Mn in the 3d series. Two YMn 2- XCr X alloys (where X=0.1 and 0.2) were submitted to treatment at 100 °C and high deuterium pressure. For X=0.1 the majority (88%) phase was Fm-3m space group whereas for X=0.2 the dominant (around 78%) was deuteride with expanded C15 Laves phase lattice (Fd-3m) like for YMn 2 and the second phase (only 22%) was the Fm-3m. This means that substitution of Mn with chromium by amount higher than X=0.1 makes the formation of Fm-3m single phase increasingly difficult. It was also confirmed that Cr preferably locates in 4a positions of the Fm-3m structure of YMn 2D 6, which might be responsible for its destabilization.

  11. EXAFS and XRD investigation of crystal structure in Cr doped YMn{sub 2} deuterides

    Energy Technology Data Exchange (ETDEWEB)

    Klepka, M.T., E-mail: Marcin.Klepka@ifpan.edu.pl [Institute of Physics, PAS, al. Lotnikow 32/46, PL-02668 Warsaw (Poland); Wolska, A.; Lawniczak-Jablonska, K. [Institute of Physics, PAS, al. Lotnikow 32/46, PL-02668 Warsaw (Poland); Filipek, S.M.; Sato, R. [Institute of Physical Chemistry, PAS, ul. Kasprzaka 44/52, PL-01224 Warsaw (Poland); Paul-Boncour, V. [Laboratoire de Chimie Metallurgique des Terres Rares, CNRS, 2-8 rue H. Dunant, 94320 Thiais (France); Marchuk, I. [Department of Physics and Colloid Chemistry, Ivan Franko National University of Lviv, Kyryla and Mefodia Street 6, 79005 Lviv (Ukraine)

    2011-10-15

    Among the number of novel hydrides synthesized recently under high hydrogen pressure from various Laves phases, very specific ones are RMn{sub 2}H{sub 6} (where R=Y, Er, Ho, Dy and Gd) with space group Fm-3m. These hydrides (or deuterides) can be formed independently on the initial structure (C14 or C15) of their parent RMn{sub 2} compounds. Surprisingly, in contrast to hydrides/deuterides derived so far from the Laves phases, RMn{sub 2}H{sub 6} compounds are not interstitial but are complex compounds. In order to understand better the role played by Mn in formation of the specific RMn{sub 2}D{sub 6} deuterides we tested the possibility of manganese substitution by chromium, the element preceding Mn in the 3d series. Two YMn{sub 2-X}Cr{sub X} alloys (where X=0.1 and 0.2) were submitted to treatment at 100 deg. C and high deuterium pressure. For X=0.1 the majority (88%) phase was Fm-3m space group whereas for X=0.2 the dominant (around 78%) was deuteride with expanded C15 Laves phase lattice (Fd-3m) like for YMn{sub 2} and the second phase (only 22%) was the Fm-3m. This means that substitution of Mn with chromium by amount higher than X=0.1 makes the formation of Fm-3m single phase increasingly difficult. It was also confirmed that Cr preferably locates in 4a positions of the Fm-3m structure of YMn{sub 2}D{sub 6}, which might be responsible for its destabilization.

  12. The solid-liquid phase diagrams of binary mixtures of consecutive, even saturated fatty acids.

    Science.gov (United States)

    Costa, Mariana C; Sardo, Mariana; Rolemberg, Marlus P; Coutinho, João A P; Meirelles, Antonio J A; Ribeiro-Claro, Paulo; Krähenbühl, M A

    2009-08-01

    For the first time, the solid-liquid phase diagrams of five binary mixtures of saturated fatty acids are here presented. These mixtures are formed of caprylic acid (C(8:0))+capric acid (C(10:0)), capric acid (C(10:0))+lauric acid (C(12:0)), lauric acid (C(12:0))+myristic acid (C(14:0)), myristic acid (C(14:0))+palmitic acid (C(16:0)) and palmitic acid (C(16:0))+stearic acid (C(18:0)). The information used in these phase diagrams was obtained by differential scanning calorimetry (DSC), X-ray diffraction (XRD), FT-Raman spectrometry and polarized light microscopy, aiming at a complete understanding of the phase diagrams of the fatty acid mixtures. All of the phase diagrams reported here presented the same global behavior and it was shown that this was far more complex than previously imagined. They presented not only peritectic and eutectic reactions, but also metatectic reactions, due to solid-solid phase transitions common in fatty acids and regions of solid solution not previously reported. This work contributes to the elucidation of the phase behavior of these important biochemical molecules, with implications in various industrial applications.

  13. Measuring Laves Phase Particle Size and Thermodynamic Calculating Its Growth and Coarsening Behavior in P92 Steels%P92钢中拉弗斯相的尺寸测量及其长大规律的动力学模拟计算

    Institute of Scientific and Technical Information of China (English)

    姚兵印; 周荣灿; 范长信; 李太江; John Hald

    2010-01-01

    拉弗斯相(Laves相)是超超临界机组用新型耐热钢--P92钢的重要析出相之一,对其在扫描电镜下的尺寸测量方法进行介绍,并采用热力学软件计算分析其长大规律.在扫描电镜下形成的背散射图像的原子序数差及二次电子像能够清晰地辨别出Laves相和碳化物(M23C6),这是Laves相测量方法的基础.通过与透射电镜对比,表明扫描电镜是分析Laves相的优先使用的方法.测量了3种P92钢中Laves相颗粒尺寸,研究表明Laves相颗粒尺寸越小,数量越多,材料的抗蠕变性能越好,相同条件下蠕变断裂时间越长.采用热力学计算程序DICTRA进行数值模拟,结果表明,所采用的Laves相长大模型能够很好地模拟Laves相的长大规律,但长时间(650℃、20000h和600℃、50000h)后应采用奥斯特瓦尔德长大规律(Ostwald ripening)来分析Laves相.

  14. 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.

  15. 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.

  16. Near zero magnetostriction of Fe-Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bormio-Nunes, C; Belarmino, A R; Santos, C T; Ugeda, V C; Baldan, C A [Escola de Engenharia de Materiais, Universidade de Sao Paulo, CP 116, 12.602-810 - Lorena, Sao Paulo (Brazil); Ghivelder, L [Instituto de Fisica, Universidade Federal do Rio de Janeiro, CP 68528, 21.941-972, Rio de Janeiro, RJ (Brazil)

    2009-08-21

    Fe{sub 100-x}Ti{sub x} alloys (x = 10, 15, 20) were studied with respect to their microstructure and magnetostriction. Depending on heat treatment temperature and composition, the sample retained either the {alpha}-phase (A2 structure) or the {alpha}-phase plus the TiFe{sub 2} Laves phase (C14 structure). The saturation magnetostriction measured at 238 K is negative, about -11 ppm. However, for fields up to 0.4 T the magnetostriction is barely zero, a very interesting result. High values of magnetostriction are of interest for applications mainly in sensors and actuators, but zero magnetostriction is also a remarkable property, desirable for many applications such as electric transformers and fluxgate sensor cores. Therefore, the Fe{sub 100-x}Ti{sub x} (x < 20 at%) are an attractive option to be considered for these applications.

  17. Electrochemical properties of TiV-based hydrogen storage alloys

    Institute of Scientific and Technical Information of China (English)

    朱云峰; 李锐; 高明霞; 刘永锋; 潘洪革; 王启东

    2003-01-01

    The electrochemical properties of the super-stoichiometric TiV-based hydrogen storage electrode alloys(Ti0.8Zr0.2)(V0.533Mn0.107Cr0.16Ni0.2)x(x=2, 3, 4, 5, 6) were studied. It is found by XRD analysis that all the al-loys mainly consist of a C14 Laves phase with hexagonal structure and a V-based solid solution phase with BCCstructure. The lattice parameters and the unit cell volumes of the two phases decrease with increasing x. The cyclelife, the linear polarization, the anode polarization and the electrochemical impedance spectra of the alloy electrodeswere investigated systematically. The overall electrochemical properties of the alloy electrode are found improvedgreatly as the result of super-stoichiometry and get to the best when x= 5.

  18. The solid-liquid phase diagrams of binary mixtures of consecutive, even saturated fatty acids: differing by four carbon atoms.

    Science.gov (United States)

    Costa, Mariana C; Sardo, Mariana; Rolemberg, Marlus P; Ribeiro-Claro, Paulo; Meirelles, Antonio J A; Coutinho, João A P; Krähenbühl, M A

    2009-01-01

    The complete solid-liquid phase diagrams for four binary mixtures of saturated fatty acids are presented, for the first time, in this work. These mixtures are formed by caprylic acid (C(8:0))+lauric acid (C(12:0)), capric acid (C(10:0))+myristic acid (C(14:0)), lauric acid (C(12:0))+palmitic acid (C(16:0)) and myristic acid (C(14:0))+stearic acid (C(18:0)). The phase diagrams were obtained by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). FT-Raman spectrometry and polarized light microscopy were used to complement the characterization for a complete understanding of the phase diagram. All of the phase diagrams here reported show the same global behavior that is far more complex than previously accepted. They present not only peritectic and eutectic reactions, but also metatectic reactions, due to solid-solid phase transitions common in fatty acids, and regions of solid solution not previously reported. This work contributes to the elucidation of the phase behavior of these important biochemical molecules with implications in various industrial applications.

  19. Phase Structural Characteristics of ZrV2 Thin Film Prepared by Magnetron Sputtering

    Institute of Scientific and Technical Information of China (English)

    XU Shi-Lin; SHI Li-Qun

    2005-01-01

    @@ The thin film metal hydride has become an emerging field of research in metal hydride batteries for its good mechanical and hydrogenation properties. ZrV2 thin films have been prepared using a dc magnetron sputtering method, and the phase structure is investigated. Only amorphous or crystalline Zr and V mixture phases are achieved when substrates are heated during either to 400℃ or to 550 ℃. The annealing causes segregation of Zr and V in the film induced by strain-driven diffusion and interdiffusion between substrate Mo and film elements at high temperature, which results in the formation of mixture phases of C14, C15, Zr and V, but the content of C15 phase is not higher compared with that in the bulk material.

  20. Experimental investigation of the U–Zr–Al ternary phase diagram: Isothermal sections at 673 K and 1073 K

    Energy Technology Data Exchange (ETDEWEB)

    Moussa, C.; Désévédavy, F.; Noël, H.; Pasturel, M.; Gouttefangeas, F. [ISCR/CSM, Université de Rennes1, UMR-CNRS 6226, Campus de Beaulieu, 263 Avenue du Général Leclerc, 35042 Rennes Cedex, France, (France); Dubois, S. [CEA/DEN/DEC, Cadarache, 13108 St. Paul Lez Durance (France); Stepnik, B. [AREVA/CERCA, 10 Rue Juliette Récamier, 69006 Lyon (France); Tougait, O., E-mail: tougait@univ-rennes1.fr [ISCR/CSM, Université de Rennes1, UMR-CNRS 6226, Campus de Beaulieu, 263 Avenue du Général Leclerc, 35042 Rennes Cedex, France, (France); UCCS, UMR 8181 CNRS, Université Lille 1, ENSCL, Avenue Mendeleiev, 59655 Villeneuve d’Ascq Cedex (France)

    2015-06-15

    Highlights: • Isothermal sections of the U–Zr–Al system were investigated for 673 K and 1073 K. • The crystallographic properties of the equilibrium phases were checked. • The ternary extension of both unary and binary phases was determined. • The solubility of Al into UZr{sub 2} (δ-phase) was assessed by diffusion couples. • The microstructure of quenched alloys is discussed. - Abstract: Isothermal sections at 673 K and 1073 K of the ternary U–Zr–Al system were established in the whole concentration range, by means of powder X-ray diffraction, scanning electron microscopy–energy dispersive X-ray spectroscopy and differential thermal analysis. All measured compositions and unit-cell refinements were performed at room temperature from quenched samples annealed at 1073 K and 673 K for four and eight weeks respectively. For both temperatures, the Al-rich corner of the phase diagram is characterized by extended homogeneity ranges due to mutual exchange between U and Zr in UAl{sub 3} (cubic, AuCu{sub 3}-type) and in the Laves phase UAl{sub 2} (cubic, MgCu{sub 2}-type). Minute U solubility in ZrAl{sub 2} (hexagonal, MgZn{sub 2}-type) and in Zr{sub 2}Al (hexagonal, Ni{sub 2}In-type) was evaluated to be of the order of 1 at.% U. For the other binary compounds, the solubility of the third component was found negligible. At 1073 K, the solid solution based on γU (cubic, W-type) which covers the U–Zr binary axis up to 95.5 at.% Zr, allows also some limited solubility of Al [maximum of 5 at.%]. For Al-content below 66 at.%, most of the phase relations comprise equilibria between the Zr–Al binaries and the γ(U,Zr,Al) solid solution. At 673 K, the U–Zr axis is found in agreement with the literature data and no Al solubility could be detected in αU, αZr and UZr{sub 2} (δ phase). The phase relations are mainly established between Zr–Al binaries and αU. For monolithic UMo fuel with a Zr diffusion barrier foil cladded with Al, the main interaction

  1. First-principles study of structure, initial lattice expansion, and pressure-composition-temperature hysteresis for substituted LaNi5 and TiMn2 alloys

    Science.gov (United States)

    Wong, D. F.; Young, K.; Ng, K. Y. S.

    2016-12-01

    The c/a unit-cell aspect ratios of CaCu5-structured AB5 and C14 Laves phase AB2 metal hydride alloy families are generally correlated to pressure-concentration-temperature hysteresis and degree of alloy pulverization. Structures of substituted LaNi4 X and C14 Ti4Mn7 X compositions and their hydrides in the α-phase were calculated by first principles using density functional theory to look at the c/a ratio and its relationship to initial lattice expansion. Lattice expansion with respect to the lattice parameters and lattice volume in the α-phase hydrides were analyzed, and a general trend in lattice expansion in the direction of higher resistance to elastic deformation was observed to correlate well to the trends in hysteresis measured in AB5 and C14 AB2 type alloys. Lattice expansion is noted to induce microstrains within the crystal lattice, and the anisotropy in the LaNi4 X and Ti4Mn7 X alloys played a role in determining the direction of higher resistance to deformation. Lattice expansions both measured and calculated have been linked to capacity degradation measurements as well as to hysteresis (a measure of irreversible energy losses due to lattice plastic deformation), which may be related to the dislocations and defects formed during hydrogenation.

  2. [Polymorphic markers of the CYP1B1 (4326C > G), CYP2F1 (c.14_15insC), CYP2J2 (-76G > T), and CYP2S1 (13106C > T and 13255A > G) genes and genetic predisposition to chronic respiratory diseases induced by smoking and occupational factors].

    Science.gov (United States)

    Akhmadishina, L A; Korytina, G F; Victorova, T V

    2011-10-01

    The contribution of the polymorphic markers of cytochrome P450 genes to respiratory diseases caused by smoking and occupational factors has been assessed. For this purpose, PCR-RFLP analysis of the CYP1B1 (rs1056836, 4326C > G), CYP2F1 (rs11399890, c.14_15insC), CYP2J2 (rs890293, -76G > T), and CYP2S1 (rs34971233, 13106C > T and rs338583, 13255A > G) gene polymorphisms has been performed. The analysis has shown that the polymorphic variants of the CYP1B1 (rs1056836, 4326C > G) and CYP2F1 (rs11399890, c. 14_15insC) genes may contribute to the development of occupational chronic bronchitis. The proportion of CYP1B1* 1*3 heterozygotes in the group of patients with occupational chronic bronchitis is considerably greater than in the group of healthy workers (69.16% versus 53.29%; chi2 = 5.94, P = 0.02, P(cor) = 0.04, OR = 1.97, the 95% CI is 1.13-3.42). Patients with occupational chronic bronchitis and healthy workers significantly differed from each other in the frequency distribution of the genotypes ofthe CYP2F1 (rs11399890, c.14_15insC) polymorphic marker (chi2 = 6.18, d.f = 2, P = 0.05). The frequency of the wild type/ins heterozygous genotype for the CYP2F1 gene is higher in healthy workers (36.08%) than in patients (22.22%) (chi2 = 5.48, P = 0.02, P(cor) = 0.04, OR = 0.51, the 95% CI is 0.28-0.90). No association has been found between the CYP2J2 (rs890293, -76G > T) or CYP2S1 (rs34971233, 13106C > T, P466L and rs338583, 13255A > G) gene polymorphisms and respiratory diseases.

  3. Permanent magnetism of intermetallic compounds between light and heavy transition-metal elements.

    Science.gov (United States)

    Kumar, P; Kashyap, A; Balamurugan, B; Shield, J E; Sellmyer, D J; Skomski, R

    2014-02-12

    First-principle calculations are used to investigate the intrinsic magnetic properties of intermetallic alloys of the type XMn, where X is a 4d or 5d element and M is Fe or Co. Emphasis is on the hexagonal C14 Laves-phase 1:2 and 1:5 alloys, the latter crystallizing in the CaCu5 structure. These series are of interest in permanent magnetism from fundamental and practical viewpoints, respectively. In the former, the unit cells form a prototypical motif where a heavy atom with high spin-orbit coupling and magnetocrystalline anisotropy is surrounded by many somewhat smaller M atoms with high magnetization, and the latter are Laves-phase derivatives of renewed interest in permanent magnetism. Our DFT calculations predict magnetic moments, magnetizations and anisotropies, as well as formation energies. The results are analyzed across the 4d and 5d series, especially with respect to hybridization effects between 3d and 4d/5d bands.

  4. Electron microscopy study of direct laser deposited IN718

    Energy Technology Data Exchange (ETDEWEB)

    Ding, R.G., E-mail: r.ding@bham.ac.uk [School of Metallurgy and Materials, The University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Huang, Z.W.; Li, H.Y. [School of Metallurgy and Materials, The University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Mitchell, I.; Baxter, G. [Rolls-Royce plc., Derby DE24 8BJ (United Kingdom); Bowen, P. [School of Metallurgy and Materials, The University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2015-08-15

    The microstructure of direct laser deposited (DLD) IN718 has been investigated in detail using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results confirm that the dendrite core microstructure can be linked to the cooling rate experienced during the deposition. A ~ 100 μm wide δ partially dissolved region in the IN718 substrate was observed close to the substrate/deposit boundary. In the deposited IN718, γ/Laves eutectic constituent is the predominant minor microconstituent. Irregular and regular (small) (Nb,Ti)C carbides and a mixture of the carbides and Laves were observed. Most M{sub 3}B{sub 2} borides were nucleated around a (Nb,Ti)C carbide. Needles of δ phase precipitated from the Laves phase were also observed. A complex constituent (of Laves, δ, α-Cr, γ″, and γ matrix) is reported in IN718 for the first time. The formation of α-Cr particles could be related to Cr rejection during the formation and growth of Cr-depleted δ phase. - Highlights: • Secondary phases in IN718 deposits were identified using electron diffraction and EDS. • MC, M{sub 3}B{sub 2}, γ/Laves eutectic and γ/NbC/Laves eutectic were observed. • Needle-like δ phases were precipitated from the Laves phase. • A complex constituent (Laves, δ, α-Cr, γ″ and γ) was reported for the first time.

  5. Mixed phases during the phase transitions

    CERN Document Server

    Tatsumi, Toshitaka; Maruyama, Toshiki

    2011-01-01

    Quest for a new form of matter inside compact stars compels us to examine the thermodynamical properties of the phase transitions. We closely consider the first-order phase transitions and the phase equilibrium on the basis of the Gibbs conditions, taking the liquid-gas phase transition in asymmetric nuclear matter as an example. Characteristic features of the mixed phase are figured out by solving the coupled equations for mean-fields and densities of constituent particles self-consistently within the Thomas-Fermi approximation. The mixed phase is inhomogeneous matter composed of two phases in equilibrium; it takes a crystalline structure with a unit of various geometrical shapes, inside of which one phase with a characteristic shape, called "pasta", is embedded in another phase by some volume fraction. This framework enables us to properly take into account the Coulomb interaction and the interface energy, and thereby sometimes we see the mechanical instability of the geometric structures of the mixed phase...

  6. 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 Tu

  7. Phases in the Al-Yb-Zn system between 25 and 50 at% ytterbium

    Science.gov (United States)

    Mazzone, Donata; Manfrinetti, Pietro; Fornasini, Maria L.

    2009-09-01

    Phases YbZn 1-xAl x, YbZn 2-xAl x and YbZn 3-xAl x were studied by electron microprobe analysis and X-ray single crystal and powder methods. The compound YbZn 0.8Al 0.2 crystallizes with the CsCl-type, a=3.635(2) Å. Four phases were investigated by single crystal X-ray diffraction: YbZn 0.996(6)Al 1.004(6), MgNi 2-type, P6 3/ mmc, a=5.573(1), c=18.051(3) Å, Z=8, w R2=0.040 and YbZn 0.88(3)Al 1.12(3), MgCu 2-type, Fd3¯m, a=7.860(2) Å, Z=8, w R2=0.060, both showing mixed Zn/Al occupancy; YbZn 2.50(1)Al 0.50(1), CeNi 3-type, P6 3/ mmc, a=5.496(1), c=17.336(2) Å, Z=6, w R2=0.036 and YbZn 1.92(2)Al 1.08(2), PuNi 3- or NbBe 3-type, R3¯m, a=5.499(1), c=26.134(5) Å, Z=9, w R2=0.053, where the zinc atoms are ordered in the CaCu 5 segment, while share the sites with aluminium in the Laves phase segment. In the pseudobinary section YbZn 2-xAl x four structures occur in sequence with increasing the electron concentration: CeCu 2 or KHg 2 ( x=0-0.3), MgZn 2 ( x=0.33-0.54), MgNi 2 ( x=0.68-1.01) and MgCu 2 ( x=1.12-2). This sequence agrees with the results of first-principles calculations, already reported in the literature for other similar series. In the YbZn 3-xAl x section CeNi 3-type compounds occur with x=0.40-0.88 followed by PuNi 3-type compounds with x=0.92-1.10. The stability ranges of these phases are related to the valence electron concentration.

  8. 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....

  9. Neutron scattering of modulated magnetic order at the border of ferromagnetism in NbFe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Niklowitz, Philipp G.; Poulten, James; Duncan, William [Dept of Physics, Royal Holloway, University of London, Egham (United Kingdom); Hirschberger, Max [Dept of Physics, Princeton University, Princeton (United States); Neubauer, Andreas; Pfleiderer, Christian [Fakultaet fuer Physik, TU Muenchen, Garching (Germany); Cermak, Petr; Schneidewind, Astrid [JCNS at MLZ, Forschungszentrum Juelich GmbH, Garching (Germany); Seemann, Klaus; Faulhaber, Enrico [MLZ, TU Muenchen, Garching (Germany); Grosche, F. Malte [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom)

    2015-07-01

    The border of ferromagnetism in the C14 Laves phase NbFe{sub 2} is characterised by non-Fermi liquid properties consistent with ferromagnetic quantum criticality, but the ferromagnetic quantum critical point appears to be masked by modulated magnetic order (MMO). With our elastic neutron scattering studies of three single-crystalline Nb{sub 1-y}Fe{sub 2+y} samples ranging from Fe-rich composition to a nearly stoichiometric sample we have directly determined the ordering wave vector q{sub 1} of MMO. A weak T and H and considerable y dependence of q{sub 1} is observed. Our inelastic neutron data is dominated by strong quasielastic scattering in the vicinity of (002) and contains further features near q{sub 1}. The results indicate that NbFe{sub 2} could display the theoretically predicted scenario of a ferromagnetic quantum critical point, which is masked by emerging modulated magnetic order.

  10. Band structure and itinerant magnetism in quantum critical NbFe2

    Energy Technology Data Exchange (ETDEWEB)

    Subedi, A. P. [University of Tennessee, Knoxville (UTK); Singh, David J [ORNL

    2010-01-01

    We report first-principles calculations of the band structure and magnetic ordering in the C14 Laves phase compound NbFe{sub 2}. The magnetism is itinerant in the sense that the moments are highly dependent on ordering. We find an overestimation of the magnetic tendency within the local spin-density approximation, similar to other metals near magnetic quantum critical points. We also find a competition between different magnetic states due to band-structure effects. These lead to competing magnetic tendencies due to competing interlayer interactions, one favoring a ferrimagnetic solution and the other an antiferromagnetic state. While the structure contains Kagome lattice sheets, which could, in principle, lead to strong magnetic frustration, the calculations do not show dominant nearest-neighbor antiferromagnetic interactions within these sheets. These results are discussed in relation to experimental observations.

