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Sample records for stable rhombohedral phase

  1. Experimental evidence for rhombohedral phase of C70 after irradiation

    International Nuclear Information System (INIS)

    Misof, K.; Fratzl, P.; Vogl, G.

    1993-01-01

    Purely f.c.c. C 70 was irradiated with high-energy heavy ions at low temperature. This led to the appearance of additional Bragg peaks attributed to an irradiation-induced f.c.c.-to-rhombohedral phase transition. On heating to about 570 K the retrasition to the pure f.c.c. phase occurred. Since no irradiation-induced phase transition was obsered in C 60 , the rhombohedral phase appears to be connected with the ''rugby-ball shape'' of C 70 which favours the alignment of the molecules. We propose that irradiation provides the agitation enabling the C 70 molecules to overcome the small energy barriers which otherwise prevent the alignment of the rugby balls over larger regions. (orig.)

  2. Adaptive ferroelectric state at morphotropic phase boundary: Coexisting tetragonal and rhombohedral phases

    International Nuclear Information System (INIS)

    Zhang, Yang; Xue, Dezhen; Wu, Haijun; Ding, Xiangdong; Lookman, Turab; Ren, Xiaobing

    2014-01-01

    With a focus on local symmetry, the microstructural basis for high piezoelectric performance in PbMg 1/3 Nb 2/3 O 3 –xPbTiO 3 (PMN–PT) ceramics at the morphotropic phase boundary (MPB) composition was investigated by means of convergent-beam electron diffraction analysis and twin diffraction pattern analysis. The local structure was found to consist of coexisting (1 0 1)-type tetragonal nanotwins and (0 0 1)-type rhombohedral nanotwins. A phenomenological theory based on crystallography is proposed to show that such nanoscale coexistence can give rise to an average monoclinic structure through strain accommodation. The average monoclinic structures (Ma and Mc) vary with temperature and composition due to the dependence on temperature and composition of the lattice parameters. Based on in situ X-ray diffraction data, we demonstrate how the polarization rotates across the MPB region in PMN–PT ceramics with varying temperatures and compositions

  3. The giant piezoelectric effect: electric field induced monoclinic phase or piezoelectric distortion of the rhombohedral parent?

    International Nuclear Information System (INIS)

    Kisi, E H; Piltz, R O; Forrester, J S; Howard, C J

    2003-01-01

    Lead zinc niobate-lead titanate (PZN-PT) single crystals show very large piezoelectric strains for electric fields applied along the unit cell edges e.g. [001] R . It has been widely reported that this effect is caused by an electric field induced phase transition from rhombohedral (R3m) to monoclinic (Cm or Pm) symmetry in an essentially continuous manner. Group theoretical analysis using the computer program ISOTROPY indicates phase transitions between R3m and Cm (or Pm) must be discontinuous under Landau theory. An analysis of the symmetry of a strained unit cell in R3m and a simple expansion of the piezoelectric strain equation indicate that the piezoelectric distortion due to an electric field along a cell edge in rhombohedral perovskite-based ferroelectrics is intrinsically monoclinic (Cm), even for infinitesimal electric fields. PZN-PT crystals have up to nine times the elastic compliance of other piezoelectric perovskites and it might be expected that the piezoelectric strains are also very large. A field induced phase transition is therefore indistinguishable from the piezoelectric distortion and is neither sufficient nor necessary to understand the large piezoelectric response of PZN-PT

  4. Gradient stress induced coexistence of tetragonal and rhombohedral phases in Pb(Zr,Ti)O3 films

    International Nuclear Information System (INIS)

    Li Liben; Chen Qingdong; Li Xinzhong; Hu Zhixiang; Zhen Zhiqiang

    2009-01-01

    Thermodynamic theory has been used to explain quantitatively the coexistence of tetragonal and rhombohedral phases in Zr-rich Pb(Zr, Ti)O 3 (PZT) films grown on a compressive substrate. The key is to consider a set of gradient thermal stresses imposed on the films. The 'stress-temperature' phase diagrams were developed for PZT films of several different compositions (Ti/Zr=20/80, 30/70, 40/60, 50/50). The characteristic feature of the phase diagrams for Zr-rich PZT films is the coexistence of tetragonal and rhombohedral phases in the compressive stress region. The volume fractions of the rhombohedral phase were calculated for the Zr-rich PZT films grown on MgO substrate. The result agrees with the experiment.

  5. The giant piezoelectric effect: electric field induced monoclinic phase or piezoelectric distortion of the rhombohedral parent?

    CERN Document Server

    Kisi, E H; Forrester, J S; Howard, C J

    2003-01-01

    Lead zinc niobate-lead titanate (PZN-PT) single crystals show very large piezoelectric strains for electric fields applied along the unit cell edges e.g. [001] sub R. It has been widely reported that this effect is caused by an electric field induced phase transition from rhombohedral (R3m) to monoclinic (Cm or Pm) symmetry in an essentially continuous manner. Group theoretical analysis using the computer program ISOTROPY indicates phase transitions between R3m and Cm (or Pm) must be discontinuous under Landau theory. An analysis of the symmetry of a strained unit cell in R3m and a simple expansion of the piezoelectric strain equation indicate that the piezoelectric distortion due to an electric field along a cell edge in rhombohedral perovskite-based ferroelectrics is intrinsically monoclinic (Cm), even for infinitesimal electric fields. PZN-PT crystals have up to nine times the elastic compliance of other piezoelectric perovskites and it might be expected that the piezoelectric strains are also very large. ...

  6. First-principles calculations on thermodynamic properties of BaTiO3 rhombohedral phase.

    Science.gov (United States)

    Bandura, Andrei V; Evarestov, Robert A

    2012-07-05

    The calculations based on the linear combination of atomic orbitals have been performed for the low-temperature phase of BaTiO(3) crystal. Structural and electronic properties, as well as phonon frequencies were obtained using hybrid PBE0 exchange-correlation functional. The calculated frequencies and total energies at different volumes have been used to determine the equation of state and thermal contribution to the Helmholtz free energy within the quasiharmonic approximation. For the first time, the bulk modulus, volume thermal expansion coefficient, heat capacity, and Grüneisen parameters in BaTiO(3) rhombohedral phase have been estimated at zero pressure and temperatures form 0 to 200 K, based on the results of first-principles calculations. Empirical equation has been proposed to reproduce the temperature dependence of the calculated quantities. The agreement between the theoretical and experimental thermodynamic properties was found to be satisfactory. Copyright © 2012 Wiley Periodicals, Inc.

  7. Two Topologically Distinct Dirac-Line Semimetal Phases and Topological Phase Transitions in Rhombohedrally Stacked Honeycomb Lattices

    Science.gov (United States)

    Hyart, T.; Ojajärvi, R.; Heikkilä, T. T.

    2018-04-01

    Three-dimensional topological semimetals can support band crossings along one-dimensional curves in the momentum space (nodal lines or Dirac lines) protected by structural symmetries and topology. We consider rhombohedrally (ABC) stacked honeycomb lattices supporting Dirac lines protected by time-reversal, inversion and spin rotation symmetries. For typical band structure parameters there exists a pair of nodal lines in the momentum space extending through the whole Brillouin zone in the stacking direction. We show that these Dirac lines are topologically distinct from the usual Dirac lines which form closed loops inside the Brillouin zone. In particular, an energy gap can be opened only by first merging the Dirac lines going through the Brillouin zone in a pairwise manner so that they turn into closed loops inside the Brillouin zone, and then by shrinking these loops into points. We show that this kind of topological phase transition can occur in rhombohedrally stacked honeycomb lattices by tuning the ratio of the tunneling amplitudes in the directions perpendicular and parallel to the layers. We also discuss the properties of the surface states in the different phases of the model.

  8. Ab initio study of phase transition of boron nitride between zinc-blende and rhombohedral structures

    Energy Technology Data Exchange (ETDEWEB)

    Nishida, S.; Funashima, H.; Sato, K.; Katayama-Yoshida, H. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)

    2013-12-04

    Boron nitride has polymorphs such as zinc-blende (c-BN), wurtzite (w-BN), rhombohedral (r-BN), and graphite-like (h-BN) forms. We simulate the direct conversion of r-BN to c-BN through electronic excitation. In our calculation, the conversion is made possible by increasing the hole concentration to over 0.06/atom. This conversion should be experimentally possible by hole-doping via an electric double layer transistor (EDLT) or capacitor.

  9. Twinning induced by the rhombohedral to orthorhombic phase transition in lanthanum gallate (LaGaO3)

    Science.gov (United States)

    Wang, W. L.; Lu, H. Y.

    2006-10-01

    Phase-transformation-induced twins in pressureless-sintered lanthanum gallate (LaGaO3) ceramics have been analysed using the transmission electron microscopy (TEM). Twins are induced by solid state phase transformation upon cooling from the rhombohedral (r, Rbar{3}c) to orthorhombic ( o, Pnma) symmetry at ˜145°C. Three types of transformation twins {101} o , {121} o , and {123} o were found in grains containing multiple domains that represent orientation variants. Three orthorhombic orientation variants were distinguished from the transformation domains converged into a triple junction. These twins are the reflection type as confirmed by tilting experiment in the microscope. Although not related by group-subgroup relation, the transformation twins generated by phase transition from rhombohedral to orthorhombic are consistent with those derived from taking cubic Pm {bar {3}}m aristotype of the lowest common supergroup symmetry as an intermediate metastable structure. The r→ o phase transition of first order in nature may have occurred by a diffusionless, martensitic-type or discontinuous nucleation and growth mechanism.

  10. Local rhombohedral symmetry in Tb0.3Dy0.7Fe2 near the morphotropic phase boundary

    International Nuclear Information System (INIS)

    Ma, Tianyu; Liu, Xiaolian; Pan, Xingwen; Li, Xiang; Jiang, Yinzhu; Yan, Mi; Li, Huiying; Fang, Minxia; Ren, Xiaobing

    2014-01-01

    The recently reported morphotropic phase boundary (MPB) in a number of giant magnetostrictive materials (GMMs) has drawn considerable interest to the local symmetry/structure near MPB region of these materials. In this letter, by in-situ X-ray diffraction and AC magnetic susceptibility measurements, we show that Tb 0.3 Dy 0.7 Fe 2 , the typical composition of Terfenol-D GMMs, has coexistence of rhombohedral and tetragonal phases over a wide temperature range in the vicinity of MPB. High resolution transmission electron microscopy provides direct evidence for local rhombohedral symmetry of the ferromagnetic phase and reveals regular-shaped nanoscale domains below 10 nm. The nano-sized structural/magnetic domains are hierarchically inside a single micron-sized stripe-like domain with the same average magnetization direction. Such domain structures are consistent with the low magnetocrystalline anisotropy and easy magnetic/structural domain switching under magnetic field, thus generating large magnetostriction at low field

  11. Ternary rhombohedral Laves phases RE_2Rh_3Ga (RE = Y, La-Nd, Sm, Gd-Er)

    International Nuclear Information System (INIS)

    Seidel, Stefan; Benndorf, Christopher; Heletta, Lukas; Poettgen, Rainer; Eckert, Hellmut; Sao Paulo Univ., Sao Carlos

    2017-01-01

    The ordered Laves phases RE_2Rh_3Ga (RE=Y, La-Nd, Sm, Gd-Er) were synthesized by arc-melting of the elements and subsequent annealing. The samples were characterized by powder X-ray diffraction (XRD). They crystallize with the rhombohedral Mg_2Ni_3Si type structure, space group R3m. Three structures were refined from single crystal X-ray diffractometer data: a=557.1(1), c=1183.1(2), wR2=0.0591, 159 F"2 values, 10 variables for Y_2Rh_3Ga, a=562.5(2), c=1194.4(2) pm, wR2=0.0519, 206 F"2 values, 11 variables for Ce_2Rh_3Ga and a=556.7(2), c=1184.1(3) pm, wR2=0.0396, 176 F"2 values, 11 variables for Tb_2Rh_3Ga. The Rh_3Ga tetrahedra are condensed via common corners and the large cavities left by the network are filled by the rare earth atoms. The RE_2Rh_3Ga Laves phases crystallize with a translationengleiche subgroup of the cubic RERh_2 Laves phases with MgCu_2 type. Magnetic susceptibility measurements reveal Pauli paramagnetism for Y_2Rh_3Ga and La_2Rh_3Ga. Ce_2Rh_3Ga shows intermediate cerium valence while all other RE_2Rh_3Ga phases are Curie-Weiss paramagnets which order magnetically at low temperatures. The "8"9Y and "7"1Ga solid state nuclear magnetic resonance (NMR) spectra of the diamagnetic representative Y_2Rh_3Ga show well-defined single resonances in agreement with an ordered bulk phase. In comparison to the binary Laves phase YRh_2 a strongly increased "8"9Y resonance frequency is observed owing to a higher s-electron spin density at the "8"9Y nuclei as proven by density of states (DOS) calculations.

  12. Electric field-induced phase transitions and composition-driven nanodomains in rhombohedral-tetragonal potassium-sodium niobate-based ceramics

    KAUST Repository

    Lv, Xiang

    2017-08-07

    The mechanisms behind the high piezoelectricity of (K,Na)NbO3-based lead-free ceramics were investigated, including electric field-induced phase transitions and composition-driven nanodomains. The construction of a rhombohedral-tetragonal (R-T) phase boundary, confirmed using several advanced techniques, allowed a large piezoelectric constant (d33) of 450 ± 5 pC/N to be obtained in (1-x)K0.4Na0.6Nb0.945Sb0.055O3-xBi0.5Na0.5(Hf1-ySny)O3 (0 ≤ x ≤ 0.06 and 0 ≤ y ≤ 0.5) ceramics possessing an ultralow ΔUT-R of 7.4 meV. More importantly, the existence of an intermediate phase, i.e., the electric-induced phase (EIP), bridging the rhombohedral R [Ps//(111)] and tetragonal T [Ps//(001)] phases during the polarization rotation was demonstrated. Striped nanodomains (∼40 nm) that easily responded to external stimulation were also observed in the ceramics with an R-T phase. Thus, the enhanced piezoelectric properties originated from EIP and the striped nanodomains.

  13. Local rhombohedral symmetry in Tb{sub 0.3}Dy{sub 0.7}Fe{sub 2} near the morphotropic phase boundary

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Tianyu, E-mail: maty@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Key Laboratory of Novel Materials for Information Technology of Zhejiang Province, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou 310027 (China); Ferroic Physics Group, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047, Ibaraki (Japan); Liu, Xiaolian; Pan, Xingwen; Li, Xiang; Jiang, Yinzhu; Yan, Mi, E-mail: mse-yanmi@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Key Laboratory of Novel Materials for Information Technology of Zhejiang Province, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou 310027 (China); Li, Huiying; Fang, Minxia [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, Xi' an Jiaotong University, Xi' an 710049 (China); Ren, Xiaobing, E-mail: ren.xiaobing@nims.go.jp [Ferroic Physics Group, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047, Ibaraki (Japan); Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, Xi' an Jiaotong University, Xi' an 710049 (China)

    2014-11-10

    The recently reported morphotropic phase boundary (MPB) in a number of giant magnetostrictive materials (GMMs) has drawn considerable interest to the local symmetry/structure near MPB region of these materials. In this letter, by in-situ X-ray diffraction and AC magnetic susceptibility measurements, we show that Tb{sub 0.3}Dy{sub 0.7}Fe{sub 2}, the typical composition of Terfenol-D GMMs, has coexistence of rhombohedral and tetragonal phases over a wide temperature range in the vicinity of MPB. High resolution transmission electron microscopy provides direct evidence for local rhombohedral symmetry of the ferromagnetic phase and reveals regular-shaped nanoscale domains below 10 nm. The nano-sized structural/magnetic domains are hierarchically inside a single micron-sized stripe-like domain with the same average magnetization direction. Such domain structures are consistent with the low magnetocrystalline anisotropy and easy magnetic/structural domain switching under magnetic field, thus generating large magnetostriction at low field.

  14. Enhanced lithium-ion storage performance by structural phase transition from two-dimensional rhombohedral Fe_2O_3 to cubic Fe_3O_4

    International Nuclear Information System (INIS)

    Ren, Yurong; Wang, Jiawei; Huang, Xiaobing; Ding, Jianning

    2016-01-01

    Highlights: • The rhombohedral Fe_2O_3 transforms to the cubic Fe_3O_4 via a calcination treatment. • Phase structure of anodes has great influences on their electrochemical performances. • Fe_3O_4/reduced graphene oxide shows a high capacity of 825.3 mAh g"−"1 at 50 mA g"−"1. - Abstract: The electrochemical performance of a material varies with its structural phase transition. It is found that the rhombohedral Fe_2O_3 can transform to the cubic Fe_3O_4 via a calcination treatment in a nitrogen atmosphere, and lithium-ion storage performances of Fe_3O_4 get an obvious improvement due to its structural advantages. On the basis of data calculated by X-ray diffraction, the larger unit cell volume as well as the higher void fraction of cubic Fe_3O_4 provides lithium-ions with more transport channels for Li ions diffusion and storage without serious volume change, and thus the cubic Fe_3O_4 delivers an excellent reversible capacity of 921.1 mAh g"−"1 after 15 cycles at the current density of 50 mA g"−"1, which is much higher than 328.3 mAh g"−"1 for the rhombohedral Fe_2O_3. To further enhance the structural stability of electrodes, reduced graphene oxide is introduced. The Fe_3O_4/reduced graphene oxide show an excellent specific capacity of 825.3 mAh g"−"1 after 40 cycles and impressive rate performance of 600 mAh g"−"1 at the current density of 400 mA g"−"1, which are much higher than that of Fe_3O_4 (417 and 300 mAh g"−"1), Fe_2O_3 (137.4 and 95 mAh g"−"1) and Fe_2O_3/reduced graphene oxide (390.1 and 480 mAh g"−"1). These results demonstrate that the structural phase transition and reduced graphene oxide of Fe_3O_4/reduced graphene oxide composites offer unique characteristics suitable for high-performance energy storage application.

  15. Collective modes in superconducting rhombohedral graphite

    Energy Technology Data Exchange (ETDEWEB)

    Kauppila, Ville [O.V. Lounasmaa Laboratory, Aalto University (Finland); Hyart, Timo; Heikkilae, Tero [University of Jyvaeskylae (Finland)

    2015-07-01

    Recently it was realized that coupling particles with a Dirac dispersion (such as electrons in graphene) can lead to a topologically protected state with flat band dispersion. Such a state could support superconductivity with unusually high critical temperatures. Perhaps the most promising way to realize such coupling in real materials is in the surface of rhombohedrally stacked graphite. We consider collective excitations (i.e. the Higgs modes) in surface superconducting rhombohedral graphite. We find two amplitude and two phase modes corresponding to the two surfaces of the graphite where the superconductivity lives. We calculate the dispersion of these modes. We also derive the Ginzburg-Landau theory for this material. We show that in superconducting rhombohedral graphite, the collective modes, unlike in conventional BCS superconductors, give a large contribution to thermodynamic properties of the material.

  16. Study of critical dependence of stable phases in Nitinol on heat treatment using electrical resistivity probe

    International Nuclear Information System (INIS)

    Uchil, J.; Mohanchandra, K.P.; Kumara, K.G.; Mahesh, K.K.

    1998-01-01

    Phase transformations in 40% cold-worked Nitinol as a function of heat treatment have been studied using electrical resistivity variation with temperature. The stabilisation of austenitic, rhombohedral and martensitic phases is shown to critically depend on the temperatures of heat treatment by the analysis of temperature dependence of electrical resistivity in heating and cooling parts of the cycle. Characteristic values of electrical resistivity of the stable phases are determined. The R-phase has been found to form continuously with increasing heat-treatment temperature starting from room temperature and to suddenly disappear beyond heat-treatment at 683 K. The observed presence or absence of R-phase is confirmed by heat capacity measurements as a function of temperature. (orig.)

  17. Phase boundary between cubic B1 and rhombohedral structures in (Mg,Fe)O magnesiowüstite determined by in situ X-ray diffraction measurements

    Science.gov (United States)

    Dymshits, Anna M.; Litasov, Konstantin D.; Shatskiy, Anton; Chanyshev, Artem D.; Podborodnikov, Ivan V.; Higo, Yuji

    2018-01-01

    The phase relations and equation of state of (Mg0.08Fe0.92)O magnesiowüstite (Mw92) have been studied using the Kawai-type high-pressure apparatus coupled with synchrotron radiation. To determine the phase boundary between the NaCl-type cubic (B1) and rhombohedral ( rB1) structures in Mw92, in situ X-ray observations were carried out at pressures of 0-35 GPa and temperatures of 300-1473 K. Au and MgO were used as the internal pressure markers and metallic Fe as oxygen fugacity buffer. The phase boundary between B1 and rB1 structures was described by a linear equation P (GPa) = 1.6 + 0.033 × T (K). The Clapeyron slope (d P/d T) determined in this study is close to that obtained at pressures above 70 GPa but steeper than that obtained for FeO. An addition of MgO to FeO structure expands the stability field of the rB1 phase to lower pressures and higher temperatures. Thus, the rB1 phase may be stabilized with respect to the B1 phase at a lower pressures. The pressure-volume-temperature equation of state of B1-Mw92 was determined up to 30 GPa and 1473 K. Fitting the hydrostatic compression data up to 30 GPa with the Birch-Murnaghan equation of state (EoS) yielded: unit cell volume ( V 0, T0), 79.23 ± 4 Å3; bulk modulus ( K 0, T0), 183 ± 4 GPa; its pressure derivative ( K' T ), 4.1 ± 0.4; (∂ K 0, T /∂ T) = -0.029 ± 0.005 GPa K‒1; a = 3.70 ± 0.27 × 10-5 K-1 and b = 0.47 ± 0.49 × 10-8 K-2, where α0, T = a + bT is the volumetric thermal expansion coefficient. The obtained bulk modulus of Mw92 is very close to the value expected for stoichiometric iron-rich (Mg,Fe)O. This result confirms the idea that the bulk modulus of (Mg,Fe)O is greatly affected by the actual defect structure, caused by either Mg2+ or vacancies.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-06-01

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

  19. Rhombohedral iron trifluoride with a hierarchized macroporous/mesoporous texture from gaseous fluorination of iron disilicide

    Energy Technology Data Exchange (ETDEWEB)

    Guérin, Katia, E-mail: katia.araujo_da_silva@univ-bpclermont.fr [Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6296, ICCF, F-63171 Aubière (France); Delbègue, Diane; Louvain, Nicolas; Doubtsof, Léa; Hamwi, André [Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6296, ICCF, F-63171 Aubière (France); Laik, Barbara; Pereira-Ramos, Jean-Pierre [Université Paris Est Créteil, Institut de Chimie et des Matériaux Paris-Est, UMR CNRS 7182, Thiais (France); Tahar-sougrati, Moulay; Jumas, Jean-Claude [Université Montpellier II, Institut Charles Gerhardt de Montpellier, UMR CNRS 5253, Montpellier (France); Willmann, Patrick; Cénac-Morthe, Céline [Centre National d' Etudes Spatiales, Toulouse (France)

    2016-04-15

    Stable low temperature rhombohedral iron trifluoride has been obtained by the fluorination under the pure fluorine gas of iron disilicide. The combination of both unusual fluorination process and precursor avoids to get unhydrated crystalline FeF{sub 3} particles and allows the formation of hierarchized channels of mesoporous/macroporous texture favorable for lithium diffusion. The fluorination mechanism proceeds by temperature steps from the formation, for a fluorination temperature below 200 °C, of an amorphous phase and an intermediate iron difluoride identified mainly by {sup 57}Fe Mössbauer spectroscopy before getting, as soon as a fluorination temperature of 260 °C is reached, the rhombohedral FeF{sub 3}. Both amorphous and crystallized samples display good ability for electrochemical process when used as cathode in lithium-ion battery. The low diameter of rhombohedral structure channels is balanced by an appropriate mesoporous texture and a capacity of 225 mAh.g{sup −1} after 5 cycles for a discharge cut-off of 2.5 V vs. Li{sup +}/Li at a current density of C/20 has been obtained and stabilized at 95 mAh.g{sup −1} after 116 cycles. - Highlights: • We investigated the synthesis of rhombohedral FeF{sub 3} by solid–gas reaction from iron disilicide. • We demonstrated that depending on the fluorination temperature various phases are stabilized. • We got a hierarchized macroporous/mesoporous texture. • We studied the electrochemical performances of amorphous and crystallized FeF{sub 3}. • Crystallized FeF{sub 3} presents a high faradic yield at first cycle focusing on insertion process.

  20. First-principles determination of the Raman fingerprint of rhombohedral graphite

    Science.gov (United States)

    Torche, Abderrezak; Mauri, Francesco; Charlier, Jean-Christophe; Calandra, Matteo

    2017-09-01

    Multilayer graphene with rhombohedral stacking is a promising carbon phase possibly displaying correlated states like magnetism or superconductivity due to the occurrence of a flat surface band at the Fermi level. Recently, flakes of thickness up to 17 layers were tentatively attributed to ABC sequences although the Raman fingerprint of rhombohedral multilayer graphene is currently unknown and the 2D resonant Raman spectrum of Bernal graphite is not understood. We provide a first principles description of the 2D Raman peak in three and four layers graphene (all stackings) as well as in Bernal, rhombohedral, and an alternation of Bernal and rhombohedral graphite. We give practical prescriptions to identify long range sequences of ABC multilayer graphene. Our work is a prerequisite to experimental nondestructive identification and synthesis of rhombohedral graphite.

  1. Radiation Response of Rhombohedral Oxides

    International Nuclear Information System (INIS)

    Devanathan, R.; Weber, W.J.; Mitchell, J.N.; Sickafus, K.E.; Nastasi, M.

    1997-05-01

    The radiation response of three rhombohedral oxides, namely, sapphire (α-Al 2 O 3 ), ilmenite (FeTiO 3 ), and geikielite (MgTiO 3 ), has been examined by irradiating electron transparent samples with 1 MeV Kr(+) and 1.5 MeV Xe(+)ions. The microstructural changes during irradiation were observed in situ in a high-voltage electron microscope using electron diffraction and microscopy. The irradiation conditions were designed to minimize beam heating and chemical effects due to the implanted ion. Of the three oxides studied, ilmenite is the most susceptible to radiation-induced amorphization while sapphire is the least susceptible. In all three materials, the critical temperature for amorphization was below 300 K indicating good room temperature resistance to amorphization by energetic beams

  2. Gas phase thermal diffusion of stable isotopes

    International Nuclear Information System (INIS)

    Eck, C.F.

    1979-01-01

    The separation of stable isotopes at Mound Facility is reviewed from a historical perspective. The historical development of thermal diffusion from a laboratory process to a separation facility that handles all the noble gases is described. In addition, elementary thermal diffusion theory and elementary cascade theory are presented along with a brief review of the uses of stable isotopes

  3. Preparation of meta-stable phases of barium titanate by Sol-hydrothermal method

    Directory of Open Access Journals (Sweden)

    Mahalakshmi Selvaraj

    2015-11-01

    Full Text Available Two low-cost chemical methods of sol–gel and the hydrothermal process have been strategically combined to fabricate barium titanate (BaTiO3 nanopowders. This method was tested for various synthesis temperatures (100 °C to 250 °C employing barium dichloride (BaCl2 and titanium tetrachloride (TiCl4 as precursors and sodium hydroxide (NaOH as mineralizer for synthesis of BaTiO3 nanopowders. The as-prepared BaTiO3 powders were investigated for structural characteristics using x-ray diffraction (XRD, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The overall analysis indicates that the hydrothermal conditions create a gentle environment to promote the formation of crystalline phase directly from amorphous phase at the very low processing temperatures investigated. XRD analysis showed phase transitions from cubic - tetragonal - orthorhombic - rhombohedral with increasing synthesis temperature and calculated grain sizes were 34 – 38 nm (using the Scherrer formula. SEM and TEM analysis verified that the BaTiO3 nanopowders synthesized by this method were spherical in shape and about 114 - 170 nm in size. The particle distribution in both SEM and TEM shows that as the reaction temperature increases from 100 °C to 250 °C, the particles agglomerate. Selective area electron diffraction (SAED shows that the particles are crystalline in nature. The study shows that choosing suitable precursor and optimizing pressure and temperature; different meta-stable (ferroelectric phases of undoped BaTiO3 nanopowders can be stabilized by the sol-hydrothermal method.

  4. Electric field-induced phase transitions and composition-driven nanodomains in rhombohedral-tetragonal potassium-sodium niobate-based ceramics

    KAUST Repository

    Lv, Xiang; Wu, Jiagang; Xiao, Dingquan; Zhu, Jianguo; Zhang, Xixiang

    2017-01-01

    -T) phase boundary, confirmed using several advanced techniques, allowed a large piezoelectric constant (d33) of 450 ± 5 pC/N to be obtained in (1-x)K0.4Na0.6Nb0.945Sb0.055O3-xBi0.5Na0.5(Hf1-ySny)O3 (0 ≤ x ≤ 0.06 and 0 ≤ y ≤ 0.5) ceramics possessing

  5. Stable Optical Phase Modulation With Micromirrors

    Science.gov (United States)

    2012-01-27

    to a voltage signal using a transimpedance amplifier with tranimpedance gain of Rf = 2 kΩ. The detected photocurrent of Iph = 0.6mA from 1.5mW of...the interferometer phase noise of δφmax = 4πrlδθmax/λ , which is then converted to the voltage noise at the output of the transimpedance amplifier by...The depth of modulation for a micromirror driven at mechanical resonance is amplified by the quality factor Q, enabling significant modulation with

  6. Tilts and Ionic Shifts in Rhombohedral Perovskites

    NARCIS (Netherlands)

    Noheda, Beatriz; Duan, Ning; Cereceda, Noé; Gonzalo, Julio A.

    1998-01-01

    We make a comparative analysis of rhombohedral perovskites (ABO3) with/without oxygen rotations and ionic shifts, within the framework of a generalised effective field approach. We analyse available data on LaAlO3 and LiTaO3 and new data on Zr-rich PZT, examples of three different ways of structural

  7. New stable phase in binary Fe-Nd

    International Nuclear Information System (INIS)

    Schneider, G.; Landgraf, F.J.G.; Villas-Boas, V.; Bezerra, G.H.; Missell, F.P.; Ray, A.E.

    1992-01-01

    An investigation of binary Fe-Nd alloys revealed the existence of an oxygen-free, stable Fe-rich phase A 2 , formed peritecticly in the range 750-800 deg C. EPMA shows this phase to contain 22.8 atomic percent Nd. This ferromagnetic phase has T c = 230 de C, but is magnetically soft. The X-ray diffraction pattern can be indexed using a hexagonal cell with a = 2.021 nm. and c = 1.235 nm. (author)

  8. Phase Stable RF-over-fiber Transmission using Heterodyne Interferometry

    International Nuclear Information System (INIS)

    Wilcox, R.; Byrd, J.M.; Doolittle, L.; Huang, G.; Staples, J.W.

    2010-01-01

    New scientific applications require phase-stabilized RF distribution to multiple remote locations. These include phased-array radio telescopes and short pulse free electron lasers. RF modulated onto a CW optical carrier and transmitted via fiber is capable of low noise, but commercially available systems aren't long term stable enough for these applications. Typical requirements are for less than 50fs long term temporal stability between receivers, which is 0.05 degrees at 3GHz. Good results have been demonstrated for RF distribution schemes based on transmission of short pulses, but these require specialized free-space optics and high stability mechanical infrastructure. We report a method which uses only standard telecom optical and RF components, and achieves less than 20fs RMS error over 300m of standard single-mode fiber. We demonstrate stable transmission of 3GHz over 300m of fiber with less than 0.017 degree (17fs) RMS phase error. An interferometer measures optical phase delay, providing information to a feed-forward correction of RF phase.

  9. Stability of lithium in α-rhombohedral boron

    International Nuclear Information System (INIS)

    Hayami, Wataru; Tanaka, Takaho; Otani, Shigeki

    2006-01-01

    The stability of lithium atoms in α-rhombohedral boron was studied by the density functional theory and Car-Parrinello molecular dynamics (MD) simulations. At a low Li concentration (1.03 at%), a Li atom at the center of the icosahedral B 12 site (the I-site) was found to be metastable, and the potential barrier was estimated at 775±25 K (=67±25 meV). Over 800 K, Li atoms began to escape from the B 12 cage and settled at the tetrahedral site (the T-site) or at the octahedral site (the O-site). Li at the T-site was also metastable below 1400 K, and Li at the O-site was energetically the most favorable. At a high Li concentration (7.69 at%), the I-site changed to an unstable saddle point. The T-site was still metastable, and the O-site was the most stable. Regardless of concentration, MD simulations showed that Li atoms at the O-site never jumped to other sites below 1400 K. The migration of Li would be very slow below this temperature

  10. Stable Low Cloud Phase II: Nocturnal Event Study

    Science.gov (United States)

    Bauman, William H., III; Barrett, Joe, III

    2007-01-01

    This report describes the work done by the Applied Meteorology Unit (AMU) in developing a database of nights that experienced rapid (formation in a stable atmosphere, resulting in ceilings at the Shuttle Landing Facility (TTS) that violated Space Shuttle Flight Rules (FR). This work is the second phase of a similar AMU task that examined the same phenomena during the day. In the first phase of this work, the meteorological conditions favoring the rapid formation of low ceilings include the presence of any inversion below 8000 ft, high relative humidity (RH) beneath the inversion and a clockwise turning of the winds from the surface to the middle troposphere (-15000 ft). The AMU compared and contrasted the atmospheric and thermodynamic conditions between nights with rapid low ceiling formation and nights with low ceilings resulting from other mechanisms. The AMU found that there was little to discern between the rapidly-forming ceiling nights and other low ceiling nights at TTS. When a rapid development occurred, the average RH below the inversions was 87% while non-events had an average RH of 79%. One key parameter appeared to be the vertical wind profile in the Cape Canaveral, FL radiosonde (XMR) sounding. Eighty-three percent of the rapid development events had veering winds with height from the surface to the middle troposphere (-15,000 ft) while 61% of the non-events had veering winds with height. Veering winds indicate a warm-advection regime, which supports large-scale rising motion and ultimately cloud formation in a moist environment. However, only six of the nights (out of 86 events examined) with low cloud ceilings had an occurrence of rapidly developing ceilings. Since only 7% rapid development events were observed in this dataset, it is likely that rapid low cloud development is not a common occurrence during the night, or at least not as common as during the day. In the AMU work on the daytime rapid low cloud development (Case and Wheeler 2005), nearly

  11. Lightweight Thermally Stable Multi-Meter Aperture Submillimeter Reflectors, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the Phase II effort will be an affordable demonstrated full-scale design for a thermally stable multi-meter submillimeter reflector. The Phase I...

  12. Asymptotically stable phase synchronization revealed by autoregressive circle maps

    Science.gov (United States)

    Drepper, F. R.

    2000-11-01

    A specially designed of nonlinear time series analysis is introduced based on phases, which are defined as polar angles in spaces spanned by a finite number of delayed coordinates. A canonical choice of the polar axis and a related implicit estimation scheme for the potentially underlying autoregressive circle map (next phase map) guarantee the invertibility of reconstructed phase space trajectories to the original coordinates. The resulting Fourier approximated, invertibility enforcing phase space map allows us to detect conditional asymptotic stability of coupled phases. This comparatively general synchronization criterion unites two existing generalizations of the old concept and can successfully be applied, e.g., to phases obtained from electrocardiogram and airflow recordings characterizing cardiorespiratory interaction.

  13. Split degenerate states and stable p+ip phases from holography

    Energy Technology Data Exchange (ETDEWEB)

    Nie, Zhang-Yu; Zeng, Hui [Kunming University of Science and Technology, Kunming (China); Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing (China); Pan, Qiyuan [Hunan Normal Univ., Key Lab. of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, and Synergetic Innovation Center for Quantum Effects and Applications, Dept. of Physics, Changsha (China); Zeng, Hua-Bi [Yangzhou University, College of Physics Science and Technology, Yangzhou, Jiangsu (China); National Central University, Department of Physics, Chungli (China)

    2017-02-15

    In this paper, we investigate the p+ip superfluid phases in the complex vector field holographic p-wave model. We find that in the probe limit, the p+ip phase and the p-wave phase are equally stable, hence the p and ip orders can be mixed with an arbitrary ratio to form more general p+λip phases, which are also equally stable with the p-wave and p+ip phases. As a result, the system possesses a degenerate thermal state in the superfluid region. We further study the case on considering the back-reaction on the metric, and we find that the degenerate ground states will be separated into p-wave and p+ip phases, and the p-wave phase is more stable. Finally, due to the different critical temperature of the zeroth order phase transitions from p-wave and p+ip phases to the normal phase, there is a temperature region where the p+ip phase exists but the p-wave phase does not. In this region we find the stable holographic p+ip phase for the first time. (orig.)

  14. Structural relationships in rhombohedral perovskites with R-3C symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Bogush, A K; Pavlov, V I [AN Belorusskoj SSR, Minsk. Inst. Fiziki Tverdogo Tela i Poluprovodnikov

    1982-05-01

    In rhombohedral perovskites the structure parameters, e.g. the interaxial angle alpha/sub rh/ or the hexagonal lattice parameters a/sub H/ and c/sub H/ are completely determined by the tilt angle omega. The geometrical relations between these structural parameters and the tilt angle omega are reported.

  15. Evidence of a stable binary CdCa quasicrystalline phase

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Jensen, C.H.; Rasmussen, A.R.

    2001-01-01

    Quasicrystals with a primitive icosahedral structure and a quasilattice constant of 5.1215 Angstrom have been synthesized in a binary Cd-Ca system. The thermal stability of the quasicrystal has been investigated by in situ high-temperature x-ray powder diffraction using synchrotron radiation. It ....... It is demonstrated that the binary CdCa quasicrystal is thermodynamic stable up to its melting temperature. The linear thermal expansion coefficient of the quasicrystal is 2.765x10(-5) K-1. (C) 2001 American Institute of Physics.......Quasicrystals with a primitive icosahedral structure and a quasilattice constant of 5.1215 Angstrom have been synthesized in a binary Cd-Ca system. The thermal stability of the quasicrystal has been investigated by in situ high-temperature x-ray powder diffraction using synchrotron radiation...

  16. Thermally stable electrolytes for rechargeable lithium batteries, phase 2

    Science.gov (United States)

    Dominey, L. A.; Goldman, J. L.; Koch, V. R.

    1989-09-01

    During the second year of research under NASA SBIR Contract NAS7-967, Covalent Associates and NASA contract monitors at the Jet Propulsion Laboratory agreed to perform an evaluation of the three best electrolytes developed during Phase 2. Due to the extensive period of time required to collect meaningful cycling data, we realized the study would extend well beyond the original formal end of the Phase 2 program (August 31, 1988). The substitution of this effort in lieu of an earlier proposed 20-cell final deliverable is formally documented in Modification No. 1 of Contract NAS7-967 as task 7. This Addendum contains the results of the cycling studies performed at Covalent Associates. In addition, sealed ampoules of each of these three electrolytes were delivered to the Jet Propulsion Laboratory Electrochemical Power Group. Their concurrent evaluation in a different test vehicle has also been recently concluded and their results are also summarized herein.

  17. Stable, metastable, and kinetically trapped amyloid aggregate phases.

    Science.gov (United States)

    Miti, Tatiana; Mulaj, Mentor; Schmit, Jeremy D; Muschol, Martin

    2015-01-12

    Self-assembly of proteins into amyloid fibrils plays a key role in a multitude of human disorders that range from Alzheimer's disease to type II diabetes. Compact oligomeric species, observed early during amyloid formation, are reported as the molecular entities responsible for the toxic effects of amyloid self-assembly. However, the relation between early-stage oligomeric aggregates and late-stage rigid fibrils, which are the hallmark structure of amyloid plaques, has remained unclear. We show that these different structures occupy well-defined regions in a peculiar phase diagram. Lysozyme amyloid oligomers and their curvilinear fibrils only form after they cross a salt and protein concentration-dependent threshold. We also determine a boundary for the onset of amyloid oligomer precipitation. The oligomeric aggregates are structurally distinct from rigid fibrils and are metastable against nucleation and growth of rigid fibrils. These experimentally determined boundaries match well with colloidal model predictions that account for salt-modulated charge repulsion. The model also incorporates the metastable and kinetic character of oligomer phases. Similarities and differences of amyloid oligomer assembly to metastable liquid-liquid phase separation of proteins and to surfactant aggregation are discussed.

  18. Modifications in the rhombohedral degree of distortion and magnetic properties of Ba-doped BiFeO3 as a function of synthesis methodology

    International Nuclear Information System (INIS)

    Rojas-George, G.; Silva, J.; Castañeda, R.; Lardizábal, D.; Graeve, O.A.; Fuentes, L.; Reyes-Rojas, A.

    2014-01-01

    We present an analysis of crystallographic symmetry and the origin of the pseudo-cubic character of doped BiFeO 3 . Specifically, barium-doped bismuth ferrite, Bi 1−x Ba x FeO 3 (x = 0.05, 0.075, 0.1, 0.125), perovskite-type nanoparticles have been synthesized by implementing five modifications to the sol–gel technique (citric acid-assisted sol–gel method, ethylene glycol method, tartaric acid-assisted sol–gel method, polyvinyl alcohol–ethylene glycol method, and EDTA complexing sol–gel method) and their final pseudo-cubic character is discussed. The effect of the carboxylic groups and hydroxyl groups during synthesis is critical to obtain single phase BBFO. Fourier transform infrared spectroscopy and thermogravimetric analysis is used to study the decomposition and thermal behavior of the precursors and their relation to the final nanoparticle characteristics. X-ray diffraction analysis shows a single phase with symmetry changes for four of the five synthesis methodologies employed. Only the EDTA complexing sol–gel method, where EDTA is used as dissolver and chelating agent, is not satisfactory in all concentration ranges. Rietveld results suggest that the degree of distortion of the rhombohedral symmetry in the crystallized BiFeO 3 powders decreases 12% as a result of progressive substitution of Bi 3+ by Ba 2+ and that there is no shift from rhombohedral to tetragonal symmetry. Magnetization properties of samples with a low-distortion rhombohedral structure show higher magnetic saturation and remanent magnetization than samples with high-distortion rhombohedral structure. - Highlights: • Ba–BiFeO 3 : rhombohedral distortion degree is highly affected by the chemical method. • Rietveld results show no shift in BBFO from rhombohedral to tetragonal symmetry. • The low-distortion rhombohedral structure show higher magnetic saturation. • To stabilize a metal complex is necessary a balance between COOH − and OH − groups

  19. Levels of acute phase proteins remain stable after ischemic stroke

    Directory of Open Access Journals (Sweden)

    Paik Myunghee C

    2006-10-01

    Full Text Available Abstract Background Inflammation and inflammatory biomarkers play an important role in atherosclerosis and cardiovascular disease. Little information is available, however, on time course of serum markers of inflammation after stroke. Methods First ischemic stroke patients ≥40 years old had levels of high-sensitivity C-reactive protein (hsCRP, serum amyloid A (SAA, and fibrinogen measured in plasma samples drawn at 1, 2, 3, 7, 14, 21 and 28 days after stroke. Levels were log-transformed as needed, and parametric and non-parametric statistical tests were used to test for evidence of a trend in levels over time. Levels of hsCRP and SAA were also compared with levels in a comparable population of stroke-free participants. Results Mean age of participants with repeated measures (n = 21 was 65.6 ± 11.6 years, and 13 (61.9% were men, and 15 (71.4% were Hispanic. Approximately 75% of patients (n = 15 had mild strokes (NIH Stroke Scale score 0–5. There was no evidence of a time trend in levels of hsCRP, SAA, or fibrinogen for any of the markers during the 28 days of follow-up. Mean log(hsCRP was 1.67 ± 1.07 mg/L (median hsCRP 6.48 mg/L among stroke participants and 1.00 ± 1.18 mg/L (median 2.82 mg/L in a group of 1176 randomly selected stroke-free participants from the same community (p = 0.0252. Conclusion Levels of hsCRP are higher in stroke patients than in stroke-free subjects. Levels of inflammatory biomarkers associated with atherosclerosis, including hsCRP, appear to be stable for at least 28 days after first ischemic stroke.

  20. Palmitic acid/polypyrrole composites as form-stable phase change materials for thermal energy storage

    International Nuclear Information System (INIS)

    Silakhori, Mahyar; Metselaar, Hendrik Simon Cornelis; Mahlia, Teuku Meurah Indra; Fauzi, Hadi; Baradaran, Saeid; Naghavi, Mohammad Sajad

    2014-01-01

    Highlights: • A novel phase change composite of palmitic acid–polypyrrole(PA–PPy) was fabricated. • Thermal properties of PA–PPy are characterized in different mass ratios of PA–PPy. • Thermal cycling test showed that form stable PCM had a favorable thermal reliability. - Abstract: In this study a novel palmitic acid (PA)/polypyrrole (PPy) form-stable PCMs were readily prepared by in situ polymerization method. PA was used as thermal energy storage material and PPy was operated as supporting material. Form-stable PCMs were investigated by SEM (scanning electron microscopy) and FTIR (Fourier transform infrared spectrometer) analysis that illustrated PA Particles were wrapped by PPy particles. XRD (X-ray diffractometer) was used for crystalline phase of PA/PPy composites. Thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC) were used for investigating Thermal stability and thermal energy storage properties of prepared form-stable PCMs. According to the obtained results the form stable PCMs exhibited favorable thermal stability in terms of their phase change temperature. The form-stable PCMs (79.9 wt% loading of PA) were considered as the highest loading PCM with desirable latent heat storage of 166.3 J/g and good thermal stability. Accelerated thermal cycling tests also showed that form stable PCM had an acceptable thermal reliability. As a consequence of acceptable thermal properties, thermal stability and chemical stability, we can consider the new kind of form stable PCMs for low temperature solar thermal energy storage applications

  1. Electronic structure and lattice dynamics of rhombohedral BiAlO_3 from first-principles

    International Nuclear Information System (INIS)

    Kaczkowski, J.

    2016-01-01

    The structural, elastic, electronic, dynamical (zone-center phonon modes and Born effective charge tensors), and ferroelectric properties of the rhombohedral BiAlO_3 were calculated within various exchange-correlation functionals. The standard local-density (LDA) and generalized gradient (GGA) approximations, and nonlocal hybrid Heyd-Scuseria-Ernzerhof (HSE) were used. We have also performed the electronic structure calculations with meta-GGA Tran-Blaha functional. BiAlO_3 is indirect band gap semiconductor with the value of band gap: 2.87 eV (GGA), 4.14 eV (HSE), and 3.78 eV (TB-mBJ). The calculated spontaneous polarization is 81 μC/cm"2 (87 μC/cm"2) for GGA (HSE). The vibrational spectrum including LO-TO splitting was calculated within GGA. The zone-center phonon modes with LO-TO splitting for BiAlO_3 were compared with those in isostructural BiFeO_3. - Highlights: • Electronic structure of the rhombohedral phase of BiAlO_3 were calculated. • Structural, elastic, dynamical, and ferroelectric properties were investigated. • Calculations were done within GGA, hybrid HSE, and TB-mBJ functionals. • The lattice dynamics with LO-TO splitting were investigated within GGA functional.

  2. Thermal performance study of form-stable composite phase change material with polyacrylic

    Science.gov (United States)

    Kee, Shin Yiing; Munusamy, Yamuna; Ong, Kok Seng; Chee, Swee Yong; Sanmuggam, Shimalaa

    2017-04-01

    Phase change material (PCM) is one of the most popular and widely used as thermal energy storage material because it is able to absorb and release a large amount of latent heat during a phase change process over a narrow temperature range. In this work, the form-stable composite PCM was prepared by blending of PMMA and myristic acid in different weight percentage. PMMA was used as a supporting material while myristic acid was used as PCM. Theoretically, PCM can be encapsulated in the support material after blending. However, a small amount of liquid PCMs can leak out from supporting material due to the volume change in phase change process. Therefore, a form-stable composite PCM with polyacrylic coating was studied. Leakage test was carried out to determine the leakage percentage of the form-stable composite PCM. Fourier transform infrared spectroscopy (FTIR) was used to characterize the chemical compatibility of the form-stable PCM composite while differential scanning calorimetry (DSC) was used to study the melting, freezing point and the latent heat of melting and freezing for the form-stable composite PCM.

  3. Intrinsically stable phase-modulated polarization encoding system for quantum key distribution

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xiaobao [Laboratory of Photonic Information Technology, School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China); Liao Changjun [Laboratory of Photonic Information Technology, School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China)], E-mail: chliao@scnu.edu.cn; Mi Jinglong; Wang Jindong; Liu Songhao [Laboratory of Photonic Information Technology, School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China)

    2008-12-22

    We demonstrate experimentally an intrinsically stable polarization coding and decoding system composed of optical-fiber Sagnac interferometers with integrated phase modulators for quantum key distribution. An interference visibility of 98.35% can be kept longtime during the experiment without any efforts of active compensation for coding all four desired polarization states.

  4. Rhombohedral PLZT piezoelectric microfibers: a combined Raman and X-ray diffraction study

    Science.gov (United States)

    Kozielski, Lucjan; Buixaderas, Elena; Clemens, Frank

    2014-11-01

    A combination of micro- and macro-scale structural characterization methods was implemented for clarification of the influence of different sintering atmospheres on the structural properties of Pb1-xLax(ZryTi1-y)O3 (PLZT) fibers. Three powders, PbZrO3 and ZrO2 (PZ + Z), PbZrO3 (PZ), and PbZrO3 + PbO (PZ + P), were used for the generation of protective atmospheres. Vibrations corresponding to the rhombohedral phase in (Pb0.93La0.07)(Zr0.65Ti0.35)O3 fibers were measured and mapped along the section of the fibers by micro-Raman spectroscopy. Comparison of the Raman data with the evolution of the unit cell parameters indicates that the PZ + Z protective atmosphere ensures the best properties during the PLZT sintering at the temperature of 1250 °C for 6 hours.

  5. Multiturn extraction and injection by means of adiabatic capture in stable islands of phase space

    Directory of Open Access Journals (Sweden)

    R. Cappi

    2004-02-01

    Full Text Available Recently a novel approach has been proposed for performing multiturn extraction from a circular machine. Such a technique consists of splitting the beam by means of stable islands created in transverse phase space by magnetic elements creating nonlinear fields, such as sextupoles and octupoles. Provided a slow time variation of the linear tune is applied, adiabatic with respect to the betatron motion, the islands can be moved in phase space and eventually charged particles may be trapped inside the stable structures. This generates a certain number of well-separated beamlets. Originally, this principle was successfully tested using a fourth-order resonance. In this paper the approach is generalized by considering other types of resonances as well as the possibility of performing multiple multiturn extractions. The results of numerical simulations are presented and described in detail. Of course, by time reversal, the proposed approach could be used also for multiturn injection.

  6. Influence of dopants, particularly carbon, on β-rhombohedral boron

    Science.gov (United States)

    Werheit, H.; Flachbart, K.; Pristáš, G.; Lotnyk, D.; Filipov, V.; Kuhlmann, U.; Shitsevalova, N.; Lundström, T.

    2017-09-01

    Due to the high affinity of carbon to boron, the preparation of carbon-free boron is problematic. Even high-purity (6 N) β-rhombohedral boron contains 30-60 ppm of C. Hence, carbon affects the boron physical properties published so far more or less significantly. We studied well-defined carbon-doped boron samples based on pure starting material carefully annealed with up to about 1% C, thus assuring homogeneity. We present and discuss their electrical conductivity, optical absorption, luminescence and phonon spectra. Earlier attempts of other authors to determine the conductivity of C-doped boron are revised. Our results allow estimating the effects of oxygen and iron doping on the electrical conductivity using results taken from literature. Discontinuities at low T impair the electronic properties.

  7. Modifications in the rhombohedral degree of distortion and magnetic properties of Ba-doped BiFeO{sub 3} as a function of synthesis methodology

    Energy Technology Data Exchange (ETDEWEB)

    Rojas-George, G. [Centro de Investigación en Materiales Avanzados S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Chih. 31109 (Mexico); Silva, J. [Universidad Autónoma de Ciudad Juárez, Ave. del Charro 450 Norte, Cd. Juárez, Chih. 32310 (Mexico); Castañeda, R.; Lardizábal, D. [Centro de Investigación en Materiales Avanzados S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Chih. 31109 (Mexico); Graeve, O.A. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, 9500 Gilman Dr. – MC 0411, La Jolla, CA 92093-0411 (United States); Fuentes, L. [Centro de Investigación en Materiales Avanzados S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Chih. 31109 (Mexico); Reyes-Rojas, A., E-mail: armando.reyes@cimav.edu.mx [Centro de Investigación en Materiales Avanzados S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Chih. 31109 (Mexico)

    2014-07-01

    We present an analysis of crystallographic symmetry and the origin of the pseudo-cubic character of doped BiFeO{sub 3}. Specifically, barium-doped bismuth ferrite, Bi{sub 1−x}Ba{sub x}FeO{sub 3} (x = 0.05, 0.075, 0.1, 0.125), perovskite-type nanoparticles have been synthesized by implementing five modifications to the sol–gel technique (citric acid-assisted sol–gel method, ethylene glycol method, tartaric acid-assisted sol–gel method, polyvinyl alcohol–ethylene glycol method, and EDTA complexing sol–gel method) and their final pseudo-cubic character is discussed. The effect of the carboxylic groups and hydroxyl groups during synthesis is critical to obtain single phase BBFO. Fourier transform infrared spectroscopy and thermogravimetric analysis is used to study the decomposition and thermal behavior of the precursors and their relation to the final nanoparticle characteristics. X-ray diffraction analysis shows a single phase with symmetry changes for four of the five synthesis methodologies employed. Only the EDTA complexing sol–gel method, where EDTA is used as dissolver and chelating agent, is not satisfactory in all concentration ranges. Rietveld results suggest that the degree of distortion of the rhombohedral symmetry in the crystallized BiFeO{sub 3} powders decreases 12% as a result of progressive substitution of Bi{sup 3+} by Ba{sup 2+} and that there is no shift from rhombohedral to tetragonal symmetry. Magnetization properties of samples with a low-distortion rhombohedral structure show higher magnetic saturation and remanent magnetization than samples with high-distortion rhombohedral structure. - Highlights: • Ba–BiFeO{sub 3}: rhombohedral distortion degree is highly affected by the chemical method. • Rietveld results show no shift in BBFO from rhombohedral to tetragonal symmetry. • The low-distortion rhombohedral structure show higher magnetic saturation. • To stabilize a metal complex is necessary a balance between COOH{sup

  8. Graphene/phase change material nanocomposites: light-driven, reversible electrical resistivity regulation via form-stable phase transitions.

    Science.gov (United States)

    Wang, Yunming; Mi, Hongyi; Zheng, Qifeng; Ma, Zhenqiang; Gong, Shaoqin

    2015-02-04

    Innovative photoresponsive materials are needed to address the complexity of optical control systems. Here, we report a new type of photoresponsive nanomaterial composed of graphene and a form-stable phase change material (PCM) that exhibited a 3 orders of magnitude change in electrical resistivity upon light illumination while retaining its overall original solid form at the macroscopic level. This dramatic change in electrical resistivity also occurred reversibly through the on/off control of light illumination. This was attributed to the reversible phase transition (i.e., melting/recrystallization) behavior of the microscopic crystalline domains present in the form-stable PCM. The reversible phase transition observed in the graphene/PCM nanocomposite was induced by a reversible temperature change through the on/off control of light illumination because graphene can effectively absorb light energy and convert it to thermal energy. In addition, this graphene/PCM nanocomposite also possessed excellent mechanical properties. Such photoresponsive materials have many potential applications, including flexible electronics.

  9. Preparation and thermal properties of form stable paraffin phase change material encapsulation

    International Nuclear Information System (INIS)

    Liu Xing; Liu Hongyan; Wang Shujun; Zhang Lu; Cheng Hua

    2006-01-01

    Paraffin waxes are cheap and have moderate thermal energy storage density but low thermal conductivity and, hence, require large surface area to be used in energy storage. Form stable paraffin phase change materials (PCM) in which paraffin serves as a latent heat storage material and polyolefins act as a supporting material, because of paraffin leakage, are required to be improved. The form stable paraffin PCM in the present paper was encapsulated in an inorganic silica gel polymer successfully by in situ polymerization. The differential scanning calorimeter (DSC) was used to measure its thermal properties. At the same time, the Washburn equation, which measures the wetting properties of powder materials, was used to test the hydrophilic-lipophilic properties of the PCMs. The result indicated that the enthalpy of the microencapsulated PCMs was reduced little, while their hydrophilic properties were enhanced largely

  10. Thermodynamic calculation of the regions of stable existance of niobium nitride phases

    International Nuclear Information System (INIS)

    Chernyaev, V.V.; Mitrofanov, B.V.; Moiseev, G.K.; 6030000SU)

    1987-01-01

    Conditions of formation and stable existence of Nb 2 N and NbN niobium nitrides and the general picture of phase transformations in Nb-N system were determined in wide range of temperatures 1400-4000 K and pressures 10 -9 -10 MPa in result of thermodynamic analysis of Nb-N system using the program, realizing algorithm of total potential minimization. The sufficient nitrogen excess is necessary for formation of Nb 2 N and NbN especially. The temperature stability region and the temperature of NbN and Nb 2 N decomposition is shifted to high temperature region with pressure growth. Pressure region where niobium nitrides are stable, is shifted to high pressure region. The obtained calculation data correspond satisfactorily with experimental publication results. This testifies to possibility of using results of thermodynamic calculations for construction of p-T-diagrams of Nb-N system state

  11. Experimental evidence of adiabatic splitting of charged particle beams using stable islands of transverse phase space

    Directory of Open Access Journals (Sweden)

    S. Gilardoni

    2006-10-01

    Full Text Available Recently, a novel technique to perform multiturn extraction from a circular particle accelerator was proposed. It is based on beam splitting and trapping, induced by a slow crossing of a nonlinear resonance, inside stable islands of transverse phase space. Experiments at the CERN Proton Synchrotron started in 2002 and evidence of beam splitting was obtained by summer 2004. In this paper, the measurement results achieved with both a low- and a high-intensity, single-bunch proton beam are presented.

  12. Phase behaviour and structure of stable complexes of oppositely charged polyelectrolytes

    Science.gov (United States)

    Mengarelli, V.; Auvray, L.; Zeghal, M.

    2009-03-01

    We study the formation and structure of stable electrostatic complexes between oppositely charged polyelectrolytes, a long polymethacrylic acid and a shorter polyethylenimine, at low pH, where the polyacid is weakly charged. We explore the phase diagram as a function of the charge and concentration ratio of the constituents. In agreement with theory, turbidity and ζ potential measurements show two distinct regimes of weak and strong complexation, which appear successively as the pH is increased and are separated by a well-defined limit. Weak complexes observed by neutron scattering and contrast matching have an open, non-compact structure, while strong complexes are condensed.

  13. Study on polyethylene glycol/epoxy resin composite as a form-stable phase change material

    International Nuclear Information System (INIS)

    Fang Yutang; Kang Huiying; Wang Weilong; Liu Hong; Gao Xuenong

    2010-01-01

    Form-stable polyethylene glycol (PEG)/epoxy resin (EP) composite as a novel phase change material (PCM) was prepared using casting molding method. In this new material, PEG acts as the latent heat storage material and EP polymer serves as the supporting material, which provides structural strength and prevents the leakage of the melted PEG. The structure and morphology of the novel composite were observed using Fourier transformation infrared spectroscope (FTIR) and scanning electronic microscope (SEM). The thermo-mechanical property and transition behavior were characterized by polarizing optical microscope (POM), static thermo-mechanical analysis (TMA) and differential scanning calorimeter (DSC). The experimental results show that, as a result of the physical tangled function of the epoxy resin carrier to the PEG segment, the composite macroscopically presents the solid-solid phase change characteristic.

  14. Surface self-diffusion behavior of individual tungsten adatoms on rhombohedral clusters

    International Nuclear Information System (INIS)

    Yang Jianyu; Hu Wangyu; Tang Jianfeng

    2011-01-01

    The diffusion of single tungsten adatoms on the surfaces of rhombohedral clusters is studied by means of molecular dynamics and the embedded atom method. The energy barriers for the adatom diffusing across and along the step edge between a {110} facet and a neighboring {110} facet are calculated using the nudged elastic band method. We notice that the tungsten adatom diffusion across the step edge has a much higher barrier than that for face-centered cubic metal clusters. The result shows that diffusion from the {110} facet to a neighboring {110} facet could not take place at low temperatures. In addition, the calculated energy barrier for an adatom diffusing along the step edge is lower than that for an adatom on the flat (110) surface. The results show that the adatom could diffuse easily along the step edge, and could be trapped by the facet corner. Taking all of this evidence together, we infer that the {110} facet starts to grow from the facet corner, and then along the step edge, and finally toward the {110} facet center. So the tungsten rhombohedron can grow epitaxially along the {110} facet one facet at a time and the rhombohedron should be the stable structure for both large and small tungsten clusters. (paper)

  15. Orientation-dependent effects of EPR-measurements on β-rhombohedral boron

    International Nuclear Information System (INIS)

    Siems, C.D.; Geist, D.

    1976-01-01

    EPR studies on β-rhombohedral boron have been reported by several authors. Two EPR-lines with the same g-value have been found by measurements with and without illumination. The microwave frequency used was 9 GHz, as far as is known. In this paper EPR-measurements at 35 GHz on β-rhombohedral boron single crystals are reported. The investigations concerning the 'dark EPR-line' were made at 300 K. (Auth.)

  16. C-Peptide Decline in Type 1 Diabetes Has Two Phases: An Initial Exponential Fall and a Subsequent Stable Phase.

    Science.gov (United States)

    Shields, Beverley M; McDonald, Timothy J; Oram, Richard; Hill, Anita; Hudson, Michelle; Leete, Pia; Pearson, Ewan R; Richardson, Sarah J; Morgan, Noel G; Hattersley, Andrew T

    2018-06-07

    The decline in C-peptide in the 5 years after diagnosis of type 1 diabetes has been well studied, but little is known about the longer-term trajectory. We aimed to examine the association between log-transformed C-peptide levels and the duration of diabetes up to 40 years after diagnosis. We assessed the pattern of association between urinary C-peptide/creatinine ratio (UCPCR) and duration of diabetes in cross-sectional data from 1,549 individuals with type 1 diabetes using nonlinear regression approaches. Findings were replicated in longitudinal follow-up data for both UCPCR ( n = 161 individuals, 326 observations) and plasma C-peptide ( n = 93 individuals, 473 observations). We identified two clear phases of C-peptide decline: an initial exponential fall over 7 years (47% decrease/year [95% CI -51%, -43%]) followed by a stable period thereafter (+0.07%/year [-1.3, +1.5]). The two phases had similar durations and slopes in patients above and below the median age at diagnosis (10.8 years), although levels were lower in the younger patients irrespective of duration. Patterns were consistent in both longitudinal UCPCR ( n = 162; ≤7 years duration: -48%/year [-55%, -38%]; >7 years duration -0.1% [-4.1%, +3.9%]) and plasma C-peptide ( n = 93; >7 years duration only: -2.6% [-6.7%, +1.5%]). These data support two clear phases of C-peptide decline: an initial exponential fall over a 7-year period, followed by a prolonged stabilization where C-peptide levels no longer decline. Understanding the pathophysiological and immunological differences between these two phases will give crucial insights into understanding β-cell survival. © 2018 by the American Diabetes Association.

  17. Linearly decoupled energy-stable numerical methods for multi-component two-phase compressible flow

    KAUST Repository

    Kou, Jisheng

    2017-12-06

    In this paper, for the first time we propose two linear, decoupled, energy-stable numerical schemes for multi-component two-phase compressible flow with a realistic equation of state (e.g. Peng-Robinson equation of state). The methods are constructed based on the scalar auxiliary variable (SAV) approaches for Helmholtz free energy and the intermediate velocities that are designed to decouple the tight relationship between velocity and molar densities. The intermediate velocities are also involved in the discrete momentum equation to ensure a consistency relationship with the mass balance equations. Moreover, we propose a component-wise SAV approach for a multi-component fluid, which requires solving a sequence of linear, separate mass balance equations. We prove that the methods have the unconditional energy-dissipation feature. Numerical results are presented to verify the effectiveness of the proposed methods.

  18. In-situ structural investigations of ferroelasticity in soft and hard rhombohedral and tetragonal PZT

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, Maxim I., E-mail: maximm@alumni.ntnu.no; Einarsrud, Mari-Ann; Tolchard, Julian R.; Grande, Tor [Department of Materials Science and Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim (Norway); Geiger, Philipp T.; Webber, Kyle G. [Department of Materials Science, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen (Germany); Damjanovic, Dragan [Ceramics Laboratory, Swiss Federal Institute of Technology in Lausanne-EPFL, 1015 Lausanne (Switzerland)

    2015-10-28

    Despite the technological importance of hard and soft PZT, Pb(Zr,Ti)O{sub 3}, ceramics, the mechanisms of ferroelectric hardening and softening remain widely discussed in the literature. The hardening and softening phenomena have traditionally been investigated in relation with dielectric manifestations such as aging of the dielectric susceptibility and constriction of the polarization-electric field hysteresis loop. Here, we present a systematic investigation of the ferroelectric and ferroelastic properties of soft and hard PZT in both the tetragonal and rhombohedral phases. A particular focus has been devoted to ferroelastic domain switching by characterizing the macroscopic mechanical constitutive behavior and in-situ synchrotron X-ray diffraction during compression. It is demonstrated that variation of the ordering state of point defects in PZT ceramics affects the switching behavior of both ferroelectric and ferroelastic domains under mechanical or electrical fields. Softening of the mechanical and electrical properties of originally hard PZT ceramics was conferred by quenching the materials from above the Curie temperature. The present findings are discussed with respect to the current understanding of hardening-softening transitions in ferroelectric materials.

  19. Generation of Phase-Stable Sub-Cycle Mid-Infrared Pulses from Filamentation in Nitrogen

    Directory of Open Access Journals (Sweden)

    Takao Fuji

    2013-02-01

    Full Text Available Sub-single-cycle pulses in the mid-infrared (MIR region were generated through a laser-induced filament. The fundamental (ω1 and second harmonic (ω2 output of a 30-fs Ti:sapphire amplifier were focused into nitrogen gas and produce phase-stable broadband MIR pulses (ω0 by using a four-wave mixing process (ω1 + ω1 - ω2 → ω0 through filamentation. The spectrum spread from 400 cm-1 to 5500 cm-1, which completely covered the MIR region. The low frequency components were detected by using an electro-optic sampling technique with a gaseous medium. The efficiency of the MIR pulse generation was very sensitive to the delay between the fundamental and second harmonic pulses. It was revealed that the delay dependence of the efficiency came from the interference between two opposite parametric processes, ω1 + ω1 - ω2 → ω0 and ω2 - ω1 - ω1 → ω0. The pulse duration was measured as 6.9 fs with cross-correlation frequency-resolved optical gating by using four-wave mixing in nitrogen. The carrier-envelope phase of the MIR pulse was passively stabilized. The instability was estimated as 154 mrad rms in 2.5 h.

  20. Right unitarity triangles, stable CP-violating phases and approximate quark-lepton complementarity

    International Nuclear Information System (INIS)

    Xing Zhizhong

    2009-01-01

    Current experimental data indicate that two unitarity triangles of the CKM quark mixing matrix V are almost the right triangles with α∼90 deg. We highlight a very suggestive parametrization of V and show that its CP-violating phase φ is nearly equal to α (i.e., φ-α∼1.1 deg.). Both φ and α are stable against the renormalizaton-group evolution from the electroweak scale M Z to a superhigh energy scale M X or vice versa, and thus it is impossible to obtain α=90 deg. at M Z from φ=90 deg. at M X . We conjecture that there might also exist a maximal CP-violating phase φ∼90 deg. in the MNS lepton mixing matrix U. The approximate quark-lepton complementarity relations, which hold in the standard parametrizations of V and U, can also hold in our particular parametrizations of V and U simply due to the smallness of |V ub | and |V e3 |.

