Science.gov

Sample records for fermi liquid behavior

  1. Magnetic moments and non-Fermi-liquid behavior in quasicrystals

    NASA Astrophysics Data System (ADS)

    Andrade, Eric

    Motivated by the intrinsic non-Fermi-liquid behavior observed in the heavy-fermion quasicrystal Au51Al34Yb15, we study the low-temperature behavior of dilute magnetic impurities placed in metallic quasicrystals. We find that a large fraction of the magnetic moments are not quenched down to very low temperatures, leading to a power-law distribution of Kondo temperatures, accompanied by a non-Fermi-liquid behavior, in a remarkable similarity to the Kondo-disorder scenario found in disordered heavy-fermion metals. This work was supported by FAPESP (Brazil) Grant No. 2013/00681-8.

  2. Non-Fermi liquid behavior from dynamical effects of impurity scattering in correlated Fermi liquids

    NASA Astrophysics Data System (ADS)

    Pramod, Kumar; Vidhyadhiraja, N. S.

    2014-03-01

    The interplay of disorder and interactions is a subject of perennial interest. In this work, we have investigated the effect of disorder due to chemical substitution on the dynamics and transport properties of correlated Fermi liquids. A low frequency analysis in the concentrated and dilute limits shows that the dynamical local potentials arising through disorder averaging generate a linear (in frequency) term in the scattering rate. Such non-Fermi liquid behavior (nFL) is investigated in detail for Kondo hole substitution in heavy fermions within dynamical mean field theory. We find closed form expressions for the dependence of the static and linear terms in the scattering rate on substitutional disorder and model parameters. We argue that the low temperature resistivity will acquire a linear in temperature term, and show that the Drude peak structure in the optical conductivity will disappear beyond a certain disorder pc, that marks the crossover from lattice coherent to single-impurity behavior. A full numerical solution of the dynamical mean field theory equations reveals that the nFL term will show up significantly only in certain regimes, although it is present for any non-zero disorder concentration in principle. DST India and CSIR India.

  3. Nonanalytic corrections to the Fermi-liquid behavior

    NASA Astrophysics Data System (ADS)

    Chubukov, Andrey V.; Maslov, Dmitrii L.

    2003-10-01

    The issue of nonanalytic corrections to the Fermi-liquid behavior is revisited. Previous studies have indicated that the corrections to the Fermi-liquid forms of the specific heat and the static spin susceptibility (CFL∝T, χFLs=const) are nonanalytic in D⩽3 and scale as δC(T)∝TD, χs(T)∝TD-1, and χs(Q)∝QD-1, with extra logarithms in D=3 and 1. It is shown that these nonanalytic corrections originate from the universal singularities in the dynamical bosonic response functions of a generic Fermi liquid. In contrast to the leading, Fermi-liquid forms which depend on the interaction averaged over the Fermi surface, the nonanalytic corrections are parametrized by only two coupling constants, which are the components of the interaction potential at momentum transfers q=0 and q=2pF. For three-dimensional (3D) systems, a recent result of Belitz, Kirkpatrick, and Vojta for the spin susceptibility is reproduced and the issue why a nonanalytic momentum dependence, χs(Q,T=0)-χFLs∝Q2log Q, is not paralleled by a nonanalyticity in the T dependence [χs(0,T)-χFLs]∝T2 is clarified. For 2D systems, explicit forms of C(T)-CFL∝T2, χ(Q,T=0)-χFL∝|Q|, and χ(0,T)-χFL∝T are obtained. It is shown that earlier calculations of the temperature dependences in two dimensions are incomplete.

  4. Annealing, lattice disorder, and non-Fermi-liquid behavior in UCu4Pd

    NASA Astrophysics Data System (ADS)

    Booth, C. H.; Scheidt, E.-W.; Killer, U.; Weber, A.; Kehrein, S.

    2002-10-01

    The magnetic and electronic properties of non-Fermi-liquid UCu4Pd depend on annealing conditions. Local structural changes due to this annealing are reported from U LIII- and Pd K-edge x-ray-absorption fine-structure measurements. In particular, annealing decreases the fraction of Pd atoms on nominally Cu 16e sites and the U-Cu pair-distance distribution width. This study provides quantitative information on the amount of disorder in UCu4Pd and allows an assessment of its possible importance to the observed non-Fermi-liquid behavior.

  5. Annealing, lattice disorder and non-Fermi liquid behavior in UCu4Pd

    SciTech Connect

    Booth, C.H.; Scheidt, E.-W.; Killer, U.; Weber, A.; Kehrein, S.

    2002-07-30

    The magnetic and electronic properties of non-Fermi liquid UCu{sub 4Pd} depend on annealing conditions. Local structural changes due to this annealing are reported from UL{sub III}- and Pd K-edge x-ray absorption fine-structure measurements. In particular, annealing decreases the fraction of Pd atoms on nominally Cu 16e sites and the U-Cu pair-distance distribution width. This study provides quantitative information on the amount of disorder in UCu{sub 4Pd} and allows an assessment of its possible importance to the observed non-Fermi liquid behavior.

  6. Non-Fermi-Liquid Behavior in Metallic Quasicrystals with Local Magnetic Moments.

    PubMed

    Andrade, Eric C; Jagannathan, Anuradha; Miranda, Eduardo; Vojta, Matthias; Dobrosavljević, Vladimir

    2015-07-17

    Motivated by the intrinsic non-Fermi-liquid behavior observed in the heavy-fermion quasicrystal Au51Al34Yb15, we study the low-temperature behavior of dilute magnetic impurities placed in metallic quasicrystals. We find that a large fraction of the magnetic moments are not quenched down to very low temperatures T, leading to a power-law distribution of Kondo temperatures P(T(K))∼T(K)(α-1), with a nonuniversal exponent α, in a remarkable similarity to the Kondo-disorder scenario found in disordered heavy-fermion metals. For α<1, the resulting singular P(T(K)) induces non-Fermi-liquid behavior with diverging thermodynamic responses as T→0. PMID:26230810

  7. Non-Fermi-Liquid Behavior in Metallic Quasicrystals with Local Magnetic Moments

    NASA Astrophysics Data System (ADS)

    Andrade, Eric C.; Jagannathan, Anuradha; Miranda, Eduardo; Vojta, Matthias; Dobrosavljević, Vladimir

    2015-07-01

    Motivated by the intrinsic non-Fermi-liquid behavior observed in the heavy-fermion quasicrystal Au51Al34Yb15 , we study the low-temperature behavior of dilute magnetic impurities placed in metallic quasicrystals. We find that a large fraction of the magnetic moments are not quenched down to very low temperatures T , leading to a power-law distribution of Kondo temperatures P (TK)˜TKα -1, with a nonuniversal exponent α , in a remarkable similarity to the Kondo-disorder scenario found in disordered heavy-fermion metals. For α <1 , the resulting singular P (TK) induces non-Fermi-liquid behavior with diverging thermodynamic responses as T →0 .

  8. Theory of helimagnons in itinerant quantum systems. II. Nonanalytic corrections to Fermi-liquid behavior

    NASA Astrophysics Data System (ADS)

    Belitz, D.; Kirkpatrick, T. R.; Rosch, A.

    2006-07-01

    A recent theory for the ordered phase of helical or chiral magnets such as MnSi is used to calculate observable consequences of the helical Goldstone modes or helimagnons. In systems with no quenched disorder, the helimagnon contribution to the specific heat coefficient is shown to have a linear temperature dependence, while the quasiparticle inelastic scattering rate is anisotropic in momentum space and depends on the electronic dispersion relation. For cubic lattices the generic temperature dependence is given by a non-Fermi-liquid T3/2 behavior. The contribution to the temperature dependence of the resistivity is shown to be T5/2 in a Boltzmann approximation. The helimagnon thus leads to nonanalytic corrections to Fermi-liquid behavior. Implications for experiments, and for transport theories beyond the Boltzmann level, are discussed.

  9. Non-Fermi liquid behavior of the drag and diffusion coefficients in QED plasma

    SciTech Connect

    Sarkar, Sreemoyee; Dutt-Mazumder, Abhee K.

    2011-11-01

    We calculate the drag and diffusion coefficients in low temperature QED plasma and go beyond the leading order approximation. The non-Fermi-liquid behavior of these coefficients are clearly revealed. We observe that the subleading contributions due to the exchange of soft transverse photon in both cases are larger than the leading order terms coming from the longitudinal sector. The results are presented in closed form at zero and low temperature.

  10. Criterion for stability of Goldstone modes and Fermi liquid behavior in a metal with broken symmetry

    PubMed Central

    Watanabe, Haruki; Vishwanath, Ashvin

    2014-01-01

    There are few general physical principles that protect the low-energy excitations of a quantum phase. Of these, Goldstone’s theorem and Landau–Fermi liquid theory are the most relevant to solids. We investigate the stability of the resulting gapless excitations—Nambu–Goldstone bosons (NGBs) and Landau quasiparticles—when coupled to one another, which is of direct relevance to metals with a broken continuous symmetry. Typically, the coupling between NGBs and Landau quasiparticles vanishes at low energies, leaving the gapless modes unaffected. If, however, the low-energy coupling is nonvanishing, non-Fermi liquid behavior and overdamped bosons are expected. Here we prove a general criterion that specifies when the coupling is nonvanishing. It is satisfied by the case of a nematic Fermi fluid, consistent with earlier microscopic calculations. In addition, the criterion identifies a new kind of symmetry breaking—of magnetic translations—where nonvanishing couplings should arise, opening a previously unidentified route to realizing non-Fermi liquid phases. PMID:25349386

  11. Criterion for stability of Goldstone modes and Fermi liquid behavior in a metal with broken symmetry.

    PubMed

    Watanabe, Haruki; Vishwanath, Ashvin

    2014-11-18

    There are few general physical principles that protect the low-energy excitations of a quantum phase. Of these, Goldstone's theorem and Landau-Fermi liquid theory are the most relevant to solids. We investigate the stability of the resulting gapless excitations--Nambu-Goldstone bosons (NGBs) and Landau quasiparticles--when coupled to one another, which is of direct relevance to metals with a broken continuous symmetry. Typically, the coupling between NGBs and Landau quasiparticles vanishes at low energies, leaving the gapless modes unaffected. If, however, the low-energy coupling is nonvanishing, non-Fermi liquid behavior and overdamped bosons are expected. Here we prove a general criterion that specifies when the coupling is nonvanishing. It is satisfied by the case of a nematic Fermi fluid, consistent with earlier microscopic calculations. In addition, the criterion identifies a new kind of symmetry breaking--of magnetic translations--where nonvanishing couplings should arise, opening a previously unidentified route to realizing non-Fermi liquid phases. PMID:25349386

  12. Ferromagnetic Kondo lattice CeRuSi{sub 2} with non-Fermi-liquid behavior

    SciTech Connect

    Nikiforov, V. N.; Baran, M.; Irkhin, V. Yu.

    2013-05-15

    The structure, electronic, thermodynamic, and magnetic properties of the CeRuSi{sub 2} Kondo lattice with ferromagnetic ordering characterized by a small moment of the ground state are investigated. Anomalies in the temperature dependences of heat capacity and resistivity (unusual power or logarithmic behavior) observed in the low-temperature range indicate a non-Fermi-liquid behavior. The results are compared with those for other Ce{sub l}Ru{sub n}X{sub m} compounds and anomalous systems based on rare-earth elements and actinides that had been studied earlier.

  13. Tuning bad metal and non-Fermi liquid behavior in a Mott material: Rare-earth nickelate thin films.

    PubMed

    Mikheev, Evgeny; Hauser, Adam J; Himmetoglu, Burak; Moreno, Nelson E; Janotti, Anderson; Van de Walle, Chris G; Stemmer, Susanne

    2015-11-01

    Resistances that exceed the Mott-Ioffe-Regel limit (known as bad metal behavior) and non-Fermi liquid behavior are ubiquitous features of the normal state of many strongly correlated materials. We establish the conditions that lead to bad metal and non-Fermi liquid phases in NdNiO3, which exhibits a prototype bandwidth-controlled metal-insulator transition. We show that resistance saturation is determined by the magnitude of Ni eg orbital splitting, which can be tuned by strain in epitaxial films, causing the appearance of bad metal behavior under certain conditions. The results shed light on the nature of a crossover to a non-Fermi liquid metal phase and provide a predictive criterion for Anderson localization. They elucidate a seemingly complex phase behavior as a function of film strain and confinement and provide guidelines for orbital engineering and novel devices. PMID:26601140

  14. Tuning bad metal and non-Fermi liquid behavior in a Mott material: Rare-earth nickelate thin films

    PubMed Central

    Mikheev, Evgeny; Hauser, Adam J.; Himmetoglu, Burak; Moreno, Nelson E.; Janotti, Anderson; Van de Walle, Chris G.; Stemmer, Susanne

    2015-01-01

    Resistances that exceed the Mott-Ioffe-Regel limit (known as bad metal behavior) and non-Fermi liquid behavior are ubiquitous features of the normal state of many strongly correlated materials. We establish the conditions that lead to bad metal and non-Fermi liquid phases in NdNiO3, which exhibits a prototype bandwidth-controlled metal-insulator transition. We show that resistance saturation is determined by the magnitude of Ni eg orbital splitting, which can be tuned by strain in epitaxial films, causing the appearance of bad metal behavior under certain conditions. The results shed light on the nature of a crossover to a non-Fermi liquid metal phase and provide a predictive criterion for Anderson localization. They elucidate a seemingly complex phase behavior as a function of film strain and confinement and provide guidelines for orbital engineering and novel devices. PMID:26601140

  15. Non-Fermi liquid behavior in quantum critical iron-pnictide metal Ba(Fe,Ni,Co)2As2

    NASA Astrophysics Data System (ADS)

    Nakajima, Yasuyuki; Kirshenbaum, Kevin; Hughes, Alex; Eckberg, Christopher; Wang, Renxiong; Metz, Tristin; Saha, Shanta; Paglione, Johnpierre

    The breakdown of Landau's Fermi liquid theory has been believed to be induced by quantum fluctuations in the vicinity of a quantum critical point (QCP), occasionally accompanied by exotic superconductivity in the strongly correlated electron systems, such as cuprate and iron pnictide superconductors. However, the superconducting dome of such materials with high Tc precludes us from investigating the interplay between quantum fluctuations and the exotic superconductivity. We report non-Fermi liquid behavior associated with quantum fluctuations in the transport and thermodynamic properties of the non-superconducting iron pnictide Ba(Fe,Co,Ni)2As2, which allows us to elucidate the behavior on cooling down to near absolute zero without distractions from the superconductivity. We will discuss the evolution of non-Fermi liquid behavior with magnetic field, highlighting the presence of field tuned QCP.

  16. Magnetic ordering and non-Fermi-liquid behavior in the multichannel Kondo-lattice model

    NASA Astrophysics Data System (ADS)

    Irkhin, Valentin Yu.

    2016-05-01

    Scaling equations for the Kondo lattice in the paramagnetic and magnetically ordered phases are derived to next-leading order with account of spin dynamics. The results are applied to describe various mechanisms of the non-Fermi-liquid (NFL) behavior in the multichannel Kondo-lattice model where a fixed point occurs in the weak-coupling region. The corresponding temperature dependences of electronic and magnetic properties are discussed. The model describes naturally formation of a magnetic state with soft boson mode and small moment value. An important role of Van Hove singularities in the magnon spectral function is demonstrated. The results are rather sensitive to the type of magnetic ordering and space dimensionality, the conditions for NFL behavior being more favorable in the antiferromagnetic and 2D cases.

  17. Kondo effect and non-Fermi-liquid behavior in Dirac and Weyl semimetals

    NASA Astrophysics Data System (ADS)

    Principi, Alessandro; Vignale, Giovanni; Rossi, E.

    2015-07-01

    We study the Kondo effect in three-dimensional (3D) Dirac materials and Weyl semimetals. We find the scaling of the Kondo temperature with respect to the doping n and the coupling J between the moment of the magnetic impurity and the carriers of the semimetal. We consider the interplay of long-range scalar disorder and Kondo screening and find that it causes the Kondo effect to be characterized not by a Kondo temperature, but by a distribution of Kondo temperatures with features that cause the appearance of strong non-Fermi-liquid behavior. We then consider the effect of Kondo screening, and of the interplay of Kondo screening and long-range scalar disorder, on the transport properties of Weyl semimetals. Finally, we compare the properties of the Kondo effect in 3D and 2D Dirac materials such as graphene and topological insulators.

  18. Lectures of Fermi liquid theory

    SciTech Connect

    Bedell, K.S.

    1993-01-01

    The Fermi liquid theory was first introduced by Landau in 1956 to provide a theoretical basis for the properties of strongly correlated Fermi systems. This theory has proven to be crucial for our understanding of a broad range of materials. These include liquid [sup 3]He, [sup 3]He-[sup 4]He mixtures, simple metals, heavy-fermions, and nuclear matter to name a few. In the high temperature superconductors questions have been raised regarding the applicability of Fermi liquid theory to the normal state behavior of these materials. I will not address this issue in these lectures. My focus will be to summarize the foundations of this theory and to explore the consequences. These lectures are in part a summary of the excellent review article by Baym and Pethick and the books by Pines and Nozieres and Baym and Pethick. They include as well a summary of some articles that I have authored and co-authored. In the main body of the lectures I will not make any additional references to the books or articles. In the absence of reading the original materials, my lectures should provide the essentials of a mini-course in Fermi liquid theory.

  19. Lectures of Fermi liquid theory

    SciTech Connect

    Bedell, K.S.

    1993-07-01

    The Fermi liquid theory was first introduced by Landau in 1956 to provide a theoretical basis for the properties of strongly correlated Fermi systems. This theory has proven to be crucial for our understanding of a broad range of materials. These include liquid {sup 3}He, {sup 3}He-{sup 4}He mixtures, simple metals, heavy-fermions, and nuclear matter to name a few. In the high temperature superconductors questions have been raised regarding the applicability of Fermi liquid theory to the normal state behavior of these materials. I will not address this issue in these lectures. My focus will be to summarize the foundations of this theory and to explore the consequences. These lectures are in part a summary of the excellent review article by Baym and Pethick and the books by Pines and Nozieres and Baym and Pethick. They include as well a summary of some articles that I have authored and co-authored. In the main body of the lectures I will not make any additional references to the books or articles. In the absence of reading the original materials, my lectures should provide the essentials of a mini-course in Fermi liquid theory.

  20. Non-Fermi-liquid behavior within the ferromagnetic phase in URu2-xRexSi2.

    PubMed

    Bauer, E D; Zapf, V S; Ho, P-C; Butch, N P; Freeman, E J; Sirvent, C; Maple, M B

    2005-02-01

    The URu2-xRexSi2 system exhibits ferromagnetic order for Re concentrations 0.3 < x < or =1.0. Non-Fermi-liquid (NFL) behavior is observed in the specific heat for 0.15< or = x< or =0.6 [C/T proportional to, -lnT (or T(-0.1))], and also in the power-law T dependence of the electrical resistivity [rhoT proportional to, Tn] with n<2 for 0.15< or = x <0.8, at low T, providing strong evidence that the NFL behavior persists within the ferromagnetic phase. Furthermore, the deviation of the physical properties of URu2-xRexSi2 from Fermi-liquid behavior is most pronounced at the ferromagnetic quantum critical point, and the NFL behavior found in the ferromagnetic phase may be consistent with the Griffiths-McCoy phase model. PMID:15783577

  1. Non-Fermi liquid behavior and non-universal superconducting gap structure in Fe-pnictides

    NASA Astrophysics Data System (ADS)

    Matsuda, Yuji

    2010-03-01

    The discovery of Fe-pnictide superconductors with Tc exceeding 55 K raises fundamental questions about origin of high-Tc superconductivity. Here we report the systematic studies of the normal-state charge transport, Fermi surface structure and superconducting gap structure in high-quality single crystals of BaFe2(As1-xPx)2 (0 <=x <=0.71), ranging from the SDW state to overdoped Fermi liquid state. Near the SDW boundary, the transport coefficients, including resistivity, Hall coefficient and magnetoresistance, exhibit striking deviations from the Fermi liquid properties [1]. The Fermi surface structure determined by the dHvA effect shows that in the superconducting dome the volume of the electron and hole sheets shrink linearly and the effective masses become strongly enhanced with decreasing x [2]. It is likely that these trends originate from the many-body interaction which gives rise to superconductivity. The penetration depth, thermal conductivity and NMR data for BaFe2(As0.67P0.33)2 (Tc=30 K) provide unambiguous evidence for line nodes in the superconducting gap function [3], in sharp contrast to the other Fe-based compounds with fully gapped structure. This indicates that the gap structure of Fe-based high-Tc superconductors is not universal.[1] S. Kasahara et al., arXiv:0905.4427 [2] H. Shishido et al., arXiv:0910.3634 [3] K. Hashimoto et al., arXiv:0907.4399 [4] K. Hashimoto et al., Phys. Rev. Lett. 102, 017002 (2009), ibid 102, 207001 (2009).

  2. Non-Fermi-liquid behavior of large-NB quantum critical metals

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, A. Liam; Kachru, Shamit; Kaplan, Jared; Raghu, S.

    2014-04-01

    The problem of continuous quantum phase transitions in metals involves critical bosons coupled to a Fermi surface. We solve the theory in the limit of a large number, NB, of bosonic flavors, where the bosons transform in the adjoint representation (a matrix representation), while the fermions are in the fundamental representation (a vector representation) of a global SU (NB) flavor symmetry group. The leading large NB solution corresponds to a non-Fermi liquid coupled to Wilson-Fisher bosons. In a certain energy range, the fermion velocity vanishes—resulting in the destruction of the Fermi surface. Subleading 1/NB corrections correspond to a qualitatively different form of Landau damping of the bosonic critical fluctuations. We discuss the model in d =3-ɛ but because of the additional control afforded by large NB, our results are valid down to d =2. In the limit ɛ ≪1, the large NB solution is consistent with the renormalization group analysis of Fitzpatrick et al. [Phys. Rev. B 88, 125116 (2013), 10.1103/PhysRevB.88.125116].

  3. Aspects of non-Fermi-liquid metals

    NASA Astrophysics Data System (ADS)

    Pivovarov, Eugene

    We consider several examples of metallic systems that exhibit non-Fermi-liquid behavior. In these examples the system is not a Fermi liquid due to the presence of a "hidden" order. The primary models are density waves with an odd-frequency-dependent order parameter and density waves with d-wave symmetry. In the first model, the same-time correlation functions vanish and there is a conventional Fermi surface. In the second model, the gap vanishes at the nodes. We derive the phase diagrams and study the thermodynamic and kinetic properties. We also consider the effects of competing orders on the phase diagram when the underlying microscopic interaction has a high symmetry.

  4. Nonanalytic magnetic response of Fermi and non-Fermi liquids

    NASA Astrophysics Data System (ADS)

    Maslov, Dmitrii L.; Chubukov, Andrey V.; Saha, Ronojoy

    2006-12-01

    We study the nonanalytic behavior of the static spin susceptibility of two-dimensional fermions as a function of temperature and magnetic field. For a generic Fermi liquid, χs(T,H)=const+c1max{T,μB∣H∣} , where c1 is shown to be expressed via complicated combinations of the Landau parameters, rather than via the backscattering amplitude, contrary to the case of the specific heat. Near a ferromagnetic quantum critical point, the field dependence acquires a universal form χs-1(H)=const-c2∣H∣3/2 , with c2>0 . This behavior implies a first-order transition into a ferromagnetic state. We establish a criterion for such a transition to win over the transition into an incommensurate phase.

  5. Non-Fermi-liquid behavior from partial nesting in multiorbital superconductors

    NASA Astrophysics Data System (ADS)

    Setty, Chandan; Phillips, Philip W.

    2016-03-01

    Partial nesting between two connected or disconnected regions of the Fermi surface leads to fractional powers of the Coulomb scattering lifetime as a function of temperature. This result is first demonstrated for a toy band structure where partial nesting occurs within a single band and between different regions of the Brillouin zone. A comparison is then made to a multiband scenario by studying the scattering rate of an effective two-orbital model that was proposed in the context of multiorbital superconductors. In the process, various model independent features affecting the temperature exponent n are identified. The logarithmically divergent contributions of the lowest order vertex correction to the multiorbital susceptibility, and the role played by nesting in suppressing these divergences, is analyzed. The relevance of these results is discussed keeping the recently observed anomalous resistivity in the Co doped iron superconductor LiFeAs as a backdrop.

  6. Deviations from Fermi-Liquid Behavior above Tc in 2D Short Coherence Length Superconductors

    NASA Astrophysics Data System (ADS)

    Trivedi, Nandini; Randeria, Mohit

    1995-07-01

    We show that there are qualitative differences between the temperature dependence of the spin and charge correlations in the normal state of the 2D attractive Hubbard model using quantum Monte Carlo simulations. The one-particle density of states shows a pseudogap above Tc with a depleted N0 with decreasing T. The susceptibility χs and the low frequency spin spectral weight track N0, which explains the spin-gap scaling: 1/T1T~χsT. However, collective excitations contribute to the charge channel, and the compressibility dn/dμ is T independent. This anomalous ``spin-charge separation'' is shown to exist even at intermediate \\|U\\| where the momentum distribution nk gives evidence for a degenerate Fermi system.

  7. Hidden non-Fermi liquid behavior caused by magnetic phase transition in Ni-doped Ba-122 pnictides

    PubMed Central

    Lee, Seokbae; Choi, Ki-Young; Jung, Eilho; Rho, Seulki; Shin, Soohyeon; Park, Tuson; Hwang, Jungseek

    2015-01-01

    We studied two BaFe2−xNixAs2 (Ni-doped Ba-122) single crystals at two different doping levels (underdoped and optimally doped) using an optical spectroscopic technique. The underdoped sample shows a magnetic phase transition around 80 K. We analyze the data with a Drude-Lorentz model with two Drude components (D1 and D2). It is known that the narrow D1 component originates from electron carriers in the electron-pockets and the broad D2 mode is from hole carriers in the hole-pockets. While the plasma frequencies of both Drude components and the static scattering rate of the broad D2 component show negligible temperature dependencies, the static scattering rate of the D1 mode shows strong temperature dependence for the both samples. We observed a hidden quasi-linear temperature dependence in the scattering rate of the D1 mode above and below the magnetic transition temperature while in the optimally doped sample the scattering rate shows a more quadratic temperature dependence. The hidden non-Fermi liquid behavior in the underdoped sample seems to be related to the magnetic phase of the material. PMID:26184412

  8. Fermi liquids near Pomeranchuk instabilities

    NASA Astrophysics Data System (ADS)

    Reidy, Kelly Elizabeth

    We explore features of a Fermi liquid near generalized Pomeranchuk instabilities (PIs) starting from both ordered and disordered phases. These PIs can be viewed as quantum critical points in parameter space, and thus provide an alternate viewpoint on quantum criticality. We employ the tractable crossing symmetric equation method, which is a non-perturbative diagrammatic many-particle method used to calculate the Fermi liquid interaction functions and scattering amplitudes. We consider both repulsive and attractive underlying interactions of arbitrary strength. Starting from a ferromagnetically ordered ground state, we find that upon approach to an s-wave instability in one critical channel, the system simultaneously approaches instabilities in non-critical channels. We study origins and implications of this "quantum multicriticality". We also find that a nematic (non-s-wave) instability precedes and is driven by Pomeranchuk instabilities in both the s-wave spin and density channels. Finally, we discuss potential applications of our results to physical systems, such as ferromagnetic superconductors.

  9. Deviations from Fermi-liquid behavior in (2+1)-dimensional quantum electrodynamics and the normal phase of high-Tc superconductors

    NASA Astrophysics Data System (ADS)

    Aitchison, I. J. R.; Mavromatos, N. E.

    1996-04-01

    We argue that the gauge-fermion interaction in multiflavor quantum electrodynamics in (2+1) dimensions is responsible for non-Fermi-liquid behavior in the infrared, in the sense of leading to the existence of a nontrivial (quasi)fixed point that lies between the trivial fixed point (at infinite momenta) and the region where dynamical symmetry breaking and mass generation occurs. This quasifixed-point structure implies slowly varying, rather than fixed, couplings in the intermediate regime of momenta, a situation which resembles that of (four-dimensional) ``walking technicolor'' models of particle physics. The inclusion of wave-function renormalization yields marginal O(1/N) corrections to the ``bulk'' non-Fermi-liquid behavior caused by the gauge interaction in the limit of infinite flavor number. Such corrections lead to the appearance of modified critical exponents. In particular, at low temperatures there appear to be logarithmic scaling violations of the linear resistivity of the system of order O(1/N). The connection with the anomalous normal-state properties of certain condensed-matter systems relevant for high-temperature superconductivity is briefly discussed. The relevance of the large (flavor) N expansion to the Fermi-liquid problem is emphasized. As a partial result of our analysis, we point out the absence of charge-density-wave instabilities from the effective low-energy theory, as a consequence of gauge invariance.

  10. Local Moment, Itinerancy, and Deviation from Fermi-Liquid Behavior in NaxCoO2 for 0.71≤x≤0.84

    NASA Astrophysics Data System (ADS)

    Balicas, L.; Jo, Y. J.; Shu, G. J.; Chou, F. C.; Lee, P. A.

    2008-03-01

    Here we report the observation of Fermi surface (FS) pockets via the Shubnikov de Haas effect in NaxCoO2 for x=0.71 and 0.84, respectively. Our observations indicate that the FS expected for each compound intersects their corresponding Brillouin zones, as defined by the previously reported superlattice structures, leading to small reconstructed FS pockets, but only if a precise number of holes per unit cell is localized. For 0.71≤x<0.75 the coexistence of itinerant carriers and localized S=1/2 spins on a paramagnetic triangular superlattice leads at low temperatures to the observation of a deviation from standard Fermi-liquid behavior in the electrical transport and heat capacity properties, suggesting the formation of some kind of quantum spin-liquid ground state.

  11. Renormalization group and the superconducting susceptibility of a Fermi liquid

    SciTech Connect

    Parameswaran, S. A.; Sondhi, S. L.; Shankar, R.

    2010-11-15

    A free Fermi gas has, famously, a superconducting susceptibility that diverges logarithmically at zero temperature. In this paper we ask whether this is still true for a Fermi liquid and find that the answer is that it does not. From the perspective of the renormalization group for interacting fermions, the question arises because a repulsive interaction in the Cooper channel is a marginally irrelevant operator at the Fermi liquid fixed point and thus is also expected to infect various physical quantities with logarithms. Somewhat surprisingly, at least from the renormalization group viewpoint, the result for the superconducting susceptibility is that two logarithms are not better than one. In the course of this investigation we derive a Callan-Symanzik equation for the repulsive Fermi liquid using the momentum-shell renormalization group, and use it to compute the long-wavelength behavior of the superconducting correlation function in the emergent low-energy theory. We expect this technique to be of broader interest.

  12. Quantum Melting of Charge Ice and Non-Fermi-Liquid Behavior: An Exact Solution for the Extended Falicov-Kimball Model in the Ice-Rule Limit

    NASA Astrophysics Data System (ADS)

    Udagawa, Masafumi; Ishizuka, Hiroaki; Motome, Yukitoshi

    2010-06-01

    An exact solution is obtained for a model of itinerant electrons coupled to ice-rule variables on the tetrahedron Husimi cactus, an analogue of the Bethe lattice of corner-sharing tetrahedra. It reveals a quantum critical point with the emergence of non-Fermi-liquid behavior in melting of the “charge ice” insulator. The electronic structure is compared with the numerical results for the pyrochlore-lattice model to elucidate the physics of electron systems interacting with the tetrahedron ice rule.

  13. Non-Fermi Liquid Behavior in Quasi-One-Dimensional Li0.9Mo6O17

    SciTech Connect

    Hager, J.; Matzdorf, R.; He, Jian; Jin, Rongying; Mandrus, David; Cazalilla, M.; Plummer, E Ward

    2005-01-01

    We present temperature dependent scanning tunneling spectroscopy data of the quasi-one-dimensional conductor Li{sub 0.9}Mo{sub 6}O{sub 17}. The differential tunneling current in our low-temperature spectra shows a power-law behavior around the Fermi energy, which is expected for a clean Luttinger liquid. The power-law exponent is found to be 0.6. Spectra for a temperature range of 5 to 55 K can be fitted fairly well with a model for tunneling into a Luttinger liquid at the appropriate temperature. A fit with a model based on a zero bias anomaly is significantly worse compared to the Luttinger liquid model. No signature of a phase transition at T = 24 K is observed in our temperature dependent data.

  14. Non-Fermi-Liquid Behavior and Anomalous Suppression of Landau Damping in Layered Metals Close to Ferromagnetism

    NASA Astrophysics Data System (ADS)

    Ridgway, Sam P.; Hooley, Chris A.

    2015-06-01

    We analyze the low-energy physics of nearly ferromagnetic metals in two spatial dimensions using the functional renormalization group technique. We find a new low-energy fixed point, at which the fermionic (electronlike) excitations are non-Fermi-liquid (zf=13 /10 ) and the magnetic fluctuations exhibit an anomalous Landau damping whose rate vanishes as Γq˜|q |3 /5 in the low-|q | limit. We discuss this renormalization of the Landau-damping exponent, which is the major novel prediction of our work, and highlight the possible link between that renormalization and neutron-scattering data on UGe2 and related compounds. Implications of our analysis for YFe2Al10 are also discussed.

  15. Nonanalytic Magnetic Response of Fermi- and non-Fermi Liquids

    NASA Astrophysics Data System (ADS)

    Chubukov, Andrey; Maslov, Dmitrii; Saha, Ronojoy

    2007-03-01

    We revisit the issue of the non-analytic dependence of the static spin susceptibility of a 2D Fermi liquid on temperature and a magnetic field, χs(T, H) = χ0+ A T fχ(μB|H|/T). We show that in a generic Fermi liquid the prefactor A is expressed via complex combinations of the Landau parameters, and does not reduce to the backscattering amplitude, contrary to the case of the specific heat C(T, H). We show that this distinction with the specific heat is mostly relevant near a ferromagnetic QCP -- the non-analytic terms in χs(T,H) are less singular near QCP than those in C(T, H).

  16. Emergence of non-Fermi liquid behaviors in 5d perovskite SrIrO3 thin films: Interplay between correlation, disorder, and spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Biswas, Abhijit; Kim, Ki-Seok; Jeong, Yoon H.

    2016-02-01

    We investigate the effects of compressive strain on the electrical resistivity of 5d iridium based perovskite SrIrO3 by depositing epitaxial films of thickness 35 nm on various substrates such as GdScO3 (110), DyScO3 (110), and SrTiO3 (001). Surprisingly, we find anomalous transport behaviors as expressed by ρ∝Tε in the temperature dependent resistivity, where the temperature exponent ε evolves continuously from 4/5 to 1 and to 3/2 with an increase of compressive strain. Furthermore, magnetoresistance always remains positive irrespective of resistivity upturns at low temperatures. These observations imply that the delicate interplay between correlation and disorder in the presence of strong spin-orbit coupling is responsible for the emergence of the non-Fermi liquid behaviors in 5d perovskite SrIrO3 thin films. We offer a theoretical framework for the interpretation of the experimental results.

  17. Breakdown of Fermi liquid behavior near the hot spots in a two-dimensional model: A two-loop renormalization group analysis

    NASA Astrophysics Data System (ADS)

    de Carvalho, Vanuildo S.; Freire, Hermann

    2013-10-01

    Motivated by a recent experimental observation of a nodal liquid on both single crystals and thin films of Bi2Sr2CaCu2O8 + δ by Chatterjee et al. [Nature Phys. 6 (2010) 99], we perform a field-theoretical renormalization group (RG) analysis of a two-dimensional model such that only eight points located near the “hot spots” on the Fermi surface are retained, which are directly connected by spin density wave ordering wavevector. We derive RG equations up to two-loop order describing the flow of renormalized couplings, quasiparticle weight, several order-parameter response functions, and uniform spin and charge susceptibilities of the model. We find that while the order-parameter susceptibilities investigated here become non-divergent at two loops, the quasiparticle weight vanishes in the low-energy limit, indicating a breakdown of Fermi liquid behavior at this RG level. Moreover, both uniform spin and charge susceptibilities become suppressed in the scaling limit which indicate gap openings in both spin and charge excitation spectra of the model.

  18. Cooper pairing in non-Fermi liquids

    NASA Astrophysics Data System (ADS)

    Metlitski, Max A.; Mross, David F.; Sachdev, Subir; Senthil, T.

    2015-03-01

    States of matter with a sharp Fermi surface but no well-defined Landau quasiparticles arise in a number of physical systems. Examples include (i) quantum critical points associated with the onset of order in metals; (ii) spinon Fermi-surface [U(1) spin-liquid] state of a Mott insulator; (iii) Halperin-Lee-Read composite fermion charge liquid state of a half-filled Landau level. In this work, we use renormalization group techniques to investigate possible instabilities of such non-Fermi liquids in two spatial dimensions to Cooper pairing. We consider the Ising-nematic quantum critical point as an example of an ordering phase transition in a metal, and demonstrate that the attractive interaction mediated by the order-parameter fluctuations always leads to a superconducting instability. Moreover, in the regime where our calculation is controlled, superconductivity preempts the destruction of electronic quasiparticles. On the other hand, the spinon Fermi surface and the Halperin-Lee-Read states are stable against Cooper pairing for a sufficiently weak attractive short-range interaction; however, once the strength of attraction exceeds a critical value, pairing sets in. We describe the ensuing quantum phase transition between (i) U(1 ) and Z2 spin-liquid states; (ii) Halperin-Lee-Read and Moore-Read states.

  19. Charge-Doping-Driven Evolution of Magnetism and Non-Fermi-Liquid Behavior in the Filled Skutterudite CePt4Ge12-xSbx

    NASA Astrophysics Data System (ADS)

    Nicklas, M.; Kirchner, S.; Borth, R.; Gumeniuk, R.; Schnelle, W.; Rosner, H.; Borrmann, H.; Leithe-Jasper, A.; Grin, Yu.; Steglich, F.

    2012-12-01

    The filled skutterudite compound CePt4Ge12 is situated close to the border between the intermediate valence of Ce and heavy-fermion behavior. Substitution of Ge by Sb drives the system into a strongly correlated and, ultimately, upon further increasing the Sb concentration, an antiferromagnetically ordered state. Our experiments evidence a delicate interplay of emerging Kondo physics and the formation of a local 4f moment. An extended non-Fermi-liquid region, which can be understood in the framework of a Kondo-disorder model, is observed. Band-structure calculations support the conclusion that the physical properties are governed by the interplay of electron supply via Sb substitution and the concomitant volume effects.

  20. Quasi-two-dimensional spin-split Fermi-liquid behavior of {kappa}-(BEDT-TTF){sub 2}I{sub 3} in strong magnetic fields

    SciTech Connect

    Harrison, N.; Mielke, C.H.; Rickel, D.G.; Wosnitza, J.; Qualls, J.S.; Brooks, J.S.; Balthes, E.; Schweitzer, D.; Heinen, I.; Strunz, W.

    1998-10-01

    Measurements of both the magnetization and magnetotransport of {kappa}-(BEDT-TTF){sub 2}I{sub 3} (BEDT-TTF is bisethylenedithio-tetrathiafulvalene) in magnetic fields extending to 60 T at 0.4 K and 20 T at 35 mK are reported. Strong eddy currents observed in the magnetization are found to exhibit critical currentlike behavior. This might be connected with the breakdown of the quantum Hall effect, as proposed previously for {alpha}-phase salts. The strong two dimensionality leads to an apparent fall of the effective mass together with an overall suppression of the amplitude of the magnetic quantum oscillations at high magnetic fields or very low temperatures. These effects are more pronounced for the Shubnikov{endash}de Haas (SdH) effect but clearly visible also for the de Haas{endash}van Alphen (dHvA) oscillations. The apparent fall of the effective mass and the deviations of the dHvA signal from the behavior predicted by the standard Lifshitz-Kosevich theory can quantitatively be explained by the influence of chemical-potential oscillations on the wave form in a two-dimensional, spin-split Fermi liquid. The much stronger deviations from the conventional behavior in the transport data hint to an additional mechanism unique to the SdH effect. thinsp {copyright} {ital 1998} {ital The American Physical Society}

  1. Remarks on Fermi liquid from holography

    SciTech Connect

    Kulaxizi, Manuela; Parnachev, Andrei

    2008-10-15

    We investigate the signatures of Fermi liquid formation in the N=4 super Yang-Mills theory coupled to fundamental hypermultiplet at nonvanishing chemical potential for the global U(1) vector symmetry. At strong 't Hooft coupling the system can be analyzed in terms of the D7-brane dynamics in the AdS{sub 5}xS{sup 5} background. The phases with vanishing and finite charge density are separated at zero temperature by a quantum phase transition. In the case of vanishing hypermultiplet mass, Karch, Son, and Starinets discovered a gapless excitation whose speed equals the speed of sound. We find that this zero sound mode persists to all values of the hypermultiplet mass, and its speed vanishes at the point of phase transition. The value of critical exponent and the ratio of the velocities of zero and first sounds are consistent with the predictions of Landau Fermi liquid theory at strong coupling.

  2. Entanglement Entropy of Fermi Liquids via Multidimensional Bosonization

    NASA Astrophysics Data System (ADS)

    Ding, Wenxin; Seidel, Alexander; Yang, Kun

    2012-01-01

    The logarithmic violations of the area law, i.e., an “area law” with logarithmic correction of the form S˜Ld-1log⁡L, for entanglement entropy are found in both 1D gapless fermionic systems with Fermi points and high-dimensional free fermions. This paper shows that both violations are of the same origin, and that, in the presence of Fermi-liquid interactions, such behavior persists for 2D fermion systems. In this paper, we first consider the entanglement entropy of a toy model, namely, a set of decoupled 1D chains of free spinless fermions, to relate both violations in an intuitive way. We then use multidimensional bosonization to rederive the formula by Gioev and Klich [D. Gioev and I. Klich, Entanglement Entropy of Fermions in Any Dimension and the Widom Conjecture, Phys. Rev. Lett.PRLTAO0031-9007 96, 100503 (2006).10.1103/PhysRevLett.96.100503] for free fermions through a low-energy effective Hamiltonian and explicitly show that, in both cases, the logarithmic corrections to the area law share the same origin: the discontinuity at the Fermi surface (points). In the presence of Fermi-liquid (forward-scattering) interactions, the bosonized theory remains quadratic in terms of the original local degrees of freedom, and, after regularizing the theory with a mass term, we are able to calculate the entanglement entropy perturbatively up to second order in powers of the coupling parameter for a special geometry via the replica trick. We show that these interactions do not change the leading scaling behavior for the entanglement entropy of a Fermi liquid. At higher orders, we argue that this should remain true through a scaling analysis.

  3. Absence of thermalization in a Fermi liquid

    NASA Astrophysics Data System (ADS)

    Maraga, Anna; Silva, Alessandro; Fabrizio, Michele

    2014-10-01

    We study a weak interaction quench in a three-dimensional Fermi gas. We first show that, under some general assumptions on time-dependent perturbation theory, the perturbative expansion of the long-wavelength structure factor S (q ) is not compatible with the hypothesis that steady-state averages correspond to thermal ones. In particular, S (q ) does develop an analytical component ˜const +O (q2) at q →0 , as implied by thermalization, but, in contrast, it maintains a nonanalytic part ˜|q | characteristic of a Fermi liquid at zero-temperature. In real space, this nonanalyticity corresponds to persisting power-law decaying density-density correlations, whereas thermalization would predict only an exponential decay. We next consider the case of a dilute gas, where one can obtain nonperturbative results in the interaction strength but at lowest order in the density. We find that in the steady state the momentum distribution jump at the Fermi surface remains finite, though smaller than in equilibrium, up to second order in kFf0 , where f0 is the scattering length of two particles in the vacuum. Both results question the emergence of a finite length scale in the quench dynamics as expected by thermalization.

  4. Precursors of 1D behavior for D>1: evolution of the non-analytic correction to the Fermi-liquid behavior

    NASA Astrophysics Data System (ADS)

    Saha, Ronojoy; Maslov, Dmitrii

    2005-11-01

    The Fermi-liquid forms of the specific heat (C(T)) and static spin susceptibility (χs) acquire universal non-analytic corrections[1] and the degree of non-analyticity increase inversely with the dimensionality. This predicts that the strongest non-analyticity in the specific heat should be found in 1D; however, bosonization shows that the C(T) is analytic in 1D. We resolve this paradox by showing that the general argument, for non-analyticity in D>1 at the second order in the interaction, breaks down in 1D due to a subtle cancellation and the non-analytic TT term in the specific heat in 1D occurs at the third order for electrons with spin. We obtain the same result by considering the RG flow of the marginally irrelevant operator in the sine-Gordon theory. For spinless electrons, the non-analyticities in the particle-particle and particle-hole channels cancel out and the resulting C(T) is linear in T. The singularity in the particle-hole channel causes non-analyticity in the spin susceptibility χs|Q|,|H|,T present at the second order. [1] A.V. Chubukov and D.L. Maslov, Phys. Rev. B 68, 155113 (2003).

  5. Precursors of 1D behavior for D>1: evolution of the non-analytic correction to the Fermi-liquid behavior

    NASA Astrophysics Data System (ADS)

    Saha, Ronojoy

    2005-03-01

    The Fermi-liquid forms of the specific heat (C(T)) and static spin susceptibility (χs) acquire universal non-analytic corrections[1] and the degree of non-analyticity increase inversely with the dimensionality. This predicts that the strongest non-analyticity in the specific heat should be found in 1D, however bosonization shows that C(T) is linear in T in 1D. We resolve this paradox by showing that the general argument, for non-analyticity in D>1 at the second order in the interaction, breaks down in 1D due to a subtle cancellation and the non-analytic TT term in 1D occurs at the third order for electrons with spin. We obtain the same result by considering the RG flow of the marginally irrelevant operator in the sine-Gordon theory. For spinless electrons, the non-analyticities in the particle-particle and particle-hole channels cancel out and the resulting C(T) is linear in T. The singularity in the particle-hole channel causes non-analyticity in the spin susceptibility χs|Q|,|H|,T present at the second order[2]. [1]A.V. Chubukov and D.L. Maslov, Phys. Rev. B 68, 155113 (2003). [2]I.E. Dzyaloshinskii and A.I. Larkin, Sov. Phys. JETP 34, 422 (1972)

  6. Bosonization of the low energy excitations of Fermi liquids

    SciTech Connect

    Castro Neto, A.H.; Fradkin, E. )

    1994-03-07

    We bosonize the low energy excitations of Fermi liquids in any number of dimensions in the limit of long wavelengths. The bosons are a coherent superposition of electron-hole pairs and are related with the displacements of the Fermi surface in some arbitrary direction. A coherent-state path integral for the bosonized theory is derived and it is shown to represent histories of the shape of the Fermi surface. The Landau theory of Fermi liquids can be obtained from the formalism in the absence of nesting of the Fermi surface and singular interactions. We show that the Landau equation for sound waves is exact in the semiclassical approximation for the bosons.

  7. Observation of Fermi Polarons in a Tunable Fermi Liquid of Ultracold Atoms

    SciTech Connect

    Schirotzek, Andre; Wu, C.-H.; Sommer, Ariel; Zwierlein, Martin W.

    2009-06-12

    We have observed Fermi polarons, dressed spin-down impurities in a spin-up Fermi sea of ultracold atoms. The polaron manifests itself as a narrow peak in the impurities' rf spectrum that emerges from a broad incoherent background. We determine the polaron energy and the quasiparticle residue for various interaction strengths around a Feshbach resonance. At a critical interaction, we observe the transition from polaronic to molecular binding. Here, the imbalanced Fermi liquid undergoes a phase transition into a Bose liquid, coexisting with a Fermi sea.

  8. Orthogonal metals: The simplest non-Fermi liquids

    NASA Astrophysics Data System (ADS)

    Nandkishore, Rahul; Metlitski, Max A.; Senthil, T.

    2012-07-01

    We present a fractionalized metallic phase which is indistinguishable from the Fermi liquid in conductivity and thermodynamics, but is sharply distinct in one-electron properties, such as the electron spectral function. We dub this phase the “orthogonal metal.” The orthogonal metal and the transition to it from the Fermi liquid are naturally described using a slave-particle representation wherein the electron is expressed as a product of a fermion and a slave Ising spin. We emphasize that when the slave spins are disordered, the result is not a Mott insulator (as erroneously assumed in the prior literature), but rather the orthogonal metal. We construct prototypical ground-state wave functions for the orthogonal metal by modifying the Jastrow factor of Slater-Jastrow wave functions that describe ordinary Fermi liquids. We further demonstrate that the transition from the Fermi liquid to the orthogonal metal can, in some circumstances, provide a simple example of a continuous destruction of a Fermi surface with a critical Fermi surface appearing right at the critical point. We present exactly soluble models that realize an orthogonal metal phase, and the phase transition to the Fermi liquid. These models thus provide valuable solvable examples for phase transitions associated with the death of a Fermi surface.

  9. Spin waves in a persistent spin-current Fermi liquid

    SciTech Connect

    Feldmann, J. D.; Bedell, K. S.

    2010-06-15

    We report two theoretical results for transverse spin waves, which arise in a system with a persistent spin current. Using Fermi liquid theory, we introduce a spin current in the ground state of a polarized or unpolarized Fermi liquid, and we derive the resultant spin waves using the Landau kinetic equation. The resulting spin waves have a q{sup 1} and q{sup 1/2} dispersion to leading order for the polarized and unpolarized systems, respectively.

  10. Non-Fermi liquid phase in metallic Skyrmion crystals

    NASA Astrophysics Data System (ADS)

    Watanabe, Haruki; Parameswaran, Siddharth; Raghu, Srinivas; Vishwanath, Ashvin

    2014-03-01

    Motivated by reports of a non-Fermi liquid state in MnSi, we examine the effect of coupling phonons of an incommensurate skyrmion crystal (SkX) to conduction electrons. We find that non-Fermi liquid behavior emerges in both two and three dimensions over the entire phase, due to an anomalous electron-phonon coupling that is linked to the net skyrmion density. A small parameter, the spiral wave vector in lattice units, allows us to exercise analytic control and ignore Landau damping of phonons over a wide energy range. At the lowest energy scales the problem is similar to electrons coupled to a gauge field. The best prospects for realizing these effects is in short period skyrmion lattice systems such as MnGe or epitaxial MnSi films. We also compare our results with the unusual T 3 / 2 scaling of temperature dependent resistivity seen in high pressure experiments on MnSi. We acknowledge support from the NSF via Grant DMR-0645691, the DOE Office of Basic Energy Sciences via contract DE-AC02-76SF00515, and the Simons, Templeton, and Alfred P. Sloan Foundations.

  11. Fermi surface behavior in the ABJM M2-brane theory

    NASA Astrophysics Data System (ADS)

    DeWolfe, Oliver; Henriksson, Oscar; Rosen, Christopher

    2015-06-01

    We calculate fermionic Green's functions for states of the three-dimensional Aharony-Bergman-Jafferis-Maldacena M2-brane theory at large N using the gauge-gravity correspondence. We embed extremal black brane solutions in four-dimensional maximally supersymmetric gauged supergravity, obtain the linearized Dirac equations for each spin-1 /2 mode that cannot mix with a gravitino, and solve these equations with infalling boundary conditions to calculate retarded Green's functions. For generic values of the chemical potentials, we find Fermi surfaces with universally non-Fermi liquid behavior, matching the situation for four-dimensional N =4 super-Yang-Mills. Fermi surface singularities appear and disappear discontinuously at the point where all chemical potentials are equal, reminiscent of a quantum critical point. One limit of parameter space has zero entropy at zero temperature, and fermionic fluctuations are perfectly stable inside an energy region around the Fermi surface. An ambiguity in the quantization of the fermions is resolved by supersymmetry.

  12. Renormalization group study of a Fragile Fermi liquid in 1 + ɛ dimensions

    NASA Astrophysics Data System (ADS)

    Mai, Peizhi; Krishna-murthy, H. R.; Sriram Shastry, B.

    2016-07-01

    We present a calculation of the low energy Greens function of interacting fermions in 1 + ɛ dimensions using the method of extended poor man's scaling, developed here. We compute the wave function renormalization Z(ω) and also the decay rate near the Fermi energy. Despite the lack of ω2 damping characteristic of 3-dimensional Fermi liquids, we show that quasiparticles do exist in 1 + ɛ dimensions, in the sense that the quasiparticle weight Z is finite and that the damping rate is smaller than the energy. We explicitly compute the crossover from this behavior to a 1-dimensional type Tomonaga-Luttinger liquid behavior at higher energies.

  13. Hidden Fermi liquid, scattering rate saturation, and Nernst effect: a dynamical mean-field theory perspective.

    PubMed

    Xu, Wenhu; Haule, Kristjan; Kotliar, Gabriel

    2013-07-19

    We investigate the transport properties of a correlated metal within dynamical mean-field theory. Canonical Fermi liquid behavior emerges only below a very low temperature scale T(FL). Surprisingly the quasiparticle scattering rate follows a quadratic temperature dependence up to much higher temperatures and crosses over to saturated behavior around a temperature scale T(sat). We identify these quasiparticles as constituents of the hidden Fermi liquid. The non-Fermi-liquid transport above T(FL), in particular the linear-in-T resistivity, is shown to be a result of a strongly temperature dependent band dispersion. We derive simple expressions for the resistivity, Hall angle, thermoelectric power and Nernst coefficient in terms of a temperature dependent renormalized band structure and the quasiparticle scattering rate. We discuss possible tests of the dynamical mean-field theory picture of transport using ac measurements. PMID:23909344

  14. The spin diffusion in normal and superfluid Fermi liquids

    SciTech Connect

    Einzel, D. )

    1991-09-01

    Spin diffusion in paramagnetic spin systems is a dissipative process that acts so as to remove all spatial variation of the magnetization. In normal and superfluid Fermi liquids its physical origin lies in the nonconservation property of the macroscopic magnetization current associated with the thermal excitations, the Landau and Bogolyubov quasi-particles, respectively. In the hydrodynamic limit, this dissipative process manifests itself in a constitutive relation connecting the decaying magnetization current with gradients in the magnetization density via a coefficient of spin diffusion. Exchange contributions to the quasi-particle interaction introduce, in addition, reactive processes, which can be associated with a rotation of the quasi-particle spin current about the direction of the spin polarization. This so-called spin current rotation - or Leggett-Rice effect - leads to nonhydrodynamic behavior of the spin diffusion whenever the exchange frequency becomes comparable to the inverse spin-current relaxation time. This article reviews the current understanding of diffusional spin transport, as influenced by nonhydrodynamic effects, in normal and superfluid Fermi systems.

  15. Fermi-liquid theory for the single-impurity Anderson model

    NASA Astrophysics Data System (ADS)

    Mora, Christophe; Moca, Cǎtǎlin Paşcu; von Delft, Jan; Zaránd, Gergely

    2015-08-01

    We generalize Nozières' Fermi-liquid theory for the low-energy behavior of the Kondo model to that of the single-impurity Anderson model. In addition to the electrons' phase shift at the Fermi energy, the low-energy Fermi-liquid theory is characterized by four Fermi-liquid parameters: the two given by Nozières that enter to first order in the excitation energy, and two additional ones that enter to second order and are needed away from particle-hole symmetry. We express all four parameters in terms of zero-temperature physical observables, namely the local charge and spin susceptibilities and their derivatives with respect to the local level position. We determine these in terms of the bare parameters of the Anderson model using Bethe ansatz and numerical renormalization group (NRG) calculations. Our low-energy Fermi-liquid theory applies throughout the crossover from the strong-coupling Kondo regime via the mixed-valence regime to the empty-orbital regime. From the Fermi-liquid theory, we determine the conductance through a quantum dot symmetrically coupled to two leads in the regime of small magnetic field, low temperature, and small bias voltage, and compute the coefficients of the ˜B2 , ˜T2 , and ˜V2 terms exactly in terms of the Fermi-liquid parameters. The coefficients of T2, V2, and B2 are found to change sign during the Kondo to empty-orbital crossover. The crossover becomes universal in the limit that the local interaction is much larger than the level width. For completeness, we also compute the shot noise and discuss the resulting Fano factor.

  16. String theory, quantum phase transitions, and the emergent Fermi liquid.

    PubMed

    Cubrović, Mihailo; Zaanen, Jan; Schalm, Koenraad

    2009-07-24

    A central problem in quantum condensed matter physics is the critical theory governing the zero-temperature quantum phase transition between strongly renormalized Fermi liquids as found in heavy fermion intermetallics and possibly in high-critical temperature superconductors. We found that the mathematics of string theory is capable of describing such fermionic quantum critical states. Using the anti-de Sitter/conformal field theory correspondence to relate fermionic quantum critical fields to a gravitational problem, we computed the spectral functions of fermions in the field theory. By increasing the fermion density away from the relativistic quantum critical point, a state emerges with all the features of the Fermi liquid. PMID:19556462

  17. Quasiparticles and Fermi liquid behaviour in an organic metal

    PubMed Central

    Kiss, T.; Chainani, A.; Yamamoto, H.M.; Miyazaki, T.; Akimoto, T.; Shimojima, T.; Ishizaka, K.; Watanabe, S.; Chen, C.-T.; Fukaya, A.; Kato, R.; Shin, S.

    2012-01-01

    Many organic metals display exotic properties such as superconductivity, spin-charge separation and so on and have been described as quasi-one-dimensional Luttinger liquids. However, a genuine Fermi liquid behaviour with quasiparticles and Fermi surfaces have not been reported to date for any organic metal. Here, we report the experimental Fermi surface and band structure of an organic metal (BEDT-TTF)3Br(pBIB) obtained using angle-resolved photoelectron spectroscopy, and show its consistency with first-principles band structure calculations. Our results reveal a quasiparticle renormalization at low energy scales (effective mass m*=1.9 me) and ω2 dependence of the imaginary part of the self energy, limited by a kink at ~50 meV arising from coupling to molecular vibrations. The study unambiguously proves that (BEDT-TTF)3Br(pBIB) is a quasi-2D organic Fermi liquid with a Fermi surface consistent with Shubnikov-de Haas results. PMID:23011143

  18. Fermi Liquid Instabilities in the Spin Channel

    SciTech Connect

    Wu, Congjun; Sun, Kai; Fradkin, Eduardo; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-03-16

    We study the Fermi surface instabilities of the Pomeranchuk type in the spin triplet channel with high orbital partial waves (F{sub l}{sup a} (l > 0)). The ordered phases are classified into two classes, dubbed the {alpha} and {beta}-phases by analogy to the superfluid {sup 3}He-A and B-phases. The Fermi surfaces in the {alpha}-phases exhibit spontaneous anisotropic distortions, while those in the {beta}-phases remain circular or spherical with topologically non-trivial spin configurations in momentum space. In the {alpha}-phase, the Goldstone modes in the density channel exhibit anisotropic overdamping. The Goldstone modes in the spin channel have nearly isotropic underdamped dispersion relation at small propagating wavevectors. Due to the coupling to the Goldstone modes, the spin wave spectrum develops resonance peaks in both the {alpha} and {beta}-phases, which can be detected in inelastic neutron scattering experiments. In the p-wave channel {beta}-phase, a chiral ground state inhomogeneity is spontaneously generated due to a Lifshitz-like instability in the originally nonchiral systems. Possible experiments to detect these phases are discussed.

  19. Non-Fermi liquids in two and three-dimensional doped SrTiO3

    NASA Astrophysics Data System (ADS)

    Mikheev, Evgeny; Raghavan, Santosh; Zhang, Jack; Marshall, Patrick; Kajdos, Adam; Balents, Leon; Stemmer, Susanne

    A remarkable feature of transport in doped SrTiO3 is the temperature dependence of the electrical resistivity that is proportional to Tn with n <= 2. This power law suggests electron-electron scattering is the dominant scattering mechanism. It extends to room temperature and above in both three-dimensional, uniformly doped SrTiO3 and in two-dimensional electron liquids (2DELs) at oxide interfaces. In case of n = 2, the behavior is traditionally identified as that of a Landau Fermi liquid. Here we argue that Landau Fermi liquid theory does not apply to the electron liquid in SrTiO3, even when n = 2. Using electrostatic gating and chemical doping, we demonstrate that this regime is associated with a scattering rate and an energy scale that are independent of carrier density. This is in fundamental conflict with the premise of the Fermi liquid theory, where this energy scale is the Fermi energy. This work raises important questions in terms of microscopic scattering mechanism. It appears to be relevant for understanding of transport in many other strongly correlated systems, which also show very robust Tn regimes with carrier density independent scattering rates.

  20. Optical spectroscopy shows that the normal state of URu2Si2 is an anomalous Fermi liquid

    PubMed Central

    Nagel, Urmas; Uleksin, Taaniel; Rõõm, Toomas; Lobo, Ricardo P. S. M.; Lejay, Pascal; Homes, Christopher C.; Hall, Jesse S.; Kinross, Alison W.; Purdy, Sarah K.; Munsie, Tim; Williams, Travis J.; Luke, Graeme M.; Timusk, Thomas

    2012-01-01

    Fermi showed that, as a result of their quantum nature, electrons form a gas of particles whose temperature and density follow the so-called Fermi distribution. As shown by Landau, in a metal the electrons continue to act like free quantum mechanical particles with enhanced masses, despite their strong Coulomb interaction with each other and the positive background ions. This state of matter, the Landau–Fermi liquid, is recognized experimentally by an electrical resistivity that is proportional to the square of the absolute temperature plus a term proportional to the square of the frequency of the applied field. Calculations show that, if electron-electron scattering dominates the resistivity in a Landau–Fermi liquid, the ratio of the two terms, b, has the universal value of b = 4. We find that in the normal state of the heavy Fermion metal URu2Si2, instead of the Fermi liquid value of 4, the coefficient b = 1 ± 0.1. This unexpected result implies that the electrons in this material are experiencing a unique scattering process. This scattering is intrinsic and we suggest that the uranium f electrons do not hybridize to form a coherent Fermi liquid but instead act like a dense array of elastic impurities, interacting incoherently with the charge carriers. This behavior is not restricted to URu2Si2. Fermi liquid-like states with b ≠ 4 have been observed in a number of disparate systems, but the significance of this result has not been recognized. PMID:23115333

  1. Singular corrections to the Fermi-liquid theory

    NASA Astrophysics Data System (ADS)

    Chubukov, Andrey V.; Maslov, Dmitrii L.

    2004-03-01

    We show that the singularities in the dynamical bosonic response functions of a two-dimensional Fermi liquid give rise to universal nonanalytic corrections to the results of the Fermi-liquid theory. In particular, we find a T2 term in the specific heat, linear-in-T terms in the effective mass and in the uniform spin susceptibility χs(Q=0,T), and |Q| term in χs(Q,T=0). The existence of these terms has been the subject of recent controversy, which is resolved in this paper. We present exact expressions for all nonanalytic terms to second order in a generic interaction U(Q) and show that the nonanalytic terms originate exclusively from forward- and backward-scattering of particles with zero total momentum.

  2. Roles of zeros of the Green function in Fermi arc and non-Fermi liquid in the two-dimensional Hubbard model

    NASA Astrophysics Data System (ADS)

    Sakai, Shiro; Motome, Yukitoshi; Imada, Masatoshi

    2009-10-01

    We clarify effects of zeros of the Green function on a Fermi arc and on a non-Fermi liquid behavior in the two-dimensional Hubbard model by means of the cellular dynamical mean-field theory (CDMFT). We study in detail the state with a hole-pocket Fermi surface and zeros of the Green function, which was found for a slightly doped Mott insulator in an earlier CDMFT calculation [T.D. Stanescu, G. Kotliar, Phys. Rev. B 74 (2006) 125110; T.D. Stanescu, M. Civelli, K. Haule, G. Kotliar, Ann. Phys. (N.Y.) 321 (2006) 1682]. As thermal or other extrinsic scatterings of electrons broaden the zeros, regions around the zero surface gain an imaginary part of the self-energy, which strongly suppresses the spectral intensity, especially on the closer side of the hole pocket to the zero surface. Then the rest emerges as a Fermi arc. Quasiparticle weight becomes ill defined on the closer side of the Fermi pocket while it is well defined on the opposite side, which means that a differentiation of electrons occurs in the momentum space, indicating an emergence of a non-Fermi liquid phase.

  3. Towards a Holographic Marginal Fermi Liquid

    SciTech Connect

    Jensen, Kristan; Kachru, Shamit; Karch, Andreas; Polchinski, Joseph; Silverstein, Eva

    2011-08-15

    We present an infinite class of 2+1 dimensional field theories which, after coupling to semi-holographic fermions, exhibit strange metallic behavior in a suitable large N limit. These theories describe lattices of hypermultiplet defects interacting with parity-preserving supersymmetric Chern-Simons theories with U(N) x U(N) gauge groups at levels {+-}k. They have dual gravitational descriptions in terms of lattices of probe M2 branes in AdS{sub 4} x S{sup 7}/Z{sub k} (for N >> 1,N >> k{sup 5}) or probe D2 branes in AdS{sub 4} x CP{sup 3} (for N >> k >> 1,N << k{sup 5}). We discuss several challenges one faces in maintaining the success of these models at finite N, including backreaction of the probes in the gravity solutions and radiative corrections in the weakly coupled field theory limit.

  4. Fermi-liquid theory of ultracold trapped Fermi gases: Implications for pseudogap physics and other strongly correlated phases

    SciTech Connect

    Chien, Chih-Chun; Levin, K.

    2010-07-15

    We show how Fermi-liquid theory can be applied to ultracold Fermi gases, thereby expanding their ''simulation'' capabilities to a class of problems of interest to multiple physics subdisciplines. We introduce procedures for measuring and calculating position-dependent Landau parameters. This lays the groundwork for addressing important controversial issues: (i) the suggestion that thermodynamically, the normal state of a unitary gas is indistinguishable from a Fermi liquid and (ii) that a fermionic system with strong repulsive contact interactions is associated with either ferromagnetism or localization; this relates as well to {sup 3}He and its p-wave superfluidity.

  5. Stable non-Fermi-liquid phase of itinerant spin-orbit coupled ferromagnets

    NASA Astrophysics Data System (ADS)

    Bahri, Yasaman; Potter, Andrew C.

    2015-07-01

    Direct (nongradient) coupling between a gapless bosonic field and a Fermi surface results in the destruction of Landau quasiparticles and a breakdown of Fermi liquid theory. Such a non-Fermi-liquid phase arises in spin-orbit coupled ferromagnets with spontaneously broken continuous symmetries due to strong coupling between rotational Goldstone modes and itinerant electrons. These systems provide an experimentally accessible context for studying non-Fermi-liquid physics. Possible examples include low-density Rashba coupled electron gases, which have a natural tendency towards spontaneous ferromagnetism, or topological insulator surface states with proximity-induced ferromagnetism. Crucially, unlike the related case of a spontaneous nematic distortion of the Fermi surface, for which controlled field theory calculations predict that the non-Fermi-liquid regime will be masked by a superconducting dome, we show that the non-Fermi-liquid phase in spin-orbit coupled ferromagnets is stable.

  6. Stable non-Fermi liquid phase of itinerant spin-orbit coupled ferromagnets

    NASA Astrophysics Data System (ADS)

    Bahri, Yasaman; Potter, Andrew

    2015-03-01

    Direct coupling between gapless bosons and a Fermi surface results in the destruction of Landau quasiparticles and a breakdown of Fermi liquid theory. Such a non-Fermi liquid phase arises in spin-orbit coupled ferromagnets with spontaneously broken continuous symmetries due to strong coupling between rotational Goldstone modes and itinerant electrons. These systems provide an experimentally accessible context for studying non-Fermi liquid physics. Possible examples include low-density Rashba coupled electron gases, which have a natural tendency towards spontaneous ferromagnetism, or topological insulator surface states with proximity-induced ferromagnetism. Crucially, unlike the related case of a spontaneous nematic distortion of the Fermi surface, for which the non-Fermi liquid regime is expected to be masked by a superconducting dome, we show that the non-Fermi liquid phase in spin-orbit coupled ferromagnets is stable.

  7. Momentum-resolved spectroscopy of a Fermi liquid.

    PubMed

    Doggen, Elmer V H; Kinnunen, Jami J

    2015-01-01

    We consider a recent momentum-resolved radio-frequency spectroscopy experiment, in which Fermi liquid properties of a strongly interacting atomic Fermi gas were studied. Here we show that by extending the Brueckner-Goldstone model, we can formulate a theory that goes beyond basic mean-field theories and that can be used for studying spectroscopies of dilute atomic gases in the strongly interacting regime. The model hosts well-defined quasiparticles and works across a wide range of temperatures and interaction strengths. The theory provides excellent qualitative agreement with the experiment. Comparing the predictions of the present theory with the mean-field Bardeen-Cooper-Schrieffer theory yields insights into the role of pair correlations, Tan's contact, and the Hartree mean-field energy shift. PMID:25941948

  8. Holographic non-Fermi liquid in a background magnetic field

    NASA Astrophysics Data System (ADS)

    Basu, Pallab; He, Jianyang; Mukherjee, Anindya; Shieh, Hsien-Hang

    2010-08-01

    We study the effects of a nonzero magnetic field on a class of 2+1 dimensional non-Fermi liquids, recently found in [Hong Liu, John McGreevy, and David Vegh, arXiv:0903.2477.] by considering properties of a Fermionic probe in an extremal AdS4 black hole background. Introducing a similar fermionic probe in a dyonic AdS4 black hole geometry, we find that the effect of a magnetic field could be incorporated in a rescaling of the probe fermion’s charge. From this simple fact, we observe interesting effects like gradual disappearance of the Fermi surface and quasiparticle peaks at large magnetic fields and changes in other properties of the system. We also find Landau level like structures and oscillatory phenomena similar to the de-Haas-van Alphen effect.

  9. Incoherence-coherence crossover and low-temperature Fermi-liquid-like behavior in AFe2As2 (A  =  K, Rb, Cs): evidence from electrical transport properties.