  11. Ti–V–Mn based metal hydrides for hydrogen compression applications

    Energy Technology Data Exchange (ETDEWEB)

    Pickering, Lydia, E-mail: lydia.pickering@btinternet.com; Reed, Daniel; Bevan, Alexander I.; Book, David, E-mail: d.book@bham.ac.uk

    2015-10-05

    Highlights: • Ti–V–Mn based alloys were investigated as V was substituted for Nb, Cr, Mo and Ta. • The produced alloys were found to possess C14 Laves, BCC and FCC phases. • <0.2 Nb substituted for V led to small hysteresis and high dissociation pressures. • Ti{sub 0.5}–V{sub 0.45}–Nb{sub 0.05}–Mn is a suitable alloy to be used in a metal hydride compressor. - Abstract: Ti–V–Mn based alloys, consisting mainly of the hexagonal C14 Laves and BCC phases, with nominal compositions of Ti{sub 0.5}V{sub 0.4}TM{sub 0.1}Mn, where TM = Nb, Cr, Mo, Ta and Ti{sub 0.5}V{sub 0.5−x}Nb{sub x}Mn, where x = 0.05 and 0.2, were synthesised by arc melting. It was found that small amounts of Nb substituted for V (x = 0.05 and 0.1) resulted in smaller hysteresis between absorption and desorption as well as higher hydrogen dissociation pressures, compared to Ti{sub 0.5}V{sub 0.5}Mn. These findings show that Ti{sub 0.5}–V{sub 0.45}–Nb{sub 0.05}–Mn is a suitable alloy to be used in a metal hydride compressor to deliver a pressure of 650 bar in the temperature range 303–473 K.

  12. 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

  13. Phase Statistics of Soliton

    OpenAIRE

    Ho, Keang-Po

    2003-01-01

    The characteristic function of soliton phase jitter is found analytically when the soliton is perturbed by amplifier noise. In additional to that from amplitude jitter, the nonlinear phase noise due to frequency and timing jitter is also analyzed. Because the nonlinear phase noise is not Gaussian distributed, the overall phase jitter is also non-Gaussian. For a fixed mean nonlinear phase shift, the contribution of nonlinear phase noise from frequency and timing jitter decreases with distance ...

  14. Propagating phase interface with intermediate interfacial phase: Phase field approach

    Science.gov (United States)

    Momeni, Kasra; Levitas, Valery I.

    2014-05-01

    An advanced three-phase phase field approach (PFA) is suggested for a nonequilibrium phase interface that contains an intermediate phase, in particular, a solid-solid interface with a nanometer-sized intermediate melt (IM). A thermodynamic potential in the polar order parameters is developed that satisfies all thermodynamic equilibrium and stability conditions. The special form of the gradient energy allowed us to include the interaction of two solid-melt interfaces via an intermediate melt and obtain a well-posed problem and mesh-independent solutions. It is proved that for stationary 1D solutions to two Ginzburg-Landau equations for three phases, the local energy at each point is equal to the gradient energy. Simulations are performed for β ↔δ phase transformations (PTs) via IM in an HMX energetic material. The obtained energy IM width dependence is described by generalized force-balance models for short- and long-range interaction forces between interfaces but not far from the melting temperature. A force-balance model is developed that describes phase field results even 100 K below the melting temperature. The effects of the ratios of width and energies of solid-solid and solid-melt interfaces, temperature, and the parameter characterizing interaction of two solid-melt interfaces, on the structure, width, energy of the IM and interface velocity are determined by finite element method. Depending on parameters, the IM may appear by continuous or discontinuous barrierless disordering or via critical nucleus due to thermal fluctuations. The IM may appear during heating and persist during cooling at temperatures well below than it follows from sharp-interface approach. On the other hand, for some parameters when IM is expected, it does not form, producing an IM-free gap. The developed PFA represents a quite general three-phase model and can be extended to other physical phenomena, such as martensitic PTs, surface-induced premelting and PTs, premelting

  15. Characterization of rhamnolipids by liquid chromatography/mass spectrometry after solid-phase extraction.

    Science.gov (United States)

    Behrens, Beate; Engelen, Jeannine; Tiso, Till; Blank, Lars Mathias; Hayen, Heiko

    2016-04-01

    Rhamnolipids are surface-active agents with a broad application potential that are produced in complex mixtures by bacteria of the genus Pseudomonas. Analysis from fermentation broth is often characterized by laborious sample preparation and requires hyphenated analytical techniques like liquid chromatography coupled to mass spectrometry (LC-MS) to obtain detailed information about sample composition. In this study, an analytical procedure based on chromatographic method development and characterization of rhamnolipid sample material by LC-MS as well as a comparison of two sample preparation methods, i.e., liquid-liquid extraction and solid-phase extraction, is presented. Efficient separation was achieved under reversed-phase conditions using a mixed propylphenyl and octadecylsilyl-modified silica gel stationary phase. LC-MS/MS analysis of a supernatant from Pseudomonas putida strain KT2440 pVLT33_rhlABC grown on glucose as sole carbon source and purified by solid-phase extraction revealed a total of 20 congeners of di-rhamnolipids, mono-rhamnolipids, and their biosynthetic precursors 3-(3-hydroxyalkanoyloxy)alkanoic acids (HAAs) with different carbon chain lengths from C8 to C14, including three rhamnolipids with uncommon C9 and C11 fatty acid residues. LC-MS and the orcinol assay were used to evaluate the developed solid-phase extraction method in comparison with the established liquid-liquid extraction. Solid-phase extraction exhibited higher yields and reproducibility as well as lower experimental effort.

  16. 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

  17. 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...

  18. Engineering holographic phase diagrams

    Science.gov (United States)

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

    2016-10-01

    By introducing interacting scalar fields, we tried to engineer physically motivated holographic phase diagrams which may be interesting in the context of various known condensed matter systems. We introduce an additional scalar field in the bulk which provides a tunable parameter in the boundary theory. By exploiting the way the tuning parameter changes the effective masses of the bulk interacting scalar fields, desired phase diagrams can be engineered for the boundary order parameters dual to those scalar fields. We give a few examples of generating phase diagrams with phase boundaries which are strikingly similar to the known quantum phases at low temperature such as the superconducting phases. However, the important difference is that all the phases we have discussed are characterized by neutral order parameters. At the end, we discuss if there exists any emerging scaling symmetry associated with a quantum critical point hidden under the dome in this phase diagram.

  19. 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

  20. Metastable phases and "metastable" phase diagrams

    OpenAIRE

    Brazhkin, V. V.

    2006-01-01

    The work discusses specifics of phase transitions for metastable states of substances. The objects of condensed media physics are primarily equilibrium states of substances with metastable phases viewed as an exception, while the overwhelming majority of organic substances investigated in chemistry are metastable. It turns out that at normal pressure many of simple molecular compounds based on light elements (these include: most hydrocarbons; nitrogen oxides, hydrates, and carbides; carbon ox...

  1. Phase jitter in a differential phase experiment.

    Science.gov (United States)

    Tanenbaum, B. S.; Connolly, D. J.; Austin, G. L.

    1973-01-01

    Austin (1971) had concluded that, because of the 'phase jitter,' the differential phase experiment is useful over a more limited height range than the differential absorption experiment. Several observations are presented to show that this conclusion is premature. It is pointed out that the logical basis of the differential absorption experiment also requires that the O- and X-mode echoes, at a given time, come from the same irregularities. Austin's calculations are believed to contain a systematic error above 80 km.

  2. Perceptions about Moon Phases.

    Science.gov (United States)

    Rider, Steven

    2002-01-01

    Presents research on different techniques to determine the level of understanding among middle school students regarding the phases of the moon. Quotes student responses to provide some insight into students' level of understanding of general knowledge about the moon, moon phases, and modeling the phases. Presents implications for teachers. (KHR)

  3. 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...

  4. 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.

  5. 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.

  6. 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

  7. 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...... efficiency. Optimization can address practical issues, such as finding an optimal spatial filter for the chosen application, and can even enable a Reverse Phase Contrast mode where intensity patterns are converted into a phase modulation....

  8. Topological phase effects

    CERN Document Server

    Robbins, J M

    2010-01-01

    Quantum eigenstates undergoing cyclic changes acquire a phase factor of geometric origin. This phase, known as the Berry phase, or the geometric phase, has found applications in a wide range of disciplines throughout physics, including atomic and molecular physics, condensed matter physics, optics, and classical dynamics. In this article, the basic theory of the geometric phase is presented along with a number of representative applications. The article begins with an account of the geometric phase for cyclic adiabatic evolutions. An elementary derivation is given along with a worked example for two-state systems. The implications of time-reversal are explained, as is the fundamental connection between the geometric phase and energy level degeneracies. We also discuss methods of experimental observation. A brief account is given of geometric magnetism; this is a Lorenz-like force of geometric origin which appears in the dynamics of slow systems coupled to fast ones. A number of theoretical developments of the...

  9. Interacting Weyl fermions: Phases, phase transitions and global phase diagram

    CERN Document Server

    Roy, Bitan; Juricic, Vladimir

    2016-01-01

    We study the effects of short-range interactions on a generalized three-dimensional Weyl semimetal, where the band touching points act as the (anti)monopoles of Abelian Berry curvature of strength $n$. We show that any local interaction has a \\emph{negative} scaling dimension $-2/n$. Consequently all Weyl semimetals are stable against weak short-range interactions. For sufficiently strong interactions, we demonstrate that the Weyl semimetal either undergoes a first order transition into a band insulator or a continuous transition into a symmetry breaking phase. A translational symmetry breaking axion insulator and a rotational symmetry breaking semimetal are two prominent candidates for the broken symmetry phase. At one loop level, the correlation length exponent for continuous transitions is $\

  10. 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.

  11. 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).

  12. 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.

  13. 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

  14. Phase Equilibria Diagrams Database

    Science.gov (United States)

    SRD 31 NIST/ACerS Phase Equilibria Diagrams Database (PC database for purchase)   The Phase Equilibria Diagrams Database contains commentaries and more than 21,000 diagrams for non-organic systems, including those published in all 21 hard-copy volumes produced as part of the ACerS-NIST Phase Equilibria Diagrams Program (formerly titled Phase Diagrams for Ceramists): Volumes I through XIV (blue books); Annuals 91, 92, 93; High Tc Superconductors I & II; Zirconium & Zirconia Systems; and Electronic Ceramics I. Materials covered include oxides as well as non-oxide systems such as chalcogenides and pnictides, phosphates, salt systems, and mixed systems of these classes.

  15. Lunar Phases Planisphere

    Science.gov (United States)

    Shawl, Stephen J.

    2010-01-01

    This paper describes a lunar phases planisphere with which a user can answer questions about the rising and setting times of the Moon as well as questions about where the Moon will be at a given phase and time. The article contains figures that can be photocopied to make the planisphere. (Contains 2 figures.)

  16. LIGHT NONAQUEOUS PHASE LIQUIDS

    Science.gov (United States)

    Nonaqueous phase liquids (NAPLS) are hydrocarbons that exist as a separate, immiscible phase when in contact with water and/or air. ifferences in the physical and chemical properties of water and NAPL result in the formation of a physical interface between the liquids which preve...

  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. Phase Contrast Imaging

    DEFF Research Database (Denmark)

    1996-01-01

    with a simple one-to-one mapping between resolution elements of a spatial phase modulator and resolution elements of the generated intensity pattern is provided. According to the invention a method is provided for synthesizing an intensity pattern with low loss of electromagnetic energy, comprising spatial...... modulation of electromagnetic radiation with a spatial phase mask for modulation of the phase of the incident eletromagnetic radiation by phasor values of individual resolution elements of the spatial phase mask, each phasor value being determined in such a way that the values of the Fourier transformed......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...

  19. Quantum Enhanced Phase Retrieval

    CERN Document Server

    Liberman, Liat; Poem, Eilon; Silberberg, Yaron

    2015-01-01

    The retrieval of phases from intensity measurements is a key process in many fields in science, from optical microscopy to x-ray crystallography. Here we study phase retrieval of a one-dimensional multi-phase object that is illuminated by quantum states of light. We generalize the iterative Gerchberg-Saxton algorithm to photon correlation measurements on the output plane, rather than the standard intensity measurements. We report a numerical comparison of classical and quantum phase retrieval of a small one-dimensional object of discrete phases from its far-field diffraction. While the classical algorithm was ambiguous and often converged to wrong solutions, quantum light produced a unique reconstruction with smaller errors and faster convergence. We attribute these improvements to a larger Hilbert space that constrains the algorithm.

  20. 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.

  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. Atomic phase diagram

    Institute of Scientific and Technical Information of China (English)

    LI Shichun

    2004-01-01

    Based on the Thomas-Fermi-Dirac-Cheng model, atomic phase diagram or electron density versus atomic radius diagram describing the interaction properties of atoms of different kinds in equilibrium state is developed. Atomic phase diagram is established based on the two-atoms model. Besides atomic radius, electron density and continuity condition for electron density on interfaces between atoms, the lever law of atomic phase diagram involving other physical parameters is taken into account, such as the binding energy, for the sake of simplicity.

  3. 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

  4. Geometry and Moon Phases.

    Science.gov (United States)

    Thompson, Kenneth W.; Harrell, Marvin E.

    1997-01-01

    Describes an activity, designed to comply with the National Science Education Standards, that integrates science and mathematics concepts. Mathematical modeling of the moon's phases is employed to show students the role of mathematics in describing scientific phenomena. (DKM)

  5. Dual Phase Cosmic Rays

    CERN Document Server

    Shurtleff, Richard

    2008-01-01

    A calculation based on flat spacetime symmetries shows how there can be two quantum phases. For one, extreme phase change determines a conventional classical trajectory and four-momentum, i.e. mass times four-velocity. The other phase occurs in an effective particle state, with the effective energy and momentum being the rate of change of the phase with respect to time and distance. A cosmic ray proton moves along a classical trajectory, but exists in an effective particle state with an effective energy that depends on the local gravitational potential. Assumptions are made so that a cosmic ray proton in an ultra-high energy state detected near the Earth was in a much less energetic state in interstellar space. A 300 EeV proton incident on the Earth was a 2 PeV proton in interstellar space. The model predicts such protons are in states with even more energy near the Sun than when near the Earth.

  6. Unparticle phase effects

    CERN Document Server

    Chen, Chuan-Hung

    2007-01-01

    Unparticles proposed by Georgi carry CP conserving phases in their propagators. We demonstrate that these peculiar phases have an important impact on CP violation. Without including the strong QCD phases, we study the unparticle phase effects on the direct CP asymmetries in the exclusive decays of $\\bar B_d\\to \\pi^{+} \\pi^{-}$ and $B\\to \\pi K$, in which the flavor changing neutral currents are forbidden at tree level but induced by one-loop diagrams. Interesting and consistent results comparing to the data are obtained. In addition, we find that unparticles will significantly enhance the differential branching ratio of $b\\to s \\ell^{+} \\ell^{-}$ at the small invariant mass of $\\ell^{+} \\ell^{-}$. The forward-backward asymmetries for $b\\to s \\ell^{+} \\ell^{-}$ due to unparticles are also explored.

  7. 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 ...

  8. 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.

  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. The SAT phase transition

    Institute of Scientific and Technical Information of China (English)

    许可; 李未

    1999-01-01

    Phase transition is an important feature of SAT problem. For random k-SAT model, it is proved that as r(ratio of clauses to variables) increases, the structure of solutions will undergo a sudden change like satisfiability phase transition when r reaches a threshold point (r=rcr). This phenomenon shows that the satisfying truth assignments suddenly shift from being relatively different from each other to being very similar to each other.##属性不符

  11. Digital Receiver Phase Meter

    Science.gov (United States)

    Marcin, Martin; Abramovici, Alexander

    2008-01-01

    The software of a commercially available digital radio receiver has been modified to make the receiver function as a two-channel low-noise phase meter. This phase meter is a prototype in the continuing development of a phase meter for a system in which radiofrequency (RF) signals in the two channels would be outputs of a spaceborne heterodyne laser interferometer for detecting gravitational waves. The frequencies of the signals could include a common Doppler-shift component of as much as 15 MHz. The phase meter is required to measure the relative phases of the signals in the two channels at a sampling rate of 10 Hz at a root power spectral density digital receiver. The input RF signal is first fed to the input terminal of an analog-to-digital converter (ADC). To prevent aliasing errors in the ADC, the sampling rate must be at least twice the input signal frequency. The sampling rate of the ADC is governed by a sampling clock, which also drives a digital local oscillator (DLO), which is a direct digital frequency synthesizer. The DLO produces samples of sine and cosine signals at a programmed tuning frequency. The sine and cosine samples are mixed with (that is, multiplied by) the samples from the ADC, then low-pass filtered to obtain in-phase (I) and quadrature (Q) signal components. A digital signal processor (DSP) computes the ratio between the Q and I components, computes the phase of the RF signal (relative to that of the DLO signal) as the arctangent of this ratio, and then averages successive such phase values over a time interval specified by the user.

  12. 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.

  13. 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.

  14. Phase transition studies of the exsoluted ilmenite-hematite at high pressure and temperature conditions

    Science.gov (United States)

    Kim, Y.; Secco, R.; Hwang, G.; Bao, X.; Ming, L.

    2011-12-01

    Ilmenite minerals found in Switzerland Alpe Arami peridotite massif indicate that these precipitates are metastable phases converted from the single perovskite phase during the ascending process in the mantle. After this work, lots of subsequent high pressure-temperature experiments on ilmenite itself and its solid solution phases were performed to check the phase boundary from the starting phase to perovskite structure. This study also aims to identify the phase transition sequence(s) of the exsoluted ilmenite-hematite specimen where its locality is the Allard Lake area, Quebac, Canada, under high pressure and high temperature conditions. Bulky ore sample consists of 76.2% ilmenite and 23.8% hematite in volume. Chemistry of ilmenite is Fe1.02Mg0.13Ti0.92O3 and that of hematite, Fe2O3. Lattice parameters of ilmenite are a=5.08287(2)Å, c=14.0511(1)Å, and those of hematite a=5.04378(4)Å, c=13.7757(2)Å. Walker-type large volume multi anvil cell was employed for high pressure and high temperature experiment up to 14GPa and 2400K, respectively. Recovered samples after high pressure-temperature treatment were subjected to identify the product phase(s) by the general area detector x-ray diffraction method with conventional x-radiation as well as the x-ray micro-diffraction technique using synchrotron radiation. Phase transition sequences observed are the followings: starting exsoluted ilmenite-hematite phase transforms to the single phase of perovskite, then this perovskite phase disproportionate into various kind of oxides. Phase boundaries to perovskite, then to oxides were determined to be P(GPa)=31.8 - 0.0178T(K), and P(GPa)=23.8 - 0.0072T(K), respectively. Present result is different from the previous reports of Syono et al. (1980)(i.e., P(GPa)=25.2 - 0.01T(K)) and Ming et al. (2006)(i.e., P(GPa)=16.0 - 0.0012T(K)). Based on the present results applied to the Alpe Arami peridotite massif, source region would be much shallower part at the upper mantle(i.e., 240km

  15. Optical Phase Imaging Using Synthetic Aperture Illumination and Phase Retrieval

    CERN Document Server

    Lee, Dennis J

    2016-01-01

    We perform quantitative phase imaging using phase retrieval to implement synthetic aperture imaging. Compared to digital holography, the developed technique is simpler, less expensive, and more stable.

  16. 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.

  17. Polymorphic phase transition in Superhydrous Phase B

    Science.gov (United States)

    Koch-Müller, M.; Dera, P.; Fei, Y.; Hellwig, H.; Liu, Z.; Orman, J. Van; Wirth, R.

    2005-09-01

    We synthesized superhydrous phase B (shy-B) at 22 GPa and two different temperatures: 1200°C (LT) and 1400°C (HT) using a multi-anvil apparatus. The samples were investigated by transmission electron microscopy (TEM), single crystal X-ray diffraction, Raman and IR spectroscopy. The IR spectra were collected on polycrystalline thin-films and single crystals using synchrotron radiation, as well as a conventional IR source at ambient conditions and in situ at various pressures (up to 15 GPa) and temperatures (down to -180°C). Our studies show that shy-B exists in two polymorphic forms. As expected from crystal chemistry, the LT polymorph crystallizes in a lower symmetry space group ( Pnn2), whereas the HT polymorph assumes a higher symmetry space group ( Pnnm). TEM shows that both modifications consist of nearly perfect crystals with almost no lattice defects or inclusions of additional phases. IR spectra taken on polycrystalline thin films exhibit just one symmetric OH band and 29 lattice modes for the HT polymorph in contrast to two intense but asymmetric OH stretching bands and at least 48 lattice modes for the LT sample. The IR spectra differ not only in the number of bands, but also in the response of the bands to changes in pressure. The pressure derivatives for the IR bands are higher for the HT polymorph indicating that the high symmetry form is more compressible than the low symmetry form. Polarized, low-temperature single-crystal IR spectra indicate that in the LT-polymorph extensive ordering occurs not only at the Mg sites but also at the hydrogen sites.

  18. Polymorphic Phase Transition in Superhydrous Phase B

    Energy Technology Data Exchange (ETDEWEB)

    Koch-Muller,M.; Dera, P.; Fei, Y.; Hellwig, H.; Liu, Z.; Van Orman, J.; Wirth, R.

    2005-01-01

    We synthesized superhydrous phase B (shy-B) at 22 GPa and two different temperatures: 1200 C (LT) and 1400 C (HT) using a multi-anvil apparatus. The samples were investigated by transmission electron microscopy (TEM), single crystal X-ray diffraction, Raman and IR spectroscopy. The IR spectra were collected on polycrystalline thin-films and single crystals using synchrotron radiation, as well as a conventional IR source at ambient conditions and in situ at various pressures (up to 15 GPa) and temperatures (down to -180 C). Our studies show that shy-B exists in two polymorphic forms. As expected from crystal chemistry, the LT polymorph crystallizes in a lower symmetry space group (Pnn2), whereas the HT polymorph assumes a higher symmetry space group (Pnnm). TEM shows that both modifications consist of nearly perfect crystals with almost no lattice defects or inclusions of additional phases. IR spectra taken on polycrystalline thin films exhibit just one symmetric OH band and 29 lattice modes for the HT polymorph in contrast to two intense but asymmetric OH stretching bands and at least 48 lattice modes for the LT sample. The IR spectra differ not only in the number of bands, but also in the response of the bands to changes in pressure. The pressure derivatives for the IR bands are higher for the HT polymorph indicating that the high symmetry form is more compressible than the low symmetry form. Polarized, low-temperature single-crystal IR spectra indicate that in the LT-polymorph extensive ordering occurs not only at the Mg sites but also at the hydrogen sites.

  19. The Phases of QCD

    CERN Document Server

    Shuryak, E V

    1996-01-01

    In the recent years we have learned that light quarks play a crucial role in QCD-like theories, transforming it to many different phases. We review what is known about them, both from lattice and non-lattice approaches. A particularly simple mechanism of the QCD chiral restoration phase transition is discussed first: it suggests that it is a transition from randomly placed tunneling events (instantons) at low T to strongly localized tunneling-anti-tunneling pairs at high T. Many features of the transition found on the lattice can be explained in this simple picture. Very relevant for RHIC, this approach predicts a strong non-perturbative interaction between quarks $above$ the phase transition. It also predicts that QGP-like phase sets in at $zero$ temperature, provided few more light quark flavors are added to QCD. Finally, we also discuss possible experimental signatures of the QCD phase transition. One issue is CERN dilepton data, possibly related with ``dropping'' masses of $\\rho, A_1$ mesons. Another is d...

  20. Progress in ferrite phase shifters

    Science.gov (United States)

    Boyd, C. R., Jr.

    1983-10-01

    Advances in the technology of reciprocal ferrite phase shifters are outlined. Nonlatching rotary-field phase shifters have been produced with enhanced phase accuracy and modest control power. A significant quantity of dual-mode latching units has been built at 35 GHz, with good results. Both types of phase shifter can be adapted to perform other functions in addition to phase shifting. Examples of phase shifters that perform duplexing and polarization switching functions are given.

  1. 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.

  2. Kirchhoff migration without phases

    Science.gov (United States)

    Bardsley, Patrick; Guevara Vasquez, Fernando

    2016-10-01

    We present a simple, frequency domain, preprocessing step to Kirchhoff migration that allows the method to image scatterers when the wave field phase information is lost at the receivers, and only intensities are measured. The resulting imaging method does not require knowing the phases of the probing field or manipulating the phase of the wave field at the receivers. In a regime where the scattered field is small compared to the probing field, the problem of recovering the full-waveform scattered field from intensity data can be formulated as an embarrassingly simple least-squares problem. Although this only recovers the projection (on a known subspace) of the full-waveform scattered field, we show that, for high frequencies, this projection gives Kirchhoff images asymptotically identical to the images obtained with full waveform data. Our method can also be used when the source is modulated by a Gaussian process and autocorrelations are measured at an array of receivers.

  3. Kirchhoff migration without phases

    CERN Document Server

    Bardsley, Patrick

    2016-01-01

    We present a simple, frequency domain, preprocessing step to Kirchhoff migration that allows the method to image scatterers when the wave field phase information is lost at the receivers, and only intensities are measured. The resulting imaging method does not require knowing the phases of the probing field or manipulating the phase of the wave field at the receivers. In a regime where the scattered field is small compared to the probing field, the problem of recovering the full-waveform scattered field from intensity data can be formulated as an embarrassingly simple least-squares problem. Although this only recovers the projection (on a known subspace) of the full-waveform scattered field, we show that, for high frequencies, this projection gives Kirchhoff images asymptotically identical to the images obtained with full waveform data. Our method can also be used when the source is modulated by a Gaussian process and autocorrelations are measured at an array of receivers.