  1. Punishment in public goods games leads to meta-stable phase transitions and hysteresis

    Science.gov (United States)

    Hintze, Arend; Adami, Christoph

    2015-07-01

    The evolution of cooperation has been a perennial problem in evolutionary biology because cooperation can be undermined by selfish cheaters who gain an advantage in the short run, while compromising the long-term viability of the population. Evolutionary game theory has shown that under certain conditions, cooperation nonetheless evolves stably, for example if players have the opportunity to punish cheaters that benefit from a public good yet refuse to pay into the common pool. However, punishment has remained enigmatic because it is costly and difficult to maintain. On the other hand, cooperation emerges naturally in the public goods game if the synergy of the public good (the factor multiplying the public good investment) is sufficiently high. In terms of this synergy parameter, the transition from defection to cooperation can be viewed as a phase transition with the synergy as the critical parameter. We show here that punishment reduces the critical value at which cooperation occurs, but also creates the possibility of meta-stable phase transitions, where populations can ‘tunnel’ into the cooperating phase below the critical value. At the same time, cooperating populations are unstable even above the critical value, because a group of defectors that are large enough can ‘nucleate’ such a transition. We study the mean-field theoretical predictions via agent-based simulations of finite populations using an evolutionary approach where the decisions to cooperate or to punish are encoded genetically in terms of evolvable probabilities. We recover the theoretical predictions and demonstrate that the population shows hysteresis, as expected in systems that exhibit super-heating and super-cooling. We conclude that punishment can stabilize populations of cooperators below the critical point, but it is a two-edged sword: it can also stabilize defectors above the critical point.

  2. Self-Assembling, Stable Photonic Bend-Gap Phases in Emulsions of Chiral Nematics with Isotropic Fluids

    Science.gov (United States)

    Huang, Chien-Yueh; Petschek, R. G.

    1998-03-01

    We investigate the possible mesophases in emulsions of chiral nematic liquid crystals with immiscible isotropic fluids and surfactants. The interactions between the orientational fields of the chiral nematics and the surfactant membranes together with the topological constraints affect stability of micellar geometries and produce a new phase diagram. We compare the free energies of various candidate phases. Appropriate, likely realizable conditions on the surfactant and the pitch of the liquid crystal result in thermodynamically stable blue-phase like phases for a relatively wide range of parameters. Processing such emulsions may result in materials with photonic band gaps.

  3. An energy-stable time-integrator for phase-field models

    KAUST Repository

    Vignal, Philippe

    2016-12-27

    We introduce a provably energy-stable time-integration method for general classes of phase-field models with polynomial potentials. We demonstrate how Taylor series expansions of the nonlinear terms present in the partial differential equations of these models can lead to expressions that guarantee energy-stability implicitly, which are second-order accurate in time. The spatial discretization relies on a mixed finite element formulation and isogeometric analysis. We also propose an adaptive time-stepping discretization that relies on a first-order backward approximation to give an error-estimator. This error estimator is accurate, robust, and does not require the computation of extra solutions to estimate the error. This methodology can be applied to any second-order accurate time-integration scheme. We present numerical examples in two and three spatial dimensions, which confirm the stability and robustness of the method. The implementation of the numerical schemes is done in PetIGA, a high-performance isogeometric analysis framework.

  4. Stable and simple quantitative phase-contrast imaging by Fresnel biprism

    Science.gov (United States)

    Ebrahimi, Samira; Dashtdar, Masoomeh; Sánchez-Ortiga, Emilio; Martínez-Corral, Manuel; Javidi, Bahram

    2018-03-01

    Digital holographic (DH) microscopy has grown into a powerful nondestructive technique for the real-time study of living cells including dynamic membrane changes and cell fluctuations in nanometer and sub-nanometer scales. The conventional DH microscopy configurations require a separately generated coherent reference wave that results in a low phase stability and a necessity to precisely adjust the intensity ratio between two overlapping beams. In this work, we present a compact, simple, and very stable common-path DH microscope, employing a self-referencing configuration. The microscope is implemented by a diode laser as the source and a Fresnel biprism for splitting and recombining the beams simultaneously. In the overlapping area, linear interference fringes with high contrast are produced. The frequency of the interference pattern could be easily adjusted by displacement of the biprism along the optical axis without a decrease in fringe contrast. To evaluate the validity of the method, the spatial noise and temporal stability of the setup are compared with the common off-axis DH microscope based on a Mach-Zehnder interferometer. It is shown that the proposed technique has low mechanical noise as well as superb temporal stability with sub-nanometer precision without any external vibration isolation. The higher temporal stability improves the capabilities of the microscope for studying micro-object fluctuations, particularly in the case of biological specimens. Experimental results are presented using red blood cells and silica microspheres to demonstrate the system performance.

  5. An energy-stable time-integrator for phase-field models

    KAUST Repository

    Vignal, Philippe; Collier, N.; Dalcin, Lisandro; Brown, D.L.; Calo, V.M.

    2016-01-01

    We introduce a provably energy-stable time-integration method for general classes of phase-field models with polynomial potentials. We demonstrate how Taylor series expansions of the nonlinear terms present in the partial differential equations of these models can lead to expressions that guarantee energy-stability implicitly, which are second-order accurate in time. The spatial discretization relies on a mixed finite element formulation and isogeometric analysis. We also propose an adaptive time-stepping discretization that relies on a first-order backward approximation to give an error-estimator. This error estimator is accurate, robust, and does not require the computation of extra solutions to estimate the error. This methodology can be applied to any second-order accurate time-integration scheme. We present numerical examples in two and three spatial dimensions, which confirm the stability and robustness of the method. The implementation of the numerical schemes is done in PetIGA, a high-performance isogeometric analysis framework.

  6. A gradient stable scheme for a phase field model for the moving contact line problem

    KAUST Repository

    Gao, Min

    2012-02-01

    In this paper, an efficient numerical scheme is designed for a phase field model for the moving contact line problem, which consists of a coupled system of the Cahn-Hilliard and Navier-Stokes equations with the generalized Navier boundary condition [1,2,4]. The nonlinear version of the scheme is semi-implicit in time and is based on a convex splitting of the Cahn-Hilliard free energy (including the boundary energy) together with a projection method for the Navier-Stokes equations. We show, under certain conditions, the scheme has the total energy decaying property and is unconditionally stable. The linearized scheme is easy to implement and introduces only mild CFL time constraint. Numerical tests are carried out to verify the accuracy and stability of the scheme. The behavior of the solution near the contact line is examined. It is verified that, when the interface intersects with the boundary, the consistent splitting scheme [21,22] for the Navier Stokes equations has the better accuracy for pressure. © 2011 Elsevier Inc.

  7. Observation of ferromagnetic ordering in a stable α -Co (OH) 2 phase grown on a Mo S2 surface

    Science.gov (United States)

    Debnath, Anup; Bhattacharya, Shatabda; Saha, Shyamal K.

    2017-12-01

    Because of the potential application of Co (OH) 2 in a magnetic cooling system as a result of its superior magnetocaloric effect many people have investigated magnetic properties of Co (OH) 2 . Unfortunately, most of the works have been carried out on the β -Co (OH) 2 phase due to the fact that the α -Co (OH) 2 phase is very unstable and continuously transformed into the stable β -Co (OH) 2 phase. However, in the present work, using a Mo S2 sheet as a two-dimensional template, we have been able to synthesize a stable α -Co (OH) 2 phase in addition to a β -Co (OH) 2 phase by varying the layer thickness. It is seen that for thinner samples the β phase, while for thicker samples α phase, is grown on the Mo S2 surface. Magnetic measurements are carried out for the samples over the temperature range from 2 to 300 K and it is seen that for the β phase, ferromagnetic ordering with fairly large coercivity (1271 Oe) at 2 K is obtained instead of the usual antiferromagnetism. The most interesting result is the observation of ferromagnetic ordering with a transition temperature (Curie temperature) more than 100 K in the α -Co (OH) 2 phase. Complete saturation in the hysteresis curve under application of very low field having coercivity of ˜162 Oe at 2 K and 60 Oe at 50 K is obtained. A thin stable α -Co (OH) 2 phase grown on Mo S2 surface with very soft ferromagnetic ordering will be very useful as the core material in electromagnets.

  8. Lightweight Thermally Stable Multi-Meter Aperture Submillimeter Reflectors, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Future astrophysics missions will require lightweight, thermally stable, submillimeter reflectors in sizes of 4m and greater. To date, graphite fiber reinforced...

  9. A stable algorithm for calculating phase equilibria with capillarity at specified moles, volume and temperature using a dynamic model

    KAUST Repository

    Kou, Jisheng

    2017-09-30

    Capillary pressure can significantly affect the phase properties and flow of liquid-gas fluids in porous media, and thus, the phase equilibrium calculation incorporating capillary pressure is crucial to simulate such problems accurately. Recently, the phase equilibrium calculation at specified moles, volume and temperature (NVT-flash) becomes an attractive issue. In this paper, capillarity is incorporated into the phase equilibrium calculation at specified moles, volume and temperature. A dynamical model for such problem is developed for the first time by using the laws of thermodynamics and Onsager\\'s reciprocal principle. This model consists of the evolutionary equations for moles and volume, and it can characterize the evolutionary process from a non-equilibrium state to an equilibrium state in the presence of capillarity effect at specified moles, volume and temperature. The phase equilibrium equations are naturally derived. To simulate the proposed dynamical model efficiently, we adopt the convex-concave splitting of the total Helmholtz energy, and propose a thermodynamically stable numerical algorithm, which is proved to preserve the second law of thermodynamics at the discrete level. Using the thermodynamical relations, we derive a phase stability condition with capillarity effect at specified moles, volume and temperature. Moreover, we propose a stable numerical algorithm for the phase stability testing, which can provide the feasible initial conditions. The performance of the proposed methods in predicting phase properties under capillarity effect is demonstrated on various cases of pure substance and mixture systems.

  10. Approaches to understanding the semi-stable phase of litter decomposition

    Science.gov (United States)

    Preston, C. M.; Trofymow, J. A.

    2012-12-01

    The slowing or even apparent cessation of litter decomposition with time has been widely observed, but causes remain poorly understood. We examine the question in part through data from CIDET (the Canadian Intersite Decomposition Experiment) for 10 foliar litters at one site with MAT 6.7 degrees C. The initial rapid C loss in the first year for some litters is followed by a second phase (1-7y) with decay rates from 0.21-0.79/y, influenced by initial litter chemistry especially the ratio AUR/N (acid-unhydrolyzable residue, negative). By contrast, 10-23% of the initial litter C mass entered the semi-stable decay phase (>7 y) with modeled decay rates of 0.0021-0.0035/y. The slowing and convergence of k values was similar to trends in chemical composition. From 7-12 y, concentrations of Ca, Mg, K, P, Mn and Zn generally declined and became more similar among litters, and total N converged around 20 mg/g. Non-polar and water-soluble extractables and acid solubles continued to decrease slowly and AUR to increase. Solid-state C-13 NMR showed continuing slight declines in O- and di-O-alkyl C and increases in alkyl, methoxyl, aryl and carboxyl C. CIDET and other studies now clearly show that lignin is not selectively preserved, and that AUR is not a measure of foliar lignin as it includes components from condensed tannins and long-chain alkyl C. Interaction with soil minerals strongly enhances soil C stabilization, but what slows decomposition so much in organic horizons? The role of inherent "chemical recalcitrance" or possible formation of new covalent bonds is hotly debated in soil science, but increasingly complex or random molecular structures no doubt present greater challenges to enzymes. A relevant observation from soils and geochemistry is that decomposition results in a decline in individual compounds that can be identified from chemical analysis and a corresponding increase in the "molecularly uncharacterizable component" (MUC). Long-term declines in Ca, Mg, K

  11. Stable water isotope simulation by current land-surface schemes:Results of IPILPS phase 1

    Energy Technology Data Exchange (ETDEWEB)

    Henderson-Sellers, A.; Fischer, M.; Aleinov, I.; McGuffie, K.; Riley, W.J.; Schmidt, G.A.; Sturm, K.; Yoshimura, K.; Irannejad, P.

    2005-10-31

    Phase 1 of isotopes in the Project for Intercomparison of Land-surface Parameterization Schemes (iPILPS) compares the simulation of two stable water isotopologues ({sup 1}H{sub 2} {sup 18}O and {sup 1}H{sup 2}H{sup 16}O) at the land-atmosphere interface. The simulations are off-line, with forcing from an isotopically enabled regional model for three locations selected to offer contrasting climates and ecotypes: an evergreen tropical forest, a sclerophyll eucalypt forest and a mixed deciduous wood. Here we report on the experimental framework, the quality control undertaken on the simulation results and the method of intercomparisons employed. The small number of available isotopically-enabled land-surface schemes (ILSSs) limits the drawing of strong conclusions but, despite this, there is shown to be benefit in undertaking this type of isotopic intercomparison. Although validation of isotopic simulations at the land surface must await more, and much more complete, observational campaigns, we find that the empirically-based Craig-Gordon parameterization (of isotopic fractionation during evaporation) gives adequately realistic isotopic simulations when incorporated in a wide range of land-surface codes. By introducing two new tools for understanding isotopic variability from the land surface, the Isotope Transfer Function and the iPILPS plot, we show that different hydrological parameterizations cause very different isotopic responses. We show that ILSS-simulated isotopic equilibrium is independent of the total water and energy budget (with respect to both equilibration time and state), but interestingly the partitioning of available energy and water is a function of the models' complexity.

  12. Determining the most stable breathing phase for respiratory gating using velocity deformable registration in patients with lung cancer

    International Nuclear Information System (INIS)

    Aarons, Y.; Wightman, F.; Roxby, P.; Kron, T.

    2011-01-01

    Full text: Respiratory gated radiotherapy is a high-precision technique where the treatment beam is turned on during a predetermined phase of the breathing cycle in order to minimise dose to surrounding healthy dose sensitive structures. We aim to compare inspiration and expiration phases to determine which is more stable in the breathing cycle to perform respiratory gating. Methods Nine patients underwent a planning time resolved 4DCT (Philips Brilliance 16-multislice widebore) and repeat 4DCT during weeks I, 3 and 5 of a radical course of radiotherapy for lung cancer. Inspiration scans were co-registered to the same phase image of the original planning CT using rigid and then deformable registration with Velocity software. The process was repeated for scans at exhalation phase. The deformation matrix for the diaphragm was used to compare the reproducibility of breathing phases. In the majority of patients (seven of nine) the expiration phase was found to be the more stable compared with inspiration. The maximum diaphragm displacement exceeded 3 cm in one case for the registered inhalation images while the deformation was typically half of that in the exhalation images. Interestingly, several patients showed significant differences in deformation for the left and right diaphragm. Conclusions In a group of lung cancer patients we found the expiration phase to be more reproducible for delivering respiratory gated RT, when compared with inspiration.

  13. Pure zero-dimensional Cs4PbBr6 single crystal rhombohedral microdisks with high luminescence and stability.

    Science.gov (United States)

    Zhang, Haihua; Liao, Qing; Wu, Yishi; Chen, Jianwei; Gao, Qinggang; Fu, Hongbing

    2017-11-08

    Zero-dimensional (0D) perovskite Cs 4 PbBr 6 has been speculated to be an efficient solid-state emitter, exhibiting strong luminescense on achieving quantum confinement. Although several groups have reported strong green luminescence from Cs 4 PbBr 6 powders and nanocrystals, doubts that the origin of luminescence comes from Cs 4 PbBr 6 itself or CsPbBr 3 impurities have been a point of controversy in recent investigations. Herein, we developed a facile one-step solution self-assembly method to synthesize pure zero-dimensional rhombohedral Cs 4 PbBr 6 micro-disks (MDs) with a high PLQY of 52% ± 5% and photoluminescence full-width at half maximum (FWHM) of 16.8 nm. The obtained rhombohedral MDs were high quality single-crystalline as demonstrated by XRD and SAED patterns. We demonstrated that Cs 4 PbBr 6 MDs and CsPbBr 3 MDs were phase-separated from each other and the strong green emission comes from Cs 4 PbBr 6 . Power and temperature dependence spectra evidenced that the observed strong green luminescence of pure Cs 4 PbBr 6 MDs originated from direct exciton recombination in the isolated octahedra with a large binding energy of 303.9 meV. Significantly, isolated PbBr 6 4- octahedra separated by a Cs + ion insert in the crystal lattice is beneficial to maintaining the structural stability, depicting superior thermal and anion exchange stability. Our study provides an efficient approach to obtain high quality single-crystalline Cs 4 PbBr 6 MDs with highly efficient luminescence and stability for further optoelectronic applications.

  14. Development of high resolution Michelson interferometer for stable phase-locked ultrashort pulse pair generation.

    Science.gov (United States)

    Okada, Takumi; Komori, Kazuhiro; Goshima, Keishiro; Yamauchi, Shohgo; Morohashi, Isao; Sugaya, Takeyoshi; Ogura, Mutsuo; Tsurumachi, Noriaki

    2008-10-01

    We developed a high resolution Michelson interferometer with a two-frequency He-Ne laser positioning system in order to stabilize the relative phase of a pulse pair. The control resolution corresponded to a 12 as time resolution or a phase of 1.5 degrees at 900 nm. This high resolution Michelson interferometer can generate a phase-locked pulse pair either with a specific relative phase such as 0 or pi radians or with an arbitrary phase. Coherent control of an InAs self-assembled quantum dot was demonstrated using the high resolution Michelson interferometer with a microspectroscopy system.

  15. Unconditionally energy stable numerical schemes for phase-field vesicle membrane model

    Science.gov (United States)

    Guillén-González, F.; Tierra, G.

    2018-02-01

    Numerical schemes to simulate the deformation of vesicles membranes via minimizing the bending energy have been widely studied in recent times due to its connection with many biological motivated problems. In this work we propose a new unconditionally energy stable numerical scheme for a vesicle membrane model that satisfies exactly the conservation of volume constraint and penalizes the surface area constraint. Moreover, we extend these ideas to present an unconditionally energy stable splitting scheme decoupling the interaction of the vesicle with a surrounding fluid. Finally, the well behavior of the proposed schemes are illustrated through several computational experiments.

  16. Preparation and flammability of high density polyethylene/paraffin/organophilic montmorillonite hybrids as a form stable phase change material

    International Nuclear Information System (INIS)

    Cai, Yibing; Hu, Yuan; Song, Lei; Kong, Qinghong; Yang, Rui; Zhang, Yinping; Chen, Zuyao; Fan, Weicheng

    2007-01-01

    A kind of form stable phase change material (PCM) based on high density polyethylene (HDPE), paraffin, organophilic montmorillonite (OMT) and intumescent flame retardant (IFR) hybrids is prepared by using a twin screw extruder technique. This kind of form stable PCM is made of paraffin as a dispersed phase change material and HDPE as a supporting material. The structure of the montmorillonite (MMT) and OMT is characterized by X-ray diffraction (XRD) and high resolution electron microscopy (HREM). The analysis indicates that the MMT is a kind of lamellar structure, and the structure does not change after organic modification. However, the structure of the hybrid is evidenced by the XRD and scanning electronic microscope (SEM). Its thermal stability, latent heat and flame retardant properties are given by the Thermogravimetry analysis (TGA), differential scanning calorimeter (DSC) method and cone calorimeter, respectively. Synergy is observed between the OMT and IFR. The XRD result indicates that the paraffin intercalates into the silicate layers of the OMT, thus forming a typically intercalated hybrid. The SEM investigation and DSC result show that the additives of OMT and IFR have hardly any effect on the HDPE/paraffin three dimensional netted structure and the latent heat. In TGA curves, although the onset of weight loss of flame-retardant form stable PCMs occur at a lower temperature than that of form stable PCM, flame-retardant form stable PCMs produce a large amount of char residue at 700 o C. The synergy between OMT and IFR leads to the decrease of the heat release rate (HRR), contributing to improvement of the flammability performance

  17. Preparation and characterization of form-stable paraffin/polyurethane composites as phase change materials for thermal energy storage

    International Nuclear Information System (INIS)

    Chen, Keping; Yu, Xuejiang; Tian, Chunrong; Wang, Jianhua

    2014-01-01

    Highlights: • Paraffin/polyurethane composite as form-stable phase change material was prepared by bulk polymerization. • Paraffin/polyurethane composite possesses typical character of dual phase transition. • Total latent heat of n-eicosane/PUPCM is as high as 141.2 J/g. • Maximum encapsulation ratio for n-octadecane/PUPCM composites is 25% w/w. - Abstract: Polyurethane phase change material (PUPCM) has been demonstrated to be effective solid–solid phase change material for thermal energy storage. However, the high cost and complex process on preparation of PUPCMs with high enthalpy and broad phase transition temperature range can prohibit industrial-scale applications. In this work, a series of novel form-stable paraffin/PUPCMs composites (n-octadecane/PUPCM, n-eicosane/PUPCM and paraffin wax/PUPCM) with high enthalpy and broad phase transition temperature range (20–65 °C) were directly synthesized via bulk polymerization. The composites were prepared at different mass fractions of n-octadecane (10, 20, 25, 30% w/w). The results indicated that the maximum encapsulation ratio for n-octadecane/PUPCM10000 composites was around 25% w/w. The chemical structure and crystalline properties of these composites were characterized by Fourier transform infrared spectroscopy (FT-IR), polarizing optical microscopy (POM), wide-angle X-ray diffraction (WAXD). Thermal properties and thermal reliability of the composites were determined using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). From DSC analysis, the composites showed a typical dual phase change temperature. The enthalpy for the composite with 25% w/w n-eicosane was as high as 141.2 J/g. TGA analysis indicated that the composites degraded at considerably high temperatures. The process of preparation of PUPCMs and their composites was very simple, inexpensive, environmental friendly and easy to process into desired shapes, which could find the promising applications in solar

  18. Phase-locked 3D3C-MRV measurements in a bi-stable fluidic oscillator

    Science.gov (United States)

    Wassermann, Florian; Hecker, Daniel; Jung, Bernd; Markl, Michael; Seifert, Avi; Grundmann, Sven

    2013-03-01

    In this work, the phase-resolved internal flow of a bi-stable fluidic oscillator was measured using phase-locked three-dimensional three-components magnetic resonance velocimetry (3D3C-MRV), also termed as 4D-MRV. A bi-stable fluidic oscillator converts a continuous inlet-mass flow into a jet alternating between two outlet channels and, as a consequence provides an unsteady, periodic flow. This actuator can therefore be used as flow-control actuator. Since data acquisition in a 3D volume takes up to several minutes, only a small portion of the data is acquired in each flow cycle for every time point of the flow cycle. The acquisition of the entire data set is segmented over many cycles of the periodic flow. This procedure allows to measure phase-averaged 3D3C velocity fields with a certain temporal resolution. However, the procedure requires triggering to the periodic nature of the flow. Triggering the MR scanner precisely on each flow cycle is one of the key issues discussed in this manuscript. The 4D-MRV data are compared to data measured using phase-locked laser Doppler anemometry and good agreement between the results is found. The validated 4D-MRV data is analyzed and the fluid-mechanic features and processes inside the fluidic oscillator are investigated and described, providing a detailed description of the internal jet-switching mechanism.

  19. Electron paramagnetic resonance investigations of carbon-doped β rhombohedral boron

    International Nuclear Information System (INIS)

    Gercke, U.; Siems, C.-D.

    1979-01-01

    Electron paramagnetic resonance (EPR) measurements at 9 and 35 GHz on polycrystalline β rhombohedral boron with various carbon contents resulted in partly resolved absorption spectra. At 300 K the spin density ratio of two lines (called D and E) showed a linear increase with the carbon content. This ratio is temperature dependent. The lines D and E are photo-EPR active with different quantum efficiencies at various temperatures. (Auth.)

  20. Chemically and Thermally Stable High Energy Density Silicone Composites, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Thermal energy storage systems with 300 -- 1000 kJ/kg energy density through either phase changes or chemical heat absorption are sought by NASA. This proposed...

  1. Liquid-Vapor Phase Transition: Thermomechanical Theory, Entropy Stable Numerical Formulation, and Boiling Simulations

    Science.gov (United States)

    2015-05-01

    vapor bubbles may generate near blades [40]. This is the phenomenon of cavitation and it is still a limiting factor for ship propeller design. Phase...van der Waals theory with hydrodynamics [39]. The fluid equations based on the van der Waals theory are called the Navier-Stokes-Korteweg equations... cavitating flows, the liquid- vapor phase transition induced by pressure variations. A potential challenge for such a simulation is a proper design of open

  2. Anharmonicity and Disorder in the Black Phases of Cesium Lead Iodide Used for Stable Inorganic Perovskite Solar Cells.

    Science.gov (United States)

    Marronnier, Arthur; Roma, Guido; Boyer-Richard, Soline; Pedesseau, Laurent; Jancu, Jean-Marc; Bonnassieux, Yvan; Katan, Claudine; Stoumpos, Constantinos C; Kanatzidis, Mercouri G; Even, Jacky

    2018-04-24

    Hybrid organic-inorganic perovskites emerged as a new generation of absorber materials for high-efficiency low-cost solar cells in 2009. Very recently, fully inorganic perovskite quantum dots also led to promising efficiencies, making them a potentially stable and efficient alternative to their hybrid cousins. Currently, the record efficiency is obtained with CsPbI 3 , whose crystallographical characterization is still limited. Here, we show through high-resolution in situ synchrotron XRD measurements that CsPbI 3 can be undercooled below its transition temperature and temporarily maintained in its perovskite structure down to room temperature, stabilizing a metastable perovskite polytype (black γ-phase) crucial for photovoltaic applications. Our analysis of the structural phase transitions reveals a highly anisotropic evolution of the individual lattice parameters versus temperature. Structural, vibrational, and electronic properties of all the experimentally observed black phases are further inspected based on several theoretical approaches. Whereas the black γ-phase is shown to behave harmonically around equilibrium, for the tetragonal phase, density functional theory reveals the same anharmonic behavior, with a Brillouin zone-centered double-well instability, as for the cubic phase. Using total energy and vibrational entropy calculations, we highlight the competition between all the low-temperature phases of CsPbI 3 (γ, δ, β) and show that avoiding the order-disorder entropy term arising from double-well instabilities is key to preventing the formation of the yellow perovskitoid phase. A symmetry-based tight-binding model, validated by self-consistent GW calculations including spin-orbit coupling, affords further insight into their electronic properties, with evidence of Rashba effect for both cubic and tetragonal phases when using the symmetry-breaking structures obtained through frozen phonon calculations.

  3. Growth of rhombohedral insulin crystals and in vitro modeling of their dissolution in the blood stream

    Energy Technology Data Exchange (ETDEWEB)

    Nanev, C.N.; Dimitrov, I.L.; Hodzhaoglu, F.V. [Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Sofia (Bulgaria)

    2011-02-15

    Insulin is the only protein that is secreted in a crystalline form in a human healthy body. To mimic the secretion process we used NaCl salting-out to growing tiny rhombohedral Zn-insulin crystals. The dissolution of the insulin crystals is of special interest for the therapeutical praxis, because the human body is supplied with the physiologically active monomers of the insulin through dissolution of the crystalline granules secreted in the pancreatic {beta}-cells. Sets of tiny rhombohedral Zn-insulin crystals, which resembled the granules secreted in the {beta}-cells, were subjected to dissolution in blood plasma and model solutions. The impacts of the solution composition, flow rate, pH and ionic strength on the insulin crystal dissolution were investigated. The effect of the blood plasma was determinant because it dissolved the rhombohedral Zn-insulin crystals almost instantly, while the effects of solution's physicochemical characteristics were of minor importance. In addition, we found that the presence of abundant zinc ions suppressed the dissolution of the insulin crystals. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Phase-sensitive optical coherence tomography-based vibrometry using a highly phase-stable akinetic swept laser source

    Energy Technology Data Exchange (ETDEWEB)

    Applegate, Brian E.; Park, Jesung; Carbajal, Esteban [Department of Biomedical Engineering, Texas A& M University, College Station, Texas (United States); Oghalai, John S. [Department of Otolaryngology - Head and Neck Surgery, Stanford University, Stanford, California (United States)

    2015-12-31

    Phase-sensitive Optical Coherence Tomography (PhOCT) is an emerging tool for in vivo investigation of the vibratory function of the intact middle and inner ear. PhOCT is able to resolve micron scale tissue morphology in three dimensions as well as measure picometer scale motion at each spatial position. Most PhOCT systems to date have relied upon the phase stability offered by spectrometer detection. On the other hand swept laser source based PhOCT offers a number of advantages including balanced detection, long imaging depths, and high imaging speeds. Unfortunately the inherent phase instability of traditional swept laser sources has necessitated complex user developed hardware/software solutions to restore phase sensitivity. Here we present recent results using a prototype swept laser that overcomes these issues. The akinetic swept laser is electronically tuned and precisely controls sweeps without any mechanical movement, which results in high phase stability. We have developed an optical fiber based PhOCT system around the akinetic laser source that had a 1550 nm center wavelength and a sweep rate of 140 kHz. The stability of the system was measured to be 4.4 pm with a calibrated reflector, thus demonstrating near shot noise limited performance. Using this PhOCT system, we have acquired structural and vibratory measurements of the middle ear in a mouse model, post mortem. The quality of the results suggest that the akinetic laser source is a superior laser source for PhOCT with many advantages that greatly reduces the required complexity of the imaging system.

  5. Data acquisition and quantitative analysis of stable hydrogen isotope in liquid and gas in the liquid phase catalytic exchange process

    International Nuclear Information System (INIS)

    Choi, H. J.; Lee, H. S.; Kim, K. R.; Cheong, H. S.; Ahn, D. H.; Lee, S. H.; Paek, S. W.; Kang, H. S.; Kim, J. G.

    2001-01-01

    A pilot plant for the Liquid Phase Catalytic Exchange process was built and has been operating to test the hydrophobic catalyst developed to remove the tritium generated at the CANDU nuclear power plants. The methods of quantitative analysis of hydrogen stable isotope were compared. Infrared spectroscopy was used for the liquid samples, and gas chromatography with hydrogen carrier gas showed the best result for gas samples. Also, a data acquisition system was developed to record the operation parameters. This record was very useful to investigate the causes of the system trip

  6. The existence of a stable noncollinear phase in a Heisenberg model with complex structure

    Energy Technology Data Exchange (ETDEWEB)

    Shopova, Diana V.; Boyadjiev, Todor L

    2003-05-19

    We have analyzed the properties of a noncollinear magnetic phase obtained in the mean-field analysis of the model of two coupled Heisenberg subsystems. The domain of its existence and stability is narrow and depends on the ratio between the averaged over nearest neighbours microscopic exchange parameters.

  7. Experimental Study of Stable Surfaces for Anti-Slug Control in Multi-phase Flow

    DEFF Research Database (Denmark)

    Pedersen, Simon; Løhndorf, Petar Durdevic; Yang, Zhenyu

    2014-01-01

    -phase flow dynamics, the slug can be avoided or eliminated by proper facility design and control of operational conditions. Based on a testing facility which can emulate a pipeline-riser or a gas-lifted production well in a scaled-down manner, this paper experimentally studies the correlations of key...

  8. Liquid phase mass production of air-stable black phosphorus/phospholipids nanocomposite with ultralow tunneling barrier

    Science.gov (United States)

    Zhang, Qiankun; Liu, Yinan; Lai, Jiawei; Qi, Shaomian; An, Chunhua; Lu, Yao; Duan, Xuexin; Pang, Wei; Zhang, Daihua; Sun, Dong; Chen, Jian-Hao; Liu, Jing

    2018-04-01

    Few-layer black phosphorus (FLBP), a recently discovered two-dimensional semiconductor, has attracted substantial attention in the scientific and technical communities due to its great potential in electronic and optoelectronic applications. However, reactivity of FLBP flakes with ambient species limits its direct applications. Among various methods to passivate FLBP in ambient environment, nanocomposites mixing FLBP flakes with stable matrix may be one of the most promising approaches for industry applications. Here, we report a simple one-step procedure to mass produce air-stable FLBP/phospholipids nanocomposite in liquid phase. The resultant nanocomposite is found to have ultralow tunneling barrier for charge carriers which can be described by an Efros-Shklovskii variable range hopping mechanism. Devices made from such mass-produced FLBP/phospholipids nanocomposite show highly stable electrical conductivity and opto-electrical response in ambient conditions, indicating its promising applications in both electronic and optoelectronic applications. This method could also be generalized to the mass production of nanocomposites consisting of other air-sensitive 2D materials, such as FeSe, NbSe2, WTe2, etc.

  9. Preparation and thermal energy storage properties of paraffin/calcined diatomite composites as form-stable phase change materials

    International Nuclear Information System (INIS)

    Sun, Zhiming; Zhang, Yuzhong; Zheng, Shuilin; Park, Yuri; Frost, Ray L.

    2013-01-01

    Highlights: ► Composite phase change material (PCM) was prepared by blending composite paraffin and calcined diatomite. ► The optimum mixed proportion was obtained through differential scanning calorimetry. ► Thermal energy storage properties of the composite PCMs were determined by DSC. ► Thermal cycling test showed that the prepared PCMs are thermally reliable and chemically stable. - Abstract: A composite paraffin-based phase change material (PCM) was prepared by blending composite paraffin and calcined diatomite through the fusion adsorption method. In this study, raw diatomite was purified by thermal treatment in order to improve the adsorption capacity of diatomite, which acted as a carrier material to prepare shape-stabilized PCMs. Two forms of paraffin (paraffin waxes and liquid paraffin) with different melting points were blended together by the fusion method, and the optimum mixed proportion with a suitable phase-transition temperature was obtained through differential scanning calorimetry (DSC) analysis. Then the prepared composite paraffin was adsorbed in calcined diatomite. The prepared paraffin/calcined diatomite composites were characterized by the scanning electron microscope (SEM) and Fourier transformation infrared (FT-IR) analysis techniques. Thermal energy storage properties of the composite PCMs were determined by DSC method. DSC results showed that there was an optimum adsorption ratio between composite paraffin and calcined diatomite and the phase-transition temperature and the latent heat of the composite PCMs were 33.04 °C and 89.54 J/g, respectively. Thermal cycling test of composite PCMs showed that the prepared material is thermally reliable and chemically stable. The obtained paraffin/calcined diatomite composites have proper latent heat and melting temperatures, and show practical significance and good potential application value

  10. Development of form stable Poly(methyl methacrylate) (PMMA) coated thermal phase change material for solar water heater applications

    Science.gov (United States)

    Munusamy, Y.; Shanmugam, S.; Shi-Ying, Kee

    2018-04-01

    Phase change material (PCM) is one of the most popular and widely used thermal energy storage material in solar water heater because it able to absorb and release a large amount of latent heat during a phase change process over a narrow temperature range. However the practical application of PCM is limited by two major issues; 1) leakage which leads to material loss and corrosion of tank and 2) large volume change during phase change process which cause pressure build up in the tank. In this work, form-stable PCM was prepared by coating myristic acid with Poly(methyl methacrylate) (PMMA) to prevent leakage of PCM. PMMA was mixed with different weight percentage (0.1, 0.2, 0.3, 0.4 and 0.5 wt%) of dicumyl peroxide (DCP). The purpose of adding DCP to PMMA is to crosslink the polymer and to increase the mechanical strength of PMMA to hold the myristic acid content inside the coating during the phase change process. Leakage test results showed that PMMA mixed with 0.1% DCP exhibit 0% leakage. This result is further supported by Field Emission Scanning Electron Microscopy (FESEM) images and Fourier transform infrared spectroscopy (FTIR) analysis results, where a compact and uniform coating without cracks were formed for PCM coated with PMMA with 0.1% DCP. Differential scanning calorimetry (DSC) results shows that the melting point of form-stable PCM is 55°C, freezing point is 50°C, the latent heat of melting and freezing is 67.59 J/g.

  11. Preparation and thermal energy storage properties of paraffin/calcined diatomite composites as form-stable phase change materials

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Zhiming [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Zhang, Yuzhong [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Zheng, Shuilin, E-mail: shuilinzh@yahoo.com.cn [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Park, Yuri [Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Frost, Ray L., E-mail: r.frost@qut.edu.au [Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001 (Australia)

    2013-04-20

    Highlights: ► Composite phase change material (PCM) was prepared by blending composite paraffin and calcined diatomite. ► The optimum mixed proportion was obtained through differential scanning calorimetry. ► Thermal energy storage properties of the composite PCMs were determined by DSC. ► Thermal cycling test showed that the prepared PCMs are thermally reliable and chemically stable. - Abstract: A composite paraffin-based phase change material (PCM) was prepared by blending composite paraffin and calcined diatomite through the fusion adsorption method. In this study, raw diatomite was purified by thermal treatment in order to improve the adsorption capacity of diatomite, which acted as a carrier material to prepare shape-stabilized PCMs. Two forms of paraffin (paraffin waxes and liquid paraffin) with different melting points were blended together by the fusion method, and the optimum mixed proportion with a suitable phase-transition temperature was obtained through differential scanning calorimetry (DSC) analysis. Then the prepared composite paraffin was adsorbed in calcined diatomite. The prepared paraffin/calcined diatomite composites were characterized by the scanning electron microscope (SEM) and Fourier transformation infrared (FT-IR) analysis techniques. Thermal energy storage properties of the composite PCMs were determined by DSC method. DSC results showed that there was an optimum adsorption ratio between composite paraffin and calcined diatomite and the phase-transition temperature and the latent heat of the composite PCMs were 33.04 °C and 89.54 J/g, respectively. Thermal cycling test of composite PCMs showed that the prepared material is thermally reliable and chemically stable. The obtained paraffin/calcined diatomite composites have proper latent heat and melting temperatures, and show practical significance and good potential application value.

  12. Compact and highly stable quantum dots through optimized aqueous phase transfer

    Science.gov (United States)

    Tamang, Sudarsan; Beaune, Grégory; Poillot, Cathy; De Waard, Michel; Texier-Nogues, Isabelle; Reiss, Peter

    2011-03-01

    A large number of different approaches for the aqueous phase transfer of quantum dots have been proposed. Surface ligand exchange with small hydrophilic thiols, such as L-cysteine, yields the lowest particle hydrodynamic diameter. However, cysteine is prone to dimer formation, which limits colloidal stability. We demonstrate that precise pH control during aqueous phase transfer dramatically increases the colloidal stability of InP/ZnS quantum dots. Various bifunctional thiols have been applied. The formation of disulfides, strongly diminishing the fluorescence QY has been prevented through addition of appropriate reducing agents. Bright InP/ZnS quantum dots with a hydrodynamic diameter <10 nm and long-term stability have been obtained. Finally we present in vitro studies of the quantum dots functionalized with the cell-penetrating peptide maurocalcine.

  13. Phase behavior and structure of stable complexes between a long polyanion and a branched polycation

    Science.gov (United States)

    Mengarelli, Valentina; Zeghal, Mehdi; Auvray, Loïc; Clemens, Daniel

    2011-08-01

    The association between oppositely charged branched polyethylenimine (BPEI) and polymethacrylic acid (PMA) in the dilute regime is investigated using turbidimetric titration and electrophoretic mobility measurements. The complexation is controlled by tuning continuously the pH-sensitive charge of the polyacid in acidic solution. The formation of soluble and stable positively charged complexes is a cooperative process characterized by the existence of two regimes of weak and strong complexation. In the regime of weak complexation, a long PMA chain overcharged by several BPEI molecules forms a binary complex. As the charge of the polyacid increases, these binary complexes condense at a well defined charge ratio of the mixture to form large positively charged aggregates. The overcharging and the existence of two regimes of complexation are analyzed in the light of recent theories. The structure of the polyelectrolytes is investigated at higher polymer concentration by small angle neutron scattering. Binary complexes of finite size present an open structure where the polyacid chains connecting a small number of BPEI molecules have shrunk slightly. In the condensed complexes, BPEI molecules, wrapped by polyacid chains, form networks of stretched necklaces.

  14. An energy-stable convex splitting for the phase-field crystal equation

    KAUST Repository

    Vignal, P.; Dalcin, L.; Brown, D. L.; Collier, N.; Calo, V. M.

    2015-01-01

    Abstract The phase-field crystal equation, a parabolic, sixth-order and nonlinear partial differential equation, has generated considerable interest as a possible solution to problems arising in molecular dynamics. Nonetheless, solving this equation is not a trivial task, as energy dissipation and mass conservation need to be verified for the numerical solution to be valid. This work addresses these issues, and proposes a novel algorithm that guarantees mass conservation, unconditional energy stability and second-order accuracy in time. Numerical results validating our proofs are presented, and two and three dimensional simulations involving crystal growth are shown, highlighting the robustness of the method. © 2015 Elsevier Ltd.

  15. An energy-stable convex splitting for the phase-field crystal equation

    KAUST Repository

    Vignal, P.

    2015-10-01

    Abstract The phase-field crystal equation, a parabolic, sixth-order and nonlinear partial differential equation, has generated considerable interest as a possible solution to problems arising in molecular dynamics. Nonetheless, solving this equation is not a trivial task, as energy dissipation and mass conservation need to be verified for the numerical solution to be valid. This work addresses these issues, and proposes a novel algorithm that guarantees mass conservation, unconditional energy stability and second-order accuracy in time. Numerical results validating our proofs are presented, and two and three dimensional simulations involving crystal growth are shown, highlighting the robustness of the method. © 2015 Elsevier Ltd.

  16. SU(2 and SU(1,1 Approaches to Phase Operators and Temporally Stable Phase States: Applications to Mutually Unbiased Bases and Discrete Fourier Transforms

    Directory of Open Access Journals (Sweden)

    Maurice R. Kibler

    2010-07-01

    Full Text Available We propose a group-theoretical approach to the generalized oscillator algebra Aκ recently investigated in J. Phys. A: Math. Theor. 2010, 43, 115303. The case κ ≥ 0 corresponds to the noncompact group SU(1,1 (as for the harmonic oscillator and the Pöschl-Teller systems while the case κ < 0 is described by the compact group SU(2 (as for the Morse system. We construct the phase operators and the corresponding temporally stable phase eigenstates for Aκ in this group-theoretical context. The SU(2 case is exploited for deriving families of mutually unbiased bases used in quantum information. Along this vein, we examine some characteristics of a quadratic discrete Fourier transform in connection with generalized quadratic Gauss sums and generalized Hadamard matrices.

  17. Single-step gas phase synthesis of stable iron aluminide nanoparticles with soft magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Vernieres, Jerome, E-mail: Jerome.vernieres@oist.jp; Benelmekki, Maria; Kim, Jeong-Hwan; Grammatikopoulos, Panagiotis; Diaz, Rosa E. [Nanoparticles by Design Unit, Okinawa Institute of Science and Technology (OIST) Graduate University, 1919-1 Tancha, Onna Son, Okinawa 904-0495 (Japan); Bobo, Jean-François [Centre d’Elaboration de Materiaux et d’Etudes Structurales (CEMES), 29 rue Jeanne Marvig, 31055 Toulouse Cedex 4 (France); Sowwan, Mukhles, E-mail: Mukhles@oist.jp [Nanoparticles by Design Unit, Okinawa Institute of Science and Technology (OIST) Graduate University, 1919-1 Tancha, Onna Son, Okinawa 904-0495 (Japan); Nanotechnology Research Laboratory, Al-Quds University, P.O. Box 51000, East Jerusalem, Palestine (Country Unknown)

    2014-11-01

    Soft magnetic alloys at the nanoscale level have long generated a vivid interest as candidate materials for technological and biomedical purposes. Consequently, controlling the structure of bimetallic nanoparticles in order to optimize their magnetic properties, such as high magnetization and low coercivity, can significantly boost their potential for related applications. However, traditional synthesis methods stumble upon the long standing challenge of developing true nanoalloys with effective control over morphology and stability against oxidation. Herein, we report on a single-step approach to the gas phase synthesis of soft magnetic bimetallic iron aluminide nanoparticles, using a versatile co-sputter inert gas condensation technique. This method allowed for precise morphological control of the particles; they consisted of an alloy iron aluminide crystalline core (DO{sub 3} phase) and an alumina shell, which reduced inter-particle interactions and also prevented further oxidation and segregation of the bimetallic core. Remarkably, the as-deposited alloy nanoparticles show interesting soft magnetic properties, in that they combine a high saturation magnetization (170 emu/g) and low coercivity (less than 20 Oe) at room temperature. Additional functionality is tenable by modifying the surface of the particles with a polymer, to ensure their good colloidal dispersion in aqueous environments.

  18. Stable tetragonal phase and magnetic properties of Fe-doped HfO2 nanoparticles

    Science.gov (United States)

    Sales, T. S. N.; Cavalcante, F. H. M.; Bosch-Santos, B.; Pereira, L. F. D.; Cabrera-Pasca, G. A.; Freitas, R. S.; Saxena, R. N.; Carbonari, A. W.

    2017-05-01

    In this paper, the effect in structural and magnetic properties of iron doping with concentration of 20% in hafnium dioxide (HfO2) nanoparticles is investigated. HfO2 is a wide band gap oxide with great potential to be used as high-permittivity gate dielectrics, which can be improved by doping. Nanoparticle samples were prepared by sol-gel chemical method and had their structure, morphology, and magnetic properties, respectively, investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) with electron back scattering diffraction (EBSD), and magnetization measurements. TEM and SEM results show size distribution of particles in the range from 30 nm to 40 nm with small dispersion. Magnetization measurements show the blocking temperature at around 90 K with a strong paramagnetic contribution. XRD results show a major tetragonal phase (94%).

  19. Stable tetragonal phase and magnetic properties of Fe-doped HfO2 nanoparticles

    Directory of Open Access Journals (Sweden)

    T. S. N. Sales

    2017-05-01

    Full Text Available In this paper, the effect in structural and magnetic properties of iron doping with concentration of 20% in hafnium dioxide (HfO2 nanoparticles is investigated. HfO2 is a wide band gap oxide with great potential to be used as high-permittivity gate dielectrics, which can be improved by doping. Nanoparticle samples were prepared by sol-gel chemical method and had their structure, morphology, and magnetic properties, respectively, investigated by X-ray diffraction (XRD, transmission electron microscopy (TEM and scanning electron microscopy (SEM with electron back scattering diffraction (EBSD, and magnetization measurements. TEM and SEM results show size distribution of particles in the range from 30 nm to 40 nm with small dispersion. Magnetization measurements show the blocking temperature at around 90 K with a strong paramagnetic contribution. XRD results show a major tetragonal phase (94%.

  20. An energy stable evolution method for simulating two-phase equilibria of multi-component fluids at constant moles, volume and temperature

    KAUST Repository

    Kou, Jisheng; Sun, Shuyu; Wang, Xiuhua

    2016-01-01

    In this paper, we propose an energy-stable evolution method for the calculation of the phase equilibria under given volume, temperature, and moles (VT-flash). An evolution model for describing the dynamics of two-phase fluid system is based on Fick

  1. Preparation and properties of lauric acid/silicon dioxide composites as form-stable phase change materials for thermal energy storage

    International Nuclear Information System (INIS)

    Fang Guiyin; Li Hui; Liu Xu

    2010-01-01

    Form-stable lauric acid (LA)/silicon dioxide (SiO 2 ) composite phase change materials were prepared using sol-gel methods. The LA was used as the phase change material for thermal energy storage, with the SiO 2 acting as the supporting material. The structural analysis of these form-stable LA/SiO 2 composite phase change materials was carried out using Fourier transformation infrared spectroscope (FT-IR). The microstructure of the form-stable composite phase change materials was observed by a scanning electronic microscope (SEM). The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetric analysis apparatus (TGA), respectively. The SEM results showed that the LA was well dispersed in the porous network of SiO 2 . The DSC results indicated that the melting latent heat of the form-stable composite phase change material is 117.21 kJ kg -1 when the mass percentage of the LA in the SiO 2 is 64.8%. The results of the TGA showed that these materials have good thermal stability. The form-stable composite phase change materials can be used for thermal energy storage in waste heat recovery and solar heating systems.

  2. Epoxy-Based Organogels for Thermally Reversible Light Scattering Films and Form-Stable Phase Change Materials.

    Science.gov (United States)

    Puig, Julieta; Dell' Erba, Ignacio E; Schroeder, Walter F; Hoppe, Cristina E; Williams, Roberto J J

    2017-03-29

    Alkyl chains of β-hydroxyesters synthesized by the capping of terminal epoxy groups of diglycidylether of bisphenol A (DGEBA) with palmitic (C16), stearic (C18), or behenic (C22) fatty acids self-assemble forming a crystalline phase. Above a particular concentration solutions of these esters in a variety of solvents led to supramolecular (physical) gels below the crystallization temperature of alkyl chains. A form-stable phase change material (FS-PCM) was obtained by blending the ester derived from behenic acid with eicosane. A blend containing 20 wt % ester was stable as a gel up to 53 °C and exhibited a heat storage capacity of 161 J/g, absorbed during the melting of eicosane at 37 °C. Thermally reversible light scattering (TRLS) films were obtained by visible-light photopolymerization of poly(ethylene glycol) dimethacrylate-ester blends (50 wt %) in the gel state at room temperature. The reaction was very fast and not inhibited by oxygen. TRLS films consisted of a cross-linked methacrylic network interpenetrated by the supramolecular network formed by the esters. Above the melting temperature of crystallites formed by alkyl chains, the film was transparent due to the matching between refractive indices of the methacrylic network and the amorphous ester. Below the crystallization temperature, the film was opaque because of light dispersion produced by the organic crystallites uniformly dispersed in the material. Of high significance for application was the fact that the contrast ratio did not depend on heating and cooling rates.

  3. A functional form-stable phase change composite with high efficiency electro-to-thermal energy conversion

    International Nuclear Information System (INIS)

    Wu, Wenhao; Huang, Xinyu; Li, Kai; Yao, Ruimin; Chen, Renjie; Zou, Ruqiang

    2017-01-01

    Graphical abstract: The thermal conductivity of PU was enhanced to 43 times of the pristine value by encapsulation in a PGF, PU@PGF can be used for highly efficient electro-to-heat energy conversion and storage with the highest energy storage efficiency up to 85%. - Highlights: • The composite exhibits an in-situ solid-solid phase change behavior. • The enthalpy of polyurethane is enhanced within the matrix. • The thermal conductivity of the composite is 43 times as much as that of the polyurethane. • Supercooling of polyurethane is greatly reduced. • The composite is applied to cold protection as a wear layer. - Abstract: A novel solid-to-solid phase change composite brick was prepared by combination of polyurethane (PU) and pitch-based graphite foam (PGF). The carbonaceous support, which can be used for mass production, not only greatly improves the thermal conductivity but promote electro-to-heat conversion efficiency of organic phase change materials (PCMs). Our composite retained the enthalpy of PCM and exhibited a greatly reduced supercooling temperature. The novel composite was investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscope (SEM). The enthalpy of polyurethane has increased about 8.6% after infiltrating into graphite foam. The composite was very stable during thermal cycle test, and the electro-to-heat conversion efficiency achieves to 85% at lower voltages (1.5–1.8 V), which can vastly reduce energy consumption. The as-prepared composite was used in a wear layer to test its performance comparing with normal fabric.

  4. Study on thermal property of lauric–palmitic–stearic acid/vermiculite composite as form-stable phase change material for energy storage

    Directory of Open Access Journals (Sweden)

    Nan Zhang

    2015-09-01

    Full Text Available The form-stable composite phase change material of lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite was prepared by vacuum impregnation method for thermal energy storage. The maximum mass fraction of lauric–palmitic–stearic acid ternary eutectic mixture retained in vermiculite was determined as 50 wt% without melted phase change material seepage from the composite phase change material. Fourier transformation infrared spectroscope and scanning electron microscope were used to characterize the structure and morphology of the prepared lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material, and the results indicate that lauric–palmitic–stearic acid ternary eutectic mixture was well confined into the layer porous structure of vermiculite by physical reaction. The melting and freezing temperatures and latent heats were measured by differential scanning calorimeter as 31.4°C and 30.3°C, and 75.8 and 73.2 J/g, respectively. Thermal cycling test showed that there was no significant change in the thermal properties of lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material after 1000 thermal cycles. Moreover, 2 wt% expanded graphite was added to improve the thermal conductivity of lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material. All results indicated that the prepared lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material had suitable thermal properties and good thermal reliability for the application of thermal energy storage in building energy efficiency.

  5. Different magnetic properties of rhombohedral and cubic Ni2+ doped indium oxide nanomaterials

    Directory of Open Access Journals (Sweden)

    Qingbo Sun

    2011-12-01

    Full Text Available Transition metal ions doped indium oxide nanomaterials were potentially used as a kind of diluted magnetic semiconductors in transparent spintronic devices. In this paper, the influences of Ni2+ doped contents and rhombohedral or cubic crystalline structures of indium oxide on magnetic properties were investigated. We found that the magnetic properties of Ni2+ doped indium oxide could be transferred from room temperature ferromagnetisms to paramagnetic properties with increments of doped contents. Moreover, the different crystalline structures of indium oxide also greatly affected the room temperature ferromagnetisms due to different lattice constants and almost had no effects on their paramagnetic properties. In addition, both the ferromagnetic and paramagnetic properties were demonstrated to be intrinsic and not caused by impurities.

  6. Identification of stable cytotoxic factors in the gas phase extract of cigarette smoke and pharmacological characterization of their cytotoxicity.

    Science.gov (United States)

    Noya, Yoichi; Seki, Koh-Ichi; Asano, Hiroshi; Mai, Yosuke; Horinouchi, Takahiro; Higashi, Tsunehito; Terada, Koji; Hatate, Chizuru; Hoshi, Akimasa; Nepal, Prabha; Horiguchi, Mika; Kuge, Yuji; Miwa, Soichi

    2013-12-06

    Smoking is a major risk factor for atherosclerotic vascular diseases, but the mechanism for its genesis is unknown. We have recently shown that the gas phase of cigarette smoke (nicotine- and tar-free cigarette smoke extract; CSE) likely to reach the systemic circulation contains stable substances which cause cytotoxicity like plasma membrane damage and cell death in cultured cells, and also that the plasma membrane damage is caused through sequential activation of protein kinase C (PKC) and NADPH oxidase (NOX) and the resulting generation of reactive oxygen species (PKC/NOX-dependent mechanism), whereas cell death is caused through PKC/NOX-dependent and -independent mechanisms. To identify these stable substances, the CSE was prepared by passing the main-stream smoke of 10 cigarettes through a Cambridge glass fiber filter, trapping of the smoke in a vessel cooled at -80°C, and subsequent dissolution in 10ml of water. The CSE was fractionated into nine fractions using reversed-phase HPLC, and each fraction was screened for cytotoxicity in cultured cells, using propidium iodide uptake assay for cell membrane damage and MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] reduction assay for cell viability. The cytotoxicity was positive in two of the nine fractions (Fr2 and Fr5). After extraction of the active fractions into dichloromethane, GC/MS analysis identified 2-cyclopenten-1-one (CPO) in Fr5 but none in Fr2. After derivatization of the active fractions with O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine hydrochloride, GC/MS analysis identified acrolein, acetone and propionaldehyde in Fr2, and methyl vinyl ketone (MVK) in Fr5. After 4-h incubation, authentic acrolein and MVK induced concentration-dependent cytotoxicity with EC50 values of 75.9±8.2 and 47.0±8.0μM (mean±SEM; n=3), respectively, whereas acetone, propionaldehyde and CPO were without effect. However, after 24-h incubation, CPO induced concentration

  7. Phase-stable, multi-µJ femtosecond pulses from a repetition-rate tunable Ti:Sa-oscillator-seeded Yb-fiber amplifier

    Science.gov (United States)

    Saule, T.; Holzberger, S.; De Vries, O.; Plötner, M.; Limpert, J.; Tünnermann, A.; Pupeza, I.

    2017-01-01

    We present a high-power, MHz-repetition-rate, phase-stable femtosecond laser system based on a phase-stabilized Ti:Sa oscillator and a multi-stage Yb-fiber chirped-pulse power amplifier. A 10-nm band around 1030 nm is split from the 7-fs oscillator output and serves as the seed for subsequent amplification by 54 dB to 80 W of average power. The µJ-level output is spectrally broadened in a solid-core fiber and compressed to 30 fs with chirped mirrors. A pulse picker prior to power amplification allows for decreasing the repetition rate from 74 MHz by a factor of up to 4 without affecting the pulse parameters. To compensate for phase jitter added by the amplifier to the feed-forward phase-stabilized seeding pulses, a self-referencing feed-back loop is implemented at the system output. An integrated out-of-loop phase noise of less than 100 mrad was measured in the band from 0.4 Hz to 400 kHz, which to the best of our knowledge corresponds to the highest phase stability ever demonstrated for high-power, multi-MHz-repetition-rate ultrafast lasers. This system will enable experiments in attosecond physics at unprecedented repetition rates, it offers ideal prerequisites for the generation and field-resolved electro-optical sampling of high-power, broadband infrared pulses, and it is suitable for phase-stable white light generation.

  8. PEG/SiO2–Al2O3 hybrid form-stable phase change materials with enhanced thermal conductivity

    International Nuclear Information System (INIS)

    Tang, Bingtao; Wu, Cheng; Qiu, Meige; Zhang, Xiwen; Zhang, Shufen

    2014-01-01

    The thermal conductivity of form-stable PEG/SiO 2 phase change material (PCM) was enhanced by in situ doping of Al 2 O 3 using an ultrasound-assisted sol–gel method. Fourier transform infrared spectroscopy (FT-IR) was used to characterize the structure, and the crystal performance was characterized by the X-ray diffraction (XRD). Differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA) were used to determine the thermal properties. The phase change enthalpy of PEG/SiO 2 –Al 2 O 3 reached 124 J g −1 , and thermal conductivity improved by 12.8% for 3.3 wt% Al 2 O 3 in the PCM compared with PEG/SiO 2 . The hybrid PCM has excellent thermal stability and form-stable effects. - Highlights: • The PEG/SiO 2 –Al 2 O 3 hybrid form-stable phase change material (PCM) was obtained through the sol–gel method. • The inexpensive aluminum nitrate and tetraethyl orthosilicate were used as sol precursors. • This organic–inorganic hybrid process can effectively enhance the thermal conductivity of PCMs. • The PCM exhibited high thermal stability and excellent form-stable effects

  9. PEG/SiO{sub 2}–Al{sub 2}O{sub 3} hybrid form-stable phase change materials with enhanced thermal conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Bingtao, E-mail: tangbt@dlut.edu.cn; Wu, Cheng; Qiu, Meige; Zhang, Xiwen; Zhang, Shufen

    2014-03-01

    The thermal conductivity of form-stable PEG/SiO{sub 2} phase change material (PCM) was enhanced by in situ doping of Al{sub 2}O{sub 3} using an ultrasound-assisted sol–gel method. Fourier transform infrared spectroscopy (FT-IR) was used to characterize the structure, and the crystal performance was characterized by the X-ray diffraction (XRD). Differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA) were used to determine the thermal properties. The phase change enthalpy of PEG/SiO{sub 2}–Al{sub 2}O{sub 3} reached 124 J g{sup −1}, and thermal conductivity improved by 12.8% for 3.3 wt% Al{sub 2}O{sub 3} in the PCM compared with PEG/SiO{sub 2}. The hybrid PCM has excellent thermal stability and form-stable effects. - Highlights: • The PEG/SiO{sub 2}–Al{sub 2}O{sub 3} hybrid form-stable phase change material (PCM) was obtained through the sol–gel method. • The inexpensive aluminum nitrate and tetraethyl orthosilicate were used as sol precursors. • This organic–inorganic hybrid process can effectively enhance the thermal conductivity of PCMs. • The PCM exhibited high thermal stability and excellent form-stable effects.

  10. Virtual histology study of atherosclerotic plaque composition in patients with stable angina and acute phase of acute coronary syndromes without ST segment elevation

    Directory of Open Access Journals (Sweden)

    Ivanović Miloš

    2013-01-01

    Full Text Available Introduction. Rupture of vulnerable atherosclerotic plaques is the cause of most acute coronary syndromes (ACS. Postmortem studies which compared stable coronary lesions and atherosclerotic plaques in patients who have died because of ACS indicated high lipid-core content as one of the major determinants of plaque vulnerability. Objective. Our primary goal was to assess the potential relations of plaque composition determined by IVUS-VH (Intravascular Ultrasound - Virtual Histology in patients with stable angina and subjects in acute phase of ACS without ST segment elevation. Methods. The study comprised of 40 patients who underwent preintervention IVUS examination. Tissue maps were reconstructed from radio frequency data using IVUS-VH software. Results. We analyzed 53 lesions in 40 patients. Stable angina was diagnosed in 24 patients (29 lesions, while acute phase of ACS without ST elevation was diagnosed in 16 patients (24 lesions. In the patients in acute phase of ACS without ST segment elevation IVUS-VH examination showed a significantly larger area of the necrotic core at the site of minimal lumen area and a larger mean of the necrotic core volume in the entire lesion comparing to stable angina subjects (1.84±0.90 mm2 vs. 0.96±0.69 mm2; p<0.001 and 20.94±15.79 mm3 vs. 11.54±14.15 mm3; p<0.05 respectively. Conclusion. IVUS-VH detected that the necrotic core was significantly larger in atherosclerotic lesions in patients in acute phase of ACS without ST elevation comparing to the stable angina subjects and that it could be considered as a marker of plaque vulnerability.

  11. Ultra-Stable Zero-CTE HoneySiC and H2CMN Mirror Support Structures, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA MSFC, GSFC and JPL are interested in Ultra-Stable Mirror Support Structures for Exoplanet Missions. Telescopes with Apertures of 4-meters or larger and using an...

  12. Experimental and numerical investigation of form-stable dodecane/hydrophobic fumed silica composite phase change materials for cold energy storage

    International Nuclear Information System (INIS)

    Chen, Jiajie; Ling, Ziye; Fang, Xiaoming; Zhang, Zhengguo

    2015-01-01

    Highlights: • Form-stable dodecane/fumed silica composite for cold storage is prepared. • A suggesting hypothesis that explains infiltration mechanism is proposed. • The performance of the composite phase change material is investigated. • Numerical simulation of system is carried out and results fit well. - Abstract: A kind of form-stable composite phase change materials used for cold thermal energy storage is prepared by absorbing dodecane into the hydrophobic fumed silica. With relatively suitable pore diameter and hydrophobic groups, hydrophobic fumed silica is beneficial to the penetration and infiltration of dodecane and the leakage problem solving. Scanned by electron micrographs and Fourier transformation infrared, the composite phase change material is characterized to be just physical penetration. Besides, the differential scanning calorimeter and thermo gravimetric analysis reveals the high enthalpy, good thermal stability and cycling performance of this composite phase change material. What’s more, Hot-Disk thermal constants analyzer demonstrates that the composite phase change material has low thermal conductivity which is desired in cold storage application. In the experiment, a cold energy storage system is set up and the results from the experiment show that the system has excellent performance of cold storage by incorporating composite phase change material. Apart from that, the experimental data is found to have a great agreement with the numerical simulation which is carried out by using the commercial computational fluid dynamics software FLUENT.

  13. Analysis of elastic strain and crystallographic texture in poled rhombohedral PZT ceramics

    International Nuclear Information System (INIS)

    Hall, D.A.; Steuwer, A.; Cherdhirunkorn, B.; Mori, T.; Withers, P.J.

    2006-01-01

    The elastic strain and crystallographic texture of a rhombohedral lead zirconate titanate ceramic have been characterised in the remanent state, after poling, using high-energy synchrotron X-ray diffraction as a function of the grain orientation ψ relative to the poling direction. It is observed that the (2 0 0) diffraction peak exhibits pronounced shifts as a function of ψ, indicating an elastic lattice strain, while others ({1 1 1}, {1 1 2} and {2 2 0}) show marked changes in intensity as a result of preferred ferroelectric domain orientation. It is shown that the (2 0 0) peak is not affected by the domain switching itself but rather acts like an elastic macrostrain sensor. A simple Eshelby analysis is used to demonstrate that both the elastic strain and texture vary systematically with ψ according to the factor (3cos 2 ψ - 1). This angular dependence is evaluated through micromechanics modelling. The physical meaning of the texture variations with ψ is also discussed

  14. Investigation of Hard Boron Rich Solids: Osmium Diboride and β-Rhombohedral Boron

    Science.gov (United States)

    Hebbache, M.; Živković, D.

    Recently, we succeeded in synthesizing three osmium borides, i.e., OsB1.1, Os2B3 and OsB2. Up to date, almost nothing is known about the physical properties of these materials. Microhardness measurements show that OsB2 is extremely hard. Ab initio calculations show that it is due to formation of covalent bonds between boron atoms. OsB2 is also a low compressibility material. It can be used for hard coatings. The β-rhombohedral polymorph of boron is the second hardest elemental crystal (H ≈ 33 GPa). It is also very light and a p-type semiconductor. In early 1970s, it has been shown that the doping of boron with 3d transition elements enhances its hardness by about 25%. We predict that, in general, heavily doped samples MBx, with x ≤ 31 or equivalently a dopant concentration larger than 3.2 at.%, should be ultrahard, i.e., H > 43 GPa. The relevant dopants M are Al, Cu, Sc, Mn, Mg and Li. In addition to these properties, boron-rich materials have a very low volatility, a high chemical inertness and high melting point. They are suitable for applications under extreme conditions and thermoelectric equipment.

  15. Dielectric properties of Na1–xKxNbO3 in orthorhombic phase

    Indian Academy of Sciences (India)

    Unknown

    reaction method. Prepared samples ... Near the transition temperature the material shows anomalous ... phase transitions at – 100°C (rhombohedral to orthorhom- bic) (Wells and ..... from the electromagnetic field to this lattice mode and is.

  16. A stable algorithm for calculating phase equilibria with capillarity at specified moles, volume and temperature using a dynamic model

    KAUST Repository

    Kou, Jisheng; Sun, Shuyu

    2017-01-01

    Capillary pressure can significantly affect the phase properties and flow of liquid-gas fluids in porous media, and thus, the phase equilibrium calculation incorporating capillary pressure is crucial to simulate such problems accurately. Recently

  17. Form-Stable Phase Change Materials Based on Eutectic Mixture of Tetradecanol and Fatty Acids for Building Energy Storage: Preparation and Performance Analysis

    Directory of Open Access Journals (Sweden)

    Yiran li

    2013-10-01

    Full Text Available This paper is focused on preparation and performance analysis of a series of form-stable phase change materials (FSPCMs, based on eutectic mixtures as phase change materials (PCMs for thermal energy storage and high-density polyethylene (HDPE-ethylene-vinyl acetate (EVA polymer as supporting materials. The PCMs were eutectic mixtures of tetradecanol (TD–capric acid (CA, TD–lauric acid (LA, and TD–myristic acid (MA, which were rarely explored before. Thermal properties of eutectic mixtures and FSPCMs were measured by differential scanning calorimeter (DSC. The onset melting/solidification temperatures of form-stable PCMs were 19.13 °C/13.32 °C (FS TD–CA PCM, 24.53 °C/24.92 °C (FS TD–LA PCM, and 33.15 °C/30.72 °C (FS TD–MA PCM, respectively, and latent heats were almost greater than 90 J/g. The surface morphologies and chemical stability of form-stable PCM were surveyed by scanning electron microscopy (SEM and Fourier-transform infrared (FT-IR spectroscopy, respectively. The thermal cycling test revealed that the thermal reliability of these three form-stable PCMs was good. Thermal storage/release experiment indicated melting/solidification time was shortened by introducing 10 wt % aluminum powder (AP. It is concluded that these FSPCMs can act as potential building thermal storage materials in terms of their satisfactory thermal properties.

  18. Form-Stable Phase Change Materials Based on Eutectic Mixture of Tetradecanol and Fatty Acids for Building Energy Storage: Preparation and Performance Analysis.

    Science.gov (United States)

    Huang, Jingyu; Lu, Shilei; Kong, Xiangfei; Liu, Shangbao; Li, Yiran

    2013-10-22

    This paper is focused on preparation and performance analysis of a series of form-stable phase change materials (FSPCMs), based on eutectic mixtures as phase change materials (PCMs) for thermal energy storage and high-density polyethylene (HDPE)-ethylene-vinyl acetate (EVA) polymer as supporting materials. The PCMs were eutectic mixtures of tetradecanol (TD)-capric acid (CA), TD-lauric acid (LA), and TD-myristic acid (MA), which were rarely explored before. Thermal properties of eutectic mixtures and FSPCMs were measured by differential scanning calorimeter (DSC). The onset melting/solidification temperatures of form-stable PCMs were 19.13 °C/13.32 °C (FS TD-CA PCM), 24.53 °C/24.92 °C (FS TD-LA PCM), and 33.15 °C/30.72 °C (FS TD-MA PCM), respectively, and latent heats were almost greater than 90 J/g. The surface morphologies and chemical stability of form-stable PCM were surveyed by scanning electron microscopy (SEM) and Fourier-transform infrared (FT-IR) spectroscopy, respectively. The thermal cycling test revealed that the thermal reliability of these three form-stable PCMs was good. Thermal storage/release experiment indicated melting/solidification time was shortened by introducing 10 wt % aluminum powder (AP). It is concluded that these FSPCMs can act as potential building thermal storage materials in terms of their satisfactory thermal properties.