    PubMed

    Xiang, Z J; Wang, N Z; Wang, A F; Zhao, D; Sun, Z L; Luo, X G; Wu, T; Chen, X H

    2016-10-26

    We study the normal-state transport properties of AFe2As2 (A  =  K, Rb and Cs) single crystals using Hall coefficient, resistivity and magnetoresistance (MR) measurements. In all three materials, the Hall coefficient R H shows a strong temperature dependence, which is typical for multi-band systems. In particular, R H develops an upturn below a characteristic temperature [Formula: see text], which is in agreement with the incoherence-coherence crossover reported in recent nuclear magnetic resonance studies. A Fermi-liquid-like state, characterized by T (2) behavior of the resistivity and a positive orbital MR obeying Kohler's rule, emerges below T FL  ∼0.4 [Formula: see text]. The superconducting transition temperature T c experiences a simultaneous suppression with [Formula: see text] and T FL as the alkali ion's radius increases from A  =  K to A  =  Cs, suggesting that the unconventional superconductivity in the AFe2As2 series is related to the strength of the electronic coherence. A phase diagram, similar to that in the heavy fermion Kondo lattice system, is obtained. Based on all the experimental evidence, we argue that the physical properties of this family of heavily hole-doped Fe-based superconductors are controlled by the hybridization between itinerant carriers and localized orbitals, and the Kondo scenario could be effective in such a case. PMID:27589485

  10. Anomalous Local Fermi Liquid in f2-Singlet Configuration: Impurity Model for Heavy-Electron System UPt3

    NASA Astrophysics Data System (ADS)

    Yotsuhashi, Satoshi; Miyake, Kazumasa; Kusunose, Hiroaki

    2016-03-01

    It is shown by the Wilson numerical renormalization group method that a strongly correlated impurity with a crystalline-electric-field singlet ground state in the f2-configuration exhibits an anomalous local Fermi liquid state in which the static magnetic susceptibility remains an uncorrelated value while the NMR relaxation rate is enhanced in proportion to the square of the mass enhancement factor. Namely, the Korringa-Shiba relation is apparently broken. This feature closely matches the anomalous behaviors observed in UPt3, i.e., the coexistence of an unenhanced value of the Knight shift due to quasiparticles contribution (the decrease across the superconducting transition) and the enhanced relaxation rate of NMR. Such an anomalous Fermi liquid behavior suggests that the Fermi liquid corrections for the susceptibility are highly anisotropic.

  11. {sup 11}B NMR in YbNi{sub 2}B{sub 2}C single crystals: Crossover from localized moments to Fermi-liquid behavior

    SciTech Connect

    Sala, R.; Borsa, F.; Lee, E.; Canfield, P.C.

    1997-09-01

    Data of {sup 11}B NMR in a single crystal of YbNi{sub 2}B{sub 2}C are reported in the temperature range 1.7{endash}300 K and for two orientations of the external magnetic field with respect to the tetragonal c axis of the crystal. For T{gt}50K both the Knight shift K and the nuclear spin-lattice relaxation rate T{sub 1}{sup {minus}1} can be accounted for by the presence of localized 4f moments at the Yb{sup 3+} site which polarize the conduction electrons via the Ruderman-Kittel-Kasuya-Yosida mechanism. On the other hand, at low temperatures, T{lt}5K, the relaxation rate T{sub 1}{sup {minus}1} obeys a Korringa-like law with a constant value of T{sub 1}T typical of a normal metal with high density of states at the Fermi level and no localized moments. {copyright} {ital 1997} {ital The American Physical Society}

  12. Two-component Fermi-liquid theory - Equilibrium properties of liquid metallic hydrogen

    NASA Technical Reports Server (NTRS)

    Oliva, J.; Ashcroft, N. W.

    1981-01-01

    It is reported that the transition of condensed hydrogen from an insulating molecular crystal phase to a metallic liquid phase, at zero temperature and high pressure, appears possible. Liquid metallic hydrogen (LMH), comprising interpenetrating proton and electron fluids, would constitute a two-component Fermi liquid with both a very high component-mass ratio and long-range, species-dependent bare interactions. The low-temperature equilibrium properties of LMH are examined by means of a generalization to the case of two components of the phenomenological Landau Fermi-liquid theory, and the low-temperature specific heat, compressibility, thermal expansion coefficient and spin susceptibility are given. It is found that the specific heat and the thermal expansion coefficient are vastly greater in the liquid than in the corresponding solid, due to the presence of proton quasiparticle excitations in the liquid.

  13. Spectral function and kinetic equation for a normal Fermi liquid

    SciTech Connect

    Arshad, M.; Siddique, I.; Kondratyev, A. S.

    2007-08-01

    On the basis of the Kadanoff-Baym (KB) version of the time-dependent Green's function method, an Ansatz for the approximation of a spectral function is offered. The Ansatz possesses all the advantages of quasiparticle and extended quasiparticle approximations and satisfies the KB equation for a spectral function in the case of slightly nonequilibrium system when disturbances in space and time are taken into consideration in the gradient approximation. This feature opens opportunities for the microscopic derivation of the Landau kinetic equation for the quasiparticle distribution function of the normal Fermi liquid and provides the widening of these equations' temperature range of validity.

  14. Spin response of a normal Fermi liquid with noncentral interactions

    SciTech Connect

    Pethick, C. J.; Schwenk, A.

    2009-11-15

    We consider the spin response of a normal Fermi liquid with noncentral interactions under conditions intermediate between the collisionless and hydrodynamic regimes. This problem is of importance for calculations of neutrino properties in dense matter. By expressing the deviation of the quasiparticle distribution function from equilibrium in terms of eigenfunctions of the transport equation under the combined influence of collisions and an external field, we derive a closed expression for the spin-density-spin-density response function and compare its predictions with that of a relaxation-time approximation. Our results indicate that the relaxation-time approximation is reliable for neutrino properties under astrophysically relevant conditions.

  15. The 2d MIT: The Pseudogap and Fermi Liquid Theory

    NASA Astrophysics Data System (ADS)

    Castner, T. G.

    2005-06-01

    Fermi liquid theory for the 2d metal-insulator transition is extended to include the correlation gap in the density-of-states. The results are consistent with the scaling form g=gce[on(To/T)] at T larger than a characteristic T* ∝ xTc (Tc=Ec= mobility edge). The two-component model n1+nloc=n=nc(1+x) for n>nc is required and the theory explains the T-dependence of the data of Hanein et al. for p-type GaAs.

  16. Kaon condensation in baryonic Fermi liquid at high density

    NASA Astrophysics Data System (ADS)

    Paeng, Won-Gi; Rho, Mannque

    2015-01-01

    We formulate kaon condensation in dense baryonic matter with antikaons fluctuating from the Fermi-liquid fixed point. This entails that in the Wilsonian renormalization group (RG) approach, the decimation is effectuated in the baryonic sector to the Fermi surface while in the meson sector to the origin. In writing the kaon-baryon (KN) coupling, we take a generalized hidden local symmetry Lagrangian for the meson sector endowed with a "mended symmetry" that has the unbroken symmetry limit at high density in which the Goldstone π , scalar s , and vectors ρ (and ω ) and a1 become massless. The vector mesons ρ (and ω ) and a1 can be identified as emergent (hidden) local gauge fields and the scalar s as the dilaton field of the spontaneously broken scale invariance at chiral restoration. In matter-free space, when the vector mesons and the scalar meson—whose masses are much greater than that of the pion—are integrated out, then the resulting KN coupling Lagrangian consists of the leading chiral order [O (p1) ] Weinberg-Tomozawa term and the next chiral order [O (p2) ] ΣKN term. In addressing kaon condensation in dense nuclear matter in chiral perturbation theory, one makes an expansion in the "small" Fermi momentum kF. We argue that in the Wilsonian RG formalism with the Fermi-liquid fixed point, the expansion is on the contrary in 1 /kF with the "large" Fermi momentum kF. The kaon-quasinucleon interaction resulting from integrating out the massive mesons consists of a "relevant" term from the scalar exchange (analog to the ΣKN term) and an "irrelevant" term from the vector-meson exchange (analog to the Weinberg-Tomozawa term). It is found that the critical density predicted by the latter approach, controlled by the relevant term with the irrelevant term suppressed, is three times less than that predicted by chiral perturbation theory. This would make kaon condensation take place at a much lower density than previously estimated in chiral perturbation theory.

  17. Quantum magneto-oscillations in a two-dimensional Fermi liquid

    NASA Astrophysics Data System (ADS)

    Martin, Gregory W.; Maslov, Dmitrii L.; Reizer, Michael Yu.

    2003-12-01

    Quantum magneto-oscillations provide a powerful tool for quantifying Fermi-liquid parameters of metals. In particular, the quasiparticle effective mass and spin susceptibility are extracted from the experiment using the Lifshitz-Kosevich formula, derived under the assumption that the properties of the system in a nonzero magnetic field are determined uniquely by the zero-field Fermi-liquid state. This assumption is valid in three dimensions (3D) but, generally speaking, erroneous in 2D where the Lifshitz-Kosevich formula may be applied only if the oscillations are strongly damped by thermal smearing and disorder. In this work, the effects of interactions and disorder on the amplitude of magneto-oscillations in 2D are studied. It is found that the effective mass diverges logarithmically with decreasing temperature signaling a deviation from the Fermi-liquid behavior. It is also shown that the quasiparticle lifetime due to inelastic interactions does not enter the oscillation amplitude, although these interactions do renormalize the effective mass. This result provides a generalization of the Fowler-Prange theorem formulated originally for the electron-phonon interaction.

  18. Emergent non-Fermi liquid in the pseudogap phase of the underdoped cuprates

    NASA Astrophysics Data System (ADS)

    Das, Tanmoy; Markiewicz, R. S.; Bansil, A.

    2010-03-01

    As the cuprates approach the Mott insulator limit, they display a remarkable gossamer-like structure: the near-Fermi level dispersion remains nearly unrenormalized while the corresponding spectral weight tends to vanish at half filling[1]. This unusual behavior cannot be understood by conventional Fermi liquid theory where both features are controlled by a single renormalization factor. We find that while the fluctuation spectrum remains nearly isotropic in cuprates, the competing order pseudogap (here modelled as antiferromagnetism) breaks the crystal symmetry and thus promotes a strong momentum dependence in the self-energy term[2]. At half-filling, this yields an essentially unrenormalized quasiparticle dispersion which approaches the uncorrelated limit, while in sharp contrast the quasiparticle spectral weight renormalizes to zero. These opposing tendencies of dispersion and spectral weight renormalization conspire in such a way that the specific heat remains Fermi liquid like in character at all dopings in accord with experiments. Work supported in part by the USDOE. [1] S. Sahrakorpi, et al., Phys. Rev. B 78, 104513 (2008). [2] T. Das, et al., arXiv:0807.4257.

  19. Experimental Evidence of Fermi-Luttinger Liquid State.

    NASA Astrophysics Data System (ADS)

    Debray, Philippe; Muhammad, Mustafa; Herbert, Steven; Newrock, Richard

    2008-03-01

    We have measured Coulomb drag between spatially separated parallel quantum wires, made on AlGaAs/GaAs heterostructures by the split-gate technique, in the absence of tunneling to experimentally probe drag by small forward momentum transfer. Drag between wires of lengths 500 and 300 nm was measured in the one-dimensional transport regime at temperatures in the range 30 mK -- 1.2 K. We have observed both positive and negative drag. The temperature dependence of drag of both types is in excellent agreement with that predicted by the recently proposed Fermi-Luttinger liquid (FLL) theory that takes into account the curvature in the fermionic dispersion. Positive drag occurs when the curvature is positive, while negative drag occurs when it is negative.

  20. Interface Superconductivity in Cuprates Defies Fermi-Liquid Description

    DOE PAGESBeta

    Radović, Zoran; Vanević, Mihajlo; Wu, Jie; Bollinger, Anthony T.; Božović, Ivan

    2016-07-26

    La2-xSrxCuO4/La2CuO4 bilayers show interface superconductivity that originates from accumulation and depletion of mobile charge carriers across the interface. Surprisingly, the doping level can be varied broadly (within the interval 0.15 < x < 0.47) without affecting the transition temperature, which stays essentially constant and equal to that in optimally doped material, Tc ≈ 40 K. Here we argue that this finding implies that doping up to the optimum level does not shift the chemical potential, unlike in ordinary Fermi liquids. Lastly, we discuss possible physical scenarios that can give doping-independent chemical potential in the pseudogap regime: electronic phase separation, formationmore » of charge-density waves, strong Coulomb interactions, or self-trapping of mobile charge carriers.« less

  1. Un-Fermi liquids: Unparticles in strongly correlated electron matter

    NASA Astrophysics Data System (ADS)

    Phillips, Philip W.; Langley, Brandon W.; Hutasoit, Jimmy A.

    2013-09-01

    Since any nontrivial infrared dynamics in strongly correlated electron matter must be controlled by a critical fixed point, we argue that the form of the single-particle propagator can be deduced simply by imposing scale invariance. As a consequence, the unparticle picture proposed by Georgi is the natural candidate to describe such dynamics. Unparticle stuff is scale-invariant matter with no particular mass. Scale invariance dictates that the propagator has an algebraic form which can admit zeros and hence is a candidate to explain the ubiquitous pseudogap state of the cuprates. We refer to the nonperturbative electronic state formed out of unparticles as an un-Fermi liquid. We show that the underlying action of the continuous mass formulation of unparticles can be recast as an action in anti-de Sitter space which serves as the generating functional for the propagator. We find that this mapping fixes the scaling dimension of the unparticle to be dU=d/2+d2+4/2 and ensures that the corresponding propagator has zeros with d the space-time dimension of the unparticle field. Should d=2+1, unparticles acquire the nontrivial phase 2πdU upon interchange. Because dU is noninteger and in general not half integer, clockwise and counterclockwise interchange of unparticles do not lead to the same phase and time-reversal symmetry is broken spontaneously as reported in numerous experiments in the pseudogap phase of the cuprates. The possible relevance of this mechanism to such experiments is discussed. We then formulate the analogous BCS gap using unparticles and find that in contrast to the Fermi-liquid case, the transition temperature increases as the attractive interaction strength decreases, indicating that unparticles are highly susceptible to a superconducting instability.

  2. Emergent Non-Fermi-Liquid at the Quantum Critical Point of a Topological Phase Transition in Two Dimensions

    NASA Astrophysics Data System (ADS)

    Isobe, Hiroki; Yang, Bohm-Jung; Chubukov, Andrey; Schmalian, Jörg; Nagaosa, Naoto

    2016-02-01

    We study the effects of Coulomb interaction between 2D Weyl fermions with anisotropic dispersion which displays relativistic dynamics along one direction and nonrelativistic dynamics along the other. Such a dispersion can be realized in phosphorene under electric field or strain, in TiO2 /VO2 superlattices, and, more generally, at the quantum critical point between a nodal semimetal and an insulator in systems with a chiral symmetry. Using the one-loop renormalization group approach in combination with the large-N expansion, we find that the system displays interaction-driven non-Fermi liquid behavior in a wide range of intermediate frequencies and marginal Fermi liquid behavior at the smallest frequencies. In the non-Fermi liquid regime, the quasiparticle residue Z at energy E scales as Z ∝Ea with a >0 , and the parameters of the fermionic dispersion acquire anomalous dimensions. In the marginal Fermi-liquid regime, Z ∝(|log E |)-b with universal b =3 /2 .

  3. Emergent Non-Fermi-Liquid at the Quantum Critical Point of a Topological Phase Transition in Two Dimensions.

    PubMed

    Isobe, Hiroki; Yang, Bohm-Jung; Chubukov, Andrey; Schmalian, Jörg; Nagaosa, Naoto

    2016-02-19

    We study the effects of Coulomb interaction between 2D Weyl fermions with anisotropic dispersion which displays relativistic dynamics along one direction and nonrelativistic dynamics along the other. Such a dispersion can be realized in phosphorene under electric field or strain, in TiO_{2}/VO_{2} superlattices, and, more generally, at the quantum critical point between a nodal semimetal and an insulator in systems with a chiral symmetry. Using the one-loop renormalization group approach in combination with the large-N expansion, we find that the system displays interaction-driven non-Fermi liquid behavior in a wide range of intermediate frequencies and marginal Fermi liquid behavior at the smallest frequencies. In the non-Fermi liquid regime, the quasiparticle residue Z at energy E scales as Z∝E^{a} with a>0, and the parameters of the fermionic dispersion acquire anomalous dimensions. In the marginal Fermi-liquid regime, Z∝(|logE|)^{-b} with universal b=3/2. PMID:26943551

  4. Un-Fermi Liquids: Unparticles in Strongly Correlated Electron Matter

    NASA Astrophysics Data System (ADS)

    Langley, Brandon; Phillips, Philip; Hutasoit, Jimmy

    2014-03-01

    Since any non-trivial infrared dynamics in strongly correlated electron matter must be controlled by a critical fixed point, we argue that the form of the single-particle propagator can be deduced simply by imposing scale invariance. As a consequence, the unparticle picture proposed by Georgi is the natural candidate to describe such dynamics. Unparticle stuff is scale-invariant matter with no particular mass. Scale invariance dictates that the propagator has an algebraic form which can admit zeros and hence is a candidate to explain the ubiquitous pseudogap state of the cuprates. The non-perturbative electronic state formed out of unparticles we refer to as an un-Fermi liquid. We show that the underlying action of the continuous mass formulation of unparticles can be recast as an action in anti de Sitter space which serves as the generating functional for the propagator. We find that this mapping fixes the scaling dimension of the unparticle to be dU = d / 2 +√{d2 + 4 } / 2 and ensures that the corresponding propagator has zeros with d the spacetime dimension of the unparticle field. This work was funded by NSF DMR-1104909, DMR-1005536 and DMR-0820404.

  5. Isoscalar Giant Dipole Resonance within Fermi Liquid Drop Model

    NASA Astrophysics Data System (ADS)

    Pochivalov, Oleksiy; Shlomo, Shalom

    2006-04-01

    Recent highly accurate experimental data on Isoscalar Giant Dipole (ISGDR) and Monopole (ISGMR) Resonances in nuclei renewed interest in correct microscopic description of collective excitations. Hartree-Fock based Random-Phase-Approximation (HF-RPA) is a successful method of describing collective excitations in nuclei. However, recent fully self-consistent HF-RPA calculations, which reproduce the centroid energies of the ISGMR, systematically overestimate by 1.5-2.5 MeV results for the ISGDR energy comparing with experimentally obtained data. Also, the HF-RPA model does not provide description of the widths of giant resonances. We consider these issues within the semi-classical generalization of the mean field theory, namely, Fermi-Liquid-Drop-Model (FLDM). In this presentation, we provide description of the FLDM formalism in its application to ISGDR and ISGMR calculations. We present results of FLDM calculations for centroid energy and widths of the ISGDR and ISGMR in the four nuclei, namely, 90Zr, 116Sn, 144Sm, and 208Pb and compare with available experimental data.

  6. Quasiparticles of strongly correlated Fermi liquids at high temperatures and in high magnetic fields

    SciTech Connect

    Shaginyan, V. R.

    2011-08-15

    Strongly correlated Fermi systems are among the most intriguing, best experimentally studied and fundamental systems in physics. There is, however, lack of theoretical understanding in this field of physics. The ideas based on the concepts like Kondo lattice and involving quantum and thermal fluctuations at a quantum critical point have been used to explain the unusual physics. Alas, being suggested to describe one property, these approaches fail to explain the others. This means a real crisis in theory suggesting that there is a hidden fundamental law of nature. It turns out that the hidden fundamental law is well forgotten old one directly related to the Landau-Migdal quasiparticles, while the basic properties and the scaling behavior of the strongly correlated systems can be described within the framework of the fermion condensation quantum phase transition (FCQPT). The phase transition comprises the extended quasiparticle paradigm that allows us to explain the non-Fermi liquid (NFL) behavior observed in these systems. In contrast to the Landau paradigm stating that the quasiparticle effective mass is a constant, the effective mass of new quasiparticles strongly depends on temperature, magnetic field, pressure, and other parameters. Our observations are in good agreement with experimental facts and show that FCQPT is responsible for the observed NFL behavior and quasiparticles survive both high temperatures and high magnetic fields.

  7. Non-Fermi-liquid magic angle effects in high magnetic fields

    NASA Astrophysics Data System (ADS)

    Lebed, A. G.

    2016-07-01

    We investigate a theoretical problem of electron-electron interactions in an inclined magnetic field in a quasi-one-dimensional (Q1D) conductor. We show that they result in strong non-Fermi-liquid corrections to a specific heat, provided that the direction of the magnetic field is far from the so-called Lebed's magic angles (LMAs). If magnetic field is directed close to one of the LMAs, the specific heat corrections become small and the Fermi-liquid picture restores. As a result, we predict Fermi-liquid-non-Fermi-liquid angular crossovers in the vicinities of the LMA directions of the field. We suggest to perform the corresponding experiment in the Q1D conductor (Per) 2Au (mnt) 2 under pressure in magnetic fields of the order of H ≃25 T .

  8. Extremely correlated Fermi liquids in the limit of infinite dimensions

    SciTech Connect

    Perepelitsky, Edward Sriram Shastry, B.

    2013-11-15

    We study the infinite spatial dimensionality limit (d→∞) of the recently developed Extremely Correlated Fermi Liquid (ECFL) theory (Shastry 2011, 2013) [17,18] for the t–J model at J=0. We directly analyze the Schwinger equations of motion for the Gutzwiller projected (i.e. U=∞) electron Green’s function G. From simplifications arising in this limit d→∞, we are able to make several exact statements about the theory. The ECFL Green’s function is shown to have a momentum independent Dyson (Mori) self energy. For practical calculations we introduce a partial projection parameter λ, and obtain the complete set of ECFL integral equations to O(λ{sup 2}). In a related publication (Zitko et al. 2013) [23], these equations are compared in detail with the dynamical mean field theory for the large U Hubbard model. Paralleling the well known mapping for the Hubbard model, we find that the infinite dimensional t–J model (with J=0) can be mapped to the infinite-U Anderson impurity model with a self-consistently determined set of parameters. This mapping extends individually to the auxiliary Green’s function g and the caparison factor μ. Additionally, the optical conductivity is shown to be obtainable from G with negligibly small vertex corrections. These results are shown to hold to each order in λ. -- Highlights: •Infinite-dimensional t–J model (J=0) studied within new ECFL theory. •Mapping to the infinite U Anderson model with self consistent hybridization. •Single particle Green’s function determined by two local self energies. •Partial projection through control variable λ. •Expansion carried out to O(λ{sup 2}) explicitly.

  9. Particle-hole symmetry and the composite Fermi liquid

    NASA Astrophysics Data System (ADS)

    Barkeshli, Maissam; Mulligan, Michael; Fisher, Matthew P. A.

    2015-10-01

    The half-filled Landau level is widely believed to be described by the Halperin-Lee-Read theory of the composite Fermi liquid (CFL). In this paper, we develop a theory for the particle-hole conjugate of the CFL, the anti-CFL, which we argue to be a distinct phase of matter as compared with the CFL. The anti-CFL provides a possible explanation of a recent experiment [D. Kamburov et al., Phys. Rev. Lett. 113, 196801 (2014), 10.1103/PhysRevLett.113.196801] demonstrating that the density of composite fermions in GaAs quantum wells corresponds to the electron density when the filling fraction ν <1/2 and to the hole density when ν >1/2 . We introduce a local field theory for the CFL and anti-CFL in the presence of a boundary, which we use to study CFL-insulator-CFL junctions, and the interface between the anti-CFL and CFL. We show that the CFL-anti-CFL interface allows partially fused boundary phases in which "composite electrons" can directly tunnel into "composite holes," providing a nontrivial example of transmutation between topologically distinct quasiparticles. We discuss several observable consequences of the anti-CFL, including a predicted resistivity jump at a first-order transition between uniform CFL and anti-CFL phases. We also present a theory of a continuous quantum phase transition between the CFL and anti-CFL. We conclude that particle-hole symmetry requires a modified view of the half-filled Landau level, in the presence of strong electron-electron interactions and weak disorder, as a critical point between the CFL and the anti-CFL.

  10. Field-Induced Quantum Critical Route to a Fermi Liquid in Overdoped Tl2Ba2CuO6+x

    NASA Astrophysics Data System (ADS)

    Shibauchi, Takasada

    2009-03-01

    In high temperature superconductivity, charge doping is a natural tuning parameter that takes copper oxides from the antiferromagnet through the superconducting `dome'-shaped region. In the metallic state above Tc the standard Landau's Fermi-liquid theory of metals, as typified by the temperature squared (AT^2) dependence of resistivity, appears to break down. The expected recovery of the usual Fermi-liquid metal on the high doping side is fundamental but ill understood. Here we uncover a new transformation in an overdoped superconducting copper oxide Tl2Ba2CuO6+x from the non-Fermi to a Fermi-liquid state driven by magnetic field [1]. From the c-axis resistivity measured up to 45 T, we show that the Fermi-liquid AT^2 features, accompanied by a field-linear magnetoresistance, appear above a field HFL. This crossover field HFL decreases linearly with decreasing temperature T and lands at a quantum critical point (QCP) near the upper critical field Hc2(0). The Fermi-liquid coefficient A(H) shows a power-law diverging behavior on the approach to the QCP, indicating the second-order quantum phase transition at this field. The connection between the field-induced QCP and the pseudogap observed in the underdoped regime will be discussed. [1] T. Shibauchi et al., Proc. Natl. Acad. Sci. USA 105, 7120 (2008).

  11. Magnetic-field-induced crossover from non-Fermi to Fermi liquid at the quantum critical point of YbCu5-xAux

    NASA Astrophysics Data System (ADS)

    Carretta, P.; Pasero, R.; Giovannini, M.; Baines, C.

    2009-01-01

    The temperature (T) dependence of the muon and C63u nuclear spin-lattice relaxation rates 1/T1 in YbCu4.4Au0.6 is reported over nearly four decades. It is shown that for T→0 1/T1 diverges following the behavior predicted by the self-consistent renormalization (SCR) theory for a ferromagnetic quantum critical point. On the other hand, the static uniform susceptibility χs is observed to diverge as T-2/3 and 1/T1T∝χs2 , a behavior which is not accounted for by SCR theory. The application of a magnetic field H is observed to induce a crossover to a Fermi-liquid behavior and for T→0 1/T1 is found to obey the scaling law 1/T1(H)=1/T1(0)[1+(μBH/kBT)2]-1 .

  12. Transport in thin polarized Fermi-liquid films

    NASA Astrophysics Data System (ADS)

    Li, David Z.; Anderson, R. H.; Miller, M. D.

    2015-10-01

    We calculate expressions for the state-dependent quasiparticle lifetime τσ, the thermal conductivity κ , the shear viscosity η , and discuss the spin diffusion coefficient D for Fermi-liquid films in two dimensions. The expressions are valid for low temperatures and arbitrary polarization. In two dimensions, as in three dimensions, the integrals over the transition rates factor into energy and angular parts. However, the angular integrations contain a weak divergence. This problem is addressed using the method of K. Miyake and W. J. Mullin [Phys. Rev. Lett. 50, 197 (1983), 10.1103/PhysRevLett.50.197; J. Low Temp. Phys. 56, 499 (1984), 10.1007/BF00681808]. The low-temperature expressions for the transport coefficients are essentially exact. We find that κ-1˜T lnT , and η-1˜T2 for arbitrary polarizations 0 ≤P ≤1 . These results are in agreement with earlier zero-polarization results of H. H. Fu and C. Ebner [Phys. Rev. A 10, 338 (1974)., 10.1103/PhysRevA.10.338], but differ from the temperature dependence of the shear viscosity found by D. S. Novikov (arXiv:cond-mat/0603184). They also differ from the discontinuous change of temperature dependence in D from zero to nonzero polarization that was discovered by Miyake and Mullin. We note that in two dimensions the shear viscosity requires a unique analysis. We obtain predictions for the density, temperature, and polarization dependence of κ ,η , and D for second-layer 3He films on graphite, and thin 3He-4He superfluid mixtures. For 3He on graphite, we find roughly an order of magnitude increase in magnitude for κ and η as the polarization is increased from 0 to 1. For D a similar large increase is predicted from zero polarization to the polarization where D is a maximum (˜0.74 ). We discuss the applicability of 3He thin films to

  13. Quantum statistical foundation to the Fermi liquid model and Ginzburg-Landau wave function

    SciTech Connect

    Fujita, Shigeji; Godoy, S. )

    1993-12-01

    An energy eigenvalue equation for a quasi-particle is derived, starting with the Heisenberg equation of motion for an annihilation operator. An elementary derivation of the Fermi liquid model having a sharply defined Fermi surface in the k-space is given, starting with a realistic model of a metal including the Coulomb interaction among and between electrons and lattice-ions. The Ginzburg-Landau wave function [Psi][sub [sigma

  14. A phenomenological description of an incoherent Fermi liquid near optimal doping in high Tc cuprates.

    PubMed

    Kim, Ki-Seok; Kim, Hyun-Chul

    2011-12-14

    Marginal Fermi-liquid physics near optimal doping in high T(c) cuprates has been explained within two competing scenarios such as the spin-fluctuation theory based on an itinerant picture and the slave-particle approach based on a localized picture. In this study we propose an alternative scenario for the anomalous transport within the context of the slave-particle approach. Although the marginal Fermi-liquid phenomenology was interpreted previously within deconfinement of the compact gauge theory, referred to as the strange metal phase, we start from confinement, introducing the Polyakov loop parameter into an SU(2) gauge theory formulation of the t-J model. The Polyakov loop parameter gives rise to incoherent electrons through the confinement of spinons and holons, which result from huge imaginary parts of self-energy corrections for spinons and holons. This confinement scenario serves a novel mechanism for the marginal Fermi-liquid transport in the respect that the scattering source has nothing to do with symmetry breaking. Furthermore, the incoherent Fermi-liquid state evolves into the Fermi-liquid phase through crossover instead of an artificial second-order transition as temperature is lowered, where the crossover phenomenon does not result from the Anderson-Higgs mechanism but originates from an energy scale in the holon sector. We fit experimental data for the electrical resistivity around the optimal doping and find a reasonable match between our theory and the experiment. PMID:22101360

  15. Holographic Fermi liquids in a spontaneously generated lattice

    NASA Astrophysics Data System (ADS)

    Alsup, James; Papantonopoulos, Eleftherios; Siopsis, George; Yeter, Kubra

    2016-05-01

    We discuss fermions in a spontaneously generated holographic lattice background. The lattice structure at the boundary is generated by introducing a higher-derivative interaction term between a U (1 ) gauge field and a scalar field. We solve the equations of motion below the critical temperature at which the lattice forms and analyze the change in the Fermi surface due to the lattice. The fermion band structure is found to exhibit a gap due to lattice effects.

  16. Fermi-Dirac statistics plus liquid description of quark partons

    NASA Astrophysics Data System (ADS)

    Buccella, F.; Miele, G.; Migliore, G.; Tibullo, V.

    1995-12-01

    A previous approach with Fermi-Dirac distributions for fermion partons is here improved to comply with the expected low x behaviour of structure functions. We are so able to get a fair description of the unpolarized and polarized structure functions of the nucleons as well as of neutrino data. We cannot reach definite conclusions, but confirm our suspicion of a relationship between the defects in Gottfried and spin sum rules.

  17. Destruction of Fermi liquid quasiparticles in two dimensions by critical fluctuations

    NASA Astrophysics Data System (ADS)

    Tremblay, Andr'e.-Marie

    1996-03-01

    For almost forty years, the concepts of Fermi liquid theory have served as a basis to understand interacting fermion systems. Recently, especially in the context of high-temperature superconductors, the universal applicability of Fermi-liquid theory has been challenged. Most studies of the stability of the Fermi liquid have been done at zero temperature. However, in many physically interesting cases, a phase transition at some temperature Tc trivially precludes a zero-temperature Fermi liquid. Yet the system behaves as a Fermi liquid at finite temperature when T_cFermi liquid quasiparticles arises. This is especially interesting in two dimensions where the transition to a spin density wave state (SDW) occurs only at exactly zero temperature ( T_c=T_N=0) but the system enters a renormalized classical regime (RC) at a finite temperature T_X<t. After formulating the approach, (Y.M. Vilk, Liang Chen and A.-M.S. Tremblay Phys. Rev. B Rapid Comm. 49), 13 267 (1994), and J. Chem. Phys. Solids, (in press) and Y.M. Vilk and A.-M.S. Tremblay, Europhys. Lett. (in press) I use it to find under which conditions critical spin fluctuations destroy the original Fermi liquid quasiparticles in the paramagnetic state. The quasiparticles are replaced by precursors of

  18. Spin-orbit coupled Fermi liquid theory of ultracold magnetic dipolar fermions

    NASA Astrophysics Data System (ADS)

    Li, Yi; Wu, Congjun

    2012-05-01

    We investigate Fermi liquid states of the ultracold magnetic dipolar Fermi gases in the simplest two-component case including both thermodynamic instabilities and collective excitations. The magnetic dipolar interaction is invariant under the simultaneous spin-orbit rotation but not under either the spin or the orbit one. Therefore, the corresponding Fermi liquid theory is intrinsically spin-orbit coupled. This is a fundamental feature of magnetic dipolar Fermi gases different from electric dipolar ones. The Landau interaction matrix is calculated and is diagonalized in terms of the spin-orbit coupled partial-wave channels of the total angular momentum J. The leading thermodynamic instabilities lie in the channels of ferromagnetism hybridized with the ferronematic order with J=1+ and the spin-current mode with J=1-, where + and - represent even and odd parities, respectively. An exotic propagating collective mode is identified as spin-orbit coupled Fermi surface oscillations in which spin distribution on the Fermi surface exhibits a topologically nontrivial hedgehog configuration.

  19. Pairing instabilities of a Non-Fermi liquid in the presence of nematic and gauge fluctuations

    NASA Astrophysics Data System (ADS)

    Mesaros, Andrej; Lawler, Michael J.; Kim, Eun-Ah

    2015-03-01

    In the absence of Fermi-liquid starting point, instabilities of non-Fermi liquids are theoretically challenging problems. Here we note that a non-Fermi liquid state occurring at ν = 1 / 2 may be a promising concrete case for theoretical investigation of the issue for two reasons. Firstly, exotic ordered states observed in half-filled Landau levels, namely the FQH state at ν = 5 / 2 which is most likely best described as a paired state, and the quantum Hall nematic state at ν = 9 / 2 , present a compelling possibility that the non-Fermi liquid state with gauge fluctuations at ν = 1 / 2 is close to instabilities towards these ordered states. Secondly, a recent theoretical progress [Metlitski et al., arXiv:1403.3694] offers a scheme for a controlled renormalization group study of the problem. We will discuss competition between the two fluctuations in promoting or suppressing a superconducting instability, based on the phase diagram we obtain from a renormalization group calculation. This research was supported by NSF through CAREER Grant DMR-0955822.

  20. A novel non-Fermi-liquid state in the iron-pnictide FeCrAs

    NASA Astrophysics Data System (ADS)

    Wu, Wenlong; McCollam, Alix; Swainson, Ian; Rourke, Patrick; Rancourt, Denis; Julian, Stephen

    2009-03-01

    We report transport and thermodynamic properties of stoichiometric single crystals of the hexagonal iron-pnictide FeCrAs. The in-plane resistivity shows an unusual ``non-metallic" dependence on temperature T, rising continuously with decreasing T from ˜ 800 K tobelow 100 mK. The c-axis resistivity is similar, except for a sharp drop upon entry into an antiferromagnetic state at TN˜125 K. Below 10 K the resistivity follows a non-Fermi-liquid power law, ρ(T) =ρ0-AT^x with x<1. The specific heat, on the other hand, shows typical Fermi liquid behaviour with a linear temperature dependence and a large Sommerfeld coefficient, γ˜30 mJ/mol,^2. The magnetic susceptibility does not follow Curie-Weiss law and it is rather weakly temperature dependent at low temperature. The high temperature properties of FeCrAs are reminiscent of those of the parent compounds of the new layered iron-pnictide superconductors, however the T ->0 K properties suggest a new class of non-Fermi liquid. This low temperature state has some features expected of a fractionalized electron system, in which conduction electrons break up into a charge carrying part that scatters anomalously and a spin part that has the thermodynamic properties of a Fermi liquid.

  1. Strong Quantum Coherence between Fermi Liquid Mahan Excitons

    NASA Astrophysics Data System (ADS)

    Paul, J.; Stevens, C. E.; Liu, C.; Dey, P.; McIntyre, C.; Turkowski, V.; Reno, J. L.; Hilton, D. J.; Karaiskaj, D.

    2016-04-01

    In modulation doped quantum wells, the excitons are formed as a result of the interactions of the charged holes with the electrons at the Fermi edge in the conduction band, leading to the so-called "Mahan excitons." The binding energy of Mahan excitons is expected to be greatly reduced and any quantum coherence destroyed as a result of the screening and electron-electron interactions. Surprisingly, we observe strong quantum coherence between the heavy hole and light hole excitons. Such correlations are revealed by the dominating cross-diagonal peaks in both one-quantum and two-quantum two-dimensional Fourier transform spectra. Theoretical simulations based on the optical Bloch equations where many-body effects are included phenomenologically reproduce well the experimental spectra. Time-dependent density functional theory calculations provide insight into the underlying physics and attribute the observed strong quantum coherence to a significantly reduced screening length and collective excitations of the many-electron system.

  2. Strong quantum coherence between Fermi liquid Mahan excitons

    DOE PAGESBeta

    Paul, J.; Stevens, C. E.; Liu, C.; Dey, P.; McIntyre, C.; Turkowski, V.; Reno, J. L.; Hilton, D. J.; Karaiskaj, D.

    2016-04-14

    In modulation doped quantum wells, the excitons are formed as a result of the interactions of the charged holes with the electrons at the Fermi edge in the conduction band, leading to the so-called “Mahan excitons.” The binding energy of Mahan excitons is expected to be greatly reduced and any quantum coherence destroyed as a result of the screening and electron-electron interactions. Surprisingly, we observe strong quantum coherence between the heavy hole and light hole excitons. Such correlations are revealed by the dominating cross-diagonal peaks in both one-quantum and two-quantum two-dimensional Fourier transform spectra. Theoretical simulations based on the opticalmore » Bloch equations where many-body effects are included phenomenologically reproduce well the experimental spectra. Furthermore, time-dependent density functional theory calculations provide insight into the underlying physics and attribute the observed strong quantum coherence to a significantly reduced screening length and collective excitations of the many-electron system.« less

  3. Strong Quantum Coherence between Fermi Liquid Mahan Excitons.

    PubMed

    Paul, J; Stevens, C E; Liu, C; Dey, P; McIntyre, C; Turkowski, V; Reno, J L; Hilton, D J; Karaiskaj, D

    2016-04-15

    In modulation doped quantum wells, the excitons are formed as a result of the interactions of the charged holes with the electrons at the Fermi edge in the conduction band, leading to the so-called "Mahan excitons." The binding energy of Mahan excitons is expected to be greatly reduced and any quantum coherence destroyed as a result of the screening and electron-electron interactions. Surprisingly, we observe strong quantum coherence between the heavy hole and light hole excitons. Such correlations are revealed by the dominating cross-diagonal peaks in both one-quantum and two-quantum two-dimensional Fourier transform spectra. Theoretical simulations based on the optical Bloch equations where many-body effects are included phenomenologically reproduce well the experimental spectra. Time-dependent density functional theory calculations provide insight into the underlying physics and attribute the observed strong quantum coherence to a significantly reduced screening length and collective excitations of the many-electron system. PMID:27127985

  4. Spin Relaxation in Hyperpolarized He-3 Fermi Liquids

    NASA Astrophysics Data System (ADS)

    Stanton, Liam; Bedell, Kevin

    2004-03-01

    In the past few years, attention has been drawn towards the hyperpolarized gases of Xenon-129 and Helium-3 isotopes. Medical research has explored the possibilities of using these isotopes for magnetic resonance imaging (MRI) of the lungs in both human and animal test subjects. Because the atoms of hyperpolarized gas are forced into a specific spin state, the MRI signal is enhanced. While the spin relaxation times of Helium-3 can be calculated in the high and low temperature limits, there exists no exact analytic solution for intermediate temperatures. The intention of this research was to numerically connect these limits with an accurate approximation. To do this, various analytic and numerical methods were used to reduce the spin relaxation time to a function of temperature, chemical potential, and particle number. Additional numerical methods were then used to calculate the chemical potential of Helium-3. The data show that a minimum occurs in the spin relaxation time at the order of the Fermi temperature, after which the classical limit is rapidly approached. These computational results seem to coincide with those expected.

  5. Reprint of : Regular and singular Fermi liquid in triple quantum dots: Coherent transport studies

    NASA Astrophysics Data System (ADS)

    Tooski, S. B.; Ramšak, A.; Bułka, B. R.

    2016-08-01

    A system of three coupled quantum dots in a triangular geometry (TQD) with electron-electron interaction and symmetrically coupled to two leads is analyzed with respect to the electron transport by means of the numerical renormalization group. Varying gate potentials this system exhibits extremely rich range of regimes with different many-electron states with various local spin orderings. It is demonstrated how the Luttinger phase changes in a controlled manner which then via the Friedel sum rule formula exactly reproduces the conductance through the TQD system. The analysis of the uncoupled TQD molecule from the leads gives a reliable qualitative understanding of various relevant regimes and an insight into the phase diagram with the regular Fermi liquid and singular-Fermi liquid phases.

  6. Regular and singular Fermi liquid in triple quantum dots: Coherent transport studies

    NASA Astrophysics Data System (ADS)

    Tooski, S. B.; Ramšak, A.; Bułka, B. R.

    2016-01-01

    A system of three coupled quantum dots in a triangular geometry (TQD) with electron-electron interaction and symmetrically coupled to two leads is analyzed with respect to the electron transport by means of the numerical renormalization group. Varying gate potentials this system exhibits extremely rich range of regimes with different many-electron states with various local spin orderings. It is demonstrated how the Luttinger phase changes in a controlled manner which then via the Friedel sum rule formula exactly reproduces the conductance through the TQD system. The analysis of the uncoupled TQD molecule from the leads gives a reliable qualitative understanding of various relevant regimes and an insight into the phase diagram with the regular Fermi liquid and singular-Fermi liquid phases.

  7. Unconventional non-Fermi liquid state caused by nematic criticality in cuprates

    NASA Astrophysics Data System (ADS)

    Wang, Jing-Rong; Liu, Guo-Zhu; Zhang, Chang-Jin

    2016-07-01

    At the nematic quantum critical point that exists in the {d}{x2-{y}2}-wave superconducting dome of cuprates, the massless nodal fermions interact strongly with the quantum critical fluctuation of nematic order. We study this problem by means of the renormalization group approach and show that, the fermion damping rate | {Im}{{{Σ }}}R(ω )| vanishes more rapidly than the energy ω and the quasiparticle residue {Z}f\\to 0 in the limit ω \\to 0. The nodal fermions thus constitute an unconventional non-Fermi liquid that represents an even weaker violation of Fermi liquid theory than a marginal Fermi liquid. We also investigate the interplay of quantum nematic critical fluctuation and gauge-potential-like disorder, and find that the effective disorder strength flows to the strong coupling regime at low energies. Therefore, even an arbitrarily weak disorder can drive the system to become a disorder controlled diffusive state. Based on these theoretical results, we are able to understand a number of interesting experimental facts observed in curpate superconductors.

  8. Direct observation of a Fermi liquid-like normal state in an iron-pnictide superconductor.

    PubMed

    Tytarenko, Alona; Huang, Yingkai; de Visser, Anne; Johnston, Steve; van Heumen, Erik

    2015-01-01

    There are two prerequisites for understanding high-temperature (high-Tc) superconductivity: identifying the pairing interaction and obtaining a correct description of the normal state from which superconductivity emerges. The nature of the normal state of iron-pnictide superconductors, and the role played by correlations arising from partially screened interactions, are still under debate. Here we show that the normal state of carefully annealed electron-doped BaFe(2-x)Co(x)As2 at low temperatures has all the hallmark properties of a local Fermi liquid, with a more incoherent state emerging at elevated temperatures, an identification made possible using bulk-sensitive optical spectroscopy with high frequency and temperature resolution. The frequency dependent scattering rate extracted from the optical conductivity deviates from the expected scaling M2 (ω, T) ∝ (ħω)(2) + (pπkBT)(2) with p ≈ 1.47 rather than p = 2, indicative of the presence of residual elastic resonant scattering. Excellent agreement between the experimental results and theoretical modeling allows us to extract the characteristic Fermi liquid scale T0 ≈ 1700 K. Our results show that the electron-doped iron-pnictides should be regarded as weakly correlated Fermi liquids with a weak mass enhancement resulting from residual electron-electron scattering from thermally excited quasi-particles. PMID:26201499

  9. Transport phenomena in correlated quantum liquids: Ultracold Fermi gases and F/N junctions

    NASA Astrophysics Data System (ADS)

    Li, Hua

    Landau Fermi-liquid theory was first introduced by L. D. Landau in the effort of understanding the normal state of Fermi systems, where the application of the concept of elementary excitations to the Fermi systems has proved very fruitful in clarifying the physics of strongly correlated quantum systems at low temperatures. In this thesis, I use Landau Fermi-liquid theory to study the transport phenomena of two different correlated quantum liquids: the strongly interacting ultracold Fermi gases and the ferromagnet/normal-metal (F/N) junctions. The detailed work is presented in chapter II and chapter III of this thesis, respectively. Chapter I holds the introductory part and the background knowledge of this thesis. In chapter II, I study the transport properties of a Fermi gas with strong attractive interactions close to the unitary limit. In particular, I compute the transport lifetimes of the Fermi gas due to superfluid fluctuations above the BCS transition temperature Tc. To calculate the transport lifetimes I need the scattering amplitudes. The scattering amplitudes are dominated by the superfluid fluctuations at temperatures just above Tc. The normal scattering amplitudes are calculated from the Landau parameters. These Landau parameters are obtained from the local version of the induced interaction model for computing Landau parameters. I also calculate the leading order finite temperature corrections to the various transport lifetimes. A calculation of the spin diffusion coefficient is presented in comparison to the experimental findings. Upon choosing a proper value of F0a, I am able to present a good match between the theoretical result and the experimental measurement, which indicates the presence of the superfluid fluctuations near Tc. Calculations of the viscosity, the viscosity/entropy ratio and the thermal conductivity are also shown in support of the appearance of the superfluid fluctuations. In chapter III, I study the spin transport in the low

  10. Evaporation temperature-tuned physical vapor deposition growth engineering of one-dimensional non-Fermi liquid tetrathiofulvalene tetracyanoquinodimethane thin films

    NASA Astrophysics Data System (ADS)

    Sarkar, I.; Laux, M.; Demokritova, J.; Ruffing, A.; Mathias, S.; Wei, J.; Solovyeva, V.; Rudloff, M.; Naghavi, S. S.; Felser, C.; Huth, M.; Aeschlimann, M.

    2010-09-01

    We describe the growth of high quality tetrathiofulvalene tetracyanoquinodimethane (TTF-TCNQ) organic charge-transfer thin films which show a clear non-Fermi liquid behavior. Temperature dependent angle resolved photoemission spectroscopy and electronic structure calculations show that the growth of TTF-TCNQ films is accompanied by the unfavorable presence of neutral TTF and TCNQ molecules. The quality of the films can be controlled by tuning the evaporation temperature of the precursor in physical vapor deposition method.

  11. Nonlinear optical conductivity of U (1 ) spin liquids with large spinon Fermi surfaces

    NASA Astrophysics Data System (ADS)

    Ma, Yuan-Fei; Ng, Tai-Kai

    2016-06-01

    In this paper we study the nonlinear current response of U (1 ) spin liquids with large spinon Fermi surfaces under the perturbation of a time-dependent ac electric field E (t ) within the framework of an effective U (1 ) gauge theory. In particular, the third-order nonlinear current response to ac electric fields is derived. We show that as in the case of linear current response, an in-gap power-law (˜ωη ) response is found for the nonlinear current at low frequency. The nonlinear susceptibility may also induce through process of third harmonic generation propagating EM wave with frequency 3 ω inside the spin liquids.

  12. Unconventional symmetries of Fermi liquid and Cooper pairing properties with electric and magnetic dipolar fermions

    NASA Astrophysics Data System (ADS)

    Li, Yi; Wu, Congjun

    2014-12-01

    The rapid experimental progress of ultra-cold dipolar fermions opens up a whole new opportunity to investigate novel many-body physics of fermions. In this article, we review theoretical studies of the Fermi liquid theory and Cooper pairing instabilities of both electric and magnetic dipolar fermionic systems from the perspective of unconventional symmetries. When the electric dipole moments are aligned by the external electric field, their interactions exhibit the explicit dr^2-3z^2 anisotropy. The Fermi liquid properties, including the single-particle spectra, thermodynamic susceptibilities and collective excitations, are all affected by this anisotropy. The electric dipolar interaction provides a mechanism for the unconventional spin triplet Cooper pairing, which is different from the usual spin-fluctuation mechanism in solids and the superfluid 3He. Furthermore, the competition between pairing instabilities in the singlet and triplet channels gives rise to a novel time-reversal symmetry breaking superfluid state. Unlike electric dipole moments which are induced by electric fields and unquantized, magnetic dipole moments are intrinsic proportional to the hyperfine-spin operators with a Lande factor. Its effects even manifest in unpolarized systems exhibiting an isotropic but spin-orbit coupled nature. The resultant spin-orbit coupled Fermi liquid theory supports a collective sound mode exhibiting a topologically non-trivial spin distribution over the Fermi surface. It also leads to a novel p-wave spin triplet Cooper pairing state whose spin and orbital angular momentum are entangled to the total angular momentum J = 1 dubbed the J-triplet pairing. This J-triplet pairing phase is different from both the spin-orbit coupled 3He-B phase with J = 0 and the spin-orbit decoupled 3He-A phase.

  13. Unconventional symmetries of Fermi liquid and Cooper pairing properties with electric and magnetic dipolar fermions.

    PubMed

    Li, Yi; Wu, Congjun

    2014-12-10

    The rapid experimental progress of ultra-cold dipolar fermions opens up a whole new opportunity to investigate novel many-body physics of fermions. In this article, we review theoretical studies of the Fermi liquid theory and Cooper pairing instabilities of both electric and magnetic dipolar fermionic systems from the perspective of unconventional symmetries. When the electric dipole moments are aligned by the external electric field, their interactions exhibit the explicit d(r(2)-3z(2)) anisotropy. The Fermi liquid properties, including the single-particle spectra, thermodynamic susceptibilities and collective excitations, are all affected by this anisotropy. The electric dipolar interaction provides a mechanism for the unconventional spin triplet Cooper pairing, which is different from the usual spin-fluctuation mechanism in solids and the superfluid (3)He. Furthermore, the competition between pairing instabilities in the singlet and triplet channels gives rise to a novel time-reversal symmetry breaking superfluid state. Unlike electric dipole moments which are induced by electric fields and unquantized, magnetic dipole moments are intrinsic proportional to the hyperfine-spin operators with a Lande factor. Its effects even manifest in unpolarized systems exhibiting an isotropic but spin-orbit coupled nature. The resultant spin-orbit coupled Fermi liquid theory supports a collective sound mode exhibiting a topologically non-trivial spin distribution over the Fermi surface. It also leads to a novel p-wave spin triplet Cooper pairing state whose spin and orbital angular momentum are entangled to the total angular momentum J = 1 dubbed the J-triplet pairing. This J-triplet pairing phase is different from both the spin-orbit coupled (3)He-B phase with J = 0 and the spin-orbit decoupled (3)He-A phase. PMID:25401291

  14. Thermodynamics of a Fermi Liquid beyond the Low-Energy Limit

    NASA Astrophysics Data System (ADS)

    Chubukov, Andrey V.; Maslov, Dmitrii L.; Gangadharaiah, Suhas; Glazman, Leonid I.

    2005-07-01

    We consider the nonanalytic temperature dependences of the specific heat coefficient, C(T)/T, and spin susceptibility, χs(T), of 2D interacting fermions beyond the weak-coupling limit. We demonstrate within the Luttinger-Ward formalism that the leading temperature dependences of C(T)/T and χs(T) are linear in T, and are described by the Fermi liquid theory. We show that these temperature dependences are universally determined by the states near the Fermi level and, for a generic interaction, are expressed via the spin and charge components of the exact backscattering amplitude of quasiparticles. We compare our theory to recent experiments on monolayers of He3.

  15. Electronic structure Fermi liquid theory of high Tc superconductors: Comparison of predictions with experiments

    NASA Technical Reports Server (NTRS)

    Yu, Jaejun; Freeman, A. J.

    1991-01-01

    Predictions of local density functional (LDF) calculations of the electronic structure and transport properties of high T(sub c) superconductors are presented. As evidenced by the excellent agreement with both photoemission and positron annihilation experiments, a Fermi liquid nature of the 'normal' state of the high T(sub c) superconductors become clear for the metallic phase of these oxides. In addition, LDF predictions on the normal state transport properties are qualitatively in agreement with experiments on single crystals. It is emphasized that the signs of the Hall coefficients for the high T(sub c) superconductors are not consistent with the types of dopants (e.g., electron-doped or hole-doped) but are determined by the topology of the Fermi surfaces obtained from the LDF calculations.

  16. Phase Diagram of Pyrochlore Iridates: All-in-All-out Magnetic Ordering and Non-Fermi-Liquid Properties

    NASA Astrophysics Data System (ADS)

    Shinaoka, Hiroshi; Hoshino, Shintaro; Troyer, Matthias; Werner, Philipp

    2015-10-01

    We study the prototype 5 d pyrochlore iridate Y2 Ir2 O7 from first principles using the local density approximation and dynamical mean-field theory (LDA +DMFT ). We map out the phase diagram in the space of temperature, on-site Coulomb repulsion U , and filling. Consistent with experiments, we find that an all-in-all-out ordered insulating phase is stable for realistic values of U . The trigonal crystal field enhances the hybridization between the jeff=1 /2 and jeff=3 /2 states, and strong interband correlations are induced by the Coulomb interaction, which indicates that a three-band description is important. We demonstrate a substantial band narrowing in the paramagnetic metallic phase and non-Fermi-liquid behavior in the electron- or hole-doped system originating from long-lived quasi-spin-moments induced by nearly flat bands.

  17. Heat diffusion in the disordered Fermi and electron liquids: the role of inelastic processes

    NASA Astrophysics Data System (ADS)

    Schwiete, Georg; Finkel'Stein, Alexander

    2015-03-01

    We study thermal transport in the disordered Fermi and electron liquids at low temperatures. Gravitational potentials are used as sources for finding the heat density and its correlation function. For a comprehensive study, we extend the renormalization group (RG) analysis developed for electric transport by including the gravitational potentials into the RG scheme. The analysis reveals that for the disordered Fermi liquid the Wiedemann-Franz law remains valid even in the presence of quantum corrections caused by the interplay of diffusion modes and the electron-electron interaction. In the present scheme this fundamental relation is closely connected with a fixed point in the multi-parametric RG flow of the gravitational potentials. For the disordered electron liquid we additionally analyze inelastic processes induced by the Coulomb interaction at sub-temperature energies. While the general form of the correlation function has to be compatible with energy conservation, these inelastic processes are at the origin of logarithmic corrections violating the Wiedemann-Franz law. The interplay of various terms in the heat density-heat density correlation function therefore differs from that for densities of other conserved quantities, such as total number of particles or spin. A. F. and G. S. acknowledge support by the Alexander von Humboldt foundation. A.F. is supported by the National Science Foundation Grant NSF-DMR-1006752.

  18. Specific heat of /sup 3/He in the Fermi-liquid region

    SciTech Connect

    Mayberry, M.C.; Phillips, N.E.

    1983-03-01

    A CMN thermometer has been calibrated by nuclear-orientation thermometry at low temperatures and He vapor-pressure thermometry at high temperatures. The calibration agrees well with the NBS temperature scale between 100 and 200 mK. Specific-heat data on /sup 3/He in the Fermi-liquid region obtained with this thermometer are in good agreement with recent measurements at Bell Laboratories. It is argued that discrepancies with other data can be understood on the basis of errors in the temperature scales on which they are based.

  19. Ultrashort Optical Pulses in a Fermi Liquid and Duality of Gauge Gravitation

    NASA Astrophysics Data System (ADS)

    Konobeeva, N. N.; Belonenko, M. B.

    2016-07-01

    The problem of the propagation of ultrashort pulses, including both two-dimensional and three-dimensional pulses, in a Fermi liquid is considered with the help of representations of the duality of gauge gravitation. The electromagnetic field is considered classically on the basis of the Maxwell equations. The effective equation so obtained is analyzed numerically and the dynamics of the state of the electromagnetic field are elucidated in the planar case, and also when it is localized in two/three spatial dimensions.

  20. Corrections to Fermi Liquid theory in 2D in a magnetic field

    NASA Astrophysics Data System (ADS)

    Chubukov, Andrey; Betouras, Joseph; Efremov, Dmitri

    2005-03-01

    In this work, we consider a Fermi liquid in two dimensions in a magnetic field, and study the effects of the Zeeman splitting on thermodynamics. We derive the temperature dependence of the spin susceptibility χs(T) from the thermodynamic potential, and show explicitly how 2pF scattering gives rise to a non- analytic temperature dependence of the susceptibility. We explain why small momentum scattering does not give rise to non-analytic χs(T). We discuss experimental implications of this result.

  1. Relationship between lattice disorder and non-Fermi liquid properties in annealed UCu_4Pd

    NASA Astrophysics Data System (ADS)

    Booth, C. H.; Scheidt, E.-W.; Weber, A.; Maurer, D.; Kehrein, S.

    2002-03-01

    The heat capacity, electrical resistivity and lattice parameter of the lattice-disordered, non-Fermi liquid (NFL) material UCu_4Pd have been shown to be sensitive to annealing time.(A. Weber et al.), Phys. Rev. B 63, 205116 (2001). We present x-ray absorption fine-structure (XAFS) measurements from the Pd K and U L_III edges that show the percentage of Pd atoms on nominally Cu 16e sites within the C15b crystal structure decreases from about 27% to 19% upon the first day of annealing, and does not change measurably with further annealing. Moreover, the U-Cu bond length distribution width, σ, narrows monotonically, with Δ σ^2 = -0.00035(3) Åafter 14 days of annealing. These changes in the local lattice properties will be related to the measured changes in the NFL properties.

  2. Chiral spin waves in Fermi liquids with spin-orbit coupling.

    PubMed

    Ashrafi, Ali; Maslov, Dmitrii L

    2012-11-30

    We predict the existence of chiral spin waves-collective modes in a two-dimensional Fermi liquid with the Rashba or Dresselhaus spin-orbit coupling. Starting from the phenomenological Landau theory, we show that the long-wavelength dynamics of magnetization is governed by the Klein-Gordon equations. The standing-wave solutions of these equations describe ''particles" with effective masses, whose magnitudes and signs depend on the strength of the electron-electron interaction. The spectrum of the spin-chiral modes for arbitrary wavelengths is determined from the Dyson equation for the interaction vertex. We propose to observe spin-chiral modes via microwave absorption by standing waves confined by an in-plane profile of the spin-orbit splitting. PMID:23368155

  3. Many-body effects on the resistivity of a multi-orbital system beyond Landau's Fermi-liquid theory

    NASA Astrophysics Data System (ADS)

    Arakawa, Naoya

    2015-06-01

    I review many-body effects on the resistivity of a multi-orbital system beyond Landau's Fermi-liquid (FL) theory. Landau's FL theory succeeds in describing electronic properties of some correlated electron systems at low temperatures. However, the behaviors deviating from the temperature dependence in the FL, non-FL-like behaviors, emerge near a magnetic quantum-critical point (QCP). These indicate the importance of many-body effects beyond Landau's FL theory. Those effects in multi-orbital systems have been little understood, although their understanding is important to deduce ubiquitous properties of correlated electron systems and characteristic properties of multi-orbital systems. To improve this situation, I formulate the resistivity of a multi-orbital Hubbard model using the extended Éliashberg theory and adopt this method to the inplane resistivity of quasi-two-dimensional paramagnetic ruthenates in combination with the fluctuation-exchange approximation including the current vertex corrections arising from the self-energy and Maki-Thompson term. The results away from and near the antiferromagnetic QCP reproduce the temperature dependence observed in Sr2RuO4 and Sr2Ru0.075Ti0.025O4, respectively. I highlight the importance of not only the momentum and the temperature dependence of the damping of a quasiparticle but also its orbital dependence in discussing the resistivity of correlated electron systems.

  4. Evolution of ferromagnetic and non-Fermi-liquid states with doping: The case of Ru-doped UCoGe

    NASA Astrophysics Data System (ADS)

    Vališka, Michal; Pospíšil, Jiří; Diviš, Martin; Prokleška, Jan; Sechovský, Vladimír; Abd-Elmeguid, Mohsen M.

    2015-07-01

    We have investigated the impact of Ru substitution for Co on the behavior of the ferromagnetic superconductor UCoGe by performing x-ray diffraction, magnetization, specific heat, and electrical resistivity measurements on polycrystalline samples of the UCo1 -xRuxGe series (0 ≥x ≤0.9 ) . The initial Ru substitution up to x ≈0.1 leads to a simultaneous sharp increase of the Curie temperature and spontaneous magnetization up to maximum values of TC=8.6 K and MS=0.1 μB per formula unit, respectively, whereas superconductivity vanishes already for x ≈0.03 . Further increase of the Ru content beyond x ≈0.1 leads to a precipitous decrease of both TC and MS towards a ferromagnetic quantum critical point (QCP) at xcr=0.31 . Consequently, the T -x magnetic phase diagram consists of a well-developed ferromagnetic dome. We discuss the evolution of ferromagnetism with x on the basis of band structure changes due to varying 5 f -ligand hybridization. This scenario is supported by the results of electronic structure calculations and consideration of the simplified periodic Anderson model. The analysis of the temperature dependencies of the electrical resistivity and heat capacity at low temperatures of the samples in the vicinity of the QCP reveals a non-Fermi-liquid behavior and assigns the ferromagnetic quantum phase transition to be most likely of a continuous Hertz-Millis type.

  5. Correlations in the low-density Fermi gas: Fermi-liquid state, dimerization, and Bardeen-Cooper-Schrieffer pairing

    NASA Astrophysics Data System (ADS)

    Fan, H. H.; Krotscheck, E.; Lichtenegger, T.; Mateo, D.; Zillich, R. E.

    2015-08-01

    We present ground-state calculations for low-density Fermi gases described by two model interactions, an attractive square-well potential and a Lennard-Jones potential, of varying strength. We use the optimized Fermi-hypernetted chain integral equation method, which has been proved to provide, in the density regimes of interest here, an accuracy of better than 1%. We first examine the low-density expansion of the energy and compare it with the exact answer of H. Huang and C. N. Yang [Phys. Rev. 105, 767 (1957), 10.1103/PhysRev.105.767]. It is shown that a locally correlated wave function of the Jastrow-Feenberg type does not recover the quadratic term in the expansion of the energy in powers of a0kF , where a0 is the vacuum s -wave scattering length and kF the Fermi wave number. The problem is cured by adding second-order perturbation corrections in a correlated basis. Going to higher densities and/or more strongly coupled systems, we encounter an instability of the normal state of the system which is characterized by a divergence of the in-medium scattering length. We interpret this divergence as a phonon-exchange-driven dimerization of the system, similar to what occurs at zero density when the vacuum scattering length a0 diverges. We then study, in the stable regime, the superfluid gap and its dependence on the density and the interaction strength. We identify two corrections to low-density expansions: One is medium corrections to the pairing interaction, and the other is finite-range corrections. We show that the most important finite-range corrections are a direct manifestation of the many-body nature of the system.

  6. The effect of the Fermi resonance on the Raman scattering cross sections of the Fermi doublet ν1 and 2ν2 of liquid carbon disulfide in benzene

    NASA Astrophysics Data System (ADS)

    Li, Dong-Fei; Gao, Shu-Qin; Sun, Cheng-Lin; Jiang, Xiu-Lan; Li, Zuo-Wei

    2012-04-01

    The effect of the Fermi resonance (FR) on the Raman scattering cross sections (RSCSs) of the Fermi doublet ν1, 2ν2 of liquid CS2 in C6H6 using the method of changing the volume concentration of the solution is investigated. We have calculated the RSCSs of the Fermi doublet ν1, 2ν2 using Onsager's theory with the 992 cm-1 Raman line of C6H6 as the internal standard. The result shows that the RSCS of the ν1 line decreases with decreasing the volume concentration of CS2, while that of the 2ν2 line unexpectedly increases. With decreasing the volume concentration of CS2, two main effects of the solvent effect (SE) and the FR in binary solution that can make the ν1, 2ν2 RSCSs change: the SE, as calculated, reduces both the ν1 and 2ν2 RSCSs; the FR plays a significant role in reducing the ν1 RSCS and enhancing the 2ν2 RSCS. In comparison with our previous investigation [J. Raman Spectrosc. 41 (2010) 776-779], it was found that the stronger the FR is, the more the RSCS of the ν1 decreases and the 2ν2 increases. Thus, we proposed that the result can be best explained by taking into account the effect of the FR on the RSCSs of the Fermi doublet. In addition, this paper also gives an explanation to the experimental results deviating from the theoretical results of the scattering coefficients of CS2 in solvent C6H6 as mentioned in Fini's paper.

  7. Nematic quantum phase transition of composite Fermi liquids in half-filled Landau levels and their geometric response

    NASA Astrophysics Data System (ADS)

    You, Yizhi; Cho, Gil Young; Fradkin, Eduardo

    2016-05-01

    We present a theory of the isotropic-nematic quantum phase transition in the composite Fermi liquid arising in half-filled Landau levels. We show that the quantum phase transition between the isotropic and the nematic phase is triggered by an attractive quadrupolar interaction between electrons, as in the case of conventional Fermi liquids. We derive the theory of the nematic state and of the phase transition. This theory is based on the flux attachment procedure, which maps an electron liquid in half-filled Landau levels into the composite Fermi liquid close to a nematic transition. We show that the local fluctuations of the nematic order parameters act as an effective dynamical metric interplaying with the underlying Chern-Simons gauge fields associated with the flux attachment. Both the fluctuations of the Chern-Simons gauge field and the nematic order parameter can destroy the composite fermion quasiparticles and drive the system into a non-Fermi liquid state. The effective-field theory for the isotropic-nematic phase transition is shown to have z =3 dynamical exponent due to the Landau damping of the dense Fermi system. We show that there is a Berry-phase-type term that governs the effective dynamics of the nematic order parameter fluctuations, which can be interpreted as a nonuniversal "Hall viscosity" of the dynamical metric. We also show that the effective-field theory of this compressible fluid has a Wen-Zee-type term. Both terms originate from the time-reversal breaking fluctuation of the Chern-Simons gauge fields. We present a perturbative (one-loop) computation of the Hall viscosity and also show that this term is also obtained by a Ward identity. We show that the topological excitation of the nematic fluid, the disclination, carries an electric charge. We show that a resonance observed in radio-frequency conductivity experiments can be interpreted as a Goldstone nematic mode gapped by lattice effects.

  8. Nematic quantum phase transition of composite Fermi liquids in half-filled Landau levels and their geometric response

    NASA Astrophysics Data System (ADS)

    You, Yizhi; Cho, Gil Young; Fradkin, Eduardo

    We present a theory of isotropic-nematic quantum phase transition in the composite Fermi liquid arising in the half-filled Landau levels. We show that the quantum phase transition is triggered by the attractive quadrupolar interaction. By performing flux attachment, system turns into a composite Fermi liquid. The nematic order parameters act as the dynamical metric interplaying with the underlying topology, the Chern-Simons theory. Here both the fluctuations of the gauge field and the nematic order parameter can soften the Fermi surface and thus the fermions form a non-Fermi liquid. The effective field theory for the isotropic-nematic phase transition has z = 3 dynamical exponent due to the Landau damping due to the finite density of the fermions. We show that there is a Berry phase term of the nematic order parameter, which can be interpreted as the ``Hall viscosity'' of the dynamical metric. We also find the Wen-Zee-like term, which effectively dresses the nematic vortex with the electric charge. Both of the terms are originated from the time reversal breaking fluctuation of the Chern-Simons gauge fields. This indicates the fluctuations of the gauge fields modify the Hall viscosity and orbital spin of the compressible half-filled Landau level.

  9. Superconductivity from a confinement transition out of a fractionalized Fermi liquid with Z2 topological and Ising-nematic orders

    NASA Astrophysics Data System (ADS)

    Chatterjee, Shubhayu; Qi, Yang; Sachdev, Subir; Steinberg, Julia

    2016-07-01

    The Schwinger boson theory of the frustrated square lattice antiferromagnet yields a stable, gapped Z2 spin liquid ground state with time-reversal symmetry, incommensurate spin correlations, and long-range Ising-nematic order. We obtain an equivalent description of this state using fermionic spinons (the fermionic spinons can be considered to be bound states of the bosonic spinons and the visons). Upon doping, the Z2 spin liquid can lead to a fractionalized Fermi liquid (FL*) with small Fermi pockets of electronlike quasiparticles, while preserving the Z2 topological and Ising-nematic orders. We describe a Higgs transition out of this deconfined metallic state into a confining superconducting state which is almost always of the Fulde-Ferrell-Larkin-Ovchinnikov type, with spatial modulation of the superconducting order.

  10. Luttinger Theorem for the Strongly Correlated Fermi Liquid of Composite Fermions.

    PubMed

    Balram, Ajit C; Tőke, Csaba; Jain, J K

    2015-10-30

    While an ordinary Fermi sea is perturbatively robust to interactions, the paradigmatic composite-fermion (CF) Fermi sea arises as a nonperturbative consequence of emergent gauge fields in a system where there was no Fermi sea to begin with. A mean-field picture suggests two Fermi seas, of composite fermions made from electrons or holes in the lowest Landau level, which occupy different areas away from half filling and thus appear to represent distinct states. Using the microscopic theory of composite fermions, which satisfies particle-hole symmetry in the lowest Landau level to an excellent approximation, we show that the Fermi wave vectors at filling factors ν and 1-ν are equal when expressed in units of the inverse magnetic length, and are generally consistent with the experimental findings of Kamburov et al. [Phys. Rev. Lett. 113, 196801 (2014)]. Our calculations suggest that the area of the CF Fermi sea may slightly violate the Luttinger area rule. PMID:26565489

  11. Ground-state and dynamical properties of two-dimensional dipolar Fermi liquids

    SciTech Connect

    Abedinpour, Saeed H.; Asgari, Reza; Tanatar, B.; Polini, Marco

    2014-01-15

    We study the ground-state properties of a two-dimensional spin-polarized fluid of dipolar fermions within the Euler–Lagrange Fermi-hypernetted-chain approximation. Our method is based on the solution of a scattering Schrödinger equation for the “pair amplitude” √(g(r)), where g(r) is the pair distribution function. A key ingredient in our theory is the effective pair potential, which includes a bosonic term from Jastrow–Feenberg correlations and a fermionic contribution from kinetic energy and exchange, which is tailored to reproduce the Hartree–Fock limit at weak coupling. Very good agreement with recent results based on quantum Monte Carlo simulations is achieved over a wide range of coupling constants up to the liquid-to-crystal quantum phase transition. Using the fluctuation–dissipation theorem and a static approximation for the effective inter-particle interactions, we calculate the dynamical density–density response function, and furthermore demonstrate that an undamped zero-sound mode exists for any value of the interaction strength, down to infinitesimally weak couplings. -- Highlights: •We have studied the ground state properties of a strongly correlated two-dimensional fluid of dipolar fermions. •We have calculated the effective inter-particle interaction and the dynamical density–density response function. •We have shown that an undamped zero sound mode exists at any value of the interaction strength.