  4. 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)

  5. 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

  6. 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

  7. Compressive Phase Contrast Tomography

    CERN Document Server

    Maia, F R N C; Marchesini, S; Padmore, H A; Parkinson, D Y; Pien, J; Schirotzek, A; Yang, C; 10.1117/12.861946

    2010-01-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. In- terference 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 con- trast 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).

  8. 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

  9. 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

  10. Can't help falling in lave SMILE or CRY?松本润

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    恋爱让人开心,也每人哭泣.如果陷入了爱河……微笑亦或是流泪,松本润的恋爱观同样充满了故事,只有经历了感情世界的颠簸曲折,才能令人真正成长。

  11. 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....

  12. Entropy of phase measurement quantum phase via quadrature measurement

    CERN Document Server

    My, R; My, Robert; Uni, Palacky

    1995-01-01

    The content of phase information of an arbitrary phase--sensitive measurement is evaluated using the maximum likelihood estimation. The phase distribution is characterized by the relative entropy--a nonlinear functional of input quantum state. As an explicit example the multiple measurement of quadrature operator is interpreted as quantum phase detection achieving the ultimate resolution predicted by the Fisher information.

  13. C14-Crash. The C14-method and dendrochronology, unveiling the illusion. 2. rev. ed.; C14-Crash. Das Ende der Illusion, mit Radiokarbonmethode und Dendrochronologie datieren zu koennen

    Energy Technology Data Exchange (ETDEWEB)

    Bloess, C.; Niemitz, H.U.

    2000-07-01

    In this second edition of the book, which was published almost three years after the first edition, the authors reiterate and substantiate their doubts as to the basic theories underlying the radiocarbon dating method and the applicability of dendrochronology. (orig/CB) [German] In dieser zweiten Auflage des Buches, die knapp drei Jahre nach der ersten erschien, vertiefen die Autoren ihre Zweifel an den grundlegenden Theorien und den bisherigen Resultaten der Radiokarbonmethode und der Dendrochronologie. (orig./CB)

  14. Adaptive MGS Phase Retrieval

    Science.gov (United States)

    Basinger, Scott A.; Bikkannavar, Siddarayappa; Cohen, David; Green, Joseph J.; Lou, John; Ohara, Catherine; Redding, David; Shi, Fang

    2008-01-01

    Adaptive MGS Phase Retrieval software uses the Modified Gerchberg-Saxton (MGS) algorithm, an image-based sensing method that can turn any focal plane science instrument into a wavefront sensor, avoiding the need to use external metrology equipment. Knowledge of the wavefront enables intelligent control of active optical systems.

  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. SSIP Phase I Roadmap

    Science.gov (United States)

    Vinh, Megan; Lucas, Anne; Taylor, Cornelia; Kelley, Grace; Kasprzak, Christina

    2014-01-01

    This roadmap provides a description of the activities involved in the development of the State Systemic Improvement Plan (SSIP) (SPP/APR Indicators C11 and B17) due to the Office of Special Education Programs (OSEP) on April 1, 2015. The roadmap is intended to support states with completing Phase I of the SSIP process. This document provides…

  17. 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.

  18. 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: A...

  19. Solid-phase microextraction

    DEFF Research Database (Denmark)

    Nilsson, Torben

    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...

  20. Fimbrial phase variation

    DEFF Research Database (Denmark)

    Khandige, Surabhi; Møller-Jensen, Jakob

    2016-01-01

    if the fimbrial diversity seen at the population level is the product of random stochasticity or a concerted effort based on active communication. Here we discuss the possibility of a mechanism alternative to a stochastic fimbrial phase variation model affecting the dynamics of a heterogeneous population....

  1. Phase separation micro molding

    NARCIS (Netherlands)

    Vogelaar, Laura

    2005-01-01

    The research described in this thesis concerns the development of a new microfabrication method, Phase Separation Micro Molding (PSμM). While microfabrication is still best known from semiconductor industry, where it is used to integrate electrical components on a chip, the scope has immensely expan

  2. 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...

  3. 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...

  4. Gas-Phase Thermolysis

    DEFF Research Database (Denmark)

    Carlsen, Lars; Egsgaard, Helge; Schaumann, Ernst

    1980-01-01

    The unimolecular gas-phase thermolytic decomposition of three silylated thionocarboxylic acid derivatives (2b), (3), and (8) have been studied by the flash vacuum thermolysis–field ionization mass spectrometry technique in the temperature range from 783 to 1 404 K in order to elucidate its possib...

  5. Phase Computations and Phase Models for Discrete Molecular Oscillators.

    OpenAIRE

    Demir, Alper; Şuvak, Önder

    2012-01-01

    RESEARCH Open Access Phase computations and phase models for discrete molecular oscillators Onder Suvak* and Alper Demir Abstract Background: Biochemical oscillators perform crucial functions in cells, e.g., they set up circadian clocks. The dynamical behavior of oscillators is best described and analyzed in terms of the scalar quantity, phase. A rigorous and useful definition for phase is based on the so-called isochrons of oscillators. Phase computation techniques for ...

  6. Phase II Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Schuknecht, Nate [Project Manager; White, David [Principle Investigator; Hoste, Graeme [Research Engineer

    2014-09-11

    The SkyTrough DSP will advance the state-of-the-art in parabolic troughs for utility applications, with a larger aperture, higher operating temperature, and lower cost. The goal of this project was to develop a parabolic trough collector that enables solar electricity generation in the 2020 marketplace for a 216MWe nameplate baseload power plant. This plant requires an LCOE of 9¢/kWhe, given a capacity factor of 75%, a fossil fuel limit of 15%, a fossil fuel cost of $6.75/MMBtu, $25.00/kWht thermal storage cost, and a domestic installation corresponding to Daggett, CA. The result of our optimization was a trough design of larger aperture and operating temperature than has been fielded in large, utility scale parabolic trough applications: 7.6m width x 150m SCA length (1,118m2 aperture), with four 90mm diameter × 4.7m receivers per mirror module and an operating temperature of 500°C. The results from physical modeling in the System Advisory Model indicate that, for a capacity factor of 75%: The LCOE will be 8.87¢/kWhe. SkyFuel examined the design of almost every parabolic trough component from a perspective of load and performance at aperture areas from 500 to 2,900m2. Aperture-dependent design was combined with fixed quotations for similar parts from the commercialized SkyTrough product, and established an installed cost of $130/m2 in 2020. This project was conducted in two phases. Phase I was a preliminary design, culminating in an optimum trough size and further improvement of an advanced polymeric reflective material. This phase was completed in October of 2011. Phase II has been the detailed engineering design and component testing, which culminated in the fabrication and testing of a single mirror module. Phase II is complete, and this document presents a summary of the comprehensive work.

  7. Phase Transitions of Simple Systems

    CERN Document Server

    Berry, Stephen

    2008-01-01

    This monograph develops a unified microscopic basis for phases and phase changes of bulk matter and small systems in terms of classical physics. The origins of such phase changes are derived from simple but physically relevant models of how transitions between rigid crystalline, glassy and fluid states occur, how phase equilibria arise, and how bulk properties evolve from those of small systems.

  8. 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

  9. Phase-only optical encryption

    DEFF Research Database (Denmark)

    Mogensen, P.C.; Glückstad, J.

    2000-01-01

    We have implemented a phase-only optical encryption and decryption system with a readout based on the generalized phase-contrast method. The experimental system has been implemented with Liquid-crystal spatial light modulators to generate binary phase-encrypted masks and a decrypting key. A phase......-contrast filter is used to display the phase information. (C) 2000 Optical Society of America....

  10. Phase noise reduction by self-phase locking in semiconductor lasers using phase conjugate feedback

    DEFF Research Database (Denmark)

    Petersen, Lykke; Gliese, Ulrik Bo; Nielsen, Torben Nørskov

    1994-01-01

    A theoretical analysis of the behavior of the frequency/phase noise of semiconductor lasers with external phase conjugate feedback is presented. It is shown that the frequency noise is drastically reduced even for lasers with butt-coupled phase conjugate mirrors. In this laser system, the phase...

  11. 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.

  12. SKIPAL, Phase 2

    Science.gov (United States)

    2009-11-01

    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...Phase 2, SKIPAL incorporated the Spring Web MVC framework to facilitate future integration efforts with SKIWeb. Spring Web MVC is a web framework...Nonparametric Analysis of Fingerprint Data on Large Data Sets,” Pattern Recognition, vol. 40, no. 9, pp. 2574-2584, Sep. 2007. 4. Davis, J. and Goadrich

  13. Phases, phase equilibria, and phase rules in low-dimensional systems

    Energy Technology Data Exchange (ETDEWEB)

    Frolov, T., E-mail: timfrol@berkeley.edu [Department of Materials Science and Engineering, University of California, Berkeley, California 94720 (United States); Mishin, Y., E-mail: ymishin@gmu.edu [Department of Physics and Astronomy, MSN 3F3, George Mason University, Fairfax, Virginia 22030 (United States)

    2015-07-28

    We present a unified approach to thermodynamic description of one, two, and three dimensional phases and phase transformations among them. The approach is based on a rigorous definition of a phase applicable to thermodynamic systems of any dimensionality. Within this approach, the same thermodynamic formalism can be applied for the description of phase transformations in bulk systems, interfaces, and line defects separating interface phases. For both lines and interfaces, we rigorously derive an adsorption equation, the phase coexistence equations, and other thermodynamic relations expressed in terms of generalized line and interface excess quantities. As a generalization of the Gibbs phase rule for bulk phases, we derive phase rules for lines and interfaces and predict the maximum number of phases than may coexist in systems of the respective dimensionality.

  14. Phases, phase equilibria, and phase rules in low-dimensional systems.

    Science.gov (United States)

    Frolov, T; Mishin, Y

    2015-07-28

    We present a unified approach to thermodynamic description of one, two, and three dimensional phases and phase transformations among them. The approach is based on a rigorous definition of a phase applicable to thermodynamic systems of any dimensionality. Within this approach, the same thermodynamic formalism can be applied for the description of phase transformations in bulk systems, interfaces, and line defects separating interface phases. For both lines and interfaces, we rigorously derive an adsorption equation, the phase coexistence equations, and other thermodynamic relations expressed in terms of generalized line and interface excess quantities. As a generalization of the Gibbs phase rule for bulk phases, we derive phase rules for lines and interfaces and predict the maximum number of phases than may coexist in systems of the respective dimensionality.

  15. Electroweak phase transitions

    CERN Document Server

    Fodor, Z

    2000-01-01

    Recent developments on the four dimensional (4d) lattice studies of the finite temperature electroweak phase transition (EWPT) are summarized. The phase diagram is given in the continuum limit. The finite temperature SU(2)-Higgs phase transition is of first order for Higgs-boson masses m/sub H/<66.5+or-1.4 GeV. Above this endpoint only a rapid cross-over can be seen. The full 4d result agrees completely with that of the dimensional reduction approximation. The Higgs-boson endpoint mass in the standard model (SM) would be 72.1+or-1. 4 GeV. Taking into account the LEP Higgs-boson mass lower bound excludes any EWPT in the SM. A one-loop calculation of the static potential in the SU(2)-Higgs model enables a precise comparison between lattice simulations and perturbative results. The most popular extension of the SM, the minimal supersymmetric SM (MSSM) is also studied on 4d lattices. (17 refs).

  16. Compactification on phase space

    Science.gov (United States)

    Lovelady, Benjamin; Wheeler, James

    2016-03-01

    A major challenge for string theory is to understand the dimensional reduction required for comparison with the standard model. We propose reducing the dimension of the compactification by interpreting some of the extra dimensions as the energy-momentum portion of a phase-space. Such models naturally arise as generalized quotients of the conformal group called biconformal spaces. By combining the standard Kaluza-Klein approach with such a conformal gauge theory, we may start from the conformal group of an n-dimensional Euclidean space to form a 2n-dimensional quotient manifold with symplectic structure. A pair of involutions leads naturally to two n-dimensional Lorentzian manifolds. For n = 5, this leaves only two extra dimensions, with a countable family of possible compactifications and an SO(5) Yang-Mills field on the fibers. Starting with n=6 leads to 4-dimensional compactification of the phase space. In the latter case, if the two dimensions each from spacetime and momentum space are compactified onto spheres, then there is an SU(2)xSU(2) (left-right symmetric electroweak) field between phase and configuration space and an SO(6) field on the fibers. Such a theory, with minor additional symmetry breaking, could contain all parts of the standard model.

  17. Zintl and intermetallic phases grown from calcium/lithium flux

    Science.gov (United States)

    Blankenship, Trevor

    Metal flux synthes is a useful alternative method to high temperature solid state synthesis; it allows easy diffusion of reactants at lower temperatures, and presents favorable conditions for crystal growth. A mixed flux of calcium and lithium in a 1:1 ratio was explored in this work; this mixture melts at 300°C and is an excellent solvent for main group elements and CaH 2. Reactions of p-block elements in a 1:1 Ca/Li flux have produced several new intermetallic and Zintl phases. Electronegative elements from groups 14 and 15 are reduced to anions in this flux, yielding charge-balanced products. More electropositive metals from group 13 are not fully reduced; the resulting products are complex intermetallics. The reactions of tin or lead and carbon in Ca/Li flux produced the analogous phases Ca11Tt3C8 (Tt = Sn, Pb) in the monoclinic C21/c space group (a = 13.2117(8) A, b =10.7029(7) A, c = 14.2493(9) A, beta = 105.650(1)° for the Sn analog). These compounds are carbide Zintl phases that includes the rare combination of C3 4- and C22- units as well as Sn4- or Pb4- anions. Ca/Li flux reactions of CaH2 and arsenic have produced the Zintl phases LiCa3As 2H in orthorhombic Pnma (a = 11.4064(7), b = 4.2702(3), c = 11.8762(8) A), and Ca 13As6C0.46N1.155H6.045in tetragonal P4/mbm (a = 15.7493(15), c = 9.1062(9) A). The complex stoichiometry of the latter phase was caused by incorporation of light element contaminants and was studied by neutron diffraction, showing mixing of anionic sites to achieve charge balance. Ca/Li flux reactions with group 13 metals have resulted in several new intermetallic phases. Reactions of indium and CaH2 in the Ca/Li flux (with or without boron) formed Ca53In13B4-x H23+x(2.4 < x < 4.0) in cubic space group Im-3 (a = 16.3608(6) A) which features metallic indium atoms and ionic hydride sites. The electronic properties of this "subhydride" were confirmed by 1H and 115In NMR spectroscopy. Attempts to replace boron with carbon yielded Ca12InC13-x

  18. Mapping the QCD phase diagram

    CERN Document Server

    Rajagopal, K

    1999-01-01

    The QCD vacuum in which we live, which has the familiar hadrons as its excitations, is but one phase of QCD, and far from the simplest one at that. One way to better understand this phase and the nonperturbative dynamics of QCD more generally is to study other phases and the transitions between phases. We are engaged in a voyage of exploration, mapping the QCD phase diagram as a function of temperature T and baryon number chemical potential mu . Because of asymptotic freedom, the high temperature and high baryon density phases of QCD are more simply and more appropriately described in terms of quarks and gluons as degrees of freedom, rather than hadrons. The chiral symmetry breaking condensate which characterizes the vacuum phase melts away. At high densities, quarks form Cooper pairs and new condensates develop. The formation of such superconducting phases requires only weak attractive interactions; these phases may nevertheless break chiral symmetry and have excitations which are indistinguishable from thos...

  19. Design of a Phase Detector for the Phase Probe

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Phase probe system is an important part of the cyclotron beam diagnostic systems. Inside the cyclotron, the beam has to be in phase with RF. Because of the mechanical deformation and instability of

  20. Athena: Assessment Phase Activities

    Science.gov (United States)

    Lumb, David; Ayre, Mark

    2015-09-01

    The Athena mission concept has been proposed by the community in response to science themes of the Hot and Energetic Universe. Unlike other, competitive, mission selection exercises this "Large" class observatory mission has essentially been pre-selected. Nevertheless it has to be demonstrated that Athena meets the programmatic constraints of 1Bn euro cost cap, and a readiness level appropriate for formal mission adoption by the end 2019. This should be confirmed through a Phase A study conducted with two parallel industry activities. We describe the technical and programmatic content of these and latest progress in space and ground segment definition.

  1. 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.

  2. Collective neurodynamics: Phase diagram

    OpenAIRE

    Ovchinnikov, Igor V.; Li, Wenyuan; Schwartz, Robert N.; Hudson, Andrew E.; Meier, Karlheinz; Wang, Kang L.

    2016-01-01

    Here, we conceptualize the phase diagram of collective short-term bio-chemo-electric component of neurodynamics (S-ND) on the parameter space of externally, e.g., pharmacologically, controllable single-neuron parameters such as the resting potential and/or firing threshold, repolarization time, etc. This concept may become a useful tool for the systematization of knowledge in anesthesiology and provide a fruitful venue for future studies of the high-level S-ND functionalities such as short-te...

  3. Quantum phase magnification

    Science.gov (United States)

    Hosten, O.; Krishnakumar, R.; Engelsen, N. J.; Kasevich, M. A.

    2016-06-01

    Quantum metrology exploits entangled states of particles to improve sensing precision beyond the limit achievable with uncorrelated particles. All previous methods required detection noise levels below this standard quantum limit to realize the benefits of the intrinsic sensitivity provided by these states. We experimentally demonstrate a widely applicable method for entanglement-enhanced measurements without low-noise detection. The method involves an intermediate quantum phase magnification step that eases implementation complexity. We used it to perform squeezed-state metrology 8 decibels below the standard quantum limit with a detection system that has a noise floor 10 decibels above the standard quantum limit.

  4. Solid phases of tenoxicam.

    Science.gov (United States)

    Cantera, Rodrigo G; Leza, María G; Bachiller, Carmen M

    2002-10-01

    In this report we describe the preparation and characterization of four polymorphic forms of tenoxicam; they are, three 1:1 stoichiometric solvates with acetonitrile, dioxane, and N,N-dimethylformamide, and an amorphous phase obtained by recrystallization in various solvents. Polymorph IV and solvates with dioxane and N,N-dimethylformamide are reported for the first time in this paper. In addition, three solvates were crystallized in acetone, ethyl acetate, and isopropyl alcohol. These solid forms were characterized by X-ray powder diffraction, differential scanning calorimetry, infrared spectroscopy, thermogravimetry, optical microscopy, and elemental analysis. Solid-state properties, intrinsic dissolution rate, and dissolution kinetics from formulated tablets are also provided.

  5. 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

  6. Phase retrieval using nonlinear diversity.

    Science.gov (United States)

    Lu, Chien-Hung; Barsi, Christopher; Williams, Matthew O; Kutz, J Nathan; Fleischer, Jason W

    2013-04-01

    We extend the Gerchberg-Saxton algorithm to phase retrieval in a nonlinear system. Using a tunable photorefractive crystal, we experimentally demonstrate the noninterferometric technique by reconstructing an unknown phase object from optical intensity measurements taken at different nonlinear strengths.

  7. Phase IV of Drug Development

    OpenAIRE

    Viraj Suvarna

    2010-01-01

    Not all Phase IV studies are post-marketing surveillance (PMS) studies but every PMS study is a phase IV study. Phase IV is also an important phase of drug development. In particular, the real world effectiveness of a drug as evaluated in an observational, non-interventional trial in a naturalistic setting which complements the efficacy data that emanates from a pre-marketing randomized controlled trial (RCT). No matter how many patients are studied pre-marketing in a controlled environment, ...

  8. On the degenerate phase boundaries

    CERN Document Server

    Ma, Y; Kuang, Z; Ma, Yongge; Liang, Canbin; Kuang, Zhiquan

    1999-01-01

    The structure of the phase boundary between degenerate and non-degenerate regions in Ashtekar's gravity has been studied by Bengtsson and Jacobson who conjectured that the "phase boundary" should always be null. In this paper, we reformulate the reparametrization procedure in the mapping language and distinguish a phase boundary from its image. It is shown that the image has to be null, while the nullness of the phase boundary requries more suitable criterion.

  9. 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.)

  10. Nonlinear phased array imaging

    Science.gov (United States)

    Croxford, Anthony J.; Cheng, Jingwei; Potter, Jack N.

    2016-04-01

    A technique is presented for imaging acoustic nonlinearity within a specimen using ultrasonic phased arrays. Acoustic nonlinearity is measured by evaluating the difference in energy of the transmission bandwidth within the diffuse field produced through different focusing modes. The two different modes being classical beam forming, where delays are applied to different element of a phased array to physically focus the energy at a single location (parallel firing) and focusing in post processing, whereby one element at a time is fired and a focused image produced in post processing (sequential firing). Although these two approaches are linearly equivalent the difference in physical displacement within the specimen leads to differences in nonlinear effects. These differences are localized to the areas where the amplitude is different, essentially confining the differences to the focal point. Direct measurement at the focal point are however difficult to make. In order to measure this the diffuse field is used. It is a statistical property of the diffuse field that it represents the total energy in the system. If the energy in the diffuse field for both the sequential and parallel firing case is measured then the difference between these, within the input signal bandwidth, is largely due to differences at the focal spot. This difference therefore gives a localized measurement of where energy is moving out of the transmission bandwidth due to nonlinear effects. This technique is used to image fatigue cracks and other damage types undetectable with conventional linear ultrasonic measurements.

  11. EGEE enters second phase

    CERN Multimedia

    2006-01-01

    This month has seen the launch of the second two-year phase of the Enabling Grids for E-sciencE project (EGEE-II), with a transition meeting for the partners held at CERN on 12-13 April. Co-funded by the European Commission and coordinated by CERN, the EGEE project is providing an international Grid computing infrastructure - now numbering some 200 sites and 20 000 CPUs in 39 countries - to support the scientific community worldwide. 'We are all very happy about the smooth start of the second phase of EGEE,' said Project Director Bob Jones. 'The project builds on the successes of its first two years and we are now focussing on the stability of the deployed infrastructure. Growing beyond our pilot application areas of HEP and biomedicine, we now see increasing use by researchers from other fields. Recently we've added finance and fusion to the list of disciplines we support, and we are always looking for new users.' More information on EGEE can be found at www.eu-egee.org.

  12. Phase down of amalgam

    Science.gov (United States)

    AL-Rabab’ah, Mohammad A.; Bustani, Mohammad A.; Khraisat, Ameen S.; Sawair, Faleh A.

    2016-01-01

    Objectives To assess the knowledge of Jordanian dentists toward phase down of dental amalgam as recommended by the Minamata Convention, and their training and competency in placing posterior composites. Methods This study was conducted through structured questionnaire interviews with randomly selected cohort of dentists in Jordan between March 2015 and June 2015. Out of 230 dentists who were invited, 196 (85.2%) agreed to participate. Dentists were asked if they know about the Minamata Convention. They were also asked about their training in placement of posterior composite. Results Out of the 196 interviewed, only 13.8% know about Minamata Convention and 17% had an undergraduate training in favor of placing composites in posterior teeth. Approximately 50% of those dentists were not trained in using rubber dam when placing posterior composites, while only 38.3% had training in sectional matrix placement. Undergraduate training did not influence (p=0.00) the dentists’ decision to remove old amalgam based on patient’s demands. Only 28.1% were of the opinion of discontinuing the use of amalgam due to its alleged health and environmental hazards. There was no general agreement on the type of composite, liner, and bonding strategy when placing posterior composites. Conclusion Dentists are not well informed on the Minamata Convention and the phase down of amalgam. Training in posterior composite placement should be given more room in undergraduate curriculum and continuous dental education. PMID:27874155

  13. Phase behavior of hard particles

    NARCIS (Netherlands)

    Duijneveldt, J.S. van; Lekkerkerker, H.N.W.

    1995-01-01

    The phase behavior of hard particles and mixtures thereof is reviewed. Special attention is given to a lattice model consisting of hard hexagons and points on a triangular lattice. This model appears to have two disordered phases and an ordered phase.

  14. Phase extraction based on sinusoidal extreme strip phase shifting method

    Science.gov (United States)

    Hui, Mei; Liu, Ming; Dong, Liquan; Liu, Xiaohua; Zhao, Yuejin

    2015-08-01

    Multiple synthetic aperture imaging can enlarge pupil diameter of optical systems, and increase system resolution. Multiple synthetic aperture imaging is a cutting-edge topic and research focus in recent years, which is prospectively widely applied in fields like astronomical observations and aerospace remote sensing. In order to achieve good imaging quality, synthetic aperture imaging system requires phase extraction of each sub-aperture and co-phasing of whole aperture. In the project, an in-depth study about basic principles and methods of segments phase extraction was done. The study includes: application of sinusoidal extreme strip light irradiation phase shift method to extract the central dividing line to get segment phase extraction information, and the use of interference measurement to get the aperture phase extraction calibration coefficients of spherical surface. Study about influence of sinusoidal extreme strip phase shift on phase extraction, and based on sinusoidal stripe phase shift from multiple linear light sources of the illumination reflected image, to carry out the phase shift error for inhibiting the effect in the phase extracted frame.