  19. A comparative structural and electrochemical study of monoclinic Li3V2(PO4)3/C and rhombohedral Li2.5Na0.5V(2−2x/3)Nix(PO4)3/C

    International Nuclear Information System (INIS)

    Wang, Wenhui; Chen, Zhenyu; Zhang, Jiaolong; Dai, Changsong; Li, Jiajie; Ji, Dalong

    2013-01-01

    In order to synthesize pure derivative of rhombohedral Li 3 V 2 (PO 4 ) 3 (LVP), lithium-ion batteries materials Li 2.5 Na 0.5 V (2−2x/3) Ni x (PO 4 ) 3 /C (x = 0.03, 0.06, 0.09) and its control, monoclinic Li 3 V 2 (PO 4 ) 3 /C (LVP/C), were prepared by sol–gel method. The samples were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), Raman spectroscopy, and electrochemical methods. The XRD patterns of Li 2.5 Na 0.5 V (2−2x/3) Ni x (PO 4 ) 3 /C are in good agreement with that of rhombohedral LVP, which indicates that the Na + –Ni 2+ composite doping can change the structure of monoclinic LVP. All the composite doping samples displayed a single flat plateau at 3.7 V in the charge/discharge voltage profile, which is caused by transformation of multi-phase mechanism to single-phase mechanism. For Li 2.5 Na 0.5 V 1.98 Ni 0.03 (PO 4 ) 3 /C, a specific discharge capacity of 108 mAh g −1 was achieved at a 0.5 C charge rate and a 1 C discharge rate, and a 99.0% retention rate of the initial capacity was obtained after 50 cycles

  20. Preparation, characterization and thermal properties of styrene maleic anhydride copolymer (SMA)/fatty acid composites as form stable phase change materials

    International Nuclear Information System (INIS)

    Sari, Ahmet; Alkan, Cemil; Karaipekli, Ali; Onal, Adem

    2008-01-01

    Fatty acids such as stearic acid (SA), palmitic acid (PA), myristic acid (MA) and lauric acid (LA) are promising phase change materials (PCMs) for latent heat thermal energy storage (LHTES) applications, but high cost is the major drawback of them, limiting their utility area in thermal energy storage. The use of fatty acids as form stable PCMs will increase their feasibilities in practical applications due to the reduced cost of the LHTES system. In this regard, a series of styrene maleic anhydride copolymer (SMA)/fatty acid composites, SMA/SA, SMA/PA, SMA/MA, and SMA/LA, were prepared as form stable PCMs by encapsulation of fatty acids into the SMA, which acts as a supporting material. The encapsulation ratio of fatty acids was as much as 85 wt.% and no leakage of fatty acid was observed even when the temperature of the form stable PCM was over the melting point of the fatty acid in the composite. The prepared form stable composite PCMs were characterized using optic microscopy (OM), viscosimetry and Fourier transform infrared (FT-IR) spectroscopy methods, and the results showed that the SMA was physically and chemically compatible with the fatty acids. In addition, the thermal characteristics such as melting and freezing temperatures and latent heats of the form stable composite PCMs were measured by using the differential scanning calorimetry (DSC) technique, which indicated they had good thermal properties. On the basis of all the results, it was concluded that form stable SMA/fatty acid composite PCMs had important potential for practical LHTES applications such as under floor space heating of buildings and passive solar space heating of buildings by using wallboard, plasterboard or floors impregnated with a form stable PCM due to their satisfying thermal properties, easy preparation in desired dimensions, direct usability without needing additional encapsulation thereby eliminating the thermal resistance caused by the shell and, thus, reducing the cost of

  1. Formation of stable and metastable phases in reciprocal systems PbSe + MI2 = MSe + PbI2 (M = Hg, Mn, Sn)

    International Nuclear Information System (INIS)

    Odin, I.N.; Grin'ko, V.V.; Kozlovskij, V.F.; Safronov, E.V.; Gapanovich, M.V.

    2004-01-01

    Using data of differential thermal, X-ray phase and microstructural analyses, phase diagrams of reciprocal systems PbSe + MI 2 = MSe + PbI 2 (M=Hg (1), Mn (2), Sn (3)) were constructed. It was ascertained that the HgSe-PbI 2 diagonal in system 1 is stable. Transformations leading to crystallization of metastable ternary compound formed in the system PbSe-PbI 2 and metastable polytypes of lead iodide in systems 1 and 2 in the range of temperatures from 620 to 685 K were studied. New intermediate metastable phases in systems 1, 2 and 3 were prepared by melt quenching. Crystal lattice parameters of the phases crystallizing in the CdCl 2 structural type were defined [ru

  2. Construction of a stable and homogeneous magnetic field at 10 milligauss for neutron electric dipole moment measurements: preparatory phase

    Energy Technology Data Exchange (ETDEWEB)

    Gravador, E.; Yoshiki, Hajime; Feizeng, H. [Ibaraki Univ., Mito (Japan)

    1996-08-01

    A superthermal UCN edm measuring machine is currently under construction at KEK. It utilizes a magnetically shielded superconducting solenoid at liquid helium temperature to generate a stable and homogeneous magnetic field at 10 milligauss. The design of the magnetic shield and solenoid and preliminary evaluation of shielding effectiveness is presented. (author)

  3. Preparation and properties studies of halogen-free flame retardant form-stable phase change materials based on paraffin/high density polyethylene composites

    International Nuclear Information System (INIS)

    Cai Yibing; Wei Qufu; Huang Fenglin; Gao Weidong

    2008-01-01

    The halogen-free flame retardant form-stable phase change materials (PCM) based on paraffin/high density polyethylene (HDPE) composites were prepared by using twin-screw extruder technique. The structures and properties of the form-stable PCM composites based on intumescent flame retardant system with expandable graphite (EG) and different synergistic additives, such as ammonium polyphosphate (APP) and zinc borate (ZB) were characterized by scanning electronic microscope (SEM), thermogravimetric analyses (TGA), dynamic Fourier-transform infrared (FTIR) spectra, differential scanning calorimeter (DSC) and Cone calorimeter test. The TGA results showed that the halogen-free flame retardant form-stable PCM composites produced a larger amount of charred residue at 700 deg. C, although the onset of weight loss of the halogen-free flame retardant form-stable PCM composites occurred at a lower temperature due to the thermal decomposition of flame retardant. The DSC measurements indicated that the additives of flame retardant had little effect on the thermal energy storage property, and the temperatures of phase change peaks and the latent heat of the paraffin showed better occurrence during the freezing process. The dynamic FTIR monitoring results revealed that the breakdowns of main chains (HDPE and paraffin) and formations of various residues increased with increasing thermo-oxidation temperature. It was also found from the Cone calorimeter tests that the peak of heat release rate (PHRR) decreased significantly. Both the decrease of the PHRR and the structure of charred residue after combustion indicated that there was a synergistic effect between the EG and APP, contributing to the improved flammability of the halogen-free flame retardant form-stable PCM composites

  4. Toward stable nickel catalysts for aqueous phase reforming of biomass-derived feedstock under reducing and alkaline conditions

    NARCIS (Netherlands)

    Haasterecht, van T.; Ludding, C.C.I.; Jong, de K.P.; Bitter, J.H.

    2014-01-01

    Nickel nanoparticles supported on carbon nanofibers (CNF) can be stabilized in aqueous phase processes at elevated temperatures and pressures by tuning the reaction conditions to control Ni oxidation and leaching. As a showcase, Ni/CNF was used for the production of hydrogen via aqueous phase

  5. An energy stable evolution method for simulating two-phase equilibria of multi-component fluids at constant moles, volume and temperature

    KAUST Repository

    Kou, Jisheng

    2016-02-25

    In this paper, we propose an energy-stable evolution method for the calculation of the phase equilibria under given volume, temperature, and moles (VT-flash). An evolution model for describing the dynamics of two-phase fluid system is based on Fick’s law of diffusion for multi-component fluids and the Peng-Robinson equation of state. The mobility is obtained from diffusion coefficients by relating the gradient of chemical potential to the gradient of molar density. The evolution equation for moles of each component is derived using the discretization of diffusion equations, while the volume evolution equation is constructed based on the mechanical mechanism and the Peng-Robinson equation of state. It is proven that the proposed evolution system can well model the VT-flash problem, and moreover, it possesses the property of total energy decay. By using the Euler time scheme to discretize this evolution system, we develop an energy stable algorithm with an adaptive choice strategy of time steps, which allows us to calculate the suitable time step size to guarantee the physical properties of moles and volumes, including positivity, maximum limits, and correct definition of the Helmhotz free energy function. The proposed evolution method is also proven to be energy-stable under the proposed time step choice. Numerical examples are tested to demonstrate efficiency and robustness of the proposed method.

  6. Development of novel CO{sub 2}-stable oxygen permeable dual phase membranes for CO{sub 2} capture in an oxy-fuel process

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Huixia

    2012-07-19

    The combustion of fossil fuels in power stations with pure oxygen following the oxy-fuel process allows the Sequestration of CO{sub 2}. The pure oxygen needed can be separated from air by oxygen transporting ceramics like single phase perovskites. However, most of the so far developed single phase perovskites have stability problems in a CO{sub 2} containing atmosphere. Dual phase membranes are micro-scale mixtures of an electron conducting phase and an oxygen ion conducting phase and their compositions can be tailored according to practical requirements, which are considered to be promising substitutes for the single phase perovskite materials. In my thesis the issues of phase stability for perovskite-type material with the common composition Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 3-{delta}} (BSCF) as weil as the development of a series of novel CO{sub 2}-stable dual phase membranes were studied. In Chapter 2, the phase stability and permeation behavior of a dead-end BSCF tube membrane in high-purity oxygen at temperatures below 750 C, were elucidated using powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDXS), high-angle annular dark-field (HAADF) and scanning transmission electron microscopy (STEM). lt was found that parts of the cubic perovskite BSCF transformed into a hexagonal perovskite Ba{sub 0.5{+-}x}Sr{sub 0.5{+-}x}CoO{sub 3-{delta}} (x {approx} 0.1) and a trigonal mixed oxide Ba{sub 1-x}Sr{sub x}CO{sub 2-y}Fe{sub y}O{sub 5{+-}{delta}} (x {approx} 0.15, y {approx} 0.25) in high-purity oxygen at 750 C. On the other hand, it was found that the partial degradation of cubic BSCF perovskite at 750 C was more pronounced under the strongly oxidizing conditions on the oxygen supply (feed) side than on the oxygen release (permeate) side of the membrane. The structural instability of BSCF is attributed to an oxidation of cobalt from Co{sup 2+} to Co{sup 3+} and Co{sup 4+}, which exhibits an ionic radius that is too small to be tolerated by

  7. Spin glass transition in the rhombohedral LiNi1/3Mn1/3Co1/3O2

    International Nuclear Information System (INIS)

    Bie, Xiaofei; Yang, Xu; Han, Bing; Chen, Nan; Liu, Lina; Wei, Yingjin; Wang, Chunzhong; Chen, Hong; Du, Fei; Chen, Gang

    2013-01-01

    Highlights: •The Rietveld analysis of XRD data reveals a single phase with rhombohedral structure. •Dc susceptibility data suggest a spin glass behavior at low T in the 333 compound. •The ac susceptibility measurements have been observed in the typical SG system. •Three models have been employed to study the behavior of the spin glass state. •Both geometrical frustration and disorder play important role in the formation of SG. -- Abstract: Layered LiNi 1/3 Mn 1/3 Co 1/3 O 2 has been synthesized by co-precipitation method, and the magnetic properties were comprehensively studied by dc and ac susceptibilities. The dc magnetization curves show the irreversibility and spin freezing behavior at 109 K and 9 K. The evolution of real and imaginary part of ac susceptibility under different frequencies indicates a spin glass transition at low temperature. Three models (the Néel–Arrhenius law, the Vogel–Fulcher law, and the power law) have been employed to study the relaxation behavior of the spin glass state. Both frustration and disorder play important role in the formation of spin glass

  8. Complex-based OCT angiography algorithm recovers microvascular information better than amplitude- or phase-based algorithms in phase-stable systems.

    Science.gov (United States)

    Xu, Jingjiang; Song, Shaozhen; Li, Yuandong; Wang, Ruikang K

    2017-12-19

    Optical coherence tomography angiography (OCTA) is increasingly becoming a popular inspection tool for biomedical imaging applications. By exploring the amplitude, phase and complex information available in OCT signals, numerous algorithms have been proposed that contrast functional vessel networks within microcirculatory tissue beds. However, it is not clear which algorithm delivers optimal imaging performance. Here, we investigate systematically how amplitude and phase information have an impact on the OCTA imaging performance, to establish the relationship of amplitude and phase stability with OCT signal-to-noise ratio (SNR), time interval and particle dynamics. With either repeated A-scan or repeated B-scan imaging protocols, the amplitude noise increases with the increase of OCT SNR; however, the phase noise does the opposite, i.e. it increases with the decrease of OCT SNR. Coupled with experimental measurements, we utilize a simple Monte Carlo (MC) model to simulate the performance of amplitude-, phase- and complex-based algorithms for OCTA imaging, the results of which suggest that complex-based algorithms deliver the best performance when the phase noise is  algorithm delivers better performance than either the amplitude- or phase-based algorithms for both the repeated A-scan and the B-scan imaging protocols, which agrees well with the conclusion drawn from the MC simulations.

  9. Liquid structure as a guide for phase stability in the solid state: Discovery of a stable compound in the Au-Si alloy system

    International Nuclear Information System (INIS)

    Tasci, Emre S.; Sluiter, Marcel H.F.; Pasturel, Alain; Villars, Pierre

    2010-01-01

    A new crystalline ground state was discovered in the Au-Si system through first-principles electronic structure calculations. The new structure was found using the experimentally and theoretically determined local atomic structure in the liquid as a guide for the solid state. Local atomic structure in the liquid was matched with that for all known crystal structures as compiled in the Pauling File structural database. The best matching crystalline structures were then explicitly calculated using first-principles methods. Most candidate crystal structures were found to be close, but above the enthalpy of a composition weighted average of the face-centered cubic Au and diamond structure Si terminal phases, but one crystal structure was more stable than the terminal phases by about 10 meV atom -1 at T = 0 K. As first-principles simulations of local structure are feasible for most liquid alloys, the present methodology is applicable to other alloys lying near a eutectic composition.

  10. Stable phase-shift despite quasi-rhythmic movements: a CPG-driven dynamic model of active tactile exploration in an insect

    Directory of Open Access Journals (Sweden)

    Nalin eHarischandra

    2015-08-01

    Full Text Available An essential component of autonomous and flexible behaviour in animals is active exploration of the environment, allowing for perception-guided planning and control of actions. An important sensory system involved is active touch. Here, we introduce a general modelling framework of Central Pattern Generators (CPGs for movement generation in active tactile exploration behaviour. The CPG consists of two network levels: (i phase-coupled Hopf oscillators for rhythm generation, and (ii pattern formation networks for capturing the frequency and phase characteristics of individual joint oscillations. The model captured the natural, quasi-rhythmic joint kinematics as observed in coordinated antennal movements of walking stick insects. Moreover, it successfully produced tactile exploration behaviour on a three-dimensional skeletal model of the insect antennal system with physically realistic parameters. The effect of proprioceptor ablations could be simulated by changing the amplitude and offset parameters of the joint oscillators, only. As in the animal, the movement of both antennal joints was coupled with a stable phase difference, despite the quasi-rhythmicity of the joint angle time courses. We found that the phase-lead of the distal scape-pedicel joint relative to the proximal head-scape joint was essential for producing the natural tactile exploration behaviour and, thus, for tactile efficiency. For realistic movement patterns, the phase-lead could vary within a limited range of 10 to 30 degrees only. Tests with artificial movement patterns strongly suggest that this phase sensitivity is not a matter of the frequency composition of the natural movement pattern. Based on our modelling results, we propose that a constant phase difference is coded into the CPG of the antennal motor system and that proprioceptors are acting locally to regulate the joint movement amplitude.

  11. The plasma centrifuge: A compact, low cost, stable isotope separator. Phase 2 final technical report, September 15, 1991 - September 14, 1995

    International Nuclear Information System (INIS)

    Guss, W.

    1996-01-01

    Enriched stable isotopes are required for production of radionuclides as well as for research and diagnostic uses. Science Research Laboratory (SRL) has developed a plasma centrifuge for moderate throughput of enriched stable isotopes, such as 13 C, 17 O, 18 O, and 203 Tl, for medical as well as other applications. Dwindling isotope stocks have restricted the use of enriched isotopes and their associated labeled organic molecules in medical imaging to very few research facilities because of high costs of isotope separation. With the introduction of the plasma centrifuge separator, the cost per separated gram of even rarely occurring isotopes (≤ 1% natural abundance) is potentially many times lower than with other separation technologies (cryogenic distillation and calutrons). The centrifuge is a simple, robust, pulsed electrical discharge device that has successfully demonstrated isotope separation of small (mg) quantities of 26 Mg. Based on the results of the Phase 2 program, modest enhancements to the power supplies and cooling systems, a centrifuge separator will have high repetition rate (60 pps) and high duty cycle (60%) to produce in one month kilogram quantities of highly enriched stable isotopes. The centrifuge may be used in stand-alone operation or could be used as a high-throughput pre-separation stage with calutrons providing the final separation

  12. Preparation and characterization of form-stable paraffin/polycaprolactone composites as phase change materials for thermal energy storage

    Directory of Open Access Journals (Sweden)

    Aludin M.S.

    2017-01-01

    Full Text Available Paraffin is Phase Change Materials (PCM that possesses desirable properties such as high thermal energy storage and thermal stability to make it suitable for thermal energy storage applications. However, paraffin has been reported to leak out during the melting process. In this study, composites were prepared by dissolving paraffin and polycaprolactone (PCL at varied mass percent compositions in chloroform and then purified through precipitation techniques. The leakage test was conducted by placing the composite samples on a set of four-layer filter papers and left in a furnace at 90°C for 1 hour. By incorporating PCL into paraffin phase, the leakage mass percentage was drastically reduced. The PCL polymer matrix in the composites may have trapped the paraffin molecules during melting process thus prevent it from leaking.

  13. Nanoscale Tapered Pt Bottom Electrode Fabricated by FIB for Low Power and Highly Stable Operations of Phase Change Memory

    International Nuclear Information System (INIS)

    Shi-Long, Lv; Zhi-Tang, Song; Yan, Liu; Song-Lin, Feng

    2010-01-01

    Phase change random access memory (PC-RAM) based on Si 2 Sb 2 Te 5 with a Pt tapered heating electrode (Pt-THE), which is fabricated using a focus ion beam (FIB), is investigated. Compared with the tungsten electrode, the Pt-THE facilitates the temperature rise in phase change material, which causes the decrease of reset voltage from 3.6 to 2.7 V. The programming region of the cell with the Pt-THE is smaller than that of the cell with a cylindrical tungsten heating electrode. The improved performance of the PC-RAM with a Pt-THE is attributed to the higher resistivity and lower thermal conductivity of the Pt electrode, and the reduction of the programming region, which is also verified by thermal simulation. (cross-disciplinary physics and related areas of science and technology)

  14. Stable, low-cost phase change material for building applications: The eutectic mixture of decanoic acid and tetradecanoic acid

    International Nuclear Information System (INIS)

    Kahwaji, Samer; Johnson, Michel B.; Kheirabadi, Ali C.; Groulx, Dominic; White, Mary Anne

    2016-01-01

    Highlights: • Decanoic/tetradecanoic acid eutectic at 0.82 ± 0.02 mole fraction (78 ± 2 mass%) decanoic acid. • Melting of eutectic at 20.5 ± 1.5 °C, useful for building applications. • High enthalpy change, 153 ± 15 J g"−"1, is promising. • Negligible change in stability after 3000 melt–freeze cycles. - Abstract: We present a thorough characterization of the thermal properties and thermal reliability of the eutectic mixture of decanoic acid with tetradecanoic acid, as a phase change material (PCM) of potential interest for passive temperature control in buildings. From the temperature-composition binary phase diagram we found that the eutectic composition is 0.82 ± 0.02 mole fraction (78 ± 2 mass%) decanoic acid. We thoroughly characterized the thermal properties of the eutectic mixture. The eutectic composition has a high latent heat of fusion Δ_f_u_sH = 153 ± 15 J g"−"1 and a melting temperature T_o_n_s_e_t = 20.5 ± 1.5 °C. The heat capacity measured as a function of temperature for the solid and liquid phases just below and above the melting point is 1.9 and 2.1 ± 0.2 J K"−"1 g"−"1, respectively. The average value of the thermal conductivity of the solid phase measured between −33 and 9 °C is κ_s = 0.20 ± 0.02 W m"−"1 K"−"1 and for the liquid phase, the thermal conductivity is κ_l = 0.23 ± 0.03 W m"−"1 K"−"1 for 28 and 38 °C. The mixture has a good long-term thermal stability as indicated by negligible changes in Δ_f_u_sH and T_o_n_s_e_t after 3000 melt–freeze cycles. The parameters determined in this work allow more accurate modeling and optimization of the behavior of the eutectic mixture in preparation for implementation as a thermal energy storage PCM.

  15. Form-stable paraffin/high density polyethylene composites as solid-liquid phase change material for thermal energy storage: preparation and thermal properties

    International Nuclear Information System (INIS)

    Sari, Ahmet

    2004-01-01

    This paper deals with the preparation of paraffin/high density polyethylene (HDPE) composites as form-stable, solid-liquid phase change material (PCM) for thermal energy storage and with determination of their thermal properties. In such a composite, the paraffin (P) serves as a latent heat storage material and the HDPE acts as a supporting material, which prevents leakage of the melted paraffin because of providing structural strength. Therefore, it is named form-stable composite PCM. In this study, two kinds of paraffins with melting temperatures of 42-44 deg. C (type P1) and 56-58 deg. C (type P2) and latent heats of 192.8 and 212.4 J g -1 were used. The maximum weight percentage for both paraffin types in the PCM composites without any seepage of the paraffin in the melted state were found as high as 77%. It is observed that the paraffin is dispersed into the network of the solid HDPE by investigation of the structure of the composite PCMs using a scanning electronic microscope (SEM). The melting temperatures and latent heats of the form-stable P1/HDPE and P2/HDPE composite PCMs were determined as 37.8 and 55.7 deg. C, and 147.6 and 162.2 J g -1 , respectively, by the technique of differential scanning calorimetry (DSC). Furthermore, to improve the thermal conductivity of the form-stable P/HDPE composite PCMs, expanded and exfoliated graphite (EG) by heat treatment was added to the samples in the ratio of 3 wt.%. Thereby, the thermal conductivity was increased about 14% for the form-stable P1/HDPE and about 24% for the P2/HDPE composite PCMs. Based on the results, it is concluded that the prepared form-stable P/HDPE blends as composite type PCM have great potential for thermal energy storage applications in terms of their satisfactory thermal properties and improved thermal conductivity. Furthermore, these composite PCMs added with EG can be considered cost effective latent heat storage materials since they do not require encapsulation and extra cost to enhance

  16. Luminescent properties of stabled hexagonal phase Sr1-xBaxAl2O4:Eu2+ (x=0.37-0.70)

    International Nuclear Information System (INIS)

    Wu Qiaoli; Liu Zhen; Jiao Huan

    2009-01-01

    Stabled hexagonal phase Sr 1-x Ba x Al 2 O 4 :Eu 2+ (x=0.37-0.70) was prepared by solid-state method. Result revealed that the structure behavior of the SrAl 2 O 4 :Eu 2+ calcined at 1350 deg. C in a reducing atmosphere for 5 h strongly depended on the Ba 2+ concentration. With increasing Ba 2+ concentration, a characteristic hexagonal phase can be observed. When 37-70% of the strontium is replaced by barium, the structure of the prepared sample is pure hexagonal. Photoluminescence and excitation spectra of the samples with different x and doped with 2% Eu 2+ were investigated. Changes in the emission spectra were observed in the two different phases. The green emission at 505 nm from Eu 2+ was found to be quite strong in the hexagonal phase. The intensity and peak position of the green luminescence from Eu 2+ changed with increasing content of Ba 2+ . The strongest green emission was obtained from Sr 0.61 Ba 0.37 Al 2 O 4 :Eu 2+ . The decay characteristics of Sr 1-x Ba x Al 2 O 4 :Eu 2+ (x=0.37-0.70) showed that the life times also varied with the value of x. Furthermore, the emission colors and decay times varying with x could be ascribed to the variation of crystal lattice.

  17. Synthesis, crystal growth and structure of Mg containing β-rhombohedral boron: MgB17.4

    International Nuclear Information System (INIS)

    Adasch, Volker; Hess, Kai-Uwe; Ludwig, Thilo; Vojteer, Natascha; Hillebrecht, Harald

    2006-01-01

    For the first time, single crystals of Mg containing β-rhombohedral boron MgB 17.4 were synthesised from the elements in a Mg/Cu melt at 1600deg. C. The crystal structure determined by the refinement of single crystal data (space group R-3m, a=10.991(2)A, c=24.161(4)A, 890 reflections, 123 variables, R 1 (F)=0.049, wR 2 (I)=0.122) improves and modifies the former structure model derived from earlier investigations on powder samples. Mg is located on four different positions with partial occupation. While the occupation of the sites D (53.3%), E (91%) and F (7.2%) is already known from other boron-rich borides related to β-rhombohedral boron, the occupation of the fourth position (18h, 6.7%) is observed for the first time. Two boron positions show partial occupation. The summation reveals the composition MgB 17.4 and Mg 5.85 B 101.9 , respectively, confirmed by WDX measurements. The single crystals of MgB 17.4 show the highest Mg content ever found. Preliminary measurements indicate no superconductivity

  18. Confinement and surface effects on the physical properties of rhombohedral-shape hematite (α-Fe_2O_3) nanocrystals

    International Nuclear Information System (INIS)

    Luna, Carlos; Cuan-Guerra, Aída D.; Barriga-Castro, Enrique D.; Núñez, Nuria O.; Mendoza-Reséndez, Raquel

    2016-01-01

    Highlights: • Uniform rhombohedral hematite nanocrystals (RHNCs) have been obtained. • A detailed formation mechanism of these HNCS has been proposed. • Phonon confinement effects were revealed in the RHNCS vibrational bands. • Quantum confinement effects on the optical and electronic properties were found. - Abstract: Morphological, microstructural and vibrational properties of hematite (α-Fe_2O_3) nanocrystals with a rhombohedral shape and rounded edges, obtained by forced hydrolysis of iron(III) solutions under a fast nucleation, have been investigated in detail as a function of aging time. These studies allowed us to propose a detailed formation mechanism and revealed that these nanocrystals are composed of four {104} side facets, two {110} faces at the edges of the long diagonal of the nanocrystals and two {−441} facets as the top and bottom faces. Also, the presence of nanoscopic pores and fissures was evidenced. The vibrational bands of such nanocrystals were shifted to lower frequencies in comparison with bulk hematite ones as the nanocrystal size was reduced due to phonon confinement effects. Also, the indirect and direct transition band gaps displayed interesting dependences on the aging time arising from quantum confinement and surface effects

  19. Low-lying dipole response in the stable 40,48Ca nuclei within the second random-phase approximation

    International Nuclear Information System (INIS)

    Gambacurta, D.; Grasso, M.; Catara, F.

    2012-01-01

    The low-lying dipole strength distributions of 40 CaCa and 48 Ca, in the energy region between 5 and 10 MeV, are studied within the second random phase approximation (RPA) with Skyrme interaction. Standard RPA models do not usually predict any presence of strength in this energy region, while experimentally a significant amount of strength is found. The inclusion of the 2 particle −2 hole configurations allows to obtain a description in a rather good agreement with the experimental data. The properties of the most collective state are analyzed in terms of its 1 particle −1 hole nature and its transition densities.

  20. Low-lying dipole response in the stable 40,48Ca nuclei within the second random-phase approximation

    Science.gov (United States)

    Gambacurta, D.; Grasso, M.; Catara, F.

    2012-10-01

    The low-lying dipole strength distributions of 40CaCa and 48Ca, in the energy region between 5 and 10 MeV, are studied within the second random phase approximation (RPA) with Skyrme interaction. Standard RPA models do not usually predict any presence of strength in this energy region, while experimentally a significant amount of strength is found. The inclusion of the 2 particle -2 hole configurations allows to obtain a description in a rather good agreement with the experimental data. The properties of the most collective state are analyzed in terms of its 1 particle -1 hole nature and its transition densities.

  1. Preparation and thermal properties of form-stable palmitic acid/active aluminum oxide composites as phase change materials for latent heat storage

    International Nuclear Information System (INIS)

    Fang, Guiyin; Li, Hui; Cao, Lei; Shan, Feng

    2012-01-01

    Form-stable palmitic acid (PA)/active aluminum oxide composites as phase change materials were prepared by adsorbing liquid palmitic acid into active aluminum oxide. In the composites, the palmitic acid was used as latent heat storage materials, and the active aluminum oxide was used as supporting material. Fourier transformation infrared spectroscope (FT-IR), X-ray diffractometer (XRD) and scanning electronic microscope (SEM) were used to determine the chemical structure, crystalloid phase and microstructure of the composites, respectively. The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetry analyzer (TGA). The FT-IR analyses results indicated that there is no chemical interaction between the palmitic acid and active aluminum oxide. The SEM results showed that the palmitic acid was well adsorbed into porous network of the active aluminum oxide. The DSC results indicated that the composites melt at 60.25 °C with a latent heat of 84.48 kJ kg −1 and solidify at 56.86 °C with a latent heat of 78.79 kJ kg −1 when the mass ratio of the PA to active aluminum oxide is 0.9:1. Compared with that of the PA, the melting and solidifying time of the composites CPCM5 was reduced by 20.6% and 21.4% because of the increased heat transfer rate through EG addition. The TGA results showed that the active aluminum oxide can improve the thermal stability of the composites. -- Highlights: ► Form-stable PA/active aluminum oxide composites as PCMs were prepared. ► Chemical structure, crystalloid phase and microstructure of composites were determined. ► Thermal properties and thermal stability of the composites were investigated. ► Expanded graphite can improve thermal conductivity of the composites.

  2. Facile synthesis of high-temperature (1000 °C) phase-stable rice-like anatase TiO{sub 2} nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Lizhen [Capital Normal University, Beijing Key Laboratory for Optical Materials and Photonic Devices, Department of Chemistry (China); Chen, Qirong [Beijing Center for Physical and Chemical Analysis (BCPCA) (China); Liu, Xiuyun; Wang, Miaomiao; Meng, Xiangfu, E-mail: xfmeng@cnu.edu.cn [Capital Normal University, Beijing Key Laboratory for Optical Materials and Photonic Devices, Department of Chemistry (China)

    2015-05-15

    High-temperature phase-stable rice-like anatase TiO{sub 2} nanocrystals were synthesized by one-pot solvothermal method using soluble titania xerogel and isopropyl alcohol (IPA) as the precursor and the solvent, respectively. Sample characterization was carried out by powder X-ray diffraction, high-resolution transmission electron microscopy, field emission scanning electron microscope, X-ray photoelectron spectroscopy, and N{sub 2} adsorption–desorption isotherms. The results showed that TiO{sub 2} nanocrystals had rice-like shapes with an average size of 5 nm in width and 35 nm in length. The BET surface area was 153 m{sup 2}/g. Unexpectedly, the rice-like TiO{sub 2} nanocrystals exhibited high-temperature phase stability, which could remain as pure anatase phase after calcinations at 1000 °C. Growth mechanism investigation revealed that the IPA solvent played a key role in nucleation and growth of rice-like anatase TiO{sub 2} nanocrystals. The photodegradation of rhodamine B demonstrated that rice-like anatase TiO{sub 2} nanocrystals exhibited enhanced photocatalytic activity under visible light irradiation.

  3. Facile synthesis of high-temperature (1000 °C) phase-stable rice-like anatase TiO2 nanocrystals

    Science.gov (United States)

    Lv, Lizhen; Chen, Qirong; Liu, Xiuyun; Wang, Miaomiao; Meng, Xiangfu

    2015-05-01

    High-temperature phase-stable rice-like anatase TiO2 nanocrystals were synthesized by one-pot solvothermal method using soluble titania xerogel and isopropyl alcohol (IPA) as the precursor and the solvent, respectively. Sample characterization was carried out by powder X-ray diffraction, high-resolution transmission electron microscopy, field emission scanning electron microscope, X-ray photoelectron spectroscopy, and N2 adsorption-desorption isotherms. The results showed that TiO2 nanocrystals had rice-like shapes with an average size of 5 nm in width and 35 nm in length. The BET surface area was 153 m2/g. Unexpectedly, the rice-like TiO2 nanocrystals exhibited high-temperature phase stability, which could remain as pure anatase phase after calcinations at 1000 °C. Growth mechanism investigation revealed that the IPA solvent played a key role in nucleation and growth of rice-like anatase TiO2 nanocrystals. The photodegradation of rhodamine B demonstrated that rice-like anatase TiO2 nanocrystals exhibited enhanced photocatalytic activity under visible light irradiation.

  4. Incorporating an Electrode Modification Layer with a Vertical Phase Separated Photoactive Layer for Efficient and Stable Inverted Nonfullerene Polymer Solar Cells.

    Science.gov (United States)

    Shi, Zhenzhen; Liu, Hao; Wang, Yaping; Li, Jinyan; Bai, Yiming; Wang, Fuzhi; Bian, Xingming; Hayat, Tasawar; Alsaedi, Ahmed; Tan, Zhan'ao

    2017-12-20

    For bulk heterojunction polymer solar cells (PSCs), the donors and acceptors featuring specific phase separation and concentration distribution within the electron donor/acceptor blends crucially affect the exciton dissociation and charge transportation. Herein, efficient and stable nonfullerene inverted PSCs incorporating a phase separated photoactive layer and a titanium chelate electrode modification layer are demonstrated. Water contact angle (WCA), scanning kelvin probe microscopy (SKPM), and atomic force microscopy (AFM) techniques are implemented to characterize the morphology of photoactive layers. Compared with the control conventional device, the short-circuit current density (J sc ) is enhanced from 14.74 to 17.45 mAcm -2 . The power conversion efficiency (PCE) for the inverted PSCs with a titanium (diisopropoxide)-bis-(2,4-pentanedionate) (TIPD) layer increases from 9.67% to 11.69% benefiting from the declined exciton recombination and fairly enhanced charge transportation. Furthermore, the nonencapsulated inverted device with a TIPD layer demonstrates the best long-term stability, 85% of initial PCE remaining and an almost undecayed open-circuit voltage (V oc ) after 1440 h. Our results reveal that the titanium chelate is an excellent electrode modification layer to incorporate with a vertical phase separated photoactive layer for producing high-efficiency and high-stability inverted nonfullerene PSCs.

  5. Phased implementation of spaced clinic visits for stable HIV-positive patients in Rwanda to support Treat All.

    Science.gov (United States)

    Nsanzimana, Sabin; Remera, Eric; Ribakare, Muhayimpundu; Burns, Tracy; Dludlu, Sibongile; Mills, Edward J; Condo, Jeanine; Bucher, Heiner C; Ford, Nathan

    2017-07-21

    In 2016, Rwanda implemented "Treat All," requiring the national HIV programme to increase antiretroviral (ART) treatment coverage to all people living with HIV. Approximately half of the 164,262 patients on ART have been on treatment for more than five years, and long-term retention of patients in care is an increasing concern. To address these challenges, the Ministry of Health has introduced a differentiated service delivery approach to reduce the frequency of clinical visits and medication dispensing for eligible patients. This article draws on key policy documents and the views of technical experts involved in policy development to describe the process of implementation of differentiated service delivery in Rwanda. Implementation of differentiated service delivery followed a phased approach to ensure that all steps are clearly defined and agreed by all partners. Key steps included: definition of scope, including defining which patients were eligible for transition to the new model; definition of the key model components; preparation for patient enrolment; considerations for special patient groups; engagement of implementing partners; securing political and financial support; forecasting drug supply; revision, dissemination and implementation of ART guidelines; and monitoring and evaluation. Based on the outcomes of the evaluation of the new service delivery model, the Ministry of Health will review and strategically reduce costs to the national HIV program and to the patient by exploring and implementing adjustments to the service delivery model.

  6. Ethograms indicate stable well-being during prolonged training phases in rhesus monkeys used in neurophysiological research.

    Science.gov (United States)

    Hage, Steffen R; Ott, Torben; Eiselt, Anne-Kathrin; Jacob, Simon N; Nieder, Andreas

    2014-01-01

    Awake, behaving rhesus monkeys are widely used in neurophysiological research. Neural signals are typically measured from monkeys trained with operant conditioning techniques to perform a variety of behavioral tasks in exchange for rewards. Over the past years, monkeys' psychological well-being during experimentation has become an increasingly important concern. We suggest objective criteria to explore whether training sessions during which the monkeys work under controlled water intake over many days might affect their behavior. With that aim, we analyzed a broad range of species-specific behaviors over several months ('ethogram') and used these ethograms as a proxy for the monkeys' well-being. Our results show that monkeys' behavior during training sessions is unaffected by the duration of training-free days in-between. Independently of the number of training-free days (two or nine days) with ad libitum food and water supply, the monkeys were equally active and alert in their home group cages during training phases. This indicates that the monkeys were well habituated to prolonged working schedules and that their well-being was stably ensured during the training sessions.

  7. Iron in carbonate containing AFm phases

    International Nuclear Information System (INIS)

    Dilnesa, B.Z.; Lothenbach, B.; Le Saout, G.; Renaudin, G.; Mesbah, A.; Filinchuk, Y.; Wichser, A.; Wieland, E.

    2011-01-01

    One of the AFm phases in hydrated Portland cement is Ca 3 (Al x Fe 2 - x )O 6 .CaCO 3 .nH 2 O. It is based on hexagonal and platey structural elements and the interlayer structure incorporates CO 3 2- . The solid phases were experimentally synthesized and characterized by different techniques including X-ray techniques (XRD and EXAFS) and vibrational spectroscopy techniques (IR, Raman). Fe-monocarbonate (Fe-Mc) and Al-monocarbonate (Al-Mc) were found to be stable up to 50 o C, while Fe-hemicarbonate (Fe-Hc) was unstable with respect to Fe-Mc in the presence of calcite. Fe-Mc has a rhombohedral R3-barc symmetry which is different from the triclinic of the Al analogue. Both XRD and thermodynamic modelling of the liquid compositions indicated that Al-Mc and the Fe-Mc phases do not form solid solution. The solubility products were calculated experimentally at 20 o C and 50 o C. Under standards condition the solubility products and other thermodynamic parameters were estimated using temperature-solubility product extrapolation and found to be logK S0 (Fe-Mc) = -34.59 ± 0.50, logK S0 (Fe-Hc) = -30.83 ± 0.50 and logK S0 (Al-Mc) = -31.32 ± 0.50.

  8. Characterization of polymethyl methacrylate/polyethylene glycol/aluminum nitride composite as form-stable phase change material prepared by in situ polymerization method

    International Nuclear Information System (INIS)

    Zhang, Lei; Zhu, Jiaoqun; Zhou, Weibin; Wang, Jun; Wang, Yan

    2011-01-01

    Highlights: → Form-stable PMMA/PEG/AlN PCMs were prepared by in situ polymerization method. → AlN additive effectively enhanced the heat transfer property of composite PCMs. → The composites exhibited desirable thermal performance and electric insulativity. → The composites were available for the thermal management of electronic device. - Abstract: This work was focused on the preparation and characterization of a new type of form-stable phase change material (PCM) employed in thermal management. Using the method of in situ polymerization, polyethylene glycol (PEG) acting as the PCM and aluminum nitride (AlN) serving as the thermal conductivity promoter were uniformly encapsulated and embedded inside the three-dimensional network structure of PMMA matrix. When the mass fraction of PEG was below 70%, the prepared composite PCMs remained solid without leakage above the melting point of the PEG. XRD and FT-IR results indicated that the PEG was physically combined with PMMA matrix and AlN additive and did not participate in the polymerization. Thermal analysis results showed that the prepared composite PCMs possess available latent heat capacity and thermal stability, and the AlN additive was able to effectively enhance the heat transfer property of organic PCM. Moreover, the volume resistivity of composite achieved (5.92 ± 0.16) x 10 10 Ω cm when the mass ratio of AlN was 30%. To sum up, the prepared form-stable PCMs were competent for the thermal management of electronic device due to their acceptable thermal performance and electric insulativity.

  9. Experiment study on the thermal properties of paraffin/kaolin thermal energy storage form-stable phase change materials

    International Nuclear Information System (INIS)

    Lv, Peizhao; Liu, Chenzhen; Rao, Zhonghao

    2016-01-01

    Highlights: • Different particle sizes of kaolin were employed to load paraffin. • The effects and reasons of particle size on thermal conductivity were studied. • Thermal property and thermal stability of the composites were investigated. • The leakage and thermal storage and release rate of the composites were studied. • The effect of vacuum impregnation method on thermal conductivity was investigated. - Abstract: In this paper, different particle sizes of kaolin were employed to incorporate paraffin via vacuum impregnation method. The paraffin/kaolin composites were characterized by Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimeter (DSC) and Thermogravimetry (TG). The results showed that the paraffin/kaolin composite with the largest particle size of kaolin (K4) has the highest thermal conductivity (0.413 W/(m K) at 20 °C) among the diverse composites. The latent heat capacity of paraffin/K4 is 119.49 J/g and the phase change temperature is 62.4 °C. In addition, the thermal properties and thermal conductivities of paraffin/K4 with different mass fraction of K4 (0–60%) were investigated. The thermal conductivities of the composites were explained in microcosmic field. The phonon mean free path determines the thermal conductivity, and it can be significantly affected by temperature and the contact surface area. The leaks, thermal storage and release properties of pure paraffin and paraffin/kaolin composites were investigated and the composites presented good thermal stabilities.

  10. Entropy stable modeling of non-isothermal multi-component diffuse-interface two-phase flows with realistic equations of state

    KAUST Repository

    Kou, Jisheng; Sun, Shuyu

    2018-01-01

    In this paper, we consider mathematical modeling and numerical simulation of non-isothermal compressible multi-component diffuse-interface two-phase flows with realistic equations of state. A general model with general reference velocity is derived rigorously through thermodynamical laws and Onsager's reciprocal principle, and it is capable of characterizing compressibility and partial miscibility between multiple fluids. We prove a novel relation among the pressure, temperature and chemical potentials, which results in a new formulation of the momentum conservation equation indicating that the gradients of chemical potentials and temperature become the primary driving force of the fluid motion except for the external forces. A key challenge in numerical simulation is to develop entropy stable numerical schemes preserving the laws of thermodynamics. Based on the convex-concave splitting of Helmholtz free energy density with respect to molar densities and temperature, we propose an entropy stable numerical method, which solves the total energy balance equation directly, and thus, naturally satisfies the first law of thermodynamics. Unconditional entropy stability (the second law of thermodynamics) of the proposed method is proved by estimating the variations of Helmholtz free energy and kinetic energy with time steps. Numerical results validate the proposed method.

  11. Entropy stable modeling of non-isothermal multi-component diffuse-interface two-phase flows with realistic equations of state

    KAUST Repository

    Kou, Jisheng

    2018-02-25

    In this paper, we consider mathematical modeling and numerical simulation of non-isothermal compressible multi-component diffuse-interface two-phase flows with realistic equations of state. A general model with general reference velocity is derived rigorously through thermodynamical laws and Onsager\\'s reciprocal principle, and it is capable of characterizing compressibility and partial miscibility between multiple fluids. We prove a novel relation among the pressure, temperature and chemical potentials, which results in a new formulation of the momentum conservation equation indicating that the gradients of chemical potentials and temperature become the primary driving force of the fluid motion except for the external forces. A key challenge in numerical simulation is to develop entropy stable numerical schemes preserving the laws of thermodynamics. Based on the convex-concave splitting of Helmholtz free energy density with respect to molar densities and temperature, we propose an entropy stable numerical method, which solves the total energy balance equation directly, and thus, naturally satisfies the first law of thermodynamics. Unconditional entropy stability (the second law of thermodynamics) of the proposed method is proved by estimating the variations of Helmholtz free energy and kinetic energy with time steps. Numerical results validate the proposed method.

  12. Quantitation of (R)- and (S)-linalool in beer using solid phase microextraction (SPME) in combination with a stable isotope dilution assay (SIDA).

    Science.gov (United States)

    Steinhaus, Martin; Fritsch, Helge T; Schieberle, Peter

    2003-11-19

    A stable isotope dilution assay (SIDA) was developed for the quantitation of both linalool enantiomers using synthesized [2H(2)]R/S-linalool as the internal standard. For enrichment of the target compound from beer, a solid phase microextraction method (SPME) was developed. In comparison to the more time-consuming extraction/distillation cleanup of the beer samples, the results obtained by SPME/SIDA were very similar, even under nonequilibration conditions. Analysis of five different types of beer showed significant differences in the linalool concentrations, which were clearly correlated with the intensity of the hoppy aroma note as evaluated by a sensory panel. In addition, significant differences in the R/S ratios were measured in the beers. The SPME/SIDA yielded exact data independently from headspace sampling parameters, such as exposure time or ionic strength of the solution.

  13. Intensity effects in the formation of stable islands in phase space during the multi-turn extraction process at the CERN PS

    CERN Document Server

    Machida, Shinji; Prior, Chris; Gilardoni, Simone; Giovannozzi, Massimo; Hirlander, Simon; Huschauer, Alexander

    2016-01-01

    The CERN PS utilises a Multi-Turn Extraction (MTE) scheme to stretch the beam pulse length to optimise the filling process of the SPS. MTE is a novel technique to split a beam in transverse phase space into nonlinear stable islands. The recent experimental results indicate that the positions of the islands depend on the total beam intensity. Particle simulations have been performed to understand the detailed mechanism of the intensity dependence. The analysis carried out so far suggests space charge effects through image charges and image currents on the vacuum chamber and the magnets iron cores dominate the observed behaviour. In this talk, the latest analysis with realistic modelling of the beam environment is discussed and it is shown how this further improves the understanding of intensity effects in MTE.

  14. Conversion From Twice-Daily Tacrolimus Capsules to Once-Daily Extended-Release Tacrolimus (LCPT): A Phase 2 Trial of Stable Renal Transplant Recipients

    Science.gov (United States)

    Gaber, A. Osama; Alloway, Rita R.; Bodziak, Kenneth; Kaplan, Bruce; Bunnapradist, Suphamai

    2013-01-01

    Background LCP-Tacro is an extended-release formulation of tacrolimus designed for once-daily dosing. Phase 1 studies demonstrated greater bioavailability to twice-daily tacrolimus capsules and no new safety concerns. Methods In this phase 2 study, adult stable kidney transplant patients on tacrolimus capsules (Prograf) twice-daily were converted to tacrolimus tablets (LCP-Tacro) once-daily; patients continued on LCP-Tacro once-daily for days 8 to 21; trough levels were to be maintained between 5 and 15 ng/mL; 24-hr pharmacokinetic assessments were done on days 7 (baseline pre-switch), 14, and 21. Results Forty-seven patients completed LCP-Tacro dosing per protocol. The mean conversion ratio was 0.71. Pharmacokinetic data demonstrated consistent exposure (AUC) at the lower conversion dose. Cmax (P=0.0001), Cmax/Cmin ratio (P<0.001), percent fluctuation (P<0.0001), and swing (P=0.0004) were significantly lower and Tmax significantly (P<0.001) longer for LCP-Tacro versus Prograf. AUC24 and Cmin correlation coefficients after 7 and 14 days of therapy were 0.86 or more, demonstrating a robust correlation between LCP-Tacro tacrolimus exposure and trough levels. There were three serious adverse events; none were related to study drug and all were resolved. Conclusions Stable kidney transplant patients can be safely converted from Prograf twice-daily to LCP-Tacro. The greater bioavailability of LCP-Tacro allows for once-daily dosing and similar (AUC) exposure at a dose approximately 30% less than the total daily dose of Prograf. LCP-Tacro displays flatter kinetics characterized by significantly lower peak-trough fluctuations. PMID:23715050

  15. Towards a new classification of stable phase schizophrenia into major and simple neuro-cognitive psychosis: Results of unsupervised machine learning analysis.

    Science.gov (United States)

    Kanchanatawan, Buranee; Sriswasdi, Sira; Thika, Supaksorn; Stoyanov, Drozdstoy; Sirivichayakul, Sunee; Carvalho, André F; Geffard, Michel; Maes, Michael

    2018-05-23

    Deficit schizophrenia, as defined by the Schedule for Deficit Syndrome, may represent a distinct diagnostic class defined by neurocognitive impairments coupled with changes in IgA/IgM responses to tryptophan catabolites (TRYCATs). Adequate classifications should be based on supervised and unsupervised learning rather than on consensus criteria. This study used machine learning as means to provide a more accurate classification of patients with stable phase schizophrenia. We found that using negative symptoms as discriminatory variables, schizophrenia patients may be divided into two distinct classes modelled by (A) impairments in IgA/IgM responses to noxious and generally more protective tryptophan catabolites, (B) impairments in episodic and semantic memory, paired associative learning and false memory creation, and (C) psychotic, excitation, hostility, mannerism, negative, and affective symptoms. The first cluster shows increased negative, psychotic, excitation, hostility, mannerism, depression and anxiety symptoms, and more neuroimmune and cognitive disorders and is therefore called "major neurocognitive psychosis" (MNP). The second cluster, called "simple neurocognitive psychosis" (SNP) is discriminated from normal controls by the same features although the impairments are less well developed than in MNP. The latter is additionally externally validated by lowered quality of life, body mass (reflecting a leptosome body type), and education (reflecting lower cognitive reserve). Previous distinctions including "type 1" (positive)/"type 2" (negative) and DSM-IV-TR (eg, paranoid) schizophrenia could not be validated using machine learning techniques. Previous names of the illness, including schizophrenia, are not very adequate because they do not describe the features of the illness, namely, interrelated neuroimmune, cognitive, and clinical features. Stable-phase schizophrenia consists of 2 relevant qualitatively distinct categories or nosological entities with SNP

  16. Stable isotopes

    International Nuclear Information System (INIS)

    Evans, D.K.

    1986-01-01

    Seventy-five percent of the world's stable isotope supply comes from one producer, Oak Ridge Nuclear Laboratory (ORNL) in the US. Canadian concern is that foreign needs will be met only after domestic needs, thus creating a shortage of stable isotopes in Canada. This article describes the present situation in Canada (availability and cost) of stable isotopes, the isotope enrichment techniques, and related research programs at Chalk River Nuclear Laboratories (CRNL)

  17. Filling the gap in Ca input-output budgets in base-poor forest ecosystems: The contribution of non-crystalline phases evidenced by stable isotopic dilution

    Science.gov (United States)

    van der Heijden, Gregory; Legout, Arnaud; Mareschal, Louis; Ranger, Jacques; Dambrine, Etienne

    2017-07-01

    In terrestrial ecosystems, plant-available pools of magnesium and calcium are assumed to be stored in the soil as exchangeable cations adsorbed on the surface of mineral and/or organic particles. The pools of exchangeable magnesium and calcium are measured by ion-exchange soil extractions. These pools are sustained in the long term by the weathering of primary minerals in the soil and atmospheric inputs. This conceptual model is the base of input-output budgets from which soil acidification and the sustainability of soil chemical fertility is inferred. However, this model has been questioned by data from long-term forest ecosystem monitoring sites, particularly for calcium. Quantifying the contribution of atmospheric inputs, ion exchange and weathering of both primary, secondary and non-crystalline phases to tree nutrition in the short term is challenging. In this study, we developed and applied a novel isotopic dilution technique using the stable isotopes of magnesium and calcium to study the contribution of the different soil phases to soil solution chemistry in a very acidic soil. The labile pools of Mg and Ca in the soil (pools in equilibrium with the soil solution) were isotopically labeled by spraying a solution enriched in 26Mg and 44Ca on the soil. Labeled soil columns were then percolated with a dilute acid solution during a 3-month period and the isotopic dilution of the tracers was monitored in the leaching solution, in the exchangeable (2 sequential 1 mol L-1 ammonium acetate extractions) and non-crystalline (2 sequential soil digestions: oxalic acid followed by nitric acid) phases. Significant amounts of Mg and Ca isotope tracer were recovered in the non-crystalline soil phases. These phases represented from 5% to 25% and from 24% to 50%, respectively, of the Mg and Ca labile pools during the experiment. Our results show that non-crystalline phases act as both a source and a sink of calcium and magnesium in the soil, and contribute directly to soil

  18. Paramagnetic centers in two phases of manganese-doped lanthanum gallate

    Science.gov (United States)

    Vazhenin, V. A.; Potapov, A. P.; Guseva, V. B.; Artyomov, M. Yu.

    2009-05-01

    An EPR study of two phases of manganese-doped lanthanum gallate (with a first-order structural transition occurring at 430 K) has revealed Gd3+, Fe3+, and Mn4+ centers at room temperature and 438 K. The parameters of spin Hamiltonians are determined for the Gd3+, Fe3+, and Mn4+ rhombohedral centers in the high-temperature phase (with no other centers found here) and for the monoclinic center Gd3+ in the low-temperature phase. Both in the orthorhombic and in the rhombohedral phase, crystallographic twins (or ferroelastic domains) are observed.

  19. Hexagonal perovskites with cationic vacancies. 24. Rhombohedral 9 L stacking polytypes in the systems Ba/sub 3/Wsub(2-x)sup(VI)Msub(x)sup(V)vacantOsub(9-x/2)vacantsub(x/2) with Msup(V) = Nb, Ta

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1980-12-01

    In the system Ba/sub 3/Wsub(2-x)sup(VI)Nbsub(x)sup(V)vacantOsub(9-x/2)vacantsub(x/2) stacking polytypes of rhombohedral 9 L type (sequence (hhc)/sub 3/; space group R-3m) can be prepared with approximately 1/3 <= x <= 2. For x = 2(Ba/sub 3/Nb/sub 2/vacantO/sub 8/vacant) two modifications are formed. In the corresponding Ta system the phase width is reduced to a smaller region with x approximately 1/3.

  20. Scaled-up solvothermal synthesis of nanosized metastable indium oxyhydroxide (InOOH) and corundum-type rhombohedral indium oxide (rh-In{sub 2}O{sub 3})

    Energy Technology Data Exchange (ETDEWEB)

    Schlicker, Lukas; Bekheet, Maged F.; Gurlo, Aleksander [Technische Univ. Berlin (Germany). Fachgebiet Keramische Werkstoffe

    2017-03-01

    Phase pure metastable indium oxyhydroxide (InOOH) with crystallite size in the range ca. 2-7 nm is synthesized by a nonaqueous solvothermal synthesis route in ethanol. The influence of synthesis parameters such as temperature, basicity (pH), synthesis time, and water content is carefully addressed. T-pH maps summarize the impact of synthesis temperature and pH and reveal that phase pure InOOH is obtained in water-free solutions at mild temperatures (150-180 C) in highly basic conditions (pH>12). Subsequent calcination of InOOH at 375-700 C in ambient air atmosphere results in metastable nanoscaled rhombohedral indium oxide (rh-In{sub 2}O{sub 3}). The synthesis protocol for phase pure nanocrystalline InOOH material was successfully upscaled allowing for obtaining ca. 3 g of phase-pure InOOH with a yield of ca. 78%. The upscaled InOOH and rh-In{sub 2}O{sub 3} batches are now available for a detailed in-situ characterization of the mechanism of decomposition of InOOH to rh-In{sub 2}O{sub 3} to c-In{sub 2}O{sub 3} as well as for the characterization of the functional properties of InOOH and rh-In{sub 2}O{sub 3} materials.

  1. High-pressure phases of CuI studied by 129I-Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Kaindl, G.; Nowik, I.; Frank, K.H.

    1992-01-01

    The results of an 129 I-Moessbauer study of the high-pressure phases of CuI at 4.2 K and for external pressures up to 71 kbar are reported. The isomer shift S and the electric quadrupole interaction E q are found to undergo large discontinuities at the crystallographic phase-transition pressures of ≅18 kbar from zinc-blende to rhombohedral structure and at ≅46 kbar from rhombohedral to tetragonal. The pressure coefficients of these hyperfine parameters are significantly different for the three phases (zinc-blende; rhombohedral; tetragonal): dS/dP=-3.3; =+1.5; =+2.5x10 -3 mm/s/kbar. These results cannot be explained in terms of a simple molecular-orbital picture; instead, they reflect pressure-induced variations of the halogen-p/metal-d hybridization in the valence bands of the various phases of CuI. (orig.)

  2. Preparation, morphology and thermal properties of electrospun fatty acid eutectics/polyethylene terephthalate form-stable phase change ultrafine composite fibers for thermal energy storage

    International Nuclear Information System (INIS)

    Cai Yibing; Ke Huizhen; Lin Liang; Fei Xiuzhu; Wei Qufu; Song Lei; Hu Yuan; Fong Hao

    2012-01-01

    Highlights: ► Electrospun binary fatty acid eutectics/PET ultrafine composite fibers were prepared. ► Fatty acid eutectics had appropriate phase transition temperature and heat enthalpy. ► Their morphological structures and thermal properties were different from each other. ► Composite fibers could be innovative form-stable PCMs for thermal energy storage. - Abstract: The ultrafine composite fibers based on the composites of binary fatty acid eutectics and polyethylene terephthalate (PET) with varied fatty acid eutectics/PET mass ratios (50/100, 70/100, 100/100 and 120/100) were fabricated using the technique of electrospinning as form-stable phase change materials (PCMs). The five binary fatty acid eutectics including LA–MA, LA–PA, MA–PA, MA–SA and PA–SA were prepared according to Schrader equation, and then were selected as an innovative type of solid–liquid PCMs. The results characterized by differential scanning calorimeter (DSC) indicated that the prepared binary fatty acid eutectics with low phase transition temperatures and high heat enthalpies for climatic requirements were more suitable for applications in building energy storage. The structural morphologies, thermal energy storage and thermal stability properties of the ultrafine composite fibers were investigated by scanning electron microscope (SEM), DSC and thermogravimetric analysis (TGA), respectively. SEM images revealed that the electrospun binary fatty acid eutectics/PET ultrafine composite fibers possessed the wrinkled surfaces morphologies compared with the neat PET fibers with cylindrical shape and smooth surfaces; the grooves or ridges on the corrugated surface of the ultrafine composite fibers became more and more prominent with increasing fatty acid eutectics amount in the composite fibers. The fibers with the low mass ratio maintained good structural morphologies while the quality became worse when the mass ratio is too high (more than 100/100). DSC measurements

  3. Thermal and electrical conductivity enhancement of graphite nanoplatelets on form-stable polyethylene glycol/polymethyl methacrylate composite phase change materials

    International Nuclear Information System (INIS)

    Zhang, Lei; Zhu, Jiaoqun; Zhou, Weibing; Wang, Jun; Wang, Yan

    2012-01-01

    Graphite nanoplatelets (GnPs), obtained by sonicating the expanded graphite, were employed to simultaneously enhance the thermal (k) and electrical (σ) conductivity of organic form-stable phase change materials (FSPCMs). Using the method of in situ polymerization upon ultrasonic irradiation, GnPs serving as the conductive fillers and polyethylene glycol (PEG) acting as the phase change material (PCM) were uniformly dispersed and embedded inside the network structure of polymethyl methacrylate (PMMA), which contributed to the well package and self-supporting properties of composite FSPCMs. X-ray diffraction and Fourier transform infrared spectroscopy results indicated that the GnPs were physically combined with PEG/PMMA matrix and did not participate in the polymerization. The GnPs additives were able to effectively enhance the k and σ of organic FSPCM. When the mass ratio of GnP was 8%, the k and σ of FSPCM changed up to 9 times and 8 orders of magnitude over that of PEG/PMMA matrix, respectively. The improvements in both k and σ were mainly attributed to the well dispersion and large aspect ratio of GnPs, which were endowed with benefit of forming conducting network in polymer matrix. It was also confirmed that all the prepared specimens possessed available thermal storage density and thermal stability. -- Highlights: ► GnPs were employed to simultaneously enhance the k and σ of organic FSPCMs. ► PEG/PMMA/GnPs composite FSPCMs were prepared by in situ polymerization method. ► The composite FSPCMs exhibited well package and self-supporting properties. ► GnPs additives effectively enhanced the k and σ of composite FSPCMs. ► All the composites possessed available thermal storage density and thermal stability.

  4. Analysis of South Atlantic Anomaly perturbations on Sentinel-3A Ultra Stable Oscillator. Impact on DORIS phase measurement and DORIS station positioning

    Science.gov (United States)

    Jalabert, Eva; Mercier, Flavien

    2018-07-01

    DORIS measurements rely on the precise knowledge of the embedded oscillator which is called the Ultra Stable Oscillator (DORIS USO). The important radiations in the South Atlantic Anomaly (SAA) perturb the USO behavior by causing rapid frequency variations when the satellite is flying through the SAA. These variations are not taken into account in standard DORIS processing, since the USO is modelled as a third degree polynomial over 7-10 days. Therefore, there are systematic measurements errors when the satellite passes through SAA. In standard GNSS processing, the clock is directly estimated at each epoch. On Sentinel-3A, the GPS receiver and the DORIS receiver use the same USO. It is thus possible to estimate the behavior of the USO using GPS measurements. This estimated USO behavior can be used in the DORIS processing, instead of the third degree polynomial, hence allowing an estimation of the orbit sensitivity to these USO anomalies. This study shows two main results. First, the SAA effect on the DORIS USO is observed well using GPS measurements. Second, the USO behavior observed with GPS can be used to mitigate the SAA effect. Indeed, when used in Sentinel-3A processing, the resulting DORIS orbit shows improved phase measurements and station positioning for stations inside the SAA (Arequipa and Cachoeira). The phase measurements residuals are improved by up to 10 cm, and station vertical positioning (i.e. on the estimated Up component in the North-East-Up station frame) is improved by up to a few centimeters. However, the orbit itself is not sensitive to the correction because only two stations (out of almost 60) are SAA-sensitive on Sentinel-3A.

  5. Properties of form-stable paraffin/silicon dioxide/expanded graphite phase change composites prepared by sol–gel method

    International Nuclear Information System (INIS)

    Li, Min; Wu, Zhishen; Tan, Jinmiao

    2012-01-01

    Highlights: ► Paraffin/SiO 2 /EG composite PCM was prepared with sol–gel method. ► The thermal conductivity of SiO 2 /paraffin/EG is 94.7% higher than paraffin. ► The latent heat of paraffin/SiO 2 /EG composite is 104.4 J/g. -- Abstract: A form-stable paraffin/silicon dioxide (SiO 2 )/expanded graphite (EG) composite phase change material (PCM) was prepared by sol–gel method. Silica gel acts as the supporting material and EG is used to increase the thermal conductivity. The mass fractions of silicon oxide and graphite are 20.8% and 7.2%, respectively. The composite PCM was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transformation infrared spectroscopy (FTIR) method. Thermal properties and thermal stability of the composite PCM were studied using differential scanning calorimetry (DSC). The result shows that paraffin was well dispersed in the network of silica gel and there is no chemical reaction between them. The phase change temperature of the paraffin/SiO 2 composite and the paraffin/SiO 2 /EG composite are 27.53 °C and 27.72 °C, respectively. The latent heat of the paraffin/SiO 2 composite and the paraffin/SiO 2 /EG composite are 112.8 J/g and 104.4 J/g, respectively. The thermal conductivity of the SiO 2 /paraffin composite and the SiO 2 /paraffin/EG composite are 28.2% and 94.7% higher than that of paraffin.

  6. Quantification of 2-acetyl-1-pyrroline in rice by stable isotope dilution assay through headspace solid-phase microextraction coupled to gas chromatography-tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Maraval, Isabelle [UMR Qualisud, CIRAD, 73 Rue J. F. Breton, 34398 Montpellier Cedex 5 (France); UMR Qualisud, Universite Montpellier 2, place E. Bataillon, 34095 Montpellier Cedex 5 (France); Sen, Kemal [Department of Food Engineering, Faculty of Agriculture, University of Cukurova, 01330 Adana (Turkey); Agrebi, Abdelhamid; Menut, Chantal; Morere, Alain [UMR 5247, Institut des Biomolecules Max Mousseron (IBMM), CNRS, Universites Montpellier 2 et 1, Ecole Nationale Superieure de Chimie de Montpellier, 8 Rue de l' Ecole Normale, 34296 Montpellier Cedex 5 (France); Boulanger, Renaud [UMR Qualisud, CIRAD, 73 Rue J. F. Breton, 34398 Montpellier Cedex 5 (France); Gay, Frederic [CIRAD, DORAS Centre, Research and Development Building, Kasetsart University, Bangkok 10900 (Thailand); Mestres, Christian [UMR Qualisud, CIRAD, 73 Rue J. F. Breton, 34398 Montpellier Cedex 5 (France); Gunata, Ziya, E-mail: zgunata@univ-montp2.fr [UMR Qualisud, Universite Montpellier 2, place E. Bataillon, 34095 Montpellier Cedex 5 (France)

    2010-08-24

    A new and convenient synthesis of 2-acetyl-1-pyrroline (2AP), a potent flavor compound in rice, and its ring-deuterated analog, 2-acetyl-1-d{sub 2}-pyrroline (2AP-d{sub 2}), was reported. A stable isotope dilution assay (SIDA), involving headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-positive chemical ionization-ion trap-tandem mass spectrometry (GC-PCI-IT-MS-MS), was developed for 2AP quantification. A divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber was used for HS-SPME procedure and parameters affecting analytes recovery, such as extraction time and temperature, pH and salt, were studied. The repeatability of the method (n = 10) expressed as relative standard deviation (RSD) was 11.6%. A good linearity was observed from 5.9 to 779 ng of 2AP (r{sup 2} = 0.9989). Limits of detection (LOD) and quantification (LOQ) for 2AP were 0.1 and 0.4 ng g{sup -1} of rice, respectively. The recovery of spiked 2AP from rice matrix was almost complete. The developed method was applied to the quantification of 2AP in aerial parts and grains of scented and non-scented rice cultivars.

  7. Synthesis and stable isotope dilution assay of ethanethiol and diethyl disulfide in wine using solid phase microextraction. Effect of aging on their levels in wine.

    Science.gov (United States)

    Belancic Majcenovic, Andrea; Schneider, Rémi; Lepoutre, Jean-Paul; Lempereur, Valérie; Baumes, Raymond

    2002-11-06

    Ethanethiol and diethyl disulfide (DEDS) most often occurred at levels above their olfactive threshold in wines with nauseous sulfur-linked smells. As ethanethiol is very oxidizable and chemically reactive, a stable isotopic dilution analysis of both ethanethiol and its disulfide in wines using solid phase microextraction and GC-MS was developed. The latter involved the determination of the proportion of DEDS formed by oxidation of the thiol during the analysis conditions, which was obtained by the use of two differently labeled disulfide standards. An original synthesis of labeled ethanethiol standards in conditions minimizing oxidation was developed, and the corresponding labeled diethyl disulfides were obtained from these thiols. This analytical method was used to follow the levels of these sulfur compounds during aging in a young red wine spiked with ethanethiol and added with enological tannins, with or without oxygen addition. The total levels of these two sulfur compounds were shown to decrease steadily after 60 days of aging, up to 83%. The effect of oxygen sped this decrease, but the effect of enological tannins was very slight. Residual ethanethiol was detected in its disulfide form from approximately 36% in the nonoxygenated wines to 69% in the oxygenated samples.

  8. Preparation and thermal properties of mineral-supported polyethylene glycol as form-stable composite phase change materials (CPCMs) used in asphalt pavements.

    Science.gov (United States)

    Jin, Jiao; Lin, Feipeng; Liu, Ruohua; Xiao, Ting; Zheng, Jianlong; Qian, Guoping; Liu, Hongfu; Wen, Pihua

    2017-12-05

    Three kinds of mineral-supported polyethylene glycol (PEG) as form-stable composite phase change materials (CPCMs) were prepared to choose the most suitable CPCMs in asphalt pavements for the problems of asphalt pavements rutting diseases and urban heat islands. The microstructure and chemical structure of CPCMs were characterized by SEM, FT-IR and XRD. Thermal properties of the CPCMs were determined by TG and DSC. The maximum PEG absorption of diatomite (DI), expanded perlite (EP) and expanded vermiculite (EVM) could reach 72%, 67% and 73.6%, respectively. The melting temperatures and latent heat of CPCMs are in the range of 52-55 °C and 100-115 J/g, respectively. The results show that PEG/EP has the best thermal and chemical stability after 100 times of heating-cooling process. Moreover, crystallization fraction results show that PEG/EP has slightly higher latent heats than that of PEG/DI and PEG/EVM. Temperature-adjusting asphalt mixture was prepared by substituting the fine aggregates with PEG/EP CPCMs. The upper surface maximum temperature difference of temperature-adjusting asphalt mixture reaches about 7.0 °C in laboratory, and the surface peak temperature reduces up to 4.3 °C in the field experiment during a typical summer day, indicating a great potential application for regulating pavement temperature field and alleviating the urban heat islands.