  12. Renormalization group analysis of thermal transport in the disordered Fermi liquid

    NASA Astrophysics Data System (ADS)

    Schwiete, G.; Finkel'stein, A. M.

    2014-10-01

    We present a detailed study of thermal transport in the disordered Fermi liquid with short-range interactions. At temperatures smaller than the impurity scattering rate, i.e., in the diffusive regime, thermal conductivity acquires nonanalytic quantum corrections. When these quantum corrections become large at low temperatures, the calculation of thermal conductivity demands a theoretical approach that treats disorder and interactions on an equal footing. In this paper, we develop such an approach by merging Luttinger's idea of using gravitational potentials for the analysis of thermal phenomena with a renormalization group calculation based on the Keldysh nonlinear sigma model. The gravitational potentials are introduced in the action as auxiliary sources that couple to the heat density. These sources are a convenient tool for generating expressions for the heat density and its correlation function from the partition function. Already in the absence of the gravitational potentials, the nonlinear sigma model contains several temperature-dependent renormalization group charges. When the gravitational potentials are introduced into the model, they acquire an independent renormalization group flow. We show that this flow preserves the phenomenological form of the correlation function, reflecting its relation to the specific heat and the constraints imposed by energy conservation. The main result of our analysis is that the Wiedemann-Franz law holds down to the lowest temperatures even in the presence of disorder and interactions and despite the quantum corrections that arise for both the electric and thermal conductivities.

  13. Non-Fermi-liquid and topological states with strong spin-orbit coupling.

    PubMed

    Moon, Eun-Gook; Xu, Cenke; Kim, Yong Baek; Balents, Leon

    2013-11-15

    We argue that a class of strongly spin-orbit-coupled materials, including some pyrochlore iridates and the inverted band gap semiconductor HgTe, may be described by a minimal model consisting of the Luttinger Hamiltonian supplemented by Coulomb interactions, a problem studied by Abrikosov and collaborators. It contains twofold degenerate conduction and valence bands touching quadratically at the zone center. Using modern renormalization group methods, we update and extend Abrikosov's classic work and show that interactions induce a quantum critical non-Fermi-liquid phase, stable provided time-reversal and cubic symmetries are maintained. We determine the universal power-law exponents describing various observables in this Luttinger-Abrikosov-Beneslavskii state, which include conductivity, specific heat, nonlinear susceptibility, and the magnetic Gruneisen number. Furthermore, we determine the phase diagram in the presence of cubic and/or time-reversal symmetry breaking perturbations, which includes a topological insulator and Weyl semimetal phases. Many of these phases possess an extraordinarily large anomalous Hall effect, with the Hall conductivity scaling sublinearly with magnetization σ(xy)∼M0.51. PMID:24289698

  14. Decoherence of Impurities in a Fermi Sea of Ultracold Atoms.

    PubMed

    Cetina, Marko; Jag, Michael; Lous, Rianne S; Walraven, Jook T M; Grimm, Rudolf; Christensen, Rasmus S; Bruun, Georg M

    2015-09-25

    We investigate the decoherence of ^{40}K impurities interacting with a three-dimensional Fermi sea of ^{6}Li across an interspecies Feshbach resonance. The decoherence is measured as a function of the interaction strength and temperature using a spin-echo atom interferometry method. For weak to moderate interaction strengths, we interpret our measurements in terms of scattering of K quasiparticles by the Fermi sea and find very good agreement with a Fermi liquid calculation. For strong interactions, we observe significant enhancement of the decoherence rate, which is largely independent of temperature, pointing to behavior that is beyond the scattering of quasiparticles in the Fermi liquid picture. PMID:26451562

  15. Decoherence of Impurities in a Fermi Sea of Ultracold Atoms

    NASA Astrophysics Data System (ADS)

    Cetina, Marko; Jag, Michael; Lous, Rianne S.; Walraven, Jook T. M.; Grimm, Rudolf; Christensen, Rasmus S.; Bruun, Georg M.

    2015-09-01

    We investigate the decoherence of 40K impurities interacting with a three-dimensional Fermi sea of 6Li across an interspecies Feshbach resonance. The decoherence is measured as a function of the interaction strength and temperature using a spin-echo atom interferometry method. For weak to moderate interaction strengths, we interpret our measurements in terms of scattering of K quasiparticles by the Fermi sea and find very good agreement with a Fermi liquid calculation. For strong interactions, we observe significant enhancement of the decoherence rate, which is largely independent of temperature, pointing to behavior that is beyond the scattering of quasiparticles in the Fermi liquid picture.

  16. Investigation of fermionic pairing on tight binding lattice for low dimensional systems - Fermi liquid vs. Luttinger-Tomonaga liquid

    NASA Astrophysics Data System (ADS)

    Roy Chowdhury, Soumi; Chaudhury, Ranjan

    2015-05-01

    Cooper's original one pair problem in continuum is revisited here corresponding to a lattice of tight binding nature, with an aim to investigate superconductivity in low dimensional systems. An electronic type of boson mediated attraction in a passive Fermi sea-like background is considered for the pairing mechanism with the non-trivial energy dependence of the electronic density of states taken into account in the calculation in a rigorous way. Some of the very important electronic and optical properties in the normal phase of quasi one dimensional organic superconductors are used for the development of the formalism and calculations. The results of our calculations show that a realistic fermionic pair formation is indeed possible with some constraints, without any necessity at all of invoking Luttinger-Tomonaga liquid (LTL) theory. Similarities emerge in the physical properties of the electron pair formed from Cooper's treatment corresponding to continuum and ours, excepting the striking difference appearing in the form of occurrences of a maximum allowed band filling for pairing and of an upper bound of the pairing energy found in our approach.

  17. Non-Fermi liquid scaling in UPd(x)Cu(5-x)(x = 1,1.5)

    NASA Astrophysics Data System (ADS)

    Aronson, M. C.; Osborn, R.; Robinson, R. A.; Lynn, J. W.

    1994-06-01

    We have determined the inelastic magnetic response S((omega)) of UPd(x)Cu(5-x) (X=1,1.5) for temperatures from 0.3 to 300 K and energies between 05 and 400 meV using the neutron time of flight technique. S((omega)) is virtually identical in the two compound, displaying marginal Fermi Liquid scaling over the entire range of temperatures, as well as scale invariant energetics.

  18. Non-Fermi Liquid Behaviour in the Heavy-Fermion Kondo Lattice Ce2Rh3Al9

    NASA Astrophysics Data System (ADS)

    Falkowski, M.; Strydom, A. M.

    2014-04-01

    In the heavy fermion class of strongly correlated electron systems, the Landau Fermi liquid description of metals has become a rather fragile basis on which to formulate an understanding of their ground state. The proximity to cooperative phenomena such as magnetic order and superconductivity and the amenability of Ce- and Yb-based compounds to be tuned into quantum criticality have been found to have extraordinary effects on the T→0 thermal scaling of electronic and magnetic properties. A collection of non-Fermi liquid scaling relations have thus far been proposed in the search for universality. Here we report on the physical properties of the heavy fermion Kondo lattice Ce2Rh3Al9. The low-temperature specific heat and electrical resistivity are best described by power laws in their temperature dependence, and we model these according to the expectation for a system close to a magnetic phase transition. We demonstrate how applied magnetic fields drive the transition from the Kondo coherent state, through a cross-over phase, and into Fermi-liquid behaviour at high fields and low temperatures.

  19. Intrinsic Damping of Collective Spin Modes in a Two-Dimensional Fermi Liquid with Spin-Orbit Coupling

    NASA Astrophysics Data System (ADS)

    Maiti, Saurabh; Maslov, Dmitrii L.

    2015-04-01

    A Fermi liquid with spin-orbit coupling (SOC) is expected to support a new set of collective modes: oscillations of magnetization in the absence of the magnetic field. We show that these modes are damped by the electron-electron interaction even in the limit of an infinitely long wavelength (q =0 ). The linewidth of the collective mode is on the order of Δ¯ 2/EF , where Δ ¯ is a characteristic spin-orbit energy splitting and EF is the Fermi energy. Such damping is in stark contrast to known damping mechanisms of both charge and spin collective modes in the absence of SOC, all of which disappear at q =0 , and arises because none of the components of total spin is conserved in the presence of SOC.

  20. Phase behavior of ionic liquid crystals

    NASA Astrophysics Data System (ADS)

    Kondrat, S.; Bier, M.; Harnau, L.

    2010-05-01

    Bulk properties of ionic liquid crystals are investigated using density functional theory. The liquid crystal molecules are represented by ellipsoidal particles with charges located in their center or at their tails. Attractive interactions are taken into account in terms of the Gay-Berne pair potential. Rich phase diagrams involving vapor, isotropic and nematic liquid, as well as smectic phases are found. The dependence of the phase behavior on various parameters such as the length of the particles and the location of charges on the particles is studied.

  1. Flow behavior in liquid molding

    NASA Technical Reports Server (NTRS)

    Hunston, D.; Phelan, F.; Parnas, R.

    1992-01-01

    The liquid molding (LM) process for manufacturing polymer composites with structural properties has the potential to significantly lower fabrication costs and increase production rates. LM includes both resin transfer molding and structural reaction injection molding. To achieve this potential, however, the underlying science base must be improved to facilitate effective process optimization and implementation of on-line process control. The National Institute of Standards and Technology (NIST) has a major program in LM that includes materials characterization, process simulation models, on-line process monitoring and control, and the fabrication of test specimens. The results of this program are applied to real parts through cooperative projects with industry. The key feature in the effort is a comprehensive and integrated approach to the processing science aspects of LM. This paper briefly outlines the NIST program and uses several examples to illustrate the work.

  2. Quantum Liquid Crystals in an Imbalanced Fermi Gas: Fluctuations and Fractional Vortices in Larkin-Ovchinnikov States

    SciTech Connect

    Radzihovsky, Leo; Vishwanath, Ashvin

    2009-07-03

    We develop a low-energy model of an unidirectional Larkin-Ovchinnikov (LO) state. Because the underlying rotational and translational symmetries are broken spontaneously, this gapless superfluid is a smectic liquid crystal, that exhibits fluctuations that are qualitatively stronger than in a conventional superfluid, thus requiring a fully nonlinear description of its Goldstone modes. Consequently, at nonzero temperature the LO superfluid is an algebraic phase even in 3D. It exhibits half-integer vortex-dislocation defects, whose unbinding leads to transitions to a superfluid nematic and other phases. In 2D at nonzero temperature, the LO state is always unstable to a nematic superfluid. We expect this superfluid liquid-crystal phenomenology to be realizable in imbalanced resonant Fermi gases trapped isotropically.

  3. Electronic specific heat enhancement in the half-metallic ferromagnet Cro2 explained by Fermi Liquid Theory

    NASA Astrophysics Data System (ADS)

    Chura, Raul; Bedell, Kevin

    2007-03-01

    Available data on the electronic specific heat of the half-metallic ferromagnet (HMF) CrO2, show that the obtained experimental values are systematically greater than the corresponding theoretical ones calculated through various band theory methods. This discrepancy is due to the presence of many-electron correlation effects (spin fluctuations, strong electron-magnon scattering) which are not taken into account in the band theory calculations. A renormalization of the band theory results is therefore needed to account for the observed enhancement in the value of the specific heat. A microscopic many-electron approach has been proposed and explains the referred enhancement in terms of non-quasiparticle effects. It has been argued that Fermi liquid theory is not sufficient to provide the appropriate renormalization able to explain the observed enhancement in the electronic specific heat of HMFs. Contrary to this statement, we have shown that the introduction of a spin-dependent density of states, in the framework of the Fermi liquid theory for spin polarized systems, gives place to a renormalization which, indeed, provides a reasonable account of the observed enhancement in the electronic specific heat of the HMF CrO2.

  4. Quantum order in chiral magnets: 3D Non-Fermi Liquid Phase and Blue Quantum Fog in MnSi

    NASA Astrophysics Data System (ADS)

    Pfleiderer, Christian

    2007-03-01

    The discovery of a distinct change from Fermi liquid to non-Fermi liquid resistivity and the observation of partial magnetic order in MnSi under high pressure [1,2] has generated great scientific interest in the properties of itinerant-electron systems with weak chiral spin-orbit interactions. Recent theoretical predictions include the spontaneous formation of a skyrmion phase at the boundary of conventional helical order [3] and the existence of a new type of Goldstone-like excitation, so called helimagnons [4]. New experimental work using sophisticated neutron scattering techniques and bulk properties exploring the question of skyrmion textures and helimagnon excitations, as well as studies of the thermal expansion under pressure using a newly developed ultra-high resolution neutron spin-resonance technique (Larmor diffraction) will be reviewed. [1] C. Pfleiderer, S. R. Julian, G. G. Lonzarich, Nature 414, 427 (2001). [2] C. Pfleiderer, et al., Nature 427, 227 (2004). [3] U. R"oßler, A. B. Bogdanov, C. Pfleiderer, Nature 442, 797 (2006). [4] D. Belitz, T. R. Kirkpatrick, A. Rosch, Phys. Rev. B 73, 054431 (2006).

  5. Interplay of Superconductivity and Fermi-Liquid Transport in Rh-Doped CaFe2As2 with Lattice-Collapse Transition

    NASA Astrophysics Data System (ADS)

    Danura, Masataka; Kudo, Kazutaka; Oshiro, Yoshihiro; Araki, Shingo; Kobayashi, Tatsuo C.; Nohara, Minoru

    2011-10-01

    Ca(Fe1-xRhx)2As2 undergoes successive phase transitions with increasing Rh doping in the T = 0 limit. The antiferromagnetic-metal phase with orthorhombic structure at 0.00 ≤ x ≤ 0.020 is driven to a superconducting phase with uncollapsed-tetragonal (ucT) structure at 0.020 ≤ x ≤ 0.024; a non-superconducting collapsed-tetragonal (cT) phase takes over at x ≥ 0.024. The breakdown of Fermi-liquid transport is observed in the ucT phase above Tc. In the adjacent cT phase, Fermi-liquid transport is restored along with a disappearance of superconductivity. This interplay of superconductivity and Fermi-liquid transport suggests the essential role of magnetic fluctuations in the emergence of superconductivity in doped CaFe2As2.

  6. Hidden Fermi liquid; the moral: a good effective low-energy theory is worth all of Monte Carlo with Las Vegas thrown in

    NASA Astrophysics Data System (ADS)

    Anderson, Philip W.; Casey, Philip A.

    2010-04-01

    We present a formalism for dealing directly with the effects of the Gutzwiller projection implicit in the t-J model which is widely believed to underlie the phenomenology of the high-Tc cuprates. We suggest that a true Bardeen-Cooper-Schrieffer condensation from a Fermi liquid state takes place, but in the unphysical space prior to projection. At low doping, however, instead of a hidden Fermi liquid one gets a 'hidden' non-superconducting resonating valence bond state which develops hole pockets upon doping. The theory which results upon projection does not follow conventional rules of diagram theory and in fact in the normal state is a Z = 0 non-Fermi liquid. Anomalous properties of the 'strange metal' normal state are predicted and compared against experimental findings.

  7. Angular dependence of novel magnetic quantum oscillations in a quasi-two-dimensional multiband Fermi liquid with impurities

    NASA Astrophysics Data System (ADS)

    Bratkovsky, A. M.; Alexandrov, A. S.

    2002-03-01

    The semiclassical Lifshitz-Kosevich-type description is given for the angular dependence of quantum oscillations with combination frequencies in a multiband quasi-two-dimensional Fermi liquid with a constant number of electrons. The analytical expressions are found for the Dingle, thermal, spin, and amplitude (Yamaji) reduction factors of the novel combination harmonics, where the latter two strongly oscillate with the direction of the field [1]. At the magic angles those factors reduce to the purely two-dimensional expressions given earlier. The combination harmonics are suppressed in the presence of the nonquantized background states, and they decay exponentially faster with temperature and/or disorder compared to the standard harmonics, providing an additional tool for electronic structure determination. The theory is applied to Sr2RuO4. [1] A.M. Bratkovsky and A.S. Alexandrov, Phys. Rev. B 65, xxxx (2002); cond-mat/0104520.

  8. Non-Fermi-liquid scattering rates and anomalous band dispersion in ferropnictides

    NASA Astrophysics Data System (ADS)

    Fink, J.; Charnukha, A.; Rienks, E. D. L.; Liu, Z. H.; Thirupathaiah, S.; Avigo, I.; Roth, F.; Jeevan, H. S.; Gegenwart, P.; Roslova, M.; Morozov, I.; Wurmehl, S.; Bovensiepen, U.; Borisenko, S.; Vojta, M.; Büchner, B.

    2015-11-01

    Angle-resolved photoemission spectroscopy is used to study the band dispersion and the quasiparticle scattering rates in two ferropnictide systems. We find the scattering rate for any given band to depend linearly on energy but to be independent of the control parameter. We demonstrate that the linear energy dependence gives rise to a weakly dispersing band with a strong mass enhancement when the band maximum crosses the chemical potential. The resulting small effective Fermi energy favors a BCS [J. Bardeen et al., Phys. Rev. 108, 1175 (1957), 10.1103/PhysRev.108.1175] -Bose-Einstein [S. N. Bose, Z. Phys. 26, 178 (1924), 10.1007/BF01327326] crossover state in the superconducting phase.

  9. Phases of one-dimensional SU(N) cold atomic Fermi gases-From molecular Luttinger liquids to topological phases

    NASA Astrophysics Data System (ADS)

    Capponi, S.; Lecheminant, P.; Totsuka, K.

    2016-04-01

    Alkaline-earth and ytterbium cold atomic gases make it possible to simulate SU(N)-symmetric fermionic systems in a very controlled fashion. Such a high symmetry is expected to give rise to a variety of novel phenomena ranging from molecular Luttinger liquids to (symmetry-protected) topological phases. We review some of the phases that can be stabilized in a one dimensional lattice. The physics of this multi-component Fermi gas turns out to be much richer and more exotic than in the standard SU(2) case. For N > 2, the phase diagram is quite rich already in the case of the single-band model, including a molecular Luttinger liquid (with dominant superfluid instability in the N-particle channel) for incommensurate fillings, as well as various Mott-insulating phases occurring at commensurate fillings. Particular attention will be paid to the cases with additional orbital degree of freedom (which is accessible experimentally either by taking into account two atomic states or by putting atoms in the p-band levels). We introduce two microscopic models which are relevant for these cases and discuss their symmetries and strong coupling limits. More intriguing phase diagrams are then presented including, for instance, symmetry protected topological phases characterized by non-trivial edge states.

  10. Double-Exchange physics in Non-Fermi-Liquid FeCrAs

    NASA Astrophysics Data System (ADS)

    O'Brien, Patrick; Birol, Turan; Ghosh, Shivam; Lawler, Michael; FeCrAs Collaboration

    2015-03-01

    We focus on the problem of determining the microscopic physics of the bad antiferromagnetic metal FeCrAs. It has been argued to be underscreened Kondo-like due to large spin moments on the Cr atoms. Using LDA+U, we show that indeed Kondo-like physics is likely. In particular, we find the band structure and Fermi surface to be hypersensitive to small changes in the Hund's coupling J with little evidence for crystal field splitting. We then propose a simple three dimensional lattice model using hybrid orbital ideas to capture hopping parameters and a Kondo coupling to capture the limit where J is larger than the crystal field splitting. This model is therefore distinct from one proposed in Ref. which assumes J is less than the crystal field splitting. We chose its parameters based on a best fit to the DFT results and use it to study the stability of the observed √{ 3} ×√{ 3} magnetic order on the kagome-like Cr lattice as a test of the model.

  11. Dynamic Behavior of EHD Extraction Phenomena of Liquids

    NASA Astrophysics Data System (ADS)

    Hanaoka, Ryoichi; Mizuno, Takanobu; Takata, Shinzo; Fukami, Tadashi; Anzai, Hidenobu

    On the liquid extraction phenomena in which are caused by a nonuniform electric field, the dynamic behavior of the liquids has been investigated experimentally using three working liquids; HFC43-10, HFE7600 and silicone oil. The sphere electrode in air over the liquid surface to the grounded plane electrode in the liquid is used as the experimental electrode configuration. When a positive or negative voltage is applied to the sphere electrode, the distinctive behaviors in each liquid are observed at an air region between the sphere electrode and the liquid surface. In HFC43-10 and HFE7600, the liquid at the air/liquid interface is swollen at just below of the sphere electrode with increasing the voltage. At a certain critical voltage, the liquid is extracted from the top of a swelled liquid and a liquid column between the sphere electrode and the liquid surface is formed instantaneously. Immediately after the formation of the column, the liquid is spouted like a shower from the sphere electrode surface to the liquid surface. The behavior in silicone oil is different from these. After swelling of the liquid, a large liquid drop is extracted intermittently from the top of a swelled liquid and it jumps toward the sphere electrode without the formation of a liquid column. On the other hand, in HFC43-10 and HFE7600, the evaporation of the liquid is accelerated by the applied electric field. The mechanism on these behaviors is discussed qualitatively on the basis of the experimental results.

  12. Behavior of Collective Cooperation Yielded by Two Update Rules in Social Dilemmas: Combining Fermi and Moran Rules

    NASA Astrophysics Data System (ADS)

    Xia, Cheng-Yi; Wang, Lei; Wang, Juan; Wang, Jin-Song

    2012-09-01

    We combine the Fermi and Moran update rules in the spatial prisoner's dilemma and snowdrift games to investigate the behavior of collective cooperation among agents on the regular lattice. Large-scale simulations indicate that, compared to the model with only one update rule, the cooperation behavior exhibits the richer phenomena, and the role of update dynamics should be paid more attention in the evolutionary game theory. Meanwhile, we also observe that the introduction of Moran rule, which needs to consider all neighbor's information, can markedly promote the aggregate cooperation level, that is, randomly selecting the neighbor proportional to its payoff to imitate will facilitate the cooperation among agents. Current results will contribute to further understand the cooperation dynamics and evolutionary behaviors within many biological, economic and social systems.

  13. Raman spectroscopy study on the ν1-2ν2 Fermi resonance of liquid carbon disulfide in binary solutions: Effect of the weak hydrogen bond formation on the Fermi resonance

    NASA Astrophysics Data System (ADS)

    Li, DongFei; Sun, Shang; Sun, ChengLin; Jiang, XiuLan; Gao, ShuQin; Li, ZuoWei

    2012-10-01

    We have measured the Raman spectra of liquid CS2 at different volume concentrations in CHCl3 and CH2Cl2 solutions. With decreasing the volume concentration of CS2, a noticeable growth in the 2ν2 band frequency was observed, while the ν1 band location remained practically unchanged. This asymmetric wavenumber shift phenomenon of the Fermi doublet ν1 and 2ν2 of CS2 has been ascribed to weak, non-conventional hydrogen bonds formed between the CS2 and the solvent molecules. These weak hydrogen bonds were also responsible for significant decreases in the C-H bond symmetric stretching vibration band frequencies of CHCl3 and CH2Cl2. The values of the ν1-2ν2 FR parameters of CS2 in CH2Cl2 and CHCl3 at different volume concentrations were calculated according to the FR theory. The magnitude of the FR coupling coefficient W of CS2 increases upon dilution with CH2Cl2 and CHCl3, indicating that the vibrational anharmonicity is relatively sensitive to variations in the weak hydrogen bonding. Compared with the changing tendencies of Fermi coupling coefficient W of CS2 in CH2Cl2 and CHCl3 at different volume concentrations, we discussed the effect of the weak hydrogen bond formation on the FR and the asymmetric wavenumber shift phenomenon of the Fermi doublet ν1 and 2ν2 of CS2.

  14. The effect of an anti-hydrogen bond on Fermi resonance: A Raman spectroscopic study of the Fermi doublet ν1-ν12 of liquid pyridine

    NASA Astrophysics Data System (ADS)

    Li, Dong-Fei; Gao, Shu-Qin; Sun, Cheng-Lin; Li, Zuo-Wei

    2012-08-01

    The effects of an anti-hydrogen bond on the ν1-ν12 Fermi resonance (FR) of pyridine are experimentally investigated by using Raman scattering spectroscopy. Three systems, pyridine/water, pyridine/formamide, and pyridine/carbon tetrachloride, provide varying degrees of strength for the diluent-pyridine anti-hydrogen bond complex. Water forms a stronger anti-hydrogen bond with pyridine than with formamide, and in the case of adding non-polar solvent carbon tetrachloride, which is neither a hydrogen bond donor nor an acceptor and incapable of forming a hydrogen bond with pyridine, the intermolecular distance of pyridine will increase and the interaction of pyridine molecules will reduce. The dilution studies are performed on the three systems. Comparing with the values of the Fermi coupling coefficient W of the ring breathing mode ν1 and triangle mode ν12 of pyridine at different volume concentrations, which are calculated according to the Bertran equations, in three systems, we find that the solution with the strongest anti-hydrogen bond, water, shows the fastest change in the ν1-ν12 Fermi coupling coefficient W with the volume concentration varying, followed by the formamide and carbon tetrachloride solutions. These results suggest that the stronger anti-hydrogen bond-forming effect will cause a greater reduction in the strength of the ν1-ν12 FR of pyridine. According to the mechanism of the formation of an anti-hydrogen bond in the complexes and the FR theory, a qualitative explanation for the anti-hydrogen bond effect in reducing the strength of the ν1-ν12 FR of pyridine is given.

  15. Vibrational Energy Relaxation of Thiocyanate Ions in Liquid-to-Supercritical Light and Heavy Water. A Fermi's Golden Rule Analysis.

    PubMed

    Czurlok, Denis; Gleim, Jeannine; Lindner, Jörg; Vöhringer, Peter

    2014-10-01

    The vibrational relaxation dynamics following an ultrafast nitrile stretching (ν3) excitation of thiocyanate anions dissolved in light and heavy water have been studied over a wide temperature and density range corresponding to the aqueous liquid up to the supercritical phase. In both solvents, the relaxation of the ν3 = 1 state of the anion leads to a direct recovery of the vibrational ground state and involves the resonant transfer of the excess vibrational energy onto the solvent. In light water, the energy-accepting states are provided by the bending-librational combination band (νb + νL), while in heavy water, the relaxation is thermally assisted by virtual acceptor states derived from the stretching-librational/restricted translational hot band (νS - νL,T). The relaxation rate is found to strictly obey Fermi's Golden Rule when the density of resonant solvent states is estimated from the linear infrared spectra of the solute and the pure solvents. PMID:26278447

  16. From Hund's insulator to Fermi liquid: Optical spectroscopy study of K doping in BaMn2As2

    NASA Astrophysics Data System (ADS)

    McNally, D. E.; Zellman, S.; Yin, Z. P.; Post, K. W.; He, Hua; Hao, K.; Kotliar, G.; Basov, D.; Homes, C. C.; Aronson, M. C.

    2015-09-01

    We present optical transmission measurements that reveal a charge gap of 0.86 eV in the local-moment antiferromagnetic insulator BaMn2As2 , an order of magnitude larger than previously reported. Density functional theory plus dynamical mean-field theory (DFT+DMFT ) calculations correctly reproduce this charge gap only when a strong Hund's coupling is considered. Thus, BaMn2As2 is a member of a wider class of Mn pnictide compounds that are Mott-Hund insulators. We also present optical reflectance for metallic 2%-K-doped BaMn2As2 that we use to extract the optical conductivity at different temperatures. The optical conductivity σ1(ω ) exhibits a metallic response that is well described by a simple Drude term. Both σ (ω →0 ,T ) and ρ (T ) exhibit Fermi-liquid temperature dependencies. From these measurements, we argue that a more strongly correlated Hund-metal version of the parent compounds of the iron pnictide superconductors has not yet been realized by doping this class of Hund insulators.

  17. Quantum-dot lithium in zero magnetic field: Electronic properties, thermodynamics, and Fermi liquid-Wigner solid crossover in the ground state

    NASA Astrophysics Data System (ADS)

    Mikhailov, S. A.

    2002-03-01

    Energy spectra, electron densities, pair-correlation functions, and heat capacity of quantum-dot lithium in zero external magnetic field (a system of three interacting two-dimensional electrons in a parabolic confinement potential) are studied using the exact diagonalization approach. Particular attention is given to a Fermi liquid-Wigner solid crossover in the ground state of the dot, induced by intradot Coulomb interaction.

  18. Nonanalytic corrections to the specific heat and susceptibility of a two-dimensional Fermi liquid without Galilean invariance

    NASA Astrophysics Data System (ADS)

    Chubukov, Andrey V.; Millis, Andrew J.

    2006-09-01

    We consider the leading nonanalytic temperature dependence of the specific heat and temperature and momentum dependence of the spin susceptibility for two-dimensional fermionic systems with noncircular Fermi surfaces. We demonstrate the crucial role played by Fermi surface curvature. For a Fermi surface with inflection points, we demonstrate that thermal corrections to the uniform susceptibility in D=2 change from χs∝T to χs∝T2/3 for generic inflection points and to χs∝T1/2 for special inflection points along symmetry directions. Errors in previous work are corrected. An application of the results to Sr2RuO4 is given.

  19. Retreating behavior of a charged ionic liquid droplet in a dielectric liquid under electric field

    NASA Astrophysics Data System (ADS)

    Ahn, Myung Mo; Im, Do Jin; Kang, In Seok

    2013-11-01

    Ionic liquids show great promise as excellent solvents or catalysts in energy and biological fields due to their unique chemical and physical properties. The ionic liquid droplets in microfluidic systems can also be used as a potential platform for chemical biological reactions. In order to control electrically the ionic liquid droplets in a microfluidic device, the charging characteristics of ionic liquid droplets need to be understood. In this work, the charging characteristics of various ionic liquids are investigated by using the parallel plate electrodes system. Under normal situation, a charged droplet shows bouncing motion between electrodes continuously. However, for some special ionic liquids, interesting retreating behavior of charged ionic liquid droplet has been observed. This retreating behavior of ionic liquid droplet has been analyzed experimentally by the image analysis and the electrometer signal analysis. Based on the hypothesis of charge leakage of the retreating ionic liquid droplets, FT-IR spectroscopy analysis has also been performed. The retreating behavior of ionic liquid droplet is discussed from the intermolecular point of view according to the species of ionic liquids. This research was supported by grant No. 2013R1A1A2011956 funded by the Ministry of Science, ICT and Future Planning (MSIP) and by grant No. 2013R1A1A2010483 funded by the Ministry of Education, Science and Technology (MEST) through the NRF.

  20. Adaptation of the Landau-Migdal quasiparticle pattern to strongly correlated Fermi systems

    SciTech Connect

    Khodel, V. A.; Clark, J. W.; Zverev, M. V.

    2011-09-15

    A quasiparticle pattern advanced in Landau's first article on Fermi-liquid theory is adapted to elucidate the properties of a class of strongly correlated Fermi systems characterized by a Lifshitz phase diagram featuring a quantum critical point (QCP) where the density of states diverges. The necessary condition for stability of the Landau Fermi-Liquid state is shown to break down in such systems, triggering a cascade of topological phase transitions that lead, without symmetry violation, to states with multi-connected Fermi surfaces. The end point of this evolution is found to be an exceptional state whose spectrum of single-particle excitations exhibits a completely flat portion at zero temperature. Analysis of the evolution of the temperature dependence of the single-particle spectrum yields results that provide a natural explanation of classical behavior of this class of Fermi systems in the QCP region.

  1. Evaporative Mass Transfer Behavior of a Complex Immiscible Liquid

    PubMed Central

    McColl, Colleen M.; Johnson, Gwynn R.; Brusseau, Mark L.

    2010-01-01

    A series of laboratory experiments was conducted with a multiple-component immiscible liquid, collected from the Picillo Farm Superfund Site in Rhode Island, to examine liquid-vapor mass-transfer behavior. The immiscible liquid, which comprises solvents, oils, pesticides, PCBs, paint sludges, explosives, and other compounds, was characterized using gas chromatography and gas chromatography/mass spectrometry to determine mole fractions of selected constituents. Batch experiments were conducted to evaluate equilibrium phase-partitioning behavior. Two sets of air-stripping column studies were conducted to examine the mass-transfer dynamics of five selected target compounds present in the immiscible-liquid mixture. One set of column experiments was designed to represent a system with free-phase immiscible liquid present; the other was designed to represent a system with a residual phase of immiscible liquid. Initial elution behavior of all target components generally appeared to be ideal for both systems, as the initial vapor-phase concentrations were similar to vapor-phase concentrations measured for the batch experiment and those estimated using Raoult’s law (incorporating the immiscible-liquid composition data). Later-stage removal of 1,2-dichlorobenzene appeared to be rate limited for the columns containing free-phase immiscible liquid and no porous medium. Conversely, evaporative mass transfer appeared to be ideal throughout the experiment conducted with immiscible liquid distributed relatively uniformly as a residual phase within a sandy porous medium. PMID:18614196

  2. Quantum Critical Behavior of the Bose-Fermi Kondo Model with Ising Anisotropy

    NASA Astrophysics Data System (ADS)

    Park, Tae-Ho

    2005-03-01

    The existence of a continous quantum phase transition of the Bose-Fermi Kondo Model (BFKM) with a self-consistently determined bosonic bath has been demonstrated within the Extended Dynamical Mean Field Approach to the anisotropic Kondo lattice model and φ/T-scaling near the quantum critical point(QCP)was found[1,2]. We study the quantum critical properties of the anisotropic BFKM with specified bath spectral function, where the spectrum of the bosonic bath vanishes in a power-law fashion with exponent γ for small frequencies. Motivated by very recent results that the quantum to classical mapping for a related class of models fails[3,4]. We determine the critical local susceptibility using both the classical and quantum Monte Carlo approaches of Ref.5. Our results cover several values of γ below and above the upper critical dimension of the classical model for temperatures down to 1% of the bare Kondo scale. [1]D. Grempel and Q. Si, Phys. Rev. Lett. 91, 026402 (2003). [2]J.Zhu, D. Grempel, and Q. Si, Phys. Rev. Lett. 91, 156404 (2003). [3]L. Zhu, S. Kirchner, Q. Si nad A. Georges, Phys. Rev. Lett. in press (cond-mat/0406293). [4]M. Vojta, N. Tong, and R. Bulla, cond-mat/0410132. [5]D. Grempel and M. Rozenberg, Phys. Rev. B 60, 4702 (1999).

  3. Thermal behaviors of liquid La-based bulk metallic glasses

    SciTech Connect

    Zhang, D. W.; Wang, X. D. E-mail: jiangjz@zju.edu.cn; Lou, H. B.; Cao, Q. P.; Jiang, J. Z. E-mail: jiangjz@zju.edu.cn; Wang, L. W.; Zhang, D. X.

    2014-12-14

    Thermal behaviors of liquid La-based bulk metallic glasses have been measured by using the dilatometer with a self-sealed sample cell. It is demonstrated that the strong glass forming liquid not only has the small thermal expansion coefficient but also shows the slow variation rate. Moreover, the strong glass former has relatively dense atomic packing and also small density change in the liquid state. The results suggest that the high glass forming ability of La-based metallic glasses would be closely related to the slow atomic rearrangements in liquid melts.

  4. Thermal behaviors of liquid La-based bulk metallic glasses

    NASA Astrophysics Data System (ADS)

    Zhang, D. W.; Wang, X. D.; Lou, H. B.; Cao, Q. P.; Wang, L. W.; Zhang, D. X.; Jiang, J. Z.

    2014-12-01

    Thermal behaviors of liquid La-based bulk metallic glasses have been measured by using the dilatometer with a self-sealed sample cell. It is demonstrated that the strong glass forming liquid not only has the small thermal expansion coefficient but also shows the slow variation rate. Moreover, the strong glass former has relatively dense atomic packing and also small density change in the liquid state. The results suggest that the high glass forming ability of La-based metallic glasses would be closely related to the slow atomic rearrangements in liquid melts.

  5. A fermi liquid electric structure and the nature of the carriers in high-T/sub c/ cuprates: A photoemission study

    SciTech Connect

    Arko, A.J.; List, R.S.; Bartlett, R.J.; Cheong, S.W.; Fisk, Z.; Thompson, J.D.; Olson, C.G.; Yang, A.B.; Liu, R.; Gu, C.; Veal, B.W.; Liu, J.Z.; Paulikas, A.P.; Vandervoort, K.; Claus, H.; Campuzano, J.C.; Schirber, J.E.; Shinn, N.D.

    1989-01-01

    We have performed angle-integrated and angle-resolved photoemission measurements at 20 K on well-characterized single crystals of high-T/sub c/ cuprates (both 1:2:3-type and 2:2:1:2-type) cleaved in situ, and find a relatively large, resolution limited Fermi edge which shows large amplitude variations with photon energy, indicative of band structure final state effects. The lineshapes of the spectra of the 1:2:3 materials as a function of photon energy are well reproduced by band structure predictions, indicating a correct mix of 2p and 3d orbitals on the calculations, while the energy positions of the peaks agree with calculated bands only to within /approx/0.5 eV. This may yet prove to reflect the effects of Coulomb correlation. We nevertheless conclude that a Fermi liquid approach to conductivity is appropriate. Angle-resolved data, while still incomplete, suggest agreement with the Fermi surface predicted by the LDA calculations. A BCS-like energy gap is observed in the 2:2:1:2 materials, whose magnitude is twice the weak coupling BCS value (i.e., 2/Delta/ = 7 KT/sub c/). 49 refs., 11 figs.

  6. Universal high-momentum behaviors and thermodynamic relations in a spinless Fermi gas with a resonant p-wave interaction

    NASA Astrophysics Data System (ADS)

    Yoshida, Shuhei M.; Ueda, Masahito

    2015-05-01

    A series of universal relations, which include high-momentum or short-range behaviors of correlation functions and thermodynamic relations, have attracted great attention, especially in studies of the unitary regime of the BCS-BEC crossover. So far, most studies of the universal relations have been conducted within the regime in which a contact interaction model and a local effective field theoretical approach are available. What remains elusive is a spinless Fermi gas with a resonant p-wave interaction, in which a strong singularity due to the centrifugal barrier precludes a contact interaction description. We study high-momentum or short-range behaviors in such a gas and show several relations which are insensitive to its short-range details. We find universal asymptotes in the momentum distribution and the density correlation function, which originate from the two-body collisions. We also find a common coefficient on them which we call a p-wave contact and discuss its physical interpretation. We show that the p-wave contact is proportional to the number of closed-channel molecules, and derive an adiabatic sweep theorem, which states that the p-wave contact is the adiabatic derivative of the energy with respect to the scattering volume.

  7. Behavior of liquid hydrogen inside an ICF target

    NASA Technical Reports Server (NTRS)

    Kim, K.; Mok, L.; Bernat, T.

    1982-01-01

    The configuration of liquid hydrogen inside spherical glass shell ICF target was studied both theoretically and experimentally. Because of the zero contact angle between the .D2 liquid and glass substrate and the limited wetting surface that is continuous, the liquid hydrogen completely covers the interior of the glass shell, resulting in the formation of a void at the center. For this reason, the present problem distinguishes itself from that for a sessile drop sitting on a flat surface. A theory was formulated to calculate the liquid hydrogen configuration by including the London-dispersion force between the liquid and the substrate molecules. The net result is an augmented Bashforth-Adams equation appropriate to a spherical substrate, which is considered to be the major contribution of the present work. Preliminary calculations indicate that this equation accurately models the liquid hydrogen behavior inside a spherical microshell.

  8. Nearly ferromagnetic Fermi-liquid behaviour in YFe2Zn20 and high-temperature ferromagnetism of GdFe2Zn20

    NASA Astrophysics Data System (ADS)

    Jia, S.; Bud'Ko, S. L.; Samolyuk, G. D.; Canfield, P. C.

    2007-05-01

    One of the historic goals of alchemy was to turn base elements into precious ones. Although the practice of alchemy has been superseded by chemistry and solid-state physics, the desire to dramatically change or tune the properties of a compound, preferably through small changes in stoichiometry or composition, remains. This desire becomes even more compelling for compounds that can be tuned to extremes in behaviour. Here, we report that the RT2Zn20 (R=rare earth and T=transition metal) family of compounds manifests exactly this type of versatility, even though they are more than 85% Zn. By tuning T, we find that YFe2Zn20 is closer to ferromagnetism than elemental Pd, the classic example of a nearly ferromagnetic Fermi liquid. By submerging Gd in this highly polarizable Fermi liquid, we tune the system to a remarkably high-temperature ferromagnetic (TC=86K) state for a compound with less than 5% Gd. Although this is not quite turning lead into gold, it is essentially tuning Zn to become a variety of model compounds.

  9. Low-energy physics of the t -J model in d =∞ using extremely correlated Fermi liquid theory: Cutoff second-order equations

    NASA Astrophysics Data System (ADS)

    Shastry, B. Sriram; Perepelitsky, Edward

    2016-07-01

    We present the results for the low-energy properties of the infinite-dimensional t -J model with J =0 , using O (λ2) equations of the extremely correlated Fermi liquid formalism. The parameter λ ∈[0 ,1 ] is analogous to the inverse spin parameter 1 /(2 S ) in quantum magnets. The present analytical scheme allows us to approach the physically most interesting regime near the Mott insulating state n ≲1 . It overcomes the limitation to low densities n ≲0.7 of earlier calculations, by employing a variant of the skeleton graph expansion, and a high-frequency cutoff that is essential for maintaining the known high-T entropy. The resulting quasiparticle weight Z , the low ω ,T self-energy, and the resistivity are reported. These are quite close at all densities to the exact numerical results of the U =∞ Hubbard model, obtained using the dynamical mean field theory. The present calculation offers the advantage of generalizing to finite T rather easily, and allows the visualization of the loss of coherence of Fermi liquid quasiparticles by raising T . The present scheme is generalizable to finite dimensions and a nonvanishing J .

  10. Stability of Fermi surfaces and K theory.

    PubMed

    Horava, Petr

    2005-07-01

    Nonrelativistic Fermi liquids in d+1 dimensions exhibit generalized Fermi surfaces: (d-p)-dimensional submanifolds in the (k,omega)-space supporting gapless excitations. We show that the universality classes of stable Fermi surfaces are classified by K theory, with the pattern of stability determined by Bott periodicity. The Atiyah-Bott-Shapiro construction implies that the low-energy modes near a Fermi surface exhibit relativistic invariance in the transverse p+1 dimensions. This suggests an intriguing parallel between nonrelativistic Fermi liquids and D-branes of string theory. PMID:16090638

  11. Phase Behavior of Perturbed Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Kralj, S.; Kutnjak, Z.; Lahajnar, G.; Svetec, M.

    We study theoretically the combined effect of confinement and randomness on LC phase transitions in orientational (isotropic-nematic) and translational (nematic-smectic A) degrees of ordering. We focus to cases where these transitions are of (very) weakly 1st order. An adequate experimental realisation is, e.g., 8CB liquid crystal confined to a Controlled-Pore Glass matrix. Based on universal responses of "hard" and "soft" continuum fields to distortions we derive how different mechanisms influence qualitative and quantitative characteristics of phase transitions under consideration.

  12. Effect of liquid viscosity on wave behavior in gas-liquid two-phase flow

    SciTech Connect

    Kondo, Yoshiyuki; Mori, Koji; Yagishita, Takuya; Nakabo, Akinobu

    1999-07-01

    Measurements of time-spatial distributions of liquid holdups for the vertical upward gas-liquid two-phase flow were carried out by using the supermultiple cross-sectional mean liquid holdup probes (S-CHOP) and the semi-supermultiple point-electrode probes (SS-PEP) in the wide range of superficial gas and liquid velocity, j{sub g} and j{sub {ell}}, and the liquid kinematic viscosities were {nu}{sub {ell}} = 1 x 10{sup {minus}6}, 10 x 10{sup {minus}6} and 20 x 10{sup {minus}6} m{sup 1}/s. The time-spatial maps of wave behavior and the interfacial profiles were presented. Close inspection of these results reveals that there also exist huge waves and disturbance waves in the higher liquid viscosity conditions. To clarify the characteristics of these waves, the wave-vein analysis and the cluster analysis by K-mean algorithm were applied. These methods distinguished huge wave and disturbance wave objectively. The appearance regions of liquid slug, huge wave, and disturbance wave for each liquid viscosity condition were presented and the effects of liquid viscosity on them were discussed. Furthermore, velocity, width and height of these waves were determined, and the effects of liquid viscosity on them were clarified.

  13. Remembering Fermi

    SciTech Connect

    Cronin, James

    2005-03-30

    A combination of the discovery of nuclear fission and the circumstances of the 2nd World War brought Enrico Fermi to Chicago, where he led the team that produced the first controlled, self-sustained nuclear chain reaction. Following the war in 1945 Chancellor Hutchins, William Zachariasen, and Walter Bartky convinced Fermi to accept a professorship at the University of Chicago, where the Institute for Nuclear Studies was established. Fermi served as the leading figure in surely the greatest collection of scientists the world has ever seen. Fermi's tenure at Chicago was cut short by his death in 1954. My talk will concentrate on the years 1945-54. Examples of his research notebooks, his speeches, his teaching, and his correspondence will be discussed.

  14. Unconventional Fermi surface in an insulating state

    SciTech Connect

    Harrison, Neil; Tan, B. S.; Hsu, Y. -T.; Zeng, B.; Hatnean, M. Ciomaga; Zhu, Z.; Hartstein, M.; Kiourlappou, M.; Srivastava, A.; Johannes, M. D.; Murphy, T. P.; Park, J. -H.; Balicas, L.; Lonzarich, G. G.; Balakrishnan, G.; Sebastian, Suchitra E.

    2015-07-17

    Insulators occur in more than one guise; a recent finding was a class of topological insulators, which host a conducting surface juxtaposed with an insulating bulk. Here, we report the observation of an unusual insulating state with an electrically insulating bulk that simultaneously yields bulk quantum oscillations with characteristics of an unconventional Fermi liquid. We present quantum oscillation measurements of magnetic torque in high-purity single crystals of the Kondo insulator SmB6, which reveal quantum oscillation frequencies characteristic of a large three-dimensional conduction electron Fermi surface similar to the metallic rare earth hexaborides such as PrB6 and LaB6. As a result, the quantum oscillation amplitude strongly increases at low temperatures, appearing strikingly at variance with conventional metallic behavior.

  15. Behavior of supercooled aqueous solutions stemming from hidden liquid-liquid transition in water

    NASA Astrophysics Data System (ADS)

    Biddle, John W.; Holten, Vincent; Anisimov, Mikhail A.

    2014-08-01

    A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid-liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid-liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H2O-NaCl and H2O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archer and Carter [J. Phys. Chem. B 104, 8563 (2000)], to be consistent with the presence of the metastable liquid-liquid transition. We elucidate the non-conserved nature of the order parameter (extent of "reaction" between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases.

  16. Behavior of supercooled aqueous solutions stemming from hidden liquid-liquid transition in water.

    PubMed

    Biddle, John W; Holten, Vincent; Anisimov, Mikhail A

    2014-08-21

    A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid-liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid-liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H2O-NaCl and H2O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archer and Carter [J. Phys. Chem. B 104, 8563 (2000)], to be consistent with the presence of the metastable liquid-liquid transition. We elucidate the non-conserved nature of the order parameter (extent of "reaction" between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases. PMID:25149798

  17. Individual behavior and pairwise interactions between microswimmers in anisotropic liquid

    NASA Astrophysics Data System (ADS)

    Sokolov, Andrey; Zhou, Shuang; Lavrentovich, Oleg D.; Aranson, Igor S.

    2015-01-01

    A motile bacterium swims by generating flow in its surrounding liquid. Anisotropy of the suspending liquid significantly modifies the swimming dynamics and corresponding flow signatures of an individual bacterium and impacts collective behavior. We study the interactions between swimming bacteria in an anisotropic environment exemplified by lyotropic chromonic liquid crystal. Our analysis reveals a significant localization of the bacteria-induced flow along a line coaxial with the bacterial body, which is due to strong viscosity anisotropy of the liquid crystal. Despite the fact that the average viscosity of the liquid crystal is two to three orders of magnitude higher than the viscosity of pure water, the speed of bacteria in the liquid crystal is of the same order of magnitude as in water. We show that bacteria can transport a cargo (a fluorescent particle) along a predetermined trajectory defined by the direction of molecular orientation of the liquid crystal. We demonstrate that while the hydrodynamic interaction between flagella of two close-by bacteria is negligible, the observed convergence of the swimming speeds as well as flagella waves' phase velocities may occur due to viscoelastic interaction between the bacterial bodies.

  18. Application of antiferromagnetic-Fermi-liquid theory to NMR experiments in La1.85Sr0.15CuO4

    NASA Astrophysics Data System (ADS)

    Monien, H.; Monthoux, P.; Pines, D.

    1991-01-01

    NMR experiments on La1.85Sr0.15CuO4 by Kitaoka et al. and Imai et al. are analyzed using the phenomenological antiferromagnetic (AF) Fermi liquid theory of Millis, Monien, and Pines, and the results are compared with those previously obtained for YBa2Cu3O7 and YBa2Cu3O6.63. A one-component model, with hyperfine couplings that are unchanged from those found previously for YBa2Cu3O7 and YBa2Cu3O6.63, and parameters obtained from experiment, provide a quantitative fit to the data. At all temperatures the antiferromagnetic correlations found in La1.85Sr0.15CuO4 are stronger than those found for the Y-Ba-Cu-O samples with the result that the characteristic energy for the antiferromagnetic paramagnons that describe the AF spin dynamics is quite low (Fermi liquid are genuinely novel, and suggest that both the spin and charge aspects of the normal-state properties of the cuprate oxide superconductors can be quantitatively explained in terms of quasiparticles coupled to antiferromagnetic paramagnons whose characteristic energy scale is

  19. Corrosion behavior of surface treated steel in liquid sodium negative electrode of liquid metal battery

    NASA Astrophysics Data System (ADS)

    Lee, Jeonghyeon; Shin, Sang Hun; Lee, Jung Ki; Choi, Sungyeol; Kim, Ji Hyun

    2016-03-01

    While liquid metal batteries are attractive options for grid-scale energy storage applications as they have flexible siting capacities and small footprints, the compatibility between structural materials such as current collectors and negative electrode such as sodium is one of major issues for liquid metal batteries. Non-metallic elements such as carbon, oxygen, and nitrogen in the liquid sodium influence the material behaviors of the cell construction materials in the battery system. In this study, the compatibility of structural materials with sodium is investigated in high temperature liquid sodium, and electrochemical impedance spectroscopy (EIS) is used to monitor in-situ the corrosion behavior at the surface of materials in sodium. Chemical vapor deposition (CVD) coatings of SiC and Si3N4 are applied as protective barriers against dissolution and corrosion on the steel surface. The results show that CVD coating of Si compounds can delay corrosion of steel in high temperature liquid sodium comparing to the result of as-received specimens, while SiC coating is more durable than Si3N4 coating in high temperature liquid sodium.

  20. Bioinspired One-Dimensional Nano-Wrinkles Guide Liquid Behaviors at the Liquid-Solid Interfaces.

    PubMed

    Li, Jing; Sun, Quanmei; Chen, Long; Feng, Jiantao; Han, Dong

    2016-01-01

    Learning from nature concerning how nanostructured surfaces interact with liquids may provide insight into better understanding of inside living biological interfaces bearing these nanostructures and further development of innovative materials contacting water. Here we investigate the dynamic behaviour of water droplet interacting with one-dimensional nano-wrinkles of different size on polydimethylsiloxane (PDMS) surface. The structure design of the variationally one-dimensional nano-wrinkles is inspired by in vivo responding topographic changes in aortic intima, which was characterized with liquid-phase atomic force microscopy. We show here that increasing the amplitude of the wrinkles promotes the spreading and energy dissipation of liquid droplets on the wrinkled interfaces. This result suggests a possible bio-protection mechanism of blood vessels via its structural changes on the aortic intima against elevated flowing blood, and provides a basis for tuning interfacial nanostructure of optimal durability against wearing by the liquid behaviors. PMID:27398541

  1. Phase behavior and local structure of liquid crystalline polymers

    NASA Astrophysics Data System (ADS)

    Fynewever, Herb

    In this work we use a combination of theory and computer simulation to study the phase behavior of liquid crystalline polymers and the local structure of polymer melts. We review experimental and simulation evidence which shows that long and stiff molecules form orientationally ordered phases at packing fractions intermediate between the liquid and the solid. With the aid of a two-molecule simulation, we are able to apply Onsager's theory [Ann. N. Y. Acad. Sci. 51, 627 (1949)] for liquid crystal formation to flexible molecules without any additional approximations. Our results have a quantitative advantage over other theories in comparison with computer simulation data such as for the liquid-liquid crystal phase diagram. We also study the local structure of polymer melts using a two-molecule simulation to apply the density functional theories of Donley, Curro, and McCoy [J. Chem. Phys. 101 , 3205 (1994)1; and Yethiraj and Woodward [J. Chem. Phys 102 , 5499 (1995)]. The accuracy of these methods rivals that of integral equation theories in their predictions of local order. Further, the two-molecule simulation facilitates a more direct calculation of the equation of state via the monitoring of orientational correlations.

  2. Solid-liquid critical behavior of water in nanopores.

    PubMed

    Mochizuki, Kenji; Koga, Kenichiro

    2015-07-01

    Nanoconfined liquid water can transform into low-dimensional ices whose crystalline structures are dissimilar to any bulk ices and whose melting point may significantly rise with reducing the pore size, as revealed by computer simulation and confirmed by experiment. One of the intriguing, and as yet unresolved, questions concerns the observation that the liquid water may transform into a low-dimensional ice either via a first-order phase change or without any discontinuity in thermodynamic and dynamic properties, which suggests the existence of solid-liquid critical points in this class of nanoconfined systems. Here we explore the phase behavior of a model of water in carbon nanotubes in the temperature-pressure-diameter space by molecular dynamics simulation and provide unambiguous evidence to support solid-liquid critical phenomena of nanoconfined water. Solid-liquid first-order phase boundaries are determined by tracing spontaneous phase separation at various temperatures. All of the boundaries eventually cease to exist at the critical points and there appear loci of response function maxima, or the Widom lines, extending to the supercritical region. The finite-size scaling analysis of the density distribution supports the presence of both first-order and continuous phase changes between solid and liquid. At around the Widom line, there are microscopic domains of two phases, and continuous solid-liquid phase changes occur in such a way that the domains of one phase grow and those of the other evanesce as the thermodynamic state departs from the Widom line. PMID:26100904

  3. Solid−liquid critical behavior of water in nanopores

    PubMed Central

    Mochizuki, Kenji; Koga, Kenichiro

    2015-01-01

    Nanoconfined liquid water can transform into low-dimensional ices whose crystalline structures are dissimilar to any bulk ices and whose melting point may significantly rise with reducing the pore size, as revealed by computer simulation and confirmed by experiment. One of the intriguing, and as yet unresolved, questions concerns the observation that the liquid water may transform into a low-dimensional ice either via a first-order phase change or without any discontinuity in thermodynamic and dynamic properties, which suggests the existence of solid−liquid critical points in this class of nanoconfined systems. Here we explore the phase behavior of a model of water in carbon nanotubes in the temperature−pressure−diameter space by molecular dynamics simulation and provide unambiguous evidence to support solid−liquid critical phenomena of nanoconfined water. Solid−liquid first-order phase boundaries are determined by tracing spontaneous phase separation at various temperatures. All of the boundaries eventually cease to exist at the critical points and there appear loci of response function maxima, or the Widom lines, extending to the supercritical region. The finite-size scaling analysis of the density distribution supports the presence of both first-order and continuous phase changes between solid and liquid. At around the Widom line, there are microscopic domains of two phases, and continuous solid−liquid phase changes occur in such a way that the domains of one phase grow and those of the other evanesce as the thermodynamic state departs from the Widom line. PMID:26100904

  4. Phase Behavior and Collective Dynamics of Liquid Water

    NASA Astrophysics Data System (ADS)

    Sastry, Srikanth

    The unusual properties of liquid water have been analyzed predominantly in terms of the hydrogen bond network which characterizes its microscopic structure. Properties of the hydrogen bond network, with physically motivated additional assumptions, have been shown to describe well most static and dynamic properties of water. However, there are important exceptions where no conclusive analysis in terms of the hydrogen bond network has been carried out. Two such exceptions are addressed in this thesis. The phase behaviour of water--in particular the limiting behavior of the metastable continuations of the liquid--is an open question. To explain the apparent divergence of many thermodynamic and microscopic quantities on supercooling, Speedy and Angell proposed that these divergences are due to an absolute limit of stability of the liquid phase, conjecturing further that such limits of stability form a continuous reentrant locus in the P-T plane. In an attempt to address this conjecture on the basis of microscopic behavior in water, a lattice gas model is developed, which exhibits water-like behavior and has phases corresponding to the real system. The liquid gas spinodal is seen to be reentrant, in accordance with the stability limit conjecture. However, the limit of stability upon supercooling in the model, while consistent with experiments, is found to differ qualitatively from the prediction, displaying no singular behavior of thermodynamic quantities. In computer and experimental studies of sound propagation in water at high wavenumbers, the sound velocity is found to be about twice the hydrodynamic value. It was proposed that this mode propagates on the hydrogen bond network and occurs due to the connectivity properties of the network. This question is studied through Molecular Dynamics simulations of the liquid and normal model analysis of inherent structures. The results show that only one longitudinal sound mode is present. However, an attempt is made to go

  5. Statistical mechanics of light elements at high pressure. VI - Liquid-state calculations with Thomas-Fermi-Dirac theory

    NASA Technical Reports Server (NTRS)

    Macfarlane, J. J.

    1984-01-01

    A model free energy is developed for hydrogen-helium mixtures based on solid-state Thomas-Fermi-Dirac calculations at pressures relevant to the interiors of giant planets. Using a model potential similar to that for a two-component plasma, effective charges for the nuclei (which are in general smaller than the actual charges because of screening effects) are parameterized, being constrained by calculations at a number of densities, compositions, and lattice structures. These model potentials are then used to compute the equilibrium properties of H-He fluids using a charged hard-sphere model. The results find critical temperatures of about 0 K, 500 K, and 1500 K, for pressures of 10, 100, and 1000 Mbar, respectively. These phase separation temperatures are considerably lower (approximately 6,000-10,000 K) than those found from calculations using free electron perturbation theory, and suggest that H-He solutions should be stable against phase separation in the metallic zones of Jupiter and Saturn.

  6. Liquid-vapor critical behavior in silica aerogel

    NASA Astrophysics Data System (ADS)

    Herman, Tobias Kent

    Fluids in porous media provide a testing ground for the effects of disorder and confinement on phase transitions and critical phenomena. Specifically, highly porous silica aerogel with its tenuous solid structure has allowed low temperature physicists to probe the effect of dilute fixed impurities on both the 4He superfluid transition and the 3He superfluid transition. Both systems have yielded exciting results and work is ongoing, especially on 3He in aerogel. This thesis explores the effect of aerogel on another transition---the liquid-vapor transition near the liquid-vapor critical point. In dense porous media, the liquid-vapor transition is usually described as capillary condensation---a process which assigns surface tension a primary role in determining the thermodynamic state of the system. However, aerogels are often so diffuse (less than 5% silica by volume---the rest is open space) that it becomes difficult to speak of pore size and meniscus shape as one would in a denser porous medium. As one approaches the liquid-vapor critical point, thermal fluctuations within the fluid grow until they exceed the scale of the aerogel strands and pores themselves. In this regime one cannot expect surface tension to control the thermodynamics of the system---it is instead in a regime where thermal fluctuations may govern its behavior. In the past there were even suggestions that the addition of aerogel might shift the character of the transition into another universality class. The following chapters present data collected on helium and neon in aerogel near their respective liquid-vapor critical points. While the behavior of the fluid at low temperatures is consistent with the pictures provided by capillary condensation, closer to the critical point they are incompatible and remain somewhat unexplained. Evidence for a shift in universality class was not found---in fact there was very little evidence for a macroscopic equilibrium transition of any type.

  7. New phase boundary between magnetic and non-Fermi-liquid in Ce(Rh1-xRux)3B2, for 0⩽x⩽0.4

    NASA Astrophysics Data System (ADS)

    Bauer, E.; Hauser, R.; Galatanu, A.; Lindbaum, A.; Hilscher, G.; Sassik, H.; Kirchmayr, H.; Sereni, J. G.; Rogl, P.

    1998-06-01

    A study of the temperature-dependent magnetic susceptibility and electrical resistivity ρ(T) (0.5-300 K) on single-phase alloys (CaCu5 type), prepared by argon arc melting, reveals a magnetic phase transition with a nonmonotonous decrease of the ordering temperature from Tc=115 K for x=0 to Tc≈0 for x=0.40. A kink in the susceptibility at about 70 K indicates that ferromagnetism (at x<0.1) transforms to a complex magnetic order for 0.125⩽x⩽0.35. Above that concentration ρ(T)=ρ0+ATn changes from n≈2 to n≈1.5, a characteristic for non-Fermi-liquid behavior. Under pressure Tc stays almost constant for x=0.125 but dTc/dp grows with increasing Ru content. On the contrary, applied fields up to 12 T do not affect Tc. Low-temperature specific heat and ac susceptibility for x=0.40 confirm the absence of long-range magnetic order down to 0.5 K. For x=0.35 Cp/T=62 mJ/mol K at 1.5 K, a value which is three times larger than that of CeRh3B2.

  8. Fermi questions

    NASA Astrophysics Data System (ADS)

    Bouffard, Karen

    1999-05-01

    This column contains problems and solutions for the general category of questions known as "Fermi" questions. Forcing the students to use their ability to estimate, giving answers in terms of order-of-magnitude, is not only a challenge for a competition, but a teaching strategy to use in the classroom to develop self-confidence and the ability to analyze answers as to whether or not they make sense, as opposed to relying on the "precision" of a calculator value.

  9. Enrico Fermi

    NASA Astrophysics Data System (ADS)

    Yang, Chen Ning

    2013-05-01

    Enrico Fermi was, of all the great physicists of the 20th century, among the most respected and admired. He was respected and admired because of his contributions to both theoretical and experimental physics, because of his leadership in discovering for mankind a powerful new source of energy, and above all, because of his personal character. He was always reliable and trustworthy. He had both of his feet on the ground all the time. He had great strength, but never threw his weight around. He did not play to the gallery. He did not practise one-up-manship. He exemplified, I always believe, the perfect Confucian gentleman...

  10. Comparison studies of rheological and thermal behaviors of ionic liquids and nanoparticle ionic liquids.

    PubMed

    Xu, Yiting; Zheng, Qiang; Song, Yihu

    2015-08-14

    Novel nanoparticle ionic liquids (NILs) are prepared by grafting modified nanoparticles with long-chain ionic liquids (ILs). The NIL behaves like a liquid at ambient temperature. We studied the rheological behavior of the IL and NIL over the range of 10-55 °C and found an extraordinary difference between the IL and NIL: a small content of nanosilica (7%) moderately improves the crystallinity by 7% of the poly(ethylene glycol) (PEG) segment in the IL, and it improves the dynamic moduli significantly (by 5 times at room temperature). It retards the decay temperature (by 10 °C) of the dynamic moduli during heating as well. The thermal rheological hysteresis observed during heating-cooling temperature sweeps is ascribed to the melting-recrystallization of the PEG segments. Meanwhile, the IL and NIL express accelerated crystallization behavior in comparison with the oligomeric anion. For the first time, we find that ILs and NILs are able to form nanoparticle-containing spherulites at room temperature after long time aging. PMID:26156247

  11. Simulations of Liquid III-V and II-VI Semiconductors: Semiconducting versus Metallic Behavior.

    NASA Astrophysics Data System (ADS)

    Godlevsky, V.

    2000-03-01

    All III-V group semiconductors exhibit metallic behavior when melted. The coordination number of these materials changes from 4 in the bulk to ~ 6 in the liquid phase. With the increase of the coordination number and compositional disorder common to liquid III-V semiconductors, the covalent bonds of these materials are predominantly replaced by metallic bonds. Electron delocalization and high atomic randomization result in a large entropy change during the solidarrowliquid transition. Unlike III-V compounds, a number of II-VI semiconductors (e.g. CdTe, ZnTe and HgS) experience a semiconductorarrowsemiconductor transition upon melting. These compounds retain their fourfold coordination in the liquid phase. In our work, we perform ab initio simulations of liquid GaAs (l-GaAs) and CdTe (l-CdTe), as representatives of III-V and II-VI materials.(V. Godlevsky, J. Derby, and J.R. Chelikowsky, Phys. Rev. Lett. 81), 4959 (1998) As opposed to the more close-packed l-GaAs, l-CdTe has an open fourfold structure. Besides the coordination number, l-CdTe also retains some of its crystalline compositional features (e.g. there are fewer ``wrong'' bond defects than in l-GaAs). In l-CdTe, the density of states has a dip at the Fermi level indicating the semiconducting character of electrical conductivity in this material. The d.c. conductivity in l-CdTe is by two orders of magnitude lower than that in l-GaAs. The small change in the structural order and electron delocalization is in good agreement with the small entropy change observed experimentally during the melting of CdTe. As the temperature increases further, l-CdTe undergoes a fourfold-sixfold transition accompanied by the disappearing of band gap. The d.c. conductivity of sixfold coordinated l-CdTe is by an order of magnitude larger than the d.c. conductivity of fourfold coordinated l-CdTe.(V. Godlevsky, M. Jain, J. Derby, and J.R. Chelikowsky, Phys. Rev. B, 60), 8640 (1999)

  12. Ultra-fast single-file transport of a simple liquid beyond the collective behavior zone.

    PubMed

    Su, Jiaye; Yang, Keda; Huang, Decai

    2016-07-27

    We use molecular dynamics simulations to analyze the single-file transport behavior of a simple liquid through a narrow membrane channel. With the decrease of the liquid-channel interaction, the liquid flow exhibits a remarkable maximum behavior owing to the competition of liquid-liquid and liquid-channel interactions. Surprisingly, this maximum flow is coupled to a sudden reduce of the liquid occupancy, where the liquid particle is moving through the channel alone at nearly constant velocity, rather than in a collective motion mode. Further investigation on the encountered energy barrier suggests that this maximum flow should be induced by particles having large instant velocities (or thermal fluctuation) that overcome the liquid-liquid and liquid-channel interaction barriers. Further decreasing the liquid-channel interaction leads to the decrease and ultimate stabilization of the liquid flow, since the energy barrier will increase and becomes steady. These results suggest that the breakdown of collective behavior can be a new rule for achieving fast single-file transportation, especially for simple or nonpolar liquids with relatively weak liquid-liquid interactions, and is thus helpful for the design of high flux nanofluidic devices. PMID:27460013

  13. Importance of Fermi energy for understanding the intermixing behavior at the LaAlO{sub 3}/SrTiO{sub 3} heterointerface

    SciTech Connect

    Yamamoto, Takashi; Mizoguchi, Teruyasu

    2014-11-17

    We investigated the migration energy and vacancy formation energy of La and Sr ions at a LaAlO{sub 3}/SrTiO{sub 3} heterointerface using first-principles calculations. Our study reveal that the migration energies at the p-type interface are lower than those at the n-type interface, and the formation energies of Sr and La vacancies are relatively high when we assume a reduction atmosphere and insulator conditions. To explain the experimental evidence that intermixing is preferentially taking place at the n-type interface, considering the Fermi energy is critical. We find that the presence of electron carriers plays an important role in the intermixing behaviors at the LaAlO{sub 3}/SrTiO{sub 3} heterointerface.

  14. Elastic response and phase behavior in binary liquid crystal mixtures.

    PubMed

    Sidky, Hythem; Whitmer, Jonathan K

    2016-05-11

    Utilizing density-of-states simulations, we perform a full mapping of the phase behavior and elastic responses of binary liquid crystalline mixtures represented by the multicomponent Lebwohl-Lasher model. Our techniques are able to characterize the complete phase diagram, including nematic-nematic phase separation predicted by mean-field theories, but previously not observed in simulations. Mapping this phase diagram permits detailed study of elastic properties across the miscible nematic region. Importantly, we observe for the first time local phase separation and disordering driven by the application of small linear perturbations near the transition temperature and more significantly through nonlinear stresses. These findings are of key importance in systems of blended nematics which contain particulate inclusions, or are otherwise confined. PMID:27093188

  15. Amphiphilic behavior of two phosphonium based ionic liquids.

    PubMed

    Mukherjee, Indrajyoti; Mukherjee, Suvasree; Naskar, Bappaditya; Ghosh, Soumen; Moulik, Satya P

    2013-04-01

    Solution and surface chemical behavior of two phosphonium based ionic liquids triisobutyl (methyl) phosphonium tosylate (IL-1) and trihexyl (tetradecyl) phosphonium bis 2,4,4-(trimethylpentyl)phosphinate (IL-2) have been studied. The polar IL-1 is surface active and water soluble, whereas the weakly polar IL-2 is more surface active with very low aqueous solubility. IL-1 does not form micelles but affects the micellization properties of ionic, nonionic, and zwitterionic surfactants more strongly than conventional electrolytes. IL-2 itself forms micelles and mixed micelles with Triton X-100 (TX-100) in aqueous solution. It also forms Langmuir monolayers of liquid expanded type, at the air/water interface. IL-1 can replace water in forming microemulsions with the oil isopropylmyristate (IPM), stabilized by IL-2 (surfactant)+isopropanol (IP as a co-surfactant) like the IL-1/IPM/(IL-2+IP) system. It produces a large monophasic zone in the pseudoternary phase diagram. The thermodynamics of formation of the microemulsions of IL-1 in oil (IPM) have been examined. The dimensions and the polydispersity of the dispersed nano-droplets in the microemulsions have been determined by DLS. The thermal stability of the microemulsion forming systems has also been studied. ILs studied against Sarcoma-180 cell lines have evidenced proficient anti-cancer activity of IL-1 and moderate activity of IL-2. PMID:23317771

  16. Critical behavior of liquid {sup 4}He at negative pressures

    SciTech Connect

    Campbell, C.E.; Folk, R.; Krotscheck, E.