  15. DEGRADATION BEHAVIORS OF NEW TYPE TiV-BASED HYDROGEN STORAGE ELECTRODE ALLOYS

    Institute of Scientific and Technical Information of China (English)

    X.Z. Sun; Y.F. Zhu; Y. Lin; R. Li; M.X. Gao; H.G. Pan

    2006-01-01

    The degradation behaviors of the TiV-based multiphase hydrogen storage alloy Ti0.8Zr0.2V3.2Mn0.64-Cr0.96Ni1.2 during electrochemical cycling in alkaline electrolyte have been studied by XRD, SEM,EIS and AES measurements. XRD analysis indicates that the alloy consists of a C14-type Laves phase and a V-based solid solution. The lattice parameters of both phases are increased after discharged with cycling, which indicates that more irreversible hydrogen remains not discharged in the alloy. It should be responsible for the decrease of discharge capacity. SEM micrographs show that after 10 electrochemical cycles, a large number of cracks can be observed in the alloy, existing mainly in the V-based solid solution phase. Moreover, after 30 cycles, the alloy particles are obviously pulverized due to the larger expansion and shrinkage of cell volumes during hydrogen absorption and desorption, which induces the fast degradation of the TiV-based hydrogen storage alloys. EIS and AES measurements indicate that some passive oxide film has been formed on the surface of alloy electrode, which has higher charge-transfer resistance, lower hydrogen diffusivity, and less electro-catalytic activity. Therefore it can be concluded that the pulverization and oxidation of the alloy are the main factors responsible for the fast degradation of the TiV-based hydrogen storage alloys.

  16. Geometric phase and Pancharatnam phase induced by light wave polarization

    CERN Document Server

    Lages, J; Vigoureux, J -M

    2013-01-01

    We use the quantum kinematic approach to revisit geometric phases associated with polarizing processes of a monochromatic light wave. We give the expressions of geometric phases for any, unitary or non-unitary, cyclic or non-cyclic transformations of the light wave state. Contrarily to the usually considered case of absorbing polarizers, we found that a light wave passing through a polarizer may acquire in general a non zero geometric phase. This geometric phase exists despite the fact that initial and final polarization states are in phase according to the Pancharatnam criterion and can not be measured using interferometric superposition. Consequently, there is a difference between the Pancharatnam phase and the complete geometric phase acquired by a light wave passing through a polarizer. We illustrate our work with the particular example of total reflection based polarizers.

  17. A modified phase-coding method for absolute phase retrieval

    Science.gov (United States)

    Xing, Y.; Quan, C.; Tay, C. J.

    2016-12-01

    Fringe projection technique is one of the most robust tools for three dimensional (3D) shape measurement. Various fringe projection methods have been proposed for addressing different issues in profilometry and phase-coding is one such technique employed to determine fringe orders for absolute phase retrieval. However this method is prone to fringe order error, while dealing with high-frequency fringes. This paper studies phase error introduced by system non-linearity in phase-coding and provides a mathematical model to obtain the maximum number of achievable codewords in a given scheme. In addition, a modified phase-coding method is also proposed for phase error compensation. Experimental study validates the theoretical analysis on the maximum number of achievable codewords and the performance of the modified phase-coding method is also illustrated.

  18. 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

  19. Dirac phase leptogenesis

    CERN Document Server

    Blanchet, Steve

    2007-01-01

    I present here a concise summary of the preprint arXiv:0707.3024, written in collaboration with A. Anisimov and P. Di Bari. There we discuss leptogenesis when {\\em CP} violation stems exlusively from the Dirac phase in the PMNS mixing matrix. Under this assumption it turns out that the situation is very constrained when a hierarchical heavy right-handed (RH) neutrino spectrum is considered: the allowed regions are small and the final asymmetry depends on the initial conditions. On the other hand, for a quasi-degenerate spectrum of RH neutrinos, the {\\em CP} asymmetry can be enhanced and the situation becomes much more favorable, with no dependence on the initial conditions. Interestingly, in the extreme case of resonant leptogenesis, in order to match the observed baryon asymmetry of the Universe, we obtain a lower bound on \\sin \\q_{13} which depends on the lightest active neutrino mass m_1.

  20. 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.

  1. Coherent imaging without phases

    CERN Document Server

    Moscoso, Miguel; Papanicolaou, George

    2015-01-01

    In this paper we consider narrow band, active array imaging of weak localized scatterers when only the intensities are recorded at an array with N transducers. We consider that the medium is homogeneous and, hence, wave propagation is fully coherent. This work is an extension of our previous paper, where we showed that using linear combinations of intensity-only measurements imaging of localized scatterers can be carried out efficiently using MUSIC or sparsity promoting optimization. Here we show the same strategy can be accomplished with only 3N-2 illuminations, therefore reducing enormously the data acquisition process. Furthermore, we show that in the paraxial regime one can form the images by using six illuminations only. In particular, this paraxial regime includes Fresnel and Fraunhofer diffraction. The key point of this work is that if one controls the illuminations, imaging with intensity-only can be easily reduced to a imaging with phases and, therefore, one can apply standard imaging techniques. Det...

  2. Algorithmic phase diagrams

    Science.gov (United States)

    Hockney, Roger

    1987-01-01

    Algorithmic phase diagrams are a neat and compact representation of the results of comparing the execution time of several algorithms for the solution of the same problem. As an example, the recent results are shown of Gannon and Van Rosendale on the solution of multiple tridiagonal systems of equations in the form of such diagrams. The act of preparing these diagrams has revealed an unexpectedly complex relationship between the best algorithm and the number and size of the tridiagonal systems, which was not evident from the algebraic formulae in the original paper. Even so, for a particular computer, one diagram suffices to predict the best algorithm for all problems that are likely to be encountered the prediction being read directly from the diagram without complex calculation.

  3. 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.

  4. VFT PHASE VOLTAGE MEASUREMENT IN THREE-PHASE ENCLOSED GIS

    Institute of Scientific and Technical Information of China (English)

    邹建华; 岳子丁; 李洋

    2002-01-01

    The measuring of VFT phase voltage in three-phase enclosed GIS is more complex and difficult than in single-phase ones. There are 3 capacitive sensors in the measuring system, the outputs of which are with a linear relation to the three phase voltages. This linear relation is presented with a factorial matrix. Because each capacitive sensor is coupled with the electric field of three phases (A, B, and C), the electric coupling coefficients are introduced. In order to determine the matrix of electric coupling coefficients, the numerical calculation method can be used. From the discussion on two types of three-phase enclosed GIS bus, i.e. standard arrangement and biased arrangement, the dominant electric coupling coefficients are named, which can be simply and approximately calculated by an analytic expression. Finally, as an example, the waveforms of VFT phase voltage generated on a three-phase enclosed GIS bus model are displayed. When a capacitive sensor is located at the 'shortest point' of phase A (or B, or C), the VFT phase voltage VA (or VB, or VC) can almost be measured by that capacitive sensor alone.

  5. Phase aberration effects in elastography.

    Science.gov (United States)

    Varghese, T; Bilgen, M; Ophir, J

    2001-06-01

    In sonography, phase aberration plays a role in the corruption of sonograms. Phase aberration does not have a significant impact on elastography, if statistically similar phase errors are present in both the pre- and postcompression signals. However, if the phase errors are present in only one of the pre- or postcompression signal pairs, the precision of the strain estimation process will be reduced. In some cases, increased phase errors may occur only in the postcompression signal due to changes in the tissue structure with the applied compression. Phase-aberration effects increase with applied strain and may be viewed as an image quality derating factor, much like frequency-dependent attenuation or undesired lateral tissue motion. In this paper, we present a theoretical and simulation study of the effects of phase aberration on the elastographic strain-estimation process, using the strain filter approach.

  6. Phase Referencing in Optical Interferometry

    CERN Document Server

    Filho, Mercedes E; 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; de Becker, Michael; Surdej, Jean; Aringer, Bernard; Hron, Joseph; Lebzelter, Thomas; Chiavassa, Andrea; Corradi, Romano; Harries, Tim

    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 images. Such techniques allow only to achieve modest dynamic ranges. However, with high contrast objects, for faint targets or when structure detail is needed, phase referencing techniques as used in radio interferometry, should theoretically achieve higher dynamic ranges for the same number of telescopes. Our approach is not to provide evidence either for or against the hypothesis that phase referenced imaging gives better dynamic range than closure phase imaging. Instead we wish to explore the potential of this techniq...

  7. Nonlinear Phase Control and Anomalous Phase Matching in Plasmonic Metasurfaces

    CERN Document Server

    Almeida, Euclides; Prior, Yehiam

    2015-01-01

    Metasurfaces, and in particular those containing plasmonic-based metallic elements, constitute a particularly attractive set of materials. By means of modern nanolithographic fabrication techniques, flat, ultrathin optical elements may be constructed. However, in spite of their strong optical nonlinearities, plasmonic metasurfaces have so far been investigated mostly in the linear regime. Here we introduce full nonlinear phase control over plasmonic elements in metasurfaces. We show that for nonlinear interactions in a phase-gradient nonlinear metasurface a new anomalous nonlinear phase matching condition prevails, which is the nonlinear analog of the generalized Snell law demonstrated for linear metasurfaces. This phase matching condition is very different from the other known phase matching schemes. The subwavelength phase control of optical nonlinearities provides a foundation for the design of flat nonlinear optical elements based on metasurfaces. Our demonstrated flat nonlinear elements (i.e. lenses) act...

  8. 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.

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

    Science.gov (United States)

    2014-03-01

    apply certain ideas from phase retrieval to resolve phase errors in SAR . Specifically, we use bistatic techniques to measure relative phases, and then we...imaging a scene of interest (left) using bistatic SAR techniques at three different times. As in Example 5.5, at the first time instant the aircraft are...Synthetic aperture radar ( SAR ) uses relative motion to produce fine resolution images from microwave frequencies and is a useful tool for regular

  10. Quantum Phase Transitions and Dimerized Phases in Frustrated Spin Ladder

    Institute of Scientific and Technical Information of China (English)

    WEN Rui; LIU Guang-Hua; TIAN Guang-Shan

    2011-01-01

    In this paper, we study the phase diagram of a frustrated spin ladder model by applying the bosonization technique and the density-matrix renormalization-group (DMRG) algorithm. Effect of the intra-chain next-nearestneighbor (NNN) super-exchange interaction is investigated in detail and the order parameters are calculated to detect the emergence of the dimerized phases. We find that the intra-chain NNN interaction plays a key role in inducing dimerized phases.

  11. Ion mixing and phase diagrams

    Science.gov (United States)

    Lau, S. S.; Liu, B. X.; Nicolet, M.-A.

    1983-05-01

    Interactions induced by ion irradiation are generally considered to be non-equilibrium processes, whereas phase diagrams are determined by phase equilibria. These two entities are seemingly unrelated. However, if one assumes that quasi-equilibrium conditions prevail after the prompt events, subsequent reactions are driven toward equilibrium by thermodynamical forces. Under this assumption, ion-induced reactions are related to equilibrium and therefore to phase diagrams. This relationship can be seen in the similarity that exists in thin films between reactions induced by ion irradiation and reactions induced by thermal annealing. In the latter case, phase diagrams have been used to predict the phase sequence of stable compound formation, notably so in cases of silicide formation. Ion-induced mixing not only can lead to stable compound formation, but also to metastable alloy formation. In some metal-metal systems, terminal solubilities can be greatly extended by ion mixing. In other cases, where the two constituents of the system have different crystal structures, extension of terminal solubility from both sides of the phase diagram eventually becomes structurally incompatible and a glassy (amorphous) mixture can form. The composition range where this bifurcation is likely to occur is in the two-phase regions of the phase diagram. These concepts are potentially useful guides in selecting metal pairs that from metallic glasses by ion mixing. In this report, phenomenological correlation between stable (and metastable) phase formation and phase diagram is discussed in terms of recent experimental data.

  12. 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

  13. Optimal Phase Oscillatory Network

    Science.gov (United States)

    Follmann, Rosangela

    2013-03-01

    Important topics as preventive detection of epidemics, collective self-organization, information flow and systemic robustness in clusters are typical examples of processes that can be studied in the context of the theory of complex networks. It is an emerging theory in a field, which has recently attracted much interest, involving the synchronization of dynamical systems associated to nodes, or vertices, of the network. Studies have shown that synchronization in oscillatory networks depends not only on the individual dynamics of each element, but also on the combination of the topology of the connections as well as on the properties of the interactions of these elements. Moreover, the response of the network to small damages, caused at strategic points, can enhance the global performance of the whole network. In this presentation we explore an optimal phase oscillatory network altered by an additional term in the coupling function. The application to associative-memory network shows improvement on the correct information retrieval as well as increase of the storage capacity. The inclusion of some small deviations on the nodes, when solutions are attracted to a false state, results in additional enhancement of the performance of the associative-memory network. Supported by FAPESP - Sao Paulo Research Foundation, grant number 2012/12555-4

  14. 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)

  15. Phase Transformations and Earthquakes

    Science.gov (United States)

    Green, H. W.

    2011-12-01

    Phase transformations have been cited as responsible for, or at least involved in, "deep" earthquakes for many decades (although the concept of "deep" has varied). In 1945, PW Bridgman laid out in detail the string of events/conditions that would have to be achieved for a solid/solid transformation to lead to a faulting instability, although he expressed pessimism that the full set of requirements would be simultaneously achieved in nature. Raleigh and Paterson (1965) demonstrated faulting during dehydration of serpentine under stress and suggested dehydration embrittlement as the cause of intermediate depth earthquakes. Griggs and Baker (1969) produced a thermal runaway model of a shear zone under constant stress, culminating in melting, and proposed such a runaway as the origin of deep earthquakes. The discovery of Plate Tectonics in the late 1960s established the conditions (subduction) under which Bridgman's requirements for earthquake runaway in a polymorphic transformation could be possible in nature and Green and Burnley (1989) found that instability during the transformation of metastable olivine to spinel. Recent seismic correlation of intermediate-depth-earthquake hypocenters with predicted conditions of dehydration of antigorite serpentine and discovery of metastable olivine in 4 subduction zones, suggests strongly that dehydration embrittlement and transformation-induced faulting are the underlying mechanisms of intermediate and deep earthquakes, respectively. The results of recent high-speed friction experiments and analysis of natural fault zones suggest that it is likely that similar processes occur commonly during many shallow earthquakes after initiation by frictional failure.

  16. 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.

  17. Learning phase transitions by confusion

    CERN Document Server

    van Nieuwenburg, Evert P L; Huber, Sebastian D

    2016-01-01

    Classifying phases of matter is a central problem in physics. For quantum mechanical systems, this task can be daunting owing to the exponentially large Hilbert space. Thanks to the available computing power and access to ever larger data sets, classification problems are now routinely solved using machine learning techniques. Here, we propose to use a neural network based approach to find phase transitions depending on the performance of the neural network after training it with deliberately incorrectly labelled data. 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 a generic tool to identify unexplored phase transitions.

  18. Modulational instability of nematic phase

    Indian Academy of Sciences (India)

    T Mithun; K Porsezian

    2014-02-01

    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 field triggers the modulational instability and demonstrate that irrespective of the magnetic field effect the uniaxial and biaxial nematic phases show modulational instability.

  19. Phase structures in fuzzy geometries

    CERN Document Server

    Govindarajan, T R; Gupta, K S; Martin, X

    2012-01-01

    We study phase structures of quantum field theories in fuzzy geometries. Several examples of fuzzy geometries as well as QFT's on such geometries are considered. They are fuzzy spheres and beyond as well as noncommutative deformations of BTZ blackholes. Analysis is done analytically and through simulations. Several features like novel stripe phases as well as spontaneous symmetry breaking avoiding Colemen, Mermin, Wagner theorem are brought out. Also we establish that these phases are stable due to topological obstructions.

  20. Magnetic resonance of phase transitions

    CERN Document Server

    Owens, Frank J; Farach, Horacio A

    1979-01-01

    Magnetic Resonance of Phase Transitions shows how the effects of phase transitions are manifested in the magnetic resonance data. The book discusses the basic concepts of structural phase and magnetic resonance; various types of magnetic resonances and their underlying principles; and the radiofrequency methods of nuclear magnetic resonance. The text also describes quadrupole methods; the microwave technique of electron spin resonance; and the Mössbauer effect. Phase transitions in various systems such as fluids, liquid crystals, and crystals, including paramagnets and ferroelectrics, are also

  1. What Are Clinical Trial Phases?

    Medline Plus

    Full Text Available ... Phases of Clinical Trials Cancer Treatment Types of Cancer Treatment Surgery Radiation Therapy Chemotherapy Immunotherapy Targeted Therapy Hormone Therapy Stem Cell Transplant Precision ...

  2. 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.

  3. Phase retrieval with prior information.

    Science.gov (United States)

    Irwan, R; Lane, R G

    1998-09-01

    An algorithm for phase retrieval with Bayesian statistics is discussed. It is shown how the statistics of Kolmogorov turbulence can be used to compute the likelihood for a particular phase screen. This likelihood is then added to that of the observed data to produce a functional that is maximized directly by use of conjugate gradient maximization. It is shown that although this can significantly improve the quality of the phase estimate,the issue is complicated by local maxima introduced by the possibility of phase wrapping. The causes of the local maxima are analyzed, and a method that increases the likelihood of convergence to the global maximum is presented.

  4. Studies of novel deuterides RMn{sub 2}D{sub 6} (R - rare earth) compressed in DAC up to 30 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Filipek, S M; Wierzbicki, R [Institute of Physical Chemistry PAS., ul. Kasprzaka 44, 01-224 Warsaw (Poland); Sugiura, H [Graduate School of Integrated Sci., Yokohama City University, 22-2 Seta, Kanazawa-ku, Yokohama 236-0027 (Japan); Paul-Boncour, V [Chimie Metallurgique des Terres Rares, ICMPE, GLVT, 2-8 rue Henri Dunant, 94320 Thiais Cedex (France); Liu, R S; Bagkar, N [Department of Chemistry, National Taiwan University, Taipei 106, Taiwan (China)], E-mail: smf@ichf.edu.pl

    2008-07-15

    The exposure of RMn{sub 2} (C15 or C14 cubic Laves phase, where R = Y; Dy; Ho or Er) to high deuterium pressure leads to formation of novel, unique YMn{sub 2}D{sub 6}, DyMn{sub 2}D{sub 6}, HoMn{sub 2}D{sub 6} and ErMn{sub 2}D{sub 6} deuterides with cubic Fm-3m symmetry. In spite of different structures and molecular volumes of parent RMn{sub 2} compounds, the molar volumes of RMn{sub 2}D{sub 6} deuterides are almost identical. In this paper, we present results of studies on RMn{sub 2}Dx (where R = Y, Dy, Ho and Er) submitted to compression up to 30 GPa in diamond anvil cell (DAC) combined with energy dispersive X-ray diffraction. The EOS (equation of state) parameters of the above four RMn{sub 2}D{sub 6} samples and YMn{sub 2}D{sub x}, with x {<=} 4 are compared. The EOS parameters of YMn{sub 2}D{sub 6} are very similar to those of other RMn{sub 2}D{sub 6} but very different than those of interstitial deuterides YMn{sub 2}D{sub x} (x {<=} 4). The phase transition or segregation was not detected in RMn{sub 2}D{sub 6} up to 30 GPa.

  5. Condensed phase decomposition and gas phase combustion of hydrazinium nitroformate

    NARCIS (Netherlands)

    Dragomir, O.E.; Tummers, M.J.; Veen, E.H. van; Heijden, A.E.D.M. van der; Roekaerts, D.J.E.M.

    2009-01-01

    This paper presents the results of a series of experiments on the condensed phase decomposition and the gas phase combustion of hydrazinium nitroformate (HNF). The experiments include SEM analysis of quenched samples that showed evidence of the formation of a foam layer. FTIR spectrometry and mass s

  6. Sleep timing and circadian phase in delayed sleep phase syndrome.

    Science.gov (United States)

    Chang, Anne-Marie; Reid, Kathryn J; Gourineni, Ramadevi; Zee, Phyllis C

    2009-08-01

    Delayed sleep phase syndrome (DSPS) is a circadian rhythm sleep disorder in which the timing of the sleep episode occurs later than desired and is associated with difficulty falling asleep, problems awakening on time (e.g., to meet work or school obligations), and daytime sleepiness. The phase relationship between the timing of sleep and endogenous circadian rhythms is critical to the initiation and maintenance of sleep, and significant alteration leads to impairment of sleep quality and duration. The aim of this retrospective study was to determine the phase relationship between sleep-wake times and physiological markers of circadian timing in clinic patients with DSPS. Objective and subjective measures of sleep timing and circadian phase markers (core body temperature and melatonin) were measured in patients with DSPS and compared with age-matched controls. As expected, significant delays in the timing of the major sleep episode and circadian phase of body temperature and melatonin rhythms were seen in the DSPS group when allowed to sleep at their own habitual schedules, but the phase relationship between sleep-wake times and circadian phase was similar between the 2 groups. These results suggest that the symptoms of insomnia and excessive daytime sleepiness in DSPS patients living under entrained real-life conditions cannot be explained by an alteration in the phase relationship between sleep-wake patterns and other physiological circadian rhythms.

  7. 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...

  8. Topology in Ordered Phases

    Science.gov (United States)

    Tanda, Satoshi; Matsuyama, Toyoki; Oda, Migaku; Asano, Yasuhiro; Yakubo, Kousuke

    2006-08-01

    .]. Nanofibers of hydrogen storage alloy / I. Saita ... [et al.]. Synthesis of stable icosahedral quasicrystals in Zn-Sc based alloys and their magnetic properties / S. Kashimoto and T. Ishimasa. One-armed spiral wave excited by eam pressure in accretion disks in Be/X-Ray binaries / K. Hayasaki and A. T. Okazaki -- IV. Topological defects and excitations. Topological excitations in the ground state of charge density wave systems / P. Monceau. Soliton transport in nanoscale charge-density-wave systems / K. Inagaki, T. Toshima and S. Tanda. Topological defects in triplet superconductors UPt3, Sr[symbol]RuO[symbol], etc. / K. Maki ... [et al.]. Microscopic structure of vortices in type II superconductors / K. Machida ... [et al.]. Microscopic neutron investigation of the Abrikosov state of high-temperature superconductors / J. Mesot. Energy dissipation at nano-scale topological defects of high-Tc superconductors: microwave study / A. Maeda. Pressure induced topological phase transition in the heavy Fermion compound CeAl[symbol] / H. Miyagawa ... [et al.]. Explanation for the unusual orientation of LSCO square vortex lattice in terms of nodal superconductivity / M. Oda. Local electronic states in Bi[symbol]Sr[symbol]CaCu[symbol]O[symbol] / A. Hashimoto ... [et al.] -- V. Topology in quantum phenomena. Topological vortex formation in a Bose-Einstein condensate of alkali-metal atoms / M. Nakahara. Quantum phase transition of [symbol]He confined in nano-porous media / K. Shirahama, K. Yamamoto and Y. Shibayama. A new mean-field theory for Bose-Einstein condensates / T. Kita. Spin current in topological cristals / Y. Asano. Antiferromagnetic defects in non-magnetic hidden order of the heavy-electron system URu[symbol]Si[symbol] / H. Amitsuka, K. Tenya and M. Yokoyama. Magnetic-field dependences of thermodynamic quantities in the vortex state of Type-II superconductors / K. Watanabe, T. Kita and M. Arai. Three-magnon-mediated nuclear spin relaxation in quantum ferrimagnets of topological

  9. 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...... the MC and M23C6 carbides found in the as-received sample, the formation of α-W phase, α-Cr phase and Laves phase in crept samples were confirmed with scanning/transmission electron microscopes. Statistical quantitative image analysis was used to evaluate the precipitation behavior and growth kinetics...

  10. Oscillator With Low Phase Noise

    Science.gov (United States)

    Kleinberg, Leonard L.

    1987-01-01

    Phase errors cancelled for high frequency stability. Radio-frequency oscillator achieves high stability of frequency through parallel, two-amplifier configuration in which effects cause phase noise tend to cancel each other. Circuit includes two amplifiers with resonating elements, each constitutes part of feedback loop of other. Generate same frequency because each circuit provides other with conditions necessary for oscillation.

  11. 78 FR 33911 - Phased Retirement

    Science.gov (United States)

    2013-06-05

    ... knowledge and expertise with the next generation of Federal leaders via mentoring and role-modeling. Once... making an election of phased retirement, the procedures for electing phased retirement, the requirements... less than the 3-year period ending on the effective date of the employee's election of...

  12. Thermodynamic and kinetic modelling: creep resistant materials

    DEFF Research Database (Denmark)

    Hald, John; Korcakova, L.; Danielsen, Hilmar Kjartansson

    2008-01-01

    particles and coarsening of MX, M23C6 and Laves phase particles. The modelling provided new insight into the long term stability of new steels. Modelling of the detrimental precipitation of Z phase Cr(V,Nb)N is described, which points to new approaches in alloy development for higher temperatures......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...