  9. An energy stable algorithm for a quasi-incompressible hydrodynamic phase-field model of viscous fluid mixtures with variable densities and viscosities

    Science.gov (United States)

    Gong, Yuezheng; Zhao, Jia; Wang, Qi

    2017-10-01

    A quasi-incompressible hydrodynamic phase field model for flows of fluid mixtures of two incompressible viscous fluids of distinct densities and viscosities is derived by using the generalized Onsager principle, which warrants the variational structure, the mass conservation and energy dissipation law. We recast the model in an equivalent form and discretize the equivalent system in space firstly to arrive at a time-dependent ordinary differential and algebraic equation (DAE) system, which preserves the mass conservation and energy dissipation law at the semi-discrete level. Then, we develop a temporal discretization scheme for the DAE system, where the mass conservation and the energy dissipation law are once again preserved at the fully discretized level. We prove that the fully discretized algorithm is unconditionally energy stable. Several numerical examples, including drop dynamics of viscous fluid drops immersed in another viscous fluid matrix and mixing dynamics of binary polymeric solutions, are presented to show the convergence property as well as the accuracy and efficiency of the new scheme.

  10. Unconditionally stable methods for simulating multi-component two-phase interface models with Peng-Robinson equation of state and various boundary conditions

    KAUST Repository

    Kou, Jisheng

    2015-03-01

    In this paper, we consider multi-component dynamic two-phase interface models, which are formulated by the Cahn-Hilliard system with Peng-Robinson equation of state and various boundary conditions. These models can be derived from the minimum problems of Helmholtz free energy or grand potential in the realistic thermodynamic systems. The resulted Cahn-Hilliard systems with various boundary conditions are fully coupled and strongly nonlinear. A linear transformation is introduced to decouple the relations between different components, and as a result, the models are simplified. From this, we further propose a semi-implicit unconditionally stable time discretization scheme, which allows us to solve the Cahn-Hilliard system by a decoupled way, and thus, our method can significantly reduce the computational cost and memory requirements. The mixed finite element methods are employed for the spatial discretization, and the approximate errors are also analyzed for both space and time. Numerical examples are tested to demonstrate the efficiency of our proposed methods. © 2015 Elsevier B.V.

  11. A new approach to establish both stable and metastable phase equilibria for fcc ordered/disordered phase transition: application to the Al–Ni and Ni–Si systems

    International Nuclear Information System (INIS)

    Yuan Xiaoming; Zhang Lijun; Du Yong; Xiong Wei; Tang Ying; Wang Aijun; Liu Shuhong

    2012-01-01

    Both two-sublattice (2SL) and four-sublattice (4SL) models in the framework of the compound energy formalism can be used to describe the fcc ordered/disordered transitions. When transferring the parameters of 2SL disregarding the metastable ordered states into those of 4SL, inconsistence in either stable or metastable phase diagrams could appear, as detected in both Al–Ni and Ni–Si systems. To avoid such a kind of drawback, this behavior was analyzed and investigated in the Ni–Si and Al–Ni systems with the aid of first–principle calculations. Furthermore, a new approach considering both the stable and metastable fcc ordered phase equilibria deduced from the first–principles calculations was proposed to perform a reliable thermodynamic modeling for the fcc ordered/disordered transition. The Ni–Si system was then thermodynamically assessed using the presently proposed approach. The good agreement between the calculation and experiments demonstrates the reliability of the proposed approach. It is expected that the approach is valid for other systems showing complex ordered/disordered transitions. - Highlights: ► We discuss the drawbacks of order/disorder modeling in the Ni–Si and Al–Ni systems. ► We perform ab initio calculation of thermodynamic properties in the Ni–Si system. ► A CALPHAD–type approach is proposed to model the fcc ordered/disordered transition. ► The Ni–Si system was thermodynamically assessed using the new approach.

  12. Preparation, thermal and flammability properties of a novel form-stable phase change materials based on high density polyethylene/poly(ethylene-co-vinyl acetate)/organophilic montmorillonite nanocomposites/paraffin compounds

    International Nuclear Information System (INIS)

    Cai Yibing; Song Lei; He Qingliang; Yang Dandan; Hu Yuan

    2008-01-01

    The paraffin is one of important thermal energy storage materials with many desirable characteristics (i.e., high heat of fusion, varied phase change temperature, negligible supercooling, self-nucleating, no phase segregation and cheap, etc.), but has low thermal stability and flammable. Hence, a novel form-stable phase change materials (PCM) based on high density polyethylene (HDPE)/poly(ethylene-co-vinyl acetate) (EVA)/organophilic montmorillonite (OMT) nanocomposites and paraffin are prepared by twin-screw extruder technique. The structures of the HDPE-EVA/OMT nanocomposites and the form-stable PCM are evidenced by the X-ray diffraction (XRD), transmission electronic microscopy (TEM) and scanning electronic microscope (SEM). The results of XRD and TEM show that the HDPE-EVA/OMT nanocomposites form the ordered intercalated nanomorphology. The form-stable PCM consists of the paraffin, which acts as a dispersed phase change material and the HDPE-EVA/OMT nanocomposites, which acts as the supporting material. The paraffin disperses in the three-dimensional net structure formed by HDPE-EVA/OMT nanocomposites. The thermal stability, latent heat and flammability properties are characterized by thermogravimetry analysis (TGA), dynamic Fourier-transform infrared (FTIR), differential scanning calorimeter (DSC) and cone calorimeter, respectively. The TGA and dynamic FTIR analyses indicate that the incorporation of suitable amount of OMT into the form-stable PCM increase the thermal stability. The DSC results show that the latent heat of the form-stable PCM has a certain degree decrease. The cone calorimeter shows that the heat release rate (HRR) has remarkably decreases with loading of OMT in the form-stable PCM, contributing to the improved flammability properties

  13. Unpredictably Stable

    DEFF Research Database (Denmark)

    Failla, Virgilio; Melillo, Francesca; Reichstein, Toke

    2014-01-01

    Is entrepreneurship a more stable career choice for high employment turnover individuals? We find that a transition to entrepreneurship induces a shift towards stayer behavior and identify job matching, job satisfaction and lock-in effects as main drivers. These findings have major implications...

  14. Metastable and stable magnetic phases in as-cast and annealed Pr80Fe15(B1-xCx)5 alloys (0.0≤x≤1.0)

    International Nuclear Information System (INIS)

    Sanchez Llamazares, J.L.; Lopez, G.; Fidler, J.

    1998-01-01

    In as-cast Pr 80 Fe 15 (B 1-x C x ) 5 , samples metastable A 1 (T c =225 C) was the predominant magnetic phase in the whole composition range, with intrinsic properties that were not affected with increasing C content. Up to x=0.75 this phase coexists with an additional minor magnetic phase having T c =263 C which has been labelled by us to as A 3 . Upon annealing at 600 C A 1 dissolves and the following stable phases were observed: (a) Pr 2 Fe 14 B and A 3 for 0.0≤x≤0.75, and; (b) an unknown stable phase D 1 with coercivity around 2.1 kOe and Curie temperature of 230 C for x=1.0. D 1 is the predominant phase for annealing times less than 8 h while for 8 and 16 h annealing an additional phase with T c =17 C appears. The latter has been tentatively identified as Pr 2 Fe 17 . SEM and X-ray microanalysis studies were performed on Pr 80 Fe 15 C 5 samples in the as-cast state and after 16 h of annealing. The as-cast sample shows large Pr-rich grains immersed in a fine eutectic microstructure consisting of Pr and Fe. In annealed samples, both large square or polygonal grains and a needle-like phase are formed. The latter is believed to be D 1 . (orig.)

  15. Molecularly imprinted solid phase extraction using stable isotope labeled compounds as template and liquid chromatography-mass spectrometry for trace analysis of bisphenol A in water sample

    International Nuclear Information System (INIS)

    Kawaguchi, Migaku; Hayatsu, Yoshio; Nakata, Hisao; Ishii, Yumiko; Ito, Rie; Saito, Koichi; Nakazawa, Hiroyuki

    2005-01-01

    We have developed a molecularly imprinted polymer (MIP) using a stable isotope labeled compound as the template molecule and called it the ''isotope molecularly imprinted polymer'' (IMIP). In this study, bisphenol A (BPA) was used as the model compound. None imprinted polymer (NIP), MIP, dummy molecularly imprinted polymer (DMIP) and IMIP were prepared by the suspension polymerization method using without template, BPA, 4-tert-butylphenol (BP) and bisphenol A-d 16 (BPA-d 16 ), respectively. The polymers were subjected to molecularly imprinted solid phase extraction (MI-SPE), and the extracted samples were subjected to liquid chromatography-mass spectrometry (LC-MS). Although the leakage of BPA-d 16 from the IMIP was observed and that of BPA was not observed. The selectivity factors of MIP and IMIP for BPA were 4.45 and 4.43, respectively. Therefore, IMIP had the same molecular recognition ability as MIP. When MI-SPE with IMIP was used and followed by LC-MS in the analysis of river water sample, the detection limit of BPA was 1 ppt with high sensitivity. Moreover, the average recovery was higher than 99.8% (R.S.D.: 3.7%) by using bisphenol A- 13 C 12 (BPA- 13 C 12 ) as the surrogate standard. In addition, the IMIP were employed in MI-SPE of BPA in river water sample by LC-MS. The concentration of BPA in the river water sample was determined to be 32 pg ml -1 . We confirmed that it was possible to measure trace amounts of a target analyte by MI-SPE using IMIP

  16. Cu Nanoparticles Improved Thermal Property of Form-Stable Phase Change Materials Made with Carbon Nanofibers and LA-MA-SA Eutectic Mixture.

    Science.gov (United States)

    Song, Xiaofei; Cai, Yibing; Huang, Cong; Gu, Ying; Zhang, Junhao; Qiao, Hui; Wei, Qufu

    2018-04-01

    A novel form-stable phase change materials (FSPCMs) was fabricated by incorporating fatty acid eutectics with electrospun carbon nanofibers (CNFs) surface-attached with copper (Cu) nanoparticles. Three different Cu/CNFs mats were made through combining the technique and principle of electrospinning, pre-oxidation/carbonization and in-situ reduction, while lauric-myristic-stearic acid (LA-MA-SA) ternary eutectic mixture was prepared as the model PCM. The morphology and crystal structure of Cu/CNFs were characterized by Fourier transfer infrared (FT-IR) spectra, Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray energy dispersive spectroscopy (EDS), respectively. The results showed that Cu nanoparticles dispersed uniformly on the surface of CNFs mats without agglomeration, and Cu/CNFs mats could provide the mechanical support for FSPCMs and effectively prevent the flow/leakage of molten fatty acid. Morphological structures, as well as the properties of thermal energy storage and thermal energy storage/retrieval rates, of the resulting FSPCMs were investigated by SEM, Differential scanning calorimetry (DSC), and measurement of melting/freezing times, respectively. The results indicated that the fabricated FSPCMs exhibited desired structural morphology, and LA-MA-SA well dispersed in three-dimensional porous structure of Cu/CNFs mats. The melting and crystallization enthalpies of the fabricated FSPCMs were in the range of 117.1-140.7 kJ/kg and 117.2-142.4 kJ/kg, respectively. In comparison with melting/freezing times of LA-MA-SA ternary eutectic mixture, the melting/freezing times of fabricated FSPCMs were respectively decreased ~27.0-49.2% and ~44.1-63.0%. The fabricated FSPCMs possessed good thermal energy storage/retrieval property, and might have great potential for renewable energy storage applications.

  17. Preparation and properties of 1-tetradecanol/1,3:2,4-di-(3,4-dimethyl) benzylidene sorbitol gelatinous form-stable phase change materials

    International Nuclear Information System (INIS)

    Tian, Tuo; Song, Jian; Niu, Libo; Feng, Rongxiu

    2013-01-01

    Graphical abstract: The 1,3:2,4-di-(3,4-dimethyl) benzylidene sorbitol can self-assemble to form three-dimensional network and immobilized the 1-tetradecanol. As a result, the gel-to-sol transition temperature of the composite PCM increased and the 1-tetradecanol leakage decreased. Highlights: ► First used of 1,3:2,4-di-(3,4-dimethyl) benzylidene sorbitol in alcohol-based PCMs. ► A new method of doping with exfoliated graphite is presented. ► A possible mechanism for decreasing leakage has been proposed based on SEM results. ► The prepared composite PCMs showed a high-energy storage density. ► The addition of exfoliated graphite enhanced the thermal conductivity of the PCMs. - Abstract: A 1-tetradecanol (TD)/1,3:2,4-di-(3,4-dimethyl) benzylidene sorbitol (DMDBS) composite was prepared as a novel form-stable phase change material (PCM), and the properties of the composites such as the gel-to-sol transition temperature, the latent heat, the microstructure and the thermal storage performance were characterized. The composite was prepared by impregnating DMDBS into TD and the maximum feasible weight percentage of TD was determined to be 94.2 wt%. The gel-to-sol transition temperature of the composite PCM was 158.3–180.0 °C, which is well above the melting point of 1-tetradecanol. Differential scanning calorimeter (DSC) was used to determine the melting and freezing enthalpies of 1-tetradecanol in the composite PCM and the values are 218.5 and 215.3 J g −1 , respectively. Scanning electron microscopy (SEM) results showed that 1-tetradecanol dispersed in the three-dimensional network formed by DMDBS. The relationship between the amount of DMDBS additive and the leakage was also discussed. The thermal conductivity of the composite PCM was improved by doping with exfoliated graphite

  18. Moisture stable Ni-Zn MOF/g-C3N4 nanoflowers: A highly efficient adsorbent for solid-phase microextraction of PAHs.

    Science.gov (United States)

    Zhang, Ning; Huang, Chuanhui; Tong, Ping; Feng, Zunmei; Wu, Xiaoping; Zhang, Lan

    2018-06-29

    Volatile polycyclic aromatic hydrocarbons (PAHs) in water and soil are associated with status in the human body. Development of simple, efficient detection method is challenging due to the coating could be attacked by the abundance of water in the direct-immersion solid-phase microextraction. The stability of coating is essential to the analysis results. In this paper, a stable Ni-Zn MOF/g-C 3 N 4 (MG NFs) nanoflowers with cavity traps structure was firstly reported and acted as solid-phase microextraction (SPME) adsorbent for PAHs. Markedly enhanced moisture and acid stability of the MG NFs was obtained through the doping the hydrophobic graphitic carbon nitride (g-C 3 N 4 ) and metal ions into metal organic frameworks (MOFs). The aperture environment and ambient environment of MG NFs were changed by the doping of the Ni and the g-C 3 N 4, respectively. The moisture and acid stability of MG NFs were prominently increased under the dual protection. Compared to commonly used commercial coatings, the MG NFs own large surface area, unique nanoflowers structure and numerous open metal sites on the nanosheets, which demonstrated significant extraction superiority for PAHs. The MG NFs coated fiber was used for the SPME preconcentration of PAHs and couped with GC-MS for detecting PAHs. It presented low detection limits (0.1-3.0 ng L -1 ), wide linearity (0.3-5000.0 ng L -1 ) and good linearity (the correlation coefficient >0.9951). The inter-day and intra-day relative standard deviation (RSD) (n = 3) for three replicate extractions using one fiber was 3.8%-9.1%, and 3.5%-9.2%, respectively. The fiber-to-fiber reproducibility (n = 3) was 4.2-11.8%. The coupling method was successfully applied in the analysis of real water and soil samples with satisfactory recoveries of 82.9-109.2%, 84.2-106.4%, and the corresponding RSDs were 2.4-11.3%, 3.6-10.8%, respectively. The results indicated the effectiveness of NG NFs coated fiber in further practical application

  19. First-principles study on the structural, cohesive and electronic properties of rhombohedral Mo2B5 as compared with hexagonal MoB2

    International Nuclear Information System (INIS)

    Shein, I.R.; Shein, K.I.; Ivanovskii, A.L.

    2007-01-01

    The full-potential linearized augmented plane wave method using the generalized gradient approximation (FLAPW-GGA) has been applied to provide comparison and contrast for Mo borides with various structural types: rhombohedral Mo 2 B 5 versus hexagonal MoB 2 . The equilibrium lattice parameters, energies of formations, total and partial densities of states, electronic density distributions and the theoretical shapes of boron K-edge X-ray emission spectra are obtained and compared to available data

  20. Rhombohedral polytypes of the layered honeycomb delafossites with optical brilliance in the visible.

    Science.gov (United States)

    Roudebush, John H; Sahasrabudhe, Girija; Bergman, Susanna L; Cava, R J

    2015-04-06

    We report the synthesis of the Delafossite honeycomb compounds Cu3Ni2SbO6 and Cu3Co2SbO6 via a copper topotactic reaction from the layered α-NaFeO2-like precursors Na3Ni2SbO6 and Na3Co2SbO6. The low-temperature exchange reaction exclusively produces the rhombahedral 3R polytype subcell, whereas only the hexagonal 2H polytype subcell has been made by conventional synthesis. The thus-synthesized 3R variants are visually striking; they are bright lime-green (Ni variant) and terracotta-orange (Co variant), while both of the conventionally synthesized 2H variants have a burnt-red color. The new structures are characterized by powder X-ray diffraction and Rietveld analysis as well as magnetic susceptibility, X-ray photoelectron spectroscopy (XPS), and diffuse-reflectance optical spectroscopy. Using thermogravimetric analysis, we identify a second order 3R → 2H phase transition as well as a first-order structural transition associated with rearrangement of the honeycomb stacking layers. The optical absorbance spectra of the samples show discrete edges that correlate well to their visual colors. Exposing Cu3Ni2SbO6 to O2 and heat causes the sample to change color. XPS confirms the presence of Cu(2+) in these samples, which implies that the difference in color between the polytypes is due to oxygen intercalation resulting from their different synthetic routes.

  1. Stable particles

    International Nuclear Information System (INIS)

    Samios, N.P.

    1993-01-01

    I have been asked to review the subject of stable particles, essentially the particles that eventually comprised the meson and baryon octets. with a few more additions -- with an emphasis on the contributions made by experiments utilizing the bubble chamber technique. In this activity, much work had been done by the photographic emulsion technique and cloud chambers-exposed to cosmic rays as well as accelerator based beams. In fact, many if not most of the stable particles were found by these latter two techniques, however, the forte of the bubble chamber (coupled with the newer and more powerful accelerators) was to verify, and reinforce with large statistics, the existence of these states, to find some of the more difficult ones, mainly neutrals and further to elucidate their properties, i.e., spin, parity, lifetimes, decay parameters, etc

  2. The phase diagram and magnetic properties of Co and Ti co-doped (1−x)BiFeO_3–xLaFeO_3 solid solutions

    International Nuclear Information System (INIS)

    Wu, Jiangtao; Xu, Jun; Li, Nan; Jiang, Yaqi; Xie, Zhaoxiong

    2015-01-01

    Single phase Co and Ti co-doped Bi_1_−_xFeO_3−La_xFeO_3 (x = 0–1) solid solutions were prepared by the sol–gel method. Room temperature x-ray powder diffraction (XRD) patterns showed that the structures of as-prepared Bi_1_−_xLa_xFe_0_._9_0Co_0_._0_5Ti_0_._0_5O_3 solid solutions transformed from rhombohedral R3c to tetragonal P4mm and then to orthorhombic Pnma, with increasing La concentration from 0 to 1. In situ high-temperature XRD (HTXRD) analysis further revealed that rhombohedral structure R3c (x ≤ 0.16) and tetragonal structure P4mm (0.17 ≤ x ≤ 0.40) changed to orthorhombic Pnma along with increasing temperature, and the phase transition temperature decreased with the increase of La doping concentration. However, the orthorhombic structure Pnma (x ≥ 0.41) kept stable even when the temperature reached 850 °C. The phase diagram of as-prepared binary solid solutions of Bi_1_−_xLa_xFe_0_._9_0Co_0_._0_5Ti_0_._0_5O_3(x = 0–1) was drawn on the basis of XRD and HTXRD analysis. Magnetic measurement revealed that the magnetic properties are greatly enhanced with the increase of La content. - Highlights: • Single phase Co and Ti co-doped (1−x)BiFeO_3–xLaFeO_3 (x = 0–1) solid solutions were synthesized. • The phase transitions were investigated by tuning composition and temperature. • Phase diagram was constructed according to the results of XRD for the first time. • The magnetization of solid solution can be enhanced when increasing La content.

  3. High-pressure synthesis of rhombohedral α-AgGaO{sub 2} via direct solid state reaction

    Energy Technology Data Exchange (ETDEWEB)

    Akhtar, Meysam [Department of Physics and Astronomy, University of Louisville, 102 Natural Science Building, Louisville, KY 40292 (United States); Menon, Madhu [Center for Computational Sciences, University of Kentucky, 325 McVey Hall, Lexington, KY 40506 (United States); Sunkara, Mahendra [Conn Center for Renewable Energy Research, University of Louisville, Ernst Hall Room 102A, Louisville, KY 40292 (United States); Sumanasekera, Gamini [Department of Physics and Astronomy, University of Louisville, 102 Natural Science Building, Louisville, KY 40292 (United States); Conn Center for Renewable Energy Research, University of Louisville, Ernst Hall Room 102A, Louisville, KY 40292 (United States); Durygin, Andriy [Center for the Study of Matter at Extreme Conditions, Florida International University, VH 140, University Park, Miami, FL 33199 (United States); Jasinski, Jacek B., E-mail: jacek.jasinski@louisville.edu [Conn Center for Renewable Energy Research, University of Louisville, Ernst Hall Room 102A, Louisville, KY 40292 (United States)

    2015-08-25

    Highlights: • Direct synthesis of α-AgGaO{sub 2} via a solid state reaction of Ag{sub 2}O and Ga{sub 2}O{sub 3} powders. • Utilizing high pressure diamond anvil cell to facilitate solid state reaction. • Experimental and theoretical study of vibrational modes for α-AgGaO{sub 2}. • Extensive characterization of synthesized α-AgGaO{sub 2} samples. • GGA + U formalism-based DFT calculations of electronic structure and band gap in α-AgGaO{sub 2}. - Abstract: In this work, we demonstrate the application of high pressure conditions to enable the direct synthesis of α-AgGaO{sub 2} via a solid state reaction of Ag{sub 2}O and Ga{sub 2}O{sub 3}. Synthesis experiments were carried out at pressures and temperatures up to ∼10 GPa and ∼600 °C, respectively, using a resistively-heated diamond anvil cell. Thus synthesized α-AgGaO{sub 2} samples were characterized and their chemical composition and crystal structure were confirmed. In particular, electron diffraction confirmed the rhombohedral delafossite crystal structure of the synthesized AgGaO{sub 2} and its corresponding lattice parameters of a = 2.99 Å and c = 18.43 Å. The vibrational modes analysis was also conducted using a combination of ab initio density functional theory (DFT) and Raman spectroscopy. This analysis yielded good agreement between the calculated Raman-active modes and experimental Raman data. Finally, the application of the GGA + U formalism-based on DFT to calculate the electronic band structure of α-AgGaO{sub 2} provided a more realistic theoretical band gap value than those reported previously.

  4. Stable, Extreme Temperature, High Radiation, Compact. Low Power Clock Oscillator for Space, Geothermal, Down-Hole & other High Reliability Applications, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Efficient and stable clock signal generation requirements at extreme temperatures (-180C to +450C)and radiation (>250 Krad TID) are not met with the current...

  5. Stable isotopes

    International Nuclear Information System (INIS)

    Brazier, J.L.; Guinamant, J.L.

    1995-01-01

    According to the progress which has been realised in the technology of separating and measuring isotopes, the stable isotopes are used as preferable 'labelling elements' for big number of applications. The isotopic composition of natural products shows significant variations as a result of different reasons like the climate, the seasons, or their geographic origins. So, it was proved that the same product has a different isotopic composition of alimentary and agriculture products. It is also important in detecting the pharmacological and medical chemicals. This review article deals with the technology, like chromatography and spectrophotometry, adapted to this aim, and some important applications. 17 refs. 6 figs

  6. Stable Tetraquarks

    Energy Technology Data Exchange (ETDEWEB)

    Quigg, Chris [Fermilab

    2018-04-13

    For very heavy quarks, relations derived from heavy-quark symmetry imply novel narrow doubly heavy tetraquark states containing two heavy quarks and two light antiquarks. We predict that double-beauty states will be stable against strong decays, whereas the double-charm states and mixed beauty+charm states will dissociate into pairs of heavy-light mesons. Observing a new double-beauty state through its weak decays would establish the existence of tetraquarks and illuminate the role of heavy color-antitriplet diquarks as hadron constituents.

  7. Stable beams

    CERN Multimedia

    2015-01-01

    Stable beams: two simple words that carry so much meaning at CERN. When LHC page one switched from "squeeze" to "stable beams" at 10.40 a.m. on Wednesday, 3 June, it triggered scenes of jubilation in control rooms around the CERN sites, as the LHC experiments started to record physics data for the first time in 27 months. This is what CERN is here for, and it’s great to be back in business after such a long period of preparation for the next stage in the LHC adventure.   I’ve said it before, but I’ll say it again. This was a great achievement, and testimony to the hard and dedicated work of so many people in the global CERN community. I could start to list the teams that have contributed, but that would be a mistake. Instead, I’d simply like to say that an achievement as impressive as running the LHC – a machine of superlatives in every respect – takes the combined effort and enthusiasm of everyone ...

  8. Phase coexistence in ferroelectric solid solutions: Formation of monoclinic phase with enhanced piezoelectricity

    Directory of Open Access Journals (Sweden)

    Xiaoyan Lu

    2016-10-01

    Full Text Available Phase morphology and corresponding piezoelectricity in ferroelectric solid solutions were studied by using a phenomenological theory with the consideration of phase coexistence. Results have shown that phases with similar energy potentials can coexist, thus induce interfacial stresses which lead to the formation of adaptive monoclinic phases. A new tetragonal-like monoclinic to rhombohedral-like monoclinic phase transition was predicted in a shear stress state. Enhanced piezoelectricity can be achieved by manipulating the stress state close to a critical stress field. Phase coexistence is universal in ferroelectric solid solutions and may provide a way to optimize ultra-fine structures and proper stress states to achieve ultrahigh piezoelectricity.

  9. Thermodynamic behavior of very stable binary compounds with a wide homogeneity range: Their influence in the liquid phase in ternary and higher component systems in the solid state

    International Nuclear Information System (INIS)

    Hoch, M.

    1988-01-01

    The Hoch-Arpshofen model is combined with the Schottky-Wagner disorder model to describe first binary liquid systems, where a very stable solid protrudes into the liquid. We analyze the systems K-I 2 , Cs-I 2 , U-UO 3 , Ag-S and Al-Sb. The system Al-Sb can be described as Al-Sb and as Al-AlSb-Sb. Then we examine the Al-Co, Al-Ni, and Al-Fe systems to describe the stable compounds CoAl, NiAl, and FeAl, which all have a wide homogeneity range in the solid state. Here the Schottky-Wagner model is sufficient. Finally we describe a model which treats the influence of these stable binary compounds in ternary and larger systems such as Al-Cr-Ni and Al-Cr-Fe, again in the solid state. (orig./IHOE) [de

  10. Structural studies of the rhombohedral and orthorhombic monouranates: CaUO{sub 4}, α-SrUO{sub 4}, β-SrUO{sub 4} and BaUO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Gabriel [School of Chemistry, The University of Sydney, Sydney, NSW 2006 (Australia); Kennedy, Brendan J., E-mail: kennedyb@chem.usyd.edu.au [School of Chemistry, The University of Sydney, Sydney, NSW 2006 (Australia); Johannessen, Bernt; Kimpton, Justin A. [Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168 (Australia); Avdeev, Maxim; Griffith, Christopher S.; Thorogood, Gordon J.; Zhang, Zhaoming [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234 (Australia)

    2016-05-15

    The structures of some AUO{sub 4} (A=Ca, Sr, or Ba) oxides have been determined using a combination of neutron and synchrotron X-ray diffraction, supported by X-ray absorption spectroscopic measurements at the U L{sub 3}-edge. The smaller Ca cation favours a rhombohedral AUO{sub 4} structure with 8-coordinate UO{sub 8} moieties whilst an orthorhombic structure based on UO{sub 6} groups is found for BaUO{sub 4}. Both the rhombohedral and orthorhombic structures can be stabilised for SrUO{sub 4}. The structural studies suggest that the bonding requirements of the A site cation play a significant role in determining which structure is favoured. In the rhombohedral structure, Bond Valence Sums demonstrate the A site is invariably overbonded, which, in the case of rhombohedral α-SrUO{sub 4}, is compensated for by the formation of vacancies in the oxygen sub-lattice. The uranium cation, with its flexible oxidation state, is able to accommodate this by inducing vacancies along its equatorial coordination site as demonstrated by neutron powder diffraction. - Graphical abstract: Diffraction studies of AUO{sub 4} (A = Ca, Sr, or Ba) oxides reveal the importance of the bonding requirements of the A site cation in determining whether the structure is rhombohedral or orthorhombic. - Highlights: • Structures of AUO{sub 4} ( A = Ca Sr, Ba) refined against X-ray and Neutron diffraction. • The alkali cations size has a dramatic effect on the crystal structure. • Smaller cations favouring a rhombohedral structure. • Oxygen vacancies to stabilise the rhombohedral structure in SrUO{sub 4}.

  11. Structural phase transitions in BaMo6S8: Evidence for an incommensurate phase

    International Nuclear Information System (INIS)

    Jorgensen, J.D.; Hinks, D.G.; Hatch, D.M.; Putnam, R.M.

    1986-01-01

    The structure of BaMo 6 S 8 has been studied over the temperature range 19 K to 573 K by time-of-flight neutron powder diffraction. Below 175 K the data can be suitably refined in a triclinic, P1, cell with volume equal to the rhombohedral, R3, cell common to most Chevrel-phase structures. At temperatures immediately above 175 K, the rhombohedral, R3, Bragg peaks are broadened by satellite reflections which appear to be identical to those recently observed at low temperature in PbMo 6 S 8 and SnMo 6 S 8 . An abrupt change in the sign of the temperature dependence of the hexagonal c axis (∂c/∂T) signals the transition to an undistorted rhombohedral, R3, structure at temperatures above about 350 K. An extended Landau theory determines both continuous and discontinuous transitions from R3 induced by a single order parameter. Analysis of the order parameters inducing commensurate transitions imposes symmetry restrictions on the atomic displacements in the lower symmetry phases. The assumption of an R3 commensurate phase is not consistent with the bond lengths obtained for the distortions to the P1 (or P1) phase for any of the possible cells preserving order parameters. Thus the phase immediately above 175 K cannot be a commensurate R3 structure. This is consistent with experimental evidence. 25 refs., 11 figs., 8 tabs

  12. Synthesis, crystal structure, and transport properties of Fe substituted rhombohedral skutterudite derivatives Co4−xFexGe6Se6

    KAUST Repository

    Wei, Kaya

    2014-11-01

    We report on the synthesis and low temperature transport properties of rhombohedral derivatives of the cubic skutterudite CoSb3, namely Co4-xFexGe6Se6 with x = 0, 1, 1.5. Rietveld refinement and elemental analyses were used to identify the structure and stoichiometry of the compositions. The thermal conductivity was investigated by employing the Debye model with different phonon-scattering parameters. This investigation demonstrates that Fe substitution is feasible in these skutterudite derivatives and can significantly affect the transport properties as compared with Co4Ge6Se6. © 2014 Elsevier B.V. All rights reserved.

  13. Synthesis, crystal structure, and transport properties of Fe substituted rhombohedral skutterudite derivatives Co4−xFexGe6Se6

    KAUST Repository

    Wei, Kaya; Dong, Yongkwan; Puneet, Pooja; Tritt, Terry M.; Nolas, George S.

    2014-01-01

    We report on the synthesis and low temperature transport properties of rhombohedral derivatives of the cubic skutterudite CoSb3, namely Co4-xFexGe6Se6 with x = 0, 1, 1.5. Rietveld refinement and elemental analyses were used to identify the structure and stoichiometry of the compositions. The thermal conductivity was investigated by employing the Debye model with different phonon-scattering parameters. This investigation demonstrates that Fe substitution is feasible in these skutterudite derivatives and can significantly affect the transport properties as compared with Co4Ge6Se6. © 2014 Elsevier B.V. All rights reserved.

  14. Phase transformations im smart materials

    International Nuclear Information System (INIS)

    Newnham, R.E.

    1998-01-01

    One of the qualities that distinguishes living systems from inanimate matter is the ability to adapt to changes in the environment. Smart materials have the ability to perform both sensing and actuating functions and are, therefore, capable of imitating this rudimentary aspect of life. Four of the most widely used smart materials are piezoelectric Pb(Zr, Ti)O 3 , electrostrictive Pb(Mg, Nb)O 3 , magnetostrictive (Tb, Dy)Fe 2 and the shape-memory alloy NiTi. All four are ferroic with active domain walls and two phase transformations, which help to tune the properties of these actuator materials. Pb(Zr, Ti)O 3 is a ferroelectric ceramic which is cubic at high temperature and becomes ferroelectric on cooling through the Curie temperature. At room temperature, it is poised on a rhombohedral-tetragonal phase boundary which enhances the piezoelectric coefficients. Terfenol, (Tb, Dy)Fe 2 , is also cubic at high temperature and then becomes magnetic on cooling through its Curie temperature. At room temperature, it too is poised on a rhombohedral-tetragonal transition which enhances its magnetostriction coefficients. Pb(Mg, Nb)O 3 and nitinol (NiTi) are also cubic at high temperatures and on annealing transform to a partially ordered state. On further cooling, Pb(Mg, Nb)O 3 passes through a diffuse phase transformation at room temperature where it exhibits very large dielectric and electrostrictive coefficients. Just below room temperature, it transforms to a ferroelectric rhombohedral phase. The partially ordered shape-memory alloy NiTi undergoes an austenitic (cubic) to martensitic (mono-clinic) phase change just above room temperature. It is easily deformed in the martensitic state but recovers its original shape when reheated to austenite

  15. Ca2Cr0.5Ga1.5O5—An extremely redox-stable brownmillerite phase

    International Nuclear Information System (INIS)

    Luo, Kun; Amano Patino, Midori; Hayward, Michael A.

    2015-01-01

    Investigation of the Ca 2 Cr x Ga 2−x O 5 compositional series reveals a maximum chromium solubility of 25%. The most chromium rich composition, Ca 2 Cr 0.5 Ga 1.5 O 5 , adopts a brownmillerite-type anion deficient perovskite structure described in space group Pnma (a=5.368 Å, b=14.547 Å, c=5.593 Å). Neutron powder diffraction data reveals rigorous B-site cation order, with all of the tetrahedral coordination sites occupied exclusively by gallium and the octahedral coordination sites occupied by gallium or chromium. Annealing studies reveals Ca 2 Cr 0.5 Ga 1.5 O 5 is stable in both oxidizing (100% O 2 ) and reducing (5% H 2 in N 2 ) conditions up to 800 °C, suggesting it could find application as a stable host lattice for fuel cell electrodes or electrolytes with suitable doping to enhance catalytic behaviour and/or anionic conductivity. - Graphical abstract: Ca 2 Cr 0.5 Ga 1.5 O 5 , adopts a brownmillerite-type anion deficient perovskite structure yet it is stable in both oxidizing (100% O 2 ) and reducing (5% H 2 in N 2 ) conditions up to 800 °C. - Highlights: • Anion deficient oxide stable to both oxidation and reduction up to 800 °C. • Cation-ordered brownmillerite structure determined by powder neutron diffraction. • Low solubility of Cr 3+ in framework due to spherical d 3 electron configuration

  16. Fragile-to-fragile liquid transition at Tg and stable-glass phase nucleation rate maximum at the Kauzmann temperature TK

    International Nuclear Information System (INIS)

    Tournier, Robert F.

    2014-01-01

    An undercooled liquid is unstable. The driving force of the glass transition at T g is a change of the undercooled-liquid Gibbs free energy. The classical Gibbs free energy change for a crystal formation is completed including an enthalpy saving. The crystal growth critical nucleus is used as a probe to observe the Laplace pressure change Δp accompanying the enthalpy change −V m ×Δp at T g where V m is the molar volume. A stable glass–liquid transition model predicts the specific heat jump of fragile liquids at T≤T g , the Kauzmann temperature T K where the liquid entropy excess with regard to crystal goes to zero, the equilibrium enthalpy between T K and T g , the maximum nucleation rate at T K of superclusters containing magic atom numbers, and the equilibrium latent heats at T g and T K . Strong-to-fragile and strong-to-strong liquid transitions at T g are also described and all their thermodynamic parameters are determined from their specific heat jumps. The existence of fragile liquids quenched in the amorphous state, which do not undergo liquid–liquid transition during heating preceding their crystallization, is predicted. Long ageing times leading to the formation at T K of a stable glass composed of superclusters containing up to 147 atom, touching and interpenetrating, are evaluated from nucleation rates. A fragile-to-fragile liquid transition occurs at T g without stable-glass formation while a strong glass is stable after transition

  17. Development of a Lower-SWaP, RAD-Tolerant, Thermally Stable High Speed Fiber Optics Network for Harsh Environment Applications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed Phase I objectives and work plan, carried through to completion, will result in the development of a RAD-tolerant, high-speed, multi-channel fiber...

  18. Investigation the effect of lattice angle on the band gap width in 3D phononic crystals with rhombohedral(I) lattice

    Science.gov (United States)

    Salehi, H.; Aryadoust, M.; Shoushtari, M. Zargar

    2014-07-01

    In this paper, the propagation of acoustic waves in the phononic crystal of 3D with rhombohedral(I) lattice is studied theoretically. The crystal composite constituted of nickel spheres embedded in epoxy. The calculations of the band structure and density of states are performed with the plane wave expansion method in the irreducible part of Brillouin zone. In the present work, we have investigated the effect of lattice angle on the band structure and width of the band gap rhombohedral(I) lattice in the irreducible part of the first Brillouin zone and its planes separately. The results show that more than one complete band gape are formed in the four planes of the irreducible part. The most complete band gaps are formed in the (111) plane and the widest complete band gap in (443) with an angle greater than 80. So, if the sound passes through the (111) and (443) planes for the lattice angle close to 90, the crystal phononic displays the excellent insulation behavior. Moreover, in the other planes, the lattice angle does not affect on the width and the number of band gaps. Also, for the filling fraction 5 %, the widest complete band gap is formed. These results are consistent with the effect of symmetry on the band gap width, because the (111) plane has the most symmetry.

  19. Confinement and surface effects on the physical properties of rhombohedral-shape hematite (α-Fe{sub 2}O{sub 3}) nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Luna, Carlos, E-mail: carlos.lunacd@uanl.edu.mx [Universidad Autónoma de Nuevo León (UANL), Av. Universidad S/N, San Nicolás de los Garza, Nuevo León 66455 (Mexico); Cuan-Guerra, Aída D. [Universidad Autónoma de Nuevo León (UANL), Av. Universidad S/N, San Nicolás de los Garza, Nuevo León 66455 (Mexico); Barriga-Castro, Enrique D. [Centro de Investigación en Química Aplicada (CIQA), Blvd. Enrique Reyna Hermosillo No. 140, Saltillo, 25294 Coahuila (Mexico); Núñez, Nuria O. [Instituto de Ciencia de Materiales de Sevilla (ICMS), CSIC-US, Avda. Americo Vespucio n° 49, Isla de la Cartuja, 41092 Sevilla (Spain); Mendoza-Reséndez, Raquel [Universidad Autónoma de Nuevo León (UANL), Av. Universidad S/N, San Nicolás de los Garza, Nuevo León 66455 (Mexico)

    2016-08-15

    Highlights: • Uniform rhombohedral hematite nanocrystals (RHNCs) have been obtained. • A detailed formation mechanism of these HNCS has been proposed. • Phonon confinement effects were revealed in the RHNCS vibrational bands. • Quantum confinement effects on the optical and electronic properties were found. - Abstract: Morphological, microstructural and vibrational properties of hematite (α-Fe{sub 2}O{sub 3}) nanocrystals with a rhombohedral shape and rounded edges, obtained by forced hydrolysis of iron(III) solutions under a fast nucleation, have been investigated in detail as a function of aging time. These studies allowed us to propose a detailed formation mechanism and revealed that these nanocrystals are composed of four {104} side facets, two {110} faces at the edges of the long diagonal of the nanocrystals and two {−441} facets as the top and bottom faces. Also, the presence of nanoscopic pores and fissures was evidenced. The vibrational bands of such nanocrystals were shifted to lower frequencies in comparison with bulk hematite ones as the nanocrystal size was reduced due to phonon confinement effects. Also, the indirect and direct transition band gaps displayed interesting dependences on the aging time arising from quantum confinement and surface effects.

  20. First-principles calculations on the four phases of BaTiO3.

    Science.gov (United States)

    Evarestov, Robert A; Bandura, Andrei V

    2012-04-30

    The calculations based on linear combination of atomic orbitals basis functions as implemented in CRYSTAL09 computer code have been performed for cubic, tetragonal, orthorhombic, and rhombohedral modifications of BaTiO(3) crystal. Structural and electronic properties as well as phonon frequencies were obtained using local density approximation, generalized gradient approximation, and hybrid exchange-correlation density functional theory (DFT) functionals for four stable phases of BaTiO(3). A comparison was made between the results of different DFT techniques. It is concluded that the hybrid PBE0 [J. P. Perdew, K. Burke, M. Ernzerhof, J. Chem. Phys. 1996, 105, 9982.] functional is able to predict correctly the structural stability and phonon properties both for cubic and ferroelectric phases of BaTiO(3). The comparative phonon symmetry analysis in BaTiO(3) four phases has been made basing on the site symmetry and irreducible representation indexes for the first time. Copyright © 2012 Wiley Periodicals, Inc.

  1. The effect of relativity on stability of Copernicium phases, their electronic structure and mechanical properties

    Science.gov (United States)

    Čenčariková, Hana; Legut, Dominik

    2018-05-01

    The phase stability of the various crystalline structures of the super-heavy element Copernicium was determined based on the first-principles calculations with different levels of the relativistic effects. We utilized the Darwin term, mass-velocity, and spin-orbit interaction with the single electron framework of the density functional theory while treating the exchange and correlation effects using local density approximations. It is found that the spin-orbit coupling is the key component to stabilize the body-centered cubic (bcc) structure over the hexagonal closed packed (hcp) structure, which is in accord with Sol. Stat. Comm. 152 (2012) 530, but in contrast to Atta-Fynn and Ray (2015) [11], Gaston et al. (2007) [10], Papaconstantopoulos (2015) [9]. It seems that the main role here is the correct description of the semi-core relativistic 6p1/2 orbitals. The all other investigated structures, i.e. face-centered cubic (fcc) , simple cubic (sc) as well as rhombohedral (rh) structures are higher in energy. The criteria of mechanical stability were investigated based on the calculated elastic constants, identifying the phase instability of fcc and rh structures, but surprisingly confirm the stability of the energetically higher sc structure. In addition, the pressure-induced structural transition between two stable sc and bcc phases has been detected. The ground-state bcc structure exhibits the highest elastic anisotropy from single elements of the Periodic table. At last, we support the experimental findings that Copernicium is a metal.

  2. A Novel In Situ Method for Producing a Dispersion of a Ceramic Phase into Copper That Remains Stable at 0.9 T M

    Science.gov (United States)

    Castellan, Enzo; Ischia, Gloria; Molinari, Alberto; Raj, Rishi

    2013-10-01

    We apply an in situ approach, whereby a polymer is incorporated into copper and evolves within the metal into the ceramic phase, to create a dispersion of hard particles in a metal. All constituents for the ceramic phase are contained within the organic polymer. The temperature for this polymer to ceramic conversion lies in the 1073 K to 1273 K (800 °C to 1000 °C) range. The process produces a nanoscale dispersion of the ceramic, which leads to high microhardness that remains unaltered at temperatures up to 1223 K (950 °C) (0.9 T M). Apparently, the introduction of the ceramic phase leads to the retention of copper crystallite size of a few hundred nm, despite exposure to heat treatments at these very high temperatures. We call these materials polymer-derived metal-matrix composites.

  3. Stable and metastable phases in reciprocal systems PbSe + Ag2I2 Ag2Se + PbI2 and PbSe + CdI2 = CdSe + PbI2

    International Nuclear Information System (INIS)

    Odin, I.N.; Grin'ko, V.V.; Kozlovskij, V.F.; Safronov, E.V.

    2005-01-01

    Mutual system PbSe + Ag 2 I 2 = Ag 2 Se + PbI 2 is investigated. It is shown that diagonal Ag 2 Se-PbI 2 is stable. Liquidus surface and isothermal section at 633 K of phase diagram of PbSe-Ag 2 Se-PbI 2 system are built. Transformations directing to crystallization metastable ternary compound forming in PbSe-PbI 2 system and metastable polytype modifications of lead iodide in PbSe-Ag 2 Se-PbI 2 system at 620-685 K are studied. By hardening from molten state (1150-1220 K) new interstitial metastable phases crystallizing in CdCl 2 structural type are obtained in PbSe-Ag 2 Se-PbI 2 and PbSe + CdI 2 = CdSe + PbI 2 systems [ru

  4. Direct formation of new, phase-stable, and photoactive anatase-type Ti1-2XNbXScXO2 solid solution nanoparticles by hydrothermal method

    International Nuclear Information System (INIS)

    Hirano, Masanori; Ito, Takaharu

    2008-01-01

    A new anatase phase of photoactive Ti 1-2X Nb X Sc X O 2 (X = 0-0.2) solid solutions was directly formed as nanoparticles from precursor solutions of TiOSO 4 , NbCl 5 , and Sc(NO 3 ) 3 under mild hydrothermal conditions at 180 deg. C for 5 h using the hydrolysis of urea. With the increase of the content of niobium and scandium from X = 0 to 0.2, the lattice parameters a 0 and c 0 , the crystallite size, and the optical band gap of anatase gradually increased. Their photocatalytic activity and adsorptivity were evaluated separately by the measurement of the concentration of methylene blue (MB) remained in the solution in the dark or under UV-light irradiation. The anatase-type Ti 1-2X Nb X Sc X O 2 (X = 0.05) showed approximately two times and three times as high photocatalytic activity as those of the hydrothermal anatase-type pure TiO 2 and commercially available reference pure TiO 2 (ST-01), respectively. The anatase phase of Ti 1-2X Nb X Sc X O 2 (X = 0-0.2) existed stably up to 900 deg. C during heat treatment in air. New rutile-type Ti 1-2X Nb X Sc X O 2 solid solutions are formed through the phase transformation. The starting temperature of anatase-to-rutile phase transformation for Ti 1-2X Nb X Sc X O 2 (X = 0-0.2) solid solutions was delayed but its completing temperature was accelerated

  5. Anomaly of the temperature dependence and nature of the optical absorption band in the 8 μm region in β-rhombohedral boron

    International Nuclear Information System (INIS)

    Yarovaya, R.G.; Tsomaya, K.P.; Gabuniya, D.L.; Nguen Van Doaj.

    1978-01-01

    Temperature dependence of reflection spectra of massive specimens of β-rhombohedral boron in the 7-10 μ region is studied. The specimen were heated from 20 to 450 C deg C in the air. Reflection spectra were measured in reference to standards of non-transparent layers of gold on the glass substrate with the reflection coefficient equal to 98%. Temperature increase was found to result in weakening reflection maximum in the spectral region under investigation and its abnormally fast shifting within the temperature range of 170-350 deg C. In measuring reflection and transmission spectra of B 2 O 3 layers deposited on the boron and rock-salt surfaces it is shown that the reflection peak under study does not involve the oxidation of the boron surface. This peak is supposed to be connected with the existance of inpure oxygen in the bulk

  6. Thermo-kinetic prediction of metastable and stable phase precipitation in Al–Zn–Mg series aluminium alloys during non-isothermal DSC analysis

    International Nuclear Information System (INIS)

    Lang, Peter; Wojcik, Tomasz; Povoden-Karadeniz, Erwin; Falahati, Ahmad; Kozeschnik, Ernst

    2014-01-01

    Highlights: • Comparison of laboratory Al–Zn–Mg alloy to industrial Al 7xxx series. • Heat flow evolution during non-isothermal DSC analysis is calculated. • TEM investigations of laboratory Al–Zn–Mg alloy at three pronounced temperatures. • Simulation and modelling of precipitation sequence. • Calculation and prediction of heat flow curves of Al 7xxx series. - Abstract: The technological properties of heat treatable Al–Zn–Mg alloys originate in the morphology and distribution of metastable particles. Starting from the solution-annealed condition, this paper describes the precipitate evolution during non-isothermal temperature changes, namely continuous heating differential scanning calorimetry (DSC) analysis. The distribution and the morphology of the metastable and stable precipitates and the heat flow accompanying the precipitation process is investigated experimentally and calculated by numerical thermo-kinetic simulations. The computer simulation results of the sizes and distributions are confirmed by transmission electron microscopy (TEM). The theoretical background and the results of the investigations are discussed

  7. Thermo-kinetic prediction of metastable and stable phase precipitation in Al–Zn–Mg series aluminium alloys during non-isothermal DSC analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lang, Peter, E-mail: pl404@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road 27, Cambridge CB3 0FS (United Kingdom); Wojcik, Tomasz [Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstraße 9-11, Vienna 1040 (Austria); Povoden-Karadeniz, Erwin [Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstraße 9-11, Vienna 1040 (Austria); Christian Doppler Laboratory “Early Stages of Precipitation”, Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstraße 9-11, Vienna 1040 (Austria); Falahati, Ahmad [Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstraße 9-11, Vienna 1040 (Austria); Kozeschnik, Ernst [Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstraße 9-11, Vienna 1040 (Austria); Christian Doppler Laboratory “Early Stages of Precipitation”, Institute of Materials Science and Technology, Vienna University of Technology, Favoritenstraße 9-11, Vienna 1040 (Austria)

    2014-10-01

    Highlights: • Comparison of laboratory Al–Zn–Mg alloy to industrial Al 7xxx series. • Heat flow evolution during non-isothermal DSC analysis is calculated. • TEM investigations of laboratory Al–Zn–Mg alloy at three pronounced temperatures. • Simulation and modelling of precipitation sequence. • Calculation and prediction of heat flow curves of Al 7xxx series. - Abstract: The technological properties of heat treatable Al–Zn–Mg alloys originate in the morphology and distribution of metastable particles. Starting from the solution-annealed condition, this paper describes the precipitate evolution during non-isothermal temperature changes, namely continuous heating differential scanning calorimetry (DSC) analysis. The distribution and the morphology of the metastable and stable precipitates and the heat flow accompanying the precipitation process is investigated experimentally and calculated by numerical thermo-kinetic simulations. The computer simulation results of the sizes and distributions are confirmed by transmission electron microscopy (TEM). The theoretical background and the results of the investigations are discussed.

  8. Low-lying dipole response in the stable {sup 40,48}Ca nuclei within the second random-phase approximation

    Energy Technology Data Exchange (ETDEWEB)

    Gambacurta, D.; Grasso, M.; Catara, F. [GANIL,CEA/DSM-CNRS/IN2P3, Caen (France); Institut de Physique Nucleaire, Universite Paris-Sud, IN2P3-CNRS, F-91406 Orsay Cedex (France); Dipartimento di Fisica e Astronomia dell' Universita di and INFN Catania (Italy)

    2012-10-20

    The low-lying dipole strength distributions of {sup 40}CaCa and {sup 48}Ca, in the energy region between 5 and 10 MeV, are studied within the second random phase approximation (RPA) with Skyrme interaction. Standard RPA models do not usually predict any presence of strength in this energy region, while experimentally a significant amount of strength is found. The inclusion of the 2 particle -2 hole configurations allows to obtain a description in a rather good agreement with the experimental data. The properties of the most collective state are analyzed in terms of its 1 particle -1 hole nature and its transition densities.

  9. Towards stable acceleration in LINACS

    CERN Document Server

    Dubrovskiy, A D

    2014-01-01

    Ultra-stable and -reproducible high-energy particle beams with short bunches are needed in novel linear accelerators and, in particular, in the Compact Linear Collider CLIC. A passive beam phase stabilization system based on a bunch compression with a negative transfer matrix element R56 and acceleration at a positive off-crest phase is proposed. The motivation and expected advantages of the proposed scheme are outlined.

  10. Stable and self-adaptive performance of mechanically pumped CO2 two-phase loops for AMS-02 tracker thermal control in vacuum

    International Nuclear Information System (INIS)

    Zhang, Z.; Sun, X.-H.; Tong, G.-N.; Huang, Z.-C.; He, Z.-H.; Pauw, A.; Es, J. van; Battiston, R.; Borsini, S.; Laudi, E.; Verlaat, B.; Gargiulo, C.

    2011-01-01

    A mechanically pumped CO 2 two-phase loop cooling system was developed for the temperature control of the silicon tracker of AMS-02, a cosmic particle detector to work in the International Space Station. The cooling system (called TTCS, or Tracker Thermal Control System), consists of two evaporators in parallel to collect heat from the tracker's front-end electronics, two radiators in parallel to emit the heat into space, and a centrifugal pump that circulates the CO 2 fluid that carries the heat to the radiators, and an accumulator that controls the pressure, and thus the temperature of the evaporators. Thermal vacuum tests were performed to check and qualify the system operation in simulated space thermal environment. In this paper, we reported the test results which show that the TTCS exhibited excellent temperature control ability, including temperature homogeneity and stability, and self-adaptive ability to the various external heat flux to the radiators. Highlights: → The active-pumped CO 2 two-phase cooling loop passed the thermal vacuum test. → It provides high temperature homogeneity and stability thermal boundaries. → Its working temperature is controllable in vacuum environment. → It possesses self-adaptive ability to imbalanced external heat fluxes.

  11. 1D and 2D NMR Spectroscopy of Bonding Interactions within Stable and Phase-Separating Organic Electrolyte-Cellulose Solutions.

    Science.gov (United States)

    Clough, Matthew T; Farès, Christophe; Rinaldi, Roberto

    2017-09-11

    Organic electrolyte solutions (i.e. mixtures containing an ionic liquid and a polar, molecular co-solvent) are highly versatile solvents for cellulose. However, the underlying solvent-solvent and solvent-solute interactions are not yet fully understood. Herein, mixtures of the ionic liquid 1-ethyl-3-methylimidazolium acetate, the co-solvent 1,3-dimethyl-2-imidazolidinone, and cellulose are investigated using 1D and 2D NMR spectroscopy. The use of a triply- 13 C-labelled ionic liquid enhances the signal-to-noise ratio for 13 C NMR spectroscopy, enabling changes in bonding interactions to be accurately pinpointed. Current observations reveal an additional degree of complexity regarding the distinct roles of cation, anion, and co-solvent toward maintaining cellulose solubility and phase stability. Unexpectedly, the interactions between the dialkylimidazolium ring C 2 -H substituent and cellulose become more pronounced at high temperatures, counteracted by a net weakening of acetate-cellulose interactions. Moreover, for mixtures that exhibit critical solution behavior, phase separation is accompanied by the apparent recombination of cation-anion pairs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Possibility of stable quark stars

    International Nuclear Information System (INIS)

    Bowers, R.L.; Gleeson, A.M.; Pedigo, R.D.

    1976-08-01

    A recent zero temperature equation of state which contains quark-partons separated from conventional baryons by a phase transition is used to investigate the stability of quark stars. The sensitivity to the input physics is also considered. The conclusions, which are found to be relatively model independent, indicate that a separately identifiable class of stable objects called quark stars does not exist

  13. The phase transition and elastic and optical properties of polymorphs of CuI

    International Nuclear Information System (INIS)

    Zhu Jiajie; Pandey, Ravindra; Gu Mu

    2012-01-01

    The high-pressure polymorphs of CuI have attracted much attention due to the somewhat contradictory identification of their structures by means of x-ray diffraction measurements and theoretical calculations. In this paper, we report the results of a theoretical investigation of polymorphs of CuI including zinc-blende, rhombohedral, tetragonal, rocksalt and orthorhombic phases. We find that CuI follows the high-pressure transition path from the zinc-blende phase to the orthorhombic phase via the tetragonal phase, and the rhombohedral phase shows mechanical instability under high pressure. The bulk moduli are almost isotropic but the shear moduli show large anisotropy in these polymorphs. A relatively strong hybridization of I p and Cu d states appears to determine the electronic properties of the CuI polymorphs. The zinc-blende and tetragonal CuI are direct gap semiconductors and their optical properties are similar, whereas the orthorhombic CuI is metallic.

  14. Stable Isotope Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Tissue samples (skin, bone, blood, muscle) are analyzed for stable carbon, stable nitrogen, and stable sulfur analysis. Many samples are used in their entirety for...

  15. Influence of boron vacancies on phase stability, bonding and structure of MB2 (M  =  Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W) with AlB2 type structure

    International Nuclear Information System (INIS)

    Dahlqvist, Martin; Rosen, Johanna; Jansson, Ulf

    2015-01-01

    Transition metal diborides in hexagonal AlB 2 type structure typically form stable MB 2 phases for group IV elements (M  =  Ti, Zr, Hf). For group V (M  =  V, Nb, Ta) and group VI (M  =  Cr, Mo, W) the stability is reduced and an alternative hexagonal rhombohedral MB 2 structure becomes more stable. In this work we investigate the effect of vacancies on the B-site in hexagonal MB 2 and its influence on the phase stability and the structure for TiB 2 , ZrB 2 , HfB 2 , VB 2 , NbB 2 , TaB 2 , CrB 2 , MoB 2 , and WB 2 using first-principles calculations. Selected phases are also analyzed with respect to electronic and bonding properties. We identify trends showing that MB 2 with M from group V and IV are stabilized when introducing B-vacancies, consistent with a decrease in the number of states at the Fermi level and by strengthening of the B–M interaction. The stabilization upon vacancy formation also increases when going from M in period 4 to period 6. For TiB 2 , ZrB 2 , and HfB 2 , introduction of B-vacancies have a destabilizing effect due to occupation of B–B antibonding orbitals close to the Fermi level and an increase in states at the Fermi level. (paper)

  16. Synchrotron X-ray topography studies of twinning and the phase transition at 145deg C in LaGaO sub 3 single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yao, G.D.; Dudley, M. (Dept. of Materials Science and Engineering, State Univ. of New York, Stony Brook, NY (USA)); Wang, Y.; Liu, X.; Liebermann, R.C. (Dept. of Earth and Space Sciences, State Univ. of New York, Stony Brook, NY (USA))

    1991-02-01

    An investigation of (i) twinning in the room temperature orthorhombic phase, (ii) the orthorhombic-to-rhombohedral phase transformation occurring at 145deg C and (iii) twinning in the high temperature rhombohedral phase, all occurring in lanthanum gallate single crystals has been undertaken using white-beam synchrotron X-ray topography (WBSXRT). At room temperature, WBSXRT results obtained from the (110){sub orth} surface, orthorhombic crystals indicated the presence of ''mirror'' twinning on (1anti 12){sub orth}, (1anti 1anti 2){sub orth}, (anti 110){sub orth} and (112){sub orth} planes. Differential thermal analysis confirmed the existence of a first-order phase transformation at 145deg C. WBSXRT observations of the associated structural change (orthorhombic to rhombohedral) correlated well with the results of temperature-dependent powder diffraction results which are presented in the companion paper. WBSXRT also revealed the detailed spatial characteristics of the transition on the microstructural scale, as well as the nature of twinning in the rhombohedral phase, with the latter occurring on (110){sub rhomb} planes. In all three cases, results were consistent with the transmission electron microscopy results presented in the companion paper. The influence of both the twinning and the phase transition on the potential use of LaGaO{sub 3} single crystals as substrates for high Tc superconductor epilayers is discussed. (orig.).

  17. Mechanisms Responsible for the Large Piezoelectricity at the Tetragonal-Orthorhombic Phase Boundary of (1-x)BaZr0.2Ti0.8O3-xBa0.7Ca0.3TiO3 System.

    Science.gov (United States)

    Yang, Tao; Ke, Xiaoqin; Wang, Yunzhi

    2016-09-16

    Recently it was found that in the lead-free (1-x)BaZr0.2Ti0.8O3-xBa0.7Ca0.3TiO3 (BZT-xBCT) system, the highest piezoelectric d33 coefficient appears at the tetragonal (T) - orthorhombic (O) phase boundary rather than the O - rhombohedral (R) phase boundary, but the physical origin of it is still unclear. In this work we construct the phase diagram of the BZT-xBCT system using a generic sixth-order Landau free energy polynomial and calculate the energy barrier (EB) for direct domain switching between two variants of the stable low-symmetry ferroelectric phase. We find that the EB at the T-O phase boundary is lower than that at the O-R phase boundary and EB may serve as a rigorous quantitative measure of the degree of polarization anisotropy through Landau potential. The calculations may shed some light on the physical origin of the highest piezoelectric coefficients as well as the softest elastic compliance at the T-O phase boundary observed in experiments.

  18. Universal phase diagram for high-piezoelectric perovskite systems

    NARCIS (Netherlands)

    Cox, D.E.; Noheda, B.; Shirane, G.; Uesu, Y.; Fujishiro, K.; Yamada, Y.

    2001-01-01

    Strong piezoelectricity in perovskite-type PbZn1-xTixO3 (PZT) and Pb(Zn1/3Nb2/3)O3–PbTiO3 (PZN–PT) systems is generally associated with the existence of a morphotropic phase boundary (MPB) separating regions with rhombohedral and tetragonal symmetry. An x-ray study of PZN–9% PT has revealed the

  19. High conductive and long-term phase stable anode materials for SOFCs: A2FeMoO6 (A = Ca, Sr, Ba)

    Science.gov (United States)

    Huan, Yu; Li, Yining; Yin, Baoyi; Ding, Dong; Wei, Tao

    2017-08-01

    In this work, the mixed oxide-ion/electron conductor (MIEC) double-perovskite compounds A2FeMoO6 (AFMO, A = Ca, Sr, Ba) are investigated as anode materials for O2--ion conducting solid-oxide fuel cells (SOFCs). Several advantages are outlined here; 1) under H2 atmosphere, the conductivities of Ba2FeMoO6 (BFMO), Sr2FeMoO6 (SFMO) and Ca2FeMoO6 (CFMO) reach as high as 243, 302 and 561 S cm-1, respectively, which can be comparable with the commercial NiO-electrolyte anode; 2) excellent structure and phase stability at high temperature and in H2 atmosphere; 3) matched thermodynamic compatibility (such as TECs) with electrolyte materials; 4) fast oxidization for fuel with O2- ions accepted by oxygen vacancies from the electrolyte. Moreover, with H2 as fuel gas, the cell power output, cell's long-term stabilities and the structural parameter are also been examined to evaluate the AFMO anode.

  20. First-principles study of lattice dynamics, structural phase transition, and thermodynamic properties of barium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Huai-Yong; Zhao, Ying-Qin; Lu, Qing [Sichuan Univ., Chengdu (China). Inst. of Atomic and Molecular Physics; Zeng, Zhao-Yi [Chongqing Normal Univ. (China). College of Physics and Electronic Engineering; Chinese Academy of Engineering Physics, Mianyang (China). National Key Laboratory for Shock Wave and Detonation Physics Research; Cheng, Yan [Sichuan Univ., Chengdu (China). Inst. of Atomic and Molecular Physics; Sichuan Univ., Chengdu (China). Key Laboratory of High Energy Density Physics and Technology of Ministry of Education

    2016-11-01

    Lattice dynamics, structural phase transition, and the thermodynamic properties of barium titanate (BaTiO{sub 3}) are investigated by using first-principles calculations within the density functional theory (DFT). It is found that the GGA-WC exchange-correlation functional can produce better results. The imaginary frequencies that indicate structural instability are observed for the cubic, tetragonal, and orthorhombic phases of BaTiO{sub 3} and no imaginary frequencies emerge in the rhombohedral phase. By examining the partial phonon density of states (PDOSs), we find that the main contribution to the imaginary frequencies is the distortions of the perovskite cage (Ti-O). On the basis of the site-symmetry consideration and group theory, we give the comparative phonon symmetry analysis in four phases, which is useful to analyze the role of different atomic displacements in the vibrational modes of different symmetry. The calculated optical phonon frequencies at Γ point for the four phases are in good agreement with other theoretical and experimental data. The pressure-induced phase transition of BaTiO{sub 3} among four phases and the thermodynamic properties of BaTiO{sub 3} in rhombohedral phase have been investigated within the quasi-harmonic approximation (QHA). The sequence of the pressure-induced phase transition is rhombohedral → orthorhombic → tetragonal → cubic, and the corresponding transition pressure is 5.17, 5.92, 6.65 GPa, respectively. At zero pressure, the thermal expansion coefficient α{sub V}, heat capacity C{sub V}, Grueneisen parameter γ, and bulk modulus B of the rhombohedral phase BaTiO{sub 3} are estimated from 0 K to 200 K.

  1. Structural phase transition in lanthanum gallate as studied by Raman and X-ray diffraction measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dhak, P.; Pramanik, P. [Department of Chemistry, Indian Institute of Technology, Kharagpur 721302 (India); Bhattacharya, S.; Roy, Anushree [Department of Physics, Indian Institute of Technology, Kharagpur 721302 (India); Achary, S.N.; Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2011-08-15

    Lanthanum gallate (LaGaO{sub 3}) is known to undergo orthorhombic to rhombohedral first order phase transition at 150 C. In this article we have shown that by introducing 2% La deficiency in the system, coexistence of above two phases can be obtained at lower temperature and a complete phase transition occurs at 200 C. The evolution of structural parameters of the system with temperature is reported from X-ray diffraction measurements and Rietveld analysis of the diffraction patterns. The change in local octahedral distortion due to 2% La deficiency is revealed through the shift in the phonon modes of GaO{sub 6} octahedra, in both orthorhombic and rhombohedral phase. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Stable convergence and stable limit theorems

    CERN Document Server

    Häusler, Erich

    2015-01-01

    The authors present a concise but complete exposition of the mathematical theory of stable convergence and give various applications in different areas of probability theory and mathematical statistics to illustrate the usefulness of this concept. Stable convergence holds in many limit theorems of probability theory and statistics – such as the classical central limit theorem – which are usually formulated in terms of convergence in distribution. Originated by Alfred Rényi, the notion of stable convergence is stronger than the classical weak convergence of probability measures. A variety of methods is described which can be used to establish this stronger stable convergence in many limit theorems which were originally formulated only in terms of weak convergence. Naturally, these stronger limit theorems have new and stronger consequences which should not be missed by neglecting the notion of stable convergence. The presentation will be accessible to researchers and advanced students at the master's level...

  3. Structural and thermodynamic study of the system Th-C-N in the presence of excess graphite; the existence of a new hexagonal phase β 'ThCN' stable at high temperature

    International Nuclear Information System (INIS)

    Pialoux, A.

    1980-01-01

    The progressive reaction of nitrogen on the 'dicarbide' of thorium in the presence of excess graphite has been studied using X-ray diffractometry at high temperature (T 0 C) under controlled pressure (10 -3 0 C using measurements of crystalline parameters, equilibrium pressures and free enthalpies of standard formation of the various carbonitrides and nitrides observed. It is notably shown that the 'dicarbide' in stable at psub(N2)'s considerably weaker than those stated by Benz and Froxel, the nitrogen content of the γ Th C 2 ' cubic phase increasing furthermore with temperature. The new β 'ThCN' phase which does not quench crystallizes in the hexagonal system and in reattatched to the group space with P31 m, the various contractions of tis crystalline parameter Csub(β) is interpreted as a closing of the double bond of the C 2 pairs in this structure. The temperature of 1125 0 C is attributed to the new polymorphic transformation: β 'ThCN' hexagonal reversible α 'ThCN' monoclinic which appear to be of the martensitic type, the crystalline parameters of α'ThCN' being furthermore measured from 20 to 1125 0 C. (orig.)

  4. Identification of {2 anti 1 anti 10} and {10 anti 10} Laue patterns of hexagonal and rhombohedral silicon carbide polytypes

    International Nuclear Information System (INIS)

    Yoganathan, M.; Suttrop, W.; Devaty, R.P.; Choyke, W.J.

    1994-01-01

    The development of epitaxic and bulk-grown semiconductor SiC exhibiting uniform polytype phase homogeneity is critically dependent upon the accurate identification of crystallographic orientations corresponding to the desired polytype. In this paper, experimental transmission Laue photographs as well as computer-generated transmission Laue patterns are presented for {2 anti 1 anti 10} and {10 anti 10} faces of the 4H, 6H and 15R polytypes of silicon carbide. The transmission patterns permit easy recognition of polytypes and crystal orientations. (orig.)