    1996-10-01

    The authors examine the equation of state of liquid {sup 4}He at negative pressures close to the spinodal density {rho}{sub s} where the hydrodynamic speed of sound vanishes. The non-analytic behavior of the equation of state and the speed of sound in the vicinity of the spinodal density are calculated in two and in three dimensions; they find for the speed of sound the non-analytic behavior mc{sub s}{sup 2} {approximately} ({rho}-{rho}{sub s}){sup 2/5} in three dimensions and mc{sub s}{sup 2} {approximately} [({rho}-{rho}{sub s})/{vert_bar}ln({rho}-{rho}{sub s}){vert_bar}]{sup 1/2} in two dimensions. The authors then examine the low density regime numerically, using a semianalytic microscopic theory. It is found that non-analytic exponents are visible only in a negligible density regime around the spinodal point. Estimates for the spinodal densities, and the range of critical fluctations are provided.

  17. Spin transport in cold Fermi gases: A pseudogap interpretation of spin diffusion experiments at unitarity

    SciTech Connect

    Wulin, Dan; Levin, K.; Guo Hao; Chien, Chih-Chun

    2011-06-15

    We address recent spin transport experiments in ultracold unitary Fermi gases. We provide a theoretical understanding for how the measured temperature dependence of the spin diffusivity at low T can disagree with the expected behavior of a Fermi liquid (FL), while the spin susceptiblity, following the experimental protocols, is consistent with a FL picture. We show that the experimental protocols for extracting the spin susceptibility implicitly reflect a FL viewpoint; relaxing this leads to consistency within but not proof of a pseudogap-based theory. Our transport calculations yield insight into the observed suppression of the spin diffusion constant at lower T.

  18. Studies of Yttrium BARIUM(2) COPPER(3) OXYGEN(7 - Materials and Layered Thin Films: Their Growth and Interdiffusion Behavior, Fermi Edge Density, and the Oxygen Depletion Problem

    NASA Astrophysics Data System (ADS)

    Chen, Li-Mei

    In 1987, Paul Chu and his colleagues discovered the high-T_{c} YBa_2Cu_3O _{7-x} (1-2-3) superconductor (HTSC). The most important research still needed on this system from a scientific point of view is to get insight into the superconducting mechanism of this new material. Using these materials in the foof films seems the most realistic for widespread application. Therefore, research in this thesis on these HTSC materials have been carried out in four parts: (1) the oxygen depletion problem, (2) Fermi density of state, (3) interdiffusion behavior and (4) multilayer growth. HTSC thin films were successfully made by either ion beam deposition or R-F magnetron sputtering at the EIC Laboratory in Massachusetts. C-axis oriented epitaxial HTSC thin films were deposited onto MgO, YSZ and sapphire. A variety of different buffer layers were also deposited onto the above-mentioned substrates to try to effectuate the elimination the interaction between the substrates and the HTSC thin films. For further interdiffusion behavior studies, the above mentioned buffer layers were also deposited in a superconductor-insulator-superconductor (S-I-S) geometry. This geometry is one employed in Josephson junctions which are the key elements of superconductive electronics. We have also studied the behavior of select HTSC ceramic systems during changes in atmospheric conditions. A four-point probe was used to measure the HTSC ceramic transition temperature. From these results, we found that in the presence of an ambient oxygen background equivalent to several torr at room temperature, the HTSC materials produced a metallic R vs. T behavior with T_0 (onset) of ~103 K and T _{c} of ~ 91 K. Lowering the oxygen pressure, followed by repeated temperature cycling, produced a continuous reduction in T_{c} to value ~60 K. Reintroduction of various dose O_2 or air immediately increased the T_{c}, with apparent total restoration to the optimal resistance values at ~5 torr to 12 torr. A finite Fermi

  19. Nanostructuration Effect on the Thermal Behavior of Ionic Liquids.

    PubMed

    Rodrigues, Ana S M C; Santos, Luís M N B F

    2016-05-18

    This work shows how the nanostructuration of ionic liquids (ILs) governs the glass and melting transitions of the bistriflimide imidazolium-based [Cn C1 im][NTf2 ] and [Cn Cn im][NTf2 ] series, which highlights the trend shift that occurs at the critical alkyl size (CAS) of n=6. An initial increase in the glass temperature (Tg ) with an increase in the alkyl side chain was observed due to the intensification of the dispersive interactions (van der Waals). Above the CAS, the -CH2 - increment has the same effect in both glass and liquid states, which leads to a plateau in the glass transition after nanostructuration. The melting temperature (Tm ) of the [Cn C1 im][NTf2 ] and [Cn Cn im][NTf2 ] series presents a V-shaped profile. For the short-alkyl ILs, the -CH2 - increment affects the electrostatic ion pair interactions, which leads to an increase in the conformational entropy. The -CH2 - increment disturbs the packing ability of the ILs and leads to a higher entropy value (ΔslSm○ ) and consequently a decrease in Tm . Above the CAS, the -CH2 - contribution to the melting temperature becomes more regular, as a consequence of the nanostructuration of the IL into polar and nonpolar domains. The dependence of the alkyl chain on the temperature, enthalpy, and entropy of melting in the ILs above the CAS is very similar to the one observed for the alkane series, which highlights the importance of the nonpolar alkyl domains on the ILs thermal behavior. PMID:26888172

  20. Self-Associating Behavior of Acetone in Liquid Krypton.

    PubMed

    De Beuckeleer, Liene I; Herrebout, Wouter A

    2016-02-18

    Acetone molecules are inclined to self-associate through dipole-dipole interactions because of their large dipole moment. Infrared spectroscopy of compounds dissolved in liquid noble gases supported by high level ab initio calculations allows investigating the self-associating behavior and determining the thermodynamical properties. In this study, infrared spectra of various concentrations of acetone dissolved in liquid krypton are recorded at constant temperature. Overlapping monomer and dimer spectra are separated by analyzing the obtained data sets with numerical methods based on least-squares fitting. Although acetone is known to self-associate, only a few spectral features have been presented in literature before. In this study, the application of new numerical approaches succeeds in resolving overlapping spectra and allows observing isolated acetone dimer absorption bands for the complete mid infrared spectrum. By use of data sets of spectra recorded at temperatures between 134 and 142 K, the experimental standard dimerization enthalpy was determined to be -10.8 kJ mol(-1). MP2/aug-cc-pVDZ calculations predicted a stacked and planar dimer geometry of which the stacked geometry is more stable. Combining MP2 energies and single point corrections involving CCSD(T) calculations and complete basis set extrapolations based on the MP2/aug-cc-pVDZ equilibrium geometry lead to complexation energy of -28.4 kJ mol(-1) for the stacked geometry and -15.1 kJ mol(-1) for the planar geometry. The corresponding values for the complexation enthalpies in solution, obtained by combining these values with corrections for thermal and solvent influences are -13.7 and -5.8 kJ mol(-1). PMID:26805773

  1. Protein Phase Behavior in Aqueous Solutions: Crystallization, Liquid-Liquid Phase Separation, Gels, and Aggregates

    PubMed Central

    Dumetz, André C.; Chockla, Aaron M.; Kaler, Eric W.; Lenhoff, Abraham M.

    2008-01-01

    The aggregates and gels commonly observed during protein crystallization have generally been considered disordered phases without further characterization. Here their physical nature is addressed by investigating protein salting-out in ammonium sulfate and sodium chloride for six proteins (ovalbumin, ribonuclease A, soybean trypsin inhibitor, lysozyme, and β-lactoglobulin A and B) at 4°C, 23°C, and 37°C. When interpreted within the framework of a theoretical phase diagram obtained for colloidal particles displaying short-range attractive interactions, the results show that the formation of aggregates can be interpreted theoretically in terms of a gas-liquid phase separation for aggregates that are amorphous or gel-like. A notable additional feature is the existence of a second aggregation line observed for both ovalbumin and ribonuclease A in ammonium sulfate, interpreted theoretically as the spinodal. Further investigation of ovalbumin and lysozyme reveals that the formation of aggregates can be interpreted, in light of theoretical results from mode-coupling theory, as a kinetically trapped state or a gel phase that occurs through the intermediate of a gas-liquid phase separation. Despite the limitations of simple theoretical models of short-range attractive interactions, such as their inability to reproduce the effect of temperature, they provide a framework useful to describe the main features of protein phase behavior. PMID:18160663

  2. Phase behavior of lysozyme solutions in the liquid-liquid phase coexistence region at high hydrostatic pressures.

    PubMed

    Schulze, Julian; Möller, Johannes; Weine, Jonathan; Julius, Karin; König, Nico; Nase, Julia; Paulus, Michael; Tolan, Metin; Winter, Roland

    2016-05-25

    We present results from small-angle X-ray scattering and turbidity measurements on the effect of high hydrostatic pressure on the phase behavior of dense lysozyme solutions in the liquid-liquid phase separation region, and characterize the underlying intermolecular protein-protein interactions as a function of temperature and pressure under charge-screening conditions (0.5 M NaCl). A reentrant liquid-liquid phase separation region is observed at elevated pressures, which may originate in the pressure dependence of the solvent-mediated protein-protein interaction. A temperature-pressure-concentration phase diagram was constructed for highly concentrated lysozyme solutions over a wide range of temperatures, pressures and protein concentrations including the critical region of the liquid-liquid miscibility gap. PMID:27165990

  3. Heavy fermions. Unconventional Fermi surface in an insulating state.

    PubMed

    Tan, B S; Hsu, Y-T; Zeng, B; Hatnean, M Ciomaga; Harrison, N; Zhu, Z; Hartstein, M; Kiourlappou, M; Srivastava, A; Johannes, M D; Murphy, T P; Park, J-H; Balicas, L; Lonzarich, G G; Balakrishnan, G; Sebastian, Suchitra E

    2015-07-17

    Insulators occur in more than one guise; a recent finding was a class of topological insulators, which host a conducting surface juxtaposed with an insulating bulk. Here, we report the observation of an unusual insulating state with an electrically insulating bulk that simultaneously yields bulk quantum oscillations with characteristics of an unconventional Fermi liquid. We present quantum oscillation measurements of magnetic torque in high-purity single crystals of the Kondo insulator SmB6, which reveal quantum oscillation frequencies characteristic of a large three-dimensional conduction electron Fermi surface similar to the metallic rare earth hexaborides such as PrB6 and LaB6. The quantum oscillation amplitude strongly increases at low temperatures, appearing strikingly at variance with conventional metallic behavior. PMID:26138105

  4. Synthesis, structure and phase behavior of liquid crystalline polyurethanes

    SciTech Connect

    Papadimitrakopoulos, F.

    1993-01-01

    This dissertation describes the synthesis, structure and phase behavior of polyurethanes based on the mesogenic biphenol 4,4'-bis (6-hydroxyhexoxy)biphenyl (BHHBP) and meta substituted tolylene/phenylene diisocynates. The structure-property relationships were determined as a function of hydrogen-bonding, the position of the methyl group in the tolylene diisocyanate moiety (TDI) and the biphenol moiety. The liquid crystalline phase (mesophase) and crystalline phase were investigated primarily with differential scanning calorimetry (DSC), wide angle X-ray scattering (WAXS) and infrared spectroscopy. The influence of H-bonding on the structure and phase behavior of 1,4-LCPU-6 was determined by the synthesis of high molecular weight N-Methyl2,4-LCPU-65, using a novel high temperature polymerization of a biscarbamoyl chloride with the BHHBP mesogenic diol. In contrast to the regular ([alpha], [omega]-hexane diol) based polyurethanes (PUs), BHHBP derived polyurethanes (LCPUs) crystallize rapidly from their melts. Hexafluoroisopropanol fast solvent-evaporation casting or rapid cooling from the melt resulted in thin films or bulk samples with a glassy mesophase morphology. During the subsequent heating scan, the mesophase to crystal transition occurs. Highly oriented fibers were obtained for the mesogenic polyurethanes. Atomistic molecular simulations coupled with X-ray intensity refinement allowed determination of the crystalline chain conformation and packing characteristics for the 2,6-LCPU-6 and 1,3-LCPU-6 (2,6-TDI and 1,3-Phenylene Diisocynate (1,3-PDI) derived LCPUs). On the basis of structural similarity and well resolved WAXS powder patterns similar analysis was extended to the regular polyurethanes as well (2,6-PU-6 and 1,3-PU-6). The good correlation polymers suggest that melting is primarily controlled by the dissociation of H-bonds in the ordered domains.

  5. Anomalous effect of flow rate on the electrochemical behavior at a liquid|liquid interface under microfluidic conditions.

    PubMed

    Kaluza, Dawid; Adamiak, Wojciech; Kalwarczyk, Tomasz; Sozanski, Krzysztof; Opallo, Marcin; Jönsson-Niedziolka, Martin

    2013-12-23

    We have investigated the oxidation of ferrocene at a flowing organic solvent|aqueous electrolyte|solid electrode junction in a microfluidic setup using cyclic voltammetry and fluorescent laser scanning confocal microscopy. At low flow rates the oxidation current decreases with increasing flow, contrary to the Levich equation, but at higher flow rates the current increases linearly with the cube root of the flow rate. This behavior is explained using a simple model postulating a smallest effective width of the three-phase junction, which after fitting to the data comes to be ca. 20 μm. The fluorescence microscopy reveals mixing of the two phases close to the PDMS cover, but the liquid|liquid junction is stable close to the glass support. This study shows the importance of the solid|liquid|liquid junctions for the behavior of multiphase systems under microfluidic conditions. PMID:24328179

  6. The Influence of Disorder on Thermotropic Nematic Liquid Crystals Phase Behavior

    PubMed Central

    Popa-Nita, Vlad; Gerlič, Ivan; Kralj, Samo

    2009-01-01

    We review the theoretical research on the influence of disorder on structure and phase behavior of condensed matter system exhibiting continuous symmetry breaking focusing on liquid crystal phase transitions. We discuss the main properties of liquid crystals as adequate systems in which several open questions with respect to the impact of disorder on universal phase and structural behavior could be explored. Main advantages of liquid crystalline materials and different experimental realizations of random field-type disorder imposed on liquid crystal phases are described. PMID:19865529

  7. Shear Flow Induced Transition from Liquid-Crystalline to Polymer Behavior in Side-Chain Liquid Crystal Polymers

    NASA Astrophysics Data System (ADS)

    Noirez, L.; Lapp, A.

    1997-01-01

    We determine the structure and conformation of side-chain liquid-crystalline polymers subjected to shear flow in the vicinity of the smectic phase by neutron scattering on the velocity gradient plane. Below the nematic-smectic transition we observe a typical liquid-crystal behavior; the smectic layers slide, leading to a main-chain elongation parallel to the velocity direction. In contrast, a shear applied above the transition induces a tilted main-chain conformation which is typical for polymer behavior.

  8. Fermi Pulsar Analysis

    NASA Video Gallery

    This animation illustrates how analysis of Fermi data reveals new pulsars. Fermi's LAT records the precise arrival time and approximate direction of the gamma rays it detects, but to identify a pul...

  9. Magnetic short-range correlations and quantum critical scattering in the non-Fermi liquid regime of URu{sub 2-x}Re{sub x}Si{sub 2} (x = 0.2-0.6).

    SciTech Connect

    Krishnamurthy, V. V.; Adroja, D. T.; Butch, N. P.; Osborn, R.; Sinha, S. K.; Robertson, J. L.; Aronson, M. C.; Nagler, S. E.; Maple, M. B.; ORNL; Rutherford Appleton Lab.; Univ. California at San Diego; Univ. Michigan

    2008-01-01

    The spin dynamics of uranium ions in the non-Fermi liquid compounds URu{sub 2-x}Re{sub x}Si{sub 2}, for x=0.2 to 0.6, have been investigated using inelastic neutron scattering. The wave vector (q) dependence of the magnetic scattering provides evidence of short-range antiferromagnetic correlations at low temperatures for x=0.2,0.25, but the scattering is nearly q independent at x=0.35,0.6. The magnetic response, {bar S}({omega}), obtained from the q-independent part of neutron scattering, varies as {omega}{sup -{alpha}} with a composition-dependent exponent {alpha} = 0.2-0.5. The dynamic magnetic susceptibility {chi}{double_prime}(q,{omega}) of the q-independent part exhibits {omega}/T scaling for the energy transfer {bar h}{omega} between 3.5 and 17 meV in the temperature (T) range of 5-300 K at all the compositions. This scaling, which indicates local quantum criticality, breaks down in the q range, 0.6-1.1 {angstrom}{sup -1} at x = 0.2 and 0.25, that is dominated by short-range antiferromagnetic correlations. The appearance of power laws in the magnetic response measured by inelastic neutron scattering over a wide Re doping region indicates a disorder driven non-Fermi liquid mechanism for the low-temperature physical properties in these compounds.

  10. Low-temperature heat capacities of confined liquid benzene, implying the behavior of ordinary bulk liquids.

    PubMed

    Nagoe, A; Oguni, M; Fujimori, H

    2015-11-18

    Isobaric heat capacities C p of benzene confined in silica MCM-41 mesopores with average diameters equal to and smaller than 2.9 nm were measured by precise adiabatic calorimetry. The confined benzene samples revealed no thermal anomaly due to crystallization/fusion and vitrified at low temperatures. The C p curves displayed a hump and a considerably quick decrease on the low-temperature side of the hump as the pore diameter increased. The enthalpy-relaxation effects observed on intermittent heating showed that the anomaly of the C p hump and quick decrease is not assigned to a glass transition. The bend in the temperature dependence of density reported previously was interpreted as corresponding to the quick decrease in C p . We concluded that the anomalous C p and density behaviors originated from the ordering/excitation in the configurational state, close to the ground state, of confined molecular aggregate and proposed a scenario that explains the general C p curves of ordinary bulk supercooled liquids in equilibrium at low temperatures below the glass-transition temperatures. PMID:26490197

  11. Low-temperature heat capacities of confined liquid benzene, implying the behavior of ordinary bulk liquids

    NASA Astrophysics Data System (ADS)

    Nagoe, A.; Oguni, M.; Fujimori, H.

    2015-11-01

    Isobaric heat capacities C p of benzene confined in silica MCM-41 mesopores with average diameters equal to and smaller than 2.9 nm were measured by precise adiabatic calorimetry. The confined benzene samples revealed no thermal anomaly due to crystallization/fusion and vitrified at low temperatures. The C p curves displayed a hump and a considerably quick decrease on the low-temperature side of the hump as the pore diameter increased. The enthalpy-relaxation effects observed on intermittent heating showed that the anomaly of the C p hump and quick decrease is not assigned to a glass transition. The bend in the temperature dependence of density reported previously was interpreted as corresponding to the quick decrease in C p . We concluded that the anomalous C p and density behaviors originated from the ordering/excitation in the configurational state, close to the ground state, of confined molecular aggregate and proposed a scenario that explains the general C p curves of ordinary bulk supercooled liquids in equilibrium at low temperatures below the glass-transition temperatures.

  12. Carrier density independent scattering rate in SrTiO3-based electron liquids

    NASA Astrophysics Data System (ADS)

    Mikheev, Evgeny; Raghavan, Santosh; Zhang, Jack Y.; Marshall, Patrick B.; Kajdos, Adam P.; Balents, Leon; Stemmer, Susanne

    2016-02-01

    We examine the carrier density dependence of the scattering rate in two- and three-dimensional electron liquids in SrTiO3 in the regime where it scales with Tn (T is the temperature and n ≤ 2) in the cases when it is varied by electrostatic control and chemical doping, respectively. It is shown that the scattering rate is independent of the carrier density. This is contrary to the expectations from Landau Fermi liquid theory, where the scattering rate scales inversely with the Fermi energy (EF). We discuss that the behavior is very similar to systems traditionally identified as non-Fermi liquids (n < 2). This includes the cuprates and other transition metal oxide perovskites, where strikingly similar density-independent scattering rates have been observed. The results indicate that the applicability of Fermi liquid theory should be questioned for a much broader range of correlated materials and point to the need for a unified theory.

  13. Unveiling Unidentified Fermi Sources

    NASA Astrophysics Data System (ADS)

    Zhang, Lizhong; South Pole Telescope

    2016-01-01

    The Fermi γ-ray Space Telescope (Fermi) has surveyed the entire sky at the highest-energy band of the electromagnetic spectrum. The majority of Fermi sources have counterpart identifications from multi-wavelength large-area surveys, particularly in the radio and x-ray bands. However, around 35% of Fermi sources remain unidentified, a problem exasperated by the low resolution of the telescope. Understanding the nature of unidentified Fermi sources is one of the most pressing problems in γ-ray astronomy. The South Pole Telescope (SPT) has completed a survey covering a 2500 square degrees of the southern extragalactic sky with arcminute resolution at millimeter wavelengths. The mm wavelength is the most efficient means to identify blazars and unidentified Fermi sources. Our analysis shows that the SPT point source catalog provides candidate associations for 40% of the unidentified Fermi sources, showing them to be flat-spectrum radio quasars which are extraordinarily bright at millimeter (mm) wavelengths.

  14. Phase behavior and dynamics of a cholesteric liquid crystal

    SciTech Connect

    Roy, D.; Fragiadakis, D.; Roland, C. M.; Dabrowski, R.; Dziaduszek, J.; Urban, S.

    2014-02-21

    The synthesis, equation of state, phase diagram, and dielectric relaxation properties are reported for a new liquid crystal, 4{sup ′}-butyl-4-(2-methylbutoxy)azoxybenzene (4ABO5*), which exhibits a cholesteric phase at ambient temperature. The steepness of the intermolecular potential was characterized from the thermodynamic potential parameter, Γ = 4.3 ± 0.1 and the dynamic scaling exponent, γ = 3.5 ± 0.2. The difference between them is similar to that seen previously for nematic and smectic liquid crystals, with the near equivalence of Γ and γ consistent with the near constancy of the relaxation time of 4ABO5* at the cholesteric to isotropic phase transition (i.e., the clearing line). Thus, chirality does not cause deviations from the general relationship between thermodynamics and dynamics in the ordered phase of liquid crystals. The ionic conductivity of 4ABO5* shows strong coupling to the reorientational dynamics.

  15. Study on Orbital Liquid Transport and Interface Behavior in Vane Tank

    NASA Astrophysics Data System (ADS)

    Kang, Qi; Rui, Wei

    2016-07-01

    Liquid propellant tank is used to supply gas free liquid for spacecraft as an important part of propulsion system. The liquid behavior dominated by surface tension in microgravity is obviously different with that on the ground, which put forward a new challenge to the liquid transport and relocation. The experiments which are investigated at drop tower in National Microgravity Lab have concentrated on liquid relocation following thruster firing. Considered that the liquid located at the bottom in the direction of the acceleration vector, a sphere scale vane tank is used to study the liquid-gas interface behaviors with different acceleration vector and different filling independently and we obtain a series of stable equilibrium interface and relocation time. We find that there is an obvious sedimentation in the direction of acceleration vector when fill rate greater than 2% fill. Suggestions have been put forward that outer vanes transferring liquid to the outlet should be fixed and small holes should be dogged at the vane close to the center post to improve the liquid flow between different vanes when B0 is greater than 2.5. The research about liquid transport alone ribbon vanes is simulated though software Flow3D. The simulation process is verified by comparing the liquid lip and vapor-liquid interface obtained from drop tower experiment and simulation result when fill rate is 15%. Then the influence of fill rate, numbers of vanes and the gap between vane and wall is studied through the same simulate process. Vanes' configurations are also changed to study the effect on the lip and liquid volume below some section. Some suggestions are put forward for the design of vanes.

  16. Collapse Dynamics and Resonance Behavior of Axisymmetric Slender Liquid Bridges

    NASA Astrophysics Data System (ADS)

    Tsige, Mesfin; Alexander, J. I. D.; Rosenblatt, C.; Taylor, P. L.

    2001-03-01

    The evolution of axisymetric liquid bridges subjected to static and oscillatory forces have been studied numerically. When the liquid bridge is subject to constant axial gravity, the collapse time is found to be largely independent of the length of the bridge when other parameters are held constant. For the case of dynamic oscillations and a given forcing amplitude, the frequency of the first resonance peak is found to be maximum when the static body force is zero and decreases with increasing total body force or length of the bridge.

  17. Transient behavior of liquid in an axially vibrated tank

    NASA Astrophysics Data System (ADS)

    Ferger, T. M.

    1981-05-01

    Vibration tests along the principal axis of a propellant tank resulted in failure of an isolation shear disc under certain conditions of tank pressurization, indicating pressures much higher than could be expected from the imposed acceleration field. A mechanism was postulated in which the liquid in the tank was assumed to move as a series of infinitesimal concentric cylinders under the influence of the imposed oscillation field. In moving upward, the liquid compresses the pressurizing gas in the ullage cavity, which then acts as a nonlinear spring propelling the liquid downward into the shear disc at varying rates causing occasional high impact pressures. A computer program was written to solve the one dimensional equations describing liquid motion in the tank. Results showed a very high degree of correlation with test accelerometer traces over a large range of test pressures. A strong nonlinear relationship between tank pressure and impact pressure was predicted and observed. The problem was resolved by increasing tank pressure to a point sufficient to overcome the effective gravitational lead developed during vibration tests.

  18. Analytical thermodynamics of a strongly attractive three-component Fermi gas in one dimension

    SciTech Connect

    He Peng; Yin Xiangguo; Wang Yupeng; Guan Xiwen; Batchelor, Murray T.

    2010-11-15

    Ultracold three-component atomic Fermi gases in one dimension are expected to exhibit rich physics due to the presence of trions and different pairing states. Quantum phase transitions from the trion state into a paired phase and a normal Fermi liquid occur at zero temperature. We derive the analytical thermodynamics of strongly attractive three-component one-dimensional fermions with SU(3) symmetry via the thermodynamic Bethe ansatz method in unequal Zeeman splitting fields H{sub 1} and H{sub 2}. We find explicitly that for low temperature the system acts like either a two-component or a three-component Tomonaga-Luttinger liquid dependent on the system parameters. The phase diagrams for the chemical potential and specific heat are presented for illustrative values of the Zeeman splitting. We also demonstrate that crossover between different Tomonaga-Luttinger-liquid phases exhibit singular behavior in specific heat and entropy as the temperature tends to zero. Beyond Tomonaga-Luttinger-liquid physics, we obtain the equation of state which provides a precise description of universal thermodynamics and quantum criticality in three-component, strongly attractive Fermi gases.

  19. Simulation of lubricating behavior of a thioether liquid lubricant by an electrochemical method

    NASA Technical Reports Server (NTRS)

    Morales, W.

    1984-01-01

    An electrochemical cell was constructed to explore the possible radical anion forming behavior of a thioether liquid lubricant. The electrochemical behavior of the thioether was compared with the electrochemical behavior of biphenyl, which is known to form radical anions. Under controlled conditions biphenyl undergoes a reversible reaction to a radical anion, whereas the thioether undergoes an irreversible reduction yielding several products. These results are discussed in relation to boundary lubrication.

  20. Collisional Properties of a Polarized Fermi Gas with Resonant Interactions

    SciTech Connect

    Bruun, G. M.; Recati, A.; Stringari, S.; Pethick, C. J.; Smith, H.

    2008-06-20

    Highly polarized mixtures of atomic Fermi gases constitute a novel Fermi liquid. We demonstrate how information on thermodynamic properties may be used to calculate quasiparticle scattering amplitudes even when the interaction is resonant and apply the results to evaluate the damping of the spin dipole mode. We estimate that under current experimental conditions the mode would be intermediate between the hydrodynamic and collisionless limits.

  1. Strong Coupling Effects on the Specific Heat of an Ultracold Fermi Gas in the Unitarity Limit

    NASA Astrophysics Data System (ADS)

    van Wyk, P.; Tajima, H.; Hanai, R.; Ohashi, Y.

    2016-05-01

    We investigate strong-coupling corrections to the specific heat C_V in the normal state of an ultracold Fermi gas in the BCS-BEC crossover region. A recent experiment on a ^6Li unitary Fermi gas (Ku et. al. in Science 335:563 2012) shows that C_V is remarkably amplified near the superfluid phase transition temperature T_c, being similar to the well-known λ -structure observed in liquid ^4He. Including pairing fluctuations within the framework of the strong-coupling theory developed by Nozières and Schmitt-Rink, we show that strong pairing fluctuations are sufficient to explain the anomalous behavior of C_V observed in a ^6Li unitary Fermi gas near T_c. We also show that there is no contribution from stable preformed Cooper pairs to C_V at the unitarity. This indicates that the origin of the observed anomaly is fundamentally different from the case of liquid 4He, where stable ^4He Bose atoms induce the λ -structure in C_V near the superfluid instability. Instead, the origin is the suppression of the entropy S, near T_c, due to the increase of metastable preformed Cooper pairs. Our results indicate that the specific heat is a useful quantity to study the effects of pairing fluctuations on the thermodynamic properties of an ultracold Fermi gas in the BCS-BEC crossover region.

  2. Basicity of aromatic amines from liquid chromatographic behavior

    NASA Technical Reports Server (NTRS)

    Young, P. R.; Mcnair, H. M.

    1975-01-01

    A liquid chromatographic investigation was conducted to determine whether the adsorption of weakly basic aromatic amines on slightly acidic silica gel adsorbents could be used to study their relative basicity. Under proper conditions, a linear correlation between pKb and log of capacity factor was observed. This finding may prove useful in helping to predict the relative basicity of closely related aromatic diamines, especially new amines being synthesized for polymer synthesis.

  3. Study of interfacial behavior in cocurrent gas-liquid flows

    SciTech Connect

    McCready, M.J.

    1990-01-01

    We have examined the mechanism of formation of solitary waves on gas-liquid flows and found, that these form from existing periodic waves which have sufficiently large ({approximately}1.5 to 2 depending upon fluid properties) amplitude to liquid layer-thickness ratios. The exact process for the wave shape change is not understood but it does not seem to be related to the wave steepness (amplitude/wavelength) or to separation of gas flow over the waves. The observed confinement of solitary waves to low liquid Reynolds numbers results because the necessary large precursor waves do not form if the wave speed dispersion is too large or if the wavelength of the dominant waves is too short, as occurs for higher Re{sub L}. Measurements of interface tracings and calculations of power spectra and bispectra as a function of flow distance for conditions close to neutral stability reveal that the initially, linearly unstable mode is stabilized by formation of overtones which are linearly stable and can dissipate energy. As a result, a stable wave field can occur. Mode equations, which include quadratic nonlinearities, can model this process to the extent of producing some degree of quantitative predictions for the amplitudes of the wave modes. However, a complete picture of the wave field must include sidebands as well because these are observed for some flow conditions. 34 refs., 12 figs., 2 tabs.

  4. Bubbling behaviors induced by gas-liquid mixture permeating through a porous medium

    NASA Astrophysics Data System (ADS)

    Hu, Liang; Li, Mingbo; Chen, Wenyu; Xie, Haibo; Fu, Xin

    2016-08-01

    This paper investigates the bubbling behaviors induced by gas-liquid mixture permeating through porous medium (PM), which was observed in developing immersion lithography system and was found having great differences with traditional bubbling behaviors injected with only gas phase through the PM. An experimental setup was built up to investigate the bubbling characteristics affected by the mixed liquid phase. Both the flow regimes of gas-liquid mixture in micro-channel (upstream of the PM) and the bubbling flow regimes in water tank (downstream of the PM) were recorded synchronously by high-speed camera. The transitions between the flow regimes are governed by gas and liquid Weber numbers. Based on the image analysis, the characteristic parameters of bubbling region, including the diameter of bubbling area on PM surface, gas-phase volume flux, and dispersion angle of bubbles in suspending liquid, were studied under different proportions of gas and liquid flow rate. Corresponding empirical correlations were developed to describe and predict these parameters. Then, the pertinent bubble characteristics in different bubbling flow regimes were systematically investigated. Specifically, the bubble size distribution and the Sauter mean diameter affected by increasing liquid flow rate were studied, and the corresponding analysis was given based on the hydrodynamics of bubble-bubble and bubble-liquid interactions. According to dimensionless analysis, the general prediction equation of Sauter mean diameter under different operating conditions was proposed and confirmed by experimental data. The study of this paper is helpful to improve the collection performance of immersion lithography and aims to reveal the differences between the bubbling behaviors on PM caused by only gas flow and gas-liquid mixture flow, respectively, for the researches of fluid flow.

  5. Numerical Modeling of Inclusion Behavior in Liquid Metal Processing

    NASA Astrophysics Data System (ADS)

    Bellot, Jean-Pierre; Descotes, Vincent; Jardy, Alain

    2013-09-01

    Thermomechanical performance of metallic alloys is directly related to the metal cleanliness that has always been a challenge for metallurgists. During liquid metal processing, particles can grow or decrease in size either by mass transfer with the liquid phase or by agglomeration/fragmentation mechanisms. As a function of numerical density of inclusions and of the hydrodynamics of the reactor, different numerical modeling approaches are proposed; in the case of an isolated particle, the Lagrangian technique coupled with a dissolution model is applied, whereas in the opposite case of large inclusion phase concentration, the population balance equation must be solved. Three examples of numerical modeling studies achieved at Institut Jean Lamour are discussed. They illustrate the application of the Lagrangian technique (for isolated exogenous inclusion in titanium bath) and the Eulerian technique without or with the aggregation process: for precipitation and growing of inclusions at the solidification front of a Maraging steel, and for endogenous inclusions in the molten steel bath of a gas-stirred ladle, respectively.

  6. Shear Alignment Behavior of Nematic Solutions Induced by Ultralong Side-Group Liquid Crystal Polymers

    NASA Astrophysics Data System (ADS)

    Kempe, M. D.; Kornfield, J. A.

    2003-03-01

    Addition of a low concentration of a very long (430 kg/mol) side group liquid crystal polymer is shown to produce dramatic changes in the flow characteristics of a calamitic nematic liquid crystal. This polymer causes a typical flow-aligning nematic liquid crystal to align near the velocity gradient direction rather than near the velocity direction, corresponding to having a tumbling parameter λ<-1, for concentrations greater than 7.5% polymer. Such flow-aligning behavior has not been reported previously in a calamitic nematic. The large molecular weight of the present polymer relative to those examined in the prior literature is responsible for these new phenomena.

  7. Dielectric Relaxation and Rheological Behavior of Supramolecular Polymeric Liquid

    SciTech Connect

    Lou, Nan; Wang, Yangyang; Li, Xiaopeng; Li, Haixia; Wang, Ping

    2013-01-01

    A model self-complementary supramolecular polymer based on thymine and diamidopyridine triple hydrogen-bonding motifs has been synthesized, and its dielectric and rheological behavior has been investigated. The formation of supramolecular polymers has been unequivocally demonstrated by nuclear magnetic resonance, electrospray ionization mass spectrometry with traveling wave ion mobility separation, dielectric spectroscopy, and rheology. The dynamical behaviors of this associating polymer generally conform to those of type-A polymers, with a low-frequency chain relaxation and a high-frequency relaxation visible in both rheological and dielectric measurements. The dielectric chain relaxation shows the ideal symmetric Debye-like shape, resembling the peculiar features of hydrogen-bonding monoalcohols. Detailed analysis shows that there exists a weak decoupling between the mechanical terminal relaxation and dielectric Debye-like relaxation. The origin of the Debye-like dielectric relaxation is further discussed in the light of monoalcohols.

  8. NONIDEAL BEHAVIOR DURING COMPLETE DISSOLUTION OF ORGANIC IMMISCIBLE LIQUID IN NATURAL POROUS MEDIA

    PubMed Central

    Russo, A.E.; Mahal, M.K.; Brusseau, M.L.

    2011-01-01

    Experiments were conducted to investigate the complete dissolution of organic immiscible liquid residing within natural porous media. Organic-liquid dissolution was investigated by conducting experiments with homogeneously packed columns containing a residual saturation of organic liquid (trichloroethene). The porous media used comprised different textures (ranges of particle-size distributions) and organic-carbon contents. The dissolution behavior that was observed for the soil and aquifer sediment systems deviated from the behavior typically observed for systems composed of ideal sands. Specifically, multi-step elution curves were observed, with multiple extended periods of relatively constant contaminant flux. This behavior was more pronounced for the two media with larger particle-size distributions. Conversely, this type of dissolution behavior was not observed for the control system, which consisted of a well-sorted sand. It is hypothesized that the pore-scale configuration of the organic liquid and of the flow field is more complex for the poorly sorted media, and that this greater complexity constrains dissolution dynamics, leading to the observed nonideal behavior. PMID:19643542

  9. Nonlinear flow behaviors of nematic liquid crystals in complex geometries

    NASA Astrophysics Data System (ADS)

    Araki, Takeaki

    2013-02-01

    We study nematic liquid crystals flowing in a regular-shaped porous medium by means of lattice Boltzmann simulations. With strong anchoring, the director field cannot align uniformly and topological defects are stably formed with a large number of possible configurations. In a quiescent state, each configuration is arrested since the energy barriers between possible configurations are higher than the thermal energy. If the flow speed is slow enough, the defect pattern is not changed from the initial quiescent configuration. Above a critical flow speed, the defect pattern transforms to a new stable configuration. In a regular-shaped porous matrix, there remain regularly aligned disclination loops. This regular pattern is maintained even after the flow is stopped.

  10. Anisotropic behavior of water in ferroelectric liquid crystals.

    PubMed

    Singh, G; Choudhary, A; Prakash, G Vijaya; Biradar, A M

    2010-05-01

    The outcome of water addition in ferroelectric liquid crystal (FLC) has been investigated in uniform and defect-free homogeneous and homeotropically aligned monodomain sample cells from electro-optical and dielectric spectroscopic measurements. The lagging in optical response between nonconducting (spatially variable switching) and conducting (conventional switching) portions of water added FLC sample cell has been observed by frequency-dependent electro-optical studies. The bias-dependent water related new relaxation peak near the conventional Goldstone mode relaxation process has been observed only in the homogeneous alignment and not in the homeotropic one. Further, the significant increment in dielectric anisotropy as well as faster diffusion of water along long molecular axis than short molecular axis has also been monitored. These studies strongly suggest that the distribution of water is anisotropic in FLC medium and could be the reason for new relaxation peak in the water added FLC sample. PMID:20866247

  11. Behavior of liquid metal droplets in an aspirating nozzle

    SciTech Connect

    Swank, W.D.; Fincke, J.R.; Mason, T.A.

    1990-01-01

    Measurements of particle size, velocity, and relative mass flux were made on spray field produced by aspirating liquid tin into 350{degrees}C argon flowing through a venturi nozzle via a small orifice in the throat of the nozzle. Details of the aspiration and droplet formation process were observed through windows in the nozzle. The spatial distribution of droplet size, velocity, and relative number density were measured at a location 10 mm from the nozzle exit. Due to the presence of separated flow in the nozzle, changes in nozzle inlet pressure did not significantly effect resulting droplet size and velocity. This suggests that good aerodynamic nozzle design is required if spray characteristics are to be controlled by nozzle flow. 5 refs.

  12. Behavior of liquid metal droplets in an aspirating nozzle. Revision

    SciTech Connect

    Swank, W.D.; Fincke, J.R.; Mason, T.A.

    1990-12-31

    Measurements of particle size, velocity, and relative mass flux were made on spray field produced by aspirating liquid tin into 350{degrees}C argon flowing through a venturi nozzle via a small orifice in the throat of the nozzle. Details of the aspiration and droplet formation process were observed through windows in the nozzle. The spatial distribution of droplet size, velocity, and relative number density were measured at a location 10 mm from the nozzle exit. Due to the presence of separated flow in the nozzle, changes in nozzle inlet pressure did not significantly effect resulting droplet size and velocity. This suggests that good aerodynamic nozzle design is required if spray characteristics are to be controlled by nozzle flow. 5 refs.

  13. Mechanical behavior of a fluid-sensitive material during liquid diffusion

    NASA Astrophysics Data System (ADS)

    Widiastuti, Indah; Sbarski, Igor; Masood, S. H.

    2014-05-01

    This paper described the analytical study that we performed in an attempt to understand the combined effect of liquid diffusion and temperature on the mechanical response of viscoelastic liquid-sensitive material. A constitutive equation for linear viscoelasticity, which includes the effect of liquid diffusion, is used to model the mechanical response of a fluid-sensitive polymer such as PLA-based bioplastic. The viscoelastic characteristics which represent material degradation due to liquid diffusion were expressed using a creep-based formulation represented by Burger's model. Creep experiment data were fitted to the Burgers model to provide a liquid content-dependent set of input data for subsequent time-dependent analysis. Further, analytical solutions for stresses and deformations were obtained from the corresponding elastic solution by applying the Correspondence Principle, using previously defined material characteristics. Spatial and time variations of stress and deformation were evaluated to give a precise description of the material behavior under hygroscopic conditions. We propose a stress concentration factor to take into account the liquid diffusion-induced stress that may result in a failure of an application. The results emphasize the importance of considering liquid diffusion and viscoelastic properties in the design of components using liquid-absorbable material.

  14. Fibroblast behavior at aqueous interfaces with perfluorocarbon, silicone, and fluorosilicone liquids.

    PubMed

    Sparrow, J R; Ortiz, R; MacLeish, P R; Chang, S

    1990-04-01

    Perfluorocarbon, silicone, and fluorosilicone liquids with potential for use as vitreous substitutes in the management of complex retinal detachment were evaluated for surface reactivity by assessing the behavior of anchorage-dependent fibroblasts plated at the phase boundary between these compounds and culture medium. Low-viscosity perfluorcarbons were alumina-treated to remove polar impurities. On perfluorodecalin, perfluorodimethylcyclohexane, perfluorotrimethylcyclohexane, perfluoroethylcyclohexane, perfluorooctane, perfluoroperhydrophenanthrene, perfluoromethyladamantane, perfluorodimethyladamantane, the highly viscous perfluoropolyether liquids Krytox TLF7067 and 6354, and dimethylsiloxane liquids of a variety of viscosities, most cells did not attach; the few that did attach exhibited minimal spreading behavior and did not achieve the flattened spindle-shape morphology which is a prerequisite to normal proliferative activity. Conversely, on perfluoromethyldecaline, perfluorofluorene, perfluorotributylamine, the perfluoropolyether K-6 hexamer, trifluoropropylmethylsiloxane (fluorosilicone), and diphenyldimethylsiloxane, some cells became fusiform-shaped and exhibited proliferation, the extent of which varied with the compound. The association of alumina treatment of perfluorocarbon liquids with a reduction in cell growth was indicative of a relationship between the presence of residual hydrogen-containing impurities and the capacity for cellular attachment and growth. This correlation was demonstrated also in experiments in which cell attachment and growth was facilitated by the addition of hydrogen-rich monohydroperfluorooctane to alumina-treated perfluorooctane. In conclusion, evidence for the presence of surface active impurities in liquid vitreous substitute materials can be obtained by observing the behavior of attachment-dependent cells plated at the boundary between these compounds and culture medium. PMID:2335433

  15. Infiltration behavior of sintering liquid on nuclei ores during low-titanium ore sintering process

    NASA Astrophysics Data System (ADS)

    Liu, Dong-hui; Zhang, Jian-liang; Xue, Xun; Wang, Guang-wei; Li, Ke-jiang; Liu, Zheng-jian

    2016-06-01

    Sinter strength is dependent not only on the self-intensity of the residual rude and bonding phase but also on the bonding degree between them. The infiltration behavior of sintering liquid on nuclei ores influences the bonding degree, which ultimately determines the sinter strength. Infiltration tests were conducted using micro-sinter equipment. The infiltration area index of original liquid (IAO), infiltration volume index of secondary liquid (IVS), and sinter body bonding strength (SBS) were proposed to study the melt infiltration behavior. The results show that the IVS first increases and then decreases with increasing TiO2 content in adhering fines, whereas the IAO exhibits the opposite behavior. Compared with the original liquid, the secondary liquid shows lower porosity, smaller pores, and more uniform distribution. The SBS increases first and then decreases with increasing IAO and TiO2 content, and reaches a maximum when the IAO and TiO2 contents are approximately 0.5 and 2.0wt%, respectively. The SBS first increases and then tends to be stable with increasing IVS. The TiO2 content is suggested to be controlled to approximately 2.0wt% in low-titanium ore sintering.

  16. Magnetic field induced motion behavior of gas bubbles in liquid

    PubMed Central

    Wang, Keliang; Pei, Pucheng; Pei, Yu; Ma, Ze; Xu, Huachi; Chen, Dongfang

    2016-01-01

    The oxygen evolution reaction generally exists in electrochemical reactions. It is a ubiquitous problem about how to control the motion of oxygen bubbles released by the reaction. Here we show that oxygen bubbles during oxygen evolution reaction exhibit a variety of movement patterns in the magnetic field, including directional migration and rotational motion of oxygen bubbles when the magnet in parallel with the electrode, and exclusion movement of oxygen bubbles when the magnet perpendicular to the electrode. The results demonstrate that the direction of oxygen bubbles movement is dependent upon the magnet pole near the electrode, and the kinetics of oxygen bubbles is mainly proportional to intensity of the electromagnetic field. The magnetic-field induced rotational motion of oxygen bubbles in a square electrolyzer can increase liquid hydrodynamics, thus solve the problems of oxygen bubbles coalescence, and uneven distribution of electrolyte composition and temperature. These types of oxygen bubbles movement will not only improve energy saving and metal deposition for energy storage and metal refinery, but also propel object motion in application to medical and martial fields. PMID:26867515

  17. Magnetic field induced motion behavior of gas bubbles in liquid

    NASA Astrophysics Data System (ADS)

    Wang, Keliang; Pei, Pucheng; Pei, Yu; Ma, Ze; Xu, Huachi; Chen, Dongfang

    2016-02-01

    The oxygen evolution reaction generally exists in electrochemical reactions. It is a ubiquitous problem about how to control the motion of oxygen bubbles released by the reaction. Here we show that oxygen bubbles during oxygen evolution reaction exhibit a variety of movement patterns in the magnetic field, including directional migration and rotational motion of oxygen bubbles when the magnet in parallel with the electrode, and exclusion movement of oxygen bubbles when the magnet perpendicular to the electrode. The results demonstrate that the direction of oxygen bubbles movement is dependent upon the magnet pole near the electrode, and the kinetics of oxygen bubbles is mainly proportional to intensity of the electromagnetic field. The magnetic-field induced rotational motion of oxygen bubbles in a square electrolyzer can increase liquid hydrodynamics, thus solve the problems of oxygen bubbles coalescence, and uneven distribution of electrolyte composition and temperature. These types of oxygen bubbles movement will not only improve energy saving and metal deposition for energy storage and metal refinery, but also propel object motion in application to medical and martial fields.

  18. Anomalous swimming behavior of bacteria in nematic liquid crystals

    NASA Astrophysics Data System (ADS)

    Sokolov, Andrey; Zhou, Shuang; Lavrentovich, Oleg; Aranson, Igor

    2015-03-01

    Flagellated bacteria stop swimming in isotropic media of viscosity higher than 0.06kgm-1s-1. However, Bacillus Subtilis slows down by only about 30% in a nematic chromonic liquid crystal (CLC, 14wt% DSCG in water), where the anisotropic viscosity can be as high as 6kgm-1s-1. The bacteria velocity (Vb) is linear with the flagella rotation frequency. The phase velocity of the flagella Vf ~ 2Vb in LC, as compared to Vf ~ 10Vb in water. The flow generated by the bacteria is localized along the bacterial body axis, decaying slowly over tens of micrometers along, but rapidly over a few micrometers across this axis. The concentrated flow grants the bacteria new ability to carry cargo particles in LC, ability not seen in their habitat isotropic media. We attribute these anomalous features to the anisotropy of viscosity of the CLC, namely, the viscosities of splay and twist is hundreds times higher than that of bend deformation, which provides extra boost of swimming efficiency and enables the bacteria swim at considerable speed in a viscous medium. Our findings can potentially lead to applications such as particle transportation in microfluidic devices. A.S and I.A are supported by the US DOE, Office of Science, BES, Materials Science and Engineering Division. S.Z. and O.D.L are supported by NSF DMR 1104850, DMS-1434185.

  19. Magnetic field induced motion behavior of gas bubbles in liquid.

    PubMed

    Wang, Keliang; Pei, Pucheng; Pei, Yu; Ma, Ze; Xu, Huachi; Chen, Dongfang

    2016-01-01

    The oxygen evolution reaction generally exists in electrochemical reactions. It is a ubiquitous problem about how to control the motion of oxygen bubbles released by the reaction. Here we show that oxygen bubbles during oxygen evolution reaction exhibit a variety of movement patterns in the magnetic field, including directional migration and rotational motion of oxygen bubbles when the magnet in parallel with the electrode, and exclusion movement of oxygen bubbles when the magnet perpendicular to the electrode. The results demonstrate that the direction of oxygen bubbles movement is dependent upon the magnet pole near the electrode, and the kinetics of oxygen bubbles is mainly proportional to intensity of the electromagnetic field. The magnetic-field induced rotational motion of oxygen bubbles in a square electrolyzer can increase liquid hydrodynamics, thus solve the problems of oxygen bubbles coalescence, and uneven distribution of electrolyte composition and temperature. These types of oxygen bubbles movement will not only improve energy saving and metal deposition for energy storage and metal refinery, but also propel object motion in application to medical and martial fields. PMID:26867515

  20. Understanding the impact of the central atom on the ionic liquid behavior: Phosphonium vs ammonium cations

    SciTech Connect

    Carvalho, Pedro J.; Ventura, Sónia P. M.; Batista, Marta L. S.; Schröder, Bernd; Coutinho, João A. P.; Gonçalves, Fernando; Esperança, José; Mutelet, Fabrice

    2014-02-14

    The influence of the cation's central atom in the behavior of pairs of ammonium- and phosphonium-based ionic liquids was investigated through the measurement of densities, viscosities, melting temperatures, activity coefficients at infinite dilution, refractive indices, and toxicity against Vibrio fischeri. All the properties investigated are affected by the cation's central atom nature, with ammonium-based ionic liquids presenting higher densities, viscosities, melting temperatures, and enthalpies. Activity coefficients at infinite dilution show the ammonium-based ionic liquids to present slightly higher infinite dilution activity coefficients for non-polar solvents, becoming slightly lower for polar solvents, suggesting that the ammonium-based ionic liquids present somewhat higher polarities. In good agreement these compounds present lower toxicities than the phosphonium congeners. To explain this behavior quantum chemical gas phase DFT calculations were performed on isolated ion pairs at the BP-TZVP level of theory. Electronic density results were used to derive electrostatic potentials of the identified minimum conformers. Electrostatic potential-derived CHelpG and Natural Population Analysis charges show the P atom of the tetraalkylphosphonium-based ionic liquids cation to be more positively charged than the N atom in the tetraalkylammonium-based analogous IL cation, and a noticeable charge delocalization occurring in the tetraalkylammonium cation, when compared with the respective phosphonium congener. It is argued that this charge delocalization is responsible for the enhanced polarity observed on the ammonium based ionic liquids explaining the changes in the thermophysical properties observed.

  1. Understanding the impact of the central atom on the ionic liquid behavior: phosphonium vs ammonium cations.

    PubMed

    Carvalho, Pedro J; Ventura, Sónia P M; Batista, Marta L S; Schröder, Bernd; Gonçalves, Fernando; Esperança, José; Mutelet, Fabrice; Coutinho, João A P

    2014-02-14

    The influence of the cation's central atom in the behavior of pairs of ammonium- and phosphonium-based ionic liquids was investigated through the measurement of densities, viscosities, melting temperatures, activity coefficients at infinite dilution, refractive indices, and toxicity against Vibrio fischeri. All the properties investigated are affected by the cation's central atom nature, with ammonium-based ionic liquids presenting higher densities, viscosities, melting temperatures, and enthalpies. Activity coefficients at infinite dilution show the ammonium-based ionic liquids to present slightly higher infinite dilution activity coefficients for non-polar solvents, becoming slightly lower for polar solvents, suggesting that the ammonium-based ionic liquids present somewhat higher polarities. In good agreement these compounds present lower toxicities than the phosphonium congeners. To explain this behavior quantum chemical gas phase DFT calculations were performed on isolated ion pairs at the BP-TZVP level of theory. Electronic density results were used to derive electrostatic potentials of the identified minimum conformers. Electrostatic potential-derived CHelpG and Natural Population Analysis charges show the P atom of the tetraalkylphosphonium-based ionic liquids cation to be more positively charged than the N atom in the tetraalkylammonium-based analogous IL cation, and a noticeable charge delocalization occurring in the tetraalkylammonium cation, when compared with the respective phosphonium congener. It is argued that this charge delocalization is responsible for the enhanced polarity observed on the ammonium based ionic liquids explaining the changes in the thermophysical properties observed. PMID:24527930

  2. Understanding the impact of the central atom on the ionic liquid behavior: Phosphonium vs ammonium cations

    NASA Astrophysics Data System (ADS)

    Carvalho, Pedro J.; Ventura, Sónia P. M.; Batista, Marta L. S.; Schröder, Bernd; Gonçalves, Fernando; Esperança, José; Mutelet, Fabrice; Coutinho, João A. P.

    2014-02-01

    The influence of the cation's central atom in the behavior of pairs of ammonium- and phosphonium-based ionic liquids was investigated through the measurement of densities, viscosities, melting temperatures, activity coefficients at infinite dilution, refractive indices, and toxicity against Vibrio fischeri. All the properties investigated are affected by the cation's central atom nature, with ammonium-based ionic liquids presenting higher densities, viscosities, melting temperatures, and enthalpies. Activity coefficients at infinite dilution show the ammonium-based ionic liquids to present slightly higher infinite dilution activity coefficients for non-polar solvents, becoming slightly lower for polar solvents, suggesting that the ammonium-based ionic liquids present somewhat higher polarities. In good agreement these compounds present lower toxicities than the phosphonium congeners. To explain this behavior quantum chemical gas phase DFT calculations were performed on isolated ion pairs at the BP-TZVP level of theory. Electronic density results were used to derive electrostatic potentials of the identified minimum conformers. Electrostatic potential-derived CHelpG and Natural Population Analysis charges show the P atom of the tetraalkylphosphonium-based ionic liquids cation to be more positively charged than the N atom in the tetraalkylammonium-based analogous IL cation, and a noticeable charge delocalization occurring in the tetraalkylammonium cation, when compared with the respective phosphonium congener. It is argued that this charge delocalization is responsible for the enhanced polarity observed on the ammonium based ionic liquids explaining the changes in the thermophysical properties observed.

  3. Universal low-energy physics in 1D strongly repulsive multi-component Fermi gases

    NASA Astrophysics Data System (ADS)

    Jiang, Yuzhu; He, Peng; Guan, Xi-Wen

    2016-04-01

    It has been shown (Yang and You 2011 Chin. Phys. Lett. 28 020503) that at zero temperature the ground state of the one-dimensional (1D) w-component Fermi gas coincides with that of the spinless Bose gas in the limit ω \\to ∞ . This behavior was experimentally evidenced through quasi-1D tightly trapping ultracold 173Yb atoms in a recent paper (Pagano et al 2014 Nat. Phys. 10 198). However, understanding of low-temperature behavior of Fermi gases with a repulsive interaction requires spin-charge separated conformal field theories of an effective Tomonaga-Luttinger liquid and an antiferromagnetic SU(w) Heisenberg spin chain. Here we analytically derive universal thermodynamics of 1D strongly repulsive fermionic gases with SU(w) symmetry via the Yang-Yang thermodynamic Bethe ansatz method. The analytical free energy and magnetic properties of the systems at low temperature in a weak magnetic field are obtained through the Wiener-Hopf method. In particular, the free energy essentially manifests the spin-charge separated conformal field theories for high-symmetry systems with arbitrary repulsive interaction strength. We also find that the sound velocity of the Fermi gases in the large w limit coincides with that for the spinless Bose gas, whereas the spin velocity vanishes quickly as w becomes large. This indicates strong suppression of the Fermi exclusion statistics by the commutativity feature among the w-component fermions with different spin states in the Tomonaga-Luttinger liquid phase. Moreover, the equations of state and critical behavior of physical quantities at finite temperature are analytically derived in terms of the polylogarithm functions in the quantum critical region.

  4. Phase and Topological Behavior of Lyotropic Chromonic Liquid Crystals in Double Emulsions

    NASA Astrophysics Data System (ADS)

    Davidson, Zoey S.; Jeong, Joonwoo; Tu, Fuquan; Lohr, Matt; Lee, Daeyeon; Collings, Peter J.; Lubensky, Tom C.; Yodh, A. G.

    2013-03-01

    Lyotropic chromonic liquid crystals, assembled by non-covalent interactions, have fascinating temperature- and concentration-dependent phase behavior. Using water-oil-water double emulsions, we are able control the inner droplet chromonic phase concentration by osmosis through the oil phase. We then study the configurations of the chromonic liquid crystal phases in droplets by varying the oil types, oil soluble surfactants, and inner droplet diameter. We employ polarization microscopy to observe resulting nematic and columnar phases of Sunset Yellow FCF, and we deduce the liquid crystal configuration of both phases within the droplets. Simulations based on Jones matrices confirm droplet appearance, and preliminary observations of chromonic liquid crystal shells in oil-water-oil double emulsions are reported. Supported by UPenn MRSEC DMR 11-20901 and NSF DMR 12-05463

  5. Entropy excess in strongly correlated Fermi systems near a quantum critical point

    NASA Astrophysics Data System (ADS)

    Clark, J. W.; Zverev, M. V.; Khodel, V. A.

    2012-12-01

    A system of interacting, identical fermions described by standard Landau Fermi-liquid (FL) theory can experience a rearrangement of its Fermi surface if the correlations grow sufficiently strong, as occurs at a quantum critical point where the effective mass diverges. As yet, this phenomenon defies full understanding, but salient aspects of the non-Fermi-liquid (NFL) behavior observed beyond the quantum critical point are still accessible within the general framework of the Landau quasiparticle picture. Self-consistent solutions of the coupled Landau equations for the quasiparticle momentum distribution n(p) and quasiparticle energy spectrum ɛ(p) are shown to exist in two distinct classes, depending on coupling strength and on whether the quasiparticle interaction is regular or singular at zero momentum transfer. One class of solutions maintains the idempotency condition n2(p)=n(p) of standard FL theory at zero temperature T while adding pockets to the Fermi surface. The other solutions are characterized by a swelling of the Fermi surface and a flattening of the spectrum ɛ(p) over a range of momenta in which the quasiparticle occupancies lie between 0 and 1 even at T=0. The latter, non-idempotent solution is revealed by analysis of a Poincaré mapping associated with the fundamental Landau equation connecting n(p) and ɛ(p) and validated by solution of a variational condition that yields the symmetry-preserving ground state. Significantly, this extraordinary solution carries the burden of a large temperature-dependent excess entropy down to very low temperatures, threatening violation of the Nernst Theorem. It is argued that certain low-temperature phase transitions, notably those involving Cooper-pair formation, offer effective mechanisms for shedding the entropy excess. Available measurements in heavy-fermion compounds provide concrete support for such a scenario.

  6. Identification of nonmonotonic behaviors and stick-slip transition in liquid crystal polymers

    NASA Astrophysics Data System (ADS)

    Pujolle-Robic, Caroline; Noirez, Laurence

    2003-12-01

    The recent identification of shear-induced phases in the isotropic melts of liquid crystal polymers shows that these materials are expected to display original nonlinear behaviors. We have investigated the flow behavior of a nematic sidechain polymer above its isotropic-nematic transition temperature. Nonlinear rheology and birefringence measurements indicate the appearance, above a critical shear rate, of the shear-induced isotropic-nematic phase transition. The rheological behavior of this induced phase is characterized by undamped time-periodic shear stress oscillations. These sustained oscillations are interpreted in terms of a stick-slip mechanism alternating high-friction static state and low-friction kinetic state.

  7. Titan's liquids: Exotic behavior and its implications on global fluid circulation

    NASA Astrophysics Data System (ADS)

    Tan, Sugata P.; Kargel, Jeffrey S.; Jennings, Donald E.; Mastrogiuseppe, Marco; Adidharma, Hertanto; Marion, Giles M.

    2015-04-01

    Based on a validated model for cryogenic chemical systems, referred to as CRYOCHEM ("Cryogenic Chemistry Model"), surface liquids on Titan are shown to exhibit exotic behavior of density increase with temperature but decrease with pressure, unless the temperature falls below 89.8 K. It is also the case for the atmospheric liquid condensates below an altitude where the liquid density is minimum. The exotic behavior is of compositional origin, which does not have an analog in the atmosphere and liquid water on Earth. As the latitudinal and seasonal variations of surface temperature are known, it is possible to map out the global liquid and vapor density variations as well as the equilibrium phase compositions, which will be useful as inputs for atmospheric general circulation models (GCMs) and investigations of Titan's methane-equivalent of Earth's hydrological cycle, local subsurface alkanology (equivalent to hydrology on Earth), lake convection, and clastic and chemical sedimentation in the lakes. Further, the density variations can be used to derive a general idea about global fluid circulation in the upper crust based on averaged conditions on Titan. The surface liquid should tend to flow toward the hottest spot on Titan and a return flow occurs beneath the surface, thus providing analogies with thermohaline circulation in Earth's oceans. The vapor phase, on the other hand, has ordinary properties that make the global atmospheric circulation similar to the Hadley cell on Earth, but Titan's cycle reaches the polar regions. The calculated compositions of surface liquids are more methane-rich than other models indicated, thus qualitatively in the right direction to satisfy polar-lake compositions deduced from loss tangents. However, quantitatively there remains a need to find yet more accurate liquid compositions and an optimum equilibrium within constraints of the atmospheric measurements.

  8. Fermi at Six Months

    NASA Technical Reports Server (NTRS)

    Hays, Elizabeth

    2009-01-01

    An overview of the Fermi Gamma-ray Space Telescope's first 6 months in operation is provided. The Fermi Gamma-ray Space Telescope, formerly called GLAST, is a mission to measure the cosmic gamma-ray flux in the energy rage 20 MeV to more than 300 GeV, with supporting measurements for gamma-ray bursts from 8 keV to 30 MeV. It contains a Large Area Telescope capable of viewing the entire sky every 3 hours and a Gamma-ray Burst Monitor for viewing the entire unocculted sky. Since its launch on June 11, 2008 Fermi has provided information on pulsars, gamma ray bursts, relativistic jets, the active galactic nucleus, and a globular star cluster. This presentation describes Fermi's development, mission, instruments and recent findings.

  9. Fermi Galactic Center Zoom

    NASA Video Gallery

    This animation zooms into an image of the Milky Way, shown in visible light, and superimposes a gamma-ray map of the galactic center from NASA's Fermi. Raw data transitions to a view with all known...

  10. Fermi, Szilard and Trinity

    ERIC Educational Resources Information Center

    Anderson, Herbert L.

    1974-01-01

    The final installment of the author's recollections of his work with physicists Enrico Fermi, Leo Szilard and others in developing the first controlled nuclear chain reaction and in preparing the test explosion of the first atomic bomb. (GS)

  11. Impact of Liquid-Vapor to Liquid-Liquid-Vapor Phase Transitions on Asphaltene-Rich Nanoaggregate Behavior in Athabasca Vacuum Residue + Pentane Mixtures

    SciTech Connect

    Long, Bingwen; Chodakowski, Martin; Shaw, John M.

    2013-06-05

    The bulk phase behavior of heavy oil + alkane mixtures and the behavior of the asphaltenes that they contain are topics of importance for the design and optimization of processes for petroleum production, transport, and refining and for performing routine saturates, aromatics, resins, and asphaltenes (SARA) analyses. In prior studies, partial phase diagrams and phase behavior models for Athabasca vacuum residue (AVR) comprising 32 wt % pentane asphaltenes + n-alkanes were reported. For mixtures with pentane, observed phase behaviors included single-phase liquid as well as liquid–liquid, liquid–liquid–vapor, and liquid–liquid–liquid–vapor regions. Dispersed solids were detected under some conditions as well but not quantified. In this work, small-angle X-ray scattering (SAXS) is used to study nanostructured materials in liquid phases present in AVR + n-pentane mixtures from 50 to 170 °C at mixture bubble pressure. The investigation focuses on the impact of the transition from a single AVR-rich liquid to co-existing pentane-rich and AVR-rich liquids on the nanostructure and the nanostructures most resistant to aggregation as the pentane composition axis is approached. Background scattering subtraction was performed using global mixture composition. The robustness of this assumption with respect to values obtained for coefficients appearing in a two level Beaucage unified equation fit is demonstrated. The nanostructured material is shown to arise at two length scales from 1 to 100 wt % AVR. Smaller nanostructures possess mean radii less than 50 Å, while the larger nanostructures possess mean radii greater than 250 Å. The addition of pentane to the AVR causes an increasingly large fraction of the large and small nanostructures to grow in size. Only nanostructures resistant to aggregation remain in the pentane-rich phase as the 0 wt % AVR axis is approached. Step changes in aggregation identified from changes in average radius of gyration, scattering

  12. Luttinger Liquid, Singular Interaction and Quantum Criticality in Cuprate Materials

    NASA Astrophysics Data System (ADS)

    di Castro, C.; Caprara, S.

    2014-10-01

    With particular reference to the role of the renormalization group (RG) approach and Ward identities (WI's), we start by recalling some old features of the one-dimensional Luttinger liquid as the prototype of non-Fermi-liquid behavior. Its dimensional crossover to the Landau normal Fermi liquid implies that a non-Fermi liquid, as, e.g., the normal phase of the cuprate high temperature superconductors, can be maintained in d > 1 only in the presence of a sufficiently singular effective interaction among the charge carriers. This is the case when, nearby an instability, the interaction is mediated by critical fluctuations. We are then led to introduce the specific case of superconductivity in cuprates as an example of avoided quantum criticality. We will disentangle the fluctuations which act as mediators of singular electron-electron interaction, enlightening the possible order competing with superconductivity and a mechanism for the non-Fermi-liquid behavior of the metallic phase. This paper is not meant to be a comprehensive review. Many important contributions will not be considered. We will also avoid using extensive technicalities and making full calculations for which we refer to the original papers and to the many good available reviews. We will here only follow one line of reasoning which guided our research activity in this field.

  13. Thermal-hydraulic behaviors of vapor-liquid interface due to arrival of a pressure wave

    SciTech Connect

    Inoue, Akira; Fujii, Yoshifumi; Matsuzaki, Mitsuo

    1995-09-01

    In the vapor explosion, a pressure wave (shock wave) plays a fundamental role for triggering, propagation and enhancement of the explosion. Energy of the explosion is related to the magnitude of heat transfer rate from hot liquid to cold volatile one. This is related to an increasing rate of interface area and to an amount of transient heat flux between the liquids. In this study, the characteristics of transient heat transfer and behaviors of vapor film both on the platinum tube and on the hot melt tin drop, under same boundary conditions have been investigated. It is considered that there exists a fundamental mechanism of the explosion in the initial expansion process of the hot liquid drop immediately after arrival of pressure wave. The growth rate of the vapor film is much faster on the hot liquid than that on the solid surface. Two kinds of roughness were observed, one due to the Taylor instability, by rapid growth of the explosion bubble, and another, nucleation sites were observed at the vapor-liquid interface. Based on detailed observation of early stage interface behaviors after arrival of a pressure wave, the thermal fragmentation mechanism is proposed.

  14. Traction and nonequilibrium phase behavior of confined sheared liquids at high pressure

    NASA Astrophysics Data System (ADS)

    Gattinoni, Chiara; Heyes, David M.; Lorenz, Christian D.; Dini, Daniele

    2013-11-01

    Nonequilibrium molecular dynamics simulations of confined model liquids under pressure and sheared by the relative sliding of the boundary walls have been carried out. The relationship between the time-dependent traction coefficient, μ(t), and the state of internal structure of the film is followed from commencement of shear for various control parameters, such as applied load, global shear rate, and solid-liquid atom interaction parameters. Phase diagrams, velocity and temperature profiles, and traction coefficient diagrams are analyzed for pure Lennard-Jones (LJ) liquids and a binary LJ mixture. A single component LJ liquid is found to form semicrystalline arrangements with high-traction coefficients, and stick-slip behavior is observed for high pressures and low-shear velocities, which is shown to involve periodic deformation and stress release of the wall atoms and slip in the solid-liquid boundary region. A binary mixture, which discourages crystallization, gives a more classical tribological response with the larger atoms preferentially adsorbing commensurate with the wall. The results obtained are analyzed in the context of tribology: the binary mixture behaves like a typical lubricant, whereas the monatomic system behaves like a traction fluid. It is discussed how this type of simulation can give insights on the tribological behavior of realistic systems.

  15. Lyotropic Phase Behavior of Polybutadiene-Poly(ethylene oxide) Diblock Copolymers in Ionic Liquids

    SciTech Connect

    Simone, Peter M.; Lodge, Timothy P.

    2008-08-26

    The lyotropic phase behavior of three poly(1,2-butadiene-b-ethylene oxide) diblock copolymers (PB-PEO) with different monomer volume fractions has been studied in two different ionic liquids, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMI][PF{sub 6}]), across the complete concentration range. The ordered microstructures present in the solutions were characterized via small-angle X-ray scattering (SAXS). The phase diagrams for the PB-PEO/ionic liquid solutions include regions corresponding to the classical copolymer microstructures: body-centered-cubic lattices of spheres, hexagonally ordered cylinders, and lamellae. Additionally, the phase diagrams also include wide regions of coexisting microstructures and regions apparently corresponding to a disordered network microstructure. The phase behavior of the PB-PEO copolymers in both ionic liquids was comparable to their previously reported aqueous solution behavior. The temperature dependence of the phase diagrams was very modest, indicative of a highly segregated system. The level of solvent selectivity was also investigated via cryogenic transmission electron microscopy (cryo-TEM) on dilute solutions. On the basis of the morphology of the dilute solution copolymer aggregate structures in the ionic liquid solvents, and on the structural length scales of the concentrated solutions, it was concluded that for PB-PEO [BMI][PF{sub 6}] behaves as a more selective solvent than [EMI][TFSI].