  13. Microgravity Passive Phase Separator

    Science.gov (United States)

    Paragano, Matthew; Indoe, William; Darmetko, Jeffrey

    2012-01-01

    A new invention disclosure discusses a structure and process for separating gas from liquids in microgravity. The Microgravity Passive Phase Separator consists of two concentric, pleated, woven stainless- steel screens (25-micrometer nominal pore) with an axial inlet, and an annular outlet between both screens (see figure). Water enters at one end of the center screen at high velocity, eventually passing through the inner screen and out through the annular exit. As gas is introduced into the flow stream, the drag force exerted on the bubble pushes it downstream until flow stagnation or until it reaches an equilibrium point between the surface tension holding bubble to the screen and the drag force. Gas bubbles of a given size will form a front that is moved further down the length of the inner screen with increasing velocity. As more bubbles are added, the front location will remain fixed, but additional bubbles will move to the end of the unit, eventually coming to rest in the large cavity between the unit housing and the outer screen (storage area). Owing to the small size of the pores and the hydrophilic nature of the screen material, gas does not pass through the screen and is retained within the unit for emptying during ground processing. If debris is picked up on the screen, the area closest to the inlet will become clogged, so high-velocity flow will persist farther down the length of the center screen, pushing the bubble front further from the inlet of the inner screen. It is desired to keep the velocity high enough so that, for any bubble size, an area of clean screen exists between the bubbles and the debris. The primary benefits of this innovation are the lack of any need for additional power, strip gas, or location for venting the separated gas. As the unit contains no membrane, the transport fluid will not be lost due to evaporation in the process of gas separation. Separation is performed with relatively low pressure drop based on the large surface

  14. Quantum processes on phase space

    CERN Document Server

    Anastopoulos, C

    2003-01-01

    Quantum theory predicts probabilities as well as relative phases between different alternatives of the system. A unified description of both probabilities and phases comes through a generalisation of the notion of a density matrix for histories; this object is the decoherence functional of the consistent histories approach. If we take phases as well as probabilities as primitive elements of our theory, we abandon Kolmogorov probability and can describe quantum theory in terms of fundamental commutative observables, without being obstructed by Bell's and related theorems. Generalising the theory of stochastic processes, we develop the description of relative phases and probabilities for paths on the classical phase space. This description provides a theory of quantum processes. We identify a number of basic postulates and study its corresponding properties. We strongly emphasise the notion of conditioning and are able to write ``quantum differential equations'' as analogous to stochastic differential equations...

  15. Closed Orbits in Phase Space

    Science.gov (United States)

    Murphy, Andrew; Haestad, Jace; Morgan, Thomas

    2015-09-01

    We report characteristics of closed classical orbits in an electric field in phase space produced in photoabsorption. Rydberg states of atomic and molecular hydrogen and helium are considered. The core potential used for the hydrogen molecule is an effective one electron one center core potential evaluated at the internuclear equilibrium distance. Poincare surfaces of section in phase space are generated by integrating the equations of motion in semiparabolic coordinates u = (r + z) 1 / 2 and v = (r - z) 1 / 2, and plotting the location in phase space (pv versus v) whenever u = 0, with the electric field in the z direction. Combination orbits produced by Rydberg electron core scattering are studied and the evolution in phase space of these combination orbits due to scattering from one closed orbit into another is investigated. Connections are made to measured laser photoabsorption experiments that excite Rydberg states (20 recurrence spectra. The phase space structures responsible for the spectra are identified.

  16. Phases of Cannibal Dark Matter

    CERN Document Server

    Farina, Marco; Ruderman, Joshua T; Trevisan, Gabriele

    2016-01-01

    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 ...

  17. Nanoscale phase change memory materials.

    Science.gov (United States)

    Caldwell, Marissa A; Jeyasingh, Rakesh Gnana David; Wong, H-S Philip; Milliron, Delia J

    2012-08-01

    Phase change memory materials store information through their reversible transitions between crystalline and amorphous states. For typical metal chalcogenide compounds, their phase transition properties directly impact critical memory characteristics and the manipulation of these is a major focus in the field. Here, we discuss recent work that explores the tuning of such properties by scaling the materials to nanoscale dimensions, including fabrication and synthetic strategies used to produce nanoscale phase change memory materials. The trends that emerge are relevant to understanding how such memory technologies will function as they scale to ever smaller dimensions and also suggest new approaches to designing materials for phase change applications. Finally, the challenges and opportunities raised by integrating nanoscale phase change materials into switching devices are discussed.

  18. Inhomogeneous phase shifting: an algorithm for nonconstant phase displacements

    Energy Technology Data Exchange (ETDEWEB)

    Tellez-Quinones, Alejandro; Malacara-Doblado, Daniel

    2010-11-10

    In this work, we have developed a different algorithm than the classical one on phase-shifting interferometry. These algorithms typically use constant or homogeneous phase displacements and they can be quite accurate and insensitive to detuning, taking appropriate weight factors in the formula to recover the wrapped phase. However, these algorithms have not been considered with variable or inhomogeneous displacements. We have generalized these formulas and obtained some expressions for an implementation with variable displacements and ways to get partially insensitive algorithms with respect to these arbitrary error shifts.

  19. Phases in the active liquid phase methanol synthesis catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Sawant, A.V.; Lee, S.; Kulik, C.J.

    1988-01-01

    An attempt has been made to identify the phases present in the active catalyst for liquid phase methanol synthesis. X-ray powder diffraction was used to identify the phases. Only metallic Cu was detected, while no Cu/sup +/ species was found to be present. A significant amount of ZnCO/sub 3/ was found to be present in catalysts which had been subjected to high partial pressures of CO/sub 2/. This fact has hitherto not been reported in literature. Some speculations about the effect of ZnCO/sub 3/ on the life of the catalyst are made. 21 refs., 6 figs.

  20. Rapid turnover of hyphae of mycorrhizal fungi determined by AMS microanalysis of C-14

    OpenAIRE

    Staddon, P L; Ramsey, C. B.; Ostle, N.; Ineson, P.; Fitter, A H

    2003-01-01

    Processes in the soil remain among the least well-characterized components of the carbon cycle. Arbuscular mycorrhizal (AM) fungi are ubiquitous root symbionts in many terrestrial ecosystems and account for a large fraction of photosynthate in a wide range of ecosystems; they therefore play a key role in the terrestrial carbon cycle. A large part of the fungal mycelium is outside the root ( the extraradical mycelium, ERM) and, because of the dispersed growth pattern and the small diameter of ...

  1. 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.

  2. 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.

  3. 26 CFR 31.3306(c)(14)-1 - Services of insurance agent or solicitor.

    Science.gov (United States)

    2010-04-01

    ... performed for such person by such individual are performed for remuneration solely by way of commission. (b) If all or any part of the remuneration of an employee for services performed as an insurance agent or... insurance solicitor for such person are excepted from employment, and his total remuneration (for...

  4. ESR and AMS-based C-14 dating of Mousterian levels at Mujina Pecina, Dalmatia, Croatia

    NARCIS (Netherlands)

    Rink, WJ; Karavanic, [No Value; Pettitt, PB; Van der Plicht, J; Smith, FH; Bartoll, J

    2002-01-01

    This paper presents the first chronometric dates for sediments that contain a Mousterian industry in Dalmatia (south Croatia). Electron spin resonance (ESR) dating was conducted on two teeth from the Mousterian level E1 at the site of Mujina Pecina. Additionally five bone and one charcoal sample fro

  5. Uptake of C(14)-atrazine by prairie grasses in a phytoremediation setting.

    Science.gov (United States)

    Khrunyk, Yuliya; Schiewer, Silke; Carstens, Keri L; Hu, Dingfei; Coats, Joel R

    2017-02-01

    Agrochemicals significantly contribute to environmental pollution. In the USA, atrazine is a widely used pesticide and commonly found in rivers, water systems, and rural wells. Phytoremediation can be a cost-effective means of removing pesticides from soil. The objective of this project was to investigate the ability of prairie grasses to remove atrazine. (14)C-labeled atrazine was added to sterilized sand and water/nutrient cultures, and the analysis was performed after 21 days. Switchgrass and big bluestem were promising species for phytoremediation, taking up about 40% of the applied [(14)C] in liquid hydroponic cultures, and between 20% and 33% in sand cultures. Yellow Indiangrass showed low resistance to atrazine toxicity and low uptake of [(14)C] atrazine in liquid hydroponic cultures. Atrazine degradation increased progressively from sand to roots and leaves. Most atrazine taken up by prairie grasses from sand culture was degraded to metabolites, which accounted for 60-80% of [(14)C] detected in leaves. Deisopropylatrazine (DIA) was the main metabolite detected in sand and roots, whereas in leaves further metabolism took place, forming increased amounts of didealkylatrazine (DDA) and an unidentified metabolite. In conclusion, prairie grasses achieved high atrazine removal and degradation, showing a high potential for phytoremediation.

  6. 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).

  7. Optimization of Sealed Tube Graphitization Method for Environmental C-14 Studies Using MICADAS

    Energy Technology Data Exchange (ETDEWEB)

    Rinyu, Laszlo, E-mail: rinyu@atomki.hu [Hertelendi Laboratory of Environmental Studies, Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), H-4026 Debrecen (Hungary); Isotoptech Zrt., H-4025 Debrecen (Hungary); Molnar, Mihaly [Hertelendi Laboratory of Environmental Studies, Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), H-4026 Debrecen (Hungary); Ion Beam Physics, ETH Zuerich, CH-8093 Zuerich (Switzerland); Major, Istvan [Hertelendi Laboratory of Environmental Studies, Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), H-4026 Debrecen (Hungary); Nagy, Tamas; Veres, Mihaly [Isotoptech Zrt., H-4025 Debrecen (Hungary); Kimak, Adam [University of Debrecen, H-4032 Debrecen (Hungary); Wacker, Lukas; Synal, Hans-Arno [Ion Beam Physics, ETH Zuerich, CH-8093 Zuerich (Switzerland)

    2013-01-15

    The original sealed tube zinc reduction graphitization process was first developed for rapid low-precision measurements of biomedical tracer samples and later also applied for high precision measurements of not too old samples. In this study we tested the MICADAS (mini radiocarbon dating system [1]) radiocarbon measurements of targets prepared by sealed tube graphitization process. We found the optimal iron catalyst and reagents (TiH{sub 2} and Zn) amount whereby we can reach a relatively low background level, and minimized the overall {delta}{sup 13}C fractionation during the graphitization. Repeated measurements of normalization standards and real samples with known {sup 14}C activities were very well reproduced. Finally, we demonstrated the applicability of the sealed tube graphitization on real environmental samples covering a wide range of {sup 14}C concentrations.

  8. 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.

  9. Early Bronze Jericho : High-precision C-14 dates of short-lived palaeobotanic remains

    NARCIS (Netherlands)

    Bruins, HJ; Van Der Plicht, J; Mook, W.G.

    1998-01-01

    Reliable series of high-precision radiocarbon dates in a stratified archaeological context are of great importance for interdisciplinary chronological and historical studies. The Early Bronze Age in the Near East is characterized by the beginning of the great civilizations in Egypt and Mesopotamia,

  10. Phase appearance or disappearance in two-phase flows

    CERN Document Server

    Cordier, Floraine; Kumbaro, Anela

    2011-01-01

    This paper is devoted to the treatment of specific numerical problems which appear when phase appearance or disappearance occurs in models of two-phase flows. Such models have crucial importance in many industrial areas such as nuclear power plant safety studies. In this paper, two outstanding problems are identified: first, the loss of hyperbolicity of the system when a phase appears or disappears and second, the lack of positivity of standard shock capturing schemes such as the Roe scheme. After an asymptotic study of the model, this paper proposes accurate and robust numerical methods adapted to the simulation of phase appearance or disappearance. Polynomial solvers are developed to avoid the use of eigenvectors which are needed in usual shock capturing schemes, and a method based on an adaptive numerical diffusion is designed to treat the positivity problems. An alternate method, based on the use of the hyperbolic tangent function instead of a polynomial, is also considered. Numerical results are presente...

  11. Phase Noise in Photonic Phased-Array Antenna Systems

    Science.gov (United States)

    Logan, Ronald T., Jr.; Maleki, Lute

    1998-01-01

    The total noise of a phased-array antenna system employing a photonic feed network is analyzed using a model for the individual component noise including both additive and multiplicative equivalent noise generators.

  12. 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

    This paper presents a new method to measure the phase dependent impedance from an experimental set up. Though most of power electronics based system is gradually migrating to IGBT based voltage source converter due to their controllability, the rectifier composed of diode or thyristor components...... 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...... application. It is found that the phase dependent impedance shows different properties with the impedance profiles, which have been proposed in the research. This paper explains a method to measure the phase dependent impedance profile from an experimental set up. Furthermore, the results are compared...

  13. Phase shift estimation in interferograms with unknown phase step

    Science.gov (United States)

    Dalmau, Oscar; Rivera, Mariano; Gonzalez, Adonai

    2016-08-01

    We first present two closed formulas for computing the phase shift in interferograms with unknown phase step. These formulas obtain theoretically the exact phase step in fringe pattern without noise and only require the information in two pixels of the image. The previous formulas allows us to define a functional that yields an estimate of the phase step in interferograms corrupted by noise. In the experiment we use the standard Least Square formulation which also yields a closed formula, although the general formulation admits a robust potential. We provide two possible implementations of our approach, one in which the sites can be randomly selected and the other in which we can scan the whole image. The experiments show that the proposed algorithm presents the best results compared with state of the art algorithms.

  14. An absorbing phase transition from a structured active particle phase

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Cristobal [Instituto Mediterraneo de Estudios Avanzados IMEDEA (CSIC-UIB), Campus de la Universidad de las Islas Baleares, E-07122 Palma de Mallorca (Spain); Ramos, Francisco [Departamento de Electromagnetismo y Fisica de la Materia and Instituto de Fisica Teorica y Computacional Carlos I, Facultad de Ciencias, Universidad de Granada, 18071 Granada (Spain); Hernandez-GarcIa, Emilio [Instituto Mediterraneo de Estudios Avanzados IMEDEA (CSIC-UIB), Campus de la Universidad de las Islas Baleares, E-07122 Palma de Mallorca (Spain)

    2007-02-14

    In this work we study the absorbing state phase transition of a recently introduced model for interacting particles with neighbourhood-dependent reproduction rates. The novelty of the transition is that as soon as the active phase is reached by increasing a control parameter a periodically arranged structure of particle clusters appears. A numerical study in one and two dimensions shows that the system falls into the directed percolation universality class.

  15. 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

  16. SLEEP TIMING AND CIRCADIAN PHASE IN DELAYED SLEEP PHASE

    OpenAIRE

    2009-01-01

    Delayed sleep phase syndrome (DSPS) is a circadian rhythm sleep disorder in which the timing of the sleep episode occurs later than desired and is associated with difficulty falling asleep, problems awakening on time (e.g., to meet work or school obligations), and daytime sleepiness. The phase relationship between the timing of sleep and endogenous circadian rhythms is critical to the initiation and maintenance of sleep, and significant alteration leads to impairment of sleep quality and dura...

  17. 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....

  18. GPC and quantitative phase imaging

    DEFF Research Database (Denmark)

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

    2016-01-01

    Generalized Phase Contrast (GPC) is a light efficient method for generating speckle-free contiguous optical distributions using binary-only or analog phase levels. It has been used in applications such as optical trapping and manipulation, active microscopy, structured illumination, optical...... 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...

  19. 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

  20. Mixed Frequency Ultrasound Phased Array

    Institute of Scientific and Technical Information of China (English)

    香勇; 霍健; 施克仁; 陈以方

    2004-01-01

    A mixed frequency ultrasonic phased array (MPA) was developed to improve the focus, in which the element excitation frequencies are not all the same as in a normal constant frequency phased array. A theoretical model of the mixed frequency phased array based on the interference principle was used to simulate the array's sound distribution. The pressure intensity in the array focal area was enhanced and the scanning area having effective contrast resolution was enlarged. The system is especially useful for high intensity focused ultrasound (HIFU) with more powerful energy and ultrasound imaging diagnostics with improved signal to noise ratios, improved beam forming and more uniform imaging quality.

  1. 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.

  2. 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....... Generalized Weyl-Wigner maps related to the notion of Hamiltonian weight are studied and used in the formulation of a twisted spectral theory for functions on phase space. Some inequalities for Wigner functions on phase space are proven. A brief discussion of the classical limit obtained through dilations...

  3. Geometrical Phases in Quantum Mechanics

    Science.gov (United States)

    Christian, Joy Julius

    In quantum mechanics, the path-dependent geometrical phase associated with a physical system, over and above the familiar dynamical phase, was initially discovered in the context of adiabatically changing environments. Subsequently, Aharonov and Anandan liberated this phase from the original formulation of Berry, which used Hamiltonians, dependent on curves in a classical parameter space, to represent the cyclic variations of the environments. Their purely quantum mechanical treatment, independent of Hamiltonians, instead used the non-trivial topological structure of the projective space of one-dimensional subspaces of an appropriate Hilbert space. The geometrical phase, in their treatment, results from a parallel transport of the time-dependent pure quantum states along a curve in this space, which is endowed with an abelian connection. Unlike Berry, they were able to achieve this without resort to an adiabatic approximation or to a time-independent eigenvalue equation. Prima facie, these two approaches are conceptually quite different. After a review of both approaches, an exposition bridging this apparent conceptual gap is given; by rigorously analyzing a model composite system, it is shown that, in an appropriate correspondence limit, the Berry phase can be recovered as a special case from the Aharonov-Anandan phase. Moreover, the model composite system is used to show that Berry's correction to the traditional Born-Oppenheimer energy spectra indeed brings the spectra closer to the exact results. Then, an experimental arrangement to measure geometrical phases associated with cyclic and non-cyclic variations of quantum states of an entangled composite system is proposed, utilizing the fundamental ideas of the recently opened field of two-particle interferometry. This arrangement not only resolves the controversy regarding the true nature of the phases associated with photon states, but also unequivocally predicts experimentally accessible geometrical phases in a

  4. Review: Acute phase reaction and acute phase proteins

    Institute of Scientific and Technical Information of China (English)

    GRUYS E.; TOUSSAINT M.J.M.; NIEWOLD T.A.; KOOPMANS S.J.

    2005-01-01

    A review of the systemic acute phase reaction with major cytokines involved, and the hepatic metabolic changes,negative and positive acute phase proteins (APPs) with function and associated pathology is given. It appears that APPs represent appropriate analytes for assessment of animal health. Whereas they represent non-specific markers as biological effect reactants,they can be used for assessing nutritional deficits and reactive processes, especially when positive and negative acute phase variables are combined in an index. When such acute phase index is applied to separate healthy animals from animals with some disease, much better results are obtained than with single analytes and statistically acceptable results for culling individual animals may be reached.Unfortunately at present no cheap, comprehensive and easy to use system is available for assessing various acute phase proteins in serum or blood samples at the same time. Protein microarray or fluid phase microchip technology may satisfy this need;and permit simultaneous analysis of numerous analytes in the same small volume sample and enable integration of information derived from systemic reactivity and nutrition with disease specific variables. Applying such technology may help to solve health problems in various countries not only in animal husbandry but also in human populations.

  5. Phase diagrams and kinetics of phase transitions in protein solutions.

    Science.gov (United States)

    Vekilov, Peter G

    2012-05-16

    The phase behavior of proteins is of interest for fundamental and practical reasons. The nucleation of new phases is one of the last major unresolved problems of nature. The formation of protein condensed phases (crystals, polymers, and other solid aggregates, as well as dense liquids and gels) underlies pathological conditions, plays a crucial role in the biological function of the respective protein, or is an essential part of laboratory and industrial processes. In this review, we focus on phase transitions of proteins in their properly folded state. We first summarize the recently acquired understanding of physical processes underlying the phase diagrams of the protein solutions and the thermodynamics of protein phase transitions. Then we review recent findings on the kinetics of nucleation of dense liquid droplets and crystals. We explore the transition from nucleation to spinodal decomposition for liquid-liquid separation and introduce the new concept of solution-to-crystal spinodal. We review the two-step mechanism of protein crystal nucleation, in which mesoscopic metastable protein clusters serve as precursors to the ordered crystal nuclei. The concepts and mechanisms reviewed here provide powerful tools for control of the nucleation process by varying the solution thermodynamic parameters.

  6. Numerical methods for phase retrieval

    CERN Document Server

    Osherovich, Eliyahu

    2012-01-01

    In this work we consider the problem of reconstruction of a signal from the magnitude of its Fourier transform, also known as phase retrieval. The problem arises in many areas of astronomy, crystallography, optics, and coherent diffraction imaging (CDI). Our main goal is to develop an efficient reconstruction method based on continuous optimization techniques. Unlike current reconstruction methods, which are based on alternating projections, our approach leads to a much faster and more robust method. However, all previous attempts to employ continuous optimization methods, such as Newton-type algorithms, to the phase retrieval problem failed. In this work we provide an explanation for this failure, and based on this explanation we devise a sufficient condition that allows development of new reconstruction methods---approximately known Fourier phase. We demonstrate that a rough (up to $\\pi/2$ radians) Fourier phase estimate practically guarantees successful reconstruction by any reasonable method. We also pres...

  7. Phase retrieval in protein crystallography.

    Science.gov (United States)

    Liu, Zhong Chuan; Xu, Rui; Dong, Yu Hui

    2012-03-01

    Solution of the phase problem is central to crystallographic structure determination. An oversampling method is proposed, based on the hybrid input-output algorithm (HIO) [Fienup (1982). Appl. Opt. 21, 2758-2769], to retrieve the phases of reflections in crystallography. This method can extend low-resolution structures to higher resolution for structure determination of proteins without additional sample preparation. The method requires an envelope of the protein which divides a unit cell into the density region where the proteins are located and the non-density region occupied by solvents. After a few hundred to a few thousand iterations, the correct phases and density maps are recovered. The method has been used successfully in several cases to retrieve the phases from the experimental X-ray diffraction data and the envelopes of proteins constructed from structure files downloaded from the Protein Data Bank. It is hoped that this method will greatly facilitate the ab initio structure determination of proteins.

  8. 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...

  9. Berry phase in Heisenberg representation

    Science.gov (United States)

    Andreev, V. A.; Klimov, Andrei B.; Lerner, Peter B.

    1994-01-01

    We define the Berry phase for the Heisenberg operators. This definition is motivated by the calculation of the phase shifts by different techniques. These techniques are: the solution of the Heisenberg equations of motion, the solution of the Schrodinger equation in coherent-state representation, and the direct computation of the evolution operator. Our definition of the Berry phase in the Heisenberg representation is consistent with the underlying supersymmetry of the model in the following sense. The structural blocks of the Hamiltonians of supersymmetrical quantum mechanics ('superpairs') are connected by transformations which conserve the similarity in structure of the energy levels of superpairs. These transformations include transformation of phase of the creation-annihilation operators, which are generated by adiabatic cyclic evolution of the parameters of the system.

  10. 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.

  11. 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.

  12. Solid-Phase Random Glycosylation

    DEFF Research Database (Denmark)

    Agoston, K.; Kröger, Lars; Dekany, Gyula;

    2009-01-01

    Two different approaches were employed to study solid phase random glycosylations to obtain oligosaccharide libraries. In approach I, Wang resin esters were attached to the acceptors structures. Following their glycosylation and resin cleavage, the peracetylated components of the oligosaccharide ...

  13. 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.

  14. 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.

  15. Berry's Phase in Noncommutative Spaces

    Institute of Scientific and Technical Information of China (English)

    S. A. Alavi

    2003-01-01

    We discuss the perturbative aspects of noncommutative quantum mechanics. Then we study Berry's phase within the framework of noncommutative quantum mechanics. The results show deviations from the usual quantum mechanics, which depend on the parameter of space/space noncommutativity.

  16. Safety performance of traffic phases and phase transitions in three phase traffic theory.

    Science.gov (United States)

    Xu, Chengcheng; Liu, Pan; Wang, Wei; Li, Zhibin

    2015-12-01

    Crash risk prediction models were developed to link safety to various phases and phase transitions defined by the three phase traffic theory. Results of the Bayesian conditional logit analysis showed that different traffic states differed distinctly with respect to safety performance. The random-parameter logit approach was utilized to account for the heterogeneity caused by unobserved factors. The Bayesian inference approach based on the Markov Chain Monte Carlo (MCMC) method was used for the estimation of the random-parameter logit model. The proposed approach increased the prediction performance of the crash risk models as compared with the conventional logit model. The three phase traffic theory can help us better understand the mechanism of crash occurrences in various traffic states. The contributing factors to crash likelihood can be well explained by the mechanism of phase transitions. We further discovered that the free flow state can be divided into two sub-phases on the basis of safety performance, including a true free flow state in which the interactions between vehicles are minor, and a platooned traffic state in which bunched vehicles travel in successions. The results of this study suggest that a safety perspective can be added to the three phase traffic theory. The results also suggest that the heterogeneity between different traffic states should be considered when estimating the risks of crash occurrences on freeways.