  5. Analysis of urinary 8-isoprostane as an oxidative stress biomarker by stable isotope dilution using automated online in-tube solid-phase microextraction coupled with liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Mizuno, Keisuke; Kataoka, Hiroyuki

    2015-08-10

    We have developed a simple and sensitive method for the determination of the oxidative stress biomarker 8-isoprostane (8-IP) in human urine by automated online in-tube solid-phase microextraction (SPME) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) using a Zorbax Eclipse XDB-8 column and 0.1% formic acid/methanol (25/75, v/v) as a mobile phase. Electrospray MS/MS for 8-IP was performed on an API 4000 triple quadruple mass spectrometer in negative ion mode. The optimum in-tube SPME conditions were 20 draw/eject cycles with a sample size of 40 μL using a Carboxen 1006 PLOT capillary column for the extraction. The extracted compounds were easily desorbed from the capillary by passage of the mobile phase, and no carryover was observed. Total analysis time of this method including online extraction and analysis was about 30 min for each sample. The in-tube SPME LC-MS/MS method showed good linearity in the concentration range of 20-1000 pg/mL with a correlation coefficient r = 0.9999 for 8-IP using a stable isotope-labeled internal standard, 8-IP-d4. The detection limit of 8-IP was 3.3 pg/mL and the proposed method showed 42-fold higher sensitivity than the direct injection method. The intra-day and inter-day precisions (relative standard deviations) were below 5.0% and 8.5% (n = 5), respectively. This method was applied successfully to the analysis of urine samples without pretreatment or interference peaks. The recovery rates of 8-IP spiked into urine samples were above 92%. This method is useful for assessing the effects of oxidative stress and antioxidant intake. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Pressure-induced phase transitions in nanocrystalline ReO3

    International Nuclear Information System (INIS)

    Biswas, Kanishka; Muthu, D V S; Sood, A K; Kruger, M B; Chen, B; Rao, C N R

    2007-01-01

    Pressure-induced phase transitions in the nanocrystals of ReO 3 with an average diameter of ∼12 nm have been investigated in detail by using synchrotron x-ray diffraction and the results compared with the literature data of bulk samples of ReO 3 . The study shows that the ambient-pressure cubic I phase (space group Pm3-barm) transforms to a monoclinic phase (space group C 2/c), then to a rhombohedral I phase (space group R3-barc), and finally to another rhombohedral phase (rhombohedral II, space group R3-barc) with increasing pressure over the 0.0-20.3 GPa range. The cubic I to monoclinic transition is associated with the largest volume change (∼5%), indicative of a reconstructive transition. The transition pressures are generally lower than those known for bulk ReO 3 . The cubic II (Im3-bar) or tetragonal (P4/mbm) phases do not occur at lower pressures. The nanocrystals are found to be more compressible than bulk ReO 3 . On decompression to ambient pressure, the structure does not revert back to the cubic I structure

  7. Form-stable LiNO_3–NaNO_3–KNO_3–Ca(NO_3)_2/calcium silicate composite phase change material (PCM) for mid-low temperature thermal energy storage

    International Nuclear Information System (INIS)

    Jiang, Zhu; Leng, Guanghui; Ye, Feng; Ge, Zhiwei; Liu, Chuanping; Wang, Li; Huang, Yun; Ding, Yulong

    2015-01-01

    Graphical abstract: The figure (a) displays the microstructure of calcium silicate and the inset figure is the LiNO_3–NaNO_3–KNO_3–Ca(NO_3)_2/calcium silicate composite PCM. Calcium silicate is used as a porous skeleton material which could absorb large amounts of the nitrate PCM in voids and prevent the PCM from leakage during phase change process. Figure (b) shows the heat capacity of the composite PCM and the inset figure is the DSC curve of the composite. It indicates that this composite has a low melting point (103.5 °C) and good energy storage property. Based on the novel LiNO_3–NaNO_3–KNO_3–Ca(NO_3)_2/calcium silicate composite PCM, this work involves fabrication process, thermal and microstructural characterization, and chemical and physical stability measurements. - Highlights: • A novel LiNO_3–NaNO_3–KNO_3–Ca(NO_3)_2/calcium silicate composite PCM was prepared. • It has a low melting point (103.5 °C) and could remain stable until 585.5 °C. • It could keep form-stable without leakage during phase change process. • Thermal conductivity of the composite PCM reaches up to 1.177 W m"−"1 K"−"1. • It shows good thermal reliability after 1000 times heating and cooling cycling. - Abstract: In this paper, a novel form-stable LiNO_3–NaNO_3–KNO_3–Ca(NO_3)_2/calcium silicate composite PCM was developed by cold compression and sintering. The eutectic quaternary nitrate is used as PCM, while calcium silicate is used as structural supporting material. X-ray Diffraction (XRD) shows the PCM and the supporting material have good chemical compatibility. This composite PCM has a low melting point (103.5 °C) and remain stable without decomposition until 585.5 °C. Moreover, this composite shows excellent long term stability after 1000 melting and freezing cycles. Thermal conductivity of the composite was measured to be 1.177 W m"−"1 K"−"1, and that could be increased by adding thermal conductivity enhancers into the composite

  8. Origin and Luminescence of Anomalous Red-Emitting Center in Rhombohedral Ba9Lu2Si6O24:Eu(2+) Blue Phosphor.

    Science.gov (United States)

    Liu, Yongfu; Zhang, Changhua; Cheng, Zhixuan; Zhou, Zhi; Jiang, Jun; Jiang, Haochuan

    2016-09-06

    We obtain a blue phosphor, Ba9Lu2Si6O24:Eu(2+) (BLS:Eu(2+)), which shows a strong emission peak at 460 nm and a weak tail from 460 to 750 nm. A 610 nm red emission is observed for the first time in this kind of rhombohedral structure material, which is much different from the same crystal structure of Ba9Sc2Si6O24:Eu(2+) and Ba9Y2Si6O24:Eu(2+). The luminescence properties and decays from 10 to 550 K are discussed. The new red emission arises from a trapped exciton state of Eu(2+) at the Ba site with a larger coordination number (12-fold). It exhibits abnormal luminescence properties with a broad bandwidth and a large Stokes shift. Under the 400 nm excitation, the external quantum efficiency of BLS:Eu(2+) is 45.4%, which is higher than the 35.7% for the commercial blue phosphor BAM:Eu(2+). If the thermal stability of BLS:Eu(2+) can be improved, it will show promising applications in efficient near-UV-based white LEDs.

  9. Interface Modification of Bernal- and Rhombohedral-Stacked Trilayer-Graphene/Metal Electrode on Resistive Switching of Silver Electrochemical Metallization Cells.

    Science.gov (United States)

    Wang, Jer-Chyi; Chan, Ya-Ting; Chen, Wei-Fan; Wu, Ming-Chung; Lai, Chao-Sung

    2017-10-25

    Bernal- and rhombohedral-stacked trilayer graphene (B- and r-TLG) on nickel (Ni) and iridium (Ir) films acting as bottom electrodes (BEs) of silver electrochemical metallization cells (Ag-EMCs) have been investigated in this study. Prior to the fabrication of the EMC devices, Raman mapping and atomic force microscopy are applied to identify the B- and r-TLG sheets, with the latter revealing a significant D peak and a rough surface for the Ir film. The Ag-EMCs with the stacked BE of r-TLG on the Ir film show a conductive mechanism of Schottky emission at the positive top electrode bias for both high- and low-resistance states that can be examined by the resistance change with the device area and are modulated by pulse bias operation. Thus, an effective electron barrier height of 0.262 eV at the r-TLG and Ir interface is obtained because of the conspicuous energy gap of r-TLG on the Ir film and the van der Waals (vdW) gap between the r-TLG and Ir contact metal. With the use of Ni instead of Ir contact metal, the Ag-EMCs with TLG BE demonstrate +0.3 V/-0.75 V operation voltages, more than 10 4 s data retention at 115 °C and 250 times endurance testing, making the TLG sheets suitable for low-power nonvolatile memory applications on flexible substrates.

  10. stableGP

    Data.gov (United States)

    National Aeronautics and Space Administration — The code in the stableGP package implements Gaussian process calculations using efficient and numerically stable algorithms. Description of the algorithms is in the...

  11. Angina Pectoris (Stable Angina)

    Science.gov (United States)

    ... Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More Angina Pectoris (Stable Angina) Updated:Aug 21,2017 You may have heard the term “angina pectoris” or “stable angina” in your doctor’s office, ...

  12. UCDS Based Stable Injector Design, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The Universal Combustion Device Stability (UCDS) Process is the culmination of more than 40 years of research and provides the means to understand the complex...

  13. Dimensionally Stable Structural Space Cable, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In response to the need for an affordable exoplanet-analysis science mission, NASA has recently embarked on the ROSES Technology Development for Exoplanet Missions...

  14. Hexagonal perovskites with cationic vacancies. 28. Structure of rhombohedral 9 L stacking polytypes Ba/sub 3/Wsub(2-x)sup(VI)Nbsub(x)sup(V)vacantOsub(9-x/2)vacantsub(x/2)

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S; Treiber, U [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1981-07-01

    According to the intensity calculations for Ba/sub 3/Wsub(4/3)Nbsub(2/3)vacantOsub(26/3)vacantsub(1/3) and Ba/sub 3/Nb/sub 2/vacantO/sub 8/vacant(II) these rhombohedral 9 L compounds crystallize in the space group R-3m, sequence (hhc)/sub 3/. The refined, intensity related R' values are 6.9% (Ba/sub 3/Wsub(4/3)Nbsub(2/3)vacantOsub(26/3)vacantsub(1/3)) and 7.2% (Ba/sub 3/Nb/sub 2/vacantO/sub 8/vacant(II)). The relations between the rhombohedral 9 L structure (A/sub 3/M/sub 2/vacantO/sub 9/) and the palmierite type (A/sub 3/M/sub 2/vacantO/sub 8/vacant) are discussed.

  15. Presence of a monoclinic (Pm) phase in the morphotropic phase boundary region of multiferroic (1 − x)Bi(Ni{sub 1/2}Ti{sub 1/2})O{sub 3}-xPbTiO{sub 3} solid solution: A Rietveld study

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Rishikesh, E-mail: akhilesh-bhu@yahoo.com, E-mail: aksingh.mst@itbhu.ac.in; Singh, Akhilesh Kumar, E-mail: akhilesh-bhu@yahoo.com, E-mail: aksingh.mst@itbhu.ac.in [School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

    2014-07-28

    We present here the results of structural studies on multiferroic (1 − x)Bi(Ni{sub 1/2}Ti{sub 1/2})O{sub 3}-xPbTiO{sub 3} solid solution using Rietveld analysis on powder x-ray diffraction data in the composition range 0.35 ≤ x ≤ 0.55. The stability region of various crystallographic phases at room temperature for (1 − x)Bi(Ni{sub 1/2}Ti{sub 1/2})O{sub 3}-xPbTiO{sub 3} is determined precisely. Structural transformation from pseudo-cubic (x ≤ 0.40) to tetragonal (x ≥ 0.50) phase is observed via phase coexistence region demarcating the morphotropic phase boundary. The morphotropic phase boundary region consists of coexisting tetragonal and monoclinic structures with space group P4mm and Pm, respectively, stable in composition range 0.41 ≤ x ≤ 0.49 as confirmed by Rietveld analysis. The results of Rietveld analysis completely rule out the coexistence of rhombohedral and tetragonal phases in the morphotropic phase boundary region reported by earlier workers. A comparison between the bond lengths for “B-site cations-oxygen anions” obtained after Rietveld refinement, with the bond length calculated using Shannon-Prewitt ionic radii, reveals the ionic nature of B-O (Ni/Ti-O) bonds for the cubic phase and partial covalent character for the other crystallographic phases.

  16. De-escalation of tyrosine kinase inhibitor dose in patients with chronic myeloid leukaemia with stable major molecular response (DESTINY): an interim analysis of a non-randomised, phase 2 trial.

    Science.gov (United States)

    Clark, Richard E; Polydoros, Fotios; Apperley, Jane F; Milojkovic, Dragana; Pocock, Christopher; Smith, Graeme; Byrne, Jenny L; de Lavallade, Hugues; O'Brien, Stephen G; Coffey, Tony; Foroni, Letizia; Copland, Mhairi

    2017-07-01

    Discontinuation of tyrosine kinase inhibitor (TKI) therapy is feasible for some patients with chronic myeloid leukaemia with deep molecular responses; however, patients with stable major molecular response (MMR), but not MR4, have not been studied, nor has the effect of treatment de-escalation rather than outright cessation. We aimed to examine the effects of treatment de-escalation as a prelude to complete cessation, not only in patients with MR4 or greater, but also in those with MMR but not MR4. We did this interim analysis of a non-randomised, phase 2 trial at 20 hospitals in the UK. We recruited patients (aged ≥18 years) with chronic myeloid leukaemia in first chronic phase who had received TKI for 3 years or more and were either in stable MR4 (BCR-ABL1:ABL1 ratio 0·1%) on two consecutive samples. The primary endpoint of this interim analysis was the proportion of patients who lost MMR on de-escalation and regained MMR on TKI resumption. Analyses were by intention to treat. This study is registered with ClinicalTrials.gov, number NCT01804985. Between Dec 16, 2013 and April 10, 2015, we enrolled 174 patients into the MMR cohort (n=49) or the MR4 cohort (n=125). During the 12 months of half-dose therapy, 12 patients (7%) had molecular recurrence, all of whom regained MMR within 4 months of full-dose TKI resumption (median time to recovery 77 days). Recurrence was significantly lower in the MR4 cohort (three [2%; 90% CI 0·2-4·8] of 121 evaluable patients) than in the MMR cohort (nine [19%; 90% CI 9·5-28·0] of 48 evaluable patients; hazard ratio 0·12, 90% CI 0·04-0·37; p=0·0007), but was unrelated to previous TKI or TKI therapy duration. Adverse events (eg, lethargy, diarrhoea, rash, and nausea) improved during the first 3 months of de-escalation, though not thereafter. 16 serious adverse events were reported, including one fatality due to worsening pre-existing peripheral arterial occlusive disease in a patient who had received only imatinib. TKI de

  17. Hexagonal perovskites with cationic vacancies. 14. The rhombohedral 12 L-stacking polytypes Ba/sub 2/La/sub 2/Bsup(II)(W/sub 2/sup(VI)vacantO/sub 12/)

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1980-02-01

    Rhombohedral 12 L-stacking polytypes with cationic vacancies of type Ba/sub 2/La/sub 2/Bsup(II)(W/sub 2/sup(VI)vacantO/sub 12/) are reported for Bsup(II) = Mg, Zn (white), Ni (light brown) and Co (brown). For Bsup(II) = Cu, as a consequence of the Jahn Teller effect, a triclinic distorted lattice is observed.

  18. Structural Evolution of the R-T Phase Boundary in KNN-Based Ceramics

    KAUST Repository

    Lv, Xiang

    2017-10-04

    Although a rhombohedral-tetragonal (R-T) phase boundary is known to substantially enhance the piezoelectric properties of potassium-sodium niobate ceramics, the structural evolution of the R-T phase boundary itself is still unclear. In this work, the structural evolution of R-T phase boundary from -150 °C to 200 °C is investigated in (0.99-x)K0.5Na0.5Nb1-ySbyO3-0.01CaSnO3-xBi0.5K0.5HfO3 (where x=0~0.05 with y=0.035, and y=0~0.07 with x=0.03) ceramics. Through temperature-dependent powder X-ray diffraction (XRD) patterns and Raman spectra, the structural evolution was determined to be Rhombohedral (R, <-125 °C) → Rhombohedral+Orthorhombic (R+O, -125 °C to 0 °C) → Rhombohedral+Tetragonal (R+T, 0 °C to 150 °C) → dominating Tetragonal (T, 200 °C to Curie temperature (TC)) → Cubic (C, >TC). In addition, the enhanced electrical properties (e.g., a direct piezoelectric coefficient (d33) of ~450±5 pC/N, a conversion piezoelectric coefficient (d33*) of ~580±5 pm/V, an electromechanical coupling factor (kp) of ~0.50±0.02, and TC~250 °C), fatigue-free behavior, and good thermal stability were exhibited by the ceramics possessing the R-T phase boundary. This work improves understanding of the physical mechanism behind the R-T phase boundary in KNN-based ceramics and is an important step towards their adoption in practical applications. This article is protected by copyright. All rights reserved.

  19. Neutron Diffraction Study of the Irreversible R-MA-MC Phase Transition in Single Crystal Pb[(Zn1/3Nb2/3)1-xTix]O3

    NARCIS (Netherlands)

    Ohwada, Kenji; Hirota, Kazuma; Rehrig, Paul W.; Gehring, Peter M.; Noheda, Beatriz; Fujii, Yasuhiko; Park, Seung-Eek Eagle; Shirane, Gen

    2001-01-01

    Single crystals of the relaxor PZN-xPT display an enormously strong piezoelectric character. Recent x-ray scattering studies have revealed novel electric-field induced phase transitions in PZN-8%PT. As-grown crystals exhibit a rhombohedral structure that, under application of an electric field

  20. Stable Boundary Layer Issues

    OpenAIRE

    Steeneveld, G.J.

    2012-01-01

    Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The development of robust stable boundary layer parameterizations for use in NWP and climate models is hampered by the multiplicity of processes and their unknown interactions. As a result, these models suffer ...

  1. Pressure-induced phase transitions in Zr-rich PbZr{sub 1-x}Ti{sub x}O{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Souza Filho, A.G. [Departamento de Fisica, Universidade Federal do Ceara, Fortaleza, Ceara (Brazil)]. E-mail: agsf@fisica.ufc.br; Faria, J.L.B.; Freire, P.T.C.; Ayala, A.P.; Sasaki, J.M.; Melo, F.E.A.; Mendes Filho, J. [Departamento de Fisica, Universidade Federal do Ceara, Fortaleza, Ceara (Brazil); Araujo, E.B. [Departamento de Fisica e Quimica, Universidade Estadual de Sao Paulo, Campus de Ilha Solteira, Ilha Solteira, SP (Brazil); Eiras, J.A. [Departamento de Fisica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil)

    2001-08-20

    A Raman study of structural changes in the Zr-rich PbZr{sub 1-x}Ti{sub x}O{sub 3} (PZT) system under hydrostatic pressures up to 5.0 GPa is presented. We observe that externally applied pressure induces several phase transitions in PZT ceramics among phases with orthorhombic (A{sub O}), rhombohedral low-temperature (R{sub LT}), and rhombohedral high-temperature (R{sub HT}) symmetries (all found in PZT at ambient pressure and room temperature). Each of the compositions investigated (0.02{<=}x{<=}0.14) exhibits a high-pressure phase with orthorhombic (O{sub I'}) symmetry. We further report a detailed study of the pressure dependence of Raman frequencies to elucidate the phase transitions and to provide a set of pressure coefficients for the high-pressure phases. (author)

  2. Thermodinamically stable phases in the CaO-SiO2-Al2O3-CaSO4-H2O closed system at 25 ºC. Application to cementitious systems

    Directory of Open Access Journals (Sweden)

    Blanco-Varela, M. T.

    2009-06-01

    Full Text Available One of the chief causes of cement and concrete deterioration is the loss of durability prompted by sulphate attack. The existing standards call for long test periods (2- 12 months. Thermodynamic modelling is a particularly appropriate technique for studying systems that only reach equilibrium in the long term. Used in the present study to establish the fields of thermodynamic stability for the phases in the CaO-SiO2-Al2O3-CaSO4-H2O system at 25 ºC. According to the model, gypsum is stable at sulphate ion concentrations of 1.23e-2 mol/kg and over, while ettringite exhibits stability at concentrations ranging from 7.64e-6 to 1.54e-2 mol/kg. Ettringite is compatible with all system phases except SH and gypsum only with ettringite, the C-S-H gels, AH3 and SH. None of the calcium aluminates or silicoaluminates in the system is compatible with gypsum: in its presence, they all decompose to cement deteriorating ettringite. Finally, the model revealed that the maximum sulphate concentration at which C-S-H gel is stable is slightly higher in systems with than without Al2O3.Uno de los principales problemas asociados al deterioro de cementos y hormigones es la pérdida de durabilidad por ataque de sulfatos. La normativa existente requiere largos tiempos de ensayo (2-12 meses. La modelización termodinámica es una técnica particularmente adecuada para el estudio de sistemas que alcanzan el equilibrio en tiempos largos. Aplicando esta metodología se han establecido los campos de estabilidad termodinámica de las fases del sistema CaO-SiO2-Al2O3-CaSO4-H2O a 25 ºC. El yeso es estable a partir de la [SO42-] = 1,23e-2 mol/kg, y la ettringita es estable en un rango de [SO42-] = 7,64e-6 -1,54e-2 mol/kg. La ettringita es compatible con todas las fases del sistema excepto con SH y el yeso sólo con la ettringita, los geles C-S-H, el AH3 y el SH. Ninguno de los aluminatos o silicoaluminatos cálcicos son compatibles con el yeso, en su presencia se descomponen

  3. Stable isotopes labelled compounds

    International Nuclear Information System (INIS)

    1982-09-01

    The catalogue on stable isotopes labelled compounds offers deuterium, nitrogen-15, and multiply labelled compounds. It includes: (1) conditions of sale and delivery, (2) the application of stable isotopes, (3) technical information, (4) product specifications, and (5) the complete delivery programme

  4. Evolutionary Stable Strategy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 21; Issue 9. Evolutionary Stable Strategy: Application of Nash Equilibrium in Biology. General Article Volume 21 Issue 9 September 2016 pp 803- ... Keywords. Evolutionary game theory, evolutionary stable state, conflict, cooperation, biological games.

  5. Stable Boundary Layer Issues

    NARCIS (Netherlands)

    Steeneveld, G.J.

    2012-01-01

    Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The

  6. Anomalous magnetoelastic behaviour near morphotropic phase boundary in ferromagnetic Tb{sub 1-x}Nd{sub x}Co{sub 2} system

    Energy Technology Data Exchange (ETDEWEB)

    Murtaza, Adil; Yang, Sen, E-mail: yang.sen@mail.xjtu.edu.cn; Zhou, Chao; Chang, Tieyan; Chen, Kaiyun; Tian, Fanghua; Song, Xiaoping [School of Science, MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behaviour of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Suchomel, Matthrew R.; Ren, Y. [X-Ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2016-08-01

    In this work, we report a morphotropic phase boundary (MPB) involved ferromagnetic system Tb{sub 1-x}Nd{sub x}Co{sub 2} and reveal the corresponding structural and magnetoelastic properties of this system. With high resolution synchrotron X-ray diffractometry, the crystal structure of the TbCo{sub 2}-rich side is detected to be rhombohedral and that of NdCo{sub 2}-rich side is tetragonal below their respective Curie temperatures T{sub C}. The MPB composition Tb{sub 0.35}Nd{sub 0.65}Co{sub 2} corresponds to the coexistence of the rhombohedral phase (R-phase) and tetragonal phase (T-phase). Contrary to previously reported MPB involved ferromagnetic systems, the MPB composition of Tb{sub 0.35}Nd{sub 0.65}Co{sub 2} shows minimum magnetization which can be understood as compensation of sublattice moments between the R-phase and the T-phase. Furthermore, magnetostriction of Tb{sub 1-x}Nd{sub x}Co{sub 2} decreases with increasing Nd concentration until x = 0.8 and then increases in the negative direction with further increasing Nd concentration; the optimum point for magnetoelastic properties lies towards the rhombohedral phase. Our work not only shows an anomalous type of ferromagnetic MPB but also provides an effective way to design functional materials.

  7. Pressure-induced phase transitions of multiferroic BiFeO3

    OpenAIRE

    XiaoLi, Zhang; Ye, Wu; Qian, Zhang; JunCai, Dong; Xiang, Wu; Jing, Liu; ZiYu, Wu; DongLiang, Chen

    2013-01-01

    Pressure-induced phase transitions of multiferroic BiFeO3 have been investigated using synchrotron radiation X-ray diffraction with diamond anvil cell technique at room temperature. Present experimental data clearly show that rhombohedral (R3c) phase of BiFeO3 first transforms to monoclinic (C2/m) phase at 7 GPa, then to orthorhombic (Pnma) phase at 11 GPa, which is consistent with recent theoretical ab initio calculation. However, we observe another peak at 2{\\theta}=7{\\deg} in the pressure ...

  8. Normal modified stable processes

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole Eiler; Shephard, N.

    2002-01-01

    Gaussian (NGIG) laws. The wider framework thus established provides, in particular, for added flexibility in the modelling of the dynamics of financial time series, of importance especially as regards OU based stochastic volatility models for equities. In the special case of the tempered stable OU process......This paper discusses two classes of distributions, and stochastic processes derived from them: modified stable (MS) laws and normal modified stable (NMS) laws. This extends corresponding results for the generalised inverse Gaussian (GIG) and generalised hyperbolic (GH) or normal generalised inverse...

  9. Applications of stable isotopes

    International Nuclear Information System (INIS)

    Letolle, R.; Mariotti, A.; Bariac, T.

    1991-06-01

    This report reviews the historical background and the properties of stable isotopes, the methods used for their measurement (mass spectrometry and others), the present technics for isotope enrichment and separation, and at last the various present and foreseeable application (in nuclear energy, physical and chemical research, materials industry and research; tracing in industrial, medical and agronomical tests; the use of natural isotope variations for environmental studies, agronomy, natural resources appraising: water, minerals, energy). Some new possibilities in the use of stable isotope are offered. A last chapter gives the present state and forecast development of stable isotope uses in France and Europe

  10. Hexagonal perovskites with cationic vacancies. 19. The rhombohedral 12 L stacking polytypes Ba/sub 3/LaBsup(III) (W/sub 2/sup(VI)vacantO/sub 12/)

    Energy Technology Data Exchange (ETDEWEB)

    Rother, H J; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1980-06-01

    Hexagonal perovskites are described for the new type Ba/sub 3/LaBsup(III)(W/sub 2/sup(VI)vacantO/sub 12/) with Bsup(III) = Sc, In, Lu, Yb. According to the intensity calculations for Ba/sub 3/LaIn(W/sub 2/vacantO/sub 12/) they crystallize in a rhombohedral 12 L structure with the sequence (3)(1) respectively (hhcc)/sub 3/; space group R3m. The refined, intensity related R' value is 6.7%.

  11. Hexagonal perovskites with cationic vacancies. 15. Ba/sub 9/Nb/sub 6/Wvacant/sub 2/O/sub 27/ - the first perovskite stacking polytype of rhombohedral 27 L-type

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1980-02-01

    The perovskite stacking polytype Ba/sub 9/Nb/sub 6/sup(V)Wsup(VI)vacant/sub 2/O/sub 27/ (white) is the first representative of a rhombohedral 27 L-type. The lattice parameters (trigonal setting) are: a = 5.79/sub 3/ A; c = 63.4/sub 1/ A; Z = 3 (rhosub(exp) = 6.4/sub 6/ g/cm/sup 3/; rhosub(calc) = 6.51/sub 2/ g/cm/sup 3/). The corresponding Tasup(V)-compound is isotypic; it tends to develop stacking faults.

  12. Hexagonal perovskites with cationic vacancies. 16. Rhombohedral 12 L-stacking polytypes Ba/sub 3/Asup(III)M/sub 3/sup(V)vacantO/sub 12/ with Msup(V) = Nb, Ta

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1980-02-01

    The white quaternary oxides Ba/sub 3/LaM/sub 3/sup(V)vacantO/sub 12/ with Msup(V) = Nb, Ta belong to the group of hexagonal perovskites with cationic vacancies. They crystallize in a rhombohedral 12 L-structure (sequence (hhcc)/sub 3/; space group R3m) with a = 5.75 A; c = 28.1 A (Msup(V) = Nb); a = 5.74 A; c = 28.2 A (Ta) and Z = 3. Signs for the formation of isotypic compounds with Asup(III) = Pr, Nd could be obtained as well.

  13. Analysing Stable Time Series

    National Research Council Canada - National Science Library

    Adler, Robert

    1997-01-01

    We describe how to take a stable, ARMA, time series through the various stages of model identification, parameter estimation, and diagnostic checking, and accompany the discussion with a goodly number...

  14. Uses of stable isotopes

    International Nuclear Information System (INIS)

    Axente, Damian

    1998-01-01

    The most important fields of stable isotope use with examples are presented. These are: 1. Isotope dilution analysis: trace analysis, measurements of volumes and masses; 2. Stable isotopes as tracers: transport phenomena, environmental studies, agricultural research, authentication of products and objects, archaeometry, studies of reaction mechanisms, structure and function determination of complex biological entities, studies of metabolism, breath test for diagnostic; 3. Isotope equilibrium effects: measurement of equilibrium effects, investigation of equilibrium conditions, mechanism of drug action, study of natural processes, water cycle, temperature measurements; 4. Stable isotope for advanced nuclear reactors: uranium nitride with 15 N as nuclear fuel, 157 Gd for reactor control. In spite of some difficulties of stable isotope use, particularly related to the analytical techniques, which are slow and expensive, the number of papers reporting on this subject is steadily growing as well as the number of scientific meetings organized by International Isotope Section and IAEA, Gordon Conferences, and regional meeting in Germany, France, etc. Stable isotope application development on large scale is determined by improving their production technologies as well as those of labeled compound and the analytical techniques. (author)

  15. Calcium stable isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Gausonne, Nikolaus [Muenster Univ. (Germany). Inst. fuer Mineralogie; Schmitt, Anne-Desiree [Strasbourg Univ. (France). LHyGeS/EOST; Heuser, Alexander [Bonn Univ. (Germany). Steinmann-Inst. fuer Geologie, Mineralogie und Palaeontologie; Wombacher, Frank [Koeln Univ. (Germany). Inst. fuer Geologie und Mineralogie; Dietzel, Martin [Technische Univ. Graz (Austria). Inst. fuer Angewandte Geowissenschaften; Tipper, Edward [Cambridge Univ. (United Kingdom). Dept. of Earth Sciences; Schiller, Martin [Copenhagen Univ. (Denmark). Natural History Museum of Denmark

    2016-08-01

    This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

  16. Calcium stable isotope geochemistry

    International Nuclear Information System (INIS)

    Gausonne, Nikolaus; Schmitt, Anne-Desiree; Heuser, Alexander; Wombacher, Frank; Dietzel, Martin; Tipper, Edward; Schiller, Martin

    2016-01-01

    This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

  17. Electrically Controllable Spontaneous Magnetism in Nanoscale Mixed Phase Multiferroics

    Energy Technology Data Exchange (ETDEWEB)

    He, Q.; Chu, Y. H.; Heron, J. T.; Yang, S. Y.; Wang, C. H.; Kuo, C. Y.; Lin, H. J.; Yu, P.; Liang, C. W.; Zeches, R. J.; Chen, C. T.; Arenholz, E.; Scholl, A.; Ramesh, R.

    2010-08-02

    The emergence of enhanced spontaneous magnetic moments in self-assembled, epitaxial nanostructures of tetragonal (T-phase) and rhombohedral phases (R-phase) of the multiferroic BiFeO{sub 3} system is demonstrated. X-ray magnetic circular dichroism based photoemission electron microscopy (PEEM) was applied to investigate the local nature of this magnetism. We find that the spontaneous magnetization of the R-phase is significantly enhanced above the canted antiferromagnetic moment in the bulk phase, as a consequence of a piezomagnetic coupling to the adjacent T-phase and the epitaxial constraint. Reversible electric field control and manipulation of this magnetic moment at room temperature is shown using a combination of piezoresponse force microscopy and PEEM studies.

  18. New transformation mechanism for a zinc-blende to rocksalt phase transformation in MgS

    International Nuclear Information System (INIS)

    Durandurdu, Murat

    2009-01-01

    The stability of the zinc-blende structured MgS is studied using a constant pressure ab initio molecular dynamics technique. A phase transition into a rocksalt structure is observed through the simulation. The zinc-blende to rocksalt phase transformation proceeds via two rhombohedral intermediate phases within R3m (No:160) and R3-barm (No:166) symmetries and does not involve any bond breaking. This mechanism is different from the previously observed mechanism in molecular dynamics simulations. (fast track communication)

  19. Stable isotope studies

    International Nuclear Information System (INIS)

    Ishida, T.

    1992-01-01

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs

  20. Interactive Stable Ray Tracing

    DEFF Research Database (Denmark)

    Dal Corso, Alessandro; Salvi, Marco; Kolb, Craig

    2017-01-01

    Interactive ray tracing applications running on commodity hardware can suffer from objectionable temporal artifacts due to a low sample count. We introduce stable ray tracing, a technique that improves temporal stability without the over-blurring and ghosting artifacts typical of temporal post-pr...

  1. The Stable Concordance Genus

    OpenAIRE

    Kearney, M. Kate

    2013-01-01

    The concordance genus of a knot is the least genus of any knot in its concordance class. Although difficult to compute, it is a useful invariant that highlights the distinction between the three-genus and four-genus. In this paper we define and discuss the stable concordance genus of a knot, which describes the behavior of the concordance genus under connected sum.

  2. Stable radiographic scanning agents

    International Nuclear Information System (INIS)

    1976-01-01

    Stable compositions which are useful in the preparation of Technetium-99m-based scintigraphic agents are discussed. They are comprised of ascorbic acid or a pharmaceutically acceptable salt or ester thereof in combination with a pertechnetate reducing agent or dissolved in oxidized pertechnetate-99m (sup(99m)TcO 4 - ) solution

  3. Some stable hydromagnetic equilibria

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J L; Oberman, C R; Kulsrud, R M; Frieman, E A [Project Matterhorn, Princeton University, Princeton, NJ (United States)

    1958-07-01

    We have been able to find and investigate the properties of equilibria which are hydromagnetically stable. These equilibria can be obtained, for example, by wrapping conductors helically around the stellarator tube. Systems with I = 3 or 4 are indicated to be optimum for stability purposes. In some cases an admixture of I = 2 fields can be advantageous for achieving equilibrium. (author)

  4. Stable isotope analysis

    International Nuclear Information System (INIS)

    Tibari, Elghali; Taous, Fouad; Marah, Hamid

    2014-01-01

    This report presents results related to stable isotopes analysis carried out at the CNESTEN DASTE in Rabat (Morocco), on behalf of Senegal. These analyzes cover 127 samples. These results demonstrate that Oxygen-18 and Deuterium in water analysis were performed by infrared Laser spectroscopy using a LGR / DLT-100 with Autosampler. Also, the results are expressed in δ values (‰) relative to V-SMOW to ± 0.3 ‰ for oxygen-18 and ± 1 ‰ for deuterium.

  5. Forensic Stable Isotope Biogeochemistry

    Science.gov (United States)

    Cerling, Thure E.; Barnette, Janet E.; Bowen, Gabriel J.; Chesson, Lesley A.; Ehleringer, James R.; Remien, Christopher H.; Shea, Patrick; Tipple, Brett J.; West, Jason B.

    2016-06-01

    Stable isotopes are being used for forensic science studies, with applications to both natural and manufactured products. In this review we discuss how scientific evidence can be used in the legal context and where the scientific progress of hypothesis revisions can be in tension with the legal expectations of widely used methods for measurements. Although this review is written in the context of US law, many of the considerations of scientific reproducibility and acceptance of relevant scientific data span other legal systems that might apply different legal principles and therefore reach different conclusions. Stable isotopes are used in legal situations for comparing samples for authenticity or evidentiary considerations, in understanding trade patterns of illegal materials, and in understanding the origins of unknown decedents. Isotope evidence is particularly useful when considered in the broad framework of physiochemical processes and in recognizing regional to global patterns found in many materials, including foods and food products, drugs, and humans. Stable isotopes considered in the larger spatial context add an important dimension to forensic science.

  6. Exploration of phase transition in ThS under pressure: An ab-initio investigation

    Science.gov (United States)

    Sahoo, B. D.; Mukherjee, D.; Joshi, K. D.; Kaushik, T. C.

    2018-04-01

    The ab-initio total energy calculations have been performed in thorium sulphide (ThS) to explore its high pressure phase stability. Our calculations predict a phase transformation from ambient rocksalt type structure (B1 phase) to a rhombohedral structure (R-3m phase) at ˜ 15 GPa and subsequently R-3m phase transforms to CsCl type structure (B2 phase) at ˜ 45 GPa. The first phase transition has been identified as second order type; whereas, the second transition is of first order type with volume discontinuity of 6.5%. The predicted high pressure R-3m phase is analogous to the experimentally observed hexagonal (distorted fcc) phase (Benedict et al., J. Less-Common Met., 1984) above 20 GPa. Further, using these calculations we have derived the equation of state which has been utilized to determine various physical quantities such as zero pressure equilibrium volume, bulk modulus, and pressure derivative of bulk modulus at ambient conditions.

  7. Thermal expansion and phase transitions of α-AlF{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Morelock, Cody R.; Hancock, Justin C. [School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400 (United States); Wilkinson, Angus P., E-mail: angus.wilkinson@chemistry.gatech.edu [School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)

    2014-11-15

    ReO{sub 3}-type materials are of interest for their potential low or negative thermal expansion. Many metal trifluorides MF{sub 3} adopt the cubic form of this structure at elevated temperatures, which rhombohedrally distorts upon cooling. The rhombohedral form displays strong positive volume thermal expansion, but cubic MF{sub 3} display much lower and sometimes negative thermal expansion. The expansion behavior of α-AlF{sub 3} was characterized via synchrotron powder diffraction between 323 and 1177 K. α-AlF{sub 3} is rhombohedral at ambient conditions and displays strongly anisotropic thermal expansion. The volume coefficient of thermal expansion (CTE), α{sub V}, at 500 K is ∼86 ppm K{sup −1}, but the linear CTE along the c-axis, α{sub c}, is close to zero. α-AlF{sub 3} becomes cubic on heating to ∼713 K and continues to show positive thermal expansion above the phase transition (α{sub V}(900 K) ∼25 ppm K{sup −1}). - Graphical abstract: α-AlF{sub 3} has a rhombohedrally distorted ReO{sub 3}-type structure at ambient conditions and displays strongly positive volume thermal expansion that is highly anisotropic; the material becomes cubic on heating above ∼713 K and continues to show positive thermal expansion. - Highlights: • ReO{sub 3}-type α-AlF{sub 3} displays strongly anisotropic thermal expansion below 713 K. • α-AlF{sub 3} is cubic above 713 K and maintains positive (isotropic) thermal expansion. • The volume CTE changes from ∼86 to ∼25 ppm K{sup −1} on heating from 500 to 900 K. • The PTE of cubic α-AlF{sub 3} may be due to the presence of local octahedral tilts.

  8. Ca{sub 2}Cr{sub 0.5}Ga{sub 1.5}O{sub 5}—An extremely redox-stable brownmillerite phase

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Kun; Amano Patino, Midori; Hayward, Michael A., E-mail: michael.hayward@chem.ox.ac.uk

    2015-02-15

    Investigation of the Ca{sub 2}Cr{sub x}Ga{sub 2−x}O{sub 5} compositional series reveals a maximum chromium solubility of 25%. The most chromium rich composition, Ca{sub 2}Cr{sub 0.5}Ga{sub 1.5}O{sub 5}, adopts a brownmillerite-type anion deficient perovskite structure described in space group Pnma (a=5.368 Å, b=14.547 Å, c=5.593 Å). Neutron powder diffraction data reveals rigorous B-site cation order, with all of the tetrahedral coordination sites occupied exclusively by gallium and the octahedral coordination sites occupied by gallium or chromium. Annealing studies reveals Ca{sub 2}Cr{sub 0.5}Ga{sub 1.5}O{sub 5} is stable in both oxidizing (100% O{sub 2}) and reducing (5% H{sub 2} in N{sub 2}) conditions up to 800 °C, suggesting it could find application as a stable host lattice for fuel cell electrodes or electrolytes with suitable doping to enhance catalytic behaviour and/or anionic conductivity. - Graphical abstract: Ca{sub 2}Cr{sub 0.5}Ga{sub 1.5}O{sub 5}, adopts a brownmillerite-type anion deficient perovskite structure yet it is stable in both oxidizing (100% O{sub 2}) and reducing (5% H{sub 2} in N{sub 2}) conditions up to 800 °C. - Highlights: • Anion deficient oxide stable to both oxidation and reduction up to 800 °C. • Cation-ordered brownmillerite structure determined by powder neutron diffraction. • Low solubility of Cr{sup 3+} in framework due to spherical d{sup 3} electron configuration.

  9. Hexagonal perovskites with cationic vacancies. 13. Rhombohedral 12 L-stacking polytypes Ba/sub 4/M/sub 2/sup(V)WvacantO/sub 12/ with Msup(V) = Nb, Ta

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.)

    1979-10-01

    The white quaternary oxides Ba/sub 4/Nb/sub 2/WvacantO/sub 12/ and Ba/sub 4/Ta/sub 2/WvacantO/sub 12/ belong to the group of hexagonal perovskites with cationic vacancies. They crystallize in the rhombohedral 12 L-type: Sequence (3)(1) = (hhcc)/sub 3/; space group R/sup -/3m (Ba/sub 4/Nb/sub 2/WvacantO/sub 12/: a = 5.77/sub 6/ A; c = 28.0/sub 55/ A; Ba/sub 4/Ta/sub 2/WvacantO/sub 12/: a = 5.77/sub 3/ A; c = 28.0/sub 75/ A; Z = 3).

  10. Hexagonal perovskites with cationic vacancies. 20. Ba/sub 6/Nb/sub 4/ZrvacantO/sub 18/ - a new stacking polytype with a rhombohedral 18 L structure

    Energy Technology Data Exchange (ETDEWEB)

    Schittenhelm, H J; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1980-06-01

    The white Ba/sub 6/Nb/sub 4/ZrvacantO/sub 18/ crystallizes in a rhombohedral 18 L structure (a = 5.82/sub 1/ A; c = 42.6/sub 3/ A; space group R3m) with three formula units for the trigonal setting (rhosub(exp) = 6.0/sub 5/ g/cm/sup 3/; rhosub(calc) = 6.27/sub 1/ g/cm/sup 3/). The corresponding Tisup(IV) and Hfsup(IV) compounds, Ba/sub 6/Nb/sub 4/TivacantO/sub 18/ and Ba/sub 6/Nb/sub 4/HfvacantO/sub 18/, are isotypic.

  11. Hexagonal perovskites with cationic vacancies. 23. Rhombohedral 12 L stacking polytypes of type Ba/sub 3/LaBsup(II)Resup(VII)Wsup(VI)vacantO/sub 12/ with Bsup(II) = Mg, Co, Ni, Cu, Zn

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, M; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1980-11-01

    The rhombohedral 12 L pervoskites with cationic vacancies of type Ba/sub 3/LaBsup(II)ReWvacantO/sub 12/ with Bsup(II) = Mg, Co, Ni, Cu, Zn are isotypic. According to intensity calculations on powder patterns of Ba/sub 3/LaZnReWvacantO/sub 12/ the series crystallize in the space group R-3m with the sequence (hhcc)/sub 3/; the refined, intensity related R' value is 5.7%. The octahedral net consists of blocks of three face connected octahedra with central void (ReWvacantO/sub 12/ units), which are linked via common corners through single octahedra, occupied by zinc.

  12. Hexagonal perovskites with cationic vacancies. 22. Polymorphism of the rhombohedral 12 L stacking polytypes in the system Sr/sub 4-x/Ba/sub x/NiRe/sub 2/vacantO/sub 12/

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, M; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1980-10-01

    In the system Sr/sub 4-x/Ba/sub x/NiRe/sub 2/vacantO/sub 12/ two different stacking polytypes of the rhombohedral 12 L type are present. Both crystallize in the space group R-3m with the same sequence of the close packed AO/sub 3/ sheets: (3)(1) = (hhcc)/sub 3/. Accordingly the octahedral net consists of groups of three face connected octahedra which are linked by another through single corner sharing octahedra. In the strontium compound, Sr/sub 4/NiRe/sub 2/vacantO/sub 12/, the occupation of the octahedral holes is the same as in other rhombohedral 12 L perovskites of type A/sub 4/(B, M)/sub 3/vacantO/sub 12/ (The two outer octahedra are occupied by rhenium, the center is vacant and the nickel is located in the single octahedron). In the barium stacking polytype, Ba/sub 4/NiRe/sub 2/vacantO/sub 12/, the distribution is completely altered: The rhenium atoms occupy the central position in the block of three face connected octahedra and the single octahedron, the nickel atom and the vacancy are distributed statistically over the two outer positions in the block of three octahedra. Intensity calculations on powder data gave the intensity related R' value of 7.2% for Sr/sub 4/NiRe/sub 2/vacantO/sub 12/ and 6.2% for Ba/sub 4/NiRe/sub 2/vacantO/sub 12/.

  13. Strontium stable isotope behaviour accompanying basalt weathering

    Science.gov (United States)

    Burton, K. W.; Parkinson, I. J.; Gíslason, S. G. R.

    2016-12-01

    The strontium (Sr) stable isotope composition of rivers is strongly controlled by the balance of carbonate to silicate weathering (Krabbenhöft et al. 2010; Pearce et al. 2015). However, rivers draining silicate catchments possess distinctly heavier Sr stable isotope values than their bedrock compositions, pointing to significant fractionation during weathering. Some have argued for preferential release of heavy Sr from primary phases during chemical weathering, others for the formation of secondary weathering minerals that incorporate light isotopes. This study presents high-precision double-spike Sr stable isotope data for soils, rivers, ground waters and estuarine waters from Iceland, reflecting both natural weathering and societal impacts on those environments. The bedrock in Iceland is dominantly basaltic, d88/86Sr ≈ +0.27, extending to lighter values for rhyolites. Geothermal waters range from basaltic Sr stable compositions to those akin to seawater. Soil pore waters reflect a balance of input from primary mineral weathering, precipitation and litter recycling and removal into secondary phases and vegetation. Rivers and ground waters possess a wide range of d88/86Sr compositions from +0.101 to +0.858. Elemental and isotope data indicate that this fractionation primarily results from the formation or dissolution of secondary zeolite (d88/86Sr ≈ +0.10), but also carbonate (d88/86Sr ≈ +0.22) and sometimes anhydrite (d88/86Sr ≈ -0.73), driving the residual waters to heavier or lighter values, respectively. Estuarine waters largely reflect mixing with seawater, but are also be affected by adsorption onto particulates, again driving water to heavy values. Overall, these data indicate that the stability and nature of secondary weathering phases, exerts a strong control on the Sr stable isotope composition of silicate rivers. [1] Krabbenhöft et al. (2010) Geochim. Cosmochim. Acta 74, 4097-4109. [2] Pearce et al. (2015) Geochim. Cosmochim. Acta 157, 125-146.

  14. Pressure-induced anomalous phase transitions and colossal enhancement of piezoelectricity in PbTiO3.

    Science.gov (United States)

    Wu, Zhigang; Cohen, Ronald E

    2005-07-15

    We find an unexpected tetragonal-to-monoclinic-to-rhombohedral-to-cubic phase transition sequence induced by pressure, and a morphotropic phase boundary in a pure compound using first-principles calculations. Huge dielectric and piezoelectric coupling constants occur in the transition regions, comparable to those observed in the new complex single-crystal solid-solution piezoelectrics such as Pb(Mg(1/3)Nb(2/3))O3-PbTiO3, which are expected to revolutionize electromechanical applications. Our results show that morphotropic phase boundaries and giant piezoelectric effects do not require intrinsic disorder, and open the possibility of studying this effect in simple systems.

  15. Theory of stable allocations

    Directory of Open Access Journals (Sweden)

    Pantelić Svetlana

    2014-01-01

    Full Text Available The Swedish Royal Academy awarded the 2012 Nobel Prize in Economics to Lloyd Shapley and Alvin Roth, for the theory of stable allocations and the practice of market design. These two American researchers worked independently from each other, combining basic theory and empirical investigations. Through their experiments and practical design they generated a flourishing field of research and improved the performance of many markets. Born in 1923 in Cambridge, Massachusetts, Shapley defended his doctoral thesis at Princeton University in 1953. For many years he worked at RAND, and for more than thirty years he was a professor at UCLA University. He published numerous scientific papers, either by himself or in cooperation with other economists.

  16. Effect of Cr substitution on magnetic and magnetic entropy change of La{sub 0.65}Eu{sub 0.05}Sr{sub 0.3}Mn{sub 1−x}Cr{sub x}O{sub 3} (0.05≤x≤0.15) rhombohedral nanocrystalline near room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Bellouz, R., E-mail: bellouzridha@yahoo.fr [Laboratoire de Physico-chimie des Matériaux, Département de Physique, Faculté des Sciences de Monastir,Université de Monastir, 5019 (Tunisia); Oumezzine, M. [Laboratoire de Physico-chimie des Matériaux, Département de Physique, Faculté des Sciences de Monastir,Université de Monastir, 5019 (Tunisia); Hlil, E.K. [Institut Néel, National Centre for Scientific Research, Université Joseph Fourier, B.P. 166, 38042 Grenoble (France); Dhahri, E. [Laboratoire de Physique appliqué, Département de physique, Faculté des Sciences de Sfax, 3018 (Tunisia)

    2015-02-01

    We have studied the effect of Cr substitution on magnetic and magnetocaloric properties in nanocrystalline La{sub 0.65}Eu{sub 0.05}Sr{sub 0.3}Mn{sub 1−x}Cr{sub x}O{sub 3} (x=0.05, 0.1 and 0.15). The materials were prepared using the Pechini sol–gel method. All the studied samples were crystallized into a single phase rhombohedral structure with R−3C space group. Magnetic measurements indicate that the ferromagnetic double exchange interaction is weakened with increasing Cr concentration, resulting in a shift in T{sub C} from 338 K to 278 K as x varied between 0.05 and 0.15. Detailed analyzes in the vicinity of the ferromagnetic (FM)–paramagnetic (PM) phase-transition temperature prove the samples undergoing a second-order phase transition. The magnetocaloric effect is calculated from the measurement of initial isothermal magnetization versus magnetic field at various temperatures. The maximum magnetic entropy change |ΔS{sub M}{sup max}| is found to decrease with increasing of Cr content from 4.04 J/Kg K for x=0.05–0.78 J/KgK for x=0.15 upon 5 T applied field change. The relative cooling power (RCP) of La{sub 0.65}Eu{sub 0.05}Sr{sub 0.3}Mn{sub 1−x}Cr{sub x}O{sub 3} series is nearly 54% of pure Gd, which will be an interesting system for application in room temperature refrigeration. - Highlights: • Nanocrystalline materials La{sub 0.65}Eu{sub 0.05}Sr{sub 0.3}Mn{sub 1−x}Cr{sub x}O{sub 3} were obtained. • The Cr substitution decreases the T{sub C} from 338 K for x=0.05–278 K for x=0.15. • The relative cooling power of La{sub 0.65}Eu{sub 0.05}Sr{sub 0.3}Mn{sub 1−x}Cr{sub x}O{sub 3} is nearly 54% of pure Gd. • Arrott plot analyses was applied to study the order of the magnetic transition. • La{sub 0.65}Eu{sub 0.05}Sr{sub 0.3}Mn{sub 1−x}Cr{sub x}O{sub 3} samples show second order PM–FM transition at T=T{sub C}.

  17. Bi-stable optical actuator

    Science.gov (United States)

    Holdener, Fred R.; Boyd, Robert D.

    2000-01-01

    The present invention is a bi-stable optical actuator device that is depowered in both stable positions. A bearing is used to transfer motion and smoothly transition from one state to another. The optical actuator device may be maintained in a stable position either by gravity or a restraining device.

  18. Pressure-induced phase transitions of multiferroic BiFeO3

    International Nuclear Information System (INIS)

    Zhang Xiaoli; Dong Juncai; Liu Jing; Chen Dongliang; Wu Ye; Zhang Qian; Wu Xiang; Wu Ziyu

    2013-01-01

    Pressure-induced phase transitions of multiferroic BiFeO 3 have been investigated using synchrotron radiation X-ray diffraction with diamond anvil cell technique at room temperature. Present experimental data clearly show that rhombohedral (R3c) phase of BiFeO 3 first transforms to monoclinic (C2/m) phase at 7 GPa, then to orthorhombic (Pnma) phase at 11 GPa, which is consistent with recent theoretical ab initio calculation. However, we observe another peak at 2θ=7° in the pressure range of 5-7 GPa that has not been reported previously. Further analysis reveals that this reflection peak is attributed to the orthorhombic (Pbam) phase, indicating the coexistence of monoclinic phase with orthorhombic phase in low pressure range. (authors)

  19. Investigation of phase stability in the scandia-zirconia

    International Nuclear Information System (INIS)

    Grosso, Robson Lopes

    2016-01-01

    In this work, the phase stability of scandia-zirconia (ScSZ) system was investigated by the thermodynamic study of nanoparticles, within the range of 0 to 20 mol% Sc 2 O 3 , and by codoping of ZrO 2 -10 mol% Sc 2 O 3 (10ScSZ) with Dy 2 O 3 and Nb 2 O 5 . The phase stability of ScSZ was evaluated based on thermodynamic data collected by water adsorption microcalorimetry and high temperature oxide melt solution. Nanostructured zirconia-scandia solid solutions were synthesized by coprecipitation method. Thermodynamic data were determined for ScSZ polymorph (monoclinic, tetragonal, cubic, rhombohedral β and γ) found by X-ray diffraction. This systemic work resulted in an unprecedented phase diagram at the nanoscale of particle size-composition. The effects of additives on 10ScSZ were investigated aiming to stabilize the cubic (c) structure at room temperature and to suppress the characteristic cubic-rhombohedral β phase transformation. Compositions were prepared by coprecipitation and solid state reaction. Materials were sintered by conventional and spark plasma sintering. Full stabilization of the cubic phase was attained by 1 mol% Dy 2 O 3 and 0.5 mol% Nb 2 O 5 additions. The smallest Nb 2 O 5 content required for cubic phase stabilization was attributed to liquid phase formation during sintering and to small ionic radius of Nb 5+ . Results of high temperature X-ray diffraction and thermal analysis show suppression of the c-β transformation. Samples containing 0.5 mol% Nb 2 O 5 show total ionic conductivity similar to 10ScSZ without additives within a broad temperature range with high stability during 170 h at 600 °C. (author)

  20. Rare stable isotopes in meteorites

    International Nuclear Information System (INIS)

    Wilson, G.C.

    1981-01-01

    Secondary Ion Mass Spectrometry (SIMS) using accelerators has been applied with success to cosmic ray exposure ages and terrestrial residence times of meteorites by measuring cosmogenic nuclides of Be, Cl, and I. It is proposed to complement this work with experiments on rare stable isotopes, in the hope of setting constraints on the processes of solar nebula/meteoritic formation. The relevant species can be classified as: a) daughter products of extinct nuclides (halflife less than or equal to 2 x 10 8 y) -chronology of the early solar system; b) products of high temperature astrophysical processes - different components incorporated into the solar nebula; and c) products of relatively low temperature processes, stellar winds and cosmic ray reactions - early solar system radiation history. The use of micron-scale primary ion beams will allow detailed sampling of phases within meteorites. Strategies of charge-state selection, molecular disintegration and detection should bring a new set of targets within analytical range. The developing accelerator field is compared to existing (keV energy) ion microprobes

  1. Crystal structure and phase transitions of sodium potassium niobate perovskites

    Science.gov (United States)

    Tellier, J.; Malic, B.; Dkhil, B.; Jenko, D.; Cilensek, J.; Kosec, M.

    2009-02-01

    This paper presents the crystal structure and the phase transitions of K xNa 1- xNbO 3 (0.4 ≤ x ≤ 0.6). X-ray diffraction measurements were used to follow the change of the unit-cell parameters and the symmetry in the temperature range 100-800 K. At room temperature all the compositions exhibited a monoclinic metric of the unit cell with a small monoclinic distortion (90.32° ≤ β ≤ 90.34°). No major change of symmetry was evidenced in the investigated compositional range, which should be characteristic of the morphotropic phase-boundary region. With increasing temperature, the samples underwent first-order monoclinic-tetragonal and tetragonal-cubic transitions. Only the potassium-rich phases were rhombohedral at 100 K.

  2. Parameter estimation of stable models and with minimum phase in dynamic aggregation of voltage regulators; Estimacao de parametros de modelos estaveis e de fase minima na agregacao dinamica de reguladores de tensao

    Energy Technology Data Exchange (ETDEWEB)

    Souza, E.J.S. Pires de [Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Eletrica], E-mail: pires@ele.puc-rio.br

    2009-07-01

    The dynamic aggregation of coherent generating unit models has been solved as an unconstrained optimization problem. In this process, negative time constants may be obtained, which characterize unstable or non-minimal phase models. The comparison of the solutions of the dynamic aggregation problem of voltage regulator models obtained with both the original formulation and the squared-variable transformation is the objective of this paper. Initial values are within the range from +100% to -90% in relation to the estimated parameters. The New England system including models of the Brazilian system is considered in the studies. (author)

  3. Effective Liquid-phase Nitration of Benzene Catalyzed by a Stable Solid Acid Catalyst: Silica Supported Cs{sub 2.5}H{sub 0.5}PMo{sub 12}O{sub 40}

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Shu-wen; Liu, Li-jun; Zhang, Qian; Wang, Liang-yin [Liaocheng University, Liaocheng (China)

    2012-04-15

    Silica supported Cs{sub 2.5}H{sub 0.5}PMo{sub 12}O{sub 40} catalyst was prepared through sol-gel method with ethyl silicate-40 as silicon resource and characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, nitrogen adsorption-desorption and potentiometric titration methods. The Cs{sub 2.5}H{sub 0.5}PMo{sub 12}O{sub 40} particles with Keggin-type structure well dispersed on the surface of silica, and the catalyst exhibited high surface area and acidity. The catalytic performance of the catalysts for benzene liquid-phase nitration was examined with 65% nitric acid as nitrating agent, and the effects of various parameters were tested, which including temperature, time and amount of catalyst, reactants ratio, especially the recycle of catalyst was emphasized. Benzene was effectively nitrated to mononitro-benzene with high conversion (95%) in optimized conditions. Most importantly, the supported catalyst was proved has excellent stability in the nitration progress, and there were no any other organic solvent and sulfuric acid were used in the reaction system, so the liquid-phase nitration of benzene that we developed was an eco-friendly and attractive alternative for the commercial technology

  4. β-Rhombohedral Boron: At the Crossroads of the Chemistry of Boron and the Physics of Frustration [Boron: a frustrated element

    Energy Technology Data Exchange (ETDEWEB)

    Ogitsu, Tadashi [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Schwegler, Eric [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Galli, Giulia [Univ. of California, Davis, CA (United States)

    2013-05-08

    In the periodic table boron occupies a peculiar, crossover position: on the first row, it is surrounded by metal forming elements on the left and by non-metals on the right. In addition, it is the only non-metal of the third column. Therefore it is perhaps not surprising that the crystallographic structure and topology of its stable allotrope at room temperature (β-boron) are not shared by any other element, and are extremely complex. The formidable intricacy of β- boron, with interconnecting icosahedra, partially occupied sites, and an unusually large number of atoms per unit cell (more than 300) has been known for more than 40 years. Nevertheless boron remains the only element purified in significant quantities whose ground state geometry has not been completely determined by experiments. However theoretical progress reported in the last decade has shed light on numerous properties of elemental boron, leading to a thorough characterization of its structure at ambient conditions, as well as of its electronic and thermodynamic properties. This review discusses in detail the properties of β-boron, as inferred from experiments and the ab-initio theories developed in the last decade.

  5. Releasing metal catalysts via phase transition: (NiO)0.05-(SrTi0.8Nb0.2O3)0.95 as a redox stable anode material for solid oxide fuel cells.

    Science.gov (United States)

    Xiao, Guoliang; Wang, Siwei; Lin, Ye; Zhang, Yanxiang; An, Ke; Chen, Fanglin

    2014-11-26

    Donor-doped perovskite-type SrTiO3 experiences stoichiometric changes at high temperatures in different Po2 involving the formation of Sr or Ti-rich impurities. NiO is incorporated into the stoichiometric strontium titanate, SrTi0.8Nb0.2O3-δ (STN), to form an A-site deficient perovskite material, (NiO)0.05-(SrTi0.8Nb0.2O3)0.95 (Ni-STN), for balancing the phase transition. Metallic Ni nanoparticles can be released upon reduction instead of forming undesired secondary phases. This material design introduces a simple catalytic modification method with good compositional control of the ceramic backbones, by which transport property and durability of solid oxide fuel cell anodes are largely determined. Using Ni-STN as anodes for solid oxide fuel cells, enhanced catalytic activity and remarkable stability in redox cycling have been achieved. Electrolyte-supported cells with the cell configuration of Ni-STN-SDC anode, La0.8Sr0.2Ga0.87Mg0.13O3 (LSGM) electrolyte, and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) cathode produce peak power densities of 612, 794, and 922 mW cm(-2) at 800, 850, and 900 °C, respectively, using H2 as the fuel and air as the oxidant. Minor degradation in fuel cell performance resulted from redox cycling can be recovered upon operating the fuel cells in H2. Such property makes Ni-STN a promising regenerative anode candidate for solid oxide fuel cells.

  6. One-dimensional stable distributions

    CERN Document Server

    Zolotarev, V M

    1986-01-01

    This is the first book specifically devoted to a systematic exposition of the essential facts known about the properties of stable distributions. In addition to its main focus on the analytic properties of stable laws, the book also includes examples of the occurrence of stable distributions in applied problems and a chapter on the problem of statistical estimation of the parameters determining stable laws. A valuable feature of the book is the author's use of several formally different ways of expressing characteristic functions corresponding to these laws.

  7. Superior Properties of Energetically Stable La2/3Sr1/3MnO3/Tetragonal BiFeO3 Multiferroic Superlattices

    KAUST Repository

    Feng, Nan; Mi, Wenbo; Wang, Xiaocha; Cheng, Yingchun; Schwingenschlö gl, Udo

    2015-01-01

    The superlattice of energetically stable La2/3Sr1/3MnO3 and tetragonal BiFeO3 is investigated by means of density functional theory. The superlattice as a whole exhibits a half-metallic character, as is desired for spintronic devices. The interfacial electronic states and exchange coupling are analyzed in details. We demonstrate that the interfacial O atoms play a key role in controlling the coupling. The higher ferroelectricity of tetragonal BiFeO3 and stronger response to the magnetic moment in La2/3Sr1/3MnO3/BiFeO3 superlattice show a strongly enhanced electric control of the magnetism as compared to the rhombohedral one. Therefore, it is particularly practical interest in the magnetoelectric controlled spintronic devices.

  8. Superior Properties of Energetically Stable La2/3Sr1/3MnO3/Tetragonal BiFeO3 Multiferroic Superlattices

    KAUST Repository

    Feng, Nan

    2015-04-30

    The superlattice of energetically stable La2/3Sr1/3MnO3 and tetragonal BiFeO3 is investigated by means of density functional theory. The superlattice as a whole exhibits a half-metallic character, as is desired for spintronic devices. The interfacial electronic states and exchange coupling are analyzed in details. We demonstrate that the interfacial O atoms play a key role in controlling the coupling. The higher ferroelectricity of tetragonal BiFeO3 and stronger response to the magnetic moment in La2/3Sr1/3MnO3/BiFeO3 superlattice show a strongly enhanced electric control of the magnetism as compared to the rhombohedral one. Therefore, it is particularly practical interest in the magnetoelectric controlled spintronic devices.

  9. Stable dark energy stars

    International Nuclear Information System (INIS)

    Lobo, Francisco S N

    2006-01-01

    The gravastar picture is an alternative model to the concept of a black hole, where there is an effective phase transition at or near where the event horizon is expected to form, and the interior is replaced by a de Sitter condensate. In this work a generalization of the gravastar picture is explored by considering matching of an interior solution governed by the dark energy equation of state, ω ≡ p/ρ < -1/3, to an exterior Schwarzschild vacuum solution at a junction interface. The motivation for implementing this generalization arises from the fact that recent observations have confirmed an accelerated cosmic expansion, for which dark energy is a possible candidate. Several relativistic dark energy stellar configurations are analysed by imposing specific choices for the mass function. The first case considered is that of a constant energy density, and the second choice that of a monotonic decreasing energy density in the star's interior. The dynamical stability of the transition layer of these dark energy stars to linearized spherically symmetric radial perturbations about static equilibrium solutions is also explored. It is found that large stability regions exist that are sufficiently close to where the event horizon is expected to form, so that it would be difficult to distinguish the exterior geometry of the dark energy stars, analysed in this work, from an astrophysical black hole

  10. Hexagonal perovskites with cationic vacancies. 5. Structure determination on H-Ba/sub 2/Lusub(2/3)vacantsub(1/3)WO/sub 6/ - a novel rhombohedral stacking polytype with 18 layers

    Energy Technology Data Exchange (ETDEWEB)

    Wischert, W; Schittenhelm, H J; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Inst. fuer Chemie

    1979-01-01

    Compounds of type Ba/sub 2/Bsub(2/3)sup(III)vacantsub(1/3)Wsup(VI)O/sub 6/ with Bsup(III) = Gd-Lu, Y are polymorphic. They crystallize in a cubic 1:1 ordered perovskite structure and in a new rhombohedral perovskite stacking polytype of 18 L respectively. By intensity calculations out of the three possible stacking sequences (4)(2), (5)(1) and (3)1(1)1 (all space group R3m) the sequence (5)(1) can be selected. For H-Ba/sub 2/Lusub(2/3)vacant sub(1/3)WO/sub 6/ the refined R' factor is 14.1%. The structure contains groups of three octahedra connected with another by common faces which are linked with each other by three corner sharing octahedra. In the block of three face sharing octahedra the central octahedral lattice site is vacant, the two outer positions are occupied by tungsten atoms. According to this distribution a direct contact of occupied face sharing octahedra is absent.

  11. Hexagonal perovskites with cationic vacancies. 17. Structure determination on Ba/sub 9/Nb/sub 6/Wvacant/sub 2/O/sub 27/ - the first stacking polytype of a rhombohedral 27 L-type

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S; Treiber, U [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1980-03-01

    The hexagonal stacking polytype of rhombohedral 27 L-type, Ba/sub 9/Nb/sub 6/Wvacant/sub 2/O/sub 27/, crystallizes in the space group R3m with the sequence (4)1(3)1 = (hhccchhcc)/sub 3/ and three formula units for the trigonal setting. The refined, intensity, related, R'-value is 9.7%. The octahedral net consists of blocks of three face connected octahedra which are linked to each other alternately through one or two octahedra connected exclusively by common vertices. The cationic vacancies are located in the centers of the groups of three octahedra. With this distribution direct contact between occupied face-sharing octahedra is avoided. The niobium and tungsten atoms are distributed statistically between the remaining octahedral holes. In the blocks of three octahedra they are displaced by approximately 0.29 A from their ideal positions in the direction of the central void. The Ba atoms neighbouring a vacancy (all in hexagonal packed BaO/sub 3/ sheets) are dislocated in the direction of the void, while the cubic packed BaO/sub 3/ sheets maintain nearly regular form.

  12. Phase space investigation of the lithium amide halides

    Energy Technology Data Exchange (ETDEWEB)

    Davies, Rosalind A. [Hydrogen Storage Chemistry Group, School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Hydrogen and Fuel Cell Group, School of Chemical Engineering, University of Birmingham, Edgbaston B15 2TT (United Kingdom); Hewett, David R.; Korkiakoski, Emma [Hydrogen Storage Chemistry Group, School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Thompson, Stephen P. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (United Kingdom); Anderson, Paul A., E-mail: p.a.anderson@bham.ac.uk [Hydrogen Storage Chemistry Group, School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2015-10-05

    Highlights: • The lower limits of halide incorporation in lithium amide have been investigated. • The only amide iodide stoichiometry observed was Li{sub 3}(NH{sub 2}){sub 2}I. • Solid solutions were observed in both the amide chloride and amide bromide systems. • A 46% reduction in chloride content resulted in a new phase: Li{sub 7}(NH{sub 2}){sub 6}Cl. • New low-chloride phase maintained improved H{sub 2} desorption properties of Li{sub 4}(NH{sub 2}){sub 3}Cl. - Abstract: An investigation has been carried out into the lower limits of halide incorporation in lithium amide (LiNH{sub 2}). It was found that the lithium amide iodide Li{sub 3}(NH{sub 2}){sub 2}I was unable to accommodate any variation in stoichiometry. In contrast, some variation in stoichiometry was accommodated in Li{sub 7}(NH{sub 2}){sub 6}Br, as shown by a decrease in unit cell volume when the bromide content was reduced. The amide chloride Li{sub 4}(NH{sub 2}){sub 3}Cl was found to adopt either a rhombohedral or a cubic structure depending on the reaction conditions. Reduction in chloride content generally resulted in a mixture of phases, but a new rhombohedral phase with the stoichiometry Li{sub 7}(NH{sub 2}){sub 6}Cl was observed. In comparison to LiNH{sub 2}, this new low-chloride phase exhibited similar improved hydrogen desorption properties as Li{sub 4}(NH{sub 2}){sub 3}Cl but with a much reduced weight penalty through addition of chloride. Attempts to dope lithium amide with fluoride ions have so far proved unsuccessful.