  16. Polymer stabilized liquid crystals: Topology-mediated electro-optical behavior and applications

    NASA Astrophysics Data System (ADS)

    Weng, Libo

    There has been a wide range of liquid crystal polymer composites that vary in polymer concentration from as little as 3 wt.% (polymer stabilized liquid crystal) to as high as 60 wt.% (polymer dispersed liquid crystals). In this dissertation, an approach of surface polymerization based on a low reactive monomer concentration about 1 wt.% is studied in various liquid crystal operation modes. The first part of dissertation describes the development of a vertical alignment (VA) mode with surface polymer stabilization, and the effects of structure-performance relationship of reactive monomers (RMs) and polymerization conditions on the electro-optical behaviors of the liquid crystal device has been explored. The polymer topography plays an important role in modifying and enhancing the electro-optical performance of stabilized liquid crystal alignment. The enabling surface-pinned polymer stabilized vertical alignment (PSVA) approach has led to the development of high-performance and fast-switching displays with controllable pretilt angle, increase in surface anchoring energy, high optical contrast and fast response time. The second part of the dissertation explores a PSVA mode with in-plane switching (IPS) and its application for high-efficiency and fast-switching phase gratings. The diffraction patterns and the electro-optical behaviors including diffraction efficiency and response time are characterized. The diffraction grating mechanism and performance have been validated by computer simulation. Finally, the advantages of surface polymerization approach such as good optical contrast and fast response time have been applied to the fringe-field switching (FFS) system. The concentration of reactive monomer on the electro-optical behavior of the FFS cells is optimized. The outstanding electro-optical results and mechanism of increase in surface anchoring strength are corroborated by the director field simulation. The density and topology of nanoscale polymer protrusions

  17. Asymptotic behavior of a viscous liquid-gas model with mass-dependent viscosity and vacuum

    NASA Astrophysics Data System (ADS)

    Liu, Qingqing; Zhu, Changjiang

    In this paper, we consider two classes of free boundary value problems of a viscous two-phase liquid-gas model relevant to the flow in wells and pipelines with mass-dependent viscosity coefficient. The liquid is treated as an incompressible fluid whereas the gas is assumed to be polytropic. We obtain the asymptotic behavior and decay rates of the mass functions n(x,t), m(x,t) when the initial masses are assumed to be connected to vacuum both discontinuously and continuously, which improves the corresponding result about Navier-Stokes equations in Zhu (2010) [23].

  18. Experimental investigation on the dynamic behavior of the liquid in spherical tanks of a spinning satellite

    NASA Astrophysics Data System (ADS)

    Komatsu, Keiji; Ono, Syuji; Shimizu, Junichiro; Nagashima, Ryuichi

    Two experiments are carried out to investigate the dynamic behavior of the liquid partially filled in spherical tanks of a spinning satellite. One is the simulation test at the spin up phase of the rocket. The other is the sloshing test to analyze the propellant sloshing effects on the satellite attitude control. These experiments are specially set for the Engineering Test Satellite V which has two spherical tanks 37 percent filled with hydrazine, but the results obtained can be applicable to the other problems of the liquid dynamics in spherical tanks.

  19. The critical behavior of the refractive index near liquid-liquid critical points.

    PubMed

    Losada-Pérez, Patricia; Glorieux, Christ; Thoen, Jan

    2012-04-14

    The nature of the critical behavior in the refractive index n is revisited in the framework of the complete scaling formulation. A comparison is made with the critical behavior of n as derived from the Lorentz-Lorenz equation. Analogue anomalies to those predicted for the dielectric constant ε, namely, a leading |t|(2β) singularity in the coexistence-curve diameter in the two-phase region and a |t|(1-α) along the critical isopleth in the one phase region, are expected in both cases. However, significant differences as regards the amplitudes of both singularities are obtained from the two approaches. Analysis of some literature data along coexistence in the two-phase region and along the critical isopleth in the one-phase region provide evidence of an intrinsic effect, independent of the density, in the critical anomalies of n. This effect is governed by the shift of the critical temperature with an electric field, which is supposed to take smaller values at optical frequencies than at low frequencies in the Hz to MHz range. PMID:22502528

  20. Bifurcation analysis of the behavior of partially wetting liquids on a rotating cylinder

    NASA Astrophysics Data System (ADS)

    Lin, Te-Sheng; Rogers, Steven; Tseluiko, Dmitri; Thiele, Uwe

    2016-08-01

    We discuss the behavior of partially wetting liquids on a rotating cylinder using a model that takes into account the effects of gravity, viscosity, rotation, surface tension, and wettability. Such a system can be considered as a prototype for many other systems where the interplay of spatial heterogeneity and a lateral driving force in the proximity of a first- or second-order phase transition results in intricate behavior. So does a partially wetting drop on a rotating cylinder undergo a depinning transition as the rotation speed is increased, whereas for ideally wetting liquids, the behavior only changes quantitatively. We analyze the bifurcations that occur when the rotation speed is increased for several values of the equilibrium contact angle of the partially wetting liquids. This allows us to discuss how the entire bifurcation structure and the flow behavior it encodes change with changing wettability. We employ various numerical continuation techniques that allow us to track stable/unstable steady and time-periodic film and drop thickness profiles. We support our findings by time-dependent numerical simulations and asymptotic analyses of steady and time-periodic profiles for large rotation numbers.

  1. Peculiar liquid-feeding and pathogen transmission behavior of Aedes togoi and comparison with Anopheles sinensis

    NASA Astrophysics Data System (ADS)

    Lee, Sang Joon; Kang, Dooho; Lee, Seung Chul; Ha, Young-Ran

    2016-02-01

    Female mosquitoes transmit various diseases as vectors during liquid-feeding. Identifying the determinants of vector efficiency is a major scientific challenge in establishing strategies against these diseases. Infection rate and transmission efficiency are interconnected with the mosquito-induced liquid-feeding flow as main indexes of vector efficiency. However, the relationship between liquid-feeding characteristics and pathogen remains poorly understood. The liquid-feeding behavior of Aedes togoi and Anopheles sinensis was comparatively investigated in conjunction with vector efficiency via micro-particle image velocimetry. The flow rates and ratio of the ejection volume of Aedes togoi were markedly higher than those of Anophels sinensis. These differences would influence pathogen re-ingestion. Wall shear stresses of these mosquito species were also clearly discriminatory affecting the infective rates of vector-borne diseases. The variations in volume of two pump chambers and diameter of proboscis of these mosquito species were compared to determine the differences in the liquid-feeding process. Liquid-feeding characteristics influence vector efficiency; hence, this study can elucidate the vector efficiency of mosquitoes and the vector-pathogen interactions and contribute to the development of strategies against vector-borne diseases.

  2. Peculiar liquid-feeding and pathogen transmission behavior of Aedes togoi and comparison with Anopheles sinensis.

    PubMed

    Lee, Sang Joon; Kang, Dooho; Lee, Seung Chul; Ha, Young-Ran

    2016-01-01

    Female mosquitoes transmit various diseases as vectors during liquid-feeding. Identifying the determinants of vector efficiency is a major scientific challenge in establishing strategies against these diseases. Infection rate and transmission efficiency are interconnected with the mosquito-induced liquid-feeding flow as main indexes of vector efficiency. However, the relationship between liquid-feeding characteristics and pathogen remains poorly understood. The liquid-feeding behavior of Aedes togoi and Anopheles sinensis was comparatively investigated in conjunction with vector efficiency via micro-particle image velocimetry. The flow rates and ratio of the ejection volume of Aedes togoi were markedly higher than those of Anophels sinensis. These differences would influence pathogen re-ingestion. Wall shear stresses of these mosquito species were also clearly discriminatory affecting the infective rates of vector-borne diseases. The variations in volume of two pump chambers and diameter of proboscis of these mosquito species were compared to determine the differences in the liquid-feeding process. Liquid-feeding characteristics influence vector efficiency; hence, this study can elucidate the vector efficiency of mosquitoes and the vector-pathogen interactions and contribute to the development of strategies against vector-borne diseases. PMID:26839008

  3. Peculiar liquid-feeding and pathogen transmission behavior of Aedes togoi and comparison with Anopheles sinensis

    PubMed Central

    Lee, Sang Joon; Kang, Dooho; Lee, Seung Chul; Ha, Young-Ran

    2016-01-01

    Female mosquitoes transmit various diseases as vectors during liquid-feeding. Identifying the determinants of vector efficiency is a major scientific challenge in establishing strategies against these diseases. Infection rate and transmission efficiency are interconnected with the mosquito-induced liquid-feeding flow as main indexes of vector efficiency. However, the relationship between liquid-feeding characteristics and pathogen remains poorly understood. The liquid-feeding behavior of Aedes togoi and Anopheles sinensis was comparatively investigated in conjunction with vector efficiency via micro-particle image velocimetry. The flow rates and ratio of the ejection volume of Aedes togoi were markedly higher than those of Anophels sinensis. These differences would influence pathogen re-ingestion. Wall shear stresses of these mosquito species were also clearly discriminatory affecting the infective rates of vector-borne diseases. The variations in volume of two pump chambers and diameter of proboscis of these mosquito species were compared to determine the differences in the liquid-feeding process. Liquid-feeding characteristics influence vector efficiency; hence, this study can elucidate the vector efficiency of mosquitoes and the vector-pathogen interactions and contribute to the development of strategies against vector-borne diseases. PMID:26839008

  4. Liquid Fuels: Pyrolytic Degradation and Fire Spread Behavior as Influenced by Buoyancy

    NASA Technical Reports Server (NTRS)

    Ross, Howard D. (Technical Monitor); Yeboah, Yaw D.

    2003-01-01

    This project was conducted by the Combustion and Emission Control Lab in the Engineering Department at Clark Atlanta University under NASA Grant No. NCC3-707. The work aimed at providing data to supplement the ongoing NASA research activities on flame spread across liquid pools by providing flow visualization and velocity measurements especially in the gas phase and gas-liquid interface. During this investigation, the detailed physics of flame spread across liquid pools was revealed using particle image velocimetry (PIV), 3-dimensional Laser Doppler velocimetry (LDV) and high-speed video imaging system (HSVS). Flow fields (front and side views) of both the liquid and gas phases were visually investigated for the three subflash regimes of flame spread behavior. Some interesting findings obtained from the front and side views on flame spread across butanol pools are presented. PIV results showed the size of the transient vortex in the liquid phase near the flame front varied with the initial pool temperature. The transient vortex ahead of the flame front in the gas phase was, for the first time, clearly observed located just within 0-3 mm above the liquid surface and its size was dependent on the initial pool temperature. We calculated the flow velocity at 1 mm below the liquid surface near the flame front and inferred the generation mechanism of the vortex in the gas phase. Finally, after comparison of the flow velocity of the liquid surface and the flame spread rate, a reasonable explanation to the formation mechanism of the pulsating characteristic was proposed. This explanation is compatible with the previous numerical calculations and deductions.

  5. Entropy excess in strongly correlated Fermi systems near a quantum critical point

    SciTech Connect

    Clark, J.W.; Zverev, M.V.; Khodel, V.A.

    2012-12-15

    A system of interacting, identical fermions described by standard Landau Fermi-liquid (FL) theory can experience a rearrangement of its Fermi surface if the correlations grow sufficiently strong, as occurs at a quantum critical point where the effective mass diverges. As yet, this phenomenon defies full understanding, but salient aspects of the non-Fermi-liquid (NFL) behavior observed beyond the quantum critical point are still accessible within the general framework of the Landau quasiparticle picture. Self-consistent solutions of the coupled Landau equations for the quasiparticle momentum distribution n(p) and quasiparticle energy spectrum {epsilon}(p) are shown to exist in two distinct classes, depending on coupling strength and on whether the quasiparticle interaction is regular or singular at zero momentum transfer. One class of solutions maintains the idempotency condition n{sup 2}(p)=n(p) of standard FL theory at zero temperature T while adding pockets to the Fermi surface. The other solutions are characterized by a swelling of the Fermi surface and a flattening of the spectrum {epsilon}(p) over a range of momenta in which the quasiparticle occupancies lie between 0 and 1 even at T=0. The latter, non-idempotent solution is revealed by analysis of a Poincare mapping associated with the fundamental Landau equation connecting n(p) and {epsilon}(p) and validated by solution of a variational condition that yields the symmetry-preserving ground state. Significantly, this extraordinary solution carries the burden of a large temperature-dependent excess entropy down to very low temperatures, threatening violation of the Nernst Theorem. It is argued that certain low-temperature phase transitions, notably those involving Cooper-pair formation, offer effective mechanisms for shedding the entropy excess. Available measurements in heavy-fermion compounds provide concrete support for such a scenario. - Highlights: Black-Right-Pointing-Pointer Extension of Landau

  6. Numerical simulation of solid liquid interface behavior during continuous strip casting process.

    PubMed

    Lee, Changbum; Yoon, Wooyoung; Shin, Seungwon; Lee, Jaewoo; Jang, Bo-Yun; Kim, Joonsoo; Ahn, Youngsoo; Lee, Jinseok

    2013-05-01

    A new metal-strip-casting process called continuous strip-casting (CSC) has been developed for making thin metal strips. A numerical simulation model to help understand solid-liquid interface behavior during CSC has been developed and used to identify the solidification morphologies of the strips and to determine the optimum processing conditions. In this study, we used a modified level contour reconstruction method (LCRM) and the sharp interface method to modify interface tracking, and performed a simulation analysis of the CSC process. The effects of process parameters such as heat-transfer coefficient and extrusion velocity on the behavior of the solid-liquid interface were estimated and used to improve the apparatus. A Sn (Tin) plate of dimensions 200 x 50 x 1 mm3 was successfully produced by CSC for a heat-transfer coefficient of 104 W/m2 K and an extrusion velocity of 0.2 m/s. PMID:23858856

  7. Observation of Fractional Stokes-Einstein Behavior in the Simplest Hydrogen-bonded Liquid

    SciTech Connect

    Herwig, Kenneth W; Molaison, Jamie J; Fernandez-Alonso, F.; Bermejo, F. J.; Turner, John F. C.; McLain, Sylvia E.

    2007-01-01

    Quasielastic neutron scattering has been used to investigate the single-particle dynamics of hydrogen fluoride across its entire liquid range at ambient pressure. For T > 230 K, translational diffusion obeys the celebrated Stokes-Einstein relation, in agreement with nuclear magnetic resonance studies. At lower temperatures, we find significant deviations from the above behavior in the form of a power law with exponent xi = -0.71+/-0.05. More striking than the above is a complete breakdown of the Debye-Stokes-Einstein relation for rotational diffusion. Our findings provide the first experimental verification of fractional Stokes-Einstein behavior in a hydrogen-bonded liquid, in agreement with recent computer simulations.

  8. Behavior of supercooled aqueous solutions stemming from hidden liquid–liquid transition in water

    SciTech Connect

    Biddle, John W.; Holten, Vincent; Anisimov, Mikhail A.

    2014-08-21

    A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid–liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid–liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H{sub 2}O-NaCl and H{sub 2}O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archer and Carter [J. Phys. Chem. B 104, 8563 (2000)], to be consistent with the presence of the metastable liquid–liquid transition. We elucidate the non-conserved nature of the order parameter (extent of “reaction” between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases.

  9. Hydrodynamic Coulomb drag of strongly correlated electron liquids

    NASA Astrophysics Data System (ADS)

    Apostolov, S. S.; Levchenko, A.; Andreev, A. V.

    2014-03-01

    We develop a theory of Coulomb drag in ultraclean double layers with strongly correlated carriers. In the regime where the equilibration length of the electron liquid is shorter than the interlayer spacing the main contribution to the Coulomb drag arises from hydrodynamic density fluctuations. The latter consist of plasmons driven by fluctuating longitudinal stresses, and diffusive modes caused by temperature fluctuations and thermal expansion of the electron liquid. We express the drag resistivity in terms of the kinetic coefficients of the electron fluid. Our results are nonperturbative in interaction strength and do not assume Fermi-liquid behavior of the electron liquid.

  10. Liquid and glass polymorphism in a monatomic system with isotropic, smooth pair interactions.

    PubMed

    Abraham, Joel Y; Buldyrev, Sergey V; Giovambattista, Nicolas

    2011-12-01

    Systems of particles with interactions given by the Jagla core-softened pair potential are known to exhibit water-like thermodynamic anomalies and a liquid-liquid phase transition. The drawback of the Jagla potential is that it is characterized by discontinuous forces acting between particles and thus is not suitable for standard molecular dynamics (MD) simulations. Here we introduce a smooth version of the Jagla potential based on two Fermi distributions and study the properties of a system of particles interacting via this new "Fermi-Jagla" pair potential by using standard MD simulations. We find that the liquid based on the Fermi-Jagla potential retains most of the properties of the liquid based on the original Jagla potential. Namely, it exhibits the following water-like anomalies: (i) decrease of density, (ii) increase of compressibility, κ(T)(T,P), and (iii) increase of isobaric specific heat, C(P)(T,P), upon isobaric cooling, and (iv) increase of diffusivity upon isothermal compression. The Fermi-Jagla potential also exhibits (i') density minima, (ii') compressibility minima, (iii') isobaric specific heat minima upon isobaric cooling, and (iv') diffusivity minima upon isothermal compression. As in the Jagla model case, we find a liquid-liquid phase transition (LLPT) and a liquid-liquid critical point in the equilibrium liquid. Contrary to the case of the original Jagla model liquid, the LLPT line for the Fermi-Jagla potential has a negative slope in the P-T plane that extends well above the crystallization temperature. This feature makes the Fermi-Jagla potential a better candidate to reproduce the behavior of tetrahedral liquids including water, for which the LLPT line observed in simulations has also negative slope. In the glass state, the Fermi-Jagla pair potential results in reversible polyamorphism between low- and high-density amorphous solids (LDA and HDA, respectively). We also find that HDA results from pressure-induced amorphization of the model

  11. The Connection Between Local Icosahedral Order in Metallic Liquids and the Nucleation Behavior of Ordered Phases

    NASA Technical Reports Server (NTRS)

    Kelton, K. F.; Gangopadhyay, A. K.; Lee, G. W.; Hyers, R. W.; Rathz, T. J.; Rogers, J. R.; Robinson, M. B.; Schenk, T.; Simonet, V.

    2003-01-01

    Over fifty years ago, David Turnbull showed that the temperature of many metallic liquids could be decreased far below their equilibrium melting temperature before crystallization occurred. To explain those surprising results, Charles Frank hypothesized that the local structures of undercooled metallic liquids are different from those of crystal phases, containing a significant degree of icosahedral order that is incompatible with extended periodicity. Such structural differences must create a barrier to the formation crystal phases, explaining the observed undercooling behavior. If true, the nucleation from the liquid of phases with extended icosahedral order should be easier. Icosahedral order is often favored in small clusters, as observed recently in liquid-like clusters of pure Pb on the (111) surface of Si[3], for example. However, it has never been shown that an increasing preference for icosahedral phase formation can be directly linked with the development of icosahedral order in the undercooled liquid. Owing to the combination of very recent advances in levitation techniques and the availability of synchrotron x-ray and high flux neutron facilities, this is shown here.

  12. Physics of ultracold Fermi gases revealed by spectroscopies

    NASA Astrophysics Data System (ADS)

    Törmä, Päivi

    2016-04-01

    This article provides a brief review of how various spectroscopies have been used to investitage many-body quantum phenomena in the context of ultracold Fermi gases. In particular, work done with RF spectroscopy, Bragg spectroscopy and lattice modulation spectroscopy is considered. The theoretical basis of these spectroscopies, namely linear response theory in the many-body quantum physics context is briefly presented. Experiments related to the BCS-BEC crossover, imbalanced Fermi gases, polarons, possible pseudogap and Fermi liquid behaviour and measuring the contact are discussed. Remaining open problems and goals in the field are sketched from the perspective how spectroscopies could contribute.

  13. FermiGrid

    SciTech Connect

    Yocum, D.R.; Berman, E.; Canal, P.; Chadwick, K.; Hesselroth, T.; Garzoglio, G.; Levshina, T.; Sergeev, V.; Sfiligoi, I.; Sharma, N.; Timm, S.; /Fermilab

    2007-05-01

    As one of the founding members of the Open Science Grid Consortium (OSG), Fermilab enables coherent access to its production resources through the Grid infrastructure system called FermiGrid. This system successfully provides for centrally managed grid services, opportunistic resource access, development of OSG Interfaces for Fermilab, and an interface to the Fermilab dCache system. FermiGrid supports virtual organizations (VOs) including high energy physics experiments (USCMS, MINOS, D0, CDF, ILC), astrophysics experiments (SDSS, Auger, DES), biology experiments (GADU, Nanohub) and educational activities.

  14. The Influence of Silica Nanoparticles on Ionic Liquid Behavior: A Clear Difference between Adsorption and Confinement

    PubMed Central

    Wang, Yaxing; Li, Cheng; Guo, Xiaojing; Wu, Guozhong

    2013-01-01

    The phase behaviors of ionic liquids (ILs) confined in nanospace and adsorbed on outer surface of nanoparticles are expected to be different from those of the bulk. Anomalous phase behaviors of room temperature ionic liquid tributylhexadecylphosphonium bromide (P44416Br) confined in ordered mesoporous silica nanoparticles with average pore size 3.7 nm and adsorbed on outer surface of the same silica nanoparticles were reported. It was revealed that the melting points (Tm) of confined and adsorbed ILs depressed significantly in comparison with the bulk one. The Tm depressions for confined and adsorbed ILs are 8 °C and 14 °C, respectively. For comparison with the phase behavior of confined P44416Br, 1-butyl-3-methylimidazolium bromide (BmimBr) was entrapped within silica nanopores, we observed an enhancement of 50 °C in Tm under otherwise similar conditions. The XRD analysis indicates the formation of crystalline-like phase under confinement, in contrast to the amorphous phase in adsorbed IL. It was confirmed that the behavior of IL has clear difference. Moreover, the complex π-π stacking and H-bonding do not exist in the newly proposed phosphonium-based IL in comparison with the widely studied imidazolium-based IL. The opposite change in melting point of P44416Br@SiO2 and BmimBr@SiO2 indicates that the cationic species plays an important role in the variation of melting point. PMID:24145752

  15. Understanding the influence of Coulomb and dispersion interactions on the wetting behavior of ionic liquids.

    PubMed

    Rane, Kaustubh S; Errington, Jeffrey R

    2014-11-01

    We study the role of dispersion and electrostatic interactions in the wetting behavior of ionic liquids on non-ionic solid substrates. We consider a simple model of an ionic liquid consisting of spherical ions that interact via Lennard-Jones and Coulomb potentials. Bulk and interfacial properties are computed for five fluids distinguished by the strength of the electrostatic interaction relative to the dispersion interaction. We employ Monte Carlo simulations and an interface-potential-based approach to calculate the liquid-vapor and substrate-fluid interfacial properties. Surface tensions for each fluid are evaluated over a range of temperatures that spans from a reduced temperature of approximately 0.6 to the critical point. Contact angles are calculated at select temperatures over a range of substrate-fluid interaction strengths that spans from the near-drying regime to the wetting regime. We observe that an increase in the relative strength of Coulombic interactions between ions leads to increasing deviation from Guggenheim's corresponding states theory. We show how this deviation is related to lower values of liquid-vapor excess entropies observed for strongly ionic fluids. Our results show that the qualitative nature of wetting behavior is significantly influenced by the competition between dispersion and electrostatic interactions. We discuss the influence of electrostatic interactions on the nature of wetting and drying transitions and corresponding states like behavior observed for contact angles. For all of the fluids studied, we observe a relatively narrow range of substrate-fluid interaction strengths wherein the contact angle is nearly independent of temperature. The influence of the ionic nature of the fluid on the temperature dependence of contact angle is also discussed. PMID:25381536

  16. Bose-Fermi solid and its quantum melting in a one-dimensional optical lattice

    SciTech Connect

    Wang Bin; Das Sarma, S.; Wang, Daw-Wei

    2010-08-15

    We investigate the quantum phase diagram of Bose-Fermi mixtures of ultracold dipolar particles trapped in one-dimensional optical lattices in the thermodynamic limit. With the presence of nearest-neighbor (NN) interactions, a long-ranged ordered crystalline phase (Bose-Fermi solid) is found stabilized in the limit of weak intersite tunneling (J). When J is increased, such a Bose-Fermi solid can be quantum melted into a Bose-Fermi liquid through different procedures, depending on whether the crystalline order is dominated by the NN interaction between fermions or bosons. These properties are qualitatively different from the classical picture of solid-liquid phase transition.

  17. Notch Effect on Tensile Deformation Behavior of 304L and 316L Steels in Liquid Helium and Hydrogen

    NASA Astrophysics Data System (ADS)

    Shibata, K.; Fujii, H.

    2004-06-01

    Tensile tests of type 304L and 316L steels were carried out using round bar specimens with a notch in liquid helium, hydrogen, liquid nitrogen and at ambient temperature. The obtained tensile strengths were compared with the tensile strengths of smooth specimens. For smooth specimens, tensile strength increased with a decrease in temperature and the strengths in liquid helium and hydrogen show similar values in both steels. For notched specimen of 304L steel, tensile strength (including fracture strength) increased noticeably from ambient to liquid nitrogen temperature but showed a large decrease in liquid helium and hydrogen. In liquid hydrogen and helium, the tensile strength is a little lower in liquid hydrogen than in liquid helium and both strengths are lower than tensile strengths of smooth specimens. For notched specimen of 316L steel, an increase in tensile strength from ambient to liquid nitrogen temperature was not so large and a decrease from liquid nitrogen to liquid hydrogen was small. The tensile strengths in liquid helium and hydrogen were nearly same and higher than those of smooth specimens. Different behavior of serration was observed between liquid helium and hydrogen, and between 304L and 316L steels. The reasons for these differences were discussed using computer simulation.

  18. Notch Effect on Tensile Deformation Behavior of 304L and 316L Steels in Liquid Helium and Hydrogen

    SciTech Connect

    Shibata, K.; Fujii, H.

    2004-06-28

    Tensile tests of type 304L and 316L steels were carried out using round bar specimens with a notch in liquid helium, hydrogen, liquid nitrogen and at ambient temperature. The obtained tensile strengths were compared with the tensile strengths of smooth specimens. For smooth specimens, tensile strength increased with a decrease in temperature and the strengths in liquid helium and hydrogen show similar values in both steels. For notched specimen of 304L steel, tensile strength (including fracture strength) increased noticeably from ambient to liquid nitrogen temperature but showed a large decrease in liquid helium and hydrogen. In liquid hydrogen and helium, the tensile strength is a little lower in liquid hydrogen than in liquid helium and both strengths are lower than tensile strengths of smooth specimens. For notched specimen of 316L steel, an increase in tensile strength from ambient to liquid nitrogen temperature was not so large and a decrease from liquid nitrogen to liquid hydrogen was small. The tensile strengths in liquid helium and hydrogen were nearly same and higher than those of smooth specimens. Different behavior of serration was observed between liquid helium and hydrogen, and between 304L and 316L steels. The reasons for these differences were discussed using computer simulation.

  19. Nonmonotonic behaviors of Fano factor in double quantum dot connected with Luttinger liquid electrodes.

    PubMed

    Kawaguchi, Satoshi

    2009-09-30

    In this study, we discuss the behavior of the Fano factor in a double quantum dot (DQD) connected with Luttinger liquid (LL) electrodes. At the Toulouse point, we study the dependence of the Fano factor on the bias voltage, the energy level of the dots, the interdot coupling, and the asymmetry parameter. We show that the behavior of the Fano factor in a DQD is similar to that in a single quantum dot (SQD); however, it behaves nonmonotonically with bias voltage and three local extrema can occur. The condition for the occurrence of nonmonotonic behavior is determined, and it is shown that local extrema result from the mixing of the bare energy levels of the dots caused by the interdot coupling. The influence of the Klein factor on the conductance in a DQD and the limitation of the perturbation calculation for a DQD are discussed. PMID:21832386

  20. Fermi TGF detection map

    NASA Video Gallery

    Fermi’s Gamma-ray Burst Monitor detected 130 TGFs from August 2008 to the end of 2010. Thanks to instrument tweaks, the team has been able to improve the detection rate to several TGFs per week. ...

  1. More Fermi questions

    NASA Astrophysics Data System (ADS)

    Bouffard, Karen

    1999-09-01

    "Fermi" questions are a popular component of most Physics Olympics meets. Asking students to make a reasonable assumption about a problem and give answers in terms of order of magnitude is not only a great challenge for a competition, but is also a valued teaching strategy in the classroom.

  2. Interaction quenches of Fermi gases

    SciTech Connect

    Uhrig, Goetz S.

    2009-12-15

    It is shown that the jump in the momentum distribution of Fermi gases evolves smoothly for small and intermediate times once an interaction between the fermions is suddenly switched on. The jump does not vanish abruptly. The loci in momentum space where the jumps occur are those of the noninteracting Fermi sea. No relaxation of the Fermi surface geometry takes place.

  3. A liquid-delivery device that provides precise reward control for neurophysiological and behavioral experiments.

    PubMed

    Mitz, Andrew R

    2005-10-15

    Behavioral neurophysiology and other kinds of behavioral research often involve the delivery of liquid rewards to experimental subjects performing some kind of operant task. Available systems use gravity or pumps to deliver these fluids, but such methods are poorly suited to moment-to-moment control of the volume, timing, and type of fluid delivered. The design described here overcomes these limitations using an electronic control unit, a pressurized reservoir unit, and an electronically controlled solenoid. The control unit monitors reservoir pressure and provides precisely timed solenoid activation signals. It also stores calibration tables and does on-the-fly interpolation to support computer-controlled delivery calibrated directly in milliliters. The reservoir provides pressurized liquid to a solenoid mounted near the subject. Multiple solenoids, each supplied by a separate reservoir unit and control unit, can be stacked in close proximity to allow instantaneous selection of which liquid reward is delivered. The precision of droplet delivery was verified by weighing discharged droplets on a commercial analytical balance. PMID:16168492

  4. Chromatographic behavior of small organic compounds in low-temperature high-performance liquid chromatography using liquid carbon dioxide as the mobile phase.

    PubMed

    Motono, Tomohiro; Nagai, Takashi; Kitagawa, Shinya; Ohtani, Hajime

    2015-07-01

    Low-temperature high-performance liquid chromatography, in which a loop injector, column, and detection cell were refrigerated at -35ºC, using liquid carbon dioxide as the mobile phase was developed. Small organic compounds (polyaromatic hydrocarbons, alkylbenzenes, and quinones) were separated by low-temperature high-performance liquid chromatography at temperatures from -35 to -5ºC. The combination of liquid carbon dioxide mobile phase with an octadecyl-silica (C18 ) column provided reversed phase mode separation, and a bare silica-gel column resulted in normal phase mode separation. In both the cases, nonlinear behavior at approximately -15ºC was found in the relationship between the temperature and the retention factors of the analytes (van't Hoff plots). In contrast to general trends in high-performance liquid chromatography, the decrease in temperature enhanced the separation efficiency of both the columns. PMID:25917311

  5. On the behavior and stability of a liquid metal in quasi-planar electric contacts

    NASA Astrophysics Data System (ADS)

    Samuilov, S. D.

    2016-06-01

    The contacts between conductors formed under relatively low pressures can be treated as quasi-planar. Melting of the material of such contacts upon the passage of electric current is used in some technological processes, but the behavior of liquid in these conditions has not been analyzed. In this study, such an estimate was obtained for specific conditions appearing under electric-pulse compacting (briquetting) of metal shavings. Analysis of derived relations shows that this estimate is valid for any quasi-2D contacts upon passage of a pulsed current of duration from microseconds to milliseconds. It is shown that the spacing between contact surfaces decreases, the liquid metal is extruded in the lateral directions, and the area of the contact and its conductivity increase. Sausage-type magnetohydrodynamic (MHD) instability and overheating instability do not evolve in these conditions because the instability wavelength is larger than the rated thickness of the molten layer; screw MHD instability can appear in slower processes.

  6. Effect of Enantiomeric Excess on the Phase Behavior of Antiferroelectric Liquid Crystals

    SciTech Connect

    L Pan; B McCoy; S Wang; Z Liu; S Wang; R Pindak; C Huang

    2011-12-31

    Null transmission ellipsometry and resonant x-ray diffraction are employed to study the effect of enantiomeric excess (EE) on the phase behavior of antiferroelectric liquid crystal 10OTBBB1M7. Phase sequence, layer spacing, and pitch of the helical structures of the smectic-C*{sub {alpha}} and smectic-C* phases are studied as a function of temperature and EE. Upon reducing EE, a liquid-gas-type critical point of the smectic-C*{sub {alpha}} to smectic-C* transition is observed, as well as the disappearance of the smectic-C*{sub d4} and the smectic-C*{sub d3} phases. Results are analyzed in a mean-field model.

  7. Synthesis and Liquid-Crystal Behavior of Bent Colloidal Silica Rods.

    PubMed

    Yang, Yang; Chen, Guangdong; Martinez-Miranda, Luz J; Yu, Hua; Liu, Kun; Nie, Zhihong

    2016-01-13

    The design and assembly of novel colloidal particles are of both academic and technological interest. We developed a wet-chemical route to synthesize monodisperse bent rigid silica rods by controlled perturbation of emulsion-templated growth. The bending angle of the rods can be tuned in a range of 0-50° by varying the strength of perturbation in the reaction temperature or pH in the course of rod growth. The length of each arm of the bent rods can be individually controlled by adjusting the reaction time. For the first time we demonstrated that the bent silica rods resemble banana-shaped liquid-crystal molecules and assemble into ordered structures with a typical smectic B2 phase. The bent silica rods could serve as a visualizable mesoscopic model for exploiting the phase behaviors of bent molecules which represent a typical class of liquid-crystal molecules. PMID:26700616

  8. Peculiar surface behavior of some ionic liquids based on active pharmaceutical ingredients

    NASA Astrophysics Data System (ADS)

    Restolho, José; Mata, José Luis; Saramago, Benilde

    2011-02-01

    The ionic liquids based on biologically active cations and anions, commonly designated by ionic liquids based on active pharmaceutical ingredients (ILs-APIs), are interesting compounds for use in pharmaceutical applications. Lidocaine docusate, ranitidine docusate, and didecyldimethylammonium ibuprofen are examples of promising ILs-APIs that were recently synthesized. They were submitted to biological testing and calorimetric measurements, but nothing is known about their surface properties. In this work, we measured the surface tension and the contact angles on both hydrophilic and hydrophobic surfaces in a temperature range as wide as possible. Based on the wettability data, the polarity fractions were estimated using the Fowkes theory. The peculiar surface behavior observed was tentatively attributed to the presence of mesophases.

  9. Effect of throttling on interface behavior and liquid residuals in weightlessness. [in flat-bottomed tank

    NASA Technical Reports Server (NTRS)

    Symons, E. P.

    1974-01-01

    An experimental investigation was conducted to study liquid-vapor interface behavior and subsequent vapor ingestion in a flat-bottomed cylindrical tank following a single-step throttling in outflow rate in a weightless environment. A throttling process in which the final Weber number was one-tenth of the initial Weber number tended to excite large-amplitude symmetric slosh, with the amplitude generally increasing as initial Weber number increased. As expected, liquid residuals were lower than those obtained without throttling and, for moderate values of initial Weber number, could be adequately predicted by assuming that all draining took place at the final Weber number. At large values of Weber number, residuals tended to be lower than this predicted value.

  10. Peculiar surface behavior of some ionic liquids based on active pharmaceutical ingredients.

    PubMed

    Restolho, José; Mata, José Luis; Saramago, Benilde

    2011-02-21

    The ionic liquids based on biologically active cations and anions, commonly designated by ionic liquids based on active pharmaceutical ingredients (ILs-APIs), are interesting compounds for use in pharmaceutical applications. Lidocaine docusate, ranitidine docusate, and didecyldimethylammonium ibuprofen are examples of promising ILs-APIs that were recently synthesized. They were submitted to biological testing and calorimetric measurements, but nothing is known about their surface properties. In this work, we measured the surface tension and the contact angles on both hydrophilic and hydrophobic surfaces in a temperature range as wide as possible. Based on the wettability data, the polarity fractions were estimated using the Fowkes theory. The peculiar surface behavior observed was tentatively attributed to the presence of mesophases. PMID:21341864

  11. Thermodynamics and Phase Behavior of Phosphonated Block Copolymers Containing Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Jung, Ha Young; Park, Moon Jeong

    Charge-containing copolymers have drawn intensive attention in recent years for their uses in wide range of electrochemical devices such as fuel cells, lithium batteries and actuators. Particularly, the creation of microphase-separated morphologies in such materials by designing them in block and graft configurations has been the subject of extensive studies, in order to establish a synergistic means of optimizing ion transport properties and mechanical integrity. Interest in this topic has been further stimulated by intriguing phase behavior from charge-containing polymers, which was not projected from conventional phase diagrams of non-ionic polymers. Herein, we investigate thermodynamics and phase behavior of a set of phosphonated block copolymers. By synthesizing low-molecular weight samples with degree of polymerization (N) <35, we observed order-disorder transition that enabled us to estimate effective Flory-Huggins interaction parameters (χ) by using random phase approximation. We further examined the systems by adding various ionic liquids, where noticeable increases in χ values and modulated microphase separation behavior were observed. The morphology-conductivity relationship has been elucidated by taking into account the segmental motion of polymer chains, volume of conducting phases, and the molecular interactions between phosphonated polymer chains and cations of ionic liquids.

  12. Phase behavior of chromonic liquid crystal mixtures of Sunset Yellow and Disodium Cromoglycate

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Akihiro; Smith, Gregory; Yi, Youngwoo; Xu, Charles; Biffi, Silvia; Serra, Francesca; Bellini, Tommaso; Clark, Noel

    2014-03-01

    Chromonic liquid crystals (CLCs) are formed when planar molecules dissolved in water stack into rod-like aggregates that can order as liquid crystals. Isotropic, nematic, and M-phases can be observed depending on the degree of molecular orientational and positional order by variation of the CLC concentration. We focused on mixtures of two well-known CLCs, Sunset Yellow, a food dye, and disodium cromoglycate (DSCG), an asthma medication. In order to study the phase behaviors of these mixtures, we observed their textures in glass cells and capillaries using polarized light microscopy. We report here a ternary phase diagram describing the complete phase behavior of the CLC mixtures. We observed a variety of phase behaviors depending on species ratio and concentration. In the isotropic phase, no clear phase separation of the two dyes was observed, while separation did occur in many nematic and M-phase combinations. We will also describe phase observations made using a light spectroscopy and bulk centrifugal partitioning. Grant support: NSF DMR 1207606 and NSF MRSEC DMR-0820579.

  13. Structural effects of anions and cations on the aggregation behavior of ionic liquids in aqueous solutions.

    PubMed

    Wang, Huiyong; Wang, Jianji; Zhang, Shibiao; Xuan, Xiaopeng

    2008-12-25

    The formation of ionic liquids aggregates in aqueous solution is of great importance to the future applications of ionic liquids. In this work, aggregation behavior of 1-alkyl-3-methylimidazolium salts [C8mim]X (X = Cl, Br, [NO3], [CH3COO], [CF3COO], [CF3SO3], and [ClO4]), 1-octyl-4-methylpyridinium bromide (4m-[C8pyr]Br), and 1-methyl-1-octylpyrrolidinium ([C8mpyrr]Br) has been investigated in aqueous solutions by conductivity, volume, fluorescence, dynamic light scattering, and transmission electron microscopy. The critical aggregation concentration (CAC), ionization degree of the aggregates alpha, the standard Gibbs energy of aggregation deltaG(m)degrees, the average aggregation number N, the apparent molar volumes at critical aggregation concentration V(phi,CAC), the apparent molar volumes in aggregation phase V(phi)mic, and the change of the apparent molar volumes upon aggregation deltaV(phi,m), have been derived from the experimental data for these ionic liquids. It is found that both nature of the anions and ring type of the cations significantly affect the aggregation in aqueous solution. The anionic effect basically follows the Hofmeister series, and the ability of anionic hydration is predominant for the aggregation behavior of the ionic liquids. Hydrophobicity and steric hindrance of the cations as well as binding strength of the cations with the anions are suggested to play important roles in the aggregation of [C8mim]Br, 4m-[C8pyr]Br, and [C8mpyrr]Br. The investigated ILs were found to form spherical aggregates. Structures of anions and cations have very weak effects on the morphology, but they do affect the aggregate sizes. PMID:19367863

  14. Corrosion behavior of cold-worked austenitic stainless steels in liquid lead-bismuth eutectic

    NASA Astrophysics Data System (ADS)

    Kurata, Yuji

    2014-05-01

    The effect of cold working on the corrosion behavior of austenitic stainless steels in liquid lead-bismuth eutectic (LBE) was studied to develop accelerator-driven systems for the transmutation of long-lived radioactive wastes and lead-bismuth cooled fast reactors. Corrosion tests on solution-treated, 20% cold-worked and 50% cold-worked 316SS and JPCA (15Cr-15Ni-Ti) were conducted in oxygen-controlled LBE. Slight ferritization caused by Ni dissolution and Pb-Bi penetration were observed for all specimens in the corrosion test conducted at 500 °C for 1000 h in liquid LBE with an intermediate oxygen concentration (1.4 × 10-7 wt.%). In the corrosion test performed at 550 °C for 1000 h in liquid LBE with a low oxygen concentration (4.2 × 10-9 wt.%), the depth of the ferritization of 316SS and JPCA increased with the extent of cold working. Only oxidation was observed in the corrosion test that was performed at 550 °C for 1000 h in liquid LBE with a high oxygen concentration (approximately 10-5 wt.%). Cold working accelerated the formation of the double layer oxide and increased the thickness of the oxide layer slightly. In contrast, the ferritization accompanied by Pb-Bi penetration was widely observed with oxidation for all specimens corrosion tested at 550 °C for 3000 h under the high-oxygen condition. Cold working increased the depth of the ferritization of 316SS and JPCA. It is considered that cold working accelerated the ferritization and Pb-Bi penetration through the enhanced dissolution of Ni into LBE due to an increase in the dislocation density under conditions in which the protective oxide layer was not formed in liquid LBE.

  15. NMR evidence of anisotropic Kondo liquid behavior in CeIrIn5

    NASA Astrophysics Data System (ADS)

    Shockley, A. C.; Shirer, K. R.; Crocker, J.; Dioguardi, A. P.; Lin, C. H.; Nisson, D. M.; apRoberts-Warren, N.; Klavins, P.; Curro, N. J.

    2015-08-01

    We report detailed Knight-shift measurements of the two indium sites in the heavy-fermion compound CeIrIn5 as a function of temperature and field orientation. We find that the Knight-shift anomaly is orientation dependent, with a crossover temperature T* that varies by 50% as the field is rotated from (001) to (100). This result suggests that the hybridization between the Ce 4 f states and the itinerant conduction electrons is anisotropic, a result that reflects its collective origin, and may lead to anisotropic Kondo liquid behavior and unconventional superconductivity.

  16. Nanoscale viscoplastic behavior of smectic liquid crystals and its application in nanolithography

    NASA Astrophysics Data System (ADS)

    Schulz, Benjamin; Steffen, Paul; Bahr, Christian

    2014-02-01

    We report a unique combination of properties of smectic liquid crystal films that can be described as a viscoplastic behavior on the nanoscale: On the one hand, the films preserve imprinted surface patterns despite being permeated by a directed molecular flow of the film material. On the other hand, their surface morphology can easily be manipulated using an atomic force microscopy tip. Our results demonstrate a controlled molecular-scale deposition of material on the film surface, thereby enabling nanolithographic surface modification of a fluid material.

  17. Nanoscale viscoplastic behavior of smectic liquid crystals and its application in nanolithography

    SciTech Connect

    Schulz, Benjamin Steffen, Paul Bahr, Christian

    2014-02-21

    We report a unique combination of properties of smectic liquid crystal films that can be described as a viscoplastic behavior on the nanoscale: On the one hand, the films preserve imprinted surface patterns despite being permeated by a directed molecular flow of the film material. On the other hand, their surface morphology can easily be manipulated using an atomic force microscopy tip. Our results demonstrate a controlled molecular-scale deposition of material on the film surface, thereby enabling nanolithographic surface modification of a fluid material.

  18. Crossover between short- and long-time behavior of stress fluctuations and viscoelasticity of liquids.

    PubMed

    Hess, Siegfried; Kröger, Martin; Evans, Denis

    2003-04-01

    An effective viscosity coefficient is introduced based on definite time averages of equilibrium stress fluctuations rather than stress correlations. Analysis of this quantity via molecular dynamics of a simple model liquid reveals a crossover between the expected short-time elastic and the long-time viscous behavior with increasing averaging time. The procedure allows us to extract the zero-rate shear viscosity when the averaging time becomes one order of magnitude larger than the relevant relaxation time. A relationship between this effective viscosity and the dynamic viscosities is established. PMID:12786406

  19. Light Responsive Microstructured Surfaces of Liquid Crystalline Network with Shape Memory and Tunable Wetting Behaviors.

    PubMed

    Wu, Zi Liang; Wang, Zhi Jian; Keller, Patrick; Zheng, Qiang

    2016-02-01

    Using adaptive soft materials to fabricate microstructured surfaces renders them with tunable topographic feature and thus controllable physical properties. Here, light responsive microstructured surfaces are reported with shape memory and tunable wetting behaviors; the surfaces are covered with micropillar arrays and constructed by lightly crosslinked azo-containing liquid crystalline network (LCN). UV light irradiation induces 25% contraction in length of the micropillars along their long axes and, as a consequence, the variations of topographic feature and wetting behavior of the surfaces. In addition, the LCNs exhibit shape memory properties, which can freeze the temporary topographic feature of microstructured surfaces (formed under UV irradiation and relatively high temperature) and enable application of their functionalities at mild conditions. This light responsiveness makes it feasible to remotely and precisely tune the local regions of microstructured surfaces, which should broaden the applications of adaptive surfaces in regulating the wetting, optical, and adhesion properties in selected regions. PMID:26676211

  20. Frustration and time-reversal symmetry breaking for Fermi and Bose-Fermi systems

    NASA Astrophysics Data System (ADS)

    Sacha, Krzysztof; Targońska, Katarzyna; Zakrzewski, Jakub

    2012-05-01

    The modulation of an optical lattice potential that breaks time-reversal symmetry enables the realization of complex tunneling amplitudes in the corresponding tight-binding model. For a superfluid Fermi gas in a triangular lattice potential with complex tunnelings, the pairing function acquires a complex phase, so the frustrated magnetism of fermions can be realized. Bose-Fermi mixtures of bosonic molecules and unbound fermions in the lattice also show interesting behavior. Due to boson-fermion coupling, the fermions become enslaved by the bosons and the corresponding pairing function takes the complex phase determined by the bosons. In the presence of bosons the Fermi system can reveal both gapped and gapless superfluidity.

  1. Dynamic Behavior of the Liquid Flow Coalescing with a Droplet in Hydrophobic Microchannels.

    PubMed

    Rong, Chen; Shuzhe, Li; Hong, Wang; Qiang, Liao; Xun, Zhu; Qinlin, Fan; Xuefeng, He; Zhibin, Wang

    2015-04-01

    In this study, the dynamic behavior of the moving liquid column coalescing with a sessile droplet in a hydrophobic microchannel under pressure driven flow conditions is numerically investigated using coupled Volume of Fluid with Level Set (CLSVOF) interface tracking method implemented in ANSYS-Fluent 14.5 in conjunction with the continuum surface force (CSF) model. Numerical result reveals that the coalescence between the moving liquid column and droplet can accelerate the original liquid column movement. Effects of the wettability, head pressure, and droplet size and position are also investigated. It is found that the velocity increment ratio increases with increasing the contact angle and decreasing the head pressure. Larger droplet and smaller distance between the droplet and inlet can result in a larger velocity increment ratio as a result of higher surface energy and lower viscous dissipation energy. The maximum velocity increment ratio of 0.17 is obtained with a 10000-µm3 droplet that is positioned at 200 µm in a microchannel with 100 µm in width and 300 µm in length and contact angle of 120°. PMID:26353515

  2. Shen-Zhi-Ling Oral Liquid Improves Behavioral and Psychological Symptoms of Dementia in Alzheimer's Disease

    PubMed Central

    Wang, Qiudong; Kwak, Shin; Song, Yu; Qin, Baofeng; Wang, Mingzhe; Yamamoto, Yoshiharu

    2014-01-01

    We evaluated the effects of the traditional Chinese medicine (TCM) Shen-Zhi-Ling oral liquid (SZL) on the behavioral and psychological symptoms of dementia (BPSD) in patients with Alzheimer's disease (AD). Among 98 patients with AD and BPSD enrolled (mean age, 57.2 ± 8.9 years old), 91 (M = 55, F = 36; mean age, 57.2 ± 9.7 years old) completed the study. Patients took either SZL (n = 45) or placebo granules (n = 46) in a double-blind manner for 20 weeks while maintaining other anticognitive medications unchanged. Changes in BPSD between week 0, week 10, week 20, and week 25 were assessed using the behavioral pathology in Alzheimer's disease (BEHAVE-AD) rating scale and the neuropsychiatric inventory (NPI), detrended fluctuation analysis (DFA) represented by diurnal activity (DA), evening activity (EA), and nocturnal activity (NA) according to actigraphic recordings. SZL but not placebo oral liquid delayed the development of BPSD significantly according to the changes in some of the clinical scores and the EA and NA parameters of DFA at week 20 compared with week 0. No side effects were observed in laboratory tests. The results indicate that SZL might delay the development of BPSD in AD patients and thus is a potentially suitable drug for long-term use. PMID:24959193

  3. Differential dynamic behaviors of undulatory nematodes in liquid vs. soft gel environment

    NASA Astrophysics Data System (ADS)

    Park, Jin-Sung; Shin, Jennifer H.

    2015-03-01

    Caenorhabditis elegans (C. elegans) is an undulatory nematode which exhibits two distinct locomotion types of swimming and crawling. Although in its natural habitat C. elegans lives in complex fluidic environment, our current understanding has been limited to the behavior of C. elegans in a simple Newtonian fluid. Here, we present some experimental results on the penetrating behavior of C. elegans at the interface from liquid to solid environment. Once C. elegans, which otherwise swims freely in a liquid, makes a contact to the solid gel boundary, it begins to penetrate vertically to the surface by changing its stroke motion characterized by a stiffer body shape and a slow stroke frequency. The particle image velocimetry (PIV) analysis reveals the flow streamlines produced by the stroke of worm. For the worm that crawls on a solid surface, we utilize a technique of traction force microscopy (TFM) to find that the crawling nematode forms localized force islands along the body where makes direct contacts to the gel surface. This work was supported by the National Research Foundation (NRF) Grant 2013R1A1A2012420 and 2010-0016886.

  4. Protonic Ammonium Nitrate Ionic Liquids and Their Mixtures: Insights into Their Thermophysical Behavior.

    PubMed

    Canongia Lopes, José N; Esperança, José M S S; de Ferro, André Mão; Pereiro, Ana B; Plechkova, Natalia V; Rebelo, Luis P N; Seddon, Kenneth R; Vázquez-Fernández, Isabel

    2016-03-10

    This study is centered on the thermophysical characterization of different families of alkylammonium nitrate ionic liquids and their binary mixtures, namely the determination at atmospheric pressure of densities, electric conductivities and viscosities in the 288.15 < T/K < 353.15 range. First, measurements focusing on ethylammonium, propylammonium and butylammonium nitrate systems, and their binary mixtures, were determined. These were followed by studies involving binary mixtures composed of ethylammonium nitrate (with three hydrogen bond donor groups) and different homologous ionic liquids with differing numbers of hydrogen bond donor groups: diethylammonium nitrate (two hydrogen bond donors), triethylammonium nitrate (one hydrogen bond donor) and tetraethylammonium nitrate (no hydrogen bond donors). Finally, the behavior of mixtures with different numbers of equivalent carbon atoms in the alkylammonium cations was analyzed. The results show a quasi-ideal behavior for all monoalkylammonium nitrate mixtures. In contrast, the other mixtures show deviations from ideality, namely when the difference in the number of carbon atoms present in the cations increases or the number of hydrogen bond donors present in the cation decreases. Overall, the results clearly show that, besides the length and distribution of alkyl chains present in a cation such as alkylammonium, there are other structural and interaction parameters that influence the thermophysical properties of both pure compounds and their mixtures. PMID:26886188

  5. Temperature Behavior of Electric Relaxational Effects due to Ionic Conductivity in Liquid Lactones

    NASA Astrophysics Data System (ADS)

    Świergiel, J.; Jadżyn, J.

    2012-05-01

    This paper concerns the studies of temperature and frequency behavior of the complex impedance, electric modulus, and electric conductivity due to an ionic current in liquid γ-butyrolactone (GBL) and γ-valerolactone (GVL). The frequency of the applied electric stimulus (500 Hz to 5 MHz) corresponds to the static dielectric regime of the lactones. The studies were performed in the temperature range of 263 K to 313 K. It was shown that in the static dielectric case, the dc ionic conductivity ( σ DC) and the static dielectric permittivity {(\\varepsilon_s)} determine the relaxational behavior of the impedance ( Z*) and the electric modulus ( M*) of the molecular liquids and both spectra are of the Debye-type characterized by the same conductivity relaxation time ( τ σ ). Both σ DC and τ σ of GBL and GVL fairly well fulfill an Arrhenius temperature dependence with very similar values of the thermal activation energy {E_{σ_DC} ≈ E_{tau_σ} ≈ 25 kJ . mol^{-1}} . The temperature dependence of the static dielectric permittivity and its temperature derivative is analyzed and interpreted in terms of the dipolar aggregation in the studied lactones.

  6. Strain-cycling fatigue behavior of ten structural metals tested in liquid helium (4 K), in liquid nitrogen (78 K), and in ambient air (300 K)

    NASA Technical Reports Server (NTRS)

    Nachtigall, A. J.

    1974-01-01

    Strain-cycling fatigue behavior of 10 different structural alloys and metals was investigated in liquid helium (4 K), in liquid nitrogen (78 K), and in ambient air (300 K). At high cyclic lives, fatigue resistance increased with decreasing temperature for all the materials investigated. At low cyclic lives, fatigue resistance generally decreased with decreasing temperature for the materials investigated. Only for Inconel 718 did fatigue resistance increase with decreasing temperature over the entire life range investigated. Comparison of the experimental fatigue behavior with that predicted by the Manson method of universal slopes showed that the fatigue behavior of these materials can be predicted for cryogenic temperatures by using material tensile properties obtained at those same temperatures.

  7. GRB Studies with Fermi

    NASA Technical Reports Server (NTRS)

    Meegan, Charles A.

    2008-01-01

    This slide presentation reviews the studies of Gamma Ray Bursts (GRB) with the Fermi Gamma Ray Space Telescope. Included are pictures of the observatory, with illustrations of the Large Area Telescope (LAT), and the Gamma-ray Burst Monitor (GBM) including information about both their capabilities. Graphs showing the GBM count rate over time after the GBM trigger for three GRBs, preliminary charts showing the multiple detector light curves the spectroscopy of the main LAT peak and the spectral evolution of GRB 080916C Burst Temporally-extended LAT emission.

  8. Angle resolved photoemission study of Fermi surfaces and single-particle excitations of quasi-low dimensional materials

    NASA Astrophysics Data System (ADS)

    Gweon, Gey-Hong

    Using angle resolved photoemission spectroscopy (ARPES) as the main experimental tool and the single particle Green's function as the main theoretical tool, materials of various degrees of low dimensionality and different ground states are studied. The underlying theme of this thesis is that of one dimensional physics, which includes charge density waves (CDW's) and the Luttinger liquid (LL). The LL is the prime example of a lattice non-Fermi liquid (non-FL) and CDW fluctuations also give non-FL behaviors. Non-FL physics is an emerging paradigm of condensed matter physics. It is thought by some researchers that one dimensional LL behavior is a key element in solving the high temperature superconductivity problem. TiTe2 is a quasi-2 dimensional (quasi-2D) Fermi liquid (FL) material very well suited for ARPES lineshape studies. I report ARPES spectra at 300 K which show an unusual behavior of a peak moving through the Fermi energy (EF). I also report a good fit of the ARPES spectra at 25 K obtained by using a causal Green's function proposed by K. Matho. SmTe3 is a quasi-2D CDW material. The near EF ARPES spectra and intensity map reveal rich details of an anisotropic gap and imperfectly nested Fermi surface (FS) for a high temperature CDW. A simple model of imperfect nesting can be constructed from these data and predicts a CDW wavevector in very good agreement with the value known from electron diffraction. NaMo6O17 and KMo 6O17 are also quasi-2D CDW materials. The "hidden nesting" or "hidden 1 dimensionality" picture for the CDW is confirmed very well by our direct image of the FS. K0.3MoO3, the so-called "blue bronze," is a quasi-1 dimensional (quasi-1D) CDW material. Even in its metallic phase above the CDW transition temperature, its photoemission spectra show an anomalously weak intensity at EF and no clear metallic Fermi edge. I compare predictions of an LL model and a CDW fluctuation model regarding these aspects, and find that the LL scenario explains them

  9. Robustness of the periodic and chaotic orientational behavior of tumbling nematic liquid crystals.

    PubMed

    Heidenreich, Sebastian; Ilg, Patrick; Hess, Siegfried

    2006-06-01

    The dynamical behavior of molecular alignment strongly affects physical properties of nematic liquid crystals. A theoretical description can be made by a nonlinear relaxation equation of the order parameter and leads to the prediction that rather complex even chaotic orientational behavior occur. Here the influence of fluctuating shear rates on the orientational dynamics especially on chaotic solutions is discussed. With the help of phase portraits and time evolution diagrams, we investigated the influence of different fluctuation strengths on the flow aligned, isotropic, and periodic solutions. To explore the effect of fluctuations on the chaotic behavior, we calculated the largest Lyapunov exponent for different fluctuation strengths. We found in all cases that small fluctuations of the shear rate do not affect the basic features of the dynamics of tumbling nematics. Furthermore, we present an amended potential modeling the isotropic to nematic transition and discuss the equivalence and difference to the commonly used Landau-de Gennes potential. In contrast to the Landau-de Gennes potential, our potential has the advantage to restrict the order parameter to physically admissible values. In the case of extensional flow, we show that the amended potential leads for increasing extensional rate to a better agreement with experimental results. PMID:16906852

  10. Effects of Flexibility on Liquid Crystalline Polymer Behavior: The Nematic Broken Road

    NASA Astrophysics Data System (ADS)

    Leal, L. Gary; Charuv, Chaubal

    1998-03-01

    A new theory for Liquid Crystalline Polymers is developed and its behavior in simple shear flow is analyzed. The theory accounts for molecular flexibility by employing a microstructure consisting of two rigid rods linked by a joint with a tunable stiffness. The probability distribution function equation for the orientation of the arms of the broken rod is derived. The adaptation of the Smoothed Particle Hydrodynamics (SPH) technique for obtaining numerical solutions to this theory is detailed. The behavior of the theory at equilibrium is derived analytically and compared with numerical results; the SPH technique is then used to obtain results in flow. It is found that in the limit of a nearly stiff joint, the model gives behavior that is very similar to that of rigid rod polymers, the only difference being a lesser tendency to tumble due to greater variation in the order parameter. For nearly free joints, the shear flow induces interesting dynamics for the transition between states with the arms outstretched and those where they are folded up (so-called ''hairpins'' of main-chain LCPs).

  11. Micellization behavior of morpholinium-based amide-functionalized ionic liquids in aqueous media.

    PubMed

    Kamboj, Raman; Bharmoria, Pankaj; Chauhan, Vinay; Singh, Sukhprit; Kumar, Arvind; Mithu, Venus Singh; Kang, Tejwant Singh

    2014-08-26

    Morpholinium-based amide-functionalized ionic liquids (ILs) [C(n)AMorph][Br], where n = 8, 12, and 16, have been synthesized and characterized for their micellization behavior in aqueous medium using a variety of state of the art techniques. The adsorption and micellization behavior of [CnAMorph][Br] ILs at the air-solution interface and in the bulk, respectively, has been found to be much better compared to that observed for nonfunctionalized homologous ILs and conventional cationic surfactants, as shown by the comparatively higher adsorption efficiency, lower surface tension at the critical micelle concentraiton (γ(cmc)), and much lower critical micelle concentration (cmc) for [C(n)AMorph][Br] ILs. Conductivity measurements have been performed to obtain the cmc, degree of counterion binding (β), and standard free energy of micellization (ΔG(m)°). Isothermal titration calorimetry has provided information specifically about the thermodynamics of micellization, whereas steady-state fluorescence has been used to obtain the cmc, micropolarity of the cybotactic region, and aggregation number (N(agg)) of the micelles. Both dynamic light scattering and atomic force microscopy have provided insights into the size and shape of the micelles. 2D (1)H-(1)H nuclear Overhauser effect spectroscopy experiments have provided insights into the structure of the micelle, where [C16AMorph][Br] has shown distinct micellization behavior as compared to [C8AMorph][Br] and [C12AMorph][Br] in corroboration with observations made from other techniques. PMID:25062465

  12. Robustness of the periodic and chaotic orientational behavior of tumbling nematic liquid crystals

    SciTech Connect

    Heidenreich, Sebastian; Hess, Siegfried; Ilg, Patrick

    2006-06-15

    The dynamical behavior of molecular alignment strongly affects physical properties of nematic liquid crystals. A theoretical description can be made by a nonlinear relaxation equation of the order parameter and leads to the prediction that rather complex even chaotic orientational behavior occur. Here the influence of fluctuating shear rates on the orientational dynamics especially on chaotic solutions is discussed. With the help of phase portraits and time evolution diagrams, we investigated the influence of different fluctuation strengths on the flow aligned, isotropic, and periodic solutions. To explore the effect of fluctuations on the chaotic behavior, we calculated the largest Lyapunov exponent for different fluctuation strengths. We found in all cases that small fluctuations of the shear rate do not affect the basic features of the dynamics of tumbling nematics. Furthermore, we present an amended potential modeling the isotropic to nematic transition and discuss the equivalence and difference to the commonly used Landau-de Gennes potential. In contrast to the Landau-de Gennes potential, our potential has the advantage to restrict the order parameter to physically admissible values. In the case of extensional flow, we show that the amended potential leads for increasing extensional rate to a better agreement with experimental results.

  13. Liquid Fuels: Pyrolytic Degradation and Fire Spread Behavior as Influenced by Buoyancy

    NASA Technical Reports Server (NTRS)

    Yeboah, Yaw D.; Malbrue, Courtney; Savage, Melane; Liao, Bo; Ross, Howard D. (Technical Monitor)

    2001-01-01

    This work is being conducted by the Combustion and Emission Control Lab in the Engineering Department at Clark Atlanta University under NASA Grant No. NCC3-707. The work aims at providing data to supplement the ongoing NASA research activities on fire spread across liquid pools by providing flow visualization and velocity measurements especially in the gas phase and gas-liquid interface. The fabrication, installation, and testing were completed during this reporting period. The system shakedown and detailed quantitative measurements with High Speed Video and Particle Image Velocimetry (PIV) systems using butanol as fuel were performed. New and interesting results, not previously reported in the literature, were obtained from the experiments using a modified NASA tray and butanol as fuel. Three distinct flame spread regimes, as previously reported, were observed. These were the pseudo-uniform regime below 20 C, the pulsating regime between 22 and 30 C and the uniform regime above about 31 C. In the pulsating regime the jump velocity appeared to be independent of the pool temperature. However, the retreat velocity between jumps appeared to depend on the initial pool temperature. The flame retreated before surging forwards with increasing brightness. Previous literature reported this phenomenon only under microgravity conditions. However, we observed such behavior in our normal gravity experiments. Mini-pulsations behind the flame front were also observed. Two or three of these pulsations were observed within a single flame front pulsating time period. The velocity vector maps of the gas and liquid phases ahead, during, and behind the flame front were characterized. At least one recirculation cell was observed right below the flame front.The size of the liquid phase vortex (recirculation cell) below the flame front appeared to decrease with increasing initial pool temperature. The experiments also showed how multiple vortices developed in the liquid phase. A large

  14. Experimental Determination of the Partitioning Behavior of Noble Gases Between Carbonate and Silicate Liquids

    NASA Astrophysics Data System (ADS)

    Burnard, P.; Koga, K. T.

    2010-12-01

    weeks) between quench and analysis. The second stage was designed to extract noble gases by thermal decarbonation of the carbonate glass. The metal of the capsule itself was also measured, but this never contained any noble gas above blank levels. Our preliminary results show that the noble gases do not preferentially partition into carbonate liquids compared to silicate liquids: DHe(carbonate/silicate)=0.3-1.4 and DAr(carbonate/silicate)=0.15-0.17 (at 1 GPa) In a two phase carbonate - silicate system, the noble gases will essentially reside in the silicate portion of the system (particularly given that carbonatite liquids will represent a small volume fraction of the two phase magma). This partitioning behavior could nevertheless separate - decouple - noble gas isotope systematics from lithophile isotopes (Sr, Nd, Pb etc) as a significant fraction of these elements could partition into the carbonate phase while noble gases remain in the silicate portion of the magma. Further work investigating pressure, temperature and compositional effects on the noble gas partition coefficients is planned. References 1. Burnard, P., Toplis, M. J. and Medynski, S. (2010) Geochim. Cosmochim. Acta 74: 1672-1683.

  15. Hard-sphere behavior in the dynamics of all mono-atomic liquids at the de Gennes minimum

    NASA Astrophysics Data System (ADS)

    Montfrooij, Wouter

    2016-08-01

    We show that the position of the de Gennes minimum in scattering spectra, where the dynamics of liquids shows down, is given by a hard-sphere expression for a range of mono-atomic liquids that crystallize in a close packed structure. This expression relates the position of the minimum to the number density of the liquid, without any adjustable or unknown parameters. We argue that this implies that a liquid can be viewed as a close packed structure of the cages that represent the confinement of atoms by their neighbors. We further show that some metals deviate from this expression, namely those metals that crystallize in a structure that is not close packed. Our expression should prove very useful in identifying what liquids to study in inelastic scattering experiments given that deviations from normal fluid behavior can already be predicted based on the peak position of the static structure factor.

  16. Self-aggregation and liquid crystalline behavior of new ester-functionalized quinuclidinolium surfactants.

    PubMed

    Bhadani, Avinash; Endo, Takeshi; Koura, Setsuko; Sakai, Kenichi; Abe, Masahiko; Sakai, Hideki

    2014-08-01

    A new type of ester-based cationic surfactant having a quinuclidinolium headgroup has been synthesized starting from linear fatty alcohols and has been characterized using spectroscopic techniques. The self-aggregation and thermodynamic properties of these surfactants have been investigated by pendant-drop surface tensiometry and conductivity measurements. The liquid crystalline behaviors of these surfactants were investigated by small-angle X-ray scattering (SAXS) technique. The quinuclidinolium headgroup demonstrated a unique ability to interlock among themselves thus affecting the physicochemical properties of surfactants in aqueous solution. The current research finding supports the new concept of headgroup interlocking which is supported by 1D and 2D NMR studies. PMID:25058797

  17. Long-time behavior of solution for the compressible nematic liquid crystal flows in R3

    NASA Astrophysics Data System (ADS)

    Gao, Jincheng; Tao, Qiang; Yao, Zheng-an

    2016-08-01

    In this paper, we investigate the global existence and long-time behavior of classical solution for the compressible nematic liquid crystal flows in three-dimensional whole space. First of all, the global existence of classical solution is established under the condition that the initial data are close to the constant equilibrium state in HN (R3) (N ≥ 3)-framework. Then, one establishes algebraic time decay for the classical solution by weighted energy method. Finally, the algebraic decay rate of classical solution in Lp (R3)-norm with 2 ≤ p ≤ ∞ and optimal decay rate of their spatial derivative in L2 (R3)-norm are obtained if the initial perturbation belong to L1 (R3) additionally.

  18. The self-associating behavior of NH3 and ND3 in liquid xenon

    NASA Astrophysics Data System (ADS)

    De Beuckeleer, Liene I.; Herrebout, Wouter A.

    2016-08-01

    In this study we report on the analysis of isothermal spectra of NH3 and ND3 solutions in liquid xenon at 203 K using newly developed and validated least-squares approaches to investigate the its self-associating behavior. For both species we observe clear dimer bands in the spectral area of the ν1+ν4, ν3+ν4 and ν1+ν2, ν3+ν2 combination bands. The analysis of the N-D stretching area, allows us to characterize clear contributions of dimers and trimers. The analysis of the Nsbnd H stretching area is hampered by the occurrence of a time dependent band due to solid water traces during the experiments. For NH3 we also performed an investigation of the Nsbnd H bending region, ν2, which demonstrated a small dimer absorption band. These obtained results compare well with literature data.

  19. Aggregation behavior of long-chain piperidinium ionic liquids in ethylammonium nitrate.

    PubMed

    Dai, Caili; Du, Mingyong; Liu, Yifei; Wang, Shilu; Zhao, Jianhui; Chen, Ang; Peng, Dongxu; Zhao, Mingwei

    2014-01-01

    Micelles formed by the long-chain piperidinium ionic liquids (ILs) N-alkyl-N-methylpiperidinium bromide of general formula CnPDB (n = 12, 14, 16) in ethylammonium nitrate (EAN) were investigated through surface tension and dissipative particle dynamics (DPD) simulations. Through surface tension measurements, the critical micelle concentration (cmc), the effectiveness of surface tension reduction (Πcmc), the maximum excess surface concentration (Гmax) and the minimum area occupied per surfactant molecule (Amin) can be obtained. A series of thermodynamic parameters (DG0 m, DH0 m and DS0 m) of micellization can be calculated and the results showed that the micellization was entropy-driven. In addition, the DPD simulation was performed to simulate the whole aggregation process behavior to better reveal the micelle formation process. PMID:25474288

  20. Using Liquid Crystals to Reveal How Mechanical Anisotropy Changes Interfacial Behaviors of Motile Bacteria

    PubMed Central

    Mushenheim, Peter C.; Trivedi, Rishi R.; Weibel, Douglas B.; Abbott, Nicholas L.