  17. Berry phase in lattice QCD

    CERN Document Server

    Yamamoto, Arata

    2016-01-01

    We propose the lattice QCD calculation of the Berry phase which is defined by the ground state of a single fermion. We perform the ground-state projection of a single-fermion propagator, construct the Berry link variable on a momentum-space lattice, and calculate the Berry phase. As the first application, the first Chern number of the (2+1)-dimensional Wilson fermion is calculated by the Monte Carlo simulation.

  18. Mindset theory of action phases

    OpenAIRE

    Gollwitzer, Peter

    2012-01-01

    Mindset theory of action phases is based on the distinction between motivation and volition as proposed by the Rubicon model which claims that prior to crossing the Rubicon (i.e., making a goal decision) motivational principles apply whereas thereafter volitional principles set in. The latter are concerned with goal implementation, whereas the former relate to the choosing of goals. Mindset theory of action phases proposes that different cognitive procedures are activated when people tackle t...

  19. Electroweak phase transition in technicolor

    CERN Document Server

    Jarvinen, Matti

    2010-01-01

    Several phenomenologically viable walking technicolor models have been proposed recently. I demonstrate that these models can have first order electroweak phase transitions, which are sufficiently strong for electroweak baryogenesis. Strong dynamics can also lead to several separate transitions at the electroweak scale, with the possibility of a temporary restoration and an extra breaking of the electroweak symmetry. First order phase transitions will produce gravitational waves, which may be detectable at future experiments.

  20. 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.

  1. Geometric phases in graphitic cones

    Energy Technology Data Exchange (ETDEWEB)

    Furtado, Claudio [Departamento de Fisica, CCEN, Universidade Federal da Paraiba, Cidade Universitaria, 58051-970 Joao Pessoa, PB (Brazil)], E-mail: furtado@fisica.ufpb.br; Moraes, Fernando [Departamento de Fisica, CCEN, Universidade Federal da Paraiba, Cidade Universitaria, 58051-970 Joao Pessoa, PB (Brazil); Carvalho, A.M. de M [Departamento de Fisica, Universidade Estadual de Feira de Santana, BR116-Norte, Km 3, 44031-460 Feira de Santana, BA (Brazil)

    2008-08-04

    In this Letter we use a geometric approach to study geometric phases in graphitic cones. The spinor that describes the low energy states near the Fermi energy acquires a phase when transported around the apex of the cone, as found by a holonomy transformation. This topological result can be viewed as an analogue of the Aharonov-Bohm effect. The topological analysis is extended to a system with n cones, whose resulting configuration is described by an effective defect00.

  2. Stochastic phase-change neurons

    Science.gov (United States)

    Tuma, Tomas; Pantazi, Angeliki; Le Gallo, Manuel; Sebastian, Abu; Eleftheriou, Evangelos

    2016-08-01

    Artificial neuromorphic systems based on populations of spiking neurons are an indispensable tool in understanding the human brain and in constructing neuromimetic computational systems. To reach areal and power efficiencies comparable to those seen in biological systems, electroionics-based and phase-change-based memristive devices have been explored as nanoscale counterparts of synapses. However, progress on scalable realizations of neurons has so far been limited. Here, we show that chalcogenide-based phase-change materials can be used to create an artificial neuron in which the membrane potential is represented by the phase configuration of the nanoscale phase-change device. By exploiting the physics of reversible amorphous-to-crystal phase transitions, we show that the temporal integration of postsynaptic potentials can be achieved on a nanosecond timescale. Moreover, we show that this is inherently stochastic because of the melt-quench-induced reconfiguration of the atomic structure occurring when the neuron is reset. We demonstrate the use of these phase-change neurons, and their populations, in the detection of temporal correlations in parallel data streams and in sub-Nyquist representation of high-bandwidth signals.

  3. Phase Diagrams of Nuclear Pasta

    Science.gov (United States)

    Caplan, Matthew; Horowitz, Chuck; Berry, Don; da Silva Schneider, Andre

    2016-03-01

    In the inner crust of neutrons stars, where matter is near the saturation density, protons and neutrons arrange themselves into complex structures called nuclear pasta. Early theoretical work predicted a simple graduated hierarchy of pasta phases, consisting of spheres, cylinders, slabs, and uniform matter with voids. Previous work has simulated these phases with a simple classical model and has shown that the formation of these structures is dependent on the temperature, density, and proton fraction. However, previous work only studied a limited range of these parameters due to computational limitations. Thanks to recent advances in computing it is now possible to survey the structure of nuclear pasta for a larger range of parameters. By simulating nuclear pasta with constant temperature and proton fraction in an expanding simulation volume we are able to study the phase transitions in nuclear pasta, and thus produce a set of phase diagrams. We report on these phase diagrams as well as newly identified phases of nuclear pasta and discuss their implications for neutron star observables.

  4. Phase retrieval from speckle images.

    Science.gov (United States)

    Rondeau, Xavier; Thiébaut, Eric; Tallon, Michel; Foy, Renaud

    2007-10-01

    In ground-based astronomy, the inverse problem of phase retrieval from speckle images is a means to calibrate static aberrations for correction by active optics. It can also be used to sense turbulent wavefronts. However, the number of local minima drastically increases with the turbulence strength, mainly because of phase wrapping ambiguities. Multifocal phase diversity has been considered to overcome some ambiguities of the phase retrieval problem. We propose an effective algorithm for phase retrieval from a single focused image. Our algorithm makes use of a global optimization strategy and an automatically tuned smoothness prior to overcome local minima and phase degeneracies. We push the limit of D/r(0)=4 achieved by Irwan and Lane [J. Opt. Soc. Am. A.15, 2302 (1998)] up to D/r(0)=11, which is a major improvement owing to the drastic increase in the problem complexity. We estimate the performances of our approach from consistent simulations for different turbulence strengths and noise levels (down to 1500 photons per image). We also investigate the benefit of temporal correlation.

  5. Observing SU(2) phases with neutrons

    Indian Academy of Sciences (India)

    Veer Chand Rakhecha; Apoorva G Wagh

    2001-02-01

    We present an overview of polarized neutron experiments observing SU(2) phases. The first experimental separation of geometric and dynamical phases, the explicit verification of Pauli anticommutation and the first observation of interference amplitudes and phases in noncyclic evolutions are described. These experiments elucidate the physics of phases and phase jumps propounded by the Pancharatnam connection.

  6. Long Term Sunspot Cycle Phase Coherence with Periodic Phase Disruptions

    CERN Document Server

    Pease, Gerald E

    2016-01-01

    In 1965 Paul D. Jose published his discovery that both the motion of the Sun about the center of mass of the solar system and periods comprised of eight Hale magnetic sunspot cycles with a mean period of ~22.375 years have a matching periodicity of ~179 years. We have investigated the implied link between solar barycentric torque cycles and sunspot cycles and have found that the unsigned solar torque values from 1610 to 2058 are consistently phase and magnitude coherent in ~179 year Jose Cycles. We are able to show that there is also a surprisingly high degree of sunspot cycle phase coherence for times of minima in addition to magnitude correlation of peaks between the nine Schwabe sunspot cycles of 1878 through 1976 (SC12 through SC20) and those of 1699 through 1797 (SC[-5] through SC4). We further identify subsequent subcycles of predominantly non-coherent sunspot cycle phase. In addition we have analyzed the empirical solar motion triggers of both sunspot cycle phase coherence and phase coherence disruptio...

  7. Monodomain Blue Phase Liquid Crystal Layers for Phase Modulation

    Science.gov (United States)

    Oton, E.; Netter, E.; Nakano, T.; D.-Katayama, Y.; Inoue, F.

    2017-03-01

    Liquid crystal “Blue Phases” (BP) have evolved, in the last years, from a scientific curiosity to emerging materials for new photonic and display applications. They possess attractive features over standard nematic liquid crystals, like submillisecond switching times and polarization- independent optical response. However, BPs still present a number of technical issues that prevent their use in practical applications: their phases are only found in limited temperature ranges, thus requiring stabilization of the layers; stabilized BP layers are inhomogeneous and not uniformly oriented, which worsen the optical performance of the devices. It would be essential for practical uses to obtain perfectly aligned and oriented monodomain BP layers, where the alignment and orientation of the cubic lattice are organized in a single 3D structure. In this work we have obtained virtually perfect monodomain BP layers and used them in devices for polarization independent phase modulation. We demonstrate that, under applied voltage, well aligned and oriented layers generate smoother and higher values of the phase shift than inhomogeneous layers, while preserving polarization independency. All BP devices were successfully stabilized in BPI phase, maintaining the layer monodomain homogeneity at room temperature, covering the entire area of the devices with a unique BP phase.

  8. Monodomain Blue Phase Liquid Crystal Layers for Phase Modulation

    Science.gov (United States)

    Oton, E.; Netter, E.; Nakano, T.; D.-Katayama, Y.; Inoue, F.

    2017-01-01

    Liquid crystal “Blue Phases” (BP) have evolved, in the last years, from a scientific curiosity to emerging materials for new photonic and display applications. They possess attractive features over standard nematic liquid crystals, like submillisecond switching times and polarization- independent optical response. However, BPs still present a number of technical issues that prevent their use in practical applications: their phases are only found in limited temperature ranges, thus requiring stabilization of the layers; stabilized BP layers are inhomogeneous and not uniformly oriented, which worsen the optical performance of the devices. It would be essential for practical uses to obtain perfectly aligned and oriented monodomain BP layers, where the alignment and orientation of the cubic lattice are organized in a single 3D structure. In this work we have obtained virtually perfect monodomain BP layers and used them in devices for polarization independent phase modulation. We demonstrate that, under applied voltage, well aligned and oriented layers generate smoother and higher values of the phase shift than inhomogeneous layers, while preserving polarization independency. All BP devices were successfully stabilized in BPI phase, maintaining the layer monodomain homogeneity at room temperature, covering the entire area of the devices with a unique BP phase. PMID:28281691

  9. Experimental study of the phase equilibria in the Mg–Zn–Ag ternary system at 300 °C

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jian, E-mail: jian.wang@polymtl.ca [Center for Research in Computational Thermochemistry (CRCT), Department of Chemical Engineering, École Polytechnique, Montréal, Québec H3C 3A7 (Canada); Zhang, Yi-Nan [Department of Mechanical Engineering, Concordia University, 1455 De Maisonneuve Blvd. West, Montreal, Quebec H3G 1M8 (Canada); Hudon, Pierre; Jung, In-Ho [Department of Mining and Materials Engineering, McGill University, 3610 University Street, Montreal, Quebec H3A 0C5 (Canada); Medraj, Mamoun [Department of Mechanical Engineering, Concordia University, 1455 De Maisonneuve Blvd. West, Montreal, Quebec H3G 1M8 (Canada); Department of Mechanical and Materials Engineering, Masdar Institute, Masdar City, P.O. Box 54224, Abu Dhabi (United Arab Emirates); Chartrand, Patrice [Center for Research in Computational Thermochemistry (CRCT), Department of Chemical Engineering, École Polytechnique, Montréal, Québec H3C 3A7 (Canada)

    2015-08-05

    Highlights: • The phase equilibria of Mg–Zn–Ag system at 300 °C were determined. • A bcc continuous ternary solid solution forms between MgAg (bcc-B2) and AgZn (bcc-A2) was determined. • The extended solid solubilities of the sub-binary compounds were also determined. - Abstract: The phase equilibria in the Mg–Zn–Ag ternary system at 300 °C were investigated using three diffusion couples and 35 key samples. Scanning electron microscopy (SEM) equipped with energy-dispersive spectroscope (EDS) and X-ray diffraction (XRD) techniques were used for homogeneity ranges and crystal structure determination. Large solid solubility limits, due to substitution among Mg, Zn and Ag atoms in Mg{sub 3}Ag and MgZn{sub 2} phases, were observed in the present work. Solid solubility limits of Ag and Zn in the hcp (Mg) phase were found to be less than 1 at.%. The extended solid solubilities of the Mg{sub 12}Zn{sub 13}, Mg{sub 2}Zn{sub 3}, MgZn{sub 2} (C14), Mg{sub 2}Zn{sub 11}, Ag{sub 5}Zn{sub 8} and hcp (AgZn{sub 3}) sub-binary compounds were also determined in the Mg–Zn–Ag ternary system. In addition, a bcc continuous ternary solid solution forms between MgAg (bcc-B2) and AgZn (bcc-A2) at 300 °C.

  10. Studies of novel deuterides RMn2D6 (R — rare earth) compressed in DAC up to 30 GPa

    Science.gov (United States)

    Filipek, S. M.; Sugiura, H.; Paul-Boncour, V.; Wierzbicki, R.; Liu, R. S.; Bagkar, N.

    2008-07-01

    The exposure of RMn2 (C15 or C14 cubic Laves phase, where R = Y; Dy; Ho or Er) to high deuterium pressure leads to formation of novel, unique YMn2D6, DyMn2D6, HoMn2D6 and ErMn2D6 deuterides with cubic Fm-3m symmetry. In spite of different structures and molecular volumes of parent RMn2 compounds, the molar volumes of RMn2D6 deuterides are almost identical. In this paper, we present results of studies on RMn2Dx (where R = Y, Dy, Ho and Er) submitted to compression up to 30 GPa in diamond anvil cell (DAC) combined with energy dispersive X-ray diffraction. The EOS (equation of state) parameters of the above four RMn2D6 samples and YMn2Dx, with x RMn2D6 but very different than those of interstitial deuterides YMn2Dx (x RMn2D6 up to 30 GPa.

  11. Mechanical, thermal, and physical properties of Mg-Ca compounds in the framework of the modified embedded-atom method.

    Science.gov (United States)

    Groh, Sébastien

    2015-02-01

    Interatomic potentials for pure Ca and the Mg-Ca binary have been developed in the framework of the second nearest-neighbors modified embedded-atom method (MEAM). The validity and the transferability of the Ca MEAM potential was performed by calculating physical, mechanical, and thermal properties. These properties were compared to experimental data and numerical data obtained from existing Ca potentials, and a good agreement was found. In addition, the dissociation of the edge dislocation into two Shockley partials aligns with the linear elasticity solution. Furthermore, the velocity of an edge dislocation under static and dynamics loading conditions predicted in Ca using the MEAM formalism reproduces the expected behavior of an edge dislocation in fcc crystal structures. The Ca MEAM potential was then coupled to an existing Mg MEAM potential to describe the properties of the Mg-Ca alloys. Heat of formation, structural energy difference, and elastic constants were calculated for several ordered Mg-Ca compounds containing different concentrations of Ca. As expected from first-principle calculations based on DFT, Mg2Ca with the Laves phase C14 was found to be the most stable structure with the lowest heat of formation compared to compounds with other Ca concentrations (Mg3Ca, MgCa, and MgCa3). Moreover, the mechanical stability was recovered for the different tested compounds and is in agreement with first-principle data.

  12. Magnetic order in ?

    Science.gov (United States)

    Crook, M. R.; Coles, B. R.; Ritter, C.; Cywinski, R.

    1996-10-01

    Neutron powder diffraction has been used to study the evolution of magnetic order with increasing Zr substitution in the C14 Laves phase compounds 0953-8984/8/41/022/img8. For compounds with x = 0.3 and x = 0.4 we find a simple antiferromagnetic structure, similar to that reported for isostructural 0953-8984/8/41/022/img9. In this structure the Fe moments at the 6h sites are aligned along the c-axis, ferromagnetically coupled within the a - b plane, with adjacent planes antiferromagnetically coupled. This spin structure results in a cancellation of the molecular field at the interplanar 2a sites, and the Fe atoms at these sites carry no ordered moment. The neutron diffraction measurements on 0953-8984/8/41/022/img10 compounds in the composition range 0953-8984/8/41/022/img11 provide evidence of a low-temperature spin-canted structure in which the antiferromagnetic structure described above is modified by the appearance of a basal-plane ferromagnetic component which in turn leads to a small ordered Fe moment at the 2a site. The temperature dependence of the staggered magnetization in the antiferromagnetic state of the x = 0.4 compounds is found to closely follow the form 0953-8984/8/41/022/img12, as predicted for weak itinerant antiferromagnets by SCR spin-fluctuation theory.

  13. 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.

  14. Phase-Locked Loop Noise Reduction via Phase Detector Implementation for Single-Phase Systems

    Energy Technology Data Exchange (ETDEWEB)

    Thacker, Timothy [Virginia Polytechnic Institute and State University (Virginia Tech); Boroyevich, Dushan [Virginia Polytechnic Institute and State University (Virginia Tech); Burgos, Rolando [ABB; Wang, Fei [ORNL

    2011-01-01

    A crucial component of grid-connected converters is the phase-locked loop (PLL) control subsystem that tracks the grid voltage's frequency and phase angle. Therefore, accurate fast-responding PLLs for control and protection purposes are required to provide these measurements. This paper proposes a novel feedback mechanism for single-phase PLL phase detectors using the estimated phase angle. Ripple noise appearing in the estimated frequency, most commonly the second harmonic under phase-lock conditions, is reduced or eliminated without the use of low-pass filters, which can cause delays to occur and limits the overall performance of the PLL response to dynamic changes in the system. The proposed method has the capability to eliminate the noise ripple entirely and, under extreme line distortion conditions, can reduce the ripple by at least half. Other modifications implemented through frequency feedback are shown to decrease the settling time of the PLL up to 50%. Mathematical analyses with the simulated and experimental results are provided to confirm the validity of the proposed methods.

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

    DEFF Research Database (Denmark)

    Madsen, Søren; Veje, Christian; Willatzen, Morten

    2012-01-01

    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...

  16. Treating Chronic Myeloid Leukemia by Phase

    Science.gov (United States)

    ... Myeloid Leukemia (CML) Treating Chronic Myeloid Leukemia Treating Chronic Myeloid Leukemia by Phase Treatment options for people ... a stem cell donor with matching tissue type. Chronic phase The standard treatment for chronic phase CML ...

  17. Noise-induced synchronization for phase turbulence

    OpenAIRE

    Sakaguchi, H.

    2003-01-01

    Phase turbulence is suppressed by applying common noise additively to the Kuramoto-Sivashinsky type equation, and the noise-induced phase synchronization is realized. The noise strength necessary for the suppression of phase turbulence is evaluated theoretically.

  18. Phase IV of Drug Development.

    Science.gov (United States)

    Suvarna, Viraj

    2010-04-01

    Not all Phase IV studies are post-marketing surveillance (PMS) studies but every PMS study is a phase IV study. Phase IV is also an important phase of drug development. In particular, the real world effectiveness of a drug as evaluated in an observational, non-interventional trial in a naturalistic setting which complements the efficacy data that emanates from a pre-marketing randomized controlled trial (RCT). No matter how many patients are studied pre-marketing in a controlled environment, the true safety profile of a drug is characterized only by continuing safety surveillance through a spontaneous adverse event monitoring system and a post-marketing surveillance/non-interventional study. Prevalent practice patterns can generate leads that could result in further evaluation of a new indication via the RCT route or even a signal that may necessitate regulatory action (change in labeling, risk management/minimization action plan). Disease registries are another option as are the large simple hybrid trials. Surveillance of spontaneously reported adverse events continues as long as a product is marketed. And so Phase IV in that sense never ends.

  19. Phase IV of Drug Development

    Directory of Open Access Journals (Sweden)

    Viraj Suvarna

    2010-01-01

    Full Text Available Not all Phase IV studies are post-marketing surveillance (PMS studies but every PMS study is a phase IV study. Phase IV is also an important phase of drug development. In particular, the real world effectiveness of a drug as evaluated in an observational, non-interventional trial in a naturalistic setting which complements the efficacy data that emanates from a pre-marketing randomized controlled trial (RCT. No matter how many patients are studied pre-marketing in a controlled environment, the true safety profile of a drug is characterized only by continuing safety surveillance through a spontaneous adverse event monitoring system and a post-marketing surveillance/non-interventional study. Prevalent practice patterns can generate leads that could result in further evaluation of a new indication via the RCT route or even a signal that may necessitate regulatory action (change in labeling, risk management/minimization action plan. Disease registries are another option as are the large simple hybrid trials. Surveillance of spontaneously reported adverse events continues as long as a product is marketed. And so Phase IV in that sense never ends.

  20. 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.

  1. Modeling of phased array transducers.

    Science.gov (United States)

    Ahmad, Rais; Kundu, Tribikram; Placko, Dominique

    2005-04-01

    Phased array transducers are multi-element transducers, where different elements are activated with different time delays. The advantage of these transducers is that no mechanical movement of the transducer is needed to scan an object. Focusing and beam steering is obtained simply by adjusting the time delay. In this paper the DPSM (distributed point source method) is used to model the ultrasonic field generated by a phased array transducer and to study the interaction effect when two phased array transducers are placed in a homogeneous fluid. Earlier investigations modeled the acoustic field for conventional transducers where all transducer points are excited simultaneously. In this research, combining the concepts of delayed firing and the DPSM, the phased array transducers are modeled semi-analytically. In addition to the single transducer modeling the ultrasonic fields from two phased array transducers placed face to face in a fluid medium is also modeled to study the interaction effect. The importance of considering the interaction effect in multiple transducer modeling is discussed, pointing out that neighboring transducers not only act as ultrasonic wave generators but also as scatterers.

  2. Random Phases and Energy Dispersion

    Institute of Scientific and Technical Information of China (English)

    刘全慧; 刘天贵; 班卫全

    2003-01-01

    Using 2N + 1 successive stationary states centred at nth, we construct a rectangular wavepacket in which the stationary states are superimposed with the equal weight √2N + 1. With the requirement of the wavepacket to be a quasi-classical state, the number N is determined by minimizing the uncertainty △x△p. Since the stationary state can only be determined to within an arbitrary multiplicative complex phase factor of unit magnitude, a number of N is obtained as a set of the phases are given. For a harmonic oscillator, when all of the phase factors are essentially the same, we have N ≈ [61/3n2/3] with [x] signifying the integral part of positive number x. When every phase in the phase factors is given by a random number generated in a closed interval [0, 2π] and when n ≥ 10, the probability of appearance of N is roughly 1/2N when N = 1 to 7, and does not exceed 0.01 whenN ≥ 8.

  3. Phase-field simulation of liquid phase migration in the WC-Co system during liquid phase sintering

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Kaiming; Zhang, Lijun; Du, Yong [Central South Univ., Changsha (China). State Key Lab. of Powder Metallurgy; Schwarze, Christian; Steinbach, Ingo [Bochum Univ. (Germany). Interdisciplinary Centre for Advanced Materials Simulation

    2016-04-15

    Liquid phase sintering is a process for forming high performance, multiple-phase components from powders. The process includes very complex interactions between various mass transportation phenomena, among which the liquid phase migration represents an important one in the aspect of forming a gradient structure in cemented carbide. In the present work, phase-field simulation of the liquid phase migration phenomenon during liquid phase sintering is performed in the WC-Co based cemented carbide. The simulation results are analyzed and compared with the experimentally determined key factors of microstructural evolution, such as contiguity and liquid phase migration rate. The diffusion-controlled solution-precipitation mechanism of the liquid phase migration process in the cemented carbide system is confirmed from the current simulation result, which provides deeper understanding of the microstructural evolution during the liquid phase migration process. These simulations can offer guidance in preventing the liquid phase migration process during liquid phase sintering of cellular cemented carbide.

  4. 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.

  5. Origin and use of crystallization phase diagrams.

    Science.gov (United States)

    Rupp, Bernhard

    2015-03-01

    Crystallization phase diagrams are frequently used to conceptualize the phase relations and also the processes taking place during the crystallization of macromolecules. While a great deal of freedom is given in crystallization phase diagrams owing to a lack of specific knowledge about the actual phase boundaries and phase equilibria, crucial fundamental features of phase diagrams can be derived from thermodynamic first principles. Consequently, there are limits to what can be reasonably displayed in a phase diagram, and imagination may start to conflict with thermodynamic realities. Here, the commonly used `crystallization phase diagrams' are derived from thermodynamic excess properties and their limitations and appropriate use is discussed.

  6. 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...

  7. Phase control of excitable systems

    Energy Technology Data Exchange (ETDEWEB)

    Zambrano, S; Seoane, J M; Marino, I P; Sanjuan, M A F [Nonlinear Dynamics and Chaos Group, Departamento de Fisica, Universidad Rey Juan Carlos, Tulipan s/n, 28933 Mostoles, Madrid (Spain); Euzzor, S; Meucci, R; Arecchi, F T [CNR-Istituto Nazionale di Ottica Applicata, Largo E. Fermi, 6 50125 Firenze (Italy)], E-mail: samuel.zambrano@urjc.es, E-mail: jesus.seoane@urjc.es, E-mail: ines.perez@urjc.es

    2008-07-15

    Here we study how to control the dynamics of excitable systems by using the phase control technique. Excitable systems are relevant in neuronal dynamics and therefore this method might have important applications. We use the periodically driven FitzHugh-Nagumo (FHN) model, which displays both spiking and non-spiking behaviours in chaotic or periodic regimes. The phase control technique consists of applying a harmonic perturbation with a suitable phase {phi} that we adjust in search of different behaviours of the FHN dynamics. We compare our numerical results with experimental measurements performed on an electronic circuit and find good agreement between them. This method might be useful for a better understanding of excitable systems and different phenomena in neuronal dynamics.