  13. Stable isotope research pool inventory

    International Nuclear Information System (INIS)

    1980-12-01

    This report contains a listing of electromagnetically separated stable isotopes which are available for distribution within the United States for non-destructive research use from the Oak Ridge National Laboratory on a loan basis. This inventory includes all samples of stable isotopes in the Materials Research Collection and does not designate whether a sample is out on loan or in reprocessing

  14. Stable carbides in transition metal alloys

    International Nuclear Information System (INIS)

    Piotrkowski, R.

    1991-01-01

    In the present work different techniques were employed for the identification of stable carbides in two sets of transition metal alloys of wide technological application: a set of three high alloy M2 type steels in which W and/or Mo were total or partially replaced by Nb, and a Zr-2.5 Nb alloy. The M2 steel is a high speed steel worldwide used and the Zr-2.5 Nb alloy is the base material for the pressure tubes in the CANDU type nuclear reactors. The stability of carbide was studied in the frame of Goldschmidt's theory of interstitial alloys. The identification of stable carbides in steels was performed by determining their metallic composition with an energy analyzer attached to the scanning electron microscope (SEM). By these means typical carbides of the M2 steel, MC and M 6 C, were found. Moreover, the spatial and size distribution of carbide particles were determined after different heat treatments, and both microstructure and microhardness were correlated with the appearance of the secondary hardening phenomenon. In the Zr-Nb alloy a study of the α and β phases present after different heat treatments was performed with optical and SEM metallographic techniques, with the guide of Abriata and Bolcich phase diagram. The α-β interphase boundaries were characterized as short circuits for diffusion with radiotracer techniques and applying Fisher-Bondy-Martin model. The precipitation of carbides was promoted by heat treatments that produced first the C diffusion into the samples at high temperatures (β phase), and then the precipitation of carbide particles at lower temperature (α phase or (α+β)) two phase field. The precipitated carbides were identified as (Zr, Nb)C 1-x with SEM, electron microprobe and X-ray diffraction techniques. (Author) [es

  15. Integrated experimental and computational methods for structure determination and characterization of a new, highly stable cesium silicotitanate phase, Cs2TiSi6O15 (SNL-A)

    International Nuclear Information System (INIS)

    Nyman D, May; Bonhomme R, Francois; Teter M, David; Maxwell, R.S.; Gu, B.X.; Wang, L.M.; Ewing, R.C.; Nenoff M, Tina

    2000-01-01

    Exploratory hydrothermal synthesis in the system Cs 2 O-SiO 2 -TiO 2 -H 2 O has produced a new polymorph of Cs 2 TiSi 6 O 15 (SNL-A) whose structure was determined using a combination of experimental and theoretical techniques ( 29 Si and 133 Cs NMR, X-ray Rietveld refinement, and Density Functional Theory). SNL-A crystallizes in the monoclinic space-group Cc with unit cell parameters: a = 12.998(2) angstrom, b = 7.5014(3) angstrom, c = 15.156(3) angstrom, η = 105.80(3) degree. The SNL-A framework consists of silicon tetrahedra and titanium octahedra which are linked in 3-, 5-, 6-, 7- and 8-membered rings in three dimensions. SNL-A is distinctive from a previously reported C2/c polymorph of Cs 2 TiSi 6 O 15 by different ring geometries. Similarities and differences between the two structures are discussed. Other characterizations of SNL-A include TGA-DTA, Cs/Si/Ti elemental analyses, and SEM/EDS. Furthermore, the chemical and radiation durability of SNL-A was studied in interest of ceramic waste form applications. These studies show that SNL-A is durable in both radioactive and rigorous chemical environments. Finally, calculated cohesive energies of the two Cs 2 TiSi 6 O 15 polymorphs suggest that the SNL-A phase (synthesized at 200 C) is energetically more favorable than the C2/c polymorph (synthesized at 1,050 C)

  16. A phase 1 study of a group B meningococcal native outer membrane vesicle vaccine made from a strain with deleted lpxL2 and synX and stable expression of opcA.

    Science.gov (United States)

    Keiser, Paul B; Gibbs, Barnett T; Coster, Trinka S; Moran, E Ellen; Stoddard, Mark B; Labrie, Joseph E; Schmiel, Deborah H; Pinto, Valerian; Chen, Ping; Zollinger, Wendell D

    2010-10-08

    This phase 1 clinical trial assessed the safety and immunogenicity of a native outer membrane vesicle (NOMV) vaccine prepared from a lpxL2(-) synX(-) mutant of strain 44/76 with opcA expression stabilized. Thirty-four volunteers were assigned to one of the three dose groups (25 mcg, 25 mcg with aluminum hydroxide adjuvant, and 50 mcg) to receive three intramuscular injections at 0, 6 and 24 weeks. Specific local and systemic adverse events (AEs) were solicited by diary and at visits on days 1, 2, 7 and 14 after each vaccination and at the end of the study at 30 weeks. Blood chemistries, complete blood count, and coagulation studies were measured on each vaccination day and again two days later. Blood for antibody measurements and bactericidal assays were drawn 0, 14, and 42 days after each vaccination. The proportion of volunteers who developed a fourfold or greater increase in serum bactericidal activity (SBA) to the wild-type parent of the vaccine strain with high opcA expression at 6 weeks after the third dose was 12/26 (0.46, 95% confidence interval 0.27-0.65). Antibody levels to OpcA were significantly higher in vaccine responders than in non-responders (p=0.008), and there was a trend for higher antibody levels to the lipooligosaccharide (LOS) (p=0.059). Bactericidal depletion assays on sera from volunteers with high-titer responses also indicate a major contribution of anti-OpcA and anti-LOS antibodies to the bactericidal response.These results suggest that genetically modified NOMV vaccines can induce protection against group B meningococcus. Copyright © 2010 Elsevier Ltd. All rights reserved.

  17. Stabilized antiferroelectric phase in lanthanum-doped (Na1/2Bi1/2)TiO3

    Science.gov (United States)

    Yi, Jae Yun; Lee, Jung-Kun

    2011-10-01

    Phase transition behaviour of La-modified sodium bismuth titanate ceramics [(Na0.5Bi0.5)1-1.5xV0.5xLax]TiO3 (NBLT) was investigated. The two anomalies in ɛr(T) and DSC analysis indicated that lower temperature phase transitions below 200 °C became pronounced with La additions. The polarization relaxation of ɛr(T) and double hysteresis loops showed that the intermediate region between two dielectric anomalies was the antiferroelectric modulated phase. The origin of the modulated antiferroelectric state was discussed in terms of disordering effects of the La ions and cation vacancies. With increasing La content, the long-range symmetry of the dipoles in the ferroelectric phase was disturbed in the intermediate region. The competition between rhombohedral ferroelectric phase and tetragonal paraelectric phase contributed to the formation of a modulated antiferroelectric phase in NBLT ceramics.

  18. Stabilized antiferroelectric phase in lanthanum-doped (Na1/2Bi1/2)TiO3

    International Nuclear Information System (INIS)

    Yi, Jae Yun; Lee, Jung-Kun

    2011-01-01

    Phase transition behaviour of La-modified sodium bismuth titanate ceramics [(Na 0.5 Bi 0.5 ) 1-1.5x V 0.5x La x ]TiO 3 (NBLT) was investigated. The two anomalies in ε r (T) and DSC analysis indicated that lower temperature phase transitions below 200 deg. C became pronounced with La additions. The polarization relaxation of ε r (T) and double hysteresis loops showed that the intermediate region between two dielectric anomalies was the antiferroelectric modulated phase. The origin of the modulated antiferroelectric state was discussed in terms of disordering effects of the La ions and cation vacancies. With increasing La content, the long-range symmetry of the dipoles in the ferroelectric phase was disturbed in the intermediate region. The competition between rhombohedral ferroelectric phase and tetragonal paraelectric phase contributed to the formation of a modulated antiferroelectric phase in NBLT ceramics.

  19. Structure and phase transition of BiFeO{sub 3} cubic micro-particles prepared by hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Jian-Ping, E-mail: zhoujp@snnu.edu.cn [College of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062 (China); Yang, Ruo-Lin; Xiao, Rui-Juan; Chen, Xiao-Ming [College of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062 (China); Deng, Chao-Yong [Department of Electronic Science, Guizhou University, Guizhou Guiyang 550025 (China)

    2012-11-15

    Graphical abstract: Bismuth ferrite (BiFeO{sub 3}) cubic micro-particles with smooth surfaces were synthesized. BiFeO{sub 3} has a hexagonal perovskite structure with a space group R3c below 370 °C and rhombohedral perovskite structure with a space group R3m below 755 °C, undergoes a phase transition in the temperature range of 755–817 °C to a cubic structure, then decompose to liquid and Fe{sub 2}O{sub 3} above 939 °C. Highlights: ► BiFeO{sub 3} micro-particles with smooth surface were synthesized by hydrothermal method. ► BiFeO{sub 3} enjoys hexagonal structure with well element ratio and chemical valence. ► BiFeO{sub 3} transition from rhombohedral phase to cubic phase lasts 60 °C. -- Abstract: Single-phase bismuth ferrite (BiFeO{sub 3}) powders were synthesized with a hydrothermal method by controlling the experimental conditions carefully. The powder structure, morphology and composition were characterized by using X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscope, Raman measurement and X-ray photoelectron spectroscopy. The particles change from irregular agglomerations to regular cubes with increasing KOH concentration. The large BiFeO{sub 3} cubic particles enjoy much smooth surfaces with well-matched element ratio (Bi:Fe:O = 1:1:3) and chemical valence (Bi{sup 3+}, Fe{sup 3+} and O{sup 2−}). The high temperature XRD and differential scanning calorimetry show that BiFeO{sub 3} powders have a hexagonal perovskite structure with a space group R3c below 370 °C and a rhombohedral structure with a space group R3m below 755 °C. BiFeO{sub 3} undergoes a phase transition in the temperature range of 755–817 °C from rhombohedral structure to a cubic phase, then decomposes to liquid and Fe{sub 2}O{sub 3} above 939 °C.

  20. Structure and phase transition of BiFeO3 cubic micro-particles prepared by hydrothermal method

    International Nuclear Information System (INIS)

    Zhou, Jian-Ping; Yang, Ruo-Lin; Xiao, Rui-Juan; Chen, Xiao-Ming; Deng, Chao-Yong

    2012-01-01

    Graphical abstract: Bismuth ferrite (BiFeO 3 ) cubic micro-particles with smooth surfaces were synthesized. BiFeO 3 has a hexagonal perovskite structure with a space group R3c below 370 °C and rhombohedral perovskite structure with a space group R3m below 755 °C, undergoes a phase transition in the temperature range of 755–817 °C to a cubic structure, then decompose to liquid and Fe 2 O 3 above 939 °C. Highlights: ► BiFeO 3 micro-particles with smooth surface were synthesized by hydrothermal method. ► BiFeO 3 enjoys hexagonal structure with well element ratio and chemical valence. ► BiFeO 3 transition from rhombohedral phase to cubic phase lasts 60 °C. -- Abstract: Single-phase bismuth ferrite (BiFeO 3 ) powders were synthesized with a hydrothermal method by controlling the experimental conditions carefully. The powder structure, morphology and composition were characterized by using X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscope, Raman measurement and X-ray photoelectron spectroscopy. The particles change from irregular agglomerations to regular cubes with increasing KOH concentration. The large BiFeO 3 cubic particles enjoy much smooth surfaces with well-matched element ratio (Bi:Fe:O = 1:1:3) and chemical valence (Bi 3+ , Fe 3+ and O 2− ). The high temperature XRD and differential scanning calorimetry show that BiFeO 3 powders have a hexagonal perovskite structure with a space group R3c below 370 °C and a rhombohedral structure with a space group R3m below 755 °C. BiFeO 3 undergoes a phase transition in the temperature range of 755–817 °C from rhombohedral structure to a cubic phase, then decomposes to liquid and Fe 2 O 3 above 939 °C.

  1. Stable configurations in social networks

    Science.gov (United States)

    Bronski, Jared C.; DeVille, Lee; Ferguson, Timothy; Livesay, Michael

    2018-06-01

    We present and analyze a model of opinion formation on an arbitrary network whose dynamics comes from a global energy function. We study the global and local minimizers of this energy, which we call stable opinion configurations, and describe the global minimizers under certain assumptions on the friendship graph. We show a surprising result that the number of stable configurations is not necessarily monotone in the strength of connection in the social network, i.e. the model sometimes supports more stable configurations when the interpersonal connections are made stronger.

  2. Development of Stable Isotope Technology

    International Nuclear Information System (INIS)

    Jeong, Do Young; Kim, Cheol Jung; Han, Jae Min

    2009-03-01

    KAERI has obtained an advanced technology with singular originality for laser stable isotope separation. Objectives for this project are to get production technology of Tl-203 stable isotope used for medical application and are to establish the foundation of the pilot system, while we are taking aim at 'Laser Isotope Separation Technology to make resistance to the nuclear proliferation'. And we will contribute to ensuring a nuclear transparency in the world society by taking part in a practical group of NSG and being collaboration with various international groups related to stable isotope separation technology

  3. Phase stability, mechanical properties, hardness, and possible reactive routing of chromium triboride from first-principle investigations

    International Nuclear Information System (INIS)

    Zhong, Ming-Min; Kuang, Xiao-Yu; Wang, Zhen-Hua; Shao, Peng; Ding, Li-Ping; Huang, Xiao-Fen

    2013-01-01

    The first-principles calculations are employed to provide a fundamental understanding of the structural features and relative stability, mechanical and electronic properties, and possible reactive route for chromium triboride. The predicted new phase of CrB 3 belongs to the rhombohedral phase with R-3m symmetry and it transforms into a hexagonal phase with P-6m2 symmetry at 64 GPa. The mechanical and thermodynamic stabilities of CrB 3 are verified by the calculated elastic constants and formation enthalpies. Also, the full phonon dispersion calculations confirm the dynamic stability of predicted CrB 3 . Considering the role of metallic contributions, the calculated hardness values from our semiempirical method for rhombohedral and hexagonal phases are 23.8 GPa and 22.1 GPa, respectively. In addition, the large shear moduli, Young's moduli, low Poisson's ratios, and small B/G ratios indicate that they are potential hard materials. Relative enthalpy calculations with respect to possible constituents are also investigated to assess the prospects for phase formation and an attempt at high-pressure synthesis is suggested to obtain chromium triboride

  4. Stable isotope research pool inventory

    International Nuclear Information System (INIS)

    1984-03-01

    This report contains a listing of electromagnetically separated stable isotopes which are available at the Oak Ridge National Laboratory for distribution for nondestructive research use on a loan basis. This inventory includes all samples of stable isotopes in the Research Materials Collection and does not designate whether a sample is out on loan or is in reprocessing. For some of the high abundance naturally occurring isotopes, larger amounts can be made available; for example, Ca-40 and Fe-56

  5. French days on stable isotopes

    International Nuclear Information System (INIS)

    2000-01-01

    These first French days on stable isotopes took place in parallel with the 1. French days of environmental chemistry. Both conferences had common plenary sessions. The conference covers all aspects of the use of stable isotopes in the following domains: medicine, biology, environment, tracer techniques, agronomy, food industry, geology, petroleum geochemistry, cosmo-geochemistry, archaeology, bio-geochemistry, hydrology, climatology, nuclear and particle physics, astrophysics, isotope separations etc.. Abstracts available on CD-Rom only. (J.S.)

  6. Stable isotope research pool inventory

    International Nuclear Information System (INIS)

    1982-01-01

    This report contains a listing of electromagnetically separated stable isotopes which are available for distribution within the United States for nondestructive research use from the Oak Ridge National Laboratory on a loan basis. This inventory includes all samples of stable isotopes in the Material Research Collection and does not designate whether a sample is out on loan or in reprocessing. For some of the high abundance naturally occurring isotopes, larger amounts can be made available; for example, Ca-40 and Fe-56

  7. Pharmaceuticals labelled with stable isotopes

    International Nuclear Information System (INIS)

    Krumbiegel, P.

    1986-11-01

    The relatively new field of pharmaceuticals labelled with stable isotopes is reviewed. Scientific, juridical, and ethical questions are discussed concerning the application of these pharmaceuticals in human medicine. 13 C, 15 N, and 2 H are the stable isotopes mainly utilized in metabolic function tests. Methodical contributions are given to the application of 2 H, 13 C, and 15 N pharmaceuticals showing new aspects and different states of development in the field under discussion. (author)

  8. X-Ray diffraction on rare earth-3d Laves phase compound ErCo2 in magnetic field

    International Nuclear Information System (INIS)

    Yagasaki, Katsuma; Notsu, Shiko; Takaesu, Yoshinao; Nakama, Takao; Sakai, Eijiro; Koyama, Keiichi; Watanabe, Kazuo; Burkov, Alexander T.

    2006-01-01

    X-Ray powder diffraction method is used to investigate the effect of magnetic ordering and external magnetic field on crystal structure of Laves phase intermetallic compound ErCo 2 . The diffraction patterns were recorded at temperatures from 300K down to 8.5K in magnetic field up to 5T. Distortion of the room-temperature cubic structure was found in magnetically ordered state below 32K. The symmetry at low temperature is rhombohedral in agreement with literature results, or lower symmetry than it. However the symmetry of the unit cell increases to cubic in external magnetic field of 5T

  9. Unconditionally Stable Low Dropout Regulators for Extreme Environments, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — We have developed a low dropout (LDO) regulator using a patented MESFET transistor technology that can be manufactured in commercial CMOS foundries with no changes...

  10. Efficient Thermally Stable Spectral Control Filters for Thermophotovoltaics, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The feasibility of radioisotope thermophotovoltaic (RTPV) power systems has been shown. The best efficiencies reported to date for a TPV module test include front...

  11. Oxidatively Stable Flexible Aerogel Composites for Reusable TPS, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA?s Next Generation Launch Vehicle Technology Program has an interest in robust TPS materials with the highest level of thermal performance at the lowest possible...

  12. Highly Stable, Large Format EUV Imager, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Higher detection efficiency and better radiation tolerance imagers are needed for the next generation of EUV instruments. Previously, CCD technology has demonstrated...

  13. Additively Manufactured, Thermally Stable Telescope Mirror Substrates, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is to demonstrate the feasibility of using selective laser melting (SLM) to develop the material composition and the additive manufacturing fabrication...

  14. Preparation of thermally stable nanocrystalline hydroxyapatite by hydrothermal method.

    Science.gov (United States)

    Prakash Parthiban, S; Elayaraja, K; Girija, E K; Yokogawa, Y; Kesavamoorthy, R; Palanichamy, M; Asokan, K; Narayana Kalkura, S

    2009-12-01

    Thermally stable hydroxyapatite (HAp) was synthesized by hydrothermal method in the presence of malic acid. X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), differential thermal analysis (DTA), thermogravimetric analysis (TGA) was done on the synthesized powders. These analyses confirmed the sample to be free from impurities and other phases of calcium phosphates, and were of rhombus morphology along with nanosized particles. IR and Raman analyses indicated the adsorption of malic acid on HAp. Thermal stability of the synthesized HAp was confirmed by DTA and TGA. The synthesized powders were thermally stable upto 1,400 degrees C and showed no phase change. The proposed method might be useful for producing thermally stable HAp which is a necessity for high temperature coating applications.

  15. Evolution from successive phase transitions to "morphotropic phase boundary" in BaTiO3-based ferroelectrics

    Science.gov (United States)

    Zhou, Chao; Ke, Xiaoqin; Yao, Yonggang; Yang, Sen; Ji, Yuanchao; Liu, Wenfeng; Yang, Yaodong; Zhang, Lixue; Hao, Yanshuang; Ren, Shuai; Zhang, Le; Ren, Xiaobing

    2018-04-01

    Obtaining superior physical properties for ferroic materials by manipulating the phase transitions is a key concern in solid state physics. Here, we investigated the dielectric permittivity, piezoelectric coefficient d33, storage modulus, and crystal symmetry of (1-x)Ba(Ti0.8Zr0.2)O3-x(Ba1-yCay)TiO3 (BZT-xBCyT) systems to demonstrate the gradual evolution process from successive phase transitions in BaTiO3 to the morphotropic phase boundary (MPB) regime in BZT-xBC0.3T. Furthermore, we analysed with a Landau-type theoretical model to show that the high field-sensitive response (dielectric permittivity) originates from a small polarization anisotropy and low energy barrier at the quadruple point. Together, the intermediate orthorhombic phase regime and the tetragonal-orthorhombic and orthorhombic-rhombohedral phase boundaries constitute the MPB. Our work not only reconciles the arguments regarding whether the structural state around the MPB corresponds to a single-phase regime or a multiple-phase-coexistence regime but also suggests an effective method to design high-performance functional ferroic materials by tailoring the successive phase transitions.

  16. [Current Treatment of Stable Angina].

    Science.gov (United States)

    Toggweiler, Stefan; Jamshidi, Peiman; Cuculi, Florim

    2015-06-17

    Current therapy for stable angina includes surgical and percutaneous revascularization, which has been improved tremendously over the last decades. Smoking cessation and regular exercise are the cornerstone for prevention of further cerebrovascular events. Medical treatment includes treatment of cardiovascular risk factors and antithrombotic management, which can be a challenge in some patients. Owing to the fact the coronary revascularization is readily accessible these days in many industrialized countries, the importance of antianginal therapy has decreased over the past years. This article presents a contemporary overview of the management of patients with stable angina in the year 2015.

  17. Pyroelectric Charge Release in Rhombohedral PZT

    NARCIS (Netherlands)

    Noheda, Beatriz; Duan, Ning; Cereceda, Noé; Gonzalo, Julio A.

    1998-01-01

    A new experimental set-up controlled by computer has been made to measure the pyroelectric charge of ferroelectric materials with a relatively high conductivity at slow rates of temperature variation. It allowed us to obtain the polarisation vs. temperature behaviour of PZT with various compositions

  18. Radiation-stable polyolefin compositions

    International Nuclear Information System (INIS)

    Rekers, J.W.

    1986-01-01

    This invention relates to compositions of olefinic polymers suitable for high energy radiation treatment. In particular, the invention relates to olefinic polymer compositions that are stable to sterilizing dosages of high energy radiation such as a gamma radiation. Stabilizers are described that include benzhydrol and benzhydrol derivatives; these stabilizers may be used alone or in combination with secondary antioxidants or synergists

  19. Bounded excursion stable gravastars and black holes

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, P [Instituto de Fisica, Universidade Federal Fluminense, Avenida Litoranea, s/n, Boa Viagem 24210-340, Niteroi, RJ (Brazil); Miguelote, A Y; Chan, R [Coordenacao de Astronomia e Astrofisica, Observatorio Nacional, Rua General Jose Cristino, 77, Sao Cristovao 20921-400, Rio de Janeiro, RJ (Brazil); Da Silva, M F; Wang, Anzhong [Departamento de Fisica Teorica, Instituto de Fisica, Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier 524, Maracana 20550-900, Rio de Janeiro-RJ (Brazil); Santos, N O, E-mail: pedrosennarocha@gmail.com, E-mail: yasuda@on.br, E-mail: chan@on.br, E-mail: mfasnic@gmail.com, E-mail: N.O.Santos@qmul.ac.uk, E-mail: anzhong_wang@baylor.edu [LERMA/CNRS-FRE 2460, Universite Pierre et Marie Curie, ERGA, Boite 142, 4 Place Jussieu, 75005 Paris Cedex 05 (France)

    2008-06-15

    Dynamical models of prototype gravastars were constructed in order to study their stability. The models are the Visser-Wiltshire three-layer gravastars, in which an infinitely thin spherical shell of stiff fluid divides the whole spacetime into two regions, where the internal region is de Sitter, and the external one is Schwarzschild. It is found that in some cases the models represent the 'bounded excursion' stable gravastars, where the thin shell is oscillating between two finite radii, while in other cases they collapse until the formation of black holes occurs. In the phase space, the region for the 'bounded excursion' gravastars is very small in comparison to that of black holes, but not empty. Therefore, although the possibility of the existence of gravastars cannot be excluded from such dynamical models, our results indicate that, even if gravastars do indeed exist, that does not exclude the possibility of the existence of black holes.

  20. On the study of the solid-solid phase transformation of TlBiTe2

    International Nuclear Information System (INIS)

    Chrissafis, K.; Vinga, E.S.; Paraskevopoulos, K.M.; Polychroniadis, E.K.

    2003-01-01

    The narrow gap semiconductor TlBiTe 2 undergoes a solid-solid phase transformation from the rhombohedral (D 3d ) to the cubic (O h ) phase. The present paper deals with the study of this phase transformation combining the results of Differential Scanning Calorimetry (DSC) and Transmission Electron Microscopy (TEM). It has been found that during heating the transformation is an athermal activated process, which can be described only by a combination of more than one processes while during cooling it exhibits an expectable thermal hysteresis due to the volume difference. The results of the kinetic analysis combined with the electron microscopy findings, supported also by the Fourier Transform Infrared (FTIR) spectroscopy ones, lead to the conclusion that TlBiTe 2 undergoes a multiple-step, displacive, martensitic type transformation. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  1. Influence of additives on phase stabilization of scandia-doped zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Muccillo, Eliana Navarro dos Santos; Grosso, Robson Lopes; Reis, Shirley Leite dos; Muccillo, Reginaldo, E-mail: enavarro@usp.br, E-mail: roblopeg@usp.br, E-mail: shirley.reis@usp.br, E-mail: muccillo@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2017-04-15

    The effects of small additions of tin, zinc, calcium and boron oxides on phase composition and electrical conductivity of zirconia-10 mol% scandia were investigated. Compounds containing 1 mol% zinc, tin and calcium oxides and 1, 3 and 5 wt.% boron oxide were prepared by solid state reaction and characterized by X-ray diffraction, density measurements, scanning electron microscopy and impedance spectroscopy. Full stabilization of the cubic structure at room temperature was obtained with additions of 1 mol% calcium oxide and 2 wt.% boron oxide. Partially stabilized compounds exhibit herringbone structure, characteristic of the β- rhombohedric phase. Specimens with calcium as additive show total conductivity of 23.8 mS.cm{sup -1} at 750 deg C with activation energy of 1.13 eV. Liquid phase sintering by boron oxide addition is effective to enhance the densification of the solid electrolyte. (author)

  2. High pressure studies of YMn{sub 2} Laves phase and its deuterides

    Energy Technology Data Exchange (ETDEWEB)

    Sugiura, H.; Paul-Boncour, V.; Percheron-Guegan, A.; Marchuk, I.; Hirata, T.; Filipek, S.M.; Dorogova, M

    2004-03-24

    The C15 Laves phase intermetallic YMn{sub 2} and its deuterides containing 1.15, 2, 3.4 and 4 deuterium (D) atoms per formula unit (pfu) (the structure of YMn{sub 2}D{sub 4} is rhombohedral whereas other three deuterides preserve the cubic C15 structure) were compressed up to 31 GPa by using diamond anvil cell (DAC). Parameters of equation of state (EOS) were derived for all phases investigated. The discontinuous change of bulk modulus under high pressure has been revealed for all samples investigated. Two deuterides, YMn{sub 2}D{sub 1.15} and YMn{sub 2}D{sub 2}, decomposed reversibly under pressure into two phases: poor and enriched in deuterium.

  3. High pressure phases of uranium monophosphide studied by synchrotron X-ray diffraction

    International Nuclear Information System (INIS)

    Staun Olson, J.; Gerward, L.; Benedict, U.; Dabos, S.; Vogt, O.

    1988-01-01

    X-ray diffraction studies have been performed on UP powder for pressures up to 51 GPa using synchrotron radiation and a diamond anvil cell. At ambient pressure UP has the rocksalt structure. The bulk modulus has been determined to B 0 = 102(4) GPa and its pressure derivative to B 0 ' = 4.0(8). The cubic phase has been found to transform to a new phase, UP II, at about 10 GPa. UP II can be characterized by a rhombohedral Bravais lattice. UP II transforms to an orthorhombic phase, UP III, at 28 GPa. No volume change has been observed at the two transitions. The influence of the 5f electrons on the transformations is discussed. (orig.)

  4. High-pressure Raman and optical absorption studies on lead pyroniobate (Pb2Nb2O7) and pressure-induced phase transitions

    International Nuclear Information System (INIS)

    Jayaraman, A.; Kourouklis, G.A.; Cooper, A.S.; Espinosa, G.P.

    1990-01-01

    High-pressure Raman scattering and optical absorption studies have been carried out on lead pyroniobate (Pb 2 Nb 2 O 7 ) up to 33 GPa, using a gasketed diamond anvil cell. The Raman study reveals the occurrence of two, possibly three, pressure-induced phase changes; a rather subtle change is indicated near 4.5 GPa. The transition near 13 GPa is attributed to a structural transition from the rhombohedral to the cubic pyrochlore structure. The third phase change occurs near 20 GPa. From the broad Raman feature that is observed at about 800 cm -1 , it is concluded that the system turns amorphous at pressures above 20 GPa. The amorphous phase recrystallizes to the original rhombohedral phase, on release of pressure. The broad Raman peaks of the recrystallized phase indicate a high degree of disorder in the material. Lead pyroniobate turns deep red near 30 GPa, from light yellow at ambient pressure. Semi quantitative absorption measurements show that the energy gap shifts red at a rate of 30 meV/GPa. This shift is attributed to the downward motion of the 5d (es) conduction band of Pb

  5. Toward Practical Secure Stable Matching

    Directory of Open Access Journals (Sweden)

    Riazi M. Sadegh

    2017-01-01

    Full Text Available The Stable Matching (SM algorithm has been deployed in many real-world scenarios including the National Residency Matching Program (NRMP and financial applications such as matching of suppliers and consumers in capital markets. Since these applications typically involve highly sensitive information such as the underlying preference lists, their current implementations rely on trusted third parties. This paper introduces the first provably secure and scalable implementation of SM based on Yao’s garbled circuit protocol and Oblivious RAM (ORAM. Our scheme can securely compute a stable match for 8k pairs four orders of magnitude faster than the previously best known method. We achieve this by introducing a compact and efficient sub-linear size circuit. We even further decrease the computation cost by three orders of magnitude by proposing a novel technique to avoid unnecessary iterations in the SM algorithm. We evaluate our implementation for several problem sizes and plan to publish it as open-source.

  6. Stable isotope research pool inventory

    International Nuclear Information System (INIS)

    1986-08-01

    This report contains a listing of electromagnetically separated stable isotopes which are available at the Oak Ridge National Laboratory for distribution for nondestructive research use on a loan basis. This inventory includes all samples of stable isotopes in the Research Materials Collection and does not designate whether a sample is out on loan or is in reprocessing. For some of the high-abundance, naturally occurring isotopes, larger amounts can be made available; for example, Ca-40 and Fe-56. All requests for the loan of samples should be submitted with a summary of the purpose of the loan to: Iotope Distribution Office, Oak Ridge National Laboratory, P.O. Box X, Oak Ridge, Tennessee 37831. Requests from non-DOE contractors and from foreign institutions require DOE approval

  7. Stable isotopes and the environment

    International Nuclear Information System (INIS)

    Krouse, H.R.

    1990-01-01

    Whereas traditionally, stable isotope research has been directed towards resource exploration and development, it is finding more frequent applications in helping to assess the impacts of resource utilization upon ecosystems. Among the many pursuits, two themes are evident: tracing the transport and conversions of pollutants in the environment and better understanding of the interplay among environmental receptors, e.g. food web studies. Stable isotope data are used primarily to identify the presence of pollutants in the environment and with a few exceptions, the consequence of their presence must be assessed by other techniques. Increasing attention has been given to the isotopic composition of humans with many potential applications in areas such as paleodiets, medicine, and criminology. In this brief overview examples are used from the Pacific Rim to illustrate the above concepts. 26 refs., 1 tab., 3 figs

  8. Stable Structures for Distributed Applications

    OpenAIRE

    Eugen DUMITRASCU; Ion IVAN

    2008-01-01

    For distributed applications, we define the linear, tree and graph structure types with different variants and modalities to aggregate them. The distributed applications have assigned structures that through their characteristics influence the costs of stages for developing cycle and the costs for exploitation, transferred to each user. We also present the quality characteristics of a structure for a stable application, which is focused on stability characteristic. For that characteristic we ...

  9. Medieval Horse Stable; The Results of Multi Proxy Interdisciplinary Research

    Science.gov (United States)

    Dejmal, Miroslav; Lisá, Lenka; Fišáková Nývltová, Miriam; Bajer, Aleš; Petr, Libor; Kočár, Petr; Kočárová, Romana; Nejman, Ladislav; Rybníček, Michal; Sůvová, Zdenka; Culp, Randy; Vavrčík, Hanuš

    2014-01-01

    A multi proxy approach was applied in the reconstruction of the architecture of Medieval horse stable architecture, the maintenance practices associated with that structure as well as horse alimentation at the beginning of 13th century in Central Europe. Finally, an interpretation of the local vegetation structure along Morava River, Czech Republic is presented. The investigated stable experienced two construction phases. The infill was well preserved and its composition reflects maintenance practices. The uppermost part of the infill was composed of fresh stabling, which accumulated within a few months at the end of summer. Horses from different backgrounds were kept in the stable and this is reflected in the results of isotope analyses. Horses were fed meadow grasses as well as woody vegetation, millet, oat, and less commonly hemp, wheat and rye. Three possible explanations of stable usage are suggested. The stable was probably used on a temporary basis for horses of workers employed at the castle, courier horses and horses used in battle. PMID:24670874

  10. Effect of Er{sup 3+} ions on the phase formation and properties of In{sub 2}O{sub 3}nanostructures crystallized upon microwave heating

    Energy Technology Data Exchange (ETDEWEB)

    Lemos, Samantha C.S.; Romeiro, Fernanda C.; Paula, Leonardo F. de [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Gonçalves, Rosana F. [UNIFESP, Universidade Federal de São Paulo, 09972-270 Diadema, SP (Brazil); Moura, Ana P. de [LIEC, Instituto de Química, Universidade Estadual Paulista, 14800-900 Araraquara, SP (Brazil); Ferrer, Mateus M.; Longo, Elson [INCTMN-UFSCar, Universidade Federal de São Carlos, 13565-905 São Carlos, SP (Brazil); Patrocinio, Antonio Otavio T. [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Lima, Renata C., E-mail: rclima@ufu.br [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil)

    2017-05-15

    Regular sized nanostructures of indium oxide (In{sub 2}O{sub 3}) were homogeneously grown using a facile route, i.e. a microwave-hydrothermal method combined with rapid thermal treatment in a microwave oven. The presence of Er{sup 3+} doping plays an important role in controlling the formation of cubic (bcc) and rhombohedral (rh) In{sub 2}O{sub 3} phases. The samples presented broad photoluminescent emission bands in the green-orange region, which were attributed to the recombination of electrons at oxygen vacancies. The photocatalytic activities of pure bcc-In{sub 2}O{sub 3} and a bcc-rh-In{sub 2}O{sub 3} mixture towards the UVA degradation of methylene blue (MB) were also evaluated. The results showed that Er{sup +3} doped In{sub 2}O{sub 3} exhibited the highest photocatalytic activity with a photonic efficiency three times higher than the pure oxide. The improved performance was attributed to the higher surface area, the greater concentration of electron traps due the presence of the dopant and the possible formation of heterojunctions between the cubic and rhombohedral phases. - Graphical abstract: Photodegradation curves as a function of irradiation time of the samples obtained upon rapid microwave heating. - Highlights: • Efficient and rapid microwave heating to obtain Er{sup 3+} doped In{sub 2}O{sub 3} nanostructures. • Er{sup 3+} ions doping is fundamental to stabilizing the crystalline rhombohedral phase. • Symmetry breaking induced by vacancies in the lattice leads to photoluminescence. • Surface area of doped sample was two times higher than the surface of pure oxide. • The presence of defects in the lattice structure favors photocatalytic activity.

  11. Organic synthesis with stable isotopes

    International Nuclear Information System (INIS)

    Daub, G.H.; Kerr, V.N.; Williams, D.L.; Whaley, T.W.

    1978-01-01

    Some general considerations concerning organic synthesis with stable isotopes are presented. Illustrative examples are described and discussed. The examples include DL-2-amino-3-methyl- 13 C-butanoic-3,4- 13 C 2 acid (DL-valine- 13 C 3 ); methyl oleate-1- 13 C; thymine-2,6- 13 C 2 ; 2-aminoethanesulfonic- 13 C acid (taurine- 13 C); D-glucose-6- 13 C; DL-2-amino-3-methylpentanoic-3,4- 13 C 2 acid (DL-isoleucine- 13 C 2 ); benzidine- 15 N 2 ; and 4-ethylsulfonyl-1-naphthalene-sulfonamide- 15 N

  12. Stable isotopes - separation and application

    International Nuclear Information System (INIS)

    Lockhart, I.M.

    1980-01-01

    In this review, methods used for the separation of stable isotopes ( 12 C, 13 C, 14 N, 15 N, 16 O, 17 O, 18 O, 34 S) will be described. The synthesis of labelled compounds, techniques for detection and assay, and areas of application will also be discussed. Particular attention will be paid to the isotopes of carbon, nitrogen, and oxygen; to date, sulphur isotopes have only assumed a minor role. The field of deuterium chemistry is too extensive for adequate treatment; it will therefore be essentially excluded. (author)

  13. Stable agents for imaging investigations

    International Nuclear Information System (INIS)

    Tofe, A.J.

    1976-01-01

    This invention concerns highly stable compounds useful in preparing technetium 99m based scintiscanning exploration agents. The compounds of this invention include a pertechnetate reducing agent or a solution of oxidized pertechnetate and an efficient proportion, sufficient to stabilize the compounds in the presence of oxygen and of radiolysis products, of ascorbic acid or a pharmaceutically acceptable salt or ester of this acid. The invention also concerns a perfected process for preparing a technetium based exploration agent, consisting in codissolving the ascorbic acid or a pharmaceutically acceptable salt or ester of such an acid and a pertechnetate reducing agent in a solution of oxidized pertechnetate [fr

  14. Stable radio frequency dissemination by simple hybrid frequency modulation scheme.

    Science.gov (United States)

    Yu, Longqiang; Wang, Rong; Lu, Lin; Zhu, Yong; Wu, Chuanxin; Zhang, Baofu; Wang, Peizhang

    2014-09-15

    In this Letter, we propose a fiber-based stable radio frequency transfer system by a hybrid frequency modulation scheme. Creatively, two radio frequency signals are combined and simultaneously transferred by only one laser diode. One frequency component is used to detect the phase fluctuation, and the other one is the derivative compensated signal providing a stable frequency for the remote end. A proper ratio of the frequencies of the components is well maintained by parameter m to avoid interference between them. Experimentally, a stable 200 MHz signal is transferred over 100 km optical fiber with the help of a 1 GHz detecting signal, and fractional instability of 2×10(-17) at 10(5) s is achieved.

  15. High precision and stable structures for particle detectors

    CERN Document Server

    Da Mota Silva, S; Hauviller, Claude

    1999-01-01

    The central detectors used in High Energy Physics Experiments require the use of light and stable structures capable of supporting delicate and precise radiation detection elements. These structures need to be highly stable under environmental conditions where external vibrations, high radiation levels, temperature and humidity gradients should be taken into account. Their main design drivers are high dimension and dynamic stability, high stiffness to mass ratio and large radiation length. For most applications, these constraints lead us to choose Carbon Fiber Reinforced Plastics ( CFRP) as structural element. The construction of light and stable structures with CFRP for these applications can be achieved by careful design engineering and further confirmation at the prototyping phase. However, the experimental environment can influence their characteristics and behavior. In this case, theuse of adaptive structures could become a solution for this problem. We are studying structures in CFRP with bonded piezoel...

  16. Leaf water stable isotopes and water transport outside the xylem.

    Science.gov (United States)

    Barbour, M M; Farquhar, G D; Buckley, T N

    2017-06-01

    How water moves through leaves, and where the phase change from liquid to vapour occurs within leaves, remain largely mysterious. Some time ago, we suggested that the stable isotope composition of leaf water may contain information on transport pathways beyond the xylem, through differences in the development of gradients in enrichment within the various pathways. Subsequent testing of this suggestion provided ambiguous results and even questioned the existence of gradients in enrichment within the mesophyll. In this review, we bring together recent theoretical developments in understanding leaf water transport pathways and stable isotope theory to map a path for future work into understanding pathways of water transport and leaf water stable isotope composition. We emphasize the need for a spatially, anatomically and isotopically explicit model of leaf water transport. © 2016 John Wiley & Sons Ltd.

  17. Electric-field-induced strain contributions in morphotropic phase boundary composition of (Bi{sub 1/2}Na{sub 1/2})TiO{sub 3}-BaTiO{sub 3} during poling

    Energy Technology Data Exchange (ETDEWEB)

    Khansur, Neamul H.; Daniels, John E. [School of Materials Science and Engineering, UNSW Australia, New South Wales 2052 (Australia); Hinterstein, Manuel [School of Materials Science and Engineering, UNSW Australia, New South Wales 2052 (Australia); Institute for Applied Materials, Karlsruhe Institute for Technology, P.O. Box 3640, 76021 Karlsruhe (Germany); Wang, Zhiyang [School of Materials Science and Engineering, UNSW Australia, New South Wales 2052 (Australia); The Australian Synchrotron, Clayton, Victoria 3168 (Australia); Groh, Claudia [Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Straße 2, 64287 Darmstadt (Germany); Jo, Wook [School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919 (Korea, Republic of)

    2015-12-14

    The microscopic contributions to the electric-field-induced macroscopic strain in a morphotropic 0.93(Bi{sub 1/2}Na{sub 1/2}TiO{sub 3})−0.07(BaTiO{sub 3}) with a mixed rhombohedral and tetragonal structure have been quantified using full pattern Rietveld refinement of in situ high-energy x-ray diffraction data. The analysis methodology allows a quantification of all strain mechanisms for each phase in a morphotropic composition and is applicable to use in a wide variety of piezoelectric compositions. It is shown that during the poling of this material 24%, 44%, and 32% of the total macroscopic strain is generated from lattice strain, domain switching, and phase transformation strains, respectively. The results also suggest that the tetragonal phase contributes the most to extrinsic domain switching strain, whereas the lattice strain primarily stems from the rhombohedral phase. The analysis also suggests that almost 32% of the total strain is lost or is a one-time effect due to the irreversible nature of the electric-field-induced phase transformation in the current composition. This information is relevant to on-going compositional development strategies to harness the electric-field-induced phase transformation strain of (Bi{sub 1/2}Na{sub 1/2})TiO{sub 3}-based lead-free piezoelectric materials for actuator applications.

  18. Stable cosmology in chameleon bigravity

    Science.gov (United States)

    De Felice, Antonio; Mukohyama, Shinji; Oliosi, Michele; Watanabe, Yota

    2018-02-01

    The recently proposed chameleonic extension of bigravity theory, by including a scalar field dependence in the graviton potential, avoids several fine-tunings found to be necessary in usual massive bigravity. In particular it ensures that the Higuchi bound is satisfied at all scales, that no Vainshtein mechanism is needed to satisfy Solar System experiments, and that the strong coupling scale is always above the scale of cosmological interest all the way up to the early Universe. This paper extends the previous work by presenting a stable example of cosmology in the chameleon bigravity model. We find a set of initial conditions and parameters such that the derived stability conditions on general flat Friedmann background are satisfied at all times. The evolution goes through radiation-dominated, matter-dominated, and de Sitter eras. We argue that the parameter space allowing for such a stable evolution may be large enough to encompass an observationally viable evolution. We also argue that our model satisfies all known constraints due to gravitational wave observations so far and thus can be considered as a unique testing ground of gravitational wave phenomenologies in bimetric theories of gravity.

  19. Stable Heavy Hadrons in ATLAS

    CERN Document Server

    Mackeprang, Rasmus

    2007-01-01

    Several extensions to the SM feature heavy long-lived particles with masses of O(10^2-10^3 GeV) and mean lifetimes fulfilling $CT \\geq 10m$. Among such theories are supersymmetric scenarios as well as extra-dimensional models in which the heavy new particles are seen as Kaluza-Klein excitations of the well-known SM particles. Such particles will, from the point of view of a collider experiment be seen as stable. This thesis is concerned with the case where the exotic heavy particles emph{can} be considered stable while traversing the detector. Specifically the case is considered where the particles in question carry the charge of the strong nuclear force, commonly referred to as emph{colour charge}. A simulation kit has been developed using GEANT4. This framework is the current standard in experimental particle physics for the simulation of interactions of particles with matter, and it is used extensively for detector simulation. The simulation describes the interactions of these particles with matter which i...

  20. Investigation of phase stability in the scandia-zirconia; Investigacao da estabilidade de fases da zirconia-escandia

    Energy Technology Data Exchange (ETDEWEB)

    Grosso, Robson Lopes

    2016-11-01

    In this work, the phase stability of scandia-zirconia (ScSZ) system was investigated by the thermodynamic study of nanoparticles, within the range of 0 to 20 mol% Sc{sub 2}O{sub 3}, and by codoping of ZrO{sub 2}-10 mol% Sc{sub 2}O{sub 3} (10ScSZ) with Dy{sub 2}O{sub 3} and Nb{sub 2}O{sub 5}. The phase stability of ScSZ was evaluated based on thermodynamic data collected by water adsorption microcalorimetry and high temperature oxide melt solution. Nanostructured zirconia-scandia solid solutions were synthesized by coprecipitation method. Thermodynamic data were determined for ScSZ polymorph (monoclinic, tetragonal, cubic, rhombohedral β and γ) found by X-ray diffraction. This systemic work resulted in an unprecedented phase diagram at the nanoscale of particle size-composition. The effects of additives on 10ScSZ were investigated aiming to stabilize the cubic (c) structure at room temperature and to suppress the characteristic cubic-rhombohedral β phase transformation. Compositions were prepared by coprecipitation and solid state reaction. Materials were sintered by conventional and spark plasma sintering. Full stabilization of the cubic phase was attained by 1 mol% Dy{sub 2}O{sub 3} and 0.5 mol% Nb{sub 2}O{sub 5} additions. The smallest Nb{sub 2}O{sub 5} content required for cubic phase stabilization was attributed to liquid phase formation during sintering and to small ionic radius of Nb{sup 5+}. Results of high temperature X-ray diffraction and thermal analysis show suppression of the c-β transformation. Samples containing 0.5 mol% Nb{sub 2}O{sub 5} show total ionic conductivity similar to 10ScSZ without additives within a broad temperature range with high stability during 170 h at 600 °C. (author)

  1. Comparative Study of Phase Transformation in Single-Crystal Germanium during Single and Cyclic Nanoindentation

    Directory of Open Access Journals (Sweden)

    Koji Kosai

    2017-11-01

    Full Text Available Single-crystal germanium is a semiconductor material which shows complicated phase transformation under high pressure. In this study, new insight into the phase transformation of diamond-cubic germanium (dc-Ge was attempted by controlled cyclic nanoindentation combined with Raman spectroscopic analysis. Phase transformation from dc-Ge to rhombohedral phase (r8-Ge was experimentally confirmed for both single and cyclic nanoindentation under high loading/unloading rates. However, compared to single indentation, double cyclic indentation with a low holding load between the cycles caused more frequent phase transformation events. Double cyclic indentation caused more stress in Ge than single indentation and increased the possibility of phase transformation. With increase in the holding load, the number of phase transformation events decreased and finally became less than that under single indentation. This phenomenon was possibly caused by defect nucleation and shear accumulation during the holding process, which were promoted by a high holding load. The defect nucleation suppressed the phase transformation from dc-Ge to r8-Ge, and shear accumulation led to another phase transformation pathway, respectively. A high holding load promoted these two phenomena, and thus decreased the possibility of phase transformation from dc-Ge to r8-Ge.

  2. Stable isotope mass spectrometry in petroleum exploration

    International Nuclear Information System (INIS)

    Mathur, Manju

    1997-01-01

    The stable isotope mass spectrometry plays an important role to evaluate the stable isotopic composition of hydrocarbons. The isotopic ratios of certain elements in petroleum samples reflect certain characteristics which are useful for petroleum exploration

  3. Stable emergent Universe - a creation without Big-Bang

    Science.gov (United States)

    Guendelman, E.; Herrera, R.; Labrana, P.; Nissimov, E.; Pacheva, S.

    2015-11-01

    Based on an earlier introduced new class of generalized gravity-matter models defined in terms of two independent non-Riemannian volume forms (alternative generally covariant integration measure densities) on the space-time manifold, we derive an effective ``Einstein-frame'' theory featuring the following remarkable properties: (i) We obtain effective potential for the cosmological scalar field possessing two infinitely large flat regions which allows for a unified description of both early Universe inflation as well as of present dark energy epoch; (ii) for a specific parameter range the model possesses a non-singular stable ``emergent Universe'' solution which describes an initial phase of evolution that precedes the inflationary phase.

  4. Stable rotating dipole solitons in nonlocal media

    DEFF Research Database (Denmark)

    Lopez-Aguayo, Servando; Skupin, Stefan; Desyatnikov, Anton S.

    2006-01-01

    We present the first example of stable rotating two-soliton bound states in nonlinear optical media with nonlocal response. We show that, in contrast to media with local response, nonlocality opens possibilities to generate stable azimuthons.......We present the first example of stable rotating two-soliton bound states in nonlinear optical media with nonlocal response. We show that, in contrast to media with local response, nonlocality opens possibilities to generate stable azimuthons....

  5. Tempered stable laws as random walk limits

    OpenAIRE

    Chakrabarty, Arijit; Meerschaert, Mark M.

    2010-01-01

    Stable laws can be tempered by modifying the L\\'evy measure to cool the probability of large jumps. Tempered stable laws retain their signature power law behavior at infinity, and infinite divisibility. This paper develops random walk models that converge to a tempered stable law under a triangular array scheme. Since tempered stable laws and processes are useful in statistical physics, these random walk models can provide a basic physical model for the underlying physical phenomena.

  6. Stable States of Biological Organisms

    Science.gov (United States)

    Yukalov, V. I.; Sornette, D.; Yukalova, E. P.; Henry, J.-Y.; Cobb, J. P.

    2009-04-01

    A novel model of biological organisms is advanced, treating an organism as a self-consistent system subject to a pathogen flux. The principal novelty of the model is that it describes not some parts, but a biological organism as a whole. The organism is modeled by a five-dimensional dynamical system. The organism homeostasis is described by the evolution equations for five interacting components: healthy cells, ill cells, innate immune cells, specific immune cells, and pathogens. The stability analysis demonstrates that, in a wide domain of the parameter space, the system exhibits robust structural stability. There always exist four stable stationary solutions characterizing four qualitatively differing states of the organism: alive state, boundary state, critical state, and dead state.

  7. Super-stable Poissonian structures

    International Nuclear Information System (INIS)

    Eliazar, Iddo

    2012-01-01

    In this paper we characterize classes of Poisson processes whose statistical structures are super-stable. We consider a flow generated by a one-dimensional ordinary differential equation, and an ensemble of particles ‘surfing’ the flow. The particles start from random initial positions, and are propagated along the flow by stochastic ‘wave processes’ with general statistics and general cross correlations. Setting the initial positions to be Poisson processes, we characterize the classes of Poisson processes that render the particles’ positions—at all times, and invariantly with respect to the wave processes—statistically identical to their initial positions. These Poisson processes are termed ‘super-stable’ and facilitate the generalization of the notion of stationary distributions far beyond the realm of Markov dynamics. (paper)

  8. Super-stable Poissonian structures

    Science.gov (United States)

    Eliazar, Iddo

    2012-10-01

    In this paper we characterize classes of Poisson processes whose statistical structures are super-stable. We consider a flow generated by a one-dimensional ordinary differential equation, and an ensemble of particles ‘surfing’ the flow. The particles start from random initial positions, and are propagated along the flow by stochastic ‘wave processes’ with general statistics and general cross correlations. Setting the initial positions to be Poisson processes, we characterize the classes of Poisson processes that render the particles’ positions—at all times, and invariantly with respect to the wave processes—statistically identical to their initial positions. These Poisson processes are termed ‘super-stable’ and facilitate the generalization of the notion of stationary distributions far beyond the realm of Markov dynamics.

  9. Periodicity of the stable isotopes

    CERN Document Server

    Boeyens, J C A

    2003-01-01

    It is demonstrated that all stable (non-radioactive) isotopes are formally interrelated as the products of systematically adding alpha particles to four elementary units. The region of stability against radioactive decay is shown to obey a general trend based on number theory and contains the periodic law of the elements as a special case. This general law restricts the number of what may be considered as natural elements to 100 and is based on a proton:neutron ratio that matches the golden ratio, characteristic of biological and crystal growth structures. Different forms of the periodic table inferred at other proton:neutron ratios indicate that the electronic configuration of atoms is variable and may be a function of environmental pressure. Cosmic consequences of this postulate are examined. (author)

  10. Stable massive particles at colliders

    Energy Technology Data Exchange (ETDEWEB)

    Fairbairn, M.; /Stockholm U.; Kraan, A.C.; /Pennsylvania U.; Milstead, D.A.; /Stockholm U.; Sjostrand, T.; /Lund U.; Skands, P.; /Fermilab; Sloan, T.; /Lancaster U.

    2006-11-01

    We review the theoretical motivations and experimental status of searches for stable massive particles (SMPs) which could be sufficiently long-lived as to be directly detected at collider experiments. The discovery of such particles would address a number of important questions in modern physics including the origin and composition of dark matter in the universe and the unification of the fundamental forces. This review describes the techniques used in SMP-searches at collider experiments and the limits so far obtained on the production of SMPs which possess various colour, electric and magnetic charge quantum numbers. We also describe theoretical scenarios which predict SMPs, the phenomenology needed to model their production at colliders and interactions with matter. In addition, the interplay between collider searches and open questions in cosmology such as dark matter composition are addressed.

  11. A highly stable microchannel heat sink for convective boiling

    International Nuclear Information System (INIS)

    Lu, Chun Ting; Pan Chin

    2009-01-01

    To develop a highly stable two-phase microchannel heat sink, we experimented with convective boiling in diverging, parallel microchannels with different distributions of laser-etched artificial nucleation sites. Each microchannel had a mean hydraulic diameter of 120 µm. The two-phase flow visualization and the magnitudes of pressure drop and inlet temperature oscillations under boiling conditions demonstrated clearly the merits of using artificial nucleation sites to further stabilize the flow boiling in diverging, parallel microchannels. The stability map showed the plane of subcooling number versus phase change number. It illustrated that diverging, parallel microchannels with artificial nucleation cavities have a much wider stable region than parallel microchannels with uniform cross-sections or diverging, parallel microchannels without artificial nucleation cavities. In addition, the results revealed that the design with cavities distributed uniformly along the downstream half of the channel presented the best stability performance among the three distributions of nucleation sites. This particular design can be regarded as a highly stable microchannel heat sink for convective boiling

  12. The Myopic Stable Set for Social Environments

    NARCIS (Netherlands)

    Demuynck, Thomas; Herings, P. Jean-Jacques; Saulle, Riccardo; Seel, Christian

    2017-01-01

    We introduce a new solution concept for models of coalition formation, called the myopic stable set. The myopic stable set is defined for a very general class of social environments and allows for an infinite state space. We show that the myopic stable set exists and is non-empty. Under minor

  13. Effectiveness and risks of stable iodine prophylaxis

    International Nuclear Information System (INIS)

    Waight, P.J.

    1995-01-01

    The factors upon which the efficacy of stable iodine prophylaxis depends are reviewed, with particular reference to the dose of stable iodine, the timing of the dose, the influence of dietary iodine and the impact of the other prospective actions. The risks of stable iodine ingestion are estimated, and their application to the principle of Justification in outlined. (Author)

  14. Temperature and Humidity Control in Livestock Stables

    DEFF Research Database (Denmark)

    Hansen, Michael; Andersen, Palle; Nielsen, Kirsten M.

    2010-01-01

    The paper describes temperature and humidity control of a livestock stable. It is important to have a correct air flow pattern in the livestock stable in order to achieve proper temperature and humidity control as well as to avoid draught. In the investigated livestock stable the air flow...

  15. Pressure-induced phase transition and octahedral tilt system change of Ba2BiSbO6

    International Nuclear Information System (INIS)

    Lufaso, Michael W.; Macquart, Rene B.; Lee, Yongjae; Vogt, Thomas; Loye, Hans-Conrad zur

    2006-01-01

    High-resolution X-ray synchrotron powder diffraction studies under high-pressure conditions are reported for the ordered double perovskite Ba 2 BiSbO 6 . Near 4GPa, the oxide undergoes a pressure-induced phase transition. The symmetry of the material changes during the phase transition from space group R3-bar to space group I2/m, which is consistent with a change in the octahedral tilting distortion from an a - a - a - type to a 0 b - b - type using the Glazer notation. A fit of the volume-pressure data using the Birch-Murnagaham equation of state yielded a bulk modulus of 144(8)GPa for the rhombohedral phase

  16. Multi-level storage and ultra-high speed of superlattice-like Ge50Te50/Ge8Sb92 thin film for phase-change memory application.

    Science.gov (United States)

    Wu, Weihua; Chen, Shiyu; Zhai, Jiwei; Liu, Xinyi; Lai, Tianshu; Song, Sannian; Song, Zhitang

    2017-10-06

    Superlattice-like Ge 50 Te 50 /Ge 8 Sb 92 (SLL GT/GS) thin film was systematically investigated for multi-level storage and ultra-fast switching phase-change memory application. In situ resistance measurement indicates that SLL GT/GS thin film exhibits two distinct resistance steps with elevated temperature. The thermal stability of the amorphous state and intermediate state were evaluated with the Kissinger and Arrhenius plots. The phase-structure evolution revealed that the amorphous SLL GT/GS thin film crystallized into rhombohedral Sb phase first, then the rhombohedral GeTe phase. The microstructure, layered structure, and interface stability of SLL GT/GS thin film was confirmed by using transmission electron microscopy. The transition speed of crystallization and amorphization was measured by the picosecond laser pump-probe system. The volume variation during the crystallization was obtained from x-ray reflectivity. Phase-change memory (PCM) cells based on SLL GT/GS thin film were fabricated to verify the multi-level switching under an electrical pulse as short as 30 ns. These results illustrate that the SLL GT/GS thin film has great potentiality in high-density and high-speed PCM applications.

  17. In situ Raman study of C60 polymerization during isothermal pressurizing at 800 K

    International Nuclear Information System (INIS)

    Talyzin, A V; Dubrovinsky, L S

    2004-01-01

    The first in situ Raman study of C 60 isothermal compression at 800 K and up to 32 GPa was performed using rhombohedral and tetragonal phases as starting materials. The rhombohedral phase shows a phase transition to 3D polymer above 10 GPa, similar to that in experiments where isobaric heating was used at pressures of 9-13 GPa. It is shown that the T-P diagram of C 60 polymeric phases (temperature increase followed by pressurizing) is significantly different from the known P-T diagram (pressurizing followed by heating). Tetragonal polymer exhibited significantly stronger stability and can be followed at least up to ∼15 GPa. Heating up to 800 K of tetragonal polymer at pressures of 6-8 GPa confirms that, due to geometrical frustrations, the tetragonal phase remains stable even at pressure and temperature conditions at which rhombohedral polymer is usually formed

  18. Effect of La3+ substitution on the phase transitions, microstructure and electrical properties of Bi1−xLaxFeO3 ceramics

    International Nuclear Information System (INIS)

    Zhang, Qiang; Zhu, Xiaohong; Xu, Yunhui; Gao, Haobin; Xiao, Yunjun; Liang, Dayun; Zhu, Jiliang; Zhu, Jianguo; Xiao, Dingquan

    2013-01-01

    Highlights: ► Structural properties of Bi 1−x La x FeO 3 ceramics are improved by La 3+ substitution. ► Significant magnetoelectric responses are observed in Bi 1−x La x FeO 3 ceramics. ► T C is lowered while T N is enhanced in the La-doped BiFeO 3 ceramics. ► Much higher dielectric constant is obtained in the La-doped BiFeO 3 ceramics. ► The ferroelectric properties are enhanced in the La-doped BiFeO 3 ceramics. - Abstract: Multiferroic Bi 1−x La x FeO 3 (x = 0.00, 0.05, 0.10, 0.15, 0.20) (represented as B 1−x L x FO) ceramics were prepared using the conventional solid state reaction route. The effects of La 3+ doping on the density, phase structure, morphology, dielectric and ferroelectric properties were investigated. Judging from X-ray diffraction patterns, all the B 1−x L x FO ceramic samples were well crystallized in a pure perovskite phase while the crystal structure changed from rhombohedral to orthorhombic with increasing the La 3+ substitution. SEM observations clearly revealed that the grain size was remarkably decreased by La 3+ doping. As a result, the ferroelectric Curie temperature was lowered in the La-doped ceramics. However, the abnormal dielectric responses near the antiferromagnetic Néel temperature (T N ) demonstrated the existence of remarkable magnetoelectric coupling in the Bi 1−x La x FeO 3 ceramics, and the T N was shown to increase substantially with the increase in La 3+ doping content. It was found that the dielectric permittivity of the ceramics was significantly increased and the dielectric loss was slightly increased with the increase in La 3+ content. The dielectric constant ε r of the Bi 0.85 La 0.15 FeO 3 ceramic at 10 kHz reached as high as 1008, 20 times larger than that for pure BiFeO 3 . In addition, the ferroelectric properties of the B 1−x L x FO ceramics were improved and the remanent polarization was increased by La 3+ doping. This is probably because the A-site doping with more stable La 3+ could

  19. A New Method to Improve the Electrical Properties of KNN-based Ceramics: Tailoring Phase Fraction

    KAUST Repository

    Lv, Xiang; Wu, Jiagang; Zhu, Jianguo; Xiao, Dingquan; Zhang, Xixiang

    2017-01-01

    Although both the phase type and fraction of multi-phase coexistence can affect the electrical properties of (K,Na)NbO3 (KNN)-based ceramics, effects of phase fraction on their electrical properties were few concerned. In this work, through changing the calcination temperature of CaZrO3 powders, we successfully developed the 0.96K0.5Na0.5Nb0.96Sb0.04O3-0.01CaZrO3-0.03Bi0.5Na0.5HfO3 ceramics containing a wide rhombohedral-tetragonal (R-T) phase coexistence with the variations of T (or R) phase fractions. It was found that higher T phase fraction can warrant a larger piezoelectric constant (d33) and d33 also showed a linear variation with respect to tetragonality ratio (c/a). More importantly, a number of domain patterns were observed due to high T phase fraction and large c/a ratio, greatly benefiting the piezoelectricity. In addition, the improved ferroelectric fatigue behavior and thermal stability were also shown in the ceramics containing high T phase fraction. Therefore, this work can bring a new viewpoint into the physical mechanism of KNN-based ceramics behind R-T phase coexistence.

  20. Room Temperature Monoclinic Phase in BaTiO3 Single Crystals

    Science.gov (United States)

    Denev, Sava; Kumar, Amit; Barnes, Andrew; Vlahos, Eftihia; Shepard, Gabriella; Gopalan, Venkatraman

    2010-03-01

    BaTiO3 is a well studied ferroelectric material for the last half century. It is well known to show phase transitions to tetragonal, orthorhombic and rhombohedral phases upon cooling. Yet, some old and some recent studies have argued that all these phases co-exist with a second phase with monoclinic distortion. Using optical second harmonic generation (SHG) at room temperature we directly present evidence for such monoclininc phase co-existing with tetragonal phase at room temperature. We observe domains with the expected tetragonal symmetry exhibiting 90^o and 180^o domain walls. However, at points of higher stress at the tips of the interpenetrating tetragonal domains we observe a well pronounced metastable ``staircase pattern'' with a micron-scale fine structure. Polarization studies show that this phase can be explained only by monoclinic symmetry. This phase is very sensitive to external perturbations such as temperature and fields, hence stabilizing this phase at room temperature could lead to large properties' tunability.

  1. Understanding Strain-Induced Phase Transformations in BiFeO3 Thin Films.

    Science.gov (United States)

    Dixit, Hemant; Beekman, Christianne; Schlepütz, Christian M; Siemons, Wolter; Yang, Yongsoo; Senabulya, Nancy; Clarke, Roy; Chi, Miaofang; Christen, Hans M; Cooper, Valentino R

    2015-08-01

    Experiments demonstrate that under large epitaxial strain a coexisting striped phase emerges in BiFeO 3 thin films, which comprises a tetragonal-like ( T ') and an intermediate S ' polymorph. It exhibits a relatively large piezoelectric response when switching between the coexisting phase and a uniform T ' phase. This strain-induced phase transformation is investigated through a synergistic combination of first-principles theory and experiments. The results show that the S ' phase is energetically very close to the T ' phase, but is structurally similar to the bulk rhombohedral ( R ) phase. By fully characterizing the intermediate S ' polymorph, it is demonstrated that the flat energy landscape resulting in the absence of an energy barrier between the T ' and S ' phases fosters the above-mentioned reversible phase transformation. This ability to readily transform between the S ' and T ' polymorphs, which have very different octahedral rotation patterns and c / a ratios, is crucial to the enhanced piezoelectricity in strained BiFeO 3 films. Additionally, a blueshift in the band gap when moving from R to S ' to T ' is observed. These results emphasize the importance of strain engineering for tuning electromechanical responses or, creating unique energy harvesting photonic structures, in oxide thin film architectures.

  2. A New Method to Improve the Electrical Properties of KNN-based Ceramics: Tailoring Phase Fraction

    KAUST Repository

    Lv, Xiang

    2017-08-18

    Although both the phase type and fraction of multi-phase coexistence can affect the electrical properties of (K,Na)NbO3 (KNN)-based ceramics, effects of phase fraction on their electrical properties were few concerned. In this work, through changing the calcination temperature of CaZrO3 powders, we successfully developed the 0.96K0.5Na0.5Nb0.96Sb0.04O3-0.01CaZrO3-0.03Bi0.5Na0.5HfO3 ceramics containing a wide rhombohedral-tetragonal (R-T) phase coexistence with the variations of T (or R) phase fractions. It was found that higher T phase fraction can warrant a larger piezoelectric constant (d33) and d33 also showed a linear variation with respect to tetragonality ratio (c/a). More importantly, a number of domain patterns were observed due to high T phase fraction and large c/a ratio, greatly benefiting the piezoelectricity. In addition, the improved ferroelectric fatigue behavior and thermal stability were also shown in the ceramics containing high T phase fraction. Therefore, this work can bring a new viewpoint into the physical mechanism of KNN-based ceramics behind R-T phase coexistence.

  3. Geochemistry of the stable isotopes of silicon

    Energy Technology Data Exchange (ETDEWEB)

    Douthitt, C B [California Inst. of Tech., Pasadena (USA). Div. of Geological and Planetary Sciences

    1982-08-01

    One hundred thirty two new measurements of the relative abundances of the stable isotopes of silicon in terrestrial materials are presented. The total variation of delta/sup 30/Si found is 6.2 parts per thousand, centered on the mean of terrestrial mafic and ultramafic igneous rocks, delta/sup 30/Si = -0.4 parts per thousand. Igneous rocks show limited variation; coexisting minerals exhibit small, systematic silicon isotopic fractionations that are roughly 1/3 the magnitude of concomitant oxygen isotopic fractionations at 1150/sup 0/C. In both igneous minerals and rocks, delta/sup 30/Si shows a positive correlation with silicon content, as does delta/sup 18/O. Opal from both sponge spicules and sinters is light, with delta/sup 30/Si = -2.3 and -1.4 parts per thousand respectively. Large delta/sup 30/Si values of both positive and negative sign are reported for the first time from clay minerals, opaline phytoliths, and authigenic quartz. All highly fractionated samples were precipitated from solution at low temperatures; however, aqueous silicon is not measurably fractionated relative to quartz at equilibrium. A kinetic isotope fractionation of approximately 3.5 parts per thousand is postulated to occur during the low temperature precipitation of opal and, possibly, poorly ordered phyllosilicates, with the silicate phase being enriched in /sup 28/Si. This fractionation, coupled with a Rayleigh precipitation model, is capable of explaining most non-magmatic delta/sup 30/Si variations.

  4. Moltex Energy's stable salt reactors

    International Nuclear Information System (INIS)

    O'Sullivan, R.; Laurie, J.