    2014-01-01

    Bacteria often inhabit and exhibit distinct dynamical behaviors at interfaces, but the physical mechanisms by which interfaces cue bacteria are still poorly understood. In this work, we use interfaces formed between coexisting isotropic and liquid crystal (LC) phases to provide insight into how mechanical anisotropy and defects in LC ordering influence fundamental bacterial behaviors. Specifically, we measure the anisotropic elasticity of the LC to change fundamental behaviors of motile, rod-shaped Proteus mirabilis cells (3 μm in length) adsorbed to the LC interface, including the orientation, speed, and direction of motion of the cells (the cells follow the director of the LC at the interface), transient multicellular self-association, and dynamical escape from the interface. In this latter context, we measure motile bacteria to escape from the interfaces preferentially into the isotropic phase, consistent with the predicted effects of an elastic penalty associated with strain of the LC about the bacteria when escape occurs into the nematic phase. We also observe boojums (surface topological defects) present at the interfaces of droplets of nematic LC (tactoids) to play a central role in mediating the escape of motile bacteria from the LC interface. Whereas the bacteria escape the interface of nematic droplets via a mechanism that involved nematic director-guided motion through one of the two boojums, for isotropic droplets in a continuous nematic phase, the elasticity of the LC generally prevented single bacteria from escaping. Instead, assemblies of bacteria piled up at boojums and escape occurred through a cooperative, multicellular phenomenon. Overall, our studies show that the dynamical behaviors of motile bacteria at anisotropic LC interfaces can be understood within a conceptual framework that reflects the interplay of LC elasticity, surface-induced order, and topological defects. PMID:24988359

  1. Structural and thermodynamic behavior of alkane chains at the liquid/vapor interface

    NASA Astrophysics Data System (ADS)

    Hernandez, David Alejandro; Domínguez, Hector

    2013-04-01

    Computer simulations for several alkane fluids were carried out to study thermodynamics and structural behavior of the molecules at the liquid-vapor interface. Three different models were used to simulate the fluids, one of them was proposed in this work and we obtained a slightly better agreement than the other models with experimental data. The fluid structure at the interface was analyzed at temperatures close to the melting point using the new model and it was found that molecules at the free surface present more order than those at the bulk liquid phase. By calculating the order of the hydrocarbon chains a strong structure of molecules was observed at the interface than those in bulk, moreover, some of those molecules at the interface were aligned perpendicular to the interface. Previous simulations report stronger structures at the interface by the formation of a monolayer of alkane chains, however, those simulations started at very low temperatures and they did not reproduce thermodynamic properties such as the interfacial tension correctly. The model proposed in the present work not only presents good agreement with surface tension data but also shows evidence that the fluid structured as experiments indicated at temperatures close to the melting temperature.

  2. Universality of One-Dimensional Fermi Systems, I. Response Functions and Critical Exponents

    NASA Astrophysics Data System (ADS)

    Benfatto, G.; Falco, P.; Mastropietro, V.

    2014-08-01

    The critical behavior of one-dimensional interacting Fermi systems is expected to display universality features, called Luttinger liquid behavior. Critical exponents and certain thermodynamic quantities are expected to be related among each other by model-independent formulas. We establish such relations, the proof of which has represented a challenging mathematical problem, for a general model of spinning fermions on a one dimensional lattice; interactions are short ranged and satisfy a positivity condition which makes the model critical at zero temperature. Proofs are reported in two papers: in the present one, we demonstrate that the zero temperature response functions in the thermodynamic limit are Borel summable and have anomalous power-law decay with multiplicative logarithmic corrections. Critical exponents are expressed in terms of convergent expansions and depend on all the model details. All results are valid for the special case of the Hubbard model.

  3. Fabrication of liquid-infused surfaces using reactive polymer multilayers: principles for manipulating the behaviors and mobilities of aqueous fluids on slippery liquid interfaces.

    PubMed

    Manna, Uttam; Lynn, David M

    2015-05-20

    The design of slippery liquid-infused porous surfaces (SLIPS) using nanoporous and chemically reactive polymer multilayers is reported. This approach permits fabrication of slippery anti-fouling coatings on complex surfaces and provides new means to manipulate the mobilities of contacting aqueous fluids. The results expand the range of tools that can be used to manipulate the behaviors of SLIPS and open the door to new applications of this emerging class of soft materials. PMID:25854608

  4. Microgravity: Molecular Dynamics Simulations at the NCCS Probe the Behavior of Liquids in Low Gravity

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The life of the very small, whether in something as complicated as a human cell or as simple as a drop of water, is of fundamental scientific interest: By knowing how a tiny amount of material reacts to changes in its environment, scientists maybe able to answer questions about how a bulk of material would react to comparable changes. NASA is in the forefront of computational research into a broad range of basic scientific questions about fluid dynamics and the nature of liquid boundary instability. For example, one important issue for the space program is how drops of water and other materials will behave in the low-gravity environment of space and how the low gravity will affect the transport and containment of these materials. Accurate prediction of this behavior is among the aims of a set of molecular dynamics experiments carried out on the NCCSs Cray supercomputers. In conventional computational studies of materials, matter is treated as continuous - a macroscopic whole without regard to its molecular parts - and the behavior patterns of the matter in various physical environments are studied using well-established differential equations and mathematical parameters based on physical properties such as compressibility density, heat capacity, and vapor pressure of the bulk material.

  5. Dynamic behaviors of liquid droplets on a gas diffusion layer surface: Hybrid lattice Boltzmann investigation

    NASA Astrophysics Data System (ADS)

    Wu, Jie; Huang, Jun-Jie

    2015-07-01

    Water management is one of the key issues in proton exchange membrane fuel cells. Fundamentally, it is related to dynamic behaviors of droplets on a gas diffusion layer (GDL) surface, and consequently they are investigated in this work. A two-dimensional hybrid method is employed to implement numerical simulations, in which the flow field is solved by using the lattice Boltzmann method and the interface between droplet and gas is captured by solving the Cahn-Hilliard equation directly. One or two liquid droplets are initially placed on the GDL surface of a gas channel, which is driven by the fully developed Poiseuille flow. At a fixed channel size, the effects of viscosity ratio of droplet to gas ( μ ∗ ), Capillary number (Ca, ratio of gas viscosity to surface tension), and droplet interaction on the dynamic behaviors of droplets are systematically studied. By decreasing viscosity ratio or increasing Capillary number, the single droplet can detach from the GDL surface easily. On the other hand, when two identical droplets stay close to each other or a larger droplet is placed in front of a smaller droplet, the removal of two droplets is promoted.

  6. From soft to hard rod behavior in liquid crystalline suspensions of sterically stabilized colloidal filamentous particles.

    PubMed

    Grelet, Eric; Rana, Richa

    2016-05-18

    The liquid crystalline phase behavior of a colloidal system of sterically stabilized rods is reported. Our colloidal suspensions consist of highly monodisperse, semi-flexible filamentous viruses which have been coated with neutral hydrophilic polymers by irreversibly binding poly(ethylene glycol) (PEG) to the surface of the virus particles. Depending on the size of the grafted polymer, up to three different phase transitions are observed (isotropic-to-chiral nematic, chiral nematic-to-smectic, and smectic-to-columnar). Each phase transition is shown to be independent of ionic strength, confirming the steric stabilization of the viral colloids. A direct, i.e. without any free parameters, comparison with theory and computer simulations of the volume fraction associated with the phase transition can be performed, showing a quantitative agreement with hard rod behavior at a low polymer chain size, and some deviation stemming from soft repulsion by increasing the polymer thickness coating of the rod. Specifically, we demonstrate that the columnar mesophase is not stabilized by electrostatic repulsion, and we discuss the conditions of its existence. PMID:27108523

  7. Using chemically patterns with different anchoring behavior to control the orientation of nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Li, Xiao; Armas Perez, Julio; Martinez-Gonzalez, Jose Adrian; Xie, Helou; de Pablo, Juan; Nealey, Paul

    2015-03-01

    We present experimental and theoretical study of nematic liquid crystal (5CB) confined to a thin cell between homeotropic anchoring top surface and chemically patterned planar/homeotropic anchoring bottom substrates. The chemically patterned substrate with different dimensions and ~ 4 nm depth topography induce the 5CB to align as the pattern direction as non-degenerate behavior, until the width of the straight line pattern is too wide to confine the 5CB to one direction and back to degenerate behavior. By changing the width of the straight line pattern, a brightness change of the intensity is shown by their corresponding crossed polarizer images. This change is mainly due to a discontinuity of the average angle between the molecules and the surface in function of line width, which is in excellent agreement with the Landan-de Gennes theory when the balance between the elastic deformation in the bulk and orientation of molecules close to the surface is simulated for different pattern dimensions. An elastic free energy transition is also observed from the numerical analysis when the strong planar anchoring for presented experiments is changed to weak. This 3D confinement by chemically patterns and small depth topography offers a new way to generate any geometry pattern controllable non-degenerate orientation, achieving switchable optical properties.

  8. A theory for the liquid-crystalline phase behavior of the Gay-Berne model

    NASA Astrophysics Data System (ADS)

    Velasco, E.; Mederos, L.

    1998-08-01

    A simple yet reasonably accurate perturbation theory for the Gay-Berne model, capable of describing the uniform isotropic and nematic phases, as well as the layered smectic-A phase, is presented. The theory, in line with a previously proposed theory, is based on a perturbative scheme, but the reference system, a hard Gaussian overlap model, is treated using the nonlocal approximation of Somoza and Tarazona. This approximate scheme, which reduces to the well-known decoupling approximation for nematics, is a simple generalization of the decoupling approximation designed to include smectic structures. The attractive free energy is calculated using a mean-field approximation. Underestimation of the attractive energy implied by this approximation is alleviated by introducing some scale factors, set to reproduce the critical point and two triple points involving the smectic phase. The choice of scale factors, which is valid for a particular set of molecular parameters, is shown to reproduce accurately the phase diagram corresponding to other parameter values. The theory is used to examine the global liquid-crystalline phase behavior of the Gay-Berne model, paying particular attention to the effect of the anisotropy attraction parameter κ' on the location of the various phase boundaries. Comparison of the results with the available computer simulations for this system indicates that the theory leads to qualitatively correct predictions. The theory could be useful to predict the phase behavior of realistic systems with respect to molecular elongation and energy anisotropy.

  9. Retention behavior of alkylated polycyclic aromatic sulfur heterocycles on immobilized ionic liquid stationary phases.

    PubMed

    Antle, Patrick; Zeigler, Christian; Robbat, Albert

    2014-09-26

    Polycyclic aromatic sulfur heterocycles (PASH) are prevalent components of fossil fuel-based pollutants, and their accurate analysis is of critical importance in risk assessment and hazardous waste site remediation. PASH, however, have a wide range of volatilities and polarities and, as such, often coelute with one another and other sample components on the non-polar gas chromatography (GC) columns commonly used in their analysis. Immobilized ionic liquid (IL)-based stationary phases have been shown to provide better separation of polar compounds than non-polar columns, while withstanding higher temperatures than typical polar columns. In this way, they offer the opportunity of improved performance in the analysis of PASH in complex environmental samples and as the "more polar" column in GC×GC/MS analyses. In this study, the retention behavior of 119 PASH on four commercially-available IL stationary phases is reported and compared to behavior on three polydimethylsiloxane-based columns of varying polarities (DB-5, DB-17, and DB-200). Additionally, the utility of IL columns in GC×GC analyses of PASH-containing coal tar samples is examined. PMID:25155062

  10. Hunger in red imported fire ants and their behavioral response to two liquid bait products.

    PubMed

    O'Brien, Kathryn S; Hooper-Bùi, Linda M

    2005-12-01

    To help manage red imported fire ant, Solenopsis invicta Buren, invasion, several types of pest management systems have been developed, including baits. To accurately test liquid bait effectiveness in the laboratory, we determined that starvation time of 96 h is required for laboratory fire ants to simulate foraging ants in the field. We measured density and viscosity of two commercial baits and 20% sugar water at 25 degrees C and then compared amount of material consumed per ant at these physical properties. Mean densities of 20% sugar water, Dr. Moss, and Terro were 1.051, 1.287, and 1.354 g/ml, respectively, and viscosity of each bait treatment varied in the same order but more drastically (1.7, 32, and 400 centipoises, respectively). Field and laboratory studies demonstrated that bait acceptability may be affected by toxicant and physical properties. Baits that are more dense have more mass per volume and may cause the ant to cease feeding with a lower crop load than when they feed on sugar water. Ants that feed on formulated baits exhibit feeding behaviors different from those that occur when feeding on sugar water. At first glance, one might conclude that the difference is because of the toxicant, but our findings suggest that physical properties of baits may be a factor in this change in feeding behavior. PMID:16539145

  11. MASS-REMOVAL AND MASS-FLUX-REDUCTION BEHAVIOR FOR IDEALIZED SOURCE ZONES WITH HYDRAULICALLY POORLY-ACCESSIBLE IMMISCIBLE LIQUID

    SciTech Connect

    Brusseau, M. L.; Difilippo, Erica L.; marble, justin C.; Oostrom, Mart

    2008-04-01

    A series of flow-cell experiments was conducted to investigate aqueous dissolution and mass-removal behavior for systems wherein immiscible liquid was non-uniformly distributed in physically heterogeneous source zones. The study focused specifically on characterizing the relationship between mass flux reduction and mass removal for systems for which immiscible liquid is poorly accessible to flowing water. Two idealized scenarios were examined, one wherein immiscible liquid at residual saturation exists within a lower-permeability unit residing in a higher-permeability matrix, and one wherein immiscible liquid at higher saturation (a pool) exists within a higher-permeability unit adjacent to a lower-permeability unit. The results showed that significant reductions in mass flux occurred at relatively moderate mass-removal fractions for all systems. Conversely, minimalmass flux reduction occurred until a relatively large fraction of mass (>80%) was removed for the control experiment, which was designed to exhibit ideal mass removal. In general, mass flux reduction was observed to follow an approximately one-to-one relationship with mass removal. Two methods for estimating mass-flux-reduction/mass-removal behavior, one based on system-indicator parameters (ganglia-to-pool ratio) and the other a simple mass-removal function, were used to evaluate the measured data. The results of this study illustrate the impact of poorly accessible immiscible liquid on mass-removal and mass-flux processes, and the difficulties posed for estimating mass-flux-reduction/mass-removal behavior.

  12. Combinatorial approach for the rapid determination of thermochromic behavior of binary and ternary cholesteric liquid crystalline mixtures.

    PubMed

    van der Werff, Louise C; Robinson, Andrea J; Kyratzis, Ilias L

    2012-11-12

    A combinatorial approach was developed for the rapid determination of thermochromic behavior of a large number of binary and ternary sterol based thermochromic liquid crystalline formulations. A binary mixture containing cholesteryl oleyl carbonate and cholesteryl nonanoate, and ternary mixtures also containing a third component, either cholesteryl oleate, cholesteryl benzoate, cholesteryl 2,4-dichlorobenzoate or cholesteryl propionate, were formulated via solvent deposition into a black Teflon coated aluminum 96 well plate. The temperature of the well plate was then varied, and the color appearance of the deposited mixture in each well was recorded. This approach allowed expedient examination of the thermochromic behavior for a large range of liquid crystal formulations. The accuracy of the rapid combinatorial technique was validated on selected thermochromic liquid crystal mixture compositions by comparing well thermochromic output with that observed using UV-vis spectroscopy on material produced in gram quantities. PMID:23072483

  13. A New Volume-Based Approach for Predicting Thermophysical Behavior of Ionic Liquids and Ionic Liquid Crystals.

    PubMed

    Nelyubina, Yulia V; Shaplov, Alexander S; Lozinskaya, Elena I; Buzin, Mikhail I; Vygodskii, Yakov S

    2016-08-17

    Volume-based prediction of melting points and other properties of ionic liquids (ILs) relies on empirical relations with volumes of ions in these low-melting organic salts. Here we report an accurate way to ionic volumes by Bader's partitioning of electron densities from X-ray diffraction obtained via a simple database approach. For a series of 1-tetradecyl-3-methylimidazolium salts, the volumes of different anions are found to correlate linearly with melting points; larger anions giving lower-melting ILs. The volume-based concept is transferred to ionic liquid crystals (ILs that adopt liquid crystalline mesophases, ILCs) for predicting the domain of their existence from the knowledge of their constituents. For 1-alkyl-3-methylimidazolium ILCs, linear correlations of ionic volumes with the occurrence of LC mesophase and its stability are revealed, thus paving the way to rational design of ILCs by combining suitably sized ions. PMID:27479022

  14. Volovik effect and Fermi-liquid behavior in the s-wave superconductor CaPd2As2: As75 NMR-NQR measurements

    DOE PAGESBeta

    Ding, Q. -P.; Wiecki, P.; Anand, V. K.; Sangeetha, N. S.; Lee, Y.; Johnston, D. C.; Furukawa, Y.

    2016-04-07

    The electronic and magnetic properties of the collapsed-tetragonal CaPd2As2 superconductor (SC) with a transition temperature of 1.27 K have been investigated by 75As nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements. The temperature (T) dependence of the nuclear spin lattice relaxation rates (1/T1) and the Knight shifts indicate the absence of magnetic correlations in the normal state. In the SC state, 1/T1 measured by 75As NQR shows a clear Hebel-Slichter (HS) peak just below Tc and decreases exponentially at lower T, confirming a conventional s-wave SC. Additionally, the Volovik effect, also known as the Doppler shift effect, hasmore » been clearly evidenced by the observation of the suppression of the HS peak with applied magnetic field.« less

  15. Volovik effect and Fermi-liquid behavior in the s -wave superconductor CaPd2As2: 75As NMR-NQR measurements

    NASA Astrophysics Data System (ADS)

    Ding, Q.-P.; Wiecki, P.; Anand, V. K.; Sangeetha, N. S.; Lee, Y.; Johnston, D. C.; Furukawa, Y.

    2016-04-01

    The electronic and magnetic properties of the collapsed-tetragonal CaPd2As2 superconductor (SC) with a transition temperature of 1.27 K have been investigated by 75As nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements. The temperature (T ) dependence of the nuclear spin lattice relaxation rates (1 /T1) and the Knight shifts indicate the absence of magnetic correlations in the normal state. In the SC state, 1 /T1 measured by 75As NQR shows a clear Hebel-Slichter (HS) peak just below Tc and decreases exponentially at lower T , confirming a conventional s -wave SC. In addition, the Volovik effect, also known as the Doppler shift effect, has been clearly evidenced by the observation of the suppression of the HS peak with applied magnetic field.

  16. Aggregation behavior in water of new imidazolium and pyrrolidinium alkycarboxylates protic ionic liquids.

    PubMed

    Anouti, Meriem; Jones, Jennifer; Boisset, Aurélien; Jacquemin, Johan; Caillon-Caravanier, Magaly; Lemordant, Daniel

    2009-12-01

    A novel class of anionic surfactants was prepared through the neutralization of pyrrolidine or imidazole by alkylcarboxylic acids. The compounds, namely the pyrrolidinium alkylcarboxylates ([Pyrr][C(n)H(2n+1)COO]) and imidazolium alkylcarboxylates ([Im][C(n)H(2n+1)COO]), were obtained as ionic liquids at room temperature. Their aggregation behavior has been examined as a function of the alkyl chain length (from n=5 to 8) by surface tensiometry and conductivity. Decreases in the critical micelle concentration (cmc) were obtained, for both studied PIL families, when increasing the anionic alkyl chain length (n). Surprisingly, a large effect of the alkyl chain length was observed on the minimum surface area per surfactant molecule (A(min)) and, hence the maximum surface excess concentration (Gamma(max)) when the counterion was the pyrrolidinium cation. This unusual comportment has been interpreted in term of a balance between van der Waals and coulombic interactions. Conductimetric measurements permit determination of the degree of ionization of the micelle (a) and the molar conductivity (Lambda(M)) of these surfactants as a function of n. The molar conductivities at infinite dilution in water (Lambda(infinity)) of the [Pyrr]+ and [Im]+ cations have been then determined by using the classical Kohlraush equation. Observed change in the physicochemical, surface, and micellar properties of these new protonic ionic liquid surfactants can be linked to the nature of the cation. By comparison with classical anionic surfactants having inorganic counterions, pyrrolidinium alkylcarboxylates and imidazolium alkylcarboxylates exhibit a higher ability to aggregate in aqueous solution, demonstrating their potential applicability as surfactant. PMID:19758596

  17. The Statistical Fermi Paradox

    NASA Astrophysics Data System (ADS)

    Maccone, C.

    In this paper is provided the statistical generalization of the Fermi paradox. The statistics of habitable planets may be based on a set of ten (and possibly more) astrobiological requirements first pointed out by Stephen H. Dole in his book Habitable planets for man (1964). The statistical generalization of the original and by now too simplistic Dole equation is provided by replacing a product of ten positive numbers by the product of ten positive random variables. This is denoted the SEH, an acronym standing for “Statistical Equation for Habitables”. The proof in this paper is based on the Central Limit Theorem (CLT) of Statistics, stating that the sum of any number of independent random variables, each of which may be ARBITRARILY distributed, approaches a Gaussian (i.e. normal) random variable (Lyapunov form of the CLT). It is then shown that: 1. The new random variable NHab, yielding the number of habitables (i.e. habitable planets) in the Galaxy, follows the log- normal distribution. By construction, the mean value of this log-normal distribution is the total number of habitable planets as given by the statistical Dole equation. 2. The ten (or more) astrobiological factors are now positive random variables. The probability distribution of each random variable may be arbitrary. The CLT in the so-called Lyapunov or Lindeberg forms (that both do not assume the factors to be identically distributed) allows for that. In other words, the CLT "translates" into the SEH by allowing an arbitrary probability distribution for each factor. This is both astrobiologically realistic and useful for any further investigations. 3. By applying the SEH it is shown that the (average) distance between any two nearby habitable planets in the Galaxy may be shown to be inversely proportional to the cubic root of NHab. This distance is denoted by new random variable D. The relevant probability density function is derived, which was named the "Maccone distribution" by Paul Davies in

  18. Chemistry in the Venus clouds: Sulfuric acid reactions and freezing behavior of aqueous liquid droplets

    NASA Astrophysics Data System (ADS)

    Delitsky, M. L.; Baines, K. H.

    2015-11-01

    Venus has a thick cloud deck at 40-70 km altitude consisting of liquid droplets and solid particles surrounded by atmospheric gases. The liquid droplets are highly concentrated aqueous solutions of sulfuric acid ranging in concentration from 70-99 wt%. Weight percent drops off with altitude (Imamura and Hashimoto 2001). There will be uptake of atmospheric gases into the droplet solutions and the ratios of gas-phase to liquid-phase species will depend on the Henry’s Law constant for those solutions. Reactions of sulfuric acid with these gases will form products with differing solubilities. For example, uptake of HCl by H2SO4/H2O droplets yields chlorosulfonic acid, ClSO3H (Robinson et al 1998) in solution. This may eventually decompose to thionyl- or sulfuryl chlorides, which have UV absorbances. HF will also uptake, creating fluorosulfonic acid, FSO3H, which has a greater solubility than the chloro- acid. As uptake continues, there will be many dissolved species in the cloudwaters. Baines and Delitsky (2013) showed that uptake will have a maximum at ~62 km and this is very close to the reported altitude for the mystery UV absorber in the Venus atmosphere. In addition, at very strong concentrations in lower altitude clouds, sulfuric acid will form hydrates such as H2SO4.H2O and H2SO4.4H2O which will have very different freezing behavior than sulfuric acid, with much higher freezing temperatures (Carslaw et al, 1997). Using temperature data from Venus Express from Tellmann et al (2009), and changes in H2SO4 concentrations as a function of altitude (James et al 1997), we calculate that freezing out of sulfuric acid hydrates can be significant down to as low as 56 km altitude. As a result, balloons, aircraft or other probes in the Venus atmosphere may be limited to flying below certain altitudes. Any craft flying at altitudes above ~55 km may suffer icing on the wings, propellers, balloons and instruments which could cause possible detrimental effects (thermal

  19. Low temperatures shear viscosity of a two-component dipolar Fermi gas with unequal population

    NASA Astrophysics Data System (ADS)

    Darsheshdar, E.; Yavari, H.; Zangeneh, Z.

    2016-07-01

    By using the Green's functions method and linear response theory we calculate the shear viscosity of a two-component dipolar Fermi gas with population imbalance (spin polarized) in the low temperatures limit. In the strong-coupling Bose-Einstein condensation (BEC) region where a Feshbach resonance gives rise to tightly bound dimer molecules, a spin-polarized Fermi superfluid reduces to a simple Bose-Fermi mixture of Bose-condensed dimers and the leftover unpaired fermions (atoms). The interactions between dimer-atom, dimer-dimer, and atom-atom take into account to the viscous relaxation time (τη) . By evaluating the self-energies in the ladder approximation we determine the relaxation times due to dimer-atom (τDA) , dimer-dimer (τcDD ,τdDD) , and atom-atom (τAA) interactions. We will show that relaxation rates due to these interactions τDA-1 ,τcDD-1, τdDD-1, and τAA-1 have T2, T4, e - E /kB T (E is the spectrum of the dimer atoms), and T 3 / 2 behavior respectively in the low temperature limit (T → 0) and consequently, the atom-atom interaction plays the dominant role in the shear viscosity in this rang of temperatures. For small polarization (τDA ,τAA ≫τcDD ,τdDD), the low temperatures shear viscosity is determined by contact interaction between dimers and the shear viscosity varies as T-5 which has the same behavior as the viscosity of other superfluid systems such as superfluid neutron stars, and liquid helium.

  20. Nonlinear vibrational spectroscopic studies of molecular interaction and charging behavior at solid/liquid interfaces

    NASA Astrophysics Data System (ADS)

    Zhang, Luning

    Solid-liquid interfaces have been the focus of different communities of scientists due to its importance in industrial applications and chemical processes in nature. Molecular interactions and surface charges affect the physicochemical properties of these interfaces and a thorough understanding is still lacking now. This thesis describes our work in studying several model solid-liquid interfaces using sum-frequency vibrational spectroscopy. Through the studies of interfacial vibrational spectra, we hope to gain better understanding of molecular interactions in competitive adsorption process and also surface charging behavior at different pH and salt concentrations. We start by studying alcohol-water mixture and the adsorption behavior at both hydrophilic and hydrophobic surfaces. In both cases, alcohol adsorbs preferentially from water. The tendency for water to form strong hydrogen-bonding network is the driving force for preferential adsorption of alcohol. We proposed two different interfacial molecular structures on hydrophilic and hydrophobic surfaces. We move on to study the interaction of pure water with a solid surface. Single crystal alumina is used as a model system. At different pH, the surface can undergo protonation and deprotonation reactions and accumulates surface charge. Both the hydrogen-bonding with water and the surface field created by surface charge can affect interfacial water structure. Combining the information obtained with intensity and phase spectra, we find water molecules have two types of bonding within the interfacial layer: weakly hydrogen-bonded species near 3450 cm-1 that does not flip with switching surface charge, and strongly hydrogen-bonded species at 3200 cm-1 that readily flips with switching surface field. One other system we have studied is nanoporous silica-water interface. We found that signal from interfacial water is reduced due to the porous nature of the film. The water spectral features tell us about the interfacial

  1. The fermi paradox is neither Fermi's nor a paradox.

    PubMed

    Gray, Robert H

    2015-03-01

    The so-called Fermi paradox claims that if technological life existed anywhere else, we would see evidence of its visits to Earth--and since we do not, such life does not exist, or some special explanation is needed. Enrico Fermi, however, never published anything on this topic. On the one occasion he is known to have mentioned it, he asked "Where is everybody?"--apparently suggesting that we do not see extraterrestrials on Earth because interstellar travel may not be feasible, but not suggesting that intelligent extraterrestrial life does not exist or suggesting its absence is paradoxical. The claim "they are not here; therefore they do not exist" was first published by Michael Hart, claiming that interstellar travel and colonization of the Galaxy would be inevitable if intelligent extraterrestrial life existed, and taking its absence here as proof that it does not exist anywhere. The Fermi paradox appears to originate in Hart's argument, not Fermi's question. Clarifying the origin of these ideas is important, because the Fermi paradox is seen by some as an authoritative objection to searching for evidence of extraterrestrial intelligence--cited in the U.S. Congress as a reason for killing NASA's SETI program on one occasion. But evidence indicates that it misrepresents Fermi's views, misappropriates his authority, deprives the actual authors of credit, and is not a valid paradox. PMID:25719510

  2. Quasicondensation in Two-Dimensional Fermi Gases.

    PubMed

    Wu, Chien-Te; Anderson, Brandon M; Boyack, Rufus; Levin, K

    2015-12-11

    In this paper we follow the analysis and protocols of recent experiments, combined with simple theory, to arrive at a physical understanding of quasi-condensation in two dimensional Fermi gases. A key signature of quasi-condensation, which contains aspects of Berezinskiĭ-Kosterlitz-Thouless behavior, is a strong zero momentum peak in the pair momentum distribution. Importantly, this peak emerges at a reasonably well defined onset temperature. The resulting phase diagram, pair momentum distribution, and algebraic power law decay are compatible with recent experiments throughout the continuum from BEC to BCS. PMID:26705613

  3. Vapor-liquid phase behavior of the iodine-sulfur water-splitting process : LDRD final report for FY03.

    SciTech Connect

    Bradshaw, Robert W.; Larson, Richard S.; Lutz, Andrew E.

    2004-01-01

    This report summarizes the results of a one-year LDRD project that was undertaken to better understand the equilibrium behavior of the iodine-water-hydriodic acid system at elevated temperature and pressure. We attempted to extend the phase equilibrium database for this system in order to facilitate development of the iodine-sulfur water-splitting process to produce hydrogen to a commercial scale. The iodine-sulfur cycle for thermochemical splitting of water is recognized as the most efficient such process and is particularly well suited to coupling to a high-temperature source of process heat. This study intended to combine experimental measurements of vapor-liquid-liquid equilibrium and equation-of-state modeling of equilibrium solutions using Sandia's Chernkin software. Vapor-liquid equilibrium experiments were conducted to a limited extent. The Liquid Chernkin software that was developed as part of an earlier LDRD project was enhanced and applied to model the non-ideal behavior of the liquid phases.

  4. X-ray imaging for studying behavior of liquids at high pressures and high temperatures using Paris-Edinburgh press

    SciTech Connect

    Kono, Yoshio; Kenney-Benson, Curtis; Park, Changyong; Shen, Guoyin; Shibazaki, Yuki; Wang, Yanbin

    2015-07-15

    Several X-ray techniques for studying structure, elastic properties, viscosity, and immiscibility of liquids at high pressures have been integrated using a Paris-Edinburgh press at the 16-BM-B beamline of the Advanced Photon Source. Here, we report the development of X-ray imaging techniques suitable for studying behavior of liquids at high pressures and high temperatures. White X-ray radiography allows for imaging phase separation and immiscibility of melts at high pressures, identified not only by density contrast but also by phase contrast imaging in particular for low density contrast liquids such as silicate and carbonate melts. In addition, ultrafast X-ray imaging, at frame rates up to ∼10{sup 5} frames/second (fps) in air and up to ∼10{sup 4} fps in Paris-Edinburgh press, enables us to investigate dynamics of liquids at high pressures. Very low viscosities of melts similar to that of water can be reliably measured. These high-pressure X-ray imaging techniques provide useful tools for understanding behavior of liquids or melts at high pressures and high temperatures.

  5. Fermi's New Pulsar Detection Technique

    NASA Video Gallery

    To locate a pulsar in Fermi LAT data requires knowledge of the object’s sky position, its pulse period, and how the pulse rate slows over time. Computers check many different combinations of posi...

  6. The Fermi LAT Pulsars

    NASA Astrophysics Data System (ADS)

    Romani, Roger W.

    2011-08-01

    The Large Area Telescope on the Fermi satellite is an impressive pulsar discovery machine, with over 75 pulse detections and counting. The populations of radio-selected, γ-selected and millisecond pulsars are now large enough to display observational patterns in the light curves and luminosities. These patterns are starting to teach us about the physics of the emission zone, which seems dominated by open field lines near the speed of light cylinder. The sample also provides initial inferences about the pulsar population. Apparently a large fraction of neutron stars have a young energetic γ-ray emitting phase, making these objects a good probe of massive star evolution. The long-lived millisecond γ-ray pulsars are even more ubiquitous and may produce a significant fraction of the γ-ray background. In any event, it is clear that the present LAT pulsar sample is dominated by nearby objects, and there is every expectation that the number, and quality, of pulsar detections will increase in years to come.

  7. Strongly correlated quantum spin liquid in herbertsmithite

    SciTech Connect

    Shaginyan, V. R.; Popov, K. G.; Khodel, V. A.

    2013-05-15

    Strongly correlated Fermi systems are among the most intriguing and fundamental systems in physics. We show that the herbertsmithite ZnCu{sub 3}(OH){sub 6}Cl{sub 2} can be regarded as a new type of strongly correlated electrical insulator that possesses properties of heavy-fermion metals with one exception: it resists the flow of electric charge. We demonstrate that herbertsmithite's low-temperature properties are defined by a strongly correlated quantum spin liquid made with hypothetic particles such as fermionic spinons that carry spin 1/2 and no charge. Our calculations of its thermodynamic and relaxation properties are in good agreement with recent experimental facts and allow us to reveal their scaling behavior, which strongly resembles that observed in heavy-fermion metals. Analysis of the dynamic magnetic susceptibility of strongly correlated Fermi systems suggests that there exist at least two types of its scaling.

  8. Smooth perfluorinated surfaces with different chemical and physical natures: their unusual dynamic dewetting behavior toward polar and nonpolar liquids.

    PubMed

    Cheng, Dalton F; Masheder, Benjamin; Urata, Chihiro; Hozumi, Atsushi

    2013-09-10

    The effects of surface chemistry and the mobility of surface-tethered functional groups of various perfluorinated surfaces on their dewetting behavior toward polar (water) and nonpolar (n-hexadecane, n-dodecane, and n-decane) liquids were investigated. In this study, three types of common smooth perfluorinated surfaces, that is, a perfluoroalkylsilane (heptadecafluoro-1,1,2,2-tetrahydrooctyl-dimethylchlorosilane, FAS17) monomeric layer, an amorphous fluoropolymer film (Teflon AF 1600), and a perfluorinated polyether (PFPE)-terminated polymer brush film (Optool DSX), were prepared and their static/dynamic dewetting characteristics were compared. Although the apparent static contact angles (CAs) of these surfaces with all probe liquids were almost identical to each other, the ease of movement of liquid drops critically depended on the physical (solidlike or liquidlike) natures of the substrate surface. CA hysteresis and substrate tilt angles (TAs) of all probe liquids on the Optool DSX surface were found to be much lower than those of Teflon AF1600 and FAS17 surfaces due to its physical polymer chain mobility at room temperature and the resulting liquidlike nature. Only 6.0° of substrate incline was required to initiate movement for a small drop (5 μL) of n-decane, which was comparable to the reported substrate TA value (5.3°) for a superoleophobic surface (θ(S) > 160°, textured perfluorinated surface). Such unusual dynamic dewetting behavior of the Optool DSX surface was also markedly enhanced due to the significant increase in the chain mobility of PFPE by moderate heating (70 °C) of the surface, with substrate TA reducing to 3.0°. CA hysteresis and substrate TAs rather than static CAs were therefore determined to be of greater consequence for the estimation of the actual dynamic dewetting behavior of alkane probe liquids on these smooth perfluorinated surfaces. Their dynamic dewettability toward alkane liquids is in the order of Optool DSX > Teflon AF1600

  9. Electrorheological Behavior of Main Chain Liquid Crystal Polymers in Thermotropic Nematic Solvents

    NASA Astrophysics Data System (ADS)

    Chiang, Yen-Ching; Jamieson, Alex. M.

    1998-03-01

    The increment in Miesowicz viscosity, δ η c on dissolving a main-chain liquid crystal polymer (LCP) in a nematic solvent was measured by cone-and-plate rheometry in the presence of a saturation electric field, applied perpendicular to the flow direction. In addition, the corresponding increment in the Leslie viscosity coefficient, δ α 2 was obtained from the dependence of the apparent viscosity response on the applied field strength, by curve-fitting to the torque balance equation using the 2D Ericksen-Leslie-Parodi theory. For the main-chain LCP TPB10, which has mesogenic groups separated by decamethylene spacers, both δ η c and δ α 2 exhibit, within experimental uncertainty, a linear dependence on the molecular weight. Using a hydrodynamic model of Brochard, this observation suggests that the chain behaves as a free-draining random coil, biased along the director. The temperature dependence of the relative viscosity increments, δ η c / η c ^o and δ α 2 / α 2 ^o, where η c ^o and α 2 ^o are the relevant solvent viscosities, exhibits Arrhenius behavior with an activation energy comparable to that for formation of hairpin turns in the spacer groups.

  10. Charge Density Wave Behavior of Ionic Liquid Gated Strontium Titanate Nanowires

    NASA Astrophysics Data System (ADS)

    Bretz-Sullivan, Terence; Goldman, Allen

    2015-03-01

    Measurements of the current-voltage characteristics of ionic liquid gated nanometer scale channels of strontium titanate have been carried out. These characteristics exhibit a large voltage threshold for conduction and a nonlinear power law behavior at all temperatures measured. The source-drain current of these nanowires scales as a power law of the difference between the source-drain voltage and the threshold voltage. The temperature dependence of the threshold voltage appears to be related to the inverse of the temperature dependent dielectric constant of strontium titanate in qualitative agreement with a simple model of charge density wave depinning. These observations, when taken together, are evidence that a gate induced charge density wave has been induced, and is depinned by strong electric fields. This work was supported by DOE Basic Energy Sciences Grant DE-FG02-02ER46004. Samples were fabricated at the Minnesota Nanofabrication Center. Parts of this work were carried out in the University of Minnesota Characterization Facility, a member of the Materials Research Facilities Network (www.mrfn.org) funded via the NSF MRSEC program.

  11. Techniques for the visualization of topological defect behavior in nematic liquid crystals.

    PubMed

    Slavin, Vadim A; Pelcovits, Robert A; Loriot, George; Callan-Jones, Andrew; Laidlaw, David H

    2006-01-01

    We present visualization tools for analyzing molecular simulations of liquid crystal (LC) behavior. The simulation data consists of terabytes of data describing the position and orientation of every molecule in the simulated system over time. Condensed matter physicists study the evolution of topological defects in these data, and our visualization tools focus on that goal. We first convert the discrete simulation data to a sampled version of a continuous second-order tensor field and then use combinations of visualization methods to simultaneously display combinations of contractions of the tensor data, providing an interactive environment for exploring these complicated data. The system, built using AVS, employs colored cutting planes, colored isosurfaces, and colored integral curves to display fields of tensor contractions including Westin's scalar cl, cp, and cs metrics and the principal eigenvector. Our approach has been in active use in the physics lab for over a year. It correctly displays structures already known; it displays the data in a spatially and temporally smoother way than earlier approaches, avoiding confusing grid effects and facilitating the study of multiple time steps; it extends the use of tools developed for visualizing diffusion tensor data, re-interpreting them in the context of molecular simulations; and it has answered long-standing questions regarding the orientation of molecules around defects and the conformational changes of the defects. PMID:17080868

  12. Carrier density independent scattering rate in SrTiO3-based electron liquids

    PubMed Central

    Mikheev, Evgeny; Raghavan, Santosh; Zhang, Jack Y.; Marshall, Patrick B.; Kajdos, Adam P.; Balents, Leon; Stemmer, Susanne

    2016-01-01

    We examine the carrier density dependence of the scattering rate in two- and three-dimensional electron liquids in SrTiO3 in the regime where it scales with Tn (T is the temperature and n ≤ 2) in the cases when it is varied by electrostatic control and chemical doping, respectively. It is shown that the scattering rate is independent of the carrier density. This is contrary to the expectations from Landau Fermi liquid theory, where the scattering rate scales inversely with the Fermi energy (EF). We discuss that the behavior is very similar to systems traditionally identified as non-Fermi liquids (n < 2). This includes the cuprates and other transition metal oxide perovskites, where strikingly similar density-independent scattering rates have been observed. The results indicate that the applicability of Fermi liquid theory should be questioned for a much broader range of correlated materials and point to the need for a unified theory. PMID:26861764

  13. Carrier density independent scattering rate in SrTiO₃-based electron liquids

    DOE PAGESBeta

    Mikheev, Evgeny; Raghavan, Santosh; Zhang, Jack Y.; Marshall, Patrick B.; Kajdos, Adam P.; Balents, Leon; Stemmer, Susanne

    2016-02-10

    We examine the carrier density dependence of the scattering rate in two- and three-dimensional electron liquids in SrTiO3 in the regime where it scales with Tn (T is the temperature and n ≤ 2) in the cases when it is varied by electrostatic control and chemical doping, respectively. It is shown that the scattering rate is independent of the carrier density. This is contrary to the expectations from Landau Fermi liquid theory, where the scattering rate scales inversely with the Fermi energy (EF). We discuss that the behavior is very similar to systems traditionally identified as non-Fermi liquids (n Fermi liquid theory should be questioned for a much broader range of correlated materials and point to the need for a unified theory.« less

  14. Modified spin-wave theory and spin-liquid behavior of cold bosons on an inhomogeneous triangular lattice

    NASA Astrophysics Data System (ADS)

    Celi, Alessio; Grass, Tobias; Ferris, Andrew J.; Padhi, Bikash; Raventós, David; Simonet, Juliette; Sengstock, Klaus; Lewenstein, Maciej

    2016-08-01

    Ultracold bosons in a triangular lattice are a promising candidate for observing quantum spin liquid behavior. Here we investigate, for such system, the role of a harmonic trap giving rise to an inhomogeneous density. We construct a modified spin-wave theory for arbitrary filling and predict the breakdown of order for certain values of the lattice anisotropy. These regimes, identified with the spin liquid phases, are found to be quite robust upon changes in the filling factor. This result is backed by an exact diagonalization study on a small lattice.

  15. Compressible Strips, Chiral Luttinger Liquids, and All That Jazz

    NASA Astrophysics Data System (ADS)

    MacDonald, A. H.

    1996-03-01

    When the quantum Hall effect occurs in a two-dimensional electron gas, all low-energy elementary excitations are localized near the system edge. The edge acts in many ways like a one-dimensional ring of electrons, except that a finite current flows around the ring in equilibrium. This article is a brief and informal review of some of the physics of quantum Hall system edges. We discuss the implications of macroscopic {\\em compressible strip} models for microscopic {chiral Luttinger liquid} models and make an important distinction between the origin of non-Fermi-liquid behavior in fractional quantum Hall edges and in usual one-dimensional electron gas systems.

  16. Correlation functions of one-dimensional Bose-Fermi mixtures

    SciTech Connect

    Frahm, Holger; Palacios, Guillaume

    2005-12-15

    We calculate the asymptotic behavior of correlators as a function of the microscopic parameters for an integrable Bose-Fermi mixture with repulsive interaction in one dimension. For two cases, namely polarized and unpolarized fermions the singularities of the momentum distribution functions are characterized as a function of the coupling constant and the relative density of bosons.

  17. Hygienic Behavior, Liquid-Foraging, and Trophallaxis in the Leaf-Cutting Ants, Acromyrmex subterraneus and Acromyrmex octospinosus

    PubMed Central

    Richard, Freddie-Jeanne; Errard, Christine

    2009-01-01

    Neotropical leaf-cutting ants (tribe Attini) live in obligate symbiosis with fungus they culture for food. To protect themselves and their fungus garden from pathogens, they minimize the entry of microorganisms through mechanical and chemical means. In this study, focusing on the species Acromyrmex subterraneus and A. octospinosus, (Hymeoptera: Formicidae). Self- and allo-grooming behavior were quantified and it was found that A. octospinosus workers spend less time in self-grooming than A. subterraneus. In the experimental absence of fungus in A. subterraneus, the times spent in these two behaviors are not affected; however workers spend significantly more time immobile. Hygienic and trophallaxis behaviors were examined as well as the possibility that workers exchange food, and the grooming behavior of foraging and non-foraging workers were compared. Behavioral observations revealed that large workers spent more time grooming than small workers, and more than 62% of replete foragers passed collected liquid food via trophallaxis to a nestmate. However, trophallaxis was rarely observed between non-forager workers. These results suggest that trophallaxis permits the exchange of alimentary liquid between colony members, but it is not important for spreading the colony odor signature. PMID:20053118

  18. Hydrodynamics in a Degenerate, Strongly Attractive Fermi Gas

    NASA Technical Reports Server (NTRS)

    Thomas, John E.; Kinast, Joseph; Hemmer, Staci; Turlapov, Andrey; O'Hara, Ken; Gehm, Mike; Granade, Stephen

    2004-01-01

    In summary, we use all-optical methods with evaporative cooling near a Feshbach resonance to produce a strongly interacting degenerate Fermi gas. We observe hydrodynamic behavior in the expansion dynamics. At low temperatures, collisions may not explain the expansion dynamics. We observe hydrodynamics in the trapped gas. Our observations include collisionally-damped excitation spectra at high temperature which were not discussed above. In addition, we observe weakly damped breathing modes at low temperature. The observed temperature dependence of the damping time and hydrodynamic frequency are not consistent with collisional dynamics nor with collisionless mean field interactions. These observations constitute the first evidence for superfluid hydrodynamics in a Fermi gas.

  19. Fermi surface, magnetic, and superconducting properties in actinide compounds

    NASA Astrophysics Data System (ADS)

    Ōnuki, Yoshichika; Settai, Rikio; Haga, Yoshinori; Machida, Yo; Izawa, Koichi; Honda, Fuminori; Aoki, Dai

    2014-08-01

    The de Haas-van Alphen effect, which is a powerful method to explore Fermi surface properties, has been observed in cerium, uranium, and nowadays even in neptunium and plutonium compounds. Here, we present the results of several studies concerning the Fermi surface properties of the heavy fermion superconductors UPt3 and NpPd5Al2, and of the ferromagnetic pressure-induced superconductor UGe2, together with those of some related compounds for which fascinating anisotropic superconductivity, magnetism, and heavy fermion behavior has been observed. xml:lang="fr"

  20. Oxidation behavior of ferritic/martensitic steels in stagnant liquid LBE saturated by oxygen at 600 °C

    NASA Astrophysics Data System (ADS)

    Shi, Quanqiang; Liu, Jian; Luan, He; Yang, Zhenguo; Wang, Wei; Yan, Wei; Shan, Yiyin; Yang, Ke

    2015-02-01

    Ferritic/martensitic (F/M) steels are primary candidates for application as cladding and structural materials in the Generation IV Nuclear Reactor, especially accelerator driven sub-critical system (ADS). The compatibility of F/M steels with liquid lead-bismuth eutectic (LBE) is a critical issue for development of ADS using liquid LBE as the coolant. In this work, the corrosion tests of two F/M steels, including a novel 9-12 Cr modified F/M steel named SIMP steel and a commercial T91 steel, were conducted in the static oxygen-saturated liquid LBE at 600 °C up to 1000 h, the microstructure of the oxide scale formed on these two steels was analyzed, the relationship between the microstructure and the oxidation behavior was studied, and the reason why the SIMP steel showed better oxidation resistance compared to T91 steel was analyzed. The results of this study confirmed that the oxidation behavior of the F/M steels in liquid metals is influenced by their alloying elements and microstructures.

  1. Lasing in Bose-Fermi mixtures

    PubMed Central

    Kochereshko, Vladimir P.; Durnev, Mikhail V.; Besombes, Lucien; Mariette, Henri; Sapega, Victor F.; Askitopoulos, Alexis; Savenko, Ivan G.; Liew, Timothy C. H.; Shelykh, Ivan A.; Platonov, Alexey V.; Tsintzos, Simeon I.; Hatzopoulos, Z.; Savvidis, Pavlos G.; Kalevich, Vladimir K.; Afanasiev, Mikhail M.; Lukoshkin, Vladimir A.; Schneider, Christian; Amthor, Matthias; Metzger, Christian; Kamp, Martin; Hoefling, Sven; Lagoudakis, Pavlos; Kavokin, Alexey

    2016-01-01

    Light amplification by stimulated emission of radiation, well-known for revolutionising photonic science, has been realised primarily in fermionic systems including widely applied diode lasers. The prerequisite for fermionic lasing is the inversion of electronic population, which governs the lasing threshold. More recently, bosonic lasers have also been developed based on Bose-Einstein condensates of exciton-polaritons in semiconductor microcavities. These electrically neutral bosons coexist with charged electrons and holes. In the presence of magnetic fields, the charged particles are bound to their cyclotron orbits, while the neutral exciton-polaritons move freely. We demonstrate how magnetic fields affect dramatically the phase diagram of mixed Bose-Fermi systems, switching between fermionic lasing, incoherent emission and bosonic lasing regimes in planar and pillar microcavities with optical and electrical pumping. We collected and analyzed the data taken on pillar and planar microcavity structures at continuous wave and pulsed optical excitation as well as injecting electrons and holes electronically. Our results evidence the transition from a Bose gas to a Fermi liquid mediated by magnetic fields and light-matter coupling. PMID:26822483

  2. Lasing in Bose-Fermi mixtures

    NASA Astrophysics Data System (ADS)

    Kochereshko, Vladimir P.; Durnev, Mikhail V.; Besombes, Lucien; Mariette, Henri; Sapega, Victor F.; Askitopoulos, Alexis; Savenko, Ivan G.; Liew, Timothy C. H.; Shelykh, Ivan A.; Platonov, Alexey V.; Tsintzos, Simeon I.; Hatzopoulos, Z.; Savvidis, Pavlos G.; Kalevich, Vladimir K.; Afanasiev, Mikhail M.; Lukoshkin, Vladimir A.; Schneider, Christian; Amthor, Matthias; Metzger, Christian; Kamp, Martin; Hoefling, Sven; Lagoudakis, Pavlos; Kavokin, Alexey

    2016-01-01

    Light amplification by stimulated emission of radiation, well-known for revolutionising photonic science, has been realised primarily in fermionic systems including widely applied diode lasers. The prerequisite for fermionic lasing is the inversion of electronic population, which governs the lasing threshold. More recently, bosonic lasers have also been developed based on Bose-Einstein condensates of exciton-polaritons in semiconductor microcavities. These electrically neutral bosons coexist with charged electrons and holes. In the presence of magnetic fields, the charged particles are bound to their cyclotron orbits, while the neutral exciton-polaritons move freely. We demonstrate how magnetic fields affect dramatically the phase diagram of mixed Bose-Fermi systems, switching between fermionic lasing, incoherent emission and bosonic lasing regimes in planar and pillar microcavities with optical and electrical pumping. We collected and analyzed the data taken on pillar and planar microcavity structures at continuous wave and pulsed optical excitation as well as injecting electrons and holes electronically. Our results evidence the transition from a Bose gas to a Fermi liquid mediated by magnetic fields and light-matter coupling.

  3. Lasing in Bose-Fermi mixtures.

    PubMed

    Kochereshko, Vladimir P; Durnev, Mikhail V; Besombes, Lucien; Mariette, Henri; Sapega, Victor F; Askitopoulos, Alexis; Savenko, Ivan G; Liew, Timothy C H; Shelykh, Ivan A; Platonov, Alexey V; Tsintzos, Simeon I; Hatzopoulos, Z; Savvidis, Pavlos G; Kalevich, Vladimir K; Afanasiev, Mikhail M; Lukoshkin, Vladimir A; Schneider, Christian; Amthor, Matthias; Metzger, Christian; Kamp, Martin; Hoefling, Sven; Lagoudakis, Pavlos; Kavokin, Alexey

    2016-01-01

    Light amplification by stimulated emission of radiation, well-known for revolutionising photonic science, has been realised primarily in fermionic systems including widely applied diode lasers. The prerequisite for fermionic lasing is the inversion of electronic population, which governs the lasing threshold. More recently, bosonic lasers have also been developed based on Bose-Einstein condensates of exciton-polaritons in semiconductor microcavities. These electrically neutral bosons coexist with charged electrons and holes. In the presence of magnetic fields, the charged particles are bound to their cyclotron orbits, while the neutral exciton-polaritons move freely. We demonstrate how magnetic fields affect dramatically the phase diagram of mixed Bose-Fermi systems, switching between fermionic lasing, incoherent emission and bosonic lasing regimes in planar and pillar microcavities with optical and electrical pumping. We collected and analyzed the data taken on pillar and planar microcavity structures at continuous wave and pulsed optical excitation as well as injecting electrons and holes electronically. Our results evidence the transition from a Bose gas to a Fermi liquid mediated by magnetic fields and light-matter coupling. PMID:26822483

  4. Photoinduced bending behavior of cross-linked azobenzene liquid-crystalline polymer films with a poly(oxyethylene) backbone.

    PubMed

    Lv, Jiu-an; Wang, Weiru; Xu, Jixiang; Ikeda, Tomiki; Yu, Yanlei

    2014-07-01

    Cross-linked azobenzene liquid-crystalline polymer films with a poly(oxyethylene) backbone are synthesized by photoinitiated cationic copolymerization. Azobenzene moieties in the film surface toward the light source are simultaneously photoaligned during photopolymerization with unpolarized 436 nm light and thus form a splayed alignment in the whole film. The prepared films show reversible photoinduced bending behavior with opposite bending directions when different surfaces of one film face to ultraviolet light irradiation. PMID:24771514

  5. Factors affecting order, photopolymerization behavior, and nanostructure development of reactive lyotropic liquid crystals

    NASA Astrophysics Data System (ADS)

    Sievens Figueroa, Lucas

    2009-10-01

    Polymerization of reactive lyotropic liquid crystals (LLC) provides a facile means for the synthesis of nanostructured organic materials. In this work the photopolymerization kinetics and polymer structure evolution have been investigated. By studying the polymerization behavior and the order retention after polymerization, the contribution of the type of reactive surfactant, cross-linking, pH, and ionic strength on the LLC order preservation has been determined. Polymerization rates are higher in more highly ordered LLC phases compared to isotropic phases. In turn, reactive LLC phases that exhibit higher reaction rates also preserve the order to a greater extent during polymerization. Reactive surfactants with longer aliphatic tails exhibit lower order and lower reaction rates. The polymerization kinetics are highly driven by segregation of the reactive groups. Lower polymerization rates are observed in isotropic discontinuous phases for the surfactant monomer bearing the reactive group near the polar head while the opposite behavior is observed for surfactant monomer bearing the reactive group in the aliphatic tail. The effect of polymerization kinetics on the resulting polymer order has also been determined using small angle X-ray scattering (SAXS). By using high light intensity and a more efficient initiator, the LLC order is more likely to be retained after polymerization. LLC phases that exhibit higher degrees of order are formed at low ionic strength and low pH. Higher polymerization rates are observed as the ionic strength increases due to an increase in the propagation rate. Higher polymerization rates are also observed as the pH increases due to an increase in the propagation rates and decrease in termination rates. The addition of a crosslinker enables the retention of LLC phases after polymerization. Competing effects between crosslinking and order are observed in the polymerization kinetics as a decrease in polymerization rate is observed at high

  6. Possible spin liquid behavior in Sc2Ga2CuO7

    NASA Astrophysics Data System (ADS)

    Mahajan, A. V.; Kumar, R.; Khuntia, P.; Sheptyakov, D.; Freeman, P. G.; Ronnow, H. M.; Koteswararao, B.; Baenitz, M.; Furukawa, Y.; Jeong, M.

    The title compound crystallizes in a hexagonal structure (space group P63/mmc) containing edge-shared triangular planes as also triangular bi-planes. Our work establishes that the single triangular layers mainly have S = 0 Ga3+(85% Ga, 15% Cu), while the bi-layers contain 43% Cu2+ and 57% Ga3+, as far as the cations are concerned. Our χ (T) data shows no spin-freezing or magnetic long-range order (LRO) down to 1.8 K. We infer an effective moment of 1.79 μB and a θCW of about -50 K, suggesting AF interactions. In our specific heat data, no anomalies were found down to 0.35 K, in the field range 0-140 kOe. The magnetic specific heat has a nearly T2 power-law behavior at low- T (for H > 90 kOe). The 71Ga nuclear magnetic resonance (NMR) shift K (T) displays a broad maximum at T ~ 50 K. The 71Ga spin lattice relaxation rate 1/T1 displays a T 3 . 2 power-law increase from 0.1 K to 2 K, then remains nearly unchanged up to 10 K, and increases thereafter. Once again, down to 100 mK there is no indication of LRO which is usually manifested as an anomaly in the T-dependence of K and 1/T1. Our data suggest the formation of a quantum spin liquid in the S = 1 / 2 system Sc2Ga2CuO7.

  7. Strongly Interacting Fermi and Bose-Fermi Gases

    NASA Astrophysics Data System (ADS)

    Lee, Ye-Ryoung; Choi, Jae; Christensen, Caleb; Jo, Gyu-Boong; Wang, Tout; Ketterle, Wolfgang; Pritchard, David

    2010-03-01

    We present our recent progress on the study ultracold gases of ^6Li and ^23Na near homonuclear and heteronuclear Feshbach resonances. We discuss new experimental and theoretical developments on itinerant ferromagnetism in a Fermi gas of ultracold atoms [1]. We also report on ultracold gases of ^6Li and ^23Na, including fermionic LiNa molecules. [4pt] [1] G.-B. Jo, Y.-R. Lee, J.-H. Choi, C.A. Christensen, T.H. Kim, J.H. Thywissen, D.E. Pritchard, and W. Ketterle, Observation of itinerant ferromagnetism in a strongly interacting Fermi gas of ultracold atoms, Science 325, 1521 (2009).

  8. Ferromagnetism in a repulsive atomic Fermi gas with correlated disorder

    NASA Astrophysics Data System (ADS)

    Pilati, S.; Fratini, E.

    2016-05-01

    We investigate the zero-temperature ferromagnetic behavior of a two-component repulsive Fermi gas in the presence of a correlated random field that represents an optical speckle pattern. The density is tuned so that the (noninteracting) Fermi energy is close to the mobility edge of the Anderson localization transition. We employ quantum Monte Carlo simulations to determine various ground-state properties, including the equation of state, the magnetic susceptibility, and the energy of an impurity immersed in a polarized Fermi gas (repulsive polaron). In the weakly interacting limit, the magnetic susceptibility is found to be suppressed by disorder. However, it rapidly increases with the interaction strength, and it diverges at a much weaker interaction strength compared to the clean gas. Both the transition from the paramagnetic phase to the partially ferromagnetic phase, and the one from the partially to the fully ferromagnetic phase, are strongly favored by disorder, indicating a case of order induced by disorder.

  9. Luminescence behavior of silicon and carbon nanoparticles dispersed in low-polar liquids

    PubMed Central

    2012-01-01

    A comparative photoluminescence analysis of as-prepared and chemically modified (by alkyl chains -C18H37) silicon and carbon nanoparticles dispersed in low-polar liquids is reported. Influence of the low-polar liquid nature and ambient temperature on photoluminescence of the nanoparticles has been investigated from the point of view of their possible application as thermal nanoprobes. PMID:22748140

  10. Strongly Interacting Homogeneous Fermi Gases

    NASA Astrophysics Data System (ADS)

    Mukherjee, Biswaroop; Patel, Parth; Yan, Zhenjie; Struck, Julian; Zwierlein, Martin

    2016-05-01

    We present a homogeneous box potential for strongly interacting Fermi gases. The local density approximation (LDA) allows measurements on traditional inhomogeneous traps to observe a continuous distribution of Fermi gases in a single shot, but also suffer from a broadened response due to line-of-sight averaging over varying densities. We trap ultracold Fermionic (6 Li) in an optical homogeneous potential and characterize its flatness through in-situ tomography. A hybrid approach combining a cylindrical optical potential with a harmonic magnetic trap allows us to exploit the LDA and measure local RF spectra without requiring significant image reconstruction. We extract various quantities from the RF spectra such as the Tan's contact, and discuss further measurements of homogeneous Fermi systems under spin imbalance and finite temperature.

  11. Mechano-regulatory cellular behaviors of NIH/3T3 in response to the storage modulus of liquid crystalline substrates.

    PubMed

    Chen, Yang; Wang, Lei; Huang, Hao; Tan, Ruizhe; Zhao, Jupeng; Yang, Shenyu; Zeng, Rong; Wu, Hao; Zhang, Jiaqing; Yu, Bin; Tu, Mei

    2016-04-01

    The extent of substrate stiffness has been shown to be predominant in regulating cellular behaviors. Previous studies have used matrices such as elastomers or hydrogels to understand cell behavior. Herein, liquid crystalline matrices that resemble movable morphology of biomembrane and viscoelasticity were fabricated with tunable storage modulus for the evaluation of the modulus-driven cell behaviors. Our results demonstrated that NIH/3T3 cells showed a hypersensitive response to the storage modulus of liquid crystalline substrates by the alteration in attachment, spreading, proliferation and viability, polarization, cell cycle and apoptosis, and activity of mechano-transduction-related signal molecules including FAK, paxillin and ERK. The octyl hydroxypropyl cellulose substrates (OPC-1-5) with intermediate storage modulus of 12,312Pa and 7228Pa (OPC-2 and OPC-3 respectively) could provide more beneficial adhesion conditions leading to a larger spreading area, more elongated morphology and higher proliferation rates possibly through paxillin-ERK pathway, whereas the substrates with the highest or lowest storage modulus (16,723Pa, OPC-1; and 41Pa, OPC-5, respectively) appeared unfavorable for cell growth. Our study provides insights into the mechanism of modulus-driven cellular behaviors for better design of bioengineered cell substrates. PMID:26703364

  12. Aggregation Behavior of Imidazolium-Based Surface-Active Ionic Liquids with Photoresponsive Cinnamate Counterions in the Aqueous Solution.

    PubMed

    Bi, Yanhui; Zhao, Liuchen; Hu, Qiongzheng; Gao, Yan'an; Yu, Li

    2015-11-24

    Two imidazolium-based surface active ionic liquids (SAILs) with photoresponsive cinnamate aromatic counterions, viz. 1-dodecyl-3-methylimidazolium cinnamate ([C12mim][CA]) and 1-dodecyl-3-methylimidazolium para-hydroxy-cinnamate ([C12mim][PCA]), were newly synthesized, and their self-assembly behaviors in aqueous solutions were systematically explored. Results of surface tension and conductivity measurements show that both [C12mim][CA] and [C12mim][PCA] display a superior surface activity in aqueous solutions compared to the common imidazolium-based SAIL, 1-dodecyl-3-methylimidazolium bromide (C12mimBr), which implies the incorporation of cinnamate aromatic counterions can promote the micellar formation. Furthermore, [C12mim][CA] shows higher surface activity due to the higher hydrophobicity of its counterion in comparison to [C12mim][PCA] that has a hydroxyl group. Both hexagonal liquid-crystalline phase (H1) and cubic liquid-crystalline phase (V2) were constructed in the [C12mim][CA] aqueous solutions. In contrast, the [C12mim][PCA]/H2O system only exhibits a single hexagonal liquid-crystalline phase (H1) in a broad concentration region. These lyotropic liquid crystal (LLC) phases were comprehensively characterized by polarized optical microscopy (POM), small-angle X-ray scattering (SAXS), and rheometer. Investigation on the temperature-dependent self-assembly nanostructures demonstrates that the higher temperature leads to a looser arrangement. Under UV irradiation, trans-cis photoisomerization of the phenylalkene group results in inferior surface activity of the prepared SAILs in aqueous solution with higher cmc values. Moreover, UV light irradiation induces obvious change of the structural parameters without altering the LLC phases. This work is expected to enrich the investigations of phase behaviors formed in SAILs systems and receive particular attention due to their unique properties and potential applications in drug delivery, biochemistry, materials

  13. Optical Behaviors of Cholesteric Liquid-Crystalline Polyester Composites with Various Chiral Photochromic Dopants.

    PubMed

    Chien, Chih-Chieh; Liu, Jui-Hsiang

    2015-12-15

    New developments in the field of chiral nematic liquid crystals, such as color displays, are now being widely proposed. This article describes the tunable incident reflection band based on composite materials of low-molecular-weight chiroptical dopants and polymeric networks. These materials have advantages including easily manageable color according to a change in the helical pitch of the cholesteric liquid crystal upon exposure to light. A series of novel chiral dopants of isosorbide derivatives containing photochromic groups and three new main-chain liquid crystalline polyesters were synthesized and identified using nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), and elemental analyses. The phase-transition temperatures and the liquid-crystal phase determination of the synthesized polymers were estimated using DSC, WAXD, and POM analyses. The influence of the dopant concentrations and the solubility in a liquid crystalline polymer blend were also studied. The reflection band of the cholesteric liquid crystalline composites could be adjusted and tuned with a wide range of color variation across the entire visible region. A real image recording of the chiral photochromic liquid crystalline polymer blend was achieved by exposing it to UV light through a mask. PMID:26636344

  14. BEHAVIOR OF SURFACTANT MIXTURES AT SOLID/LIQUID AND OIL/LIQUID INTERFACES IN CHEMICAL FLOODING SYSTEMS

    SciTech Connect

    P. Somasundaran

    2004-11-20

    The aim of the project is to develop a knowledge base to help the design of enhanced processes for mobilizing and extracting untrapped oil. We emphasize evaluation of novel surfactant mixtures and obtaining optimum combinations of the surfactants for efficient chemical flooding EOR processes. In this regard, an understanding of the aggregate shape, size and structure is crucial since these properties govern the crude oil removal efficiency. During the three-year period, the adsorption and aggregation behavior of sugar-based surfactants and their mixtures with other types of surfactants have been studied. Sugar-based surfactants are made from renewable resources, nontoxic and biodegradable. They are miscible with water and oil. These environmentally benign surfactants feature high surface activity, good salinity, calcium and temperature tolerance, and unique adsorption behavior. They possess the characteristics required for oil flooding surfactants and have the potential for replacing currently used surfactants in oil recovery. A novel analytical ultracentrifugation technique has been successfully employed for the first time, to characterize the aggregate species present in mixed micellar solution due to its powerful ability to separate particles based on their size and shape and monitor them simultaneously. Analytical ultracentrifugation offers an unprecedented opportunity to obtain important information on mixed micelles, structure-performance relationship for different surfactant aggregates in solution and their role in interfacial processes. Initial sedimentation velocity investigations were conducted using nonyl phenol ethoxylated decyl ether (NP-10) to choose the best analytical protocol, calculate the partial specific volume and obtain information on sedimentation coefficient, aggregation mass of micelles. Four softwares: OptimaTM XL-A/XL-I data analysis software, DCDT+, Svedberg and SEDFIT, were compared for the analysis of sedimentation velocity

  15. Lithium ion conductive behavior of TiO2 nanotube/ionic liquid matrices

    PubMed Central

    2014-01-01

    A series of TiO2 nanotube (TNT)/ionic liquid matrices were prepared, and their lithium ion conductive properties were studied. SEM images implied that ionic liquid was dispersed on the whole surface of TNT. Addition of TNT to ionic liquid (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (BMImTFSA)) resulted in significant increase of ionic conductivity. Furthermore, lithium transference number was also largely enhanced due to the interaction of anion with TNT. Vogel-Fulcher-Tammann parameter showed higher carrier ion number for TNT/BMImTFSA in comparison with BMImTFSA. PMID:25313300

  16. The Rheological Behavior of Multiphase Liquids Characterized by an Advanced Dilatometric Method

    NASA Astrophysics Data System (ADS)

    Helo, C. S.; Hess, K.; Potuzak, M.; Dingwell, D. B.

    2006-12-01

    Silicic volcanic rocks often contain a glassy groundmatrix. During formation of the glass when the liquid line of descent intersects the glass transition interval, all magmatic processes (e.g. crystallization, nucleation of bubbles) are frozen in. A corresponding `glass transition temperature' Tg can be determined by measuring changes in the temperature dependence of enthalpy (H) or volume (V) of the sample during subsequent reheating. The glass transition temperature is strongly dependent on the cooling rate which the sample experienced when the glass matrix was formed. Especially for silica-rich rocks the calorimetric analysis is usually hampered by the loss of the characteristic peaks in the time derivative curves, due to the presence of phenocrysts, microlites, or bubbles. However, it is possible to extract two characteristic features from the dilatometric dV/dt curve (in contrast to dH/dt), a dilatometrical `onset' and a `softening' temperature (Tg on and Tg soft, respectively). The method has been calibrated using a series well-known synthetic melt compositions ranging in NBO/T (non-bridging oxygen NBO over tetrahedral coordinated cations T) from 0 - 0.6. For these melts the viscosities at Tg on and Tg soft have been calculated. The viscosity at Tg on shows no compositional dependence on composition at fixed cooling and heating rates, and the precision is comparable to the conventional dilatometrical and calorimetrical measurements. The determination of Tg soft is even more precise (only approx. half the standard deviation) in contrast to the standard methods. Moreover, with one single measurement it is possible to determine directly the fragility of the melt, defined as the temperature dependence of the structural relaxation time at Tg on, by using a new parameter Fv = (Tg soft - Tg on) / Tg on. Measurements on selected pristine samples from several silicic volcanic centers have shown different trends. Throughout repeated heating / cooling with fixed rates

  17. Fermi Finds Youthful Pulsar Among Ancient Stars

    NASA Video Gallery

    In three years, NASA's Fermi has detected more than 100 gamma-ray pulsars, but something new has appeared. Among a type of pulsar with ages typically numbering a billion years or more, Fermi has fo...

  18. Investigation on the effect of microstructure of proton exchange membrane fuel cell porous layers on liquid water behavior by soft X-ray radiography

    NASA Astrophysics Data System (ADS)

    Sasabe, Takashi; Deevanhxay, Phengxay; Tsushima, Shohji; Hirai, Shuichiro

    2011-10-01

    In order to investigate the effect of microstructure of PEMFC porous layers on the liquid water transport, liquid water accumulation and discharge behavior in the operating PEMFC was visualized by laboratory-based soft X-ray radiography. The utilization of low energy X-ray made it possible to visualize the liquid water behavior in the PEMFC with the spatial resolution of 0.8 μm and the temporal resolution of 2.0 s frame-1, and the cross-sectional imaging can resolve the each components of the PEMFC. The visualization results showed that adding the MPL prevents the accumulation of liquid water in the substrate layer from contacting and forming the liquid water film on the catalyst layer. Furthermore, it was found that the liquid water distribution in the carbon paper and the carbon cloth GDL was completely different. The liquid water in the carbon cloth GDL concentrates at the weaves of fiber bundle and was effectively discharged to the channel. These visualization results suggested that the microstructure of the PEMFC porous layers strongly affect the liquid water behavior in the PEMFC, and the detailed understanding of the pore structures and the network of liquid water is essential for keeping the oxygen transport path to the catalyst site.

  19. Communication: High pressure specific heat spectroscopy reveals simple relaxation behavior of glass forming molecular liquid

    NASA Astrophysics Data System (ADS)

    Roed, Lisa Anita; Niss, Kristine; Jakobsen, Bo

    2015-12-01

    The frequency dependent specific heat has been measured under pressure for the molecular glass forming liquid 5-polyphenyl-4-ether in the viscous regime close to the glass transition. The temperature and pressure dependences of the characteristic time scale associated with the specific heat is compared to the equivalent time scale from dielectric spectroscopy performed under identical conditions. It is shown that the ratio between the two time scales is independent of both temperature and pressure. This observation is non-trivial and demonstrates the existence of specially simple molecular liquids in which different physical relaxation processes are both as function of temperature and pressure/density governed by the same underlying "inner clock." Furthermore, the results are discussed in terms of the recent conjecture that van der Waals liquids, like the measured liquid, comply to the isomorph theory.