  8. Phase preservation in musical signals

    Science.gov (United States)

    Vijayakumar, V.; Eswaran, C.

    2005-04-01

    The intensity variations of the harmonics of musical instruments in the frequency domain can be interpreted to store phase information. The motivation for this arises by considering the similarity of the timbre of in- struments to that obtained through a diffraction model proposed here. The intensity modifications of an input spectrum of discrete frequencies of unit intensity into the known spectra of different musical instruments have been found to match that of known instruments. According to diffraction theory, the modifying envelope encodes phase information. By considering the similarity, it is proposed that musical instrument timbre store phase information. It is suggested that timbre itself could have diffraction origins. Specific examples of musical instruments are considered to illustrate this intepretation.

  9. Phase Transformations in Confined Nanosystems

    Energy Technology Data Exchange (ETDEWEB)

    Shield, Jeffrey E. [Department of Mechanical & Materials Engineering; Belashchenko, Kirill [Department of Physics & Astronomy

    2014-04-29

    This project discovered that non-equilibrium structures, including chemically ordered structures not observed in bulk systems, form in isolated nanoscale systems. Further, a generalized model was developed that effectively explained the suppression of equilibrium phase transformations. This thermodynamic model considered the free energy decrease associated with the phase transformation was less than the increase in energy associated with the formation of an interphase interface, therefore inhibiting the phase transformation. A critical diameter exists where the system transitions to bulk behavior, and a generalized equation was formulated that successfully predicted this transition in the Fe-Au system. This provided and explains a new route to novel structures not possible in bulk systems. The structural characterization was accomplished using transmission electron microscopy in collaboration with Matthew Kramer of Ames Laboratory. The PI and graduate student visited Ames Laboratory several times a year to conduct the experiments.

  10. Guiding light via geometric phases

    CERN Document Server

    Slussarenko, Sergei; Jisha, Chandroth P; Piccirillo, Bruno; Santamato, Enrico; Assanto, Gaetano; Marrucci, Lorenzo

    2015-01-01

    Known methods for transverse confinement and guidance of light can be grouped into a few basic mechanisms, the most common being metallic reflection, total internal reflection and photonic-bandgap (or Bragg) reflection. All of them essentially rely on changes of the refractive index, that is on scalar properties of light. Recently, processes based on "geometric Berry phases", such as manipulation of polarization states or deflection of spinning-light rays, have attracted considerable interest in the contexts of singular optics and structured light. Here, we disclose a new approach to light waveguiding, using geometric Berry phases and exploiting polarization states and their handling. This can be realized in structured three-dimensional anisotropic media, in which the optic axis lies orthogonal to the propagation direction and is modulated along it and across the transverse plane, so that the refractive index remains constant but a phase distortion can be imposed on a beam. In addition to a complete theoretic...

  11. Shock dynamics of phase diagrams

    CERN Document Server

    Moro, Antonio

    2014-01-01

    A thermodynamic phase transition denotes a drastic change of state of a physical system due to a continuous change of thermodynamic variables, as for instance pressure and temperature. The classical van der Waals equation of state is the simplest model that predicts the occurrence of a critical point associated with the gas-liquid phase transition. Nevertheless, below the critical temperature, theoretical predictions of the van der Waals theory significantly depart from the observed physical behaviour. We develop a novel approach to classical thermodynamics based on the solution of Maxwell relations for a generalised family of nonlocal entropy functions. This theory provides an exact mathematical description of discontinuities of the order parameter within the phase transition region, it explains the universal form of the equations of state and the occurrence of triple points in terms of the dynamics of nonlinear shock wave fronts.

  12. Phase diagram of ammonium nitrate

    Science.gov (United States)

    Dunuwille, M.; Yoo, C. S.

    2014-05-01

    Ammonium Nitrate (AN) has often subjected to uses in improvised explosive devices, due to its wide availability as a fertilizer and its capability of becoming explosive with slight additions of organic and inorganic compounds. Yet, the origin of enhanced energetic properties of impure AN (or AN mixtures) is neither chemically unique nor well understood -resulting in rather catastrophic disasters in the past1 and thereby a significant burden on safety in using ammonium nitrates even today. To remedy this situation, we have carried out an extensive study to investigate the phase stability of AN at high pressure and temperature, using diamond anvil cells and micro-Raman spectroscopy. The present results confirm the recently proposed phase IV-to-IV' transition above 17 GPa2 and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400 °C.

  13. GPC and quantitative phase imaging

    Science.gov (United States)

    Palima, Darwin; Bañas, Andrew Rafael; Villangca, Mark Jayson; Glückstad, Jesper

    2016-03-01

    Generalized Phase Contrast (GPC) is a light efficient method for generating speckle-free contiguous optical distributions using binary-only or analog phase levels. It has been used in applications such as optical trapping and manipulation, active microscopy, structured illumination, optical security, parallel laser marking and labelling and recently in contemporary biophotonics applications such as for adaptive and parallel two-photon optogenetics and neurophotonics. We will present our most recent GPC developments geared towards these applications. We first show a very compact static light 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 (QPI).

  14. 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.)

  15. Phased arrays: inline flow line hub inspection using phased arrays

    NARCIS (Netherlands)

    Bloom, J.G.P.; Chougrani, K.; Rundberg, H.; Oldenziel, G.; Deleye, X.; Martina, Q.

    2011-01-01

    The feasibility of the inspection of flow line hubs using the phased array technique was investigated to determine the surface area of the seal area degraded by corrosion. A clean model of the hub was simulated to gain insight into the geometrical echoes and to determine the area covered by the ultr

  16. The comfortable driving model revisited: Traffic phases and phase transitions

    CERN Document Server

    Knorr, Florian

    2013-01-01

    We study the spatiotemporal patterns resulting from different boundary conditions for a microscopic traffic model and contrast it with empirical results. By evaluating the time series of local measurements, the local traffic states are assigned to the different traffic phases of Kerner's three-phase traffic theory. For this classification we use the rule-based FOTO-method, which provides `hard' rules for this assignment. Using this approach, our analysis shows that the model is indeed able to reproduce three qualitatively different traffic phases: free flow (F), synchronized traffic (S), and wide moving jams (J). In addition, we investigate the likelihood of transitions between the three traffic phases. We show that a transition from free flow (F) to a wide moving jam (J) often involves an intermediate transition; first from free flow F to synchronized flow S and then from synchronized flow to a wide moving jam. This is supported by the fact that the so called F->S transition (from free flow to synchronized t...

  17. EHF multifunction phased array antenna

    Science.gov (United States)

    Solbach, Klaus

    1986-07-01

    The design of a low cost demonstration EHF multifunction-phased array antenna is described. Both, the radiating elements and the phase-shifter circuits are realized on microstrip substrate material in order to allow photolithographic batch fabrication. Self-encapsulated beam-lead PIN-diodes are employed as the electronic switch elements to avoid expensive hermetic encapsulation of the semiconductors or complete circuits. A space-feed using a horn-radiator to illuminate the array from the front-side is found to be the simplest and most inexpensive feed. The phased array antenna thus operates as a reflect-array, the antenna elements employed in a dual role for the collection of energy from the feed-horn and for the re-radiation of the phase-shifted waves (in transmit-mode). The antenna is divided into modules containing the radiator/phase-shifter plate plus drive- and BITE-circuitry at the back. Both drive- and BITE-components use gate-array integrated circuits especially designed for the purpose. Several bus-systems are used to supply bias and logical data flows to the modules. The beam-steering unit utilizes several signal processors and high-speed discrete adder circuits to combine the pointing, frequency and beam-shape information from the radar system computer with the stored phase-shift codes for the array elements. Since space, weight and power consumption are prime considerations only the most advanced technology is used in the design of both the microwave and the digital/drive circuitry.

  18. Biometeorological phases influence pedestrian trauma

    Directory of Open Access Journals (Sweden)

    Gajić Vladimir

    2011-01-01

    Full Text Available Introduction. Biometeorological circumstances have a big influence on all traffic participants, especially reflexes, moving coordination and perception ability. With a lower attention and drivers’ and pedestrians’ concentration, there was a larger amount of pedestrian trauma in certain biometeorological phases. Objective. The aim of this study was to establish the correlation between pedestrian trauma and biometeorological phases. Methods. The comparative analysis of everyday biometeorological phases for the city of Kragujevac determined by RHMI and the evidence of knocked-down pedestrians from the Kragujevac traffic police for the period 2003-2008. Results. There were 6,127 accidents, with 696 knocked pedestrians in 666 (10.87% accidents. Most of them happened in 2003 (135, and the fewest in 2005 (90. Most accidents were during December (74, the fewest were in June (46. The fewest accidents were during 04-05-06 hour interval (by 2, most during 13-14 hours (61. There were 374 males and 349 females. Most of the males (by 60 were 0-10 and 11-20 years old, most of the females (74 were 11-20 years old. There were 443 pedestrians who suffered slight body injuries (112 were 11-20, 225 suffered heavy and 28 had lethal injuries (most over 70. As provokers, the pedestrians suffered because of improper crossing roads (185, while as a casualties, they suffered due to speeding of vechicles (285. Most accidents happened in biometeorological phases 4 (168 and 9 (151, the fewest in phase 10 (4. Conclussion. Statistical analysis shows a significant correlation between pedestrians’ accidents and biometeorological phases, when the most accidents occurred during penetrations of cold fronts, while there was a sudden switch of weather conditions from warm-dry to cold-wet weather.

  19. 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.

  20. Closure phase and lucky imaging.

    Science.gov (United States)

    Rhodes, William T

    2009-01-01

    Since its introduction by Jennison in 1958, the closure-phase method for removing the effects of electrical path-length errors in radio astronomy and of atmospheric turbulence in optical astronomy has been based on the non-redundant-spacing triple interferometer. It is shown that through application of lucky imaging concepts it is possible to relax this condition, making closure-phase methods possible with redundantly spaced interferometer configurations and thereby widening their range of application. In particular, a quadruple-interferometer can, under lucky imaging conditions, be treated as though it were a triple interferometer. The slit-annulus aperture is investigated as a special case.

  1. Fractional vortex dipole phase filter

    Science.gov (United States)

    Sharma, Manoj Kumar; Joseph, Joby; Senthilkumaran, Paramasivam

    2014-10-01

    In spatial filtering experiments, the use of vortex phase filters plays an important role in realizing isotropic edge enhancement. In this paper, we report the use of a vortex dipole phase filter in spatial filtering. A dipole made of fractional vortices is used, and its filtering characteristics are studied. It is observed that the filter performance can be tuned by varying the distance of separation between the vortices of the dipole to achieve better contrast and output noise suppression, and when this distance tends to infinity, the filter performs like a 1-D Hilbert mask. Experimental and simulation results are presented.

  2. Robust Adaptive Quantum Phase Estimation

    CERN Document Server

    Roy, Shibdas; Huntington, Elanor H

    2014-01-01

    Quantum parameter estimation is central to many fields such as quantum computation, communications and metrology. Optimal estimation theory has been instrumental in achieving the best accuracy in quantum parameter estimation, which is possible when we have very precise knowledge of and control over the model. However, uncertainties in key parameters underlying the system are unavoidable and may impact the quality of the estimate. We show here how quantum optical phase estimation of a squeezed state of light exhibits improvement when using a robust fixed-interval smoother designed with uncertainties explicitly introduced in parameters underlying the phase noise.

  3. Phase Transformation of Nanosized Zirconia

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The nanosized zirconia was synthesized via solid state reaction in the presence of surfactant. The results indicate that crystal phase of zirconia can be controlled by tuning the syn- thesis parameters such as OH-/Zr molar ratio, crystallizing temperature and time. It can be trans- formed among amorphous, tetragonal and monoclinic phases. The transformation is driven by particle size. The research shows the nanocrystalline zirconia possesses the higher thermal stability compared with amorphous framework. The "glow exotherm" can be observed for the amorphous samples. Otherwise, it is in the absence for nanocrystalline samples. Herein, the reason for retention of tetragonal zirconia is demonstrated.

  4. Thermal Phase in Bubbling Geometries

    Institute of Scientific and Technical Information of China (English)

    LIU Chang-Yong

    2008-01-01

    We use matrix model to study thermal phase in bubbling half-BPS type IIB geometries with SO(4)×SO(4) symmetry.Near the horizon limit,we find that thermal vacua of bubbling geometries have disjoint parts,and each part is one kind of phase of the thermal system.We connect the thermal dynamics of bubbling geometries with one-dimensional fermions thermal system.Finally,we try to give a new possible way to resolve information loss puzzle.

  5. 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....

  6. Identification of alkyl dimethylbenzylammonium surfactants in water samples by solid-phase extraction followed by ion trap LC/MS and LC/MS/MS

    Science.gov (United States)

    Ferrer, I.; Furlong, E.T.

    2001-01-01

    A novel methodology was developed for the determination of alkyl (C12, C14, and C16) dimethylbenzylammonium chloride (benzalkonium chloride or BAC, Chemical Abstract Service number: 8001-54-5) in water samples. This method is based on solid-phase extraction (SPE) using polymeric cartridges, followed by high-performance liquid chromatography/ion trap mass spectrometry (LC/MS) and tandem mass spectrometry(MS/MS) detection, equipped with an electrospray interface in positive ion mode. Chromatographic separation was achieved for three BAC homologues by using a C18 column and a gradient of acetonitrile/10 millimolar aqueous ammonium formate. Total method recoveries were higher than 71% in different water matrices. The main ions observed by LC/MS were at mass-to-charge ratios (m/z) of 304, 332, and 360, which correspond to the molecular ions of the C12, C14, and C16 alkyl BAC, respectively. The unequivocal structural identification of these compounds in water samples was performed by LC/MS/MS after isolation and subsequent fragmentation of each molecular ion. The main fragmentation observed for the three different homologues corresponded to the loss of the toluyl group in the chemical structure, which leads to the fragment ions at m/z 212, 240, and 268 and a tropylium ion, characteristic of all homologues, at m/z 91. Detection limits for the methodology developed in this work were in the low nanogram-per-liter range. Concentration levels of BAC - ranging from 1.2 to 36.6 micrograms per liter - were found in surface-water samples collected downstream from different wastewater-treatment discharges, thus indicating its input and persistence through the wastewater-treatment process.

  7. 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.

  8. 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...

  9. Tradespace and Affordability - Phase 2

    Science.gov (United States)

    2013-12-31

    159 Figure 77: Ship Cost Model Mockup ...160 Figure 78: Satellite Cost Model Mockup ................................................................................... 161 Figure 79...evaluated as part of the TSSE initiative in Phase 3. 159 Figure 77: Ship Cost Model Mockup 160 3.3.3.5 COSATMO Prototyping

  10. 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)

  11. Scrutinizing the pion condensed phase

    CERN Document Server

    Carignano, Stefano; Mammarella, Andrea; Mannarelli, Massimo; Pagliaroli, Giulia

    2016-01-01

    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 in the normal phase and 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 ...

  12. 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.

  13. Symmetry structure and phase transitions

    Indian Academy of Sciences (India)

    Ashok Goyal; Meenu Dahiya; Deepak Chandra

    2003-05-01

    We study chiral 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 their survival.

  14. 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...

  15. Backyard Astronomy: Observing Moon Phases.

    Science.gov (United States)

    Brandou, Bob

    1997-01-01

    Presents an activity involving the observation of moon phases that can provide a one-on-one learning experience and stimulate interaction between a child and an adult family member. This activity can also be initiated by teachers and outcomes can be integrated into the classroom science curriculum. (JRH)

  16. Relativistic phase space dimensional recurrences

    CERN Document Server

    Delbourgo, Robert

    2003-01-01

    We derive recurrence relations between phase space expressions in different dimensions by confining some of the coordinates to tori or spheres of radius $R$ and taking the limit as $R \\to \\infty$. These relations take the form of mass integrals, associated with extraneous momenta (relative to the lower dimension), and produce the result in the higher dimension.

  17. Beyond the random phase approximation

    DEFF Research Database (Denmark)

    Olsen, Thomas; Thygesen, Kristian S.

    2013-01-01

    We assess the performance of a recently proposed renormalized adiabatic local density approximation (rALDA) for ab initio calculations of electronic correlation energies in solids and molecules. The method is an extension of the random phase approximation (RPA) derived from time-dependent density...

  18. SOLID PHASE SYNTHESIS OF ISOXAZOLINES

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The solid-phase synthesis of isoxazolines on 2-polystyrylsulfonamidoethanol resin isreported. 2-Polystyrylsuifonamidoethanol resin 1 was reacted with acryloyl chloride to afford2-polystyrylsulfonylamidoethyl acrylate resin 2, which was further reacted with brominatedaldoximes by [3+2] cycioaddition to give isoxazoline resin 4. Resin 4 was treated with aqueous 6mol/L HCI solution to obtain isoxazolines in good yield and purity.

  19. 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

  20. Calibrating for Ionospheric Phase Delays

    Science.gov (United States)

    Macdoran, P. F.

    1985-01-01

    Technique determines ionospheric phase delay on real-time universally applicable basis in terms of electrons per meter squared by coherently modulating two L-band carrier frequencies received from two Global Positioning System satelites. Two pseudorandom number sequences cross-correlated to derive delay time.

  1. 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.

  2. 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...

  3. Progress in bulk MgCu2-type rare-earth iron magnetostrictive compounds

    Institute of Scientific and Technical Information of China (English)

    Ren Wei-Jun; Zhang Zhi-Dong

    2013-01-01

    Studies of bulk MgCu2-type rare-earth iron compounds with Laves phase are reviewed.The relationship between magnetostriction and structural distortion and the consequent crystallographic method for measuring magnetostriction are introduced at first.Then we review recent progress in understanding bulk magnetostrictive Laves phase materials,especially the magnetostriction and the minimization of the anisotropy of the light rare-earth Pr-and Sm-based compounds.Finally,a summary and outlook for this kind of compounds are presented.

  4. Functional integral calculation of local magnetic moments at Ta impurities embedded in XFe{sub 2}(X=Gd,Yb) compounds: Temperature dependence

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, A.L. de [Centro Federal de Educacao Tecnologica de Quimica de Nilopolis, Rua Lucio Tavares, 1045, Nilopolis-RJ, 26530-060 (Brazil); Tovar Costa, M.V. [Instituto de Aplicacao, Universidade do Estado do Rio de Janeiro, Rua Santa Alexandrina, 288, Rio de Janeiro, 20261-232 (Brazil); Oliveira, N.A. de [Instituto de Fisica, Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier, 524, Rio de Janeiro, 20550-013 (Brazil); Troper, A. [Instituto de Fisica, Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier, 524, Rio de Janeiro, 20550-013 (Brazil); Centro Brasileiro de Pesquisas Fisicas, Rua Dr. Xavier Sigaud, 150, Rio de Janeiro, 22290-180 (Brazil)], E-mail: atroper@cbpf.br

    2008-04-01

    In this work, we study the systematics, at finite temperature, of the formation of local magnetic moments at a Ta impurity diluted in intermetallic Laves phases compounds XFe{sub 2}(X=Gd,Yb). We use an extended two-coupled sublattices Hubbard Hamiltonian, to describe the Laves phases host. The d-d electronic interaction is treated via a functional integral approach in the quasi-static saddle point approximation. Temperature dependent pressure effects are included considering induced electron-phonon interaction which renormalizes the pure electron hybridization. The calculated magnetic hyperfine fields related to the obtained local magnetic moments, are in a quite good agreement with available experimental data.

  5. Nonclassicality in phase-number uncertainty relations

    Energy Technology Data Exchange (ETDEWEB)

    Matia-Hernando, Paloma; Luis, Alfredo [Departamento de Optica, Facultad de Ciencias Fisicas, Universidad Complutense, 28040 Madrid (Spain)

    2011-12-15

    We show that there are nonclassical states with lesser joint fluctuations of phase and number than any classical state. This is rather paradoxical since one would expect classical coherent states to be always of minimum uncertainty. The same result is obtained when we replace phase by a phase-dependent field quadrature. Number and phase uncertainties are assessed using variance and Holevo relation.

  6. Phase control system for SSRF linac

    Institute of Scientific and Technical Information of China (English)

    YIN Chongxian; YU Luyang; LIU Dekang

    2008-01-01

    The design of phase control system in Shanghai Synchrotron Radiation Facility (SSRF) linac is presented in this paper. And digital phase detecting algorithm, the key for phase control system, is fully described. The testing results for phase control system in 100MeV linac are discussed in detail.

  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. IMPROVEMENT OF PHASE GRADIENT AUTOFOCUS ALGORITHM

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The phase error estimated by phase gradient autofocus(PGA) is not based on a finite order polynomial mode, so PGA has a good autofocus property for arbitrary order phase error and is fit for high resolution airborne SAR. But PGA has two shortcomings: first, it has a worse estimation property for fast changing phase error; second, there exists a section of linear phase in the phase error estimated by this algorithm. This paper introduces the idea of rank one phase estimate (ROPE) autofocus technique, and improves PGA. The improved PGA(IPGA) can successfully overcome both these shortcomings of PGA.

  9. Nanostructures having crystalline and amorphous phases

    Science.gov (United States)

    Mao, Samuel S; Chen, Xiaobo

    2015-04-28

    The present invention includes a nanostructure, a method of making thereof, and a method of photocatalysis. In one embodiment, the nanostructure includes a crystalline phase and an amorphous phase in contact with the crystalline phase. Each of the crystalline and amorphous phases has at least one dimension on a nanometer scale. In another embodiment, the nanostructure includes a nanoparticle comprising a crystalline phase and an amorphous phase. The amorphous phase is in a selected amount. In another embodiment, the nanostructure includes crystalline titanium dioxide and amorphous titanium dioxide in contact with the crystalline titanium dioxide. Each of the crystalline and amorphous titanium dioxide has at least one dimension on a nanometer scale.

  10. Analysis of phase regeneration of DPSK/DQPSK signals based on Phase-sensitive amplification

    Institute of Scientific and Technical Information of China (English)

    Xianfeng Tang; Xiaoguang Zhang; Lixia Xi

    2009-01-01

    Amplification and phase regeneration can be realized using a phase-sensitive amplifier(PSA).The phase regeneration of differential phase-shift keying(DPSK)signals based on PSA is analyzed theoretically.We realize the phase regeneration of differential quadrature phase-shift keying(DQPSK)signals based on a structure using two balanced PSAs.Simulations show that nearly ideal phase regeneration can be achieved for the DPSK/DQPSK signals.

  11. "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....

  12. Phases of holographic d-wave superconductor

    OpenAIRE

    Krikun, A.

    2015-01-01

    We study different phases in the holographic model of d-wave superconductor. These are described by solutions to the classical equations of motion found in different ansatze. Apart from the known homogeneous d-wave superconducting phase we find three new solutions. Two of them represent two distinct families of the spatially modulated solutions, which realize the charge density wave phases in the dual theory. The third one is the new homogeneous phase with nonzero anapole moment. These phases...

  13. Adiabatic geometric phases in hydrogenlike atoms

    OpenAIRE

    Sjöqvist, Erik; Yi, X. X.; Åberg, J.

    2005-01-01

    We examine the effect of spin-orbit coupling on geometric phases in hydrogenlike atoms exposed to a slowly varying magnetic field. The marginal geometric phases associated with the orbital angular momentum and the intrinsic spin fulfill a sum rule that explicitly relates them to the corresponding geometric phase of the whole system. The marginal geometric phases in the Zeeman and Paschen-Back limit are analyzed. We point out the existence of nodal points in the marginal phases that may be det...

  14. A New Phase Noise Detection Method

    OpenAIRE

    Yan, Gangfeng

    2015-01-01

    Phase noise is one of the most important parameters in many oscillators. Detecting accurately phase noise for oscillators has importance significance. In this paper, based on correlation operation detection phase noise for oscillators was proposed. This method not only can save a high precision reference oscillator, but also can detect accurately the phase noise of measured oscillator in theory. Detected phase noise of oscillators using this method has very strong utility value.