    2016-01-01

    A stable salt reactor is a molten salt reactor in which the molten fuel salt is contained in fuel rods. This concept was invented in 1951 and re-discovered and improved recently by Moltex Energy Company. The main advantage of using molten salt fuel is that the 2 problematic fission products cesium and iodine do not exist in gaseous form but rather in a form of a salt that present no danger in case of accident. Another advantage is the strongly negative temperature coefficient for reactivity which means the reactor self-regulates. The feasibility studies have been performed on a molten salt fuel composed of sodium chloride and plutonium/uranium/lanthanide/actinide trichloride. The coolant fluid is a mix of sodium and zirconium fluoride salts that will need low flow rates. The addition of 1 mol% of metal zirconium to the coolant fluid reduces the risk of corrosion with standard steels and the addition of 2% of hafnium reduces the neutron dose. The temperature of the coolant is expected to reach 650 Celsius degrees at the exit of the core. This reactor is designed to be modular and it will be able to burn actinides. (A.C.)

  5. Stable piecewise polynomial vector fields

    Directory of Open Access Journals (Sweden)

    Claudio Pessoa

    2012-09-01

    Full Text Available Let $N={y>0}$ and $S={y<0}$ be the semi-planes of $mathbb{R}^2$ having as common boundary the line $D={y=0}$. Let $X$ and $Y$ be polynomial vector fields defined in $N$ and $S$, respectively, leading to a discontinuous piecewise polynomial vector field $Z=(X,Y$. This work pursues the stability and the transition analysis of solutions of $Z$ between $N$ and $S$, started by Filippov (1988 and Kozlova (1984 and reformulated by Sotomayor-Teixeira (1995 in terms of the regularization method. This method consists in analyzing a one parameter family of continuous vector fields $Z_{epsilon}$, defined by averaging $X$ and $Y$. This family approaches $Z$ when the parameter goes to zero. The results of Sotomayor-Teixeira and Sotomayor-Machado (2002 providing conditions on $(X,Y$ for the regularized vector fields to be structurally stable on planar compact connected regions are extended to discontinuous piecewise polynomial vector fields on $mathbb{R}^2$. Pertinent genericity results for vector fields satisfying the above stability conditions are also extended to the present case. A procedure for the study of discontinuous piecewise vector fields at infinity through a compactification is proposed here.

  6. Stable Structures for Distributed Applications

    Directory of Open Access Journals (Sweden)

    Eugen DUMITRASCU

    2008-01-01

    Full Text Available For distributed applications, we define the linear, tree and graph structure types with different variants and modalities to aggregate them. The distributed applications have assigned structures that through their characteristics influence the costs of stages for developing cycle and the costs for exploitation, transferred to each user. We also present the quality characteristics of a structure for a stable application, which is focused on stability characteristic. For that characteristic we define the estimated measure indicators for a level. The influence of the factors of stability and the ways for increasing it are thus identified, and at the same time the costs of development stages, the costs of usage and the costs of maintenance to be keep on between limits that assure the global efficiency of application. It is presented the base aspects for distributed applications: definition, peculiarities and importance. The aspects for the development cycle of distributed application are detailed. In this article, we alongside give the mechanisms for building the defined structures and analyze the complexity of the defined structures for a distributed application of a virtual store.

  7. Raman and infrared spectroscopic investigations of a ferroelastic phase transition in B a2ZnTe O6 double perovskite

    Science.gov (United States)

    Moreira, Roberto L.; Lobo, Ricardo P. S. M.; Ramos, Sérgio L. L. M.; Sebastian, Mailadil T.; Matinaga, Franklin M.; Righi, Ariete; Dias, Anderson

    2018-05-01

    The low-temperature vibrational properties of B a2ZnTe O6 double-perovskite ceramics obtained by the solid-state route were investigated by Raman scattering and Fourier-transform infrared reflectivity. We found that this material undergoes a reversible ferroelastic phase transition at around 140 K, well compatible with a recently proposed rhombohedral-to-monoclinic structural change that would occur below 165 K. Complementary calorimetric measurements showed that the phase transition has a first-order character, with an entropy jump compatible with a displacive mechanism. The vibrational spectra show clearly the splitting of the doubly degenerate E modes into nondegenerate representations of the low-symmetry phase. In particular, the lowest-frequency Raman mode presents soft-mode behavior and splits below the critical temperature, confirming the in-plane ferroelastic deformation in the low-temperature phase.

  8. Advanced thermally stable jet fuels

    Energy Technology Data Exchange (ETDEWEB)

    Schobert, H.H.

    1999-01-31

    The Pennsylvania State University program in advanced thermally stable coal-based jet fuels has five broad objectives: (1) Development of mechanisms of degradation and solids formation; (2) Quantitative measurement of growth of sub-micrometer and micrometer-sized particles suspended in fuels during thermal stressing; (3) Characterization of carbonaceous deposits by various instrumental and microscopic methods; (4) Elucidation of the role of additives in retarding the formation of carbonaceous solids; (5) Assessment of the potential of production of high yields of cycloalkanes by direct liquefaction of coal. Future high-Mach aircraft will place severe thermal demands on jet fuels, requiring the development of novel, hybrid fuel mixtures capable of withstanding temperatures in the range of 400--500 C. In the new aircraft, jet fuel will serve as both an energy source and a heat sink for cooling the airframe, engine, and system components. The ultimate development of such advanced fuels requires a thorough understanding of the thermal decomposition behavior of jet fuels under supercritical conditions. Considering that jet fuels consist of hundreds of compounds, this task must begin with a study of the thermal degradation behavior of select model compounds under supercritical conditions. The research performed by The Pennsylvania State University was focused on five major tasks that reflect the objectives stated above: Task 1: Investigation of the Quantitative Degradation of Fuels; Task 2: Investigation of Incipient Deposition; Task 3: Characterization of Solid Gums, Sediments, and Carbonaceous Deposits; Task 4: Coal-Based Fuel Stabilization Studies; and Task 5: Exploratory Studies on the Direct Conversion of Coal to High Quality Jet Fuels. The major findings of each of these tasks are presented in this executive summary. A description of the sub-tasks performed under each of these tasks and the findings of those studies are provided in the remainder of this volume

  9. Hexagonal perovskites with cationic vacancies. 7. Vibrational spectroscopic investigations on the rhombohedral 12 L-stacking polytypes Ba/sub 4/Bsup(II)(Re/sub 2/vacantO/sub 12/) and Ba/sub 4/Bsub(2/3)sup(III)vacantsub(1/3)(Re/sub 2/vacantO/sub 12/)

    Energy Technology Data Exchange (ETDEWEB)

    Fadini, A; Kemmler-Sack, S; Schittenhelm, H J; Rother, H J; Treiber, U [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1979-07-01

    For the rhombohedral 12 L stacking polytypes Ba/sub 4/Bsup(II)(Re/sub 2/vacantO/sub 12/) and Ba/sub 4/Bsub(2/3)sup(III)vacantsub(1/3)(Re/sub 2/vacantO/sub 12/), space group R3m, sequence (3)(1), the lattice consists of groups of three face sharing octahedra with the composition Re/sub 2/vacantO/sub 12/. They are isolated from each other by the Ba and B ions. The vibrational spectra are interpreted according to the factor group analysis. For the Re/sub 2/vacantO/sub 12/ unit (symmetry Dsub(3d) the results of a complete vibrational analysis and the calculation of the force constants are reported.

  10. Hexagonal perovskites with cationic vacancies. 26. Ba/sub 12/Ba/sub 2//sub 2/3/M/sub 7//sup V//sub 1/3/vacant/sub 2/O/sub 33/vacant/sub 3/ (Msup(V) =Nb, Ta) - the first stacking polytypes of a rhombohedral 36 L-type

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1981-05-01

    In the systems BaO-M/sub 2//sup V/O/sub 5/ (M/sup V/ = Nb, Ta) for a Ba:M/sup V/ ratio of 2:1 polymorphism is observed. Here the low temperature modifications are described. They crystallize in a rhombohedral 36 L structure with three formula units Ba/sub 12/Ba/sub 2//sub 2/3/M/sub 7//sup V//sub 1/3/vacant/sub 2/O/sub 33/vacant/sub 3/ for the trigonal setting (M/sup V/ = Nb: a = 5.92/sub 2/ A; c = 93./sub 25/ A; Ta: a = 5.92/sub 2/ A; c = 93.4 A).

  11. Stable isotope geochemistry : definitions, terminology, measurement and some applications

    International Nuclear Information System (INIS)

    Faure, K.

    2009-01-01

    In 1936, Alfred Nier produced the first precise measurement of isotope abundance ratios and his design still remains the basis of stable isotope mass spectrometry. With this gift from the physicists for routine measurement of isotope ratios, earth scientists began to explore the natural variations of isotopes. Thus began a new era in geoscience research with the hydrological cycle and marine palaeolimatic research being the first topics to be investigated. Stable isotope measurements have been applied to many fundamental problems in geochemistry, petrology, and paleoclimatology, as well as related fields in archaeology, anthropology, physical chemistry, biology and forensic sciences. These applications can be broadly classified into four main types: 1. Thermometry: Formation temperatures of rock and mineral systems are determined on the basis of temperature-dependent fractionations of the isotopic ratios between two or more cogenetic phases. 2. Tracers: Reservoirs like the ocean, the mantle, meteroic waters and organic matter have distinct stable isotope signatures that can be used to trace the origin of rocks, fluids, contaminants etc. 3. Reaction mechanism: Distinctions can be made between diffusion and recrystallization, open and closed systems and bacterial and thermogenic processes. 4. Chemostratigraphy: Abrupt changes (excursions) in the stable isotope ratios of ocean sediments and certain terrestrial materials can be used as stratigraphic markers. (author). 56 refs., 11 figs., 2 tabs.

  12. Stable isotope geochemistry : definitions, terminology, measurement and some applications

    International Nuclear Information System (INIS)

    Faure, K.

    2014-01-01

    In 1936, Alfred Nier produced the first precise measurement of isotope abundance ratios and his design still remains the basis of stable isotope mass spectrometry. With this gift from the physicists for routine measurement of isotope ratios, earth scientists began to explore the natural variations of isotopes. Thus began a new era in geoscience research with the hydrological cycle and marine palaeoclimatic research being the first topics to be investigated. Stable isotope measurements have been applied to many fundamental problems in geochemistry, petrology, and paleoclimatology, as well as related fields in archaeology, anthropology, physical chemistry, biology and forensic sciences. These applications can be broadly classified into four main types: 1. Thermometry: Formation temperatures of rock and mineral systems are determined on the basis of temperature-dependent fractionations of the isotopic ratios between two or more cogenetic phases. 2. Tracers: Reservoirs like the ocean, the mantle, meteoric waters and organic matter have distinct stable isotope signatures that can be used to trace the origin of rocks, fluids, contaminants etc. 3. Reaction mechanism: Distinctions can be made between diffusion and recrystallization, open and closed systems and bacterial and thermogenic processes. 4. Chemostratigraphy: Abrupt changes (excursions) in the stable isotope ratios of ocean sediments and certain terrestrial materials can be used as stratigraphic markers. (author)

  13. Stable isotope geochemistry: definitions, terminology, measurement and some applications

    International Nuclear Information System (INIS)

    Faure, K.

    2015-01-01

    In 1936, Alfred Nier produced the first precise measurement of isotope abundance ratios and his design still remains the basis of stable isotope mass spectrometry. With this gift from the physicists for routine measurement of isotope ratios, earth scientists began to explore the natural variations of isotopes. Thus began a new era in geoscience research with the hydrological cycle and marine palaeoclimatic research being the first topics to be investigated. Stable isotope measurements have been applied to many fundamental problems in geochemistry, petrology, and paleoclimatology, as well as related fields in archaeology, anthropology, physical chemistry, biology and forensic sciences. These applications can be broadly classified into four main types: 1. Thermometry: Formation temperatures of rock and mineral systems are determined on the basis of temperature-dependent fractionations of the isotopic ratios between two or more cogenetic phases. 2. Tracers: Reservoirs like the ocean, the mantle, meteoric waters and organic matter have distinct stable isotope signatures that can be used to trace the origin of rocks, fluids, contaminants etc. 3. Reaction mechanism: Distinctions can be made between diffusion and recrystallization, open and closed systems and bacterial and thermogenic processes. 4. Chemostratigraphy: Abrupt changes (excursions) in the stable isotope ratios of ocean sediments and certain terrestrial materials can be used as stratigraphic markers. (author).

  14. Stable isotope geochemistry : definitions, terminology, measurement and some applications

    International Nuclear Information System (INIS)

    Faure, K.

    2012-01-01

    In 1936, Alfred Nier produced the first precise measurement of isotope abundance ratios and his design still remains the basis of stable isotope mass spectrometry. With this gift from the physicists for routine measurement of isotope ratios, earth scientists began to explore the natural variations of isotopes. Thus began a new era in geoscience research with the hydrological cycle and marine palaeoclimatic research being the first topics to be investigated. Stable isotope measurements have been applied to many fundamental problems in geochemistry, petrology, and paleoclimatology, as well as related fields in archaeology, anthropology, physical chemistry, biology and forensic sciences. These applications can be broadly classified into four main types: 1. Thermometry: Formation temperatures of rock and mineral systems are determined on the basis of temperature-dependent fractionations of the isotopic ratios between two or more cogenetic phases. 2. Tracers: Reservoirs like the ocean, the mantle, meteoric waters and organic matter have distinct stable isotope signatures that can be used to trace the origin of rocks, fluids, contaminants etc. 3. Reaction mechanism: Distinctions can be made between diffusion and recrystallization, open and closed systems and bacterial and thermogenic processes. 4. Chemostratigraphy: Abrupt changes (excursions) in the stable isotope ratios of ocean sediments and certain terrestrial materials can be used as stratigraphic markers. (author). 89 refs., 12 figs., 2 tabs.

  15. Stable isotope geochemistry : definitions, terminology, measurement and some applications

    International Nuclear Information System (INIS)

    Faure, K.

    2008-01-01

    In 1936, Alfred Nier produced the first precise measurement of isotope abundance ratios and his design still remains the basis of stable isotope mass spectrometry. With this gift from the physicists for routine measurement of isotope ratios, earth scientists began to explore the natural variations of isotopes. Thus began a new era in geoscience research with the hydrological cycle and marine palaeolimatic research being the first topics to be investigated. Stable isotope measurements have been applied to many fundamental problems in geochemistry, petrology, and paleoclimatology, as well as related fields in archaeology, anthropology, physical chemistry, biology and forensic sciences. These applications can be broadly classified into four main types: 1. Thermometry: Formation temperatures of rock and mineral systems are determined on the basis of temperature-dependent fractionations of the isotopic ratios between two or more cogenetic phases. 2. Tracers: Reservoirs like the ocean, the mantle, meteroic waters and organic matter have distinct stable isotope signatures that can be used to trace the origin of rocks, fluids, contaminants etc. 3. Reaction mechanism: Distinctions can be made between diffusion and recrystallization, open and closed systems and bacterial and thermogenic processes. 4. Chemostratigraphy: Abrupt changes (excursions) in the stable isotope ratios of ocean sediments and certain terrestrial materials can be used as stratigraphic markers. (author). 56 refs., 11 figs., 2 tabs

  16. Stable isotope geochemistry : definitions, terminology, measurement and some applications

    International Nuclear Information System (INIS)

    Faure, K.

    2009-01-01

    In 1936, Alfred Nier produced the first precise measurement of isotope abundance ratios and his design still remains the basis of stable isotope mass spectrometry. With this gift from the physicists for routine measurement of isotope ratios, earth scientists began to explore the natural variations of isotopes. Thus began a new era in geoscience research with the hydrological cycle and marine palaeolimatic research being the first topics to be investigated. Stable isotope measurements have been applied to many fundamental problems in geochemistry, petrology, and paleoclimatology, as well as related fields in archaeology, anthropology, physical chemistry, biology and forensic sciences. These applications can be broadly classified into four main types: 1. Thermometry: Formation temperatures of rock and mineral systems are determined on the basis of temperature-dependent fractionations of the isotopic ratios between two or more cogenetic phases. 2. Tracers: Reservoirs like the ocean, the mantle, meteroic waters and organic matter have distinct stable isotope signatures that can be used to trace the origin of rocks, fluids, contaminants etc. 3. Reaction mechanism: Distinctions can be made between diffusion and recrystallization, open and closed systems and bacterial and thermogenic processes. 4. Chemostratigraphy: Abrupt changes (excursions) in the stable isotope ratios of ocean sediments and certain terrestrial materials can be used as stratigraphic markers. (author). 56 refs., 11 figs., 2 tabs

  17. Stable isotope geochemistry : definitions, terminology, measurement and some applications

    International Nuclear Information System (INIS)

    Faure, K.

    2016-01-01

    In 1936, Alfred Nier produced the first precise measurement of isotope abundance ratios and his design still remains the basis of stable isotope mass spectrometry. With this gift from the physicists for routine measurement of isotope ratios, earth scientists began to explore the natural variations of isotopes. Thus began a new era in geoscience research with the hydrological cycle and marine palaeoclimatic research being the first topics to be investigated. Stable isotope measurements have been applied to many fundamental problems in geochemistry, petrology, and paleoclimatology, as well as related fields in archaeology, anthropology, physical chemistry, biology and forensic sciences. These applications can be broadly classified into four main types: 1. Thermometry: Formation temperatures of rock and mineral systems are determined on the basis of temperature-dependent fractionations of the isotopic ratios between two or more cogenetic phases. 2. Tracers: Reservoirs like the ocean, the mantle, meteoric waters and organic matter have distinct stable isotope signatures that can be used to trace the origin of rocks, fluids, contaminants etc. 3. Reaction mechanism: Distinctions can be made between diffusion and recrystallization, open and closed systems and bacterial and thermogenic processes. 4. Chemostratigraphy: Abrupt changes (excursions) in the stable isotope ratios of ocean sediments and certain terrestrial materials can be used as stratigraphic markers. (author).

  18. Stable isotope geochemistry : definitions, terminology, measurement and some applications

    International Nuclear Information System (INIS)

    Faure, K.

    2013-01-01

    In 1936, Alfred Nier produced the first precise measurement of isotope abundance ratios and his design still remains the basis of stable isotope mass spectrometry. With this gift from the physicists for routine measurement of isotope ratios, earth scientists began to explore the natural variations of isotopes. Thus began a new era in geoscience research with the hydrological cycle and marine palaeoclimatic research being the first topics to be investigated. Stable isotope measurements have been applied to many fundamental problems in geochemistry, petrology, and paleoclimatology, as well as related fields in archaeology, anthropology, physical chemistry, biology and forensic sciences. These applications can be broadly classified into four main types: 1. Thermometry: Formation temperatures of rock and mineral systems are determined on the basis of temperature-dependent fractionations of the isotopic ratios between two or more cogenetic phases. 2. Tracers: Reservoirs like the ocean, the mantle, meteoric waters and organic matter have distinct stable isotope signatures that can be used to trace the origin of rocks, fluids, contaminants etc. 3. Reaction mechanism: Distinctions can be made between diffusion and recrystallization, open and closed systems and bacterial and thermogenic processes. 4. Chemostratigraphy: Abrupt changes (excursions) in the stable isotope ratios of ocean sediments and certain terrestrial materials can be used as stratigraphic markers. (author). 91 refs., 12 figs., 2 tabs.

  19. Population Games, Stable Games, and Passivity

    Directory of Open Access Journals (Sweden)

    Michael J. Fox

    2013-10-01

    Full Text Available The class of “stable games”, introduced by Hofbauer and Sandholm in 2009, has the attractive property of admitting global convergence to equilibria under many evolutionary dynamics. We show that stable games can be identified as a special case of the feedback-system-theoretic notion of a “passive” dynamical system. Motivated by this observation, we develop a notion of passivity for evolutionary dynamics that complements the definition of the class of stable games. Since interconnections of passive dynamical systems exhibit stable behavior, we can make conclusions about passive evolutionary dynamics coupled with stable games. We show how established evolutionary dynamics qualify as passive dynamical systems. Moreover, we exploit the flexibility of the definition of passive dynamical systems to analyze generalizations of stable games and evolutionary dynamics that include forecasting heuristics as well as certain games with memory.

  20. Monoclinic MB phase and phase instability in [110] field cooled Pb(Zn1/3Nb2/3)O3-4.5%PbTiO3 single crystals

    Science.gov (United States)

    Yao, Jianjun; Cao, Hu; Ge, Wenwei; Li, Jiefang; Viehland, D.

    2009-08-01

    We report the finding of a monoclinic MB phase in Pb(Zn1/3Nb2/3)O3-4.5%PbTiO3 single crystals. High precision x-ray diffraction investigations of [110] field cooled crystals have shown a transformation sequence of cubic(C)→tetragonal(T)→orthorhombic(O)→monoclinic(MB), which is different from that previously reported [A.-E. Renault et al., J. Appl. Phys. 97, 044105 (2005)]. Beginning in the zero-field-cooled condition at 383 K, a rhombohedral (R)→MB→O sequence was observed with increasing field. Coexisting MB and O phases were then found upon removal of field, which fully transformed to MB on cooling to room temperature.

  1. Structural phase transition at the percolation threshold in epitaxial (La0.7Ca0.3MnO3)1-x:(MgO)x nanocomposite films.

    Science.gov (United States)

    Moshnyaga, V; Damaschke, B; Shapoval, O; Belenchuk, A; Faupel, J; Lebedev, O I; Verbeeck, J; van Tendeloo, G; Mücksch, M; Tsurkan, V; Tidecks, R; Samwer, K

    2003-04-01

    'Colossal magnetoresistance' in perovskite manganites such as La0.7Ca0.3MnO3 (LCMO), is caused by the interplay of ferro-paramagnetic, metal-insulator and structural phase transitions. Moreover, different electronic phases can coexist on a very fine scale resulting in percolative electron transport. Here we report on (LCMO)1-x:(MgO)x (0 strain. The largest colossal magnetoresistance of 10(5)% was observed at the percolation threshold in the conductivity at xc 0.3, which is coupled to a structural phase transition from orthorhombic (0 < x < or 0.1) to rhombohedral R3c structure (0.33 < or = x < or = 0.8). An increase of the Curie temperature for the Rc phase was observed. These results may provide a general method for controlling the magnetotransport properties of manganite-based composite films by appropriate choice of the second phase.

  2. Phase transformations in chalkogenides of germanium subgroup elements and in alloys on their base at high pressures

    International Nuclear Information System (INIS)

    Skums, V.F.; Skoropanov, A.S.; Vecher, A.A.

    1990-01-01

    An attempt was made to systematize and analyze the available data on behaviour of chalkogenides of germanium subgroup elements and their alloys at high pressures, as applied to the problem of their use as reference materials for pressure determination. It is shown that phase transformations, accompanied by sharp change of electric resistance, are observed in chalkogenides of cubic and rhombohedral structures (lead, tin (SnTe) and germanium (GeTe)) under the effect of high pressures. It was established that electric resistance in the region of phase transformation (electric signal) depended on the type and concentration of current carriers: electric sigual grew with decrease of current carrier concentration; substances with p-type of conductivity were characterized by lower electric signal, as compared to substances with n-conductivety

  3. Consistent Atomic Geometries and Electronic Structure of Five Phases of Potassium Niobate from Density-Functional Theory

    Directory of Open Access Journals (Sweden)

    Falko Schmidt

    2017-01-01

    Full Text Available We perform a comprehensive theoretical study of the structural and electronic properties of potassium niobate (KNbO3 in the cubic, tetragonal, orthorhombic, monoclinic, and rhombohedral phase, based on density-functional theory. The influence of different parametrizations of the exchange-correlation functional on the investigated properties is analyzed in detail, and the results are compared to available experimental data. We argue that the PBEsol and AM05 generalized gradient approximations as well as the RTPSS meta-generalized gradient approximation yield consistently accurate structural data for both the external and internal degrees of freedom and are overall superior to the local-density approximation or other conventional generalized gradient approximations for the structural characterization of KNbO3. Band-structure calculations using a HSE-type hybrid functional further indicate significant near degeneracies of band-edge states in all phases which are expected to be relevant for the optical response of the material.

  4. What can Fe stable isotopes tell us about magmas?

    DEFF Research Database (Denmark)

    Stausberg, Niklas

    the differentiation of magmas from the perspective of Fe stable isotopes, integrated with petrology, by studying igneous rocks and their constituent phases (minerals and glasses) from the Bushveld Complex, South Africa, Thingmuli, Iceland, Pantelleria, Italy, and the Bishop Tuff, USA. The findings are interpreted......The majority of the Earth’s crust is formed by magmas, and understanding their production and differentiation is important to interpret the geologic rock record. A powerful tool to investigate magmatic processes is the distribution of the stable isotopes of the major redox-sensitive element...... in magmas, Fe. Fe isotope compositions of magmatic rocks exhibit systematic differences, where the heaviest compositions are found in rhyolites and granites. Understanding of these systematics is complicated by a lack of constraints on Fe isotope fractionation among minerals and liquids under magmatic...

  5. Prediction of pressure induced structural phase transitions and internal mode frequency changes in solid N2+

    International Nuclear Information System (INIS)

    Etters, R.D.; Kobashi, K.; Chandrasekharan, V.

    1983-01-01

    A rhombohedral distortion of the Pm3n structure is introduced which shows that a low temperature phase transition occurs from P4 2 /mnm into the R3c calcite structure at P approx. = 19.2 kbar with a volume change of 0.125 cm 3 /mole. This transition agrees with recent Raman scattering measurements. Another transition from R3c into R3m is predicted at P approx. = 67.5 kbar, with a volume change of 0.1 cm 3 /mole. The pressure dependence of the intramolecular mode frequencies for the R3c structure is in reasonably good agreement with the two main branches observed experimentally

  6. Effect of Bi doping on morphotropic phase boundary and dielectric properties of PZT

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Shraddha; Acharya, Smita, E-mail: saha275@yahoo.com [Advanced Materials Research Laboratory, Department of Physics, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur-440033, M.S. India (India)

    2016-05-23

    In our present attempt, Pb{sub (1-x)}Bi{sub x}Zr{sub 0.52}Ti{sub 0.48}O{sub 3} [PBZT] {where x = 0, 0.05, 0.1} is synthesized by sol-gel route. Effect of Bi addition on structure, sinterability and dielectric properties are observed. The presence of morphotropic phase boundary (coexistence of tetragonal and rhombohedral symmetry) is confirmed by X-ray diffraction. Enhancement of sinterability after Bi doping is observed through a systematic sintering program. Frequency and temperature dependent dielectric constant are studied. Bi doping in PZT is found to enhance room temperature dielectric constant. However, at high temperature the dielectric constant of pure PZT is more than that of doped PZT.

  7. PHASE TRANSITION OF CaFeO2.5 AT HIGH TEMPERATURE

    Directory of Open Access Journals (Sweden)

    T Labii

    2011-12-01

    Full Text Available The numerous studies conducted on the structure of CaFeO2.5 showed that the material undergoes a series of transformations based on temperature. The first one appears around 700 K and indicates the evolution of the phasemagnetic material to a paramagnetic phase. At about 970 K the structure of CaFeO2.5 changes from rhombohedral to centered structure. Finally, around 1180 K it undergoes the transition to a structure that has been described as incommensurate modulated structure. We have observed the behavior of the material beyond this temperature by dilatometry, DSC and TGA. The tests conducted on a single crystal CaFeO2.5 confirm the changes already observed.For the first time there was a dilatometric anomaly (confirmed by DSC and TGA at 1310 K. This anomaly appears only in the crystallographic direction b which should probably be a  commensurate transformation of the material.

  8. Stable isotope separation by thermal diffusion

    International Nuclear Information System (INIS)

    Vasaru, Gheorghe

    2001-01-01

    Thermal diffusion in both gaseous and liquid phase has been subject of extensive experimental and theoretical investigations, especially after the invention of K. Clusius and G. Dickel of the thermal diffusion column, sixty three years ago. This paper gives a brief overview of the most important research and developments performed during the time at the National Institute for Research and Development for Isotopic and Molecular Technology (ITIM) at Cluj - Napoca, Romania in the field of separation of stable isotopes by thermal diffusion. An retrospective analysis of the research and results concerning isotope separation by thermal diffusion entails the following conclusions: - thermal diffusion is an adequate method for hydrogen isotope separation (deuterium and tritium) and for noble gas isotope separation (He, Ne, Ar, Kr, Xe); - thermal diffusion is attractive also for 13 C enrichment using methane as raw material for separation, when annual yields of up to 100 g are envisaged; - lately, the thermal diffusion appears to be chosen as a final enrichment step for 17 O. An obvious advantage of this method is its non-specificity, i.e. the implied equipment can be utilized for isotope separation of other chemical elements too. Having in view the low investment costs for thermal diffusion cascades the method appears economically attractive for obtaining low-scale, laboratory isotope production. The paper has the following content: 1. The principle of method; 2. The method's application; 3. Research in the field of thermal diffusion at ITIM; 4. Thermal diffusion cascades for N, C, Ne, Ar and Kr isotope separation; 5. Conclusion

  9. Applications of stable isotopes in clinical pharmacology

    NARCIS (Netherlands)

    Schellekens, Reinout C A; Stellaard, Frans; Woerdenbag, Herman J; Frijlink, Henderik W; Kosterink, Jos G W

    2011-01-01

    This review aims to present an overview of the application of stable isotope technology in clinical pharmacology. Three main categories of stable isotope technology can be distinguished in clinical pharmacology. Firstly, it is applied in the assessment of drug pharmacology to determine the

  10. Stable isotopes and biomarkers in microbial ecology

    NARCIS (Netherlands)

    Boschker, H.T.S.; Middelburg, J.J.

    2002-01-01

    The use of biomarkers in combination with stable isotope analysis is a new approach in microbial ecology and a number of papers on a variety of subjects have appeared. We will first discuss the techniques for analysing stable isotopes in biomarkers, primarily gas chromatography-combustion-isotope

  11. Modelling stable atmospheric boundary layers over snow

    NARCIS (Netherlands)

    Sterk, H.A.M.

    2015-01-01

    Thesis entitled:

    Modelling Stable Atmospheric Boundary Layers over Snow

    H.A.M. Sterk

    Wageningen, 29th of April, 2015

    Summary

    The emphasis of this thesis is on the understanding and forecasting of the Stable Boundary Layer (SBL) over snow-covered surfaces. SBLs

  12. Structure of acid-stable carmine.

    Science.gov (United States)

    Sugimoto, Naoki; Kawasaki, Yoko; Sato, Kyoko; Aoki, Hiromitsu; Ichi, Takahito; Koda, Takatoshi; Yamazaki, Takeshi; Maitani, Tamio

    2002-02-01

    Acid-stable carmine has recently been distributed in the U.S. market because of its good acid stability, but it is not permitted in Japan. We analyzed and determined the structure of the major pigment in acid-stable carmine, in order to establish an analytical method for it. Carminic acid was transformed into a different type of pigment, named acid-stable carmine, through amination when heated in ammonia solution. The features of the structure were clarified using a model compound, purpurin, in which the orientation of hydroxyl groups on the A ring of the anthraquinone skeleton is the same as that of carminic acid. By spectroscopic means and the synthesis of acid-stable carmine and purpurin derivatives, the structure of the major pigment in acid-stable carmine was established as 4-aminocarminic acid, a novel compound.

  13. Finding Non-Zero Stable Fixed Points of the Weighted Kuramoto model is NP-hard

    OpenAIRE

    Taylor, Richard

    2015-01-01

    The Kuramoto model when considered over the full space of phase angles [$0,2\\pi$) can have multiple stable fixed points which form basins of attraction in the solution space. In this paper we illustrate the fundamentally complex relationship between the network topology and the solution space by showing that determining the possibility of multiple stable fixed points from the network topology is NP-hard for the weighted Kuramoto Model. In the case of the unweighted model this problem is shown...

  14. Direct transition from a stable equilibrium to quasiperiodicity in non-smooth systems

    DEFF Research Database (Denmark)

    Zhusubaliyev, Z.T.; Mosekilde, Erik

    2008-01-01

    The purpose of this Letter is to show how a border-collision bifurcation in a piecewise-smooth dynamical system can produce a direct transition from a stable equilibrium point to a two-dimensional invariant torus. Considering a system of nonautonomous differential equations describing the behavior...... of a power electronic DC/DC converter, we first determine the chart of dynamical modes and show that there is a region of parameter space in which the system has a single stable equilibrium point. Under variation of the parameters, this equilibrium may collide with a discontinuity boundary between two smooth...... regions in phase space. When this happens, one can observe a number of different bifurcation scenarios. One scenario is the continuous transformation of the stable equilibrium into a stable period-1 cycle. Another is the transformation of the stable equilibrium into an unstable period-1 cycle with complex...

  15. Stable Blind Deconvolution over the Reals from Additional Autocorrelations

    KAUST Repository

    Walk, Philipp

    2017-10-22

    Recently the one-dimensional time-discrete blind deconvolution problem was shown to be solvable uniquely, up to a global phase, by a semi-definite program for almost any signal, provided its autocorrelation is known. We will show in this work that under a sufficient zero separation of the corresponding signal in the $z-$domain, a stable reconstruction against additive noise is possible. Moreover, the stability constant depends on the signal dimension and on the signals magnitude of the first and last coefficients. We give an analytical expression for this constant by using spectral bounds of Vandermonde matrices.

  16. Grain size dependent phase stabilities and presence of a monoclinic (Pm) phase in the MPB region of (1-x)Bi(Mg_1_/_2Ti_1_/_2)O_3_-_xPbTiO_3

    International Nuclear Information System (INIS)

    Upadhyay, A.; Singh, A.K.

    2016-01-01

    The results of the room temperature structural studies on (1-x)Bi(Mg_1_/_2Ti_1_/_2)O_3_-_xPbTiO_3 ceramics using Rietveld analysis of the powder X-ray diffraction data in the composition range 0.28≤x≤0.45 are presented. The morphotropic phase boundary region exhibits coexistence of monoclinic (space group Pm) and tetragonal (space group P4mm) phases in the composition range 0.33≤x≤0.40. The structure is nearly single phase monoclinic (space group Pm) in the composition range 0.28≤x≤0.32. The structure for the compositions with x≥0.45 is found to be predominantly tetragonal with space group P4mm. Rietveld refinement of the structure rules out the coexistence of rhombohedral and tetragonal phases in the morphotropic phase boundary region reported by earlier authors. The Rietveld structure analysis for the sample x=0.35 calcined at various temperatures reveals that phase fraction of the coexisting phases in the morphotropic phase boundary region varies with grain size. The structural parameters of the two coexisting phases also change slightly with changing grain size. (author)

  17. Phase transition and multicolor luminescence of Eu2+/Mn2+-activated Ca3(PO4)2 phosphors

    International Nuclear Information System (INIS)

    Li, Kai; Chen, Daqin; Xu, Ju; Zhang, Rui; Yu, Yunlong; Wang, Yuansheng

    2014-01-01

    Graphical abstract: We have synthesized Eu 2+ doped and Eu 2+ /Mn 2+ co-doped Ca 3 (PO 4 ) 2 phosphors. The emitting color varies from blue to green with increasing of Eu 2+ content for the Eu 2+ -doped phosphor, and the quantum yield of the 0.05Eu 2+ : Ca 2.95 (PO 4 ) 2 sample reaches 56.7%. Interestingly, Mn 2+ co-doping into Eu 2+ : Ca 3 (PO 4 ) 2 leads to its phase transition from orthorhombic to rhombohedral, and subsequently generates tunable multi-color luminescence from green to red via Eu 2+ → Mn 2+ energy transfer. - Highlights: • A series of novel Eu 2+ : Ca 3 (PO 4 ) 2 phosphors were successfully synthesized. • Phase transition of Ca 3 (PO 4 ) 2 from orthorhombic to rhombohedral occurred when Mn 2+ ions were doped. • The phosphors exhibited tunable multi-color luminescence. • The quantum yield of 0.05Eu 2+ : Ca 2.95 (PO 4 ) 2 phosphor can reach 56.7%. • The analyses of phosphors were carried out by many measurements. - Abstract: Intense blue-green-emitting Eu 2+ : Ca 3 (PO 4 ) 2 and tunable multicolor-emitting Eu 2+ /Mn 2+ : Ca 3 (PO 4 ) 2 phosphors are prepared via a solid-state reaction route. Eu 2+ -doped orthorhombic Ca 3 (PO 4 ) 2 phosphor exhibits a broad emission band in the wavelength range of 400–700 nm with a maximum quantum yield of 56.7%, and the emission peak red-shifts gradually from 479 to 520 nm with increase of Eu 2+ doping content. Broad excitation spectrum (250–420 nm) of Eu 2+ : Ca 3 (PO 4 ) 2 matches well with the near-ultraviolet LED chip, indicating its potential applications as tri-color phosphors in white LEDs. Interestingly, Mn 2+ co-doping into Eu 2+ : Ca 3 (PO 4 ) 2 leads to its phase transition from orthorhombic to rhombohedral, and subsequently generates tunable multi-color luminescence from green to red via Eu 2+ → Mn 2+ energy transfer, under 365 nm UV lamp excitation

  18. Novel Quantum Phases at Interfaces

    Science.gov (United States)

    2014-12-12

    defined quasiparticle and the system cannot be adequately described by an electronic band structure. The chief theoretical challenges for the study of...electronic quasiparticle weight is proportional to the expectation value of the rotor field. The resulting theory typically has two dis- tinct stable phases...band structure is well defined, while in the strongly interacting phase the quasiparticle weight vanishes due to strong rotor fluc- tuations

  19. Grain size dependent phase stabilities and presence of a monoclinic (Pm) phase in the morphotropic phase boundary region of (1−x)Bi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}-xPbTiO{sub 3} piezoceramics

    Energy Technology Data Exchange (ETDEWEB)

    Upadhyay, Ashutosh; Singh, Akhilesh Kumar, E-mail: akhilesh-bhu@yahoo.com, E-mail: aksingh.mst@itbhu.ac.in [School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

    2015-04-14

    Results of the room temperature structural studies on (1−x)Bi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}-xPbTiO{sub 3} ceramics using Rietveld analysis of the powder x-ray diffraction data in the composition range 0.28 ≤ x ≤ 0.45 are presented. The morphotropic phase boundary region exhibits coexistence of monoclinic (space group Pm) and tetragonal (space group P4 mm) phases in the composition range 0.33 ≤ x ≤ 0.40. The structure is nearly single phase monoclinic (space group Pm) in the composition range 0.28 ≤ x ≤ 0.32. The structure for the compositions with x ≥ 0.45 is found to be predominantly tetragonal with space group P4 mm. Rietveld refinement of the structure rules out the coexistence of rhombohedral and tetragonal phases in the morphotropic phase boundary region reported by earlier authors. The Rietveld structure analysis for the sample x = .35 calcined at various temperatures reveals that phase fraction of the coexisting phases in the morphotropic phase boundary region varies with grain size. The structural parameters of the two coexisting phases also change slightly with changing grain size.

  20. Ferroelastic Phase Transition in Pb_3(PO_4)_2 Studied by Computer Simulation

    Science.gov (United States)

    Parlinski, K.; Kawazoe, Y.

    1997-01-01

    A model of lead phosphate which describes its rhombohedral-monoclinic improper ferroelastic phase transition is proposed. It contains a reduced number of degrees of freedom but it is constructed consistently with symmetry changes at the phase transition. Potential parameters of the model are derived from available experimental data. The crystallites of 25× 25× 25 and 121× 121 × 25 unit cells have been simulated by the molecular-dynamics technique. The results determine the phase transition at the L point of reciprocal space, the order parameter, and the temperature behavior of monoclinic lattice parameters. In the rhombohedral phase the calculated dynamical structure factor shows inelastic peaks from which a soft branch of underdamped phonons has been established. The model has been used to calculate a diffuse scattering function which shows above T_c a maximum at an incommensurate wave vector located along the L F line of the Brillouin zone. The mentioned line is parallel to the ternary symmetry axis. On the basis of the above results we were able to vizualize the nature of the dynamical monoclinic microdomains persisting in the high-temperature rhombohedral phase. It has been shown that above T_c the fluctuations can be treated as temporary orientational monoclinic microdomains. Each type of microdomains always contains an irregular sequence of antiphase domains. Un modèle permettant de décrire la transition de phase ferroélastique impropre, rhomboédrique-monoclinique, du phosphate de plomb est proposé ci-dessous. Il est construit à partir d'un nombre réduit de degrés de liberté, tout en tenant compte des changements de symétrie caractéristique de la transition de phase. Les paramètres du modèle sont déduits quantitativement des résultats expérimentaux disponibles. La technique de dynamique moléculaire a permis de simuler le comportement des cristallites comportant 25× 25× 25 et 121× 121 × 25 mailles. Les résultats permettent de d

  1. Force production during squats performed with a rotational resistance device under stable versus unstable conditions.

    Science.gov (United States)

    Moras, Gerard; Vázquez-Guerrero, Jairo

    2015-11-01

    [Purpose] Force production during a squat action on a rotational resistance device (RRD) under stable and unstable conditions. [Subjects and Methods] Twenty-one healthy males were asked to perform six sets of six repetitions of squats on an RRD on either stable or unstable surfaces. The stable and unstable sets were performed on different days. Muscular outputs were obtained from a linear encoder and a strain gauge fixed to a vest. [Results] Overall, the results showed no significant differences for any of the dependent variables across exercise modes. Forcemean outputs were higher in the concentric phase than in the eccentric phase for each condition, but there were no differences in velocity, time or displacement. The forcepeak was similar in the eccentric and concentric phases of movement under both stable and unstable conditions. There were no significant differences in forcemean between sets per condition or between conditions. [Conclusion] These results suggest that performing squats with a RRD achieves similar forcemean and forcepeak under stable and unstable conditions. The forcepeak produced is also similar in concentric and eccentric phases.

  2. Ballooning stable high beta tokamak equilibria

    International Nuclear Information System (INIS)

    Tuda, Takashi; Azumi, Masafumi; Kurita, Gen-ichi; Takizuka, Tomonori; Takeda, Tatsuoki

    1981-04-01

    The second stable regime of ballooning modes is numerically studied by using the two-dimensional tokamak transport code with the ballooning stability code. Using the simple FCT heating scheme, we find that the plasma can locally enter this second stable regime. And we obtained equilibria with fairly high beta (β -- 23%) stable against ballooning modes in a whole plasma region, by taking into account of finite thermal diffusion due to unstable ballooning modes. These results show that a tokamak fusion reactor can operate in a high beta state, which is economically favourable. (author)

  3. Development of stable isotope manufacturing in Russia

    International Nuclear Information System (INIS)

    Pokidychev, A.; Pokidycheva, M.

    1999-01-01

    For the past 25 years, Russia has relied heavily on the electromagnetic separation process for the production of middle and heavy mass stable isotopes. The separation of most light isotopes had been centered in Georgia which, after the collapse of the USSR, left Russia without this capability. In the mid-1970s, development of centrifuge technology for the separation of stable isotopes was begun. Alternative techniques such as laser separation, physical-chemical methods, and ion cyclotron resonance have also been investigated. Economic considerations have played a major role in the development and current status of the stable isotope enrichment capabilities of Russia

  4. Dispersive-cavity actively mode-locked fiber laser for stable radio frequency delivery

    International Nuclear Information System (INIS)

    Dai, Yitang; Wang, Ruixin; Yin, Feifei; Xu, Kun; Li, Jianqiang; Lin, Jintong

    2013-01-01

    We report a novel technique for highly stable transfer of a radio frequency (RF) comb over long optical fiber link, which is highly dispersive and is a part of an actively mode-locked fiber laser. Phase fluctuation along the fiber link, which is mainly induced by physical vibration and temperature fluctuations, is automatically compensated by the self-adapted wavelength shifting. Without phase-locking loop or any tunable parts, stable radio frequency is transferred over a 2-km fiber link, with a time jitter suppression ratio larger than 110. (letter)

  5. Long term thermal energy storage with stable supercooled sodium acetate trihydrate

    DEFF Research Database (Denmark)

    Dannemand, Mark; Schultz, Jørgen M.; Johansen, Jakob Berg

    2015-01-01

    Utilizing stable supercooling of sodium acetate trihydrate makes it possible to store thermal energy partly loss free. This principle makes seasonal heat storage in compact systems possible. To keep high and stable energy content and cycling stability phase separation of the storage material must...... it expands and will cause a pressure built up in a closed chamber which might compromise stability of the supercooling. This can be avoided by having an air volume above the phase change material connected to an external pressure less expansion tank. Supercooled sodium acetate trihydrate at 20 °C stores up...

  6. Membrane-Sculpting BAR Domains Generate Stable Lipid Microdomains

    Science.gov (United States)

    Zhao, Hongxia; Michelot, Alphée; Koskela, Essi V.; Tkach, Vadym; Stamou, Dimitrios; Drubin, David G.; Lappalainen, Pekka

    2014-01-01

    SUMMARY Bin-Amphiphysin-Rvs (BAR) domain proteins are central regulators of many cellular processes involving membrane dynamics. BAR domains sculpt phosphoinositide-rich membranes to generate membrane protrusions or invaginations. Here, we report that, in addition to regulating membrane geometry, BAR domains can generate extremely stable lipid microdomains by “freezing” phosphoinositide dynamics. This is a general feature of BAR domains, because the yeast endocytic BAR and Fes/CIP4 homology BAR (F-BAR) domains, the inverse BAR domain of Pinkbar, and the eisosomal BAR protein Lsp1 induced phosphoinositide clustering and halted lipid diffusion, despite differences in mechanisms of membrane interactions. Lsp1 displays comparable low diffusion rates in vitro and in vivo, suggesting that BAR domain proteins also generate stable phosphoinositide microdomains in cells. These results uncover a conserved role for BAR superfamily proteins in regulating lipid dynamics within membranes. Stable microdomains induced by BAR domain scaffolds and specific lipids can generate phase boundaries and diffusion barriers, which may have profound impacts on diverse cellular processes. PMID:24055060

  7. From stable to unstable anomaly-induced inflation

    Science.gov (United States)

    Netto, Tibério de Paula; Pelinson, Ana M.; Shapiro, Ilya L.; Starobinsky, Alexei A.

    2016-10-01

    Quantum effects derived through conformal anomaly lead to an inflationary model that can be either stable or unstable. The unstable version requires a large dimensionless coefficient of about 5× {10}^8 in front of the {R}^2 term that results in the inflationary regime in the R+{R}^2 ("Starobinsky") model being a generic intermediate attractor. In this case the non-local terms in the effective action are practically irrelevant, and there is a `graceful exit' to a low curvature matter-like dominated stage driven by high-frequency oscillations of R - scalarons, which later decay to pairs of all particles and antiparticles, with the amount of primordial scalar (density) perturbations required by observations. The stable version is a genuine generic attractor, so there is no exit from it. We discuss a possible transition from stable to unstable phases of inflation. It is shown that this transition is automatic if the sharp cut-off approximation is assumed for quantum corrections in the period of transition. Furthermore, we describe two different quantum mechanisms that may provide a required large {R}^2-term in the transition period.

  8. From stable to unstable anomaly-induced inflation

    Energy Technology Data Exchange (ETDEWEB)

    Paula Netto, Tiberio de [Universidade Federal de Juiz de Fora, Departamento de Fisica, ICE, Juiz de Fora, MG (Brazil); Pelinson, Ana M. [Universidade Federal de Santa Catarina, Departamento de Fisica, CFM, Bairro da Trindade, Florianopolis, SC (Brazil); Shapiro, Ilya L. [Universidade Federal de Juiz de Fora, Departamento de Fisica, ICE, Juiz de Fora, MG (Brazil); Tomsk State Pedagogical University and Tomsk State University, Tomsk (Russian Federation); Starobinsky, Alexei A. [L.D. Landau Institute for Theoretical Physics RAS, Moscow (Russian Federation); Utrecht University, Department of Physics and Astronomy, Institute for Theoretical Physics, Utrecht (Netherlands)

    2016-10-15

    Quantum effects derived through conformal anomaly lead to an inflationary model that can be either stable or unstable. The unstable version requires a large dimensionless coefficient of about 5 x 10{sup 8} in front of the R{sup 2} term that results in the inflationary regime in the R+R{sup 2} (''Starobinsky'') model being a generic intermediate attractor. In this case the non-local terms in the effective action are practically irrelevant, and there is a 'graceful exit' to a low curvature matter-like dominated stage driven by high-frequency oscillations of R - scalarons, which later decay to pairs of all particles and antiparticles, with the amount of primordial scalar (density) perturbations required by observations. The stable version is a genuine generic attractor, so there is no exit from it. We discuss a possible transition from stable to unstable phases of inflation. It is shown that this transition is automatic if the sharp cut-off approximation is assumed for quantum corrections in the period of transition. Furthermore, we describe two different quantum mechanisms that may provide a required large R{sup 2}-term in the transition period. (orig.)

  9. Stable Isotope Group 1982 progress report

    International Nuclear Information System (INIS)

    Stewart, M.K.

    1983-06-01

    The work of the Stable Isotope Group of the Institute of Nuclear Sciences during 1982, in the fields of isotope geology, isotope hydrology, geochronology, isotope biology and mass spectrometer instrumentation, is described

  10. Bartolome Island, Galapagos Stable Oxygen Calibration Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Galapagos Coral Stable Oxygen Calibration Data. Sites: Bartolome Island: 0 deg, 17'S, 90 deg 33' W. Champion Island: 1 deg, 15'S, 90 deg, 05' W. Urvina Bay (Isabela...

  11. Stable Isotope Group 1983 progress report

    International Nuclear Information System (INIS)

    Stewart, M.K.

    1984-06-01

    The work of the Stable Isotope Group of the Institute of Nuclear Sciences in the fields of isotope geology, isotope hydrology, geochronology, isotope biology and related fields, and mass spectrometer instrumentation, during 1983, is described

  12. Tellurium Stable Isotopes as a Paleoredox Proxy

    Science.gov (United States)

    Wasserman, N.; Johnson, T. M.

    2017-12-01

    Despite arguments for variably-oxygenated shallow waters and anoxic deep marine waters, which delayed animal development until the Neoproterozoic Oxidation Event, the magnitude of atmospheric oxygen during the Proterozoic is still uncertain [1]. The evidence for low pO2 (<0.1-1% PAL) is based on geochemical and isotopic proxies, which track the mobilization of Fe and Mn on the continents. For example, large chromium isotope shifts occur at the Neoproterozoic Oxidation Event due to the initiation of Cr redox cycling, but this proxy is insensitive to fluctuations in the lower-pO2 conditions at other times during the Proterozoic. Tellurium, a metalloid with a lower threshold to oxidation, may be sensitive to pO2 shifts in a lower range. In the reduced forms, Te(-II) and Te(0), the element is insoluble and immobile. However, in the more oxidized phases, Te(IV) and Te(VI), Te can form soluble oxyanions (though it tends to adsorb to Fe-oxyhydroxides and clays) [2]. Te stable isotopes have been shown to fractionate during abiotic or biologic reduction of Te(VI) or Te(IV) to elemental Te(0) [3, 4]. Utilizing hydride generation MC-ICP-MS, we are able to obtain high precision (2σ 0.04‰) measurements of δ128Te/125Te for natural samples containing < 10 ng of Te. A suite of Phanerozoic and Proterozoic ironstones show significant variation in δ128Te/125Te (<0.5‰), suggesting that the Te redox cycle was active during the Proterozoic. Future directions will include Te isotope measurements of Precambrian paleosols to determine natural isotope variation before the Great Oxidation Event and experiments to determine fractionation during adsorption to Fe-oxyhydroxides. [1] Planavsky et al. (2014) Science 346 (6209), pp. 635-638 [2] Qin et al. (2017) Environmental Science and Technology 51 (11), pp 6027-6035 [3] Baesman et al. (2007) Applied Environmental Microbiology 73 (7), pp 2135-2143 [4] Smithers and Krause (1968) Canadian Journal of Chemistry 46(4): pp 583-591

  13. Stable atomic hydrogen: Polarized atomic beam source

    International Nuclear Information System (INIS)

    Niinikoski, T.O.; Penttilae, S.; Rieubland, J.M.; Rijllart, A.

    1984-01-01

    We have carried out experiments with stable atomic hydrogen with a view to possible applications in polarized targets or polarized atomic beam sources. Recent results from the stabilization apparatus are described. The first stable atomic hydrogen beam source based on the microwave extraction method (which is being tested ) is presented. The effect of the stabilized hydrogen gas density on the properties of the source is discussed. (orig.)

  14. Quantum dot-polymer conjugates for stable luminescent displays.

    Science.gov (United States)

    Ghimire, Sushant; Sivadas, Anjaly; Yuyama, Ken-Ichi; Takano, Yuta; Francis, Raju; Biju, Vasudevanpillai

    2018-05-23

    The broad absorption of light in the UV-Vis-NIR region and the size-based tunable photoluminescence color of semiconductor quantum dots make these tiny crystals one of the most attractive antennae in solar cells and phosphors in electrooptical devices. One of the primary requirements for such real-world applications of quantum dots is their stable and uniform distribution in optically transparent matrices. In this work, we prepare transparent thin films of polymer-quantum dot conjugates, where CdSe/ZnS quantum dots are uniformly distributed at high densities in a chitosan-polystyrene copolymer (CS-g-PS) matrix. Here, quantum dots in an aqueous solution are conjugated to the copolymer by a phase transfer reaction. With the stable conjugation of quantum dots to the copolymer, we prevent undesired phase separation between the two and aggregation of quantum dots. Furthermore, the conjugate allows us to prepare transparent thin films in which quantum dots are uniformly distributed at high densities. The CS-g-PS copolymer helps us in not only preserving the photoluminescence properties of quantum dots in the film but also rendering excellent photostability to quantum dots at the ensemble and single particle levels, making the conjugate a promising material for photoluminescence-based devices.

  15. Development of Stable Solidification Method for Insoluble Ferrocyanides-13170

    Energy Technology Data Exchange (ETDEWEB)

    Ikarashi, Yuki; Masud, Rana Syed; Mimura, Hitoshi [Dept. of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Aramaki-Aza-Aoba6-6-01-2, Sendai, 980-8579 (Japan); Ishizaki, Eiji; Matsukura, Minoru [UNION SHOWA K.K. 17-20, Mita 2-chome, Minato-ku, Tokyo 108-0073 (Japan)

    2013-07-01

    The development of stable solidification method of insoluble ferrocyanides sludge is an important subject for the safety decontamination in Fukushima NPP-1. By using the excellent immobilizing properties of zeolites such as gas trapping ability and self-sintering properties, the stable solidification of insoluble ferrocyanides was accomplished. The immobilization ratio of Cs for K{sub 2}[CoFe(CN){sub 6}].nH{sub 2}O saturated with Cs{sup +} ions (Cs{sub 2}[CoFe(CN){sub 6}].nH{sub 2}O) was estimated to be less than 0.1% above 1,000 deg. C; the adsorbed Cs{sup +} ions are completely volatilized. In contrast, the novel stable solid form was produced by the press-sintering of the mixture of Cs{sub 2}[CoFe(CN){sub 6}].nH{sub 2}O and zeolites at higher temperature of 1,000 deg. C and 1,100 deg. C; Cs volatilization and cyanide release were completely depressed. The immobilization ratio of Cs, under the mixing conditions of Cs{sub 2}[CoFe(CN){sub 6}].nH{sub 2}O:CP= 1:1 and calcining temperature: 1,000 deg. C, was estimated to be nearly 100%. As for the kinds of zeolites, natural mordenite (NM), clinoptilolite (CP) and Chabazite tended to have higher immobilization ratio compared to zeolite A. This may be due to the difference in the phase transformation between natural zeolites and synthetic zeolite A. In the case of the composites (K{sub 2-X}Ni{sub X/2}[NiFe(CN){sub 6}].nH{sub 2}O loaded natural mordenite), relatively high immobilization ratio of Cs was also obtained. This method using zeolite matrices can be applied to the stable solidification of the solid wastes of insoluble ferrocyanides sludge. (authors)

  16. Local Search Approaches in Stable Matching Problems

    Directory of Open Access Journals (Sweden)

    Toby Walsh

    2013-10-01

    Full Text Available The stable marriage (SM problem has a wide variety of practical applications, ranging from matching resident doctors to hospitals, to matching students to schools or, more generally, to any two-sided market. In the classical formulation, n men and n women express their preferences (via a strict total order over the members of the other sex. Solving an SM problem means finding a stable marriage where stability is an envy-free notion: no man and woman who are not married to each other would both prefer each other to their partners or to being single. We consider both the classical stable marriage problem and one of its useful variations (denoted SMTI (Stable Marriage with Ties and Incomplete lists where the men and women express their preferences in the form of an incomplete preference list with ties over a subset of the members of the other sex. Matchings are permitted only with people who appear in these preference lists, and we try to find a stable matching that marries as many people as possible. Whilst the SM problem is polynomial to solve, the SMTI problem is NP-hard. We propose to tackle both problems via a local search approach, which exploits properties of the problems to reduce the size of the neighborhood and to make local moves efficiently. We empirically evaluate our algorithm for SM problems by measuring its runtime behavior and its ability to sample the lattice of all possible stable marriages. We evaluate our algorithm for SMTI problems in terms of both its runtime behavior and its ability to find a maximum cardinality stable marriage. Experimental results suggest that for SM problems, the number of steps of our algorithm grows only as O(n log(n, and that it samples very well the set of all stable marriages. It is thus a fair and efficient approach to generate stable marriages. Furthermore, our approach for SMTI problems is able to solve large problems, quickly returning stable matchings of large and often optimal size, despite the

  17. A novel perovskite oxide chemically designed to show multiferroic phase boundary with room-temperature magnetoelectricity

    Science.gov (United States)

    Fernández-Posada, Carmen M.; Castro, Alicia; Kiat, Jean-Michel; Porcher, Florence; Peña, Octavio; Algueró, Miguel; Amorín, Harvey

    2016-09-01

    There is a growing activity in the search of novel single-phase multiferroics that could finally provide distinctive magnetoelectric responses at room temperature, for they would enable a range of potentially disruptive technologies, making use of the ability of controlling polarization with a magnetic field or magnetism with an electric one (for example, voltage-tunable spintronic devices, uncooled magnetic sensors and the long-searched magnetoelectric memory). A very promising novel material concept could be to make use of phase-change phenomena at structural instabilities of a multiferroic state. Indeed, large phase-change magnetoelectric response has been anticipated by a first-principles investigation of the perovskite BiFeO3-BiCoO3 solid solution, specifically at its morphotropic phase boundary between multiferroic polymorphs of rhombohedral and tetragonal symmetries. Here, we report a novel perovskite oxide that belongs to the BiFeO3-BiMnO3-PbTiO3 ternary system, chemically designed to present such multiferroic phase boundary with enhanced ferroelectricity and canted ferromagnetism, which shows distinctive room-temperature magnetoelectric responses.

  18. RF phase distribution systems at the SLC

    International Nuclear Information System (INIS)

    Jobe, R.K.; Schwarz, H.D.

    1989-04-01

    Modern large linear accelerators require RF distribution systems with minimal phase drifts and errors. Through the use of existing RF coaxial waveguides, and additional installation of phase reference cables and monitoring equipment, stable RF distribution for the SLC has been achieved. This paper discusses the design and performance of SLAC systems, and some design considerations for future colliders. 6 refs., 4 figs

  19. Method of stripping plutonium from tributyl phosphate solution which contains dibutyl phosphate-plutonium stable complexes

    International Nuclear Information System (INIS)

    Ochsenfeld, W.; Schmieder, H.

    1976-01-01

    Fast breeder fuel elements which have been highly burnt-up are reprocessed by extracting uranium and plutonium into an organic solution containing tributyl phosphate. The tributyl phosphate degenerates at least partially into dibutyl phosphate and monobutyl phosphate, which form stable complexes with tetravalent plutonium in the organic solution. This tetravalent plutonium is released from its complexed state and stripped into aqueous phase by contacting the organic solution with an aqueous phase containing tetravalent uranium. 6 claims, 1 drawing figure

  20. Relations between temperature coefficients of permittivity and elastic compliances in PZT ceramics near the morphotropic phase boundary.

    Science.gov (United States)

    Boudys, M

    1991-01-01

    Variations of temperature coefficients of permittivity epsilon(33)(T), elastic compliances at constant electric fields s(11)(E), and constant polarization s(11)(P) with a Zr/Ti ratio of Pb(Zr(x)Ti(1-x))O(3) and Pb[(Sb(1/3)Mn(2/3))(0.05)Zr(x)Ti (0.95-x)]O(3) solid solutions, were investigated. Relations between temperature coefficients of epsilon(33)(T ), S(11)(E), and S(11) (P) were theoretically derived; a discrepancy was found between theoretical relations and experimental results. On the basis of the observed discrepancy, it is proposed that some extrinsic effects arising from the motion of interphase boundaries between the tetragonal and the rhombohedral phases which exist in grains contribute to values of both elastic compliances.

  1. Metabolic studies in man using stable isotopes

    International Nuclear Information System (INIS)

    Faust, H.; Jung, K.; Krumbiegel, P.

    1993-01-01

    In this project, stable isotope compounds and stable isotope pharmaceuticals were used (with emphasis on the application of 15 N) to study several aspects of nitrogen metabolism in man. Of the many methods available, the 15 N stable isotope tracer technique holds a special position because the methodology for application and nitrogen isotope analysis is proven and reliable. Valid routine methods using 15 N analysis by emission spectrometry have been demonstrated. Several methods for the preparation of biological material were developed during our participation in the Coordinated Research Programme. In these studies, direct procedures (i.e. use of diluted urine as a samples without chemical preparation) or rapid isolation methods were favoured. Within the scope of the Analytical Quality Control Service (AQCS) enriched stable isotope reference materials for medical and biological studies were prepared and are now available through the International Atomic Energy Agency. The materials are of special importance as the increasing application of stable isotopes as tracers in medical, biological and agricultural studies has focused interest on reliable measurements of biological material of different origin. 24 refs

  2. Characteristics of the stress-induced formation of R-phase in ultrafine-grained NiTi shape memory wire

    International Nuclear Information System (INIS)

    Olbricht, J.; Yawny, A.; Pelegrina, J.L.; Eggeler, G.; Yardley, V.A.

    2013-01-01

    Highlights: •We investigated the stress-induced formation of R-phase in NiTi shape memory wires. •The R-phase related strains were isolated from the overall stress-strain-behavior. •The stress–strain characteristics of R-phase suggest a homogeneous transformation. •Thermography confirms the homogeneous R-phase formation in ultrafine-grained NiTi. -- Abstract: The transformation between the cubic B2 and monoclinic B19′ phases in ultrafine-grained pseudoelastic NiTi can occur as a two-step process involving the intermediate rhombohedral R-phase. Experimental work using differential scanning calorimetry, electrical resistance measurements and transmission electron microscopy has demonstrated the formation of this intermediate phase during thermal cycling and during mechanical loading. In the present paper, complementary mechanical and thermographic results are presented which allow to further assess the character of the stress-induced R-phase formation. The transformation from B2 to R-phase is demonstrated to occur homogeneously within the gauge length rather than via advancing Lüders-type transition regions as it is the case in the localized transformation from B2 or R-phase to B19′

  3. Cesium and its analogs, rubidium and potassium, in rhombohedral [NaZr2(PO4)3 type] and cubic (langbeinite type) phosphates: 2. Properties: behavior on heating, in aqueous solutions, and in salt melts

    International Nuclear Information System (INIS)

    Orlova, A.I.; Orlova, V.A.; Buchirin, A.V.; Korchenkin, K.K.; Beskrovnyj, A.I.; ); Demarin, V.T.

    2005-01-01

    The properties (behavior on heating, in aqueous solutions, and in salt melts) of orthophosphates A 2 RM(PO 4 ) 3 , A 2 B 0.5 Zr 1.5 (PO 4 ) 3 , and ABR 2 (PO 4 ) 3 [A = K, Rb, Cs; B = Mg, Sr, Ba; R = Ga, Fe, Cr, Ln (Ce-Lu)] crystallizing in the structure of langbeinite mineral (cubic system, space group P2 1 3, Z = 4) were studied and compared with those of NaZr 2 (PO 4 ) 3 type phosphates. The thermal transformations of the structure and the influence of temperature on the distortion of the framework-forming polyhedra were examined. The volatilization of cesium, in particular, from the solid phase in the course of its formation, was evaluated. The rates of cesium and barium leaching at 90 and 95 deg C were determined [ru

  4. Perspective: Highly stable vapor-deposited glasses

    Science.gov (United States)

    Ediger, M. D.

    2017-12-01

    This article describes recent progress in understanding highly stable glasses prepared by physical vapor deposition and provides perspective on further research directions for the field. For a given molecule, vapor-deposited glasses can have higher density and lower enthalpy than any glass that can be prepared by the more traditional route of cooling a liquid, and such glasses also exhibit greatly enhanced kinetic stability. Because vapor-deposited glasses can approach the bottom of the amorphous part of the potential energy landscape, they provide insights into the properties expected for the "ideal glass." Connections between vapor-deposited glasses, liquid-cooled glasses, and deeply supercooled liquids are explored. The generality of stable glass formation for organic molecules is discussed along with the prospects for stable glasses of other types of materials.

  5. Concentration of stable elements in food products

    International Nuclear Information System (INIS)

    Montford, M.A.; Shank, K.E.; Hendricks, C.; Oakes, T.W.

    1980-01-01

    Food samples were taken from commercial markets and analyzed for stable element content. The concentrations of most stable elements (Ag, Al, As, Au, Ba, Br, Ca, Ce, Cl, Co, Cr, Cs, Cu, Fe, Hf, I, K, La, Mg, Mn, Mo, Na, Rb, Sb, Sc, Se, Sr, Ta, Th, Ti, V, Zn, Zr) were determined using multiple-element neutron activation analysis, while the concentrations of other elements (Cd, Hg, Ni, Pb) were determined using atomic absorption. The relevance of the concentrations found are noted in relation to other literature values. An earlier study was extended to include the determination of the concentration of stable elements in home-grown products in the vicinity of the Oak Ridge National Laboratory. Comparisons between the commercial and local food-stuff values are discussed

  6. Stable Chimeras and Independently Synchronizable Clusters

    Science.gov (United States)

    Cho, Young Sul; Nishikawa, Takashi; Motter, Adilson E.

    2017-08-01

    Cluster synchronization is a phenomenon in which a network self-organizes into a pattern of synchronized sets. It has been shown that diverse patterns of stable cluster synchronization can be captured by symmetries of the network. Here, we establish a theoretical basis to divide an arbitrary pattern of symmetry clusters into independently synchronizable cluster sets, in which the synchronization stability of the individual clusters in each set is decoupled from that in all the other sets. Using this framework, we suggest a new approach to find permanently stable chimera states by capturing two or more symmetry clusters—at least one stable and one unstable—that compose the entire fully symmetric network.

  7. On some topological properties of stable measures

    DEFF Research Database (Denmark)

    Nielsen, Carsten Krabbe

    1996-01-01

    Summary The paper shows that the set of stable probability measures and the set of Rational Beliefs relative to a given stationary measure are closed in the strong topology, but not closed in the topology of weak convergence. However, subsets of the set of stable probability measures which...... are characterized by uniformity of convergence of the empirical distribution are closed in the topology of weak convergence. It is demonstrated that such subsets exist. In particular, there is an increasing sequence of sets of SIDS measures who's union is the set of all SIDS measures generated by a particular...... system and such that each subset consists of stable measures. The uniformity requirement has a natural interpretation in terms of plausibility of Rational Beliefs...

  8. Experimental investigations on prototype heat storage units utilizing stable supercooling of sodium acetate trihydrate mixtures

    DEFF Research Database (Denmark)

    Dannemand, Mark; Dragsted, Janne; Fan, Jianhua

    2016-01-01

    Laboratory tests of two heat storage units based on the principle of stable supercooling of sodium acetate trihydrate (SAT) mixtures were carried out. One unit was filled with 199.5 kg of SAT with 9% extra water to avoid phase separation of the incongruently melting salt hydrate. The other unit...

  9. A Systematic and Numerically Efficient Procedure for Stable Dynamic Model Inversion of LTI Systems

    NARCIS (Netherlands)

    George, K.; Verhaegen, M.; Scherpen, J.M.A.

    1999-01-01

    Output tracking via the novel Stable Dynamic model Inversion (SDI) technique, applicable to non-minimum phase systems, and which naturally takes into account the presence of noise in target time histories, is considered here. We are motivated by the typical need to replicate time signals in the

  10. Faster and Simpler Approximation of Stable Matchings

    Directory of Open Access Journals (Sweden)

    Katarzyna Paluch

    2014-04-01

    Full Text Available We give a 3 2 -approximation algorithm for finding stable matchings that runs in O(m time. The previous most well-known algorithm, by McDermid, has the same approximation ratio but runs in O(n3/2m time, where n denotes the number of people andm is the total length of the preference lists in a given instance. In addition, the algorithm and the analysis are much simpler. We also give the extension of the algorithm for computing stable many-to-many matchings.