  20. Fermi GBM Early Trigger Characteristics

    SciTech Connect

    Connaughton, Valerie; Briggs, Michael; Paciesas, Bill; Meegan, Charles

    2009-05-25

    Since the launch of the Fermi observatory on June 11 2008, the Gamma-ray Burst Monitor (GBM) has seen approximately 250 triggers of which about 150 were cosmic gamma-ray bursts (GRBs). GBM operates dozens of trigger algorithms covering various energy bands and timescales and is therefore sensitive to a wide variety of phenomena, both astrophysical and not.

  1. Fermi's Large Area Telescope (LAT)

    NASA Video Gallery

    Fermi’s Large Area Telescope (LAT) is the spacecraft’s main scientificinstrument. This animation shows a gamma ray (purple) entering the LAT,where it is converted into an electron (red) and a...

  2. CCC and the Fermi paradox

    NASA Astrophysics Data System (ADS)

    Gurzadyan, V. G.; Penrose, R.

    2016-01-01

    Within the scheme of conformal cyclic cosmology (CCC), information can be transmitted from aeon to aeon. Accordingly, the "Fermi paradox" and the SETI programme --of communication by remote civilizations-- may be examined from a novel perspective: such information could, in principle, be encoded in the cosmic microwave background. The current empirical status of CCC is also discussed.

  3. Fermi, Enrico (1901-54)

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    Italian physicist, created the first controlled chain reaction, founded Argonne National Laboratory. His work on the properties of electrons (spin-half particles like electrons are called fermions after him, and the study of their properties is called Fermi-Dirac statistics) enabled the pressure source in white dwarf stars to be identified, and white dwarf star properties to be calculated by CHAN...

  4. Fermi's β-DECAY Theory

    NASA Astrophysics Data System (ADS)

    Yang, Chen Ning

    2013-05-01

    Throughout his lifetime Enrico Fermi (1901-1954) had considered his 1934 β-decay theory as his most important contribution to theoretical physics. E. Segrè (1905-1989) had vividly written about an episode at the inception of that paper:1...

  5. Influence of interspecific competition on the recruitment behavior and liquid food transport in the tramp ant species Pheidole megacephala

    NASA Astrophysics Data System (ADS)

    Dejean, Alain; Breton, Julien; Suzzoni, Jean Pierre; Orivel, Jérôme; Saux-Moreau, Corrie

    2005-07-01

    This study was conducted on the reactions of Pheidole megacephala scouts when finding liquid food sources situated on territories marked by competing dominant ant species or on unmarked, control areas to see if the number of recruited nestmates is affected and if soldiers behave in ways adapted to the situation. We show that scouts recruit more nestmates, particularly soldiers, on marked rather than on unmarked areas. This recruitment allows P. megacephala to organize the defence and rapid depletion of these food sources prior to any contact with competitors. Soldiers can carry liquid foods both (1) in their crops like other Myrmicinae and (2), in a new finding concerning myrmicine ants, under their heads and thoraxes like certain poneromorph genera because the droplets adhere through surface tension strengths. Later, the liquids stored in the crop are distributed to nestmates through regurgitations during trophallaxis and the external droplets are distributed through “social buckets”, or the mode of liquid food transfer common in poneromorphs. Their flexibility to use or not use the latter technique, based on the situation, corroborates other reports that Pheidole soldiers have a relatively large behavioral repertoire.

  6. Pressure profiles of nonuniform two-dimensional atomic Fermi gases

    NASA Astrophysics Data System (ADS)

    Martiyanov, Kirill; Barmashova, Tatiana; Makhalov, Vasiliy; Turlapov, Andrey

    2016-06-01

    Spatial profiles of the pressure have been measured in atomic Fermi gases with primarily two-dimensional (2D) kinematics. The in-plane motion of the particles is confined by a Gaussian-shape potential. The two-component deeply degenerate Fermi gases are prepared at different values of the s -wave attraction. The pressure profile is found using the force-balance equation, from the measured density profile and the trapping potential. The pressure is compared to zero-temperature models within the local density approximation. In the weakly interacting regime, the pressure lies above a Landau Fermi-liquid theory and below the ideal-Fermi-gas model, whose prediction coincides with that of the Cooper-pair mean-field theory. The values closest to the data are provided by the approach where the mean field of Cooper pairs is supplemented with fluctuations. In the regime of strong interactions, in response to the increasing attraction, the pressure shifts below this model reaching lower values calculated within Monte Carlo methods. Comparison to models shows that interaction-induced departure from 2D kinematics is either small or absent. In particular, comparison with a lattice Monte Carlo suggests that kinematics is two dimensional in the strongly interacting regime.

  7. Pronounced asymmetry in the crystallization behavior during constant heating and cooling of a bulk metallic glass-forming liquid

    SciTech Connect

    Schroers, J.; Masuhr, A.; Johnson, W.L.; Busch, R.

    1999-11-01

    The crystallization behavior of the supercooled bulk metallic glass-forming Zr{sub 41}Ti{sub 14}Cu{sub 12}Ni{sub 10}Be{sub 23} liquid was studied with different heating and cooling rates. A rate of about 1 K/s is sufficient to suppress crystallization of the melt upon cooling from the equilibrium liquid. Upon heating, in contrast, a rate of about 200 K/s is necessary to avoid crystallization. The difference between the critical heating and cooling rate is discussed with respect to diffusion-limited growth taking classical nucleation into account. The calculated asymmetry of the critical heating and cooling rate can be explained by the fact that nuclei formed during cooling and heating are exposed to different growth rates. thinsp {copyright} {ital 1999} {ital The American Physical Society}

  8. Liquid-crystalline and microemulsion phase behavior in alcohol-free aerosol-OT/oil/brine systems

    SciTech Connect

    Ghosh, O.; Miller, C.A.

    1987-08-13

    The phase behavior of systems containing the pure anionic surfactant Aerosol OT or sodium bis(2-ethylhexyl) sulfosuccinate was studied as a function of salt concentration, surfactant concentration, alkane carbon number, and water-to-oil ratio. Since the hydrophilic and lipophilic properties of Aerosol OT are nearly balanced, the surfactant forms microemulsions with water and oil in the absence of cosurfactant, allowing for simplified representation of phase behavior. In particular, this property aided in the understanding of transitions between the aqueous surfactant phase behavior and the well-studied oil-rich microemulsion regime. With the addition of salt to dilute alcohol-free surfactant-water mixtures, transitions in the liquid-crystalline phases similar to those seen previously for systems containing petroleum sulfonates and other anionic surfactants with alcohol cosurfactants were found. When hydrocarbons of various chain lengths were equilibrated with the aqueous surfactant solutions, again behavior similar to that of anionic surfactants with alcohol cosurfactants was observed. Pseudoternary diagrams of surfactant-brine-oil were constructed at various brine salinities with n-dodecane as the oil. The assumption that brine acts as a pseudocomponent was found to work best at salinities well below and well above the optimum and at low surfactant concentrations. In any case, the results provide extensive information on phase behavior of a four-component system containing a pure anionic surfactant, a pure hydrocarbon, and sodium chloride brine over a region of considerable interest for enhanced oil recovery and other applications.

  9. Alkyl-Based Surfactants at a Liquid Mercury Surface: Computer Simulation of Structure, Self-Assembly, and Phase Behavior.

    PubMed

    Iakovlev, Anton; Bedrov, Dmitry; Müller, Marcus

    2016-04-21

    Self-assembled organic films on liquid metals feature a very rich phase behavior, which qualitatively differs from the one on crystalline metals. In contrast to conventional crystalline supports, self-assembled alkylthiol monolayers on liquid metals possess a considerably higher degree of molecular order, thus enabling much more robust metal-molecule-semiconductor couplings for organic electronics applications. Yet, compared to crystalline substrates, the self-assembly of organic surfactants on liquid metals has been studied to a much lesser extent. In this Letter we report the first of its kind molecular simulation investigation of alkyl-based surfactants on a liquid mercury surface. The focus of our investigation is the surfactant conformations as a function of surface coverage and surfactant type. First, we consider normal alkanes because these systems set the basis for simulations of all other organic surfactants on liquid mercury. Subsequently, we proceed with the discussion of alkylthiols that are the most frequently used surfactants in the surface science of hybrid organometallic interfaces. Our results indicate a layering transition of normal alkanes as well as alkylthiols from an essentially bare substrate to a completely filled monolayer of laying molecules. As the surface coverage increases further, we observe a partial wetting of the laying monolayer by the bulk phase of alkanes. In the case of alkylthiols, we clearly see the coexistence of molecules in laying-down and standing-up conformations, in which the sulfur headgroups of the thiols are chemically bound to mercury. In the standing-up phase, the headgroups form an oblique lattice. For the first time we were able to explicitly characterize the molecular-scale structure and transitions between phases of alkyl-based surfactants and to demonstrate how the presence of a thiol headgroup qualitatively changes the phase equilibrium and structure in these systems. The observed phenomena are consistent with

  10. Adaptive Optics with a Liquid-Crystal-on-Silicon Spatial Light Modulator and Its Behavior in Retinal Imaging

    NASA Astrophysics Data System (ADS)

    Shirai, Tomohiro; Takeno, Kohei; Arimoto, Hidenobu; Furukawa, Hiromitsu

    2009-07-01

    An adaptive optics system with a brand-new device of a liquid-crystal-on-silicon (LCOS) spatial light modulator (SLM) and its behavior in in vivo imaging of the human retina are described. We confirmed by experiments that closed-loop correction of ocular aberrations of the subject's eye was successfully achieved at the rate of 16.7 Hz in our system to obtain a clear retinal image in real time. The result suggests that an LCOS SLM is one of the promising candidates for a wavefront corrector in a prospective commercial ophthalmic instrument with adaptive optics.

  11. Investigaction of Switching Behavior in a Ferroelectric Liquid Crystal Aligned on Obliquely Deposited SiO Films

    NASA Astrophysics Data System (ADS)

    Yamada, Yuichiro; Yamamoto, Norio; Inoue, Tetsuya; Orihara, Hiroshi; Ishibashi, Yoshihiro

    1989-01-01

    The effect of oblique evaporation of SiO on the chevron structure and the switching behavior in a ferroelectric liquid crystal have been investigated by means of the X-ray diffraction and the stroboscopic micrographs. It is found experimentally that the chevron direction and the domain structure appearing during the switching are determined by the direction of incidence of evaporated SiO. On the basis of the experimental results, it is clarified that the bow and the stern of the boat-shaped domain correspond to {+}2π and {-}2π internal disclinations, respectively. The structure of the zig-zag defect is determined.

  12. The Gamma-ray Universe through Fermi

    NASA Technical Reports Server (NTRS)

    Thompson, David J.

    2012-01-01

    Gamma rays, the most powerful form of light, reveal extreme conditions in the Universe. The Fermi Gamma-ray Space Telescope and its smaller cousin AGILE have been exploring the gamma-ray sky for several years, enabling a search for powerful transients like gamma-ray bursts, novae, solar flares, and flaring active galactic nuclei, as well as long-term studies including pulsars, binary systems, supernova remnants, and searches for predicted sources of gamma rays such as dark matter annihilation. Some results include a stringent limit on Lorentz invariance derived from a gamma-ray burst, unexpected gamma-ray variability from the Crab Nebula, a huge ga.nuna-ray structure associated with the center of our galaxy, surprising behavior from some gamma-ray binary systems, and a possible constraint on some WIMP models for dark matter.

  13. The Gamma-ray Sky with Fermi

    NASA Technical Reports Server (NTRS)

    Thompson, David

    2012-01-01

    Gamma rays reveal extreme, nonthermal conditions in the Universe. The Fermi Gamma-ray Space Telescope has been exploring the gamma-ray sky for more than four years, enabling a search for powerful transients like gamma-ray bursts, novae, solar flares, and flaring active galactic nuclei, as well as long-term studies including pulsars, binary systems, supernova remnants, and searches for predicted sources of gamma rays such as dark matter annihilation. Some results include a stringent limit on Lorentz invariance derived from a gamma-ray burst, unexpected gamma-ray variability from the Crab Nebula, a huge gamma-ray structure associated with the center of our galaxy, surprising behavior from some gamma-ray binary systems, and a possible constraint on some WIMP models for dark matter.

  14. Photoresponsive Liquid Crystalline Epoxy Networks with Shape Memory Behavior and Dynamic Ester Bonds.

    PubMed

    Li, Yuzhan; Rios, Orlando; Keum, Jong K; Chen, Jihua; Kessler, Michael R

    2016-06-22

    Functional polymers are intelligent materials that can respond to a variety of external stimuli. However, these materials have not yet found widespread real world applications because of the difficulties in fabrication and the limited number of functional building blocks that can be incorporated into a material. Here, we demonstrate a simple route to incorporate three functional building blocks (azobenzene chromophores, liquid crystals, and dynamic covalent bonds) into an epoxy-based liquid crystalline network (LCN), in which an azobenzene-based epoxy monomer is polymerized with an aliphatic dicarboxylic acid to create exchangeable ester bonds that can be thermally activated. All three functional building blocks exhibited good compatibility, and the resulting materials exhibits various photomechanical, shape memory, and self-healing properties because of the azobenzene molecules, liquid crystals, and dynamic ester bonds, respectively. PMID:27245744

  15. Effect of molecular architecture on the electrorheological behavior of liquid crystal polymers in nematic solvents

    NASA Astrophysics Data System (ADS)

    Chiang, Yen-Ching

    1998-11-01

    The Miesowicz viscosities of dilute nematic solutions of liquid crystal polymers (LCP) in low molar mass nematic solvents have been measured by a cone-and-plate rheometer in the presence of a saturated electric field applied perpendicular to the shear plane. For mixtures with a positive dielectric anisotropy in the presence of the electric field the nematic director is perpendicular to the velocity gradient and the viscosity measured is the Miesowicz viscosity ηc. With the electric field off the nematic director orients parallel to the shear flow direction and the viscosity measured is closed to the Miesowicz viscosity η b. Specifically, we show that main-chain LCPs strongly increase the magnitude of the electrorheological (ER) response, ηc-ηb, a side-on side chain LCP moderately increases the response, and an end- on side-chain LCP weakly increases the response. The diverse behaviors can be interpreted using theoretical arguments which assume that the LCP conformation is an ellipsoid of revolution whose orientation relative to the flow is determined by the balance between the hydrodynamic and electric torques on the fluid. For the main-chain LCP TPB10 in 5OCB, which has mesogenic groups separated by decamethylene spacers, the intrinsic Miesowicz viscosity [ηc] was found to follow a Mark-Houwink-Sakurada relationship [ηc]/propto M/sp/alpha with α~1 and the configurational relaxation time (τR) shows a strong dependence on molecular weight, τR/propto M/sp/beta with β~2. Applying a theoretical description by Brochard, these results suggest that TPB10 behaves hydrodynamically like a free-draining random coil stretched along the director. The temperature dependence of Miesowicz viscosities η c and η b of LCPs dissolved in nematic solvent E48 was also investigated. The variations in δeta c and δeta c with temperature can be described by the Brochard theory in terms of the corresponding variation of the configurational anisotropy (R///R/sb/perp) with

  16. Effect of stress states on the deformation behavior of Cu-based bulk metallic glass in the supercooled liquid region

    SciTech Connect

    Park, Eun Soo; Kim, Hyong June; Bae, J. C.; Huh, M. Y.

    2013-01-24

    The effect of stress states on the deformation behavior of the Cu54Zr22Ti18Ni6 bulk metallic glass (BMG) alloy was studied in the supercooled liquid region. At 723 K, Newtonian plastic flow governed the deformation during the compression test, whereas strain-hardening occurred during the tensile test. At 733 K, a fast failure was observed during tensile test. The diffusion rate of Cu atoms in the BMG alloy plays an important role in the deformation behavior. The fast diffusion of Cu atoms under the tensile stress state caused faster crystallization leading to a fast strain-hardening during the tensile plastic deformation. Published by Elsevier B.V.

  17. From ultracold Fermi Gases to Neutron Stars

    NASA Astrophysics Data System (ADS)

    Salomon, Christophe

    2012-02-01

    Ultracold dilute atomic gases can be considered as model systems to address some pending problem in Many-Body physics that occur in condensed matter systems, nuclear physics, and astrophysics. We have developed a general method to probe with high precision the thermodynamics of locally homogeneous ultracold Bose and Fermi gases [1,2,3]. This method allows stringent tests of recent many-body theories. For attractive spin 1/2 fermions with tunable interaction (^6Li), we will show that the gas thermodynamic properties can continuously change from those of weakly interacting Cooper pairs described by Bardeen-Cooper-Schrieffer theory to those of strongly bound molecules undergoing Bose-Einstein condensation. First, we focus on the finite-temperature Equation of State (EoS) of the unpolarized unitary gas. Surprisingly, the low-temperature properties of the strongly interacting normal phase are well described by Fermi liquid theory [3] and we localize the superfluid phase transition. A detailed comparison with theories including recent Monte-Carlo calculations will be presented. Moving away from the unitary gas, the Lee-Huang-Yang and Lee-Yang beyond-mean-field corrections for low density bosonic and fermionic superfluids are quantitatively measured for the first time. Despite orders of magnitude difference in density and temperature, our equation of state can be used to describe low density neutron matter such as the outer shell of neutron stars. [4pt] [1] S. Nascimbène, N. Navon, K. Jiang, F. Chevy, and C. Salomon, Nature 463, 1057 (2010) [0pt] [2] N. Navon, S. Nascimbène, F. Chevy, and C. Salomon, Science 328, 729 (2010) [0pt] [3] S. Nascimbène, N. Navon, S. Pilati, F. Chevy, S. Giorgini, A. Georges, and C. Salomon, Phys. Rev. Lett. 106, 215303 (2011)

  18. Thin-thick coexistence behavior of 8CB liquid crystalline films on silicon.

    PubMed

    Garcia, R; Subashi, E; Fukuto, M

    2008-05-16

    The wetting behavior of thin films of 4-n-octyl-4'-cyanobiphenyl (8CB) on Si is investigated via optical and x-ray reflectivity measurement. An experimental phase diagram is obtained showing a broad thick-thin coexistence region spanning the bulk isotropic-to-nematic (T(IN)) and the nematic-to-smectic-A (T(NA)) temperatures. For Si surfaces with coverages between 47 and 72 +/- 3 nm, reentrant wetting behavior is observed twice as we increase the temperature, with separate coexistence behaviors near T(IN) and T(NA). For coverages less than 47 nm, however, the two coexistence behaviors merge into a single coexistence region. The observed thin-thick coexistence near the second-order NA transition is not anticipated by any previous theory or experiment. Nevertheless, the behavior of the thin and thick phases within the coexistence regions is consistent with this being an equilibrium phenomenon. PMID:18518487

  19. Behavior of Avirulent Yersinia pestis in Liquid Whole Egg as Affected by Antimicrobials and Thermal Pasteurization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Yersinia spp. is a psychrotrophic bacterium that can grow at temperatures as low as minus two degrees Celsius, and is known to contaminate shell eggs in the United States and shell eggs and liquid egg in South America. A study was performed to determine the thermal sensitivity of avirulent Yersinia...

  20. PREDICTION OF TRANSIENT BEHAVIOR DURING BATCH INCINERATION OF LIQUID WASTES IN ROTARY KILNS

    EPA Science Inventory

    The paper discusses a theoretical model which was designed to: (1) provide insight into why, for liquid wastes, "puffs" are very easily generated, and why their magnitudes and intensities increase with increasing kiln temperature and speed of rotation; and (2) predict how the gen...

  1. Fermi resonance in optical microcavities

    NASA Astrophysics Data System (ADS)

    Yi, Chang-Hwan; Yu, Hyeon-Hye; Lee, Ji-Won; Kim, Chil-Min

    2015-04-01

    Fermi resonance is a phenomenon of quantum mechanical superposition, which most often occurs between normal and overtone modes in molecular systems that are nearly coincident in energy. We find that scarred resonances in deformed dielectric microcavities are the very phenomenon of Fermi resonance, that is, a pair of quasinormal modes interact with each other due to coupling and a pair of resonances are generated through an avoided resonance crossing. Then the quantum number difference of a pair of quasinormal modes, which is a consequence of quantum mechanical superposition, equals periodic orbits, whereby the resonances are localized on the periodic orbits. We derive the relation between the quantum number difference and the periodic orbits and confirm it in an elliptic, a rectangular, and a stadium-shaped dielectric microcavity.

  2. Heat capacity and sound velocities of low dimensional Fermi gases

    NASA Astrophysics Data System (ADS)

    Salas, P.; Solis, M. A.

    2014-03-01

    We report the heat capacity ratio and sound velocities for an interactionless Fermi gas immersed in periodic structures such as penetrable multilayers or multitubes created by one (planes) or two perpendicular (tubes) external Dirac comb potentials. The isobaric specific heat of the fermion gas presents the dimensional crossover previously observed in the isochoric specific heat - from 3D to 2D or to 1D -. The quotient between the two quantities has a prominent bump related to the confinement, and as the temperature increases, it goes towards the monoatomic classical gas value 5/3. We present the isothermal and the adiabatic sound velocities of the fermion gas which show anomalous behavior at temperatures below TF due to the dimensionality of the system, while at higher temperatures again we recover the behavior of a classical Fermi gas. Furthermore, as the temperature goes to zero the sound velocity has a finite value, as expected.

  3. A Fast Scanning Calorimetric Comparison Study of Crystallization Behavior between Semi-crystalline Polymers and Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Zhou, Dongshan; Jiang, Jing; Wei, Lai; Huang, Zhijie; Xue, Gi

    2013-03-01

    Mesomorphic state with similar liquid crystal order was found to precede the crystallization in many polymers, so the study of nucleation and crystallization from a liquid crystal can provide reference for the study of polymers. The same procedure to study the nucleation and crystallization of semi-crystalline polymers was used to study 4-cyano-4'-octyloxy biphenyl-carbonitrile (8OCB). Different from metastable semi-crystalline polymers of multi-folded chains, whose melting temperature was basically continuously dependent on the crystallization temperature, melting temperature of 8OCB should have definite values, corresponding to disordering of four different polymorphism modifications at 309.0 K, 319.0 K, 325.0 K, and 327.0K, respectively. But, a lower temperature melting peak below 300K was found when 8OCB was annealed at temperature below 250K. More importantly, the peak temperature shifted positively with the increasing annealing temperature, just the same as that of semi-crystalline polymers. At the moment, we were not sure about the structure of the metamorphism and why small molecular liquid crystal showed similar melting behavior that was thought only inherited to chain like semi-crystalline polymers. This work is financially supported by the 973 Program(2012CB821500) and NSFC (No: 21027006,21274059)

  4. Leaching behavior of copper from waste printed circuit boards with Brønsted acidic ionic liquid.

    PubMed

    Huang, Jinxiu; Chen, Mengjun; Chen, Haiyan; Chen, Shu; Sun, Quan

    2014-02-01

    In this work, a Brønsted acidic ionic liquid, 1-butyl-3-methyl-imidazolium hydrogen sulfate ([bmim]HSO4), was used to leach copper from waste printed circuit boards (WPCBs, mounted with electronic components) for the first time, and the leaching behavior of copper was discussed in detail. The results showed that after the pre-treatment, the metal distributions were different with the particle size: Cu, Zn and Al increased with the increasing particle size; while Ni, Sn and Pb were in the contrary. And the particle size has significant influence on copper leaching rate. Copper leaching rate was higher than 99%, almost 100%, when 1g WPCBs powder was leached under the optimum conditions: particle size of 0.1-0.25 mm, 25 mL 80% (v/v) ionic liquid, 10 mL 30% hydrogen peroxide, solid/liquid ratio of 1/25, 70°C and 2h. Copper leaching by [bmim]HSO4 can be modeled with the shrinking core model, controlled by diffusion through a solid product layer, and the kinetic apparent activation energy has been calculated to be 25.36 kJ/mol. PMID:24246577

  5. Enrico Fermi and the Dolomites

    NASA Astrophysics Data System (ADS)

    Battimelli, Giovanni; de Angelis, Alessandro

    2014-11-01

    Summer vacations in the Dolomites were a tradition among the professors of the Faculty of Mathematical and Physical Sciences at the University of Roma since the end of the XIX century. Beyond the academic walls, people like Tullio Levi-Civita, Federigo Enriques and Ugo Amaldi sr., together with their families, were meeting friends and colleagues in Cortina, San Vito, Dobbiaco, Vigo di Fassa and Selva, enjoying trekking together with scientific discussions. The tradition was transmitted to the next generations, in particular in the first half of the XX century, and the group of via Panisperna was directly connected: Edoardo Amaldi, the son of the mathematician Ugo sr., rented at least during two summers, in 1925 and in 1949, and in the winter of 1960, a house in San Vito di Cadore, and almost every year in the Dolomites; Enrico Fermi was a frequent guest. Many important steps in modern physics, in particular the development of the Fermi-Dirac statistics and the Fermi theory of beta decay, are related to scientific discussions held in the region of the Dolomites.

  6. Fermi Timing and Synchronization System

    SciTech Connect

    Wilcox, R.; Staples, J.; Doolittle, L.; Byrd, J.; Ratti, A.; Kaertner, F.X.; Kim, J.; Chen, J.; Ilday, F.O.; Ludwig, F.; Winter, A.; Ferianis, M.; Danailov, M.; D'Auria, G.

    2006-07-19

    The Fermi FEL will depend critically on precise timing of its RF, laser and diagnostic subsystems. The timing subsystem to coordinate these functions will need to reliably maintain sub-100fs synchronicity between distant points up to 300m apart in the Fermi facility. The technology to do this is not commercially available, and has not been experimentally demonstrated in a working facility. Therefore, new technology must be developed to meet these needs. Two approaches have been researched by different groups working with the Fermi staff. At MIT, a pulse transmission scheme has been developed for synchronization of RF and laser devices. And at LBL, a CW transmission scheme has been developed for RF and laser synchronization. These respective schemes have advantages and disadvantages that will become better understood in coming years. This document presents the work done by both teams, and suggests a possible system design which integrates them both. The integrated system design provides an example of how choices can be made between the different approaches without significantly changing the basic infrastructure of the system. Overall system issues common to any synchronization scheme are also discussed.

  7. Mechanical and optical behavior of a tunable liquid lens using a variable cross section membrane: modeling results

    NASA Astrophysics Data System (ADS)

    Flores-Bustamante, Mario C.; Rosete-Aguilar, Martha; Calixto, Sergio

    2016-03-01

    A lens containing a liquid medium and having at least one elastic membrane as one of its components is known as an elastic membrane lens (EML). The elastic membrane may have a constant or variable thickness. The optical properties of the EML change by modifying the profile of its elastic membrane(s). The EML formed of elastic constant thickness membrane(s) have been studied extensively. However, EML information using elastic membrane of variable thickness is limited. In this work, we present simulation results of the mechanical and optical behavior of two EML with variable thickness membranes (convex-plane membranes). The profile of its surfaces were modified by liquid medium volume increases. The model of the convex-plane membranes, as well as the simulation of its mechanical behavior, were performed using Solidworks® software; and surface's points of the deformed elastic lens were obtained. Experimental stress-strain data, obtained from a silicone rubber simple tensile test, according to ASTM D638 norm, were used in the simulation. Algebraic expressions, (Schwarzschild formula, up to four deformation coefficients, in a cylindrical coordinate system (r, z)), of the meridional profiles of the first and second surfaces of the deformed convex-plane membranes, were obtained using the results from Solidworks® and a program in the software Mathematica®. The optical performance of the EML was obtained by simulation using the software OSLO® and the algebraic expressions obtained in Mathematica®.

  8. Vapor-liquid equilibrium and critical behavior of the square-well fluid of variable range: a theoretical study.

    PubMed

    Schöll-Paschinger, Elisabeth; Benavides, Ana Laura; Castañeda-Priego, Ramon

    2005-12-15

    The vapor-liquid phase behavior and the critical behavior of the square-well (SW) fluid are investigated as a function of the interaction range, lambdain [1.25, 3], by means of the self-consistent Ornstein-Zernike approximation (SCOZA) and analytical equations of state based on a perturbation theory [A. L. Benavides and F. del Rio, Mol. Phys. 68, 983 (1989); A. Gil-Villegas, F. del Rio, and A. L. Benavides, Fluid Phase Equilib. 119, 97 (1996)]. For this purpose the SCOZA, which has been restricted up to now to a few model systems, has been generalized to hard-core systems with arbitrary interaction potentials requiring a fully numerical solution of an integro-partial differential equation. Both approaches, in general, describe well the liquid-vapor phase diagram of the square-well fluid when compared with simulation data. SCOZA yields very precise predictions for the coexistence curves in the case of long ranged SW interaction (lambda>1.5), and the perturbation theory is able to predict the binodal curves and the saturated pressures, for all interaction ranges considered if one stays away from the critical region. In all cases, the SCOZA gives very good predictions for the critical temperatures and the critical pressures, while the perturbation theory approach tends to slightly overestimate these quantities. Furthermore, we propose analytical expressions for the critical temperatures and pressures as a function of the square-well range. PMID:16392937

  9. A Fermi gas in a homogeneous box potential

    NASA Astrophysics Data System (ADS)

    Mukherjee, Biswaroop; Ku, Mark; Yan, Zhenjie; Patel, Parth; Guardado-Sanchez, Elmer; Yefsah, Tarik; Struck, Julian; Zwierlein, Martin; Zwierlein Group Team

    2015-05-01

    Traditionally, bulk quantum gas experiments take place in inhomogeneous optical and/or magnetic traps. The properties of the homogeneous gas are in many cases masked by line-of-sight integration over the inhomogeneous sample. We report on the trapping of strongly interacting fermionic atoms (6Li) in a quasi-homogenous all-optical potential. We characterize the potential flatness through in-trap imaging, and discuss progress towards directly observing the momentum distribution of the fermions in a box, with the prospect to test predictions from Fermi liquid theory for interacting gases. In contrast to inhomogeneous traps, box potentials prepare a system in one particular point of the phase diagram, giving access to the properties of bulk matter with a high signal-to-noise ratio. This sets a new direction for the exploration of strongly interacting Fermi gases at finite temperature and in the presence of spin imbalance.

  10. Hall effect and Fermi surface reconstruction via electron pockets in the high-Tc cuprates

    NASA Astrophysics Data System (ADS)

    Storey, J. G.

    2016-01-01

    The mechanism by which the Fermi surface of high-T c cuprates undergoes a dramatic change from a large hole-like barrel to small arcs or pockets on entering the pseudogap phase remains a question of fundamental importance. Here we calculate the normal-state Hall coefficient from the resonating-valence-bond spin-liquid model developed by Yang, Rice and Zhang. In this model, reconstruction of the Fermi surface occurs via an intermediate regime where the Fermi surface consists of both hole- and electron-like pockets. We find that the doping (x) dependence of the Hall number transitions from 1+x to (x) over this narrow doping range. At low temperatures, a switch from a downturn to an upturn in the Hall coefficient signals the departure of the electron-like pockets from the Fermi surface.

  11. Acoustic behavior of ordered droplets in a liquid: A phase space approach

    SciTech Connect

    Rivera, A.L.; Lozada-Cassou, M.; Palomino, M.R.; Icaza, M. de; Castano, V.M.

    2005-03-01

    The transmission of an acoustical signal through a spatial arrangement consisting of a bidimensional crystal of droplets (liquid spheres) immersed into another liquid is analyzed. As a first approximation, the paraxial case is solved by considering a set of acoustical lenses which allow us to model the effect of each droplet on the signal. An expression for the Wigner distribution function that lets us evaluate the corresponding image, diffraction pattern, and even the output signal of any given paraxial input signal to that crystalline substrate is obtained, with particular emphasis on the case of an incoming plane wave. To solve the nonparaxial situation, a generalization of the concept of focal distance interpreting every sphere as a superposition of concentric rings of different radius, which permits us to find a general expression for the Wigner distribution function is proposed.

  12. Corrosion behavior of Al-surface-treated steels in liquid Pb?Bi in a pot

    NASA Astrophysics Data System (ADS)

    Kurata, Y.; Futakawa, M.; Saito, S.

    2004-12-01

    Corrosion tests were performed in oxygen-saturated liquid Pb-Bi at 450 °C and 550 °C in a pot for 3000 h for Al-surface-treated steels containing various levels of Cr contents. The Al surface treatments were achieved using a gas diffusion method and a melt dipping method. Al2O3, FeAl2 and AlCr2 produced by the gas diffusion method exhibited corrosion resistance to liquid Pb-Bi, while the surface layer produced by the melt dipping method suffered a severe corrosion attack. Fe4Al13 and Fe2Al5 produced by the melt dipping method disappeared during the corrosion test at 550 °C and only FeAl remained.

  13. A study on corrosion behavior of austenitic stainless steel in liquid metals at high temperature

    NASA Astrophysics Data System (ADS)

    Shin, Sang Hun; Kim, Jong Jin; Jung, Ju Ang; Choi, Kyoung Joon; Bang, In Cheol; Kim, Ji Hyun

    2012-03-01

    The purpose of this study is to investigate the interaction between austenitic stainless steel, AISI 316L, and gallium liquid metal at a high temperature, for the potential application to advanced fast reactor coolants. Test specimens of AISI 316L were exposed to static gallium at 500 °C for up to 700 h in two different cover-gas conditions, including air and vacuum. Similar experimental tests were conducted in gallium alloy liquid metal environments, including Ga-14Sn-6Zn and Ga-8Sn-6Zn, in order to study the effect of addition of alloying elements. The results have shown that the weight change and metal loss of specimens were generally reduced in Ga-14Sn-6Zn and Ga-8Sn-6Zn compared to those in pure gallium at a high temperature.

  14. Acoustic behavior of ordered droplets in a liquid: a phase space approach.

    PubMed

    Rivera, A L; Palomino, M R; de Icaza, M; Lozada-Cassou, M; Castaño, V M

    2005-03-01

    The transmission of an acoustical signal through a spatial arrangement consisting of a bidimensional crystal of droplets (liquid spheres) immersed into another liquid is analyzed. As a first approximation, the paraxial case is solved by considering a set of acoustical lenses which allow us to model the effect of each droplet on the signal. An expression for the Wigner distribution function that lets us evaluate the corresponding image, diffraction pattern, and even the output signal of any given paraxial input signal to that crystalline substrate is obtained, with particular emphasis on the case of an incoming plane wave. To solve the nonparaxial situation, a generalization of the concept of focal distance interpreting every sphere as a superposition of concentric rings of different radius, which permits us to find a general expression for the Wigner distribution function is proposed. PMID:15903601

  15. Influence of Viscoelasticity Behavior on Liquid Film Surface Appearance in Multilayered Polymer Solution

    NASA Astrophysics Data System (ADS)

    Nakamura, Naoki; Yamazaki, Hidekazu; Yokoyama, Atsushi

    In this study, through using three-layer channels and polymer solution, it is aimed to evaluate the influence that the flow condition (flow rate, shape of channel and solution property) in the channel exerts on the liquid film surface appearance immediately after the discharge, and to clarify the rule factor in which it influences the liquid film surface appearance. Experiments were conducted by taking pictures of the bead surface appearance immediately after the discharge with a high-speed camera by using three-layer channels where the change in the merging point shape was possible. As a result of the examination, the following results were obtained. (1) As a result of the observation of surface, it is understood a peculiar surface ruggedness (thickness irregularity) is generated when the viscoelastic fluid is used in the direction of the liquid film discharge different from Melt fracture and Sharkskin. It is thought that this irregular thickness is a peculiar phenomenon to the viscoelastic fluid, because when Newtonian fluid is injected, this irregular thickness is not generated, and it is suppressed because of increased residence time in channel. (2) The factor separation between layers is done at an irregular thickness to specify the rule factor, therefore it has been understood that the correlation is strong in the first normal stress difference generated in the sub-fluid when merging for the incidence of this irregular thickness. Concretely, it is understood that the thickness irregular incidence increases as the first normal stress difference generated in the sub-fluid when merging grows. Moreover, the influence of the main-fluid on the incidence of an irregular thickness in this system is understood to be negligible.

  16. Physico-Chemical Properties and Phase Behavior of the Ionic Liquid-β-Cyclodextrin Complexes

    PubMed Central

    Rogalski, Marek; Modaressi, Ali; Magri, Pierre; Mutelet, Fabrice; Grydziuszko, Aleksandra; Wlazło, Michał; Domańska, Urszula

    2013-01-01

    The solubility of β-cyclodextrin (β-CD) in ionic liquids (ILs) and the activity coefficients at infinite dilution ( γ13∞) of more than 20 solutes (alkanes, aromatic hydrocarbons, alcohols) were measured in four chosen ionic liquids, their mixtures with β-CD, and in the β-CD at high temperatures from 338 to 398 K using the inverse gas chromatography. The intermolecular interactions, inclusion complexes and the possible increasing of the solubility of β-CD in water using the IL are presented. The solubility of β-CD in ten chosen hydrophobic ILs at the temperature T = 423 K was detected. The solid-liquid phase diagrams (SLE) of {IL (1) + β-CD (2)} binary systems at the high mole fraction of the IL were measured for three systems (1-ethyl-3-methylimidazolium chloride, [EMIM][Cl], 1-ethyl-3-methylimidazolium bromide, [EMIM][Br]; and for 1-butyl-3-methylimidazolium chloride, [BMIM][Cl]). The eutectic points were determined at the high IL concentration for all binary systems. The intermolecular interaction and the possibility of inclusion complexes of the IL and/or solvents with β-CD were discussed. The infrared spectroscopy, IR was used for the description of the intermolecular interactions in the (β-CD + IL) systems. It was shown via the activity coefficients at infinite dilution results that the inclusion complexes are dependent on the temperature. The addition of β-CD to the IL does not improve the selectivity of the separation of the aliphatics from aromatics. PMID:23945559

  17. Chaotic orientational behavior of a nematic liquid crystal subjected to a steady shear flow.

    PubMed

    Rienäcker, Götz; Kröger, Martin; Hess, Siegfried

    2002-10-01

    Based on a relaxation equation for the second rank alignment tensor characterizing the molecular orientation in liquid crystals, we report on a number of symmetry-breaking transient states and simple periodic and irregular, chaotic out-of-plane orbits under steady flow. Both an intermittency route and a period-doubling route to chaos are found for this five-dimensional dynamic system in a certain range of parameters (shear rate, tumbling parameter at isotropic-nematic coexistence, and reduced temperature). A link to the corresponding rheochaotic states, present in complex fluids, is made. PMID:12443167

  18. Photomobile polymer materials: photoresponsive behavior of cross-linked liquid-crystalline polymers with mesomorphic diarylethenes.

    PubMed

    Mamiya, Jun-ichi; Kuriyama, Akito; Yokota, Naoki; Yamada, Munenori; Ikeda, Tomiki

    2015-02-16

    Cross-linked liquid-crystalline (LC) polymers with a mesomorphic diarylethene were prepared to demonstrate a versatile strategy for cross-linked photochromic LC polymers as photomobile materials. Upon exposure to UV light to cause photocyclization of the diarylethene chromophore, the cross-linked polymer films bend toward an actinic light source. By irradiation with visible light to cause a closed-ring to open-ring isomerization, the bent films revert to the initial flat state. Without visible-light irradiation, the bent films remain bent even at 120 °C, indicating high thermal stability of the cross-linked diarylethene LC polymers. PMID:25581255

  19. Phase equilibria and self-organizing behavior of side-chain liquid crystalline polymer mixtures

    NASA Astrophysics Data System (ADS)

    Chiu, Hao-Wen

    1998-12-01

    Phenomenological models for elucidating phase diagrams of binary smectic-A mixtures, polymer/smectic-A mixtures, induced smectic in nematic mixtures, and nematic/smectic mixtures have been proposed on the basis of the combination of the Flory-Huggins (FH) free energy of isotropic mixing and Maier-Saupe-McMillan (MSM) free energy for nematic/smectic ordering. The nematic and smectic order parameters have been coupled through the normalized partition and the orientation distribution functions. Flory-Huggins interaction parameter (chi) for isotropic mixing and the coupling term involving the nematic interaction parameter (nu) and the McMillan smectic interaction parameter (alpha) for phase transitions of liquid crystals have been incorporated in the calculation. The predictive capability of the combined FH/MSM theory has been demonstrated by testing with reported phase diagrams. Dynamics of phase separation and morphology development in mixtures of a nematic liquid crystal and a polymer due to thermal quenching have been investigated theoretically in comparison with experimental results. In the proposed model, the combined free energy densities of Flory-Huggins theory for isotropic mixing and Maier-Saupe (MS) theory for nematic ordering have been incorporated into the time-dependent Ginzburg-Landau equation (TDGL, type C). The temporal evolution of the structure factor and the emergence of phase separated liquid crystal (LC) domains have been simulated on the basis of an explicit central difference method based on a square lattice with a periodic boundary condition. Of particular interest is the observed plateau (or inflection) region in the growth dynamic curve, which may be attributed to the breakdown of the interconnected domains caused by the nematic ordering. The emergence of LC domains during polymerization induced phase separation in a polymer dispersed liquid crystal (PDLC) has been solved numerically by incorporating the reaction kinetics into the TDGL

  20. Fermi surface reconstruction in hole-doped t-J models without long-range antiferromagnetic order

    NASA Astrophysics Data System (ADS)

    Punk, Matthias; Sachdev, Subir

    2012-05-01

    We calculate the Fermi surface of electrons in hole-doped, extended t-J models on a square lattice in a regime where no long-range antiferromagnetic order is present, and no symmetries are broken. Using the “spinon-dopon” formalism of Ribeiro and Wen, we show that short-range antiferromagnetic correlations lead to a reconstruction of the Fermi surface into hole pockets which are not necessarily centered at the antiferromagnetic Brillouin zone boundary. The Brillouin zone area enclosed by the Fermi surface is proportional to the density of dopants away from half-filling, in contrast to the conventional Luttinger theorem, which counts the total electron density. This state realizes a “fractionalized Fermi liquid” (FL*), which has been proposed as a possible ground state of the underdoped cuprates; we note connections to recent experiments. We also discuss the quantum phase transition from the FL* state to the Fermi liquid state with long-range antiferromagnetic order.

  1. Structural and Critical Behaviors of Ag Rough Films Deposited on Liquid Substrates

    NASA Astrophysics Data System (ADS)

    Ye, Gao-xiang; Feng, Chun-mu; Zhang, Qi-rui; Ge, Hong-liang; Zhang, Xuan-jia

    1996-10-01

    A new Ag rough film system, deposited on silicone oil surfaces by rf-magnetron sputtering method, has been fabricated. The chrysanthemum-like surface morphology at micron length scale is observed. It is proposed that the anomalous critical behavior mainly results from the relative shift between the Ag atom clusters and the substrate. The discussion of the deposition mechanism is also presented.

  2. Macroscopic behavior of ferrocholesteric liquid crystals and ferrocholesteric gels and elastomers.

    PubMed

    Brand, Helmut R; Fink, Alexander; Pleiner, Harald

    2015-06-01

    We study the influence of macroscopic chirality on the macroscopic properties of superparamagnetic liquid crystals and gels. Specifically we derive macroscopic dynamic equations for ferrocholesteric low molecular weight (LMW) liquid crystals and for ferrocholesteric gels and elastomers in the local description using the director field as macroscopic variable. The magnetization is treated as a macroscopic dynamic degree of freedom and its coupling to all other macroscopic variables is examined in detail. We incorporate into our dynamic analysis terms that are linear in a magnetic field giving rise to a number of cross-coupling terms not possible otherwise. A number of properties that are unique to the class of systems studied arise. As an example for a static property we find a term in the generalized energy which is linear in the electric field and quadratic in the magnetic field. We find that applying a magnetic field to a ferrocholesteric can lead to reversible electric currents, heat currents and concentration currents, which change their sign with a sign change of macroscopic chirality. As an example of a rather intriguing dissipative dynamic contribution we point out that for ferrocholesterics and for ferrocholesteric gels and elastomers in a magnetic field extensional flow leads to electric and heat currents. PMID:26123769

  3. Li-Doped Ionic Liquid Electrolytes: From Bulk Phase to Interfacial Behavior

    NASA Technical Reports Server (NTRS)

    Haskins, Justin B.; Lawson, John W.

    2016-01-01

    Ionic liquids have been proposed as candidate electrolytes for high-energy density, rechargeable batteries. We present an extensive computational analysis supported by experimental comparisons of the bulk and interfacial properties of a representative set of these electrolytes as a function of Li-salt doping. We begin by investigating the bulk electrolyte using quantum chemistry and ab initio molecular dynamics to elucidate the solvation structure of Li(+). MD simulations using the polarizable force field of Borodin and coworkers were then performed, from which we obtain an array of thermodynamic and transport properties. Excellent agreement is found with experiments for diffusion, ionic conductivity, and viscosity. Combining MD simulations with electronic structure computations, we computed the electrochemical window of the electrolytes across a range of Li(+)-doping levels and comment on the role of the liquid environment. Finally, we performed a suite of simulations of these Li-doped electrolytes at ideal electrified interfaces to evaluate the differential capacitance and the equilibrium Li(+) distribution in the double layer. The magnitude of differential capacitance is in good agreement with our experiments and exhibits the characteristic camel-shaped profile. In addition, the simulations reveal Li(+) to be highly localized to the second molecular layer of the double layer, which is supported by additional computations that find this layer to be a free energy minimum with respect to Li(+) translation.

  4. Adsorption Behaviors of Mixed Monolayers of n-Alkanes at the Liquid-Solid Interface.

    PubMed

    Hibino, Masahiro

    2016-05-17

    To understand the self-assembly of monolayers at the liquid-solid interface, a thermodynamic model, which describes the contributions of the molecular interactions, is essential. We present an adapted Zimm-Bragg model of the cooperativity transitions for determining the Gibbs free energy for self-assembly at the liquid-solid interface. Scanning tunneling microscopy was used to observe the monolayers formed on graphite from phenyloctane solutions of binary mixtures of n-hexacosane (C26H54) and n-tetratriacontane (C34H70). This revealed that the sharp transition in the monolayers from the full surface coverage of the long-chain alkane, which is adsorbed preferentially, to the full coverage of the short-chain alkane is a function of the mixture composition. The model allows for the estimation of the free-energy changes associated with the difference in the alkyl chain length and the interface between the two different alkane regions in the monolayers. It is also suitable for understanding more complex systems that exhibit intermolecular interactions. PMID:27124544

  5. Electrooptical behavior of aqueous (hydroxypropyl)cellulose liquid crystals containing imidazolium salts.

    PubMed

    Ito, Mitsuhiro; Teramoto, Yoshikuni; Nishio, Yoshiyuki

    2012-02-13

    A dynamic control of the cholesteric coloration and optical clarity of aqueous (hydroxypropyl)cellulose (HPC) lyotropics is attainable under a weak electric field by employing a fluctuating ionic additive as P and T(c) shifter (P, cholesteric pitch; T(c), cloud point). The present Article demonstrates some examples of time-evolving gradation in reflection color and transparency for HPC liquid crystals containing various N-alkyl-substituted methylimidazolium salts ([CnMim][X]); this was perceivable when each anisotropic solution was sealed in a layer form between parallel slide glasses spaced by a pair of carbon electrodes and then electrified with a direct circuit. The electrooptical phenomenon was interpreted as being primarily due to generation of a disproportional dislocation of cation (CnMim(+))/anion (X(-)) constituents. Even after the electric supply was ceased, an appreciable potential difference remained in the color-gradated samples. It is suggested that the salt-containing liquid-crystalline system behaves like a quasi-capacitor as a viscous electrolytic medium of high resistance. PMID:22283424

  6. Bioterrorism and the Fermi Paradox

    NASA Astrophysics Data System (ADS)

    Cooper, Joshua

    2013-04-01

    We proffer a contemporary solution to the so-called Fermi Paradox, which is concerned with conflict between Copernicanism and the apparent paucity of evidence for intelligent alien civilizations. In particular, we argue that every community of organisms that reaches its space-faring age will (1) almost immediately use its rocket-building computers to reverse-engineer its genetic chemistry and (2) self-destruct when some individual uses said technology to design an omnicidal pathogen. We discuss some of the possible approaches to prevention with regard to Homo sapiens' vulnerability to bioterrorism, particularly on a short-term basis.

  7. Behavior of Spinning Space Vehicles with Onboard Liquids, 2nd Edition, Technical Report B8030

    NASA Technical Reports Server (NTRS)

    Hubert, Carl

    2008-01-01

    Although the fundamental principles of spin stabilization are well established, uncertainty regarding the potential for rapid nutation growth caused by onboard liquids is a continuing concern. NASA and other organizations regularly encounter the issue of rapid nutation growth due to energy dissipation by liquids on spinning vehicles. Of concern is the stability of spinning upper stages and of spacecraft that spin for part or all of their missions. Several missions have required last-minute hardware or operational changes to deal with rapid nutation divergences that were identified late in the program. In some instances, major schedule slips were barely averted. In at least two cases, it was determined that a spinning upper stage was not a viable option. Historically, the "slosh" issue has been addressed by each space vehicle project individually, if it has been addressed at all. Due to budgetary and programmatic constraints, individual projects are unable to address the problem globally. Hence, there has been little effort to collect available test and flight data and use that data to make a coherent, unified picture of the "slosh" effect and how to deal with it. To some extent, each project has had to "reinvent the wheel", which can be both costly and risky. This study is a step toward correcting the situation. Specifically, the goal was to identify and collect available flight and test data for spinning vehicles with onboard liquid propellants. A total of 149 flight data points and 1,692 test points were collected as part of this study. This data was analyzed, correlated, and is presented here in a normalized form. In most cases, the normalization involves a dimensionless nutation time constant that can be used to predict performance of other vehicles with the same type of tank. For some configurations, it was also possible to identify conditions that can lead to resonance between nutational motion and liquid modes. Gaps in the knowledge base are identified and

  8. Generalized second-order Thomas-Fermi method for superfluid Fermi systems

    NASA Astrophysics Data System (ADS)

    Pei, J. C.; Fei, Na; Zhang, Y. N.; Schuck, P.

    2015-12-01

    Using the ℏ expansion of the Green's function of the Hartree-Fock-Bogoliubov equation, we extend the second-order Thomas-Fermi approximation to generalized superfluid Fermi systems by including the density-dependent effective mass and the spin-orbit potential. We first implement and examine the full correction terms over different energy intervals of the quasiparticle spectra in calculations of finite nuclei. Final applications of this generalized Thomas-Fermi method are intended for various inhomogeneous superfluid Fermi systems.

  9. Numerical Investigation and Experimental Reproduction of Fermi Acceleration in Laboratory Scale

    NASA Astrophysics Data System (ADS)

    Zhou, M.; Zhai, C.

    2015-12-01

    Fermi acceleration is widely accepted as the mechanism to explain power law of cosmic ray spectrum. Now this mechanism has been developed to first order Fermi acceleration and second order Fermi acceleration. In first order Fermi acceleration, also known as diffusive shock acceleration, particles are confined around the shock through scattering and accelerated by repeatedly crossing shock front. In second order Fermi acceleration, particles gain energy through statistical collisions with interstellar clouds. In this proposed work, we plan to carefully study these two kinds of acceleration numerically and experimentally. We first consider a single relativistic particle and investigate how it gains energy in Fermi-Ulam model and shock wave acceleration model respectively. We investigate collective behavior of particles with different kinds of wall-oscillation functions and try to find an optimal one in terms of efficiency of acceleration. Then, we plan to go further and consider a group of particles statistically, during which we borrow the correct generalization of Maxwell's velocity distribution in special relativity and compare the results with those in cases where we simply use Maxwell-Boltzmann distribution. To this end, we try to provide a scheme to build an accelerator applying both laser technology and mirror effect in Laboratory to reproduce Fermi acceleration, which might be a promising source to obtain high energy particles and further study the mechanism of cosmic rays acceleration.

  10. Validation of a Chiral Liquid Chromatographic Method for the Degradation Behavior of Flumequine Enantiomers in Mariculture Pond Water.

    PubMed

    Wang, Yan-Fei; Gao, Xiao-Feng; Jin, Huo-Xi; Wang, Yang-Guang; Wu, Wei-Jian; Ouyang, Xiao-Kun

    2016-09-01

    In this work, flumequine (FLU) enantiomers were separated using a Chiralpak OD-H column, with n-hexane-ethanol (20:80, v/v) as the mobile phase at a flow rate of 0.6 mL/min. Solid phase extraction (SPE) was used for cleanup and enrichment. The limit of detection, limit of quantitation, linearity, precision, and intra/interday variation of the chiral high-performance liquid chromatography (HPLC) method were determined. The developed method was then applied to investigate the degradation behavior of FLU enantiomers in mariculture pond water samples. The results showed that the degradation of FLU enantiomers under natural, sterile, or dark conditions was not enantioselective. Chirality 28:649-655, 2016. © 2016 Wiley Periodicals, Inc. PMID:27483447

  11. Control of the anchoring behavior of polymer-dispersed liquid crystals: effect of branching in the side chains of polyacrylates.

    PubMed

    Zhou, Jian; Collard, David M; Park, Jung O; Srinivasarao, Mohan

    2002-08-28

    A temperature-driven anchoring transition in a polymer/nematic fluid composite that is far from the bulk nematic-isotropic transition temperature is reported. A series of poly(methylheptyl acrylates) were studied to probe the subtle effects of the side chain structure of the polymer on control of the anchoring. A polymer-dispersed liquid crystal film made from TL205 and 1-methylheptyl acrylate shows only planar anchoring over the temperature range studied, while the films made from TL205 and each of the other methylheptyl acrylates or n-heptyl acrylate show the homeotropic-to-planar anchoring transition at temperatures between 70 and 78 degrees C. An interfacial model is proposed in which the different conformation of the side chains is suggested as the cause for the dramatic difference in the observed anchoring behavior. PMID:12188649

  12. Metallic 2D Surface State of Silicon by Ionic Liquid gating and observation of Reentrant Insulating behavior

    NASA Astrophysics Data System (ADS)

    Nelson, J. J.; Goldman, A. M.

    2015-03-01

    Metal insulator transitions are usually observed in high mobility and low carrier density 2D electron systems. There are several open questions regarding the metallic state including its existence in the limit of zero temperature. The current experimental focus is on the production of higher mobility samples to push the critical carrier density to even lower values, which will increase the effects of the Coulomb interaction. Here we report an unexpected result, the observation of the onset of a metallic state at high carrier densities in silicon gated with the ionic liquid DEME-TFSI. In addition we have observed a return to the insulating state as the carrier density was further increased. This reentrant insulting behavior is an effect that was recently predicted. Supported in part by NSF/DMR-1263316. Part of this work was carried out at the Minnesota Nanocenter.

  13. Leaching behavior of copper from waste printed circuit boards with Brønsted acidic ionic liquid

    SciTech Connect

    Huang, Jinxiu; Chen, Mengjun Chen, Haiyan; Chen, Shu; Sun, Quan

    2014-02-15

    Highlights: • A Brønsted acidic ILs was used to leach Cu from WPCBs for the first time. • The particle size of WPCBs has significant influence on Cu leaching rate. • Cu leaching rate was higher than 99% under the optimum leaching conditions. • The leaching process can be modeled with shrinking core model, and the E{sub a} was 25.36 kJ/mol. - Abstract: In this work, a Brønsted acidic ionic liquid, 1-butyl-3-methyl-imidazolium hydrogen sulfate ([bmim]HSO{sub 4}), was used to leach copper from waste printed circuit boards (WPCBs, mounted with electronic components) for the first time, and the leaching behavior of copper was discussed in detail. The results showed that after the pre-treatment, the metal distributions were different with the particle size: Cu, Zn and Al increased with the increasing particle size; while Ni, Sn and Pb were in the contrary. And the particle size has significant influence on copper leaching rate. Copper leaching rate was higher than 99%, almost 100%, when 1 g WPCBs powder was leached under the optimum conditions: particle size of 0.1–0.25 mm, 25 mL 80% (v/v) ionic liquid, 10 mL 30% hydrogen peroxide, solid/liquid ratio of 1/25, 70 °C and 2 h. Copper leaching by [bmim]HSO{sub 4} can be modeled with the shrinking core model, controlled by diffusion through a solid product layer, and the kinetic apparent activation energy has been calculated to be 25.36 kJ/mol.

  14. Wetting behavior of nonpolar nanotubes in simple dipolar liquids for varying nanotube diameter and solute-solvent interactions

    NASA Astrophysics Data System (ADS)

    Rana, Malay Kumar; Chandra, Amalendu

    2015-01-01

    Atomistic simulations of model nonpolar nanotubes in a Stockmayer liquid are carried out for varying nanotube diameter and nanotube-solvent interactions to investigate solvophobic interactions in generic dipolar solvents. We have considered model armchair type single-walled nonpolar nanotubes with increasing radii from (5,5) to (12,12). The interactions between solute and solvent molecules are modeled by the well-known Lennard-Jones and repulsive Weeks-Chandler-Andersen potentials. We have investigated the density profiles and microscopic arrangement of Stockmayer molecules, orientational profiles of their dipole vectors, time dependence of their occupation, and also the translational and rotational motion of solvent molecules in confined environments of the cylindrical nanopores and also in their external peripheral regions. The present results of structural and dynamical properties of Stockmayer molecules inside and near atomistically rough nonpolar surfaces including their wetting and dewetting behavior for varying interactions provide a more generic picture of solvophobic effects experienced by simple dipolar liquids without any specific interactions such as hydrogen bonds.

  15. Anodic behavior of Al current collector in 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] amide ionic liquid electrolytes

    NASA Astrophysics Data System (ADS)

    Peng, Chengxin; Yang, Li; Zhang, Zhengxi; Tachibana, Kazuhiro; Yang, Yong

    The anodic behaviors of aluminum current collector for lithium ion batteries were investigated in a series of 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] amide room temperature ionic liquids (RTILs) and EC + DMC electrolytes. It was found that the aluminum corrosion, which occurred in EC + DMC electrolytes containing LiTFSI, was not observed in the RTIL electrolytes. Further research showed that a passive film with amide compounds as main components formed firmly on aluminum surface during the anodic polarization in the RTIL electrolytes, which inhabited the aluminum corrosion. In addition, the additives generally used in the batteries, such as ethylene carbonate, ethylene sulfite and vinyl carbonate, as well as temperature did not obviously affect the aluminum passive film, the oxidation of the RTILs increased at the elevated temperature, which only resulted in the corrosion potential of aluminum in the RTIL electrolytes shifted to more negative potential, a passive film still firmly formed on the aluminum surface to surpassed the further oxidation of the aluminum current collector. Those results lead to a potential for the practical use of LiTFSI salt in the room temperature ionic liquid electrolytes for lithium ion batteries.

  16. Wetting behavior of nonpolar nanotubes in simple dipolar liquids for varying nanotube diameter and solute-solvent interactions

    SciTech Connect

    Rana, Malay Kumar; Chandra, Amalendu

    2015-01-21

    Atomistic simulations of model nonpolar nanotubes in a Stockmayer liquid are carried out for varying nanotube diameter and nanotube-solvent interactions to investigate solvophobic interactions in generic dipolar solvents. We have considered model armchair type single-walled nonpolar nanotubes with increasing radii from (5,5) to (12,12). The interactions between solute and solvent molecules are modeled by the well-known Lennard-Jones and repulsive Weeks-Chandler-Andersen potentials. We have investigated the density profiles and microscopic arrangement of Stockmayer molecules, orientational profiles of their dipole vectors, time dependence of their occupation, and also the translational and rotational motion of solvent molecules in confined environments of the cylindrical nanopores and also in their external peripheral regions. The present results of structural and dynamical properties of Stockmayer molecules inside and near atomistically rough nonpolar surfaces including their wetting and dewetting behavior for varying interactions provide a more generic picture of solvophobic effects experienced by simple dipolar liquids without any specific interactions such as hydrogen bonds.

  17. Accommodative Behavior of Non-porous Molecular crystal at Solid-Gas and Solid-Liquid Interface

    PubMed Central

    Mande, Hemant M.; Ghalsasi, Prasanna S.

    2015-01-01

    Molecular crystals demonstrate drastically different behavior in solid and liquid state, mainly due to their difference in structural frameworks. Therefore, designing of unique structured molecular compound which can work at both these interfaces has been a challenge. Here, we present remarkable ‘molecular’ property by non-porous molecular solid crystal, dinuclear copper complex (C6H5CH(X)NH2)2CuCl2, to reversibly ‘adsorb’ HCl gas at solid-gas interface as well as ‘accommodate’ azide anion at solid-liquid interface with crystal to crystal transformation. The latter process is driven by molecular recognition, self-assembly, and anchimeric assistance. The observed transformations are feasible due to breathing of inner and outer coordination sphere around metal center resulting in change in metal polyhedra for ‘accommodating’ guest molecule. These transformations cause changes in optical, magnetic, and/or ferroelectric property offering diversity in ‘sensing’ application. With the proposed underlying principles in these exceptional reversible and cyclic transformations, we prepared a series of compounds, can facilitate designing of novel multifunctional molecular materials. PMID:26411980

  18. Decay behavior of screened electrostatic surface forces in ionic liquids: the vital role of non-local electrostatics.

    PubMed

    Kjellander, Roland

    2016-07-28

    Screened electrostatic surface forces, also called double layer forces, between surfaces in ionic liquids can, depending on the circumstances, decay in an exponentially damped, oscillatory manner or in a plain exponential way (the latter as in dilute electrolyte solutions where ion-ion correlations are very weak). The occurrence of both of these behaviors in dense ionic liquids, where ion-ion correlations are very strong, is analyzed in the current work using exact statistical mechanics formulated in a manner that is physically transparent. A vital ingredient in understanding the decay behaviors is the fact that electrostatics in dense electrolytes have a non-local nature caused by the strong correlations. It is shown that the effects of non-locality can be elucidated by a remarkably simple, general expression for the decay parameter κ that replaces the classical expression for the inverse Debye length κDH of the Debye-Hückel (DH) and non-linear Poisson-Boltzmann approximations. This exact expression is valid for both the plain exponential and the oscillatory cases. It shows how strong correlations can give rise to plain exponential decay with a long decay length. Such a decay can arise from anion-cation associations of various kinds, for instance transient ion pairing or association caused by many-body correlations; ion pairing is a possibility but not a necessity for this to occur. Theoretical analysis is done for systems consisting of ions with an arbitrary shape and internal charge density and immersed planar walls with arbitrary internal charge distribution and any short-range ion-surface interaction. The screened electrostatic surface force between two walls is at large separations proportional to the product of effective surface charge densities of each wall. For the oscillatory case, each wall contributes with a phase shift to the oscillations of the interaction. PMID:27356099

  19. Phase behavior of AOT microemulsions in compressible liquids. [AOT = bis(2-ethylhexyl) sodium sulfosuccinate

    SciTech Connect

    McFann, G.J.; Johnston, K.P. )

    1991-06-13

    The phase behavior of bis(2-ethylhexyl) sodium sulfosuccinate (AOT)-alkane-brine systems is described over a wide range of pressure, temperature, and salinity for alkanes from ethane to dodecane. The partitioning of AOT between the oil, middle, and brine phases is reported for propane in order to determine the natural curvature. This is important for understanding separation processes with water-in-oil microemulsions. For the lighter, more compressible alkanes, the pressure effect on the hydrophilicity of the surfactant is much larger and in the opposite direction as for the heavier, less compressible ones. In propane at constant temperature and salinity, water-in-oil (w/o) microemulsions have been converted to middle phase microemulsions and then to oil-in-water (o/w) microemulsions by decreasing the pressure. These phase inversions are described in terms of the immiscibilities in the binary systems, and the molecular interactions at the surfactant interface. Although temperature and salinity are used commonly to manipulate interactions primarily on the water side of the interface, these results show it is possible to control interactions on the oil side by adjusting the pressure. The well-established trends in the phase behavior and size of microemulsion drops for dodecane through hexane are not observed for the lighter alkanes. For butane through ethane, a new unusual behavior is identified and attributed to a significant decrease in the strength of the attractive interactions between the surfactant tails and the alkane.

  20. Irreversible thermochromic behavior in gold and silver nanorod/polymeric ionic liquid nanocomposite films.

    PubMed

    Tollan, Christopher M; Marcilla, Rebeca; Pomposo, Jose A; Rodriguez, Javier; Aizpurua, Javier; Molina, Jon; Mecerreyes, David

    2009-02-01

    The novel application of gold and silver nanorods as irreversible thermochromic dyes in polymeric ionic liquid (PIL) nanocomposites is proposed here. These materials have been synthesized by anion exchange of an imidazolium-based PIL in a solution that also contained gold nanorods. This resulted in the entrapment of the nanoobjects within a solid polymer precipitate. In this article, the effect of the temperature was studied in relation to the change of shape and, consequently, color of the gold or silver nanorods within the films. For the nanocomposites studied here, a maximum of two visual thermochromic transitions was observed for gold nanorods and up to three transitions were observed for silver nanorods. PMID:20353222

  1. Superior switching behavior of liquid crystals on surface-modified compound oxide films

    NASA Astrophysics Data System (ADS)

    Jeong, Hae-Chang; Oh, Byeong-Yun; Park, Hong-Gyu; Lee, Ju Hwan; Jung, Yoon Ho; Jang, Sang Bok; Seo, Dae-Shik

    2015-12-01

    We demonstrate high-performance liquid crystal (LC) devices using alignment layers formed of solution-processed HfYO films that were subjected to ion-beam (IB) irradiation. IB irradiation entails the increment of the surface roughness and chemical modification of the surface. Our X-ray photoelectron spectroscopy (XPS) analysis revealed that IB irradiation also breaks oxygen bonds, and thereby creates oxygen vacancies with lattice displacement of the metal atoms. This variation stabilizes the homogeneous LC alignment. The LC cells formed using the IB-irradiated HfYO films with an intensity of 2200 eV yielded a rapid response time of 6.579 ms. Therefore, our fast switching application based on IB-irradiated HfYO films has great potential for application of display devices.

  2. A simplified computer program for the prediction of the linear stability behavior of liquid propellant combustors

    NASA Technical Reports Server (NTRS)

    Mitchell, C. E.; Eckert, K.

    1979-01-01

    A program for predicting the linear stability of liquid propellant rocket engines is presented. The underlying model assumptions and analytical steps necessary for understanding the program and its input and output are also given. The rocket engine is modeled as a right circular cylinder with an injector with a concentrated combustion zone, a nozzle, finite mean flow, and an acoustic admittance, or the sensitive time lag theory. The resulting partial differential equations are combined into two governing integral equations by the use of the Green's function method. These equations are solved using a successive approximation technique for the small amplitude (linear) case. The computational method used as well as the various user options available are discussed. Finally, a flow diagram, sample input and output for a typical application and a complete program listing for program MODULE are presented.

  3. Homeotropic orientation behavior of nematic liquid crystals induced by copper ions.

    PubMed

    Li, Guang; Gao, Bin; Yang, Meng; Chen, Long-Cong; Xiong, Xing-Liang

    2015-06-01

    A homeotropic ordering film of nematic liquid crystal (LC) induced by copper ions (Cu(2+)) had been developed. The Cu(ClO4)2 was directly spin-coated on the glass substrate without any other chemical modification. A homeotropic orientation of LC thin-film was generated by the interfacial chemical interaction between nitrile-containing LC and copper ions on the surface. Results showed that an appropriate density of Cu(2+) could shorten the response time of orientation, but a shelf-time was prolonged. The LC film fabrication not only offered a simple process, but also presented a great repeatability to detect organophosphonates (DMMP). This study provided guidance for the design of LC films responding to organic molecules as a biosensor. PMID:25935262

  4. Behaviors of random laser in dye-doped nematic liquid crystals

    NASA Astrophysics Data System (ADS)

    Yao, Fengfeng; Bian, Huanting; Pei, Yanbo; Hou, Chunfeng; Sun, Xiudong

    2016-01-01

    Random lasing in the nematic liquid crystals (NLCs) with a high doping concentration of the laser dye was observed and characterized. With increasing the pump energy after the occurrence of the random laser (RL), the RL intensity first increases gradually to a maximum, then drops sharply to zero, accompanied by the gradual enhancement of scattering manifested by the growth of far-field diffraction rings of the transmitted pump beam in number. The threshold energy per unit pump area, slope efficiency, and maximal output intensity of the NLC RL depend heavily and nonmonotonically on the pump angle. A model involving the pump pulse induced molecular reorientation in NLCs leading to the pump angle dependent enhancement of scattering is proposed to explain the pump angle dependent properties of RLs.

  5. Migration behavior of supercritical and liquid CO2 in a stratified system: Experiments and numerical simulations

    NASA Astrophysics Data System (ADS)

    Oh, Junho; Kim, Kue-Young; Han, Weon Shik; Park, Eungyu; Kim, Jeong-Chan

    2015-10-01

    Multiple scenarios of upward CO2 migration driven by both injection-induced pressure and buoyancy force were investigated in a horizontally and vertically stratified core utilizing a core-flooding system with a 2-D X-ray scanner. Two reservoir-type scenarios were considered: (1) the terrestrial reservoir scenario (10 MPa and 50°C), where CO2 exists in a supercritical state and (2) the deep-sea sediment reservoir scenario (28 MPa and 25°C), where CO2 is stored in the liquid phase. The core-flooding experiments showed a 36% increase in migration rate in the vertical core setting compared with the horizontal setting, indicating the significance of the buoyancy force under the terrestrial reservoir scenario. Under both reservoir conditions, the injected CO2 tended to find a preferential flow path (low capillary entry pressure and high-permeability (high-k) path) and bypass the unfavorable pathways, leaving low CO2 saturation in the low-permeability (low-k) layers. No distinctive fingering was observed as the CO2 moved upward, and the CO2 movement was primarily controlled by media heterogeneity. The CO2 saturation in the low-k layers exhibited a more sensitive response to injection rates, implying that the increase in CO2 injection rates could be more effective in terms of storage capacity in the low-k layers in a stratified reservoir. Under the deep-sea sediment condition, the storage potential of liquid CO2 was more than twice as high as that of supercritical CO2 under the terrestrial reservoir scenario. In the end, multiphase transport simulations were conducted to assess the effects of heterogeneity on the spatial variation of pressure buildup, CO2 saturation, and CO2 flux. Finally, we showed that a high gravity number (Ngr) tended to be more influenced by the heterogeneity of the porous media.