  15. The VLA Atmospheric Phase Interferometer

    Science.gov (United States)

    Morris, Keith

    2014-05-01

    The Atmospheric Phase Interferometer (API) is a two-element atmospheric seeing monitor located at the Very Large Array (VLA) site. The instrument measures turbulent refractive index variation through the atmosphere by examining phase differences in a satellite beacon signal detected at two (or more) antennas. With this measurement, the VLA scheduling software is able to consider atmospheric stability when determining which frequency observation to schedule next. We are in the process of extending this two-element interferometer to four elements, which will allow us to measure the turbulence in two dimensions and at multiple length scales. This thesis will look at some statistical properties of turbulence, the effects of atmospheric stability on radio interferometric observations, and discuss details of the instrument and the data that it collects. The thesis will also cover some techniques and principles of signal processing, and an analysis of some data from the instrument. The results demonstrate that other surface atmospheric variables (e.g. windspeed, water vapor pressure) show the same structure function exponent as the atmospheric phase fluctuations. In particular, the structure functions of water vapor partial pressure and wind speed show the same exponent as the phase. Though the agreement between meteorological variables and atmospheric phase is scientifically satisfying, these surface measurements are not nearly as sensitive as the API saturation phase measurement, and therefore cannot be used to schedule telescope time in its stead. What is informative about these results is that the similar structure functions for API and meteorological data are detecting reinforce the claim that both measurements represent turbulent transport, and not instrumental noise. Data from the instrument reveals that measurements are consistent with both Kolmogorov turbulence theory, and with prior observations. The API predominately measures three-dimensional isotropic

  16. Multiphase, multicomponent phase behavior prediction

    Science.gov (United States)

    Dadmohammadi, Younas

    Accurate prediction of phase behavior of fluid mixtures in the chemical industry is essential for designing and operating a multitude of processes. Reliable generalized predictions of phase equilibrium properties, such as pressure, temperature, and phase compositions offer an attractive alternative to costly and time consuming experimental measurements. The main purpose of this work was to assess the efficacy of recently generalized activity coefficient models based on binary experimental data to (a) predict binary and ternary vapor-liquid equilibrium systems, and (b) characterize liquid-liquid equilibrium systems. These studies were completed using a diverse binary VLE database consisting of 916 binary and 86 ternary systems involving 140 compounds belonging to 31 chemical classes. Specifically the following tasks were undertaken: First, a comprehensive assessment of the two common approaches (gamma-phi (gamma-ϕ) and phi-phi (ϕ-ϕ)) used for determining the phase behavior of vapor-liquid equilibrium systems is presented. Both the representation and predictive capabilities of these two approaches were examined, as delineated form internal and external consistency tests of 916 binary systems. For the purpose, the universal quasi-chemical (UNIQUAC) model and the Peng-Robinson (PR) equation of state (EOS) were used in this assessment. Second, the efficacy of recently developed generalized UNIQUAC and the nonrandom two-liquid (NRTL) for predicting multicomponent VLE systems were investigated. Third, the abilities of recently modified NRTL model (mNRTL2 and mNRTL1) to characterize liquid-liquid equilibria (LLE) phase conditions and attributes, including phase stability, miscibility, and consolute point coordinates, were assessed. The results of this work indicate that the ϕ-ϕ approach represents the binary VLE systems considered within three times the error of the gamma-ϕ approach. A similar trend was observed for the for the generalized model predictions using

  17. National Dam Safety Program. Lake Ashroe Dam (NJ00023), Delaware River Basin, Branch of Big Flat Brook, Sussex County, New Jersey. Phase I Inspection Report.

    Science.gov (United States)

    1981-03-01

    discharges into the spillway riser. A toe drain ) system which involved 4-inch diameter perforated asbestos-cement pipes and a rock fill toe blanket...repaired by the placement of cobbles and boulders. There appeared to be no warning system in effect. SECTION 5 HYDRAULIC/HYDROLOGIC Available...r* T oLAVE ASI-4FOE 4’,4 625- 1 5LRlCC PO H’ cI.AES i AS AD0’ IPTV ~ S~IA AWVIN SCOUT LIESERVATION AT LAI-E Asl4jzoe ("s7--12z) P-~ATe:P MAY, 1969

  18. 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.

  19. 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.

  20. Multiply Phased Traveling BPS Vortex

    CERN Document Server

    Kimm, Kyoungtae; Cho, Y M

    2016-01-01

    We present the multiply phased current carrying vortex solutions in the U(1) gauge theory coupled to an $(N+1)$-component SU(N+1) scalar multiplet in the Bogomolny limit. Our vortex solutions correspond to the static vortex dressed with traveling waves along the axis of symmetry. What is notable in our vortex solutions is that the frequencies of traveling waves in each component of the scalar field can have different values. The energy of the static vortex is proportional to the topological charge of $CP^N$ model in the BPS limit, and the multiple phase of the vortex supplies additional energy contribution which is proportional to the Noether charge associated to the remaining symmetry.

  1. 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...

  2. Coherent phase argument for inflation

    Energy Technology Data Exchange (ETDEWEB)

    Scott Dodelson

    2004-03-17

    Cosmologists have developed a phenomenally successful picture of structure in the universe based on the idea that the universe expanded exponentially in its earliest moments. There are three pieces of evidence for this exponential expansion--inflation--from observations of anisotropies in the cosmic microwave background. First, the shape of the primordial spectrum is very similar to that predicted by generic inflation models. Second, the angular scale at which the first acoustic peak appears is consistent with the flat universe predicted by inflation. Here the author describes the third piece of evidence, perhaps the most convincing of all: the phase coherence needed to account for the clear peak/trough structure observed by the WMAP satellite and its predecessors. The author also discusses alternatives to inflation that have been proposed recently and explain how they produce coherent phases.

  3. Three-phase Photovoltaic Systems

    DEFF Research Database (Denmark)

    Kerekes, Tamas; Sera, Dezso; Máthé, Lászlo

    2015-01-01

    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......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......, 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...

  4. Cavity Voltage Phase Modulation MD

    CERN Document Server

    Mastoridis, Themistoklis; Molendijk, John; Timko, Helga; CERN. Geneva. ATS Department

    2016-01-01

    The LHC RF/LLRF system is currently configured for extremely stable RF voltage to minimize transient beam loading effects. The present scheme cannot be extended beyond nominal beam current since the demanded power would exceed the peak klystron power and lead to saturation. A new scheme has therefore been proposed: for beam currents above nominal (and possibly earlier), the cavity phase modulation by the beam will not be corrected (transient beam loading), but the strong RF feedback and One-Turn Delay feedback will still be active for loop and beam stability in physics. To achieve this, the voltage set point will be adapted for each bunch. The goal of this MD was to test a new algorithm that would adjust the voltage set point to achieve the cavity phase modulation that would minimize klystron forward power.

  5. Singular Integrals with Bilinear Phases

    Institute of Scientific and Technical Information of China (English)

    Elena PRESTINI

    2006-01-01

    We prove the boundedness from Lp(T2) to itself, 1 < p <∞, of highly oscillatory singular integrals Sf(x, y) presenting singularities of the kind of the double Hilbert transform on a non-rectangular domain of integration, roughly speaking, defined by |y′| > | x′|, and presenting phases λ(Ax + By) with 0 ≤ A, B ≤ 1 and λ≥ 0. The norms of these oscillatory singular integrals are proved to be independent of all parameters A, B and λ involved. Our method extends to a more general family of phases. These results are relevant to problems of almost everywhere convergence of double Fourier and Walsh series.

  6. Phase-domain photoacoustic sensing

    Science.gov (United States)

    Gao, Fei; Zhang, Ruochong; Feng, Xiaohua; Liu, Siyu; Ding, Ran; Kishor, Rahul; Qiu, Lei; Zheng, Yuanjin

    2017-01-01

    As one of the fastest-growing imaging modalities in recent years, photoacoustic imaging has attracted tremendous research interest for various applications including anatomical, functional, and molecular imaging. The majority of the photoacoustic imaging systems are based on the time-domain pulsed photoacoustic method, which utilizes a pulsed laser source to induce a wideband photoacoustic signal, revealing optical absorption contrast. An alternative way is the frequency-domain photoacoustic method utilizing the chirping modulation of laser intensity to achieve lower system cost. In this paper, we report another way of the photoacoustic method, called phase-domain photoacoustic sensing, which explores the phase difference between two consequent intensity-modulated laser pulse induced photoacoustic measurements to reveal the optical properties. The basic principle is introduced, modeled, and experimentally validated in this paper, which opens another potential pathway to perform photoacoustic sensing and imaging, eliminating acoustic detection variations beyond the conventional time-domain and frequency-domain photoacoustic methods.

  7. 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.

  8. 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....... Optimal conditions for visibility, peak irradiance and accuracy are derived and shown to be perfectly in line with empirical results from the literature. New graphic methods for advanced analysis purposes are demonstrated supporting these conclusions as well as providing new tools for innovative filter...... 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...

  9. 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.

  10. Phase space embedding of electrocardiograms

    CERN Document Server

    Richter, M; Richter, Marcus; Schreiber, Thomas

    1998-01-01

    We study properties of the human electrocardiogram under the working hypothesis that fluctuations beyond the regular structure of single cardiac cycles are unpredictable. On this background we discuss the possibility to use the phase space embedding method for this kind of signal. In particular, the specific nature of the stochastic or high dimensional component allows to use phase space embeddings for certain signal processing tasks. As practical applications, we discuss noise filtering, fetal ECG extraction, and the automatic detection of clinically relevant features. The main purpose of the paper is to connect results of embedding theory which had not been previously applied in practise, and practical applications which had not yet been justified theoretically.

  11. Moment Distributions of Phase Type

    DEFF Research Database (Denmark)

    Bladt, Mogens; Nielsen, Bo Friis

    -type distributions. We construct representations for moment distributions based on a general matrix-exponential distribution which turns out to be a generalization of the moment distributions based on exponential distributions. For moment distributions based on phase{type distributions we find an appropriate...... alternative representation in terms of sub{intensity matrices. Finally we are able to nd explicit expressions for both the Lorenz curve and the Gini index....

  12. 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.

  13. Quantum gates with topological phases

    CERN Document Server

    Ionicioiu, R

    2003-01-01

    We investigate two models for performing topological quantum gates with the Aharonov-Bohm (AB) and Aharonov-Casher (AC) effects. Topological one- and two-qubit Abelian phases can be enacted with the AB effect using charge qubits, whereas the AC effect can be used to perform all single-qubit gates (Abelian and non-Abelian) for spin qubits. Possible experimental setups suitable for a solid state implementation are briefly discussed.

  14. DESIGN THREE PHASE OVERCURRENT RELAYS

    Directory of Open Access Journals (Sweden)

    Mohammed Y Suliman,

    2013-05-01

    Full Text Available  A new design of three phase overcurrent relay described in this paper. The performance of the new design shows the ability to obtain any shape of characteristic with high accuracy and distinguish between transient and steady state fault. This design used more precise and flexible model Sachdev linear model for get any characteristic, also fast measurement theory to measure load current for less than half cycle and good hardware system design controlled by Pentium version 4 processor.

  15. Tent Shaped Phased Array Tests.

    Science.gov (United States)

    1982-01-01

    AD-A113 191 HARRIS CORP MELBOURNE FL GOVERNMENT COMMUNICATION SY-ETC Fi 20/11TENT SHAPED PHASED ARRAY TESTS.(U JAN 82 C A CHUANG F19628-79-C-T173...821714f1 45 0 +450 SCAN PLANE ARRAY PATTERNS FIG. B-31 B- 31 AD-AL13 191 HARRS CRP PMELBOURNE FLY GOVERNMENT COMMUNICATION ST--ETC F/6 20/14 TENT SHAPED

  16. SOLID PHASE SYNTHESIS OF ISOXAZOLINES

    Institute of Scientific and Technical Information of China (English)

    SUNWeimin; LUOJuntao; 等

    2002-01-01

    The solid-phase synthesis of isoxazolines on 2-polystyrylsulfonamidoethanol resin is reported.2-Polystyrylsulfonamidoethanol resin 1 was reacted with acryloyl chloride to afford 2-polystyrylsulfonylamidoethyl acrylate resin 2,which was further reacted with brominated aldoximes by [3+2] cycloaddition to give isoxazoline resin 4.Resin 4 was treated with aqueous 6 mol/L HCl solution to obtain isoxazolines in good yield and purity.

  17. 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....

  18. 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.

  19. NIF optics phase gradient specfication

    Energy Technology Data Exchange (ETDEWEB)

    Williams, W.; Auerbach, J.; Hunt, J.; Lawson, L.; Manes, K.; Orth, C.; Sacks, R.; Trenholme, J.; Wegner, P.

    1997-05-02

    A root-mean-square (rms) phase gradient specification seems to allow a good connection between the NIP optics quality and focal spot requirements. Measurements on Beamlet optics individually, and as a chain, indicate they meet the assumptions necessary to use this specification, and that they have a typical rms phase gradient of {approximately}80 {angstrom}/cm. This may be sufficient for NIP to meet the proposed Stockpile Stewardship Management Program (SSMP) requirements of 80% of a high- power beam within a 200-250 micron diameter spot. Uncertainties include, especially, the scale length of the optics phase noise, the ability of the adaptive optic to correct against pump-induced distortions and optics noise, and the possibility of finding mitigation techniques against whole-beam self-focusing (e.g. a pre- correction optic). Further work is needed in these areas to better determine the NIF specifications. This memo is a written summary of a presentation on this topic given by W. Williams 24 April 1997 to NIP and LS&T personnel.

  20. Phase diagram of elastic spheres.

    Science.gov (United States)

    Athanasopoulou, L; Ziherl, P

    2017-02-15

    Experiments show that polymeric nanoparticles often self-assemble into several non-close-packed lattices in addition to the face-centered cubic lattice. Here, we explore theoretically the possibility that the observed phase sequences may be associated with the softness of the particles, which are modeled as elastic spheres interacting upon contact. The spheres are described by two finite-deformation theories of elasticity, the modified Saint-Venant-Kirchhoff model and the neo-Hookean model. We determine the range of indentations where the repulsion between the spheres is pairwise additive and agrees with the Hertz theory. By computing the elastic energies of nine trial crystal lattices at densities far beyond the Hertzian range, we construct the phase diagram and find the face- and body-centered cubic lattices as well as the A15 lattice and the simple hexagonal lattice, with the last two being stable at large densities where the spheres are completely faceted. These results are qualitatively consistent with observations, suggesting that deformability may indeed be viewed as a generic property that determines the phase behavior in nanocolloidal suspensions.

  1. Phase-preserved optical elevator

    Science.gov (United States)

    Luo, Yuan; Zhang, Baile; Han, Tiancheng; Chen, Zhi; Duan, Yubo; Chu, Chia-Wei; Barbastathis, George; Qiu, Cheng Wei

    2013-01-01

    The unique superiority of transformation optics devices designed from coordinate transformation is their capability of recovering both ray trajectory and optical path length in light manipulation. However, very few experiments have been done so far to verify this dual-recovery property from viewpoints of both ray trajectory and optical path length simultaneously. The experimental difficulties arise from the fact that most previous optical transformation optics devices only work at the nano-scale; the lack of intercomparison between data from both optical path length and ray trajectory measurement in these experiments obscured the fact that the ray path was subject to a subwavelength lateral shift that was otherwise not easily perceivable and, instead, was pointed out theoretically [B. Zhang et al. Phys. Rev. Lett. 104, 233903, (2010)]. Here, we use a simple macroscopic transformation optics device of phase-preserved optical elevator, which is a typical birefringent optical phenomenon that can virtually lift an optical image by a macroscopic distance, to demonstrate decisively the unique optical path length preservation property of transformation optics. The recovery of ray trajectory is first determined with no lateral shift in the reflected ray. The phase preservation is then verified with incoherent white-light interferometry without ambiguity and phase unwrapping. PMID:23546046

  2. Vital phase of space science

    Energy Technology Data Exchange (ETDEWEB)

    Parker, E.N. [Univ. of Chicago, IL (United States)

    1994-10-01

    Space science began with the indirect phase where the activity in space was inferred from such terrestrial phenomena as geomagnetic storms, ionospheric variations, and fluctuations in the cosmic ray intensity. The direct phase was initiated with spaceflight placing instruments directly in space and permitting the direct observation of UV and X rays, as well as precision observations of solar luminosity variations. The evidence from these many direct studies, together with the historical record of terrestrial conditions, shows that the variations of the luminosity of the Sun affect the terrestrial atmosphere at all levels, with devastating changes in climate tracking the major changes in the activity level and luminosity of the Sun. The quantification and understanding of this vital connection should be the first priority of space science and geophysics, from oceans and atmosphere through the ionosphere, magnetosphere, and all the way to the convective zone of the Sun. It becomes the vital phase of space science, focused on the basic science of the changing habitability of Earth. 13 refs.

  3. Phase diagram of crushed powders

    Science.gov (United States)

    Bodard, Sébastien; Jalbaud, Olivier; Saurel, Richard; Burtschell, Yves; Lapebie, Emmanuel

    2016-12-01

    Compression of monodisperse powder samples in quasistatic conditions is addressed in a pressure range such that particles fragmentation occurs while the solid remains incompressible (typical pressure range of 1-300 MPa for glass powders). For a granular bed made of particles of given size, the existence of three stages is observed during compression and crush up. First, classical compression occurs and the pressure of the granular bed increases along a characteristic curve as the volume decreases. Then, a critical pressure is reached for which fragmentation begins. During the fragmentation process, the granular pressure stays constant in a given volume range. At the end of this second stage, 20%-50% of initial grains are reduced to finer particles, depending on the initial size. Then the compression undergoes the third stage and the pressure increases along another characteristic curve, in the absence of extra fragmentation. The present paper analyses the analogies between the phase transition in liquid-vapour systems and powder compression with crush-up. Fragmentation diagram for a soda lime glass is determined by experimental means. The analogues of the saturation pressure and latent heat of phase change are determined. Two thermodynamic models are then examined to represent the crush-up diagram. The first one uses piecewise functions while the second one is of van der Waals type. Both equations of state relate granular pressure, solid volume fraction, and initial particle diameter. The piecewise functions approach provides reasonable representations of the phase diagram while the van der Waals one fails.

  4. CERN openlab enters new phase

    CERN Multimedia

    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 ...

  5. 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.

  6. Simultaneous amplitude and phase modulation by a discrete phase-only filter.

    Science.gov (United States)

    Goto, Hiroomi; Konishi, Tsuyoshi; Itoh, Kazuyoshi

    2009-03-01

    We propose a simultaneous amplitude and phase modulation method by a discrete phase-only filter. The proposed amplitude-phase filter can be realized by a discrete phase modulation of the diffractive optical element as well as a continuous phase modulation of the liquid crystal spatial light modulator. The fabricated amplitude-phase filter that has the six phase modulation levels shows a transfer efficiency of 75% regardless of the polarization state of the incident light. By using the proposed amplitude-phase filter, we demonstrate a temporal waveform conversion from sech(2) to super-Gaussian, which requires both amplitude and phase modulations.

  7. Two-phase flow research. Phase 1: Two-phase nozzle research

    Science.gov (United States)

    Toner, S. J.

    1981-07-01

    Experimental performance of converging-diverging nozzles operating on air-water mixtures is presented for a wide range of parameters. Thrust measurements characterized the performance and photographic documentation was used to visually observe the off-design regimes. Thirty-six nozzle configurations were tested to determine the effects of convergence angle, area ratio, and nozzle length. In addition, the pressure ratio and mass flowrate ratio were varied to experimentally map off-design performance. The test results indicate the effects of wall friction and infer temperature and velocity differences between phases and the effect on nozzle performance. The slip ratio between the phases, gas velocity to liquid velocity, is shown to be below about 4 or 5.

  8. 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.

  9. Discrete continuous-phase superresolving filters.

    Science.gov (United States)

    Zhou, Sumei; Zhou, Changhe

    2004-12-01

    A new type of phase-only superresolving pupil filter with a discrete continuous-phase profile is presented that is a combination of discrete multilevel-phase modulation and continuous-phase modulation. This type of filter can achieve better superresolution performance than the continuous-phase filters reported in Opt. Lett. 28, 607 (2003). Therefore, with regard to the superresolution effect, this type of filter deserves study for practical applications. More importantly, the diffraction performance of this type of filter can explain the effect of a discrete-phase filter illuminated with a continuous wave front, whose superresolving performance cannot be analyzed with previous superresolution methods.

  10. Quark Deconfinement Phase Transition in Neutron Stars

    CERN Document Server

    Alaverdyan, G B

    2009-01-01

    The hadron-quark phase transition in the interior of compact stars is investigated, when the transition proceeds through a mixed phase. The hadronic phase is described in the framework of relativistic mean-field theory, when also the scalar-isovector delta-meson mean-field is taken into account. The changes of the parameters of phase transition caused by the presence of delta-meson field are explored. The results of calculation of structure of the mixed phase (Glendenning construction) are compared with the results of usual first-order phase transition (Maxwell construction).

  11. Phase-locked laser coherent interference

    Institute of Scientific and Technical Information of China (English)

    Jingjing Wang; Xiaobo Wang; Bo He; Liantuan Mao; Suotang Jia

    2011-01-01

    A method of locking the relative phase to provide stable constructive or destructive interference between the phase-modulated sidebands from a pair of phase modulators is demonstrated. It is discussed theoretically for optimal fringe visibility related to the phase noise from faulty system. After phase locking using the phase modulating and lock-in technique, the drift of the relative phase is focalized around ±0.0016 rad and the fringe visibility is restricted to 2×l0-4.%@@ A method of locking the relative phase to provide stable constructive or destructive interference between the phase-modulated sidebands from a pair of phase modulators is demonstrated.It is discussed theoretically for optimal fringe visibility related to the phase noise from faulty system.After phase locking using the vhase modulating and lock-in technique.the drift of the relative phase is focalized around±0.0016 rad and the fringe visibility is restricted to 2×10-4.

  12. A novel three-phase UPS system with a single-phase resonant HF link

    OpenAIRE

    Darwish, MK

    2006-01-01

    This paper presents a new three-phase uninterruptible power supply (UPS) system based on a single-phase resonant high frequency (HF) link and a single-phase transformer. The three-phase output voltage is constructed and regulated from a three-phase cycloconverter fed from the constant amplitude, constant frequency link voltage. The generation of a novel switching stategy for the three-phase cycloconverter is presented. The simulation of the proposed system is carried out and verified with exp...

  13. Experimental Blade Research - phase 2

    OpenAIRE

    Eder, Martin Alexander; Branner, Kim; Berring, Peter; Belloni, Federico; Stensgaard Toft, Henrik; Sørensen, John Dalsgaard; Corre, Adrien; Lindby, Torben; Quispitupa, Amilcar; Petersen, Thomas Karl

    2015-01-01

    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 publicati...

  14. 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.

  15. Phase Transition in Tensor Models

    CERN Document Server

    Delepouve, Thibault

    2015-01-01

    Generalizing matrix models, tensor models generate dynamical triangulations in any dimension and support a $1/N$ expansion. Using the intermediate field representation we explicitly rewrite a quartic tensor model as a field theory for a fluctuation field around a vacuum state corresponding to the resummation of the entire leading order in $1/N$ (a resummation of the melonic family). We then prove that the critical regime in which the continuum limit in the sense of dynamical triangulations is reached is precisely a phase transition in the field theory sense for the fluctuation field.

  16. Phase 2 reentry in man

    DEFF Research Database (Denmark)

    Thomsen, P.E.B.; Jørgensen, R.M.; Kanters, J.K.;

    2005-01-01

    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 changes documented in the last sinus beat prior to ventricular extrasystoles are in agreement with phase 2 reentry, suggesting that this may be the responsible mechanism for ventricular extrasystoles and ventricular tachycardia/fibrillation. The phenomenon has been demonstrated in only animal experiments...

  17. ZBLAN Fiber Phase B Study

    Science.gov (United States)

    Workman, Gary L.; Smith, Guy A.

    1997-01-01

    A Phase B feasibility study will be performed for the study of the effects of microgravity on the preform processing and fiber pulling of ZBLAN optical glass. Continuing from the positive results achieved in the fiber annealing experiments in 20 second intervals at 0.001 g on the KC-135 and the 5 minute experiments on the SPAR rocket, experiments will continue to work towards design of a fiber sting to initiate fiber pulling operations in space. Anticipated results include less homogeneous nucleation than ground-based annealed fibers. Infrared Fiber Systems and Galileo are the participating industrial investigators.

  18. Airborne electronically steerable phased array

    Science.gov (United States)

    1972-01-01

    The results are presented of the second stage of a program for the design and development of a phased array capable of simultaneous and separate transmission and reception of radio frequency signals at S-band frequencies. The design goals of this stage were the development of three major areas of interest required for the final prototype model. These areas are the construction and testing of the low-weight, full-scale 128-element array of antenna elements, the development of the RF manifold feed system, and the construction and testing of a working module containing diplexer and transmit and receive circuits.

  19. Waveguide mutually pumped phase conjugators

    OpenAIRE

    James, S. W.; Youden, K.E.; Jeffrey, P. M.; EASON, R. W.; Chandler, P.J.; Zhang, L.; Townsend, P.D.

    1993-01-01

    The operation of the Bridge Mutually Pumped Phase Conjugator is reported in a planar waveguide structure in photorefractive BaTiO3. The waveguide was fabricated by the technique of ion implantation. using 1.5 MeV H+ at a dose of 10^16 ions/cm^2. An order of magnitude decrease in response time is observed in the waveguide as compared to typical values obtained in bulk crystals, probably resulting from a combination of the optical confinement within the waveguide, and possibly modification of t...

  20. 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