  11. Moving stable solitons in Galileon theory

    International Nuclear Information System (INIS)

    Masoumi, Ali; Xiao Xiao

    2012-01-01

    Despite the no-go theorem Endlich et al. (2011) which rules out static stable solitons in Galileon theory, we propose a family of solitons that evade the theorem by traveling at the speed of light. These domain-wall-like solitons are stable under small fluctuations-analysis of perturbation shows neither ghost-like nor tachyon-like instabilities, and perturbative collision of these solitons suggests that they pass through each other asymptotically, which maybe an indication of the integrability of the theory itself.

  12. Bordism, stable homotopy and adams spectral sequences

    CERN Document Server

    Kochman, Stanley O

    1996-01-01

    This book is a compilation of lecture notes that were prepared for the graduate course "Adams Spectral Sequences and Stable Homotopy Theory" given at The Fields Institute during the fall of 1995. The aim of this volume is to prepare students with a knowledge of elementary algebraic topology to study recent developments in stable homotopy theory, such as the nilpotence and periodicity theorems. Suitable as a text for an intermediate course in algebraic topology, this book provides a direct exposition of the basic concepts of bordism, characteristic classes, Adams spectral sequences, Brown-Peter

  13. Stable isotopes in Lithuanian bioarcheological material

    Science.gov (United States)

    Skipityte, Raminta; Jankauskas, Rimantas; Remeikis, Vidmantas

    2015-04-01

    Investigation of bioarcheological material of ancient human populations allows us to understand the subsistence behavior associated with various adaptations to the environment. Feeding habits are essential to the survival and growth of ancient populations. Stable isotope analysis is accepted tool in paleodiet (Schutkowski et al, 1999) and paleoenvironmental (Zernitskaya et al, 2014) studies. However, stable isotopes can be useful not only in investigating human feeding habits but also in describing social and cultural structure of the past populations (Le Huray and Schutkowski, 2005). Only few stable isotope investigations have been performed before in Lithuanian region suggesting a quite uniform diet between males and females and protein intake from freshwater fish and animal protein. Previously, stable isotope analysis has only been used to study a Stone Age population however, more recently studies have been conducted on Iron Age and Late medieval samples (Jacobs et al, 2009). Anyway, there was a need for more precise examination. Stable isotope analysis were performed on human bone collagen and apatite samples in this study. Data represented various ages (from 5-7th cent. to 18th cent.). Stable carbon and nitrogen isotope analysis on medieval populations indicated that individuals in studied sites in Lithuania were almost exclusively consuming C3 plants, C3 fed terrestrial animals, and some freshwater resources. Current investigation demonstrated social differences between elites and country people and is promising in paleodietary and daily life reconstruction. Acknowledgement I thank prof. dr. G. Grupe, Director of the Anthropological and Palaeoanatomical State Collection in Munich for providing the opportunity to work in her laboratory. The part of this work was funded by DAAD. Antanaitis-Jacobs, Indre, et al. "Diet in early Lithuanian prehistory and the new stable isotope evidence." Archaeologia Baltica 12 (2009): 12-30. Le Huray, Jonathan D., and Holger

  14. Unconditionally stable microwave Si-IMPATT amplifiers

    International Nuclear Information System (INIS)

    Seddik, M.M.

    1986-07-01

    The purpose of this investigation has been the development of an improved understanding of the design and analysis of microwave reflection amplifiers employing the negative resistance property of the IMPATT devices. Unconditionally stable amplifier circuit using a Silicon IMPATT diode is designed. The problems associated with the design procedures and the stability criterion are discussed. A computer program is developed to perform the computations. The stable characteristics of a reflection-type Si-IMPATT amplifier, such as gain, frequency and bandwidth are examined. It was found that at large signal drive levels, 7 dB gain with bandwidth of 800 MHz at 22,5 mA was obtained. (author)

  15. Comparative biogeochemical behaviors of iron-55 and stable iron in the marine environment

    International Nuclear Information System (INIS)

    Weimer, W.C.; Langford, J.C.; Jenkins, C.E.

    1978-01-01

    Studies of atmospheric aerosols have demonstrated that much of the 55 Fe associated with the aerosol input to the oceans is present as either an amorphous or hydrous iron oxide or as very small particulate species attached to the surfaces of the large aerosol particles. By comparison, nearly all of the stable iron is bound in the mineral phase of aerosol particles. This difference in the chemical and physical forms of the radioactive and stable iron isotopes results in the 55 Fe being more biologically available than is the stable iron. This difference in availability is responsible for the transfer of a much higher specific activity 55 Fe to certain ocean organisms and man relative to the specific activity of the total aerosol or of sea water. This differential biological uptake of the radioactive element and its stable element counterpart points out that natural levels of stable elements in the marine environment may not effectively dilute radioelements or other stable elements of anthropogenic sources. The effectiveness of dilution by natural sources depends on the chemical and physical forms of the materials in both the source terms and the receiving environments. The large difference in specific activities of 55 Fe in aerosols and sea water relative to ocean organisms reflects the independent behaviors of 55 Fe and stable iron

  16. Leg-adjustment strategies for stable running in three dimensions

    International Nuclear Information System (INIS)

    Peuker, Frank; Maufroy, Christophe; Seyfarth, André

    2012-01-01

    The dynamics of the center of mass (CoM) in the sagittal plane in humans and animals during running is well described by the spring-loaded inverted pendulum (SLIP). With appropriate parameters, SLIP running patterns are stable, and these models can recover from perturbations without the need for corrective strategies, such as the application of additional forces. Rather, it is sufficient to adjust the leg to a fixed angle relative to the ground. In this work, we consider the extension of the SLIP to three dimensions (3D SLIP) and investigate feed-forward strategies for leg adjustment during the flight phase. As in the SLIP model, the leg is placed at a fixed angle. We extend the scope of possible reference axes from only fixed horizontal and vertical axes to include the CoM velocity vector as a movement-related reference, resulting in six leg-adjustment strategies. Only leg-adjustment strategies that include the CoM velocity vector produced stable running and large parameter domains of stability. The ability of the model to recover from perturbations along the direction of motion (directional stability) depended on the strategy for lateral leg adjustment. Specifically, asymptotic and neutral directional stability was observed for strategies based on the global reference axis and the velocity vector, respectively. Additional features of velocity-based leg adjustment are running at arbitrary low speed (kinetic energy) and the emergence of large domains of stable 3D running that are smoothly transferred to 2D SLIP stability and even to 1D SLIP hopping. One of the additional leg-adjustment strategies represented a large convex region of parameters where stable and robust hopping and running patterns exist. Therefore, this strategy is a promising candidate for implementation into engineering applications, such as robots, for instance. In a preliminary comparison, the model predictions were in good agreement with the experimental data, suggesting that the 3D SLIP is an

  17. Kohn Anomaly and Phase Stability in Group VB Transition Metals

    Directory of Open Access Journals (Sweden)

    Alexander Landa

    2018-03-01

    Full Text Available In the periodic table, only a few pure metals exhibit lattice or magnetic instabilities associated with Fermi surface nesting, the classical examples being α-U and Cr. Whereas α-U displays a strong Kohn anomaly in the phonon spectrum that ultimately leads to the formation of charge density waves (CDWs, Cr is known for its nesting-induced spin density waves (SDWs. Recently, it has become clear that a pronounced Kohn anomaly and the corresponding softening in the elastic constants is also the key factor that controls structural transformations and mechanical properties in compressed group VB metals—materials with relatively high superconducting critical temperatures. This article reviews the current understanding of the structural and mechanical behavior of these metals under pressure with an introduction to the concept of the Kohn anomaly and how it is related to the important concept of Peierls instability. We review both experimental and theoretical results showing different manifestations of the Kohn anomaly in the transverse acoustic phonon mode TA (ξ00 in V, Nb, and Ta. Specifically, in V the anomaly triggers a structural transition to a rhombohedral phase, whereas in Nb and Ta it leads to an anomalous reduction in yield strength.

  18. Thermodynamics of Minerals Stable Near the Earth's Surface

    International Nuclear Information System (INIS)

    Navrotsky, Alexandra

    2003-01-01

    OAK B262 Research and Education Activities We are working on developing calorimetric techniques for sulfide minerals. We have completed calorimetric studies of (Na, K, H3O) jarosites, of Na and K jarosite -alunite solid solutions, and of Cr6+ - containing jarosites. We are now working on phases containing As and Pb. These studies are important to issues of heavy metal pollution in the environment. A number of postdocs, graduate students, and undergrads have participated in the research. We have active collaboration with Dirk Baron, faculty at California State University, Bakersfield. In a collaboration with Peter Burns, Notre Dame University, we are working on thermochemistry of U6+ minerals. Navrotsky has participated in a number of national workshops that are helping to define the interfaces between nanotechnology and earth/environmental science. Major Findings Our first finding on uranyl minerals shows that studtite, a phase containing structural peroxide ion, is thermodynamically unstable in the absence of a source of aqueous peroxide ion but is thermodynamically stable in contact with a solution containing peroxide concentrations expected for the radiolysis of water in contact with spent nuclear fuel. This work is in press in Science. We have a consistent thermodynamic data set for the (Na, K, H3O) (Al, Fe) jarosite, alunite minerals and for Cr6+ substituting for S6+ in jarosite. The latter phases represent one of the few solid sinks for trapping toxic Cr6+ in groundwater. Contributions within Discipline Better understanding of thermodynamic driving for and constraints on geochemical and environmental processes

  19. Subsolidus phase relations of Bi2O3-Nd2O3-CuO

    International Nuclear Information System (INIS)

    Sun Yezhou

    1997-01-01

    The subsolidus phase relations of the Bi 2 O 3 -Nd 2 O 3 -CuO ternary system and its binary systems along with crystallographic parameters of the compounds were investigated by X-ray powder diffraction and differential thermal analysis. The room temperature section of the phase diagram of the Bi 2 O 3 -Nd 2 O 3 -CuO system can be divided into two diphase regions and six triphase regions. No ternary compound was found. There exist two solid solutions (α, β) and a compound Bi 0.55 Nd 0.45 O 1.5 in the (Bi 2 O 2 ) 1-x (Nd 2 O 3 ) x system. Both solid solution α (0.05≤x≤0.30) and β (0.53≤x≤0.73) belong to the rhombohedral system (R3m). The lattice parameters represented by a hexagonal cell are a=3.9832(4), c=27.536(5) A for Bi 0.8 Nd 0.2 O 1.5 (α phase) and a=3.8826(3), c=9.727(1) A for Bi 0.4 Nd 0.8 O 1.5 (β phase). The Bi 0.55 Nd 0.45 O 1.5 compound crystallizes in a face-centered cubic (f.c.c.) lattice with a=5.5480(2) A. (orig.)

  20. petrography, compositional characteristics and stable isotope ...

    African Journals Online (AJOL)

    PROF EKWUEME

    Subsurface samples of the predominantly carbonate Ewekoro Formation, obtained from Ibese core hole within the Dahomey basin were used in this study. Investigations entail petrographic, elemental composition as well as stable isotopes (carbon and oxygen) geochemistry in order to deduce the different microfacies and ...

  1. Working conditions remain stable in the Netherlands

    NARCIS (Netherlands)

    Houtman, I.; Hooftman, W.

    2008-01-01

    Despite significant changes in the national questionnaires on work and health, the quality of work as well as health complaints in the Netherlands appear to be relatively stable. Pace of work seems to be on the increase again and more people are working in excess of their contractual hours.

  2. Thermally stable sintered porous metal articles

    International Nuclear Information System (INIS)

    Gombach, A.L.; Thellmann, E.L.

    1980-01-01

    A sintered porous metal article is provided which is essentially thermally stable at elevated temperatures. In addition, a method for producing such an article is also provided which method comprises preparing a blend of base metal particles and active dispersoid particles, forming the mixture into an article of the desired shape, and heating the so-formed article at sintering temperatures

  3. TOF for heavy stable particle identification

    International Nuclear Information System (INIS)

    Chang, C.Y.

    1983-01-01

    Searching for heavy stable particle production in a new energy region of hadron-hadron collisions is of fundamental theoretical interest. Observation of such particles produced in high energy collisions would indicate the existence of stable heavy leptons or any massive hadronic system carrying new quantum numbers. Experimentally, evidence of its production has not been found for PP collisions either at FNAL or at the CERN ISR for √S = 23 and 62 GeV respectively. However, many theories beyond the standard model do predict its existence on a mass scale ranging from 50 to a few hundred GeV. If so, it would make a high luminosity TeV collider an extremely ideal hunting ground for searching the production of such a speculated object. To measure the mass of a heavy stable charged particle, one usually uses its time of flight (TOF) and/or dE/dX information. For heavy neutral particle, one hopes it may decay at some later time after its production. Hence a pair of jets or a jet associated with a high P/sub t/ muon originated from some places other than the interacting point (IP) of the colliding beams may be a good signal. In this note, we examine the feasibility of TOF measurement on a heavy stable particle produced in PP collisions at √S = 1 TeV and a luminosity of 10 33 cm -2 sec -1 with a single arm spectrometer pointing to the IP

  4. Axisymmetric MHD stable sloshing ion distributions

    International Nuclear Information System (INIS)

    Berk, H.L.; Dominguez, N.; Roslyakov, G.V.

    1986-07-01

    The MHD stability of a sloshing ion distribution is investigated in a symmetric mirror cell. Fokker-Planck calculations show that stable configurations are possible for ion injection energies that are at least 150 times greater than the electron temperture. Special axial magnetic field profiles are suggested to optimize the favorable MHD properties

  5. Exact simulation of max-stable processes.

    Science.gov (United States)

    Dombry, Clément; Engelke, Sebastian; Oesting, Marco

    2016-06-01

    Max-stable processes play an important role as models for spatial extreme events. Their complex structure as the pointwise maximum over an infinite number of random functions makes their simulation difficult. Algorithms based on finite approximations are often inexact and computationally inefficient. We present a new algorithm for exact simulation of a max-stable process at a finite number of locations. It relies on the idea of simulating only the extremal functions, that is, those functions in the construction of a max-stable process that effectively contribute to the pointwise maximum. We further generalize the algorithm by Dieker & Mikosch (2015) for Brown-Resnick processes and use it for exact simulation via the spectral measure. We study the complexity of both algorithms, prove that our new approach via extremal functions is always more efficient, and provide closed-form expressions for their implementation that cover most popular models for max-stable processes and multivariate extreme value distributions. For simulation on dense grids, an adaptive design of the extremal function algorithm is proposed.

  6. Unconditionally stable integration of Maxwell's equations

    NARCIS (Netherlands)

    Verwer, J.G.; Bochev, Mikhail A.

    Numerical integration of Maxwell's equations is often based on explicit methods accepting a stability step size restriction. In literature evidence is given that there is also a need for unconditionally stable methods, as exemplified by the successful alternating direction implicit finite difference

  7. Unconditionally stable integration of Maxwell's equations

    NARCIS (Netherlands)

    J.G. Verwer (Jan); M.A. Botchev

    2008-01-01

    htmlabstractNumerical integration of Maxwell''s equations is often based on explicit methods accepting a stability step size restriction. In literature evidence is given that there is also a need for unconditionally stable methods, as exemplified by the successful alternating direction

  8. Unconditionally stable integration of Maxwell's equations

    NARCIS (Netherlands)

    J.G. Verwer (Jan); M.A. Botchev

    2009-01-01

    textabstractNumerical integration of Maxwell’s equations is often based on explicit methods accepting a stability step size restriction. In literature evidence is given that there is also a need for unconditionally stable methods, as exemplified by the successful alternating direction implicit –

  9. Method of producing thermally stable uranium carbonitrides

    International Nuclear Information System (INIS)

    Ugajin, M.; Takahashi, I.

    1975-01-01

    A thermally stable uranium carbonitride can be produced by adding tungsten and/or molybdenum in the amount of 0.2 wt percent or more, preferably 0.5 wt percent or more, to a pure uranium carbonitride. (U.S.)

  10. Champion Island, Galapagos Stable Oxygen Calibration Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Galapagos Coral Stable Oxygen Calibration Data. Sites: Bartolome Island: 0 deg, 17 min S, 90 deg 33 min W. Champion Island: 1 deg, 15 min S, 90 deg, 05 min W. Urvina...

  11. 26 S proteasomes function as stable entities

    DEFF Research Database (Denmark)

    Hendil, Klavs B; Hartmann-Petersen, Rasmus; Tanaka, Keiji

    2002-01-01

    , shuttles between a free state and the 26-S proteasome, bringing substrate to the complex. However, S5a was not found in the free state in HeLa cells. Besides, all subunits in PA700, including S5a, exchanged at similar low rates. It therefore seems that 26-S proteasomes function as stable entities during...

  12. Formal derivation of a stable marriage algorithm.

    NARCIS (Netherlands)

    Bijlsma, A.

    1991-01-01

    In this paper the well-known Stable Marriage Problem is considered once again. The name of this programming problem comes from the terms in which it was first described [2]: A certain community consists of n men and n women. Each person ranks those of the opposite sex in accordance with his or

  13. The Nature of Stable Insomnia Phenotypes

    Science.gov (United States)

    Pillai, Vivek; Roth, Thomas; Drake, Christopher L.

    2015-01-01

    Study Objectives: We examined the 1-y stability of four insomnia symptom profiles: sleep onset insomnia; sleep maintenance insomnia; combined onset and maintenance insomnia; and neither criterion (i.e., insomnia cases that do not meet quantitative thresholds for onset or maintenance problems). Insomnia cases that exhibited the same symptom profile over a 1-y period were considered to be phenotypes, and were compared in terms of clinical and demographic characteristics. Design: Longitudinal. Setting: Urban, community-based. Participants: Nine hundred fifty-four adults with Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition based current insomnia (46.6 ± 12.6 y; 69.4% female). Interventions: None. Measurements and results: At baseline, participants were divided into four symptom profile groups based on quantitative criteria. Follow-up assessment 1 y later revealed that approximately 60% of participants retained the same symptom profile, and were hence judged to be phenotypes. Stability varied significantly by phenotype, such that sleep onset insomnia (SOI) was the least stable (42%), whereas combined insomnia (CI) was the most stable (69%). Baseline symptom groups (cross-sectionally defined) differed significantly across various clinical indices, including daytime impairment, depression, and anxiety. Importantly, however, a comparison of stable phenotypes (longitudinally defined) did not reveal any differences in impairment or comorbid psychopathology. Another interesting finding was that whereas all other insomnia phenotypes showed evidence of an elevated wake drive both at night and during the day, the “neither criterion” phenotype did not; this latter phenotype exhibited significantly higher daytime sleepiness despite subthreshold onset and maintenance difficulties. Conclusions: By adopting a stringent, stability-based definition, this study offers timely and important data on the longitudinal trajectory of specific insomnia phenotypes. With

  14. Experimental studies on cycling stable characteristics of inorganic phase change material CaCl2·6H2O-MgCl2·6H2O modified with SrCl2·6H2O and CMC

    Science.gov (United States)

    He, Meizhi; Yang, Luwei; Zhang, Zhentao

    2018-01-01

    By means of mass ratio method, binary eutectic hydrated salts inorganic phase change thermal energy storage system CaCl2·6H2O-20wt% MgCl2·6H2O was prepared, and through adding nucleating agent 1wt% SrCl2·6H2O and thickening agent 0.5wt% carboxy methyl cellulose (CMC), inoganic phase change material (PCM) modified was obtained. With recording cooling-melting curves simultaneously, this PCM was frozen and melted for 100 cycles under programmable temperature control. After per 10 cycles, the PCM was charaterized by differential scanning calorimeter (DSC), X-ray diffraction (XRD) and density meter, then analysing variation characteristics of phase change temperature, supercooling degree, superheat degree, latent heat, crystal structure and density with the increase of cycle index. The results showed that the average values of average phase change temperature for cooling and heating process were 25.70°C and 27.39°C respectively with small changes. The average values of average supercooling and superheat degree were 0.59°C and 0.49°C respectively, and the maximum value was 1.10°C. The average value and standard deviation of latent heat of fusion were 120.62 J/g and 1.90 J/g respectively. Non-molten white solid sediments resulted from phase separation were tachyhydrite (CaMg2Cl6·12H2O), which was characterized by XRD. Measuring density of the PCM after per 10 cycles, and the results suggested that the total mass of tachyhydrite was limited. In summary, such modified inoganic PCM CaCl2·6H2O-20wt% MgCl2·6H2O-1wt% SrCl2·6H2O-0.5wt% CMC could stay excellent circulation stability within 100 cycles, and providing reference value in practical use.

  15. Covalent and stable CuAAC modification of silicon surfaces for control of cell adhesion

    DEFF Research Database (Denmark)

    Vutti, Surendra; Buch-Månson, Nina; Schoffelen, Sanne

    2015-01-01

    in the vapor or liquid phase. In this work, we compared these two methods for oxidized silicon surfaces and thoroughly characterized the functionalization steps by tagging and fluorescence imaging. We demonstrate that the vapor-phase functionalization only provided transient surface modification that was lost...... on extensive washing. For stable surface modification, a liquid-phase method was developed. In this method, silicon wafers were decorated with azides, either by silanization with (3-azidopropyl)triethoxysilane or by conversion of the amine groups of an aminopropylated surface by means of the azido...

  16. Relation between distribution coefficient of radioactive strontium and solid-liquid distribution ratio of background stable strontium

    International Nuclear Information System (INIS)

    Igarashi, Toshifumi; Mahara, Yasunori; Okamura, Masaki; Ashikawa, Nobuo.

    1992-01-01

    Distribution coefficients (K d ) of nuclides, which are defined as the ratio of the adsorbed concentration to the solution concentration, are important in predicting nuclide migration in the subsurface environment. This study was undertaken to contrust an effective method of determining the most pertinent K d value for simulating in situ distribution phenomena between the solid and liquid phases, by using background stable isotopes. This paper describes the applicability of this method to Sr by carrying out a batch Sr adsorption experiment where stable Sr coexisted with the radioactive isotope, 85 Sr, and by comparing the concentration distribution ratio of the background stable Sr with the K d value obtained by the batch experiment. The results showed that the K d of 85 Sr (K d85 ) agreed well with the K d of the coexisting stable Sr (K ds ) and that the two values decreased with an increase in the concentration of the stable Sr, when sand was used as an adsorbent. In addition, the K d85 corresponded to the ratio of the exchangeable solid-phase concentration of background stable Sr to the concentration of the background stable Sr in groundwater when the concentration of the coexisting stable Sr approached the background level. On the other hand, when powdered rock samples were used, the K d85 did not agree with the K ds , and the concentration distribution ratio of the background stable Sr was greater than the K d85 . This discrepancy might be due to the disequilibrium resulting from grinding the rock matrices. This suggests that measurement of the background stable Sr distribution ratio between the solid and liquid phases can be an effective method of estimating the K d of radioactive Sr when the groundwater is in satisfactory contact with the adsorption medium. (author)

  17. The stable Cr isotopic compositions of chondrites and silicate planetary reservoirs

    Science.gov (United States)

    Schoenberg, Ronny; Merdian, Alexandra; Holmden, Chris; Kleinhanns, Ilka C.; Haßler, Kathrin; Wille, Martin; Reitter, Elmar

    2016-06-01

    The depletion of chromium in Earth's mantle (∼2700 ppm) in comparison to chondrites (∼4400 ppm) indicates significant incorporation of chromium into the core during our planet's metal-silicate differentiation, assuming that there was no significant escape of the moderately volatile element chromium during the accretionary phase of Earth. Stable Cr isotope compositions - expressed as the ‰-difference in 53Cr/52Cr from the terrestrial reference material SRM979 (δ53/52CrSRM979 values) - of planetary silicate reservoirs might thus yield information about the conditions of planetary metal segregation processes when compared to chondrites. The stable Cr isotopic compositions of 7 carbonaceous chondrites, 11 ordinary chondrites, 5 HED achondrites and 2 martian meteorites determined by a double spike MC-ICP-MS method are within uncertainties indistinguishable from each other and from the previously determined δ53/52CrSRM979 value of -0.124 ± 0.101‰ for the igneous silicate Earth. Extensive quality tests support the accuracy of the stable Cr isotope determinations of various meteorites and terrestrial silicates reported here. The uniformity in stable Cr isotope compositions of samples from planetary silicate mantles and undifferentiated meteorites indicates that metal-silicate differentiation of Earth, Mars and the HED parent body did not cause measurable stable Cr isotope fractionation between these two reservoirs. Our results also imply that the accretionary disc, at least in the inner solar system, was homogeneous in its stable Cr isotopic composition and that potential volatility loss of chromium during accretion of the terrestrial planets was not accompanied by measurable stable isotopic fractionation. Small but reproducible variations in δ53/52CrSRM979 values of terrestrial magmatic rocks point to natural stable Cr isotope variations within Earth's silicate reservoirs. Further and more detailed studies are required to investigate whether silicate

  18. Development of a Safety Management Web Tool for Horse Stables.

    Science.gov (United States)

    Leppälä, Jarkko; Kolstrup, Christina Lunner; Pinzke, Stefan; Rautiainen, Risto; Saastamoinen, Markku; Särkijärvi, Susanna

    2015-11-12

    Managing a horse stable involves risks, which can have serious consequences for the stable, employees, clients, visitors and horses. Existing industrial or farm production risk management tools are not directly applicable to horse stables and they need to be adapted for use by managers of different types of stables. As a part of the InnoEquine project, an innovative web tool, InnoHorse, was developed to support horse stable managers in business, safety, pasture and manure management. A literature review, empirical horse stable case studies, expert panel workshops and stakeholder interviews were carried out to support the design. The InnoHorse web tool includes a safety section containing a horse stable safety map, stable safety checklists, and examples of good practices in stable safety, horse handling and rescue planning. This new horse stable safety management tool can also help in organizing work processes in horse stables in general.

  19. Composition-Driven Phase Boundary and Piezoelectricity in Potassium-Sodium Niobate-Based Ceramics.

    Science.gov (United States)

    Zheng, Ting; Wu, Jiagang; Xiao, Dingquan; Zhu, Jianguo; Wang, Xiangjian; Lou, Xiaojie

    2015-09-16

    The piezoelectricity of (K,Na)NbO3 ceramics strongly depends on the phase boundary types as well as the doped compositions. Here, we systematically studied the relationships between the compositions and phase boundary types in (K,Na) (Nb,Sb)O3-Bi0.5Na0.5AO3 (KNNS-BNA, A=Hf, Zr, Ti, Sn) ceramics; then their piezoelectricity can be readily modified. Their phase boundary types are determined by the doped elements. A rhombohedral-tetragonal (R-T) phase boundary can be driven in the compositions range of 0.035≤BNH≤0.040 and 0.035≤BNZ≤0.045; an orthorhombic-tetragonal (O-T) phase boundary is formed in the composition range of 0.005≤BNT≤0.02; and a pure O phase can be only observed regardless of BNS content (≤0.01). In addition, the phase boundary types strongly affect their corresponding piezoelectricities. A larger d33 (∼440-450 pC/N) and a higher d33* (∼742-834 pm/V) can be attained in KNNS-BNA (A=Zr and Hf) ceramics due to the involvement of R-T phase boundary, and unfortunately KNNS-BNA (A=Sn and Ti) ceramics possess a relatively poor piezoelectricity (d33≤200 and d33*piezoelectricity and phase boundary types were also discussed. We believe that comprehensive research can design more excellent ceramic systems concerning potassium-sodium niobate.

  20. Metallization systems for stable ohmic contacts to GaAs

    International Nuclear Information System (INIS)

    Tandon, J.L.; Douglas, K.D.; Vendura, G.; Kolawa, E.; So, F.C.T.; Nicolet, M.A.

    1986-01-01

    A metallization scheme to form reproducible and stable ohmic contacts to GaAs is described. The approach is based on the configuration: GaAs/X/Y/Z; where X is a thin metal film (e.g. Pt, Ti, Pd, Ru), Y is an electrically conducting diffusion barrier layer (TiN, W or W/sub 0.7/N/sub 0.3/), and Z is a thick metal layer (e.g. Ag) typically required for bonding or soldering purposes. The value and reproducibility of the contact resistance in these metallization systems results from the uniform steady-state solid-phase reaction of the metal X with GaAs. The stability of the contacts is achieved by the diffusion barrier layer Y, which not only confines the reaction of X with GaAs, but also prevents the top metal layer Z from interfering with this reaction. Applications of such contacts in fabricating stable solar cells are also discussed

  1. Spatial-Frequency Azimuthally Stable Cartography of Biological Polycrystalline Networks

    Directory of Open Access Journals (Sweden)

    V. A. Ushenko

    2013-01-01

    Full Text Available A new azimuthally stable polarimetric technique processing microscopic images of optically anisotropic structures of biological tissues histological sections is proposed. It has been used as a generalized model of phase anisotropy definition of biological tissues by using superposition of Mueller matrices of linear birefringence and optical activity. The matrix element M44 has been chosen as the main information parameter, whose value is independent of the rotation angle of both sample and probing beam polarization plane. For the first time, the technique of concerted spatial-frequency filtration has been used in order to separate the manifestation of linear birefringence and optical activity. Thereupon, the method of azimuthally stable spatial-frequency cartography of biological tissues histological sections has been elaborated. As the analyzing tool, complex statistic, correlation, and fractal analysis of coordinate distributions of M44 element has been performed. The possibility of using the biopsy of the uterine wall tissue in order to differentiate benign (fibromyoma and malignant (adenocarcinoma conditions has been estimated.

  2. Management standards for stable coronary artery disease in India

    Directory of Open Access Journals (Sweden)

    Sundeep Mishra

    2016-12-01

    Full Text Available Coronary artery disease (CAD is one of the important causes of cardiovascular morbidity and mortality globally, giving rise to more than 7 million deaths annually. An increasing burden of CAD in India is a major cause of concern with angina being the leading manifestation. Stable coronary artery disease (SCAD is characterised by episodes of transient central chest pain (angina pectoris, often triggered by exercise, emotion or other forms of stress, generally triggered by a reversible mismatch between myocardial oxygen demand and supply resulting in myocardial ischemia or hypoxia. A stabilised, frequently asymptomatic phase following an acute coronary syndrome (ACS is also classified as SCAD. This definition of SCAD also encompasses vasospastic and microvascular angina under the common umbrella.

  3. Classically and quantum stable emergent universe from conservation laws

    Energy Technology Data Exchange (ETDEWEB)

    Campo, Sergio del; Herrera, Ramón [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Avenida Brasil 2950, Casilla 4059, Valparaíso (Chile); Guendelman, Eduardo I. [Physics Department, Ben Gurion University of the Negev, Beer Sheva 84105 (Israel); Labraña, Pedro, E-mail: guendel@bgu.ac.il, E-mail: ramon.herrera@ucv.cl, E-mail: plabrana@ubiobio.cl [Departamento de Física, Universidad del Bío Bío and Grupo de Cosmología y Gravitación-UBB, Avenida Collao 1202, Casilla 5-C, Concepción (Chile)

    2016-08-01

    It has been recently pointed out by Mithani-Vilenkin [1-4] that certain emergent universe scenarios which are classically stable are nevertheless unstable semiclassically to collapse. Here, we show that there is a class of emergent universes derived from scale invariant two measures theories with spontaneous symmetry breaking (s.s.b) of the scale invariance, which can have both classical stability and do not suffer the instability pointed out by Mithani-Vilenkin towards collapse. We find that this stability is due to the presence of a symmetry in the 'emergent phase', which together with the non linearities of the theory, does not allow that the FLRW scale factor to be smaller that a certain minimum value a {sub 0} in a certain protected region.

  4. Stable particle motion in a linear accelerator with solenoid focusing

    International Nuclear Information System (INIS)

    Wadlinger, E.A.

    1979-01-01

    The equation governing stable particle motion in a linear ion accelerator containing discrete rf and either discrete or continuous solenoid focusing was derived. It was found for discrete solenoid focusing that: cos μ = (1 + dΔ) cos theta/2 + (lΔ/theta - dtheta/2l - thetaΔd 2 /4l) sin theta/2, Δ = 1/f and l + 2d = βlambda, where μ, theta, f, l, and d are the phase advance per cell, precession angle in the solenoid, focal length of the rf lens, length of the solenoid in one cell, and the drift distance between the center of the rf gap and the effective edge of the solenoid. The relation for a continuous solenoid is found by setting d equal to zero. The boundaries of the stability region for theta vs Δ with fixed l and d are obtained when cos μ =+-1

  5. Multistability in Chua's circuit with two stable node-foci

    International Nuclear Information System (INIS)

    Bao, B. C.; Wang, N.; Xu, Q.; Li, Q. D.

    2016-01-01

    Only using one-stage op-amp based negative impedance converter realization, a simplified Chua's diode with positive outer segment slope is introduced, based on which an improved Chua's circuit realization with more simpler circuit structure is designed. The improved Chua's circuit has identical mathematical model but completely different nonlinearity to the classical Chua's circuit, from which multiple attractors including coexisting point attractors, limit cycle, double-scroll chaotic attractor, or coexisting chaotic spiral attractors are numerically simulated and experimentally captured. Furthermore, with dimensionless Chua's equations, the dynamical properties of the Chua's system are studied including equilibrium and stability, phase portrait, bifurcation diagram, Lyapunov exponent spectrum, and attraction basin. The results indicate that the system has two symmetric stable nonzero node-foci in global adjusting parameter regions and exhibits the unusual and striking dynamical behavior of multiple attractors with multistability.

  6. Ultra-stable long distance optical frequency distribution using the Internet fiber network.

    Science.gov (United States)

    Lopez, Olivier; Haboucha, Adil; Chanteau, Bruno; Chardonnet, Christian; Amy-Klein, Anne; Santarelli, Giorgio

    2012-10-08

    We report an optical link of 540 km for ultrastable frequency distribution over the Internet fiber network. The stable frequency optical signal is processed enabling uninterrupted propagation on both directions. The robustness and the performance of the link are enhanced by a cost effective fully automated optoelectronic station. This device is able to coherently regenerate the return optical signal with a heterodyne optical phase locking of a low noise laser diode. Moreover the incoming signal polarization variation are tracked and processed in order to maintain beat note amplitudes within the operation range. Stable fibered optical interferometer enables optical detection of the link round trip phase signal. The phase-noise compensated link shows a fractional frequency instability in 10 Hz bandwidth of 5 × 10(-15) at one second measurement time and 2 × 10(-19) at 30,000 s. This work is a significant step towards a sustainable wide area ultrastable optical frequency distribution and comparison network.

  7. Phase formation in the (1-y)BiFeO{sub 3}-yBiScO{sub 3} system under ambient and high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Salak, A.N., E-mail: salak@ua.pt [Department of Materials and Ceramic Engineering and CICECO – Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro (Portugal); Khalyavin, D.D., E-mail: dmitry.khalyavin@stfc.ac.uk [ISIS Facility, Rutherford Appleton Laboratory, Chilton, OX11 0QX Didcot (United Kingdom); Pushkarev, A.V.; Radyush, Yu.V.; Olekhnovich, N.M. [Scientific-Practical Materials Research Centre of NAS of Belarus, P. Brovka Street, 19, 220072 Minsk (Belarus); Shilin, A.D.; Rubanik, V.V. [Institute of Technical Acoustics of NAS of Belarus, Lyudnikov Avenue, 13, 210023 Vitebsk (Belarus)

    2017-03-15

    Formation and thermal stability of perovskite phases in the BiFe{sub 1-y}Sc{sub y}O{sub 3} system (0≤y≤0.70) were studied. When the iron-to-scandium substitution rate does not exceed about 15 at%, the single-phase perovskite ceramics with the rhombohedral R3c symmetry (as that of the parent compound, BiFeO{sub 3}) can be prepared from the stoichiometric mixture of the respective oxides at ambient pressure. Thermal treatment of the oxide mixtures with a higher content of scandium results in formation of two main phases, namely a BiFeO{sub 3}-like R3c phase and a cubic (I23) sillenite-type phase based on γ-Bi{sub 2}O{sub 3}. Single-phase perovskite ceramics of the BiFe{sub 1-y}Sc{sub y}O{sub 3} composition were synthesized under high pressure from the thermally treated oxide mixtures. When y is between 0 and 0.25 the high-pressure prepared phase is the rhombohedral R3c with the √2a{sub p}×√2a{sub p}×2√3a{sub p} superstructure (a{sub p} ~ 4 Å is the pseudocubic perovskite unit-cell parameter). The orthorhombic Pnma phase (√2a{sub p}×4a{sub p}×2√2a{sub p}) was obtained in the range of 0.30≤y≤0.60, while the monoclinic C2/c phase (√6a{sub p}×√2a{sub p}×√6a{sub p}) is formed when y=0.70. The normalized unit-cell volume drops at the crossover from the rhombohedral to the orthorhombic composition range. The perovskite BiFe{sub 1-y}Sc{sub y}O{sub 3} phases prepared under high pressure are metastable regardless of their symmetry. At ambient pressure, the phases with the compositions in the ranges of 0.20≤y≤0.25, 0.30≤y<0.50 and 0.50≤y≤0.70 start to decompose above 970, 920 and 870 K, respectively. - Graphical abstract: Formation of perovskite phases in the BiFe{sub 1-y}Sc{sub y}O{sub 3} system when y≥0.15 requires application of pressure of several GPa. The phases formed under high pressure: R3c (0.20≤y≤0.25), Pnma (0.30≤y≤0.60) and C2/c (y≥0.70) are metastable. - Highlights: • Maximal Fe-to-Sc substitution rate in Bi

  8. Solid-liquid stable phase equilibria of the ternary systems MgCl2 + MgB6O10+ H2O AND MgSO4 + MgB6O10 + H2O at 308.15 K

    Directory of Open Access Journals (Sweden)

    Lingzong Meng

    2014-03-01

    Full Text Available The solubilities and the relevant physicochemical properties of the ternary systems MgCl2 + MgB6O10 + H2O and MgSO4 + MgB6O10 + H2O at 308.15 K were investigated using an isothermal dissolution method. It was found that there is one invariant point, two univariant curves, and two crystallization regions of the systems. The systems belong to a simple co-saturated type, and neither double salts nor solid solutions were found. Based on the extended HW model and its temperature-dependent equations, the single-salt Pitzer parameters β(0, β(1, β(2 and CØ for MgCl2, MgSO4, and Mg(B6O7(OH6, the mixed ion-interaction parameters θCl,B6O10, θSO4,B6O10, ΨMg,Cl,B6O10, ΨMg,SO4,B6O10 of the systems at 308.15 K were fitted, In addition, the average equilibrium constants of the stable equilibrium solids at 308.15 K were obtained by a method using the activity product constant. Then the solubilities of the ternary systems are calculated. The calculated solubilities agree well with the experimental values.

  9. Stable Controller Reconfiguration through Terminal Connections

    DEFF Research Database (Denmark)

    Trangbæk, K; Bendtsen, Jan Dimon

    2009-01-01

    system from scratch again, it is often desirable to retain the existing control system in place and phase the new parts in gradually. This paper presents a method for introducing new control components in a smooth manner, providing stability guarantees during the transition phase, and  retaining...

  10. Electrostatic Effects in Phase Transitions of Biomembranes between Cubic Phases and Lamellar Liquid-Crystalline (Lα) phase

    Science.gov (United States)

    Masum, Shah Md.; Li, Shu Jie; Tamba, Yukihiro; Yamashita, Yuko; Yamazaki, Masahito

    2004-04-01

    Elucidation of the mechanisms of transitions between cubic phase and liquid-crystalline (Lα) phase, and between different IPMS cubic phases, are essential for understanding of dynamics of biomembranes and topological transformation of lipid membranes. Recently, we found that electrostatic interactions due to surface charges of lipid membranes induce transition between cubic phase and Lα phase, and between different IPMS cubic phases. As electrostatic interactions increase, the most stable phase of a monoolein (MO) membrane changes: Q224 ⇒ Q229 ⇒ Lα. We also found that a de novo designed peptide partitioning into electrically neutral lipid membrane changed the phase stability of the MO membranes. As peptide-1 concentration increased, the most stable phase of a MO membrane changes: Q224 ⇒ Q229 ⇒Lα. In both cases, the increase in the electrostatic repulsive interaction greatly reduced the absolute value of spontaneous curvature of the MO monolayer membrane. We also investigated factors such as poly (L-lysine) and osmotic stress to control structure and phase stability of DOPA/MO membranes. Based on these results, we discuss the mechanism of the effect of electrostatic interactions on the stability of cubic phase.

  11. Superconductivity of divalent Chevrel phases at very high pressures

    International Nuclear Information System (INIS)

    Yao, Y.S.; Guertin, R.P.; Hinks, D.G.; Jorgensen, J.; Capone II, D.W.

    1988-01-01

    The electrical resistivity and the superconducting transition temperatures were examined for three representative divalent Chevrel phase systems, SnMo 6 S 8 , EuMo 6 S 8 , and BaMo 6 S 8 , as a function of hydrostatic pressure to 2 GPa and in quasihydrostatic pressures to 10 GPa. In all systems, T/sub c/ is depressed to 0 K for sufficiently large pressures. For the Sn- and Eu-based systems, both highly purified samples and samples with controlled oxygen content were used. In an oxygenated SnMo 6 S 8 sample (less than 3% O 2 substituted for the S atoms) the pressure threshold and maximum T/sub c/ are 40% lower than in the pure sample, but for P>3.5 GPa the T/sub c/-P phase diagrams nearly coincide, with T/sub c/ reaching zero at an extrapolated pressure of about 12 GPa. In pure EuMo 6 S 8 , superconductivity appears only above a threshold pressure of about 1 GPa and is depressed to 0 K above 4.5 GPa. In an oxygenated sample the maximum T/sub c/ and the threshold pressure are depressed, and above about 3.5 GPa the T/sub c/-P phase diagrams coincide, as in the Sn-based system, although T/sub c/ is then rapidly depressed to 0 K at about 4.5 GPa. In a highly purified BaMo 6 S 8 sample superconductivity appears above about 2 GPa and is depressed to 0 K at extrapolated pressures above 12 GPa. A full transition to the zero-resistance superconducting state is observed in BaMo 6 S 8 . The data are discussed in terms of a model linking the rhombohedral-to-triclinic structural transition, the superconducting transition temperature, and the role of pressure in suppressing the structural transition

  12. Fundamentals of the LISA stable flight formation

    International Nuclear Information System (INIS)

    Dhurandhar, S V; Nayak, K Rajesh; Koshti, S; Vinet, J-Y

    2005-01-01

    The joint NASA-ESA mission, LISA, relies crucially on the stability of the three-spacecraft constellation. Each of the spacecraft is in heliocentric orbit forming a stable triangle. In this paper we explicitly show with the help of the Clohessy-Wiltshire equations that any configuration of spacecraft lying in the planes making angles of ±60 0 with the ecliptic and given suitable initial velocities within the plane, can be made stable in the sense that the inter-spacecraft distances remain constant to first order in the dimensions of the configuration compared with the distance to the Sun. Such analysis would be useful in order to carry out theoretical studies on the optical links, simulators, etc

  13. A model for a stable coronal loop

    International Nuclear Information System (INIS)

    Hoven, G.V.; Chiuderi, C.; Giachetti, R.

    1977-01-01

    We present here a new plasma-physics model of a stable active-region arch which corresponds to the structure observed in the EUV. Pressure gradients are seen, so that the equilibrium magnetic field must depart from the force-free form valid in the surrounding corona. We take advantage of the data and of the approximate cylindrical symmetry to develop a modified form of the commonly assumed sheared-spiral structure. The dynamic MHD behavior of this new pressure/field model is then evaluated by the Newcomb criterion, taken from controlled-fusion physics, and the results show short-wavelength stability in a specific parameter range. Thus we demonstrate the possibility, for pressure profiles with widths of the order of the magnetic-field scale, that such arches can persist for reasonable periods. Finally, the spatial proportions and magnetic fields of a characteristic stable coronal loop are described

  14. Utilization of stable isotopes in medicine

    International Nuclear Information System (INIS)

    1980-11-01

    The ten lectures given at this round table are presented together with a discussion. Five lectures, relating to studies in which deuterium oxide was employed as a tracer of body water, dealt with pulmonary water measurements in man and animals, the total water pool in adipose subjects, and liquid compartments in children undergoing hemodyalisis. The heavy water is analysed by infrared spectrometry and a new double spectrodoser is described. Two studies using 13 C as tracer, described the diagnosis of liver troubles and diabetes respectively. A general review of the perspectives of the application of stable isotopes in clinical medicine is followed by a comparison of the use of stable and radioactive isotopes in France [fr

  15. Stable isotope enrichment: Current and future potential

    International Nuclear Information System (INIS)

    Tracy, J.G.; Aaron, W.S.

    1992-01-01

    Oak Ridge National Laboratory (ORNL) operates the Isotope Enrichment Facility for the purpose of providing enriched stable isotopes, selected radioactive isotopes (including the actinides), and isotope-related materials and services for use in various research applications. ORNL is responsible for isotope enrichment and the distribution of approximately 225 nongaseous stable isotopes from 50 multi-isotopic elements. Many enriched isotope products are of prime importance in the fabrication of nuclear targets and the subsequent production of special radionuclides. State-of-the-art techniques to achieve special isotopic, chemical, and physical requirements are performed at ORNL This report describes the status and capabilities of the Isotope Enrichment Facility and the Isotope Research Materials Laboratory as well as emphasizing potential advancements in enrichment capabilities

  16. Stable plastid transformation in Scoparia dulcis L.

    Science.gov (United States)

    Muralikrishna, Narra; Srinivas, Kota; Kumar, Kalva Bharath; Sadanandam, Abbagani

    2016-10-01

    In the present investigation we report stable plastid transformation in Scoparia dulcis L., a versatile medicinal herb via particle gun method. The vector KNTc, harbouring aadA as a selectable marker and egfp as a reporter gene which were under the control of synthetic promoter pNG1014a, targets inverted repeats, trnR / t rnN of the plastid genome. By use of this heterologous vector, recovery of transplastomic lines with suitable selection protocol have been successfully established with overall efficiency of two transgenic lines for 25 bombarded leaf explants. PCR and Southern blot analysis demonstrated stable integration of foreign gene into the target sequences. The results represent a significant advancement of the plastid transformation technology in medicinal plants, which relevantly implements a change over in enhancing and regulating of certain metabolic pathways.

  17. On The Roman Domination Stable Graphs

    Directory of Open Access Journals (Sweden)

    Hajian Majid

    2017-11-01

    Full Text Available A Roman dominating function (or just RDF on a graph G = (V,E is a function f : V → {0, 1, 2} satisfying the condition that every vertex u for which f(u = 0 is adjacent to at least one vertex v for which f(v = 2. The weight of an RDF f is the value f(V (G = Pu2V (G f(u. The Roman domination number of a graph G, denoted by R(G, is the minimum weight of a Roman dominating function on G. A graph G is Roman domination stable if the Roman domination number of G remains unchanged under removal of any vertex. In this paper we present upper bounds for the Roman domination number in the class of Roman domination stable graphs, improving bounds posed in [V. Samodivkin, Roman domination in graphs: the class RUV R, Discrete Math. Algorithms Appl. 8 (2016 1650049].

  18. Design of optically stable image reflector system.

    Science.gov (United States)

    Tsai, Chung-Yu

    2013-08-01

    The design of a partially optically stable (POS) reflector system, in which the exit ray direction and image pose are unchanged as the reflector system rotates about a specific directional vector, was presented in an earlier study by the current group [Appl. Phys. B100, 883-890 (2010)]. The present study further proposes an optically stable image (OSI) reflector system, in which not only is the optical stability property of the POS system retained, but the image position and total ray path length are also fixed. An analytical method is proposed for the design of OSI reflector systems comprising multiple reflectors. The validity of the proposed approach is demonstrated by means of two illustrative examples.

  19. Formation of stable radicals during perfluoroalkane radiolysis

    International Nuclear Information System (INIS)

    Allayarov, S.R.; Demidov, S.V.; Kiryukhin, D.P.; Mikhajlov, A.I.; Barkalov, I.M.

    1984-01-01

    Accumulation and stabilization kinetics of perfluoroalkyls during α-radiolysis ( 60 Co) of perfluoralkanes (PFA) in a wide temperature range for different PFA fractions differing in the average molecular weight, is investigated. It is noted that low temperature (PFA) radiolysis (77 K) is of a linear nature of accumulation of stabilized radicals up to doses of approximately 700 KGy. In the case of PFA radiolysis at 300 K radiation yields of stable radicals are somewhat lower than at 47 K and at doses of 200-300 KGy, their accumulation ceases. It is shown that kinetics of formation and accumulation of stable radicals does not depend on molecular mass and PFA fraction viscosity. Perfluoroalkyl stability is explained by intra molecular conformation spheric insulation of the free valency. Perfluoroalkyl stability in different PFA fractions in a wide time range in different media is investigated

  20. Stable isotope enrichment - current and future potential

    International Nuclear Information System (INIS)

    Tracy, J.G.; Aaron, W.S.

    1993-01-01

    Oak Ridge National Laboratory (ORNL) operates the Isotope Enrichment Facility for the purpose of providing enriched stable isotopes, selected radioactive isotopes (including the actinides), and isotope-related materials and services for use in various research applications. ORNL is responsible for isotope enrichment and the distribution of approximately 225 nongaseous stable isotopes from 50 multi-isotopic elements. Many enriched isotope products are of prime importance in the fabrication of nuclear targets and the subsequent production of special radionuclides. State-of-the-art techniques to achieve special isotopic, chemical, and physical requirements are performed at ORNL. This report describes the status and capabilities of the Isotope Enrichment Facility and the Isotope Research Materials Laboratory as well as emphasizing potential advancements in enrichment capabilities. (orig.)

  1. Three phase carbon EOS model with electronic excitation

    International Nuclear Information System (INIS)

    van Thiel, M.; Ree, F.H.; Grover, R.

    1987-07-01

    A simple and rapid way for computing EOS data of multiphase solids with a liquid phase is described with emphasis on carbon. The method uses a scaling model for the liquid phase and includes a provision for electronic effects. The free energy minimum determines the stable phase

  2. Optimization of Parameters of Asymptotically Stable Systems

    Directory of Open Access Journals (Sweden)

    Anna Guerman

    2011-01-01

    Full Text Available This work deals with numerical methods of parameter optimization for asymptotically stable systems. We formulate a special mathematical programming problem that allows us to determine optimal parameters of a stabilizer. This problem involves solutions to a differential equation. We show how to chose the mesh in order to obtain discrete problem guaranteeing the necessary accuracy. The developed methodology is illustrated by an example concerning optimization of parameters for a satellite stabilization system.

  3. Multi-Stable Morphing Cellular Structures

    Science.gov (United States)

    2015-05-14

    stiffness on critical buckling load and arch stres - ses. It should be noted that although the arches in these studies snapped-through, they did not...switch roles in moving the VMT back from the second to the first stable equilibrium state. A prototype is designed and fabricated and the transition...pulling forward on the insert on the right blade and assisting its deployment. During this process the cable 3-4-1 goes slack and plays no role , but if

  4. The nature of stable insomnia phenotypes.

    Science.gov (United States)

    Pillai, Vivek; Roth, Thomas; Drake, Christopher L

    2015-01-01

    We examined the 1-y stability of four insomnia symptom profiles: sleep onset insomnia; sleep maintenance insomnia; combined onset and maintenance insomnia; and neither criterion (i.e., insomnia cases that do not meet quantitative thresholds for onset or maintenance problems). Insomnia cases that exhibited the same symptom profile over a 1-y period were considered to be phenotypes, and were compared in terms of clinical and demographic characteristics. Longitudinal. Urban, community-based. Nine hundred fifty-four adults with Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition based current insomnia (46.6 ± 12.6 y; 69.4% female). None. At baseline, participants were divided into four symptom profile groups based on quantitative criteria. Follow-up assessment 1 y later revealed that approximately 60% of participants retained the same symptom profile, and were hence judged to be phenotypes. Stability varied significantly by phenotype, such that sleep onset insomnia (SOI) was the least stable (42%), whereas combined insomnia (CI) was the most stable (69%). Baseline symptom groups (cross-sectionally defined) differed significantly across various clinical indices, including daytime impairment, depression, and anxiety. Importantly, however, a comparison of stable phenotypes (longitudinally defined) did not reveal any differences in impairment or comorbid psychopathology. Another interesting finding was that whereas all other insomnia phenotypes showed evidence of an elevated wake drive both at night and during the day, the 'neither criterion' phenotype did not; this latter phenotype exhibited significantly higher daytime sleepiness despite subthreshold onset and maintenance difficulties. By adopting a stringent, stability-based definition, this study offers timely and important data on the longitudinal trajectory of specific insomnia phenotypes. With the exception of daytime sleepiness, few clinical differences are apparent across stable phenotypes.

  5. Strongly stable real infinitesimally symplectic mappings

    NARCIS (Netherlands)

    Cushman, R.; Kelley, A.

    We prove that a mapA εsp(σ,R), the set of infinitesimally symplectic maps, is strongly stable if and only if its centralizerC(A) insp(σ,R) contains only semisimple elements. Using the theorem that everyB insp(σ,R) close toA is conjugate by a real symplectic map to an element ofC(A), we give a new

  6. A belief-based evolutionarily stable strategy

    OpenAIRE

    Deng, Xinyang; Wang, Zhen; Liu, Qi; Deng, Yong; Mahadevan, Sankaran

    2014-01-01

    As an equilibrium refinement of the Nash equilibrium, evolutionarily stable strategy (ESS) is a key concept in evolutionary game theory and has attracted growing interest. An ESS can be either a pure strategy or a mixed strategy. Even though the randomness is allowed in mixed strategy, the selection probability of pure strategy in a mixed strategy may fluctuate due to the impact of many factors. The fluctuation can lead to more uncertainty. In this paper, such uncertainty involved in mixed st...

  7. Multiple stable isotope fronts during non-isothermal fluid flow

    Science.gov (United States)

    Fekete, Szandra; Weis, Philipp; Scott, Samuel; Driesner, Thomas

    2018-02-01

    Stable isotope signatures of oxygen, hydrogen and other elements in minerals from hydrothermal veins and metasomatized host rocks are widely used to investigate fluid sources and paths. Previous theoretical studies mostly focused on analyzing stable isotope fronts developing during single-phase, isothermal fluid flow. In this study, numerical simulations were performed to assess how temperature changes, transport phenomena, kinetic vs. equilibrium isotope exchange, and isotopic source signals determine mineral oxygen isotopic compositions during fluid-rock interaction. The simulations focus on one-dimensional scenarios, with non-isothermal single- and two-phase fluid flow, and include the effects of quartz precipitation and dissolution. If isotope exchange between fluid and mineral is fast, a previously unrecognized, significant enrichment in heavy oxygen isotopes of fluids and minerals occurs at the thermal front. The maximum enrichment depends on the initial isotopic composition of fluid and mineral, the fluid-rock ratio and the maximum change in temperature, but is independent of the isotopic composition of the incoming fluid. This thermally induced isotope front propagates faster than the signal related to the initial isotopic composition of the incoming fluid, which forms a trailing front behind the zone of transient heavy oxygen isotope enrichment. Temperature-dependent kinetic rates of isotope exchange between fluid and rock strongly influence the degree of enrichment at the thermal front. In systems where initial isotope values of fluids and rocks are far from equilibrium and isotope fractionation is controlled by kinetics, the temperature increase accelerates the approach of the fluid to equilibrium conditions with the host rock. Consequently, the increase at the thermal front can be less dominant and can even generate fluid values below the initial isotopic composition of the input fluid. As kinetics limit the degree of isotope exchange, a third front may

  8. Exploring the Clapeyron Equation and the Phase Rule Using a Mechanical Drawing Toy

    Science.gov (United States)

    Darvesh, Katherine V.

    2013-01-01

    The equilibrium between phases is a key concept from the introductory physical chemistry curriculum. Phase diagrams display which phase is the most stable at a given temperature and pressure. If more than one phase has the lowest Gibbs energy, then those phases are in equilibrium under those conditions. An activity designed to demonstrate the…

  9. Mechanical Properties of Stable Glasses Using Nanoindentation

    Science.gov (United States)

    Wolf, Sarah; Liu, Tianyi; Jiang, Yijie; Ablajan, Keyume; Zhang, Yue; Walsh, Patrick; Turner, Kevin; Fakhraai, Zahra

    Glasses with enhanced stability over ordinary, liquid quenched glasses have been formed via the process of Physical Vapor Deposition (PVD) by using a sufficiently slow deposition rate and a substrate temperature slightly below the glass transition temperature. These stable glasses have been shown to exhibit higher density, lower enthalpy, and better kinetic stability over ordinary glass, and are typically optically birefringent, due to packing and orientational anisotropy. Given these exceptional properties, it is of interest to further investigate how the properties of stable glasses compare to those of ordinary glass. In particular, the mechanical properties of stable glasses remain relatively under-investigated. While the speed of sound and elastic moduli have been shown to increase with increased stability, little is known about their hardness and fracture toughness compared to ordinary glasses. In this study, glasses of 9-(3,5-di(naphthalen-1-yl)phenyl)anthracene were deposited at varying temperatures relative to their glass transition temperature, and their mechanical properties measured by nanoindentation. Hardness and elastic modulus of the glasses were compared across substrate temperatures. After indentation, the topography of these films were studied using Atomic Force Microscopy (AFM) in order to further compare the relationship between thermodynamic and kinetic stability and mechanical failure. Z.F. and P.W. acknowledge funding from NSF(DMREF-1628407).

  10. Detonation of Meta-stable Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Kuhl, Allen; Kuhl, Allen L.; Fried, Laurence E.; Howard, W. Michael; Seizew, Michael R.; Bell, John B.; Beckner, Vincent; Grcar, Joseph F.

    2008-05-31

    We consider the energy accumulation in meta-stable clusters. This energy can be much larger than the typical chemical bond energy (~;;1 ev/atom). For example, polymeric nitrogen can accumulate 4 ev/atom in the N8 (fcc) structure, while helium can accumulate 9 ev/atom in the excited triplet state He2* . They release their energy by cluster fission: N8 -> 4N2 and He2* -> 2He. We study the locus of states in thermodynamic state space for the detonation of such meta-stable clusters. In particular, the equilibrium isentrope, starting at the Chapman-Jouguet state, and expanding down to 1 atmosphere was calculated with the Cheetah code. Large detonation pressures (3 and 16 Mbar), temperatures (12 and 34 kilo-K) and velocities (20 and 43 km/s) are a consequence of the large heats of detonation (6.6 and 50 kilo-cal/g) for nitrogen and helium clusters respectively. If such meta-stable clusters could be synthesized, they offer the potential for large increases in the energy density of materials.

  11. Clinically stable angina pectoris is not necessarily associated with histologically stable atherosclerotic plaques

    NARCIS (Netherlands)

    van der Wal, A. C.; Becker, A. E.; Koch, K. T.; Piek, J. J.; Teeling, P.; van der Loos, C. M.; David, G. K.

    1996-01-01

    OBJECTIVE: To investigate the extent of plaque inflammation in culprit lesions of patients with chronic stable angina. DESIGN: Retrospective study. SETTING: Amsterdam reference centre. SUBJECTS: 89 consecutive patients who underwent directional coronary atherectomy, 58 of whom met the following

  12. Phase transitions

    CERN Document Server

    Sole, Ricard V; Solé, Ricard V; Solé, Ricard V; Sol, Ricard V; 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 of diverse ecosystems, the book illustrates the power of simple models to reveal how phase transitions occur. Introductory chapters provide the critical concepts and the simplest mathematical techniques required to study phase transitions. In a series of example-driven chapters, Ricard Solé shows how such concepts and techniques can be applied to the analysis and prediction of complex system behavior, including the origins of ...

  13. A finite element analysis of stable crack growth in inhomogeneous materials

    International Nuclear Information System (INIS)

    Miyazaki, N.; Sakai, T.; Nakagaki, M.; Sasaki, T.

    1993-01-01

    The finite element method was applied to generation phase analyses for stable crack growth in inhomogeneous materials. Experimental data on stable crack growth in bimaterial CT specimens, which were composed of a base metal and a weld metal, were numerically simulated using the node-release technique, and the variations of the fracture mechanics parameters such as J-integral. T*-integral. J-circumflex-integral and CTOA were calculated. The effects of the fusion line and the weld on the near crack fracture mechanics parameters were discussed. (author)

  14. Danish stable schools for experiential common learning in groups of organic dairy farmers

    DEFF Research Database (Denmark)

    Waarst, M.; Nissen, T.B; Østergaard, I.

    2007-01-01

    in phasing out antibiotics from their herds through promotion of animal health. One way of reaching this goal was to form participatory focused farmer groups in an FFS approach, which was adapted to Danish conditions and named "stable schools." Four stable schools were established and went through a 1-yr......The farmer field school (FFS) is a concept for farmers' learning, knowledge exchange, and empowerment that has been developed and used in developing countries. In Denmark, a research project focusing on explicit non-antibiotic strategies involves farmers who have actively expressed an interest...

  15. Laboratory test of a prototype heat storage module based on stable supercooling of sodium acetate trihydrate

    DEFF Research Database (Denmark)

    Dannemand, Mark; Kong, Weiqiang; Fan, Jianhua

    2015-01-01

    Laboratory test of a long term heat storage module utilizing the principle of stable supercooling of 199.5 kg of sodium acetate water mixture has been carried out. Avoiding phase separation of the incongruently melting salt hydrate by using the extra water principle increased the heat storage...... capacity. An external expansion vessel minimized the pressure built up in the module while heating and reduced the risk of instable supercooling. The module was stable supercooled at indoor ambient temperature for up to two months after which it was discharged. The energy discharged after activating...

  16. High-pressure phase diagram of hydrogen and deuterium sulfides from first principles: Structural and vibrational properties including quantum and anharmonic effects

    Science.gov (United States)

    Bianco, Raffaello; Errea, Ion; Calandra, Matteo; Mauri, Francesco

    2018-06-01

    We study the structural and vibrational properties of the high-temperature superconducting sulfur trihydride and trideuteride in the high-pressure I m 3 ¯m and R 3 m phases by first-principles density-functional-theory calculations. On lowering pressure, the rhombohedral transition I m 3 ¯m →R 3 m is expected, with hydrogen-bond desymmetrization and occurrence of trigonal lattice distortion. With both Perdew-Burke-Ernzerhof (PBE) and Becke-Lee-Yang-Parr (BLYP) exchange-correlation functional, in hydrostatic conditions we find that, contrary to what is suggested in some recent experiments, if the rhombohedral distortion exists it affects mainly the hydrogen bonds, whereas the resulting cell distortion is minimal. We estimate that the occurrence of a stress anisotropy of approximately 10 % could explain this discrepancy. Assuming hydrostatic conditions, we calculate the critical pressure at which the rhombohedral transition occurs. Quantum and anharmonic effects, which are relevant in this system, are included at nonperturbative level with the stochastic self-consistent harmonic approximation. Within this approach, we determine the transition pressure by calculating the free-energy Hessian, a method that allows to estimate the critical pressure with much higher precision (and much lower computational cost) compared with the free-energy "finite-difference" approach previously used. Using PBE and BLYP, we find that quantum anharmonic effects are responsible for a strong reduction of the critical pressure with respect to the one obtained with the classical harmonic approach. Interestingly, for the two functionals, even if the transition pressures at classical harmonic level differ by 83 GPa, the transition pressures including quantum anharmonic effects differ only by 23 GPa. Moreover, we observe a prominent isotope effect, as we estimate higher transition pressure for D3S than for H3S . Finally, within the stochastic self-consistent harmonic approximation, with PBE

  17. Synthesis of monoclinic potassium niobate nanowires that are stable at room temperature.

    Science.gov (United States)

    Kim, Seungwook; Lee, Ju-Hyuck; Lee, Jaeyeon; Kim, Sang-Woo; Kim, Myung Hwa; Park, Sungnam; Chung, Haegeun; Kim, Yong-Il; Kim, Woong

    2013-01-09

    We report the synthesis of KNbO(3) nanowires (NWs) with a monoclinic phase, a phase not observed in bulk KNbO(3) materials. The monoclinic NWs can be synthesized via a hydrothermal method using metallic Nb as a precursor. The NWs are metastable, and thermal treatment at ∼450 °C changed the monoclinic phase into the orthorhombic phase, which is the most stable phase of KNbO(3) at room temperature. Furthermore, we fabricated energy-harvesting nanogenerators by vertically aligning the NWs on SrTiO(3) substrates. The monoclinic NWs showed significantly better energy conversion characteristics than orthorhombic NWs. Moreover, the frequency-doubling efficiency of the monoclinic NWs was ∼3 times higher than that of orthorhombic NWs. This work may contribute to the synthesis of materials with new crystalline structures and hence improve the properties of the materials for various applications.

  18. Phase transition characteristics and associated piezoelectricity of potassium-sodium niobate lead-free ceramics.

    Science.gov (United States)

    Wang, Yuanyu; Hu, Liang; Zhang, Qilong; Yang, Hui

    2015-08-14

    To achieve high piezoelectric activity and a wide sintering temperature range, the ceramic system concerning (1 - x)(K(0.48)Na(0.52))(Nb(0.96)Sb(0.04))O(3)-x[Bi(0.5)(Na(0.7)Ag(0.3))(0.5)](0.90) Zn(0.10)ZrO(3) was designed, and the rhombohedral-tetragonal (R-T) phase boundary can drive a high d(33). Phase transition characteristics as well as their effects on the electrical properties were investigated systematically. The R-T coexistence phase boundary (0.04 ≤ x ≤ 0.05) can be driven via modification with BNAZZ, and has been confirmed by XRD and temperature-dependent dielectric constants as well as Raman analysis, and the ceramics possess enhanced piezoelectric properties (d(33) ∼ 425 pC N(-1) and k(p) ∼ 0.43) and a high unipolar strain (∼0.3%). In addition, a wide sintering temperature range of 1050-1080 °C can warrant a large d(33) of 400-430 pC N(-1), which can benefit practical applications. As a result, the addition of BNAZZ is an effective method to improve the electrical properties (piezoelectricity and strain) and sintering behavior of potassium-sodium niobate ceramics.

  19. Microstructure and magnetic behavior of Mn doped GeTe chalcogenide semiconductors based phase change materials

    Science.gov (United States)

    Adam, Adam Abdalla Elbashir; Cheng, Xiaomin; Abuelhassan, Hassan H.; Miao, Xiang Shui

    2017-06-01

    Phase-change materials (PCMs) are the most promising candidates to be used as an active media in the universal data storage and spintronic devices, due to their large differences in physical properties of the amorphous-crystalline phase transition behavior. In the present study, the microstructure, magnetic and electrical behaviors of Ge0.94Mn0.06Te thin film were investigated. The crystallographic structure of Ge0.94Mn0.06Te thin film was studied sing X-ray diffractometer (XRD) and High Resolution Transmission Electron Microscope (HR-TEM). The XRD pattern showed that the crystallization structure of the film was rhombohedral phase for GeTe with a preference (202) orientation. The HR-TEM image of the crystalline Ge0.94Mn0.06Te thin film demonstrated that, there were two large crystallites and small amorphous areas. The magnetization as a function of the magnetic field analyses of both amorphous and crystalline states showed the ferromagnetic hysteretic behaviors. Then, the hole carriers concentration of the film was measured and it found to be greater than 1021 cm-3 at room temperature. Moreover, the anomalous of Hall Effect (AHE) was clearly observed for the measuring temperatures 5, 10 and 50 K. The results demonstrated that the magnitude of AHE decreased when the temperature was increasing.

  20. A zero density change phase change memory material: GeTe-O structural characteristics upon crystallisation.

    Science.gov (United States)

    Zhou, Xilin; Dong, Weiling; Zhang, Hao; Simpson, Robert E

    2015-06-11

    Oxygen-doped germanium telluride phase change materials are proposed for high temperature applications. Up to 8 at.% oxygen is readily incorporated into GeTe, causing an increased crystallisation temperature and activation energy. The rhombohedral structure of the GeTe crystal is preserved in the oxygen doped films. For higher oxygen concentrations the material is found to phase separate into GeO2 and TeO2, which inhibits the technologically useful abrupt change in properties. Increasing the oxygen content in GeTe-O reduces the difference in film thickness and mass density between the amorphous and crystalline states. For oxygen concentrations between 5 and 6 at.%, the amorphous material and the crystalline material have the same density. Above 6 at.% O doping, crystallisation exhibits an anomalous density change, where the volume of the crystalline state is larger than that of the amorphous. The high thermal stability and zero-density change characteristic of Oxygen-incorporated GeTe, is recommended for efficient and low stress phase change memory devices that may operate at elevated temperatures.