  6. Quadratic Fermi node in a 3D strongly correlated semimetal

    SciTech Connect

    Kondo, Takeshi; Nakayama, M.; Chen, R.; Ishikawa, J. J.; Moon, E. -G.; Yamamoto, T.; Ota, Y.; Malaeb, W.; Kanai, H.; Nakashima, Y.; Ishida, Y.; Yoshida, R.; Yamamoto, H.; Matsunami, M.; Kimura, S.; Inami, N.; Ono, K.; Kumigashira, H.; Nakatsuji, S.; Balents, L.; Shin, S.

    2015-12-07

    We report that strong spin–orbit coupling fosters exotic electronic states such as topological insulators and superconductors, but the combination of strong spin–orbit and strong electron–electron interactions is just beginning to be understood. Central to this emerging area are the 5d transition metal iridium oxides. Here, in the pyrochlore iridate Pr2Ir2O7, we identify a non-trivial state with a single-point Fermi node protected by cubic and time-reversal symmetries, using a combination of angle-resolved photoemission spectroscopy and first-principles calculations. Owing to its quadratic dispersion, the unique coincidence of four degenerate states at the Fermi energy, and strong Coulomb interactions, non-Fermi liquid behaviour is predicted, for which we observe some evidence. Lastly, our discovery implies that Pr2Ir2O7 is a parent state that can be manipulated to produce other strongly correlated topological phases, such as topological Mott insulator, Weyl semimetal, and quantum spin and anomalous Hall states.

  7. Numerical methods for the Poisson-Fermi equation in electrolytes

    NASA Astrophysics Data System (ADS)

    Liu, Jinn-Liang

    2013-08-01

    The Poisson-Fermi equation proposed by Bazant, Storey, and Kornyshev [Phys. Rev. Lett. 106 (2011) 046102] for ionic liquids is applied to and numerically studied for electrolytes and biological ion channels in three-dimensional space. This is a fourth-order nonlinear PDE that deals with both steric and correlation effects of all ions and solvent molecules involved in a model system. The Fermi distribution follows from classical lattice models of configurational entropy of finite size ions and solvent molecules and hence prevents the long and outstanding problem of unphysical divergence predicted by the Gouy-Chapman model at large potentials due to the Boltzmann distribution of point charges. The equation reduces to Poisson-Boltzmann if the correlation length vanishes. A simplified matched interface and boundary method exhibiting optimal convergence is first developed for this equation by using a gramicidin A channel model that illustrates challenging issues associated with the geometric singularities of molecular surfaces of channel proteins in realistic 3D simulations. Various numerical methods then follow to tackle a range of numerical problems concerning the fourth-order term, nonlinearity, stability, efficiency, and effectiveness. The most significant feature of the Poisson-Fermi equation, namely, its inclusion of steric and correlation effects, is demonstrated by showing good agreement with Monte Carlo simulation data for a charged wall model and an L type calcium channel model.

  8. Quadratic Fermi node in a 3D strongly correlated semimetal

    PubMed Central

    Kondo, Takeshi; Nakayama, M.; Chen, R.; Ishikawa, J. J.; Moon, E.-G.; Yamamoto, T.; Ota, Y.; Malaeb, W.; Kanai, H.; Nakashima, Y.; Ishida, Y.; Yoshida, R.; Yamamoto, H.; Matsunami, M.; Kimura, S.; Inami, N.; Ono, K.; Kumigashira, H.; Nakatsuji, S.; Balents, L.; Shin, S.

    2015-01-01

    Strong spin–orbit coupling fosters exotic electronic states such as topological insulators and superconductors, but the combination of strong spin–orbit and strong electron–electron interactions is just beginning to be understood. Central to this emerging area are the 5d transition metal iridium oxides. Here, in the pyrochlore iridate Pr2Ir2O7, we identify a non-trivial state with a single-point Fermi node protected by cubic and time-reversal symmetries, using a combination of angle-resolved photoemission spectroscopy and first-principles calculations. Owing to its quadratic dispersion, the unique coincidence of four degenerate states at the Fermi energy, and strong Coulomb interactions, non-Fermi liquid behaviour is predicted, for which we observe some evidence. Our discovery implies that Pr2Ir2O7 is a parent state that can be manipulated to produce other strongly correlated topological phases, such as topological Mott insulator, Weyl semimetal, and quantum spin and anomalous Hall states. PMID:26640114

  9. Quadratic Fermi node in a 3D strongly correlated semimetal

    NASA Astrophysics Data System (ADS)

    Kondo, Takeshi; Nakayama, M.; Chen, R.; Ishikawa, J. J.; Moon, E.-G.; Yamamoto, T.; Ota, Y.; Malaeb, W.; Kanai, H.; Nakashima, Y.; Ishida, Y.; Yoshida, R.; Yamamoto, H.; Matsunami, M.; Kimura, S.; Inami, N.; Ono, K.; Kumigashira, H.; Nakatsuji, S.; Balents, L.; Shin, S.

    2015-12-01

    Strong spin-orbit coupling fosters exotic electronic states such as topological insulators and superconductors, but the combination of strong spin-orbit and strong electron-electron interactions is just beginning to be understood. Central to this emerging area are the 5d transition metal iridium oxides. Here, in the pyrochlore iridate Pr2Ir2O7, we identify a non-trivial state with a single-point Fermi node protected by cubic and time-reversal symmetries, using a combination of angle-resolved photoemission spectroscopy and first-principles calculations. Owing to its quadratic dispersion, the unique coincidence of four degenerate states at the Fermi energy, and strong Coulomb interactions, non-Fermi liquid behaviour is predicted, for which we observe some evidence. Our discovery implies that Pr2Ir2O7 is a parent state that can be manipulated to produce other strongly correlated topological phases, such as topological Mott insulator, Weyl semimetal, and quantum spin and anomalous Hall states.

  10. Quasiparticle scattering rate in a strongly polarized Fermi mixture

    NASA Astrophysics Data System (ADS)

    Christensen, Rasmus Søgaard; Bruun, Georg M.

    2015-04-01

    We analyze the scattering rate of an impurity atom in a Fermi sea as a function of momentum and temperature in the BCS-BEC crossover. The cross section is calculated using a microscopic multichannel theory for the Feshbach resonance scattering, including finite range and medium effects. We show that pair correlations significantly increase the cross section for strong interactions close to the unitarity regime. They give rise to a molecule pole of the cross section at negative energy on the BEC side of the resonance, which smoothly evolves into a resonance at positive scattering energy with a nonzero imaginary part on the BCS side. The resonance is the analog of superfluid pairing for the corresponding population balanced system. Using Fermi liquid theory, we show that the low temperature scattering rate of the impurity atom is significantly increased due to these pair correlations for low momenta. We demonstrate that finite range and mass imbalance effects are significant for the experimentally relevant 6Li-40K mixture, and we finally discuss how the scattering rate can be measured using radio-frequency spectroscopy and Bose-Fermi mixtures.

  11. Quadratic Fermi node in a 3D strongly correlated semimetal

    DOE PAGESBeta

    Kondo, Takeshi; Nakayama, M.; Chen, R.; Ishikawa, J. J.; Moon, E. -G.; Yamamoto, T.; Ota, Y.; Malaeb, W.; Kanai, H.; Nakashima, Y.; et al

    2015-12-07

    We report that strong spin–orbit coupling fosters exotic electronic states such as topological insulators and superconductors, but the combination of strong spin–orbit and strong electron–electron interactions is just beginning to be understood. Central to this emerging area are the 5d transition metal iridium oxides. Here, in the pyrochlore iridate Pr2Ir2O7, we identify a non-trivial state with a single-point Fermi node protected by cubic and time-reversal symmetries, using a combination of angle-resolved photoemission spectroscopy and first-principles calculations. Owing to its quadratic dispersion, the unique coincidence of four degenerate states at the Fermi energy, and strong Coulomb interactions, non-Fermi liquid behaviour ismore » predicted, for which we observe some evidence. Lastly, our discovery implies that Pr2Ir2O7 is a parent state that can be manipulated to produce other strongly correlated topological phases, such as topological Mott insulator, Weyl semimetal, and quantum spin and anomalous Hall states.« less

  12. [The Effects of Complex of Benzoquinone on Fermi Resonance].

    PubMed

    Li, Shuai-peng; Zhang, Feng-qin; Jiang, Li-tong; Lin, Xiao-long; Jiang, Yong-heng; Zhang Liu-yang; Lin, Bo; Gu, Hao

    2015-07-01

    Fermi resonance phenomenon exists in simple compounds and it also widely exists in vibration spectra of complex. The complex can be formed by adding up simple compounds. As a result, the characteristic parameters of some parts of molecule will make changes, and the molecular spectra have a significant change along with it. Benzoquinone and proline in the solution form charge-transfer complex under certain conditions, but the spectra intensity is weak, our research uses Teflon liquid-core optical fiber technology to gain high quality resonance Raman spectra. We acquire Raman spectra of Benzoquinone and its complex in experiments, and analyze the characteristic parameters of Fermi resonance according to J. F. Bertran quantum theory. The results shows that, because of the formation of complex, Fermi resonance peak of C==0 bond shifts to high wavelength, the spectra intensity decreases, the frequency space increases, the coupling coefficient increases. The explanation is that, in the solution of complex, proline is donor, while benzoquinone is acceptor, the non-bonding electron of N atom which is belong to proline transfers to the pi anti-bonding orbital of benzoquinone, then n-pi* charge transfer complex is produced. That causes the change of molecular energy level, changes the Raman spectra. All these researches provide new idea and clue for spectral line certification and attribution of complex molecules, complexes and polymer. PMID:26717725

  13. Quadratic Fermi node in a 3D strongly correlated semimetal.

    PubMed

    Kondo, Takeshi; Nakayama, M; Chen, R; Ishikawa, J J; Moon, E-G; Yamamoto, T; Ota, Y; Malaeb, W; Kanai, H; Nakashima, Y; Ishida, Y; Yoshida, R; Yamamoto, H; Matsunami, M; Kimura, S; Inami, N; Ono, K; Kumigashira, H; Nakatsuji, S; Balents, L; Shin, S

    2015-01-01

    Strong spin-orbit coupling fosters exotic electronic states such as topological insulators and superconductors, but the combination of strong spin-orbit and strong electron-electron interactions is just beginning to be understood. Central to this emerging area are the 5d transition metal iridium oxides. Here, in the pyrochlore iridate Pr2Ir2O7, we identify a non-trivial state with a single-point Fermi node protected by cubic and time-reversal symmetries, using a combination of angle-resolved photoemission spectroscopy and first-principles calculations. Owing to its quadratic dispersion, the unique coincidence of four degenerate states at the Fermi energy, and strong Coulomb interactions, non-Fermi liquid behaviour is predicted, for which we observe some evidence. Our discovery implies that Pr2Ir2O7 is a parent state that can be manipulated to produce other strongly correlated topological phases, such as topological Mott insulator, Weyl semimetal, and quantum spin and anomalous Hall states. PMID:26640114

  14. Heavy-fermion semiconductor behavior of the SU({ital N}{sub {ital d}}) Anderson lattice model

    SciTech Connect

    Hu, L.; Yang, F.; Sun, J. |; Lin, T. |

    1995-08-15

    The heavy-fermion semiconductor behavior of the SU({ital N}{sub {ital d}}) Anderson lattice model is examined by using the slave-boson technique within the framework of mean-field theory. The results show that the slave-boson mean-field theory of this model can present a heavy Fermi liquid or a heavy-fermion semiconductor ground state for different {ital n} values ({ital n} is the total number of the conduction and the on-site {ital f} electrons per lattice site), thus providing a unified description of the heavy Fermi liquid and the heavy-fermion semiconductor. The basic features of this theory are in qualitative agreement with the experimentally observed heavy-fermion semiconductor behavior of some rare-earth compounds.

  15. Magnetar Observations in the Swift-Fermi/GBM Era

    NASA Technical Reports Server (NTRS)

    Kouveliotou, Chryssa

    2010-01-01

    NASA's Fermi Observatory was launched June 11, 2008; the Fermi Gamma Ray Burst Monitor (GBM) began normal operations on July 14, about a month after launch, when the trigger algorithms were enabled. Since then, and against all odds, GBM recorded over 600 bursts from 4 SGRs. Of these four sources, only one was an old magnetar: SGR J1806+20. SGR J0501+4516, was discovered with Swift and extensively monitored with GBM. A source originally classified as AXP 1E1547.0-5408 exhibited SGR-like bursting behavior and we reclassified it as SGR J1550-5418. Finally, GBM discovered SGR J0418+5729 on 2009 June. Finally, on March 2010, a third new magnetar was discovered with Swift, SGR J1833-0832. I report below on the current status of the field and on several results combining multi-satellite and ground-based data

  16. Vibrational lifetime and Fermi resonance in polyatomic molecules

    NASA Astrophysics Data System (ADS)

    Fendt, A.; Fischer, S. F.; Kaiser, W.

    1981-05-01

    The energy decay of CH-stretching modes of the molecules CHCl 3 ,CH 2Cl 2, CH 3COCH 3, CH 3OH, and CH 3CH 2OH is measured in the liquid state. The observed lifetime very between 1.5 and 65 ps. A theoretical analysis points to the importance of Fermi resonance in the vibrational relaxation process. Quantitative comparison between theory and experiments is presented for the individual molecules. The strong variation of the lifetime for CH-stretching modes of various molecules may be understood if several effects are taken into account. First and most important is the influence of the Fermi resonances. Without the anharmonic mixing of the initial state, the overtone of the CH-bending modes and/or a higher order combination tone, one would predict lifetimes which are more than an order of magnitude longer than the observed lifetimes. This effect has been discussed earlier in detail for methylhalides by Zygan-Maus and Fischer [11] and, more recently, it has been incorporated in elaborate discussions for triatomic molecules like CO 2 by several authors [12]. A second factor to be considered for the interpretation is the rapi energy redistribution between different CH-stretching states was found theoretically to be faster than the further decay process by an order of magnitude [6, 11]. Experimentally, this effect was verified in this note for CH 2Cl 2 by the observation that the decay time was the same regardl whether the symmetric or the asymmetric CH-stretching mode was excited. This effect leads to a lengthening of the observed decay process. There is a bottleneck effect. Finally, we have shown that location and width of the final state are important parameters for the interpretation of the depopulatio lifetime. The empirical determination of these effects is not free of uncertainties. Very strong Fermi resonance can lead to rapid energy exchange during the exc process. In this case there is no bottleneck effect and it is difficult to detect the pathway of the energy

  17. Two-dimensional Fermi surfaces in Kondo insulator SmB₆.

    PubMed

    Li, G; Xiang, Z; Yu, F; Asaba, T; Lawson, B; Cai, P; Tinsman, C; Berkley, A; Wolgast, S; Eo, Y S; Kim, Dae-Jeong; Kurdak, C; Allen, J W; Sun, K; Chen, X H; Wang, Y Y; Fisk, Z; Li, Lu

    2014-12-01

    In the Kondo insulator samarium hexaboride (SmB6), strong correlation and band hybridization lead to an insulating gap and a diverging resistance at low temperature. The resistance divergence ends at about 3 kelvin, a behavior that may arise from surface conductance. We used torque magnetometry to resolve the Fermi surface topology in this material. The observed oscillation patterns reveal two Fermi surfaces on the (100) surface plane and one Fermi surface on the (101) surface plane. The measured Fermi surface cross sections scale as the inverse cosine function of the magnetic field tilt angles, which demonstrates the two-dimensional nature of the conducting electronic states of SmB6. PMID:25477456

  18. Temperature dependence of phase behavior for ternary systems composed of ionic liquid + sucrose + water.

    PubMed

    Wu, Bo; Zhang, Yumei; Wang, Huaping; Yang, Lingling

    2008-10-16

    In this work, temperature dependence of phase behaviors for the [Bmim]BF 4 + sucrose + water system was investigated. It was found that interaction of [Bmim]BF 4 with sucrose is exothermic, and lowering temperature is favorable for phase separation. In addition, a "[Bmim] (+)-induced structural changes" model was developed and used to interpret the temperature effect, whereby the salting-out effect was thought to be an entropy driving process through analysis of the structural interaction and the electrostatic interaction. PMID:18808091

  19. Floating liquid bridge tensile behavior: Electric-field-induced Young's modulus measurements

    NASA Astrophysics Data System (ADS)

    Teschke, Omar; Mendez Soares, David; Valente Filho, Juracyr Ferraz

    2013-12-01

    A floating bridge is formed spontaneously when high voltage is applied to polar fluids in two capillary tubes that were in contact and then separated. This bridge bends under its own weight, and its bending profile was used to calculate its Young's modulus. For electric field intensities of ˜106 V/m, water bridges exhibit viscoelastic behavior, with Young's moduli of ˜24 MPa; dimethylsulfoxide (DMSO) bridges exhibited Young's moduli of ˜60 kPa. The scheme devised to measure the voltage drop across the water bridge for high voltages applied between the electrodes shows that the bulk water resistance decreases with increasing voltage.

  20. End Groups of Functionalized Siloxane Oligomers Direct Block-Copolymeric or Liquid-Crystalline Self-Assembly Behavior.

    PubMed

    Zha, R Helen; de Waal, Bas F M; Lutz, Martin; Teunissen, Abraham J P; Meijer, E W

    2016-05-01

    Monodisperse oligodimethylsiloxanes end-functionalized with the hydrogen-bonding ureidopyrimidinone (UPy) motif undergo phase separation between their aromatic end groups and dimethylsiloxane midblocks to form ordered nanostructures with domain spacings of <5 nm. The self-assembly behavior of these well-defined oligomers resembles that of high degree of polymerization (N)-high block interaction parameter (χ) linear diblock copolymers despite their small size. Specifically, the phase morphology varies from lamellar to hexagonal to body-centered cubic with increasing asymmetry in molecular volume fraction. Mixing molecules with different molecular weights to give dispersity >1.13 results in disorder, showing importance of molecular monodispersity for ultrasmall ordered phase separation. In contrast, oligodimethylsiloxanes end-functionalized with an O-benzylated UPy derivative self-assemble into lamellar nanostructures regardless of volume fraction because of the strong preference of the end groups to aggregate in a planar geometry. Thus, these molecules display more classically liquid-crystalline self-assembly behavior where the lamellar bilayer thickness is determined by the siloxane midblock. Here the lamellar nanostructure is tolerant to molecular polydispersity. We show the importance of end groups in high χ-low N block molecules, where block-copolymer-like self-assembly in our UPy-functionalized oligodimethylsiloxanes relies upon the dominance of phase separation effects over directional end group aggregation. PMID:27054381

  1. Effect of water on the local structure and phase behavior of imidazolium-based protic ionic liquids.

    PubMed

    Yaghini, Negin; Pitawala, Jagath; Matic, Aleksandar; Martinelli, Anna

    2015-01-29

    We report on the effect of water on local structure and phase behavior of two protic ionic liquids, C2HImTFSI and C2HImTfO. Raman and infrared spectroscopy are employed to investigate the local coordination state. We find that water interacts weakly with TFSI(-) while more specifically with TfO(-) through the -SO3 group. Additionally, we observe that upon addition of water the -NH stretching frequency does not change in C2HImTFSI, while it red-shifts in C2HImTfO, indicative of different hydrogen bonding configurations. Supported by the appearance of some additional features in the 800-1000 cm(-1) frequency range where ring out-of-plane bending (γ) modes are found, we hypothesize that in C2HImTFSI water interacts only with the cation coordinating to the ring C(2)H and the N(3)H sites, while it interacts with both cation and anion in C2HImTfO forming hydrogen bonds that involve the cationic N-H site as well as the anionic -SO3 group. These different local structures also reflect in the phase behavior investigated by DSC, which reveals a more homogeneous solution when water is added to C2HImTfO, as compared to H2O/C2HImTFSI mixtures. Finally we report that the addition of water also significantly affects both Tm and Tg. PMID:25548901

  2. Anomalous behavior in the crossover between the negative and positive biaxial nematic mesophases in a lyotropic liquid crystal.

    PubMed

    Akpinar, Erol; Reis, Dennys; Figueiredo Neto, Antonio M

    2014-05-19

    A novel quaternary lyotropic liquid-crystalline mixture of dodecyltrimethylammonium bromide (DDTMABr)/sodium bromide/1-dodecanol/water, presenting the biaxial nematic phase (NB ) in addition to two uniaxial discotic (ND) and calamitic (NC) nematic ones, was synthesized. The partial phase diagram of this new mixture was constructed as a function of the DDTMABr molar-fraction concentration. The phase transitions from uniaxial to biaxial nematic phases were studied by means of the temperature dependence of the optical birefringence. In a particular region of the phase diagram, anomalous behavior was observed in the crossover from N-B to N+b: the contrast of the conoscopic fringes, which allows the birefringence measurements, almost vanishes, and the sample loses its alignment. This behavior, which was not observed before in lyotropics, was interpreted as a decrease in the mean diamagnetic susceptibility anisotropy (Δχ) of the sample, which was related to the shape anisotropy of the micelles. Small-angle X-ray scattering measurements were performed to evaluate the micellar shape anisotropy; these revealed that this mixture presented a smaller shape anisotropy than those of other lyotropic micellar systems presenting the NB phase. PMID:24692308

  3. End Groups of Functionalized Siloxane Oligomers Direct Block-Copolymeric or Liquid-Crystalline Self-Assembly Behavior

    PubMed Central

    2016-01-01

    Monodisperse oligodimethylsiloxanes end-functionalized with the hydrogen-bonding ureidopyrimidinone (UPy) motif undergo phase separation between their aromatic end groups and dimethylsiloxane midblocks to form ordered nanostructures with domain spacings of <5 nm. The self-assembly behavior of these well-defined oligomers resembles that of high degree of polymerization (N)–high block interaction parameter (χ) linear diblock copolymers despite their small size. Specifically, the phase morphology varies from lamellar to hexagonal to body-centered cubic with increasing asymmetry in molecular volume fraction. Mixing molecules with different molecular weights to give dispersity >1.13 results in disorder, showing importance of molecular monodispersity for ultrasmall ordered phase separation. In contrast, oligodimethylsiloxanes end-functionalized with an O-benzylated UPy derivative self-assemble into lamellar nanostructures regardless of volume fraction because of the strong preference of the end groups to aggregate in a planar geometry. Thus, these molecules display more classically liquid-crystalline self-assembly behavior where the lamellar bilayer thickness is determined by the siloxane midblock. Here the lamellar nanostructure is tolerant to molecular polydispersity. We show the importance of end groups in high χ–low N block molecules, where block-copolymer-like self-assembly in our UPy-functionalized oligodimethylsiloxanes relies upon the dominance of phase separation effects over directional end group aggregation. PMID:27054381

  4. Phase behavior and microstructure of microemulsions with a room-temperature ionic liquid as the polar phase.

    PubMed

    Atkin, Rob; Warr, Gregory G

    2007-08-01

    Microemulsions of nonionic alkyl oligoethyleneoxide (CiEj) surfactants, alkanes, and ethylammonium nitrate (EAN), a room-temperature ionic liquid, have been prepared and characterized. Studies of phase behavior reveal that EAN microemulsions have many features in common with corresponding aqueous systems, the primary difference being that higher surfactant concentrations and longer surfactant tailgroups are required to offset the decreased solvophobicity the surfactant molecules in EAN compared with water. The response of the EAN microemulsions to variation in the length of the alkane, surfactant headgroup, and surfactant tailgroup has been found to parallel that observed in aqueous systems in most instances. EAN microemulsions exhibit a single broad small-angle X-ray scattering peak, like aqueous systems. These are well described by the Teubner-Strey model. A lamellar phase was also observed for surfactants with longer tails at lower temperatures. The scattering peaks of both microemulsion and lamellar phases move to lower wave vector on increasing temperature. This is ascribed to a decrease in the interfacial area of the surfactant layer. Phase behavior, small-angle X-ray scattering, and conductivity experiments have allowed the weakly to strongly structured transition to be identified for EAN systems. PMID:17636975

  5. Modeling the Effects of Microencapsulation on the Electro-Optic Behavior of Polymer Cholesteric Liquid Crystal Flakes

    SciTech Connect

    Cox, G.P.; Marshall, K.L.; Lambropoulos, J.C.; Leitch, M.; Fromen, C.; Jacobs, S.D.

    2010-01-10

    A method for modeling the effect of microencapsulation on the electro-optical behavior of polymer cholesteric liquid crystal (PCLC) flakes suspended in a host fluid is introduced. Several microencapsulation configurations in an applied ac electric field are investigated using COMSOL MULTIPHYSICS software in combination with an analytical model. The field acting on the flakes is significantly altered as various encapsulant materials and boundary conditions are explored. The modeling predicts that test cells with multiple materials in the electric field path can have a wide range of electro-optic responses in ac electric fields. Both theoretical predictions and experimental evidence show that for PCLC flake reorientation to occur due to Maxwell–Wagner polarization, a reasonably strong electric field must be present along with at least moderately dissimilar PCLC flake and host fluid material dielectric constants and conductivities. For materials with low dielectric constants, electrophoretic behavior is observed under dc drive conditions at high field strengths for all evaluated microencapsulation configurations. This modeling method is shown to be a useful predictive tool for developing switchable particle devices that use microencapsulated dielectric particles in a host fluid medium.

  6. Presmectic wetting and supercritical-like phase behavior of octylcyanobiphenyl liquid crystal confined to controlled-pore glass matrices

    NASA Astrophysics Data System (ADS)

    Kralj, Samo; Cordoyiannis, George; Zidanšek, Aleksander; Lahajnar, Gojmir; Amenitsch, Heinz; Žumer, Slobodan; Kutnjak, Zdravko

    2007-10-01

    The influence of controlled-pore glass (CPG) confinement on the phase behavior of octylcyanobiphenyl liquid crystal (LC) is studied by means of x-ray scattering and high precision calorimetry. For CPG samples with pore diameter 2R>24nm, the smectic order parameter temperature dependence η(T ) reveals apparent presmectic ordering far above the bulk smectic A-nematic (SmA-N) phase transition for both nontreated and silane-treated CPG matrices. The behavior of η(T ) is qualitatively similar in all samples, well obeying the mean field approach (MFA) in which the surface wetting tendency plays the dominant role. In contrast, the critical fluctuations remain important in the specific heat data, which cannot be described within the MFA. We show experimentally that randomness and surface wetting become dominant over finite-size effects for 2R≲10nm, in agreement with theoretical analysis. In nontreated samples, the noncritical character of the static disorder and the interfacial LC-CPG coupling almost completely suppress the quasi-SmA-N and nematic-isotropic phase transitions at 2R˜15.1 and ˜7.5nm, respectively.

  7. Exploring the thermodynamics of a universal Fermi gas

    NASA Astrophysics Data System (ADS)

    Nascimbène, S.; Navon, N.; Jiang, K. J.; Chevy, F.; Salomon, C.

    2010-02-01

    One of the greatest challenges in modern physics is to understand the behaviour of an ensemble of strongly interacting particles. A class of quantum many-body systems (such as neutron star matter and cold Fermi gases) share the same universal thermodynamic properties when interactions reach the maximum effective value allowed by quantum mechanics, the so-called unitary limit. This makes it possible in principle to simulate some astrophysical phenomena inside the highly controlled environment of an atomic physics laboratory. Previous work on the thermodynamics of a two-component Fermi gas led to thermodynamic quantities averaged over the trap, making comparisons with many-body theories developed for uniform gases difficult. Here we develop a general experimental method that yields the equation of state of a uniform gas, as well as enabling a detailed comparison with existing theories. The precision of our equation of state leads to new physical insights into the unitary gas. For the unpolarized gas, we show that the low-temperature thermodynamics of the strongly interacting normal phase is well described by Fermi liquid theory, and we localize the superfluid transition. For a spin-polarized system, our equation of state at zero temperature has a 2 per cent accuracy and extends work on the phase diagram to a new regime of precision. We show in particular that, despite strong interactions, the normal phase behaves as a mixture of two ideal gases: a Fermi gas of bare majority atoms and a non-interacting gas of dressed quasi-particles, the fermionic polarons.

  8. Modulation of phase behaviors and charge carrier mobilities by linkage length in discotic liquid crystal dimers.

    PubMed

    Wang, Yi-Fei; Zhang, Chun-Xiu; Wu, Hao; Zhang, Ao; Wang, Jian-Chuang; Zhang, Shuai-Feng; Pu, Jia-Ling

    2015-01-28

    A clear structure-property relationship was revealed in a series of triphenylene-based dimers, which contained two triphenylene nuclei each bearing five β-OC4H9 substituents and are linked through a flexible O(CH2)nO polymethylene chain (n=6-12). Dimers with the linkage close to twice the length of the free side chains (n=8, 9) exhibited a single Colhp phase, while others with the linkage shorter (n=6, 7) or longer (n=10, 11, 12) showed multiphase behaviors with a transition from the Colhp phase to Colh phase; hole mobilities of Colhp phases reached 1.4×10(-2) cm2 V(-1) s(-1) in the dimer for which the linkage is exactly twice the length of the free side chains (n=8), and decreased regularly both with linkage length becoming shorter or longer. This modulation of phase behaviors and charge carrier mobilities was demonstrated to be generated by various steric perturbations introduced by linkages with different lengths, which result in different degrees of lateral fluctuations of discotic moieties in the columns. PMID:25467212

  9. Dynamic Study of Liquid Drop Impact on Supercooled Cerium Dioxide: Anti-Icing Behavior.

    PubMed

    Fu, Sin-Pui; Sahu, Rakesh P; Diaz, Estefan; Robles, Jaqueline Rojas; Chen, Chen; Rui, Xue; Klie, Robert F; Yarin, Alexander L; Abiade, Jeremiah T

    2016-06-21

    This work deals with the anti-icing behavior at subfreezing temperatures of CeO2/polyurethane nanocomposite coatings with and without a stearic acid treatment on aluminum alloy substrates. The samples ranged from superhydrophilic to superhydrophobic depending on surface morphology and surface functionalization. X-ray photoelectron spectroscopy was used to determine the surface composition. The anti-icing behavior was studied both by importing fog into a chamber with controlled atmosphere at subzero temperatures and by conducting experiments with drop impact velocities of 1.98, 2.8, 3.83, and 4.95 m/s. It was found that the ice-phobicity of the ceramic/polymer nanocomposite coating was dependent on the surface roughness and surface energy. Water drops were observed to completely rebound from the surface at subfreezing temperatures from superhydrophobic surfaces with small contact angle hysteresis regardless of the impact velocity, thus revealing the anti-icing capability of such surfaces. PMID:27166506

  10. Thermohydraulic behavior of the liquid metal target of a spallation neutron source

    SciTech Connect

    Takeda, Y.

    1996-06-01

    The author presents work done on three main problems. (1) Natural circulation in double coaxial cylindircal container: The thermohydraulic behaviour of the liquid metal target of the spallation neutron source at PSI has been investigated. The configuration is a natural-circulation loop in a concentric double-tube-type container. The results show that the natural-circulation loop concept is valid for the design phase of the target construction, and the current specified design criteria will be fulfilled with the proposed parameter values. (2) Flow around the window: Water experiments were performed for geometry optimisation of the window shape of the SINQ container for avoiding generating recirculation zones at peripheral area and the optimal cooling of the central part of the beam entrance window. Flow visualisation technique was mainly used for various window shapes, gap distance between the window and the guide tube edge. (3) Flow in window cooling channels: Flows in narrow gaps of cooling channels of two different types of windows were studied by flow visualisation techniques. One type is a slightly curved round cooling channel and the other is hemispherical shape, both of which have only 2 mm gap distance and the water inlet is located on one side and flows out from the opposite side. In both cases, the central part of the flow area has lower velocity than peripheral area.

  11. The behavior of a liquid drop levitated and drastically flattened by an intense sound field

    NASA Technical Reports Server (NTRS)

    Lee, C. P.; Anilkumar, A. V.; Wang, Taylor G.

    1992-01-01

    The deformation and break-up are studied of a liquid drop in levitation through the radiation pressure. Using high-speed photography ripples are observed on the central membrane of the drop, atomization of the membrane by emission of satellite drops from its unstable ripples, and shattering of the drop after upward buckling like an umbrella, or after horizontal expansion like a sheet. These effects are captured on video. The ripples are theorized to be capillary waves generated by the Faraday instability excited by the sound vibration. Atomization occurs whenever the membrane becomes so thin that the vibration is sufficiently intense. The vibration leads to a destabilizing Bernoulli correction in the static pressure. Buckling occurs when an existent equilibrium is unstable to a radial (i.e., tangential) motion of the membrane because of the Bernoulli effect. Besides, the radiation stress at the rim of the drop is a suction stress which can make equilibrium impossible, leading to the horizontal expansion and the subsequent break-up.

  12. Phase Behavior and Conductivity of Phosphonated Block Copolymers Containing Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Jung, Ha Young; Kim, Sung Yeon; Park, Moon Jeong

    2015-03-01

    As the focus on proton exchange fuel cells continues to escalate in the era of alternative energy systems, the rational design of sulfonated polymers has emerged as a key technique for enhancing device efficiency. While the sulfonic acid group guarantees high proton conductivity of membranes under humidified conditions, the growing need for high temperature operation has discouraged their practical uses in fuel cells. In this respect, phosphonated polymers have drawn intensive attention in recent years owing to their self-dissociation ability. In this study, we have synthesized a set of phosphonated block copolymers, poly(styrenephosphonate-methylbutylene) (PSP- b - PMB), by varying phosphonation level (PL). A wide variety of self-assembled morphologies, i.e., disordered, lamellar, hexagonally perforated lamellae and hexagonally packed cylindrical phases, were observed with PL. Remarkably, upon comparing the morphology of PSP- b-PMB and that of sulfonated analog, we found distinctly dissimilar domain sizes at the same molecular weight and composition. A range of ionic liquids (ILs) were incorporated into the PSP- b-PMB block copolymers and their ion transport properties were examined. It has been revealed that the degree of confinement of ionic phases (domain size) impacts the ion mobility and proton dissociation efficiency of IL-containing polymers.

  13. Surfactant behavior of ionic liquids involving a drug: from molecular interactions to self-assembly.

    PubMed

    Tourné-Péteilh, Corine; Coasne, Benoit; In, Martin; Brevet, David; Devoisselle, Jean-Marie; Vioux, André; Viau, Lydie

    2014-02-11

    Aggregates formed in an aqueous medium by three ionic liquids CnMImIbu made up of 1-alkyl-3-methyl-imidazolium cation (n = 4, 6, 8) and ibuprofenate anion are investigated. Dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryo-TEM), (1)H nuclear magnetic resonance measurements, and atom-scale molecular dynamics simulations are used to shed light on the main interactions governing the formation of the aggregates and their composition. At high concentration, mixed micelles are formed with a composition that depends on the imidazolium alkyl chain length. For the shortest alkyl chain, micelles are mainly composed of ibuprofenate anions with some imidazolium cations intercalated between the anions. Upon increasing the alkyl chain length, the composition of the aggregates gets enriched in imidazolium cations and aggregates of stoichiometric composition are obtained. Attractive interactions between these aggregates led to the formation of larger aggregates. As suggested by molecular simulations, these larger aggregates might constitute the early stage of phase separation. Transitions from micelles to vesicles or ribbons are observed due to dilution effects and changes in the chemical composition of the aggregates. We also show that aggregation can be probed using simple microscopic quantities such as radial distribution functions and average solvation numbers. PMID:24437472

  14. Theoretical studies on CO2 capture behavior of quaternary ammonium-based polymeric ionic liquids.

    PubMed

    Wang, Tao; Ge, Kun; Chen, Kexian; Hou, Chenglong; Fang, Mengxiang

    2016-05-14

    Quaternary ammonium-based polymeric ionic liquids (PILs) are novel CO2 sorbents as they have high capacity, high stability and high binding energy. Moreover, the binding energy of ionic pairs to CO2 is tunable by changing the hydration state so that the sorbent can be regenerated through humidity adjustment. In this study, theoretical calculations were conducted to reveal the mechanism of the humidity swing CO2 adsorption, based on model compounds of quaternary ammonium cation and carbonate anions. The electrostatic potential map demonstrates the anion, rather than the cation, is chemically preferential for CO2 adsorption. Further, the proton transfer process from water to carbonate at the sorbent interface is successfully depicted with an intermediate which has a higher energy state. By determining the CO2 adsorption energy and activation energy at different hydration states, it is discovered that water could promote CO2 adsorption by reducing the energy barrier of proton transfer. The adsorption/desorption equilibrium would shift to desorption by adding water, which constitutes the theoretical basis for humidity swing. By analyzing the hydrogen bonding and structure of the water molecules, it is interesting to find that the CO2 adsorption weakens the hydrophilicity of the sorbent and results in release of water. The requirement of latent heat for the phase change of water could significantly reduce the heat of adsorption. The special "self-cooling" effect during gas adsorption can lower the temperature of the sorbent and benefit the adsorption isotherms. PMID:27115032

  15. Patterning behavior of gravitationally modulated supercritical Marangoni flow in liquid layers

    NASA Astrophysics Data System (ADS)

    Lappa, Marcello

    2016-05-01

    The objective of the present analysis is the investigation of hybrid convection induced by the joint influence of imposed vibrations (g-jitters) of desired amplitude and frequency and surface-tension-induced forces in a nonisothermal liquid layer. This study may be regarded as the natural extension of an earlier work [V. M. Shevtsova, I. Nepomnyashchy, and J. C. Legros, Phys. Rev. E 67, 066308 (2003), 10.1103/PhysRevE.67.066308], where the focus was on convection driven by interacting thermocapillarity and steady gravity. As in that work, conditions are considered for which the unperturbed (vibrationless) Marangoni flow would be characterized by the emergence and propagation of a classical hydrothermal wave, namely, a supercritical thermofluidynamic disturbance propagating continuously in the upstream direction. A number of numerical results are analyzed and discussed. Regimes of quasistationary rolls, standing waves, traveling waves, and modulated (pulsotraveling) disturbances are identified in the considered space of parameters. Most interestingly, it is observed that traveling waves can reverse their direction of propagation in some specific regions of the phase space.

  16. Tuning Lyotropic Liquid Crystalline Phase Behavior of Gemini Surfactants by Linker Parity

    NASA Astrophysics Data System (ADS)

    Perroni, Dominic; Baez-Cotto, Carlos; Mantha, Sriteja; Sorenson, Gregory; Yethiraj, Arun; Mahanthappa, Mahesh

    2015-03-01

    Aqueous bicontinuous lyotropic liquid crystals (LLCs) derived from small molecule surfactants are useful nanostructured materials with myriad applications, in fields ranging from structural biology to membrane science. However, access to these coveted phases is limited by the fact that few surfactant platforms readily stabilize these network phases over the wide amphiphile concentration and temperature phase windows necessary for their widespread applications. We have recently shown that gemini (``twin tail'') dicarboxylate surfactants, comprising two single tail amphiphiles covalently linked near the headgroup by a hydrophobic bridge, exhibit a greatly increased propensity to form stable double gyroid LLC phases. In this presentation, we will demonstrate the unusual sensitivity of gemini dicarboxylate surfactant lyotropic self-assembly to the length of the hydrophobic bridge: odd-carbon linkers produce stable double gyroid phases over amphiphile composition windows as wide as 40 wt% that are stable between T = 22-100 °C. We rationalize these results in terms of the detailed molecular conformations of the surfactants that stem from the length of the bridging moiety, which suggests that this molecular design strategy may generally extend to other surfactant classes.

  17. Spin-liquid behavior and weak static magnetism in pyrochlore Pr2Ir2O7

    SciTech Connect

    Heffner, R H; Maclaughlin, D E; Nakatsuji, S; Machida, Y

    2008-01-01

    Muon spin relaxation experiments have been performed in powder samples of the pyrochlore iridate Pr{sub 2}Ir{sub 2}O{sub 7} for temperatures in the range 0.02-250 K. Two-component muon spin relaxation functions are observed up to {approx}> 150 K, indicating static magnetism with a freezing temperature T{sub f} of this value or higher. The static muon spin relaxation rate {Delta}. suggests weak-moment freezing ({approx} 10{sup -1} {micro}{sub B} at T = 0), probably due to Ir{sup 4+} spin ordering as in isostructural Y{sub 2}Ir{sub 2}O{sub 7}. The temperature dependence of {Delta} is highly unusual, decreasing smoothly by orders of magnitude but remaining nonzero for T < T{sub f}. The smoothness of {Delta}(T) suggests that Pr{sup 3+} moments do not order down to 0.025 K. The dynamic relaxation rate {Lambda} increases markedly below {approx}20 K, indicating a shift of spin fluctuation noise power to low frequencies in the spin-liquid state. At low temperatures {Lambda} is strong and temperature-independent, indicative of numerous low-lying spin excitations as is common in frustrated antiferromagnets.

  18. Retention behavior of alkyl-substituted polycyclic aromatic sulfur heterocycles in reversed-phase liquid chromatography.

    PubMed

    Wilson, Walter B; Sander, Lane C; de Alda, Miren Lopez; Lee, Milton L; Wise, Stephen A

    2016-08-26

    Retention indices for 79 alkyl-substituted polycyclic aromatic sulfur heterocycles (PASHs) were determined by using reversed-phase liquid chromatography (LC) on a monomeric and polymeric octadecylsilane (C18) stationary phase. Molecular shape parameters [length, breadth, thickness (T), and length-to-breadth ratio (L/B)] were calculated for all the compounds studied. Based on separations of isomeric methylated polycyclic aromatic hydrocarbons on polymeric C18 phases, alkyl-substituted PASHs are expected to elute based on increasing L/B ratios. However, the correlation coefficients had a wide range of values from r=0.43 to r=0.93. Several structural features besides L/B ratios were identified to play an important role in the separation mechanism of PASHs on polymeric C18 phases. First, the location of the sulfur atom in a bay-like-region results in alkylated-PASHs being more retentive than non-bay-like-region alkylated-PASHs, and they elute later than expected based on L/B value. Second, the placement of the alkyl group in the k region of the structure resulted in a later elution than predicted by L/B. Third, highly nonplanar methyl-PASHs (i.e., 1-Me and 11-MeBbN12T) elute prior to the parent PASH (BbN12T). PMID:27477517

  19. Patterning behavior of gravitationally modulated supercritical Marangoni flow in liquid layers.

    PubMed

    Lappa, Marcello

    2016-05-01

    The objective of the present analysis is the investigation of hybrid convection induced by the joint influence of imposed vibrations (g-jitters) of desired amplitude and frequency and surface-tension-induced forces in a nonisothermal liquid layer. This study may be regarded as the natural extension of an earlier work [V. M. Shevtsova, I. Nepomnyashchy, and J. C. Legros, Phys. Rev. E 67, 066308 (2003)10.1103/PhysRevE.67.066308], where the focus was on convection driven by interacting thermocapillarity and steady gravity. As in that work, conditions are considered for which the unperturbed (vibrationless) Marangoni flow would be characterized by the emergence and propagation of a classical hydrothermal wave, namely, a supercritical thermofluidynamic disturbance propagating continuously in the upstream direction. A number of numerical results are analyzed and discussed. Regimes of quasistationary rolls, standing waves, traveling waves, and modulated (pulsotraveling) disturbances are identified in the considered space of parameters. Most interestingly, it is observed that traveling waves can reverse their direction of propagation in some specific regions of the phase space. PMID:27300978

  20. Retention behavior of isomeric polycyclic aromatic sulfur heterocycles in reversed-phase liquid chromatography.

    PubMed

    Wilson, Walter B; Sander, Lane C; de Alda, Miren Lopez; Lee, Milton L; Wise, Stephen A

    2016-08-26

    Retention indices for 70 polycyclic aromatic sulfur heterocycles (PASHs) were determined using reversed-phase liquid chromatography (LC) on a monomeric and a polymeric C18 stationary phase. Molecular shape parameters [length, breadth, thickness (T), and length-to-breadth ratio (L/B)] were calculated for all the compounds studied. Correlations between the retention on the polymeric C18 phase and PASH geometry (L/B and T) were investigated for six specific PASH isomer groups with molecular mass (MM) 184Da, 234Da, 258Da, 284Da, 334Da, and 384Da. Similar to previous studies for polycyclic aromatic hydrocarbons (PAHs), PASH elution order on the polymeric C18 phase was generally found to follow increasing L/B values. Correlation coefficients for retention vs L/B ranged from r=0.45 (MM 184Da) to r=0.89 (MM 284Da). In the case of smaller PASHs (MM≤258Da), the location of the sulfur atom in the bay-region of the structure resulted in later than expected elution of these isomers based on L/B. In the case of the larger PASHs (MM≥284Da), nonplanarity had a significant influence on earlier than predicted elution based on L/B values. PMID:27481401

  1. Tribological behavior of liquid metallurgy-processed AA 6061-B4C composites

    NASA Astrophysics Data System (ADS)

    Monikandan, V. V.; Joseph, M. A.; Rajendrakumar, P. K.; Sreejith, M.

    2015-01-01

    Aluminum metal matrix composites (AMMCs) possess improved properties compared to their monolithic counterparts and serve as a reliable alternative to replace them for applications that are considered as their niche. In the present investigation, 6061 Al alloy-10 wt% B4C composite is fabricated through liquid metallurgy stir casting technique and analyzed for its tribological characteristics. The uniform distribution of B4C reinforcement particles in the composite is achieved by the above route and is characterized using microstructure analysis and x-ray diffraction spectrum. The dry wear tests have been conducted under ambient conditions using a pin-on-disc tribometer. The worn surface and debris of the composite are also characterized using a scanning electron microscope (SEM) and energy-dispersive x-ray spectroscopy (EDS). It is found that the combination of adhesion, delamination and abrasion constitute the predominant wear mechanism and this is influenced by the B4C particles, applied load, sliding distance and speed. The wear and friction coefficient increase with increase in applied load for all the load conditions studied. While the sliding speed fosters the engendering of a mechanically mixed layer (MML) to reduce the wear and friction coefficient, in contrast, the increase in sliding distance scuttles the MML formation owing to abrasion induced by the hard B4C particles.

  2. Demonstration of an Electrochemical Liquid Cell for Operando Transmission Electron Microscopy Observation of the Lithiation/Delithiation Behavior of Si Nanowire Battery Anodes

    SciTech Connect

    Gu, Meng; Parent, Lucas R.; Mehdi, Beata L.; Unocic, Raymond R.; McDowell, Matthew T.; Sacci, Robert L.; Xu, Wu; Connell, Justin G.; Xu, Pinghong; Abellan Baeza, Patricia; Chen, Xilin; Zhang, Yaohui; Perea, Daniel E.; Evans, James E.; Lauhon, Lincoln; Zhang, Jiguang; Liu, Jun; Browning, Nigel D.; Cui, Yi; Arslan, Ilke; Wang, Chong M.

    2013-11-13

    Over the last few years, in-situ transmission electron microscopy (TEM) studies of lithium ion batteries using an open-cell configuration have helped us to gain fundamental insights into the structural and chemical evolution of the electrode materials in real time. In the standard open-cell configuration, the electrolyte is either solid lithium oxide or an ionic liquid, which is point-contacted with the electrode. This cell design is inherently different from a real battery, where liquid electrolyte forms conformal contact with electrode materials. The knowledge learnt from open cells can deviate significantly from the real battery, calling for operando TEM technique with conformal liquid electrolyte contact. In this paper, we developed an operando TEM electrochemical liquid cell to meet this need, providing the configuration of a real battery and in a relevant liquid electrolyte. To demonstrate this novel technique, we studied the lithiation/delithiation behavior of single Si nanowires. Some of lithiation/delithation behaviors of Si obtained using the liquid-cell are consistent with the results from the open-cell studies. However, we also discovered new insights different from the open cell configuration - the dynamics of the electrolyte and, potentially, a future quantitative characterization of the SEI layer formation and structural and chemical evolution.

  3. Wormlike micelles with photoresponsive viscoelastic behavior formed by surface active ionic liquid/azobenzene derivative mixed solution.

    PubMed

    Bi, Yanhui; Wei, Hongtu; Hu, Qiongzheng; Xu, Wenwen; Gong, Yanjun; Yu, Li

    2015-04-01

    The UV-light-stimulated self-assembly behavior of a surface active ionic liquid (SAIL), 1-hexadecyl-3-methylimidazolium bromide (C16mimBr), with an azobenzene derivative, sodium azobenzene 4-carboxylate (AzoCOONa), was investigated in aqueous solution. The properties and structures of the aggregates, formed at a concentration ratio equal to 2:1 ([C16mimBr]:[AzoCOONa]), were comprehensively characterized by rheometer and cryogenic transmission electron microscopy. Initially, viscoelastic wormlike micelles with a viscosity of 0.65 Pa·s were constructed in the C16mimBr/AzoCOONa system. Upon irradiation by UV light (365 nm), particularly fascinating is that the wormlike micelles become much longer and more entangled, exhibiting a high viscosity of 6.9 Pa·s. This can be attributed to photoisomerization of the AzoCOONa molecule from trans to cis form. It is the first time that, with exposure to UV or visible light, the aggregate type of the photoresponsive system has remained unchanged, with only a change of internal property parameters. The cation-π interaction prevailing over the hydrophobic interaction and electrostatic interaction between C16mimBr and AzoCOONa molecules is supposed to be responsible for this peculiar phase behavior. The wormlike micelles constructed with the SAIL and photosensitive additive exhibit controllable viscoelastic behavior in the photoresponsive process. In addition, the average contour length of wormlike micelles was found to slightly decrease with the increase of temperature. We expect this system will receive particular attention due to its unique properties and potential applications in drug delivery, biochemistry, and materials science, etc. PMID:25763685

  4. Influence of Variations in Liquid-Crystalline Content upon the Self-Assembly Behavior of Siloxane-Based Block Copolymers

    SciTech Connect

    Verploegen,E.; Zhang, T.; Murlo, N.; Hammond, P.

    2008-01-01

    A series of well-defined smectic side chain liquid-crystalline (LC) block copolymers with a low glass transition (Tg) siloxane block has been synthesized via anionic polymerization; these systems consist of a glassy polystyrene block and a unique low glass transition temperature LC block based on poly(vinylmethylsiloxane) to which six different LCs have been synthesized and attached. The synthesis techniques used provide systematic control over covalent LC side chain content, allowing for a range of morphologies to be obtained from a single block copolymer backbone during a one-step LC attachment reaction. Variations in the LC structure and content significantly affect the morphology of the LC mesophase, allowing the smectic-to-isotropic transition temperature to be tuned from room temperature up to 150 C. There are two key driving forces in the self-assembly behavior of these materials that are significantly affected by the LC content. The first is the segmental interaction parameter (?) between the blocks, which is a function of the amount of LC attached to the siloxane block. The attachment percent of the LCs to the siloxane block determines the packing density, which affects the stability of the LC mesophase and its interactions with the inter-material dividing surface. The self-assembled morphologies are characterized as a function of LC content and the mechanisms for the observed behavior are detailed. Additional insights into the interactions between the LC and block copolymer mesophases are gained by investigating the morphologies in response to mechanical deformation. The elastic modulus of this system can be tailored over several orders of magnitude by controlling the LC content, and the thermo-mechanical behavior is also highly dependent. The ability to precisely control the degree of LC functionalization enables the custom design and tailoring of material properties for specific applications such as electro-mechanical, damping, and mechano

  5. An investigation into the flow behavior of a single phase gas system and a two phase gas/liquid system in normal gravity with nonuniform heating from above

    NASA Technical Reports Server (NTRS)

    Disimile, Peter J.; Heist, Timothy J.

    1990-01-01

    The fluid behavior in normal gravity of a single phase gas system and a two phase gas/liquid system in an enclosed circular cylinder heated suddenly and nonuniformly from above was investigated. Flow visualization was used to obtain qualitative data on both systems. The use of thermochromatic liquid crystal particles as liquid phase flow tracers was evaluated as a possible means of simultaneously gathering both flow pattern and temperature gradient data for the two phase system. The results of the flow visualization experiments performed on both systems can be used to gain a better understanding of the behavior of such systems in a reduced gravity environment and aid in the verification of a numerical model of the system.

  6. Photoluminescence behavior of riboflavin and lumiflavin in liquid solutions and solid films

    NASA Astrophysics Data System (ADS)

    Penzkofer, A.

    2012-05-01

    The absorption and emission behavior of riboflavin and lumiflavin in water, tetrahydrofuran (THF), water-starch, THF-polystyrene, starch films, and polystyrene films was studied at room temperature. Absorption cross-section spectra, fluorescence quantum distributions, and fluorescence quantum yields were determined. For the starch films additionally phosphorescence and delayed fluorescence spectra as well as phosphorescence lifetimes and delayed fluorescence lifetimes were measured and their quantum yields of intersystem-crossing, intrinsic triplet-based phosphorescence quantum yields, T1-S0 radiative lifetimes, and S0-T1 absorption strengths were calculated. A method of absolute intrinsic luminescence quantum distribution and quantum yield determination for dye doped films on transparent plates with a fluorimeter is described.

  7. Thermal behavior of nano cellulose doped polymer dispersed liquid crystal (PDLC)

    NASA Astrophysics Data System (ADS)

    Kashyap, Swati; Saxena, S. K.; Gupta, S. J.; Mahajan, Jyoti

    2016-05-01

    Nano cellulose or cellulose nanofibers (CNF) material is composed of Nano sized cellulose fibrils with a high aspect ratio and typical lateral dimensions are 20-50 nm. Its pseudo-plastic characteristics exhibit the property of certain gels or fluids (viscous) and over a period of time, becomes, Thixotropic. The ability of CNFs to go into a PDLC ultrasonically with a helical arrangement results in dried CNF films. The films thus acquire attractive thermal properties, creating possibilities for their use in various applications. In this presentation, we discuss the thermal behavior of Nano cellulose doped in PDLC that governs the formation of the desired helical structure. By comparison with the corresponding self-assembly processes of other rod-like nanoparticles, for example, carbon nanotubes particles, we outline in the present paper the variation in the number of mesogen phases in varying compositions of Nano Cellulose doped PDLCs.

  8. Optical klystron SASE at FERMI

    NASA Astrophysics Data System (ADS)

    Penco, G.; Allaria, E. M.; De Ninno, G.; Ferrari, E.; Giannessi, L.

    2015-05-01

    The optical klystron enhancement to a self-amplified spontaneous emission (SASE) free electron laser (FEL) has been deeply studied in theory and in simulations. In this FEL scheme, a relativistic electron beam passes through two undulators, separated by a dispersive section. The latter converts the electron-beam energy modulation produced in the first undulator in density modulation, thus enhancing the free-electron laser gain. We report the first experiment that has been carried out at the FERMI facility in Trieste, of enhancement to a SASE FEL by using the optical klystron scheme. XUV photons have been produced with an intensity several orders of magnitude larger than in pure SASE mode. The impact of the uncorrelated energy spread of the electron beam on the optical klystron SASE performance has been also investigated.

  9. Ionization and dissociation equilibria in liquid SO/sub 2/. 12. The behavior of tetrahedral ions

    SciTech Connect

    Lichtin, N.N.; Wasserman, B.; Clougherty, E.; Wasserman, J.; Reardon, J.F.

    1980-10-30

    Electrolytic conductance of their solutions in liquid sulfur dioxide over a wide range of concentrations was measured for the 21 ionophores, Me/sub 4/NCl, Me/sub 4/NClO/sub 4/, PhMe/sub 3/NBr, PhMe/sub 3/NCl, PhMe/sub 3/NI, Et/sub 4/NI, Pr/sub 4/NCl, Pr/sub 4/NBr, Pr/sub 4/NI, Bu/sub 4/NBr, Bu/sub 4/NI, Bu/sub 4/NPc, (i-Am)/sub 4/NBr, (i-Am)/sub 4/Ni, (i-Am)/sub 4/NB(i-Am)/sub 4/, (i-Am)/sub 3/NHBr, Hex/sub 4/NI, Ph/sub 4/AsC1, Ph/sub 4/AsI, Ph/sub 4/AsPc, and Ph/sub 4/PPc, at 273.15 K and other temperatures. Limiting equivalent conductances and dissociation constants were determined for these solutes by Shedlovsky's procedure. Utilizing the data of this and other investigations, we calculated thermodynamic quantities for the dissociation equilibria of many of the solutes. Values of Bjerrum's contact distance parameter, a, were calculated from the equilibrium data and compared to sums of estimated ionic radii. Limiting ionic conductances were evaluated by a Fuoss-Coplan division of the limiting equivalent conductance of (i-Am)/sub 4/NB(i-Am)/sub 4/. Stokes radii were calculated for the ions employed. The results of the measurements are interpreted in terms of ion-ion and ion-solvent interactions.

  10. Dynamic Behavior of Clobazam on High-Performance Liquid Chromatography Chiral Stationary Phases.

    PubMed

    Sabia, Rocchina; De Martino, Michela; Cavazzini, Alberto; Villani, Claudio

    2016-01-01

    Clobazam, a 1,5-benzodiazepin-2,4-dione, is a chiral molecule because its ground state conformation features a nonplanar seven-membered ring lacking reflection symmetry elements. The two conformational enantiomers of clobazam interconvert at room temperature by a simple ring-flipping process. Variable temperature HPLC on the Pirkle type (R)-N-(3,5-dinitronenzoyl)phenylglycine and (R,R)-Whelk-O1 chiral stationary phases (CSPs) allowed us to separate for the first time the conformational enantiomers of clobazam and to observe peak coalescence-decoalescence phenomena due to concomitant separation and interconversion processes occurring on the same time scale. Clobazam showed temperature dependent dynamic high-performance liquid chromatography (HPLC) profiles with interconversion plateaus on the two CSPs indicative of on-column enantiomer interconversion. (enantiomerization) in the column temperature range between Tcol = 10°C and Tcol = 30°C, whereas on-column interconversion was absent at temperature close to or lower than Tcol = 5°C. Computer simulation of exchange-deformed HPLC profiles using a program based on the stochastic model yielded the apparent rate constants for the on-column enantiomerization and the corresponding free energy activation barriers. At Tcol = 20°C the averaged enantiomerization barriers, ΔG(‡), for clobazam were found in the range 21.08-21.53 kcal mol(-1) on the two CSPs. The experimental dynamic chromatograms and the corresponding interconversion barriers reported in this article are consistent with the literature data measured by DNMR at higher temperatures and in different solvents. PMID:26477466

  11. Study of anchoring behavior of nematic fluids at the interface of polymer-dispersed liquid crystals

    NASA Astrophysics Data System (ADS)

    Zhou, Jian

    A liquid crystal (LC) at its boundary surface adopts a preferential alignment, which is referred to as anchoring. The direction of this alignment (i.e., anchoring direction) may be perpendicular, parallel or tilted with respect to the surface. Transitions from one anchoring condition to another may occur when the parameters (e.g., temperature) charactering the surface change, as referred to as anchoring transitions. In the LC-polymer composite systems under our study, the anchoring and temperature-driven anchoring transitions of nematic fluids is very sensitive to the structure of the side chain of poly (alkyl acrylate) matrixes that encapsulate the LC. We have shown that the anchoring transition temperature of these systems can be tuned far below the nematic-to-isotropic transition temperature, by varying either the length, branching structure of the side chains of homopolymers, or the composition of copolymer of two dissimilar monomers. Both sharp and broad anchoring transitions with respect to the temperature range over which a transition occurs were observed. It is postulated that microscopic interactions between the polymer side chains and LC molecules play an important role in determining the anchoring. In particular, the conformation of the polymer side chain is proposed to have important control over the anchoring. Anchoring strength and tilt angle as a function of temperature during the anchoring transitions were also experimentally investigated, which contribute to understanding of the microscopic mechanism for such transitions. Based on the LC-polymer composites with controlled anchoring, a LC display with reverse switching mode and a novel electrically switchable diffraction grating have been demonstrated. The advantages of these devices are ease of manufacturing, low operation voltage, and mechanical stability offered by polymer matrix. Moreover, a detailed study of the director configuration of wall defects found in these composite films was carried

  12. Terrestrial fate of coal-liquid constituents: behavior of alkyl anilines in soil

    SciTech Connect

    Felice, L.J.; Zachara, J.M.; Rogers, J.E.

    1982-07-01

    The low molecular weight aromatic amines (anilines) are important water soluble constituents of coal liquids. The impact of anilines released to the terrestrial environment will largely depend on their mobility and persistence. Studies were conducted to investigate those processes governing the mobility and persistence of the alkylanilines, namely, soil sorption and chemical/microbial degradation. Soil sorption measurements were conducted on aniline and several methyl substituted anilines on A and B horizons of a soil profile collected from Davies County, Kentucky. The magnitude of sorption was large in all horizons. Sorption in the B horizons was larger than in the A horizon for many of the anilines studied, indicating the importance of both the mineral matrix and organic carbon content of the soil in determining the magnitude of sorption. Results of these measurements indicate that movement of the anilines through the soil would be significantly attenuated by sorption reactions. Aniline sorption measurement in the A horizon after removal of the organic matter and in the B/sub 22/ horizon after removal of amorphous iron oxides and crystalline iron oxides indicate that organic matter largely controls aniline sorption in the A horizon, while crystalline iron oxides and phyllosilicates are important in the B horizons. The effects of pH on aniline sorption was also examined and shown to have significant effects on the magnitude of sorption in both A and B horizons. Soil degradation studies using /sup 14/C-3-methylaniline as a model for alkyl aniline degradation show that 3-methylaniline is readily metabolized by soil microorganisms during the 32-day period examined.

  13. Quench dynamics of a superfluid Fermi gas

    SciTech Connect

    Warner, G.L.; Leggett, A.J.

    2005-04-01

    With an eye toward the interpretation of so-called 'cosmological' experiments performed on the low-temperature phases of {sup 3}He, in which regions of the superfluid are destroyed by local heating with neutron radiation, we have studied the behavior of a Fermi gas subjected to uniform variations of an attractive BCS interaction parameter {lambda}. In {sup 3}He, the quenches induced by the rapid cooling of the 'hot spots' back through the transition may lead to the formation of vortex loops via the Kibble-Zurek mechanism. A consideration of the free energy available in the quenched region for the production of such vortices reveals that the Kibble-Zurek scaling law gives at best a lower bound on the defect spacing. Further, for quenches that fall far outside the Ginzburg-Landau regime, the dynamics on the pair subspace, as initiated by quantum fluctuations, tends irreversibly to a self-driven steady state with a gap {delta}{sub {infinity}}={epsilon}{sub C}(e{sup 2/N(0){lambda}}-1){sup -1/2}. In weak coupling, this is only half the BCS gap, the extra energy being taken up by the residual collective motion of the pairs.

  14. A singular thermodynamically consistent temperature at the origin of the anomalous behavior of liquid water

    PubMed Central

    Mallamace, Francesco; Corsaro, Carmelo; Stanley, H. Eugene

    2012-01-01

    The density maximum of water dominates the thermodynamics of the system under ambient conditions, is strongly P-dependent, and disappears at a crossover pressure Pcross ~ 1.8 kbar. We study this variable across a wide area of the T–P phase diagram. We consider old and new data of both the isothermal compressibility KT(T, P) and the coefficient of thermal expansion αP(T, P). We observe that KT(T) shows a minimum at T* ~ 315±5 K for all the studied pressures. We find the behavior of αP to also be surprising: all the αP(T) curves measured at different P cross at T*. The experimental data show a “singular and universal expansivity point” at T* ~ 315 K and αP(T*) ≃ 0.44 10−3 K−1. Unlike other water singularities, we find this temperature to be thermodynamically consistent in the relationship connecting the two response functions. PMID:23251779

  15. The extragalactic gamma-ray sky in the Fermi era

    NASA Astrophysics Data System (ADS)

    Massaro, Francesco; Thompson, David J.; Ferrara, Elizabeth C.

    2015-12-01

    The Universe is largely transparent to γ -rays in the GeV energy range, making these high-energy photons valuable for exploring energetic processes in the cosmos. After 7 years of operation, the Fermi Gamma-ray Space Telescope has produced a wealth of information about the high-energy sky. This review focuses on extragalactic γ -ray sources: what has been learned about the sources themselves and about how they can be used as cosmological probes. Active galactic nuclei (blazars, radio galaxies, Seyfert galaxies) and star-forming galaxies populate the extragalactic high-energy sky. Fermi observations have demonstrated that these powerful non-thermal sources display substantial diversity in energy spectra and temporal behavior. Coupled with contemporaneous multifrequency observations, the Fermi results are enabling detailed, time-dependent modeling of the energetic particle acceleration and interaction processes that produce the γ -rays, as well as providing indirect measurements of the extragalactic background light and intergalactic magnetic fields. Population studies of the γ -ray source classes compared to the extragalactic γ -ray background place constraints on some models of dark matter. Ongoing searches for the nature of the large number of γ -ray sources without obvious counterparts at other wavelengths remain an important challenge.

  16. Crow Instability in Unitary Fermi Gas

    NASA Astrophysics Data System (ADS)

    Gautam, Sandeep

    2013-06-01

    In this paper, we investigate the initiation and subsequent evolution of Crow instability in an inhomogeneous unitary Fermi gas using zero-temperature Galilei-invariant nonlinear Schrödinger equation. Considering a cigar-shaped unitary Fermi gas, we generate the vortex-antivortex pair either by phase-imprinting or by moving a Gaussian obstacle potential. We observe that the Crow instability in a unitary Fermi gas leads to the decay of the vortex-antivortex pair into multiple vortex rings and ultimately into sound waves.

  17. Quantum Mechanical Models Of The Fermi Shuttle

    SciTech Connect

    Sternberg, James

    2011-06-01

    The Fermi shuttle is a mechanism in which high energy electrons are produced in an atomic collision by multiple collisions with a target and a projectile atom. It is normally explained purely classically in terms of the electron's orbits prescribed in the collision. Common calculations to predict the Fermi shuttle use semi-classical methods, but these methods still rely on classical orbits. In reality such collisions belong to the realm of quantum mechanics, however. In this paper we discuss several purely quantum mechanical calculations which can produce the Fermi shuttle. Being quantum mechanical in nature, these calculations produce these features by wave interference, rather than by classical orbits.

  18. Retention behavior of lipids in reversed-phase ultrahigh-performance liquid chromatography-electrospray ionization mass spectrometry.

    PubMed

    Ovčačíková, Magdaléna; Lísa, Miroslav; Cífková, Eva; Holčapek, Michal

    2016-06-10

    Reversed-phase ultrahigh-performance liquid chromatography (RP-UHPLC) method using two 15cm sub-2μm particles octadecylsilica gel columns is developed with the goal to separate and unambiguously identify a large number of lipid species in biological samples. The identification is performed by the coupling with high-resolution tandem mass spectrometry (MS/MS) using quadrupole - time-of-flight (QTOF) instrument. Electrospray ionization (ESI) full scan and tandem mass spectra are measured in both polarity modes with the mass accuracy better than 5ppm, which provides a high confidence of lipid identification. Over 400 lipid species covering 14 polar and nonpolar lipid classes from 5 lipid categories are identified in total lipid extracts of human plasma, human urine and porcine brain. The general dependences of relative retention times on relative carbon number or relative double bond number are constructed and fit with the second degree polynomial regression. The regular retention patterns in homologous lipid series provide additional identification point for UHPLC/MS lipidomic analysis, which increases the confidence of lipid identification. The reprocessing of previously published data by our and other groups measured in the RP mode and ultrahigh-performance supercritical fluid chromatography on the silica column shows more generic applicability of the polynomial regression for the description of retention behavior and the prediction of retention times. The novelty of this work is the characterization of general trends in the retention behavior of lipids within logical series with constant fatty acyl length or double bond number, which may be used as an additional criterion to increase the confidence of lipid identification. PMID:27179677

  19. Investigation of the shear thinning behavior of epoxy resins for utilization in vibration assisted liquid composite molding processes

    NASA Astrophysics Data System (ADS)

    Meier, R.; Kirdar, C.; Rudolph, N.; Zaremba, S.; Drechsler, K.

    2014-05-01

    Efficient production and consumption of energy are of greatest importance for contemporary industries and their products. This has led to an increasing application of lightweight materials in general and of Carbon Fiber Reinforced Plastics (CFRP) in particular. However, broader application of CFRP is often limited by high costs and manual labor production processes. These constraints are addressed by Liquid Composite Molding (LCM) processes. In LCM a dry fibrous preform is placed into a cavity and infiltrated mostly by thermoset resins; epoxy resins are wide spread in CFRP applications. One crucial parameter for a fast mold filling is the viscosity of the resin, which is affected by the applied shear rates as well as temperature and curing time. The work presented focuses on the characterization of the shear thinning behavior of epoxy resins. Furthermore, the correlation with the conditions in vibration assisted LCM processes, where additional shear rates are created during manufacture, is discussed. Higher shear rates result from high frequencies and/or high amplitudes of the vibration motions which are created by a vibration engine mounted on the mold. In rheological investigations the shear thinning behavior of a representative epoxy resin is studied by means of rotational and oscillatory experiments. Moreover, possible effects of shear rates on the chemical curing reaction are studied. Here, the time for gelation is measured for different levels of shear rates in a pre-shearing phase. Based on the rheological studies, the beneficial effect of vibration assistance in LCM processes with respect to mold filling can further be predicted and utilized.

  20. Aggregation behavior of 1-dodecyl-3-methylimidazolium bromide in aqueous solution: effect of ionic liquids with aromatic anions.

    PubMed

    Gu, Yingqiu; Shi, Lijuan; Cheng, Xiyuan; Lu, Fei; Zheng, Liqiang

    2013-05-28

    The effects of ionic liquids (ILs), 1-butyl-3-methylimidazolium methylsulfonate (bmimMsa), 1-butyl-3-methylimidazolium benzenesulfonate (bmimBsa), and 1-butyl-3-methylimidazolium 2-naphthalenesulfonate (bmimNsa), on the aggregation behavior of 1-dodecyl-3-methylimidazolium bromide (C12mimBr) in aqueous solution were investigated by surface tension, dynamic light scattering measurements, and (1)H NMR spectroscopy. The ability to promote the surfactant aggregation is in the order bmimNsa > bmimBsa > bmimMsa. Nevertheless, only bmimNsa distinctly reduces both the CMC value and the surface tension at CMC. Due to the penetration of C10H7SO3(-)anions into the surfactant aggregate, bmimNsa is found to induce a phase transition from micelles to vesicles, whereas the other ILs only slightly increase the sizes of micelles. The combined effect of intermolecular interactions, such as hydrophobic effect, electrostatic attractions, and π-π stacking interactions, is supposed to be responsible for this structural transformation, in which π-π stacking plays an important role. PMID:23642150